What is the effect of Montelukast on the amount of IgE in blood?

What is the effect of Montelukast on the amount of IgE in blood?

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I know that it decreases the amount of leucotrienes in blood. I saw a patient with high IgE altough under Montelukast medication. This suggests me that Montelukast does not affect the immunoglobulins, but somehow restrict the allergic reaction indirectly.

What is the effect of Montelukast on the amount of IgE in blood?

I was interested in this question because I have always been a little confused about allergic responses, so I did some rather superficial research (i.e. I looked at some Wikipedia pages). As far as I can see there is no reason to think that Montelukast will have any effect upon IgE levels.

Montelukast is a leukotriene receptor antagonist. It is used to treat allergies and asthma.

Leukotrienes are lipid signalling molecules that are used by cells to regulate immune responses. One role of leukotrienes is to promote contractions in the smooth muscles lining the bronchioles. If they are over-produced they can cause inflammation in the airways leading to symptoms of asthma. Since leukotrienes act through a receptor, an antagonist of that receptor such as montelukast can reduce their effect.

IgE is involved in allergic responses because it interacts with Fc receptors on the surface of certain cells such as mast cells. If the IgE molecules are associated with one another through Ig-antigen interactions this leads to clustering of the Fc receptors which triggers an intracellular signalling pathway leading to mast cell degranulation - the release of histamine by fusion of storage vesicles with the cell membrane (i.e. exocytosis). Histamine causes constriction of the bronchioles via effects on smooth muscle, just like leukotrienes.

Montelukast versus inhaled corticosteroids in the management of pediatric mild persistent asthma

International guidelines recommend the use of inhaled corticosteroids (ICSs) as the preferred therapy, with leukotriene receptor antagonists (LTRAs) as an alternative, for the management of persistent asthma in children. Montelukast (MLK) is the first LTRA approved by the Food and Drug Administration for the use in young asthmatic children.

Therefore, we performed an analysis of studies that compared the efficacy of MLK versus ICSs. We considered eligible for the inclusion randomized, controlled trials on pediatric populations with Jadad score > 3, with at least 4 weeks of treatment with MLK compared with ICS.

Although it is important to recognize that ICSs use is currently the recommended first-line treatment for asthmatic children, MLK can have consistent benefits in controlling asthmatic symptoms and may be an alternative in children unable to use ICSs or suffering from poor growth. On the contrary, low pulmonary function and/or high allergic inflammatory markers require the corticosteroid use.


Monoclonal antibodies—including rituximab, alemtuzumab, trastuzumab, bevacizumab, cetuximab, and panitumumab—have improved the treatment of various malignancies. Although generally better tolerated with less toxicity than conventional anticancer agents, monoclonal antibodies may cause infusion-related reactions like other infusional agents. The incidence of infusion reactions varies by agent, but severe events occur only occasionally, mostly with the first or second infusion. Although the exact etiology of infusion reactions remains unclear, they may arise via either IgE- or non-IgE–dependent mechanisms. There is a compelling clinical need to improve the risk assessment for severe infusion reactions. The recent identification of pre-existing IgE crossreacting with cetuximab, its association with severe reactions, and regional variation in the prevalence may provide a marker for high-risk assessment. Premedication with antihistamines, acetaminophen, and/or corticosteroids is a common practice to prevent infusion reactions with all monoclonal antibodies. However, a recent observational study suggests that premedication may no longer be necessary after the second infusion of cetuximab if patients did not develop any symptoms with the first two infusions. Considering the heterogeneity of infusion reactions, clinicians need to recognize the underlying nature of these events in order to identify patients at risk as well as provide optimal prophylactic measures and management of symptoms.


IL-6 functions as a mediator for notification of the occurrence of some emergent event. IL-6 is generated in an infectious lesion and sends out a warning signal to the entire body. The signature of exogenous pathogens, known as pathogen-associated molecular patterns, is recognized in the infected lesion by pathogen-recognition receptors (PRRs) of immune cells such as monocytes and macrophages (Kumar et al. 2011). These PRRs comprise Toll-like receptors (TLRs), retinoic acid-inducible gene-1-like receptors, nucleotide-binding oligomerization domain-like receptors, and DNA receptors. They stimulate a range of signaling pathways including NF-㮫, and enhance the transcription of the mRNA of inflammatory cytokines such as IL-6, tumor necrosis factor (TNF)-α, and IL-1β. TNF-α and IL-1β also activate transcription factors to produce IL-6.

IL-6 also issues a warning signal in the event of tissue damage. Damage-associated molecular patterns (DAMPs), which are released from damaged or dying cells in noninfectious inflammations such as burn or trauma, directly or indirectly promote inflammation. During sterile surgical operations, an increase in serum IL-6 levels precedes elevation of body temperature and serum acute phase protein concentration (Nishimoto et al. 1989). DAMPs from injured cells contain a variety of molecules such as mitochondrial (mt) DNA, high mobility group box 1 (HMGB1), and S100 proteins (Bianchi 2007). Serum mtDNA levels in trauma patients are thousands of times higher than in controls and this elevation leads to TLR9 stimulation and NF-㮫 activation (Zhang et al. 2010), whereas binding of HMGB1 to TLR2, TLR4, and the receptor of advanced glycation end products (RAGE) can promote inflammation. The S100 family of proteins comprises more than 25 members, some of which also interact with RAGE to evoke sterile inflammation (Sims et al. 2010).

In addition to immune-mediated cells, mesenchymal cells, endothelial cells, fibroblasts, and many other cells are involved in the production of IL-6 in response to various stimuli (Akira et al. 1993). The fact that IL-6 issues a warning signal to indicate occurrence of an emergency accounts for the strict regulation of IL-6 synthesis both gene transcriptionally and posttranscriptionally. A number of transcription factors have been shown to regulate the IL-6 gene transcription ( Fig. 2 ). The functional cis-regulatory elements in the human IL-6 gene 5′ flanking region are found binding sites for NF-㮫, specificity protein 1 (SP1), nuclear factor IL-6 (NF-IL-6) (also known as CAAT/enhancer-binding protein β), activator protein 1 (AP-1), and interferon regulatory factor 1 (Libermann and Baltimore 1990 Akira and Kishimoto 1992 Matsusaka et al. 1993). Activation of cis-regulatory elements by stimulation with IL-1, TNF, TLR-mediated signal, and forskolin lead to activation of the IL-6 promoter.

Transcriptional and posttranscriptional regulation of IL-6 gene. The expression and degradation of IL-6 mRNA is regulated transcriptionally and posttranscriptionally by several proteins and microRNAs. Activation of these proteins and microRNAs determines the fate of IL-6 mRNA. NF-IL-6, nuclear factor of IL-6 Tax, transactivator protein TAT, transactivator of the transcription HBVX, hepatitis B virus X protein Ahr, aryl hydrocarbon receptor GR, glucocorticoid receptor ER, estrogen receptor Rb, retinoblastoma PPARα, peroxisome proliferator�tivated receptor α miR, microRNA IRAK1, IL-1 receptor𠄺ssociated kinase 1 STAT3, signal transducer and activator of transcription 3 ORF, open reading frame TTP, tristetraprolin BRF1, butyrate response factor 1.

A polymorphism at position -174 of the IL-6 promoter region is reportedly associated with systemic onset juvenile idiopathic arthritis (Fishman et al. 1998) and susceptibility to RA in Europeans (Lee et al. 2012). Stimulation with lipopolysaccharide (LPS) and IL-1 did not evoke any response in a reporter assay using -174 C construct. A -174 G construct, on the other hand, was found to promote transcription of the reporter gene, suggesting that a genetic background of excess IL-6 production constitutes a risk factor for juvenile idiopathic arthritis and RA.

An interesting finding is that some viral products enhance the DNA-binding activity of NF-㮫 and NF-IL-6, resulting in an increase in IL-6 mRNA transcription. An instance of this phenomenon is that interaction with NF-㮫 of the Tax derived from the human T lymphotropic virus 1 enhances IL-6 production (Ballard et al. 1988 Leung and Nabel 1988). Another example is the enhancement of both NF-㮫 and NF-IL-6 DNA-binding activity by the transactivator of the TAT protein of the human immunodeficiency virus 1 (Scala et al. 1994 Ambrosino et al. 1997). Moreover, it has been shown that DNA binding of NF-IL-6 can be enhanced by the human hepatitis B virus X protein (Mahe et al. 1991 Ohno et al. 1999).

On the other hand, some transcription factors suppress IL-6 expression. Peroxisome proliferator�tivated receptors (PPARs) are ligand-activated transcription factors consisting of three subtypes: α, β, and γ. Among three PPARs, fibrates-activated PPARα interacts with c-Jun and p65 NF-㮫 subunits, which negatively regulate IL-6 transcription (Delerive et al. 1999). In addition, some hormone receptors have been identified as repressors of IL-6 expression. The increase in serum IL-6 after menopause or ovarectomy is reportedly associated with suppression of IL-6 expression by estrogen receptors (Jilka et al. 1992), whereas activation of the glucocorticoid receptor can repress IL-6 expression, and this is thought to be one of mechanisms responsible for the anti-inflammatory effects of corticosteroids (Ray and Prefontaine 1994). It has further been shown that retinoblastoma protein and p53 repress the IL-6 gene promoter, whereas it is up-regulated by mutant p53 (Santhanam et al. 1991).

In addition, some microRNAs directly or indirectly regulate transcription activity. Interaction of microRNA-155 with the 3′ untranslated regions (UTR) of NF-IL-6 results in suppression of NF-IL-6 expression (He et al. 2009), whereas microRNA-146a/b and -223 indirectly suppress transcription of IL-6 by respectively targeting IL-1 receptor𠄺ssociated kinase 1 and STAT3 (Chen et al. 2012 Zilahi et al. 2012).

Nonpharmacologic Therapies


Although the precise mechanism by which acupuncture works is unclear, proponents suggest that it releases neurochemicals such as beta-endorphins, enkephalins, and serotonin, which in turn mediate the inflammatory pathways involved in allergic rhinitis. Based on RCTs looking at acupuncture as a treatment for allergic rhinitis in adults and children, there is insufficient evidence to support or refute its use.46 – 49


Based on the limited data to date, probiotics cannot be endorsed as a useful alternative therapy for allergic rhinitis. Studies of probiotics gave mixed results and included 12 RCTs and one study looking at prenatal treatment.50 , 51


Many herb and plant-extract compounds have been studied with respect to allergic rhinitis treatment, but the effectiveness and safety of these compounds have not been established.52


Patients with allergic rhinitis should avoid exposure to cigarette smoke, pets, and allergens to which they have a known sensitivity. Nasal irrigation is beneficial in the treatment of chronic rhinorrhea and may be used alone or as adjuvant therapy.53 Irrigation using a neti pot is superior to saline sprays it may also be done with a low-pressure squeeze bottle.53

Prevention has been a large focus in the study of allergic rhinitis, but few interventions have proven effective. Although dust mite allergies are common, studies have not found any benefit to using mite-proof impermeable mattress and pillow covers.54 – 56 Other examples of proposed interventions without documented effectiveness include breastfeeding, delayed exposure to solid foods in infancy, and use of air filtration systems.57 – 61 Figure 1 provides an algorithm for the treatment of allergic rhinitis with pharmacologic and nonpharmacologic therapies.

MCAS: Treatment

This post discusses medications used to treat MCAS. Doses listed are taken directly from “Presentation, diagnosis and management of mast cell activation syndrome” by Lawrence B. Afrin. These doses are general recommendations. Medication should always be taken under the direction of a provider who knows you and your case personally.

MCAS is generally treated identically to ISM, with the medications that block the action of released mediators, that prevent the release of mediators or that prevent the production of mediators. As a reminder, any medication that causes a reaction should be evaluated to see if it is truly caused by the drug or by a dye or inert ingredient. Medications compounded without dyes or noxious fillers can be truly life changing for mast cell patients. Generally, new medications for be trialed for 1-2 months to determine if they are effective.

Antihistamines are first line medications for both acute and chronic management of MCAS (but not for anaphylaxis – epinephrine is first line medication for anaphylaxis.) Most currently available antihistamines either block the histamine 1 (H1) receptor or the histamine 2 (H2) receptor and are referred to by the receptors they block. It is generally recommended for MCAS patients to take medication to block H1 and H2 receptors daily as baseline medications.

Loratadine is a common H1 starting medication. It has low anticholinergic activity and is not sedating. Dosing usually starts at 10mg daily and may be increased to 10mg 2-3 times a day. Fexofenadine starting dose in MCAS is usually 180mg every 12 hours cetirizine 10mg every 12 hours levocetirizine 5mg every 12 hours. Loratadine, fexofenadine and cetirizine are all available without prescription in the US. Of note, none of these medications are available for IV administration, so Benadryl should be used for emergency management of severe MCAS symptoms.

There are several H2 blockers available in the US, most over the counter. Cimetidine and ranitidine have more drug-drug interactions than famotidine and nizatadine. Famotidine, which is also readily sourced for IV administration, is usually dosed at 20-40mg every 12 hours, though in severe cases, doses of 80mg every 12 hours may be used. (This dosing is also seen in Zollinger-Ellison Syndrome patients.) Ranitidine starts at 75mg every 12 hours, increasing to 300mg every 12 hours. Nizatadine (Axid) is dosed at 150-300mg every 12 hours, and cimetidine at 400mg every 12 hours.

There are several other medications with H1 antihistamine effect. Tricyclic antidepressants, phenothiazine antiemetics (like promethazine) and quetiapine, an antipsychotic, are all H1 blockers. Addition of these medications often helps even when another H1 blocker is being taken by the patient. In particular, use of doxepin has been well described. It is usually started at 10mg twice daily and can be increased by 10mg twice daily to doses of 40-50mg twice daily. Beyond this, exhaustion and grogginess are often intolerable.

Ketotifen is a medication with both antihistamine and mast cell stabilizing properties, meaning it interferes with the release of mediators. The oral use of this medication for mast cell disease management is not well described, in part due to the oral formulation not being available in the US. Dosing is usually started at 1mg twice daily and increased in increments of 1mg twice daily until desired effects are noted and balanced with an acceptable side effect profile. As described by Afrin, single dosing is usually 6mg or less, and can be taken up to four times a day.

Benzodiazepines are often helpful in MCAS, due both to its action on mast cells and also directly on organs, particularly GI organs. Lorazepam, clonazepam and alprazolam are preferred due to their shorter window of action. All can be dosed beginning at 0.25mg every 12 hours, increasing by 0.25mg twice daily every week. Flunitrazepam has been described in treatment of mast cell disease. This medication has a longer halflife and is generally dosed at 0.5-2mg once a day.

Imidazopyridine medications like zolpidem (Ambien) also act on the benzodiazepine receptors of the body. Though usually taken for insomnia, some MCAS patients report relief of other symptoms. Whether or not these medications work in a patient seems independent of whether benzodiazepines are currently being taken by the patient or have worked or failed in the past.

Non-steroidal anti-inflammatory drugs (NSAIDS) can be helpful in MCAS patients who tolerate them. In particular, use of aspirin to bind prostaglandins has been very well described. A common starting dose is 325mg twice daily, with dosing up to 650-1300mg twice daily seen. Some patients take as much as 1300mg four times a day, but doses higher than 2600mg/day are unhelpful in most patients. Non enteric coated aspirin seems to be better tolerated and more effective at relieving symptoms in MCAS than enteric coated. In MCAS patients for whom aspirin is inappropriate (such as those with low platelets or decreased kidney function), COX2 inhibitors like Celebrex are sometimes used. Celebrex dosing in these patients usually begins at 100mg twice daily and increases up to 400mg twice daily.

Leukotriene inhibitors are frequently used in MCAS patients. Montelukast is the most common, being dosed as 10mg once to twice a day. Zafirlukast is dosed at 20mg twice daily. Doses should be decreased appropriately if liver dysfunction is also present.

Cromolyn is the most well known mast cell stabilizer, despite the fact that the mechanism by which it acts is still unclear. More recently, it has been noted to block mast cell receptor 35, which is increased when IgE is present. Cromolyn has extremely poor absorption, with 98% of oral doses being excreted unchanged. When inhaled, absorption increases to around 5%. Oral dosing is from 100-200mg 2-4 times daily. When nebulized, dosing is usually 20mg 2-4 times daily. Of note, patients usually experience a resurgence of symptoms when first starting the medication that may last 3-4 days. In my experience, this symptom increase is sometimes observed when increasing the dose. It can take several weeks to determine if cromolyn is truly effective in patient, with some people only seeing serious gains after four months.

Pentosan is less well known mast cell stabilizer whose mechanism is likewise unknown. This medication is commonly used in interstitial cystitis, a mast cell disorder that affects the genitourinary tract. Though Pentosan seems to be most effective in the GU tract, some patients report decrease in other symptoms while on this medication. It is usually dosed at 100mg every 8-12 hours.

Quercetin is commonly mentioned as a natural/homeopathic mast cell stabilizer. After much research on the topic, I have to say that I agree. It has been found to inhibit lipoxygenase and cyclooxygenase, which in turn decreases production of leukotrienes and histamine. It is usually dosed starting at 500-2000mg per day, divided up into 2-4 doses. For example, a daily dose of 500mg may be taken as 125mg four times a day. A newer form, quercetin chalcone, is usually taken at 250mg three times a day.

Pancreatic enzymes, like Creon, are sometimes helpful in MCAS patients who have pancreatitis symptoms, even if they are not having pancreatic type pain. It sometimes helps with chronic diarrhea, weight loss and malabsorption.

Corticosteroids like prednisone are sometimes used to manage MCAS symptoms. These medications can prevent mast cells from producing mediators and as such can be very effective. However, long term use can have severe side effects and as such is discouraged.

Omaluzimab (Xolair) is an anti-IgE antibody. It is not clear exactly how this stabilizes mast cells reacting by a non-IgE mechanism. Xolair is injected subcutaneously at doses of 150-300mg every 2-4 weeks. It should be trialed for at least 3-4 months before determining if it is effective. Interestingly, whether or not a patient responds and how well seems to be independent of their pretreatment IgE level.

The successful use of chemo medications for severe MCAS cases has been described in literature. In particular, hydroxyurea can be effective, though rapid onset and severe low blood cell counts are a real risk. It is usually started at 500mg daily and increased up to 2000mg daily as needed. Blood counts should be monitored weekly for four weeks at the onset of treatment and after any dosage increase. Tyrosine kinase inhibitors, like imatinib and dasatinib, have also been used as last resorts in MCAS patients. Imatinib is usually dosed at 100-200mg daily and dasatinib at 20-50mg daily. Patients on these medications require careful monitoring for pulmonary and renal issues. All chemo patients are at increased risk of infection.

IV hydration is being used more frequently to manage baseline symptoms of MCAS patients. TNF-alpha inhibitors have been suggested to help mast cell symptoms, but there have been no symptoms. (I take a TNF-alpha inhibitor for autoimmune issues and do find it helps to relieve some of my mast cell symptoms.) Other possible avenues include IL-1 and IL-1b inhibitors and kinin-b2 receptor blockers. Tryptase inhibitors continue to be in development.

Afrin, Lawrence B. Presentation, diagnosis and management of mast cell activation syndrome. 2013. Mast cells.

Part 2: A Role for the Actin-Reorganizing Protein Drebrin in Mast Cell Function

00:00:08.02 Hello.
00:00:09.12 I'm Avery August,
00:00:10.24 I'm at Cornell University,
00:00:12.02 and in the second part of this talk
00:00:13.27 I'm going to tell you about a little bit
00:00:15.19 some of our research studies
00:00:16.27 trying to understand the molecular basis
00:00:18.23 for the allergic response in mast cells.
00:00:23.04 So, here's a summary
00:00:25.10 of how the allergic response occurs.
00:00:29.02 You have an allergen,
00:00:30.02 it generates a IgE response,
00:00:32.16 that IgE then coats mast cells and basophils
00:00:36.20 so that the second time you get exposed to an allergen,
00:00:39.01 the mast cells degranulate
00:00:41.11 and you get these symptoms
00:00:43.18 of an allergic response.
00:00:45.29 So, we're very interested in trying to understand
00:00:48.13 the molecular basis for this degranulation response,
00:00:50.21 because we'd like to understand
00:00:52.26 how to better target this process
00:00:55.10 to prevent both degranulation
00:00:57.27 and the development of these symptoms.
00:01:00.29 So, as I told you in the first part of my talk,
00:01:04.24 blocking mast cells
00:01:06.20 and blocking mast cell degranulation
00:01:08.08 can reduce the release of the components,
00:01:10.28 and by reducing the release of these components,
00:01:12.25 we actually reduce the symptoms.
00:01:14.28 But what is the molecular basis for this?
00:01:17.10 As I told you, the drug Chromolyn
00:01:19.26 is able to do this,
00:01:21.10 but we don't quite understand how Chromolyn works,
00:01:23.26 and also Chromolyn has side effects.
00:01:26.22 So, what we do know is that
00:01:29.13 the mast cell has a receptor for IgE,
00:01:32.00 and that receptors for IgE
00:01:34.00 is actually very similar to receptors
00:01:36.14 that are found on T cells, like the T cell receptor,
00:01:38.22 or on B cells, the B cell receptor.
00:01:40.25 And all those receptors,
00:01:42.13 what they have in common,
00:01:44.03 are cytoplasmic tails
00:01:45.23 that have what are called ITAM motifs,
00:01:47.11 and these ITAM motifs
00:01:49.10 interact with families of kinases
00:01:52.10 that lead to an intracellular signaling pathway
00:01:54.08 that eventually leads to degranulation
00:01:56.12 and histamine release,
00:01:58.03 as I discussed in part one,
00:01:59.24 as well as cytokine production.
00:02:01.25 And so what we're very interested in is
00:02:05.14 trying to understand how these pathways
00:02:07.14 actually lead to these different effects.
00:02:10.01 So, what we do know is that
00:02:13.00 the FC receptor for IgE
00:02:14.16 triggers an increase in intracellular calcium,
00:02:16.14 and that increase in intracellular calcium
00:02:18.10 is very important
00:02:20.09 for both degranulation and cytokine production,
00:02:23.08 and one of the compounds
00:02:26.02 that has been discovered that can actually
00:02:28.24 inhibit this calcium release is
00:02:30.27 a molecule that was first reported by other Abbott labs
00:02:33.02 as an immunosuppressant.
00:02:34.27 And that molecule, which I'll name BTP for short,
00:02:38.12 is actually very interesting,
00:02:40.27 because it actually can inhibit
00:02:42.27 calcium signaling in cells.
00:02:45.14 And so we were very interested in trying to understand
00:02:47.27 whether this particular compound
00:02:50.05 would also inhibit the mast cell response in vivo.
00:02:53.13 So, to do that, what we did
00:02:56.20 is we took mice and we injected them with IgE
00:03:00.25 that was specific to a molecule
00:03:03.19 called DNP-BSA.
00:03:06.07 And when we injected that IgE,
00:03:08.17 that IgE will now circulate within the mouse,
00:03:11.04 will coat the mast cells and basophils,
00:03:13.27 and now when we inject the mouse
00:03:16.06 with the allergen,
00:03:19.00 within three minutes,
00:03:20.13 we can determine whether the mast cells will release histamine,
00:03:23.16 which we can then analyze.
00:03:25.07 We also determined whether BTP
00:03:27.04 would block this effect.
00:03:29.00 And so what we found was that
00:03:31.22 when we injected mice with BTP
00:03:33.26 an hour before we gave them the allergen,
00:03:35.28 we could get reduced histamine release,
00:03:38.24 indicating that BTP actually blocks
00:03:41.12 the release of histamine from these mast cells.
00:03:43.27 The other thing we wanted to do
00:03:45.21 is determine whether this mast cell effect
00:03:48.23 would lead to differences in temperature.
00:03:52.04 One of the things that happens
00:03:54.02 when you expose mice to IgE and the allergen
00:03:57.22 is that they actually lose body temperature,
00:04:00.04 and we can measure that body temperature
00:04:01.28 by measuring the temperature over time
00:04:04.16 in the presence or absence of the BTP.
00:04:08.10 And so in that experiment what we did.
00:04:10.26 we injected the mice with IgE and,
00:04:14.16 an hour before we have them the allergen,
00:04:16.16 we gave the BTP
00:04:18.02 and then we measured the amount of.
00:04:20.04 the temperature changes that occurred.
00:04:22.12 What you can see here
00:04:24.12 is a difference in body temperature in these mice,
00:04:26.25 and you can see that the mice that received the vehicle
00:04:29.02 actually lost body temperature,
00:04:31.13 whereas the mice that received BTP
00:04:33.20 did not lose body temperature.
00:04:35.16 And so what that experiment indicated to us
00:04:38.04 was that BTP was able to inhibit
00:04:40.04 both histamine release in mast cells,
00:04:41.23 but also the effects of mast cell degranulation,
00:04:44.10 that is, temperature loss.
00:04:47.01 So, BTP, then,
00:04:49.05 can inhibit mast cell degranulation
00:04:51.29 and can inhibit the release
00:04:54.11 of the mast cell granule contents,
00:04:57.17 so we wanted to find out whether BTP
00:04:59.26 could affect mast cells directly.
00:05:01.13 And so, fortunately, we can generate mast cells very simply
00:05:03.28 by taking bone marrow from mice,
00:05:05.24 culturing them in the presence of cytokines,
00:05:08.00 interleukin-3,
00:05:09.18 and stem cell factor,
00:05:11.06 and 4-6 weeks later
00:05:12.20 we have a population that's largely mast cells,
00:05:14.18 almost 100% mast cells.
00:05:16.10 We can then take those mast cells and analyze them.
00:05:19.00 And the way we did this is
00:05:21.00 we took the mast cells,
00:05:22.16 we incubated them with IgE overnight,
00:05:24.20 by arming them,
00:05:26.12 and then we can add the antigen,
00:05:28.04 and over time we can analyze these mast cells.
00:05:30.23 And so we did that,
00:05:32.12 and what we found was that
00:05:34.21 in mast cells that were just treated with vehicle
00:05:36.26 we got nice degranulation,
00:05:39.13 whereas mast cells that were
00:05:41.11 only treated with BTP
00:05:43.07 and triggered with IgE.
00:05:45.04 we no longer got degranulation,
00:05:46.27 indicating that BTP
00:05:49.01 actually inhibits the degranulation of mast cells,
00:05:52.00 blocking them from releasing their contents,
00:05:54.09 including histamine, heparin, and TNF.
00:05:57.27 So, the next thing we wanted to find out is
00:06:00.03 what is the target of BTP.
00:06:01.29 And so we collaborated with a couple of chemists,
00:06:06.16 Blake Peterson and his student Laurie Mottram,
00:06:09.20 and they synthesized for us
00:06:11.26 the BTP coupled to a linker and biotin.
00:06:15.13 And what we could then do
00:06:17.12 is take that BTP-biotin linkage
00:06:19.18 and couple it to a bead
00:06:21.13 and determine, using standard biochemical techniques,
00:06:24.18 which proteins would actually interact
00:06:26.28 with the BTP moiety.
00:06:29.00 And so that experiment is shown over here.
00:06:31.09 You can see that we would take control beads
00:06:34.16 and coat them with just the linker and biotin,
00:06:37.18 or beads that have the BTP.
00:06:41.05 We would pass a protein extract over those beads,
00:06:44.09 we would wash away all the extraneous material,
00:06:47.00 and then we would analyze the proteins
00:06:50.03 that actually specifically interacted with the beads
00:06:52.06 on SDS-PAGE gels
00:06:54.04 by mass spectrometry
00:06:56.06 to identify BTP-associated proteins.
00:06:58.19 And so we did that experiment
00:07:00.09 using lysates from cells,
00:07:03.05 and what we found was that
00:07:05.15 a prominent protein that was purified
00:07:07.09 on these BTP beads
00:07:08.22 was a protein called drebrin.
00:07:10.12 And so drebrin is actually
00:07:12.24 an actin-binding protein,
00:07:14.12 and it actually can interact with actin
00:07:16.25 and leads to the polymerization of actin
00:07:20.04 when you put it in cells.
00:07:22.24 We also found that
00:07:25.03 when you mutate two residues
00:07:27.14 within the actin binding domain of drebrin,
00:07:29.28 we could abolish binding of BTP to drebrin,
00:07:32.26 indicating that BTP interacted
00:07:35.02 directly with drebrin
00:07:36.21 and not in an indirect manner.
00:07:38.08 And those residues are shown here in red.
00:07:39.24 If we mutate lysine 270 and lysine 271
00:07:42.17 to methionines,
00:07:44.11 we completely abolish the binding of BTP to drebrin,
00:07:47.04 whereas if we mutated arginine to methionine,
00:07:50.17 or glutamine to leucine,
00:07:52.23 we maintained the interaction,
00:07:54.25 indicating that this interaction is specific.
00:07:57.18 So we could show, then,
00:07:59.18 that BTP interacts with this actin-binding protein drebrin,
00:08:03.07 and drebrin is an actin regulating protein.
00:08:06.05 So that introduced a whole new area
00:08:10.03 that we could explore
00:08:11.27 to try to determine
00:08:13.18 what was the molecular basis for this Fc receptor response.
00:08:17.24 So again, here's the pathway that I showed you,
00:08:19.20 and what we showed you is that
00:08:22.04 calcium, shown in red,
00:08:24.02 is actually inhibited by BTP.
00:08:25.11 I also just showed you that drebrin
00:08:27.16 was identified as a BTP-interacting protein.
00:08:31.22 And so the question was,
00:08:33.14 where does drebrin fall within this pathway
00:08:36.25 that is triggered by the FC receptor?
00:08:39.13 And so we did some experiments
00:08:40.28 to try to determine
00:08:42.28 whether drebrin would be able
00:08:45.05 to affect the activation of
00:08:47.12 a number of these different pathways.
00:08:48.25 So, in order to do that,
00:08:50.10 we actually generated drebrin knockout mice,
00:08:52.06 and we did that by procuring the embryonic stem cells,
00:08:54.24 which had a cassette
00:08:57.26 that was trapped within the gene for drebrin,
00:09:00.06 which resulted in the cells
00:09:02.25 not being able to make the protein.
00:09:05.04 We generated mice from those embryonic stem cells
00:09:07.16 and then we examined the brains of those mice,
00:09:09.23 which also expressed drebrin,
00:09:11.21 for the expression of drebrin.
00:09:12.24 And you can see, here,
00:09:14.12 in this western blot
00:09:16.17 that the wild type brains
00:09:18.12 expressed full length drebrin,
00:09:19.26 whereas the brains from the drebrin-deficient mice
00:09:22.06 had no drebrin at all.
00:09:24.16 We then went on to further characterize these mice
00:09:27.24 to determine whether their mast cells
00:09:29.24 were functional.
00:09:31.03 And what you can see here
00:09:33.12 is skin from either the wild type of drebrin-deficient mice,
00:09:37.14 stained with Toluidine blue,
00:09:39.11 and in the black arrows
00:09:41.08 you can see where the mast cells are found in the skin,
00:09:43.00 and you can see that mast cell development
00:09:44.18 was completely fine in the absence of drebrin
00:09:47.01 in these mice.
00:09:48.24 We also looked at electron micrograph images
00:09:52.16 and you can see, again,
00:09:54.03 that the ultrastructure of these mast cells
00:09:55.26 was completely fine,
00:09:57.16 whether drebrin was there or not.
00:09:59.20 So we were fairly confident that in the absence of drebrin,
00:10:01.10 at least in vivo,
00:10:03.02 mast cells were able to develop
00:10:04.27 and they were found in the right place.
00:10:07.02 So, the next thing that we decided to do
00:10:09.05 is ask whether these mast cells
00:10:11.11 were functional in vivo in this analysis,
00:10:14.21 that I showed you earlier.
00:10:16.27 And here, what we did again.
00:10:19.00 we armed the mast cells in vivo
00:10:21.14 with IgE by injecting IgE,
00:10:23.22 and then, the next day,
00:10:26.18 we challenged them with the allergen
00:10:27.27 and then three minutes later
00:10:29.25 we collected these mice
00:10:31.18 and determined whether there was any histamine.
00:10:32.28 And again, what you see here
00:10:35.15 is that wild type mice generated a lot of histamine
00:10:37.00 when we gave them the allergen plus IgE,
00:10:39.18 whereas the drebrin deficient mice
00:10:41.18 had a much reduced histamine response
00:10:44.20 under the same conditions.
00:10:46.03 So these experiments indicated to us
00:10:48.19 that drebrin was really important for the release of histamine
00:10:51.04 from mast cells in vivo
00:10:52.16 when we triggered them with IgE.
00:10:55.10 The second experiment we did
00:10:57.06 was the experiment that I talked about earlier, which is,
00:11:00.13 do these drebrin-deficient mice actually lose body temperature
00:11:03.20 when we inject them with allergen?
00:11:05.14 And so we did the same experiment.
00:11:06.22 We armed the mast cells in vivo with IgE,
00:11:09.24 we gave them the allergen,
00:11:11.04 and then we monitored their temperature
00:11:12.24 for up to 60 minutes later
00:11:14.28 to determine whether they lose body temperature.
00:11:17.05 And what you can see here is that
00:11:22.16 the wild type mice that received vehicle.
00:11:24.06 they lost body temperature,
00:11:27.01 in the absence of drebrin,
00:11:29.08 they no longer lost body temperature,
00:11:32.00 and wild type mice that are treated with BTP
00:11:34.02 also no longer lost body temperature.
00:11:36.10 So, in both the knockout,
00:11:38.02 as well as the compound,
00:11:39.14 we got the same result.
00:11:40.22 That is, passive systemic anaphylaxis
00:11:43.18 was actually reduced
00:11:46.02 in response to allergen
00:11:48.09 when we inhibit with BTP
00:11:49.26 or when we knock out the gene drebrin.
00:11:53.25 So, the next thing we wanted to do, then,
00:11:55.27 is look at the individual mast cells
00:11:58.01 and ask whether we saw the same result.
00:11:59.11 So, again, we took bone marrow from mice,
00:12:01.26 in this case either wild type or drebrin-deficient mice,
00:12:04.02 grew them out in culture for six weeks,
00:12:06.24 and then we coated them with IgE overnight
00:12:08.20 and then triggered them with allergen
00:12:10.18 to determine whether they would respond.
00:12:13.22 And so, again,
00:12:16.04 we're looking at the activation of mast cells
00:12:18.23 by the IgE receptor,
00:12:20.22 and first we're going to look at calcium responses
00:12:22.12 to see whether calcium was affected
00:12:24.10 in the absence of drebrin,
00:12:26.12 and that experiment is shown here.
00:12:29.00 We take mast cells and we load them
00:12:30.27 with a calcium-sensitive dye,
00:12:33.03 we then coat them with IgE,
00:12:35.00 and then trigger them with the antigen,
00:12:37.14 and you can see that the wild type cells,
00:12:39.14 in light gray,
00:12:41.16 increase calcium and that calcium stays up for a long time,
00:12:44.23 whereas in the absence of drebrin
00:12:46.26 these mast cells increase calcium initially,
00:12:49.24 but the calcium doesn't stay up,
00:12:51.20 it starts to decrease over time.
00:12:54.01 And on the bottom graph
00:12:55.29 you can see the slope of that calcium decay
00:12:58.05 is a negative slope
00:13:00.13 in the absence of drebrin in these mast cells,
00:13:02.10 whereas it's a positive slope in the wild type cells,
00:13:04.29 indicating that in the absence of drebrin
00:13:06.27 what we're actually affecting
00:13:08.28 is the prolonged calcium release
00:13:10.26 that we see that's required
00:13:12.26 for these mast cells to degranulate and release their contents.
00:13:16.20 So, mast cell degranulation, then,
00:13:20.08 requires the activation of drebrin,
00:13:22.26 the activation of the FC receptor,
00:13:25.04 and releases these contents:
00:13:26.16 histamine, heparin, and other cytokines.
00:13:29.11 And so we then asked whether we could
00:13:32.27 see reduction in degranulation
00:13:34.17 in the absence of drebrin in these mast cells.
00:13:36.22 So, that experiment is shown over here.
00:13:39.04 We can stimulate these mast cells,
00:13:41.04 either wild type mast cells
00:13:42.16 or drebrin-deficient mast cells,
00:13:44.02 with IgE and the allergen,
00:13:46.10 and in a concentration dependent manner
00:13:48.08 you get an increase in degranulation,
00:13:50.26 as measured by the release of β-hexosaminase.
00:13:54.02 So, in wild type mast cells
00:13:55.22 you get an increase in β-hexosaminase release,
00:13:58.14 and when drebrin is missing,
00:14:01.05 you can see here that the mast cells
00:14:04.06 degranulate much less compared to the wild type.
00:14:07.06 So the absence of drebrin, then,
00:14:09.07 affects mast cell degranulation in vitro,
00:14:10.26 in addition to reductions in intracellular calcium over time.
00:14:16.00 So, what about cytokines?
00:14:17.26 So, I told you in the first part of my talk
00:14:20.08 that activation of mast cells with allergen
00:14:22.18 not only releases histamines,
00:14:24.10 but also releases cytokines,
00:14:26.08 and those cytokines can have important effects
00:14:28.02 on the immune system,
00:14:29.10 so we therefore did a similar experiment
00:14:31.09 where we took mast cells
00:14:33.27 and stimulated them
00:14:35.25 and asked whether drebrin, or the absence of drebrin,
00:14:37.28 would affect the cytokine release.
00:14:41.12 And the cytokine release.
00:14:43.12 some of those cytokines are dependent on calcium
00:14:44.21 and some of the cytokines are not dependent on calcium,
00:14:46.28 so we looked at two different patterns of cytokines:
00:14:49.00 calcium-dependent cytokines
00:14:50.11 and calcium-independent cytokines.
00:14:53.04 And that experiment is shown over here.
00:14:55.04 In the top two graphs are calcium-dependent cytokines,
00:14:57.19 interleukin-2 and GM-CSF,
00:15:00.23 and you can see here, in the filled circles,
00:15:03.29 wild type cells produce IL-2 and GM-CSF
00:15:08.04 perfectly fine,
00:15:09.16 but in the mast cells that are missing drebrin,
00:15:11.14 you can see that they now no longer
00:15:13.20 release the calcium-dependent cytokines.
00:15:16.02 By contrast, if we look at IL-6, on the bottom graph,
00:15:19.04 which is not a calcium-dependent cytokine,
00:15:21.18 you can see that there's very little difference
00:15:23.03 between the wild type cells and the drebrin-deficient cells
00:15:24.26 in cytokine production.
00:15:27.02 So, these experiments show that
00:15:29.08 drebrin plays a critical role
00:15:30.24 in regulating both calcium signaling leading to degranulation,
00:15:34.17 but also calcium signaling
00:15:36.12 leading to cytokine production
00:15:38.24 and only those cytokines
00:15:40.10 that are calcium-dependent
00:15:41.17 are affected by the absence of drebrin.
00:15:43.24 The other thing that we wanted to find out
00:15:48.04 is where in this pathway
00:15:50.00 does drebrin lie.
00:15:51.02 And so we did a number of experiments
00:15:52.19 where we examined the
00:15:54.17 activation of the Src, Syk, and Tec kinases,
00:15:56.18 and there was no difference.
00:15:58.05 We asked whether PLC-gamma activation
00:16:00.21 was affected by the absence of drebrin,
00:16:02.29 and there was no difference.
00:16:04.14 And so what we could conclude, then,
00:16:06.12 was that drebrin plays a role
00:16:08.18 in a parallel or different pathway
00:16:10.13 that is not upstream of PLC-gamma,
00:16:12.25 but actually still affects calcium
00:16:14.24 in a manner
00:16:16.22 that we don't quite understand.
00:16:19.06 Now, one of the things that I told you about
00:16:22.01 was that the activation of drebrin
00:16:23.16 is important for actin polymerization,
00:16:28.03 and so we wanted to find out
00:16:29.20 whether drebrin would affect actin
00:16:32.22 in these cells.
00:16:33.24 Now, actin is really important
00:16:35.10 for the structure of the cell,
00:16:38.01 but it has also been shown to be important
00:16:40.18 for degranulation
00:16:42.20 and the movement of granules within cells,
00:16:44.24 and so the idea that drebrin plays a role
00:16:47.03 not only in regulating calcium signaling
00:16:49.05 but also in regulating the actin cytoskeleton
00:16:52.07 prompted us to look at the actin
00:16:54.07 in these cells.
00:16:55.22 So, we did some very simple experiments
00:16:57.20 to determine that.
00:16:59.00 First, we took either wild type
00:17:01.09 or drebrin-deficient mast cells
00:17:02.25 and stained them with phalloidin,
00:17:04.24 which stains F, or filamentous, actin.
00:17:09.16 And you can see, most apparent,
00:17:11.20 is that the wild type cells
00:17:13.24 actually have nice actin
00:17:16.04 around the perimeter of the cell,
00:17:18.11 but if we look at the drebrin-deficient cells
00:17:20.19 you can see that they have more actin
00:17:22.04 and the actin is actually distributed
00:17:24.16 not only in the perimeter of the cell,
00:17:26.14 but starts to extend within the cell.
00:17:28.04 So, we wanted to quantify this a bit more,
00:17:30.23 and so we did flow cytometry
00:17:32.14 with these cells
00:17:34.01 using labeled phalloidin,
00:17:36.01 and you can see here
00:17:38.07 that wild type mast cells, in solid,
00:17:41.01 have actually less actin if you look
00:17:43.23 at the mean fluorescence intensity
00:17:45.14 than the mast cells that don't have drebrin.
00:17:50.13 So, in the absence of drebrin,
00:17:51.27 these mast cells actually have increased F-actin,
00:17:54.11 which may be affecting the response.
00:17:57.15 So, we wanted to explore this a bit further
00:17:59.01 and ask, what happens to the F-actin
00:18:01.11 when these cells are actually stimulated?
00:18:04.06 And so what we did is we took these mast cells
00:18:06.23 and stimulated them the same way that
00:18:08.17 we stimulated them before,
00:18:09.23 with IgE and allergen,
00:18:11.03 and we looked at F-actin over time
00:18:13.07 in these cells.
00:18:15.00 And so this is a bit of a complicated slide
00:18:17.11 and I'll take you through it slowly.
00:18:19.07 On the right you can see that the wild type mast cells
00:18:22.12 start out with actin at time zero,
00:18:23.25 most of the actin is at the edge of the cell.
00:18:26.14 at the perimeter of the cell.
00:18:28.05 By two minutes after activation,
00:18:29.18 you can see that the F-actin
00:18:31.04 starts to move within the cell,
00:18:33.20 with the increase in the signal
00:18:36.14 at 2 minutes, 5 minutes, and 10 minutes,
00:18:38.26 and then by 30 minutes, at the bottom,
00:18:40.29 the cell looks very similar to a cell
00:18:43.03 that hasn't been activated.
00:18:44.13 So, in wild type cells,
00:18:45.29 there's an increase in F-actin
00:18:47.23 that's reorganized
00:18:50.03 away from the perimeter of the cell
00:18:52.15 towards the middle of the cell
00:18:54.03 and then it moves back
00:18:56.01 to the perimeter of the cell.
00:18:58.04 If we look at the drebrin-deficient mast cells,
00:19:00.04 you can see that at time 0,
00:19:02.09 actin is distributed all over the cell,
00:19:04.07 not only at the perimeter,
00:19:06.07 and that pattern doesn't change much
00:19:08.27 as we stimulate the cells over time.
00:19:11.15 So, IgE FC receptor-induced changes
00:19:15.05 are different between the wild type cells
00:19:18.20 and the drebrin-deficient cells,
00:19:20.19 in space and in time.
00:19:23.17 And we can quantify this
00:19:25.03 by comparing the difference
00:19:26.27 between the drebrin-deficient cells
00:19:28.07 and the wild type cells at each time point,
00:19:31.04 statistically, and you can see here that.
00:19:33.14 on the y-axis in the graph on the left,
00:19:37.05 that at time 0,
00:19:40.03 there's a huge difference in the F-actin localization in these cells,
00:19:42.27 and that changes as the cell is activated,
00:19:45.19 but in all cases there's a statistically significant difference
00:19:49.03 in the location of actin
00:19:51.09 in the wild type cells
00:19:53.01 compared to the drebrin-deficient cells.
00:19:56.09 So, what these experiments
00:19:58.29 indicated to us
00:20:00.18 was that drebrin was regulating
00:20:02.18 the F-actin superstructure in these mast cells.
00:20:05.11 So, we asked the question,
00:20:07.28 can we relax the F-actin superstructure
00:20:10.10 in these drebrin-deficient cells
00:20:12.20 and rescue the function
00:20:14.19 in the absence of drebrin?
00:20:15.29 So, we used a compound
00:20:17.26 called latrunculin B.
00:20:18.29 What latrunculin B does
00:20:20.19 is it binds to F-actin
00:20:22.14 and increases its mobility,
00:20:24.11 or it reduces the amount of F-actin in cells.
00:20:27.15 And what I show you here on the [left]
00:20:30.20 are flow cytometry graphs
00:20:32.06 of drebrin-deficient mast cells
00:20:33.27 treated with latrunculin B,
00:20:35.07 and you can see here,
00:20:36.22 in the table on the [right],
00:20:38.00 as we increase the amount of latrunculin B,
00:20:39.27 we reduce the amount of F-actin
00:20:42.29 in these cells.
00:20:44.07 So we can use latrunculin B
00:20:45.19 to tune the amount of F-actin in these cells,
00:20:47.22 and we can now ask the question,
00:20:49.15 if we reduce the amount of F-actin in these drebrin-deficient cells,
00:20:52.25 can we rescue degranulation?
00:20:55.20 And that experiment is shown here.
00:20:57.25 So, here in the black filled circles
00:21:00.02 are wild type mast cells
00:21:02.14 that we've stimulated with IgE and antigen,
00:21:05.07 in a concentration-dependent fashion,
00:21:07.01 and we get an increase in degranulation
00:21:09.00 over that time period.
00:21:11.12 In the absence of drebrin,
00:21:13.01 in the open circles,
00:21:14.08 you can see that drebrin-deficient mast cells
00:21:18.19 actually degranulate much less.
00:21:22.18 However, when we treat these drebrin-deficient mast cells
00:21:25.13 with either 0.5 or 1 [micromolar] latrunculin B,
00:21:28.17 we can partially rescue degranulation,
00:21:30.26 indicating that allowing F-actin
00:21:32.11 to be more fluid in these cells
00:21:34.13 allows these cells to now
00:21:37.07 be able to degranulate.
00:21:39.17 So, we can summarize, then,
00:21:41.05 by placing drebrin in this pathway,
00:21:44.11 in a way
00:21:46.13 that the FC receptor triggers the activation
00:21:48.02 of these tyrosine kinases,
00:21:49.22 which then leads to the activation
00:21:51.06 of a number of different pathways,
00:21:53.02 including drebrin,
00:21:54.15 and what drebrin does
00:21:56.01 is control the amount of F-actin in these cells,
00:21:57.23 to control either the calcium signaling
00:21:59.22 and/or degranulation of these cells
00:22:02.14 so that they can release their contents,
00:22:04.15 produce cytokines,
00:22:06.11 and participate in the allergic response.
00:22:09.09 And so, with that,
00:22:10.15 I'd like to thank the people who did the work in the lab.
00:22:12.13 Most of this work was done
00:22:14.27 by the people shown in red.
00:22:16.25 Mankit Law was main the person
00:22:19.19 who drove most of the work,
00:22:21.03 with help from a number of postdocs
00:22:22.25 and graduate students in the lab.
00:22:24.17 We collaborated with Laurie Mottram and Blake Peterson,
00:22:27.05 along with Tomo Shirao and Hiro Yamazaki
00:22:29.29 at Gunma University.

  • Part 1: Allergies and the Immune System

Mast cell disease fact sheet

*Edited to add: Psychiatric symptoms are organic symptoms of mast cell disease, rather than reactive conditions from chronic illness.

This list is not exhaustive.

  • Many things can cause mast cell reactions or anaphylaxis in mast cell patients.
  • Allergy testing (skin prick or blood testing) is inaccurate in mast cell patients as these tests assess IgE allergies and mast cell patients often have non-IgE reactions.
  • Triggers can change over time and can include:
    • Heat, cold, or rapid change in temperature
    • Friction, especially on the skin
    • Sunlight
    • Illness, such as viral or bacterial infection
    • Exercise
    • Many foods, especially high histamine foods
    • Many preservatives and dyes
    • Many medications
    • Scents and fragrances
    • Physical stress, such as surgery
    • Emotional or psychological stress

    Diagnosis: Blood and Urine Testing

    • Blood test: Serum tryptase
      • This tests for the total amount of mast cells in the body, the “mast cell burden”
      • Should be tested during a non-reactive period for baseline and during a reaction
      • Time sensitive: should be tested 1-4 hours after start of reaction
      • Normal range for adults is under 11 ng/ml. (Edited to remove out of place words “is abnormal” at the end of this statement)
      • 2 ng/ml + 20% increased from baseline is indicative of mast cell activation
      • Baseline over 20 ng/ml is a minor criteria for diagnosis systemic mastocytosis
      • N-methylhistamine
        • Breakdown product of histamine
        • Released by mast cells when reacting
        • Very temperature sensitive
        • Sample must be refrigerated and transported on ice (unless preservative is provided)
        • Measured as a ratio of another molecule, creatinine
        • Normal range for adults is 30-200 mcg/g creatinine
        • One study found that if level was 300 mcg/g creatinine, a bone marrow biopsy was likely to be positive for systemic mastocytosis
        • Released by mast cells when reacting
        • Very temperature sensitive
        • Sample must be refrigerated and transported on ice (unless preservative is provided)
        • Normal range for both is under 1000 ng
        • 9a,11b-F2 prostaglandin is a breakdown product of D2 prostaglandin
        • 9a,11b-F2 prostaglandin is the marker for which MCAS/MCAD patients are most often positive
        • If taking aspirin or NSAIDs, these may be discontinued five days before the test or as directed by your physician
        • Other tests sometimes done in blood include heparin, histamine, prostaglandin D2 and chromogranin A.
        • Serum tryptase and 24 hour urine n-methylhistamine, D2 prostaglandin and 9a,11b-F2 prostaglandin are the tests considered to be most reliable indicators of mast cell disease.

        Diagnosis: Biopsies

        • Bone marrow biopsy
          • Obtained by bone marrow biopsy and aspiration procedure
          • Stained with Giemsa and tryptase stains
          • Tested with antibodies for CD117, CD2, CD25 and CD34
          • Looking for clusters of mast cells in groups of 15 or more
          • Looking for mast cells that are shaped abnormally, like spindles
          • DNA from the biopsy should be tested for the CKIT D816V mutation, a marker for systemic mastocytosis
          • Obtained by punch biopsy
          • Stained with Giemsa and tryptase stains
          • Tested with antibodies for CD117, CD2, CD25 and CD34
          • Looking for clusters of mast cells in groups of 15 or more
          • Looking for mast cells that are shaped abnormally, like spindles
          • DNA from the biopsy should be tested for the CKIT D816V mutation, a marker for systemic mastocytosis
          • Obtained by scoping procedures
          • Stained with Giemsa and tryptase stains
          • Tested with antibodies for CD117, CD2, CD25 and CD34
          • Looking for clusters of mast cells in groups of 15 or more
          • Looking for mast cells that are shaped abnormally, like spindles
          • DNA from the biopsy should be tested for the CKIT D816V mutation, a marker for systemic mastocytosis (less likely to be positive than bone marrow biopsies)
          • Mast cells should be counted in five high powered (60X or 100X) fields and the count then averaged
          • Some researchers consider an average of more than 20 mast cells in a high powered field to be high, but this is not agreed upon
          • Some researchers consider an average of more than 20 mast cells in a high powered field to be diagnostic for mastocytic enterocolitis
          • H1 antihistamines
            • Second generation, longer acting, non-sedating for daily use
            • First generation, shorter acting, sedating, but more potent
            • Other medications with H1 antihistamine properties like tricyclic antidepressants
            • Cromolyn
            • Ketotifen
            • Quercetin

            Medications to Avoid

            • Medications that cause degranulation
              • Alcohol (ethanol, isopropanol)
              • Amphoteracin B
              • Atracurium
              • Benzocaine
              • Chloroprocaine
              • Colistin
              • Dextran
              • Dextromethorphan
              • Dipyridamole
              • Doxacurium
              • Iodine based radiographic dye
              • Ketorolac
              • Metocurine
              • Mivacurium
              • Polymyxin B
              • Procaine
              • Quinine
              • Succinylcholine
              • Tetracine
              • Tubocurarine
              • Vancomycin (especially when given intravenously)
              • In some patients, aspirin and NSAIDs (please ask if your doctor if these are appropriate for you)
              • Medications that interfere with the action of epinephrine
                • Alpha adrenergic blockers
                  • Alfuzosin
                  • Atipamezole
                  • Carvedilol
                  • Doxazosin
                  • Idazoxan
                  • Labetalol
                  • Mirtazapine
                  • Phenoxybenzamide
                  • Phentolamine
                  • Prazosin
                  • Silodosin
                  • Tamsulosin
                  • Terazosin
                  • Tolazoline
                  • Trazodone
                  • Yohimbine
                  • Acebutolol
                  • Atenolol
                  • Betaxolol
                  • Bisoprolol
                  • Bucindolol
                  • Butaxamine
                  • Carteolol
                  • Carvedilol
                  • Celiprolol
                  • Esmolol
                  • Metoprolol
                  • Nadolol
                  • Nebivolol
                  • Oxprenolol
                  • Penbutolol
                  • Pindolol
                  • Propranolol
                  • Sotalol
                  • Timolol

                  Please note these lists are not exhaustive and you should check with your provider before starting a new medication. A pharmacist can review to determine if a medication causes mast cell degranulation or interferes with epinephrine. This list represents the medications for which I was able to find evidence of degranulation or a-/b-adrenergic activity.

                  Drugs for Asthma and Chronic Obstructive Pulmonary Disease

                  Symptoms of COPD result largely from two pathologic processes: chronic bronchitis and emphysema. In most cases, both processes are caused by an exaggerated inflammatory reaction to cigarette smoke. Chronic bronchitis—defined by chronic cough and excessive sputum production—results from hypertrophy of mucus-secreting glands in the epithelium of the larger airways. Emphysema is defined as enlargement of the air space within the bronchioles and alveoli brought on by deterioration of the walls of these air spaces. Among individuals with COPD, the relative contribution of these two processes can vary. That is, some patients may suffer primarily from chronic bronchitis, some primarily from emphysema, and some from both disease processes.

                  Fig. 60.2 depicts the events that lead to inflammation, airway obstruction, and air trapping in patients with COPD. Irritants such as tobacco smoke initiate an inflammatory response in the airways. As a result of the frequent and recurrent irritation and the subsequent response by various leukocytes and inflammatory mediators, pathologic changes result in the bronchial edema and increase in mucus secretion that characterize chronic bronchitis. Additionally, the continuous inflammation inhibits the production of protease inhibitors, which have a protective role in maintaining alveolar integrity. As a result of the inhibition, the protease enzymes break down elastin, resulting in the destruction of alveolar walls and the decrease in elastic recoil that characterize emphysema. In a small percentage of the population, emphysema results from a genetic alteration that results in alpha-1 antitrypsin deficiency. (Alpha-1 antitrypsin is a protease inhibitor that protects the lungs from enzymatic destruction by proteases.)

                  Overview of Drugs for Asthma and Chronic Obstructive Pulmonary Disease

                  The major drugs for asthma and COPD are shown in Table 60.1. They fall into two main pharmacologic classes: antiinflammatory agents and bronchodilators. The principal antiinflammatory drugs are the glucocorticoids. The principal bronchodilators are the beta 2 agonists. For chronic asthma and stable COPD, glucocorticoids are administered on a fixed schedule, almost always by inhalation. Beta 2 agonists may be administered on a fixed schedule for long-term control or as needed (PRN) to manage an acute attack. Like the glucocorticoids, beta 2 agonists are usually inhaled.

                  Drugs for Asthma and Chronic Obstructive Pulmonary Disease

                  Antiinflammatory Drugs: Glucocorticoids

                  Antiinflammatory Drugs: Others

                  Cromolyn (mast cell stabilizer, inhaled)

                  Zafirlukast (leukotriene modifier, oral)

                  Bronchodilators: Beta 2 -Adrenergic Agonists

                  Albuterol (inhaled, short acting)

                  Salmeterol (inhaled, long acting)

                  Overview of Major Drugs for Asthma and Chronic Obstructive Pulmonary Disease

                  Beclomethasone dipropionate [QVAR]

                  Budesonide [Pulmicort Flexhaler, Pulmicort Respules, Pulmicort Turbuhaler ]

                  Fluticasone propionate [Flovent HFA, Flovent Diskus]

                  Mometasone furoate [Asmanex Twisthaler]

                  Methylprednisolone [A-Methapred, Depo-Medrol, Medrol, Medrol Dose-Pak]

                  Prednisolone [Flo-Pred, Orapred ODT, Millipred, Pediapred, Prelone, Hydeltra TBA ]

                  Prednisone [Deltasone, Winpred ]

                  Montelukast, oral [Singulair]*

                  Zafirlukast, oral [Accolate]*

                  Zileuton, oral [Zyflo, Zyflo CR]*

                  Omalizumab, subcutaneous [Xolair]*

                  Roflumilast, oral [Daliresp, Daxas ]

                  Beta 2 -Adrenergic Agonists

                  Albuterol [ProAir HFA, ProAir RespiClick, Proventil HFA, Ventolin HFA, Airomir , Apo-Salvent MDI ]

                  Levalbuterol [Xopenex, Xopenex HFA]

                  Formoterol [Foradil Aerolizer, Perforomist, Oxeze Turbuhaler ] ‡

                  Indacaterol [Arcapta Neohaler, Onbrez Breezhaler ] †

                  Olodaterol [Striverdi Respimat] †

                  Salmeterol [Serevent Diskus] ‡

                  Aminophylline, oral [generic]

                  Theophylline, oral [Theo-24, Elixophyllin, Theolair , Theolair-SR, Pulmophylline, Theo ER ]

                  Aclidinium bromide, inhaled [Tudorza Pressair] †

                  Glycopyrronium bromide, inhaled [Seebri Neohaler, Seebri Breezhaler ] †

                  Ipratropium, inhaled [Atrovent HFA]

                  Tiotropium, inhaled [Spiriva, Spiriva HandiHaler, Spiriva Respimat]

                  Umeclidinium, inhaled [Incruse Ellipta] †

                  Budesonide/formoterol, inhaled [Symbicort]

                  Fluticasone/salmeterol, inhaled [Advair Diskus, Advair HFA]

                  Fluticasone/vilanterol, inhaled [Breo Ellipta]

                  Mometasone/formoterol, inhaled [Dulera, Zenhale ]


                  Albuterol/ipratropium, inhaled [Combivent Respimat, Combivent UDV ] †

                  Indacaterol/glycopyrronium, inhaled [Utibron Neohaler, Ultibro Breezhaler ] †

                  Olodaterol/tiotropium, inhaled [Stiolto Respimat] †

                  Vilanterol/umeclidinium, inhaled [Anoro Ellipta] †

                  * Approved only for asthma, not for chronic obstructive pulmonary disease.

                  † Approved only for chronic obstructive pulmonary disease, not for asthma.

                  ‡ For treatment of asthma, must always be combined with an inhaled glucocorticoid.

                  Administering Drugs by Inhalation

                  Most antiasthma drugs can be administered by inhalation. This route has three advantages: (1) therapeutic effects are enhanced by delivering drugs directly to their site of action, (2) systemic effects are minimized, and (3) relief of acute attacks is rapid. Three types of inhalation devices are usually employed: metered-dose inhalers (MDIs), dry-powder inhalers (DPIs), and nebulizers. Some pharmaceutical companies also have developed specialized inhaler devices for their products.

                  Metered-Dose Inhalers

                  MDIs are small, hand-held, pressurized devices that deliver a measured dose of drug with each actuation. Dosing is usually accomplished with 1 or 2 inhalations. When 2 inhalations are needed, an interval of at least 1 minute should separate the first inhalation from the second.

                  When using most MDIs, the patient must begin to inhale before activating the device. This requires hand-breath coordination, making MDIs difficult to use correctly. Accordingly, patients will need a demonstration as well as written and verbal instruction. Even with optimal use, only about 10% of the dose reaches the lungs. About 80% effects the oropharynx and is swallowed, and the remaining 10% is left in the device or exhaled.

                  Spacers are devices that attach directly to the MDI to increase delivery of drug to the lungs and decrease deposition of drug on the oropharyngeal mucosa (Fig. 60.3). Several kinds of spacers are available for use with MDIs. Some spacers contain a one-way valve that activates on inhalation, obviating the need for good hand-breath coordination. Some spacers also contain an alarm whistle that sounds off when inhalation is too rapid, thus maximizing effective drug administration. They can also prevent bronchospasm that may occur with sudden intake of an inhaled drug.

                  Dry-Powder Inhalers

                  DPIs are used to deliver drugs in the form of a dry, micronized powder directly to the lungs. Unlike MDIs, DPIs are breath activated. As a result, DPIs don’t require the hand-breath coordination needed with MDIs, and so DPIs are much easier to use. Compared with MDIs, DPIs deliver more drug to the lungs (20% of the total released vs. 10%) and less to the oropharynx. Also, spacers are not used with DPIs.


                  A nebulizer is a small machine used to convert a drug solution into a mist. The droplets in the mist are much finer than those produced by inhalers, resulting in less drug deposit on the oropharynx and increased delivery to the lung. Inhalation of the nebulized mist can be done through a face mask or through a mouthpiece held between the teeth. Because the mist produced by a nebulizer is inhaled with each breath, hand-breath coordination is not a concern. Nebulizers take several minutes to deliver the same amount of drug contained in 1 inhalation from an inhaler, but for some patients, a nebulizer may be more effective than an inhaler. Although nebulizers are usually used at home or in a clinic or hospital, these devices, which weigh less than 10 pounds, are sufficiently portable for use in other locations.

                  Antiinflammatory Drugs

                  Antiinflammatory drugs—especially inhaled glucocorticoids—are the foundation of asthma and COPD therapy. These drugs are taken daily for long-term control. Most people with asthma require these drugs for management at some point.


                  Life Stage Patient Care Concerns
                  Children Inhaled glucocorticoids are the preferred long-term treatment for children of all ages, including infants. Face masks are recommended for administration of inhaled glucocorticoids to children younger than 4 years. Alternative treatments include cromolyn and leukotriene receptor antagonists (e.g., montelukast), but evidence supporting these drugs for asthma management is lower than that supporting inhaled glucocorticoids. Montelukast is the only leukotriene modifier approved for children aged 1–5 years.
                  Pregnant women Inhaled glucocorticoids are classified in FDA Pregnancy Risk Category C however, they are preferred for uncontrolled asthma in pregnant women because uncontrolled asthma is associated with greater fetal risks. Of the leukotriene modifiers, montelukast and zafirlukast are Pregnancy Risk Category B, whereas zileuton is Pregnancy Risk Category C.
                  Breastfeeding women Inhaled glucocorticoids are not a contraindication to breastfeeding. Women taking systemic glucocorticoids should not breastfeed.
                  Older adults Benefits exceed risk. Inhaled glucocorticoids are much safer than systemic formulations.


                  Glucocorticoids (e.g., budesonide, fluticasone) are the most effective drugs available for long-term control of airway inflammation. Administration is usually by inhalation, but may also be intravenous (IV) or oral. Adverse reactions to inhaled glucocorticoids are generally minor, as are reactions to systemic glucocorticoids taken acutely. However, when systemic glucocorticoids are used long term, severe adverse effects are likely. The basic pharmacology of the glucocorticoids is presented in Chapter 56. Discussion here is limited to their use in asthma.

                  Mechanism of Antiasthma Action

                  Glucocorticoids reduce asthma symptoms by suppressing inflammation. Specific antiinflammatory effects include the following:

                  • Decreased synthesis and release of inflammatory mediators (e.g., leukotrienes, histamine, prostaglandins)

                  • Decreased infiltration and activity of inflammatory cells (e.g., eosinophils, leukocytes)

                  • Decreased edema of the airway mucosa (secondary to a decrease in vascular permeability)

                  By suppressing inflammation, glucocorticoids reduce bronchial hyperreactivity and decrease airway mucus production. There is also some evidence that glucocorticoids may increase the number of bronchial beta 2 receptors as well as their responsiveness to beta 2 agonists.

                  Use in Asthma

                  Glucocorticoids are used for prophylaxis in managing chronic asthma therefore, dosing must be done on a fixed schedule—not PRN. Because beneficial effects develop slowly, these drugs cannot be used to abort an ongoing attack. Glucocorticoids do not alter the natural course of asthma, even when used in young children however, they provide significant long term control and management of symptoms.

                  Inhalation Use

                  Inhaled glucocorticoids are first-line therapy for management of the inflammatory component of asthma. Most patients with persistent asthma should use these drugs daily. Inhaled glucocorticoids are very effective and are much safer than systemic glucocorticoids.

                  Oral Use

                  Oral glucocorticoids may be required for patients with moderate to severe persistent asthma or for management of acute exacerbations of asthma or COPD. Because of their potential for toxicity, these drugs are prescribed only when symptoms cannot be controlled with safer medications (inhaled glucocorticoids, inhaled beta 2 agonists). Because the risk for toxicity increases with duration of use, treatment should be as brief as possible.

                  Adverse Effects

                  Inhaled Glucocorticoids

                  These preparations are largely devoid of serious toxicity, even when used in high doses. The most serious concern is adrenal suppression.

                  The most common adverse effects are oropharyngeal candidiasis and dysphonia (hoarseness, speaking difficulty). Both effects result from local deposition of inhaled glucocorticoids. To minimize these effects, patients should rinse the mouth with water and gargle after each administration. Using a spacer device can help too. If candidiasis develops, it can be treated with an antifungal drug.

                  With long-term, high-dose therapy, some adrenal suppression may develop, although the degree of suppression is generally low. In contrast, with prolonged use of oral glucocorticoids, adrenal suppression can be profound.

                  Glucocorticoids can slow growth in children and adolescents—but these drugs do not decrease adult height. Short-term studies have shown that inhaled glucocorticoids slow growth however, long-term studies indicate that adult height, although delayed, is not reduced. Less is known regarding whether glucocorticoids suppress growth and development of the brain, lungs, and other organs, in part because having asthma alone can affect organ growth. Because the benefits of inhaled glucocorticoids tend to be much greater than the risks, current guidelines for asthma management recommend these drugs for children while monitoring for evidence of complications.

                  Long-term use of inhaled glucocorticoids may promote bone loss. Fortunately, the amount of loss is much lower than the amount caused by oral glucocorticoids. To minimize bone loss, patients should (1) use the lowest dose that controls symptoms, (2) ensure adequate intake of calcium and vitamin D, and (3) participate in weight-bearing exercise.

                  There has been concern that prolonged therapy might increase the risk for cataracts and glaucoma. Although this may be an issue of concern with continuous use of high-dose inhaled glucocorticoids, this problem is not associated with long-term use of low to medium doses of inhaled glucocorticoids.

                  Inform patients that glucocorticoids are intended for preventive therapy—not for aborting an ongoing attack. Instruct patients to administer glucocorticoids on a regular schedule—not PRN.

                  Instruct patients on the proper use of inhalers. Have patients demonstrate proper technique. If patients are prescribed both a SABA and a glucocorticoid, explain that delivery of glucocorticoids to the bronchial tree can be enhanced by inhaling a SABA 5 minutes before inhaling the glucocorticoid.

                  Teach patients with chronic asthma to monitor and record PEF, symptom frequency and symptom intensity, nighttime awakenings, effect on normal activity, and SABA use.

                  Advise patients to rinse their mouth and gargle after dosing to minimize dysphonia and oropharyngeal candidiasis.

                  Counsel patients to contact the clinic if they develop complications following a change from oral to inhaled glucocorticoids. Wearing a medical alert bracelet is advisable for patients who are at risk of adrenal insufficiency associated with long-term systemic use.

                  Advise patients to ensure adequate intake of calcium and vitamin D to decrease risk of bone loss. Performing weight-bearing exercise provides additional protection.

                  Oral Glucocorticoids

                  When used acutely (less than 10 days), even in very high doses, oral glucocorticoids do not cause significant adverse effects. However, prolonged therapy, even in moderate doses, can be hazardous. Potential adverse effects include adrenal suppression, osteoporosis, hyperglycemia, peptic ulcer disease, and, in young patients, growth suppression.

                  Adrenal suppression is of particular concern. As discussed in Chapter 56, prolonged glucocorticoid use can decrease the ability of the adrenal cortex to produce glucocorticoids of its own. This can be life-threatening at times of severe physiologic stress (e.g., surgery, trauma, or systemic infection). Because high levels of glucocorticoids are required to survive severe stress and because adrenal suppression prevents production of endogenous glucocorticoids, patients must be given increased doses of oral or IV glucocorticoids at times of stress. Failure to do so can prove fatal.

                  Compensating for Adrenal Insufficiency

                  When patients have been on prolonged systemic glucocorticoid therapy, the adrenal glands decrease their endogenous production of glucocorticoids. If systemic therapy is stopped suddenly, as when switching from oral therapy to inhalation therapy, the patient can die. Similarly, during times of severe physical stress when the body would normally produce high levels of glucocorticoids, if the dose of systemic glucocorticoids is not increased to compensate, the patient can die. What important lesson can you take from this? When discontinuing a systemic glucocorticoid, you must be sure it is done gradually to allow the body to resume producing the endogenous hormone. On the other hand, if a patient taking systemic glucocorticoids experiences severe physical stress, such as a motor vehicle crash, or is scheduled for a stressful procedure, such as surgery, you must prescribe additional glucocorticoids to supplement for the endogenous hormone that the patient cannot produce.

                  Adrenal suppression is also a concern when discontinuing prolonged use of oral glucocorticoids or when transferring from an oral route to an inhaled route. Several months are required for recovery of adrenocortical function, so it is important to decrease the dosage gradually. Throughout this time, all patients—including those switched to inhaled glucocorticoids—must be given supplemental oral or IV glucocorticoids at times of severe stress.

                  A complete list of contraindications to oral glucocorticoids is presented in the “Prescribing and Monitoring Considerations” section at the end of this chapter.

                  Preparations, Dosage, and Administration

                  Inhaled Glucocorticoids

                  Six glucocorticoids are available for inhalation (Table 60.2). Four are available in MDIs, three are available in DPIs, and one is available in suspension for nebulization. Inhaled glucocorticoids are administered on a regular schedule—not PRN. Pediatric and adult dosages are shown in Table 60.2. The dosage should be kept as low as possible to minimize adrenal suppression, possible bone loss, and other adverse effects.

                  Inhaled Glucocorticoids: Formulations and Dosages

                  Drug Formulation Adults Children
                  Beclomethasone dipropionate [QVAR] MDI: 40 or 80 mcg/inhalation 40–320 mcg twice daily 40–80 mcg twice daily (5–11 years)
                  [Pulmicort Flexhaler] DPI: 90 or 180 mcg/inhalation 360–720 mcg twice daily 180–360 mcg twice daily (6–17 years)
                  [Pulmicort Respules] Suspension for nebulization 250–500 mcg once or twice daily or 1000 mcg once daily 500–1000 mcg/day (1–8 years)
                  Ciclesonide [Alvesco] MDI: 80 or 160 mcg/inhalation 80–320 mcg twice daily 80–320 mcg twice daily (12 years and up)
                  Flunisolide [Aerospan] MDI: 80 mcg/inhalation 160–320 mcg twice daily 80–320 mcg twice daily (6–11 years)
                  Fluticasone propionate
                  [Flovent HFA] MDI: 44, 110, or 220 mcg/inhalation 88–440 mcg twice daily 88 mcg twice daily (4–11 years)
                  [Flovent Diskus] DPI: 50, 100, or 250 mcg/inhalation 100–1000 mcg twice daily 50–100 mcg twice daily (4–11 years)
                  Mometasone furoate [Asmanex Twisthaler] DPI: 110 or 220 mcg/inhalation 220–440 mcg once or twice daily 110 mcg once daily (4–11 years)

                  DPI, dry-powder inhaler MDI, metered-dose inhaler.

                  Nebulized Budesonide

                  Budesonide suspension [Pulmicort Respules] is the first inhaled glucocorticoid formulated for nebulized dosing. The product is approved for maintenance therapy of persistent asthma in children 1 to 8 years old. Improvement should begin in 2 to 8 days maximal benefits may take 4 to 6 weeks to develop. Budesonide suspension is available in 2-mL ampules containing 250 or 500 mcg of the drug. Administration is done with a jet nebulizer equipped with a mouthpiece or face mask ultrasonic nebulizers should not be used. Administration takes 5 to 10 minutes. For children who are not taking an oral glucocorticoid, the initial dosage is 500 mcg/day in one or two doses. For children who are taking an oral glucocorticoid, the initial dosage is 1000 mcg/day in one or two doses. After 1 week, dosage of the oral glucocorticoid should be tapered off.

                  Oral Glucocorticoids

                  Methylprednisolone, prednisone, and prednisolone are preferred glucocorticoids for oral therapy of asthma. The dosage is the same regardless of the drug.

                  When beginning therapy with oral glucocorticoids, dosing initially focuses on bringing symptoms under control. The National Asthma Education and Prevention Program (NAEPP) guidelines recommend an initial burst of 40 to 60 mg administered daily for 3 to 10 days for adults. The initial pediatric dosage is 1 to 2 mg/kg/day for 3 to 10 days. Thereafter, the typical dose is 0.25 to 2 mg/kg daily or every other day for children younger than 12 years and 7.5 to 60 mg daily or every other day for older children and adults. For long-term treatment, alternate-day dosing is recommended to minimize adrenal suppression. After symptoms have been controlled for 3 months, dosages should be decreased gradually to establish the lowest dosage that can keep the patient free of symptoms. As discussed previously, the dosage of oral glucocorticoids must be increased during times of stress.

                  Leukotriene Modifiers

                  Leukotrienes modifiers suppress the effects of leukotrienes, which are compounds that promote smooth muscle constriction, blood vessel permeability, and inflammatory responses through direct action as well as through recruitment of eosinophils and other inflammatory cells. In patients with asthma, these drugs can decrease bronchoconstriction and inflammatory responses such as edema and mucus secretion.

                  Three leukotriene modifiers are currently available: zileuton, zafirlukast, and montelukast. Zileuton blocks leukotriene synthesis zafirlukast and montelukast block leukotriene receptors. All three drugs are dosed orally. Current guidelines recommend using these agents as second-line therapy (if an inhaled glucocorticoid cannot be used) and as add-on therapy when an inhaled glucocorticoid alone is inadequate. Although generally well tolerated, all of the leukotriene modifiers can cause adverse neuropsychiatric effects, including depression, suicidal thinking, and suicidal behavior.


                  Zileuton [Zyflo, Zyflo CR], an inhibitor of leukotriene synthesis, is approved for asthma prophylaxis and maintenance therapy in adults and children 12 years and older. Symptomatic improvement can be seen within 1 to 2 hours of dosing. Because effects are not immediate, zileuton cannot be used to abort an ongoing attack. Zileuton is less effective than an inhaled glucocorticoid alone and appears to be less effective than a long-acting inhaled beta 2 agonist as adjunctive therapy in patients not adequately controlled with an inhaled glucocorticoid.

                  Mechanism of Action

                  Benefits derive from inhibiting 5-lipoxygenase, the enzyme that converts arachidonic acid into leukotrienes. This decreases the amount of leukotrienes available to induce inflammation.


                  Zileuton is given orally and undergoes rapid absorption, in both the presence and absence of food. Plasma levels peak 2 to 3 hours after dosing. Zileuton is rapidly metabolized by the liver, and the metabolites are excreted in the urine. Its plasma half-life is 2.5 hours.

                  Adverse Effects

                  Zileuton can injure the liver, as evidenced by increased plasma levels of alanine aminotransferase (ALT) activity. A few patients have developed symptomatic hepatitis, which reversed after drug withdrawal. To reduce the risk for serious liver injury, ALT activity should be monitored. The recommended schedule is once a month for 3 months, then every 2 to 3 months for the remainder of the first year, and periodically thereafter.

                  Postmarketing reports indicate that zileuton and the other leukotriene modifiers can cause adverse neuropsychiatric effects, including depression, anxiety, agitation, abnormal dreams, hallucinations, insomnia, irritability, restlessness, and suicidal thinking and behavior. If these develop, switching to a different medication should be considered.

                  Zileuton is metabolized by cytochrome P450, where it acts as an inhibitor of CYP1A2 isoenzymes and can slow metabolism of drug substrates metabolized by this pathway, increasing their levels. Combined use with theophylline can markedly increase theophylline levels, so dosage of theophylline should be reduced. Zileuton can also increase levels of warfarin and propranolol.

                  Preparations, Dosage, and Administration

                  Zileuton is available in 600-mg immediate-release tablets, sold as Zyflo, and 600-mg extended-release tablets, sold as Zyflo CR. With the immediate-release tablets, the recommended dosage is 600 mg 4 times a day. With the extended-release tablets, the recommended dosage is two 600 mg tablets twice a day, taken within 1 hour of the morning and evening meals.


                  Zafirlukast [Accolate] was the first representative of a unique group of antiinflammatory agents, the leukotriene receptor antagonists. The drug is approved for maintenance therapy of chronic asthma in adults and children 5 years and older.

                  Mechanism of Action

                  Benefits derive in part from reduced infiltration of inflammatory cells, resulting in decreased bronchoconstriction.


                  Zafirlukast is administered orally, and absorption is rapid. Food reduces absorption by 40% therefore, the drug should be administered at least 1 hour before meals or 2 hours after. Zafirlukast undergoes hepatic metabolism followed by fecal excretion. The half-life is about 10 hours but may be as long as 20 hours in older adults.

                  Adverse Effects

                  The most common side effects of zafirlukast are headache and gastrointestinal (GI) disturbances, both of which are infrequent. Arthralgia and myalgia may also occur. Like zileuton, zafirlukast can cause depression, suicidal thinking, hallucinations, and other neuropsychiatric effects. A few patients have developed Churg-Strauss syndrome, a potentially fatal disorder characterized by weight loss, flu-like symptoms, and pulmonary vasculitis (blood vessel inflammation). However, in most cases, symptoms developed when glucocorticoids were being withdrawn, suggesting that glucocorticoid withdrawal may be a contributing factor.

                  Rarely, patients develop clinical signs of liver injury (e.g., abdominal pain, jaundice, fatigue). If these occur, zafirlukast should be discontinued, and liver function tests (especially serum ALT) should be performed immediately. If test results are consistent with liver injury, zafirlukast should not be resumed. Curiously, signs of liver injury have developed mainly in females.

                  Zafirlukast inhibits several isoenzymes of cytochrome P450 and can suppress metabolism of other drugs, causing their levels to rise. Concurrent use can raise serum theophylline to toxic levels. Theophylline levels should be closely monitored, especially when zafirlukast is started or stopped. Zafirlukast can also raise levels of warfarin (an anticoagulant) and thus may cause bleeding.

                  Preparations, Dosage, and Administration

                  Zafirlukast is available in 10- and 20-mg tablets. The dosage for adults and children 12 years and older is 20 mg twice a day. The dosage for children age 5 to 11 years is 10 mg twice a day. Zafirlukast should not be administered with food.


                  Montelukast [Singulair], a leukotriene receptor blocker, is the most commonly used leukotriene modulator. The drug has three approved indications: (1) prophylaxis and maintenance therapy of asthma in patients at least 1 year old (2) prevention of exercise-induced bronchospasm (EIB) in patients at least 15 years old and (3) relief of allergic rhinitis (see Chapter 61). Montelukast cannot be used for quick relief of an asthma attack because effects develop too slowly. For prophylaxis and maintenance therapy of asthma, maximal effects develop within 24 hours of the first dose and are maintained with once-daily dosing in the evening. In clinical trials, montelukast decreased asthma-related nocturnal awakening, improved morning lung function, and decreased the need for a short-acting inhaled beta 2 agonist throughout the day. Although montelukast is approved for preventing EIB, a short-acting beta 2 agonist is preferred.

                  Mechanism of Action

                  Montelukast has a high affinity for leukotriene receptors in the airway and on proinflammatory cells such as eosinophils. By occupying these receptors, the drug blocks receptor activation by the body’s leukotrienes.


                  Montelukast is rapidly absorbed after oral administration. Bioavailability is about 64%. Blood levels peak 3 to 4 hours after ingestion. The drug is highly bound (more than 99%) to plasma proteins. Montelukast undergoes extensive metabolism by hepatic cytochrome P450 enzymes followed by excretion in the bile. The plasma half-life ranges from 2.7 to 5.5 hours.

                  Adverse Effects

                  Montelukast is generally well tolerated. In clinical trials, adverse effects were equivalent to those of placebo. In contrast to zileuton and zafirlukast, montelukast does not seem to cause liver injury. As with zafirlukast, Churg-Strauss syndrome has occurred when glucocorticoid dosage was reduced. Postmarketing reports suggest a link between montelukast and neuropsychiatric effects, especially mood changes and suicidality. Fortunately, these effects are rare.

                  Montelukast appears devoid of serious drug interactions. Unlike zileuton and zafirlukast, it does not increase levels of theophylline or warfarin. Concurrent use of phenytoin (an anticonvulsant that induces P450 isoenzymes) can decrease levels of montelukast.

                  Preparations, Dosage, and Administration

                  Montelukast is available in three formulations: standard tablets (10 mg), chewable tablets (4 and 5 mg), and oral granules (4 mg/packet). The oral granules may be put directly in the mouth or may be mixed with one spoonful of either applesauce, carrots, rice, or ice cream. For prophylaxis or chronic treatment of asthma, dosing is done once a day in the evening, with or without food. Dosage is based on patient age as follows:

                  • Age 15 years and older—one 10-mg tablet daily

                  • Age 6 to 14 years—one 5-mg chewable tablet daily

                  • Age 2 to 5 years—one 4-mg chewable tablet or 4 mg of oral granules daily

                  • Age 12 to 23 months—4 mg of oral granules daily

                  To prevent EIB, patients should take one 10-mg tablet at least 2 hours before exercising. No additional dose should be taken for at least 24 hours. Patients already taking montelukast daily should not take any more to prevent EIB.


                  Cromolyn is an inhalational agent that suppresses bronchial inflammation. The drug is used for prophylaxis—not quick relief—in patients with mild to moderate asthma. Antiinflammatory effects are less than with glucocorticoids therefore, cromolyn is not a preferred drug for asthma therapy. When glucocorticoids create problems, however, cromolyn may be prescribed as alternative therapy.

                  Mechanism of Action

                  Cromolyn suppresses inflammation it does not cause bronchodilation. The drug acts in part by stabilizing the cytoplasmic membrane of mast cells, preventing release of histamine and other mediators. In addition, cromolyn inhibits eosinophils, macrophages, and other inflammatory cells.


                  Cromolyn is administered by nebulizer. The fraction absorbed from the lungs is small and rarely produces significant systemic effects. Absorbed cromolyn is excreted unchanged in the urine.

                  Therapeutic Uses

                  Chronic Asthma

                  Cromolyn is an alternative to inhaled glucocorticoids for prophylactic therapy of mild persistent asthma. When administered on a fixed schedule, cromolyn reduces both the frequency and intensity of asthma attacks. Maximal effects may take several weeks to develop. No tolerance to effects is seen with long-term use. Cromolyn is especially effective for prophylaxis of seasonal allergic attacks and for acute allergy prophylaxis immediately before allergen exposure (e.g., before mowing the lawn).

                  Exercise-Induced Bronchospasm

                  Instruct patients on the proper use and care of nebulizers.

                  For acute prophylaxis, instruct patients to administer cromolyn 15 minutes before exercise and exposure to other precipitating factors (e.g., cold, environmental agents).

                  For long term use, instruct patients to administer cromolyn on a regular schedule. Be sure to inform them that full therapeutic effects may take several weeks to develop.

                  Teach patients with chronic asthma to monitor and record PEF, symptom frequency and symptom intensity, nighttime awakenings, effect on normal activity, and SABA use.

                  Cromolyn can prevent bronchospasm in patients at risk for EIB. For best results, cromolyn should be administered 10 to 15 minutes before anticipated exertion but no longer than 1 hour before exercise.

                  Allergic Rhinitis

                  Intranasal cromolyn [NasalCrom] can relieve symptoms of allergic rhinitis (see Chapter 61).

                  Adverse Effects

                  Cromolyn is the safest of all antiasthma medications. Significant adverse effects occur in fewer than 1 of every 10,000 patients. Occasionally, cough or bronchospasm occurs in response to cromolyn inhalation.

                  Preparations, Dosage, and Administration

                  Cromolyn is administered using a power-driven nebulizer. The initial dosage for adults and children is 20 mg 4 times a day. For maintenance therapy, the lowest effective dosage should be established.


                  Omalizumab [Xolair] is a monoclonal antibody with a unique mechanism of action: antagonism of IgE, a type of antibody. The drug is a second-line agent indicated only for allergy-related asthma and only when preferred options have failed. Omalizumab offers modest benefits and has significant drawbacks: the drug poses a risk for anaphylaxis and cancer, must be given subcutaneously, and costs more than $10,000 a year. Furthermore, its long-term safety is unknown.

                  Mechanism of Action

                  Omalizumab forms complexes with free IgE in the blood and thereby reduces the amount of IgE available to bind with its receptors on mast cells. This greatly reduces the number of IgE molecules on the mast cell surface and thus limits the ability of allergens to trigger release of histamine, leukotrienes, and other mediators that promote bronchospasm and airway inflammation. At recommended doses, omalizumab decreases free IgE in serum by 96%. When treatment stops, about 1 year is required for free IgE to return to its pretreatment level.

                  What is the effect of Montelukast on the amount of IgE in blood? - Biology

                  Montelukast and zafirlukast are cysteinyl leukotriene receptor antagonists indicated for the prevention and treatment of chronic asthma. This activity will highlight the mechanism of action, adverse event profile, and monitoring pertinent for members of the interprofessional team in the management of patients with asthma and related conditions with leukotriene receptor antagonists.

                  • Explain the mechanism of action of leukotriene receptor antagonists.
                  • Describe the potential adverse effects of leukotriene receptor antagonists.
                  • Review the appropriate monitoring for patients using leukotriene receptor antagonists.
                  • Summarize interprofessional team strategies for improving care coordination and communication to advance the treatment of asthma with leukotriene receptor antagonists and improve outcomes.


                  Montelukast and zafirlukast are cysteinyl leukotriene receptor antagonists.[1] Leukotrienes are eicosanoid inflammatory mediators derived from arachidonic acid. Montelukast's indications are the prophylaxis and chronic treatment of asthma, the prevention of exercise-induced bronchospasm, and the relief of symptoms of allergic rhinitis.[2][3]

                  Montelukast monotherapy is not recommended for first-line therapy for allergic rhinitis.[4] Instead, monotherapy with an intranasal glucocorticoid is a strong recommendation in the initial treatment of patients with moderate/severe seasonal allergic rhinitis who are 12 years of age or older and not treated previously.[5] The role of montelukast in an effective treatment for eczema remains inconclusive.[6]

                  Parents of asthmatic children prefer montelukast because the once-a-day oral dosage is more convenient than inhaler use. It also avoids the concerns regarding the side effects of long-term use of corticosteroids, such as growth retardation and metabolic abnormalities.

                  Zafirlukast indications include the prophylaxis and chronic treatment of asthma in children five years and older and adults. It is used off-label for allergic rhinitis and the prophylaxis of exercise-induced bronchospasm.

                  The first-line therapy for the prophylaxis of exercise-induced bronchospasm is inhaled short-acting beta-agonist such as albuterol. Daily use of inhaled corticosteroid or leukotriene receptor antagonists, such as montelukast and zafirlukast, is recommended in patients with exercise-induced bronchospasm who inhaled preventative short-acting beta-agonist but continue to have symptoms or who develop tolerance to continued usage of short-acting beta-agonist.[7]

                  Both montelukast and zafirlukast have no role as rescue medication during an acute asthmatic attack.[8] Instead, inhaled beta-agonist induces immediate bronchodilation.

                  Mechanism of Action

                  The main indication for leukotriene receptor antagonists is in the treatment of chronic asthma. Leukotrienes are synthesized from arachidonic acid by the action of 5-lipoxygenase in many inflammatory cells in the airways.[9] Arachidonic acid is released from cell membrane phospholipids mainly by phospholipase A2.[10] The cyclooxygenase pathway produces thromboxane and prostaglandins from arachidonic acid. Corticosteroids inhibit phospholipase A2 and subsequent synthesis of eicosanoid inflammatory mediators, including both prostaglandins and leukotrienes. Non-steroidal anti-inflammatory drugs such as aspirin inhibit cyclooxygenases. Zileuton inhibits 5-Lipoxygenase.

                  There are two groups of leukotrienes: one with and the other without amino acid moieties.[1] Leukotriene B4 carries hydroxyl moiety only and binds to BLT receptors. The signaling pathway via G protein-coupled BLT receptor activation produces a potent chemotaxis response. Cysteinyl leukotrienes (LTC4, LTD4, and LTE4) have amino acid moiety and bind to cysteinyl leukotriene receptors (CysLT1 and CysLT2). Bronchoconstriction, vascular permeability, eosinophil recruitment, and chronic inflammation are mediated through the G protein-coupled activation of cysteinyl leukotriene receptors. Montelukast and zafirlukast are antagonists to cysteinyl leukotriene CysLT1 receptors but not to CysLT2 receptors. Research has shown that eosinophils are the main source of cysteinyl leukotrienes, and cysteinyl leukotrienes are very important in eosinophil recruitment.[11] Earlier studies have shown that cysteinyl leukotrienes also play an important role in airway remodeling in chronic asthma.[12]

                  Asthma is the most common chronic lung disease characterized by reversible bronchoconstriction, inflammation, and airway remodeling that results in hyperresponsiveness. Sympathomimetic agents such as beta-adrenergic receptor agonists are the therapeutic choice for treatment for acute bronchoconstriction. They activate beta two adrenergic receptors and relax airway smooth muscle cells. Short-acting beta2-selective agonists include albuterol, levalbuterol, terbutaline, metaproterenol, and pirbuterol. They sustain bronchodilation for 3-4 hours. Long-acting beta2-selective agonists with 12-hour durations of action include salmeterol and formoterol. Ultra-long-acting beta-agonists such as indacaterol, olodaterol, and vilanterol patients should take bambuterol only once a day. Because beta-agonists do not inhibit inflammatory responses, they do not have a role as monotherapy for control of persistent asthma and are frequently a second agent added to inhaled corticosteroids.[13]

                  Based on the inflammatory mechanism of asthma, several pharmacological agents with different modes of action have undergone development to treat this endotype of asthma. Exposure to allergen stimulates the synthesis of IgE driven by CD4+ T helper type 2 cells. The IgE antibodies bind to their receptors on the tissue mast cells and blood basophils.[14] On re-exposure to an allergen, the allergen cross-links the IgE antibodies on the immune cell surface. It triggers the release of preformed mediators of anaphylaxis and synthesis of inflammatory mediators. Cromolyn or nedocromil may prevent mast cell degranulation. However, these drugs are not commonly used in asthma treatment nowadays because they are less effective than inhaled corticosteroids. Histamine, tryptase, and arachidonic acid metabolites such as leukotrienes C4 and D4 and prostaglandin D2 are released and cause acute smooth muscle contraction and increased vascular permeability. Three to six hours later, more sustained bronchoconstriction occurs in the late asthmatic response. There are suggestions that the cytokines produced by type 2 immune response mediate late asthmatic response.[15]

                  Advances in understanding the molecular heterogeneity of asthma have revealed the importance of type 2 immune response mediated by T helper type 2 cells in the pathology of eosinophilic asthma.[16] Omalizumab is a monoclonal antibody that can reduce the amount of circulating IgE. IL-4, IL-5, and IL-13 mediate type 2 immune responses. Anti-IL-5 antibody mepolizumab minimizes the number and activity of eosinophils in the airway mucosa. Dupilumab is an anti-IL-4 receptor antibody.


                  Montelukast administration is via the oral route, without regard to food or meals. It should be taken a single dose in the evening in patients with asthma and both asthma and allergic rhinitis. For the treatment of allergic rhinitis, administration can be either morning or evening. For the prevention of exercise-induced asthma, it should be taken at least two hours before exercise. Patients should not take another dose within 24 hours.

                  Zafirlukast is administered orally. It should be taken 2 hours after or 1 hour before meals because food decreases bioavailability by 40%.

                  Adverse Effects

                  Montelukast is relatively well tolerated generally safe.[17] The most commonly observed side effects in patients aged 15 years and over were headaches, influenza infection, abdominal pain, cough, and dyspepsia. In children, diarrhea, nausea, laryngitis, pharyngitis, sinusitis, otitis, and viral infection may occur. Neuropsychiatric disorders, including depression, aggression, suicidal ideation, insomnia, anxiety, and nightmares, may occur.[18] Allergic granulomatous angiitis (Churg-Strauss syndrome) may also correlate with the use of montelukast, although there is not yet an established causal relationship.[19][20] There are some reports of serious adverse events due to angioedema, hypersensitivity, fatigue, confusional state, abnormal dreams, epilepsy, aggression, immune system disorder, hemorrhage, excoriation, eosinophil count increase, pain in extremity, and abdominal pain.[18] In an animal study, it did not produce teratogenic effects at doses much higher than the maximum daily dose in humans.[17]

                  Zafirlukast is generally well tolerated, and associated adverse events are minimal.[21] Headache, upper respiratory tract infection, gastrointestinal disturbances such as nausea, vomiting, dyspepsia, abdominal pain, diarrhea, and malaise are common adverse effects.[21] Rarely, the elevation of liver enzymes, acute hepatitis, and hyperbilirubinemia has been linked to zafirlukast.[22][23]


                  Both montelukast and zafirlukast are contraindicated in patients with hypersensitivity to the drug or any component of their formulation. Contraindications to zafirlukast also include patients with hepatic impairment.


                  Depression, aggression, and other behavioral changes have correlations with the leukotriene receptor antagonists. Careful monitoring is necessary for patients treated with leukotriene receptor antagonists.

                  Zafirlukast may cause severe but rare acute liver damage. It is a major substrate of the cytochrome P450 CYP2C9 enzyme. Patients receiving concomitant therapy with drugs such as alpelisib, dabrafenib, enzalutamide, erythromycin, loxapine, lumacaftor, rifapentine, terfenadine, and warfarin require monitoring for potential drug interactions.[24]


                  Both montelukast and zafirlukast have a wide margin of safety. Patients who took an overdose had no adverse symptoms, an uneventful course of recovery, or a rash and upset stomach.[25][26]

                  When overdosed, remove unabsorbed drugs using active charcoal and institute supportive therapy, if needed.

                  Enhancing Healthcare Team Outcomes

                  Several adverse drug reactions were reported to the Netherlands pharmacovigilance center Lareb and the WHO global individual case safety report database. The most common adverse effect in the whole population was depression, and in children under the age of 19 years, it was aggression.[18] Suicidal ideation, abnormal behavior, nightmares, headaches, insomnia, and anxiety have been reported in patients treated with montelukast. Nightmares may frighten children. Aggression and abnormal behavior of children may cause concerns from their parents and teachers. Insomnia in adults may impact the safety of the patients and others. The interprofessional healthcare team should educate their patients or parents and monitor the incidence of adverse drug effects.

                  Asthma is a chronic lung disease. Even in patients with a well-established medication regimen, acute asthma exacerbations may occur. Understanding the risk factors for exacerbation-prone asthma is critical for the prevention of potentially fatal acute asthma attacks.[27][28]

                  Both African Americans and Hispanics have a higher incidence of exacerbations. Poor compliance with medication due to patient&rsquos poor access to healthcare and inadequate education and knowledge about the disease put the patients at great risk of acute exacerbations. Other potentially modifiable risk factors include uncontrolled allergies, upper respiratory viral infections, obesity, smoking, and gastroesophageal reflux disease.[29][30][31][32] Interprofessional approaches by all healthcare team members, including clinicians, mid-level practitioners, specialists, nurses, pharmacists, and respiratory therapists, may reduce acute asthma attacks by taking control of these risk factors.


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