Garlic oligosaccharides upregulate RAW264.7 cellular immunity and enhance intestinal mucosal immunity in immunosuppressed mice

In this study, we comparatively investigated the immunomodulatory effects of garlic oligosaccharides (GPs) of different molecular weights (GPs-U2, GPs-U1 and GPs-U0.3) on RAW264.7 macrophages in vitro and cyclophosphamide (CY)-induced immunosuppressed mice model (C57BL/6 male mice) in vivo. All three GPs displayed high immunomodulatory effects in enhancing cell viability and promoting the secretion of cytokines ( i.e. tumor necrosis factor- α (TNF- α ), interleukin (IL)-1 β and IL-10) in RAW264.7 macrophages in vitro , especially GPs-U2 exhibited the highest immune activity. Furthermore, GPs-U2 showed good immune effects in CY-induced immunosuppressed mouse model in vivo by regulating cytokine secretion, antioxidant levels, goblet cells numbers, expression of tight junction proteins (TJs) and short-chain fatty acids (SCFAs) content. In addition, GPs-U2 maintained mucosal immunity by increasing the abundance of Bacteroidota and Verrucomicrobiota and decreasing the abundance of Firmicutes . These findings support the immune-enhancing effects of GPs-U2 in vitro and in vivo , and provide a scientific basis for the rational use of GPs to alleviate immunosuppression and related diseases.