Temporal patterns and distribution of pyroptosis-related molecules and effects of human mesenchymal stem cells on pyroptosis following cerebral ischemia/reperfusion in rats

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.

Ischemia‒Reperfusion accelerates neointimal hyperplasia via IL-1β-mediated pyroptosis after balloon injury in the rat carotid artery

Background

Ischemia‒reperfusion (IR) is a pathological process that causes secondary damage to blood vessels. However, whether IR can further worsen neointima formation after balloon injury and the detailed mechanism are unclear.

Methods

An in vivo model of balloon injury to the rat carotid artery was established to study the effect of IR following balloon injury on neointima formation. Smooth muscle cells (SMCs) were isolated from rat aortas and exposed to hypoxia-reoxygenation to mimic the IR process in vitro. The in vitro cell model was used to investigate the mechanism of IR-mediated neointima formation after balloon injury, which was further confirmed in an in vivo rat model.

Results

IR aggravated neointima formation in the rat carotid artery 2 weeks after balloon injury compared with that observed in the absence of balloon injury (P < 0.001). Compared with that of normal SMCs in the rat carotid artery, the expression of IL-1β, a key proinflammatory cytokine associated with pyroptosis, was increased more than 3-fold in the IR-induced neointima (P < 0.0001) and contributed to the proliferation and migration of rat primary aortic SMCs (P < 0.0001). This process was alleviated by the antioxidant acetylcysteine (NAC), suggesting its partial dependence on intracellular ROS. In the rat model of IR following balloon injury in the carotid artery, the carotid artery that was locally transfected with AAV carrying sh-IL-1β or sh-caspase-1, which alleviated neointima formation, as indicated by a reduction in intima-media thickness in the rat carotid artery (P < 0.0001).

Conclusion

Our results suggested that IR could promote IL-1β production in SMCs in the carotid artery after balloon injury and aggravate neointimal hyperplasia, which was alleviated by silencing caspase-1/IL-1β signaling in SMCs in the carotid artery. These results suggest that IL-1β may be an effective target to combat IR-related neointima formation.