Neutrophil-targeted Mn3O4 nanozyme treats myocardial ischemia reperfusion injury by scavenging reactive oxygen species

Abstract Background: The core pathophysiological process of myocardial ischemia reperfusion injury (MIRI) is the excessive reactive oxygen species (ROS) production (including •O2-, H2O2, •OH) in the injured areas. Manganese tetroxide (Mn3O4) nanozymes are capable of scavenging multiple ROS, but whether they are applicable in MIRI is unclear. Rat IgG-modified liposomes can be specifically phagocytosed by activated neutrophils. Activated neutrophils can penetrate the vascular barrier and infiltrate into the inflamed myocardial tissue induced by MIRI. We synthesized IgG-Lip-Mn3O4 (rat IgG-modified liposomes encapsulated with Mn3O4 nanozyme). It is unclear whether they can be phagocytosed by activated neutrophils and then infiltrate into deep myocardial tissues to remove excess ROS. Methods: Fluorescent probe technique was used to test ROS scavenging ability of IgG-Lip-Mn3O4. Apoptosis and cell death were detected with regular staining kits. Flow cytometry and in vivo imaging system were used to evaluate the targeting ability of IgG-Lip-Mn3O4 on myocardial tissue. Serum inflammatory factors were measured with ELISA kits. Echocardiography was used to detected cardiac function. Pathological staining was used to detected scar size, cardiac fibrosis, and cardiac remodeling. Immunofluorescence was used to detect vascular regeneration and macrophage polarization. Results: Mn3O4 nanozyme can scavenge various ROS such as •O2-, •OH and exert therapeutic effects in MIRI. IgG-Lip-Mn3O4, specifically phagocytosed by activated neutrophils, can be carried to the deep injured areas by utilizing the chemotactic effect of activated neutrophils towards inflammation areas. IgG-Lip-Mn3O4 could remove excess ROS from the injured areas, reduce the release of inflammatory factors and increase the content of M2-phenotype macrophages. It also protected cardiomyocytes against apoptosis and decreased the infarction size. IgG-Lip-Mn3O4 not only decreased scar tissue accumulation and ventricular remodeling, but also promoted angiogenesis and restored cardiac function. In addition, IgG-Lip-Mn3O4 was biocompatible and did not cause organ toxicity. Conclusions: IgG-Lip-Mn3O4 can specifically reach the injured areas and remove a variety of ROS. By reducing inflammatory responses and apoptosis, IgG-Lip-Mn3O4 provided precise and effective treatment for MIRI.