Effects of lactoferrin on the expression of TLR4 signaling pathway-associated membrane molecule in LPS-activated U937 macrophages

Abstract:

Objective：To investigate the effects of recombinant human lactoferrin（rhLF） on the expression of toll-like receptors 4 （TLR4） signaling pathway-associated membrane molecule（TLR4，CD14 and MD2） in lipopolysaccharide（LPS）-activated U937 macrophages. Methods：U937 was induced to maturation by phorbol 12-myristate 13-acetate（PMA） and then divided into six groups：control group，LPS group（100 ng/ml LPS），LPS+50 μg/ml rhLF group，LPS+100 μg/ml rhLFgroup，LPS+200 μg/ml rhLF group and LPS+500 μg/ml rhLF group. The mRNA and protein expressions of TLR4，CD14 and MD2 were determined by RT-PCR and Western blot. The concentration of tumor necrosis factor-α（TNF-α） was detected by ELISA. Results：The mRNA and protein expres－sion of TLR4，CD14 and MD2 increased significantly in LPS group than in control group（P<0.05）. The mRNA and protein expression of TLR4，CD14 and MD2 had no significant change in LPS+50 μg/ml rhLF group（P >0.05），but reduced significantly in LPS+100 μg/ml rhLF group，LPS+200 μg/ml rhLF group and LPS+500 μg/ml rhLF group than in LPS group（P<0.05）. The concentration of TNF-α increased significantly in the LPS group than in the control group（P<0.05）. The levels of TNF-α reduced significantly in LPS+50 μg/ml rhLF group，LPS+100 μg/ml rhLF group，LPS+200 μg/ml rhLF group and LPS+500 μg/ml rhLF group than in LPS group（P<0.05）. Conclusion：rhLF might have a potential protective effect on LPS induced sepsis through suppressing TLR4 transmembrane signal transduction pathway and reducing the secretion of TNF-α.