Cutaneous lupus erythematosus - from pathogenesis to targeted therapy.

Cutaneous lupus erythematosus (CLE) is a complex inflammatory skin disease that presents either in isolation or as a frequent manifestation of systemic lupus erythematosus (SLE). CLE subtypes show clinical heterogeneity and varying associations with SLE. Histologically, CLE is characterized by interface dermatitis, a reaction pattern that involves immune-cell infiltration of the dermo-epidermal junction. In-depth characterization of both non-lesional and lesional lupus skin has reshaped our understanding of pathogenesis. Non-lesional and lesional lupus skin exhibits early and chronic upregulation of type I interferons, which drive photosensitivity, myeloid-cell recruitment and amplification of cytokine responses in both immune and non-immune cells. This detailed understanding of CLE biology has enabled the development of targeted therapies. Ongoing research to identify key pathogenic mechanisms will create opportunities for prevention of CLE and CLE-to-SLE transition.