A Novel Cargo Delivery System‐AnCar‐ExoLaIMTS Ameliorates Arthritis via Specifically Targeting Pro‐Inflammatory Macrophages

Abstract Macrophages are heterogenic phagocytic cells that play distinct roles in physiological and pathological processes. Targeting different types of macrophages has shown potent therapeutic effects in many diseases. Although many approaches are developed to target anti‐inflammatory macrophages, there are few researches on targeting pro‐inflammatory macrophages, which is partially attributed to their non‐s pecificity phagocytosis of extracellular substances. In this study, a novel recombinant protein is constructed that can be anchored on an exosome membrane with the purpose of targeting pro‐inflammatory macrophages via antigen recognition, which is named AnCar‐ExoLaIMTS. The data indicate that the phagocytosis efficiencies of pro‐inflammatory macrophages for different AnCar‐ExoLaIMTS show obvious differences. The AnCar‐ExoLaIMTS3 has the best targeting ability for pro‐inflammatory macrophages in vitro and in vivo. Mechanically, AnCar‐ExoLaIMTS3 can specifically recognize the leucine‐rich repeat domain of the TLR4 receptor, and then enter into pro‐inflammatory macrophages via the TLR4‐mediated receptor endocytosis pathway. Moreover, AnCar‐ExoLaIMTS3 can efficiently deliver therapeutic cargo to pro‐inflammatory macrophages and inhibit the synovial inflammatory response via downregulation of HIF‐1α level, thus ameliorating the severity of arthritis in vivo. Collectively, the work established a novel gene/drug delivery system that can specifically target pro‐inflammatory macrophages, which may be beneficial for the treatments of arthritis and other inflammatory diseases.