Effects of ethanol on gut-associated lymphoid tissues in a model of bacterial translocation: a possible role of apoptosis.

Chronic ethanol intake has been shown to be associated with immune suppression and impairment of epithelial barrier function. We investigated the effects of ethanol on intestinal immunity and its relation to bacterial translocation (BT). Male Wistar rats were assigned to one of three groups and received respective diets for 28 days. The ethanol-fed group [(EG); n=11] received a liquid diet containing 5% [volume/volume (vol./vol.)] ethanol; a pair-fed group [(PFG); n=11] received an isocaloric diet without ethanol; and a third (control) group [(CG); n=11] received water and chow ad libitum. On experimental day 29, animals in the EG and the PFG underwent distal ileum ligature and small intestine inoculation of a tetracycline-resistant Escherichia coli strain (TcR E. coli R6), by means of gastric intubation, followed by duodenal ligature. One hour after inoculation, mesenteric lymph nodes, right lobe of liver, spleen, and left kidney were excised for bacterial studies. Sections of jejunum and colon were immunostained, with the use of antibodies against immunoglobulin (Ig) A, T cells, macrophages, and proliferating cell nuclear antigen (PCNA). Apoptosis was determined by the terminal deoxynucleotidyltransferase TdT-mediated dUDP-biotin nick end labeling (TUNEL) method. Bacterial translocation rates were greater in the PFG compared with findings for the EG. Lamina propria of the jejunum of the EG showed a reduction in the densities of IgA+ cells and T cells compared with findings for the PFG and the CG. Colonic lamina propria of the EG showed reduced densities of IgA+ cells and macrophages compared with findings for the PFG and the CG. Apoptotic index was increased in the EG compared with findings for the PFG and the CG, in both jejunum and colon. Proliferation index was not significantly different among groups. Results of the current study show that chronic ethanol ingestion led to a reduction of cellular and humoral components of the intestinal mucosa, possibly by cell loss as a result of ethanol-induced apoptosis. The reduced rates of BT observed after chronic ethanol intake seem to indicate that factors irrespective of immune function might be involved in BT inhibition.

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.