Genetic polymorphisms in nitric oxide synthase 3 gene and implications for kidney disease: a meta-analysis

Influence of genetic polymorphisms in vascular endothelial-related genes on the clinical outcome of axitinib in patients with metastatic renal cell carcinoma

OBJECTIVE

Axitinib is an oral multi-target tyrosine kinase inhibitor used for the treatment of renal cell carcinoma (RCC). Because of the severe adverse events (AEs) associated with axitinib, patients often need dose reductions or discontinue its use, highlighting the need for effective biomarkers to assess efficacy and/or AEs. The aim of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) in genes involved in the pharmacodynamic action of axitinib and clinical prognosis and AEs in metastatic RCC (mRCC) patients.

METHODS

This study included 80 mRCC patients treated with first-, second-, or third-line axitinib (5 mg orally twice daily). Clinical parameters and genetic polymorphisms were examined in 75 cases (53 males and 22 females). We assessed three SNPs in each of three candidate genes namely, angiotensin-converting enzyme (ACE), nitric oxide synthase 3 (NOS3), and angiotensin II receptor type 1 (AT1R), all of which are involved in axitinib effects on vascular endothelial function.

RESULTS

Axitinib-treated patients carrying the ACE deletion allele suffered more frequently from hand-foot syndrome and a deterioration in kidney function (p  = .045 and p =  0.005, respectively) whereas those carrying the NOS3 G allele suffered more frequently from proteinuria and multiple AEs (p  = .025 and p =  0.036, respectively).

CONCLUSIONS

Our study found that the ACE deletion allele and the NOS3 G allele are associated with increased AEs.

Genetic Variants and Their Associations to Type 2 Diabetes Mellitus Complications in the United Arab Emirates

Aim

Type 2 Diabetes Mellitus (T2DM) is associated with microvascular complications, including diabetic retinopathy (DR), diabetic nephropathy (DNp), and diabetic peripheral neuropathy (DPN). In this study, we investigated genetic variations and Single Nucleotide Polymorphisms (SNPs) associated with DR, DNp, DPN and their combinations among T2DM patients of Arab origin from the United Arab Emirates, to establish the role of genes in the progression of microvascular diabetes complications.

Methods

A total of 158 Emirati patients with T2DM were recruited in this study. The study population was divided into 8 groups based on the presence of single, dual, or all three complications. SNPs were selected for association analyses through a search of publicly available databases, specifically genome-wide association study (GWAS) catalog, infinome genome interpretation platform, and GWAS Central database. A multivariate logistic regression analysis and association test were performed to evaluate the association between 83 SNPs and DR, DNp, DPN, and their combinations.

Results

Eighty-three SNPs were identified as being associated with T2DM and 18 SNPs had significant associations to one or more diabetes complications. The most strongly significant association for DR was rs3024997 SNP in the VEGFA gene. The top-ranked SNP for DPN was rs4496877 in the NOS3 gene. A trend towards association was detected at rs833068 and rs3024998 in the VEGFA gene with DR and rs743507 and rs1808593 in the NOS3 gene with DNp. For dual complications, the rs833061, rs833068 and rs3024997 in the VEGFA gene and the rs4149263 SNP in the ABCA1 gene were also with borderline association with DR/DNp and DPN/DNp, respectively. Diabetic with all of the complications was significantly associated with rs2230806 in the ABCA1 gene. In addition, the highly associated SNPs rs3024997 of the VEGFA gene and rs4496877 of the NOS3 gene were linked to DR and DPN after adjusting for the effects of other associated markers, respectively.

Conclusions

The present study reports associations of different genetic polymorphisms with microvascular complications and their combinations in Emirati T2DM patients, reporting new associations, and corroborating previous findings. Of interest is that some SNPs/genes were only present if multiple comorbidities were present and not associated with any single complication.

Diabetic kidney disease: Are the reported associations with single-nucleotide polymorphisms disease-specific?

BACKGROUND

The genetic backgrounds of diabetic kidney disease (DKD) and end-stage kidney disease (ESKD) have not been fully elucidated.

AIM

To examine the individual and cumulative effects of single-nucleotide polymorphisms (SNPs) previously associated with DKD on the risk for ESKD of diabetic etiology and to determine if any associations observed were specific for DKD.

METHODS

Fourteen SNPs were genotyped in hemodialyzed 136 patients with diabetic ESKD (DKD group) and 121 patients with non-diabetic ESKD (NDKD group). Patients were also re-classified on the basis of the primary cause of chronic kidney disease (CKD). The distribution of alleles was compared between diabetic and non-diabetic groups as well as between different sub-phenotypes. The weighted multilocus genetic risk score (GRS) was calculated to estimate the cumulative risk conferred by all SNPs. The GRS distribution was then compared between the DKD and NDKD groups as well as in the groups according to the primary cause of CKD.

RESULTS

One SNP (rs841853; SLC2A1) showed a nominal association with DKD (P = 0.048; P > 0.05 after Bonferroni correction). The GRS was higher in the DKD group (0.615 ± 0.260) than in the NDKD group (0.590 ± 0.253), but the difference was not significant (P = 0.46). The analysis of associations between GRS and individual factors did not show any significant correlation. However, the GRS was significantly higher in patients with glomerular disease than in those with tubulointerstitial disease (P = 0.014) and in those with a combined group (tubulointerstitial, vascular, and cystic and congenital disease) (P = 0.018).

CONCLUSION

Our results suggest that selected SNPs that were previously associated with DKD may not be specific for DKD and may confer risk for CKD of different etiology, particularly those affecting renal glomeruli.

Genome-Wide Association Study of Diabetic Kidney Disease Highlights Biology Involved in Glomerular Basement Membrane Collagen

BACKGROUND

Although diabetic kidney disease demonstrates both familial clustering and single nucleotide polymorphism heritability, the specific genetic factors influencing risk remain largely unknown.

METHODS

To identify genetic variants predisposing to diabetic kidney disease, we performed genome-wide association study (GWAS) analyses. Through collaboration with the Diabetes Nephropathy Collaborative Research Initiative, we assembled a large collection of type 1 diabetes cohorts with harmonized diabetic kidney disease phenotypes. We used a spectrum of ten diabetic kidney disease definitions based on albuminuria and renal function.

RESULTS

Our GWAS meta-analysis included association results for up to 19,406 individuals of European descent with type 1 diabetes. We identified 16 genome-wide significant risk loci. The variant with the strongest association (rs55703767) is a common missense mutation in the collagen type IV alpha 3 chain (COL4A3) gene, which encodes a major structural component of the glomerular basement membrane (GBM). Mutations in COL4A3 are implicated in heritable nephropathies, including the progressive inherited nephropathy Alport syndrome. The rs55703767 minor allele (Asp326Tyr) is protective against several definitions of diabetic kidney disease, including albuminuria and ESKD, and demonstrated a significant association with GBM width; protective allele carriers had thinner GBM before any signs of kidney disease, and its effect was dependent on glycemia. Three other loci are in or near genes with known or suggestive involvement in this condition (BMP7) or renal biology (COLEC11 and DDR1).

CONCLUSIONS

The 16 diabetic kidney disease-associated loci may provide novel insights into the pathogenesis of this condition and help identify potential biologic targets for prevention and treatment.

Diabetic Microvascular Disease: An Endocrine Society Scientific Statement

Both type 1 and type 2 diabetes adversely affect the microvasculature in multiple organs. Our understanding of the genesis of this injury and of potential interventions to prevent, limit, or reverse injury/dysfunction is continuously evolving. This statement reviews biochemical/cellular pathways involved in facilitating and abrogating microvascular injury. The statement summarizes the types of injury/dysfunction that occur in the three classical diabetes microvascular target tissues, the eye, the kidney, and the peripheral nervous system; the statement also reviews information on the effects of diabetes and insulin resistance on the microvasculature of skin, brain, adipose tissue, and cardiac and skeletal muscle. Despite extensive and intensive research, it is disappointing that microvascular complications of diabetes continue to compromise the quantity and quality of life for patients with diabetes. Hopefully, by understanding and building on current research findings, we will discover new approaches for prevention and treatment that will be effective for future generations.

Association study of NOS3 gene polymorphisms and hypertension in the Han Chinese population

BACKGROUND

Recent studies have reported that NOS3 plays an important role in cardiovascular pathology, whereas the association of NOS3 and hypertension (HT) has been controversial between African Americans and European whites. Here, we aimed to further investigate the genetic effect of unexplored loci at NOS3 on the susceptibility of HT in the Han Chinese population.

METHODS AND RESULTS

The association of three polymorphisms; rs4496877, rs1808593 and rs3918186 to HT was tested in a case control study that included 2012 HT cases and 2210 controls. Association analysis showed that there was no significant association between rs4496877, rs1808593 and rs3918186 of NOS3 and HT in the whole study population. Stratification analysis indicated that rs3918186 was significantly associated with HT in the ≥55-year-old population (OR = 1.245, 95% CI = 1.010-1.534, P = 0.04). The rs4496877 and rs1808593 were significantly associated with HT in the male population (P = 0.015) and <55-year-old population (P = 0.025), respectively (OR = 3.254, 95% CI = 1.257-8.425 and OR = 1.683, 95% CI = 1.066-2.657, respectively). Quantitative trait analysis showed that there were significant differences in systolic blood pressure (SBP) among the genotypes (AA, AT and TT) of rs3918186 in the non-intervention populations (P = 0.016). GMDR analysis showed that drinking and rs3918186 had significant interaction effects for risk of HT.

CONCLUSIONS

The findings of this study indicated that the rs4496877, rs1808593 and rs3918186 polymorphisms of NOS3 contribute to the genetic susceptibility of HT and that rs3918186 was associated with SBP in the Chinese population. Age and gender might modify the genetic effect of NOS3 on HT, and drinking significantly interacts with rs3918186.

The -974C>A (rs3087459) gene polymorphism in the endothelin gene (EDN1) is associated with risk of developing acute coronary syndrome in Mexican patients

Endothelial dysfunction plays an essential role in the development and progression of atherosclerotic lesions. Endothelial nitric oxide synthase (eNOS) and endothelin-1 (ET-1) are considered important molecules in the endothelial dysfunction process. The aim of the present study was to evaluate the role of eNOS and ET-1 (EDN1) gene polymorphisms as susceptibility markers for acute coronary syndrome (ACS). Six polymorphisms (rs1799983, rs2070744, rs1800783, rs3087459, rs1800541, and rs5369) of eNOS and EDN1 genes were analyzed by 5' exonuclease TaqMan genotyping assays in a group of 452 patients with ACS and 283 healthy controls. The results showed increased frequencies of the A allele of the END1-914 C>A (rs3087459) polymorphism in ACS patients when compared to controls (OR=1.56, Pc=0.01). Under an additive model, the "AA" genotype was associated with an increased risk of developing ACS, adjusted for gender, hypertension, dyslipidemia, alcohol consumption, smoking, and diabetes (OR=1.56, p=0.045). Linkage disequilibrium analysis showed one EDN1 haplotype (AT) with increased frequency in ACS patients when compared to healthy controls (OR=1.65, Pc=0.0015). The "AT" haplotype was associated with the risk of developing ACS after adjusting for cardiovascular risk factors using multiple logistic analysis. In this case, the adjusted OR was 1.73 for the AT haplotype (Pc=0.0018). In summary, resulting data suggest that the END1-914 C>A gene polymorphism could be involved in the risk of developing ACS in Mexican individuals.

Genetic and epigenetic risk factors for diabetic kidney disease

Diabetes is increasing at daunting rates worldwide, and approximately 40% of affected individuals will develop kidney complications. Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease, and there are significant healthcare costs providing appropriate renal replacement therapies to affected individuals. For several decades, investigators have sought to discover inherited risk factors and biomarkers for DKD. In recent years, advances in high-throughput laboratory techniques and computational analyses, coupled with the establishment of multicenter consortia, have helped to identify genetic loci that are replicated across multiple populations. Several genome-wide association studies (GWAS) have been conducted for DKD with further meta-analysis of GWAS and comprehensive "single gene" meta-analyses now published. Despite these efforts, much of the inherited predisposition to DKD remains unexplained. Meta-analyses and integrated-omics pathway studies are being used to help elucidate underlying genetic risks. Epigenetic phenomena are increasingly recognized as important drivers of disease risk, and several epigenome-wide association studies have now been completed. This review describes key findings and ongoing genetic and epigenetic initiatives for DKD.

Review of Genetic Association in the SOD2 Gene with Chronic Kidney Disease: Case-Control Studies and Meta-Analysis Confirm Association with Diabetic Nephropathy

The SOD2 gene encodes a mitochondrial protein that is involved with response to oxidative stress and cellular proliferation. The diabetic milieu, in particular hyperglycemia, results in the overproduction of superoxide and formation of secondary reactive oxygen species contributing to the accumulation of DNA, protein and cellular damage. Functional genetic variants within the SOD2 gene are postulated to influence renal injury. We sought to resolve the inconsistent conclusions of several studies examining the SOD2 gene for association with chronic kidney disease, in particular diabetic nephropathy. We genotyped a total of 3,913 individuals with diabetic nephropathy, glomerulonephritis and/or end-stage renal disease, reviewed published literature, and conducted a subsequent meta-analysis. Using χ2 test, our independent case-control study for diabetic nephropathy revealed evidence for association of rs4880 (P=0.01). However, this was ameliorated by adjusting for age at diagnosis, duration, sex and recruitment centre in the logistical model. Genotype counts were obtained for all published studies having genotyped this SNP and a meta-analysis was performed on a total of 3,949 individuals with type 1 diabetes mellitus (cases n=2,184; controls, n=1,765). No significant heterogeneity was observed (P=0.5) and association with diabetic nephropathy was supported by P=0.005 (odds ratio 0.87, 95% confidence interval: 0.79–0.96). There is biological evidence that this amino-acid changing SNP, rs4880, directly influences enzymatic activity of the SOD2 gene product. We conclude that the functional, clinically associated rs4880 is important in the pathogenesis of diabetic nephropathy.

eNOS tag SNP haplotypes in hypertensive disorders of pregnancy

Haplotypes formed by polymorphisms (T-786C, rs2070744; a variable number of tandem repeats in intron 4, and Glu298Asp, rs1799983) of the eNOS gene were associated previously with gestational hypertension (GH) and preeclampsia (PE). However, no study has explored the Tag SNPs rs743506 and rs7830 in these disorders. The aim of the current study was to compare the distribution of the genotypes and haplotypes formed by the five eNOS polymorphisms mentioned among healthy pregnant (HP, n=122), GH (n=138), and PE (n=157). The haplotype formed by "C b G G C" was more frequent in HP compared to GH and PE (p=0.0071), which is supported by previous findings that demonstrated the association of the combination "C b G" with a higher level of nitrite (NO marker). Our results suggest a protective effect of the haplotype "C b G G C" against the development of hypertensive disorders of pregnancy.

Nitric oxide synthase derangements and hypertension in kidney disease

PURPOSE OF REVIEW

Nitric oxide deficiency occurs by multiple mechanisms and contributes to the pathogenesis of progression of chronic kidney disease (CKD) and its cardiovascular complications. This article concentrates on recent developments on the regulation of the endogenous nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA) in CKD and on the importance of the nitric oxide synthases in kidney disease progression, particularly in diabetic nephropathy.

RECENT FINDINGS

The increased plasma ADMA seen in renal disease is generally predictive of severity of CKD progression and cardiovascular risk. However, some assumptions about the control of ADMA have been challenged: the primacy of the kidney as a metabolic organ for plasma ADMA regulation has come under scrutiny and the relative importance of the two isoforms of the ADMA-metabolizing enzymes dimethylarginine dimethylaminohydrolases (DDAHs) is being re-evaluated. Alterations in NOS also contribute to CKD progression with the endothelial isoform playing a major role in diabetic nephropathy.

SUMMARY

Improving our understanding of ADMA regulation is important since pharmacologic targeting of DDAH is underway. The major role of endothelial NOS-derived nitric oxide in diabetic nephropathy should lead to novel therapies. The beneficial actions of dietary nitrate supplementation on blood pressure and kidney disease are of considerable clinical relevance.

Association of NOS3 tag polymorphisms with hypoxic-ischemic encephalopathy

Aim

To test the association of NOS3 gene with hypoxic-ischemic encephalopathy (HIE).

Methods

The study included 110 unrelated term or preterm born children (69 boys and 41 girls) with HIE and 128 term and preterm born children (60 boys and 68 girls) without any neurological problems after the second year of life. Children with perinatal HIE fulfilled the diagnostic criteria for perinatal asphyxia. All children were admitted to the Clinical Hospital Split between 1992 and 2008. We analyzed 6 tagging single nucleotide polymorphisms (SNP) within NOS3 gene (rs3918186, rs3918188, rs1800783, rs1808593, rs3918227, rs1799983), in addition to previously confirmed NOS3-associated SNP rs1800779. Genotyping was conducted using real-time polymerase chain reaction (PCR). Association analyses were performed according to allelic and genotypic distribution.

Results

Allelic test did not show any SNP association with HIE. SNP rs1808593 showed genotype association (P = 0.008) and rs1800783-rs1800779 TG haplotype showed an association with HIE (P < 0.001). The study had 80% statistical power to detect (α = 0.05) an effect with odds ratio (OR) = 2.07 for rs3918186, OR = 1.69 for rs3918188, OR = 1.70 for rs1800783, OR = 1.80 for rs1808593, OR = 2.10 for rs3918227, OR = 1.68 for rs1800779, and OR = 1.76 for rs1799983, assuming an additive model.

Conclusion

Despite the limited number of HIE patients, we observed genotypic and haplotype associations of NOS3 polymorphisms with HIE.