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针对感染的免疫防御，而且还导致缺血和再灌注后组织损伤的加剧。我们之前已经证明，小鼠中调节性 Gα _i蛋白的基因消融对心肌缺血再灌注损伤 (mIRI) 既有保护作用，也有有害作用，具体取决于删除的亚型。为了更详细地深化和分析这些发现，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都会降低 mIRI 的程度（危险区域梗死面积 (AAR) Gnai2 ^−/− → wt 为 22.9% ，而wt → wt 为 44.0%； p < 0.001），而非造血细胞中缺乏 Gα _i2会增加梗塞损伤（66.5% wt → Gnai2 ^−/− vs 44.0% wt → wt； p < 0.001）。之前我们报道过血小板 Gα _i2对 mIRI 的影响。在这里，我们发现，当使用 LysM 驱动的 Cre 重组酶在中性粒细胞/巨噬细胞中基因消除 Gα _i2信号传导时，梗塞面积大幅减小（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 ）对比49.0%（IgG）； p < 0.001）。 此外，梗塞区域中血小板-中性粒细胞复合物 (PNC) 的数量在两种转基因药物中均有所减少（PNC：18 ( Gnai2 ^fl/fl ; LysM-Cre ^{+ /tg} ) vs 31 ( Gnai2 ^fl/fl )； p < 0.001) 和抗 Gα _i2抗体处理的小鼠 (PNC: 9 (抗 Gα _i2 ) vs 33 (IgG); p < 0.001) 小鼠。值得注意的是，在血管再灌注前进行单一抗 Gα _i2抗体攻击即可实现显着的梗塞限制效果，且不会影响出血时间、心率或中性粒细胞的细胞分布。最后，抗 Gα _i2抗体治疗还抑制人中性粒细胞的跨内皮迁移（25,885 个（IgG）与13,225 个（抗 Gα _i2 ）中性粒细胞； p < 0.001），共同表明溶栓和再灌注期间功能性 Gα _i2抑制的治疗概念患有心肌梗塞的患者应进一步考虑。