Luzhou-Feier powder reduces inflammatory response and improves intestinal immune barrier in rats with severe acute pancreatitis

Inhibition of circulating exosomes release with GW4869 mitigates severe acute pancreatitis-stimulated intestinal barrier damage through suppressing NLRP3 inflammasome-mediated pyroptosis

Intestinal barrier dysfunction frequently occurs as a complication in cases of severe acute pancreatitis (SAP); however, no effective therapeutic methods are available because the precise mechanism remains obscure. Recent research has elucidated the role of circulating exosomes in the progression of SAP. Therefore, the present study explored whether inhibiting circulating exosomes release would improve intestinal barrier injury triggered via SAP and investigated the possible underlying mechanism. In vivo, we found that circulating exosomes release exhibited a considerable increase in SAP rats than in SO rats, and GW4869, a suppressor of exosomes release, significantly decreased exosomes release in SAP rats. We also observed that GW4869 suppressed NLRP3 inflammasome-mediated pyroptosis within the intestine and alleviated intestinal barrier injury within SAP. Moreover, the inflammatory response and remote organ (kidney and lung) injury associated with SAP improved after GW4869 treatment. In vitro, we confirmed that depletion of exosomes with GW4869 could partially abolish the destructive effects of SAP rat plasma on the viability and barrier function of IEC-6 cells. In summary, our findings show that the suppression of the release of circulating exosomes effectively inhibits the process of pyroptosis mediated by the NOD-like receptor protein 3 (NLRP3) inflammasome and, therefore, mitigates intestinal barrier dysfunction in SAP, suggesting that circulating exosomes may be a potential target for treating SAP.

Dynamic Monitoring of Immunoinflammatory Response Identifies Immunoswitching Characteristics of Severe Acute Pancreatitis in Rats

Background

Immune dysfunction is the main characteristic of severe acute pancreatitis (SAP), and the timing of immune regulation has become a major challenge for SAP treatment. Previous reports about the time point at which the immune status of SAP changed from excessive inflammatory response to immunosuppression (hypo-inflammatory response) are conflicting.

Purposes

The aims of this study are to explore the immunological dynamic changes in SAP rats from the perspective of intestinal mucosal immune function, and to determine the immunoswitching point from excessive inflammatory response to immunosuppression.

Methods

Retrograde injection of sodium taurocholate into the pancreaticobiliary duct was applied to establish a SAP model in rats. The survival rate and the activities of serum amylase and pancreatic lipase in SAP rats were measured at different time points after model construction. The pathological changes in the pancreas and small intestines were analyzed, and the levels of intestinal pro- and anti-inflammatory cytokines and the numbers of intestinal macrophages, dendritic cells, Th1, Th2, and T regulatory cells were assessed. Meanwhile, the SAP rats were challenged with Pseudomonas aeruginosa (PA) strains to simulate a second hit, and the levels of intestinal inflammatory cytokines and the numbers of immune cells were analyzed to confirm the immunoswitching point.

Results

The time periods of 12–24 h and 48–72 h were the two death peaks in SAP rats. The pancreas of SAP rats showed self-limiting pathological changes, and the switching period of intestinal cytokines, and innate and adaptive immunity indexes occurred at 24–48 h. It was further confirmed that 48 h after SAP model construction was the immunoswitching point from excessive inflammatory response to immunosuppression.

Conclusion

The SAP rats showed characteristics of intestinal mucosal immune dysfunction after model construction, and the 48th h was identified as the immunoswitching point from excessive inflammatory response to immunosuppression. The results are of great significance for optimizing the timing of SAP immune regulation.