Induced signals by the polysccharide chitosan in the intestinal epithelium: a non inflammatory stimulus

CANALI MM, PORPORATTO C, RIERA CM, CORREA SG

Río de Janeiro

Congreso; XIII International Congress of Immunology and VIII Latin American Congress of Immunology (ALAI).; 2007

IUIS y ALAI

Intestinal epithelial cells (IECs) are components of the mucosal immune system that limit the host’s exposure to luminal antigens. Chitosan (Ch) is a polycationic polysaccharide that has immunostimulatory properties including TGF-b stimulation in the mucosal inductive sites and tolerogenic effects against certain proteins. In our model, we decided to evaluate if Ch represents an inflammatory stimulus for IECs. Wistar rats were fed with a single dose of diluent, 1, 3, or 5 mg. of Ch and parameters were evaluated in purified IECs 16h after treatments. We determined the production of nitric oxide (NO) and the arginase activity upon feeding. After 6h, cultures of intestinal segments of Ch-fed rats showed no significant changes in NO levels but a significant increment in arginase activity compared to the control group. Surface ICAM-1 and intracellular pSTAT-3 increase during inflammatory processes. In our model, we have not observed changes in the expression of these molecules after Ch treatments. The relationship smad7/smad3 is augmented in patients with inflammatory intestinal bowel disease. In our model the balance of those two signaling factors decreased with the Ch treatments. The polysaccharide significantly increased the levels of the chemokines CCL-2 and CCL-20 but not IL-8 and also increased the number of OX62+CD11b/c+ dendritic cells in the submucosa. We conclude that Ch represents rather an anti-inflammatory than an inflammatory stimulus for IECs and interestingly is also able to induce certain cytokines and chemokines expression known to be involved in the recruitment of immature dendritic cells into the submucosa.