fumarates and Colitis

The renin-angiotensin system (RAS) plays pathogenic roles in renal and cardiovascular disorders, but whether it is involved in colitis is unclear. Here we show that RenTgMK mice that overexpress active renin from the liver developed more severe colitis than wild-type controls. More than 50% RenTgMK mice died whereas all wild-type mice recovered. RenTgMK mice exhibited more robust mucosal TH17 and TH1/TH17 responses and more profound colonic epithelial cell apoptosis compared to wild-type controls. Treatment with aliskiren (a renin inhibitor), but not hydralazine (a smooth muscle relaxant), ameliorated colitis in RenTgMK mice, although both drugs normalized blood pressure. Chronic infusion of angiotensin II into wild-type mice mimicked the severe colitic phenotype of RenTgMK mice, and treatment with losartan [an angiotensin type 1 receptor blocker (ARB)] ameliorated colitis in wild-type mice, confirming a colitogenic role for the endogenous RAS. In human biopsies, pro-inflammatory cytokines were suppressed in patients with inflammatory bowel disease who were on ARB therapy compared to patients not receiving ARB therapy. These observations demonstrate that activation of the RAS promotes colitis in a blood pressure independent manner. Angiotensin II appears to drive colonic mucosal inflammation by promoting intestinal epithelial cell apoptosis and mucosal TH17 responses in colitis development.

Topics: Amides; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Apoptosis; Colitis; Colon; Epithelial Cells; Fumarates; Humans; Hydralazine; Inflammatory Bowel Diseases; Losartan; Mice; Mice, Transgenic; Receptor, Angiotensin, Type 1; Renin; Renin-Angiotensin System; Th17 Cells

In the present study, we investigated the ameliorative potential of aliskiren in dextran sulfate sodium (DSS) induced colitis in mice. Aliskiren (3 and 10mg/kg, i.p.) was administered for 10 days from the day of DSS administration. The severity of colitis in mice was assessed using body weight loss, colon and spleen weight, hematological parameters, food intake, stool consistency, rectal bleeding and colon shortening. Colonic malondialdehyde (MDA), myeloperoxidase (MPO) and renin mRNA levels were also estimated. Furthermore, TNF-α and IL-6 in plasma and colon were analyzed. The results showed that aliskiren (10mg/kg, i.p.) significantly improved the severity of colitis by, decrease in weight loss, improvement in food intake and stool consistency, decrease in rectal bleeding, decrease in relative colon and spleen weight and improvement in colonic shortening. Aliskiren (10mg/kg, i.p.) improved blood hemoglobin, red blood cells (RBC) and hematocrit. Colonic malondialdehyde (MDA), MPO and histolopathological score were significantly diminished by aliskiren (10mg/kg, i.p.). Furthermore, aliskiren (10mg/kg, i.p.) significantly diminished the elevated levels of TNF-α, IL-6 and renin mRNA in inflammed colon. These results indicate involvement of renin in colitis and inhibition of renin by aliskiren ameliorates colitis.

Topics: Amides; Animals; Anti-Inflammatory Agents; Antioxidants; Body Weight; Colitis; Colon; Cytokines; Dextran Sulfate; Eating; Erythrocytes; Female; Fumarates; Gene Expression Regulation; Hematocrit; Hemoglobins; Malondialdehyde; Mice; Organ Size; Peroxidase; Renin; RNA, Messenger; Spleen