Role of Exosomal Modulation of Macrophages in Liver Fibrosis.

Exosomes are 60-120 nm diameter double-membrane lipid organelles discharged by cells. Various studies have shown that exosomes exert multiple functions in both physical and diseased processes, such as intercellular information exchange, immune response, and disease progression. Repeated chronic injury to the liver often leads to inflammation and liver fibrosis (LF), a disorder that, if unchecked, may progress to cirrhosis, liver failure, portal hypertension, and even hepatocellular carcinoma. As an essential component of host innate immunity against pathogen invasion, macrophages play an important role in modulating inflammation homeostasis by finely tuning the polarization process of macrophages into either M1 or M2 subtypes in response to different microenvironments. As a critical contributor to the inflammation process, macrophages also play a complex and instrumental function in the progression of LF. This review focuses on recent advancements in the role of macrophage-associated exosomes implicated in LF, including macrophage-released exosomes and macrophage-targeted exosomes. In addition, the progress made in exosome-based antifibrotic therapy by in vivo and in vitro studies is also highlighted.