Metabolomics and 16S rDNA sequencing of intestinal flora reveal the regulation of Sparassis latifolia polysaccharides on splenic immune function in lead-exposed mice

Sparassis latifolia polysaccharides (SLPs) have immunomodulatory activity and lead excretion ability, but its regulatory mechanism through the gut microbiota-spleen axis has not been elucidated. In this study, spleen metabolomics and intestinal flora sequencing were combined to explore the regulatory mechanism of SLPs on spleen immune function in lead-exposed mice. The results showed that SLPs effectively reduced spleen lead content, alleviated spleen enlargement and oxidative stress. SLPs changed glycerophospholipid metabolism, increased lysophosphatidylcholine content and inhibited the expression of G2A, ERK2 and NF-kB genes and the phosphorylation of ERK2 and NF-kB in lead-exposed mice. Furthermore, SLPs inhibited potential intestinal pathogens such as Clostridium_sensu_stricto_1, Lachnospiraceae, Oscillospiraceae and Alistipes_indistinctus, which were positively correlated with phosphatidylethanolamine metabolites. In addition, SLPs reduced the spleen tissue damage of lead-exposed mice by co-housing, and reduced the relative abundance of Clostridium_sensu_stricto_1, Prevotellaceae, and RF39, which were positively correlated with spleen enlargement, and inhibited the expression of ERK2/NF-κB signaling pathway-related genes such as G2A, ERK2 and Fas. In summary, SLPs can reduce the relative abundance of pathogenic microorganisms by regulating the structure of intestinal flora, regulate the glycerophospholipid metabolism of spleen in lead-exposed mice, alleviate oxidative damage and inflammatory response, and restore spleen immune function.