可溶性IL-6R介导的IL-6/Stat3反式通路的异常活化在调控银屑病皮损形成过程中的作用研究

In the skin, Stat3 has been considered as a therapeutic target for the treatment of psoriasis, however, the pathological reason for the induction of abnormal STAT3 activation in epidermal keratinocytes is not clear. Interleukin-6 is a Stat3 activated cytokine involved in multiple types of inflammation, the biological function of IL-6 rely on its receptors, there are two forms of IL-6R, the membrane binding form of IL-6R which mediated the classical activation of IL-6/Stat3; the soluble form of IL-6R mainly act through the trans-signaling for the activation of IL-6/Stat3, which are frequently associated with the induction of various type of inflammations. In our previous study, we observed that there were significant increase of IL-6 and sIL-6R in the serum from patients with psoriasis, supplement of sIL-6R in the cultured keratinocytes resulted in a significant increase of Stat3 signaling pathway activaiton, accompanied with enhanced keratinocyte proliferation and abnormal differentiation. For a better understanding of the effect of sIL-6R mediated trans-signaling in control the development of psoriasis , here in this study, we aim to perform several experiments including the analysis of clinical samples, in vitro and in vivo assays, to explore the influence of sIL-6R mediated IL-6/Stat3 trans-signaling in controlling the functions of keratinocytes and T cells. Apart from measureing the effeciency of ADAM17 mediated protein sheding function, we are going to analysis the contribution of the functional IL6R polymorphism SNPs to the heritability of plasma sIL-6R levels to address the relevant mechanism why there are abnormal release of sIL-6R in psoriasis. By measuring the sIL-6R regulated Stat3 activation and analysis the possibility of targeting IL-6/Stat3 trans-signaling for the treatment of psoriasis, we are going to delineate the mechanism of sIL-6R mediated trans-signaling in regulation of the psoriasis development. This study will provide a direct experimental evidence to test the possibility for the treatment of psoriasis by targeting sIL-6R trans-signaling in skin epidermis.

Stat3通路的过度激活是诱发银屑病皮损形成的关键。IL-6是Stat3通路的上游分子，其生物学功能依赖两种不同类型的受体，包括跨膜受体mIL-6R以及可溶性受体sIL-6R，sIL-6R介导的Stat3反式通路的活化是诱发多种炎症形成的关键。我们的前期研究发现，银屑病患者IL-6 及 sIL-6R的血浆含量显著增加；培养的角质形成细胞中，sIL-6R可上调IL-6诱导的Stat3活化水平。为了进一步阐明sIL-6R 介导的Stat3反式通路活化在调控银屑病皮损形成中的作用，本课题将分别从临床标本、体外细胞学及动物实验三个层面，研究银屑病发病过程中诱导sIL-6R过度生成的分子机制，阐明IL-6R基因的SNP组成以及 ADAM17介导的蛋白剪切对sIL-6R表达的影响，验证以sIL-6R 为靶点进行银屑病治疗的可行性；本课题为进一步揭示银屑病的发病机制，筛选银屑病的治疗药物，提供实验依据。

研究背景：白细胞介素6可通过自分泌的方式，参与调控银屑病皮损的形成。白介素6的生物学功能主要依靠与特异性受体的结合发挥作用，其中包括膜结合型受体（mIL-6R ）以及可溶性受体（sIL-6R ）两种类型，两种受体分别以传统通路及反式通路的方式，诱导IL-6相关信号的活化，但在这一过程中，sIL-6R反式通路在调控银屑病发病中的作用，目前尚不清除。.研究内容：本课题通过开展临床样本分析，研究了IL-6R的基因型SNP组成对血浆sIL-6R表达的影响；在此基础上，通过开展细胞学实验，我们进一步分析了sIL-6R通路活化对银屑病皮损形成的影响，重点观察了sIL-6R介导的反式通路激活对皮肤角质形成细胞的功能，以及对STAT3通路活化的调控作用；在动物实验中，我们检测了sIL-6R介导的反式通路的激活与抑制对银屑病皮损形成的影响，同时探讨了以IL-6反式通路为靶点开展银屑病治疗的可行性。.研究结果：本课题的研究发现，银屑病患者血浆IL-6其及可溶性受体sIL-6R的表达水平显著上调，说明IL-6反式信号对银屑病皮损的形成过程中发挥重要作用；基因分型检测发现，编码IL-6R的基因存在着两个关键性的SNP位点，其中包括rs4845617 和 rs2228145这两个重要的调控位点，分别位于IL-6R基因的启动子区和蛋白酶识别与剪切部位；人群中的SNP组成差异可影响sIL-6R的表达水平，其中位于IL-6R基因启动子区的rs4845617位点，参与调控sIL-6R的表达水平。为了检测sIL-6R的功能，我们分别利用培养的角质形成细胞和米奎莫特诱导的银屑病动物模型，研究了sIL-6R在银屑病发病中的作用。我们的研究发现，在培养的角质形成细胞中，sIL-6R介导的反式通路可显著增加STAT3通路的活化水平，引发角质形成细胞的过度增殖与异常角化；而在银屑病小鼠动物模型中，sIL-6R可显著促进皮损的形成，而使用IL-6反式通路的拮抗剂gp130-FC对银屑病皮损的形成具有明显的保护作用；.研究意义：本课题的研究结果对于深入阐明银屑病的发病机制，筛选针对银屑病的新型治疗靶点，具有重要的理论意义和潜在的临床应用前景。