Serum Levels Of Trace Elements And Vitamins In Coronary Artery Disease And Their Predictive Values

Background:Coronary artery disease(CAD)refers to a chronic heart disease induced by coronary atherosclerosis.Nowadays,cardiovascular diseases have been a serious threat to human life and health,and CAD has become the leading cause of death in the world.In the past 30 years,there had been an elevating level of risk factors for CAD and increasing number of CAD patients in China.CAD is a chronic cardiovascular disease caused by the combination of multiple risk factors,and controlling risk factors is extremely important for its prevention and treatment.There are many risk factors for CAD,including genetic factors,poor lifestyle,disease factors,psychosocial factors and dietary factors.At present,traditional risk factors for CAD include smoking,obesity,diabetes,hypertension,family genetic history,gender,age,and hyperlipidemia.These risk factors have been taken seriously in clinical studies and have been actively treated,but even so,the incidence of CAD remains high in some populations.Plenty of epidemiological,clinical and experimental studies have shown that some new risk factors may also participate in the development of CAD.Trace elements not only have a wide range of regulatory effects in the normal growth and development of the body and various metabolic processes,but also contribute to the maintenance of the normal structure and function of the cardiovascular system.They can prevent the myocardium from damage caused by lipid peroxides and free radicals,and are also beneficial to the maintenance of its normal myocardial activity.Recent studies have also found a significant correlation between multiple vitamins and CAD.Antioxidant vitamins(vitamin A,C and E)can prevent low-density lipoproteins from being oxidized by free radicals,so that low-density lipoproteins are not easily swallowed by macrophages and deposited on arterial walls.This can thereby delay the occurrence and development of atherosclerosis,and further prevent the occurrence of CAD.Homocysteine(Hcy)has been shown to be one of the independent risk factors of CAD,and the metabolism of Hcy is related with vitamin B12 and folic acid.The lack of vitamin B12 and folic acid can lead to the accumulation of Hcy.Vitamin B12 and folic acid supplementation can reduce the level of homocysteine in the blood of homocysteinemia patients.Vitamin D deficiency has also been proved to be significantly correlated with the development of CAD.Vitamin D can bind to vitamin D receptors on immune cells such as T cells and macrophages,and thus play a role in delaying the development of atherosclerotic plaque caused by inflammatory response.However,comprehensive analysis of the association between trace elements and vitamins and CAD has not been reported,and the quantitative relationship between different levels of trace elements and vitamins and CAD has also not been clarified.Part I Association between serum levels of trace elements and vitamins and coronary artery diseaseObjective:To study the association between serum levels of trace elements and vitamins and CAD.Methods:198 CAD patients were enrolled as the case group,and 396 health controls were enrolled as the control group according to age and sex of these cases at the ratio of 2:1.Demographic data and traditional risk factors were collected.Serum concentrations of 10 trace elements(iron,copper,zinc,manganese,selenium,Chromium,cobalt,lead,nickel and vanadium)and 6 vitamins(A,C,D3,E,B12 and folic acid)were measured.The concentrations of serum trace elements and vitamins in control group and case group were classified into 4 levels(level 1:<Q1,level 2:>Q1 and ?Q2,level 3:>Q2 and? Q3 and level 4:>Q3)according to the quartile(Q1,Q2 and Q3)of the control group.Logistic regression analysis was then performed to determine the quantitative relationship(OR value)between serum levels of trace elements and vitamins and CAD with adjusting the traditional risk factors of CAD.Results:?The results of univariate analysis showed that body mass index(BMI),history of diabetes,history of hypertension,history of smoking,family genetic history of CAD and hyperlipidemia are statistically different between the case group and control group(P<0.001),but history of drinking was not statistically different(P>0.05).? The results of the Kologorov-Smirov test showed that the concentrations of serum iron,copper,zinc,manganese,selenium,Chromium,cobalt,lead,nickel and vanadium were non-normally distributed in the case group and control group.Both the control group and case group were classified into 4 levels according to the quartile of the control group(Q1,Q2,and Q3),which were level 1:?Q1,level 2:>Q1 and? Q2,level 3:>Q2 and? Q3 and level 4:>Q3,respectively.The results of chi-square test showed that the distribution of serum iron,copper,zinc,selenium,Chromium,lead,vitamin D3,B12 and folic acid were statistically different between the case group and control group(P<0.001),and the distribution of serum manganese,cobalt,nickel,vanadium,vitamin A,C and E was not significantly different(P>0.05).? According to the results of univariate analysis,serum levels of trace elements(iron,copper,zinc,selenium,Chromium and lead)and vitamins(D3,B12 and folic acid)were included in Logistic regression analysis,and meanwhile the traditional risk factors of CAD(obesity,history of smoking,family genetic history,hyperlipidemia,history of diabetes and history of hypertension)were also included to adjust the OR value.The results of multivariate analysis showed that serum iron level>Q2(1.71 mg/L),copper level>Q2(0.67 mg/L),zinc level?Q3(1.53 mg/L),selenium level? Q3(1.10 mg/L),lead level>Q1(0.067 mg/L),vitamin D3 level? Q2(36.47 ?g/dL),vitamin B12 level? Q2(68.41 ?g/dL)and folic acid level ? Q2(13.57 ?g/dL)were independent risk factors of CAD after adjusting the traditional risk factors of CAD.Among them,serum iron level>Q2(1.71 mg/L)and?Q3(2.80 mg/L),iron level>Q3(2.80 mg/L),copper level>Q2(0.67 mg/L)and ? Q3(0.92 mg/L),copper level>Q3(0.92 mg/L),zinc level>Q2(1.08 mg/L)and? Q3(1.53 mg/L),zinc level>Q1(0.87 mg/L)and? Q2(1.08 mg/L),zinc level?Q1(0.87 mg/L),selenium level>Q2(0.67 mg/L)and? Q3(1.10 mg/L),selenium level>Q1(0.42 mg/L)and? Q2(0.67 mg/L),selenium level? Q1(0.42 mg/L),lead level>Q1(0.067 mg/L)and? Q2(0.097 mg/L),lead level>Q2(0.097 mg/L)and?Q3(0.142 mg/L),lead level>Q3(0.142 mg/L),vitamin D3 level>Q1(29.67 ?g/dL)?Q2(36.47 ?g/dL),vitamin D3 level ? Q1(29.67 ?g/dL),vitamin B12 level>Q1(49.57 jag/dL)and? Q2(68.41 ?g/dL).vitamin B12 level? Q1(49.57 ?g/dL),folic acid level>Q1(10.28 ?g/dL)and ? Q2(13.57 ?g/dL),folic acid level? Q1(10.28 ?g/dL)were 8.956,26.385,4.016,4.438,3.426,17.047,19.438,3.445,16.962,19.440,2.916,5.327,6.926,3.574,4.239,11.054,11.758,12.137 and 12.847,respectively.Conclusions:Serum iron level>Q2(1.71 mg/L),copper level>Q2(0.67 mg/L),zinc level<Q3(1.53 mg/L),selenium level<Q3(1.10 mg/L),lead level>Q1(0.067 mg/L),vitamin D3 level ?2(36.47 ?g/dL),vitamin B12 level ?Q2(68.41 ?g/dL)and folic acid level? Q2(13.57 ?g/dL)were independent risk factors of CAD.Part ? Values of serum levels of trace elements and vitamins applied in predicting coronary artery diseaseObjective:To evaluate the values of serum levels of trace elements and vitamins applied in CAD.Methods:Receiver operating characteristics(ROC)curves and diagnostic test were employed to evaluate the value of serum levels of trace elements and vitamins applied in predicting CAD..Results:?ROC analysis showed that the area under ROC curve for serum iron level>Q3(2.80 mg/L),zinc level:?Q2(1.08 mg/L),selenium level?Q2(0.67 mg/L),vitamin B12 level ? Q2(68.41 ?g/dL)and folic acid level ? Q2(13.57 ?)g/dL)applied in predicting CAD was 0.782,0.715,0.712,0.707,and 0.722,respectively.Their predictive values were moderate,but the specificity and accuracy were low,the false positive rate was very high,and the positive predictive value was very low.?In order to elevate the values of serum levels of trace elements and vitamins in predicting CAD,serum iron level>Q3(2.80 mg/L),zinc level? Q2(1.08 mg/L),selenium level?Q2(0.67 mg/L),vitamin B12 level? Q2(68.41 ?g/dL)and folic acid level?Q2(13.57 ?)g/dL)were pairwise applied in predicting CAD.ROC analysis showed that the AUCs were all more than 0.800 except for the three combinations including zinc and vitamin B12,selenium and vitamin B12,and vitamin B12 and folic acid.Their predictive values were higher,and the specificity,accuracy and positive predictive value were significantly elevated,and the false positive rate was significantly decreased.Especially for the combination of serum iron and folic acid[serum iron level>Q3(2.80 mg/L)and folic acid level? Q2(13.57 ?g/dL)],its AUC was up to 0.835,the sensitivity,specificity,accuracy,false positive rate,false negative rate,positive likelihood ratio,negative likelihood ratio,positive predictive value and negative predictive value were 79.29%,87.63%,84.85%,23.79%,10.57%,6.41,0.24,76.21%and 89.43%,respectively.Conclusions:Serum iron level>Q3(2.80 mg/L),zinc level? Q2(1.08 mg/L),selenium level<Q2(0.67 mg/L),vitamin B:2 level<Q2(68.41 ?g/dL)and folic acid level? Q2(13.57 ?)g/dL)had moderate values when applied in predicting CAD,but the specificity and accuracy were low.the false positive rate was very high,and the positive predictive value was very low;AUCs were all more than 0.800 except for the combinations of zinc and vitamin B12,selenium and vitamin B12,and vitamin B12 and folic acid when they were pairwise applied in predicting CAD.Their predictive values were higher,and the specificity,accuracy and positive predictive value were significantly elevated,and the false positive rate was significantly decreased.Their combination in predicting CAD might increase the predictive value and optimize the diagnostic indexes.Therefore,serum iron,zinc,selenium,vitamin B12 and folic acid were independently associated with the occurrence of CAD.Their combinations had high values in predicting CAD,and thus had the potential for clinical application.Part III Potential mechanisms of vitamin D involved in coronary artery diseaseObjective:To explore the potential mechanisms of vitamin D involved in coronary artery disease(CAD)Methods:The relative expression of mRNA of MMP-9,IL-6,VEGF and CDK2 was measured using RT-PCR,and mean platelet volume(MPV)was evaluated using laser scattering counting technique.The difference of vitamin D3,MMP-9,IL-6,VEGF,CDK2 and MPV was compared between case group and control group to explore the potential mechanisms of vitamin D involved in CAD.Ordinal multinomial logistic regression was performed to determine the association between vitamin D and MMP-9,IL-6,VEGF,CDK2 and MPV.Results:Mann-Whitney U showed that the concentration of vitamin D3 was higher in control group than in case group,the relative expression of IL-6,MMP-9 and CDK2 and MPV were lower in control group than in case group,and the relative expression of VEGF was higher in control group than in case group.Ordinal multinomial logistic regression analysis showed that the concentration of vitamin D3 was independently associated with the relative expression of IL-6,MMP-9,VEGF and CDK2 and MPV after adjusting CAD,obesity,history of smoking,family genetic history,hyperlipidemia,history of diabetes and history of hypertension.Conclusions:Vitamin D was involved in CAD,and the potential mechanisms included inhibiting the expression of IL-6,MMP-9 and CDK2,enhancing the expression of VEGF and reducing MPV.