Enhanced Expression of Kallikrein-related Peptidase 7 in Lichen Planus, Lichen Sclerosis, Porokeratosis and Psoriasis Vulgaris

Abstract

AIM: Kallikrein-related peptidase KLK7 is implicated in desquamation and homeostasis of epidermis. In this study, we aim to determine KLK7 protein expression in four different skin diseases with abnormal keratinization including lichen planus, lichen sclerosis, porokeratosis and psoriasis vulgaris. We also investigate whether skin diseases –related inflammatory cytokines and transcription factor ZNF750 regulates KLK7 gene expression in normal human epidermal keratinocytes (NHEK), and whether ZNF750 protein levels in psoriasis are correlated with KLK7 protein levels.

MATERIALS AND METHODS: Human skin biopsies were obtained from normal subjects and patients with lichen planus, porokeratosis, lichen sclerosis and psoriasis vulgaris. Immunohistochemistry staining, NHEK cell culture, Ca2Cl-induced differentiation, small siRNA interfering technology, real-time PCR and western-blot assays were performed in this study.

RESULTS: KLK7 protein levels are significantly enhanced in skin lesions of lichen planus, porokeratosis, lichen sclerosis and psoriasis vulgaris as compared to normal skin epidermis. Addition of a single cytokine of TNFα, IFNγ, IL1α, IL1β, IL17A don’t affect KLK7 protein expression, but a combination of these cytokines reduces both KLK7 mRNA and protein levels in differentiated NHEK. KLK7 is significantly reduced in ZNF750 silenced differentiated NHEK cells. ZNF750 protein expression levels in psoriasis vulgaris lesions are not correlated with enhanced KLK7 expression levels.

CONCLUSION: Enhanced protein expression of KLK7 is a common characteristics for both hyperkeratosis and parakeratosis disorders. The enhanced KLK7 expression is not associated with increased inflammatory cytokines and ZNF750.