Distinct patterns of mucosal apoptosis in H pylori-associated gastric ulcer are associated with altered FasL and perforin cytotoxic pathways.

AIM: To analyze the level of apoptosis in different mucosal compartments and the differential expression of Fas/Fas-ligand and perforin in H pylori-associated gastric ulcer. METHODS: Antral specimens from patients with H pylori-related active gastric ulcer (GU), H pylori-related gastritis, and non-infected controls were analysed for densities and distribution of apoptotic cells determined by the TdT-mediated dUDP-biotin nick-end-labelling method. GU patients were submitted to eradication therapy with follow-up biopsy after 60 d. Fas, FasL, and perforin-expressing cells were assessed by immunoperoxidase, and with anti-CD3, anti-CD20 and anti-CD68 by double immunofluorescence and confocal microscopy. Quantitative analysis was performed using a computer-assisted image analyser. RESULTS: H pylori-infected antrum showed greater surface epithelial apoptosis which decreased after eradication therapy. In the lamina propria, higher rates of mononuclear cell apoptosis were observed in H pylori-gastritis. Co-expression of Fas with T-cell and macrophage markers was reduced in GU. FasL- and perforin-expressing cells were increased in H pylori-infection and correlated with epithelial apoptosis. Perforin-expressing cells were also increased in GU compared with H pylori-gastritis. CONCLUSION: Epithelial apoptosis is increased in H pylori-infection and correlates to FasL- and perforin-expression by T cells. Expression of perforin is correlated with the tissue damage, and may represent the enhancement of a distinct cytotoxic pathway in GU. Increased expression of FasL not paralleled by Fas on T-cells and macrophages may indicate a reduced susceptibility to the Fas/FasL-mediated apoptosis of lymphoid cells in H pylori-infection.

Apoptosis in the intestinal mucosa of patients with inflammatory bowel disease: evidence of altered expression of FasL and perforin cytotoxic pathways.

BACKGROUND AND AIMS: Abnormal apoptosis may result in the persistence of activated intestinal T-cells in inflammatory bowel disease (IBD). We investigated apoptosis in distinct mucosal compartments, and the expression of Fas/Fas ligand and perforin in the inflamed and non-inflamed intestinal mucosa of patients with IBD. METHODS: Colon specimens from 15 patients with ulcerative colitis (UC) and inflamed and non-inflamed mucosa from 15 patients with Crohn's disease (CD) were analysed for densities and distribution of apoptotic cells determined by the terminal deoxynucleotidyltransferase-mediated dUDP-biotin nick-end labelling (TUNEL) method. Fas, FasL, and perforin-expressing cells were assessed by immunoperoxidase, and with anti-CD3, anti-CD20 and anti-CD68, by double immunofluorescence with confocal microscopy. Quantitative analysis was performed using a computer-assisted image analyser. RESULTS: Colonic lamina propria (LP) and epithelium from patients with UC showed higher rates of apoptosis than controls, but no difference was shown regarding patients with CD. In LP, co-expression of Fas was reduced with T-cells in inflamed CD mucosa, and with macrophages in all patients with IBD. No difference was found in the expression of Fas on B-cells. Rates of FasL-expressing cells in LP were higher in IBD than in controls, with no correlation with the rates of apoptosis. Rates of perforin-expressing cells in LP were greater in UC than in controls, and correlated to the rates of apoptosis. No difference was shown regarding the inflamed and non-inflamed CD mucosa. Rates of FasL and perforin-expressing intra-epithelial lymphocytes showed no difference among groups. CONCLUSIONS: Increased expression of FasL in IBD colonic LP not parallelled by Fas on T-cells and macrophages may indicate a reduced susceptibility to the Fas/FasL-mediated apoptosis of lymphoid cells. Expression of perforin is correlated to the tissue damage, and may represent the enhancement of a distinct cytotoxic pathway in UC.

Small bowel of patients with asthma and allergic rhinitis: absence of inflammation despite the presence of major cellular components of allergic inflammation.

Eosinophils participate in the pathogenesis of inflammatory diseases of the respiratory tract and the gut. We investigated the constitutive presence of eosinophils and mononuclear cells in the macroscopically normal duodenal mucosa of patients with asthma and allergic rhinitis. Macroscopically normal duodenal specimens were obtained at routine endoscopy for upper gastrointestinal symptoms from 16 patients with asthma and 13 patients with allergic rhinitis. Twelve nonatopic patients with irritable bowel syndrome were studied as controls. Specimens were analyzed by immunohistochemistry using a panel of antibodies to human eosinophil cationic protein clone EG1 (EG1) and clone EG2 (EG2), anti-human interleukin (anti-hIL)-5, anti-hIL-4, anti-CD4, and anti-CD68. Significantly increased numbers of eosinophils stained with EG1 and EG2 were found in the duodenum of patients with asthma and allergic rhinitis compared with controls. IL-5+ cells and IL-4+ cells were detected in significantly increased numbers in the duodenal mucosa of patients with asthma and rhinitis compared with controls. Mononuclear cells expressing CD4 (helper T cells) and CD68 (macrophages) also were significantly increased in the duodenal mucosa of asthma and rhinitis compared with controls. Accumulation of eosinophils in conjunction with IL-4+ cells and IL-5+ cells in the noninflamed duodenal mucosa may reflect a predominant T helper cell subset 2 systemic immune response in patients with asthma and allergic rhinitis. The absence of intestinal inflammation despite the marked presence of cells implicated in the allergic inflammation suggests that local mechanisms might determine the state of nonresponsiveness in the gut mucosa of patients with asthma and allergic rhinitis.