Activation of RAW 264.7 cells by a polysaccharide isolated from Antarctic bacterium Pseudoaltermonas sp S-5

The aim of this study was to examine the effect of extracellular polysaccharide (PEP) from Antarctic bacterium Pseudoaltermonas sp. S-5 on RAW 264.7 cells together with the underlying signaling pathways. Our results illustrated that PEP induced dendritic-like morphological change in RAW 264.7 cells, and increased the productions of nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha). PEP could also enhance phagocytic activity of RAW 264.7 cells. Results of immunofluorescence staining and immunoblotting indicated that PEP caused the nuclear translocation of nuclear factor (NF)-kappa B subunit p65, the degradation of I kappa B-alpha and up-expression of phosphorylated p38 mitogen-activated protein kinase (MAPK) in RAW 264.7 cells. According to pharmacological evaluation with specific enzyme inhibitors, both NF-kappa B and p38 MAPK signaling pathways were involved in the generation of NO and TNF-alpha induced by PEP. All these results indicated that PEP from Antarctic bacterium Pseudoaltermonas sp. S-5 activated RAW 264.7 cells through NF-kappa B and p38 MAPK signaling pathways. (C) 2015 Elsevier Ltd. All rights reserved.