M2 Macrophage and Extracellular Matrix Genes Are Enriched in High-Activity Lichen Planopilaris

The study investigates the pathophysiology of lichen planopilaris (LPP) by analyzing RNA expression in scalp biopsies before and after 6 months of treatment with oral hydroxychloroquine (HCQ), narrow band ultraviolet B (NB-UVB), or low level laser light therapy (LLLLT). Significant increases in <i>PTGER4</i> and <i>DOCK2</i> were observed post-treatment across all patients. Specific gene changes were noted in the HCQ and NB-UVB treatment arms, but not in the LLLLT arm. Higher baseline expressions of genes related to extracellular matrix organization and M2 macrophage polarization were found in patients with higher Lichen Planopilaris Activity Index scores, suggesting these factors may contribute to LPP's immunopathogenesis and follicular scarring. The study highlights potential RNA biomarkers for LPP activity.