High-entropy alloy nanozyme ROS biocatalyst treating tendinopathy via up-regulation of PGAM5/FUNDC1/GPX4 pathway

Tendinopathy is a common and complex musculoskeletal disorder, unfortunately current clinical strategies for tendinopathy have low therapeutic efficacy because of complicated pathogenesis. Oxidative stress is considered as the major cause of tendinopathy as well as the important target, but still lacking ideal antioxidant solution. To this end, an efficient reactive oxygen species (ROS) biocatalyst, PtIrRuRhCu high-entropy alloy nanozyme (HEANZ), has been designed for treatment of tendinopathy. The non-ionic block copolymer (polyvinyl pyrrolidone) coated PtIrRuRhCu HEANZ with size of ~ 4.0 nm exhibits good biocompatibility and multiple enzyme-like antioxidant activity (including peroxidase, catalase and superoxide dismutase (SOD)-like) to modulate ROS. The therapeutic efficacy of PtIrRuRhCu HEANZ in tendinopathy has been systematically demonstrated in vitro and in vivo. PtIrRuRhCu HEANZ can alleviate the t-Butyl hydroperoxide (TBHP) stimulated tendinopathy by clearing ROS, reducing inflammation and restoring mitochondrial autophagy. Using phosphoglycerate mutase family member 5 (PGAM5) siRNA and FUN14 domain containing protein 1 (FUNDC1) siRNA for intervention, we clearly revealed that PtIrRuRhCu HEANZ promots mitochondrial autophagy through upregulating the PGAM5/FUNDC1/glutathione peroxidase 4 (GPX4) axis. This study provides a nanozyme strategy for the antioxidant treatment of tendinopathy and provides insights into the therapeutic mechanism.