Ziziphus jujuba “Huizao” Polysaccharides Exert Immunomodulatory Activity In Vitro and In Vivo by Modulating the TLR4/MAPK/NF-κB Signalling Pathway

Ziziphus jujub a is important sources of polysaccharides in food supply, and studies have shown that polysaccharides are primary immunomodulatory active components. The results indicated that “Huizao” polysaccharides (HP) with a molecular weight of 129 kDa and mainly consisting of galactose, glucose and galacturonic acid. HP increased the viability and phagocytic activity of RAW264.7 cells and triggered immune responses by promoting cytokines TNF-α, IL-6 and IL-1β secretion, NO and ROS production. HP also stimulated cytokine production and elevated immunoglobulin levels in immunosuppressed mice. In addition, the oxidative stress was alleviated by HP via increasing antioxidant enzyme activities and reducing MDA production. Moreover, HP enhanced immune responses in vitro and in vivo by modulating the TLR4/MAPK/NF-κB pathway, via increasing the expression of the immune receptor TLR4, promoting the activation of ERK, JNK, and p38 within the MAPK signalling pathway, and subsequently activating NF-κB transcription factors to facilitate cytokines secretion.