IL6 and major depressive disorder: Anti-IL-6 drugs target interleukin-6 (IL-6), a proinflammatory cytokine involved in the pathological processes that contribute to the symptoms of RA while playing a crucial role in regulating immune responses and inflammation.21 IL-6 affects lymphocyte differentiation and is the main contributor to the response in acute-phase of RA and systemic disease symptoms such as pain, fatigue, depression, anaemia, and cardiovascular disease.21, 22 Overall, synovial fluid of affected joints in patients with RA present elevated serum levels of both IL-6 and IL-6 receptors (IL-6R).