microRNA-210对角质形成细胞趋化功能的调控及其在银屑病皮损形成中的作用机制研究

The interaction between keratinocytes and immune cells is central to the formation of psoriatic lesions. It has been confirmed that keratinocytes in psoriatic skin lesion recruit the skin homing of activated peripheral T lymphocytes through secreting a lot of chemokines. However, the underlying molecular mechanism of aberrant chemotactic function of keratinocytes in psoriasis is still unknown. MicroRNAs has been proved to be involved in the pathogenesis of psoriasis. Our previous experiments found that the expression of miR-210 was increased significantly in skin lesions of psoriasis vulgaris compared with normal controls and overexpressing miR-210 could induce the production of CCL5 and CCL20 in keratinocytes. Therefore, we proposed a new hypothesis that up-regulated miR-210 induces the overproduction of chemokines by keratinocytes in psoriatic lesions to increase skin homing of activated T lymphocytes, promoting the formation of psoriatic skin lesions. Our project will investigate the role and mechanism that miR-210 regulates the chemotactic function of keratinocytes and explore the effect of miR-210 overexpression on the formation of skin lesions in psoriasis-like mouse models. This project will help to further clarify the pathogenesis of psoriasis vulgaris and will provide a novel target for psoriasis treatment.

角质形成细胞与免疫细胞的相互作用是银屑病皮损形成的关键。研究证实，在银屑病皮损组织中角质形成细胞通过分泌大量趋化因子，促进循环的活化T细胞皮肤归巢。然而，角质形成细胞趋化T细胞归巢的分子机制目前尚未阐明。研究表明，microRNAs参与银屑病发病机制中的多个环节。我们前期预实验发现miR-210在寻常型银屑病皮损中表达升高，过表达miR-210可诱导角质形成细胞分泌趋化因子CCL5、CCL20。由此，我们提出miR-210过度表达，促进银屑病皮损角质形成细胞分泌大量趋化因子，导致活化T细胞归巢增加，进一步促进银屑病皮损形成的全新假说。本课题拟通过体内外实验阐明miR-210对角质形成细胞趋化功能的调控机制以及对银屑病样小鼠模型皮损形成的影响，同时，初步探讨银屑病角质形成细胞中miR-210表达上调的分子机制。通过该研究为阐明银屑病皮损形成的机制、发现银屑病治疗新靶点提供理论和实验依据。

银屑病是一种多因素﹑免疫介导的慢性炎症性皮肤病。银屑病皮损组织中角质形成细胞通过分泌大量趋化因子，促进循环的活化T细胞皮肤归巢，而T淋巴细胞活化并迁移至发病部位是银屑病发病的关键步骤。我们先前的研究表明，miR-210在银屑病CD4+ T细胞功能失调和皮损形成中发挥了至关重要的作用，但miR-210是否也通过调控角质形成细胞趋化功能从而促进T细胞活化与迁移尚不清楚，因此本项目进一步探究miR-210对角质形成细胞趋化功能的调控作用及其具体的分子机制。研究结果显示：寻常型银屑病患者皮损组织中趋化因子CCL5、CCL20和CXCL10的mRNA表达水平较正常人均显著升高；患者皮损区浸润的CD4+ T细胞中趋化因子受体CCR5、CCR6、CXCR3的mRNA表达水平较外周血CD4+ T细胞明显升高；通过免疫荧光进一步证实寻常型银屑病患者皮损组织中CD4+ T细胞中趋化因子受体CXCR3及CCR5的表达均明显增多。通过体外实验证实过表达或抑制miR-210可促进或抑制HaCaT细胞中趋化因子的表达和分泌，transwell实验结果表明HaCaT细胞过表达miR-210可显著促进CD4+ T细胞的迁移。体内实验表明，皮内注射miR-210模拟物（agomir-210）的银屑病小鼠皮损明显加重，且皮损和血清中趋化因子的表达增多；而miR-210基因敲除的银屑病小鼠皮损减轻，皮损和血清中趋化因子的表达显著减少。我们利用生物信息学预测发现，FoxO3可能为miR-210下游潜在靶基因。银屑病患者皮损组织中FoxO3的表达水平显著降低, miR-210基因敲除小鼠银屑病皮损中FoxO3的表达水平显著升高。过表达miR-210可显著降低HaCaT细胞FoxO3的表达,而抑制miR-210可显著升高HaCaT细胞FoxO3的表达。干扰FoxO3可显著升高HaCat细胞中趋化因子CCL5、CCL20和CXCL10的mRNA表达水平。我们通过以上实验首次证明miR-210可能通过抑制靶基因FoxO3的表达促进角质形成细胞分泌CCL5、CCL20、CXCL10，进而调控T细胞的迁移，参与银屑病的发生发展。该研究进一步完善了银屑病的发病机制，为靶向miR-210治疗银屑病提供了新的理论依据。