The Study Of The Relationship Between Protein Composition In High Density Lipoprotein And Coronary Heart Disease And Its Alteration By Statins Among Patients With Coronary Heart Disease

BackgroundThe alteration of proteins existing in high density lipoprotein (HDL) is found to affect its function. It will be helpful to comprehend the relationship between HDL and coronary heart disease (CHD) by studying the protein composition of HDL and to clarify the role of HDL in atherosclerosis further.Recently, there are several studies exploring the proteins in HDL by proteomics technology, showing that the protein composition in HDL isolated from patients with CHD was different from controls and combined statin and niacin therapy may remodel the HDL proteome. However, the related study was rare and insufficient.In our laboratory, we have conducted a preliminary study comparing the difference in HDL proteome between patients with CHD and controls and found that a significant decrease in the level of apolipoprotein A-I (apoA-I) and the increase in the level of serum amyloid A protein (SAA), which need to be validated in another independent group with larger sample size. In addition, there is no study exploring the effect of statins per se on HDL proteome at present, and the interaction between statins and HDL has been found in several studies.Part1:The relationship between apolipoprotein A-I and SAA in high density lipoprotein isolated from patients with coronary heart diseaseObjectTo compare the difference in the levels of apoA-I and SAA in HDL isolated form patient with CHD and controls and understand the relationship between apoA-I and SAA.MethodsPatients with at least one coronary artery stenosis more that50%and never take statins and other lipids-lowing drugs (CHD group) and a group of age and sex-matched subjects (control group) were enrolled. HDL was isolated by ultracentrifugation. Enzyme linked immunosorbent assay (ELISA) was used to detect the levels of apoA-I and SAA in plasma and in HDL. Pearson correlation analysis was used to explore the relationship between apoA-Ⅰ and SAA in HDL. Logistic regression was used to study the association between apoA-Ⅰ and CHD and between SAA and CHD.Results1.67patients and67controls were enrolled in this part of study.2. Compared with controls, the level of apoA-Ⅰ was significantly decreased in HDL isolated from CHD patients (7.80±3.32g/mL vs.10.42±5.51g/mL, P=0.001). However, the difference was disappeared when adjusted by potential confounding factors (B=-0.109, P=0.088). The level of log (HDL-SAA) was significantly higher in CHD patient than the one in control group (1.39±0.58vs.1.15±0.46, P=0.011). The significance was still exist after adjustment for confounding factors (B=1.738, P=0.017). The OR value was5.685, which means that the risk of CHD will increase4.685when the log(HDL-SAA) increase1unit (OR=5.685,95%CI:1.371,23.581).3. Compared with controls, the level of apoA-Ⅰ in plasma was not different between the two groups (0.7±0.33g/mL vs.0.79±0.28g/mL, P=0.122). The level of log(plasma-SAA) was significantly higher in CHD group than in control group (1.13±0.54vs.0.88±0.48, P=0.005) independently from confounding factors (B=1.646, P=0.038). The OR value for log(plasma-SAA) was5.185(OR=5.185,95%CI:1.095,24.544).4. The level of apoA-I and SAA did not show any correlation in HDL or in plasma both in the two groups.Part2:The alteration in HDL proteome by statins among patients with coronary heart diseaseObjectivesTo study the alteration in HDL proteome by statins among patients with coronary heart disease and the difference of the level of each protein in HDL isolated from CHD patient before and about half year after statins therapy.MethodsHDL isolated from9patients with CHD before and about half year after statins therapy and10age-sex matched controls was analyzed by isobaric tags for relative and absolute quantitation (iTRAQ)-liquid chromatography-mass spectrometry. GO analysis was performed to understand the function classification and molecular activity of all detected proteins in HDL. Cluster analysis was used to clarify the difference characteristic of all proteins in HDL among the three groups. Treatment-induced decrease in SAA2level of HDL were validated in a second group of44CHD patients and45controls and in a third group of67CHD patients never using statins or other lipid-lowing drugs and65CHD patients who had already taken statins for about half year.Results1.196proteins with high confidence coefficient (FDR=0.01and at least two peptides matched) were detected by iTRAQ-LC-MS.2. The GO analysis indicated that these detected proteins maybe involved in many biological processes, such as lipids-transport, inflammation, innate immune defence, and so on. These proteins also showed multiple activities, for example lipids-binding activity, enzyme inhibitor activity, peptide-chain hydrolysis activity, and so on.3.14proteins were found different with significance in HDL isolated from CHD patients before statins therapy and after about half year therapy.13proteins were found different between CHD and control. There3proteins, serum amyloid A2isoform(SAA2)、complement C5preproprotein and histone H1.0, showed the same alteration trend in these three groups, which increased in CHD patients when compared with controls, and decreased in CHD patients after statins therapy.4. The level of SAA was significantly decreased after statins therapy. The level of SAA in HDL among CHD patients was correlated with statins therapy.Conclusion1. HDL is composed of many proteins, and these proteins showed multiple activities, for example lipids-binding activity, enzyme inhibitor activity, peptide-chain hydrolysis activity, etc. and may be involved many biological processes, such as lipids-transport, inflammation, innate immune defence, and so on.2. The HDL proteome is altered in patients with CHD. When compared with control, the level of SAA was significantly increased and there is a decrease trend in the level of apoA-I.13new proteins were found to be different between CHD group and control group in the present study.3. Level of SAA was significantly decreased after statins therapy.14new proteins altered after statins therapy in the present study, which maybe the new targets of statins.4. Statins may remodel the HDL proteome.5. HDL is composed of many proteins, and the alteration of protein composition in HDL may be helpful to study the HDL functions.