Increased Expression of PD-L1 and PD-L2 in Dermal Fibroblasts From Alopecia Areata Mice

The study investigated the expression of PD-L1 and PD-L2 in dermal fibroblasts from alopecia areata (AA) mice. It was found that AA-affected skin had a significantly higher number of PD-L1 and PD-L2 positive cells compared to non-AA skin. This increase was correlated with the presence of infiltrated T cells, particularly CD8+ T cells. The expression of these molecules was associated with biomarkers for dermal fibroblasts, such as type 1 pro-collagen, CD90, and vimentin. The study concluded that activated T cells in AA-affected skin up-regulated PD-L1 and PD-L2 expression in dermal fibroblasts, suggesting these molecules may not effectively control immune activation in AA lesions.