Epigenetic Mechanisms Of Hypertension And High Blood Pressure Complications - Genetic Risk Factors For Stroke

Object:Cardiovascular and cerebrovascular diseases are significant healthcare issues around the world. Hypertension is leading risk factor for the diseases It has long been known that hypertension is a multifactorial disease caused by environmental and genetic risk factors. Lots of susceptibility loci associated with blood pressure have been identified using candidate gene approach and genome-wide association studies(GWAS), but only accounted for10%of the heritability in population levels. Hypertension has been estimated to be40%-60%contributed by genetic factors, but for which responsible are still unknown. GWAS studies told us that there maybe the mishersitability could explain why GWAS can only discover10%of the susceptible genetic factors in common diseases such as hypertension. One of the reason for misheristablility is epigenetics referning to hentable changes in gene expression float occur without a change in DNA sequence. To date, the best understood epigenetic mechanisms are CpG DNA methylation, histone modifications and microRNA. It has been known that epigenetic mechanism, such as DNA methylation can be modified by environment factors such highsalt diet, smoking, alcohol, methylation could change the DNA expression. DNA methylation in patients has been the subject of inheres interest because of its recently recognized role in disease as well as in the development in normal function of organisms. From1958to now the hypertension prevalence was increased from5.88%to22%. What we changed mostly are our lifestyle and environment not our gene mutations. Therefore we hypothesized that changes in lifestyle and environmental factors as through epigenetic mechanism such as DNA methylation to change gene expression, therefore disease such as hypertension susceptibility. Our hypothesis was tested in two cohorts perfect control(age>50years old; BP<120/80mmHg; no other major CVD nor major risk factors). The aim of present studies was designed to explore the DNA methylation difference in two case-controls (hypertensive vs. perfect control and prehyertensive untransform vs. transform). As well the preliminary functional research about novel target were performed. We also confirmed the rs1842896reported by pervious GWAS in our case-control. Further, the relation among epigenetic, genetic variation and hypertension was analyzed. Method:we conducted a genome-wide methylation analysis on44severe hypertensive cases,44pre-hypertensive cases and44perfect controls using Illumina450K BeadChip. Pyrosequence was performed on136cases and70controls to validate the most significant CpG sites. The serum level of OVGP1were detected in hypertensives and normotensives by ELISA method, and the expression of OVGP1in endothelial cell(HUVEC) were investigated by real-time PCR, western blot and immunoflourence techniques. Further, pull-down technique was employed in order to capture the proteins interacted possibly with OVGP1from HUVEC. HUVEC was tranfected with lentivirus with OVGP1gene to detect expression changes of genes related with hypertension. In addition, two variants previously reported by GWAS among Chinese hypertensives were genotyped in44server hypertension cases and44perfect controls. We analyzed the relativeship between genotype and epigenetic modification.Results:In discovery step,14CpG sites were significant difference either between sever hypertension and perfect controls or between pre-hypertensive untransform and transform. cg20823859and cg17600943, in the promoter of OVGP1and CPO respectively, were confirmed in an independent sample of136hypertensives and70normotensives. The two CpG sites showed lower methylation levels in case than in controls, indicating beta value difference were-0.11and-0.10, respectively.(adjusted P=0.02and0.001respectively) The serum level of OVGP1was significantly increased in hypertensives. Our results showed that OVGP1was expressed in the cytoplasm of HUVEC. Twenty five proteins potentially interacted with OVGP1were captured by pull-down method, four of which were associated with the mechanism of hypertension in reported studies. Further, the mRNA levels of TGF-fil and TGF-β2were increased when OVGP1was overexpressed in HUVEC and THP1, respectively.Comparied44hypertensives well as that of44normotensives, rs1842896was significantly associated with hypertension in allelic and additive genetic models.(P＜0.05) By integrating the genetic and genome-wide DNA methylation data, we found the subjects who were carrying rsl842896TT genotype and showed a value of beta less than0.75on cg21176026sites were prone to hypertension.Conclusion:Two difference sites identified in peripheral blood genome DNA were associated with hypertension, supporting that changes in DNA methylation may play roles in the pathogenesis of hypertension. Object:Uric acid is the end product of nucleic acid metabolism. Diets heavy in purine or fructose, or exposure to lead can also contribute to high uric acid levels, which is defined as hyperuricemia. Hyperuricemia is not only the major etiological factor of gout, but also the independent risk factor of hypertension, nephrosis, cardiovascular and cerebrovascular disease. Although it seems possible that high uric acid levels are a mere consequence of disease, high uric acid levels always precede the development of hypertension. It is speculated that uric acid, as endogenous environmental risk factor, participants in the pathogenesis of essential hypertension. In this present study, the genome-wide DNA methylation difference was investigated on hyperuricemic hypertension.Method:Here we describe the genome-wide pattern of DNA methylation change in human peripheral blood leucocyte from12hyeruricemia patients and44perfect control using Illumina450K BeadChip. We also investigated the differences of DNA methylation between44sever hypertensive patients and44perfect control. Seven DNA methylation difference loci were associated with both hyperuricemia and hypertension. Further, in vitro we detected the expression change of mRNA level of adjacent genes after THP1and Jurkat cell lines were treated with uric acid.Results:Four significant CpG low methylation sites, including cg15711973、 cg23812489、 cg02157463and cg23947654, were identified in both hyperuricemia and hypertensive cases than in control. The increasing DNA methylation level were observed in cg12252547、 cg06827234and cg16051083. A simultaneous change in mRNA expression was seen for3of those adjacent genes in THP1and Jurkat cell lines treated with uric acid.Conclusion:Six DNA methylation sites identified were associated with both hyperuricemic and hypertension suggesting that changes in DNA methylation may play an important role in the pathogenesis of hyperuricemic hypertension. Intracranial aneurysms (IAs) cause a catastrophic consequence when ruptured. Several genome-wide association studies have been performed in European, but these susceptibility loci to IAs have not been validated in Chinese Han patients. To further investigate the roles of these newly identified variants, we replicated individually the previous association of single nucleotide polymorphism(SNP) with the risk of IAs in a large sample size of the Chinese Han race.Using the Sequenom MassARRAY system, we replicated ten susceptible loci reported in previous genome-wide investigations in649sporadic patients with IAs and1682controls of Chinese. The significant association of rs12413409and rs1980781with sporadic IAs were replicated and shown by allelic association (P=0.002and P=0.002, respectively), as well as by the additive model (adjusted P=0.002and P=0.003, respectively). In younger subgroup, these two variants showed an even stronger association with IAs. Based on the analysis of allele and genotype, rsl2413409-G of CNNM2and rs1980781-C of STARD13increased the risk of IA rupture (adjusted OR=1.25and OR=1.24, respectively). Furthermore, the genotype distributions of rs12413409and rs1980781were marked difference between patients with single IAs and controls (adjusted P=0.001for rs12413409and P=0.001for rs1980781, respectively) after adjustment of modifiable risk factors.In sporadic IAs, two variants of ten loci identified in previous genome-wide association studies are associated with increased risk of IAs among Chinese Han population.