Narrow-band UVB decreases epidermal thickness, mast cell density and downregulates IL-8 expression in psoriatic lesions histological and immunohistochemical study

ABSTRACT

The increased epidermal thickness and number of early activated cutaneous mast cells is a typical feature of psoriatic inflammation. Over expression of IL-8 and its receptor CXCR2 is typically observed in psoriasis lesions and is thought to contribute to keratinocyte dysfunction and to influx of T cells, neutrophils and mast cells. This study was conducted to evaluate epidermal thickness, mast cell density and IL-8 expression in psoriatic lesions before and after narrow-band ultraviolet B [NB-UVB] therapy using histological and immunohistochemical techniques. Twenty five psoriatic patients referred from Dermatology Outpatient Clinics for NB-UVB phototherapy were enrolled in this study. Patients received irradiation with NB-UVB [312 nm, Philips TL01] on the whole body. Four groups were included in this study; control group [1] normal skin from 5 healthy volunteers], control group [2] non-lesional control group; normal skin from psoriatic patients,Pre-NB-UVB group twenty five psoriatic patients and Post- NB-UVB group psoriatic patients after NB-UVB treatment. Skin biopsies were taken, fixed, processed and stained to assess general skin structure and epidermal thickness, mast cell density and IL-8 expression by using histological and immunohistochemical procedures. After NB-UVB therapy; there was significant improvement in PASI score and significant decrease in epidermal thickness, mast cell density and optical density of IL-8. NB-UVB therapies targeting epidermal thickness, mast cells or IL-8 should be considered in the treatment of psoriasis