Livin is upregulated in keratinocytes and promotes the release of inflammatory mediators in psoriasis

Psoriasis is a common chronic inflammatory skin disease. Keratinocytes (KCs) are important effector cells that can recruit inflammatory cells by releasing inflammatory factors and chemokines to promote the inflammatory cascade in psoriasis. However, the mechanism underlying KC activation in psoriasis remains unclear. Livin is an inhibitor of apoptotic proteins and its expression can directly affect the proliferation and metastasis of tumor cells. Livin expression has been reported to be significantly increased in the lesions of patients with psoriasis; however, its specific role in KC activation has not yet been reported. The aim of this study was to investigate whether livin regulates KC activation and causes the release of inflammatory mediators. The expression levels of livin in patients with psoriasis, an imiquimod (IMQ) mouse model, and M5-treated HaCaT cells were determined via immunofluorescence staining, reverse transcription-quantitative polymerase chain reaction, enzyme-linked immunosorbent assay (ELISA), and western blotting. We constructed livin knockdown (Knockdown-HaCaT) and negative control (NC-HaCaT) cells using human immunodeficiency virus-1-based lentiviral vectors to study the function of livin in KCs via RNA-sequencing and proteomics analysis. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed. Moreover, the effect of livin expression on the release of inflammatory mediators in KCs was verified using ELISA.

银屑病（Psoriasis）是一种常见的慢性炎症性皮肤病。角质形成细胞（Keratinocytes，KCs）作为重要的效应细胞，可通过释放炎症因子与趋化因子招募炎症细胞，进而推动银屑病的炎症级联反应。然而，银屑病中角质形成细胞激活的潜在分子机制仍未阐明。Livin是一种凋亡抑制蛋白（inhibitor of apoptotic proteins），其表达可直接影响肿瘤细胞的增殖与转移。已有研究报道，银屑病患者皮损组织中Livin的表达水平显著升高，但其在角质形成细胞激活过程中的具体作用尚未见报道。本研究旨在探究Livin是否可调控角质形成细胞激活并介导炎症介质释放。本研究通过免疫荧光染色、逆转录定量聚合酶链反应（reverse transcription-quantitative polymerase chain reaction）、酶联免疫吸附试验（ELISA）以及蛋白质印迹（western blotting），检测了银屑病患者、咪喹莫特（imiquimod，IMQ）诱导小鼠模型以及经M5处理的HaCaT细胞中Livin的表达水平。本研究基于人类免疫缺陷病毒1型（human immunodeficiency virus-1）慢病毒载体，构建了Livin敲低细胞株（Knockdown-HaCaT）与阴性对照细胞株（NC-HaCaT），并通过RNA测序（RNA-sequencing）与蛋白质组学分析，探究Livin在角质形成细胞中的生物学功能。随后开展了基因本体（Gene Ontology，GO）与京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes，KEGG）富集分析。此外，本研究还通过ELISA验证了Livin表达对角质形成细胞炎症介质释放的影响。