Decrease in enkephalin levels in psoriatic lesions after calcipotriol and mometasone furoate treatment

Background: Enkephalins are opioid peptides that can modulate immune respon ses and inflammatory processes. Furthermore, they inhibit keratinocyte prol iferation/differentiation in vitro. Previously, we have shown that enkephal ins are present in increased amounts in lesional psoriasis. Objective: To d etermine the effect of topical treatment with the vitamin D analogue calcip otriol and the corticosteroid mometasone furoate on the level of methionine -enkephalin (enk) in psoriatic lesions. Methods: Twelve psoriatic patients were treated with calcipotriol and mometasone furoate for 14 days without o r with hydrocolloid occlusion. Keratome biopsies were obtained from treated and untreated skin, and the extracted enk was quantified by radioimmunoass ay. Furthermore, punch biopsies were obtained for immunohistochemical analy sis. Results: Clinically, both calcipotriol and mometasone furoate improved psoriasis to the same degree, the effects being more pronounced after occl usion, Histologically, treatment with mometasone furoate without occlusion decreased both the epidermal thickness/parakeratosis and the number of derm al immunocompetent cells (CD3- and CD68-positive cells). In contrast, treat ment with calcipotriol without ocelusion reduced the epidermal thickness an d the degree of parakeratosis but decreased the number of CD3- and CD68-pos itive cells only slightly. The mean enk level was decreased by 26 and 86% b y calcipotriol without and with occlusion and by 16 and 63% by mometasone f uroate without and with occlusion, respectively. The decreases in the enk l evels corresponded to the degree of clinical improvement but not to the his tological changes. Conclusion: The increased levels of enk in psoriatic les ions are reduced in parallel with the clinical improvement induced by a top ical vitamin D analogue and a corticosteroid. Because enkephalins can modul ate epidermal differentiation and inflammatory processes, the findings indi cate that enkephalins may play a role in the pathogenesis of psoriasis.