Dichotomal role of inhibition of p38 MAPK with SB 203580 in experimental colitis.

BACKGROUND Crohn's disease is characterised by a chronic relapsing inflammation of the bowel in which proinflammatory cytokines play an important perpetuating role. Mitogen activated protein kinase p38 (p38 MAPK) has been established as a major regulator of the inflammatory response, especially with regard to production of proinflammatory cytokines, but its role in inflammatory bowel disease is unexplored. In this paper we describe the effects of a specific p38 MAPK inhibitor, SB 203580, in trinitrobenzene sulphonic acid (TNBS) induced colitis in mice. RESULTS SB 203580 had a dichotomal effect in TNBS mice. Weight loss of TNBS mice treated with SB 203580 was significantly worse and colon weight on sacrifice was significantly increased in MAPK inhibitor treated TNBS mice (229.2 mg and 289.1 mg, respectively). However, the total number of cells in the caudal lymph node decreased to 188.8 x 10(4) cells in SB 203580 treated TNBS mice compared with 334 x 10(4) cells in vehicle treated mice. CD3/CD28 double stimulated caudal lymph node cells of SB 203580 treated mice showed decreased interferon gamma production but increased tumour necrosis factor alpha production. The concentration of interleukin 12p70 in colon homogenates was significantly decreased in SB 203580 treated mice whereas concentrations of interleukin 12p40, tumour necrosis factor alpha, and interleukin 10 were similar in vehicle and SB 203580 treated TNBS mice. CONCLUSION Our results reveal a dichotomy in p38 MAPK action during experimental colitis.