Objective:

To examine the mechanisms underlying immunological heterogeneity in rheumatoid arthritis (RA) and discuss their implications for patient stratification and treatment response.

Approach:

• Mechanisms of Heterogeneity: The review explores genetic susceptibility, epigenetic regulation, autoantibody diversification, synovial pathotypes, and gut-joint axis-related immune-metabolic interactions.
• Clinical Implications: It discusses how multi-omics, synovial molecular pathology, and biopsy-driven trials can inform early stratification and predict treatment non-response based on current evidence.
• Emerging Strategies: Evaluates investigational strategies such as pharmacomicrobiomics, local drug delivery, nanomedicine, and cell-based therapies.

Key Findings:

• RA is characterized by significant inter-patient heterogeneity in disease course and treatment response.
• Genetic factors, particularly HLA and non-HLA loci, influence disease risk and immune phenotype diversity.
• Current evidence does not support a simple one-marker-one-drug model for treatment response prediction.

Interpretation:

A critical understanding of RA heterogeneity may enhance patient stratification and therapeutic selection.

Limitations:

• The causal role of gut-joint axis and microbiome in RA remains incompletely defined.
• Current therapeutic strategies require further validation based on ongoing research.

Conclusion:

A more integrated approach to understanding RA immunological diversity is necessary for improving treatment outcomes.