Department of Anesthesiology and Intensive Care Medicine, Eberhard Karls University, Tübingen, Germany.
Department of Pharmacology, Experimental Therapy and Toxicology, Institute for Experimental and Clinical Pharmacology and Pharmacogenomic, Eberhard Karls University, and Interfaculty Center of Pharmacogenomic and Drug Research, Wilhelmstrasse 56, 72074, Tübingen, Germany.
Basic Res Cardiol. 2024 Oct;119(5):717-732. doi: 10.1007/s00395-024-01057-x. Epub 2024 May 30.
Neutrophils are not only involved in immune defense against infection but also contribute to the exacerbation of tissue damage after ischemia and reperfusion. We have previously shown that genetic ablation of regulatory Gα proteins in mice has both protective and deleterious effects on myocardial ischemia reperfusion injury (mIRI), depending on which isoform is deleted. To deepen and analyze these findings in more detail the contribution of Gα proteins in resident cardiac vs circulating blood cells for mIRI was first studied in bone marrow chimeras. In fact, the absence of Gα in all blood cells reduced the extent of mIRI (22,9% infarct size of area at risk (AAR) Gnai2 → wt vs 44.0% wt → wt; p < 0.001) whereas the absence of Gα in non-hematopoietic cells increased the infarct damage (66.5% wt → Gnai2 vs 44.0% wt → wt; p < 0.001). Previously we have reported the impact of platelet Gα for mIRI. Here, we show that infarct size was substantially reduced when Gα signaling was either genetically ablated in neutrophils/macrophages using LysM-driven Cre recombinase (AAR: 17.9% Gnai2 LysM-Cre vs 42.0% Gnai2; p < 0.01) or selectively blocked with specific antibodies directed against Gα (AAR: 19.0% (anti-Gα) vs 49.0% (IgG); p < 0.001). In addition, the number of platelet-neutrophil complexes (PNCs) in the infarcted area were reduced in both, genetically modified (PNCs: 18 (Gnai2; LysM-Cre) vs 31 (Gnai2); p < 0.001) and in anti-Gα antibody-treated (PNCs: 9 (anti-Gα) vs 33 (IgG); p < 0.001) mice. Of note, significant infarct-limiting effects were achieved with a single anti-Gα antibody challenge immediately prior to vessel reperfusion without affecting bleeding time, heart rate or cellular distribution of neutrophils. Finally, anti-Gα antibody treatment also inhibited transendothelial migration of human neutrophils (25,885 (IgG) vs 13,225 (anti-Gα) neutrophils; p < 0.001), collectively suggesting that a therapeutic concept of functional Gα inhibition during thrombolysis and reperfusion in patients with myocardial infarction should be further considered.
中性粒细胞不仅参与抗感染的免疫防御，而且还促进缺血再灌注后组织损伤的恶化。我们之前的研究表明，在小鼠中敲除调节性 Gα 蛋白不仅对心肌缺血再灌注损伤（mIRI）具有保护作用，也具有损伤作用，具体取决于敲除的是哪种同工型。为了更详细地深入研究这些发现，我们首先在骨髓嵌合体中研究了 Gα 蛋白在驻留心肌细胞与循环血细胞中的作用对 mIRI 的影响。事实上，所有血细胞中 Gα 的缺失减少了 mIRI 的程度（风险区域面积的梗死大小（AAR）Gnai2→wt 为 22.9%，而 wt→wt 为 44.0%；p<0.001），而非造血细胞中 Gα 的缺失增加了梗死损伤（wt→Gnai2 为 66.5%，而 wt→wt 为 44.0%；p<0.001）。此前我们曾报道过血小板 Gα 对 mIRI 的影响。在这里，我们表明，当使用 LysM 驱动的 Cre 重组酶在中性粒细胞/巨噬细胞中遗传敲除 Gα 信号（AAR：17.9% Gnai2 LysM-Cre 比 42.0% Gnai2；p<0.01）或用针对 Gα 的特异性抗体选择性阻断 Gα 信号（AAR：19.0%（抗-Gα）比 49.0%（IgG）；p<0.001）时，梗死面积大大减少。此外，在基因修饰（PNCs：18（Gnai2；LysM-Cre）比 31（Gnai2）；p<0.001）和抗-Gα 抗体治疗（PNCs：9（抗-Gα）比 33（IgG）；p<0.001）的小鼠中，梗死区的血小板-中性粒细胞复合物（PNCs）数量也减少。值得注意的是，在血管再灌注前立即给予单次抗-Gα 抗体治疗，不影响出血时间、心率或中性粒细胞的细胞分布，即可实现显著的梗死限制作用。最后，抗-Gα 抗体治疗还抑制了人中性粒细胞的跨内皮迁移（IgG 为 25,885 个，抗-Gα 为 13,225 个；p<0.001），这表明在心肌梗死患者的溶栓和再灌注期间，应进一步考虑 Gα 功能抑制的治疗概念。
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