Abstract
Immune enhancement is an important factor that not only helps prevent infections but also affects overall health. This study aims to evaluate the immunostimulatory effects of a novel Lactobacillus strain, Lactobacillus paracasei L-30, and to elucidate its underlying mechanisms. The extract obtained from Lactobacillus paracasei L-30 significantly increased phagocytosis and the production of NO and ROS in RAW264.7 macrophages. The protein and mRNA expression levels of COX-2 and iNOS which are immune regulators were upregulated by the L-30 extract. The levels of cytokines and chemokines, such as G-CSF, IL-6, MIP-1α, MIP-1γ, RANTES, sTNF RI, and sTNF RII, were increased by the treatment with the L-30 extract. In addition, the L-30 extract degraded IκB-α and induced the phosphorylation of NF-κB. Furthermore, the MAPK signaling pathways ERK, JNK, and p38 were activated by the L-30 extract. The production of iNOS, COX-2, and NO was inhibited by MAPK pathway inhibitors. Therefore, our data suggest that the Lactobacillus paracasei L-30 extract has the potential to be developed as a healthy functional food that can enhance immune responses by activating macrophages.