Curcuma longa L. extract increased immune responses in RAW 264.7 cells and cyclophosphamide-induced BALB/c mice

Abstract Curcuma longa L. extract (CLE) exerts various biological functions including antioxidant, anti-inflammation, anticancer, and antiallergenic effects. However, its immune-enhancing capacity remains unclear. Therefore, the immune-enhancing effect of CLE was investigated in RAW 264.7 cells and cyclophosphamide (CPP)-induced immunosuppression model. CLE upregulated nitric oxide (NO) and reactive oxygen species production and increased inducible nitric oxide synthase and cyclooxygenase-2 expression without affecting the RAW 264.7 cells viability. The results of quantitative real-time reverse transcription polymerase chain reaction and sandwich enzyme-linked immunosorbent assay showed that CLE increased the gene expression and protein levels of tumor necrosis factor-α, interleukin-6, and interleukin-1β in RAW 264.7 cells. Moreover, CLE upregulated p65, I kappa B kinase α/β, and I kappa B α (IκBα) phosphorylation and downregulated IκBα expression in RAW 264.7 cells. CLE also increased p65 translocation from the cytoplasmic to the nucleus in RAW 264.7 cells. The oral administration of CLE increased organ indexes (including the spleen and thymus) and NO production in peritoneal macrophages and improved natural killer cell activity in CPP-induced immunosuppression BALB/c mice. Overall, CLE could be a useful health functional food material that can improve innate immunity via macrophage activation.