Bacterial extract (OM-89) specific and non specific immunomodulation in rheumatoid arthritis patients

Abstract

The Escherichia Coli bacterial extract (OM-89) is used in the treatment of rheumatoid arthritis (RA). We evaluated the immunological changes induced by oral administration of OM-89 in 12 RA patients (polyclonal T cell reactivity to PHA, T cell precursor frequencies specific for OM-89 and Tetanus toxoid (TT), a control antigen and the release of Th1 (IFN-γ, TNF-α), Th2 (IL-4) and T regulatory 1 cell (Tr1) (IL-10) cytokines in the supernatants of PBMC cultures. Stimulation index in response to PHA decreased at month 3 as well as T cell precursor frequencies specific for TT with similar trends for OM-89-specific T cell precursor frequencies. OM-89 induced a strong production of IL-10, a significant decrease in IL-4 production while TNF-α and IFN-γ production tended to decrease during the study.

Our results suggest that OM-89 has immunomodulatory properties by inducing changes in PBMC cytokines release suggestive of an induced Tr1 response to OM-89.

• Oral tolerance
• heat shock protein
• rheumatoid arthritis
• T regulatory cells, Interleukin-10

Acknowledgements

The authors thank Giancesare Gamba (PhD) for his statistical assistance, Patricia Caillon (OM PHARMA) for her contribution, Agnès Lienard (Établissement Français du Sang, Besançon, France) for flow cytometry analysis and Patricia Mercier (Établissement Français du Sang, Besançon, France) for cytokine cellular source analysis. This work was supported by a grant from OM PHARMA, Meyrin/Geneva, Switzerland.