HLA class I-downregulated senescent epidermal basal cells orchestrate skin pathology in cutaneous lupus erythematosus.

Abstract

OBJECTIVE To investigate the role of senescent epidermal basal cells in cutaneous lupus erythematosus (CLE) pathogenesis using skin samples from patients with CLE and a mouse model of systemic lupus erythematosus (SLE). METHODS Cellular senescence profiling utilized datasets from the NCBI Gene Expression Omnibus database and Accelerating Medicines Partnership® (AMP®) Phase 1-Metro. Gene array data from GSE184989 (CLE: n = 68, control: n = 4), single-cell RNA sequencing data from GSE186476 (CLE: n = 7, control: n = 14), and AMP® Phase 1-Metro (SLE: n = 17) were utilized. In vitro experiments further examined the expression of p21WAF1/CIP1, type I interferon (IFN), human leukocyte antigen class I (HLA-I), and epidermal growth factor receptor (EGFR) signalling. Pharmacological clearance of senescent cells was performed using the senolytic drug fisetin in the SLE mouse model. RESULTS p21WAF1/CIP1-high senescent epidermal basal cells in patients with CLE exhibit high type I IFN expression. These cells enhance IFN signalling in surrounding normal epidermal basal cells, leading to increased HLA-I expression. In contrast, senescent epidermal cells upregulate EGFR signalling, which downregulates HLA-I expression, allowing them to evade immune surveillance. This heterogeneity of HLA-I expression promotes CD8-positive T-mediated toxicity against normal epidermal basal cells, resulting in their apoptosis. Pharmacological clearance of senescent epidermal basal cells improved SLE-like skin lesions. CONCLUSION Senescent cells create a microenvironment that directs cytotoxic T-cell-mediated responses against normal epidermis in CLE, contributing to disease pathology. Targeting senescent cells and their signalling pathways may offer novel therapeutic strategies for CLE and SLE skin lesions.