Regulatory mechanism of lipoprotein on LPS-induced monocyte activation

Objective To investigate the affect mechanism of serum lipoproteins(HDL, LDL, VLDL) on LPS,and compare the regulation ability in LPS-activated of them, to provide theoretical basis for the application of lipoprotein in treatment of sepsis. Methods TNF-α secreted from PMA-differentiated THP-1 cell were detected to reflect the inhibitory action of lipoprotein on LPS indirectly. THP-1 cell were incubated with LPS for 4 houris, TNF-α levels were detected and then compared with the levels in which THP-1 cell incubated with lipoprotein-LPS mixture. Futhermore, the inhibitory action from lipoprotein to LPS was estimated. Results HDL, LDL and VLDL did not induce differentiated THP-1 cells to secrete TNF-α( P ＞ 0.05). When lipoprotein was above 0.05 mg/mL and mixed with 10 ng/mL LPS,TNF-α decreased obviously. The inhibition action of 0. 1 mg/mL lipoprotein (HDL, LDL, VLDL) on LPS was low when LPS was 100 ng/mL, and the rates were (20.7± 11.1)%, (8.85+2.75)%, (4.3± 1.6)% respectively; the inhibitory effect was significantly increased when LPS was 10 ng/mL, and the rates were (69.3±3.7)%, (42.9±5.7)%,(42.7±4.5)% respectively. HDL had stronger inhibitory effect than LDL and VLDL(P ＜ 0.05). ConclusionsLipoprotein in serum can inhibit LPS-activated macrophage cells to secrete cytolines, but the inhibition of lipoprotein is more obvious in high concentration of LPS than low concentration. HDL has a stronger inhibitory effect on LPS activation than LDL and VLDL. Key words: Lipopolysaccharicdes; Lipoproteins; Tumor necrosis factor-α