Department of Anesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein Campus Luebeck, Luebeck, Germany.
Institute of Physiology, University of Luebeck, Luebeck, Germany.
Front Immunol. 2024 Jul 11;15:1426526. doi: 10.3389/fimmu.2024.1426526. eCollection 2024.
Complement-mediated damage to the myocardium during acute myocardial infarction (AMI), particularly the late components of the terminal pathway (C5-convertase and C5b-9), have previously been characterized. Unfortunately, only few studies have reported a direct association between dysregulated complement activation and endothelial function. Hence, little attention has been paid to the role of the anaphylatoxin C5a. The endothelial glycocalyx (eGC) together with the cellular actin cortex provide a vasoprotective barrier against chronic vascular inflammation. Changes in their nanomechanical properties (stiffness and height) are recognized as hallmarks of endothelial dysfunction as they correlate with the bioavailability of vasoactive substances, such as nitric oxide (NO). Here, we determined how the C5a:C5aR1 axis affects the eGC and endothelial function in AMI.
Samples of fifty-five patients with ST-elevation myocardial infarction (STEMI) vs. healthy controls were analyzed in this study. eGC components and C5a levels were determined via ELISA; NO levels were quantified chemiluminescence-based. Endothelial cells were stimulated with C5a or patient sera (with/without C5a-receptor1 antagonist "PMX53") and the nanomechanical properties of eGC quantified using the atomic force microscopy (AFM)-based nanoindentation technique. To measure actin cytoskeletal tension regulator activation (RhoA and Rac1) G-LISA assays were applied. Vascular inflammation was examined by quantifying monocyte-endothelium interaction via AFM-based single-cell-force spectroscopy.
Serum concentrations of eGC components and C5a were significantly increased during STEMI. Serum and solely C5a stimulation decreased eGC height and stiffness, indicating shedding of the eGC. C5a enhanced RhoA activation, resulting in increased cortical stiffness with subsequent reduction in NO concentrations. Monocyte adhesion to the endothelium was enhanced after both C5a and stimulation with STEMI serum. eGC degradation- and RhoA-induced cortical stiffening with subsequent endothelial dysfunction were attenuated after administering PMX53.
This study demonstrates that dysregulated C5a activation during AMI results in eGC damage with subsequent endothelial dysfunction and reduced NO bioavailability, indicating progressively developing vascular inflammation. This could be prevented by antagonizing C5aR1, highlighting the role of the C5a:C5a-Receptor1 axis in vascular inflammation development and endothelial dysfunction in AMI, offering new therapeutic approaches for future investigations.
在急性心肌梗死（AMI）期间，补体介导的心肌损伤，特别是末端途径的晚期成分（C5-转化酶和 C5b-9），此前已经得到了描述。不幸的是，只有少数研究报告了补体激活失调与内皮功能之间的直接关联。因此，人们对过敏毒素 C5a 的作用关注甚少。内皮糖萼（eGC）与细胞肌动蛋白皮质一起为慢性血管炎症提供了血管保护屏障。它们的纳米力学特性（硬度和高度）的变化被认为是内皮功能障碍的标志，因为它们与血管活性物质（如一氧化氮（NO））的生物利用度相关。在这里，我们确定了 C5a：C5aR1 轴如何影响 AMI 中的 eGC 和内皮功能。
本研究分析了 55 名 ST 段抬高型心肌梗死（STEMI）患者和健康对照组的样本。通过 ELISA 测定 eGC 成分和 C5a 水平；通过化学发光法定量 NO 水平。用 C5a 或患者血清（用/不用 C5a 受体 1 拮抗剂“PMX53”）刺激内皮细胞，并使用原子力显微镜（AFM）-基于纳米压痕技术定量 eGC 的纳米力学特性。应用 G-LISA 测定法测量肌动蛋白细胞骨架张力调节剂的激活（RhoA 和 Rac1）。通过 AFM 基于单细胞力谱法测定单核细胞-内皮细胞相互作用来检测血管炎症。
STEMI 期间血清中 eGC 成分和 C5a 的浓度显著升高。血清和仅 C5a 刺激降低了 eGC 的高度和硬度，表明 eGC 的脱落。C5a 增强了 RhoA 的激活，导致皮质硬度增加，随后 NO 浓度降低。在 C5a 和 STEMI 血清刺激后，单核细胞与内皮细胞的黏附都增强了。在用 PMX53 给药后，eGC 降解和 RhoA 诱导的皮质变硬以及随后的内皮功能障碍得到了缓解。
这项研究表明，AMI 期间补体的失调激活导致 eGC 损伤，随后内皮功能障碍和 NO 生物利用度降低，表明血管炎症的进展。通过拮抗 C5aR1 可以预防这种情况，这突显了 C5a：C5a 受体 1 轴在 AMI 中血管炎症发展和内皮功能障碍中的作用，为未来的研究提供了新的治疗方法。
