α1肾上腺素能受体激活抑制脓毒症诱导的心脏内皮ICAM-1和VCAM-1表达的分子机制研究

Sepsis-induced cardiac dysfunction is a common complication in septic patients, which is closely related to cardiac endothelial injury. However, there is no specific treatment towards sepsis-induced cardiac dysfunction. It has been demonstrated that the cardiac α1 adrenergic receptor (α1-AR) activation inhibited the endothelial injury markers ICAM-1 and VCAM-1 expression in the myocardium of septic mice. However, the molecular mechanism is unclear. Moreover, MAPKs/NF-κB and PI3K/Akt signaling pathways play an important role in maintaining endothelial function. Therefore, we hypothesize that activation of the α1-AR in cardiac endothelial cells inhibits the expression of ICAM-1 and VCAM-1 by regulating MAPKs/NF-κB and PI3K/Akt signaling pathways and improves the cardiac function in septic mice. In the present study, immunofluorescence staining, α1-AR antagonists, isolated heart perfusion and other methods were used in a sepsis model in vivo and vitro to clarify the mechanisms responsible for the α1-AR activation of cardiac endothelial cells in inhibiting the ICAM-1 and VCAM-1 expression, including the role of MAPKs/NF-κB and PI3K/Akt signaling pathways. These investigations will further explain the molecular mechanisms for α1-AR activation in cardiac endothelial cells in preventing the endothelial injury and cardiac dysfunction and provide new ideas for the treatment of septic patients with cardiac dysfunction.

心功能障碍是脓毒症病人常见的并发症，目前临床缺乏特异性治疗手段。心脏内皮细胞损伤与脓毒症心功能障碍的发生密切相关。我们前期研究发现，心脏α1肾上腺素能受体（α1-AR）激活可抑制脓毒症小鼠心脏内皮损伤标志物ICAM-1和VCAM-1的表达，但分子机制不清楚。MAPKs/NF-κB和PI3K/Akt信号通路在维持正常内皮功能中发挥重要作用，据此我们提出如下科学假说：α1-AR激活后通过调节MAPKs/NF-κB和PI3K/Akt信号通路来抑制心脏内皮ICAM-1和VCAM-1的表达，改善脓毒症小鼠心功能。本课题拟采用脓毒症模型，用免疫荧光定位、α1-AR阻断剂、离体心脏灌流等方法，通过体内外实验研究心脏内皮细胞α1-AR激活抑制ICAM-1和VCAM-1表达的机制，旨在阐明心脏内皮细胞α1-AR激活在抑制内皮细胞损伤及心脏功能障碍中的作用及其机制，为脓毒症心功能障碍的防治提供新的思路。

背景：有研究表明，特异性阻断内皮炎症反应中心环节核因子κB（NF-κB）可改善脓毒症多器官损伤。我们前期研究发现，苯肾上腺素（PE）可抑制脓毒症小鼠心脏内皮损伤标志物ICAM-1和VCAM-1的表达，但分子机制不清楚。本研究以MAPKs/NF-κB信号通路为切入点，进一步阐明PE在抑制心脏内皮细胞损伤及心功能障碍中的作用及机制，为脓毒症心功能障碍的防治提供新的思路。方法与内容：在动物实验中，随机分为4组：假手术组（Sham）、脓毒症模型组（CLP）、PE治疗组（CLP+PE）、PE对照组。主要观察指标：①小鼠存活率、心功能检测；血浆内皮损伤因子sICAM-1、sP-Selectin、sE-Selectin和PAI-1含量；ICAM-1、VCAM-1、iNOS、E-selectin蛋白和mRNA含量测定以及MAPK信号通路蛋白的表达；心肌组织转录组学分析。在细胞实验中，分为Control、LPS、LPS+PE、PE组，检测ICAM-1、VCAM-1、E-selectin、PKC以及MAPK-NF-κB信号通路蛋白含量；运用PKC阻断剂进行干预，进一步检测PE对LPS诱导的内皮细胞MAPK-NF-κB信号通路及ICAM-1、VCAM-1蛋白表达的影响。研究结果：①PE可明显提高脓毒症小鼠的生存率、改善脓毒症小鼠心脏的收缩功能、降低脓毒症小鼠血清及心肌组织中内皮炎症标志物的表达，降低脓毒症小鼠心脏组织TGF-β/Alox5AP基因表达。②PE可通过调节PKC/P38MAPK/NF-κB通路显著抑制LPS诱导的内皮细胞ICAM-1、VCAM-1的表达。科学意义：本研究初步明确了PE通过调节PKC/P38MAPK/NF-κB信号通路抑制内皮细胞炎症反应，从而减轻脓毒症心功能障碍，提高脓毒症小鼠存活率。初步揭示了苯肾上腺素防治脓毒症心功能障碍的机制。