Serum amyloid A3 is required for caerulein-induced acute pancreatitis through induction of RIP3-dependent necroptosis.

Serum amyloid A (SAA) is an early and sensitive biomarker of inflammatory diseases, but its role in acute pancreatitis (AP) is still unclear. Here, we used a caerulein-induced mouse model to investigate the role of SAA in AP and other related inflammatory responses. In our study, we found that the expression of a specific SAA isoform, SAA3, was significantly elevated in a caerulein-induced AP animal model. In addition, SAA3-knockout (Saa3-/- ) mice showed lower serum levels of amylase and lipase, tissue damage and proinflammatory cytokine production in the pancreas compared with those of wild-type mice in response to caerulein administration. AP-associated acute lung injury was also significantly attenuated in Saa3-/- mice. In our in vitro experiments, treatment with cholecystokinin and recombinant SAA3 significantly induced necroptosis and cytokine production. Moreover, we found that the regulatory effect of SAA3 on acinar cell necroptosis was through a receptor-interacting protein 3 (RIP3)-dependent manner. Collectively, our findings indicate that SAA3 is required for AP by inducing an RIP3-dependent necroptosis pathway in acinar cells and is a potential drug target for AP.