INVESTIGADORES
PORPORATTO Carina
congresos y reuniones científicas
Título:
?Induced signals by the polysaccharide chitosan in the intestinal epithelium: a non inflammatory stimulus?.
Autor/es:
CANALI, MAGDALENA M; PORPORATTO CARINA; CORREA SILVIA G
Lugar:
Brasil,
Reunión:
Congreso; XIII International Congress of Immunology.; 2007
Institución organizadora:
IUIS.
Resumen:
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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.