Efficacy of Thalidomide in Discoid Lupus Erythematosus: Insights into the Molecular Mechanisms.

Background: Thalidomide has been used successfully in a variety of chronic refractory inflammatory dermatological conditions with underlying autoimmune or infectious pathogenesis. It was first used for refractory discoid lupus erythematosus (DLE) in 1983 and has steadily grown since then. Method: In this review, we describe the therapeutic benefits of thalidomide for DLE treatment and its biological properties. We explain how new discoveries in DLE pathogenesis are relevant to understand thalidomide's mechanism of action and the need to find an alternative safe drug with similar therapeutic effects. Summary: Thalidomide's efficacy in DLE patients is significant, with 80-90% reaching clinical remission according to different studies. However, thalidomide's use is still limited by serious adverse effects such as teratogenicity, neurotoxicity, and thrombosis. In addition, there is a frequent rate of relapse and many patients require a longterm low dose of thalidomide as maintenance. The achievement of clinical response within weeks is key to avoid irre-versible DLE fibrotic sequelae, making it critical to introduce thalidomide earlier in the DLE treatment algorithm. Recently, microarray and miRNA screenings demonstrated a significant CD4(+) T enrichment and T-helper 1 response predominance with a dysregulation of regulatory T cell (Treg) expression in DLE lesions that induced high levels of proinflammatory, chemotaxis, and apoptotic proteins that induce the chronic inflammation response. Thalidomide's anti-inflammatory, antiangiogenic, and T-cell co-stimulatory effects may be beneficial for DLE since it promotes cytokine inhibition, inhibits macrophage activation, regulates Treg responses, inhibits angiogenesis, modulates T cells, and promotes NK cell-mediated cytotoxicity. (C) 2020 S. Karger AG, Basel