Singh et al.: 8-Methoxypsoralen Plus Ultraviolet A Therapy Acts via Inhibition of the IL-23/Th17 Axis and Induction of Foxp3+ Regulatory T Cells Involving CTLA4 Signaling in a Psoriasis-Like Skin Disorder

Singh, TP; Schön, MP; Wallbrecht, K; Michaelis, K; Rinner, B; Mayer, G; Schmidbauer, U; Strohmaier, H; Wang, XJ; Wolf, P.
8-Methoxypsoralen Plus Ultraviolet A Therapy Acts via Inhibition of the IL-23/Th17 Axis and Induction of Foxp3+ Regulatory T Cells Involving CTLA4 Signaling in a Psoriasis-Like Skin Disorder.
J Immunol. 2010; PUBMED full text full text MUG-login

Abstract:
To elucidate the molecular action of 8-methoxypsoralen plus UVA (PUVA), a standard dermatological therapy, we used K5.hTGF-beta1 transgenic mice exhibiting a skin phenotype and cytokine abnormalities with strong similarities to human psoriasis. We observed that impaired function of CD4(+)CD25(+) regulatory T cells (Tregs) and increased cytokine levels of the IL-23/Th17 pathway were responsible for the psoriatic phenotype in this mouse model. Treatment of K5.hTGF-beta1 transgenic mice with PUVA suppressed the IL-23/Th17 pathway, Th1 milieu, as well as transcription factors STAT3 and orphan nuclear receptor RORgammat. PUVA induced the Th2 pathway and IL-10-producing CD4(+)CD25(+)Foxp3(+)Tregs with disease-suppressive activity that was abolished by anti-CTLA4 mAb treatment. These findings were paralleled by macroscopic and microscopic clearance of the diseased murine skin. Anti-IL-17 mAb treatment also diminished the psoriatic phenotype of the mice. This indicated that both induced Tregs involving CTLA4 signaling and inhibition of the IL-23/Th17 axis are central for the therapeutic action of PUVA.


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