Immunostimulatory effects of polysaccharides isolated from young barley leaves (Hordeum vulgare L.) with dual activation of Th1 and Th2 in splenic T cells and cyclophosphamide-induced immunosuppressed mice

Botanical polysaccharides have been widely known to possess immunological activity. The objective of this study was to investigate the molecular mechanisms underlying the immunostimulatory properties of polysaccharides isolated from barley leaf (Hordeum vulgare L.) (BLE0) in splenocytes and cyclophosphamide (CYP)-induced immunosuppressed mice. BLE0 showed cell proliferative activity and markedly increased the secretion of both Th1-cytokines (IFN-γ and IL-2) and Th2-cytokines (IL-4 and IL-10) in CD3/CD28-activated splenocytes. Molecular data revealed that BLE0 up-regulated the expression of T-bet with enhanced phosphorylation of Janus kinase (JAK)-signal transducer and activator of transcription (STAT) 1 signaling pathway. BLE0 also increase the phosphorylation of GATA3 via toll-like receptor (TLR) 2-mediated signaling pathway with nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and activator protein 1 (AP-1) activation. Oral administration of BLE0 effectively improved CYP-induced decrease of body weight, splenocyte proliferation, and natural killer (NK) cell cytotoxic activity and significantly increased Th1 and Th2 cytokines, T-bet, and GATA3 mRNA expression. Dietary intake of BLE0 improves the immunological manifestations by stimulating both Th1 and Th2 responses via JAK/STAT1/T-bet and TLR2/GATA3, respectively.