Abstract

Though ultraviolet (UV) radiation is a known trigger for cutaneous lupus erythematosus (CLE), UVA-1 phototherapy is an established treatment for sclerosing skin disorders and has been proposed as a therapy for CLE. We sought to investigate the safety and efficacy of low-dose UVA-1 as a treatment for CLE and assess the histopathologic effects of low-dose UVA-1, with novel use of QuPath software to quantify cells stained by immunohistochemistry (IHC) in skin biopsies. Nine patients were enrolled, and five patients completed ten weeks of UVA-1 treatments three times weekly in this open-label clinical trial. Skin biopsies were obtained before and after treatment and stained for H&E. IHC was performed for CD3, CD4, CD8, CD20, CD123, CD163, CD183, and CXCL10 to assess cell populations. Inflammatory cell subsets were counted manually and with QuPath software. Statistical analysis was completed using GraphPad Prism. No adverse events were noted with UVA-1 phototherapy, and indices of disease activity were unchanged before and after treatment. Using QuPath for cell counting, CXCL10 expression in skin biopsies down-trended and reached statistical significance (p=0.042) before and after treatment with UVA-1. Cells stained with H&E and IHC for CD3, CD4, CD8, CD20, CD123, CD163, CD183 showed non-significant downtrends in cell counts. These trends were similar with manual cell counts. This preliminary study shows that low dose UVA-1 phototherapy may be a safe treatment for CLE and can decrease CXCL10-positive cells in CLE. Furthermore, this study demonstrates a novel use of QuPath in quantifying inflammatory cell subsets in dermatologic disorders.