[Mechanism of Sijunzi Decoction in treating chronic atrophic gastritis via "gut microbiota-ferroptosis" axis]

This study investigated the therapeutic efficacy of Sijunzi Decoction on chronic atrophic gastritis(CAG) in rats and its potential mechanism of action in mitigating gastric mucosal injury through the "gut microbiota-hepcidin-ferroptosis" pathway. Specific pathogen-free(SPF) grade male Wistar rats were randomly divided into a normal group, a model group, a positive drug vatacoenayme group, and low-, medium-, and high-dose Sijunzi Decoction groups. A CAG model was established using a composite modeling method combining multiple pathogenic factors with irregular feeding. Gut microbiota composition and functional changes were analyzed by 16S rRNA high-throughput sequencing. Hepcidin expression in gastric tissues was assessed by immunofluorescence. Western blot was performed to measure the expression of ferroportin 1(FPN1) and ferroptosis-related proteins, including glutathione peroxidase 4(GPX4) and solute carrier family 7 member 11(SLC7A11). The levels of ferrous iron(Fe~(2+)), malondialdehyde(MDA), superoxide dismutase(SOD), and glutathione peroxidase(GSH-Px) were determined by colorimetric assay. Histopathological alterations in gastric tissue were observed via hematoxylin-eosin(HE) staining. The 16S rRNA sequencing results indicated a significant gut microbiota dysbiosis in the model group compared to the normal group. The model group exhibited significant enrichment of Prevotella, Allobaculum, Bacteroides, Enterococcus, and members of Enterobacteriaceae, whereas the normal group was relatively enriched with Turicibacteraceae/Turicibacter, Roseburia, and Veillonellaceae. Following pharmacological intervention, the vitaminazyme group showed enrichment of Clostridiaceae and Bifidobacterium. Distinct microbial signatures were observed across different doses of Sijunzi Decoction: the low-dose group was enriched with Bacteroides, Prevotella, and Veillonellaceae; the medium-dose group was enriched in Turicibacter and Actinobacteria; and the high-dose group was enriched with Sutterella, Allobaculum, and Blautia. Overall, the microbiota structure in all treatment groups shifted back towards that of the normal group compared to the model group. Functional prediction indicated that Sijunzi Decoction could upregulate metabolic pathways related to the degradation of aromatic compounds. In gastric tissues, the model group exhibited significant iron overload, oxidative stress, and ferroptosis activation, manifested as elevated Fe~(2+) and MDA levels, reduced GSH-Px and SOD activities, upregulated hepcidin expression, and markedly downregulated FPN1 and the key ferroptosis proteins GPX4 and SLC7A11. Sijunzi Decoction intervention effectively reversed these changes, restored iron homeostasis and redox balance, significantly upregulated the expression of FPN1, GPX4, and SLC7A11, and notably ameliorated gastric mucosal atrophy, glandular structural damage, and inflammatory cell infiltration in CAG rats. In summary, Sijunzi Decoction may improve gastric tissue injury and oxidative stress in CAG by remodeling the structure and function of the gut microbiota, downregulating hepcidin expression, promoting iron export, and inhibiting ferroptosis.