Mutant p53^R211* ameliorates inflammatory arthritis in AIA rats via inhibition of TBK1-IRF3 innate immune response

Background: Rheumatoid arthritis (RA) is an autoimmune inflammation disease characterized by imbalance of immune homeostasis. p53 mutants are commonly described as the guardian of cancer cells by conferring them drug-resistance and immune evasion. Importantly, p53 mutations have also been identified in RA patients, and this prompts the investigation of its role in RA pathogenesis.Methods: The cytotoxicity of disease-modifying anti-rheumatic drugs (DMARDs) against p53 (wild-type (WT)/mutant)-transfected RA fibroblast-like synoviocytes (RAFLSs) was evaluated by MTT assay. Adeno-associated virus (AAV) was employed to establish p53 (WT/R211*) adjuvant-induced arthritis (AIA) rat model. The arthritic condition of rats was assessed by various parameters such as micro-CT analysis. Knee joint samples were isolated for total RNA sequencing analysis. The expressions of cytokines and immune-related genes were examined by qPCR, ELISA assay and immunofluorescence. The mechanistic pathway was determined by immunoprecipitation and Western blotting in vitro and in vivo.Results: Among p53 mutants, p53(R213*) exhibited remarkable DMARD-resistance in RAFLSs. However, AAV-induced p53(R211*) overexpression ameliorated inflammatory arthritis in AIA rats without Methotrexate (MTX)-resistance, and our results discovered the immunomodulatory effect of p53(R211*) via suppression of T-cell activation and T helper 17 cell (Th17) infiltration in rat joint, and finally downregulated expressions of pro-inflammatory cytokines. Total RNA sequencing analysis identified the correlation of p53(R211*) with immune-related pathways. Further mechanistic studies revealed that p53(R213*/R211*) instead of wild-type p53 interacted with TANK-binding kinase 1 (TBK1) and suppressed the innate immune TBK1-Interferon regulatory factor 3 (IRF3)-Stimulator of interferon genes (STING) cascade.Conclusions: This study unravels the role of p53(R213*) mutant in RA pathogenesis, and identifies TBK1 as a potential anti-inflammatory target.