Oral antibiotics as a novel therapy for arthritis - Evidence for a beneficial effect of intestinal Escherichia coli

Objective. The intestinal flora is thought to play an important role in reg ulation of immune responses. We investigated the effects of changing the in testinal flora on the course of adjuvant-induced arthritis (AIA) and on exp erimental autoimmune encephalomyelitis (EAE) by the use of oral antibiotics , Methods. Oral treatment with either vancomycin or vancomycin, tobramycin, a nd colistin was started after AIA and EAE induction, Clinical symptoms of A IA and EAE were monitored, and microbial analysis of ileal samples was perf ormed. Results. Oral vancomycin treatment after disease induction significantly de creased clinical symptoms of AIA, Simultaneously, increased concentrations of Escherichia coli were detected in the distal ileum of vancomycin-treated rats. Ileal concentrations of E coli were inversely related to disease sco res in rats with AIA, Coadministration of colistin/tobramycin to prevent th e increase in E coli abrogated the beneficial effect of vancomycin on AIA. Vancomycin treatment also reduced the clinical symptoms of EAE. Conclusion. We propose oral vancomycin as a novel therapeutic strategy in a utoimmune diseases.