The effect of phototherapy on systemic inflammatory process in patients with plaque psoriasis.

Psoriasis is a common, chronic immune-mediated inflammatory disease. The inflammatory process in psoriasis has systemic effects and may influence the development of psoriatic comorbidities. The systemic action of phototherapy in patients with psoriasis has been so far poorly elucidated. We aimed to investigate the expression of genes encoding selected psoriasis-related cytokines in peripheral blood mononuclear cells (PBMCs) isolated from patients with psoriasis before and after treatment with phototherapy. 17 patients with mild to moderate plaque psoriasis were treated with narrow band-UVB (NB-UVB), 8 patients with moderate to severe plaque psoriasis with bath-psoralen-ultraviolet A therapy (PUVA). PBMCs were isolated by Ficoll gradient density centrifugation. Expression of genes encoding TNF-α, IL-17A, IL-6, IL-1 β, INF-γ, and IL-10 in PBMCs of patients with psoriasis before and after phototherapy was analyzed with quantitative RT-PCR. Treatment with NB-UVB therapy led to a significant decrease in IL-17A, TNF-α, and IL-6 mRNA levels in PBMCs (p=0.003; p=0.042; p=0.019, respectively). Following treatment with bath-PUVA therapy, we observed a significant decrease in TNF-α and IL-6 mRNA levels in PBMCs (p=0.031, p=0.035, respectively). Treatment with phototherapy in patients with psoriasis may affect systemic inflammation by downregulation of the expression of genes encoding proinflammatory cytokines in PBMCs, implicated in the development of psoriasis and psoriatic comorbidities.