S100A9通过激活成纤维细胞参与硬皮病皮肤纤维化的机制研究

Scleroderma is an autoimmune disease, characterized by progressive fibrosis of skin and internal organs. However, the mechanisms of scleroderma remain unclear. The fibroblasts are considered to be responsible for excessive collagen and other ECM synthesis and deposition that occur in skin fibrosis. The mouse model of scleroderma established by local injections of bleomycin is a classic model in this field. Our previous data found that the skin tissues from bleomycin treated mice had significantly increased expression of S100A9 by using gene expression chips. S100A9 is confirmed to exert pro-inflammatory effects, whether the cytokine has pro-fibrotic function remains unknown. Our previous research showed that the levels of S100A9 were elevated in the plasma and sclerotic skin of scleroderma patients than controls, and the human embryo lung fibroblasts were activated by S100A9 in vitro. The aims of this study are to investigate whether S100A9 can stimulate skin fibroblasts to produce more collagen, to further determine whether S100A9 could aggravate bleomycin induction of sclerotic changes of the mouse skin, to understand whether the sclerotic changes of the mice skin induced by bleomycin can be alleviate using anti-S100A9 antibody and to further study the fibrotic skin of S100A9 knock-out mice induced by bleomycin can be less. This study may provide insight on the treatment of scleroderma.

硬皮病是一种以皮肤及多个内脏器官炎症和弥漫性纤维化为特征的自身免疫性疾病，其发病机制一直未明。目前认为硬皮病患者的皮肤纤维化是由于成纤维细胞过度活化导致细胞外基质产生增加所致，成纤维细胞在该病的发病过程中发挥着关键作用。博来霉素可诱导小鼠皮肤发生纤维化，是硬皮病研究领域的经典模型。本课题组将博来霉素诱导性硬皮病鼠皮肤组织进行基因谱芯片扫描，发现S100A9基因表达明显升高；申请人的前期研究进一步发现硬皮病患者血浆和病变皮肤组织中S100A9含量亦显著升高，且体外S100A9可活化肺成纤维细胞。S100A9已被证实有强大的促炎活性，但尚不清楚该因子是否具有致纤维化的功能。本项目将探讨S100A9如何激活人皮肤成纤维细胞，并诱导细胞分泌细胞外基质增多；观察抗S100A9抗体能否缓解硬皮病模型鼠皮肤的纤维化进程，从而为硬皮病寻找新的治疗靶点提供理论依据。

硬皮病是一种以皮肤及多个内脏器官炎症和弥漫性纤维化为特征的自身免疫性疾病，其发病机制一直未明。本课题组前期研究发现硬皮病患者血浆和病变皮肤组织中S100A9含量亦显著升高。本项目中，我们发现体外S100A9可显著上调人皮肤成纤维细胞分泌炎症因子，并促进细胞表达胶原、α-平滑肌肌动蛋白(α-smooth muscle actin,α-SMA)和晚期糖基化终末产物受体(receptor for advanced glycation end-product,RAGE)增加；S100A9可活化细胞内的ERK1/2 MAPK 和NF-κB信号通路。高剂量博来霉素造模1、2、3 周后，硬皮病模型鼠皮肤组织中S100A9蛋白水平和mRNA含量均逐渐增高，显著高于生理盐水对照组。此外，将 S100A9与低剂量博来霉素同时给药，发现S100A9明显促进低剂量博来霉素诱导小鼠背部皮肤发生纤维化硬化，皮肤厚度显著增加，皮肤内炎症因子、胶原、α-SMA 表达增多，两者协同的促纤维化效应更强于高剂量博来霉素注射组小鼠。本课题组通过与南京大学模式动物研究所合作，成功制备出S100A9基因敲除小鼠，选用C57BL/6 小鼠作为野生型鼠，两组小鼠皮下注射博来霉素连续三周，发现S100A9基因敲除小鼠皮肤纤维化程度较野生型鼠明显减轻。本研究结果显示，S100A9可活化皮肤成纤维细胞，加重博来霉素诱导的小鼠皮肤纤维化硬化，并且S100A9-/-鼠抵制博来霉素诱导性硬皮病鼠皮肤纤维化进程，从而为硬皮病寻找新的治疗靶点提供了理论依据。