ICIs induce both arthritis and oral disorders through intersecting immune pathways; these conditions exhibit bidirectional relationships, as recognized by the correlations between RA and periodontal disease (PD), where common cytokines (e.g., IL-6, IL-1, TNF-α) and citrullination mediated by Porphyromonas gingivalis facilitate mutual aggravation. The gene discussed is IL6; the disease is arthritic joint disease.