Project description:Background and Aims: We have shown in several controlled rat and human infection studies that dietary calcium improves intestinal resistance and strengthens the mucosal barrier. Reinforcement of gut barrier function is also relevant for inflammatory bowel disease (IBD). Therefore, we investigated the effect of supplemental calcium on spontaneous colitis development in HLA-B27 transgenic rats, an experimental animal model of IBD. Methods: HLA-B27 transgenic rats were fed a purified high-fat diet containing either a low or high calcium content (30 and 120 mmol CaHPO4/kg diet, respectively) for almost 7 weeks. Inert chromium ethylenediamine-tetraacetic acid (CrEDTA) was added to the diets to quantify intestinal permeability by measuring urinary CrEDTA excretion. Relative fecal dry-weight was determined to quantify diarrhea. Colonic inflammation was determined histologically, and by measuring mucosal interleukin-1M-NM-2. In addition, colonic mucosal gene expression of individual rats was analyzed, using whole genome microarrays. Interesting results were verified by Q-PCR. Results: The high-calcium diet significantly prevented the increase in intestinal permeability and diarrhea with time in HLA-B27 rats developing colitis as compared to the low-calcium group. The histological colitis score and mucosal interleukin-1M-NM-2 levels were lower in high-calcium fed rats. Supplemental calcium prevented the colitis-induced increase in the expression of extracellular matrix remodeling genes (e.g. matrix metalloproteinases, procollagens and fibronectin), which was confirmed by Q-PCR. Conclusions: Dietary calcium inhibits colitis development in HLA-B27 transgenic rats. Calcium prevents the colitis-related increase in intestinal permeability, diminishes diarrhea, and lowers the inflammatory response in the mucosa, resulting in less extracellular matrix breakdown. Keywords: nutritional intervention Female HLA-B27/M-NM-22-microglobulin transgenic rats on an inbred Fisher 344 background (n=8 in experimental group and n=9 in control group) (Taconic Farms, Inc, Germantown, NY), 8-10 weeks old and with a mean body weight of 128 g at the start of the experiment, were housed individually in metabolic cages. Animals were kept in a temperature- and humidity-controlled environment and in a 12-h light-dark cycle. Rats were fed a purified M-bM-^@M-^XhumanizedM-bM-^@M-^Y Western diet which contained in the control situation (per kg): 200 g acid casein, 326 g corn starch, 174 g glucose, 160 g palm oil, 40 g corn oil, 50 g cellulose and 5.16 g CaHPO4.2H2O (corresponding to 30 mmol calcium/kg diet; Sigma-Aldrich, St Louis, MO). Vitamins and minerals (other than calcium) were added to all diets according to the recommendations of the American Institute of Nutrition 1993.17 The experimental diet contained more calcium (120 mmol calcium/kg diet) at the expense of glucose. All samples were individually labelled and hybridized (Cy5). Equal amounts of Cy3 cRNA of all animals were pooled to serve as standard reference pool.

Project description:Background; MUC2 mucin produced by intestinal goblet cells is the major component of the intestinal mucus barrier. MUC2 homo-oligomerizes intracellularly into large secreted polymers which give mucus its viscous properties. The inflammatory bowel disease (IBD) ulcerative colitis is characterized by depleted goblet cells and a reduced mucus layer, whereas goblet cells and the mucus layer are increased in the other major inflammatory bowel disease, Crohnâs disease. Methods and Findings; By murine N-ethyl-N-nitrosourea-mutagenesis we identified two distinct non-complementing missense mutations in Muc2 exons encoding N- and C-terminal homo-oligomerization domains causing an ulcerative colitis-like phenotype. Both strains developed mild spontaneous distal intestinal inflammation, chronic diarrhea, rectal bleeding and prolapse, increased susceptibility to acute and chronic colitis induced by a luminal toxin, aberrant Muc2 biosynthesis, smaller goblet cell thecae (less stored mucin) and a diminished mucus barrier. Enhanced local production of IL-1beta, TNF-alpha and IFN-gamma was seen in the distal colon. The number of leukocytes within mesenteric lymph nodes was increased five-fold and leukocytes cultured in vitro produced both Th1 and Th2 cytokines (IFN-gamma, TNF-alpha and IL-13). Intestinal permeability was increased and the luminal bacterial flora were more heavily coated with immunoglobulin as occurs in IBD. This pathology was accompanied by accumulation of the Muc2 precursor and ultrastructural and biochemical evidence of endoplasmic reticulum (ER) stress in goblet cells, activation of the unfolded protein response, and altered intestinal expression of genes involved in ER stress, inflammation, apoptosis and wound repair. Expression of mutated Muc2 oligomerization domains in vitro demonstrated that aberrant Muc2 oligomerization underlies the ER stress. These models show that mutations in Muc2 oligomerization domains can lead to aberrant assembly of the Muc2 complex leading to ER stress, a depleted mucus barrier and intestinal inflammation. In ulcerative colitis we demonstrate similar accumulation of non-glycosylated MUC2 precursor in goblet cells together with ultrastructural and biochemical evidence of ER stress even in non-inflamed intestinal tissue. Conclusions; The observations that mucin misfolding and ER stress lead directly to intestinal inflammation and that ER stress and goblet cell pathology occur in ulcerative colitis suggest that ER stress-related mucin depletion could be a fundamental component of the pathogenesis of colitis. Experiment Overall Design: 3 individual mice from the Eeyore, Winnie or Wild-type strains were compared as groups. An Affymetrix ID was compared between groups if the ID was Present within two of the three mice within each grouping. IDs were compared by calculating the log2 of Group One average signal divided by Group 2 average signal.

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Homo sapiens

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