Multidimensional regulatory mechanisms and translational potential of epigenetic networks in the rheumatoid arthritis disease course.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic synovitis that may progress to irreversible joint destruction and disability, thereby substantially impairing quality of life. RA results from complex interactions among genetic predisposition, environmental exposures, and immune dysregulation; however, current therapies are not curative, and many patients continue to experience pain, morning stiffness, and recurrent inflammation. In recent years, epigenetic mechanisms have emerged as key modulators of RA heterogeneity and disease persistence. Reversible regulatory layers-including non-coding RNAs, RNA modifications, DNA methylation, histone modifications, and microbiota-host interactions-provide a conceptual framework linking environmental cues to cell-type-specific inflammatory programs. This review summarizes recent advances in the epigenetic regulation of RA and outlines six interconnected dimensions. (1) miRNA-mediated post-transcriptional regulation: dysregulated miRNAs reshape inflammatory circuits and promote synovial activation through regulatory hubs. (2) RNA m6A modification: aberrant m6A remodeling alters immune metabolism and inflammatory gene expression, thereby reinforcing pathogenic responses. (3) DNA methylation: genome-wide profiling of synovium reveals differentially methylated loci that may activate disease-relevant pathways. (4) Histone modification and chromatin remodeling: altered activity of histone-modifying enzymes (e.g., HDACs) modulates inflammatory transcriptional programs and may contribute to epigenetic memory. (5) Hypoxia-driven metabolic-epigenetic crosstalk: hypoxia-inducible factors (HIFs) coordinate metabolic adaptation and inflammatory amplification; for example, HIF-1α supports the FLSs under hypoxic conditions. (6) Microbiome-epigenome interactions: gut microbial metabolites (e.g., butyrate) regulate immune homeostasis, partly by promoting follicular regulatory T cell (TFR) differentiation and restraining inflammation. Collectively, these findings indicate that epigenetic networks exert multilevel control over RA pathogenesis and highlight translational opportunities for targeted epigenetic interventions, including RNA methylation modulators, DNA methyltransferase inhibitors, and histone deacetylase-directed strategies.