Ganoderic Acid A Alleviates Severe Acute Pancreatitis by Modulating Gut Homeostasis and Inhibiting TLR4-NLRP3 Signaling

Background Severe acute pancreatitis (SAP) manifests as a critical state marked by acute abdominal symptoms, often associated with intestinal barrier dysfunction, exacerbating SAP retroactively. Ganoderic acid A (GAA) demonstrates anti-inflammatory properties in various inflammatory disorders. Nonetheless, its potential therapeutic impact on SAP and the underlying mechanisms remain unexplored. Methods In both wild-type and TLR4^-/- mice, experimental SAP was induced using caerulein plus lipopolysaccharide. Caerulein injections were administered intraperitoneally following 7 days of intragastric GAA administration. Additionally, the potential mechanisms by which GAA ameliorates SAP were further investigated using fecal microbiota transplantation and TLR4-overexpressing IEC-6 cells. Results We observed that GAA treatment significantly ameliorated serum levels of amylase, lipase, and pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) in SAP mice. Pretreatment with GAA mitigated pathological injuries and reduced M1 macrophage and neutrophil infiltration in pancreatic or ileal tissues. Additionally, GAA treatment down-regulated TLR4-MAPK/NF-κB signaling and NLRP3 inflammasome activation in the pancreatic and ileal tissues of SAP mice. The results further revealed that the gavage of GAA decreased bacterial translocation (Escherichia coli and EUB338), repaired intestinal barrier dysfunction (ZO-1, occludin, DAO, and FITC), increased lysozyme and MUC2 expression, and raised the levels of short-chain fatty acids. Analysis of the gut microbiome showed that the beneficial effects of GAA treatment were associated with improvements in pancreatitis-associated gut microbiota dysbiosis, characterized by notable increases in α-diversity and the abundance of probiotics such as Akkermansia, GCA-900066575, and Parvibacter. Fecal transplantation experiments further confirmed that GAA exerts protective effects by modulating intestinal flora. The protective role of GAA in intestinal and pancreatic injuries is mediated by the inhibition of TLR4 signaling, as further evidenced in TLR4-deficient mice and TLR4-overexpressed IEC-6 cells. The results of docking indicated that GAA interacts with TLR4 via a hydrophobic interaction. Conclusions The study demonstrates that GAA significantly alleviates SAP through its anti-inflammatory and antioxidant capacities, as well as by restoring intestinal homeostasis, thereby providing insights into novel treatments for SAP.