The activation of synovial mast cells: modulation of histamine release by tryptase and chymase and their inhibitors

Mast cells have been implicated as having pivotal roles in arthritis, but little is known of the processes leading to the activation of synovial mast cells or their potential for pharmacological control. We have investigated the ability of tryptase and chymase, and inhibitors of these major mast cell proteases to modulate the activation of mast cells from human synovial tissue. The tryptase inhibitor drug N-(1-hydroxy-2-naphthoyl)-L-arginyl-L-prolinamide hydrochloride (APC366) inhibited immunoglobulin E (IgE)-dependent histamine release in a dose-dependent manner, with about 70% inhibition being achieved at a dose of 300 microM. Histamine release stimulated by calcium ionophore A23187 was also inhibited by this compound. The chymase inhibitor chymostatin inhibited IgE-dependent histamine release by approximately 60% at 1 microg/ml. Tryptase at concentrations of 3.0 microg/ml and greater stimulated histamine release from synovial cells, which was dependent on catalytic activity, whereas chymase had little effect on these cells. The activation of mast cells by tryptase may represent an amplification process in the synovium. The mast cell stabilising properties of inhibitors of tryptase and chymase could be of therapeutic value in arthritis.     

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 histamine release from dispersed human lung and tonsillar mast cells by nicardipine and nifedipine

Calcium entry blocking drugs attenuate antigen-induced bronchoconstriction in asthma which is mast cell mediated. We have investigated the effects of two calcium uptake blockers, nicardipine and nifedipine on histamine secretion from human mast cells dispersed from lung and tonsillar tissue. Mast cells were activated for secretion with anti-human IgE or calcium ionophore, A23187. Nicardipine and nifedipine caused a concentration-related inhibition of IgE-dependent histamine release from both lung (IC30 10 microM and 4.4 microM) and tonsillar (IC30 21 microM and 47 microM) mast cells. Nicardipine and nifedipine also inhibited mast cell histamine release induced by A23187 with IC30 values of 14 microM and 67 microM for lung and 15 microM and 30 microM for tonsillar mast cells. In the absence of drugs, increasing the extracellular calcium concentrations from 0.2 to 5 mM caused a concentration related increase in IgE-dependent histamine release from tonsillar mast cells. Both nicardipine and nifedipine (50 microM) displaced the concentration-effect curve to the right. Nicardipine (0.01-100 microM) caused a concentration related inhibition of rat kidney histamine methyltransferase activity used in the radioenzymatic assay of histamine (ki of 7.5-12 microM) whereas nifedipine was only a weak inhibitor. Nicardipine also interfered with the spectrofluorimetric assay after exposure to ultraviolet light. These observations demonstrate that nicardipine and nifedipine inhibit IgE-dependent and ionophore stimulated mediator secretion from human mast cells. The lack of stimulus-related specificity and the high drug concentrations required suggest that classical calcium channel blockade is not responsible for inhibition of mast cell mediator release. Furthermore, we suggest that inhibition of mast cell mediator release is unlikely to be the mechanism by which these drugs alleviate asthma.     

The effect of serine esterase inhibitors on ionophore-induced histamine release from human pulmonary mast cells

The serine proteases tryptase and chymase are present in human pulmonary mast cells. About 10-100 times more tryptase than chymase is found in these cells. However, a clear physiological role for both enzymes remains to be elucidated; angiotensin processing has been proposed as one possible function of chymase. A dose-dependent inhibition of A23187-induced histamine release from dispersed human lung mast cells was observed after pretreatment with the serine protease inhibitor diisopropylfluorophosphate (DFP) or the chymotrypsin-like enzyme inhibitor N-tosyl-L-phenylalanine chloromethylketone (TPCK) but not with the trypsin-like enzyme inhibitor N-tosyl-L-lysine chloromethylketone (TLCK). These results indicate that a chymase is probably an important factor in a late phase of human lung mast cell activation.     

类糜蛋白酶抑制剂对人结肠肥大细胞组胺释放的影响

目的　研究类糜蛋白酶抑制剂对人结肠肥大细胞释放组胺的影响。方法　用酶消化人结肠组织并分离细胞成份。激发过程在LP4试管中、37℃条件下完成。组胺水平用以玻璃纤维为基础的荧光方法测定。结果　类糜蛋白酶抑制剂ZIGPFM、TPCK和α1 抗胰蛋白酶无明显刺激人类结肠肥大细胞释放组胺的作用。 3种类糜蛋白酶抑制剂均可以剂量依赖性方式抑制抗IgE抗体诱导的组胺释放 ,最大浓度的ZIGPFM(1mmol·L-1)、TPCK(80mmol·L-1)和α1 抗胰蛋白酶(30mmol·L-1)可分别抑制 37%、2 6 %和 36 8%的组胺释放。在 37℃条件下同结肠细胞预培养 2 0min与无预培养相比 ,ZIGPFM和TPCK抑制抗IgE抗体诱导的组胺释放的作用略有增强。 3种类糜蛋白酶抑制剂均可以剂量依赖性方式抑制CI诱导的组胺释放 ,最大抑制范围在 2 3 6 %～ 35 %之间。在 37℃条件下同结肠细胞预培养 2 0min与无预培养相比 ,TPCK对CI诱导的组胺释放的抑制作用略有增强 ,但ZIGPFM则无此特点。结论　我们发现了类糜蛋白酶抑制剂可抑制人结肠肥大细胞IgE依赖性和非依赖性组胺释放 ,提示类糜蛋白酶抑制剂可能有抗炎症性肠病的作用 ,可研究开发     

The inhibition of histamine release from rat peritoneal mast cells by non-steroid anti-inflammatory drugs and its reversal by calcium.

1 The non-steroid anti-inflammatory drugs, indomethacin, flufenamate and meclofenamate, inhibited the release of histamine from rat peritoneal mast cells induced by pharmacological or immunological challenge in vitro. 2 Anti-inflammatory steroids had little effect on histamine release from the mast cells. 3 Th inhibition of histamine release by the aspirin-like drugs was not prevented by incubation with glucose, unlike the inhibition of 2,4,dinitrophenol or antimycin-A. This suggests that the non-steroid anti-inflammatory compounds do not act by preventing the energy production from oxidative metabolism, required for histamine release. 4 The inhibition of the calcium ionophore A23187-induced histamine release by the aspirin-like drugs was reversed by an increase in the calcium concentration of the incubation medium. 5 The results suggest that the non-steroid anti-inflammatory compounds inhibit histamine release by actions on calcium influx into the mast cell, or on calcium mobilization or utilization within the mast cell.     

Compound 48/80-induced secretion of histamine from rat peritoneal mast cells depends on a tryptase controlled step also leading to chymase activity.

Compound 48/80 caused activation of rat mast cell tryptase and chymase along with the release of histamine. Following low speed centrifugation, tryptase remained essentially in the supernatant while chymase sedimented. Enzyme activities as well as histamine release were inhibited by phenylmethyl-sulfonyl fluoride and tosyl-lysine chloromethyl ketone, which are respectively unspecific and specific inhibitors of trypsin-like enzymes. Chymostatin inhibited chymase, but not the release of histamine by 48/80. Tryptase activity thus seems to be essentially involved in the mechanism of histamine release, while chymase activity may be merely one of its accompanying events.     

The effect of methyltransferase inhibitors on histamine release from human dispersed lung mast cells activated with anti-human IgE and calcium ionophore A23187

Inhibitors of adenosylmethionine (AdoMet)-dependent methyltransferases reduce histamine release from enzymatically dispersed human lung mast cells activated with either anti-human IgE or calcium ionophore A23187. The IC25 values for adenosine and 3-deazaadenosine (DZA) inhibiting anti-IgE-induced histamine release were 395 microM and 301 microM respectively. The addition of homocysteine thiolactone (Hcy) potentiated the effects of adenosine and DZA, reducing their IC25 values to 32 microM and 10.5 microM respectively. The adenosine deaminase (adenosine aminohydrolase EC 3.5.4.4) inhibitors erythro-9-(2-hydroxy-3-nonyl)-adenine (EHNA) inhibited anti-IgE-induced histamine release with an IC50 of 162 microM. This inhibition was not potentiated by Hcy. The combination of DZA and Hcy effectively inhibited histamine release induced by concentrations of A23187 which released a similar amount of histamine to anti-IgE. However the combination was 17 times less potent against A23187-compared with anti-IgE-induced release. These observations suggest that AdoMet-dependent methyltransferases play an important role in IgE-dependent histamine release from human lung mast cells but their role in A23187-induced release is less clear.     

Activation of human tonsil and skin mast cells by agonists of proteinase activated receptor-2

Aim: To investigate the effects of the agonists of proteinase activated receptor (PAR)-2,and histamine on degranulation of human mast cells. Methods: Human mast cells were enzymatically dispersed from tonsil and skin tissues. The dispersed cells were then cultured with various stimuli, and tryptase and histamine levels in cell supernatants collected from challenge tubes were measured. Results:PAR-2 agonist peptide SLIGKV provoked a dose-dependent release of histamine from skin mast cells. It also induced tryptase release from tonsil mast cells, tcLIGRLO appeared less potent than SLIGKV in induction of release of histamine and tryptase. Trypsin was able to induce a “bell” shape increase in tryptase release from tonsil mast cells. It was also able to induce a dose-dependent release of histamine from both tonsil and skin mast cells. The actions of trypsin on mast cells were inhibited by soy bean trypsin inhibitor (SBTI) or α1-antitrypsin (α1-AT).Time course study revealed that both stimulated tryptase or histamine release initiated within 10s and reached their peak release between 4 and 6min. Pretreatment of cells with metabolic inhibitors or pertussis toxin reduced the ability of mast cells to release tryptase or histamine. Conclusion: It was demonstrated that the in vitro tryptase release properties of human tonsil and skin mast cells suggested a novel type of mast cell heterogeneity. The activation of mast cells by PAR-2 agonists indicated a self-amplification mechanism of mast cell degranulation.     

The effect of ribose and purine modified adenosine analogues on the secretion of histamine from rat mast cells induced by ionophore A23187

The purine nucleosides adenosine and 2',5'-dideoxyadenosine (2',5'ddAdo) enhance and inhibit respectively the anti-IgE-induced secretion of histamine and transient rise in cellular levels of cyclic AMP in rat mast cells. These findings have provided evidence for a role for cyclic AMP in the activation of mast cell secretion. It has been generally accepted that the nucleosides mediate their effects on mast cells by altering adenylate cyclase activity. We have investigated the effect of various purine and ribose modified analogues of adenosine on secretion of histamine from rat mast cells induced by ionophore A23187 for which there is no associated elevation in cyclic AMP and no evidence for the activation of adenylate cyclase in its mechanism of action. Adenosine and N6, phenylisopropyladenosine (0.01-1000 microM) (activators of adenylate cyclase in many tissues) enhanced the secretion of histamine induced by ionophore A23187 and anti-IgE. Two inhibitors of adenylate cyclase had differential effects on secretion. 2',5'ddAdo (100-1000 microM) inhibited both A23187-and anti-IgE-mediated secretion; whilst 9-beta-D-arabinofuranosyladenine had no effect on secretion. These results suggest that the ability of these nucleosides to modulate histamine secretion is unrelated to their effects on adenylate cyclase.     

Effect of a Chymotrypsin-like Inhibitor,TPCK, on Histamine Release from Cultured Human Mast Cells

The involvement of endogenous proteases in the secretory process from human mast cells remains to be clarified. A chymotrypsin-like protease inhibitor, N-tosyl-l-phenylalanylchloromethyl ketone (TPCK), blocked both FcεRI- and A23187-mediated histamine release from cultured human mast cells at concentrations above 1 μm. At 10 μm, the concentration that completely inhibited FcεI-mediated histamine release, TPCK did not inhibit the chymase activity of the lysate or that in intact cells. The addition of TPCK to cells 30 min before challenge did not affect FcεRI- or A23187-mediated Ca²⁺ mobilization. These findings suggest that a TPCK-sensitive molecule distinct from chymase is involved in a late stage of the process of histamine release from mast cells in man.     

Histamine release induced from rat mast cells by the ionophore A23187 in the absence of extracellular calcium

Isolated rat mast cells were used to study whether ionophore A23187 could induce histamine release by mobilizing cellular calcium. The histamine release was a slow process which was completed after about 20 min incubation with A23187. The A23187-induced histamine release was inhibited after incubation of the cells with EDTA for 1 h in a 37°C water bath in calcium-free medium. Reintroduction of calcium in excess of EDTA induced the release of histamine. The observations suggest that A23187 can induce histamine release by mobilizing a cellular pool of calcium.     

Inhibition of calcium ionophore (A23187)-stimulated histamine release from rat peritoneal mast cells by azelastine: implications for its mode of action

Azelastine is a novel, orally effective, long-acting, antiallergic agent. The ability of azelastine to influence calcium ionophore A23187-induced histamine release from rat peritoneal mast cells was investigated and compared with selected antiallergic drugs. The concentrations of drugs required to inhibit A23187 (0.2 microM)-stimulated histamine release by 50% (IC50S, microM) were as follows: azelastine 5; diphenhydramine 52; and ketotifen 200. Theophylline and sodium cromoglycate in a concentration range of 0.1-1000 microM failed to exert any significant inhibition of histamine release. The inhibitory effects of azelastine on A23187-stimulated histamine release were antagonized by high concentrations of exogenous Ca2+ ions. These data suggest that azelastine inhibits A23187-stimulated histamine release by interfering with the influx of Ca2+ into the mast cells.     

Kinetics of the inhibitory effect of flavonoids on histamine secretion from mast cells

The effect of cromoglycate and of natural flavonoids on histamine release from peritoneal rat mast cells induced by compound 48/80 and ionophore A23187 was studied according to preincubation time of mast cells with drugs and to incubation time of cells with the triggering agent. Preincubation of cells with cromoglycate, dihydroquercetin and amentoflavone, a biflavonoid, decreased the potency of drugs to inhibit the ionophore-induced release; the optimal inhibitions were observed when drugs were added simultaneously with the ionophore A23187. In contrast, a short preincubation (2 min) of cells with quercetin or luteolin decreased their inhibitory effect on the ionophore-induced release, whereas a longer preincubation increased the inhibition. When compound 48/80 was used to trigger histamine secretion, the inhibitory potencies of all the compounds used were decreased according to preincubation time. Dihydroquercetin (taxifolin), previously considered as inactive, showed an interesting cromoglycate-like behaviour.     

Utilization of adenosine triphosphate in rat mast cells during histamine release induced by the ionophore A23187.

The role of endogenous adenosine triphosphate (ATP) in histamine release from rat mast cells induced by the ionophore A23187 in vitro has been studied. 2 The amount of histamine released by calcium from rat mast cells primed with the ionophore A23187 was dependent on the ATP content of the mast cells. 3 In aerobic experiments a drastic reduction in mast cell ATP content was found during the time when histamine release induced by A23187 takes place. 4 Anaerobic experiments were performed with metabolic inhibitors (antimycin A, oligomycin, and carbonyl cyanide p-trifluorometroxyphenylnydrazone), which are known to block the energy-dependent calcium uptake by isolated mitochondria. The mast cell ATP content was reduced during A23187-induced histamine release under anaerobic conditions in the presence of glucose. This indicates an increased utilization of ATP during the release process. 5 The observations are consistent with the view that energy requiring processes are involved in ionophore-induced histamine release from rat mast cells although part of the ATP reduction in the aerobic experiments may be due to an uncoupling effect of calcium on the oxidative phosphorylation.     

The sensitivity to Zn2+ discriminates between typical and atypical mast cells.

The effects of zinc gluconate have been studied on rat peritoneal mast cells and rat basophilic leukemia cells (RBL 2H3) stimulated by various secretagogues. The IC50's of zinc gluconate on peritoneal cells were (microM): 1.6, 1.9, 5.4 and 18 for ionophore A23187, phorbol 12-myristate 13-acetate, substance P and immunoglobulin E-antigen, respectively. Higher concentrations of zinc gluconate were required to inhibit histamine secretion from RBL 2H3 cells, i.e. 12 microM (ionophore A23187) and 140 microM (immunoglobulin E-antigen). Zinc gluconate (10(-4) to 10(-3) M) also inhibited the IgE-dependent contraction of guinea pig trachea but was unable to affect that induced by exogenous histamine. These results suggest that zinc gluconate acts intracellularly and is selective of "typical" or "connective tissue" mast cells.     

Role of calcineurin in the regulation of human lung mast cell and basophil function by cyclosporine and FK506

BACKGROUND AND PURPOSE: Cyclosporine and FK506 are thought to act by targeting the Ca2+-dependent protein phosphatase, calcineurin. The aim of the present study was to determine whether cyclosporine and FK506 stabilize mast cells and basophils by interacting with calcineurin. EXPERIMENTAL APPROACH: The effects of cyclosporine and FK506 on the IgE-mediated release of histamine from mast cells and basophils were evaluated. The presence of calcineurin in cells was determined by Western blotting. Ca2+-dependent protein phosphatase activities were assessed in cell extracts using a synthetic phosphorylated peptide that is known to serve as a substrate for calcineurin. KEY RESULTS: FK506 was about 100-fold more potent than cyclosporine as an inhibitor of IgE-dependent histamine release from mast cells and basophils. Immunoblotting of solubilized preparations of purified cells demonstrated the presence of calcineurin in mast cells and basophils. In enzyme assays, mast cells expressed approximately 7-fold higher Ca2+-dependent protein phosphatase activity than basophils. Whereas cyclosporine effectively inhibited Ca2+-dependent protein phosphatase activity in cell extracts, FK506 was considerably less effective. CONCLUSIONS AND IMPLICATIONS: FK506 and cyclosporine inhibit the stimulated release of histamine from mast cells and basophils. However, the ability of cyclosporine, but not FK506, to inhibit Ca2+-dependent protein phosphatase activity questions whether FK506 stabilizes mast cells and basophils by interacting with calcineurin.     

Recovery of purification-associated reduction in antigen-induced histamine release from rat peritoneal mast cells.

Immunoglobulin E (IgE)-dependent histamine release from purified rat peritoneal mast cells (PMC) is very low in comparison to that from a non-purified preparation (PEC). The reduced histamine release from PMC is recovered or potentiated by reconstitution with separated non-mast cells (NMC). In the present study, further characterization was undertaken to elucidate the mechanisms involved. Sensitized mast cells were recovered from peritoneal cavities of rats, and purified by density gradient centrifugation with Percoll. Effects of NMC reconstitution, membrane fraction of NMC, NMC incubation supernatant, adhesion molecules and extracellular matrix proteins on IgE-dependent histamine release from PMC were examined. IgE-dependent histamine release was significantly potentiated by NMC reconstitution to PMC. The potentiation was dependent on the concentration of NMC reconstituted and reached a plateau after 30 min incubation. Increasing concentration of PMC did not affect the histamine release. Membrane fraction prepared from NMC also potentiated PMC histamine release in a dose-dependent manner. The potentiation reached a plateau in 5 min. Furthermore, incubation supernatant of NMC potentiated PMC histamine release. Antibodies against intercellular adhesion molecule (ICAM)-1, lymphocyte function-associated antigen (LFA)-1, very late activation antigen (VLA)-1, VLA-4 and VLA-6, and fibronectin did not affect the potentiation of PMC histamine release by NMC reconstitution. Fibronectin, laminin and collagen failed to potentiate PMC histamine release. These results indicate that the membrane component(s) of NMC in the rat peritoneal cavity seems to modulate IgE-dependent histamine release from peritoneal mast cells of rats, and that the active molecule(s) may be released from NMC. Adhesion molecules such as ICAM-1, LFA-1 and VLA are not involved.     

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.     

β‐eudesmol suppresses allergic reactions via inhibiting mast cell degranulation

The regulatory effect of β‐eudesmol, which is an active constituent of Pyeongwee‐San (KMP6), is evaluated for allergic reactions induced by mast cell degranulation. Phorbol 12‐myristate 13‐acetate (PMA) plus calcium ionophore A23187‐stimulated human mast cell line, HMC‐1 cells, and compound 48/80‐stimulated rat peritoneal mast cells (RPMCs) are used as the in vitro models; mice models of systemic anaphylaxis, ear swelling, and IgE‐dependent passive cutaneous anaphylaxis (PCA) are used as the in vivo allergic models. The results demonstrate that β‐eudesmol suppressed the histamine and tryptase releases from the PMA plus calcium ionophore A23187‐stimulated HMC‐1 cells. β‐eudesmol inhibits the expression and activity of histidine decarboxylase in the activated HMC‐1 cells. In addition, β‐eudesmol inhibits the levels of histamine and tryptase released from the compound 48/80‐stimulated RPMCs. Furthermore, β‐eudesmol decreases the intracellular calcium level in the activated RPMCs. β‐eudesmol also decreases the compound 48/80‐induced mortality and ear swelling response. β‐eudesmol suppresses the serum levels of histamine, IgE, interleukin (IL)‐1β, IL‐4, IL‐5, IL‐6, IL‐13, and vascular endothelial growth factor (VEGF) under PCA mice as well as PCA reactions. Therefore, the results from this study indicate the potential of β‐eudesmol as an anti‐allergic drug with respect to its pharmacological properties against mast cell‐mediated allergic reactions.