hP-MSCs attenuate severe acute pancreatitis in mice via inhibiting NLRP3 inflammasome-mediated acinar cell pyroptosis.

BACKGROUND:Severe acute pancreatitis (SAP) is a serious gastrointestinal disease that is facilitated by pancreatic acinar cell death. The protective role of human placental mesenchymal stem cells (hP-MSCs) in SAP has been demonstrated in our previous studies. However, the underlying mechanisms of this therapy remain unclear. Herein, we investigated the regularity of acinar cell pyroptosis during SAP and investigated whether the protective effect of hP-MSCs was associated with the inhibition of acinar cell pyroptosis. METHODS:A mouse model of SAP was established by the retrograde injection of sodium taurocholate (NaTC) solution in the pancreatic duct. For the hP-MSCs group, hP-MSCs were injected via the tail vein and were monitored in vivo. Transmission electron microscopy (TEM) was used to observe the pyroptosis-associated ultramorphology of acinar cells. Immunofluorescence and Western blotting were subsequently used to assess the localization and expression of pyroptosis-associated proteins in acinar cells. Systemic inflammation and local injury-associated parameters were evaluated. RESULTS:Acinar cell pyroptosis was observed during SAP, and the expression of pyroptosis-associated proteins initially increased, peaked at 24 h, and subsequently showed a decreasing trend. hP-MSCs effectively attenuated systemic inflammation and local injury in the SAP model mice. Importantly, hP-MSCs decreased the expression of pyroptosis-associated proteins and the activity of the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome in acinar cells. CONCLUSIONS:Our study demonstrates the regularity and important role of acinar cell pyroptosis during SAP. hP-MSCs attenuate inflammation and inhibit acinar cell pyroptosis via suppressing NLRP3 inflammasome activation, thereby exerting a protective effect against SAP.