Kim Chan Woo, Pokutta-Paskaleva Anastassia, Kumar Sandeep, Timmins Lucas H, Morris Andrew D, Kang Dong-Won, Dalal Sidd, Chadid Tatiana, Kuo Katie M, Raykin Julia, Li Haiyan, Yanagisawa Hiromi, Gleason Rudolph L, Jo Hanjoong, Brewster Luke P
From Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta (C.W.K., A.P.-P., S.K., D.-W.K., J.R., R.L.G., H.J., L.P.B.); Department of Microbiology, College of Medicine, Inha University, Incheon, Republic of Korea (C.W.K.); Department of Surgery, Emory University, Atlanta, GA (A.P.-P., A.D.M., T.C., K.M.K., H.L., L.P.B.); Department of Radiology and Imaging Sciences, Emory University, Atlanta, GA (L.H.T.); Department of Bioengineering, University of Utah, Salt Lake City (L.H.T.); Mercer University School of Medicine, Macon, GA (S.D.); Life Science Center, Tsukuba Advanced Research Alliance, University of Tsukuba, Ibaraki, Japan (H.Y.); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta (R.L.G.); Surgical and Research Services, Atlanta VA Medical Center, Decatur, GA (L.P.B.); and Parker H. Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta (L.P.B.).
Circulation. 2017 Sep 26;136(13):1217-1232. doi: 10.1161/CIRCULATIONAHA.116.026361. Epub 2017 Aug 4.
Arterial stiffness and wall shear stress are powerful determinants of cardiovascular health, and arterial stiffness is associated with increased cardiovascular mortality. Low and oscillatory wall shear stress, termed disturbed flow (d-flow), promotes atherosclerotic arterial remodeling, but the relationship between d-flow and arterial stiffness is not well understood. The objective of this study was to define the role of d-flow on arterial stiffening and discover the relevant signaling pathways by which d-flow stiffens arteries.
D-flow was induced in the carotid arteries of young and old mice of both sexes. Arterial stiffness was quantified ex vivo with cylindrical biaxial mechanical testing and in vivo from duplex ultrasound and compared with unmanipulated carotid arteries from 80-week-old mice. Gene expression and pathway analysis was performed on endothelial cell-enriched RNA and validated by immunohistochemistry. In vitro testing of signaling pathways was performed under oscillatory and laminar wall shear stress conditions. Human arteries from regions of d-flow and stable flow were tested ex vivo to validate critical results from the animal model.
D-flow induced arterial stiffening through collagen deposition after partial carotid ligation, and the degree of stiffening was similar to that of unmanipulated carotid arteries from 80-week-old mice. Intimal gene pathway analyses identified transforming growth factor-β pathways as having a prominent role in this stiffened arterial response, but this was attributable to thrombospondin-1 (TSP-1) stimulation of profibrotic genes and not changes to transforming growth factor-β. In vitro and in vivo testing under d-flow conditions identified a possible role for TSP-1 activation of transforming growth factor-β in the upregulation of these genes. TSP-1 knockout animals had significantly less arterial stiffening in response to d-flow than wild-type carotid arteries. Human arteries exposed to d-flow had similar increases TSP-1 and collagen gene expression as seen in our model.
TSP-1 has a critical role in shear-mediated arterial stiffening that is mediated in part through TSP-1's activation of the profibrotic signaling pathways of transforming growth factor-β. Molecular targets in this pathway may lead to novel therapies to limit arterial stiffening and the progression of disease in arteries exposed to d-flow.
动脉僵硬度和壁面剪应力是心血管健康的重要决定因素，动脉僵硬度与心血管死亡率增加相关。低且振荡的壁面剪应力，即紊乱血流（d-flow），会促进动脉粥样硬化性动脉重塑，但d-flow与动脉僵硬度之间的关系尚不清楚。本研究的目的是确定d-flow在动脉僵硬中的作用，并发现d-flow使动脉僵硬的相关信号通路。
在雌雄年轻和老年小鼠的颈动脉中诱导产生d-flow。通过圆柱形双轴力学测试在体外对动脉僵硬度进行量化，并通过双功超声在体内进行量化，然后与80周龄小鼠未处理的颈动脉进行比较。对富含内皮细胞的RNA进行基因表达和通路分析，并通过免疫组织化学进行验证。在振荡和层流壁面剪应力条件下对信号通路进行体外测试。对来自d-flow区域和稳定血流区域的人体动脉进行体外测试，以验证动物模型的关键结果。
d-flow通过部分颈动脉结扎后胶原沉积诱导动脉僵硬，僵硬程度与80周龄小鼠未处理的颈动脉相似。内膜基因通路分析确定转化生长因子-β通路在这种动脉僵硬反应中起主要作用，但这归因于血小板反应蛋白-1（TSP-1）对促纤维化基因的刺激，而非转化生长因子-β的变化。在d-flow条件下的体外和体内测试确定了TSP-1激活转化生长因子-β在这些基因上调中的可能作用。与野生型颈动脉相比，TSP-1基因敲除动物对d-flow的动脉僵硬反应明显较小。暴露于d-flow的人体动脉中TSP-1和胶原基因表达的增加与我们模型中的情况相似。
TSP-1在剪切力介导的动脉僵硬中起关键作用，部分是通过TSP-1激活转化生长因子-β的促纤维化信号通路实现的。该通路中的分子靶点可能会带来新的治疗方法，以限制动脉僵硬以及暴露于d-flow的动脉中疾病的进展。
