Differential effects of phototherapy, adalimumab and betamethasone–calcipotriol on effector and regulatory T cells in psoriasis

Summary Background Psoriasis is a chronic T‐cell‐mediated skin disease with marked social and economic burdens. Current treatments are unsatisfactory, with unpredictable remission times and incompletely understood modes of action. Recent advances in our understanding of the pathogenesis of psoriasis have identified the imbalance between CD4+ T effector cells, particularly the T helper (Th)17 subset, and regulatory T cells (Tregs) as key to the development of psoriatic lesions, and therefore a novel therapeutic target. Objectives To quantify in patients the effects of three commonly used psoriasis treatment modalities on the Th1, Th2, Th17 and Treg subsets, and to test whether any change correlates with clinical response. Methods Flow cytometry was used to enumerate Th1, Th2, Th17 and Treg subsets in blood and skin of patients with psoriasis before and after receiving any of the following treatments: narrowband ultraviolet B (NB‐UVB), adalimumab and topical betamethasone–calcipotriol combination (Dovobet®) Results All patients responded clinically to the treatments. NB‐UVB significantly increased the numbers of circulating and skin Tregs, while, by contrast, adalimumab reduced Th17 cells in these compartments, and Dovobet had dual effects by both increasing Tregs and reducing Th17 cells. Conclusions The differential effects reported here for the above‐mentioned treatment modalities could be exploited to optimize or design therapeutic strategies to overcome the inflammatory drivers more effectively and restore the Th17–Treg balance in psoriasis. What's already known about this topic? The imbalance between CD4+ T effector cells, particularly the T helper (Th)17 subset, and regulatory T cells (Tregs) is key to the development of psoriatic lesions, and therefore a novel therapeutic target. What does this study add? This study quantifies in patients the effects of three commonly used psoriasis treatment modalities on the Th1, Th2, Th17 and Treg subsets, and tests whether any changes correlate with clinical response. What is the translational message? The results can be used to optimize or design therapeutic strategies to overcome the inflammatory drivers and restore the Th17–Treg balance in psoriasis. Plain language summary available online Respond to this article