Targeting G?i2 in neutrophils protects from myocardial ischemia-reperfusion injury
KUSHWAHA R. 1, LEISS V. 1, KÖHLER D. 2, WEIGELIN B. 3,4, NÜRNBERG B. 1, BEER-HAMMER S. 1,4
1 Department of Pharmacology and Experimental Therapy and Toxicology, Institute for Experimental and Clinical Pharmacology and Pharmacogenomic, Eberhard Karls University, and Interfaculty Center of Pharmacogenomic and Drug Research, Tübingen, Germany; 2 Department of Anesthesiology and Intensive Care Medicine, Eberhard Karls University, Tübingen, Germany; 3 Department of Preclinical Imaging and Radiopharmacy, Multiscale Immunoimaging, Eberhard Karls University, Tübingen, Germany; 4 Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University, Tübingen, Germany
Objective: To investigate the role of Gαi2 in neutrophils and to propose Gαi2 as a potential target for pharmacological treatment of myocardial ischemia-reperfusion injury (mIRI)
Background: The importance of Gαi2 in platelets on the impact of mIRI has been investigated, but its functional role in neutrophils remains unclear. Among the first cells recruited to sites of tissue damage, Neutrophils contribute to wound healing and potential damage to healthy tissue. Their involvement exacerbates tissue damage and inflammation after ischemia and reperfusion. In animal studies, the number of platelet-neutrophil complexes (PNCs) in ischemic myocardial tissue correlated with the extent of mIRI. However, the bloodstream's PNCs influence neutrophil activity and migration into ischemic tissue. Therefore, PNCs contribute significantly to mIRI, which is also reflected in increased circulating PNCs in the blood of patients with acute MI.
Method: To determine the extent to which Gαi proteins in neutrophils contribute to the protection or exacerbation of mIRI, neutrophil-specific deletion of Gαi proteins was achieved by the LysM-Cre method. To study the effects of Gαi proteins on neutrophil migration and PNC formation, 3D collagen matrix-based in vitro models and live cell microscopy were used.
Results: Genetic ablation of Gαi proteins has different effects on mIRI in mice depending on the isoform deleted. Both genetic targeting of Gαi2 restricted to neutrophils and therapeutic blockade of Gαi2 signalling in neutrophils with antibodies directed against Gαi2 reduced infarct size in our mouse model of mIRI, indicating a crucial role of Gαi2 in mIRI. Remarkably, the therapeutic benefit was achieved with a single antibody intervention immediately before reperfusion. The number of stained PNCs in the histological sections of the hearts of the Gαi2 knockout or Gαi2-antibody-treated mice was significantly reduced.
Conclusion: Inactivation of Gαi2 may be considered an acute therapy for myocardial infarction in humans.