Stimulating effects of cheonggukjang extract on macrophage-mediated immune responses

In Asia, there are various fermented soybean products like Natto, Doenjang, Tempeh and so on. Cheonggukjang is soybean paste fermented by Bacillus subtilis and a traditional healthy food in Korea. Here, we investigated the regulatory effects of Cheonggukjang extract on macrophage-mediated immune responses. When Cheonggukjang extract treatment was used in combination with interferon-γ (IFN-γ), there was a marked cooperative induction of nitric oxide (NO) and tumor necrosis factor-α (TNF-α) production in macrophages. Cheonggukjang extract increased the expression of inducible NO synthase mRNA, protein and TNF-α mRNA in macrophages. These alterations of Cheonggukjang extract-treated cells were associated with the activation of nuclear factor-κB (NF-κB). Cheonggukjang extract increased the phosphorylation and transcriptional activity of p65 in macrophages. These results suggest that Cheonggukjang extract increased NO and TNF-α production through phosphorylation of p65 following IκBα degradation and NF-κB activation. Treating macrophages with pyrrolidine dithiocarbamate and BAY11–7082, an inhibitor of NF-κB, decreased the synergistic effects of Cheonggukjang extract. In conclusion, our results demonstrate that Cheonggukjang extract can effectively promote the activation of macrophages, suggesting that Cheonggukjang extract may possess the potential to regulate immune responses.