Evidence of honey-processed Astragalus polysaccharides improving intestinal immune function in spleen Qi deficiency mice integrated with microbiomics and metabolomics analysis

Background: Radix Astragali, commonly known as Astragalus, is a traditional medicinal and edible plant valued for its Qi-tonifying properties. The dosage form of Radix Astragali processed with honey, known as honey-processed Astragalus (HPA), shows improved Qi-tonifying efficacy as compared to the raw product. Polysaccharides are the main bioactive ingredients in its aqueous extract. This study used a multiomics approach integrating microbiomics and metabolomics to elucidate the Qi-tonifying mechanisms of honey-processed Astragalus polysaccharides (HAPS).

Results: HAPS-treated mice showed improved symptom scores, spleen and thymus indices, serum cytokines (tumor necrosis factor α, interleukin 1β) and intestinal mucosa secretory immunoglobulin A (SIgA) compared to the mice with spleen Qi deficiency. The analysis of gut microbiota indicated that HAPS regulated the relative abundance of Bacteroidetes, Bacteroides, Proteobacteria and Helicobacter, thereby improving intestinal flora dysbiosis in mice with spleen Qi deficiency. Eleven biomarkers in fecal metabolomics analysis were screened and identified, primarily associated with linoleic acid metabolism, sphingolipid metabolism, glycerophospholipid metabolism and biosynthesis of unsaturated fatty acids. Furthermore, comprehensive analyses demonstrated that HAPS regulates palmitic acid and sphingolipid metabolism by modulating the abundance of Bacteroidetes, which in turn increased the levels of intestinal mucosal SIgA and restored intestinal mucosal immune function in mice with spleen Qi deficiency.

Conclusion: Our findings revealed that HAPS is an essential active ingredient of HPA, and its Qi-tonifying mechanism is closely related to the improvement of intestinal immune function. These findings lay the foundation for the application of HAPS as an immunomodulatory agent in health and dietary foods. © 2024 Society of Chemical Industry.