The Relationship Between DNA Methylation Of IGFBP-3 Gene,hypertension And Body Weight And The Impact Of Long Term Burden Of Hypertension And Body Weight On Cardiovascular Disease

BackgoundCardiovascular disease is the leading cause of death worldwide and a major contributor to reduce quality of life.High blood pressure is one of the most important risk factors for cardiovascular disease and the number one preventable risk factor for cardiovascular disease and premature death.The pathogenesis of hypertension is very complex,most of which are caused by a variety of genetic and environmental factors.It is important to find new pathogenesis and influenc factors of hypertension for the diagnosis and treatment.Overweight and obesity are important risk factors for cardiovascular disease and premature death,the incidence is increasing in surprising rate globally.Hypertension and obesity are caused by many factors,which are influenced by genetic,epigenetic and environmental factors.A large cross-ethnic GWAS study published in Nature Genetics in 2015 identified 12 new genes,including IFGBP-3,that are significantly associated with blood pressure phenotypes.IGFBP-3 can affect the function of vascular smooth muscle cells and is significantly related to cardiovascular diseases.IGFBP-3 DNA methylation may regulate gene expression and affect the occurrence and development of cardiovascular diseases through mechanisms such as neurohumoral,inflammation and oxidative stress.At present,a large number of studies are still needed to explore the relationship between the epigenetics of cardiovascular disease-related genes and hypertension and body weight,and understand the occurrence and development of the disease and develop new targets for intervention therapy.Atherosclerosis,the most important independent risk factor for cardiovascular disease,begins long before clinical symptoms appear and progresses slowly.Obesity and hypertension play very important role in the occurrence and development of atherosclerosis.Until now,the complex relationship between body mass index,blood pressure,and atherosclerosis has not been fully understood.In the occurrence and development of atherosclerosis,whether obesity causes atherosclerosis directly by acting on the arteries or indirectly by increasing blood pressure,further research is needed to clarify this process.Heart failure is the final stage of many heart diseases,is caused by hypertension through left ventricular hypertrophy and diastolic dysfunction.Obesity may lead to heart failure through direct mechanisms such as increased cardiac output and increased blood pressure and indirect mechanisms such as activation of the renin-angiotensin-aldosterone system and the sympathetic nervous system.Although there is substantial evidence that obesity and hypertension are associated with left ventricular hypertrophy,the long-term cumulative effects of increased body mass index and elevated blood pressure starting in childhood on cardiac structure and function are unclear and further research is needed to clarify this concordant process.Part ⅠObjectiveWe detecte the methylation levels of CpG sites in the IGFBP-3 gene promoter region to study the relationship between IGFBP-3 DNA methylation,blood pressure,BMI and overweight.Subjects and MethodsThe IGFBP-3 gene DNA methylation was detected by sulfite sequencing technology in the target region of 1241 subjects from Jiangsu Metmetabolic Syndrome Study（JSMSS）.The relationship between IGFBP-3 DNA methylation and blood pressure,BMI and overweight was investigated by using multiple linear model and Logistic regression model.Furthermore,we analyzed the mediating relationship between IGFBP3 DNA methylation and DBP and hypertension mediated by BMI and overweight.ResultsWe first analyzed the relationship between the methylation level of CpG site of IGFBP3 gene and blood pressure level.The results showed that after adjusting for confounding factors such as gender,age,smoking,alcohol consumption,BMI,blood glucose and blood lipid,the methylation levels of three CpG sites in IGFBP-3₁ fragment were positively correlated with Systolic blood pressure（SBP）,and the standardized regression coefficients（β）between them were statistically significant（all P<0.05）,these sites include:IGFBP3₁₄9,IGFBP-3₁₁55 and IGFBP-3₁₁93.In contrast to the effect of CpG methylation in IGFBP-3₁ fragment,the methylation levels of four CpG sites in IGFBP-3₂ fragment were negatively correlated with SBP,and the β values were all statistically significant（all P<0.05）,these sites include:IGFBP-3₂₂8,IGFBP-3₂₉6,IGFBP-3₂₁04 and IGFBP3₂₁87.The methylation levels of 19 CpG sites in IGFBP-3₁ fragment were positively correlated with DBP,and the β values between them were statistically significant（all P<0.05）,these sites include:IGFBP-3₁₂8,IGFBP-3₁₃1,IGFBP-3₁₃5,IGFBP3₁₃8,IGFBP-3₁₄3,IGFBP-3₁₄5,IGFBP-3₁₄9,IGFBP-3₁₅8,IGFBP-3₁₆8,IGFBP-3₁₈9,IGFBP-3₁₉8,IGFBP-3₁₁05,IGFBP-3₁₁11,IGFBP-3₁₁13,IGFBP-3₁₁30,IGFBP-3₁₁55,IGFBP-3₁₁57,IGFBP-3₁₁66 and IGFBP-3₁₁93,the mean β value（standard error SE）between DNA methylation levels and DBP at these CpG sites was 0.88（0.029）,P=0.003.The analysis of the relationship between the methylation of CpG sites in IGFBP-3₁ fragment and hypertension showed that the methylation level of 14 CpG sites was positively correlated with hypertension,that is,the hypermethylation level of these sites could increase the risk of hypertension,and the OR value was statistically significant（all P<0.05）,these sites include:IGFBP-3₁₂8,IGFBP-3₁₃1,IGFBP-3₁₃5,IGFBP-3₁₃8,IGFBP3₁₄3,IGFBP-3₁₄5,IGFBP-3₁₄9,IGFBP-3₁₅8,IGFBP-3₁₆8,IGFBP-3₁₁11,IGFBP-3₁₁13,IGFBP-3₁₁55,IGFBP-3₁₁57 and IGFBP-3₁₁93,average DNA methylation levels at these CpG sites were positively correlated with hypertension,with OR（95%CI）of 1.03（1.01-1.05）,P=0.015.In contrast to the CpG methylation of IGFBP-3₁,IGFBP-3₂₁87 in IGFBP-3₂ fragment was negatively correlated with hypertension,that is,hypermethylation could reduce the risk of hypertension,and the OR value was statistically significant（P<0.05）.After subgroup analysis for factors such as sex,age and overweight,the results in some subgroups were similar to those in the general population.We also analyzed the relationship between CpG methylation of IGFBP-3 gene and body weight.The results showed that after adjusting for confounding factors such as gender,age,smoking,drinking,blood pressure,blood glucose,blood lipid,16 CpG sites in IGFBP-3₁ fragment were positively correlated with BMI（all P<0.05）,these sites include:IGFBP3₁₂8,IGFBP-3₁₃1,IGFBP-3₁₃5,IGFBP-3₁₃8,IGFBP-3₁₄3,IGFBP-3₁₄5,IGFBP-3₁₄9,IGFBP-3₁₅8,IGFBP-3₁₆8,IGFBP-3₁₉8,IGFBP-3₁₁05,IGFBP₃₁₁11,IGFBP-3₁₁13,IGFBP-3₁₁51,IGFBP-3₁₁55 and IGFBP-3₁₁93,the mean β value（SE）between DNA methylation levels at these CpG sites and BMI was 0.17（0.07）,P=0.018.In the same direction as IGFBP-3₁,IGFBP-3₂₁55 in IGFBP-3₂ fragment also showed a positive correlation with BMI（P<0.05）.We further analyzed the association between CpG methylation of IGFBP-3 gene and overweight（BMI≥24 kg/m2）.The results showed that the methylation level of 11 CpG sites in IGFBP-3₁ fragment was positively correlated with overweight,that is,the hypermethylation level of these sites could increase the risk of overweight,and the OR value was statistically significant（all P<0.05）,these sites include:IGFBP-3₁₃5,IGFBP-3₁₄3,IGFBP-3₁₄5,IGFBP-3₁₉8,IGFBP-3₁₁05,IGFBP-3₁₁11,IGFBP-3₁₁13,IGFBP-3₁₁30,IGFBP-3₁₁51,IGFBP-3₁₁55 and IGFBP-3₁₁93,average DNA methylation levels at these CpG sites were positively associated with overweight,i.e.,hypermethylation levels increased the risk of overweight by 2%for each 1 methylated unit increased（OR:1.02;95%CI:1.00 1.04;P=0.024）.After subgroup analysis for factors such as sex,age and blood pressure,the results in some subgroups were similar to those in the general population.We analyzed the mediation effect of DNA methylation at the CpG site of IGFBP-3 gene and the relationship between BMI and blood pressure levels,the results showed that BMI had a mediating effect between DNA methylation at CpG site of IGFBP-3 gene and DBP level,and the mediating effect was 26.3%.These results suggested that BMI mediated DNA methylation at CpG site of IGFBP-3 gene to regulate DBP level.Conclusions1.The DNA methylation level of the CpG site of IGFBP-3 gene was positively correlated with SBP,DBP and hypertension.The methylation of some CpG sites in IGFBP-3₁ fragment was positively correlated with SBP,DBP and hypertension.The methylation level of some CpG sites in IGFBP-3₂ fragment was negatively correlated with SBP and hypertension.2.The methylation level of some CpG sites in IGFBP3₁ fragment was positively correlated with BMI or overweight.3.BMI mediated the relationship between DNA methylation level at CpG site of IGFBP-3 gene and DBP.The results of this study provide epigenetic evidence for the relationship between DNA methylation at CpG site of IGFBP-3 gene and hypertension,overweight and their relationship.Part ⅡObjectiveA longitudinal cohort of Bogalusa Heart Study was used from childhood to adulthood to investigate the long-term mediating effect of blood pressure on the relationship between body mass index（BMI）and adult atherosclerosis,and the effects of increasing body mass index（BMI）and blood pressure starting in childhood on the structure and function of left ventricular of adults.Subjects and MethodsWe used the Bogalusa Heart Study cohort,a cross-sectional survey conducted every 23 years from 1973 to 2016,to produce a series of observations from children to adults.The current longitudinal study cohort consisted of approximately 1190 adult subjects,of whom 829 were white,361 were black,43.5%were male,and the mean age was 48.2 years.BMI and BP measurements were performed 4 to 16 times,at least 2 times in childhood and at least 2 times in adulthood,and aorto-femoral pulse wave velocity（AFPWV）examinations and echocardiography were performed.The baseline and follow-up data of all subjects were checked and collated.The long-term cumulative effect and long-term growth trend of BMI and BP were measured by area under the curve（AUC）.The total effect and mediating effect of BMI on adult AFPWV were studied by multivariate linear regression analysis after adjusting for confounding factors.An ethnic-predictor interaction term was added to the interactive regression model to test the significance of differences in regression coefficients between races.After adjusting for age,race,gender,heart rate,smoking and alcohol consumption,multivariate linear regression was performed to analyze the relationship between LVMI,LVEF,E/A ratio and E/E ’ratio and BMI and BP.LVH,CR,EH,and CH were all normal LVM as the reference group for geometric remodeling analysis of the left ventricle.ResultsIn this study,we quantified the mediating effect of adult BMI,blood pressure and their long-term effects,and found that the association between BMI and afPWV was mainly mediated by adult blood pressure and its long-term cumulative value,rather than by adult body mass index.The correlation between childhood BMI and adult afPWV was mainly mediated by blood pressure（SBP:20.2%,DBP:25.0%）and the increasing trend of blood pressure AUCi（SBP:16.9%,DBP:21.4%）during adulthood.When analyzing the correlation between the increasing trend of BMI AUCi and adult afPWV,long-term measurement of BMI and blood pressure were used as predictors and mediators respectively,the increasing trend of blood pressure AUCi showed a greater mediating effect than adult blood pressure at one time point（SBP:63.3%,DBP:64.6%）.The effects of body mass index and blood pressure on heart structure and function in adults begin early in life.Compared with blood pressure,childhood body mass index,adult body mass index,and long-term cumulative effects were more closely associated with left ventricular hypertrophy.We also found that body mass index was inversely associated with systolic function（left ventricular ejection fraction）in adults.Body mass index and blood pressure were significantly positively correlated with diastolic function（E/e’ratio）.Compared with normal left ventricular mass group,left ventricular ejection fraction was significantly decreased and E/e ’ratio was significantly increased in patients with left ventricular hypertrophy,eccentric hypertrophy,and concentric hypertrophy.Conclusions1.In this study,we demonstrate that the increase of BMI and its cumulative burden and trend during childhood and adulthood are significantly associated with adult atherosclerosis（afPWV）.The relationship between higher BMI and increased afPWV was mainly mediated by increased blood pressure.Compared with BMI in adulthood,the long-term burden of elevated blood pressure plays a more important role in angiosclerosis in adulthood.Chronically elevated blood pressure played a stronger mediating role in the association between cumulative increased BMI and adult atherosclerosis.2.We also demonstrated that the effects of BMI and BP levels and their cumulative long-term increase on cardiac structure and function begin early in life,and that BMI and its measurements are more strongly associated with left ventricular hypertrophy than BP.BMI measurements were negatively correlated with adult systolic function represented by LVEF,while blood pressure measurements were more strongly correlated with diastolic function represented by E/e ’ratio than BMI.3.The systolic and diastolic functions of left ventricular hypertrophy,eccentric hypertrophy and concentric hypertrophy were worse than those of normal left ventricular mass group.