Noninvasive analysis of skin proteins in healthy Chinese subjects using an Orbitrap Fusion Tribrid mass spectrometer.

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.

Non­invasive proteome­wide quantification of skin barrier­related proteins using label­free LC­MS/MS analysis.

A number of epidermal proteins are closely related to skin barrier function, the abnormalities of which can lead to specific skin diseases. These proteins must be quantified to further investigate the changes in the skin barrier between healthy and disease states. However, the non­invasive and proteome­wide quantification of skin proteins without any labelling steps remains a challenge. In this study, 3M medical adhesive tapes were used to obtain skin samples from volunteers. Proteins were extracted from fresh skin samples and digested with trypsin. Each tryptic peptide was analysed in three replicates using liquid chromatography with tandem mass spectrometry analysis and label­free quantification. The data were searched against the Human Universal Protein Resource (UniProt) to match with known proteins. Using this method, 1,157 skin proteins recorded in the UniProt were quantified. A total of 50 identical proteins were identified in the three replicate analyses of all samples with no significant differences in abundance. The results provided an objective metric for further study of skin ageing and various skin diseases. Specifically, the non­invasive proteome­wide method used in this study can be applied to future studies of skin diseases related to barrier destruction by monitoring the changes in the levels of epidermal proteins.

A rare variant in COL11A1 is strongly associated with adult height in Chinese Han population.

Human height is a highly heritable trait in which multiple genes are involved. Recent genome-wide association studies (GWASs) have identified that COL11A1 is an important susceptibility gene for human height. To determine whether the variants of COL11A1 are associated with adult and children height, we analyzed splicing and coding single-nucleotide variants across COL11A1 through exome-targeted sequencing and two validation stages with a total 20,426 Chinese Han samples. A total of 105 variants were identified by exome-targeted sequencing, of which 30 SNPs were located in coding region. The strongest association signal was Chr1_103380393 with P value of 4.8 × 10(-7). Chr1_103380393 also showed nominal significance in the validation stage (P = 1.21 × 10(-6)). Combined analysis of 16,738 samples strengthened the original association of chr1_103380393 with adult height (Pcombined = 3.1 × 10(-8)), with an increased height of 0.292sd (standard deviation) per G allele (95% CI: 0.19-0.40). There was no evidence (P = 0.843) showing that chr1_103380393 altered child height in 3688 child samples. Only the group of 12-15 years showed slight significance with P value of 0.0258. This study firstly shows that genetic variants of COL11A1 contribute to adult height in Chinese Han population but not to children height, which expand our knowledge of the genetic factors underlying height variation and the biological regulation of human height.

Epigenome-wide association data implicates DNA methylation-mediated genetic risk in psoriasis.

BACKGROUND: Psoriasis 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. METHODS: We 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. RESULTS: We 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. CONCLUSIONS: This 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.