ANNEXIN-1 IS OVEREXPRESSED AND SPECIFICALLY SECRETED DURING EXPERIMENTALLY-INDUCED COLITIS IN RATS

Annexin 1 is a protein induced by glucocorticoids endowed with extrace llular anti-inflammatory properties. In this study, the local expressi on and secretion of annexins 1-6, in rat proximal colon, were studied at different times after intracolonic administration of 30 mg trinitro benzenesulfonic acid in 50% ethanol. Secretion was identified by incub ating colonic tissues in a culture medium. The expression of annexins was detected by immunoblotting in tissue homogenates and incubation me dia. Inflammatory stages were evaluated by measuring myeloperoxidase a ctivity. Annexin 1 expression in colons increased after trinitrobenzen esulfonic acid treatment and was maximal between days 1 to 9, during t he cellular stage of the inflammation that corresponded to maximal mye loperoxidase activity. From 12 h to 9 days after trinitrobenzenesulfon ic acid/ethanol treatment, annexin 1 was specifically secreted. Annexi n 3 was also overexpressed during the cellular stage, but the expressi on of annexins 2, 4, 5, and 6 was unchanged; none of these annexins we re secreted. Annexin 1 was shown to be physiologically secreted becaus e its release was specific, abundant, and not correlated with cellular lysis. Annexin 1 may be considered as a putative candidate in the con trol of the gut inflammatory processes.