Immunoregulatory effect of Lactobacillus paracasei VL8 exopolysaccharide on RAW264.7 cells by NF-κB and MAPK pathways
Jie Gao, Qi Li, Yuwei Liu, Bing Yang, Faizan Ahmed Sadiq, Xiyu Li, Si Mi, Yaxin Sang
Abstract
This study explored the immunoregulatory mechanism of VL8-EPS, obtained from Viili. An RAW264.7 macrophage cell-line was used along with real-time quantitative PCR to evaluate the impact of VL8-EPS on mRNA expression of IL-1β, TNF-α, IL-6, IL-10, and TLR4. Moreover, western blot assay was conducted to study the signal pathway of NF-κB and MAPK. The VL8-EPS was found to upregulate the mRNA expression of these cytokines and TLR4, while it promoted protein phosphorylation of p65, IκBα, ERK1/2, and JNK. The immunofluorescence staining and inhibitor blocking experiments proved that TLR4, NF-κB, and MAPK signal pathway were involved to secrete immune-enhancing substances. In conclusion, VL8-EPS was involved to activate downstream signal pathways of NF-κB and MAPK through TLR4 identification, which caused an increase in mRNA expression and cytokines release, ultimately exerting immune regulation.