Mast Cell Membrane Stabilizer Research Articles

Reduced mucosal injury of SPF chickens by mast cell stabilization after infection with very virulent infectious bursal disease virus

Recent studies here have demonstrated that increased mast cell populations and tryptase activity contribute to lesion formation in regions of immune organs in special-pathogen-free chickens after infection with very virulent infectious bursal disease virus (vvIBDV). Mast cells and their mediators have been implicated in acute inflammatory injury after vvIBDV infection, but their precise role in this process remains elusive. In this study, the role of mast cells in the vvIBDV infection process was examined using ketotifen, a mast cell membrane stabilizer. On days 1, 2, and 3 postinfection, the bursa of Fabricius (BFs) were collected to quantify mast cells, tryptase and histamine contents by cytochemistry, immunohistochemistry and fluorospectrophotometry analyses, respectively. The results showed that the mast cell populations, tryptase expression, and histamine released increased significantly in the BFs ( p < 0.01) of infected birds compared to controls, and acute inflammatory responses were observed in the former. In contrast, in infected chickens pretreated with ketotifen, mast cells, tryptase, and histamine were markedly decreased ( p < 0.01) and probably as a result, the BFs remitted significantly. The overall results suggest that mast cells are positively involved in BF injury induced by vvIBDV infection. Inhibition of mast cell degranulation and concurrent mediator release may represent a novel strategy to modulate this process. This study, thus, advances the understanding of the acute inflammatory injury mechanisms triggered by vvIBDV infection and the contribution of mast cell activity in this process.

Evidence for a role of mast cells in the mucosal injury induced by Newcastle disease virus

We have previously demonstrated that mast cells were significantly increased during Newcastle disease virus (NDV) infection, but their precise role in the process is unknown. In this study, we investigated the role of mast cells in this process by using ketotifen, a mast cell membrane stabilizer. A total of 60 specific-pathogen-free chickens were randomly divided into 3 groups of 20 birds each (NDV-infected group, ketotifen-pretreated group, and the control group). The ketotifen-pretreated group was administered orally with ketotifen before NDV infection. On 12, 24, and 48 h postinfection, 5 chickens from each treatment were killed. Tissues of proventriculus were collected to quantify mast cells, the content of tryptase and histamine by cytochemistry, immunohistochemistry, and fluorescence analysis, respectively. The results showed that the population of mast cells and the content of tryptase and histamine were increased significantly in the proventriculus (P < 0.01) of infected birds compared with the control group. An acute mucosal injury was observed in the infected chickens. In contrast, among chickens pretreated with ketotifen, followed by NDV infection, the mast cells number and the content of tryptase and histamine were decreased significantly (P < 0.01). Likely as a result, the mucosal injury was remitted remarkably. The overall results of this experiment suggest that mast cells are implicated in NDV-induced mucosal injury. Inhibition of mast cell mediator release may represent a novel strategy to modulate this process.

The nociceptive mechanism of 5-hydroxytryptamine released into the peripheral tissue in acute inflammatory pain in rats

The present study examined the contribution of 5-hydroxytryptamine (5-HT) to acute peripheral inflammatory pain in rats. We used formalin test in this study. After formalin injection into the rat hind paw, biphasic pain-related behavior (phases 1 and 2) was observed. A microdialysis study revealed that 5-HT was released into the formalin injection site in a formalin concentration-dependent manner (1.25–5%), and its peak time was 18 min after the injection. Previous studies suggest that peripheral 5-HT2 receptors are involved in inflammatory pain. Therefore, we next examined whether 5-HT2A and 5-HT2C receptors are involved, and from where 5-HT is released in the formalin test. Local pretreatment with a selective 5-HT2A receptor antagonist, ketanserin, and selective 5-HT2C receptor antagonists, RS102221 and SB242084, inhibited the number of flinches in early part of phase 2 (phase 2A) of the formalin test in a dose-dependent manner. Peripheral pretreatment with sodium cromoglycate (cromolyn), a mast cell membrane stabilizer, completely suppressed 5-HT release and inhibited phase 2 responses of the formalin test. These drugs inhibited c-fos expression in the superficial layer of the spinal dorsal horn of segments L4-5 at 2 h after formalin injection. These results indicate that 5-HT released into peripheral tissue and its receptors, 5-HT2A as well as 5-HT2C, at the periphery have an important role in pain-related behaviors during acute peripheral inflammation.

Super-oxidized solution inhibits IgE-antigen-induced degranulation and cytokine release in mast cells

Activation of the high affinity IgE receptor (FcεRI) through IgE-antigen complexes induces mast cell degranulation, synthesis of lipid mediators and cytokine production. These effects are involved in Type I hypersensitivity reactions and controlling them has been the main objective of many anti-allergic therapies. Here we report that pretreatment of murine bone marrow derived mast cells (BMMC) with super-oxidized solution (SOS) inhibits FcεRI dependent-β hexosaminidase and cytokine release. This effect is exerted without altering total protein tyrosine phosphorylation, MAPK activation, cytokine mRNA accumulation or calcium mobilization after FcεRI triggering. Our data suggest that this neutral pH-SOS acts like a mast cell-membrane stabilizer inhibiting the cell machinery for granule secretion without altering the signal transduction pathways induced by IgE-antigen receptor crosslinking.

Impairment of the Intestinal Barrier by Ethanol Involves Enteric Microflora and Mast Cell Activation in Rodents

Alcohol hepatic toxicity in heavy drinkers is associated with high endotoxin blood levels and increased intestinal permeability. Because endotoxins can cross damaged mucosa, we investigated the mechanisms through which ethanol impairs the colonic epithelium of rats submitted to acute alcohol intake. Colonic permeability to (51)Cr-ethylenediamintetraacetic acid was increased 24 hours after 3.0 g/kg ethanol intake (3.2 +/- 0.2% versus 2.2 +/- 0.2%) and was associated with significant endotoxemia. Antibiotics and doxantrazole (a mast cell membrane stabilizer) significantly inhibited the effect of ethanol. Two hours after intake, plasma concentrations of ethanol were twofold higher in antibiotic-treated rats than in controls (155.8 +/- 9.3 mg/dl versus 75.7 +/- 7.6 mg/dl, P < 0.001). Lumenal concentrations of acetaldehyde were markedly increased after ethanol intake (132.6 +/- 31.6 micromol/L versus 20.8 +/- 1.4 micromol/L, P < 0.05) and antibiotics diminished this increase (86.2 +/- 10.9 micromol/L). In colonic samples mounted in Ussing chambers, acetaldehyde but not ethanol increased dextran flux across the mucosa by 54%. Doxantrazole inhibited the effect of acetaldehyde. This study demonstrates that an acute and moderate ethanol intake alters the epithelial barrier through ethanol oxidation into acetaldehyde by the colonic microflora and downstream mast cell activation. Such alterations that remain for longer periods could result in excessive endotoxin passage, which could explain the subsequent endotoxemia frequently observed in patients with alcoholic liver disease.

Inhibition of granuloma-associated angiogenesis by controlling mast cell mediator release: role of mast cell protease-5.

We investigated the role of mast cells in granuloma-associated angiogenesis in rat by using: (i) a mast cell membrane stabilizer, ketotifen; (ii) a mast cell depleting agent, compound 48/80. Moreover, we focused on the role of chymases, which exhibit proinflammatory and pro-angiogenic properties by using: (i) chymostatin, an inhibitor of chymase activity; (ii) a specific antisense oligonucleotide (AS-ODN) designed against rat mast cell protease-5 (rMCP-5), the most abundantly expressed chymase in the skin. The formation of granuloma was evaluated, as wet weight, 96 h after the subcutaneous implant of two lambda-carrageenin (1%)-soaked sponges on the back of male Wistar rats. Angiogenesis was evaluated as haemoglobin content in the granulomatous tissue and as level of tumour necrosis factor-alpha (TNF-alpha) in the exudates. A single injection of ketotifen (1-5-25 mg kg(-1) i.p.) significantly reduced granuloma formation by 31.6, 44.6 and 71.9%, and haemoglobin content by 17.0, 35.0 and 66.2%, suggesting that the release of mediator(s) from mast cells modulates the process. Chymostatin (5-10 nmol(-1) site(-1) day(-1)) reduced granuloma-associated angiogenesis by 57.3 and 70.0%. RT-PCR analysis showed that rMCP-5 mRNA amounts were significantly reduced by rMCP-5 AS-ODN (1.25-2.5-5.0 nmol site(-1)) by 69.5, 72.5 and 81.8%. In parallel experiments, rMCP-5 AS-ODN (1.25, 2.5, 5.0 nmol site(-1)) strongly reduced granuloma weight (26.1, 45.0 and 56.3%) and haemoglobin content (22.2, 50.4, 62.03%), suggesting that the observed effect is mediated through an antisense mechanism. In conclusion, these data suggest that: (i) inhibition of mast cell mediators release may represent a novel strategy to modulate angiogenesis; (ii) among the chymase family, rMCP-5 is a key promoter of angiogenesis in the rat.

Evidence that mast cell degranulation, histamine and tumour necrosis factor alpha release occur in LPS-induced plasma leakage in rat skin.

1. In the present study we investigated the role of mast cells during inflammation in rat skin. As the release of several pro-inflammatory mediators, such as histamine and tumour necrosis factor alpha (TNFalpha), occurs following mast cell activation we studied whether mast cell degranulation and the release of both histamine (H) and TNFalpha occurred in a model of lipopolysaccharide (LPS)-induced plasma leakage in rat skin. 2. Plasma leakage in the rat skin was measured over a period of 2 h as the local accumulation of intravenous injection of 125I-human serum albumin (125I-HSA) in response to intradermal injection of LPS. LPS (10 microg site-1) produced an increase of plasma leakage (50.1+/-2.3 microl site-1) as compared to saline (9.0+/-3.2 microl site-1). Histological analysis of rat tissue showed that LPS induced a remarkable mast cell degranulation (59.8+/-2.1%) as compared to saline (13.5+/-2.2%). 3. Ketotifen (10-9 - 10-7 mol site-1), a well-known mast cell-membrane stabilizer, produced a dose-related inhibition of LPS-induced plasma leakage by 36+/-3.5%, 47+/-4.0%, 60+/-3.3% respectively. In addition, ketotifen (10-7 mol site-1) inhibited mast cell degranulation by 59. 2+/-2.7%. 4. Chlorpheniramine maleate (CPM) (10-9 - 10-7 mol site-1), an H1 histamine receptor antagonist only partially inhibited LPS-induced plasma leakage in rat skin (38+/-1.1% at the highest dose). Furthermore, CPM (10-7 mol site-1) did not prevent mast cell degranulation. 5. A polyclonal antibody against TNFalpha (1:500, 1:100, 1:50 v v-1 dilution), locally injected, decreased LPS-induced plasma leakage in the skin by 15+/-2.0%, 24+/-2.1% and 50+/-3.0% respectively. 6. Taken together these results suggest that LPS-induced plasma leakage in rat skin is mediated, at least in part, by mast cell degranulation and by the release of histamine and TNFalpha from these cells.

The effect of captopril on histamine release from purified rat mast cells.

Captopril as inhibitor of angiotensin-converting enzyme is widely used in cardiovascular therapy, however, in some patients this drug causes allergic side effects. This fact suggests that captopril may release histamine from mast cells. Peritoneal mast cells were obtained from rats. The cells were purified by Percoll. Aliquots of mast cells were incubated with captopril or with vehicle. Histamine was determined by the spectrofluorimetric assay. The results were analyzed with the Kruskall-Wallis (ANOVA) test. The study has shown that captopril releases histamine from mast cells. The process depends on Ca2+ presence in the incubation environment. Sodium cromoglycate, as mast cell membrane stabilizer, inhibits the effect of captopril. Our results suggest that allergic side effects of captopril may be linked to histamine release from mast cells.

Cis-Urocanic Acid Induces Mast Cell Degranulation and Release of Preformed TNF--α: A Possible Mechanism Linking UVB and cis-Urocanic Acid to Immunosuppression of Contact Hypersensitivity

The search for effective inhibitors of transdermal drug-induced contact sensitization was directed to dermal mast-cell-degranulating agents (MCDA). Human skin organ cultures were employed to test whether cis-urocanic acid (C-UA) and other potential MCDAs cause mast cell degranulation. These were then tested for their ability to inhibit the induction phase of the contact hypersensitivity reaction (CHR). C-UA at 1 μg/ml significantly depleted mast cell chymase, whereas trans-urocanic acid (T-UA) was relatively ineffective. C-UA, but not T-UA, induced local effects of liberated mast cell TNF-α, as detected by E-selectin expression on the microvascular dermal endothelium. C-UA significantly reduced (>70%) the ear swelling response in Balb/c mice, when applied 24 h prior to application of a sensitizing amount of dinitrochlorobenzene (DNCB), and induced a prolonged (>3 weeks) state of immune tolerance (>40%). Similar effects on local immunosuppression of CHR were observed with topical chloroquine and capsaicin, while cromolyn, a mast cell membrane stabilizer, was unable to inhibit DNCB-induced CHR. It is suggested that MCDAs may interfere with downstream events associated with accessory cell function.

Effect of lodoxamide on tear leukotriene levels in giant papillary conjunctivitis associated with ocular prosthesis

Leukotrienes have been shown to play a role in the patho-genesis of ocular inflammatory and allergic reactions like vernal kerato-conjunctivitis and contact lens-associated giant papillary conjunctivitis. This study was designed to determine leukotriene B4 (LTB4) and leukotriene C4 (LTC4) levels in the tears of patients with ocular prosthesis-associated giant papillary conjunctivitis (OP-GPC) and to evaluate the effects of lodoxamide 0.1% on tear LTB4 and LTC4 levels of OP-GPC patients. Tear LTB4 and LTC4 levels were determined by an ELISA technique in the tears of ten OP-GPC patients before and after treatment with lodoxamide 0.1% for one month. The results were compared with that of ten healthy control subjects. The mean tear LTB4 and LTC4 levels of the OP-GPC patients were significantly higher than those of the control group. After treatment with lodoxamide 0.1%, tear LTB4 and LTC4 levels of the OP-GPC patients decreased significantly. This is the first report of elevated LTB4 and LTC4 levels in tears of OP-GPC patients and it points to the possible role of leukotrienes in the immunopathogenesis of OP-GPC. The results also indicate that lodoxamide 0.1%, a mast cell membrane stabilizer, is effective in significantly reducing tear LTB4 and LTC4 levels in OP-GPC patients.