POS0384 A NOVEL MECHANISM LINKING MUCOSAL BACTERIA WITH AUTOANTIBODY RESPONSES IN RA: ACETYLATED BACTERIAL LYSATE AS A MODEL ANTIGEN

Background: Rheumatoid arthritis (RA) is characterized by autoantibodies against post-translationally modified proteins (AMPA) such as citrullinated, carbamylated and acetylated proteins. Importantly, these antibodies are highly multireactive, they often recognize more than one of post-translational modifications. Despite extensive research, the antigens inducing breach tolerance remain unknown, although microbial suspected. Various bacteria known to be capable acetylation, therefore, it intriguing know what mechanisms can underlie towards development anti-acetylated protein (AAPA). Objectives: To investigate whether bacterial origin (1) recognized human derived AMPA expressing B cells; (2) induce when used immunize mice. Methods: Acetylated E. coli were acquired with two separate methods (Figure 1A): culturing in a condition promoting auto-acetylation (intrinsically proteins, IABP), or directly acetylating lysate-derived via chemical reaction (extrinsically BP, EABP). ovalbumin (AcOVA) served positive control for AAPA induction mice, non-acetylated BP (NABP) phosphate buffer saline (PBS) negative control. Mice immunized resulting antibody response was studied ELISA. Furthermore, EABP/IABP/NABP investigated recognition human-derived ELISA AAPA-expressing cells spleen tyrosine kinase (Syk) phosphorylation assay; fibrinogen native Results: Repetitive immunization mice EABP resulted an recognizing acetylated, citrullinated titers exceeded AcOVA substantially higher NABP-immunized 1B). Human-derived monoclonal IABP (not shown). cell activation (measured Syk phosphorylation) assay indicated that (to lesser extent) IABP, but not NABP 1C). Conclusion: potent cross-reactive responses AAPA. This suggests could possibly involved RA. Acknowledgements: We thank Dr. Can Araman Prof. Chunaram Choudhary their advice regarding optimization auto-acetylation. Disclosure Interests: None declared