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ABSTRACT: The aim of this study is to define the putative role of complement activation and mucosal mast cell (MMC) degranulation in the pathogenesis of rapid ischemia-reperfusion (I/R) injury. We prepared complement activity-depleted rats by the administration of the anti-complementary agent K-76COONa. To assess the role of MMC degranulation, we used the MMC stabilizer MAR-99 and genetically mast cell-deficient Ws/Ws rats. Autoperfused segments of the jejunum were exposed to 60 min of ischemia, followed by 60 min reperfusion. The epithelial permeability was assessed by (51)Cr-EDTA clearance rate, and the number of MMC was immunohistochemically assessed. I/R treatment induced a marked increase in mucosal permeability and MMC degranulation. The treatment with K-76COONa and MAR-99 significantly attenuated these changes. Furthermore, in Ws/Ws rats the increase in mucosal permeability and MMC degranulation was significantly attenuated. These findings indicate the role of complement activation and MMC activation in the pathogenesis of rapid intestinal I/R injury. A regulation of the complement activation and MMC degranulation may be one of the clinical strategies for prevention of I/R-induced mucosal injury.
Digestion 02/2001; 63 Suppl 1:103-7. · 2.05 Impact Factor
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ABSTRACT: Ws/Ws rats have a small deletion of the c-kit gene, and are deficient in both mucosal and connective tissue-type mast cells. In this study, the role of mucosal type mast cells (MMC) in the development of intestinal ischaemia-reperfusion injury was investigated in Ws/Ws rats. Autoperfused segments of the jejunum were exposed to 60 min of ischaemia, followed by reperfusion for various time periods. The epithelial permeability was then assessed by the 51Cr-EDTA clearance rate. In the control (+/+) rats, the maximal increase in mucosal permeability was achieved at 45 min of reperfusion. In contrast, this increase was significantly and potently attenuated in the Ws/Ws rats. Mucosal alkaline phosphatase activity decreased in the control (+/+) rats, but was not altered in the Ws/Ws rats. There were no differences in mucosal myeloperoxidase activity, indicating that granulocytes did not contribute to tissue injury. These results provide direct evidence for the role of mast cells in the pathogenesis of intestinal ischaemia-reperfusion injury.
Clinical & Experimental Immunology 05/1999; 116(1):90-3. · 3.36 Impact Factor
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ABSTRACT: In this study, we determined the role of mucosal mast cell (MMC) activation in the pathogenesis of intestinal ischaemia-reperfusion (I/R) injury by immunohistochemical analysis using anti-RMCP II antibody. In addition, we investigated the role of free-radical generation in the activation of MMCs in this model.
In the first experiment, rats were divided into four groups: (1) sham operated; (2) I/R + saline; (3) I/R + the mast cell stabilizer, MAR-99 (30 mg/kg); and (4) I/R + MAR-99 (100 mg/kg). Treatment with MAR-99 was started 1 h before the occlusion of the superior mesenteric artery (SMA). In the second experiment, rats were divided into five groups: (1) sham operated; (2) I/R + saline; (3) I/R + superoxide dismutase (SOD; 50,000 U/ml); (4) I/R + catalase (90,000 U/ml); and (5) I/R + allopurinol (50 mg/kg/day). Intravenous administration of SOD and catalase was performed 1 h before SMA occlusion. Oral administration of allopurinol was started 2 days before I/R surgery. We measured several parameters of intestinal mucosal injury and evaluated the degranulation of MMCs by using an immunohistochemical technique.
The number of resting MMCs, detected by anti-RMCP II antibody, was significantly decreased in the I/R-treated rats. The I/R treatment induced a decrease in the mucosal histamine content and an increase in plasma histamine levels. Mucosal permeability in the small intestine was significantly enhanced by I/R treatment. However, these changes were significantly prevented by pretreatment with the MMC stabilizer, MAR-99. Furthermore, administration of several free-radicals scavengers (SOD, catalase, and allopurinol) also blocked the I/R-induced degranulation of MMCs.
These data indicate that activation of MMCs was involved in the pathogenesis of I/R-induced intestinal mucosal injury. In addition, some parts of the I/R-induced MMC activation pathway were mediated by free-radical generation.
European Journal of Gastroenterology & Hepatology 09/1998; 10(8):659-66. · 1.76 Impact Factor
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ABSTRACT: Local secretion of complement components in the human intestine has been previously reported. However, the cellular source has not been identified. In this study, we demonstrate complement C3 and factor B mRNA expression in the normal colonic mucosa by in situ hybridization analysis. C3 and factor B genes were found to be expressed at high levels in the epithelial cells of the lower parts of the crypts in colonic mucosa, and this expression decreased gradually from the crypt base to the luminal surface. At the upper crypt and the luminal surface, these genes almost disappeared. C3 and factor B genes were expressed in all crypts at the same level. Furthermore, C3 and factor B gene expression was also identified in adenomas and carcinomas. In these neoplastic tissues, C3 and factor B genes were expressed uniformly, and the polarized distribution observed in the normal crypts was not detected. It is likely that complement components are locally synthesized in the intestine, and that these complement components may actively participate in normal immune and inflammatory responses over the enormous surface area of the intestinal mucosa.
Clinical & Experimental Immunology 03/1998; 111(3):477-83. · 3.36 Impact Factor
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ABSTRACT: We attempted to define the putative role of complement activation in association with mucosal mast cell (MMC) degranulation in the pathogenesis of rapid intestinal ischaemia-reperfusion (I/R) injury. We prepared complement activity-depleted rats by the administration of the anti-complement agent K-76COOH and the serine-protease inhibitor FUT-175. Autoperfused segments of the jejunum were exposed to 60 min of ischaemia, followed by reperfusion for various time periods, and the epithelial permeability was assessed by the 51Cr-EDTA clearance rate. The number of MMC was immunohistochemically assessed. In control rats, the maximal increase in mucosal permeability was achieved by 30-45 min of reperfusion. This increase was significantly attenuated by the administration of either K-76COONa alone or in combination with FUT-175. In contrast, the administration of carboxypeptidase inhibitor (CPI), which prevents the inactivation of complement-derived anaphylatoxins such as C5a, significantly enhanced the increase in I/R-induced mucosal permeability. These findings were confirmed morphologically by light microscopy and scanning electron microscopy. In addition, the I/R-induced mucosal injury was accompanied by a marked decrease in the number of MMC, and administration of K-76COOH significantly inhibited this change. These results indicate that complement activation and the generation of complement-derived anaphylatoxins are key events in I/R-induced mucosal injury. It is likely that intestinal I/R-induced mucosal injury may be partially mediated by MMC activation associated with the complement activation.
Clinical & Experimental Immunology 03/1998; 111(3):484-90. · 3.36 Impact Factor
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ABSTRACT: A molecular analysis of complement components (C3, C4, and factor B) in human saliva was performed by SDS-PAGE and immunoblotting. Complement C3 was detected as a molecule composed of a 115-kDa alpha-chain linked to a 70-kDa beta chain by disulfide bonds, and C3 levels ranged from 0.52 to 15.0 micrograms/ml (n = 15). C4 was detected as a triple-chain molecule (98-kDa alpha chain, 73-kDa beta chain, and 33-kDa gamma chain) linked by disulfide bonds, and C4 levels ranged from 0.086 to 4.8 micrograms/ml. Factor B was detected as a 100-kDa single chain, and factor B levels ranged from 0.042 to 0.62/microgram/ml. The sizes and subunit structures of the complement components in human saliva were compatible with those reported in human serum. The results of a hemolytic assay indicated that the complement molecules in human saliva were functionally active. These complement components may participate in the local immune and inflammatory responses in the oral cavity.
Journal of Clinical Immunology 10/1997; 17(5):404-7. · 3.08 Impact Factor
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ABSTRACT: A woman who had no known underlying diseases showed a persistent elevation (about 300 U/L) of serum aspartate aminotransferase (AST) without other abnormal laboratory findings. Cellolose gel electrophoresis showed that the AST activity in the patient had an atypical band with slower mobility than normal AST. When the sera from the patient and from a patient with acute hepatitis were mixed, the atypical band increased in density and the band of normal size AST disappeared. When the serum was fractionated on Sephadex G-200 gel filtration medium, almost all AST activity was found between the void volume and the gamma-globulin fraction. However, the AST activity in this fraction was not retained on dissociation into small AST by acid treatment. This suggests the loss of enzyme activity in dissociated small AST. The patient's serum was then incubated with iodine 125-labeled porcine AST; when this was fractionated on gel filtration medium, the main radioactivity was eluted in the void volume fraction. The binding activity for 125I-porcine AST was found in the gamma-globulin fraction obtained by gel filtration. The affinity constant of 125I-porcine AST binding to the gamma-globulin fraction was 1.0 x 10(-8) mol/L by Scatchard analysis. The binding gamma-globulin appeared to be (polyclonal) IgG, and the binding site was located in F(ab')2 and Fab fragments. The IgG could be bound with both human and porcine AST but not with chick AST. Thus the IgG appears specific for AST of mammalian species.(ABSTRACT TRUNCATED AT 250 WORDS)
Journal of Laboratory and Clinical Medicine 09/1994; 124(2):218-23. · 2.62 Impact Factor
