Necroptosis Is an important Severity Determinant and Potential Therapeutic Target in Experimental Severe Pancreatitis

BACKGROUND & AIMS: Severe acute pancreatitis is characterized by acinar cell death and inflammation. Necroptosis is an aggressive and proinflammatory mode of cell death that can be prevented by necrostatin-1 administration or receptor-interacting protein kinase (RIP3) deletion. METHODS: Mouse pancreatic acinar cells were incubated with supramaximally stimulating concentrations of caerulein or submicellar concentrations of taurolithocholic acid-3-sulfate (TLCS), and necroptosis was inhibited by either addition of necrostatin or by RIP3 deletion. Cell death was quantitated using either lactate dehydrogenase leakage from acini or propidium iodide staining of nuclei. Necrosome formation was tracked and quantitated using cell fractionation or immunoprecipitation. Pancreatitis was induced in mice by retrograde intraductal infusion of TLCS or by repetitive supramaximal stimulation with caerulein. RESULTS: Necroptosis was found to be the most prevalent mode of acinar cell in vitro death and little or no apoptosis was observed. Acinar cell death was associated with necrosome formation and prevented by either necrostatin administration or RIP3 deletion. Both of these interventions reduced the severity of TLCS- or caerulein-induced pancreatitis. Delaying necrostatin administration until after pancreatitis already had been established did not prevent its ability to reduce the severity of TLCS-induced pancreatitis. CONCLUSIONS: Necroptosis is the predominant mode of acinar cell death in severe experimental mouse pancreatitis. The severity of pancreatitis can be reduced by administration of necrostatin, and necrostatin still can reduce the cell injury of pancreatitis even if it is administered after the disease already has been established. Inhibition of necroptosis may be an effective strategy for the treatment of severe clinical pancreatitis.