BACKGROUND CRP (C-reactive protein) is a prototypical acute phase reactant. Upon dissociation of the pentameric isoform (pCRP [pentameric CRP]) into its monomeric subunits (mCRP [monomeric CRP]), it exhibits prothrombotic and proinflammatory activity. Pathophysiological shear rates as observed in aortic valve stenosis (AS) can influence protein conformation and function as observed with vWF (von Willebrand factor). Given the proinflammatory function of dissociated CRP and the important role of inflammation in the pathogenesis of AS, we investigated whether shear stress can modify CRP conformation and induce inflammatory effects relevant to AS. METHODS To determine the effects of pathological shear rates on the function of human CRP, pCRP was subjected to pathophysiologically relevant shear rates and analyzed using biophysical and biochemical methods. To investigate the effect of shear on CRP conformation in vivo, we used a mouse model of arterial stenosis. Levels of mCRP and pCRP were measured in patients with severe AS pre- and post-transcatheter aortic valve implantation, and the presence of CRP was investigated on excised valves from patients undergoing aortic valve replacement surgery for severe AS. Microfluidic models of AS were then used to recapitulate the shear rates of patients with AS and to investigate this shear-dependent dissociation of pCRP and its inflammatory function. RESULTS Exposed to high shear rates, pCRP dissociates into its proinflammatory monomers (mCRP) and aggregates into large particles. Our in vitro findings were further confirmed in a mouse carotid artery stenosis model, where the administration of human pCRP led to the deposition of mCRP poststenosis. Patients undergoing transcatheter aortic valve implantation demonstrated significantly higher mCRP bound to circulating microvesicles pre-transcatheter aortic valve implantation compared with post-transcatheter aortic valve implantation. Excised human stenotic aortic valves display mCRP deposition. pCRP dissociated in a microfluidic model of AS and induces endothelial cell activation as measured by increased ICAM-1 (intercellular adhesion molecule 1) and P-selectin expression. mCRP also induces platelet activation and TGF-β (transforming growth factor beta) expression on platelets. CONCLUSIONS We identify a novel mechanism of shear-induced pCRP dissociation, which results in the activation of cells central to the development of AS. This novel mechanosensing mechanism of pCRP dissociation to mCRP is likely also relevant to other pathologies involving increased shear rates, such as in atherosclerotic and injured arteries.

中文翻译：

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C 反应蛋白的剪切感应：连接主动脉瓣狭窄和炎症。


背景CRP （C 反应蛋白） 是一种典型的急性期反应物。在五聚体亚型 （pCRP [pentameric CRP]）解离成其单体亚基 （mCRP [monomeric CRP]） 后，它表现出促血栓形成和促炎活性。在主动脉瓣狭窄 （AS） 中观察到的病理生理剪切率会影响蛋白质构象和功能，如 vWF （血管性血友病因子） 所观察到的那样。鉴于解离的 CRP 的促炎功能以及炎症在 AS 发病机制中的重要作用，我们研究了剪切应力是否可以改变 CRP 构象并诱导与 AS 相关的炎症作用。方法 为了确定病理剪切速率对人类 CRP 功能的影响，对 pCRP 进行病理生理相关的剪切速率，并使用生物物理和生化方法进行分析。为了研究剪切对体内 CRP 构象的影响，我们使用了动脉狭窄的小鼠模型。测量经导管主动脉瓣植入前后重度 AS 患者的 mCRP 和 pCRP 水平，并调查因重度 AS 接受主动脉瓣置换手术的患者切除的瓣膜上是否存在 CRP。然后使用 AS 的微流体模型来概括 AS 患者的剪切速率，并研究 pCRP 及其炎症功能的这种剪切依赖性解离。结果 暴露于高剪切速率下，pCRP 解离成其促炎单体 （mCRP） 并聚集成大颗粒。我们的体外发现在小鼠颈动脉狭窄模型中得到进一步证实，其中人类 pCRP 的施用导致 mCRP 狭窄后沉积。 与经导管主动脉瓣植入术后相比，接受经导管主动脉瓣植入术的患者在经导管主动脉瓣植入术前与循环微泡结合的 mCRP 显著升高。切除的人狭窄主动脉瓣显示 mCRP 沉积。pCRP 在 AS 的微流控模型中解离并诱导内皮细胞活化，通过增加 ICAM-1 （细胞间粘附分子 1） 和 P-选择素表达来测量。mCRP 还诱导血小板活化和血小板上的 TGF-β （转化生长因子 β） 表达。结论 我们确定了一种剪切诱导的 pCRP 解离的新机制，这导致对 AS 发展至关重要的细胞的激活。pCRP 与 mCRP 解离的这种新颖的机械感应机制也可能与涉及剪切速率增加的其他病理有关，例如动脉粥样硬化和受伤的动脉。