Changes in the skin microbiome have been shown to promote cutaneous inflammation. The skin microbiome of patients with chronic plaque type psoriasis was analysed before and after treatment with narrowband ultraviolet B (UVB). Swab samples of the microbiome were taken from lesional and non-lesional skin of 26 patients. Microbiotas were characterized by sequencing 16S rRNA bacterial genes on the Illumina MiSeq platform. Lesional skin microbiome diversity correlated with psoriasis severity (measured with the Psoriasis Area and Severity Index; PASI). There was a significantly lower abundance of the phylum Firmicutes and the genus Staphylococcus in lesional skin compared with non-lesional skin before UVB treatment. Responders (> 75% target Psoriasis Severity Index (PSI) improvement) had significantly lower abundance of the phyla Firmicutes in lesional and non-lesional skin and lower abundance of the genera Staphylococcus, Finegoldia, Anaerococcus, Peptoniphilus, Gardnerella, Prevotella and Clostridium in lesional skin after UVB treatment. Pseudomonas significantly decreased in lesional and non-lesional skin of treatment responders. These results suggest that skin microbiome alterations after UVB treatment could be related to treatment and treatment response.

Studies have shown differences in the skin and gut bacterial microbiomes in patients with psoriasis, but the pharyngeal microbiome has not been studied previously. The aim of this study was to investigate differences in the bacterial microbiome of the pharynx and skin of patients with psoriasis compared with healthy controls. Swabs were taken from the pharynx and elbow skin of 39 patients with psoriasis and 70 controls. Microbiomes were characterized by sequencing 16S rRNA genes on the Illumina MiSeq platform. Significant differences were found in alpha and beta diversity in the skin, but not in the pharynx. Significant differences were also found between several phyla and genera in both skin and pharynx. The severity of psoriasis did not correlate with any genera in the pharynx, but with Capnocytophaga , Leptotrichia , Abiotrophia and Tannerella in the skin. The composition of the pharyngeal and skin microbiome may be of importance in the pathogenesis of psoriasis.

S100A8 and S100A9 proteins are highly upregulated in patients with psoriasis and have been proposed as potential biomarkers for psoriasis. The present study was designed to analyze the effect of narrowband ultraviolet B therapy on these proteins.S100A8, S100A9 gene expression and S100A8/A9 heterocomplex protein levels were analyzed in lesional and non-lesional skin before and after narrowband-UVB treatment in patients with chronic plaque type psoriasis. In addition, disease severity was measured by psoriasis area and severity index (PASI) and serum protein levels of S100A8/A9 were repeatedly analyzed. Narrowband-UVB treatment significantly reduced S100A8, S100A9 gene expression and S100A8/A9 protein levels in lesional skin while serum levels showed no significant change. No correlation between PASI and serum S100A8/A9 protein levels was found. These results implicate a role of S100A8/A9 in the anti-inflammatory effect of narrowband-UVB. Serum S100A8/A9 levels do not respond to treatment suggesting that serum S100A8/A9 does not originate from psoriasis skin keratinocytes. Serum S100A8/A9 levels do not correlate with PASI questioning serum S100A8/A9 as a biomarker for psoriasis skin activity.Trial Registration: DRKS 00014817.

WNT/β-catenin signaling pathways play a pivotal role in the human immune defense against infections and in chronic inflammatory conditions as psoriasis. Wnt gene alterations are linked to known comorbidities of psoriasis as obesity, diabetes and Crohn’s disease. The objective of this study was to investigate WNT7B, WNT10B, WNT16 and TCF7L2 gene and protein expression in lesional and non-lesional skin and in the peripheral blood of patients with chronic plaque psoriasis compared with healthy individuals. To investigate the effect of narrowband UVB radiation, expression of these genes were analyzed before and after narrowband UVB treatment. Associations between single nucleotide polymorphisms for WNT7B, WNT10B, WNT16 and TCF7L2 genes and psoriasis were tested. Our results show significantly decreased WNT7B, WNT10B and TCF7L2 gene expression in lesional skin compared with non-lesional skin and healthy controls. Narrowband UVB treatment significantly increased expression of these genes in lesional skin. Immunohistochemistry shows increased WNT16 expression in lesional skin. No significant differences in allele or genotype frequencies for Wnt or TCF7L2 gene polymorphisms were found between patient and control group. This study shows for the first time significant UVB induced upregulation of WNT7B, WNT10B and TCF7L2 in patients with psoriasis and suggests a potential role of these genes in psoriasis pathogenesis. Electronic supplementary material The online version of this article (10.1007/s00403-019-01931-y) contains supplementary material, which is available to authorized users.

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