Modulating butyric acid-producing bacterial community abundance and structure in the intestine of immunocompromised mice with neutral polysaccharides extracted from Codonopsis pilosula

Codonopsis pilosula , an important medicinal and edible plant in traditional Chinese medicine, is used widely as a tonifying herb for various immunodeficiency diseases. A neutral polysaccharide (CPPs-D1N1) was purified from C. pilosula , composed of fructose and glucose in a molar ratio of 97.28:2.72, with an average molecular weight of 5.985 kDa. Structural analysis revealed a backbone composed of →1)-β-D-Fruf-(2 → units with some β-D-Fruf-(2 → linkages. In a murine immunosuppression model induced by cyclophosphamide injection, oral treatment with C. pilosula polysaccharide was administered, investigating changes in gut microbiota during therapy. The polysaccharide modulated serum immunoglobulins (Ig-G, Ig-M), cytokines (IL-2, IL-6, TNFα), and spleen and thymus indices in immunodeficient mice. Additionally, functional gene primer sequencing enrichment methods revealed alterations in abundance, diversity, and structure of butyrate-producing bacterial populations in the gut, with primary differential genera identified as Butyribacter , Rumanococcus , Dysosmobacter , and Ruseburia . This study provides in vivo evidence supporting the beneficial effects of C. pilosula polysaccharide oral therapy in improving gut microbiota, particularly butyrate-producing bacteria, during treatment of immunosuppressive diseases.