S100A8/A9, a potent biomarker and clinical candidate for the treatment of uveitis

Uveitis, the pathological condition of inflammation of the uvea, commonly causes severe visual impairment and blindness. Possible causes of uveitis include infection, injury, or an autoimmune or inflammatory disease. However, the pathogenesis of uveitis is not fully understood. Glucocorticoids are widely used for the treatment of uveitis, but long-term steroid use carries a risk of potential complications. Early diagnosis and proper treatment are important to prevent the complications of uveitis. Thus far, researchers have not identified an effective biological marker for auxiliary diagnosis or an appropriate method for monitoring the inflammatory activity of uveitis. S100A8/A9, also known as calprotectin, belongs to the Ca 2+ -binding S100 protein family; is mainly expressed in myeloid leukocytes; and plays a prominent role in a variety of pathological process, such as inflammation, infection and autoimmune diseases. Extracellular S100A8/A9 released from granulocytes and monocytes has recently gained a great deal of attention as a critical alarmin for the modulation of the inflammatory response. This review will summarize recent insights into the biological function of S100A8/A9 in uveitis and provide an outlook on diagnostic, inflammation monitoring and therapeutic applications targeting S100A8/A9 for the treatment of uveitis.