Acinar cell NLRP3 inflammasome and gasdermin D (GSDMD) activation mediates pyroptosis and systemic inflammation in acute pancreatitis

Pyroptosis is a lytic form of pro-inflammatory cell death characterised as caspase 1 dependent with canonical NLRP3 inflammasome-induced gasdermin D (GSDMD) activation. We aimed to investigate the role of acinar pyroptotic cell death in pancreatic injury and systemic inflammation in AP.Pancreatic acinar pyroptotic cell death pathway activation upon pancreatic toxin stimulation in vitro and in vivo was investigated. Effects of pharmacological (NLRP3 and caspase-1 inhibitors), constitutive (Nlrp3-/- , Casp1-/- and Gsdmd-/- ) and acinar cell conditional (Pdx1Cre Nlrp3Δ/Δ and Pdx1Cre GsdmdΔ/Δ ) genetic inhibition on pyroptotic acinar cell death, pancreatic necrosis and systemic inflammation were assessed using mouse AP models (caerulein, sodium taurocholate and l-arginine). Effects of Pdx1Cre GsdmdΔ/Δ versus myeloid conditional knockout (Lyz2Cre GsdmdΔ/Δ ) and Gsdmd-/- versus receptor-interacting protein 3 (RIP3) inhibitor were compared in CER-AP.There was consistent pyroptotic acinar cell death upon pancreatic toxin stimulation both in vitro and in vivo, which was significantly reduced by pharmacological or genetic pyroptosis inhibition. Pdx1Cre GsdmdΔ/Δ but not Lyz2Cre GsdmdΔ/Δ mice showed significantly reduced pyroptotic acinar cell death, pancreatic necrosis and systemic inflammation in caerulein-AP. Co-application of RIP3 inhibitor on Gsdmd-/- mice further increased protection on caerulein-AP.This work demonstrates a critical role for NLRP3 inflammasome and GSDMD activation-mediated pyroptosis in acinar cells, linking pancreatic necrosis and systemic inflammation in AP. Targeting pyroptosis signalling pathways holds promise for specific AP therapy.