Primary hypertension and nephropathy

Combined exposure to multiple dioxins and dioxin-like polychlorinated biphenyls on hypertension among US adults in NHANES: a cross-sectional study under three statistical models

Dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) are mainly released as by-products of human activities, often in the form of mixtures, and the potential harm on human health deserves attention. Therefore, our study aimed to analyze the combined effect of dioxins and DL-PCB exposures on hypertension (HTN) among US adults. Data of eligible participants were acquired from the National Health and Nutrition Examination Survey (NHANES). Multiple logistic regression models with adjustment for covariates were applied to explore the associations between 13 persistent organic pollutants (POPs) and HTN. Stratified analyses and interaction analyses were then conducted by age and gender. Finally, the combined effects of dioxins and DL-PCBs on HTN were assessed by the weighted quantile sum (WQS) model and the Bayesian kernel machine regression (BKMR) model. A total of 976 adults were included in our study, of whom 397 had HTN. Spearman correlations indicated positive correlations among 13 POPs. And most of them (except PCB28, PCB66, and 1,2,3,4,7,8,9-hpcdf) had significant effects on HTN. The result of WQS revealed that mixed exposure to dioxins and DL-PCBs was significantly associated with increased risk of HTN (OR: 2.205; 95% CIs: 1.555, 3.127). The BKMR model also presented a positive trend of HTN risk with exposure to multiple dioxins and DL-PCBs. And 1,2,3,4,6,7,8,9-ocdd may be the main factor for this positive association. Considering the limitations of our cross-sectional study with the small sample, further prospective studies are necessary to validate our findings.

Rare Variants in Genes Encoding Subunits of the Epithelial Na+ Channel Are Associated With Blood Pressure and Kidney Function

BACKGROUND

The epithelial Na+ channel (ENaC) is intrinsically linked to fluid volume homeostasis and blood pressure. Specific rare mutations in SCNN1A, SCNN1B, and SCNN1G, genes encoding the α, β, and γ subunits of ENaC, respectively, are associated with extreme blood pressure phenotypes. No associations between blood pressure and SCNN1D, which encodes the δ subunit of ENaC, have been reported. A small number of sequence variants in ENaC subunits have been reported to affect functional transport in vitro or blood pressure. The effects of the vast majority of rare and low-frequency ENaC variants on blood pressure are not known.

METHODS

We explored the association of low frequency and rare variants in the genes encoding ENaC subunits, with systolic blood pressure, diastolic blood pressure, mean arterial pressure, and pulse pressure. Using whole-genome sequencing data from 14 studies participating in the Trans-Omics in Precision Medicine Whole-Genome Sequencing Program, and sequence kernel association tests.

RESULTS

We found that variants in SCNN1A and SCNN1B were associated with diastolic blood pressure and mean arterial pressure (P<0.00625). Although SCNN1D is poorly expressed in human kidney tissue, SCNN1D variants were associated with systolic blood pressure, diastolic blood pressure, mean arterial pressure, and pulse pressure (P<0.00625). ENaC variants in 2 of the 4 subunits (SCNN1B and SCNN1D) were also associated with estimated glomerular filtration rate (P<0.00625), but not with stroke.

CONCLUSIONS

Our results suggest that variants in extrarenal ENaCs, in addition to ENaCs expressed in kidneys, influence blood pressure and kidney function.

Diabetes mellitus and hearing loss: A review

Diabetes (type 2) and sensorineural hearing loss are common health problems manifested with ageing. While both type 1 and type 2 diabetes have been associated with hearing loss, a causal link has been difficult to establish. Individuals with diabetes have twice the incidence of hearing loss compared to those without diabetes and those with prediabetes have a 30% higher rate of hearing loss. Whether hearing loss is associated with diabetes independent of glycemic control remains to be determined. Hearing loss has its own set of risk factors and shares others with diabetes. This review will summarize the complex relationship between diabetes and sensorineural hearing loss.

Superresolving the kidney-a practical comparison of fluorescence nanoscopy of the glomerular filtration barrier

Immunofluorescence microscopy is routinely used in the diagnosis of and research on renal impairments. However, this highly specific technique is restricted in its maximum resolution to about 250 nm in the lateral and 700 nm in the axial directions and thus not sufficient to investigate the fine subcellular structure of the kidney's glomerular filtration barrier. In contrast, electron microscopy offers high resolution, but this comes at the cost of poor preservation of immunogenic epitopes and antibody penetration alongside a low throughput. Many of these drawbacks were overcome with the advent of super-resolution microscopy methods. So far, four different super-resolution approaches have been used to study the kidney: single-molecule localization microscopy (SMLM), stimulated emission depletion (STED) microscopy, structured illumination microscopy (SIM), and expansion microscopy (ExM), however, using different preservation methods and widely varying labelling strategies. In this work, all four methods were applied and critically compared on kidney slices obtained from samples treated with the most commonly used preservation technique: fixation by formalin and embedding in paraffin (FFPE). Strengths and weaknesses, as well as the practicalities of each method, are discussed to enable users of super-resolution microscopy in renal research make an informed decision on the best choice of technique. The methods discussed enable the efficient investigation of biopsies stored in kidney banks around the world. Graphical abstract.

Therapeutic potentials of mesenchymal stem cells on the renal cortex of experimentally induced hypertensive albino rats: Relevant role of Nrf2

Bone marrow derived-mesenchymal stem cells (BM-MSCs) have brought great attention in regenerative medicine field, various experimental & clinical trials were held to investigate their therapeutic effects in different disorders. We designed a histological & immunohistochemical study to evaluate effectiveness of MSCs therapy in withhold of end-stage renal disease (ESRD) secondary to hypertension which has become a growing & striking public health problem. 30 adult male albino rats were utilized, 20 of them were exposed to experimental induction of hypertension, then divided equally to MSCs treated group (injected with 1×10⁶ fluorescent labeled cell i.v./rat), while the second one was left without treatment. Renal specimens were subjected to histopathological, ultrastructural and immunohistochemical examination for Nrf2 in addition to biochemical estimation of serum urea & creatinine. Our results documented that BM-derived MSCs exerts considerable reversing effect of histopathologic and ultrastructural hypertensive nephropathy. Moreover, immunohistochemical results clearly pointed to relevant role of Nrf2 pathway in MSCs related renal therapeutic effects.

Rate of change in renal function and mortality in elderly treated hypertensive patients

BACKGROUND AND OBJECTIVES

Evidence relating the rate of change in renal function, measured as eGFR, after antihypertensive treatment in elderly patients to clinical outcome is sparse. This study characterized the rate of change in eGFR after commencement of antihypertensive treatment in an elderly population, the factors associated with eGFR rate change, and the rate's association with all-cause and cardiovascular mortality.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from the Second Australian National Blood Pressure study were used, where 6083 hypertensive participants aged ≥65 years were enrolled during 1995-1997 and followed for a median of 4.1 years (in-trial). Following the Second Australian National Blood Pressure study, participants were followed-up for a further median 6.9 years (post-trial). The annual rate of change in the eGFR was calculated in 4940 participants using creatinine measurements during the in-trial period and classified into quintiles (Q) on the basis of the following eGFR changes: rapid decline (Q1), decline (Q2), stable (Q3), increase (Q4), and rapid increase (Q5).

RESULTS

A rapid decline in eGFR in comparison with those with stable eGFRs during the in-trial period was associated with older age, living in a rural area, wider pulse pressure at baseline, receiving diuretic-based therapy, taking multiple antihypertensive drugs, and having blood pressure <140/90 mmHg during the study. However, a rapid increase in eGFR was observed in younger women and those with a higher cholesterol level. After adjustment for baseline and in-trial covariates, Cox-proportional hazard models showed a significantly greater risk for both all-cause (hazard ratio, 1.28; 95% confidence interval, 1.09 to 1.52; P=0.003) and cardiovascular (hazard ratio, 1.40; 95% confidence interval, 1.11 to 1.76; P=0.004) mortality in the rapid decline group compared with the stable group over a median of 7.2 years after the last eGFR measure. No significant association with mortality was observed for a rapid increase in eGFR.

CONCLUSIONS

In elderly persons with treated hypertension, a rapid decline in eGFR is associated with a higher risk of mortality.

Antihypertensive medication use and change in kidney function in elderly adults: a marginal structural model analysis

BACKGROUND

The evidence for the effectiveness of antihypertensive medication use for slowing decline in kidney function in older persons is sparse. We addressed this research question by the application of novel methods in a marginal structural model.

METHODS

Change in kidney function was measured by two or more measures of cystatin C in 1,576 hypertensive participants in the Cardiovascular Health Study over 7 years of follow-up (1989-1997 in four U.S. communities). The exposure of interest was antihypertensive medication use. We used a novel estimator in a marginal structural model to account for bias due to confounding and informative censoring.

RESULTS

The mean annual decline in eGFR was 2.41 ± 4.91 mL/min/1.73 m(2). In unadjusted analysis, antihypertensive medication use was not associated with annual change in kidney function. Traditional multivariable regression did not substantially change these estimates. Based on a marginal structural analysis, persons on antihypertensives had slower declines in kidney function; participants had an estimated 0.88 (0.13, 1.63) ml/min/1.73 m(2) per year slower decline in eGFR compared with persons on no treatment. In a model that also accounted for bias due to informative censoring, the estimate for the treatment effect was 2.23 (-0.13, 4.59) ml/min/1.73 m(2) per year slower decline in eGFR.

CONCLUSION

In summary, estimates from a marginal structural model suggested that antihypertensive therapy was associated with preserved kidney function in hypertensive elderly adults. Confirmatory studies may provide power to determine the strength and validity of the findings.

Higher peripheral neutrophil and monocyte counts are independent indicators of the presence and severity of proteinuria in apparently normal adults

BACKGROUND

Proteinuria reflects disrupted renal function in which enhanced immuno-inflammation activity plays a key role. So far, information concerning the relations between proteinuria and peripheral different leucocyte counts is limited. We thereby conducted this study aiming to obtain comprehensive information of the issue.

METHODS

Study subjects were participants of a health check programme from 2000 to 2002. Additional two enrolment criteria were (i) leucocyte analysis was checked with a same blood cell counter and (ii) urinalysis showed no pyuria or haematuria. Data of subjects were retrospectively collected and analysed by using sas program.

RESULTS

Higher neutrophil and monocyte counts, but not lymphocyte count, were significantly associated with both the presence and the severity of proteinuria (all P < 0.0001, n= 12 225). Such associations maintained significant after adjustments of age, sex, body mass index, mean blood pressure and blood levels of glycosylated hemoglobin (HbA1c), total cholesterol, triglycerides and creatinine (all P< or = 0.001, n= 12 225). There was a sharp increase in the incidence of proteinuria in association with a neutrophil count > or =4.50 x 10(9)/L (P< or = 0.0001).

CONCLUSION

Our study showed that in apparently normal adults the presence and the severity of proteinuria could be reflected by the peripheral neutrophil and monocyte counts, but not the lymphocyte count. These findings, together with the documented inflammatory basis of proteinuria and the diverse pathophysiological roles of differential leucocytes, suggest that peripheral differential leucocyte counting may be useful in predicting the course of an existing proteinuria. Perspective longitudinal follow-up studies are needed to test this presumption.

Etiopathology of chronic tubular, glomerular and renovascular nephropathies: clinical implications

Chronic kidney disease (CKD) comprises a group of pathologies in which the renal excretory function is chronically compromised. Most, but not all, forms of CKD are progressive and irreversible, pathological syndromes that start silently (i.e. no functional alterations are evident), continue through renal dysfunction and ends up in renal failure. At this point, kidney transplant or dialysis (renal replacement therapy, RRT) becomes necessary to prevent death derived from the inability of the kidneys to cleanse the blood and achieve hydroelectrolytic balance. Worldwide, nearly 1.5 million people need RRT, and the incidence of CKD has increased significantly over the last decades. Diabetes and hypertension are among the leading causes of end stage renal disease, although autoimmunity, renal atherosclerosis, certain infections, drugs and toxins, obstruction of the urinary tract, genetic alterations, and other insults may initiate the disease by damaging the glomerular, tubular, vascular or interstitial compartments of the kidneys. In all cases, CKD eventually compromises all these structures and gives rise to a similar phenotype regardless of etiology. This review describes with an integrative approach the pathophysiological process of tubulointerstitial, glomerular and renovascular diseases, and makes emphasis on the key cellular and molecular events involved. It further analyses the key mechanisms leading to a merging phenotype and pathophysiological scenario as etiologically distinct diseases progress. Finally clinical implications and future experimental and therapeutic perspectives are discussed.

Renal function recovery in chronic dialysis patients

Renal function recovery (RFR) from acute kidney injury requiring dialysis occurs at a high frequency. RFR from chronic dialysis, on the other hand, is an uncommon but well-recognized phenomenon, occurring at a rate of 1.0-2.4% according to data from large observational studies. The underlying etiology of renal failure is the single most important predicting factor of RFR in chronic dialysis patients. The disease types with the highest RFR rates are atheroembolic renal disease, systemic autoimmune disease, renovascular diseases, and scleroderma. The disease types with the lowest RFR rates are diabetic nephropathy and cystic kidney disease. Initial dialysis modality does not appear to influence RFR. Careful observation and history taking are needed to recognize the often nonspecific clinical and laboratory signs of RFR. When RFR is suspected in a chronic dialysis patient, a 24-hour urine urea and creatinine clearance should be measured. Based on the renal clearance, along with other clinical factors, the dialysis prescription may be gradually reduced until a complete discontinuation of dialysis. After RFR from maintenance dialysis, patients require close follow-up in an office setting for chronic kidney disease management.

[Hypertension and the kidney]

Hypertension and proteinuria are common risk factors for cardiovascular morbidity and mortality, as well as for the progression of renal disease. Renal functional impairment represents an independent cardiovascular risk factor by itself. Strict antihypertensive therapy and measures to maximally reduce proteinuria can substantially improve the prognosis of renal patients. This review summarizes current evidence for the role of hypertension and proteinuria with regard to renal and cardiovascular outcomes and for the importance of intensive antihypertensive and anti-proteinuric measures.

Angiotensin receptor blockers: RAAS blockade and renoprotection

INTRODUCTION

Chronic kidney disease (CKD) is an increasingly prevalent public health concern and is associated with a high risk of adverse cardiovascular outcomes. Renal impairment is frequently associated with hypertension and there is compelling evidence of the benefits of antihypertensive therapy for reducing progression of kidney disease. The central role of the renin-angiotensin-aldosterone system (RAAS) in hypertension and renal disease has led to interest in the ability of RAAS-blocking agents to provide benefits beyond blood pressure control.

SCOPE

This review explores the mechanisms involved in CKD development, assesses markers of CKD progression, explores the role of the RAAS in renal disease, and examines RAAS blockade as a therapeutic option for renoprotection. For this purpose, a non-systematic literature review was conducted using the Medline database.

FINDINGS

Studies in patients with diabetic renal disease have shown that RAAS blockade with angiotensin converting enzyme (ACE)-inhibitors or angiotensin receptor blockers (ARBs) reduces progression of renal disease. Similarly, several studies have demonstrated the benefits of ACE inhibitors in non-diabetic renal disease, although few studies have been conducted with ARBs in this setting. At present, there is little evidence to determine the relative merits of ARBs and ACE inhibitors in terms of clinical outcomes, although ARBs appear to have advantages in terms of renal haemodynamics and measures of renal function.

CONCLUSIONS

The beneficial effects of ARBs, which result from a combination of antihypertensive, haemodynamic, antiproteinuric and pleiotropic mechanisms, provide a strong rationale for considering the use of these agents in the treatment of high-risk patients.

N-acetyltransferase 8, a positional candidate for blood pressure and renal regulation: resequencing, association and in silico study

BACKGROUND

Kidneys have an important function in blood pressure (BP) regulation and elevated BP may lead to kidney failure. Chr2p12-p13 region linked to BP traits in multiple studies harbours a potential candidate for BP and renal function, N-acetyltransferase 8 (NAT8) expressed in embryonic and adult kidney and associated with nephrotoxicity response.

METHODS/RESULTS

We report the first study exploring NAT8 as a potential candidate gene for blood pressure and kidney function. The resequencing (n = 42, random Estonian samples) identified 15 NAT8 polymorphisms, including 6 novel variants. The diversity of NAT8 5' upstream region (pi/bp = 0.00320) exceeded up to 10 times the variation in the NAT8 genic region (pi/bp = 0.00037) as well as the average variation (pi/bp = 0.00040) for the promoters of 29 reference genes associated with hypertension. We suggest that a potential source for such high variation could be an active gene conversion process from NAT8B duplicate gene to NAT8. Similarly to NAT8, several reference genes with the most variable upstream regions have also duplicate copies. The NAT8 promoter SNPs were targeted with pilot quantitative association studies for blood pressure (n = 137, healthy unrelated individuals) and for the index of kidney function - estimated glomerular filtration rate (eGFR; n = 157 hypertensives with and without nephropathy). Minor alleles of these polymorphisms revealed a significant protective effect against elevated systolic BP as well as kidney failure in hypertension patients (p < 0.05; linear regression model, addictive effect).

CONCLUSION

The full resequencing and pilot association study of a novel positional candidate gene for blood pressure and renal function, human N-acetyltransferase 8, suggested a contribution of highly variable NAT8 promoter polymorphisms in determination of systolic blood pressure and eGFR. Based on in silico analysis, we raise the hypothesis that the alternative SNP alleles of the NAT8 upstream region may have differential effect on gene expression.

Telomere dysfunction in hypertension

Aging is a major risk factor for hypertension and associated cardiovascular disease. In most proliferative tissues, aging is characterized by shortening of the DNA component of telomeres, the specialized genetic segments that cap the end of eukaryotic chromosomes and protect them from end-to-end fusions. By inducing genomic instability, replicative senescence and apoptosis, telomere shortening is thought to contribute to organismal aging and to the development of age-related diseases. Here, we review animal and human studies that have investigated the possible links between telomere ablation and the pathogenesis of hypertension and related target organ damage. Although evidence is mounting that alterations in telomerase activity and telomere shortening may play a role in the pathogenesis of hypertension, additional studies are required to understand the molecular mechanisms by which telomere dysfunction and hypertension are functionally connected. As our knowledge on this emerging field grows, the challenge will be to ascertain whether all this information might translate into clinical applications.