Sodium intake, RAAS-blockade and progressive renal disease

The role of a novel mineralocorticoid receptor antagonist, finerenone, in chronic kidney disease: mechanisms and clinical advances

BACKGROUND

Chronic kidney disease (CKD) poses a significant health risk in contemporary society. Current CKD treatments primarily involve renin-angiotensin-aldosterone system inhibitors and mineralocorticoid receptor antagonists, albeit associated with hyperkalemia risks. A novel selective mineralocorticoid receptor antagonist, finerenone, offers a promising, safer alternative for CKD therapy. This review comprehensively assesses the role and efficacy of finerenone in CKD treatment by analyzing clinical and animal studies. Emerging evidence consistently supports finerenone's ability to effectively slow the progression of CKD. By targeting the mineralocorticoid receptor, finerenone not only mitigates renal damage but also exhibits a favorable safety profile, minimizing hyperkalemia concerns.

CONCLUSION

Finerenone emerges as a valuable addition to CKD therapy, demonstrating potential benefits in delaying CKD progression while minimizing side effects. Nevertheless, further clinical trials are necessary to provide a comprehensive understanding of its safety and efficacy.

Association of renal resistive indices with kidney disease progression and mortality

BACKGROUND

Renal resistive indices (RRI) have been shown to predict the progression of kidney disease. This study aims to evaluate the association of RRI with mortality and dialysis initiation after adjustment to therapeutic and life style interventions.

METHODS

This is a retrospective study that included all chronic kidney disease patients followed for at least two years in three nephrology clinics between 2006 and 2019 and who had a RRI level in their files. Kaplan Meier and log rank test compared the survival of patients with normal versus high RRI. Cox regression analysis evaluated the association between RRI and death or dialysis initiation after adjustment to treatments and life style modifications.

RESULTS

A total of 192 patients were analyzed: 68 had RRI < 0.7 and 124 had RRI ≥ 0.7. Their mean age was 66.5 ± 13.1 years at first visit, 78.1% were males. There was a negative correlation between baseline eGFR and RRI (p < 0.001; Spearman correlation coefficient = -0.521). The survival was significantly better in patients with RRI < 0.7 with a Log Rank test < 0.001. The univariate cox regression analysis showed a significant association between RRI and mortality (HR = 1.08; 95%CI: 1.04-1.11; p < 0.001) that remained significant after adjustment to cardiovascular risk factors and interventions such as salt reduction, blood pressure control, statins and RAAS inhibitors (HR = 1.04; 95%CI: 1.00-1.08; p = 0.036). Cox regression analysis showed a significant association between RRI and dialysis initiation (HR = 1.06; 95%CI 1.01-1.10; p = 0.011).

CONCLUSION

Our study revealed that patients with an elevated RRI ≥ 0.7 are at a higher risk of mortality after adjustment to medications and lifestyle modifications. RRI can, according to this study, be considered as an independent prognostic factor in CKD patients.

Psychological Distress and Self-Management in CKD: A Cross-Sectional Study

Rationale & Objective

Patients with chronic kidney disease (CKD) not receiving dialysis, including kidney transplant recipients, often experience difficulties regarding self-management. An important barrier for adherence to self-management recommendations may be the presence of psychological distress, consisting of depressive and anxiety symptoms. We investigated relationships between psychological distress and adherence to self-management recommendations.

Study Design

Cross-sectional online questionnaire data as part of the E-GOAL study.

Setting & Participants

Patients with CKD (estimated glomerular filtration rate, 20-89 mL/min/1.73 m2) were recruited from April 2018 to October 2020 at 4 hospitals in The Netherlands and completed online screening questionnaires.

Exposures

Psychological distress, depressive symptoms, and anxiety symptoms.

Outcomes

Dietary adherence, physical activity, medication adherence, smoking, body mass index, and a CKD self-management index (ie, the sum of 5 binary indicators of nonadherence to the recommended self-management factors).

Analytical Approach

Adjusted multivariable regression and ordinal logistic regression analyses.

Results

In our sample (N = 460), 27.2% of patients reported psychological distress, and 69.8% were nonadherent to 1 or more recommendations. Higher psychological distress was significantly associated with poorer dietary adherence (βadj, -0.13; 95% CI, -0.23 to -0.04), less physical activity (βadj, -0.13; 95% CI, -0.22 to -0.03), and lower medication adherence (βadj, -0.15; 95% CI, -0.24 to -0.05), but not with smoking and body mass index. Findings were similar for depressive symptoms, whereas anxiety was only associated with poorer dietary and medication adherence. Every 1-point higher psychological distress was also associated with a higher likelihood of being nonadherent to an accumulating number of different recommendations (adjusted OR, 1.04; 95% CI, 1.02-1.07).

Limitations

Cross-sectional design, possible residual confounding, and self-report.

Conclusions

Many people with CKD experience psychological distress, of whom most have difficulties self-managing their CKD. Given the relationship between psychological distress and adherence to CKD self-management recommendations, behavioral interventions are needed to identify and treat psychological distress as a potential barrier to CKD self-management.

Plain-Language Summary

This online questionnaire study investigated relationships between psychological distress and self-management among 460 people with chronic kidney disease. Over a quarter of them reported mild-to-severe psychological distress. Alarmingly, 4 out of 5 patients with psychological distress were also nonadherent to 1 or more self-management recommendations, and higher levels of psychological distress were associated with poorer dietary and medication adherence and lower physical activity. Moreover, patients who suffered from moderate-to-severe distress were relatively more often nonadherent to 3 or more recommendations compared with patients with no or mild distress symptoms. So, it seems that psychological distress can be a barrier for self-management. To support patients in managing chronic kidney disease, researchers and health professionals should not overlook patients' mental health.

Global, regional, and national burden of chronic kidney disease attributable to high sodium intake from 1990 to 2019

Background

High sodium intake is a crucial risk factor for the development and progression of chronic kidney disease (CKD). However, the latest global spatiotemporal patterns of CKD burden attributable to high sodium intake still remain unclear. We aimed to evaluate the level and trends of the CKD burden associated with high sodium intake according to sex, age, socio-demographic index (SDI), region, and country from 1990 to 2019.

Methods

Data on CKD burden attributable to high sodium intake from 1990 to 2019 were extracted from the Global Burden of Disease (GBD) Study 2019. The CKD-related deaths, disability-adjusted life years (DALYs), age-standardized mortality rate (ASMR), and age-standardized DALYs rate (ASDR) attributable to high sodium intake were estimated by age, sex, SDI, region, and country. The estimated annual percentage change (EAPC) was calculated to evaluate the secular trends of ASMR and ASDR of CKD attributable to high sodium intake from 1990 to 2019. We further explored the associations of SDI with the ASMR and ASDR of CKD attributable to high sodium intake.

Results

Globally, the number of CKD-related deaths and DALYs attributable to high sodium intake were 45,530 (95% UI: 12,640 to 93,830) and 1.32 million (95% UI: 0.43 to 2.8) in 2019, both twice as many as those in 1990. However, the ASMR and ASDR slightly grew, with an EAPC of 0.22 (95% CI: 0.16 to 0.28) and 0.10 (95% CI: 0.04 to 0.16), respectively. The age-specific numbers and rates of deaths, as well as DALYs of CKD attributable to high sodium intake, rose with age and were greater in males than in females. The rates of deaths and DALYs peaked in the >95 age group for both females and males in 2019. From 1990 to 2019, the trends of both age-specific rates of mortality and DALYs of CKD attributable to high sodium intake were down in people under 60, while in people over 60, the trends were the opposite. The burden of CKD attributable to high sodium intake in 2019 and its temporal trends from 1990 to 2019 varied greatly by SDI quintile and geographic location. The ASMR or ASDR showed a non-linear negative correlation with SDI at the regional level. The EAPC in ASMR or ASDR showed a markedly negative correlation with ASMR or ASDR in 1990, with a coefficient of -0.40. Nevertheless, the EAPC in ASMR rather than ASDR was positively correlated with SDI in 2019, with a coefficient of 0.18.

Conclusion

Our findings suggest that there are significant sexual and geographic variations in the burden of CKD attributable to high sodium intake and its temporal trends. Globally, the high sodium intake-caused CKD burden continues to elevate, posing a major challenge to public health. In response to this, strengthened and tailored approaches for CKD prevention and sodium intake management are needed, especially for elderly populations, males, and the population in the middle SDI regions.

High-Salt Attenuates the Efficacy of Dapagliflozin in Tubular Protection by Impairing Fatty Acid Metabolism in Diabetic Kidney Disease

High-salt intake leads to kidney damage and even limits the effectiveness of drugs. However, it is unclear whether excessive intake of salt affects renal tubular energy metabolism and the efficacy of dapagliflozin on renal function in diabetic kidney disease (DKD). In this study, we enrolled 350 DKD patients and examined the correlation between sodium level and renal function, and analyzed influencing factors. The results demonstrated that patients with macroalbuminuria have higher 24 h urinary sodium levels. After establishment of type 2 diabetes mellitus model, the animals received a high-salt diet or normal-salt diet. In the presence of high-salt diet, the renal fibrosis was aggravated with fatty acid metabolism dysregulation. Furthermore, Na+/K+-ATPase expression was up-regulated in the renal tubules of diabetic mice, while the fatty acid metabolism was improved by inhibiting Na+/K+-ATPase of renal tubular epithelial cells. Of note, the administration with dapagliflozin improved renal fibrosis and enhanced fatty acid metabolism. But high salt weakened the above-mentioned renal protective effects of dapagliflozin in DKD. Similar results were recapitulated in vitro after incubating proximal tubular epithelial cells in high-glucose and high-salt medium. In conclusion, our results indicate that high salt can lead to fatty acid metabolism disorders by increasing Na+/K+-ATPase expression in the renal tubules of DKD. High salt intake diminishes the reno-protective effect of dapagliflozin in DKD.

Recent therapeutic targets in diabetic nephropathy

BACKGROUND

The prevalence of diabetes mellitus has been increased dramatically which in turn leads to complications including cardiovascular diseases, diabetic kidney disease, and substantially end-stage renal disease.

METHODS

We reviewed articles discussing the pathophysiology of diabetic nephropathy with new agents that may be useful in the management of the disease. We used PubMed, Scopus, Google Scholar and the Open-access searching engines.

RESULTS

The recent recommendations primarily depend on glycaemic and blood pressure control and the use of standard renin-angiotensin system blockade. Currently, the use of agents with nephroprotective effects beyond the hyperglycaemic lowering effect has been evidenced clinically.

CONCLUSIONS

In his review, the pathophysiology, clinical manifestations, and lines of treatment of diabetic nephropathy are discussed. In addition, a focus on the clinical role and nephroprotective effects of the emerging therapeutic class, dipeptidyl peptidase IV (DPP-4) inhibitors, is addressed in detail.

Effect of a sodium restriction diet on albuminuria and blood pressure in diabetic kidney disease patients: a meta-analysis

BACKGROUND

A sodium restriction diet is a key component of chronic kidney disease (CKD) management. However, the efficacy of its use in patients with diabetic kidney disease (DKD) is uncertain. The present meta-analysis explored the effects of restricting sodium intake on albuminuria and blood pressure in DKD patients with albuminuria.

METHODS

We searched the Cochrane Central Register of Controlled Trials, Web of Science, MEDLINE, and EMBASE for randomized controlled trials, and we reviewed the references of all searched articles to avoid omitting other relevant articles. Our primary endpoints were blood pressure, albumin excretion rate, and plasma renin activity. We assessed pooled data using a random-effects model.

RESULTS

Of the 661 articles identified, a total of 12 articles were included in the meta-analysis. The random-effects model indicated that salt-restriction diet interventions led to a poled - 4.72 mmHg (95% CI - 6.71, - 2.73) difference in systolic blood pressure and that the intervention resulted in a 2.33 mmHg lower diastolic blood pressure (95% CI - 3.61, - 1.05). In patients with microalbuminuria, restricted sodium intake decreased the albumin excretion rate (AER) by 12.62 mg/min (95% CI - 19.64, - 5.60). Furthermore, the AER was 127.69 mg/min lower in patients with macroalbuminuria (95% CI - 189.07, - 66.32).

CONCLUSION

Moderate sodium restriction diets reduce urinary albumin excretion and decrease the level of blood pressure, especially for patients with macro-albuminuria. Thus, it is necessary to strengthen the intervention and health education as well as to provide individualized dietary advice.

Measured sodium excretion is associated with CKD progression: results from the KNOW-CKD study

BACKGROUND

Diet is a modifiable factor of chronic kidney disease (CKD) progression. However, the effect of dietary salt intake on CKD progression remains unclear. Therefore, we analyzed the effect of dietary salt intake on renal outcome in Korean patients with CKD.

METHODS

We measured 24-h urinary sodium (Na) excretion as a marker of dietary salt intake in the prospective, multi-center, longitudinal KoreaN cohort study for Outcome in patients With CKD (KNOW-CKD). Data were analyzed from CKD patients at Stages G3a to G5 (n = 1254). We investigated the association between dietary salt intake and CKD progression. Patients were divided into four quartiles of dietary salt intake, which was assessed using measured 24-h urinary Na excretion. The study endpoint was composite renal outcome, which was defined as either halving the estimated glomerular filtration rate or developing end-stage renal disease.

RESULTS

During a median (interquartile range) follow-up of 4.3 (2.8-5.8) years, 480 (38.7%) patients developed the composite renal event. Compared with the reference group (Q2, urinary Na excretion: 104.2 ≤ Na excretion < 145.1 mEq/day), the highest quartile of measured 24-h urinary Na excretion was associated with risk of composite renal outcome [Q4, urinary Na excretion ≥192.9 mEq/day, hazard ratio 1.8 (95% confidence interval 1.12-2.88); P = 0.015] in a multivariable hazards model. Subgroup analyses showed that high-salt intake was particularly associated with a higher risk of composite renal outcome in women, in patients <60 years of age, in those with uncontrolled hypertension and in those with obesity.

CONCLUSIONS

High salt intake was associated with increased risk of progression in CKD.

Salt Reduction to Prevent Hypertension and Cardiovascular Disease: JACC State-of-the-Art Review

There is strong evidence for a causal relationship between salt intake and blood pressure. Randomized trials demonstrate that salt reduction lowers blood pressure in both individuals who are hypertensive and those who are normotensive, additively to antihypertensive treatments. Methodologically robust studies with accurate salt intake assessment have shown that a lower salt intake is associated with a reduced risk of cardiovascular disease, all-cause mortality, and other conditions, such as kidney disease, stomach cancer, and osteoporosis. Multiple complex and interconnected physiological mechanisms are implicated, including fluid homeostasis, hormonal and inflammatory mechanisms, as well as more novel pathways such as the immune response and the gut microbiome. High salt intake is a top dietary risk factor. Salt reduction programs are cost-effective and should be implemented or accelerated in all countries. This review provides an update on the evidence relating salt to health, with a particular focus on blood pressure and cardiovascular disease, as well as the potential mechanisms.

Sodium Intake and Target Organ Damage in Hypertension-An Update about the Role of a Real Villain

Salt intake is too high for safety nowadays. The main active ion in salt is sodium. The vast majority of scientific evidence points out the importance of sodium restriction for decreasing cardiovascular risk. International Guidelines recommend a large reduction in sodium consumption to help reduce blood pressure, organ damage, and cardiovascular risk. Regulatory authorities across the globe suggest a general restriction of sodium intake to prevent cardiovascular diseases. In spite of this seemingly unanimous consensus, some researchers claim to have evidence of the unhealthy effects of a reduction of sodium intake, and have data to support their claims. Evidence is against dissenting scientists, because prospective, observational, and basic research studies indicate that sodium is the real villain: actual sodium consumption around the globe is far higher than the safe range. Sodium intake is directly related to increased blood pressure, and independently to the enlargement of cardiac mass, with a possible independent role in inducing left ventricular hypertrophy. This may represent the basis of myocardial ischemia, congestive heart failure, and cardiac mortality. Although debated, a high sodium intake may induce initial renal damage and progression in both hypertensive and normotensive subjects. Conversely, there is general agreement about the adverse role of sodium in cerebrovascular disease. These factors point to the possible main role of sodium intake in target organ damage and cardiovascular events including mortality. This review will endeavor to outline the existing evidence.

A Self-management Approach for Dietary Sodium Restriction in Patients With CKD: A Randomized Controlled Trial

RATIONALE & OBJECTIVE

Patients with chronic kidney disease (CKD) are particularly sensitive to dietary sodium. We evaluated a self-management approach for dietary sodium restriction in patients with CKD.

STUDY DESIGN

Randomized controlled trial.

SETTING & PARTICIPANTS

Nephrology outpatient clinics in 4 Dutch hospitals. 99 adults with CKD stages 1 to 4 or a functioning (estimated glomerular filtration rate≥25mL/min/1.73m²) kidney transplant, hypertension, and sodium intake>130mmol/d.

INTERVENTION

Routine care was compared with routine care plus a web-based self-management intervention including individual e-coaching and group meetings implemented over a 3-month intervention period, followed by e-coaching over a 6-month maintenance period.

OUTCOMES

Primary outcomes were sodium excretion after the 3-month intervention and after the 6-month maintenance period. Secondary outcomes were blood pressure, proteinuria, costs, quality of life, self-management skills, and barriers and facilitators for implementation.

RESULTS

Baseline estimated glomerular filtration rate was 55.0±22.0mL/min/1.73m². During the intervention period, sodium excretion decreased in the intervention group from 188±8 (SE) to 148±8mmol/d (P<0.001), but did not change significantly in the control group. At 3 months, mean sodium excretion was 24.8 (95% CI, 0.1-49.6) mmol/d lower in the intervention group (P=0.049). At 3 months, systolic blood pressure (SBP) decreased in the intervention group from 140±3 to 132±3mm Hg (P<0.001), but was unchanged in the control group. Mean difference in SBP across groups was-4.7 (95% CI, -10.7 to 1.3) mm Hg (P=0.1). During the maintenance phase, sodium excretion increased in the intervention group, but remained lower than at baseline at 160±8mmol/d (P=0.01), while it decreased in the control group from 174±9 at the end of the intervention period to 154±9mmol/d (P=0.001). Consequently, no difference in sodium excretion between groups was observed after the maintenance phase. There was no difference in SBP between groups after the maintenance phase.

LIMITATIONS

Limited power, postrandomization loss to follow-up, Hawthorne effect, lack of dietary data, short-term follow-up.

CONCLUSIONS

A coaching intervention reduced sodium intake at 3 months. Efficacy during the maintenance phase was diminished, possibly due to inadvertent adoption of the intervention by the control group.

FUNDING

Grant funding from the Netherlands Organization for Health Research and Development and the Dutch Kidney Foundation.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT02132013.

Modifiers of Plasma 25-Hydroxyvitamin D and Chronic Kidney Disease Outcomes in Black Americans: The Jackson Heart Study

BACKGROUND

25-hydroxyvitamin D [25(OH)D] is lower in black compared with white Americans but is not consistently associated with outcomes in this group, possibly due to genetic and other biological differences. We examined the association of plasma 25(OH)D and renal outcomes in black Americans with a focus on effect modifiers.

METHODS

We studied associations between baseline 25(OH)D with (i) annual rate of estimated glomerular filtration rate (eGFR) decline and (ii) incident chronic kidney disease (CKD) in the Jackson Heart Study, a prospective cohort of black Americans. Plasma 25(OH)D levels were corrected for monthly variation in sunlight exposure using the residual method. We used adjusted generalized linear models to evaluate outcomes and assessed potential effect modification by diabetes mellitus, vitamin D binding protein (DBP) genotype, obesity, dietary sodium intake, and use of renin-angiotensin-aldosterone system inhibitors.

RESULTS

Among 5164 participants with 25(OH)D available, plasma 25(OH)D was 14.5 ± 6.5 ng/mL (mean ± SD), and eGFR was 94.1 ± 22.0 mL/min/1.73 m2. Over a median of 8 years, eGFR decline was 1.3 ± 2.0 mL/min/1.73 m2 per year in 3228 participants with complete data, and 220 out of 1803 eligible participants developed incident CKD. Overall, 25(OH)D was not associated with eGFR decline in fully adjusted models. However, higher 25(OH)D was associated with slower eGFR decline among those with diabetes: each 5 ng/mL higher 25(OH)D was associated with a 0.27 mL/min/1.73 m2/y slower eGFR decline (95% CI, 0.13 to 0.41; P < 0.001). Higher 25(OH)D was not associated with incident CKD overall, but it was associated with lower odds of incident CKD among participants with the GG or GT genotype at rs7041 in the gene encoding DBP [OR, 0.69 per 5 ng/mL higher 25(OH)D; 95% CI, 0.51 to 0.93; P-interaction = 0.005]. Other interactions were not significant.

CONCLUSION

These findings support a potential benefit of higher 25(OH)D for kidney health in black Americans with diabetes or specific variants in DBP.

Perceived Sodium Reduction Barriers Among Patients with Chronic Kidney Disease: Which Barriers Are Important and Which Patients Experience Barriers?

PURPOSE

The purposes of this study were to assess the importance of perceived sodium reduction barriers among patients with chronic kidney disease (CKD) and identify associated sociodemographic, clinical, and psychosocial factors.

METHOD

A total of 156 patients with CKD completed a questionnaire assessing sodium reduction barriers (18 self-formulated items), depressive symptoms (Beck Depression Inventory), perceived autonomy support (Modified Health Care Climate Questionnaire), and self-efficacy (Partners in Health Questionnaire). Factor analysis was used to identify barrier domains. Correlation coefficients were computed to examine relationships between barrier domains and patient characteristics.

RESULTS

Nine barrier domains were identified. Barriers perceived as important were as follows: high sodium content in products, lack of sodium feedback, lack of goal setting and discussing strategies for sodium reduction, and not experiencing CKD-related symptoms (mean scores > 3.0 on 5-point scales, ranging from 1 'no barrier' to 5 'very important barrier'). Other barriers (knowledge, attitude, coping skills when eating out, and professional support) were rated as moderately important (rated around midpoint), and the barrier 'intrinsic motivation' was rated as somewhat important (mean score = 1.9). Sodium reduction barrier domains were not associated with gender and kidney function, but were associated with age, level of education, number of comorbidities, perceived autonomy support, depressive symptoms, and self-efficacy (range r = 0.17-0.35). Patients with lower self-efficacy and perceived autonomy support scores experienced most sodium reduction barriers.

CONCLUSION

Patients with CKD experience multiple important sodium reduction barriers and could benefit from support strategies that target various sodium reduction barriers and strengthen beliefs regarding self-efficacy and autonomy support. Additionally, environmental interventions should be implemented to reduce sodium levels in processed foods.

Inappropriate activity of local renin-angiotensin-aldosterone system during high salt intake: impact on the cardio-renal axis

Although there is a general agreement on the recommendation for reduced salt intake as a public health issue, the mechanism by which high salt intake triggers pathological effects on the cardio-renal axis is not completely understood. Emerging evidence indicates that the renin-angiotensin-aldosterone system (RAAS) is the main target of high Na⁺ intake. An inappropriate activation of tissue RAAS may lead to hypertension and organ damage. We reviewed the impact of high salt intake on the RAAS on the cardio-renal axis highlighting the molecular pathways that leads to injury effects. We also provide an assessment of recent observational studies related to the consequences of non-osmotically active Na⁺ accumulation, breaking the paradigm that high salt intake necessarily increases plasma Na⁺ concentration promoting water retention

Nutritional treatment of advanced CKD: twenty consensus statements

The Italian nephrology has a long tradition and experience in the field of dietetic-nutritional therapy (DNT), which is an important component in the conservative management of the patient suffering from a chronic kidney disease, which precedes and integrates the pharmacological therapies. The objectives of DNT include the maintenance of an optimal nutritional status, the prevention and/or correction of signs, symptoms and complications of chronic renal failure and, possibly, the delay in starting of dialysis. The DNT includes modulation of protein intake, adequacy of caloric intake, control of sodium and potassium intake, and reduction of phosphorus intake. For all dietary-nutritional therapies, and in particular those aimed at the patient with chronic renal failure, the problem of patient adherence to the dietetic-nutritional scheme is a key element for the success and safety of the DNT and it can be favored by an interdisciplinary and multi-professional approach of information, education, dietary prescription and follow-up. This consensus document, which defines twenty essential points of the nutritional approach to patients with advanced chronic renal failure, has been written, discussed and shared by the Italian nephrologists together with representatives of dietitians (ANDID) and patients (ANED).

Microbiota metabolites: Pivotal players of cardiovascular damage in chronic kidney disease

In chronic kidney disease (CKD), cardiovascular (CV) damage is present in parallel which leads to an increased risk of CV disease. Both traditional and non-traditional risk factors contribute to CV damage in CKD. The systemic role of the microbiota as a central player in the pathophysiology of many organs is progressively emerging in the literature: the microbiota is indeed involved in a complex, bi-directional network between many organs, including the kidney and heart connection, although many of these relationships still need to be elucidated through in-depth mechanistic studies. The aim of this review is to provide evidence that microbiota metabolites influence non-traditional risk factors, such as inflammation and endothelial dysfunction in CKD-associated CV damage. Here, we report our current understanding and hypotheses on the gut-kidney and gut-heart axes and provide details on the potential mechanisms mediated by microbial metabolites. More specifically, we summarize some novel hypotheses linking the microbiota to blood pressure regulation and hypertension. We also emphasise the idea that the nutritional management of CKD should be redesigned and include the new findings from research on the intrinsic plasticity of the microbiota and its metabolites in response to food intake. The need is felt to integrate the classical salt and protein restriction approach for CKD patients with foods that enhance intestinal wellness. Finally, we discuss the new perspectives, especially the importance of taking care of the microbiota in order to prevent the risk of developing CKD and hypertension, as well as the still not tested but very promising CKD innovative treatments, such as postbiotic supplementation and bacteriotherapy. This interesting area of research offers potential complementary approaches to the management of CKD and CV damage assuming that the causal mechanisms underlying the gut-kidney and gut-heart axes are clarified. This will pave the way to the design of new personalized therapies targeting gut microbiota.

Challenges in Treating Cardiovascular Disease: Restricting Sodium and Managing Hyperkalemia

High sodium intake, whether via diet or drugs, augments cardiorenal risk. Regardless of its source, high sodium intake can both lead to hypertension and reduce the efficacy of renin-angiotensin-aldosterone system inhibitors, which are currently guideline-recommended treatments for hypertension, chronic kidney disease, and heart failure. Reducing sodium intake is therefore recommended to reduce the risk of adverse cardiorenal outcomes. An inverse relationship exists between sodium and potassium, with foods high in sodium being lower in potassium. Diets high in potassium have been associated with reducing hypertension and heart failure; however, optimal renin-angiotensin-aldosterone system inhibitor dosing is often limited by hyperkalemia, which can lead to life-threatening cardiac arrhythmias and increased mortality. Potassium binders are effective at reducing potassium levels. Although some use sodium as the potassium exchange ion, thus increasing sodium intake, a new potassium binder uses another exchange ion and therefore does not increase sodium intake. When treatment options require agents that may precipitate hyperkalemia, particularly in patients at high cardiorenal risk, drugs that do not add to the sodium load may be preferred. A literature search was conducted using PubMed; search terms included potassium, sodium, hyperkalemia, potassium binders, and the literature search focused on manuscripts published more recently since 2000.

Dietary restriction but not angiotensin II type 1 receptor blockade improves DNA damage-related vasodilator dysfunction in rapidly aging Ercc1Δ/− mice

DNA damage is an important contributor to endothelial dysfunction and age-related vascular disease. Recently, we demonstrated in a DNA repair-deficient, prematurely aging mouse model (Ercc1Δ/− mice) that dietary restriction (DR) strongly increases life- and health span, including ameliorating endothelial dysfunction, by preserving genomic integrity. In this mouse mutant displaying prominent accelerated, age-dependent endothelial dysfunction we investigated the signaling pathways involved in improved endothelium-mediated vasodilation by DR, and explore the potential role of the renin-angiotensin system (RAS). Ercc1Δ/− mice showed increased blood pressure and decreased aortic relaxations to acetylcholine (ACh) in organ bath experiments. Nitric oxide (NO) signaling and phospho-Ser1177-eNOS were compromised in Ercc1Δ/−. DR improved relaxations by increasing prostaglandin-mediated responses. Increase of cyclo-oxygenase 2 and decrease of phosphodiesterase 4B were identified as potential mechanisms. DR also prevented loss of NO signaling in vascular smooth muscle cells and normalized angiotensin II (Ang II) vasoconstrictions, which were increased in Ercc1Δ/− mice. Ercc1Δ/− mutants showed a loss of Ang II type 2 receptor-mediated counter-regulation of Ang II type 1 receptor-induced vasoconstrictions. Chronic losartan treatment effectively decreased blood pressure, but did not improve endothelium-dependent relaxations. This result might relate to the aging-associated loss of treatment efficacy of RAS blockade with respect to endothelial function improvement. In summary, DR effectively prevents endothelium-dependent vasodilator dysfunction by augmenting prostaglandin-mediated responses, whereas chronic Ang II type 1 receptor blockade is ineffective.

Effects of Vitamin D Receptor Activation and Dietary Sodium Restriction on Residual Albuminuria in CKD: The ViRTUE-CKD Trial

Reduction of residual albuminuria during single-agent renin-angiotensin-aldosterone blockade is accompanied by improved cardiorenal outcomes in CKD. We studied the individual and combined effects of the vitamin D receptor activator paricalcitol (PARI) and dietary sodium restriction on residual albuminuria in CKD. In a multicenter, randomized, placebo (PLAC)-controlled, crossover trial, 45 patients with nondiabetic CKD stages 1-3 and albuminuria >300 mg/24 h despite ramipril at 10 mg/d and BP<140/90 mmHg were treated for four 8-week periods with PARI (2 μg/d) or PLAC, each combined with a low-sodium (LS) or regular sodium (RS) diet. We analyzed the treatment effect by linear mixed effect models for repeated measurements. In the intention-to-treat analysis, albuminuria (geometric mean) was 1060 (95% confidence interval, 778 to 1443) mg/24 h during RS + PLAC and 990 (95% confidence interval, 755 to 1299) mg/24 h during RS + PARI (P=0.20 versus RS + PLAC). LS + PLAC reduced albuminuria to 717 (95% confidence interval, 512 to 1005) mg/24 h (P<0.001 versus RS + PLAC), and LS + PARI reduced albuminuria to 683 (95% confidence interval, 502 to 929) mg/24 h (P<0.001 versus RS + PLAC). The reduction by PARI beyond the effect of LS was nonsignificant (P=0.60). In the per-protocol analysis restricted to participants with ≥95% compliance with study medication, PARI did provide further albuminuria reduction (P=0.04 LS + PARI versus LS + PLAC). Dietary adherence was good as reflected by urinary excretion of 174±64 mmol Na⁺ per day in the combined RS groups and 108±61 mmol Na⁺ per day in the LS groups (P<0.001). In conclusion, moderate dietary sodium restriction substantially reduced residual albuminuria during fixed dose angiotensin-converting enzyme inhibition. The additional effect of PARI was small and nonsignificant.