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

BACKGROUND AND AIMS Severe acute pancreatitis is characterized by acinar cell death and inflammation. Necroptosis is an aggressive and pro-inflammatory mode of cell death that can be prevented by necrostatin-1 administration or RIP3 deletion. METHODS Mouse pancreatic acinar cells were incubated with supramaximally stimulating concentrations of caerulein or sub-micellar concentrations of TLCS and necroptosis was inhibited by either addition of necrostatin or by RIP3 deletion. Cell death was quantitated using either LDH leakage from acini or PI 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 had already been established could still 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 that necrostatin can still reduce the cell injury of pancreatitis even if it is administered after the disease has already been established. Inhibition of necroptosis may be an effective strategy for the treatment of severe clinical pancreatitis.