Activation and modulation of the MAP kinase pathway in IBD

DOCENA G; FANNING A; ROVEDATTI L; DI SABATINO A; LEAKEY N; KNOWLES C; LEE K; SHANAHAN L; NALLY K; MCLEAN P; MACDONALD T; KRUIDENIER L

SAN DIEGO USA

Congreso; Digestive Disease Week Congress; 2008

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US; mso-fareast-language:EN-US;} @page Section1 {size:21.0cm 842.0pt; margin:72.0pt 89.85pt 72.0pt 89.85pt; mso-header-margin:35.45pt; mso-footer-margin:35.45pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Background: Pro-inflammatory cytokines are key pathophysiologic factors in the inflammatory bowel diseases (IBD), Crohn’s disease (CD) and ulcerative colitis (UC). Their expression is regulated via different intracellular pathways, eg through NFkB and JAK/STAT, but the role of the p38 mitogen-activated protein kinase (MAPK) pathway has remained controversial. Aim: In this work, we have evaluated the activation status of the p38 MAPK pathway in IBD patient biopsies. In addition, we have used a range of novel and selective small molecule p38 inhibitors to assess their potential as novel therapeutics for the treatment of IBD. Methods: Colonic mucosal biopsies were freshly obtained from normal subjects (n=6-18) and patients with CD (n=7-11) or UC (n=7-25) and incubated without further stimulation in the presence or absence of four different experimental p38 MAPK inhibitors in concentrations ranging from 0.01–10uM. After 24h, protein extracts were evaluated for the activation status of p38α MAPK by Western blotting, while levels of a range of cytokines and chemokines were measured by multiplex ELISA. Results: As compared to healthy controls, p38α MAPK phopshorylation levels were significantly elevated in biopsies from IBD patients, with CD and UC being similarly affected. This was accompanied by a markedly increased release of TNF-α (30–500 pg/mL), IL-6 (1–30 ng/mL), IL-1β (20–1200 pg/mL) and monocyte chemoattractant protein (MCP)-1 (300–2000 pg/mL) from CD and UC biopsies. Treatment with the different inhibitory drugs down modulated the phosphorylation of p38α MAPK, and significantly reduced cytokine secretion in a dose-dependent manner. Conclusions: These results confirm the importance of the p38 MAPK pathway in pro-inflammatory cytokine production in IBD patient biopsies, and identify novel p38 MAPK inhibitors which may form the basis for future therapeutic strategies in the treatment of patients with IBD.