Exosomes Derived from Caerulein-Stimulated Pancreatic Acinar Cells Mediate Peritoneal Macrophage M1 Polarization and Pyroptosis via an miR-24-3p/MARCH3/NLRP3 Axis in Acute Pancreatitis.

OBJECTIVES: Acute pancreatitis (AP) has a high incidence of hospitalizations, morbidity, and mortality worldwide. A growing number of studies on AP pathogenesis are based on caerulein-induced experimental model, which simulates human AP in vivo. It has been demonstrated that both pancreatic acinar cells and peritoneal macrophages are involved in pancreatic inflammation and damage. However, their connection has not been well understood.

METHODS: A caerulein-induced AP model was established on the pancreatic acinar cell line AR42J. Rat macrophages were isolated from the peritoneal cavity. The effects of caerulein-induced pancreatic exosomes on the peritoneal macrophage and pancreas in vivo and in vitro were examined. The underlying molecular mechanism was investigated by exploring the regulatory role of downstream molecules.

RESULTS: We found that exosomes derived from caerulein-treated AR42J cells induced rat peritoneal macrophage M1 polarization and pyroptosis. miR-24-3p was upregulated in caerulein-stimulated exosomes, whereas the miR-24-3p inhibitor counteracted the effect of pancreatic exosomes on peritoneal macrophage M1 polarization and pyroptosis. Furthermore, miR-24-3p inhibited March3 expression, whereas MARCH3 mediated NLRP3 ubiquitination in rat peritoneal macrophages, which, in turn, contributed to the apoptosis, reactive oxygen species production, and inflammation in AR42J cells.

CONCLUSIONS: Exosomes derived from caerulein-stimulated pancreatic acinar cells mediate peritoneal macrophage M1 polarization and pyroptosis via an miR-24-3p/MARCH3/NLRP3 axis in AP.