Lipopolysaccharides from Escherichia coli 055:B5

Lipopolysaccharide (LPS) is vital to both the structural and functional integrity of the Gram-negative bacterial outer membrane. Ubiquitously expressed by all Gram-negative bacteria, and containing several well-conserved domains, lipopolysaccharide also serves as one of the primary targets of the innate arm of the mammalian immune system. The lipopolysaccharides have a profound effect on the mammalian immune system and are of great significance in the pathophysiology of many disease processes.^[1]

In vitro study indicated that the bone resorption and the inhibition of collagen synthesis caused by lipopolysaccharide could be prevented by PB effectively. Lipopolysaccharide at a concentration of 10μg /ml inhibited bone collagen synthesis by 43% and PB reversed this inhibition in a dose-dependent manner. Even at concentrations as low as 5 μg/ml (PB: LPS =1:2) it reduced the bone-resorbing activity of the lipopolysaccharide by 85%. This effect was specific for resorption stimulated by lipopolysaccharide.^[2]

Lipopolysaccharide preconditioning to mice obviously reduced coelenterazine-Induced fluorescent lesions of Colon26 cells at 7 and 14 days after the intraportal inoculation of Colon26 cells, which expressed Nano-lantern, in comparison to control mice. Moreover, lipopolysaccharide preconditioning significantly reduced the fluorescence intensity of tumors than that of the control mice at both 7 and 14 days after tumor inoculation as well as reduced the liver weight in comparison to control mice at 14 days. Results showed that tumor metastasis was exclusively found in the lungs but not liver. Lipopolysaccharide preconditioning also tended to reduce lung metastasis in vivo.^[3]

References:
[1]. Erridge C, et al. Structure and function of lipopolysaccharides. Microbes Infect. 2002 Jul;4(8):837-51.
[2]. Harvey W, et al. In vitro inhibition of lipopolysaccharide-induced bone resorption by polymyxin B. Br J Exp Pathol. 1986 Oct;67(5):699-705.
[3]. Nishikawa M, et al. Lipopolysaccharide preconditioning reduces liver metastasis of Colon26 cells by enhancing antitumor activity of natural killer cells and natural killer T cells in murine liver. J Gastroenterol Hepatol. 2021 Jul;36(7):1889-1898.