骨桥蛋白在Hedgehog通路参与的系统性硬皮病血管损伤和成纤维细胞活化中的作用机制研究

Systemic sclerosis (SSc) is characterized by immune dysregulation, microvasculopathy and fibrosis involving skin as well as internal organs. Activated fibroblasts are responsible for abnormal extracellular matrix accumulation. Although it was reported that osteopontin (OPN) is highly expressed in the plasma and skin tissue of systemic sclerosis patients’, the mechanisms of the role of osteopontin in the development of dermal fibrosis in systemic sclerosis remain unclear. It has been known that Hedgehog pathway activation is involved in vascular smooth muscle cells proliferation, fibroblast activation and tissue fibrosis in systemic sclerosis, and in hepatic stellate cells (HSC), osteopontin is induced by Hedgehog pathway activation. This study focus on the role of osteopontin in inducing vasculopathy and fibroblast activation in systemic sclerosis and its mechanisms. First, the level, distribution and localization of osteopontin in systemic sclerosis patients’ skin biopsy is identified. Whether there is co-localization of osteopontin in skin tissue with Hedgehog activation signals is studied. Second, the cellular source of osteopontin in the microenvironment of skin tissue (secreted by immune cells, vascular smooth muscle cells and fibroblasts) is identified. Third, immune cells recruitment in response to secreted osteopontinn are studied. Last, the role of osteopontin in phenotype transformation of vascular smooth muscle cells and fibroblast activation in systemic sclerosis and its mechanisms are studied. The aim is to clarify whether the effects of osteopontin on phenotype transformation of vascular smooth muscle cells (leading to fibroproliferative vasculopathy) and fibroblast activation (cell proliferation, phenotype transformation and collagen synthesis) in systemic sclerosis are mediated by Hedgehog pathway activation. This study may suggest a novel therapeutic target in systemic sclerosis.

系统性硬皮病(systemic sclerosis, SSc)免疫紊乱，血管病变，成纤维细胞(fibroblast, Fb)活化，引起纤维化。骨桥蛋白(osteopontin, OPN)在SSc血浆和皮损中表达增高，但其在SSc发病机制中的作用尚不清楚。鉴于Hedgehog(Hh)通路活化参与SSc 血管平滑肌细胞增殖、Fb活化和组织纤维化，且有报道Hh通路活化诱导OPN表达，拟研究OPN在SSc血管病变、Fb活化中的作用及机制：1.明确SSc皮肤组织中OPN的表达及定位，皮肤组织中OPN是否与Hh通路活化因子高表达共定位；2.研究SSc皮肤组织微环境中OPN的来源（免疫细胞、血管平滑肌细胞及成纤维细胞）；3.探讨OPN对免疫细胞的募集作用；4.研究OPN在SSc血管平滑肌细胞表型转化及Fb活化中的作用及机制；探讨OPN在SSc血管平滑肌细胞表型转化（合成细胞外基质，导致纤维增生性血管病变）及Fb活化（细胞增殖、表型转化及胶原合成）中的作用是否通过Hh通路活化介导，为寻找SSc新的治疗靶点提供依据。

系统性硬皮病（SSc）免疫紊乱，血管损伤，成纤维细胞（Fb）活化，引起纤维化。骨桥蛋白（OPN）在SSc血浆和皮损中表达增高，但其在SSc发病机制中的作用尚不清楚。鉴于Hedgehog（Hh）通路活化参与SSc血管平滑肌细胞增殖、Fb活化和组织纤维化，且有报道Hh通路活化诱导OPN表达，拟研究OPN在 SSc血管损伤、Fb活化中的作用及机制，明确SScPBMC和皮肤组织中OPN的表达及定位，皮肤组织中OPN是否与Hh通路活化因子高表达共定位；研究SSc皮肤组织微环境中OPN的来源及OPN对免疫细胞的募集作用；研究OPN在SSc血管内皮细胞炎症、血管平滑肌细胞表型转化及Fb活化中的作用及机制，探讨OPN在SSc血管平滑肌细胞表型转化（合成细胞外基质，导致纤维增生性血管病变）及Fb活化中的作用是否通过Hh通路活化介导。. 研究显示SScPBMC中Th17和单核细胞高表达OPN，血浆中sOPN高表达。激光共聚焦/免疫荧光三标检测显示SSc皮肤组织中OPN高表达，与Hh通路活化因子Gli1/Gli2高表达共定位。Transwell技术显示sOPN趋化单核细胞，对其有募集作用，ELISA检测显示SSc微环境中sOPN主要来源于免疫细胞旁分泌。OPN可引起皮肤微血管内皮细胞黏附分子ICAM-1、 VCAM-1及趋化因子CXCR-4表达增高，可能通过整合素β1受体介导。OPN可诱导血管平滑肌细胞表型转化（转换为合成表型）；抑制Hh通路，SSc血管平滑肌细胞OPN表达减少，Ⅰ型胶原表达降低。SSc免疫活性细胞可通过旁分泌sOPN参与皮肤Fb活化，抑制Hh通路，SSc皮肤FbOPN表达减少，Ⅰ型胶原表达降低。本研究为寻找SSc新的治疗靶点提供依据。