Deficiency of invariant natural killer T cells in coeliac disease.

BACKGROUND: Immunoregulatory invariant natural killer (iNK) T cells rapidly produce interleukin (IL)-4 and other cytokines that suppress a Th1 response and are deficient in some autoimmune diseases. AIM: The aim of this study was to investigate any deficiency of iNK T cells in coeliac disease. METHODS: Blood was collected from 86 subjects with coeliac disease and from 152 healthy control subjects for investigation of Valpha24+ T cells by flow cytometry. iNK T cells were assessed by Valpha24 and alpha-galactosylceramide/CD1d tetramer markers in 23 normal controls and 13 subjects with coeliac disease. Intracellular IL-4 was measured after anti-CD3 antibody stimulation. Duodenal biopsies were obtained in a subgroup of subjects with coeliac disease and control subjects for Valpha24 mRNA expression using relative PCR and for Valpha24+ T cells by immunofluorescence. RESULTS: The mean numbers of circulating Valpha24+ T cells and iNK T cells in coeliac disease were 27% (p<0.001) and 16% (p<0.001), respectively, of levels in control subjects. After in vitro anti-CD3 stimulation, numbers of IL-4+ producing iNK T cells from subjects with coeliac disease were unchanged but increased by 21% in control subjects. In subjects with coeliac disease, Valpha24 mRNA intestinal expression was reduced to 17% (p<0.001) by relative PCR and numbers of intestinal Valpha24+ T cells were 16% (p<0.01) of levels in control subjects. CONCLUSIONS: We conclude that Valpha24+ T cells and iNK T cells are deficient in coeliac disease. We speculate that this deficiency could contribute to the failure of immunological oral tolerance that seems to underlie this disease.

The role of small intestinal bacterial overgrowth, intestinal permeability, endotoxaemia, and tumour necrosis factor alpha in the pathogenesis of non-alcoholic steatohepatitis.

BACKGROUND: Small intestinal bacterial overgrowth may contribute to the development of non-alcoholic steatohepatitis, perhaps by increasing intestinal permeability and promoting the absorption of endotoxin or other enteric bacterial products. AIMS: To investigate the prevalence of small intestinal bacterial overgrowth, increased intestinal permeability, elevated endotoxin, and tumour necrosis factor alpha (TNF-alpha) levels in patients with non-alcoholic steatohepatitis and in control subjects. PATIENTS AND METHODS: Twenty two patients with non-alcoholic steatohepatitis and 23 control subjects were studied. Small intestinal bacterial overgrowth was assessed by a combined (14)C-D-xylose and lactulose breath test. Intestinal permeability was assessed by a dual lactulose-rhamnose sugar test. Serum endotoxin levels were determined using the limulus amoebocyte lysate assay and TNF-alpha levels using an ELISA. RESULTS: Small intestinal bacterial overgrowth was present in 50% of patients with non-alcoholic steatosis and 22% of control subjects (p=0.048). Mean TNF-alpha levels in non-alcoholic steatohepatitis patients and control subjects were 14.2 and 7.5 pg/ml, respectively (p=0.001). Intestinal permeability and serum endotoxin levels were similar in the two groups. CONCLUSIONS: Patients with non-alcoholic steatohepatitis have a higher prevalence of small intestinal bacterial overgrowth, as assessed by the (14)C-D-xylose-lactulose breath test, and higher TNF-alpha levels in comparison with control subjects. This is not accompanied by increased intestinal permeability or elevated endotoxin levels.

Expression of B7 costimulatory molecules by cells infiltrating the colon in experimental colitis induced by oral dextran sulfate sodium in the mouse.

BACKGROUND AND AIM: T-cell activation, mediated by the interaction with major histocompatibility complex (MHC)-peptide complexes and B7 costimulatory molecules on antigen-presenting cells, is an essential event in the pathogenesis of inflammatory bowel disease (IBD). We investigated the expression of B7 costimulatory molecules on cells in the colon in an experimental mouse model of IBD to determine whether the B7/ligand interaction could provide a target for therapeutic intervention in IBD. METHODS: Experimental colitis was induced in mice by oral consumption of water substituted with 5% dextran sulfate sodium (DSS). Mice (n=4) were killed 1, 2, 3, 4 and 7 days after commencing DSS consumption, and colonic tissue was collected and examined immunohistochemically for T cells, B cells, macrophages and cells expressing B7-1 or B7-2. RESULTS: Compared to control mice drinking water, macrophage numbers in the colonic epithelium were elevated sevenfold by day 1 and T cells were elevated threefold by day 3 following commencement of DSS consumption. Numbers of infiltrating B7-positive (B7+) cells were not significantly elevated until day 7 when B7-1+, B7-2+ cells and macrophages were increased 20-fold compared to normal mice. CONCLUSION: These results demonstrate that an initial and rapid infiltration of the colonic epithelium by B7-negative macrophages is followed by an infiltration of T cells and subsequent upregulation of the B7 costimulatory molecules potentiating the inflammatory reaction in this disease model. These results suggest an intervention strategy based on the blockade of the B7-costimulatory axis could find application in the treatment of inflammatory bowel disease.