Single-cell sequencing of pancreatic tissues of mice with acute pancreatitis under the background of normal diet and high-fat diet was compared

Background: Acute pancreatitis (AP) is a common severe digestive disorder, with severity linked to high-fat diets (HFD). HFD may exacerbate AP by promoting inflammation and altering gut microbiota. Astragalus polysaccharides (APS) possess anti-inflammatory properties, but it is unclear if APS supplementation can mitigate HFD's detrimental effects on AP by modulating gut microbiota. This study investigates the mechanisms by which APS improves HFD-induced AP exacerbation. In this study, C57BL/6 mice were fed HFD or a standard diet, with or without APS, for 12 weeks. AP was induced via intraperitoneal caerulein injection. Analyses included ELISA, Western blotting, histology, immunohistochemistry, immunofluorescence, single-cell RNA sequencing (scRNA-seq), 16S rRNA sequencing of gut microbiota, and short-chain fatty acid (SCFA) analysis to evaluate inflammation and cellular changes. Results: HFD significantly increased AP severity, indicated by elevated serum enzyme and pro-inflammatory cytokine levels, along with extensive pancreatic damage. Single-cell RNA sequencing (scRNA-seq) showed a notable rise in ICAM1+ neutrophils and activation of the NF-κB/necroptosis pathway in HAP mice. APS alleviated these effects by decreasing ICAM1+ neutrophil infiltration, downregulating the NF-κB pathway, and reducing necroptosis. Moreover, APS restored gut microbiota balance, significantly boosting Lactobacillus reuteri (L. reuteri) abundance and propionate (PA) levels. Treatments with L. reuteri and PA independently mitigated HFD-induced AP severity, indicating that APS's protective effects are microbiota-dependent. Conclusion: APS improves HFD-induced gut dysbiosis and intestinal barrier dysfunction by enriching L. reuteri and PA, effectively reducing AP exacerbation. Our findings highlight the gut-pancreas axis as a promising target for addressing AP severity.