Research Data

Low molecular weight (6.5 kDa) glycyrrhiza polysaccharide (GP) shows a good immunomodulatory activity, however, its regulatory mechanism is still unclear. Using cyclophosphamide (CTX)-induced immunosuppressed mice as model, GP was verified to be able to reverse the CTX-induced intestinal structure damage. GP could increase the number of goblet cells, CD4+, CD8+ T lymphocytes and mucins, especially maintain the balance of Helper T lymphocyte 1/ Helper T lymphocyte 2 (Th1/Th2). Moreover, GP could alleviate immunosuppression through down-regulating extracellular regulated protein kinases/p38/nuclear factor kappa-Bp50 (ERK/p38/NF-κBp50) pathways, increasing short-chain fatty acids (SCFAs) level and secretion of cytokines such as interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-2 (IL-2), interleukin-10 (IL-10), interleukin-22 (IL-22), transforming growth factor-β3 (TGF-β3) and immunoglobulin M (IgM), immunoglobulin M (IgG) and Secretory immunoglobulin A (SIgA). The treatment of GP increased the total species and diversity of intestinal microbiota. Notably, immunoregulation of GP is closely related to the composition and diversity of intestinal microbiota. Microbiota analysis indicated that GP promoted the proliferation of beneficial bacteria such as Muribaculaceae_unclassified, Alistipes, Lachnospiraceae_NK4A136_group, Bacteroides, Ligilactobacillus and Clostridia_vadinBB60_group, conversely reduced the abundance of Proteobacteria and CTX-derived bacteria (Clostridiales_unclassified, Candidatus_Arthromitus, Firmicutes_unclassified and Clostridium). These results strongly displayed that GP enhance the immunity through these routes: increasing immune cell and cytokines, stimulating immune-related pathways, modulating intestinal microbiota and metabolites. Thus, GP shows a great potential to be an immune enhancer or a natural medicine for the treatment of intestinal mucosal injury.