Sympathetic activation in chronic kidney disease: out of the shadow

Prognostic Value of Cardio-Ankle Vascular Index for Cardiovascular and Kidney Outcomes: Systematic Review and Meta-Analysis

Background

Arterial stiffness causes cardiovascular disease and target-organ damage. Carotid-femoral pulse wave velocity is regarded as a standard arterial stiffness metric. However, the prognostic value of cardio-ankle vascular index (CAVI), which is mathematically corrected for blood pressure, remains understudied.

Objectives

The purpose of this study was to determine the association of CAVI with cardiovascular and kidney outcomes.

Methods

PubMed, Scopus, and Web of Science were searched until May 6, 2023, for longitudinal studies reporting the association of CAVI with mortality, cardiovascular events (CVEs) (including death, acute coronary syndromes, stroke, coronary revascularization, heart failure hospitalization), and kidney function decline (incidence/progression of chronic kidney disease, glomerular filtration rate decline). Random-effects meta-analysis was performed. Studies were assessed with the "Quality in Prognostic Studies" tool.

Results

Systematic review identified 32 studies (105,845 participants; follow-up range: 12-148 months). Variable cutoffs were reported for CAVI. The risk of CVEs was higher for high vs normal CAVI (HR: 1.46 [95% CI: 1.22-1.75]; P < 0.001; I2 = 41%), and per SD/unit CAVI increase (HR: 1.30 [95% CI: 1.20-1.41]; P < 0.001; I2 = 0%). Among studies including participants without baseline cardiovascular disease (primary prevention), higher CAVI was associated with first-time CVEs (high vs normal: HR: 1.60 [95% CI: 1.15-2.21]; P = 0.005; I2 = 65%; HR per SD/unit increase: 1.28 [95% CI: 1.12-1.47]; P < 0.001; I2 = 18%). There was no association between CAVI and mortality (HR = 1.31 [0.92-1.87]; P = 0.130; I2 = 53%). CAVI was associated with kidney function decline (high vs normal: HR = 1.30 [1.18-1.43]; P < 0.001; I2 = 38%; HR per SD/unit increase: 1.12 [95% CI: 1.07-1.18]; P < 0.001; I2 = 0%).

Conclusions

Higher CAVI is associated with incident CVEs, and this association is present in the primary prevention setting. Elevated CAVI is associated with kidney function decline.

Neuroimmune axis of cardiovascular control: mechanisms and therapeutic implications

Cardiovascular diseases (CVDs) make a substantial contribution to the global burden of disease. Prevention strategies have succeeded in reducing the effect of acute CVD events and deaths, but the long-term consequences of cardiovascular risk factors still represent the major cause of disability and chronic illness, suggesting that some pathophysiological mechanisms might not be adequately targeted by current therapies. Many of the underlying causes of CVD have now been recognized to have immune and inflammatory components. However, inflammation and immune activation were mostly regarded as a consequence of target-organ damage. Only more recent findings have indicated that immune dysregulation can be pathogenic for CVD, identifying a need for novel immunomodulatory therapeutic strategies. The nervous system, through an array of afferent and efferent arms of the autonomic nervous system, profoundly affects cardiovascular function. Interestingly, the autonomic nervous system also innervates immune organs, and neuroimmune interactions that are biologically relevant to CVD have been discovered, providing the foundation to target neural reflexes as an immunomodulatory therapeutic strategy. This Review summarizes how the neural regulation of immunity and inflammation participates in the onset and progression of CVD and explores promising opportunities for future therapeutic strategies.

Oral Anticoagulant Treatment in Patients with Atrial Fibrillation and Chronic Kidney Disease

Over the past few decades, a series of innovative medicines have been developed in order to optimize anticoagulation therapy for atrial fibrillation (AF). As a result, a number of nonvitamin K antagonist oral anticoagulants (NOAC) that directly target the enzymatic activity of factor II and factor Xa have been successfully licensed providing a more predictable effect and better safety profile compared to conventional anticoagulants (heparins and vitamin K antagonists (VKAs)). However, comparative efficacy and safety data is limited in patients with advanced chronic kidney disease (i.e., CKD stage 4/5 and end stage renal disease) because patients with estimated glomerular filtration rate (eGFR) < 30 mL/min/1.73 m² were actively excluded from landmark trials, thus representing a major clinical limitation for the currently available agents. However, the renal function of AF patients can be altered over time. On the other hand, patients with CKD have an increased risk of developing AF. This review article will provide an overview of current concepts and recent evidence guiding the clinical use of NOACs in patients with CKD requiring chronic anticoagulation, and the associated risks and benefits of treatment in this specific patient population.

Comparison of Risk for End-Stage Renal Disease Between Physicians and the General Population: A Nationwide Population-Based Cohort Study

Physicians experience high stress and have much responsibility during a night shift, which contributes to increased sympathetic activity, the risk factor for renal disease. The risk for end-stage renal disease (ESRD) in physicians is still unclear. Therefore, we conducted a nationwide population-based cohort study to clarify this issue. Using Taiwan’s National Health Insurance Research Database, we identified 30,268 physicians and 60,536 individuals from the general population matched with a ratio of 1:2 by age and sex. All participants who had ESRD before 2006 and residents were excluded. ESRD risk between physicians and the general population and among physician subgroups was compared by following up their medical histories until 2012. We also compared the treatments between both cohorts with ESRD. Physicians had a lower ESRD risk than the general population (adjusted odds ratio (AOR): 0.5; 95% confidence interval (CI): 0.4–0.7), particularly in the middle-age subgroup (35–64 years) (AOR: 0.4; 95% CI: 0.3–0.7); however, there was no difference in the older age subgroup (≥65 years) (AOR: 1.0; 95% CI: 0.6–1.7). More physicians received peritoneal dialysis (63.0% vs. 11.1%) and renal transplantation (5.6% vs. 1.7%) than the general population after being diagnosed with ESRD. Compared with the general population, physicians had a lower ESRD risk and higher treatment selection for peritoneal dialysis and renal transplantation after being diagnosed with ESRD. Better medical knowledge, a greater awareness of diseases and their risk factors, more rigorous implementation of preventive measures, and easy access to medical care may play a role in this aspect. Further studies are warranted for elucidating the associated mechanisms.

Morphological evaluation of sympathetic renal innervation in patients with autosomal dominant polycystic kidney disease

Several evidences support the hypothesis that patients affected by autosomal dominant polycystic kidney disease (ASPKD) show a sympathetic renal hyperactivity. Nevertheless, no morphological evidences are available yet. Therefore, the aim of the study was to demonstrate that an increase in sympathetic renal artery innervation was present in the ADPKD patients by using histological methods. In addition, here we correlated the sympathetic renal artery innervation with the evolutionary state of ADPKD (increase in volume of kidney, onset of chronic renal failure and hypertension). To this end, peri-adventitial innervation of renal arteries was studied using morphological methods from 49 patients in total: 29 underwent surgical nephrectomies for ADPKD and 20 non-dialysis patients (CTRL group) undergoing nephrectomy for other diseases. Nerve density (number of nerves per mm²) was evaluated in the peri-adventitial tissue in a concentric ring that was located within 2 mm from the beginning of the adventitia by using immunohistochemistry. The total nerve density was significantly increased in the ADPKD group (1.26 ± 0.82 × mm²) as compared to controls (0.78 ± 0.40 × mm²) (p = 0.02). Hypertensive patients with ADPKD showed a greater nerve density than control hypertensives. However, the increase in renal sympathetic innervation in the ADPKD patients was found to be independent of hypertension, resistance to antihypertensive therapy, age, sex and kidney volume, as demonstrated by the uni and multivariate analysis. In conclusion, our study better clarifies the effect of sympathetic hyperactivity in the progression of polycystic disease.

Biomarker Profiling in Stage 5 Chronic Kidney Disease Identifies the Relationship between Angiopoietin-2 and Atrial Fibrillation

Atrial fibrillation (AF) is prevalent in nearly 27% of patients with stage 5 chronic kidney disease on hemodialysis (CKD5-HD), suggesting a strong association between these 2 pathologies. It is hypothesized that the relationship between these 2 diseases may be mediated by inflammation. Angiopoietin-2 (Ang-2), a pro-inflammatory biomarker of endothelial instability, inflammation, and vascular remodeling, is elevated in CKD5-HD and AF, yet has not been evaluated in patients with concomitant AF and CKD5-HD. The aim of this study is to analyze circulating levels of inflammatory and thrombotic biomarkers in patients with concomitant AF and CKD5-HD. Plasma levels of Ang-2 were measured via sandwich enzyme-linked immunosorbent assay method in CKD5-HD patients (n = 96), patients with AF (n = 38), and controls (n = 50). Angiopoietin-2 was markedly elevated in CKD5-HD with comorbid AF as compared to CKD5-HD alone, and AF alone, respectively (13.05 ± 1.56 vs 9.57 ± 0.71 ng/mL; P = .00169; vs 2.48 ± 0.57 ng/mL; P < .0001). The results of this study suggest an additive effect of Ang-2 with coexistence of AF and CKD5-HD, which may be useful in the detection of AF within this patient population.

Hypertension in kidney transplantation is associated with an early renal nerve sprouting

Background. Normalization of arterial pressure occurs in just a few patients with hypertensive chronic kidney disease undergoing kidney transplantation. Hypertension in kidney transplant recipients may be related to multiple factors. We aimed to assess whether hypertension in kidney-transplanted patients may be linked to reinnervation of renal arteries of the transplanted kidney.

Methods. We investigated renal arteries innervation from native and transplanted kidneys in three patients 5 months, 2 years and 11 years after transplantation, respectively. Four transplanted kidneys from non-hypertensive patients on immunosuppressive treatment without evidence of hypertensive arteriolar damage were used as controls.

Results. Evidence of nerve sprouting was observed as early as 5 months following transplantation, probably originated from ganglions of recipient patient located near the arterial anastomosis and was associated with mild hypertensive arteriolar damage. Regeneration of periadventitial nerves was already complete 2 years after transplantation. Nerve density tended to reach values observed in native kidney arteries and was associated with hypertension-related arteriolar lesions in transplanted kidneys. Control kidneys, albeit on an immunosuppressive regimen, presented only a modest regeneration of sympathetic nerves.

Conclusions. Our results suggest that the considerable increase in sympathetic nerves, as found in patients with severe arterial damage, may be correlated to hypertension rather than to immunosuppressive therapy, thus providing a morphological basis for hypertension recurrence despite renal denervation.

Pathophysiology and Potential Non-Pharmacologic Treatments of Obesity or Kidney Disease Associated Refractory Hypertension

PURPOSE OF REVIEW

The review assesses the role of non-pharmacologic therapy for obesity and chronic kidney disease (CKD) associated refractory hypertension (rf HTN).

RECENT FINDINGS

Hypertensive patients with markedly heightened sympathetic nervous system (SNS) activity are prone to develop refractory hypertension (rfHTN). Patients with obesity and chronic kidney disease (CKD)-associated HTN have particularly heightened SNS activity and are at high risk of rfHTN. The role of bariatric surgery is increasingly recognized in treatment of obesity. Current evidence advocates for a greater role of bariatric surgery in the management of obesity-associated HTN. In contrast, renal denervation does not appear have a role in the management of obesity or CKD-associated HTN. The role of baroreflex activation as adjunctive anti-hypertensive therapy remains to be defined.

Renalase Assessment With Regard to Kidney Function, Lipid Disturbances, and Endothelial Dysfunction Parameters in Stable Renal Transplant Recipients

BACKGROUND

Renal transplant dysfunction has been shown to be independent predictor for premature cardiovascular disease and mortality. Renalase, a flavoprotein secreted by several tissues, including the kidney, has been found to regulate sympathetic tone and blood pressure. The purpose of this secondary analysis was to explore relationships among parameters of endothelial dysfunction, lipids, glomerular filtration rate, and renalase in 2 groups: renal transplant patients with controlled hypertension and healthy volunteers.

METHODS

In the parent study, 73 renal transplant recipients and 32 age- and gender-matched controls were enrolled. A fasting sample for endothelial, lipid, and renalase values, along with other clinical parameters, was obtained.

RESULTS

We found statistically significant inverse correlation between renalase and estimated glomerular filtration rate ( r = -0.552, P < .001), positive correlation between renalase and creatinine ( r = 0.364, P = .003), total cholesterol ( r = 0.578, P < .001), low-density lipoprotein cholesterol ( r = 0.261, P = .046), and non-high-density lipoprotein cholesterol ( r = 0.327, P = .01). Renalase inversely correlated with hemoglobin ( r = -0.232, P = .032) and positively with white blood cells ( r = 0.233, P = .032). There was a significant difference in plasma renalase with regard to chronic kidney disease stages ( F = 13.346, P < .001) but did not correlate with C-reactive protein. Renalase did not correlate with any of parameters of endothelial dysfunction, C-reactive protein, neither with some demographic data (gender, age, time or type of transplantation, risk factors). There were no differences in renalase concentration with regard to antihypertensive therapy.

CONCLUSION

Renalase strongly and inversely correlated with kidney function, positively with creatinine and lipid disturbances. Due to that it is very likely that renalase levels are determined mostly by renal function.

Spectrum of Cerebrovascular Disease in Patients with Multiple Myeloma Undergoing Chemotherapy-Results of a Case Control Study

Objectives

Patients with multiple myeloma (MM) are at increased risk of arterial thrombosis. Our aim was to determine the risk factors, mechanisms and outcome of strokes in these patients.

Methods

We conducted a retrospective matched case–control study from our database of MM patients enrolled in Total Therapy (TT) 2, TT3a and TT3b protocols who developed a vascular event (transient ischemic attack, ischemic stroke, or intracerebral hemorrhage) from October 1998 to January 2014. Cases were matched for age-matched selected controls. Baseline demographics, risk factors, MM characteristics, laboratory values, and mortality of cases were compared to those of controls. Multivariate logistic regression analysis identified risk factors associated with stroke. Ischemic strokes (IS) were classified with modified Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria.

Results

Of 1,148 patients, 46 developed a vascular event (ischemic stroke, 33; transient ischemic attack, 11; hypertensive intracerebral hemorrhage, 2). Multivariate logistic regression analysis determined renal insufficiency (odds Ratio, 3.528; 95% CI, 1.36–9.14; P = 0.0094) and MM Stages I and II (odds Ratio, 2.770, 95% CI, 1.31–5.81; p = 0.0073) were independent predictors of stroke. In our study, strokes attributable to hypercoagulability, atrial fibrillation and small-vessel occlusion were common mechanisms. After a stroke, 78% of patients were discharged to home or a rehabilitation facility and 4% to a long-term nursing facility; in-hospital mortality was 15%. Despite suffering a stroke no significant differences in survival were observed.

Conclusion

In our cohort of multiple myeloma patients, renal failure and MM Stages I and II had increased risk of stroke.

Renalase Gene rs2576178 Polymorphism in Hemodialysis Patients: Study in Bosnia and Herzegovina

Introduction:

Renalase is a protein secreted in kidneys and considered as a blood pressure modulator. High rates of hypertension and its regulation in patients on hemodialysis demands search for potential cause and treatment. The aim of this study was to determine the genotype and allele frequencies of renalase gene rs2576178 polymorphism in population from Bosnia and Herzegovina. Also, the objective of present study was to find the possible association between renalase gene rs2576178 polymorphism and hypertension in patients on hemodialysis.

Material and Methods:

The genotype of renalase gene rs2576178 polymorphism was determined in 137 participants (100 patients on hemodialysis and 37 controls), using polymerase chain reaction (PCR) and subsequent cleavage with MspI restriction endonuclease. Genotype and allele frequencies were assessed for Hardy-Weinberg equilibrium using a Chi-squared test. The value of P<0.05 was considered as statistically significant.

Results:

Comparison of genotype distribution and allele frequency in participants on hemodialysis with and without hypertension, and healthy control showed no statistical difference.

Conclusion:

The results of the study suggest that renalase gene rs2576178 polymorphism is not a factor that influences blood pressure in patients on hemodialysis.

Increased Sympathetic Renal Innervation in Hemodialysis Patients Is the Anatomical Substrate of Sympathetic Hyperactivity in End-Stage Renal Disease

BACKGROUND

Renal denervation represents an emerging treatment for resistant hypertension in patients with end-stage renal disease, but data about the anatomic substrate of this treatment are lacking. Therefore, the aim of this study was to investigate the morphological basis of sympathetic hyperactivity in the setting of hemodialysis patients to identify an anatomical substrate that could warrant the use of this new therapeutic approach.

METHODS AND RESULTS

The distribution of sympathetic nerves was evaluated in the adventitia of 38 renal arteries that were collected at autopsy or during surgery from 25 patients: 9 with end-stage renal disease on dialysis (DIAL group) and 16 age-matched control nondialysis patients (CTRL group). Patients in the DIAL group showed a significant increase in nerve density in the internal area of the peri-adventitial tissue (within the first 0.5 mm of the beginning of the adventitia) compared with the CTRL group (4.01±0.30 versus 2.87±0.28×mm(2), P=0.01). Regardless of dialysis, hypertensive patients with signs of severe arteriolar damage had a greater number of nerve endings in the most internal adventitia, and this number was significantly higher than in patients without hypertensive arteriolar damage (3.90±0.36 versus 2.87±0.41×mm(2), P=0.04), showing a correlation with hypertensive arteriolar damage rather than with hypertensive clinical history.

CONCLUSIONS

The findings from this study provide a morphological basis underlying sympathetic hyperactivity in patients with end-stage renal disease and might offer useful information to improve the use of renal denervation in this group of patients.

Blood pressure control according to the prevalence of diabetes in renal transplant recipients

Hypertension is one of the most frequent complications of renal transplantation. About 70% to 90% of this population display either high blood pressure (BP) or require antihypertensive therapy. Diabetes mellitus is also a common finding among kidney transplant recipients. The aim of the study was to assess the BP control among kidney transplant recipients according to the prevalence of diabetes. This retrospective analysis included 172 renal transplant recipients of overall mean age 50 years and 51% males. Hypertension was present in 79% of patients. About one-third of the studied population showed abnormal blood pressures based on office measurements. The cohort was divided into two groups according to the presence of diabetes: group 1, diabetic patients (n = 14) versus group 2, nondiabetics (n = 158). Nondiabetic patients were significantly older than diabetic ones (61.5 versus 49 years; P < .05) and their time after renal transplantation was longer (98.83 versus 67.33 months, P < .05). There was no difference in regard to hypertension prevalence, mean BP value, percentage of abnormal (≥ 140/90 mm Hg) BP values or glomerular filtration rate. Diabetic patients were prescribed less steroid. The main hypotensive drug used in whole cohort and in no-diabetic patients was a beta-blocker (n = 64, 37%; n = 4, 28%), patients with diabetes used beta-blockers and angiotensin-converting enzyme inhibitors at the same frequency (n = 60, 37%). The main causative factor for hypertension appeared to be the calcineurin inhibitor. More aggressive antihypertensive treatment using combined drugs, including RAS blockers, might provide adequate BP control among renal transplant subjects with high cardiovascular risk.

Occupational risk and chronic kidney disease: a population-based study in the United States adult population

OBJECTIVE

Previous studies on occupational risk for chronic kidney disease (CKD) have analyzed a limited range of occupations and focused on nephrotoxins. The primary purpose of this study was to examine the relative risk for the occurrence of CKD between different occupations in the US adult population.

MATERIALS AND METHODS

This was a population-based survey study of 91,340 participants in the US, who completed the National Health Interview Survey, 2004 through 2008. The outcome variable, CKD, was defined as having weakening/failing kidneys in the past 12 months, as diagnosed by a physician. The predictor variable, occupation, was obtained using the census occupational codes, regrouped according to North American Industrial Classification System.

RESULTS

After controlling for age, gender, hypertension, and education, and with the category Life, Physical, and Social Science Occupations as a reference group, the likelihood of developing CKD was 4.3 times higher in respondents working in Building, Grounds Cleaning and Maintenance Occupations, 4.4 times higher in Healthcare Practitioners and Technical Occupations, 4.7 times higher in Transportation and Material Moving Occupations and in Computer and Mathematical Occupations, 4.8 times higher in Production Occupations, 5.3 times higher in Food Preparation and Serving Related Occupations, and 6.1 times higher in Healthcare Support Occupations and in Legal Occupations.

CONCLUSION

This study identified occupation groups in US adult population with increased risk for CKD. Alleviation of workplace stress is suggested as a goal for behavioral intervention in high-risk occupations.

The Relationship Between Atrial Fibrillation and Chronic Kidney Disease : Epidemiologic and Pathophysiologic Considerations for a Dual Epidemic

Atrial fibrillation (AF) presently affects over 2 million Americans, and the magnitude and population burden from AF continues to increase concomitant with the aging of the U.S.

POPULATION

Chronic kidney disease (CKD) is present in 13% of individuals in the U.S., and the prevalence of CKD is also rapidly increasing. The increasing population burden of CKD and AF will profoundly affect the clinical and public health, since CKD and AF are both associated with lower quality of life, increased hospitalization rates, and a greater risk of heart failure, stroke, and total mortality. AF and CKD often co-exist, each condition predisposes to the other, and the co-occurrence of these disorders worsens prognosis relative to either disease alone. The shared epidemiology of CKD and AF may be explained by the strong pathophysiologic connections between these diseases. In order to promote a better understanding of CKD and AF, we have reviewed their shared epidemiology and pathophysiology and described the natural history of patients affected by both diseases.

Effects of renal denervation on sympathetic activation, blood pressure, and glucose metabolism in patients with resistant hypertension

Increased central sympathetic drive is a hallmark of several important clinical conditions including essential hypertension, heart failure, chronic kidney disease, and insulin resistance. Afferent signaling from the kidneys has been identified as an important contributor to elevated central sympathetic drive and increased sympathetic outflow to the kidney and other organs is crucially involved in cardiovascular control. While the resultant effects on renal hemodynamic parameters, sodium and water retention, and renin release are particularly relevant for both acute and long term regulation of blood pressure, increased sympathetic outflow to other vascular beds may facilitate further adverse consequences of sustained sympathetic activation such as insulin resistance, which is commonly associated with hypertension. Recent clinical studies using catheter-based radiofrequency ablation technology to achieve functional renal denervation in patients with resistant hypertension have identified the renal nerves as therapeutic target and have helped to further expose the sympathetic link between hypertension and insulin resistance. Initial data from two clinical trials and several smaller mechanistic clinical studies indicate that this novel approach may indeed provide a safe and effective treatment alternative for resistant hypertension and some of its adverse consequences.