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-?B/necroptosis pathway in HAP mice. APS alleviated these effects by decreasing ICAM1+ neutrophil infiltration, downregulating the NF-?B 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. Overall design: C57BL/6 mice were fed a high-fat diet or a standard diet with or without APS for 12 weeks. Acute pancreatitis was induced by intraperitoneal injection of caerulein (50 ug/kg), once per hour for a total of 12 times. Then, pancreatic tissues from each group were taken out and subjected to 10x single-cell sequencing. The groups included normal control group (NC), acute pancreatitis group induced by normal diet (AP), high-fat diet group (HFD), and acute pancreatitis group induced by high-fat diet (HAP). Astragalus polysaccharides were added or not added to AP mice on a high-fat diet to observe the therapeutic effect of astragalus polysaccharides.