Immunomodulatory Effects of Traditional Korean Gochujang in Rats Immunosuppressed with Cyclophosphamide

Fermented foods are consumed in several cultures worldwide and their health benefits are being increasingly reported. Fermented soybean products in Asia include soybean paste (doenjang), fermented soybeans (cheonggukjang), red pepper paste (gochujang, GCJ), and natto. These fermented foods are reportedly associated with health benefits, including the alleviation of colitis and improvement of immune function. In this study, we investigated the immune-enhancing effects of GCJs produced in four different regions of Korea (including a commercial brand) in cyclophosphamide-treated immunosuppressed rats. The GCJs-treated group showed prevention of weight loss, increased levels of butyric acid in the cecum, and increased weight of lymphoid organs such as the thymus and spleen. Whole blood and serum analysis revealed increased numbers of white blood cells, including granulocytes and lymphocytes, pro-inflammatory cytokines (IL-2, IL-12, IFN-γ, and TNF-α), and elevated immunoglobulin G levels. Additionally, splenocyte proliferation, splenic natural killer cell activity, and immune-related signal pathways (MAPK and NF-κB) were increased. Histological analysis revealed improved tissue structure in the GCJs group. In conclusion, these findings show that GCJs enhance immune function by promoting the growth of immune organs, increasing cytokine production, and activating immune-related signaling pathways. These results suggested the potential of traditional Korean GCJs as a dietary intervention to improve immune health.