Psoriasis is a chronic inflammatory skin disease related to immune, whose complexity of molecular mechanisms is still not fully clear. RNA sequencing has been widely applied in various fields including biological medicine. According to the bioinformatics analysis of differential genes, biomarkers and drug targets have been discovered for the diagnosis and treatment of diseases. Besides, the pathological mechanisms of disease and functions of gene can be evaluated. In the present study, we report the application of RNA sequencing in skin tissues from psoriatic and healthy persons. By obtaining 2139 differential expressed genes (DEGs), 208 significantly differential GO terms and 44 significantly differential pathways were generated. We found that the functions of DEGs were mainly related to cell cycle, inflammatory, virus, immune response and metabolic process.The major pathways included cytokine-cytokine receptor interaction, Toll-like receptor signaling pathway, chemokine signaling pathway, cell cycle, metabolic pathways, ribosome, peroxisome, steroid biosynthesis and biosynthesis of unsaturated fatty acids. Furthermore, co-expression network was constructed to identify core genes and relations between genes. we considered genes with high values of degree and k-core difference in the co-expression network as core genes, such as IFNG, IL26, TLR3, PRKCQ, TLR4, CD274, CDK1 and IL17A. We chose CD274, an important immune checkpoint, to evaluate its regulatory mechanisms. Candidate genes related to CD274 were evaluated by the co-expression network analysis, and the relations between CD274 and candidate genes were validated in epidermal keratinocytes. Finally, IFNG and CDK1 inhibitor (indirubin) were found increasing the expression levels of CD274. In addition, indirubin was confirmed to attenuate mouse psoriasis-like skin lesion with the mechanisms related to CD274. In conclusion, this study provides us a comprehensive transcriptome analysis method on psoriasis to identify core genes and explore the important regulatory functions of genes.
Overall design: Nine normal skins from healthy volunteers and 18 lesional skins from patients with psoriasis vulgaris were obtained for RNA sequencing
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