Interleukin‐6 blockade in ocular inflammatory diseases

Summary Interleukin‐6 ( IL ‐6) is a key cytokine featuring redundancy and pleiotropic activity. It plays a central role in host defence against environmental stress such as infection and injury. Dysregulated, persistent interleukin ( IL) ‐6 production has been implicated in the development of various autoimmune, chronic inflammatory diseases and even cancers. Significant elevation of IL ‐6 has been found in ocular fluids derived from refractory/chronic uveitis patients. In experimental autoimmune uveitis models with IL ‐6 knock‐out mice, IL ‐6 has shown to be essential for inducing inflammation. IL ‐6 blockade can suppress acute T helper type 17 ( T h17) responses via its differentiation and, importantly, can ameliorate chronic inflammation. Tocilizumab, a recombinant humanized anti‐ IL ‐6 receptor antibody, has been shown to be effective in several autoimmune diseases, including uveitis. Herein, we discuss the basic biology of IL ‐6 and its role in development of autoimmune conditions, focusing particularly on non‐infectious uveitis. It also provides an overview of efficacy and safety of tocilizumab therapy for ocular inflammatory diseases.