Effects of polyclonal lipopolysaccharide binding protein antibody on the expression of Toll-like receptor 4 and tolerance to lipopolysaccharide in alveolar macrophages of rats

Objective To explore the effects of polyclonal lipopolysaccharide binding protein (LBP) antibody on the expression changes of Toll-like receptor 4(TLR4) and the tolerance to lipopolysaccharide (LPS) in alveolar macrophages(ΦAM) of rats. Methods The ΦAM obtained from 32 Wistar male rats were randomly divided into control group (A), LPS single stimulating group (B), LPS re-stimulating group (C) and LPS re-stimulating plus polyclonal LBP antibody group (D). TNF-α concentration and TLR4 mRNA expression were measured by ELISA and semi-quantitive reverse transcription-polymerase chain reaction (RT-PCR ) respectively in ΦAM of each group. The expression of TLR4 protein was measured by Western blotting. Results The TNF-α concentration and TLR4 expression in the ΦAM stimulated with single dose LPS (100 ng/ml) were highly increased compared with the control group, but significantly decreased after re-stimulated with two dose of LPS (100 ng/ml and 500 ng/ml) and the reduction was more overt in group D. Conclusion The tolerance to LPS in ΦAM can be induced by re-stimulation with LPS. The down-regulated expression of TLR4 is related to the tolerance to LPS. Poly-clonal LBP antibody can enhanceΦAMtolerance to LPS by decreasing TLR4 expres-sion and the antibody is presumably eligible on the basis of molecular biology for the treatment of acute lung in-jury induced by LPS.