| CRP, a prototypic kind of acute phase protein, has been shown in several prospective studies to predict acute cardiovascular events, furthermore increasing data demonstrated that CRP was directly involved in atherogenesis. Recruitment of peripheral blood monocyte to arterial wall, uptake OX-LDL by macrophage, secretion of MMP by macrophage are crucial to the initiation and development of atherosclerosis. The study was to focus on these problems. Moreover it was documented that CRP was expressed by the cell components in atherosclerotic lesion. This phenomenon, similar to autocrine and paracrine, provides another proof that CRP participates in atherosclerosis. Another issue to study is expression of CRP by macrophage. Method:THP-1, a human monocyte cell line, human peripheral blood monocyte were used as materials. CD11b and CCR2, associated with adhesion and migration of monocyte, as well as CD36, a scavenger receptor on macrophage were measured by RT-PCR and flow cytometry. The concentration of CRP in conditioned culture medium was measured by ELISA. Activity of MMP-2,MMP-9,MMP-1 in conditioned culture medium were measured by gelatin SDS-PAGE zymography to clarify the effects of CRP on atherogenesis. Result:(1) CRP induced the expression of CCR2 and CD11b on monocyte in dose-dependent mode(p<0.05, n=4), showed by both RT-PCR and flow cytometry. OX-LDL also induced the expression(p<0.01, n=4), while native LDL had no effect on them, and HDL inhibited them. CRP affect the roles of lipoprotein on CCR2 and Cd11b. CRP had additional effectson CCR2(101.80 + 2.59 VS 161.77 + 10.82 , p<0.01, n=4) and CDllb(102.14+2.73 VS 147.14+12.14,p<0.01, n=4) when worked with LDL, but down-regulate the increase of CCR2(115.75+6.4 VS 99+3.65,p<0.01,n=4)andCD11b (121.25+4.79 VS 98.5+4.93, p<0.01, n=4) induced by OX-LDL, but when presented with HDL, the effect of CRP decreased.(2) The changes of CCR2(r=0.613, p<0.01) and CDllb(r=0.615, p<0.01) were correlated with NO in conditioned medium, and CCR2 was also correlated with CD11b(r=0.883, p<0.01).(3) Macrophages in control group differentiated from THP-1, stimulated by PMA, secreted MMP-2, MMP-9, MMP-l,that was inhibited by CRP. For example, Pro-mmp2 (0.82+0.05 VS control group, pO.Ol) and mmp-2 ( 0.61 + 0.03 VS control group, p<0.01 ) were decreased significantly by CRP. furthermore CRP decreased the induction of OX-LDL on MMPs in THP-1 macrophage(0.56 + 0.10 VS OX-LDL group, pO.Ol) .(4) OX-LDL increased the accumulation of cholesterol in foam cell (0.323+0.023 VS 0.150+0.013 nmol/u gPro,p<0.01) , but CRP inhibtedthe accumulation of cholesterol even at 1 u g/ml (0.212+0.028 vs 0.150 +0.013 nmol/y gPro, p<0.01) ,and more efficient at 10u g/ml(0.195 + 0.011 nmol/u gPro). CD36, an important scavenger receptor on surface of macrophage, was also down-regulated by CRP showed by RT-PCR (p<0.05).(5) Macrophage, differentiated from both human peripheral blood monocyte and THP-1 cell line, expressed CRP. The concentration of CRP was very low in control group(0.448 + 0.368ng/ml), and wasup-regulated by OX-LDL in dose-dependent mode(OX-LDL 100 u g/ml group, CRP 8.115+0.433ng/ml, VS control, p<0.01), but decreased by LPS added subsequently (VS OX50+LPS group and OX50group, p<0.01). The result was demonstrated by PMA-induced macrophage. Conclusion:(1) CRP induced the expression of CCR2 and CD11b on the surface of monocyte, and regulated the effects of lipoprotein on them.(2) CRP inhibited MMP-2,MMP-9,MMP-1 secreted by activated macrophage, and also decreased the MMPs induced by OX-LDL.(3) CRP inhibited the accumulation of cholesterol in foam call, at least partially resulted from the down-regulate of CD36 on transcription level, on surface of macrophage.(4) CRP could be produced by Macrophage in vitro, was up-regulated by OX-LDL significantly.
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