TGF-β2经Rho GTPase信号通路调控静脉血栓后管壁重塑的机制研究

Venous wall fibrosis remodeling is one of the important pathogenesis of post thrombotic syndromes (PTS). Although the correlation between the inflammation and the remodeling has attracted more and more attention, the detailed mechanism is still unclear. The TGF-β has a wide range of biological functions and play a important role in the induction of fibrosis through the promotion of extracellular matrix (ECM) gene and collagen deposition. Our former research showed that TGF-β2 was closely related with collagen deposition in human thrombotic vein wall and the expression of Rho GTPases, one of the important downstream signaling molecules associated with fibrosis, was significantly increased. Based on this, we set the scientific hypothesis: TGF-β2 may promote venous wall fibrosis remodeling by Rho GTPases signaling pathway in PTS. In this study, we first observe the relationship between the change of venous wall remodeling and TGF-β2 in human specimen. Secondly, the effect of exogenous TGF-β2 on the remodeling is observed by animal model, which is mainly focused on the changes of smooth muscle cell phenotype, collagen deposition and ECM remodeling. Finally, the signal mechanism of venous wall remolding through TGF-β2-Rho GTPase-MRTF-SRF is studied with inhibitor method. The aim of this study is to elucidate the major mechanism of TGF-β2 on the venous wall remolding in PTS, further to provide clues and theory for precision intervention and treatment of PTS in the future.

管壁纤维化重塑是静脉血栓后综合征（PTS）发病机制研究热点，虽然炎症反应与其相关性日益引起关注，但具体机制不明。最新研究发现TGF-β可通过上调细胞外基质、促进胶原沉积发挥诱导纤维化转变的作用。前期我们已证实，血栓静脉壁中TGF-β2与胶原沉积密切相关，同时其下游与纤维化相关的信号分子Ras相似物GTP酶（Rho GTPases）表达显著升高，据此提出科学假设：TGF-β2可能通过Rho GTPase信号通路促进PTS管壁重塑。本课题通过人体标本、动物模型和细胞培养 探索PTS管壁重塑改变与TGF-β2的相关性。重点关注TGF-β2对平滑肌细胞表型转变、胶原蛋白沉积和ECM重构的影响。将Rho GTPase-MRTF-SRF作为切入点，通过正向刺激和信号通路抑制等方法，研究TGF-β2促管壁重塑的信号级联机制。在阐明TGF-β2调控PTS管壁重塑机制的同时，为靶向治疗PTS提供理论依据。

管壁纤维化重塑是静脉血栓后综合征（PTS）发病机制研究热点。转化生长因子-β（TGF-β）是一类具有多重生物学效应的生长因子，它在血管重塑中的作用仍存在争议。既往研究表明TGF-β可以上调细胞外基质，促进胶原沉积，从而诱导纤维化转变。我们前期研究发现，血栓静脉壁中TGF-β2与胶原改变密切相关，其下游与纤维化相关的信号分子Ras相似物GTP酶（Rho GTPases）表达显著升高。然而， TGF-β2在静脉血栓后管壁重塑中的作用，目前仍不清楚。本研究发现，人血栓段静脉管壁TGFβ2表达下调，平滑肌细胞内收缩型标志物表达下降，合成型标志物表达增多，使平滑肌表型由收缩型向合成型转变，造成血栓段静脉胶原增多、纤维排列紊乱、细胞外基质异常沉积。体外研究也表明，TGFβ2可以通过激活下游Smad和Rho GTPases-ERK信号通路，增加人脐静脉平滑肌细胞系和原代培养的大鼠平滑肌细胞内收缩型表型标记物的表达，而对合成型标志物影响较小。血栓动物模型显示，TGFβ2的局部使用能较好的恢复受损平滑肌细胞的收缩功能，上调收缩标志物的表达，但对已经升高的合成型标志物作用不明显。细胞划痕实验也显示，TGFβ2抑制体外原代培养的人静脉平滑肌细胞的迁移能力。综上所述，本研究表明TGF-β2在静脉血栓发生后SMC表型转化、ECM成分改变和管壁重塑中发挥重要功能，并为临床PTS疾病的治疗和干预提供新的实验依据。