Corticotropin‐releasing hormone receptor‐1 is increased in mast cells in psoriasis and actinic keratosis, but not markedly in keratinocyte skin carcinomas

Abstract

AbstractCorticotropin‐releasing hormone receptor‐1 (CRH‐R1) is expressed in human mast cells, but its role in skin diseases is unknown. By using a sequential double‐staining technique, the mast cell expression of CRH‐R1 was investigated in biopsies from lesional and non‐lesional skin samples of patients with actinic keratosis (AK), basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and psoriasis. Dermal tryptase+ mast cells expressed CRH‐R1 immunoreactivity in the non‐lesional skin in all patient groups. The CRH‐R1 expression was significantly increased in the lesional skin of AK (p = 0.03) and psoriasis (p = 0.02), non‐significantly in BCC (p = 0.129), but not increased in SCC. To investigate the regulation of CRH‐R1, the LAD2 mast cell line was irradiated with UVB or stimulated with CRH or 1,25‐dihydroxyvitamin D3 [1,25‐(OH)2D3]. Consequently, UVB at 90 mJ/cm2 (p = 0.041) and 120 mJ/cm2 (p = 0.039) decreased CRH‐R1 expression. Instead, CRH at 100 and 1000 nM increased CRH‐R1 immunostaining, but did not affect the proliferative response. The treatment with 10 and 100 nM 1,25‐(OH)2D3 led to a noticeable increase in CRH‐R1 staining. After irradiating with UVB, the concentration of CRH increased in the conditioned medium, but not in sonicated LAD2 mast cells. In conclusion, the lack of sufficient levels of CRH‐R1 in mast cells may be related to diminished antitumoural response in SCC and possibly in BCC.