Role of tumor necrosis factor receptor‑associated factor 6 in pyroptosis during acute pancreatitis

Abstract

Acute pancreatitis (AP) is hypothesized to be related to the activation of an inflammatory response induced by pyroptosis. The aim of the present study was to investigate the potential role of tumor necrosis factor receptor-associated factor 6 (TRAF6) in pyroptosis in an AP rat model and the human pancreatic ductal epithelial HPDE6C7 cell line. In vivo, AP was induced by intraperitoneal injection of caerulein (CAE) in rats. The rats were sacrificed at 24 or 48 h after the final CAE injection. In vitro, HPDE6C7 cells were treated with CAE for 12, 24 and 48 h. Moreover, TRAF6 was overexpressed and treated with CAE for 48 h. Histopathological changes of pancreatic, serum and supernatant inflammatory cytokines and pyroptosis-related mRNA and protein expression levels were determined by histopathological scores, ELISA, reverse transcription-quantitative PCR and western blotting. In addition, pyroptosis morphological changes were also determined by Hoechst/PI staining in HPDE6C7 cells. Results showed that AP was observed in the CAE-induced rat model, and that serum IL-1β and IL-18 levels, and TRAF6, NLR pyrin domain containing 3 (NLRP3), caspase-1 and caspase-3 mRNA and protein expression levels were increased. Similar in HPDE6C7 cells, CAE treatment caused supernatant IL-1β level, NLRP3 and caspase-1 mRNA expression levels to significantly increase. After TRAF6 overexpression and CAE treatment, supernatant IL-1β level, caspase-1 protein expression level, and NLRP3 and caspase-3 mRNA and protein expression levels were also significantly increased. Furthermore, cells exhibited red fluorescence in Hoechst/PI staining, which can be used as a method of detecting pyroptosis activation. The results also showed that the red fluorescence was stronger after CAE treatment or TRAF6 overexpression plus CAE treatment. In conclusion, TRAF6 and caspase-1/3 signaling pathways were involved in the pathogenesis of CAE-induced AP in rats. Pyroptosis was activated by CAE and TRAF6 overexpression via the caspase-1/3 signaling pathways in HPDE6C7 cells.

Inhibition of TRAF6 improves hyperlipidemic acute pancreatitis by alleviating pyroptosis in vitro and in vivo rat models

“…Subsequently, we investigated whether regulating TRAF6 affects HTG-AP via the pyroptosis pathway, which would indicate the involvement of TRAF6 in the pathogenesis of HTG-AP. First, this finding is consistent with a previous study in which TRAF6 was found highly-expressed in both in vitro and in vivo AP and HTG-AP models, especially in HTG-AP groups [ 24 ]. Next, the TRAF6 gene was knocked down by siRNA-transfection in pancreatic acinar cells according to the most significant knockout efficiency in previous study [ 44 ].…”

“…Hence, we conducted a series of experiments to determine the function and underlying mechanism of participation of TRAF6 in pyroptosis during AP. In our previous studies, we found high expression of TRAF6 in cerulein-induced AP in vivo, and overexpression of TRAF6 gene was found to activate pyroptosis to induce AP in vitro [ 24 ]. Therefore, we hypothesized that TRAF6 may mediate cerulein-induced HTG-AP by regulating pyroptosis.…”

Gelsolin inhibits autophagy by regulating actin depolymerization in pancreatic ductal epithelial cells in acute pancreatitis

“…However, high concentrations of pancreatitis-inducing factors reverse these effects and impair PACs and PDECs ( 13 - 16 ). In our previous studies, AP was mimicked in PDECs in vitro using CAE and led to pyroptosis and barrier function impairment, in line with the results in a rat model of AP ( 17 - 19 ). However, the role of autophagy in this in vitro model has not been determined.…”

Gelsolin impairs barrier function in pancreatic ductal epithelial cells by actin filament depolymerization in hypertriglyceridemia‑induced pancreatitis in vitro

“…Previous studies have reported that barrier disfunction in PDECs is a major contributor to the occurrence of pancreatitis ( 6-9 ). Our previous study revealed that the synthetic cholecystokinin analogue caerulein (CAE) induced AP in the human pancreatic ductal epithelial cell line HPDE6-C7( 10 ). In addition, high-fat diet-derived FFAs can impair intestinal epithelial cell permeability ( 11-13 ); nonetheless, the effect of HTG on PDECs in AP is incompletely understood.…”