Differential and complementary effects of Baizhu and Fuling on spleen deficiency syndrome by regulating...

Atractylodes macrocephala Koidz. (commonly known as Baizhu, BZ) and Poria cocos (Schwan.) Wolf. (referred to as Fuling, FL) are frequently employed in the treatment of spleen deficiency syndrome (SDS) owing to their spleen-tonifying and dampness-eliminating properties. The combination of the two herbs, referred to as the BZ-FL herb pair, exhibited complementary and enhancing effects. Nevertheless, the distinct and complementary mechanisms and effects of BZ and FL individually remain inadequately understood.

This study aimed to investigate the differential and complementary effects and underlying mechanisms of BZ and FL on SDS.

The chemical components in BZ, FL, and the BZ-FL herb pair were qualitatively and quantitatively analyed using UHPLC-Q Exactive HF-X and UPLC-MS technique. SDS model rats were established by a combination of dietary and fatigue-inducing methods and then treated with BZ, FL, and the BZ-FL herb pair. In order to elucidate the effects on gastrointestinal motility, immune function, and water metabolism, the concentrations of gastrointestinal hormones, low-density lipoprotein, high-density lipoprotein, total cholesterol, serum protein levels, and albumin were measured. Additionally, the levels of IL-2, IgA, IL-4, IgG, and IFN-γ in colon tissue were quantified utilizing enzyme-linked immunosorbent assay (ELISA) and biochemical assays. Pathological changes were examined using hematoxylin and eosin staining, while immunofluorescence was used to measure the levels of the intestinal barrier proteins and aquaporins (Aqps) in colonic tissues. The levels of Aqps and cAMP/PKA/CREB signaling pathway were detected in colon and kidney tissues using western blot analysis. Untargeted metabolomics was used to analyze the serum and feces metabolic profile. The 16S rRNA gene high-throughput sequencing was performed to detect the gut microbiota composition in fecal samples.

The quantification of chemical components revealed that BZ significantly enhanced the dissolution of triterpene acids from FL. BZ, FL, and the BZ-FL herb pair effectively mitigated SDS by modulating gastrointestinal hormones, kidney and colon Aqps, and protein expression within the cAMP/PKA/CREB signaling pathway, while also enhancing intestinal barrier integrity. Serum metabolomics analysis demonstrated that BZ influenced bile acid biosynthesis, FL affected the citrate cycle and glycerophospholipid metabolism, and the BZ-FL herb pair impacted all these pathways. Gut microbiota analysis indicated that the efficacy of the BZ-FL herb pair in ameliorating SDS was associated with a preserved gut microbiome, characterized by the relative abundance of microbial taxa such as Escherichia-Shigella, Kurthia, and UCG-005. Fecal metabolomics analysis indicated that the BZ-FL herb pair synergistically enhances and complements each other by influencing metabolites in butanoate, arginine and proline, starch and sucrose, cysteine and methionine, purine, and propanoate metabolism. Moreover, correlation and comprehensive analyses identified a robust association among SDS phenotypes, serum metabolites, fecal metabolites, and microbial genera. In addition, the BZ-FL herb pair and BZ alone exhibited significantly greater regulatory effects on gastrointestinal function-related indicators compared to FL.

This study presents initial evidence of the differential and complementary effects of BZ and FL, analyzing their chemical compositions and their influence on water-fluid metabolism and the microbiota-gut-metabolites axis in SDS. These findings reflect the rationality and scientific basis of the compatibility theory. The study identified potential mechanisms of the BZ-FL herb pair in treating SDS, providing a reference for future research and clinical applications.