Chymotrypsin- and trypsin-type serine proteases in rat mast cells: properties and functions

Two of the major enzymes present in and released from rat mast cells are chymotrypsin-type serine protease (chymase) and trypsin-type serine protease (tryptase), and these have been postulated to be important in the inflammatory reactions. There have been no clear data regarding the trypsin-type protease in rat mast cells. Tryptase was recently purified from rat peritoneal mast cells with an associated protein (trypstatin) that inhibited the protease activity above pH 7.5. Chymase was also purified from rat peritoneal cells by employing a one-step method involving hydrophobic chromatography on octyl-Sepharose 4B or arginine-Sepharose 4B. The properties of chymase and tryptase were described in relation to substrate specificity and their relative sensitivity to inhibitors. It was found that proteolytic activities of these enzymes were modulated by naturally occurring substances, such as phosphoglycerides, long-chain fatty acids, and trypstatin. There is as yet little evidence for the physiological roles of these enzymes in the inflammatory reaction. It has been found that the specific, low-molecular-weight inhibitor of chymase, chymostatin, and that of tryptase, leupeptin, inhibit histamine release induced by addition of anti-rat IgE to mast cells. However, the inhibitors with molecular weights of more than 6000 were found to have no effect in this process. The data suggest that chymase and tryptase in mast cell granules play a crucial or significant role in the process of degranulation.     

实电解质钙可诱发人肥大细胞组胺和类胰蛋白酶分泌

目的: 利用人大肠组织的肥大细胞和肥大细胞激活的体外研究系统,评价实电解质钙(calcium ionophore A23187, CI)诱导肥大细胞释放类胰蛋白酶和组胺的能力和机制.方法: 经酶悬浮的人大肠肥大细胞与CI共同培养后收集上清液,并用酶联免疫吸附试验(ELISA)的方法检测类胰蛋白酶分泌量,用以玻璃纤维为基础的荧光比色法检测组胺释放量.结果: 经过15 min的培养,CI可引起浓度相关性的组胺和类胰蛋白酶释放.其中组胺的最大分泌量比基础分泌量超出了5.3倍以上,而类胰蛋白酶的最大分泌量则比基础分泌量超出了2.8倍以上.CI在浓度高于1.0 μmol/L时引起的组胺释放量明显多于类胰蛋白酶释放量.时间关系曲线显示,CI的作用从加样后10 s开始,6 min后达高峰并至少持续15 min.百日咳毒素和代谢抑制剂均能抑制CI引起的组胺和类胰蛋白酶释放.结论: 人大肠肥大细胞在受到CI刺激时具有释放类胰蛋白酶和组胺的能力,这个过程与肥大细胞膜G蛋白偶联受体的激活有关,并消耗能量.     

Grifola frondosa extract and ergosterol reduce allergic reactions in an allergy mouse model by suppressing the degranulation of mast cells

ABSTRACT

The increasing number of patients suffering from allergic diseases is a global health problem. Grifola frondosa is an edible mushroom consumed as a health food in Asia, and has recently been reported to have anti-allergic effects. We previously reported that G. frondosa extract (GFE) and its active components, ergosterol and its derivatives, inhibited the antigen-induced activation of RBL-2H3 cells. Here, we demonstrated that GFE and ergosterol also had an inhibitory effect on the degranulation of bone marrow–derived mast cells (BMMCs) and alleviated anaphylactic cutaneous responses in mice. Using an air pouch-type allergic inflammation mouse model, we confirmed that oral administration of GFE and ergosterol suppressed the degranulation of mast cells in vivo. Our findings suggest that G. frondosa, including ergosterol as its active component, reduces type I allergic reactions by suppressing mast cell degranulation in mice, and might be a novel functional food that prevents allergic diseases.     

SG-HQ2 inhibits mast cell-mediated allergic inflammation through suppression of histamine release and pro-inflammatory cytokines

In this study, we investigated the effect of 3,4,5-trihydroxy-N-(8-hydroxyquinolin-2-yl)benzamide) (SG-HQ2), a synthetic analogue of gallic acid (3,4,5-trihydroxybenzoic acid), on the mast cell-mediated allergic inflammation and the possible mechanism of action. Mast cells play major roles in immunoglobulin E-mediated allergic responses by the release of histamine, lipid-derived mediators, and pro-inflammatory cytokines. We previously reported the potential effects of gallic acid using allergic inflammation models. For incremental research, we synthesized the SG-HQ2 by the modification of functional groups from gallic acid. SG-HQ2 attenuated histamine release by the reduction of intracellular calcium in human mast cells and primary peritoneal mast cells. The inhibitory efficacy of SG-HQ2 was similar with gallic acid. Enhanced expression of pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β, interleukin-4, and interleukin-6 in activated mast cells was significantly diminished by SG-HQ2 100 times lower concentration of gallic acid. This inhibitory effect was mediated by the reduction of nuclear factor-κB. In animal models, SG-HQ2 inhibited compound 48/80-induced serum histamine release and immunoglobulin E-mediated local allergic reaction, passive cutaneous anaphylaxis. Our results indicate that SG-HQ2, an analogue of gallic acid, might be a possible therapeutic candidate for mast cell-mediated allergic inflammatory diseases through suppression of histamine release and pro-inflammatory cytokines.     

IgE-Independent Activation of Human Mast Cells Indicates their Role in the Late Phase Reaction of Allergic Inflammation

Mast cells are tissue dwelling cells that have a clear-cut pathologic role in allergy. Besides that, they participate in several chronic inflammatory conditions, helminitic parasitosis, and in some solid tumor reactions, but also in physiological situations, such as wound healing and innate immunity. Mast cells produce and release various mediators after activation induced by either IgE-dependent or IgE-independent mechanisms. Although much information has been gathered on the immunological (IgE-dependent) mast cell activation both in vivo and in vitro, not much is known about the non-immunological (IgE-independent) activation particularly in human mast cells. Mast cell IgE-independent activation is mediated through Gi3alpha which has been identified in rat mast cells as the pertussis toxin (Ptx)-sensitive heterotrimeric G protein that interacts with cationic secretagogues inducing PLC-independent mast cell exocytosis. Mast cell IgE-independent activation in allergy most likely occurs when mast cells encounter eosinophils, the main inflammatory cells that persist throughout the late and chronic phases of the allergic reaction. This review summarizes the influence of eosinophils on mast cell activation demonstrating that IgE-independent activation has a significant role in pathophysiological processes.     

Neovascularization and mast cells with tryptase activity increase simultaneously in human pterygium

Mast cells (MC) have been implicated in both normal and pathological angiogenesis, such as that in chronic inflammatory diseases and tumors. This assumption is partially supported by the close structural association between MC and blood vessels and the recruitment of these cells during tumor growth. MC release a number of angiogenic factors among which tryptase, a serine protease stored in MC granules, is one of the most active. In this study, we correlate the extent of angiogenesis with the number of tryptase-reactive MC in tissue fragments from pterygium and normal bulbar conjunctiva investigated by immunohistochemistry, using two murine monoclonal antibodies against the endothelial cell marker CD31 and the MC marker tryptase. Angiogenesis, measured as microvessel density, was highly correlated with MC tryptase-positive cell count in pterygium tissues. These results suggest that the characteristic neovascularization observed in pterygium may be sustained, at least in part, by MC angiogenic mediators, in particular tryptase.     

Analysis of the effect of a 60 Hz AC field on histamine release by rat peritoneal mast cells

Reports have indicated effects of electromagnetic fields on inflammatory processes in vivo. To begin a systematic approach toward separating and examining the many components of such responses, we created and tested a temperature-controlled device to develop 5 mT 60 Hz magnetic fields for studies of the effects of fields on mast cells, a key component in acute inflammatory responses. Such fields have been reported to modulate cell activity, including changes in membrane function, in various systems. The magnetic field was generated using a solenoid and calibrated with an induction probe. Tests of mast cell function were determined by histamine release response to stimulation by compound 48/80, using both an “expose then test” and a “test during exposure” protocol. Aliquots not treated with 48/80 were used to evaluate field treatment effects on spontaneous histamine release. Freshly harvested rat peritoneal mast cells were exposed to the magnetic field for periods of 30 min to 2 h at 37 °C. They showed no significant degranulation during treatment, nor did they show reduced sensitivity to the degranulating agent 48/80. These observations are consistent with a model in which such processes are exclusively reflexive by the cells using field-independent membrane systems. This observation is very useful and was needed before examining longer term exposures in which gene expression in the cells might be influenced; this is the first such report of in vitro exposure of purified mast cells under these conditions and will further the study of the effects of electromagnetic fields on cell types active in acute inflammation. Bioelectromagnetics 19:192–198, 1998. © 1998 Wiley-Liss, Inc.     

Redox regulation of mast cell histamine release in thioredoxin-1 （TRX） transgenic mice

Thioredoxin-1 （TRX） is a stress-inducible redox-regulatory protein with antioxidative and anti-inflammatory effects. Here we show that the release of histamine from mast cells elicited by cross-linking of high-affinity receptor for IgE （FcεRI） was significantly suppressed in TRX transgenic （TRX-tg） mice compared to wild type （WT） mice. Intracellular reactive oxygen species （ROS） of mast cells stimulated by IgE and antigen was also reduced in TRX-tg mice compared to WT mice. Whereas there was no difference in the production ofcytokines （IL-6 and TNF-α） from mast cells in response to 2,4-dinitrophenylated bovine serum albumin （DNP-BSA） stimulation in TRX-tg and WT mice. Immunological status of TRX-tg mice inclined to T helper （Th） 2 dominant in primary immune response, although there was no difference in the population of dendritic cells （DCs） and regulatory T cells. We conclude that the histamine release from mast cells in TRX-tg mice is suppressed by inhibition of ROS generation. As ROS are involved in mast cell activation and facilitate mediator release, TRX may be a key signaling molecule regulating the early events in the IgE signaling in mast cells and the allergic inflammation.     

The role of mast cells in thioglycollate-induced inflammation

The possible role of mast cells in the initiation of inflammation was studied in genetically mast cell-deficient mice, WBB6F1-W/Wv. Inflammation was induced by i.p. injection of thioglycollate. The influx of neutrophils was markedly delayed in WBB6F1-W/Wv mice as compared to the WBB6F1-+/+, mice (congeneic controls). At the time (14 h) of maximum influx of neutrophils in WBB6F1-+/+ mice, thioglycollate caused a 3-fold increase in the total cell number in the peritoneal lavage fluid, and the neutrophil count was elevated 14-fold. At the same time point in W/Wv mice, the total cell number in the peritoneal lavage fluid was not increased significantly and the neutrophils were increased only three- to four-fold. Not only was the neutrophil influx in WBB6F1-W/Wv mice delayed, but the length of time during which the neutrophil count was elevated in the peritoneal fluid was significantly shortened. Transfer (i.p.) of mast cells cultured from the bone marrow of congeneic controls corrected the delay in the neutrophil influx. The magnitude of the neutrophil influx in WBB6F1-W/Wv mice was equivalent to that of congeneic controls 9 days after mast cell repletion. Histologic studies were performed to follow the migration and differentiation of mast cells after adoptive transfer into WBB6F1-W/Wv mice. No connective tissue mast cells could be identified on day 9 when the inflammatory reaction was restored. Migration of mast cells into the tissue, as studied in the cecum, progressed steadily. On day 9 after adoptive transfer, the mast cell number was 38% of congeneic controls. Therefore, the increase in thioglycollate-induced neutrophil influx in WBB6F1W/Wv mice after mast cell repletion seemed to be correlated, at least to some extent, with the migration of mast cells into tissues and not with differentiation into connective tissue mast cells. However, a certain maturation and differentiation may have occurred. These results suggest that mast cells play an important role, although they do not seem to be the only cell type responsible for the initiation of inflammation.     

Activation of mast cells is essential for development of house dust mite Dermatophagoides farinae-induced allergic airway inflammation in mice

In this study, we demonstrate that Dermatophagoides farinae (Der f), a major source of airborne allergens, but not OVA, could rapidly activate mast cells in mice. This was indicated by an elevation of serum mouse mast cell protease 1, a mast cell-specific proteinase, as early as 30 min after intratracheal challenge. Administration of sodium cromoglycate (40 mg/kg, i.p., 1 h before Der f instillation), a mast cell stabilizer, not only suppressed acute mouse mast cell protease 1 production but also attenuated the allergic airway inflammation provoked by repetitive Der f challenge in mice (five times at 1-wk interval). Der f induced the expression of mRNA for TNF-alpha, IL-1beta, IL-4, IL-6, IL-9, and IL-13 in mastocytoma P815 cells and stimulated both P815 cells and bone marrow-derived mast cells to produce IL-4, IL-6, and TNF-alpha in a dose- and time-dependent manner. Cycloheximide as well as sodium cromoglycate blocked the Der f-induced IL-4 production, indicating a de novo protein synthesis process. Supernatants of Der f-stimulated mast cells chemoattracted monocytes and T lymphocytes; they up-regulated the expression of costimulatory B7 molecules, eotaxin, RANTES, monocyte chemoattractant protein 1, and IFN-inducible protein 10 mRNA of alveolar macrophages; they supported PHA-induced T cell proliferation; and they promoted Th2 cell development. Our data indicate that mast cells may be an important cell type during the initiation of Der f sensitization in the airway by modulating the function of alveolar macrophages and T cells.     

蛋白酶激活受体2(PAR-2)激动剂对肥大细胞释放类胰蛋白酶的影响

研究反肉桂酰-亮-异亮-甘-精-亮-鸟-[酰胺]（tc-LIGRLO),一种PAR-2激动剂,对肥大细胞类胰蛋白酶释放的影响。结果显示,经过15min的培养,tc-LIGRLO可引起比基础分泌量增加1倍以上的类胰蛋白酶释放,作用强度超过抗IgE抗体和钙离子导入剂（calcium ionophore A23187,CI),而反PAR-2激动剂-反肉桂酰-鸟-亮-精-甘-异亮-亮-[酰胺]（tc-OLRGIL)无此作用,培养时间延长到30min时对tc-LIGRLO的作用无明显影响,其时间关系曲线表明,tc-LIGRLO的作用从1min开始,3min后达高峰,结果表明,PAR-2激动剂tc-LIGRLO是一种高效类胰蛋白酶释放刺激剂,在肥大细胞上可能有PAR-2存在。     

Cytotoxicity of Vibrio vulnificus cytolysin on rat peritoneal mast cells

Histamine has been thought to be a permeability enhancing factor in Vibrio vulnificus infection. The injection of living bacteria or purified V. vulnificus cytolysin (VVC) can cause lethality in mice by inducing hemoconcentration and increased vascular permeability. In the present study, we tried to identify whether histamine release causes the increased vascular permeability that is responsible for the lethal effect of VVC. Treatment of rat peritoneal mast cells with high concentrations of VVC caused the release of whole cellular histamine and lactate dehydrogenase (LDH). At concentrations less than 10 HU/ml, histamine and LDH were not released whereas preloaded 2-deoxy-D-glucose was rapidly effluxed with the concomitant decrease in cellular ATP. VVC-treated mast cells were refractory to the stimulation of histamine secretion by Compound 48/80 but remained fully responsive to Ca2+ plus GTP-gamma-S. These results indicate that histamine can be released from mast cells only when the concentration of VVC is high enough to cause the lysis of cells. At low concentrations, VVC does not induce the release of stored histamine from damaged cells. The intravenous injection of 80 HU purified VVC to rats, which can produce the calculated blood concentration of about 3 HU/ml, caused a marked increase in pulmonary vascular permeability, hemoconcentration and death. However, no increase in blood histamine level was detected. This level of VVC in rat blood was enough to cause severe hemoconcentration and lethality but might not be enough to cause cytolysis of the mast cells and resulting histamine release.     

Evolving functions of endothelial cells in inflammation

Inflammation is usually analysed from the perspective of tissue-infiltrating leukocytes. Microvascular endothelial cells at a site of inflammation are both active participants in and regulators of inflammatory processes. The properties of endothelial cells change during the transition from acute to chronic inflammation and during the transition from innate to adaptive immunity. Mediators that act on endothelial cells also act on leukocytes and vice versa. Consequently, many anti-inflammatory therapies influence the behaviour of endothelial cells and vascular therapeutics influence inflammation. This Review describes the functions performed by endothelial cells at each stage of the inflammatory process, emphasizing the principal mediators and signalling pathways involved and the therapeutic implications.     

Intestinal mast cells in gut inflammation and motility disturbances

Mast cells may be regarded as prototypes of innate immune cells that can be controlled by neuronal mediators. Their activation has been implicated in many types of neuro-inflammatory responses, and related disturbances of gut motility, via direct or indirect mechanisms that involve several mechanisms relevant to disease pathogenesis such as changes in epithelial barrier function or activation of adaptive or innate immune responses. Here we review the evidence for the involvement of mast cells in the inflammation of the bowel wall caused by bowel manipulation that leads to motility disturbances such as postoperative gastroparesis and ileus. Also in IBD there is substantial evidence for the involvement of mast cells and a mast cell-mediated neuroimmune interaction showing an increased number and an increased degranulation of mast cells. We discuss the potential of mast cell inhibition as a bona fide drug target to relief postoperative ileus. Further research on mast cell-related therapy either by stabilizing the mast cells or by blocking specific mast cell mediators as adjunctive therapy in IBD is encouraged, bearing in mind that several drugs currently used in the treatment of IBD possess properties affecting mast cell activities. This article is part of a Special Issue entitled: Mast cells in inflammation.     

Preliminary estimation of chemoattractant activity of staphylococcal serine proteinase in vitro

Human polymorphonuclear leukocytes isolated from peripheral blood of healthy donors migrated toward the staphylococcal serine proteinase.     

Physicochemical properties of alkaline serine proteases in alcohol

The alkaline proteases subtilisin Carlsberg and alcalase possess substantial enzymatic activity even when dissolved in ethanol. The crude enzymes were purified by gel filtration and the main fractions suspended in ethanol to give a translucent suspension. Both the supernatant and the resuspended precipitate after high-speed centrifugation were found to have enzymatic activities. The solubility of subtilisin Carlsberg in anhydrous ethanol was found to be 45.1g/ml and that of alcalase was 48.1g/ml by Coomassie blue dye-binding method using bovine serum albumin as a standard. In the presence of water, the solubility of both enzymes increased with water content. The stability of enzymes incubated in ethanol was assayed by their amidase and transesterase activities using Ala-Ala-Pro-Phe-pNA as substrate in phosphate buffer (pH8.2) and Moz-Leu-OBzl as substrate in anhydrous ethanol, respectively. The soluble enzymes have a half-life of about 36 hr and that of suspended enzymes about 50 hr in the amidase activity assay, whereas the same soluble enzymes have a half-life of about several hours and that of suspended enzymes 1 h by the transesterase activity assay. The stability of both enzymes decreased as water concentration increased. The diastereoselectivity of the enzyme-catalyzed hydrolysis of diastereo pairs of tetrapeptide esters,l-Ala-l-Ala-(d-orl-)Pro-l-Phe-OMe andl-Ala-l-Ala-(d-orl-)Ala-l-Phe-OMe, in phosphate is as high as that of the transesterification of these substrates in ethanol. It is concluded that active sites and selectivity of alkaline serine proteases in anhydrous alcohol are probably very similar to those in aqueous solution in spite of the fact that a lower reactivity is usually associated with the enzymes in nonaqueous solvents.     

Granule-associated serine neutral proteases of the mouse bone marrow-derived mast cell that degrade fibronectin: their increase after sodium butyrate treatment of the cells

Mouse bone marrow-derived mast cells, differentiated in vitro with concanavalin A splenocyte-conditioned medium and sensitized with monoclonal IgE, release neutral serine proteases after activation with specific antigen. Sodium dodecyl sulfate polyacrylamide gel electrophoretic (SDS-PAGE) analysis of the supernatants from immunologically activated mast cells revealed the presence of four prominent proteins of 27,000, 29,000, 30,000 and 31,000 m.w. When the supernatants and sonicated residual cells from antigen-challenged or nonactivated IgE-sensitized mast cells were incubated with [3H]diisopropylfluorophosphate ([3H]DFP) and the proteins were subjected to SDS-PAGE followed by autoradiography, proteins of 27,000 to 31,000 m.w. were labeled with [3H]DFP. The antigen-dependent release of labeled proteins was accompanied by a corresponding depletion of similarly sized [3H]DFP-labeled proteins from these cell pellets relative to unactivated cells. The SDS gels were also stained with Coomassie Blue and were sectioned to separate the individual proteins for measurement of their incorporated radioactivity; the net percent antigen-dependent release of all four [3H]DFP-labeled proteins ranged from 64 to 68% and was comparable to that of the secretory granule markers, beta-hexosaminidase and histamine. That the [3H]DFP-labeled proteins were derived from the secretory granules of the cells was supported by studies in which mast cells were cultured for 4 days in the presence of 1 mM sodium butyrate. This treatment produced a differential increase in their cellular content of histamine (10-fold), [3H]DFP binding proteins (two- to fourfold), and beta-hexosaminidase (minimally), while the net percent antigen-dependent release of each of these constituents was unchanged. After sensitization and antigen activation, the net percent release of histamine, beta-hexosaminidase, and the four [3H]DFP-labeled proteins was 51, 59, and 53 to 61%, respectively, for sodium butyrate-treated cells, and 53, 60, and 64 to 68%, respectively, for cells not exposed to sodium butyrate. Human plasma fibronectin was used as a substrate to demonstrate that the exocytosed proteins possessed proteolytic activity. As assessed by optical density scanning of stained SDS-PAGE gels of the substrate, the proteases present in the supernatants of antigen-activated cells, but not of sensitized unchallenged cells, rapidly degraded native fibronectin at pH 7.0. This degradation was prevented by pretreatment of the exocytosed proteins from immunologically activated cells for 90 min at 37 degrees C with 2 mM DFP.(ABSTRACT TRUNCATED AT 400 WORDS)     

The role of mast cells in atrial natriuretic peptide-induced cutaneous inflammation

Atrial natriuretic peptide (ANP) is widely distributed throughout the heart, skin, gastrointestinal and genital tracts, and nervous and immune systems. ANP acts to mediate vasodilation and induces mast cell activation in both human and rats in vitro. However, the mechanisms of ANP-induced mast cell activation, the extent to which ANP can induce tissue swelling, mast cell degranulation, and granulocyte infiltration in mouse skin are not fully understood. This issue was investigated by treatment with ANP in rat peritoneal mast cells (RPMCs) and mouse peritoneal mast cells (MPMCs) in vitro and by injection of ANP into the skin of congenic normal WBB6F1/J-Kit+/Kit+ +/+, genetically mast cell-deficient WBB6F1/J-Kit(W)/Kit(W-v) (W/W(v)) and mast cell-engrafted W/W(v) (BMCMC→W/W(v)) mice in vivo. ANP induced the release of histamine and TNF-α from RPMCs and enhanced serotonin release from MPMCs, in a dose-dependent fashion, as well as reduced cAMP level of RPMCs in vitro. In +/+ mice, ANP induced significant tissue swelling, mast cell degranulation, and granulocyte infiltration in a dose-dependent manner, whereas not in genetically mast cell-deficient W/W(v) mice. However, ANP-induced cutaneous inflammation has been restored in BMCMC→W/W(v) mice. These data indicate that mast cells play a key role in the ANP-induced cutaneous inflammation.