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_i 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_i2 proteins in resident cardiac vs circulating blood cells for mIRI was first studied in bone marrow chimeras. In fact, the absence of Gα_i2 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_i2 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_i2 for mIRI. Here, we show that infarct size was substantially reduced when Gα_i2 signaling was either genetically ablated in neutrophils/macrophages using LysM-driven Cre recombinase (AAR: 17.9% Gnai2^fl/fl LysM-Cre^+/tg vs 42.0% Gnai2^fl/fl; p < 0.01) or selectively blocked with specific antibodies directed against Gα_i2 (AAR: 19.0% (anti-Gα_i2) 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^fl/fl; LysM-Cre^+/tg) vs 31 (Gnai2^fl/fl); p < 0.001) and in anti-Gα_i2 antibody-treated (PNCs: 9 (anti-Gα_i2) vs 33 (IgG); p < 0.001) mice. Of note, significant infarct-limiting effects were achieved with a single anti-Gα_i2 antibody challenge immediately prior to vessel reperfusion without affecting bleeding time, heart rate or cellular distribution of neutrophils. Finally, anti-Gα_i2 antibody treatment also inhibited transendothelial migration of human neutrophils (25,885 (IgG) vs 13,225 (anti-Gα_i2) neutrophils; p < 0.001), collectively suggesting that a therapeutic concept of functional Gα_i2 inhibition during thrombolysis and reperfusion in patients with myocardial infarction should be further considered.

中性粒细胞不仅参与对感染的免疫防御，还有助于缺血和再灌注后组织损伤的加剧。我们之前已经表明，小鼠调节性 Gα 蛋白的遗传消融对心肌缺血再灌注损伤 （mIRI） 具有保护和有害作用，具体取决于删除的亚型。为了更详细地加深和分析这些发现，首先在骨髓嵌合体中研究了 Gα_i2 蛋白在常驻心脏血细胞与循环血细胞中对 mIRI 的贡献。事实上，所有血细胞中缺乏 Gα_i2 降低了 mIRI 的范围（22,9% 梗死风险区域大小 （AAR） Gnai2 ^{- /-} → wt 对 44.0% wt → wt;p < 0.001），而非造血细胞中 Gα_i2 的缺失增加了梗死损伤（Gnai2 → 66.5% wt ^{- /-} vs 44.0% wt → wt;p < 0.001）。之前我们已经报道了血小板 Gα_i2 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/巨噬细胞中对 Gα_i2 信号传导进行遗传消融时，梗死面积显着减小（AAR：17.9% Gnai2^fl/fl LysM-Cre^+/tg vs 42.0% Gnai2^fl/fl;p < 0.01） 或用针对 Gα_i2 的特异性抗体选择性阻断 （AAR： 19.0% （抗 Gα_i2） vs 49.0% （IgG）;p < 0.001）。 此外，在转基因 （PNC： 18 （Gnai2^fl/fl;LysM-Cre ^{+ / tg}） vs 31 （Gnai2^fl/fl）;p < 0.001） 和抗 Gα_i2 抗体处理 （PNC： 9 （抗 Gα_i2） vs 33 （IgG）;p < 0.001） 小鼠。值得注意的是，在血管再灌注前立即进行单次抗 Gα_i2 抗体攻击可达到显著的梗死限制作用，而不会影响出血时间、心率或中性粒细胞的细胞分布。最后，抗 Gα_i2 抗体治疗还抑制了人中性粒细胞的跨内皮迁移 （25,885 （IgG） vs 13,225 （抗 Gα_i2） 中性粒细胞;p < 0.001），共同表明应进一步考虑心肌梗死患者溶栓和再灌注过程中功能性 Gα_i2 抑制的治疗概念。