Polymyxin B antagonizing biological activity of lipopolysaccharide / 中华创伤杂志(英文版)

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the mechanism of polymyxin B (PMB) antagonizing the biological activity of lipopolysaccharide (LPS).</p><p><b>METHODS</b>The affinity of PMB for LPS and lipid A was assayed by biosensor, and the neutralization of PMB for LPS (2 ng/ml) was detected by kinetic turbidimetric limulus test. The releases of TNF-alpha and IL-6 in murine peritoneal macrophages a (PMphi) after exposure to LPS (100 ng/ml) were detected, and the expression levels of TLR4, TNF-alpha and IL-6 mRNA in PMphi induced by LPS (100 ng/ml) were measured by RT-PCR.</p><p><b>RESULTS</b>PMB had high-affinity to LPS and lipid A with dissociation equilibrium constants of 18.9 nmol/L and 11.1 nmol/L, respectively, and neutralized LPS in a dose-dependent manner. Furthermore, PMB could markedly inhibit the expressions of TLR4, TNF-alpha and IL-6 mRNA and the release of cycokines in LPS-stimulated murine peritoneal macrophages.</p><p><b>CONCLUSIONS</b>PMB neutralizes LPS and inhibites the expression and release of cycokines in macrophages, in which the affinity of PMB for lipid A plays an important role.</p>