Significant upregulation of antimicrobial peptides and proteins in lichen sclerosus

Background Lichen sclerosus (LS) is a chronic inflammatory T cell-driven sclerotic skin condition in which skin barrier disruption frequently occurs. Inflamed and injured epithelia are a particularly rich source of antimicrobial peptides and proteins (AMPs). Objectives We aimed to investigate for the first time the expression pattern of AMPs in lesions of LS as compared with healthy skin. Methods Twenty-four women with LS as well as 10 healthy women were included in the study. In order to assess the expression of human β-defensin (hBD)-1, hBD-2, hBD-3, psoriasin (S100A7), the cathelicidin LL-37 and RNase 7, real-time reverse transcriptase–polymerase chain reaction and immunohistochemistry were performed on skin specimens obtained from lesional and healthy skin of the genital region, respectively. Results Median hBD-2 mRNA levels observed in LS were significantly higher than in controls (0·15 vs. 0·008; P = 0·0037). Moreover, psoriasin (98·2 vs. 28·1; P = 0·0052) mRNA expression was significantly higher in LS lesions as compared with controls. Significant differences in mRNA expression of hBD-2 and psoriasin were also confirmed by immunohistochemistry. For hBD-1, hBD-3, LL-37 and RNase 7, levels did not differ significantly or were significant only at the gene level but not protein level. Conclusions We have demonstrated that hBD-2 and psoriasin expression levels in lesional skin of patients with LS are significantly increased when compared with healthy controls. Whether this observation simply reflects an innate defence response caused by an increased risk of local infection, or whether our data indicate a pathogenetic role of AMPs in LS, will be addressed in future studies.