Keratinocyte VISTA attenuates UV light-induced skin injury by suppressing cutaneous type I interferon (IFN-I) response.

Persistent production of type I interferons (IFN-Is) is a hallmark of cutaneous lupus erythematosus (CLE). Ultraviolet (UV) light stimulates IFN-I response in the skin and exacerbates CLE. Here, we identify V-type immunoglobulin domain-containing suppressor of T cell activation (VISTA) as a negative regulator of both basal and UV-induced IFN-I response in the skin and show that VISTA limits skin photosensitivity in an IFN-I-dependent manner, in part through Stimulator of Interferon Genes (STING). Furthermore, we demonstrate a novel role for VISTA in keratinocytes both at steady state and in response to UV light. Conditional deletion of VISTA in epidermal keratinocytes results in a ~10-fold increase in basal skin IFN-I scores and a heightened UV-induced skin injury score, both of which are dependent on IFN-I signaling. VISTA-targeting monoclonal antibodies suppress the UV-induced IFN-I response in human keratinocytes and in mice expressing human VISTA in vivo, thereby reducing UV-induced skin injury scores. Together, these findings identify VISTA as a keratinocyte-intrinsic checkpoint that restrains STING-associated IFN-I response in the skin and suggest VISTA agonism as a therapeutic strategy to limit photosensitivity in CLE.