TNF and rheumatoid arthritis: Disease-modifying anti-rheumatic drugs (DMARDs) are currently the first line treatment for RA patients and can have a broad immunosuppressive activity (conventional DMARDs, such as methotrexate and leflunomide) or specific by targeting pro-inflammatory cytokines, such as TNF-α or IL-6 (biological DMARDs, e.g. adalimumab and sarilumab) [2,99].