Mast Cell Histamine Release Research Articles

Absence of Tec family kinases Itk and Btk significantly impairs FcϵRI dependent mast cell responses (86.26)

Abstract While the etiology of asthma can be multi factorial, signaling through the IgE receptor (Fcϵ receptor I) on mast cells is critical to its onset. The Tec family tyrosine kinases ITK and BTK serve important roles as signal amplifiers downstream of the FcϵRI, however, their individual contribution to FcϵRI signaling has not been fully established. We have generated Itk and Btk double deficient (DKO) mice in an effort to determine the relative role of Itk and Btk to FcϵRI signaling in mast cells. Analyses of skin mast cells from these mice revealed reduced mast cell granule content and density. However, in vitro cultured bone marrow derived mast cells (BMMCs) had normal gross morphology and granule density. Mast cell histamine release was also compromised in DKO mice, likely associated with elevated endogenous IgE expression in these mice. In vitro growth analysis indicated that Btk negatively regulates BMMC growth as previously published, while the absence of both Itk/Btk did not further contribute to this phenotype. However, there was a significant reduction in FcϵRI mediated calcium responses, accompanied by reduced phosphorylation of PLCγ2 and the mitogen activated protein kinase p38. Lastly, a reduction in the production of several cytokines was also observed in DKO BMMCs. Our results suggest that Itk and Btk have redundant, complementary, and unique functions in mast cell FcϵRI signaling that could be pharmacologically manipulated to treat asthma.

Antagonistic Control of IgG-mediated Mast Cell Activation by Lyn and Fyn Kinases (86.8)

Abstract Mast cells are key players of the innate immune system. In addition to their role in atopic disease, mast cell involvement is strongly suspected in inflammatory diseases such as multiple sclerosis, rheumatoid arthritis, and atherosclerosis. Once activated, they degranulate and produce cytokines, resulting in the recruitment of other immune cells. It is well-appreciated that mast cells are activated via the high-affinity immunoglobulin E (IgE) receptor FcϵRI. In this study we focus on mast cell activation via the immunoglobulin G (IgG) receptor FcγRII/RIII and downstream signaling by Fyn and Lyn kinases. Lyn-deficient mast cells displayed increased FcγR expression, correlating with enhanced IgG-mediated histamine and leukotriene C4 secretion. The mast cells did not show a change in IgG-mediated cytokine production, suggesting a restricted and negative regulatory role for Lyn kinase in mast cell IgG signaling. In contrast, we show that Fyn kinase is rapidly activated by IgG crosslinkage, and is required for both IgG-mediated histamine release and cytokine production in mast cells. We obtained similar results when studying Lyn- or Fyn-deficient basophils and macrophages. Finally, we found that Lyn-deficient mice had exacerbated responses to passive systemic anaphylactic shock elicited by IgG challenge in vivo. These data illustrate the importance of Src family kinases in IgG signaling, a means by which mast cells may be activated in chronic inflammatory diseases.

TRPM7 kinase domain confers magnesium sensitivity to G-protein regulated mast cell degranulation (86.14)

Abstract TRPM7 is a bi-functional protein where an ion channel domain is fused with an atypical α-kinase domain. Impairment of the kinase domain leads to hypomagnesemia and sensitization to allergic reactions. We here investigate whether TRPM7 is involved in receptor-stimulated peritoneal mast cell degranulation and histamine release. Using the whole-cell patch clamp technique, we find that mimicking hypomagnesemic conditions by removal of extracellular Mg2+ shifts the degranulation response to intracellular Ca2+ from a graded to an all-or-none process independent of functional TRPM7 activity. In contrast, G-protein-induced mast cell degranulation requires higher intracellular Ca2+ levels in cells isolated from a mouse heterozygotic for a TRPM7 kinase domain knock-out (dKhet). Removal of extracellular Mg2+ compensates for this effect by both significantly increasing the degranulation amplitude and accelerating the rate of secretion in dKhet but not wild type (wt) cells. These observations are confirmed in a histamine release assay, where G-protein induced histamine secretion using MIP-1α is greatly enhanced in dKhet mast cells under hypomagensemic conditions, whereas Ca2+-induced degranulation by FcϵRI crosslinking is similar compared to wt. We conclude that Ca2+-induced mast cell activation is sensitive to extracellular Mg2+ concentrations independent of TRPM7 and that the TRPM7 kinase domain, but not the channel domain, is involved in G-protein-regulated degranulation.

Histamine release induced by antimicrobial agents and effects of antimicrobial agents on vancomycin-induced histamine release from rat peritoneal mast cells.

Vancomycin and certain fungicides may cause anaphylactoid reactions. We investigated the effects of vancomycin, miconazole and fluconazole on histamine release in rat peritoneal mast cells. Vancomycin and miconazole provoked histamine release in a dose-dependent manner. In contrast, fluconazole did not provoke histamine release at concentrations of 3 x 10(-6)-3 x 10(-3) M. Vancomycin is efficacious in the treatment of gram-positive bacterial infections; patients presenting themselves with mixed infections require concomitant therapy with a second antimicrobial agent. We investigated the effect of fosfomycin sodium, cilastatin sodium or fluconazole on vancomycin-induced histamine release. Fosfomycin sodium inhibited vancomycin-induced histamine release but neither cilastatin sodium nor fluconazole inhibited it in the mole ratios of daily doses used in humans. These results suggest that vancomycin and miconazole provoke histamine release in rat mast cells, but that fluconazole probably does not, while fosfomycin sodium may inhibit vancomycin-induced histamine release.

Paracetamol (acetaminophen) attenuates in vitro mast cell and peripheral blood mononucleocyte cell histamine release induced by N-acetylcysteine

Introduction. The treatment of acute paracetamol (acetaminophen) poisoning with N-acetylcysteine (NAC) is frequently complicated by an anaphylactoid reaction to the antidote. The mechanism that underlies this reaction is unclear. We used the human mast cell line 1 (HMC-1) and human peripheral blood mononucleocytes (PBMCs) to investigate the effects of NAC and paracetamol on histamine secretion in vitro. Method. HMC-1 and human PBMCs were incubated in the presence of increasing concentrations of NAC ± paracetamol. Cell viability was determined by the Trypan Blue Assay, and histamine secretion was measured by ELISA. Results. NAC was toxic to HMC-1 cells at 100 mg/mL and to PBMCs at 67 mg/mL. NAC increased HMC-1 and PBMC histamine secretion at concentrations of NAC from 20 to 50 mg/mL and 2.5 to 100 mg/mL, respectively. NAC-induced histamine secretion by both cell types was reduced by co-incubation with 2.5 mg/mL of paracetamol. Conclusion. Paracetamol (acetaminophen) is capable of modifying histamine secretion in vitro. This may explain the clinical observation of a lower incidence of adverse reactions to NAC in vivo when higher concentrations of paracetamol are present than when paracetamol concentrations are low. Paracetamol (acetaminophen) attenuates in vitro mast cell and PBMC cell histamine release induced by NAC.

Inhibitory effects of curcumin on passive cutaneous anaphylactoid response and compound 48/80-induced mast cell activation

Mast cells participate in allergies and inflammation by secreting a variety of pro-inflammatory mediators. Curcumin, the active component of turmeric, is a polyphenolic phytochemical with anti-tumor, anti-inflammatory, anti-oxidative, and anti-allergic properties. The effects of curcumin on compound 48/80-induced mast cell activation and passive cutaneous anaphylactoid reactions are unknown. In this report, we investigated the influences of curcumin on the passive cutaneous anaphylactoid response in vivo and compound 48/80-induced mast cell activation in vitro. The mechanism of action was examined by calcium uptake measurements and cAMP assays in mast cells. Curcumin significantly attenuated the mast cell-mediated passive cutaneous anaphylactoid reaction in an animal model. In agreement with this in vivo activity, curcumin suppressed compound 48/80-induced rat peritoneal mast cell (RPMC) degranulation and histamine release from RPMCs. Moreover, compound 48/80-elicited calcium uptake into RPMCs was reduced in a dose-dependent manner by curcumin. Furthermore, curcumin increased the level of intracellular cAMP and significantly inhibited the compound 48/80-induced reduction of cAMP in RPMCs. These results corroborate the finding that curcumin may have anti-allergic activity.

Diverse effects of bacterial cell wall components on mast cell degranulation, cysteinyl leukotriene generation and migration

Nowadays there is more and more evidence that mast cells take part in antibacterial defence. Mast cells have the ability to kill bacteria via phagocytose-dependent or phagocytose-independent ways and express antimicrobial peptides that can directly kill pathogens at their site of entry. What is more, mast cells are capable of processing bacterial antigens for presentation through class I and II MHC molecules. Some data indicate that these cells can release various proinflammatory mediators in response to activation with bacteria and/or their products, however this information is still far from complete. Therefore, in this study we examined the ability of PGN from Staphylococcus aureus, LPS from Eschericha coli and LAM from Mycobacterium smegmatis to stimulate mature rat mast cell degranulation as well as cysteinyl LT generation. We also studied the influence of these bacterial components on mast cell migration. We found that PGN, LPS and LAM all failed to induce mast cell degranulation and histamine release. At the same time, activation of mast cells with these bacterial antigens resulted in generation and release of significant amounts of LT. Moreover, we documented that, even in the presence of laminin, none of the bacterial antigens used stimulated mast cell migration. However, PGN did induce migration of RANTES-primed mast cells, and LPS did stimulate mast cell migratory response after priming with IL-6. Our results show that PGN, LPS and LAM might be among the important bacterial antigens involved in mast cell activation during bacterial infection.

Induction of mast cell accumulation, histamine release and skin edema by N49 phospholipase A2

BackgroundIt has been recognized that phospholipase A2 (PLA2) is a crucial component of snake venom, which contributes greatly to snake venom induced inflammation in man. However, the mechanisms through which N49 PLA2 provoke inflammation remain unclear. Recently, a N49 PLA2, TM-N49 from Protobothrops mucrosquamatus crude venom was characterized in our laboratory. Since the purification procedure developed is able to supply us with relatively large quantity of highly purified TM-N49, we investigated the ability of TM-N49 in induction of inflammation.ResultsThe results showed that TM-N49 provoked a dose dependent increase in microvascular leakage in the skin of rats. The potency of TM-N49 in induction of skin edema appeared similar potency of bradykinin and histamine. Pretreatment of rats with compound 48/80 diminished TM-N49 induced skin reaction and reduced mast cell numbers in rats. Ginkgolide B and cyproheptadine, but not terfenadine and quinacrine, inhibited TM-N49 elicited microvascular leakage when they were co-injected with the stimulus to rat skin. Moreover, TM-N49 was found to induce histamine release from human colon, lung and tonsil mast cells, and both metabolic inhibitors and pertussis toxin were capable of inhibiting TM-N49 elicited histamine release. TM-N49 induced mast cell accumulation in the peritoneum of mice, which was inhibited by co-injection of ginkgolide B, cyproheptadine and terfenadine. Intravenous injection of monoclonal antibodies against CD18, ICAM-1 and CD11a also blocked TM-N49 induced mast cell accumulation.ConclusionTM-N49 is a potent stimulus for skin edema, mast cell activation and accumulation.

Chitosan–hyaluronic acid nanoparticles loaded with heparin for the treatment of asthma

The purpose of this study was to produce mucoadhesive nanocarriers made from chitosan (CS) and hyaluronic acid (HA), and containing the macromolecular drug heparin, suitable for pulmonary delivery. For the first time, this drug was tested in ex vivo experiments performed in mast cells, in order to investigate the potential of the heparin-loaded nanocarriers in antiasthmatic therapy. CS and mixtures of HA with unfractionated or low-molecular-weight heparin (UFH and LMWH, respectively) were combined to form nanoparticles by the ionotropic gelation technique. The resulting nanoparticles loaded with UFH were between 162 and 217 nm in size, and those prepared with LMWH were 152 nm. The zeta potential of the nanoparticle formulations ranged from +28.1 to +34.6 mV, and in selected nanosystems both types of heparin were associated with a high degree of efficiency, which was approximately 70%. The nanosystems were stable in phosphate buffered saline (PBS), pH 7.4, for at least 24 h, and released 10.8% of UFH and 79.7% of LMWH within 12 h of incubation. Confocal microscopy experiments showed that fluorescent heparin-loaded CS–HA nanoparticles were effectively internalized by rat mast cells. Ex vivo experiments aimed at evaluating the capacity of heparin to prevent histamine release in rat mast cells indicated that the free or encapsulated drug exhibited the same dose–response behaviour.

Mode of action of histone deacetylase inhibitors on mast cell histamine release and colon muscle contraction

Mode of action of histone deacetylase inhibitors on mast cell histamine release and colon muscle contraction

Association of CRTH2 Gene Polymorphisms with the Required Dose of Antihistamines in Patients with Chronic Urticaria

Chronic urticaria (CU), defined as the recurring incidence of wheals with or without angioedema for more than 6 weeks, is a common disorder associated with mast cell activation, degranulation, and histamine release. Considering the association between the CRTH2 gene and mast cells, we investigated the association of this gene polymorphism with the CU phenotype and antihistamine drug requirement in patients with CU. Two groups consisting of 384 patients with CU and 231 patients as normal controls (NCs) were enrolled from the Department of Allergy and Rheumatology, Ajou University Hospital, Suwon, Korea. Two polymorphisms of the CRTH2 gene, -466T>C and -129C>A were genotyped using primer extension methods. No significant differences were detected in the genotype and allele frequencies of the two CRTH2 polymorphisms between the CU and NC groups, and no significant associations were observed with clinical parameters, such as atopy status, serum total IgE, prevalence of autoantibodies and duration of CU. However, CU patients with homozygous TT genotypes had significantly higher dose requirements of antihistamines to control the CU symptoms (164.56 +/- 115.62 vs 137.38 +/- 90.15 loratadine equivalents, mg/week) than those with the CT and CC genotypes (p = 0.025). The luciferase activity was significantly enhanced in the construct containing CRTH2 466C compared with the -466T-containing construct (p < 0.001). Co-transfection experiments with GATA-3 (300 ng) and the -466T and -466C CRTH2 alleles revealed that the CRTH2 -466T allele produced a greater increase in induction of luciferase activity than the -466C allele (p < 0.001). The CRTH2 -466T>C gene polymorphism may not affect on the phenotype of CU, but contributes to the required dose of antihistamines in patients with CU.

Glucocorticoids inhibit degranulation of mast cells in allergic asthma via nongenomic mechanism

Glucocorticoids (GCs) are the most potent anti-inflammatory agents available for allergic diseases including asthma, which are routinely believed to need several hours to take effect through regulating gene expression. Our previous report had shown that GCs could inhibit allergic asthma within 10 min, which the classical mechanism could not explain. To confirm the existence and verify the sites of GCs' rapid action, we investigated nongenomic effects of GCs on degranulation of mast cells in allergic asthma. The GCs' rapid action on airway mast cells deregulations was evaluated in the allergic asthma model of guinea pigs by the computer-assisted morphometry. Using whole-cell patch clamp and fluorometric assay, we examined GCs' nongenomic effect on IgE-mediated exocytosis and histamine release of rat basophilic leukaemia-2H3 mast cells. Employing the flash photolysis technique, we studied the role of Ca(2+) signal in the GCs' nongenomic effect. Inhaled GCs significantly inhibited airway mast cells degranulation in the allergic asthma model of guinea pigs within 10 min. In vitro, GCs could rapidly inhibit IgE-mediated exocytosis and histamine release of mast cells, and neither GC nuclear receptor antagonist nor protein synthesis inhibitor could block the rapid action. We further demonstrated that GCs' nongenomic effect was not through direct action on secretory machinery, but was mediated by a reduction in the [Ca(2+)](i) elevation. The study suggested for the first time that nongenomic pathway was involved in GCs' rapid inhibition on allergic asthma, and raised the possibility of new therapeutic strategies for allergic diseases including asthma.

Immunomodulatory pretreatment with Kalanchoe pinnata extract and its quercitrin flavonoid effectively protects mice against fatal anaphylactic shock

Previously, we reported the immunosuppressive action of the aqueous extract of Kalanchoe pinnata (Kp) in mice. In the present study, we report on the protective effect of Kp in fatal anaphylactic shock, likewise a Th2-driven immunopathology, and the identification of its active component. Mice daily treated with oral Kp during hypersensitization with ovalbumin were all protected against death when challenged with the allergen, as compared with the 100% mortality in the untreated group. A single intraperitoneal dose 3 h prior to challenge was partially effective. Oral protection was accompanied by a reduced production of OVA-specific IgE antibodies, reduced eosinophilia, and impaired production of the IL-5, IL-10 and TNF-α cytokines. In vitro, Kp prevented antigen-induced mast cell degranulation and histamine release. Oral treatment with the quercitrin flavonoid isolated from Kp prevented fatal anaphylaxis in 75% of the animals. These findings indicate that oral treatment with Kp effectively downmodulates pro-anaphylactic inducing immune responses. Protection achieved with quercitrin, although not maximal, suggests that this flavonoid is a critical component of Kp extract against this extreme allergic reaction.

The anti-allergic activity of the acetate fraction of Schinus terebinthifolius leaves in IgE induced mice paw edema and pleurisy

Schinus is a genus of the Anacardiaceae family and contains Schinus terebinthifolius, the Brazilian pepper tree that is widely used in folk medicine. We investigate the anti-allergic activity of the ethyl acetate fraction of S. terebinthifolius Raddi (ST fraction). HPLC analysis reveled that gallic acid, methyl gallate and 1,2,3,4,6-pentagalloylglucose are the major aromatic components of the fraction. Oral pre-treatment with the ST fraction (100 mg/kg) significantly inhibited paw edema induced by compound 48/80 (100 ng/paw) and to a lesser extent, the allergic paw edema (OVA, 3 μg/paw). The ST fraction (100 and 200 mg/kg) also inhibited the edema induced by histamine (100 μg/paw), preventing mast cell degranulation and, consequently, histamine release in Wistar rat peritoneal mast cells induced by C 48/80 (5 μg/mL). This histamine inhibition was also observed after mast cell pre-treatment with both methyl gallate and 1,2,3,4,6-pentagalloylglucose (100 μg/mL), the isolated compounds from the ethyl acetate fraction. Pre-treatment with the ST fraction (100 mg/kg) significantly inhibited total leukocyte and eosinophil accumulation in pleural cavities 24 h after the intrathoracic injection of OVA (12.5 μg/cavity). This effect was related to the inhibition of CCL11/eotaxin and CCL5/RANTES in pleural lavage fluid. Pre-treatment with this fraction (100 mg/kg) failed to reduce the cell influx that was observed after LPS-injection into pleural cavity (250 ng/cavity). These findings demonstrate the anti-allergic effect of the ST fraction, which includes the inhibition of edema formation and histamine release caused by mast cell degranulation and eosinophil influx into the pleural cavity probably reflected by the decreased levels of chemokines in recovered pleural lavage fluid.

Inhibitions of mast cell-derived histamine release by different Flos Magnoliae species in rat peritoneal mast cells

Flos Magnoliae (FM) is a commonly used Chinese medicinal herb for symptomatic relief of allergic rhinitis, sinusitis and headache. A number of FM species have been used as substitutes or adulterants for clinical application, although the differences in their pharmacological actions have not been reported. The present study investigated the effects of six identified FM species M. biondii, M. denudata, M. kobus, M. liliflora, M. sargentiana and M. sprengeri, as well as the marker compounds magnolin and fargesin on compound 48/80-induced histamine release in rat peritoneal mast cells (RPMC) in vitro. Ethanolic extracts of all FM species produced a concentration-dependent inhibition of compound 48/80-induced histamine release in RPMC. The rank order of the IC(50)s was M. biondii<M. kobus<M. liliflora<M. denudata<M. sprengeri<M. sargentiana. The marker compound magnolin, but not fargesin, only slightly inhibited the histamine release. The contents of magnolin and fargesin, determined by using RP-HPLC, varied significantly among these FM species. Magnolin was found in M. biondii, M. kobus and M. liliflora, but not in M. denudate, M. sprengeri and M. sargentiana, while fargesin was only found in M. biondii and M. kobus. These findings provide the first evidence of differences in pharmacological actions of different FM species on mast cell-derived histamine release in vitro. In addition, the marker compounds magnolin and fargesin may not play a major role in the observed pharmacological actions of FM species.

A carbon monoxide‐releasing molecule (CORM‐3) abrogates polymorphonuclear granulocyte‐induced activation of endothelial cells and mast cells

We hypothesized that circulating polymorphonuclear granulocytes (PMNs), vascular endothelial cells (ECs), and perivascular mast cells (MCs) may initiate and sustain the inflammatory response through the generation of the superoxide anion (O(2)(*-)) by PMNs primed by inflammatory stimuli, which in turn evoked the overexpression of adhesion molecules from ECs and release of histamine by MCs. To pin-point the role of carbon monoxide (CO) in curbing vascular inflammation, we studied the effect of a water-soluble CO-releasing molecule [tricarbonylchloro-glycinate-ruthenium (II); CORM-3] on an experimental model of vascular inflammation. The model consists of coincubating formyl-methionyl peptide (fMLP) -primed human PMNs with rat ECs or with rat MCs. The effects of CORM-3 were evaluated by measuring the generation of O(2)(*-) and the expression of CD11b in fMLP-primed PMNs; the expression of ICAM-1 and CD203c in ECs and MCs, respectively; and the release of histamine from MCs. Our results show that the chemotactic peptide fMLP primes PMNs to generate O(2)(*-) and overexpress CD11b, both events being central to the inflammatory process, while CORM-3 significantly decreases these events (IC(50)=1.66 microM for O(2)(*-) production; 1.20 microM for CD11b expression in human PMNs). The experiments also show that fMLP-primed PMNs increase the CD54 expression by coincubated ECs, and the expression of CD203c and the release of histamine by coincubated MCs. Once again, CORM-3 abolishes these events (IC(50)=6.78 microM for CD54 expression in ECs; 1.18 microM for CD203 expression; 1.15 microM for histamine release in MCs). Thus, CORM-3 exerts a powerful anti-inflammatory action by down-regulating the oxidative burst in PMNs, the overexpression of adhesion molecules in PMNs and ECs, the release of histamine, and the overexpression of an activation marker by MCs.

Inhibitory Activity of α,β-Unsaturated Lactones on Histamine Release from Rat Peritoneal Mast Cells

The present study was designed to examine the effects of a sesquiterpene lactone isolated from Artemisia douglasiana Besser (dehydroleucodine, DhL), a xanthanolide sesquiterpene isolated from Xanthium cavanillesii Schouw (xanthatin, Xt) and a semisynthetic butenolide (3-benzyloxymethyl-5 H-furan-2-one, But) on mast cell histamine release induced by compound 48/80. Peritoneal mast cells from male adult Sprague-Dawley rats were purified in Percoll, preincubated in the presence of test lactones (DhL, Xt or But) and then challenged with the mast cell activator compound 48/80. Concentration-response studies of mast cell histamine release evoked by compound 48/80, evaluation of mast cell viability and morphology studies by light microscopy were carried out. Biochemical and morphological studies showed the effectiveness of the above lactones to inhibit secretory responses of rat peritoneal mast cells. The present study provides evidence in favor of the hypothesis that DhL, Xt and But inhibit compound 48/80-induced histamine release from rat peritoneal mast cells. Our findings may provide an insight into the design of novel pharmacological agents that may be used to regulate the mast cell response.

Effects of glycinin on IgE-mediated increase of mast cell numbers and histamine release in the small intestine

Soybean allergy represents a significant health threat to individuals with food allergies. Glycinin, the main storage protein in soybean, has been identified as a major food allergen. The present study was conducted to investigate the mechanism of glycinin-induced hypersensitivity in a swine model. The relationship between glycinin dose and the severity of hypersensitive reactions was also explored. Twenty-four piglets weaned at 18 days were gastric sensitized and subjected to repeated oral challenges with diets containing 0%, 2%, 4% and 8% glycinin. The results showed that dietary supplementation of glycinin reduced piglet performance ( P<.01) while increasing occurrence of diarrhea ( P<.05) and erythema area ( P=.01) in response to an intradermal injection of glycinin. Intestinal mast cell numbers ( P<.05) and immunoglobulin E (IgE) levels ( P<.05) were increased linearly, whereas the histamine content in intestinal specimens (except in the duodenum) was decreased ( P<.01), indicating that more histamine had been released in glycinin-fed piglets than in control. Serum concentrations of total IgE, glycinin-specific IgG1 and interleukin (IL)-4 and IL-10 were also greater ( P<.05) in the pigs treated with glycinin. In this study, we found that glycinin-induced hypersensitivity is a predominantly Th2-type immune response, mediated by IgE and associated with increases in intestinal mast cell numbers and histamine release as well as IL-4 and IL-10 concentrations in the serum of sensitized piglets, resulting in diarrhea and reduced performance. The severity of the hypersensitive reactions depends on the dose of glycinin. Higher dose may cause more severe anaphylactic symptoms.

Antigen inhalation induces mast cells and eosinophils infiltration in the guinea pig esophageal epithelium involving histamine-mediated pathway

Antigen challenge in sensitized guinea pig esophagus in vitro induces mast cell degranulation and histamine release. This study tests the hypothesis that antigen inhalation in vivo induces infiltration of the esophageal epithelium by mast cells and eosinophils via a histamine pathway. Actively sensitized guinea pigs were exposed to inhaled 0.1% ovalbumin. One or 24 h after inhalation exposure, the esophagus was processed for immunofluorescent staining of mast cell tryptase and eosinophil major basic protein (MBP). Additional animals were pretreated with thioperamide, a histamine H4/H3 receptor antagonist. Total tryptase- and MBP-labeled cells and percent of positive cells in the epithelial layer were counted. The total number of mast cells was unchanged after inhalation challenge, but the percentage in the epithelium increased 1 h after challenge. The total number of eosinophils increased 1 h after challenge, and the percentage migrating to the epithelium increased by 24 h after challenge. Mast cell migration into the mucosal epithelium preceded that of eosinophils. Thioperamide inhibited mast cell and eosinophil migration. In conclusion, antigen inhalation in sensitized animals induces mast cells and eosinophils to infiltrate in the esophageal epithelium via histamine-mediated mechanism.

Carnosine attenuates mast cell degranulation and histamine release induced by oxygen–glucose deprivation

Carnosine (beta-alanyl-histidine) is a naturally occurring dipeptide that has been characterized as a putative hydrophilic antioxidant. The protective function of carnosine has been demonstrated in neuronal cells under ischemic injury. The purpose of this study was to investigate the effects of carnosine on oxygen-glucose deprivation (OGD)-induced degranulation and histamine release from mast cells. Cultured mast cells were exposed to OGD for 4 h, and then the degranulation was observed immediately by microscopy. Histamine release was analyzed by high-performance liquid chromatography (HPLC). OGD caused degranulation of mast cells, and increased histamine and lactate dehydrogenase (LDH) release. Carnosine (at a concentration of 5 mM) alone did not produce any appreciable effect on degranulation, histamine, and LDH release from mast cells under normal condition, but significantly inhibited the degranulation, histamine, and LDH release of mast cells induced by OGD. These results indicate that carnosine can protect mast cells from degranulation and histamine release and it may be an endogenous mast cell stabilizer in the pathological processes induced by ischemia.