Hypertensive nephrosclerosis in African Americans

Impact of Sleep Duration on Decline in Kidney Function in Adult Patients with Hypertension: A Community-Based Prospective Cohort Study

Background

Sleep duration is associated with various health conditions, including chronic kidney disease. However, the association between sleep duration and decline in kidney function in the South Korean population remains unclear. We aimed to investigate the impact of sleep duration on kidney function decline in adult patients with hypertension.

Methods

This cohort study was performed using data obtained from the Korean Genome and Epidemiology Study; 2,837 patients with hypertension who initially had normal kidney function were included. Glomerular filtration rates (GFRs) were estimated at baseline and throughout the 16 years of follow-up. A person was considered to have a decline in kidney function if they had a GFR <60 mL/min/1.73 m². Sleep duration data were obtained through interviewer-assisted questionnaires. Sleep durations were classified as short (<6 hours), normal (≥6 hours but <9 hours), and long (≥9 hours). The Cox proportional hazards model was applied, with adjustments for covariates.

Results

After adjusting for covariates, sleep duration was not associated with a decline in kidney function. However, among men with poorly controlled hypertension at baseline, compared to men with normal sleep durations, men with sleep durations <6 hours had a significantly higher risk of kidney function decline (hazard ratio, 1.56; 95% confidence interval, 1.02–2.36).

Conclusion

Short sleep duration did not seem to be associated with an increased risk of decline in kidney function; however, it may be a risk factor for the decline in kidney function in men with poorly controlled hypertension.

Improvement of the Safety Profile of Canaloplasty and Phacocanaloplasty: A Review of Complications and Their Management

Research on the methods used to achieve persistent and safe control of intraocular pressure resulted in the implementation of novel surgical procedures, such as canaloplasty and phacocanaloplasty. Herein, we review the literature focused on the safety profile of canaloplasty and phacocanaloplasty and the management of related complications. The aim of canaloplasty is to restore the natural aqueous outflow. This goal is achieved via a surgical procedure that involves viscocanalostomy with catheterisation of Schlemm's canal (360°) and placement of a circumferential suture that tensions the canal walls. This improves Schlemm's canal drainage, choroidoscleral flow, and subconjunctival filtration. The efficacy of canaloplasty for reducing the intraocular pressure is similar to those of trabeculectomy with mitomycin C and deep sclerectomy augmented with an implant and mitomycin C. However, canaloplasty is associated with a lower complication rate than those conventional techniques. Novel microsurgical techniques for the treatment of glaucoma are unlikely to replace the conventional methods. However, these new techniques offer alternatives, especially for patients who have an early indication for surgical intervention. Nevertheless, canaloplasty is associated with the expectations of efficient, safe, and modern surgical treatment.

Evidence of selection as a cause for racial disparities in fibroproliferative disease

Fibroproliferative diseases are common complex traits featuring scarring and overgrowth of connective tissue which vary widely in presentation because they affect many organ systems. Most fibroproliferative diseases are more prevalent in African-derived populations than in European populations, leading to pronounced health disparities. It is hypothesized that the increased prevalence of these diseases in African-derived populations is due to selection for pro-fibrotic alleles that are protective against helminth infections. We constructed a genetic risk score (GRS) of fibroproliferative disease risk-increasing alleles using 147 linkage disequilibrium-pruned variants identified through genome-wide association studies of seven fibroproliferative diseases with large African-European prevalence disparities. A comparison of the fibroproliferative disease GRS between 1000 Genomes Phase 3 populations detected a higher mean GRS in AFR (mean = 148 risk alleles) than EUR (mean = 136 risk alleles; T-test p-value = 1.75x10^-123). To test whether differences in GRS burden are systematic and may be due to selection, we employed the quantitative trait loci (QTL) sign test. The QTL sign test result indicates that population differences in risk-increasing allele burdens at these fibroproliferative disease variants are systematic and support a model featuring selective pressure (p-value = 0.011). These observations were replicated in an independent sample and were more statistically significant (T-test p-value = 7.26x10^-237, sign test p-value = 0.015). This evidence supports the role of selective pressure acting to increase frequency of fibroproliferative alleles in populations of African relative to European ancestry populations.

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.

Pleiotropic Effects of Immune Responses Explain Variation in the Prevalence of Fibroproliferative Diseases

Many diseases are differentially distributed among human populations. Differential selection on genetic variants in ancestral environments that coincidentally predispose to disease can be an underlying cause of these unequal prevalence patterns. Selected genes may be pleiotropic, affecting multiple phenotypes and resulting in more than one disease or trait. Patterns of pleiotropy may be helpful in understanding the underlying causes of an array of conditions in a population. For example, several fibroproliferative diseases are more prevalent and severe in populations of sub-Saharan ancestry. We propose that this disparity is due to selection for an enhanced Th2 response that confers resistance to helminthic infections, and concurrently increases susceptibility to fibrosis due to the profibrotic action of Th2 cytokines. Many studies on selection of Th2-related genes for host resistance to helminths have been reported, but the pleiotropic impact of this selection on the distribution of fibrotic disorders has not been explicitly investigated. We discuss the disproportionate occurrence of fibroproliferative diseases in individuals of African ancestry and provide evidence that adaptation of the immune system has shaped the genetic structure of these human populations in ways that alter the distribution of multiple fibroproliferative diseases.

Molecular mechanisms of renal blood flow autoregulation

Diabetes and hypertension are the leading causes of chronic kidney disease and their incidence is increasing at an alarming rate. Both are associated with impairments in the autoregulation of renal blood flow (RBF) and greater transmission of fluctuations in arterial pressure to the glomerular capillaries. The ability of the kidney to maintain relatively constant blood flow, glomerular filtration rate (GFR) and glomerular capillary pressure is mediated by the myogenic response of afferent arterioles working in concert with tubuloglomerular feedback that adjusts the tone of the afferent arteriole in response to changes in the delivery of sodium chloride to the macula densa. Despite intensive investigation, the factors initiating the myogenic response and the signaling pathways involved in the myogenic response and tubuloglomerular feedback remain uncertain. This review focuses on current thought regarding the molecular mechanisms underlying myogenic control of renal vascular tone, the interrelationships between the myogenic response and tubuloglomerular feedback, the evidence that alterations in autoregulation of RBF contributes to hypertension and diabetes-induced nephropathy and the identification of vascular therapeutic targets for improved renoprotection in hypertensive and diabetic patients.

Pattern of hypertensive kidney disease in a black Kenyan population

BACKGROUND

Hypertensive kidney disease is a major cause of morbidity and mortality. Its pattern displays geographical and ethnic variations. Data on these patterns are important for informing management and prevention strategies, but on Kenyans such data are scarce.

OBJECTIVE

By means of a retrospective study at Kenyatta National Hospital, Nairobi, we aimed to describe the pattern of hypertensive kidney disease in a black Kenyan population.

METHODS

Records of hypertensive patients who had impaired kidney function between January 2000 and December 2010 were examined for mode of diagnosis, age, gender, comorbid factors, treatment and outcome. Data were analyzed using the Statistical Package for Social Sciences, version 16.0 for Windows, and are presented using tables and bar charts.

RESULTS

A total of 114 cases (72 males, 42 females) were analyzed. The mean age was 42.7 years (range 12-83), peaking at 51-70 years. The male to female ratio was 1.7:1. Comorbid factors included left ventricular hypertrophy (21.1%), congestive heart failure (15.8%), alcohol (11.4%), cerebrovascular accidents, smoking and retinopathy (10.5% each). Multiple comorbid factors were present in 8.8% of the cases. The majority (52.6%) of the patients survived on hemodialysis, 8.8% underwent successful renal transplant and 22.8% died.

CONCLUSION

Hypertensive kidney disease affects all age groups, males more than females. It is commonly associated with other cardiovascular conditions and carries a high morbidity. Vigilant control of blood pressure is recommended.

How to treat hypertension in blacks: review of the evidence

Presentation, response to therapy, and clinical outcome differ according to race for patients with hypertension. Black patients have a higher prevalence and earlier onset of hypertension than other ethnic groups, with poorer prognosis than white patients. Blacks are more likely to be salt-sensitive, and to have a low plasma renin activity than are whites. They are at much greater risk of developing cardiovascular and renal complications. Despite many advances in the understanding and treatment of cardiovascular diseases, black patients continue to have increased morbidity and mortality from the end-organ complications of hypertension. The explanations for these observations remain incompletely understood, but genetic differences, added to socio-economic and environmental factors, have been proposed to explain this disparity. The first therapeutic approach is to decrease salt and increase potassium intakes. Diuretics (thiazides and potassium-sparing agents) and calcium channel blockers constitute the first antihypertensive drug choices. The angiotensin-converting-enzyme inhibitors, the angiotensin II receptor blockers and beta-blockers appear to be less effective in blacks with regard to uncomplicated hypertension, especially in older people, but addition of a small dose of diuretic improves their efficacy. These combinations are preferred among patients with chronic kidney disease or heart failure. The goal for blood pressure target is the same in blacks as it is in whites, being a blood pressure of less than 140/90 mmHg in uncomplicated hypertension and less than 130/80 mmHg in patients with diabetes mellitus or chronic kidney disease.

Role of inflammation in the development of renal damage and dysfunction in angiotensin II-induced hypertension

Angiotensin II (Ang II)-induced hypertension is associated with an inflammatory response that may contribute to the development of target organ damage. We tested the hypothesis that, in Ang II-induced hypertension, CC chemokine receptor 2 (CCR2) activation plays an important role in the development of renal fibrosis, damage, and dysfunction by causing oxidative stress, macrophage infiltration, and cell proliferation. To test this hypothesis, we used CCR2 knockout mice (CCR2-/-). The natural ligand of CCR2 is monocyte chemoattractant protein-1, a chemokine important for macrophage recruitment and activation. CCR2-/- and age-matched wild-type (CCR2+/+) C57BL/6J mice were infused continuously with either Ang II (5.2 ng/10 g per minute) or vehicle via osmotic minipumps for 2 or 4 weeks. Ang II infusion caused similar increases in systolic blood pressure and left ventricular hypertrophy in both strains of mice. However, in CCR2-/- mice with Ang II-induced hypertension, oxidative stress, macrophage infiltration, albuminuria, and renal damage were significantly decreased, and glomerular filtration rate was significantly higher than in CCR2+/+ mice. We concluded that, in Ang II-induced hypertension, CCR2 activation plays an important role in the development of hypertensive nephropathy via increased oxidative stress and inflammation.

Hypertension and kidney disease: a deadly connection

Kidney disease may be the cause or a consequence of hypertension. Hypertension affects 25% of the adult population in the United States. Similarly, chronic kidney disease (CKD) and end-stage renal disease (ESRD) have been steadily increasing in incidence because of the increasing age of the US population and rise in the incidence of risk factors, including hypertension. Substantial evidence supports the notion that elevated blood pressure is the most significant risk factor for developing CKD. Microalbuminuria has been shown to be the early marker of hypertensive renal disease. Furthermore, therapy to reduce microalbuminuria was associated with delayed progression of renal disease. Black Americans are at higher risk for developing hypertensive nephrosclerosis than whites. Hypertension is a major risk factor for cardiovascular events in patients with CKD and ESRD and those who have undergone renal transplantation. Studies have documented that elevated serum creatinine and CKD are risk factors for a cardiovascular event. Tight blood pressure control has been shown to reduce microalbuminuria and proteinuria and to delay progression of renal disease. Tailoring antihypertensive medication to the clinical setting to achieve a blood pressure goal is critical in reducing complications from this deadly connection.

Hypertension and kidney disease: A deadly connection

Kidney disease may be the cause or a consequence of hypertension. Hypertension affects 25% of the adult population in the United States. Similarly, chronic kidney disease (CKD) and end-stage renal disease (ESRD) have been steadily increasing in incidence because of the increasing age of the US population and rise in the incidence of risk factors, including hypertension. Substantial evidence supports the notion that elevated blood pressure is the most significant risk factor for the development of CKD. Microalbuminuria has been shown to be the early marker of hypertensive renal disease. Furthermore, therapy to reduce microalbuminuria was associated with delay in the progression of renal disease. Black Americans are at higher risk for developing hypertensive nephrosclerosis than whites. Hypertension is a major risk factor for cardiovascular events in patients with CKD and ESRD and those who have undergone renal transplantation. Studies have documented that elevated serum creatinine and CKD are risk factors for a cardiovascular event. Tight blood pressure control has been shown to reduce microalbuminuria and proteinuria and to delay progression of renal disease. Tailoring the choice of antihypertensive medication to the clinical setting to achieve a blood pressure goal is critical in reducing complications from this deadly connection.

Systemic and glomerular hypertension and progression of chronic renal disease: the dilemma of nephrosclerosis

The link between the kidney and hypertension has been considered a villain-victim relationship. High blood pressure levels are a well-recognized feature in chronic renal disease, but the ability of mild-to-moderate hypertension to produce renal insufficiency has been questioned. Nephrosclerosis, benign nephrosclerosis, and hypertensive kidney disease are terms that clinicians use when renal damage is thought to be secondary to essential hypertension. Many cases of end-stage renal disease are ascribed to so-called benign nephrosclerosis. This entity could actually be a primary renal disease affecting the preglomerular microvasculature, perhaps genetically mediated and ethnically influenced, and showing a heterogeneous clinical expression. African Americans suffer from nephrosclerosis more frequently than Caucasians. Nephrosclerosis affecting Caucasians seems to show a less aggressive pattern and could represent early age-related renal sclerosis. The risk of end-stage renal disease is increased when atherosclerotic lesions in large renal arteries coexist. Age, systolic blood pressure, proteinuria, and concomitant cardiovascular disease are well-known promoters of renal failure. A multifactorial strategy, including antihypertensive and antiproteinuric drugs, and lipid-lowering and anti-platelet agents, could improve cardiovascular and renal outcomes in patients with nephrosclerosis.

Progression of chronic kidney disease: can it be prevented or arrested?

Chronic kidney disease constitutes a highly prevalent health problem worldwide. Left untreated, it progresses inexorably to greater levels of severity at variable rates. The morbid impact of chronic kidney disease is heightened by its role as risk factor for cardiovascular disease. In the past two decades, considerable gains have been realized in retarding progression of chronic kidney disease by emphasizing blood pressure control and blockade of the renin-angiotensin system. Notwithstanding, the therapeutic goal of preventing or arresting chronic kidney disease progression remains unfulfilled. Currently attainable rates of decrease in glomerular filtration rate remain at 2 to 8 mL/min/y depending on the underlying disease. It is now believed that to achieve optimal therapeutic targets (proteinuria of <500 mg/day and decrease in glomerular filtration rate of 1 mL/min/y, the average age-related decline) we must introduce novel strategies and a multifaceted approach to treatment that interrupts multiple mechanisms of progression. To this end, and wherever relevant, new approaches to cause-specific treatment must be applied, such as targeted immunosuppression, intensive glycemic control, gene therapy, and enzyme replacement therapy. Furthermore, in all chronic kidney disease, we must interfere more effectively with the multitude of common mechanisms of progression. Established or putative, such approaches include aggressive blood pressure control; advanced renin-angiotensin system blockade; cytokine modulation and antifibrotic therapy; aldosterone blockade; endothelin blockade, nitric oxide modulation and vasopeptidase inhibition; antioxidant therapy; statin therapy; glycosaminoglycan therapy; anemia therapy; dietary restrictions; lifestyle changes; and pharmacogenomic profiling. Such a concerted, multifaceted approach to management might indeed prevent or arrest progression of chronic kidney disease, or even achieve regression of chronic kidney disease.

Hypertension and the Kidney

Hypertension is an important and widely prevalent risk factor for the development of chronic kidney disease (CKD), which unfortunately may progress to end-stage renal disease. CKD is a progressive condition that causes significant morbidity and mortality. Diabetes is the leading cause of end-stage renal disease in the Western world. Both hypertension and diabetes are the causative factors for the occurrence of CKD and its consequences. Aggressive control of hypertension and diabetes is indicated to reduce the risk for kidney disease in the community. Certainly, effective control of hypertension is a proven modality to prevent renal disease. The concept of decreasing the systemic blood pressure as well as the intraglomerular pressure has led to the application of rational therapeutic options in patients with renal insufficiency. Although treatment of hypertension alone is critical, drugs that block the renin-angiotensin system have been shown to have special renal (and cardiovascular) benefits. Early detection and treatment of microalbuminuria is an integral part of disease management. This article reviews the pathophysiologic and therapeutic implications of the link between hypertension and the kidney.

Hypothesis: obesity and the insulin resistance syndrome play a major role in end-stage renal failure attributed to hypertension and labelled 'hypertensive nephrosclerosis'

About a third of new cases of renal failure in USA are attributed to hypertension despite controversy about the frequency and pathology of so called hypertensive nephrosclerosis. In spite of good documentation that obesity causes renal failure and in spite of the global epidemic of obesity this diagnosis does not feature on most renal failure registries. New documentation that progressive renal failure in hypertension is linked to insulin resistance and analysis of NHANES III data which shows a strong positive significant dose-response relationship between insulin resistance and chronic kidney disease strengthen the view that so called hypertensive nephrosclerosis may be linked more closely to obesity and insulin resistance than to blood pressure. The pathology of the kidney in hypertension has changed. Studies 50 years ago did not show segmental glomerulosclerosis, which has recently been shown to be the key lesion in hypertensive nephrosclerosis. Recent documentation that this is a major mechanism of progression in hypertension together with the fact that similar segmental glomerulosclerosis is the key lesion in obesity and the metabolic syndrome suggests that these factors are more important than hypertension in renal failure attributed to hypertensive nephrosclerosis.