Endothelial nitric oxide synthase gene expression is associated with hypertension in autosomal dominant polycystic kidney disease

Cardiac Localized Polycystin-2 plays a Functional Role in Natriuretic Peptide Production and its Absence Contributes to Hypertension

Cardiovascular complications are the most common cause of mortality in patients with autosomal dominant polycystic kidney disease (ADPKD). Hypertension is seen in 70% of patients by the age of 30 prior to decline in kidney function. The natriuretic peptides (NPs), atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), are released by cardiomyocytes in response to membrane stretch, increasing urinary excretion of sodium and water. Mice heterozygous for Pkd2 have attenuated NP responses and we hypothesized that cardiomyocyte-localized polycystin proteins contribute to production of NPs. Cardiomyocyte-specific knock-out models of polycystin-2 (PC2), one of the causative genes of ADPKD, demonstrate diurnal hypertension. These mice have decreased ANP and BNP expression in the left ventricle. Analysis of the pathways involved in production, maturation, and activity of NPs identified decreased transcription of CgB, PCSK6, and NFAT genes in cPC2-KOs. Engineered heart tissue with human iPSCs driven into cardiomyocytes with CRISPR/Cas9 KO of PKD2 failed to produce ANP. These results suggest that PC2 in cardiomyocytes are involved in NP production and lack of cardiac PC2 predisposes to a hypertensive volume expanded phenotype, which may contribute to the development of hypertension in ADPKD.

NOS3 gene intron 4 a/b polymorphism is associated with ESRD in autosomal dominant polycystic kidney disease patients

Introduction:

Endothelial nitric oxide synthase (eNOS) genes have been implicated in renal hemodynamics as potent regulators of vascular tone and blood pressure. It has been linked to a reduction in plasma nitric oxide levels. Several studies have recently been conducted to investigate the role of NOS3 gene polymorphisms and end-stage renal disease (ESRD). However, the results are still unclear and the mechanisms are not fully defined. As a result, we conducted a meta-analysis to examine the relationship between NOS3 gene polymorphism and ESRD in autosomal polycystic kidney disease (ADPKD) patients.

Methods:

To assess the relationship between NOS3 gene polymorphism and ESRD, relevant studies published between September 2002 and December 2020 were retrieved from the PubMed (Medline), EMBASE, Google Scholar, and Web of Science databases. The pooled odds ratio (OR) and 95 % confidence interval (CI) were calculated using a fixed-effect model. To assess the heterogeneity of studies, we used Cochrane’s Q test and the Higgins and Thompson I² statistics.

Results:

Our meta-analysis of 13 studies showed that the presence of the two NOS3 gene polymorphisms significantly increased ESRD risk in ADPKD patients with 4a/b gene polymorphism (aa+ab vs. bb: OR=1.95, 95% CI=1.24-3.09, p=0.004). In addition, no significant association was found between the NOS3 894G>T (Glu298Asp) polymorphism and the risk of ESRD in ADPKD patients (GT+TT vs. GG: OR=1.21, 95% CI=0.93-1.58, p=0.157). There was no evidence of publication bias.

Conclusions:

The findings of the current meta-analysis suggest that NOS3 intron 4a/b polymorphism plays a vital role in the increasing risk of ESRD in ADPKD patients.

Polycystins, ADPKD, and Cardiovascular Disease

Cardiovascular disorders are the most common cause of mortality in autosomal dominant polycystic kidney disease (ADPKD). This review considers recent clinical and basic science studies that address the contributing factors of cardiovascular dysfunction in ADPKD. In particular, attention is placed on how dysfunction of the polycystin proteins located in the cardiovascular system contributes to extrarenal manifestations of ADPKD.

Association of OSR-1 With Vascular Dysfunction and Hypertension in Polycystic Kidney Disease

Autosomal-dominant polycystic kidney disease (ADPKD) is associated with oxidative stress and hypertension development before renal function decline and cardiovascular disease development. Oxidative stress-responsive kinase-1 (OSR-1) participates in the signaling regulating Na⁺ transport during oxidative stress and also plays a role in the regulation of cell volume and blood pressure. Therefore, we aimed to investigate the potential role of OSR-1 in ADPKD patients. Eighty ADPKD patients, 80 healthy controls, and 80 non-ADPKD patients with hypertension were enrolled in this cross-sectional study. Twenty-four-hour ambulatory blood pressure monitoring was conducted in all participants. Blood samples were taken after 12-h fasting for the measurement of biochemical parameters and OSR-1 gene expression. Vascular dysfunction was assessed using ischemia-induced forearm flow-mediated vasodilation (FMD). Briefly, of the 80 ADPKD patients, 41(51%) were male, and 53(66%) of them were hypertensive. The mean age of the 80 controls was 35.3 ± 12.6 years, and 37(46%) of them were male. The mean age of the 80 non-ADPKD patients with hypertension was 44.6 ± 11.9 years, and 38(47.5) of them were male. There were significant differences in serum OSR-1 gene expression between the ADPKD patients and the control subjects. Serum OSR-1 gene expression was also significantly increased in hypertensive ADPKD patients in comparison with both normotensive ADPKD counterparts and non-ADPKD hypertensive subjects. Serum OSR-1 gene expression was increased in patients with ADPKD than healthy subjects. Low estimated glomerular filtration rate (eGFR), OSR-1 gene expression, total kidney volume (TKV), and high-density lipoprotein (HDL) were also independently associated with hypertension in ADPKD patients.

Relationship of genetic factors with development of aortic dissection and aneurysm

Background

This study aims to investigate the relationship between the development of aortic dissections and aneurysms with the polymorphisms of angiotensin converting enzyme gene, methylenetetrahydrofolate reductase gene, plasminogen activator inhibitor-1 gene, and nitric oxide synthase gene.

Methods

Between April 2009 and July 2014, 38 patients with aortic dissections (28 males, 10 females; mean age 55.1±10.7 years; range, 30 to 78 years) and 67 patients with aortic aneurysms (57 males, 10 females; mean age 63.0±11.4 years; range, 31 to 82 years) were included in this cross-sectional study. The control group consisted of 60 healthy volunteers (41 males, 19 females; mean age 56.3±11.2 years; range, 30 to 82 years) without an aortic aneurysm or dissection, as assessed by thoracoabdominal computed tomography. The prespecified four genes were genotyped with competitive allelespecific polymerase chain reaction.

Results

The aortic dissection group had higher nitric oxide synthase-3 (4b/4b) expression levels, compared to the control group. The aortic aneurysm group had also higher nitric oxide synthase-3 (4b/4a) expression levels, compared to the control group. Compared to the control group, a higher rate of angiotensin converting enzyme I/D gene polymorphism was detected in the aneurysm group, while higher D/D polymorphism rates were found in the dissection group; although not statistically significant.

Conclusion

Our study results suggest that the nitric oxide synthase-3 intron 4b/4b and nitric oxide synthase-3 intron 4b/4a gene polymorphisms can be used as a predictor of aortic dissection and aneurysm development.

Insulin Resistance in Kidney Disease: Is There a Distinct Role Separate from That of Diabetes or Obesity?

Insulin resistance is a central component of the metabolic dysregulation observed in obesity, which puts one at risk for the development of type 2 diabetes and complications related to diabetes such as chronic kidney disease. Insulin resistance and compensatory hyperinsulinemia place one at risk for other risk factors such as dyslipidemia, hypertension, and proteinuria, e.g., development of kidney disease. Our traditional view of insulin actions focuses on insulin-sensitive tissues such as skeletal muscle, liver, adipose tissue, and the pancreas. However, insulin also has distinct actions in kidney tissue that regulate growth, hypertrophy, as well as microcirculatory and fibrotic pathways which, in turn, impact glomerular filtration, including that governed by tubuloglomerular feedback. However, it is often difficult to discern the distinct effects of excess circulating insulin and impaired insulin actions, as exist in the insulin resistance individual, from the associated effects of obesity or elevated systolic blood pressure on the development and progression of kidney disease over time. Therefore, we review the experimental and clinical evidence for the distinct impact of insulin resistance on kidney function and disease.

A role of the endothelial nitric oxide system in acute renal colic caused by ureteral stone

BACKGROUND AND AIMS

Endothelial nitric oxide synthase gene polymorphisms play a role in some pathophysiological processes. In this study, the possible effects of endothelial nitric oxide synthase gene polymorphisms on ureteral stone disease in patients who were admitted to the emergency department with severe pain due to renal colic are examined.

MATERIALS AND METHODS

The study groups were designed as controls and patients. The control group was formed from the healthy volunteers who applied to the blood center next to the emergency service. The patient group comprised patients who were diagnosed with ureteral stone disease with severe pain. All of the genetic studies were based on extracted peripheral blood samples using the necessary procedures from the Genome and Stem Cell Center at Erciyes University (GENKOK). The data were analyzed with SPSS (IBM, ver 20, United Sate).

RESULTS

The study group comprised 62 females and 138 males, and the control group comprised 64 females and 136 males. All of the stones that caused renal colic were found to be localized in the ureters and the ureterovesical junction. The genotypes of the intron 4 polymorphism were found to be as follows: 4a/4a in 10 people, 4b/4a in 115, and 4b/4b in 275 people. The GG genotype of the eNOS-G894T polymorphism was found in 108 patients in the study group and in117 of the healthy individuals. There was no statistically significant difference between the two groups regarding these data.

CONCLUSION

Although this study is the first in the literature to examine the relationship between renal colic and endothelial nitric oxide synthase gene polymorphisms, our study demonstrated that no relation was found.

Altered Nitric Oxide System in Cardiovascular and Renal Diseases

Nitric oxide (NO) is synthesized by a family of NO synthases (NOS), including neuronal, inducible, and endothelial NOS (n/i/eNOS). NO-mediated effects can be beneficial or harmful depending on the specific risk factors affecting the disease. In hypertension, the vascular relaxation response to acetylcholine is blunted, and that to direct NO donors is maintained. A reduction in the activity of eNOS is mainly responsible for the elevation of blood pressure, and an abnormal expression of iNOS is likely to be related to the progression of vascular dysfunction. While eNOS/nNOS-derived NO is protective against the development of atherosclerosis, iNOS-derived NO may be proatherogenic. eNOS-derived NO may prevent the progression of myocardial infarction. Myocardial ischemia/reperfusion injury is significantly enhanced in eNOS-deficient animals. An important component of heart failure is the loss of coronary vascular eNOS activity. A pressure-overload may cause severer left ventricular hypertrophy and dysfunction in eNOS null mice than in wild-type mice. iNOS-derived NO has detrimental effects on the myocardium. NO plays an important role in regulating the angiogenesis and slowing the interstitial fibrosis of the obstructed kidney. In unilateral ureteral obstruction, the expression of eNOS was decreased in the affected kidney. In triply n/i/eNOS null mice, nephrogenic diabetes insipidus developed along with reduced aquaporin-2 abundance. In chronic kidney disease model of subtotal-nephrectomized rats, treatment with NOS inhibitors decreased systemic NO production and induced left ventricular systolic dysfunction (renocardiac syndrome).

The functions of TRPP2 in the vascular system

TRPP2 (polycystin-2, PC2 or PKD2), encoded by the PKD2 gene, is a non-selective cation channel with a large single channel conductance and high Ca(2+) permeability. In cell membrane, TRPP2, along with polycystin-1, TRPV4 and TRPC1, functions as a mechanotransduction channel. In the endoplasmic reticulum, TRPP2 modulates intracellular Ca(2+) release associated with IP3 receptors and the ryanodine receptors. Noteworthily, TRPP2 is widely expressed in vascular endothelial and smooth muscle cells of all major vascular beds, and contributes to the regulation of vessel function. The mutation of the PKD2 gene is a major cause of autosomal dominant polycystic kidney disease (ADPKD), which is not only a common genetic disease of the kidney but also a systemic disorder associated with abnormalities in the vasculature; cardiovascular complications are the leading cause of mortality and morbidity in ADPKD patients. This review provides an overview of the current knowledge regarding the TRPP2 protein and its possible role in cardiovascular function and related diseases.

Correlation between polymorphism of endothelial nitric oxide synthase and avascular necrosis of femoral head

OBJECTIVE

We analyzed the correlation between mutation in intron 4 and exon 7 of endothelial nitric oxide synthase (eNOS) and avascular necrosis of femoral head (ANFH).

METHOD

A total of 260 ANFH cases without history of hip joint injuries were diagnosed and subject to staging according to Ficat standard, with 262 health subjects as control. Venous blood was collected to extract genome DNA, which was then amplified by PCR. The polymorphism of 27 bp repeat sequence in intron 4 and G894T polymorphism in exon 7 of eNOS gene was detected.

RESULTS

The b/b, b/a and a/a genotype frequency of intron 4 was 77.7%, 19.2% and 3.1% in ANFH group, respectively, and that in the control group was 58.0%, 32.8% and 9.2%, respectively. The b allele frequency in ANFH group was obviously higher than that in the control (P<0.0001). The frequency of 894 G/G wild type, G/T heterozygote and T/T homozygote in eNOS exon 7 was analyzed by PCR-RLFP: 65.4%, 26.5% and 8.1% in ANFH group, and 46.2%, 37.8% and 16% in normal control, respectively. The frequency of TT genotype in ANFH was obviously higher than that in the control group (P<0.001).

CONCLUSION

Polymorphism of eNOS was correlated with ANFH.

An overview of experimental and early investigational therapies for the treatment of polycystic kidney disease

INTRODUCTION

At present, treatment of autosomal dominant polycystic kidney disease (ADPKD) is essentially supportive as there is still no specific therapy. However, recent advances with ADPKD pathophysiology have stimulated research for new therapeutic strategies.

AREAS COVERED

The aim of this systematic review is to analyze the experimental and early investigational therapies currently under evaluation in this field. Data from completed clinical trials were retrieved from the currently available scientific literature and from the ClinicalTrials.gov website.

EXPERT OPINION

Among the drugs currently being explored, mammalian target of rapamycin inhibitors reduce kidney volume enlargement but their role remains uncertain. The most promising drug is the V2 receptor antagonist tolvaptan, which reduces the increased rate of total kidney volume and slows down glomerular filtration rate decline. The main candidates for the treatment of cysts growth, both in the kidney and in the liver whenever present, are the somatostatin analogues, such as lanreotide and octreotide and more recently pasireotide. As for other therapies, some favorable results have been achieved but data are still not sufficient to establish if these approaches may be beneficial in slowing ADPKD progression in the future.