Synovial macrophages of rheumatoid arthritic mice protectively responded by altered M1/M2 differentiation after antibody blocking of TNFR1 and IL-1R.

ABSTRACT

Rheumatoid arthritis (RA) primarily affecting the synovial tissue, has emerged as a major concern leading to the pressing need to develop effective treatment strategies. In the affected synovial tissue, resident macrophages play a pivotal role in the pathogenesis of RA. TNF-α and IL-1ß released from pro-inflammatory M1 synovial macrophages are the master regulators of chronic joint inflammation. In this study collagen-induced rheumatoid arthritis model was developed in mice and post isolation, macrophages were subjected to administration with neutralizing antibodies IL1R and TNFR1 either alone or in combination. Flow cytometric analysis followed by Western blots, ROS, and IL-1ß, TNF-α release assays were performed. Outcomes suggested that post-dual blockade of IL1R and TNFR1 arthritic synovial macrophages showed a shifting of the M1 towards the anti-inflammatory M2 phenotype. Moreover, the switch towards the M2 phenotype might be responsible for decreased levels of IL-1ß,TNF-α, and ROS and simultaneous elevation in the activity of antioxidant enzymes like SOD, CAT, and GPX content in the isolated macrophages. Simultaneous blocking of both IL1R and TNFR1 also showed a sharp reduction in the expression of NF-κB and SAPK-JNK. The elevated arginase and GRX activity further confirmed the polarization towards M2. Moreover, bioinformatics analysis was performed,and it was found that blocking TNFR1 with an antibody could hamper the binding of TNF to TNFR1 in the TNF-TNFR1 pathway. Thus, it may be inferred that dual blockade of IL1R and TNFR1 and a suitable antibody blocking of TNFR1 might be alternative therapeutic approaches for the regulation of RA-induced inflammation in the future.