Levels Of Mast Cell Mediators Research Articles

Targeting the RhoA-GEF-H1 pathway of mast cells attenuates experimental airway allergy

Mast cells are the major effector cells in allergic diseases. RhoA and its downstream pathway is associated with the pathogenesis of airway allergy. The objective of this study is to test a hypothesis that modulating the RhoA-GEF-H1 axis in mast cells can attenuate airway allergy. An airway allergic disorder (AAD) mouse model was employed. Mast cells were isolated from AAD mouse airway tissues to be analyzed by RNA sequencing. We observed that mast cells isolated from the respiratory tract of AAD mice were resistant to apoptosis. Mast cell mediator levels in nasal lavage fluid were correlated with apoptosis resistance in AAD mice. Activation of RhoA in AAD mast cells was related to resistance to apoptosis. Mast cells isolated from the airway tissues in AAD mouse exhibited strong RhoA-GEF-H1 expression. The RhoA-GEF-H1 axis was associated with the lower FasL expression in AAD mast cells. Activation of the RhoA-GEF-H1 axis promoted the production of mediators in mast cells. Inhibition of GEF-H1 facilitated the SIT-induced mast cell apoptosis and enhanced the therapeutic efficacy of AAD. In conclusion, RhoA-GEF-H1 activities are associated with resistance to apoptosis in mast cells isolated from sites of allergic lesions. The state of apoptosis resistance in mast cells is associated with the state of AAD disease. Inhibition of GEF-H1 restores the sensitivity of mast cells to apoptosis inducers, and alleviates experimental AAD in mice.

Differential mast cell mediators in systemic mastocytosis and hereditary α-tryptasemia

Patients with systemic mastocytosis often have symptoms of mast cell activation, which is associated with elevated levels of urinary mast cell mediator metabolites. Patients with hereditary α-tryptasemia (HαT) may present with symptoms of mast cell activation. Whether levels of mast cell mediators are elevated in this patient population is not known. The purpose of this study was to determine whether patients with HαT and symptoms of mast cell activation have elevated levels of urinary mediators and compare the levels with those in patients with systemic mastocytosis. We retrospectively analyzed mast cell mediators in 63 patients with a confirmed diagnosis of HαT, 20 patients with a confirmed diagnosis of indolent systemic mastocytosis (ISM), and 23 healthy controls. All patients were referred to the Brigham and Women's Hospital Mastocytosis Center or the Mayo Clinic for evaluation of mast cell activation disorders. Our population was predominantly female (85.7%) with an average age of 53.8 years. The average baseline serum tryptase level was significantly higher in patients with ISM than in those with HαT (65.9 vs 19.3 ng/mL [P< .01]). When compared with patients with HαT, those with ISM had statistically significant increases in their levels of urinary N-methylhistamine (P< .01) and 2,3-dinor-11β-prostaglandin F2α (P< .05). Patients with symptomatic HαT do not have elevations of mast cell urinary metabolites, suggesting that granule- and membrane-derived mediators may not drive symptoms in HαT.

Mediator production and severity of aspirin-induced respiratory reactions: Impact of sampling site and body mass index

Patients with aspirin-exacerbated respiratory disease can experience severe reactions during aspirin challenge that are associated with high levels of mast cell mediators. The tissue source and clinical factors contributing to systemic mediator levels are unknown. We sought to determine the concordance between respiratory tract and systemic inflammatory mediator levels and identify clinical factors associated with these mediators. We performed an oral aspirin challenge in 30 subjects with aspirin-exacerbated respiratory disease. Respiratory symptoms and function, nasal mucosal fluid, blood, and urine were collected at baseline, at the onset of a respiratory reaction, and over a 3-hour observation period. Changes in nasal and systemic mediator levels were compared. Neither tryptase nor leukotriene E4 levels in nasal fluid correlated with serum tryptase or urinary leukotriene E4 levels at baseline or during reactions. We observed no association between the baseline or aspirin-induced change in nasal versus urinary leukotriene E4 and serum tryptase levels. Body mass index inversely correlated with baseline and aspirin-induced urinary leukotriene E4, prostaglandin D2 metabolite, and serum tryptase levels, as well as with aspirin-induced symptoms and respiratory function, but not with nasal mediators. The levels of nasal and systemic aspirin-induced mast cell products are discordant in aspirin-exacerbated respiratory disease. Systemically detected levels are likely derived from mast cells outside of the sinonasal cavity and do not accurately reflect upper respiratory tract production. Increased body mass index decreases systemic mast cell mediator production and reaction severity, supporting a contribution of metabolic regulation in aspirin-induced systemic reactions.

Pediatric Mast Cell Activation Syndrome

Patients with mast cell activation syndrome(MCAS) have symptoms consistent with mast cell mediator release, elevation of mast cell(MC) mediator(s) and symptomatic resolution following medications that block MC mediator effect(s). MC mediator levels in pediatric mast cell disorders are unknown. Our hypothesis is that the pattern of mast cell mediator(s) elevation in pediatric MCAS resembles adult MCAS. A retrospective chart review of 104 children who underwent evaluation for MCAS (2015-2017) was performed. Levels of serum tryptase, urinary n-methyl-histamine(n-MH), 2,3-dinor11β-prostaglandin-F2α(PG-D2), and leukotriene E4(LTE4) are reported. Thirty-two patients had ≥1 elevated urine MC mediators, based on established adult reference intervals. Of this total, 1 patient had systemic mastocytosis, 4 patients had cutaneous mastocytosis, and 6(6%) patients had MCAS. The average age at diagnosis was 9±5years. Serial testing in two patients with normal baseline revealed an elevated urine mast cell mediator level during an episode; one of those patients (with suspected familial hypertryptasemia) had PG-D2 elevation and the other LTE4 elevation. Five patients (83%) had at least 2 elevated MC mediators. More patients had an elevated PG-D2 (n=5) compared to serum tryptase(n=2). There was a greater percentage of patients that had elevated PG-D2 compared to an elevated serum tryptase for flushing(80-vs-50%), diarrhea(100-vs-100%), and abdominal pain(100%-vs-50%). There was a greater percentage of patients with elevated tryptase compared PG-D2 for pruritus(100-vs-60%) and urticaria(50-vs-40%). Urinary PG-D2 is the most frequently elevated product in our pediatric MCAS cohort, resembling adult MCAS. We recommend measurement of all MC mediators in patients with symptoms suggestive of MCAS.

Patient Reported Symptoms and Tryptase Levels in WHO-Defined Systemic Mastocytosis (SM) Versus Mast Cell Activation Syndrome (MCAS) Versus Neither

Introduction: The utility of patient reported symptoms and serum tryptase levels in distinguishing those with systemic mastocytosis (SM) versus mast cell activation syndrome (MCAS) versus those not meeting formal diagnostic criteria for SM or MCAS has not been systematically examined.Methods: This study was approved by our institutional review board. Patients were referred for suspected SM based on symptoms of mast cell activation, osteopenia, skin rash, etc., or had an established diagnosis of SM. All patients were given a Mastocytosis Symptom Assessment Form (MastSAF) to complete at their initial evaluation. The MastSAF is comprised of 36 symptom questions to be graded on a scale of 0 (absent) to 10 (worst imaginable), and is organized around 9 symptom clusters: gastrointestinal (8 questions), constitutional (3 questions), musculoskeletal (5 questions), cutaneous (4 questions), neuropsychological (6 questions), genitourinary (3 questions), respiratory (4 questions), angioedema (1 question), and cardiovascular (2 questions). All patients underwent bone marrow biopsy and serum tryptase level assessment. SM was diagnosed by 2008 WHO criteria. In the presence of characteristic symptoms, if clonal or abnormal mast cells were not identified, and if serum/urine mast cell mediator levels were increased, then non-SM associated, non-monoclonal MCAS was diagnosed.Results: A total 53 patients were studied.1) SM: Of 28 patients, 13 had indolent SM (ISM), 9 aggressive SM (ASM) and 6 SM with associated hematological disease (SM-AHD)The median total symptom score was 47 (range 8-159). The median (range) for SM subgroups was: ISM 51 (9-159), ASM 55 (19-157) and SM-AHD 27 (8-131) (p=0.2). The normalized median score for individual symptom categories (total median score/no. of symptoms per category) in order of severity was cutaneous 1.9, gastrointestinal 1.8, constitutional 1.7, neuropsychological 1.3, respiratory 1.3, musculoskeletal 0.9, cardiovascular 0.3, genitourinary 0.3, and angioedema 0. Symptom severity was not significantly different among the 3 SM subgroups, except for constitutional symptoms (median score ASM 9, ISM 4, SM-AHD 2.5, p=0.02).The median (range) tryptase level was 48.4 ng/mL (8.8-282); four patients (14%) had a baseline level <20 ng/mL. The median (range) tryptase level among SM subgroups was: ISM 46.9 (8.8-225), ASM 103 (29.4-282), and SM-AHD 43.5 (28.5-233) (p=0.1). When considering patients with tryptase level ≥50 versus <50 ng/mL, symptom scores were not significantly higher in the former group with the exception of constitutional (p=0.02) and genitourinary symptoms (p=0.04).2) MCAS: 15 patientsThe median total symptom score was 127 (range 2-248). The normalized median score for individual symptom categories in order of severity was neuropsychological 4.5, musculoskeletal 4.2, cutaneous 4.0, constitutional 3.3, gastrointestinal 2.1, respiratory and cardiovascular 2.0 each, genitourinary 1.7, and angioedema 1.0.The median (range) serum tryptase level at referral was 12.7 ng/mL (1.7-25.8); five patients (33%) had a baseline level >20 ng/mL.3) Neither SM/MCAS: 10 patientsThe median total symptom score was 119 (range 45-177). The normalized median score for individual symptom categories in order of severity was musculoskeletal 4.2, gastrointestinal 3.6, constitutional 3.3, neuropsychological 3.3, cutaneous 3.0, cardiovascular and genitourinary 2.0 each, respiratory 1.3, and angioedema 0.The median (range) serum tryptase level at referral (n=9) was 4.8 ng/mL (2.9-6.6).4) Comparison:MCAS vs. SM: Symptom scores were significantly higher in MCAS as compared to SM (p<0.05), except for genitourinary and respiratory symptoms, which were not significantly different.‘Neither SM/MCAS’ vs. SM: Symptom scores (total, gastrointestinal, constitutional, musculoskeletal, cutaneous, and neuropsychological) were significantly higher in the former group (p<0.05). Other symptom scores were not significantly different.Conclusions: The spectrum and severity of patient reported symptoms was broadly similar among WHO subcategories of SM, and serum tryptase level had limited if any correlation with symptom scores. Despite the significantly higher overall symptom burden in MCAS versus SM, tryptase levels in the former group were significantly lower with values >30 ng/mL unusual. Despite overlap, the top ranked symptoms in the 3 groups were different. DisclosuresNo relevant conflicts of interest to declare.

Acetylsalicylic acid potentiates passive systemic anaphylaxis in mice

Acetylsalicylic acid (ASA) is a nonsteroidal anti-inflammatory drug that can cause mast cell dependent diseases in sensitive individuals. ASA induced asthma is believed to be related to an overproduction of cysteinyl leukotriene C4 (LTC4) secondary to cyclooxygenase inhibition. It remains to be elucidated whether and by which mechanisms ASA may also influence systemic anaphylactic reactions. In order to clarify if ASA modulates passive systemic anaphylaxis (PSA), Balb/c mice were pre-treated with ASA, sensitized with anti-TNP-BSA intravenously followed by intravenous challenge with TNP-BSA. The temperature profile was assessed for 70 min. Levels of mast cell mediators in the sera (histamine, serotonin, LTC4) were determined by ELISA. Additionally murine bone marrow-derived cultured and peritoneal mast cells were incubated in vitro with ASA, loaded with IgE, stimulated with anti-IgE and histamine release was assessed. ASA aggravated the symptoms of PSA; the maximum temperature drop for ASA pre-treated mice was 5.1 ± 0.4 versus 3.7 ± 0.5 in the control (p = 0.004). In line with exacerbated hypothermia, elevated amounts of mast cell mediators were found in mouse sera. LTC4 was enhanced and most interestingly, increases in the preformed mediators histamine and serotonin were likewise detected. Contrary to these findings the histamine release of mast cells incubated with ASA in vitro was reduced. Together, ASA potentiates PSA probably by enhancing the degranulation of mast cells in vivo, thereby increasing the availability of anaphylactic mediators. Since ASA suppresses mast cell activation in vitro, the environment surrounding the mast cells dictate most likely changes in the releasability of these effector cells upon ASA treatment. Our findings emphasize the importance of in vivo models to study anaphylaxis as only in vivo experiments can unravel the complex interplay of different cells and tissue factors.

Prehepatic portal hypertension produces increased mast cell density in the small bowel and in mesenteric lymph nodes in the rat

Because most of the characteristics of the portal hypertensive enteropathy can be explained on the basis of increased levels of mast cell mediators, the purpose of the present paper was to study mast cell splanchnic infiltration. Duodenum, jejunum, ileum and mesenteric lymph node complex infiltration by mast cells was assayed by a stereological technique in control rats (group I; n = 5) and in an experimental model of portal hypertension (the portal vein-stenosed rat, group II; n = 5) at 6 weeks after operation. Intestinal and mesenteric lymph node complex infiltration by mast cells increased in the animals with partial portal vein ligation. The mast cell density progressively increased distally along the small bowel. The mast cell increase in the mesenteric lymph node complex in portal vein-stenosed rats was greater than in the duodenum (P = 0.001), jejunum (P = 0.006) and ileum. The rise of mast cells density in the small bowel and mesenteric lymph node complex in rats with partial portal vein ligation suggests that these cells are involved in the etiopathogenesis of experimental portal prehepatic hypertensive enteropathy.

Mast Cell-Dependent Control ofGiardia lambliaInfections in Mice

Mast cells are important for protective immunity to intestinal helminth infections and as mediators of allergic disease. Their role in protozoan infections is less well described. We have therefore analyzed mast cell responses and parasite control in mice infected with the protozoan Giardia lamblia. We also measured immunoglobulin A (IgA) responses to the parasite, as IgA can have a protective role in this model. c-kit w/wv mice failed to make parasite-specific IgA, mount a mast cell response, or eliminate the infection. Anti-c-kit-treated C57BL/6 mice had normal IgA responses, lacked mast cell responses, had reduced interleukin-6 (IL-6) mRNA in the small intestine, and failed to control the infection within 10 days. IL-9-deficient mice had a significant but reduced mast cell response and still controlled the infection within 2 weeks. Interestingly, IL-6-deficient mice had enhanced mast cell responses yet failed to rapidly control the infection. However, prevention of mast cell responses in IL-6-deficient mice by anti-c-kit treatment did not lead to parasite elimination. Both IL-6- and IL-9-deficient mice had normal IgA production. IL-6-deficient mice had significant serum levels of mast cell mediators, histamine and mast cell protease 1, following infection. Together, these results show that mast cells are important for the rapid control of Giardia infections in mice. Furthermore, they show that IL-6 is not necessary for these mast cell responses. Instead, they suggest that mast cell production of IL-6 appears to be important for control of this infection.

Mast cell mediator release in nonasthmatic subjects after endobronchial adenosine challenge

BackgroundAdenosine 5′-monophosphate (AMP) has been shown to cause bronchoconstriction in atopic subjects but to have no effect on nonatopic nonasthmatic subjects. Endobronchial AMP challenge has previously been shown to cause mast cell mediator release in asthmatic subjects, but it is unknown whether a similar response occurs in atopic nonasthmatic and nonatopic nonasthmatic control subjects who have no response to inhalation AMP challenge. ObjectiveThis study examined the change in mast cell–derived products after endobronchial saline challenge and AMP challenge in subjects with and without a positive inhalation response to AMP. MethodsInhalation challenge with AMP challenge was performed in normal, atopic nonasthmatic, and atopic asthmatic subjects. Levels of mast cell mediators were measured after endobronchial adenosine challenge and after placebo endobronchial saline challenge. ResultsThere were significant increases in histamine, tryptase, protein, and prostaglandin D2 levels (P=.02, P=.02, P=.01, and P=.01, respectively) after AMP challenge compared with after saline challenge in nonatopic nonasthmatic subjects. There was no significant increase in any mediator in either of the other 2 groups. ConclusionThis study suggests dissociation between mediator release and bronchoconstriction in response to AMP.

Histamine and tryptase in nasal lavage fluid after allergen challenge: Effect of 1 week of pretreatment with intranasal azelastine or systemic cetirizine

Background: Antihistamines (H 1 -receptor antagonists) act by competitive antagonism of histamine at H 1 -receptors. In addition, high concentrations of some antihistamines inhibit allergen-induced histamine release from mast cells in vitro. Objective: The purpose of this study was to determine the effect of intranasal azelastine or systemic cetirizine (both potent antihistamines) on the allergen-induced release of mast-cell mediators from the human nasal mucosa in vivo. Methods: Patients allergic to birch pollen (n = 11) and control subjects not allergic to birch pollen (n = 5) were included in a randomized, double-blind, placebo-controlled, 3-way crossover study outside the pollen season. Each subject was treated with azelastine nasal spray 0.14 mg per nostril twice daily, cetirizine tablets 10 mg every day, or placebo for 1 week using a double-dummy design. At the end of each treatment period, nasal allergen challenges were performed, and the number of sneezes were counted. In addition, nasal lavage fluid was collected, and the levels of mast-cell mediators (histamine and tryptase) were measured. Results: The allergen challenge of patients allergic to pollen produced sneezing and a significant increase in the levels of histamine and tryptase. The challenge of subjects not allergic to pollen produced no such response. Azelastine and cetirizine significantly reduced allergen-induced sneezing and the associated increase in histamine and tryptase levels. No significant differences were found between the azelastine and cetirizine treatments. Conclusion: Pretreatment with azelastine or cetirizine inhibits the allergen-induced release of mast-cell mediators from the human nasal mucosa. Our results are consistent with the hypothesis that both antihistamines reduce mediator release from nasal mucosa mast cells in vivo. However, further studies are necessary to test this hypothesis. (J Allergy Clin Immunol 1999;103:768-72.)

Mast Cell Activation in Children With Migraine Before and After Training in Self‐regulation

Migraine may affect as many as 9% of all schoolchildren and often presents with abdominal symptoms of pain, nausea, and vomiting. Even though the pathophysiology of migraine remains unknown, self-regulation techniques appear to be more effective in prevention of childhood migraine than conventional pharmacotherapy which is often associated with adverse effects. Mast cells have been implicated in the pathogenesis of migraine in adults, but have not been previously studied in children with migraine. Mast cells are found close to the vessels and nerves in the meninges where they can release multiple vasoactive, neurosensitizing, and pro-inflammatory mediators. Therefore, we investigated whether children with migraine may have increased urinary levels of mast cell mediators and whether practicing relaxation imagery exercises has an effect on the frequency of headache, as well as on mast cell activation. Urine was collected for 24 hours from children with and without migraine after a 5-day amine-restricted diet. Children with migraine also collected urine during migraine episodes. The mean levels of urinary histamine, its main metabolite, methylhistamine, and the mast cell enzyme, tryptase, were higher in children than generally found in adults, but they did not differ statistically in any of the categories studied. However, in 8 of 10 children who practiced relaxation imagery techniques and successfully reduced the number of migraines, the urine tryptase levels were also significantly lower. There was no relationship between successful practice and sex or age of the child. These results suggest that stress may activate mast cells which could be involved in the pathophysiology of migraine.

Investigations on plasma levels of mast cell mediators in acute atopic dermatitis

Skin mast cells have been proposed to be involved in the pathogenesis of acute and chronic phases of atopic dermatitis (AD). The aim of the present study was to investigate the significance of different mast cell mediators during acute exacerbation of this frequent skin disease. Plasma levels from 19 patients with AD were screened for elevation of the mast cell-specific protease tryptase, the biogene amine histamine, and the arachidonic acid metabolite prostaglandin D 2. None of the patients showed elevated plasma levels of these three mediators, whereas the mean serum IgE level was strongly elevated. We conclude that the investigated mediators are either only active on the cutaneous level or that other mediators are responsible for the development of the acute eczematous and pruritic skin reactions. Alternatively, the assays could have been insufficiently sensitive since some studies have demonstrated increased plasma histamine levels, e.g. after food challenge of such patients.