Calcipotriol/Betamethasone Dipropionate Foam Inhibits Th17 Cytokine Secretion and Improves Epidermal Barrier Markers in a Human Th17 Skin Inflammation Model

Introduction: T-helper 17 (Th17) cytokines play a key role in the pathophysiology of psoriasis by driving inflammatory responses that lead to epidermal alterations. Markers of epidermal differentiation, including the proteins loricrin (LOR), filaggrin (FLG) and involucrin (IVL), are dysregulated in psoriatic skin. The fixed-dose combination of calcipotriol/betamethasone dipropionate (Cal/BD) foam and clobetasol propionate (CP) are widely used, effective topical treatments for psoriasis. In this study, we investigated the effects of Cal/BD foam and CP cream on Th17 cytokine secretion and epidermal differentiation using a human Th17 skin inflammation model (InflammaSkin (R)). Methods: The fixed-dose combination Cal/BD foam and the CP cream were applied once and twice daily, respectively, onto the air-exposed epidermal surface of InflammaSkin cultures for 7 days. Th17 cytokine levels were measured in culture supernatants, and gene expression analysis and immunohistochemical staining for LOR, FLG and IVL were performed on the skin samples. Results: Topical treatment with Cal/BD foam almost completely inhibited Th17 cytokine secretion and upregulated LOR and IVL expression, but not FLG expression, at the mRNA and protein levels. Topical treatment with CP cream significantly reduced Th17 cytokine levels, but to a lesser extent than Cal/BD foam, and did not improve expression of any of the epidermal differentiation markers. Conclusion: Compared with CP treatment, the fixed-dose combination Cal/BD foam showed a greater suppression of Th17 cytokine secretion and improved epidermal differentiation, resulting in an overall higher degree of improvement of the skin. These results support our understanding of the mechanisms behind the clinical efficacy observed for Cal/BD foam and of its use for long-term proactive treatment of psoriasis vulgaris.