M1 macrophage‐derived exosomes promote autoimmune liver injury by transferring long noncoding RNA H19 to hepatocytes

Abstract Exosomes mediate intercellular communication by transmitting active molecules. The function of long noncoding RNA (lncRNA) H19 in autoimmune liver injury is unclear. Concanavalin A (ConA)‐induced liver injury is well‐characterized immune‐mediated hepatitis. Here, we showed that lncRNA H19 expression was increased in the liver after ConA treatment, accompanied by increased exosome secretion. Moreover, injection of AAV‐H19 aggravated ConA‐induced hepatitis, with an increase in hepatocyte apoptosis. However, GW4869, an exosome inhibitor, alleviated ConA‐induced liver injury and inhibited the upregulation of lncRNA H19. Intriguingly, lncRNA H19 expression in the liver was significantly downregulated, after macrophage depletion. Importantly, the lncRNA H19 was primarily expressed in type I macrophage (M1) and encapsulated in M1‐derived exosomes. Furthermore, H19 was transported from M1 to hepatocytes via exosomes, and exosomal H19 dramatically induced hepatocytes apoptosis both in vitro and vivo. Mechanistically, H19 upregulated the transcription of hypoxia‐inducible factor‐1 alpha (HIF‐1α), which accumulated in the cytoplasm and mediated hepatocyte apoptosis by upregulating p53. M1‐derived exosomal lncRNA H19 plays a pivotal role in ConA‐induced hepatitis through the HIF‐1α–p53 signaling pathway. These findings identify M1 macrophage‐derived exosomal H19 as a novel target for the treatment of autoimmune liver diseases.