Interleukin-17 and lupus: enough to be a target? For which patients?

The involvement of the interleukin (IL)-17 axis in many inflammatory and autoimmune diseases is now well established, and this has led to the development of successful targeted therapies. Its role in systemic lupus erythematosus (SLE) is less described, since SLE is characterized by the impairment of many other immune actors. However, results from animal models and patients strongly suggest that IL-17 and its producing cells are involved in SLE pathogenesis. Circulating levels of IL-17 are increased in lupus, and tissue staining shows the presence of IL-17-producing cells in organ lesions. Through different mechanisms, the IL-17 axis promotes autoantibody production, immune complex deposition, complement activation and then tissue damage. There are also many interactions with other immune and non-immune actors, which account for the broad spectrum of clinical manifestations and disease heterogeneity. SLE treatment faces challenges with many disappointing trials and persistent unmet needs. The identification of subsets of SLE patients with an IL-17-driven disease now constitutes the key priority before starting trials. More preclinical studies are needed to improve the selection of the right patients able to respond and tolerate the many inhibitors that are already available.