器官移植慢性排斥反应的主要病理学基础是移植物动脉硬化，它是导致慢性移植物失功的重要原因。研究表明，血管平滑肌细胞(VSMC)表型转化是移植物动脉硬化的始动因素和关键环节，但是移植损伤引起VSMC表型转化的分子机制目前尚不清楚。我们前期研究提示，LKB1可能作为VSMC的看家基因，由AMPK/Hippo/YAP信号轴介导负向调控VSMC表型转化，并抑制移植物动脉硬化。. 本项目拟体外培养VSMCs，采用基因转染和药物干预等方法，阐明LKB1负向调控HMGB1诱导YAP活化及VSMC表型转化的作用及分子机制；然后制备含有LKB1或shRNA-LKB1的SM22α启动子慢病毒，感染移植动脉供体并建立大鼠腹主动脉移植模型，探讨移植动脉VSMC中LKB1基因表达对VSMC表型转化和移植动脉内膜增生的影响。本研究将进一步揭示移植物动脉硬化发生发展的内在机制，为临床防治慢性移植物失功提供新思路。

Organ transplantation is currently the most effective therapy for patients with end-stage organ failure. Chronic allograft rejection is the leading cause of chronic allograft dysfunction following organ transplantation. There is growing evidence to suggest that transplant arteriosclerosis is the common histopathological characteristic of chronic allograft rejection in different transplants including heart, kidney and lung. It has been demonstrated that phenotypic modulation of vascular smooth muscle cells (VSMCs) from contractile phenotype to synthetic phenotype is a central event in the initiation and progression of neointimal formation and transplant arteriosclerosis after transplantation. However, so far the molecular mechanism underlying VSMC phenotypic modulation in allografts remains to be elucidated. Our preliminary studies indicated that LKB1 acting as a gatekeeper of contractile VSMCs may play a critical role in negatively regulating VSMC phenotypic modulation and subsequent transplant arteriosclerosis through AMPK/Hippo/YAP signaling axis.. In this project, to explore the role of LKB1 in the regulation of VSMC phenotypic modulation and its possible mechanism, rat aortic VSMCs will be cultured in vitro and exposed to HMGB1 preceded by treatment with pcDNA-LKB1 transfection, specific siRNA-LKB1 transfection, or inhibitors of various signaling molecules. In vitro experiments are focused on elucidating the signaling mechanism underlying the modulation of LKB1 expression and VSMC phenotypic modulation stimulated by HMGB1. Moreover, to gain better insights into the functions of LKB1 in SMC phenotypic modulation and transplant arteriosclerosis following allogeneic transplantation, animal model of aortic transplantation will be established between BN and Lewis rats, in which aortic allografts will be infected with lentivirus carrying LKB1 gene or shRNA-LKB1 whose specific expression in VSMCs is controlled by a minimal SM22α promoter. This project aims to elucidate the precise molecular mechanism of VSMC phenotypic modulation and transplant arteriosclerosis after transplantation. This study will provide novel evidence for the development of new therapeutic strategies to prevent chronic allograft rejection.