Associations between genetic variants in the ACE, AGT, AGTR1 and AGTR2 genes and renal function in the Multi-ethnic Study of Atherosclerosis

Epigenome-wide association study of diabetic chronic kidney disease progression in the Korean population: the KNOW-CKD study

Since the etiology of diabetic chronic kidney disease (CKD) is multifactorial, studies on DNA methylation for kidney function deterioration have rarely been performed despite the need for an epigenetic approach. Therefore, this study aimed to identify epigenetic markers associated with CKD progression based on the decline in the estimated glomerular filtration rate in diabetic CKD in Korea. An epigenome-wide association study was performed using whole blood samples from 180 CKD recruited from the KNOW-CKD cohort. Pyrosequencing was also performed on 133 CKD participants as an external replication analysis. Functional analyses, including the analysis of disease-gene networks, reactome pathways, and protein-protein interaction networks, were conducted to identify the biological mechanisms of CpG sites. A phenome-wide association study was performed to determine the associations between CpG sites and other phenotypes. Two epigenetic markers, cg10297223 on AGTR1 and cg02990553 on KRT28 indicated a potential association with diabetic CKD progression. Based on the functional analyses, other phenotypes (blood pressure and cardiac arrhythmia for AGTR1) and biological pathways (keratinization and cornified envelope for KRT28) related to CKD were also identified. This study suggests a potential association between the cg10297223 and cg02990553 and the progression of diabetic CKD in Koreans. Nevertheless, further validation is needed through additional studies.

Differential Expression of lncRNA-miRNA-mRNA and Their Related Functional Networks in New-Onset Type 2 Diabetes Mellitus among Chinese Rural Adults

Increasing evidence suggested that the expression and inter-regulation of long noncoding RNA (lncRNA), microRNA (miRNA), and messenger RNA (mRNA) were related to the development of diabetes. Based on bioinformatics analysis, this study aimed to comprehensively analyze the dysregulated RNA molecules related to new-onset type 2 diabetes mellitus (T2DM). Twenty-four patients with new-onset T2DM were included as cases, and sex- and age-matched participants were included as controls. The differentially expressed lncRNAs, miRNAs, and mRNAs between the two groups were screened by RNA sequencing. LncRNA-miRNA-mRNA network and enrichment analysis were used to reveal the RNA molecules that were potentially associated with T2DM and their early changes. A total of 123 lncRNAs, 49 miRNAs, and 312 mRNAs were differentially expressed in the new-onset T2DM (fold change ≥ 1.5 and p value < 0.05). Functional analysis revealed that differentially expressed RNAs were likely to play essential roles in diabetes-related pathways. In addition, the protein-protein interaction (PPI) network screened multiple hub mRNAs, and lncRNA-miRNA-mRNA networks showed that a single miRNA could be related to multiple lncRNAs, and then they coregulated more mRNAs. SLC25A4, PLCB1, AGTR2, PRKN, and SCD5 were shown to be important mRNAs in T2DM, and miR-199b-5p, miR-202-5p, miR-548o-3p as well as miR-1255b-5p could be involved in their regulation. In conclusion, several new and previously identified dysregulated lncRNAs, miRNAs, and mRNAs were found to be vital biomarkers in T2DM. Their alterations and interactions could modulate the pathophysiology of T2DM. Those findings may provide new insights into the molecular mechanisms underlying the development of T2DM.

Unravelling the Lesser Known Facets of Angiotensin II Type 1 Receptor

PURPOSE OF REVIEW

Hypertension is an important risk factor in various pathologies. Despite enormous advancements in health sciences, the number of hypertensive individuals is increasing worldwide. The complex interplay between genetic and epigenetic factors seems to be a promising pathway to exploring the pathophysiology of hypertension.

RECENT FINDINGS

Various single gene and genome wide association studies have generated huge but non-reproducible data that highlights the role of some additional but as yet unidentified factor(s) in disease outcome. Dietary pattern and epigenetic mechanism (mainly DNA methylation) have shown a profound effect on blood pressure regulation. Angiotensin II and its receptors are known to play an important role in maintaining blood pressure; hence, a larger section of antihypertensive drugs targets the renin-angiotensin system (RAS). Angiotensin II type 1 receptor (AT1R), besides maintaining blood pressure, also has a role in cancer progression. Besides other pathways, RAS still remains the main player in blood pressure regulation. Additionally, AT1R has recently emerged as a molecule with diverse roles ranging from physiologic to cancer progression.

Angiotensinogen (AGT) gene missense polymorphisms (rs699 and rs4762) and diabetic nephropathy in Caucasians with type 2 diabetes mellitus

Gene polymorphisms associated with the renin-angiotensin-aldosterone system (RAAS) have been extensively studied in diabetic nephropathy (DN) patients, due to therapeutic potential of targeting the RAAS and slowing down the disease progression. The aim of our study was to examine the association between angiotensinogen (AGT) gene polymorphisms (rs699 and rs4762) and DN in Caucasians with type 2 diabetes mellitus (T2DM). A total of 651 unrelated Slovenian (Caucasian) T2DM patients were tested for AGT rs699 and rs4762 polymorphisms using a novel fluorescence-based kompetitive allele-specific polymerase chain reaction (KASPar) assay. A study group consisted of 276 T2DM patients with DN, while control group included 375 patients without DN but who have had T2DM for >10 years. For rs699 polymorphism, the frequencies of GG, GA and AA genotypes were 20.6%, 52.2% and 27.2%, respectively in T2DM patients and 23.4%, 48.1% and 28.5%, respectively in controls. The distributions of GG, GA and AA genotypes for rs4762 polymorphism were 73.9%, 23.2% and 2.9%, respectively in T2DM patients and 70.4%, 27.5% and 2.1%, respectively in controls. No significant differences in the allele frequencies were found between T2DM patients and controls for both polymorphisms. AGT rs699 and rs4762 missense polymorphisms are not associated with DN in our subset of Slovenian T2DM patients.

Angiotensin type 1 receptor A1166C polymorphism and systemic lupus erythematosus: correlation with cellular immunity and oxidative stress markers

Angiotensin II, one of the rennin–angiotensin system components, is important in the cardiovascular hemodynamic and plays an important role in the development of cardiovascular disease in systemic lupus erythematosus (SLE) patients. The angiotensin II, through interaction with angiotensin II type 1 receptor (AGTR1), promotes proliferation, inflammation and fibrosis. The single nucleotide polymorphism of the AGTR1 (dbSNP: rs5186) gene can be associated with development and progression of SLE disease. The aims of this study were to compare the frequency of AGTR1 rs5186 in SLE patients with healthy individuals and to evaluate possible association between AGTR1 A1166C gene polymorphism and serum level of lipids, neopterin and malondialdehyde in SLE patients from a population of West Iran. One hundred SLE patients and 98 healthy subjects were studied. The AGTR1 A1166C polymorphism was detected by polymerase chain reaction– restriction fragment length polymorphism method and the serum lipid profile was obtained by enzymatic method. Neopterin and malondialdehyde were detected using high-performance liquid chromatography. We did not detect significant association between AGTR1 A1166C polymorphism and the risk of SLE. The levels of triglyceride (225 ± 118 mg/dl), neopterin (30 ± 24 nmol/l) and malondialdehyde (25 ± 9.6 nmol/l) in SLE patients were significantly higher than those in control subjects (139 ± 56 mg/dl, p = 0.03, 6.4 ± 2, p = 0.03, 9.4 ± 2.5 nmol/l, p = 0.01, respectively). Individuals with AGTR1 AC + CC genotype had higher levels of total cholesterol and malondialdehyde compared with those with AGTR1 AA genotype. SLE patients with either AGTR1 AA or AGTR1AC + CC genotype had significantly higher malondialdehyde or neopterin levels compared with the corresponding control subjects. In conclusion, although the present study did not find any association between AGTR1 A1166C polymorphism and the risk of SLE, the presence of this polymorphism was associated with higher levels of malondialdehyde and higher concentration of neopterin in patients.

Estimation of the relationship between the polymorphisms of selected genes: ACE, AGTR1, TGFβ1 and GNB3 with the occurrence of primary vesicoureteral reflux

PURPOSE

Etiopathogenesis of VUR is composite and not fully understood. Many data indicate the importance of genetic predisposition. The aim of this study was to establish the relationship of selected polymorphisms: 14094 polymorphism of the ACE, polymorphism rs1800469 of TGFβ-1, rs5443 gene polymorphism of the GNB3 and receptor gene polymorphism rs5186 type 1 AGTR1 with the occurrence of the primary vesicoureteral reflux.

MATERIAL

The study included 190 children: 90 with the primary VUR confirmed with the voiding cystourethrogram and excluded secondary VUR and a control group of 100 children without a history of the diseases of the genitourinary tract.

METHODS

The study was planned in the scheme: "tested case versus control." Genomic DNA was isolated from the leukocytes of peripheral blood samples. The results were statistically analyzed in the Statistica 10 using χ ² test and analysis of the variance Anova.

RESULTS

Any of the four studied polymorphisms showed no difference in the distribution of genotypes between patients with primary vesicoureteral reflux and the control group. In patients with VUR and TT genotype polymorphism rs5443 GNB3 gene, the glomerular filtration rate was significantly higher than in patients with genotype CC or CT.

CONCLUSIONS

(1) No relationship was found between the studied polymorphisms (14094 ACE gene, rs1800469 gene TGFβ1, GNB3 gene rs5443, rs5186 AGTR1 gene) and the occurrence of primary vesicoureteral reflux. (2) TT genotype polymorphism rs5443 GNB3 gene may be a protective factor for the improved renal function in patients with primary vesicoureteral reflux in patients with genotype CC or CT.

Identification of potential candidate genes for hypertensive nephropathy based on gene expression profile

Background

This study was aimed to explore the molecular mechanisms of hypertensive nephropathy (HTN).

Methods

Gene expression profile of GSE37460, which based on 27 healthy living donor samples (HTN group) and 15 hypertensive nephropathy samples (control group), were downloaded from Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) between two groups were identified. STRING database was used to reveal protein-protein interaction (PPI) network of DEGs, followed by the functional enrichment analysis of the PPI network. Additionally, miRNA-DEG regulatory network was constructed to reveal the validated miRNAs targeting the DEGs.

Results

In total, 51 up-regulated genes and 140 down-regulated genes were obtained. In the PPI network, cytochrome P450 3A4 (CYP3A4) and angiotensin II receptor type 1 (AGTR1) had a higher degree, and CYP3A4 interacted with CYP4A11. The DEGs in the network were significantly enriched in drug metabolism, focal adhesion and arachidonic acid metabolism. Furthermore, in the miRNA-DEG regulatory network, hsa-miR-335-5p and hsa-miR-26b-5p were the two most outstanding miRNAs. AGTR1, CYP3A4 and CYP4A11 were predicted to be regulated by hsa-miR-26b-5p.

Conclusion

The DEGs, such as AGTR1, CYP3A4 and CYP4A11 may play critical roles in the development of HTN likely via the regulation by hsa-miR-26b-5p and taking part in some pathways.

Impact of interactions between risk alleles on clinical endpoints in hypertension

OBJECTIVE

Impairment of the renin-angiotensinogen-aldosterone system (RAAS), one of the characteristics of essential hypertension (EH), imbalances vascular homeostasis. Despite inconsistent reports on individual single nucleotide polymorphisms (SNPs) as a major predictor of EH, interactions among RAAS genetic variants are rarely investigated.

METHODS

Using SNP markers, we studied potential interactions between angiotensin 1 converting enzyme (ACE), angiotensinogen (AGT), angiotensin II-type 1 receptor (AGTR1), and α adducin (ADD1) variants and their correlation with clinical endpoints in 545 individuals with hypertension and 400 age- and ethnicity-matched unrelated controls. Generalised multifactor dimensionality reduction (GMDR) analysis identified the models for genotype interaction.

RESULTS

Although the results on single genes were significant, gene-gene interactions were more reliable and promising as markers in predisposing hypertension. The best models to represent association of multi-locus interactions with augmented hypertension susceptibility were: (a) within gene 4-locus model comprised of AGT SNPs -217G/A, -20A/C, -6G/A and 235M/T (p=0.022, OR 6.1); and (b) between genes 5-locus model comprised of AGT -217G/A, -20A/C, -6G/A, 235M/T and ACE I/D (p=0.05, OR 4.6). Stratification of 4- and 5-locus GMDR models on the basis of risk alleles from ≤1 to ≥7 increased the ORs from 2.8 to 36.1 and from 0.9 to 16.1, respectively. Moreover, compared to ≤1 risk alleles the ≥7 interacting risk alleles in both 4- and 5-locus models showed an increment of 14.2% and 11.1% in systolic blood pressure, 7.7% and 1.1% in diastolic blood pressure, and 10.5% and 5.1% in mean arterial pressure, respectively, in patients.

CONCLUSIONS

Interactions among the genetic loci of RAAS components may be used as a predictor for susceptibility to hypertension.

Contextualizing Genetics for Regional Heart Failure Care

Congestive heart failure (CHF) is a chronic and often devastating cardiovascular disorder with no cure. There has been much advancement in the last two decades that has seen improvements in morbidity and mortality. Clinicians have also noted variations in the responses to therapies. More detailed observations also point to clusters of diseases, phenotypic groupings, unusual severity and the rates at which CHF occurs. Medical genetics is playing an increasingly important role in answering some of these observations. This developing field in many respects provides more information than is currently clinically applicable. This includes making sense of the established single gene mutations or uncommon private mutations. In this thematic series which discusses the many factors that could be relevant for CHF care, once established treatments are available in the communities; this section addresses a contextual role for medical genetics.

Association between angiotensinogen M235T polymorphism and hypertrophic cardiomyopathy

BACKGROUND

To investigate the relationship between angiotensinogen (AGT) gene M235T polymorphism and hypertrophic cardiomyopathy (HCM) to explore the potential role of the AGT polymorphism in HCM.

METHODS

PubMed, Embase, OVID, Cochrane library, CNKI, Wan Fang Database were searched to identify the studies involving AGT M235T polymorphism and HCM. Two authors performed independent literature review and study quality assessment using the Newcastle-Ottawa Scale (NOS) checklist. A random-effects model was used to calculate the overall combined risk estimates.

RESULTS

Nine studies involving 887 cases and 1407 controls were included in our meta-analysis. No significant associations were found between AGT M235T polymorphism and HCM (allele model T vs M: OR = 1.17, 95% CI = 0.95-1.45; dominant model TT vs (MM/MT): OR = 1.21, 95% CI = 1.00-1.45; recessive model (TT/MT) vs MM: OR = 1.12, 95% CI = 0.87-1.45; heterozygous comparison MT vs MM: OR = 1.07, 95% CI = 0.82-1.41; homozygous comparison TT vs MM OR = 1.19, 95% CI = 0.88-1.61. In subgroup analysis, the significant difference of association between AGT M235T polymorphism and HCM existed in Asian and sporadic hypertrophic cardiomyopathy (SHCM), but no significant difference was found in Europeans and familial hypertrophic cardiomyopathy (FHCM).

CONCLUSIONS

There is no association between AGT M235T polymorphism and HCM in general populations, but such a relationship exists in Asians and SHCM.

The role of renin-angiotensin-aldosterone system genes in the progression of chronic kidney disease: findings from the Chronic Renal Insufficiency Cohort (CRIC) study

BACKGROUND

We conducted single-marker, gene- and pathway-based analyses to examine the association between renin-angiotensin-aldosterone system (RAAS) variants and chronic kidney disease (CKD) progression among Chronic Renal Insufficiency Cohort study participants.

METHODS

A total of 1523 white and 1490 black subjects were genotyped for 490 single nucleotide polymorphisms (SNPs) in 12 RAAS genes as part of the ITMAT-Broad-CARe array. CKD progression phenotypes included decline in estimated glomerular filtration rate (eGFR) over time and the occurrence of a renal disease event, defined as incident end-stage renal disease or halving of eGFR from baseline. Mixed-effects models were used to examine SNP associations with eGFR decline, while Cox proportional hazards models tested SNP associations with renal events. Gene- and pathway-based analyses were conducted using the truncated product method. All analyses were stratified by race, and a Bonferroni correction was applied to adjust for multiple testing.

RESULTS

Among white and black participants, eGFR declined an average of 1.2 and 2.3 mL/min/1.73 m(2)/year, respectively, while renal events occurred in a respective 11.5 and 24.9% of participants. We identified strong gene- and pathway-based associations with CKD progression. The AGT and RENBP genes were consistently associated with risk of renal events in separate analyses of white and black participants (both P < 1.00 × 10(-6)). Driven by the significant gene-based findings, the entire RAAS pathway was also associated with renal events in both groups (both P < 1.00 × 10(-6)). No single-marker associations with CKD progression were observed.

CONCLUSIONS

The current study provides strong evidence for a role of the RAAS in CKD progression.

Association of ACE polymorphism and diabetic nephropathy susceptibility

AIM

The study was aimed to analyze whether ACE rs267604983 polymorphism was related to the onset of diabetic nephropathy (DN).

METHODS

80 DN patients and 78 healthy controls were enrolled in the study. The differences of age, sex, body mass index (BMI), systolic blood pressure (SBP) and diastolic blood pressure (DBP) between two groups were analyzed. The genotyping of ACE rs267604983 was conducted by the technology of PCR-HRM. Odds ratio (ORs) with 95% CI were used to evaluate the relationship of ACE rs267604983 with DN susceptibility.

RESULTS

The AA genotype of ACE rs267604983 was remarkably associated with the risk for DN (OR = 2.90, 95% CI = 1.12-7.51). In addition, for the A allele carriers, the risk for DN increased 1.87 fold (OR = 1.87, 95% CI = 1.16-3.01). The subgroup analysis showed that the AA genotype was found higher in normal albuminuria group than other groups (P = 0.006), while AG genotype was higher in macro albuminuria group (P = 0.036).

CONCLUSION

ACE rs267604983 polymorphism is associated with the risk of DN. AA genotype and A allele may increase the risk for DN. Furthermore, AA and AG genotypes may have effects on the subgroups of DN.

Gene polymorphisms of adducin GLY460TRP, ACE I/D, AND AGT M235T in pediatric hypertension patients

BACKGROUND

Hypertension is a major global public health problem that affects both pediatric and adult populations. ACE I/D, AGT M235T, and ADD Gly460Trp polymorphisms are thought to be associated with primary hypertension. In the present study, we examined the frequency of these polymorphisms in a pediatric population with secondary hypertension.

MATERIAL AND METHODS

Included in the study were 58 hypertensive and 58 normotensive pediatric patients. ACE I/D and AGT M235T polymorphisms are determined by conventional PCR; ADD Gly460Trp polymorphism was investigated using PCR amplification of genomic DNA.

RESULTS

There were significant differences between the control group and pediatric hypertensive group in terms of ACE I/D (P<0.05) and AGT M235T (P<0.05) polymorphisms, but there were no differences in ADD Gly460Trp (P>0.05) polymorphism.

CONCLUSIONS

We suggest that RAS gene polymorphisms (ACE-I/D, AGT M235T) are significantly associated with susceptibility to diseases that lead to secondary hypertension.

Gene-gene interactions in renin-angiotensin-aldosterone system contributes to end-stage renal disease susceptibility in a Han Chinese population

OBJECTIVE

In this study, we investigated whether RAAS gene single nucleotide polymorphisms (SNPs) and their interactions were associated with end-stage renal stage (ESRD).

METHODOLOGY AND RESULTS

This was a case-control study for 647 ESRD cases and 644 controls. AGT (M235T (rs699) and T174M (rs4762)), AGTR1 (A1166C (rs5186) and C573T (rs5182)), ACE (I/D (rs1799752) and G2350A (rs4343)), and CYP11B2 C-344T (rs1799998) were genotyped and compared between cases and controls to identify SNPs associated with ESRD susceptibility. Multifactor dimensionality reduction (MDR) was used to identify gene-gene interactions. Several RAAS genes were associated with ESRD: AGT M235T, ACE I/D, ACE G2350A, and CYP11B2 C-344T. By MDR analysis, a three-locus model (ACE ID/ACE G2350A/CYP11B2 C-344T) of gene-gene interaction was the best for predicting ESRD risk, and its maximum testing accuracy was 56.08% and maximum cross-validation consistency was 9/10. ESRD risk was higher with the simultaneous occurrence of ACE I/D DD-ACE G2350A AA. AGT, ACE, and CYP11B2 gene polymorphisms are associated with ESRD.

CONCLUSIONS

The gene-gene interaction effects of ACE I/D, ACE G2350A, and CYP11B2 C-344T polymorphisms are more important than individual factors for ESRD development among Han Chinese.

The renin-angiotensin system from conception to old age: the good, the bad and the ugly

The renin-angiotensin system (RAS) plays a critical role in placentation and nephrogenesis. Failure to thrive during intrauterine life, possibly related to placental dysfunction and impaired expression of the renal RAS, as well as prematurity, results in smaller kidneys at birth and reduced nephron number. The remaining nephrons are therefore hyperfiltering from birth. Hyperfiltration, infections and Type 2 diabetes cause glomerular and tubular fibrosis, leading to further reductions in nephron number. The intrarenal RAS plays a key role in promoting tubulointerstitial fibrosis. Low birth weight and a high incidence of preterm birth program Indigenous children for early onset renal disease in adult life. Indigenous Australians have 404 000 fewer nephrons than non-Indigenous Australians. This, coupled with the high incidence of infectious diseases (particularly acute post-streptococcal glomerulonephritis) and the increasing prevalence of Type 2 diabetes, explains why end-stage renal disease is of epidemic proportions in Indigenous Australians. The existence of RAS gene polymorphisms and inflammatory cytokines may further potentiate susceptibility to renal disease in Indigenous Australians.

The "his and hers" of the renin-angiotensin system

Sex differences exist in the regulation of arterial pressure and renal function by the renin-angiotensin system (RAS). This may in part stem from a differential balance in the pressor and depressor arms of the RAS. In males, the ACE/AngII/AT(1)R pathways are enhanced, whereas, in females, the balance is shifted towards the ACE2/Ang(1-7)/MasR and AT(2)R pathways. Evidence clearly demonstrates that premenopausal women, as compared to aged-matched men, are protected from renal and cardiovascular disease, and this differential balance of the RAS between the sexes likely contributes. With aging, this cardiovascular protection in women is lost and this may be related to loss of estrogen postmenopause but the possible contribution of other sex hormones needs to be further examined. Restoration of these RAS depressor pathways in older women, or up-regulation of these in males, represents a therapeutic target that is worth pursuing.

Top Three Pharmacogenomics and Personalized Medicine Applications at the Nexus of Renal Pathophysiology and Cardiovascular Medicine

Pharmacogenomics is a field with origins in the study of monogenic variations in drug metabolism in the 1950s. Perhaps because of these historical underpinnings, there has been an intensive investigation of 'hepatic pharmacogenes' such as CYP450s and liver drug metabolism using pharmacogenomics approaches over the past five decades. Surprisingly, kidney pathophysiology, attendant diseases and treatment outcomes have been vastly under-studied and under-theorized despite their central importance in maintenance of health, susceptibility to disease and rational personalized therapeutics. Indeed, chronic kidney disease (CKD) represents an increasing public health burden worldwide, both in developed and developing countries. Patients with CKD suffer from high cardiovascular morbidity and mortality, which is mainly attributable to cardiovascular events before reaching end-stage renal disease. In this paper, we focus our analyses on renal function before end-stage renal disease, as seen through the lens of pharmacogenomics and human genomic variation. We herein synthesize the recent evidence linking selected Very Important Pharmacogenes (VIP) to renal function, blood pressure and salt-sensitivity in humans, and ways in which these insights might inform rational personalized therapeutics. Notably, we highlight and present the rationale for three applications that we consider as important and actionable therapeutic and preventive focus areas in renal pharmacogenomics: 1) ACE inhibitors, as a confirmed application, 2) VDR agonists, as a promising application, and 3) moderate dietary salt intake, as a suggested novel application. Additionally, we emphasize the putative contributions of gene-environment interactions, discuss the implications of these findings to treat and prevent hypertension and CKD. Finally, we conclude with a strategic agenda and vision required to accelerate advances in this under-studied field of renal pharmacogenomics with vast significance for global public health.