BackgroundPsoriasis is a chronic inflammatory skin disease characterized by epidermal hyperproliferation and altered keratinocyte differentiation and inflammation and is caused by the interplay of genetic and environmental factors. Previous studies have revealed that DNA methylation (DNAm) and genetic makers are closely associated with psoriasis, and strong evidences have shown that DNAm can be controlled by genetic factors, which attracted us to evaluate the relationship among DNAm, genetic makers, and disease status.MethodsWe utilized the genome-wide methylation data of psoriatic skin (PP, N = 114) and unaffected control skin (NN, N = 62) tissue samples in our previous study, and we performed whole-genome genotyping with peripheral blood of the same samples to evaluate the underlying genetic effect on skin DNA methylation. Causal inference test (CIT) was used to assess whether DNAm regulate genetic variation and gain a better understanding of the epigenetic basis of psoriasis susceptibility.ResultsWe identified 129 SNP-CpG pairs achieving the significant association threshold, which constituted 28 unique methylation quantitative trait loci (MethQTL) and 34 unique CpGs. There are 18 SNPs were associated with psoriasis at a Bonferoni-corrected P < 0.05, and these 18 SNPs formed 93 SNP-CpG pairs with 17 unique CpG sites. We found that 11 of 93 SNP-CpG pairs, composed of 5 unique SNPs and 3 CpG sites, presented a methylation-mediated relationship between SNPs and psoriasis. The 3 CpG sites were located on the body of C1orf106, the TSS1500 promoter region of DMBX1 and the body of SIK3.ConclusionsThis study revealed that DNAm of some genes can be controlled by genetic factors and also mediate risk variation for psoriasis in Chinese Han population and provided novel molecular insights into the pathogenesis of psoriasis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13148-016-0297-z) contains supplementary material, which is available to authorized users.

Substantial alterations of the intestinal microbiota in psoriasis patients of ChinaPsoriasis is an immune-mediated inflammatory skin condition.Accumulating evidence suggests that there is an intimate relationship between intestinal dysbiosis and psoriasis. In order to evaluate

Objective The objective of this study was to perform noninvasive analysis of skin proteins in a healthy Chinese population using label‐free nanoflow liquid chromatography‐mass spectrometry (nLC‐MS). Materials and Methods Five consecutive tape strippings were obtained from the volar forearm skin of healthy Chinese subjects. Proteins were extracted, and trypsin‐digested peptides were analyzed by a nanochromatography instrument coupled to an Orbitrap Fusion Tribrid mass spectrometer. Data‐dependent acquisition allowed protein identification, which was performed by using Proteome Discoverer software (v2.2). Results In this study, we identified 80 common proteins that were expressed in the skin of healthy Chinese volunteers and divided these proteins into 16 categories, including keratins, cornified envelope proteins, and enzymes associated with substance metabolism. These proteins were closely associated with multiple functions of the skin barrier. Conclusion This study provides a noninvasive method to analyze healthy human epidermal proteins, which are closely associated with the skin barrier. In addition, this study provides a reference for further studies on the application of proteomic technologies to investigate the role of human epidermal proteins in health and disease.