Albuminuria, Forgotten No More: Underlining the Emerging Role in CardioRenal Crosstalk

Kidneys have an amazing ability to adapt to adverse situations, both acute and chronic. In the presence of injury, the kidney is able to activate mechanisms such as autoregulation or glomerular hyperfiltration to maintain the glomerular filtration rate (GFR). While these adaptive mechanisms can occur in physiological situations such as pregnancy or high protein intake, they can also occur as an early manifestation of diseases such as diabetes mellitus or as an adaptive response to nephron loss. Although over-activation of these mechanisms can lead to intraglomerular hypertension and albuminuria, other associated mechanisms related to the activation of inflammasome pathways, including endothelial and tubular damage, and the hemodynamic effects of increased activity of the renin-angiotensin-aldosterone system, among others, are recognized pathways for the development of albuminuria. While the role of albuminuria in the progression of chronic kidney disease (CKD) is well known, there is increasing evidence of its negative association with cardiovascular events. For example, the presence of albuminuria is associated with an increased likelihood of developing heart failure (HF), even in patients with normal GFR, and the role of albuminuria in atherosclerosis has recently been described. Albuminuria is associated with adverse outcomes such as mortality and HF hospitalization. On the other hand, it is increasingly known that the systemic effects of congestion are mainly preceded by increased central venous pressure and transmitted retrogradely to organs such as the liver or kidney. With regard to the latter, a new entity called congestive nephropathy is emerging, in which increased renal venous pressure can lead to albuminuria. Fortunately, the presence of albuminuria is modifiable and new treatments are now available to reverse this common risk factor in the cardiorenal interaction.

Nonsteroidal Mineralocorticoid Receptor Antagonist (Finerenone) in Cardiorenal Disease

Nonsteroidal mineralocorticoid receptor antagonists (MRAs) present a promising therapeutic option in cardiorenal diseases, mitigating the limitations of steroidal MRAs. Finerenone, a third-generation nonsteroidal MRA, has demonstrated beneficial effects in heart failure (HF) and chronic kidney disease (CKD). Clinical trials, including FIDELIO-DKD and FIGARO-DKD, revealed finerenone's efficacy in improving kidney and cardiovascular (CV) outcomes. Patients with CKD and type 2 diabetes (T2DM) on finerenone experienced reduced rates of cardiovascular events, including hospitalization for HF. However, these trials excluded symptomatic HF patients, focusing on asymptomatic or early-stage HF. The ongoing FINEARTS-HF trial evaluates finerenone in HF with preserved ejection fraction (HFpEF). Additionally, studies exploring finerenone and sodium-glucose cotransporter 2 (SGLT2) inhibitors' (Empagliflozin) combination effects in CKD and T2DM (CONFIDENCE) and the selective MR modulator AZD9977 with another SGLT2 inhibitor (dapagliflozin) in HF and CKD (MIRACLE) aim to expand treatment options. While SGLT-2 inhibitors were shown to reduce hyperkalemia risk in FIDELIO-DKD and potentially lower new-onset HF incidence in FIGARO-DKD, further research is essential. So far, the evidence for the beneficial effect of finerenone in the spectrum of cardiorenal diseases is based only on the results of studies conducted in patients with T2DM, and clinical trials of finerenone in patients with nondiabetic kidney disease are ongoing. Nonsteroidal MRAs hold significant potential as pivotal treatment targets across the cardiorenal disease spectrum. This review will focus on the effects of finerenone on cardiorenal disease.

Industrial Use of Phosphate Food Additives: A Mechanism Linking Ultra-Processed Food Intake to Cardiorenal Disease Risk?

The consumption of ultra-processed food (UPF) keeps rising, and at the same time, an increasing number of epidemiological studies are linking high rates of consumption of UPF with serious health outcomes, such as cardiovascular disease, in the general population. Many potential mechanisms, either in isolation or in combination, can explain the negative effects of UPF. In this review, we have addressed the potential role of inorganic phosphate additives, commonly added to a wide variety of foods, as factors contributing to the negative effects of UPF on cardiorenal disease. Inorganic phosphates are rapidly and efficiently absorbed, and elevated serum phosphate can lead to negative cardiorenal effects, either directly through tissue/vessel calcification or indirectly through the release of mineral-regulating hormones, parathyroid hormone, and fibroblast growth factor-23. An association between serum phosphate and cardiovascular and bone disease among patients with chronic kidney disease is well-accepted by nephrologists. Epidemiological studies have demonstrated an association between serum phosphate and dietary phosphate intake and mortality, even in the general American population. The magnitude of the role of inorganic phosphate additives in these associations remains to be determined, and the initial step should be to determine precise estimates of population exposure to inorganic phosphate additives in the food supply.

SGLT2 Inhibitors: The Next Blockbuster Multifaceted Drug?

Sodium glucose cotransporter 2 inhibitor (SGLT2i) is a class of drugs that were originally intended for decreasing blood glucose in diabetes. However, recent trials have shown that there are other beneficial effects. Major clinical trials involving SGLT2i medications from 2015 to 2022 were reviewed using PUBMED search. Recent major SGLT2i landmark trials have demonstrated benefits for cardiovascular disease (reduce major adverse cardiovascular events (heart attack, stroke, cardiovascular death), hospitalization for heart failure, all-cause death), and renal disease (delay the onset of dialysis) regardless of diabetic status. The consistent cardiorenal benefits observed in major landmark trials have resulted in the rapid adoption of SGLT2i therapy not only in diabetes guidelines but also cardiovascular and renal guidelines.

Cardiovascular changes in young renal failure patients

Progresses in medical care of severe kidney disease and congenital anomalies of kidney and urinary tract make it possible for a higher percentage of young renal failure patients to survive and enter adulthood. There is thus an increasing need to focus on the long-term effects of severely reduced kidney function early in life. Cardiovascular changes are known to contribute considerably in adulthood to the severe complications of renal failure. In young chronic kidney disease patients, there is limited knowledge of subclinical cardiovascular disease. In this issue of Clinical Kidney Journal, Lalayiannis et al. describe significant structural and functional cardiovascular changes in a young cohort of kidney failure patients with glomerular filtration rate <30 mL/min/1.73 m². Among the 100 patients between 5 and 30 years of age included in the study, 84 presented with signs of cardiovascular disease. There is a need for long-term follow-up data on cardiovascular consequences of renal failure early in life and evaluation of prophylactic and therapeutic measures that can ameliorate the overall prognosis for these patients. We look forward to planned future long-term data from this cohort as well as increased focus in general on cardiovascular changes in young renal failure patients.

Differentiation between emerging non-steroidal and established steroidal mineralocorticoid receptor antagonists: head-to-head comparisons of pharmacological and clinical characteristics

INTRODUCTION

Mineralocorticoid receptor (MR) antagonists (MRAs) provide cardiorenal protection. However steroidal MRAs might induce hyperkalemia and sex hormone-related adverse effects. Several novel non-steroidal MRAs are being developed that are highly selective for the MR and may have an improved safety profile.

AREAS COVERED

This narrative review summarizes data from head-to-head comparisons of emerging non-steroidal MRAs with older steroidal MRAs, including pharmacological characteristics, pharmacokinetic properties, clinical outcomes, and safety, and highlights similarities and differences between emerging agents and established steroidal MRAs.

EXPERT OPINION

Head-to-head comparisons in phase 2 trials suggest that the new non-steroidal MRAs exhibit at least equivalent efficacy to steroidal MRAs but may have a better safety profile in patients with heart failure and/or kidney disease. When also taking into account data from recent phase 3 placebo-controlled trials, these novel non-steroidal MRAs have the potential to provide a cardiorenal benefit above that of current optimized standard-of-care treatment in a high-risk population with reduced renal function, and with a lower risk of hyperkalemia. To optimize therapy, further research is needed to clarify the molecular differences in the mode of action of non-steroidal MRAs versus steroidal MRAs, and biomarkers that are predictive of MRA response need to be identified and validated.

Interventions to empower cardiorenal patients: A systematic review

AIMS

To identify the most effective interventions to empower cardiorenal patients.

DESIGN

A systematic review of the literature has been carried out.

DATA SOURCES

The PubMed, CINAHL, PsycINFO and Cochrane databases were reviewed, and journals in the field were manually searched between January and February 2020.

REVIEW METHODS

Five randomized clinical trials and quasi-experimental studies that met the selection and CONSORT & TREND methodological quality criteria were selected.

RESULTS

The evidence supports that there are no existing interventions aimed at empowering cardiorenal patients. However, the interventions to empower people with chronic kidney disease and heart failure suggest that their integration should address seven domains: patient education, sense of self-management, constructive coping, peer sharing, enablement, self-efficacy and quality of life.

CONCLUSION

A gap has been revealed in the literature regarding the empowerment of cardiorenal patients. This review provides relevant information to help design, implement and evaluate interventions to empower these patients by describing the strategies used to empower people experiencing both chronic conditions and the tools used for their assessment.

IMPACT

There is a need for further research to design, implement and evaluate a multidimensional intervention that favours the empowerment of cardiorenal patients by using valid and reliable instruments that measure the domains that constitute it in an integrated manner. Interventions aimed at empowering the cardiorenal patient should include seven domains: patient education, sense of self-management, constructive coping, peer sharing, enablement, self-efficacy and quality of life.

Cardiorenal Fat: A Cardiovascular Risk Factor With Implications in Chronic Kidney Disease

There is a growing interest in the potential role of adipose tissues in cardiac and renal pathophysiology, and determining the mechanisms by which fat compartments around the heart and kidneys influence cardiovascular disease is of clinical importance in both general and high-risk populations. Epicardial fat and perirenal fat have been associated with adverse outcomes in chronic kidney disease (CKD) patients. Epicardial fat is a rich source of free fatty acids and is capable of secreting inflammatory and pro-atherogenic cytokines that promote atherosclerosis through a local paracrine effect. Recent evidence has demonstrated that perirenal fat has a closer correlation with kidney diseases than other visceral fat deposits in obesity or metabolic disturbances. Moreover, perirenal fat has been reported as an independent risk factor for CKD progression and even associated with cardiorenal dysfunction. Accordingly, these forms of organ-specific fat deposits may act as a connecter between vascular and cardiorenal disease. This review explores the possible links between epicardial and perirenal fat and its significant role as a modulator of cardiorenal dysfunction in CKD patients.

The role of miR-29 family in disease

MicroRNAs are small noncoding RNAs that can bind to the target sites in the 3’‐untranslated region of messenger RNA to regulate posttranscriptional gene expression. Increasing evidence has identified the miR‐29 family, consisting of miR‐29a, miR‐29b‐1, miR‐29b‐2, and miR‐29c, as key regulators of a number of biological processes. Moreover, their abnormal expression contributes to the etiology of numerous diseases. In the current review, we aimed to summarize the differential expression patterns and functional roles of the miR‐29 family in the etiology of diseases including osteoarthritis, osteoporosis, cardiorenal, and immune disease. Furthermore, we highlight the therapeutic potential of targeting members of miR‐29 family in these diseases. We present miR‐29s as promoters of osteoblast differentiation and apoptosis but suppressors of chondrogenic and osteoclast differentiation, fibrosis, and T cell differentiation, with clear avenues for therapeutic manipulation. Further research will be crucial to identify the precise mechanism of miR‐29 family in these diseases and their full potential in therapeutics.

Umbilical artery histomorphometry: a link between the intrauterine environment and kidney development. J Dev Orig Health Dis. 2017;8:349-356. [PMID: 28260559 DOI: 10.1017/s2040174417000113]

Prematurity is a risk factor for hypertension, vascular stiffness, nephron deficit and adult onset cardiorenal disease. The vascular tree and kidneys share morphogenic drivers that promote maturation in utero before 36 weeks of gestation. Vascular elastin accrual terminates after birth leaving collagen to promote vascular stiffness. Our objective was to determine if the histomorphometry of the umbilical artery, an extension of the aorta, parallels nephron mass across gestational age groups. From a cohort of 54 newborns, 32 umbilical cord specimens were adequate for evaluation. The umbilical cord was sectioned, stained with trichrome, and digitalized. Muscular and collagenous areas of the umbilical artery were measured in pixels using the Image J 1.48q software. Total kidney volume was measured by ultrasound and factored by body surface area (TKV/BSA). The umbilical artery total area was significantly greater in term v. preterm infants (9.3±1.3 v. 7.0±2.0 mm2; P<0.05) and increased with gestational age; while the percent muscular and collagen areas were independent of gestational age (R 2=0.04; P=ns). Percent muscular area correlated positively with TKV/BSA (r=0.53; P=0.002); while an increase in collagen correlated inversely with kidney mass (r=-0.53; P=0.002). In conclusion, an enhanced % muscular area and presumed vascular elasticity was associated with increased renal mass in all infants. Umbilical artery histomorphometry provides a link between the intrauterine environment, vascular and kidney development.

The cardioprotective effect of melatonin and exendin-4 treatment in a rat model of cardiorenal syndrome

We investigated the cardioprotective effect of melatonin (Mel) and exendin-4 (Ex4) treatment in a rat model of cardiorenal syndrome (CRS). Adult male SD rats (n=48) were randomly and equally divided into sham control (SC), dilated cardiomyopathy (DCM) (doxorubicin 7 mg/kg i.p. every five days/4 doses), CRS (defined as DCM+CKD) only, CRS-Mel (20 mg/kg/d), CRS-Ex4 (10 μg/kg/d), and CRS-Mel-Ex4 groups. In vitro results showed protein expressions of oxidative stress (NOX-1/NOX-2/oxidized protein), DNA/mitochondrial damage (γ-H2AX/cytosolic cytochrome c), apoptosis (cleaved caspase-3/PARP), and senescence (β-galactosidase cells) biomarkers were upregulated, whereas mitochondrial ATP level was decreased in doxorubicin/p-cresol-treated H9c2 cells that were revised by Mel and Ex4 treatments (all P<.001). By day 60, LVEF was highest in the SC and lowest in the CRS, significantly lower in the DCM than in other treatment groups, lower in the CRS-Mel and CRS-Ex4 than in the CRS-Mel-Ex4, and lower in the CRS-Mel than in the CRS-Ex4, whereas LV chamber size and histopathology score showed a pattern opposite to that of LVEF among all groups (all P<.001). Plasma creatinine level was highest in the CRS and lowest in the SC and progressively decreased from the CRS-Mel, CRS-Ex4, CRS-Mel-Ex4 to DCM (P<.0001). Protein expressions of inflammation (TNF-α/NF-κB/MMP-2/MMP-9/IL-1β), apoptosis/DNA damage (Bax/c-caspase-3/c-PARP/γ-H2AX), fibrosis (Smad3/TGF-β), oxidative stress (NOX-1/NOX-2/NOX-4/oxidized protein), cardiac hypertrophy/pressure overload (BNP/β-MHC), and cardiac integrity (Cx43/α-MHC) biomarkers in LV myocardium showed an opposite pattern compared to that of LVEF among all groups (all P<.001). Fibrotic area, DNA damage (γ-H2AX⁺ /53BP1⁺ CD90⁺ /XRCC1⁺ CD90⁺ ), and inflammation (CD14⁺ /CD68⁺ ) biomarkers in LV myocardium displayed a pattern opposite to that of LVEF among all groups (all P<.001). Combined melatonin and exendin-4 treatment suppressed CRS-induced deterioration of LVEF and LV remodeling.

ADMA injures the glomerular filtration barrier: role of nitric oxide and superoxide

Chronic kidney disease (CKD) is associated with decreased renal nitric oxide (NO) production and increased plasma levels of methylarginines. The naturally occurring guanidino-methylated arginines N-monomethyl-l-arginine (l-NMMA) and asymmetric dimethyl-l-arginine (ADMA) inhibit NO synthase activity. We hypothesized that ADMA and l-NMMA compromise the integrity of the glomerular filtration barrier via NO depletion. We studied the effect of ADMA on albumin permeability (P(alb)) in isolated glomeruli and examined whether this effect involves NO- and superoxide (O(2)(*-))-dependent mechanisms. ADMA at concentrations found in circulation of patients with CKD decreased cGMP and increased P(alb) in a dose-dependent manner. A similar increase in P(alb) was caused by l-NMMA but at a concentration two orders of magnitude higher than that of ADMA. NO donor DETA-NONOate or cGMP analog abrogated the effect of ADMA on P(alb). The SOD mimetic tempol or the NAD(P)H oxidase inhibitor apocynin also prevented the ADMA-induced increase in P(alb). The NO-independent soluble guanylyl cyclase (sGC) activator BAY 41-2272, at concentrations that increased glomerular cGMP production, attenuated the ADMA-induced increase in P(alb). Furthermore, sGC incapacitation by the heme site-selective inhibitor ODQ increased P(alb). We conclude that ADMA compromises the integrity of the filtration barrier by altering the bioavailability of NO and O(2)(*-) and that NO-independent activation of sGC preserves the integrity of this barrier under conditions of NO depletion. NO-independent activation of sGS may be a useful pharmacotherapeutic approach for preservation of glomerular function in CKD thereby reducing the risk for cardiovascular events.