The dynamics of mast cell secretion mediated by IgE or polyamines

Mast cell secretion can be mediated not only by IgE but also by a number of secretagogues of various chemical structure. In the present study the dynamics of the mast cell secretory process induced by different polyamines and anti-IgE were compared using a combination of vital berberine binding (demonstrating intracellular granules that have released amines) and measurement of histamine and heparin release. The results suggest that the basic secretory pattern is the same no matter whether the secretion is induced by polymyxin B, polylysine, compound 48/80, or an IgE-anti-IgE reaction. Histamine can be released from intracellular granules which, according to previous results, may be reincorporated into the cytoplasm, but which are to a large extent expelled from the cell by exocytosis.     

Inhibition of gastric acid secretion with a mast cell stabiliser, FPL-52694.

1 The effect on gastric acid secretion of a mast cell stabiliser FPL-52694 was examined in nine healthy volunteers. 2 The compound which is moderately well absorbed after oral ingestion, was taken for 5 days prior to the measurement of acid secretion and was also given intravenously during part of the gastric test. A submaximal dose of pentagastrin (0.3 microgram/kg/h) was given by intravenous infusion for 2 h in a controlled test and then after administration of FPL-52694. 3 There was a significant reduction (37%) in acid secretion during the second test which was probably due to the effect of the compound on mast cell degranulation in the gastric mucosa.     

Induction of mast cell secretion by parathormone

The biologically active fragment of human parathormone (PTH) and intact bovine PTH were found to induce secretion of both serotonin and histamine from rat peritoneal mast cells in vitro. Release of serotonin and histamine was demonstrated with 25 units/ml PTH or higher. This level is within the higher limits of the elevated PTH levels found in advanced uremia. Mast cell secretion by PTH was dose, time and energy dependent and was not cytotoxic. Although mast cell activation was independent of extracellular calcium, it required intracellular calcium, thus resembling the action of certain other peptide secretagogues. Intradermal injection of PTH induced immediate increases in vascular permeability suggesting that PTH could induce mast cell secretion in vivo. Light and electron microscopic observations confirmed mast cell degranulation by exocytosis. These results demonstrate that elevated levels of PTH can induce mast cell secretion in vitro and in vivo and suggest a possible role for mast cells in the pathophysiology of non-allergic disease states.     

Inhibition of IgE-mediated mast cell degranulation by sulphasalazine

The effect of sulphasalazine on two mast cell populations and human peripheral leukocytes is reported. Sulphasalazine inhibited histamine release from mouse and rat mast cells, but it caused a potentiation of secretion in human peripheral leukocytes. The drug alone did not induce histamine release when administered without an anaphylactic stimulus. The results are discussed in terms of a possible mode of action of sulphasalazine in the treatment of inflammatory bowel disease.     

Inhibition of rat mast cell degranulation by verapamil

Calcium antagonists, e.g. verapamil, prevent exercise-induced asthma. This protective effect may proceed from inhibition of contraction of bronchial smooth muscle, release of mediators by primary effector cells, e.g. mast cells, or both. Therefore, we studied the inhibitory effect of increasing concentrations of verapamil on both in vitro antigen-induced degranulation and ionophore A23187-induced release of labelled serotonin by rat peritoneal mast cells. There was a dose-dependent inhibition by verapamil of both ovalbumin-induced degranulation of mast cells passively sensitized by incubation with mice IgE-rich serum and ionophore-induced release of tritiated serotonin by mast cells previously incubated with (3H)-5HT; the 50% inhibiting concentration was 1.4 X 10(-4) mol I-1 and 5.2 X 10(-5) mol I-1, respectively. An attractive explanation of our results is that verapamil inhibits the antigen-induced release of mediators by mast cells through its calcium antagonist effect. Our results also suggest that the preventing effect of calcium antagonists on asthma may be multi-factorial since other authors have clearly shown that these drugs inhibit contraction of guinea-pig tracheal smooth muscle in vitro.     

Progesterone inhibits mast cell secretion

Mast cells are involved in allergic reactions, where they secrete numerous vasoactive, inflammatory and nociceptive mediators in response to immunoglobulin E (IgE) and antigen. However, they have also been implicated in inflammatory conditions, such as painful bladder syndrome/interstitial cystitis (PBS/IC), irritable bowel syndrome (IBS) and migraines, all of which occur more often in women and are exacerbated during ovulation, but are suppressed during pregnancy. Mast cells express high affinity estrogen receptors and estradiol augments their secretion, while tamoxifen inhibits it. Here we report that progesterone (100 nM), but not the structurally related cholesterol, inhibits histamine secretion from purified rat peritoneal mast cells stimulated immunologically or by substance P (SP), an effect also documented by electron microscopy. These results suggest that mast cell secretion may be regulated by progesterone and may explain the reduced symptoms of certain inflammatory conditions during pregnancy.     

Inhibition of advanced glycation end products by aminoguanidine restores mast cell numbers and reactivity in alloxan-diabetic rats

Mast cell number and reactivity have been shown to be down-regulated under diabetic conditions. This study was undertaken in order to investigate the role of the advanced glycation end products in the reduction of mast cell number and reactivity in diabetic rats. The effect of aminoguanidine on mast cell apoptosis was also evaluated. Diabetes was induced by intravenous injection of alloxan into fasted rats and aminoguanidine was administered after 3 days of diabetes induction, once daily for 18 consecutive days. Mast cell apoptosis and levels of Bax, a pro-apoptotic member of Bcl-2 family, were evaluated by TUNEL and western blot, respectively. Diabetes led to increased levels of fructosamine and AGEs in the plasma, an effect prevented by aminoguanidine. Treatment with aminoguanidine restored mast cell numbers in the pleural cavity and in mesenteric tissue of diabetic rats. Aminoguanidine also significantly reversed the diabetes-induced reduction in histamine release, as measured by fluorescence, following activation with substance P or antigen in vitro. Increased apoptosis and levels of Bax in mast cells from diabetic rats were inhibited by aminoguanidine. In conclusion, our findings showed that aminoguanidine restored the number and reactivity of mast cells in diabetic rats, accompanied by suppression of apoptosis, evidencing that advanced glycation end product formation has a critical role in mast cell behavior of diabetic rats.     

Inhibition of mouse mast cell proliferation and proinflammatory mediator release by benzodiazepines.

Mast cell (MC) activation may occur in vitro and in vivo following stimulation with various immunologic or nonimmunologic agents. Such activation leads to the release of several biological mediators, including vasoactive amines, nitric oxide and cytokines, which account for the adverse effects observed during allergic reactions. While high affinity binding sites for benzodiazepines (BZDs) have been reported on MC, the effects of the ligation of these receptors on the proliferation of, and the mediator release from, these cells are poorly documented. In the present work, we have examined the effects of midazolam and of diazepam on the proliferation of mucosal (MMC)-like and of serosal (CTMC)-like mouse MC. In addition, we have studied the effects of these BZDs on beta-hexosaminidase, TNF-alpha and nitrite release induced from mouse mast cells through IgE receptor activation. We demonstrated that each of the two BZDs studied inhibited the proliferation of MMC- and CTMC-like elements in a dose-dependent fashion (10 to 100 microM). Furthermore, the BZDs inhibited the IgE-mediated release of beta-hexosaminidase, TNF-alpha and nitrites from MMC- or CTMC-like cells. Altogether, these data provide new insights into the pharmacological regulation of MC activation and may lead to the discovery of new and potent antiallergic compounds.     

Inhibition of allergic and non-allergic histamine secretion from rat peritoneal mast cells by calcium antagonists.

Bepridil, TMB-8 (8-(diethylamino)octyl 3,4,5-trimethoxybenzoate hydrochloride), diltiazem, verapamil and nifedipine exerted concentration-dependent inhibition of antigen and calcium ionophore A23187-induced histamine release from rat peritoneal mast cells. The inhibitory effects of verapamil and bepridil against calcium ionophore A23187-induced histamine secretion were antagonized by increased Ca2+ concentrations in the extracellular medium. These observations suggest that both agents act by interfering with the influx of Ca2+ into the mast cells. The inhibitory activities of five different Ca2+ channel blockers on allergic and non-allergic histamine secretion from rat peritoneal mast cells varied considerably depending upon the nature of the secretagogue as well as concentration and type of Ca2+-antagonist examined.     

Inhibition of histamine release from human mast cells by natural chymase inhibitors

AIM: To investigate the ability of natural chymase inhibitors to modulate histamine release from human mast cells.METHODS: Enzymatically dispersed cells from human lung, tonsil, and skin were challenged with anti-IgE or calcium ionophore A23187 in the absence or presence of the natural chymase inhibitors secretory leukocyte protease inhibitor (SLPI) and α1-antitrypsin, then histamine release was determined. RESULTS: IgE-dependent histamine release from lung, tonsil, and skin mast cells were inhibited by up to 70 %, 61%, and 62 %, respectively following incubation with α1-antitrypsin (5000 nmol/L). SLPI 5000 nmol/L was also able to inhibit anti-IgE-dependent histamine released from lung, tonsil and skin mast cells by up to approximately 72 %, 67 %, and 58 %,respectively. While neither α1-antitrypsin nor SLPI by themselves altered histamine release from lung, tonsil and skin mast cells, they were able to inhibit calcium ionophore-induced histamine release from lung and tonsil mast cells. CONCLUSION: Both α1-antitrypsin and SLPI could potently inhibit IgE-dependent and calcium ionophoreinduced histamine release from dispersed human lung, tonsil, and skin mast cells in a concentration-dependent manner, which suggested that they were likely to play a protective role in mast cell associated diseases including allergy.     

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.     

Inhibition of mast cell histamine release by flavonoids and biflavonoids

The effect of 11 flavonoids and 4 biflavonoids on the release of histamine from peritoneal rat mast cells induced by compound 48/80 and calcium ionophore A23187 was studied. Dihydroflavonoids (flavanones) and (+)-catechin did not modify histamine release induced by both secretagogues. Flavone, apigenin and cromoglycate inhibited the secretion elicited by compound 48/80 but did not modify the A23187-induced secretion. The effect of kaempferol on the compound 48/80-induced histamine release was biphasic. Low doses (10 (-6) to 10 (-5)M) of the compound potentiated secretion whereas higher doses inhibited histamine secretion. Some of the drugs tested revealed a higher potency as referred to quercetin. Luteolin, a tetrahydroxyflavone and amentoflavone, a biapigenin, exhibited the highest inhibitory effects of mast cell histamine secretion.     

Inhibition of anaphylaxis like reaction and mast cell activation by Sitagliptin

Mast cells stimulation activates degranulation process resulting in releasing of mediators, such as histamine. In this study, the effect of aqueous extract of sitagliptin, a selective dipeptidylpeptidase-4 inhibitor, on the mast cell-mediated allergic response was studied with the possible mechanisms of action, focusing on the histamine release and pro-inflammatory cytokine secretion in mast cells. Sitagliptin produced dose dependent inhibition in compound 48/80-induced systemic reactions. In addition, sitagliptin attenuated IgE-mediated skin allergic reaction. Sitagliptin dose-dependently reduced compound 48/80- and IgE-induced histamine release from mast cells. Sitagliptin decreased the secretion of pro-inflammatory cytokines, tumor necrosis factor-α, in mast cells. So, the finding of this study provides evidence that sitagliptin inhibits mast cell derived allergic reactions, and involvement of pro-inflammatory cytokine secretion in such effects.     

Inhibition of P-glycoprotein by natural products in human breast cancer cells

Multidrug resistance (MDR) is one of the most significant obstacles in cancer chemotherapy. One of the mechanisms involved in the development of MDR is the over-expression of P-glycoprotein (P-gp). It is widely known that natural compounds found in vegetables, fruits, plant-derived beverages and herbal dietary supplements not only have anticancer properties, but may also modulate P-gp activity. Therefore, the purpose of this investigation was to examine the effects of naturally occurring products on P-gp function in human breast cancer cell lines, MCF-7 (sensitive) and MCF-7/ADR (resistant). The accumulation of daunomycin (DNM), a P-gp substrate, was greater in the sensitive cells compared to the resistant cells, while the efflux of DNM was higher in the resistant cells compared to the sensitive cells over a period of 2 h. The IC50 value of DNM in the resistant cells was about 22 times higher than that in the sensitive cells, indicating an over-expression of P-gp in the resistant cells, MCF-7/ADR. All of the compounds tested, with the exception of fisetin, significantly decreased the IC50 value of DNM. Biochanin A showed the greatest increase in [3H]-DNM accumulation, increasing by 454.3 +/- 19.5% in the resistant cells, whereas verapamil, the positive control, increased the accumulation by 229.4 +/- 17.6%. Also, the accumulation of [3H]-DNM was increased substantially by quercetin and silymarin while it was reduced by fisetin. Moreover, biochanin A, silymarin, and naringenin significantly decreased DNM efflux from MCF-7/ADR cells compared with the control. These results suggest that some flavonoids such as biochanin A and silymarin may reverse MDR by inhibiting the P-gp function.     

Inhibition of natural killer cell function by marijuana components

The extent of modulation of host resistance mechanisms by marijuana components is not fully understood. Natural killer (NK) cells are a subpopulation of lymphoid cells and are important in host resistance mechanisms against malignant cells, virus-infected cells, and possibly pathogenic bacteria and fungi. We report that the marijuana component delta-9-tetrahydrocannabinol (THC) injected into mice results in a suppression of splenic NK activity. Furthermore, THC and the hydroxylated metabolite 11-hydroxy-delta-9-tetrahydrocannabinol (11-hydroxy-THC) suppress the NK activity of cultured murine splenocytes in a dose-dependent manner (range 1 X 10(-5) to 3.2 X 10(-5) M) without diminishing NK cell viability. The hydroxylated derivative appears to possess a more potent suppressive effect, in that it suppresses at lower concentrations than THC does and requires a shorter incubation time with the effector cells for its suppressive action. Purification of NK cells by Percoll density-gradient centrifugation suggests that both cannabinoids act directly on the natural killer cell population, resulting in suppression. Studies involving target binding analysis and calcium ionophore experiments suggest that cannabinoids do not suppress NK cell killing by the inhibition of effector/target binding or by disruption of calcium ion flux. These results suggest that two principal psychoactive cannabinoids can suppress natural killer cell function by interacting directly with the killer cells and disrupting cellular events postbinding and during the programming for lysis. Furthermore, the data suggest different modes of action for THC and the hydroxylated metabolite.     

Inhibition of mast cell mediator release by 5-amino-4-imidazolecarboxamide riboside

Stimulated mast cells produce and release adenosine, and the release of mast cell mediators is potentiated by adenosine, yet very little is known regarding mast cell purine metabolism. Because 5-amino-4-imidazolecarboxamide riboside (AICA riboside) has been shown to alter adenosine metabolism and accelerate the repletion of ATP pools in other tissues, its effects on mast cell function were examined. Neither simultaneous addition of A23187 and AICA riboside nor a 1-hr preincubation with AICA riboside altered mast cell beta-hexosaminidase release to an appreciable degree. However, mouse bone marrow-derived mast cells cultured for 2 or more days in the presence of 1-100 microM AICA riboside exhibited a markedly attenuated mediator release response to A23187 compared to control cells with or without the additional presence of adenosine. IgE-mediated leukotriene C4 generation from AICA riboside-exposed mast cells was even more profoundly inhibited without affecting cell viability or resting mediator content. An unusual ribonucleotide triphosphate previously identified in folate-depleted cells, 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranosyl 5'-triphosphate (ZTP), has been identified in AICA riboside-treated mast cells as well. Although the mechanism of this global inhibition of mast cell mediator release by chronic AICA riboside treatment is not clear, alterations in mast cell purine metabolism may prove to be important in the treatment of allergic diseases.     

Stimulation of mucin secretion from human bronchial epithelial cells by mast cell chymase

AIM: To investigate the effect of chymase on the mucin secretion from human bronchial epithelial cells. METHODS:Primarily-cultured human bronchial epithelial (PCHBE) cells and normal human bronchial epithelial (NI-IBE) cell swere cultured with chymase or other stimulus in a mixture of bronchial epithelial growth medium (BEGM) and Dulbecco‘s modified Eagle‘s medium (DMEM), and the quantities of stimulatory mucin release were recorded.MUC5AC mucin was measured with an ELISA and dolichos biflorus agglutinin (DBA) mucin was determined with an enzyme linked DBA assay. RESULTS: A dose-dependent secretion of DBA mucin from PCHBE cells was observed with chymase with a maximum secretion of 98 % above baseline being achieved following 3 h incubation.The action of chymase started from 1 h, peaked at 3 h and dramatically decreased at 20 h following incubation.Chymase was able to also stimulate approximately 38 % increase in MUC5AC mucin release from PCHBE cells, and about 121% increase in DBA mucin release from NHBE cells. A chymase inhibitor soybean trypsin inhibitor (SBTI)was able to inhibit up to 85 % chymase induced mucin release, indicating that the enzymatic activity was essential for the actions of chymase on bronchial epithelial cells. CONCLUSION: Chymase is a potent stimulus of mucin secretion from human bronchial epithelial cells. It can contribute to mucus hypersecretion process in the patients with chronic obstructive pulmonary disease or asthma.     

Inhibition of mast cell degranulation by tanshinones from the roots of Salvia miltiorrhiza

The activity-guided fractionation of the extract of the root of Salvia miltiorrhiza B. (Labiatae, Tanshen), led to the isolation of four active components responsible for the anti-allergic activity in vitro. Among them, 15,16-dihydrotanshinone-I and cryptotanshinone demonstrated significant inhibition of the release of beta-hexosaminidase from cultured RBL-2H3 cells in a dose-dependent manner; the IC50 values were calculated as 16 and 36 microM, respectively.     

Inhibition of mast cell adenosine responsiveness by chronic exposure to adenosine receptor agonists

Mast cell adenosine receptors are up-regulated functionally and numerically by chronic exposure to receptor antagonists, but their response to long-term treatment with receptor agonists has not been studied. To address this issue cultured mouse bone marrow-derived mast cells were exposed to N-ethylcarboxamide adenosine (NECA), an adenosine receptor agonist that augments stimulated mast cell mediator release. Cells grown for 3 days in 1 nM NECA responded normally to A23187 or antigen in releasing beta-hexosaminidase, but the ability of exogenous adenosine to potentiate this mediator release was attenuated markedly. This inhibition of adenosine responsiveness was partially present after 10 min of 1 microM NECA exposure and complete after 4 hr. The inhibitory effects could be reversed by washing NECA-exposed cells and returning them to culture for more than 4 hr. The adenosine present in the fetal calf serum coupled with deoxycoformycin attenuated mast cell adenosine responsiveness. The NECA-treated cells also exhibited a hyporesponsiveness to adenosine's augmentation of cell cyclic AMP content. This hyporesponsiveness was specific for adenosine receptors in that exogenous isoproterenol was able to increase cyclic AMP levels to a similar degree in both control and NECA-treated cells. Thus, chronic NECA exposure induces a homologous desensitization of mast cell adenosine receptors.