Abstract：
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 Gαi 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 Gαi2 proteins in resident cardiac vs circulating blood cells for mIRI was first studied in bone marrow chimeras. In fact, the absence of Gαi2 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 Gαi2 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 Gαi2 for mIRI. Here, we show that infarct size was substantially reduced when Gαi2 signaling was either genetically ablated in neutrophils/macrophages using LysM-driven Cre recombinase (AAR: 17.9% Gnai2fl/fl LysM-Cre+/tg vs 42.0% Gnai2fl/fl; p < 0.01) or selectively blocked with specific antibodies directed against Gαi2 (AAR: 19.0% (anti-Gαi2) 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 (Gnai2fl/fl; LysM-Cre+/tg) vs 31 (Gnai2fl/fl); p < 0.001) and in anti-Gαi2 antibody-treated (PNCs: 9 (anti-Gαi2) vs 33 (IgG); p < 0.001) mice. Of note, significant infarct-limiting effects were achieved with a single anti-Gαi2 antibody challenge immediately prior to vessel reperfusion without affecting bleeding time, heart rate or cellular distribution of neutrophils. Finally, anti-Gαi2 antibody treatment also inhibited transendothelial migration of human neutrophils (25,885 (IgG) vs 13,225 (anti-Gαi2) neutrophils; p < 0.001), collectively suggesting that a therapeutic concept of functional Gαi2 inhibition during thrombolysis and reperfusion in patients with myocardial infarction should be further considered.
摘要：
中性粒细胞不仅参与针对感染的免疫防御,而且有助于缺血和再灌注后组织损伤的恶化。我们先前已经表明，小鼠中调节性Gαi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，取决于哪个同工型被删除。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Gαi2蛋白在常驻心脏和循环血细胞中对mIRI的贡献。事实上,所有血细胞中不存在Gαi2会降低mIRI的程度（危险区域的梗死面积（AAR）Gnai2-/-→wtvs44.0％wt→wt；p<0.001），而非造血细胞中不存在Gαi2会增加梗死损伤（66.5％wt→Gnai2-/-vs44.0％wt→wt；p<0.001）。以前我们已经报道了血小板Gαi2对mIRI的影响。这里,我们发现,当使用LysM驱动的Cre重组酶(AAR:17.9%Glai2fl/flLysM-Cre+/tgvs42.0%Gna2fl/fl;p<0.01)或选择性阻断针对Gai2的特异性抗体(AAR:19.0%(抗4Gp))在嗜中性粒细胞/巨噬细胞中遗传消除Gαi2信号时,梗死面积显著减少此外,梗死区血小板-中性粒细胞复合物（PNC）的数量均减少，基因修饰(PNC:18(Glai2fl/fl;LysM-Cre+/tg)vs31(Glai2fl/fl);p<0.001)和抗Gαi2抗体处理(PNC:9(抗Gαi2)vs33(IgG);p<0.001)小鼠。值得注意的是，在血管再灌注前,单次抗Gαi2抗体攻击可达到显著的梗死限制效应,而不影响出血时间,心率或中性粒细胞的细胞分布。最后,抗Gαi2抗体治疗还抑制了人中性粒细胞的跨内皮迁移（25,885（IgG）对13,225（抗Gαi2）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Gαi2抑制的治疗概念。
