Genetic variant coding for iron regulatory protein HFE contributes to hypertension, the TAMRISK study

Family history of hypertension enhances age-dependent rise in blood pressure, a 15-year follow-up, the Tampere adult population cardiovascular risk study

A family history (FH) of hypertension is known to predispose to high blood pressure. We wanted to study whether it associates with blood pressure and hypertension in the Tampere adult population cardiovascular risk 15-year longitudinal study. A 50-year-old Finnish cohort having hypertension and their controls was examined retrospectively. The groups were combined and stratified to 396 subjects with a positive FH of hypertension and 384 with a negative FH. A 15-year follow-up was done from their periodic health examinations at the ages of 35-, 40-, 45-, and 50 years. In follow-up from the age of 35 years, systolic blood pressure (P < .001), diastolic blood pressure (P < .001), and the annual increase of systolic blood pressure (P < .010) were higher in the group with positive FH, compared to the negative FH group. Positive FH associated with diagnosed hypertension by the age of 50 years (OR 3.52, P < .001). The FH groups were not associated with body mass index. Our findings show that the prevalence of hypertension at the age of 50 years was significantly higher in those with a positive FH of hypertension. Asking about FH can provide the clinician with a simple instrument for recognition of subjects at risk of hypertension for closer monitoring at a younger age.

The gene variant for desmin rs1058261 may protect against combined cancer and cardiovascular death, the Tampere adult population cardiovascular risk study

Desmin-containing intermediate filaments are a part of muscle cytoskeleton. We have previously reported that the wild-type cytosine/cytosine genotype of a common Desmin synonymous single nucleotide polymorphism (C > T) (rs1058261) associated with cardiovascular diseases in a cohort of subjects from the Tampere adult population cardiovascular risk study. We now examined whether rs1058261 also associates with early death by following the cohort of 801 subjects from the age of 50 up to the age of 65. Outcomes for death were collected from the National Statistics Centre. Linkage disequilibrium analysis and gene expression correlations for rs1058261 were done in silico. With follow-up, subjects with wild-type cytosine/cytosine genotype had higher incidence of cancer deaths (odds ratio [OR] 5.27, confidence interval [CI] 1.160-23.946, P = .031), combined deaths from cardiovascular diseases or cancers (OR 3.92, CI 1.453-10.596, P = .007), and "hard" acute cardiovascular disease events (early myocardial infarction and/or death) (OR 3.90, CI 1.287-11.855, P = .016) compared to subjects with the T-allele. The in silico results of linkage disequilibrium and gene expression analyses showed negative gene expression sizes associated with rs1058261, which theoretically decreases desmin expression. Our findings suggest that variation rs1058261 in Desmin may serve as a surrogate marker for other variations involved in decrease of deaths from combined cancer and cardiovascular disease.

Hepcidin is potential regulator for renin activity

An association between genetic variants in the genes HFE, HJV, BMP4 and arterial hypertension has been shown earlier. Proteins encoded by these genes participate in the signalling routes leading eventually to the production of the peptide hormone hepcidin. Mutations in these genes have been associated with the abnormal production of hepcidin in the body. This finding led to studies exploring the possible role of hepcidin in regulating the activity of blood pressure related renin-angiotensin system enzymes. We used molecular modelling to find out if it is possible for hepcidin to bind to the active site of the renin-angiotensin system enzymes, especially renin. Fluorometric assays were used to evaluate the inhibitory effect of hepcidin on renin as well as angiotensin converting enzymes 1 and 2. Finally, bio-layer interferometry technique was used to study hepcidin binding to renin. The molecular modelling showed that hepcidin seems to have similar binding properties to the renin active site as angiotensinogen does. Based on fluorometric enzyme activity assay, hepcidin has an inhibitory effect on renin in vitro, too. However, angiotensin converting enzymes 1 and 2 were not inhibited remarkably by hepcidin-25. In bio-layer interferometry analysis hepcidin-renin binding was concentration dependent. Our results suggest that hepcidin could act as an inhibitor to the renin. Nowadays, there is no known biological inhibitor for renin in vivo and our finding may thus have important clinical implications.

Positive Association of the JAG1 rs1327235 Genotype with Coronary Artery Disease in Men, the Tampere Adult Population Cardiovascular Risk Study

Aims: The intronic single nucleotide polymorphism rs1327235 (A>G) close to the JAG gene has been implicated to be involved in blood pressure physiology in a genome-wide association study. We wanted to study whether it was associated with hypertension and coronary artery disease (CAD) in the Tampere adult population cardiovascular risk study. Materials and Methods: We analyzed a Finnish periodic health examination cohort of 191 men with diagnosed hypertension and 295 controls. Samples were genotyped for the JAG1 rs1327235 polymorphism using Competitive Allelic Specific PCR (KASP). The incidence of CAD was determined by self-report and the National Hospital Discharge Registry (HILMO). Results: There was no association between the JAG1 rs1327235 genotypes with hypertension at the age of 50 years. However, when the subjects were followed to the age of 60 years, those with the genotype GG had a higher prevalence of CAD (17.9%), compared with the A-allele (9.7%) (p = 0.036). When prevalence of CAD was adjusted by body mass index and total cholesterol, the OR for GG genotype was 2.19 (p = 0.029, confidence interval 1.084 - 4.429) compared with A-allele carriers. In addition, the GG genotype was associated with higher total cholesterol and low-density lipoprotein-cholesterol values, compared with the A-allele. Conclusions: Our findings suggest that the variations in JAG1 rs1327235 may be involved in CAD and cholesterol metabolism.

Association of the Collagen Type IV Alpha 1 Chain Gene rs3783107 GG Genotype with Hypertension, Asthma, and Eczema: The Tampere Adult Population Cardiovascular Risk Study

Aims: Basement membranes (BMs) provide structural support to tissues, and also offer functional input to modulate cellular function. Type IV collagen is the most abundant protein in BMs. The collagen type IV alpha 1 chain (COL4A1) gene variant rs3783107 G > A has previously been associated with intracranial aneurysms. We examined this polymorphism's association with cerebrovascular events in the Tampere adult population cardiovascular risk study, and also evaluated its association with hypertension, asthma, and long-term eczema in this population. Materials and Methods: A Finnish periodic health examination (PHE) cohort of 331 subjects with diagnosed hypertension and 440 normotensive controls was analyzed. DNA was extracted from buccal swabs. Genotyping was performed using KASP (competitive allelic-specific amplification). Prevalence of hypertension, asthma, or long-term eczema was obtained from the PHE. The incidences of cerebrovascular diseases and transient cerebral ischemic attacks was obtained from the National Hospital Discharge Registry (HILMO). Results: Even after adjusting for body mass index class and gender, subjects with the rs3783107 major genotype GG had significantly more hypertension (OR [odds ratio] = 1.38, 95% CI [confidence interval]: 1.01-1.87, p = 0.043), asthma (OR = 2.78, 95% CI: 1.25-6.19, p = 0.012), and eczema (OR = 2.00, 95% CI: 1.08-3.70, p = 0.027) than those with the A allele. Furthermore, subjects with the GG genotype had significantly higher systolic (p = 0.026) and diastolic blood pressure (p = 0.013) that those with the A allele. Variant rs3783107 did not significantly associate with cerebrovascular events. Conclusions: Our findings suggest that there are genotype-phenotype associations between the COL4A1 gene variant rs3783107 and hypertension, asthma, and eczema.

Association of a Chromosome Locus 9p21.3 CDKN2B-AS1 Variant rs4977574 with Hypertension: The TAMRISK Study

AIMS

Chromosome locus 9p21.3 CDKN2B antisense RNA 1 (CDKN2B-AS1) has been found to contain multiple genetic markers for coronary artery disease (CAD) by genome-wide association studies (GWAS). Of these, the association of variants rs4977574, rs10757274, and rs2383206 with hypertension was studied in the Tampere adult population cardiovascular risk study (TAMRISK).

MATERIALS AND METHODS

A Finnish cohort of 336 subjects diagnosed with hypertension and 444 controls was analyzed. Samples were genotyped for the CDKN2B-AS1 polymorphisms using Kompetitive Allele Specific PCR (KASP) or TaqMan techniques.

RESULTS

Individuals with the minor genotype GG of rs4977574 had less hypertension compared to the other genotypes (p = 0.048, OR 1.58, 95% CI 1.01-2.48). The variants rs2383206 and rs10757274 were not associated with hypertension.

CONCLUSIONS

Our findings suggest that the GG genotype of the CDKN2B-AS1 gene variant rs4977574, which has been previously associated with an increased CAD risk, is also associated with a decreased susceptibility to the development of hypertension.

Association of Desmin Gene Variant rs1058261 with Cardiovascular Disease, the TAMRISK Study

AIMS

Since desmin expression is diminished in vascular smooth muscle cells during reparative processes, we wanted to study whether a common intragenic single nucleotide polymorphism at nucleotide position 828 (rs1058261) of the DES gene associates with hypertension, cerebrovascular complications, and all cardiovascular events in the Tampere adult population cardiovascular risk (TAMRISK) study.

MATERIALS AND METHODS

A Finnish periodic health examination cohort of 336 subjects with diagnosed hypertension and 473 controls were analyzed. Samples were genotyped for polymorphism using TaqMan techniques. Prevalence of ischemic heart diseases, incidence of cerebrovascular diseases, and transient cerebral ischemic attacks (TIAs) were obtained by self-report and the National Hospital Discharge Registry (HILMO).

RESULTS

There was no association of any of the rs1058261 genotypes with hypertension at the age of 50. When the subjects were followed to the age of 60, after adjustment for gender and body mass index, subjects with the genotype CC had higher incidence of cerebrovascular events (cerebrovascular diseases and TIA) (4.1%) compared with the T allele (1.6%) (p = 0.046). In addition, those with CC genotype had a higher incidence of all combined cardiovascular events (12.8%) compared with subjects with the T allele (8.5%) (p = 0.028).

CONCLUSIONS

Our findings suggest that variations in the DES gene may be involved in cardiovascular disease.

Association of low-density lipoprotein receptor-related protein 1 rs11613352 and angiopoietin-like 3 rs2131925 with hypertension in men-the Tampere adult population cardiovascular risk study

Background

We examined the association of three known genome‐wide association study loci for blood lipids that have lead traits for triglycerides with hypertension in the Tampere adult population cardiovascular risk study.

Methods

A Finnish cohort of 190 men with diagnosed hypertension and 279 controls were analyzed. Samples were genotyped for low‐density lipoprotein receptor‐related protein 1 rs11613352 (C>T), angiopoietin‐like 3 rs2131925 (T>G), and fatty acid desaturase 1 rs174546 (C>T) polymorphisms using competitive allele‐specific polymerase chain reaction technique.

Results

At the age of 50, subjects with low‐density lipoprotein receptor‐related protein 1 rs11613352 (C>T) minor genotype TT had significantly more hypertension than those with the C allele (OR 5.17, CI 2.03–12.74, p < 0.001). Subjects with angiopoietin‐like 3 rs2131925 (T>G) T allele had more hypertension than those with the minor genotype GG (OR 5.02, CI 1.40–17.98, p = 0.013). Fatty acid desaturase 1 rs174546 (C>T) did not associate with hypertension.

Conclusion

Association of low‐density lipoprotein receptor‐related protein 1 rs11613352 and angiopoietin‐like 3 rs2131925 with hypertension might imply a direct effect at the artery wall.

The α1-adrenergic receptor is involved in hepcidin upregulation induced by adrenaline and norepinephrine via the STAT3 pathway

Elevated body iron stores are associated with hypertension progression, while hypertension is associated with elevated plasma catecholamine levels in patients. However, there is a gap in our understanding of the connection between catecholamines and iron regulation. Hepcidin is a key iron-regulatory hormone, which maintains body iron balance. In the present study, we investigated the effects of adrenaline (AD) and norepinephrine (NE) on hepatic hepcidin regulation. Mice were treated with AD, NE, phenylephrine (PE, α1-adrenergic receptor agonist), prazosin (PZ, α1-adrenergic receptor antagonist), and/or propranolol (Pro, β-adrenergic receptor antagonist). The levels of hepcidin, as well as signal transducer and activator of transcription 3 (STAT3), ferroportin 1 (FPN1), and ferritin-light (Ft-L) protein in the liver or spleen, were assessed. Six hours after AD, NE, or PE treatment, hepatic hepcidin mRNA levels increased. Pretreatment with PZ, but not Pro, abolished the effects of AD or NE on STAT3 phosphorylation and hepatic hepcidin expression. When mice were treated with AD or NE continuously for 7 days, an increase in hepatic hepcidin mRNA levels and serum hepcidin concentration was also observed. Meanwhile, the expected downstream effects of elevated hepcidin, namely decreased FPN1 expression and increased Ft-L protein and non-heme iron concentrations in the spleen, were observed after the continuous AD or NE treatments. Taken together, we found that AD or NE increase hepatic hepcidin expression via the α1-adrenergic receptor and STAT3 pathways in mice. The elevated hepatic hepcidin decreased FPN1 levels in the spleen, likely causing the increased iron accumulation in the spleen.

Gene polymorphisms of fibronectin rs2289202 and fibrillin 2 rs331069 associate with vascular disease, the TAMRISK study

Cell surface heparan sulfate (HS) proteoglycans interact with other extracellular matrix (ECM) components, and HS-binding regions are present in ECM proteins such as fibronectin and fibrillin. Because of their previously established role in susceptibility to intracranial aneurysms, the authors sought to determine whether polymorphisms of fibronectin (FN1, rs2289202) and fibrillin 2 (FBN2, rs331069) associate with selected cardiovascular risk factors and events in the TAMRISK study. A 50-year-old Finnish cohort of 810 subjects of whom 340 had diagnosed hypertension was analyzed. Samples were genotyped for FN1 rs2289202 and FBN2 rs331069 polymorphisms. Incidence of myocardial infarction (I21-I22), transient cerebral ischemic attacks (TIA, G45) and cerebrovascular diseases (I60-I69) were followed up until the subjects were on the average 60 years old. Subjects with FN1 rs2289202 (G>A) minor genotype AA had significantly more cerebrovascular disease than those with the G allele [P<0.001, odds ratio (OR), 8.73; confidence index (CI), 2.79-27.31], although those with the A allele had lower body mass index (P=0.008). Subjects with fibrillin rs331069 (T>C) minor genotype CC had more atherothrombotic disease (P=0.012, OR, 3.16; CI, 1.29-7.71), as measured by combined myocardial infarction and TIA, than those with the T allele. The gene polymorphisms for fibronectin and fibrillin 2 appear to associate with vascular disease.

Genetic variation in bone morphogenetic proteins family members (BMPs 2 and 4) and hypertension risk in middle-aged men: The TAMRISK study

Bone morphogenetic proteins (BMPs) are important regulators of iron metabolism affecting hepcidin expression. We have previously shown that 2 genetic polymorphisms in different genes (histocompatibility complex class I-like transmembrane protein, hemojuvelin) involved in the regulation of hepcidin expression pathways are associated with hypertension. In this study, we analyzed genetic variation sites in BMP2 (rs235756, rs235768) and BMP4 (rs4901474) to get more evidence linking iron metabolism to hypertension risk in the Finnish population.The study included 321 hypertensive cases and 463 controls from the Tampere Adult Population Cardiovascular Risk study cohort. Genotyping of polymorphisms was done by polymerase chain reaction using DNAs extracted from buccal swabs.We found that men carrying the GG genotype of BMP2 rs235756 (A>G) polymorphic site had a 4.09-fold risk (confidence interval [CI] 1.61-10.39, P = .003) for hypertension at the age of 50 years compared with A-allele carriers. The risk was significant in the age groups of 45 and 40 years as well. In addition, the 15-year follow-up period of the same individuals showed that carriers of the GG-genotype had also significantly higher readings of both systolic (P < .001) and diastolic (P = .01) blood pressure during the follow-up time. No significant association between BMP2 rs235768 (A>T) and hypertension was found. BMP4 polymorphic site rs4901474 (T>C) also had an effect on hypertension. CC genotype carriers had a 1.48-fold risk (CI 1.03-2.13, P = .033) for hypertension at the age of 50 years when compared with T-allele carriers.In conclusion, BMP2 polymorphic site rs235756 was associated with hypertension in Finnish men. An effect of BMP4 polymorphic site on hypertension was also found.

Minor variant of rs 16827043 in the iron regulator hemojuvelin gene (HJV) contributes to hypertension: The TAMRISK study

It is known that iron overload may lead to an increased risk for many diseases. According to GWAS studies, iron regulatory protein HFE gene variant H63D (rs1799945) was associated with hypertension, an observation which we were able to confirm also in our TAMRISK cohort. Thus, it is possible that abnormalities in iron homeostasis may predispose to hypertension. This prompted us to study whether there is an association between hypertension and another iron overload-associated gene, hemojuvelin (HJV), which has 2 common polymorphic sites (rs 16827043, rs7536827).The study included 336 hypertensive cases and 480 controls. All participants were 50- year-old Finnish men and women, and the data was collected from the Tampere adult population cardiovascular risk study (TAMRISK). Genotypes were determined using Competitive Allelic Specific PCR (KASP).We found that the minor variant of the HJV polymorphic site rs16827043 (G-allele) is a statistically significant factor associated with hypertension among 50 year-old individuals compared with the AA genotype carriers (OR = 1.66, 95% CI: 1.06 - 2.60, P = 0.03). The risk was even higher when overweight subjects (BMI>30) were excluded from the analyses. For the other polymorphic variant rs7536827, association with hypertension was found only among normal or slightly overweight A-allele carriers.In conclusion, HJV genetic variants were associated with essential hypertension in Finnish subjects from the TAMRISK cohort. Previous studies together with the present one indicate that individuals with possible dysregulation of iron metabolism may have higher risk for hypertension than those with normal iron homeostasis.

Haplotype analysis of the HFE gene among populations of Northern Eurasia, in patients with metabolic disorders or stomach cancer, and in long-lived people

BACKGROUND

Previously, it was shown that the HFE gene (associated with human hereditary hemochromatosis) has several haplotypes of intronic polymorphisms. Some haplotype frequencies are race specific and hence can be used in phylogenetic analysis. We assumed that analysis of Caucasoid patients-living now in Western Siberia and having diseases associated with dietary habits and metabolic rate-will allow us to understand the processes of possible selection during settling of the northern part of Asia.

RESULTS

Haplotype analysis of Northern Eurasian native and recently settled ethnic groups was performed on polymorphisms rs1799945, rs1800730, rs1800562, rs2071303, rs1800708, rs1572982, rs2794719, rs807209, and rs2032451 of this gene. The CCA haplotype of the rs2071303, rs1800708, and rs1572982 was found to be associated with HLA-A2 (39 %) in Asian populations. Haplotype analysis for the rs1799945, rs1800730, rs1800562, rs2071303, rs1800708, and rs1572982 was performed on Russian patients with some metabolic disorders or stomach cancer and among long-lived people. Decreased frequencies of the TTA haplotype (T in rs2071303, T in rs1800708, and A in rs1572982) were observed in the groups of patients with diseases associated with overweight (fatty liver disease, type 2 diabetes mellitus, or metabolic syndrome + arterial hypertension) as compared with the control sample. We detected significant differences in this haplotype's frequency between the patients with type 2 diabetes mellitus and Russian adolescents, elderly citizens, and long-lived people (χ(2) P value = 0.003, 0.010, and 0.015, respectively).

CONCLUSIONS

No significant differences in frequencies of the alleles with mutations in coding regions of the HFE gene (C282Y, H63D, and S65C) were detected between the analyzed patients (with stomach cancer, metabolic syndrome, fatty liver disease, or type 2 diabetes mellitus) and the control Caucasoid sample. Monophyletic origin of H63D (rs1799945) was confirmed in Caucasoids and Northern Asians. The reasons for a sharp increase in the frequency of CCA haplotype of HFE in the Asian race remain unclear.

Genetic Polymorphisms of Transcription Factor NRF2 and of its Host Gene Sulfiredoxin (SRXN1) are Associated with Cerebrovascular Disease in a Finnish Cohort, the TAMRISK Study

Oxidative stress is involved in the pathophysiology of many cardiovascular disorders, such as hypertension and atherosclerosis. NRF2 is the primary transcriptional regulator of several antioxidant genes, including that of sulfiredoxin (SRXN1). The association of genotypes of NRF2 and SRXN1 with cardiovascular conditions was studied in a Finnish cohort of 336 subjects with diagnosed hypertension and 480 normotensive controls from the Tampere adult population cardiovascular risk study (TAMRISK). Samples were genotyped for four SNPs (rs1962142, rs2706110, rs6721961 and rs6706649) in the NRF2 gene region and four SNPs (rs6053666, rs6116929, rs2008022, rs6085283) in the SRXN1 gene region using Competitive Allele Specific PCR (KASP) technique. Cardiovascular diseases were followed up from 2005 to 2014 using the Finnish National Hospital Discharge Registry (HILMO). Four out of eight studied polymorphisms: rs6721961, rs1962142, rs2706110 of NRF2, and rs6053666 of SRXN1 were associated with cerebrovascular disease. NRF2 polymorphism rs6721961 showed association with hypertension. NRF2 and SRXN1 polymorphisms, previously thought to be associated with human disease, appear to be associated particularly with cerebrovascular disease.

Functional Inducible Nitric Oxide Synthase Gene Variants Associate With Hypertension: A Case-Control Study in a Finnish Population-The TAMRISK Study

Increased inducible nitric oxide synthase (iNOS) activity and expression has been associated with hypertension, but less is known whether the 2 known functional polymorphic sites in the iNOS gene (g.-1026 C/A (rs2779249), g.2087 G/A (rs2297518)) affect susceptibility to hypertension. The objective of this study was to investigate the association between the genetic variants of iNOS and diagnosed hypertension in a Finnish cohort.This study included 320 hypertensive cases and 439 healthy controls. All participants were 50-year-old men and women and the data were collected from the Tampere adult population cardiovascular risk study (TAMRISK). DNA was extracted from buccal swabs and iNOS single nucleotide polymorphisms (SNPs) were analyzed using KASP genotyping PCR. Data analysis was done by logistic regression.At the age of 50 years, the SNP rs2779249 (C/A) associated significantly with hypertension (P = 0.009); specifically, subjects carrying the A-allele had higher risk of hypertension compared to those carrying the CC genotype (OR = 1.47; CI = 1.08-2.01; P = 0.015). In addition, a 15-year follow-up period (35, 40, and 45 years) of the same individuals showed that carriers of the A-allele had more often hypertension in all of the studied age-groups. The highest risk for developing hypertension was obtained among 35-year-old subjects (odds ratio [OR] 3.83; confidence interval [CI] = 1.20-12.27; P = 0.024). Those carrying variant A had also significantly higher readings of both systolic (P = 0.047) and diastolic (P = 0.048) blood pressure during the follow-up. No significant associations between rs2297518 (G/A) variants alone and hypertension were found. However, haplotype analysis of rs2779249 and rs2297518 revealed that individuals having haplotype H3 which combines both A alleles (CA-GA, 19.7% of individuals) was more commonly found in the hypertensive group than in the normotensive group (OR = 2.01; CI = 1.29-3.12; P = 0.002).In conclusion, there was a significant association between iNOS genetic variant (rs2779249) and hypertension in the genetically homogenous Finnish population. Those who carried the rare A-allele of the gene had higher risk for hypertension already at the age of 35 years.

NLR family pyrin domain containing 3 (NLRP3) inflammasome gene polymorphism rs7512998 (C>T) predicts aging-related increase of blood pressure, the TAMRISK study

Background

The activation of NLR family pyrin domain containing 3 (NLRP3) inflammasome by cellular stress leads to activation of the inflammasome, and NLRP3 gene polymorphisms have been associated with autoinflammatory diseases. Inflammasomes have also been implicated in the initiation or progression of metabolic disorders such as atherosclerosis, type 2 diabetes and obesity. The association of NLRP3 genetic variant rs7512998 with blood pressure and hypertension was studied in a 50-year-old Finnish cohort with a subpopulation who had available data on blood pressure measurements also at the age of 45 years.

Results

NLRP3 gene polymorphism rs7512998 C-allele was associated with higher systolic (p = 0.006) and diastolic (p = 0.011) blood pressure compared to the TT-genotype carriers in 50-year-old subjects. In addition, by analysis of variance for repeated measures between ages of 45- and 50 years there was a significant time by genotype interaction; blood pressure increased more in subjects with the C-allele both in systolic (p = 0.035) and diastolic (p = 0.012) values. However, no association with diagnosed hypertension was found.

Conclusion

We report for the first time that NLRP3 gene polymorphism rs7512998 was associated with systolic and diastolic blood pressure in 50-year-old subjects. In addition, an effect of this variation upon blood pressure was seen in these same subjects in a 5-year follow-up from a 45-year-old cohort to 50 years of age.