Targeting Ferroptosis By Mn₃O₄ Nanoparticles Alleviates Acute Liver Injury

Ferroptosis is a novel type of cell death defined by Brent R.Stckwell and colleagaes in 2012.It is caused by lipid peroxidation catalyzed by intracellular bioactive iron.Increasing evidences have emerged that ferroptosis plays an important regulatory role in the occurrence and progression of various diseases.For example,liver cells exhibit the main characteristics of ferroptosis during acute liver injury.Targeted regulation of ferroptosis holds a great promise for pathological research and clinical treatment of these diseases.As a substitute for"natural enzyme",nanozyme has been widely used in biomedicine because of their advantages of high stability,low price and targeted modification.Many nanozyme possess good scavenging activity of reactive oxygen species,but there has not been any report about the effect of nanozyme on liver injury by regulating ferroptosis.In this study,an ultra-small poly（acrylic）acid coated Mn₃O₄ nanoparticles（PAA@Mn₃O₄-NPs,PMO）was innovatively synthesized,which could effectively scavenge broad-spectrum reactive oxygen species,inhibit ferroptosis,and relieve acute liver injury.The main results are as follows:1)PMO is a nanoparticles with high reactive oxygen scavenging ability.The PMO was synthesized from hydrated manganese sulfate and polyacrylic acid in one pot in an autoclave,and the PMO was detected as 6.1±2.2 nm nanoparticles with efficient reactive oxygen species scavenging ability.2)PMO effectively counteracts ferroptosis.In the ferroptosis sensitive cell line MEF,PMO significantly inhibited the cell death induced by ferroptosis inducers RSL3 and Erastin,and increased levels of intracellular Lipid ROS,ROS and bioactive iron.3)The lysosome-enriched PMO restrains ferritinophagy.Confocal scaning suggests that PMO is enriched in lysosome after uptake.It was detected that the expression of ferritin and its co-localization with lysosomes increased in cells treated with RSL3 and Erastin,activation of ferritinophagy,but the PMO can effectively inhibit ferritinophagy,and reduced the iron content in lysosomes.4)PMO shows good biocompatibility.After intravenously injected PMO,serum and tissue samples were collected at different time points,and it was found that PMO did not change the histomorphologic characteristics of major organs in mice,and the serum markers related to major organ injury did not change significantly.5)PMO alleviate APAP-induced acute liver injury.Intraperitoneal injection of APAP can induce acute liver injury in mice,while injection of PMO can significantly reduce the levels of serum ALT and AST,and reduce the APAP-induced hepatocyte necrosis.Further determination of ferroptosis indexes in liver of mice showed that the levels of 4-HNE,MDA,8-OHd G and FTH protein were significantly decreased after injection of PMO.It proved that PMO could alleviate acute liver injury by inhibiting ferroptosis.In conclusion,the results of this study revealed that PMO nanozyme can effectively alleviate APAP-induced acute liver injury by removing reactive oxygen species,reducing ferritin autophagy,inhibiting ferroptosis.This project provides a theoretical basis for the clinical treatment of ferroptosis related diseases and promotes the development and application of nanozyme in the biomedical field.