Exopolysaccharides of Bifidobacterium longum subsp. infantis E4 on the immune and anti-inflammatory effects in vitro

Abstract

Exopolysaccharides (EPS) are biological macromolecules produced by Bifidobacterium to the outside of the cell wall during growth and metabolism. The EPS of Bifidobacterium have anti-inflammatory and antimicrobial activities and could regulate the immune system. In this study, the Bifidobacterium longum subsp. infantis E4 (B. infantis E4) has 21 specific genes for carbohydrate transport and metabolism compared with other 12 strains of B. infantis and could produce exopolysaccharides. The average molecular weights of EPS-1, EPS-2 and EPS-3 were 2.68 × 104, 3.79 × 104 and 4.72 × 104 Da, respectively. The EPS-1 mainly comprised of 7 kinds of monosaccharide, and EPS-2 and EPS-3 mainly comprised of 8 kinds of monosaccharide. The immunomodulatory and anti-inflammatory properties of EPS-1, EPS-2 and EPS-3 on RAW264.7 cells, spleen lymphocytes and NK cells of mouse were investigated in vitro of this study. EPS-1, EPS-2 and EPS-3 promoted the growth and increased phagocytic index of macrophage RAW264.7 at the concentration of 100 μg/mL. Subsequently, EPS-1, EPS-2 and EPS-3 groups were found to increase splenic lymphocyte proliferation and NK cell activity. Compared with the LPS group, EPS-1, EPS-2 and EPS-3 reduced the production of NO, IL-1β, IL-6, TNF-α and PGE-2 in RAW264.7 cells after in lipopolysaccharide (LPS) induced, with EPS-1 having the best effect. Meanwhile, EPS-1, EPS-2 and EPS-3 down-regulated the expression levels of LPS-induced NF-κβ signaling pathway-related genes p-p65, p-Iκβ, iNOS, COX-2 and reduced the nuclear translocation of p65 protein in RAW264.7 cells. In conclusion, our study suggested that EPS produced by B. infantis E4 has immunostimulatory and anti-inflammatory activities and may serve as a potential prebiotic to maintain future health.