Narrow-band UVB phototherapy for psoriasis

Psoriasis is a common chronic inflammatory and hyperproliferative immune-mediated skin disorder. Narrow-band UVB (NB-UVB) phototherapy is a convenient first-line treatment of psoriasis, though the mechanisms underlying its efficacy have not been completely elucidated. In order to improve our understanding of NB-UVB phototherapy, gene expression profiling was used to characterize gene expression in lesional epidermis from psoriasis patients undergoing NB-UVB phototherapy. Increased expression of melanogenesis pathway genes was observed to be the earliest response. At the end of treatment, genes involved in diverse biological processes were affected, such as pigmentation, cell adhesion, ectodermal development and metabolism. The relationship between gene expression and treatment outcome was further studied using Partial Least Squares Discriminant Analysis (PLS-DA). Gene ontology analysis showed that genes responding to phototherapy and highly correlated to treatment outcome were involved in oxidation reduction, growth and mitochondria organization. In particular SPATA18, a key regulator of mitochondria quality, was found to be significantly downregulated in psoriasis, and its upregulation following phototherapy was required for optimal clinical improvement. Our data suggest that oxidation reduction is a critical event for the resolution of psoriatic plaques.

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Gu X, Nylander E, Coates PJ, Nylander K