Minocycline attenuates piroxicam-induced colonic damage in IL-10-/- KO mice.

N Garrido-Mesa1, F Algieri1, P Zorrilla1, A Rodríguez-Nogales1, J Mañe2, A Zarzuelo1, M Comalada3, ME Rodriguez-Cabezas1, J Galvez1. 1CIBER-EHD University of Granada, Department of Pharmacology, Spain, 2Germans Trias i Pujol,Barcelona, Health Sciences Research Institute, Spain, 3Institute of Biomedical Research, Barcelona, Macrophage Biology Group, Spain

Introduction: Nonsteroidal anti-inflammatory drugs (NSAIDs), including conventional and selective cyclooxygenase-2 (COX-2) inhibitors, are among the most widely used medications for the treatment of inflammatory conditions. However, there is strong evidence of a possible association between the use of these drugs and the relapse of inflammatory bowel diseases (IBD), intestinal conditions that are commonly associated with extra-intestinal manifestations, many of them related to an inflammatory status, which may require the administration of NSAIDs. Minocycline is an antibiotic with immunomodulatory properties that has been report to exert intestinal anti-inflammatory effects in experimental models of colitis in mice and rats (1,2). The aim of the present study is to evaluate the effects of this antibiotic in preventing the deleterious effects that piroxicam may exert in a spontaneous experimental model of mouse colitis (IL-10-/- KO mice).

Material and Methods: Five-week-old mice IL-10-/- KO (n=24) and wild type (C57Bl/6) (n=8) mice (Jackson Laboratories, USA) were used. Colitis was induced by orally administration of three consecutive doses of piroxicam (37.5 mg/kg) to IL-10-/- KO mice (n=16). Afterwards, one group of colitic mice (n=8) received for seven days a daily dose of minocycline (30 mg/kg; p.o.), whereas another group (n=8) received the corresponding vehicle. Colonic damage was evaluated macroscopically (weight/length ratio) and biochemically by determining the expression of different inflammatory markers including TNFα IL-1β, IL-12, IL-17, ICAM-1, MCP-1, MIP-1, MMP-9 and iNOS by qPCR. Statistical analyses was carried out with GraphPad Prism 5 with statistical significance set at p<0.05 using a one-way analysis of variance (ANOVA) and post hoc least significance tests.

Results: The administration of minocycline resulted in an intestinal anti-inflammatory effects evidenced macroscopically by a 30% reduction of the weight/length ratio of the colon (Table 1). Biochemically, it was observed a three-fold decrease in IL-1β, a pro-inflammatory cytokine derived from macrophages very important for the initial phase of the inflammatory response, as well as a five-fold reduction in IL-17, key player in the chronic inflammation. Minocycline treatment also reduced leukocyte chemotaxis since there was at least a two-fold decrease in the adhesion molecule ICAM-1 and the chemokines MCP-1 and MIP-1. The anti-inflammatory effects of minocycline also included a three-fold reduction of the metalloproteinase MMP-9 and a two-fold decrease of iNOS, another key player in the intestinal inflammation due the deleterious effects of NO overproduction (Table 1).

Table 1. Effects of minocycline (MNC) in piroxicam-induced colitis in IL-10-/- KO mice

Data are expressed as mean ± SEM. *p<0.05 vs. IL-10-/- KO + Piroxicam group.

Conclusion: In conclusion, the immunomodulatory effects of minocycline exerted an intestinal anti-inflammatory activity in the piroxicam-induced colitis in IL-10-/- KO mice, acting at different levels of the inflammatory response.

References: (1) Pharmacol Res. 2011;63:308-19. (2) Biochem Pharmacol. 2011;82:1891-900.