Overexpressed perforin contributes to the melanocyte destruction via epigenetic regulation in patients with vitiligo

Perforin (PRF), a pivotal cytotoxic effector molecule of activated CD8+ T cells, has a crucial role in the pathogenesis of vitiligo. However, the mechanisms leading to the abnormal perforin expression remain poorly understood in the CD8+ T cells of vitiligo patients. To investigate the contributions of DNA methylation to the abnormal expression of perforin in CD8+ T cells of vitiligo patients. Skin samples and CD8+ T cells from peripheral blood were collected to detect the expression levels of perforin in vitiligo patients. The methylation status of the perforin promoter was investigated by bisulfite sequencing. The apoptosis of melanocytes co-cultured with CD8+ T cells was evaluated to determinate the cytotoxic role of perforin. Increased CD8+ and perforin+ cells were found in lesion of vitiligo patients. The expression levels of perforin were elevated in the CD8+ T cells from peripheral blood of vitiligo patients and their culture supernatants. The perforin promoter was hypomethylated in vitiligo CD8+ T cells. Treatment of normal CD8+ T cells with the DNA methylation inhibitor 5-Azacytidine (5-Azac) reduced the perforin methylation level and caused perforin overexpression. The methylation levels of perforin were inversely correlated with its mRNA expression in CD8+ T cells. The apoptosis rates of the melanocytes co-cultured with vitiligo- and 5-Azac-treated-normal CD8+ T cells were significantly increased compared with normal-untreated CD8+ T cells. And the apoptosis rates of melanocytes co-cultured with si-PRF-treated-vitiligo CD8+ T cells were significantly decreased compared with vitiligo-untreated CD8+ T cells. Hypomethylation of the perforin promoter contributes to its overexpression in CD8+ T cells from vitiligo patients, which then mediates the melanocyte destruction in vitiligo.