The Association between Nitric Oxide Pathway, Blood Pressure Abnormalities, and Cardiovascular Risk Profile in Pediatric Chronic Kidney Disease

Plasma and Urinary Platelet Factor 4 as Biomarkers for Cardiovascular Risk in Children with Chronic Kidney Disease

Children suffering from chronic kidney disease (CKD) have a high risk of cardiovascular disease (CVD). The early detection and diagnosis of subclinical CVD in pediatric CKD can reduce mortality later in life. Plasma factor 4 (PF4) is a chemokine released by activated platelets. We examined whether or not PF4 in the plasma and urine, its kidney function normalized ratio, and fractional excretion have differential associations with CVD risk markers in 139 youths aged 3 to 18 years old with CKD stages G1-G4. Significant negative correlations were observed between plasma PF4 and cardiovascular surrogate markers, such as the left ventricular mass index (LVMI), carotid intima-media thickness (cIMT), and pulse wave velocity (PWV). The plasma PF4/creatinine (Cr) ratio was lower in CKD children with a high daytime BP and 24 h BP, high BP load, and nocturnal non-dipping status. After adjusting for confounders, the plasma PF4 and plasma PF4/Cr ratio still independently predicted an abnormal ABPM profile. In addition, both the plasma PF4 and plasma PF4/Cr ratio presented a negative correlation with the L-arginine and asymmetric dimethylarginine ratio. These findings provide convincing evidence supporting the link between PF4 and CVD markers in pediatric CKD. Our study highlights the importance of further research to assess the performance of PF4-related biomarkers in predicting CVD events and CKD progression in children with CKD.

Comparisons of EQ-5D-Y and PedsQL in pediatric patients with mild-to-moderate chronic kidney disease in longitudinal analyses

OBJECTIVE

To characterize longitudinal changes and correlations between the measures of EQ-5D-Y and generic PedsQL and their associations with clinical changes in children and adolescents with mild-to-moderate chronic kidney disease (CKD).

METHODS

Participants were recruited from January 2017 to September 2021 in a medical center in Taiwan. Both instruments were administered in their initial visits and every 6-month subsequent visits. Spearman's Rho (ρ) was used to assess correlations between the scores of EQ-5D-Y and PedsQL measures in longitudinal changes. Cohen's effect size (ES) was used to evaluate the changes of scores/subscales over time. In addition, factors associated with longitudinal changes in the score/subscales were explored.

RESULTS

A total of 121 participants were enrolled, and 83 with ≥ 3 HRQOL measures during the 3.5 years follow-up were assessed their changes of HRQOL measures. The correlations (ρ > 0.3) appeared between the changes in the visual analog scale (VAS) of EQ-5D-Y and emotional and social subscales of PedsQL. ES was small (< 0.5) in the VAS and level-sum-score (LSS) of EQ-5D-Y scores for the clinical changes in comorbidities, while some PedsQL subscales were medium to high (0.5-0.8 or > 0.8). Hypertension, mineral bone disorder/anemia, and hyperuricemia associated with the changes in both HRQOL scores were varied by their various domains.

CONCLUSION

Both EQ-5D-Y and PedsQL of HRQOL measures were responsive to worsened childhood CKD-related comorbidities during the follow-up; however, convergent validity between them was limited in some domains. The LSS of EQ-5D-Y showed greater changes than the VAS by comorbidity status; further comparison with utility weight is needed to determine the better performance of EQ-5D-Y.

Pregnancy Zone Protein as an Emerging Biomarker for Cardiovascular Risk in Pediatric Chronic Kidney Disease

Cardiovascular disease (CVD) is a significant cause of mortality and morbidity among children with chronic kidney disease (CKD). The causes of pediatric CKD differ from those in adults, as congenital anomalies in the kidney and urinary tract (CAKUT) are the leading causes in childhood. Identifying ideal markers of CVD risk early is crucial for CKD children to improve their care. Previously, we screened differentially expressed proteins in CKD children with or without blood pressure (BP) abnormalities and identified pregnancy zone protein (PZP). In 106 children and adolescents with CKD stages G1-G4, we analyzed plasma PZP concentration. The associations between PZP and ambulatory BP monitoring (ABPM) profile, parameters of cardiac and carotid ultrasounds, indices of arterial stiffness, and nitric oxide (NO) parameters were determined. We observed that PZP positively correlated with arterial stiffness indices, beta index, and pulse wave velocity in CAKUT. CKD children with abnormalities in ABPM and night dipping displayed a higher PZP concentration than those without. Additionally, the PZP level was positively correlated with NO bioavailability. In conclusion, our results suggest PZP has differential influences on cardiovascular risk in CAKUT and non-CAKUT children. Identification of this relationship is novel in the pediatric CKD literature.

Aerobic Exercise versus Electronic Cigarette in Vascular Aging Process: First Histological Insight

Smoking is related to vascular aging. However, the hazardous effect of e-cigarette is often debatable, with limited studies available. In contrast, moderate-intensity aerobic exercise is well known to decrease aortic stiffness. We provide novel research to determine the effect of e-cigarette and aerobic moderate-intensity exercise on the aortic structure of Wistar rats. A total of 26 male Wistar rats (Rattus norvegicus) 8 weeks aged, 200-250 g b.w., were randomly divided into 4 groups, namely, K0 (normal rats), K1 (rats were given moderate-intensity aerobic exercise by animal treadmill 20 m/30 min), K2 (rats were given e-cigarette with 6 mg nicotine, 40% propylene glycol, and 60% vegetable glycerine 30 min for 5 days/week), and K3 (rats were given e-cigarette and moderate-intensity aerobic exercise). After exposure for 6 weeks, all animals were sacrificed to isolate the aorta for histopathological analysis with hematoxylin-eosin stain to evaluate the elastic fiber layer and intimal-medial thickness. The Verhoeff-Van Gieson staining was done for quantification elastic lamina fragmentation. Our study found that the e-cigarette group had the highest elastic lamina fragmentation among groups (8.14 ± 2.85). The exercise only group showed the lowest elastic lamina fragmentation (2.50 ± 1.87). Fragmentation in the e-cigarette and exercise group was higher than in the exercise only group (5.83 ± 0.753 vs. 2.50 ± 1.87, p = 0.002). There is a significant difference of NO serum between four groups. The result of post hoc analysis using LSD showed that there is a significant difference of NO serum between K0 and K2, K0 and K3, K1 and K2, and K1 and K3. Therefore, our research demonstrated that the most injury of aorta elastic lamina was in the group that was exposed to e-cigarette that leads to vascular aging while exercise is not yet proven to reverse this effect.

Arginine Dysregulation and Myocardial Dysfunction in a Mouse Model and Children with Chronic Kidney Disease

Cardiovascular disease is the leading cause of death in chronic kidney disease (CKD). Arginine, the endogenous precursor for nitric oxide synthesis, is produced in the kidneys. Arginine bioavailability contributes to endothelial and myocardial dysfunction in CKD. Plasma from 129X1/SvJ mice with and without CKD (5/6th nephrectomy), and banked plasma from children with and without CKD were analyzed for amino acids involved in arginine metabolism, ADMA, and arginase activity. Echocardiographic measures of myocardial function were compared with plasma analytes. In a separate experiment, a non-specific arginase inhibitor was administered to mice with and without CKD. Plasma citrulline and glutamine concentrations correlated with multiple measures of myocardial dysfunction. Plasma arginase activity was significantly increased in CKD mice at 16 weeks vs. 8 weeks (p = 0.002) and ventricular strain improved after arginase inhibition in mice with CKD (p = 0.03). In children on dialysis, arginase activity was significantly increased vs. healthy controls (p = 0.04). Increasing ADMA correlated with increasing RWT in children with CKD (r = 0.54; p = 0.003). In a mouse model, and children, with CKD, arginine dysregulation correlates with myocardial dysfunction.

Is There a Role for Imaging Youth at Risk of Atherosclerosis?

PURPOSE OF REVIEW

Cardiovascular (CV) risk factors such as dyslipidemia, hypertension, diabetes, and obesity are associated with an increased risk for CV events in adults. Noninvasive measures of vascular health are associated with these CV events and can potentially help risk stratify children with CV risk factors. The purpose of this review is to summarize recent literature regarding vascular health in children with cardiovascular risk factors.

RECENT FINDINGS

Adverse changes in pulse wave velocity, pulse wave analysis, arterial distensibility, and carotid intima-media thickness are seen in children with CV risk factors supporting potential utility in risk stratification. Assessing vascular health in children can be challenging due to growth-related changes in vasculature, multiple assessment modalities, and differences in normative data. Vascular health assessment in children with cardiovascular risk factors can be a valuable tool for risk stratification and help identify opportunities for early intervention. Future areas of research include increasing normative data, improving conversion of data between different modalities, and increasing longitudinal studies in children linking childhood risk factors to adult CV outcomes.

Anti-Hypertensive Property of an NO Nanoparticle in an Adenine-Induced Chronic Kidney Disease Young Rat Model

Hypertension is the most common complication of chronic kidney disease (CKD) in children but is still poorly controlled. Nitric oxide (NO) deficiency plays a pivotal role in CKD and hypertension. NO is known to have health benefits, while NO typically has a short half-life and is not specifically targeted. In this study, we used a pediatric CKD model, which was induced in young rats by feeding them 0.25% adenine. We investigated two different NO donors, namely S-nitrosoglutathione (GSNO) and diethylenetriamine/NO adduct (DETA NONOate) via intraperitoneal injection at 10 mg/kg/day daily for 3 weeks. GSNO was delivered by Cu²⁺-doped zeolitic imidazolate framework (Cu/ZIF-8) nanoparticles to generate NO. As a result, we observed Cu/ZIF-8 nanoparticles were successfully loaded with GSNO and were able to release NO. Young rats fed with adenine displayed kidney dysfunction and hypertension at 9 weeks of age, which were prevented by GSNO-loaded nanoparticle or DETA NONOate treatment. GSNO-loaded nanoparticles reduced CKD-induced hypertension, which was related to an enhanced endogenous NO-generating system, reduced renal oxidative stress, and downregulated several components belonging to the classic renin-angiotensin (RAS) system. Our results cast new light on targeting NO delivery through the use of nanoparticles aiming to improve child-focused outcomes related to CKD worthy of clinical translation.

Differences in health-related quality of life in children with chronic kidney disease as reported by children and parent proxies

BACKGROUND

Correlation between reports of children and parent for health-related quality of life (HRQOL) is not well studied. This study aims to assess the degree of agreement between child self- and parent proxy-rated HRQOL and to identify factors associated with discordance at baseline and during follow-up in Taiwanese children with chronic kidney disease (CKD).

METHODS

This study includes pediatric patients aged 5-18 years with confirmed CKD. Participants completed the generic version of the Pediatric Quality of Life Inventory (PedsQL) at baseline and every 6 months during follow-up. Child-parent agreement on HRQOL reports was assessed using intraclass correlation coefficient (ICC). Multivariate regression models were used to determine factors associated with child-parent discordance.

RESULTS

Of the 112 child-parent dyads included in the analysis, 97 dyads with 640 patient visits were assessed in 4.5 years. Children reported higher total scores on the physical and psychosocial domains as compared to their parent proxies. ICC was low (< 0.5) for the psychosocial domain and moderate for the physical health domain at initial assessment and slightly increased for the physical health (0.62) and for school functioning (0.51) during follow-up. Development of mineral bone disorder/anemia (β, 11.75 [3.77-19.72]) and proteinuria (β, 8.48 [1.15-15.81]) in the follow-up were associated with increased discordance in school functioning, and fathers with chronic disease were associated with increased discordance in social functioning (β, 4.21 [0.68-7.74]).

CONCLUSIONS

Parent proxy consistently estimated lower PedsQL score compared to self-reports of children. Child self-rated psychosocial health domains should be evaluated whenever possible to better elucidate treatment outcome over time. A higher resolution version of the Graphical abstract is available as Supplementary information.

Asymmetric and Symmetric Dimethylarginines as Renal Function Parameters in Paediatric Kidney Diseases: A Literature Review from 2003 to 2022

Asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA), inhibitors of nitric oxide synthase, play important roles in many processes in the body. Most data in the literature concern their importance in adult chronic kidney disease (CKD). According to them, SDMA well reflects the glomerular filtration rate (GFR), and higher ADMA concentrations are associated with hypertension and higher mortality. In addition, both substances are recognised cardiovascular risk factors in CKD. The purpose of this review was to summarise the studies on dimethylarginines in renal diseases in children, about which we have much fewer data. The review focuses specifically on dimethylarginine's relation to routinely used renal function parameters. Finally, we analysed 21 of the 55 articles published between 2003 and 2022 on dimethylarginines in kidney diseases in children (from birth to 18 years of age), obtained by searching PubMed/MEDLINE (search terms: "dimethylarginine" and "kidney").

Cardiovascular Risks of Hypertension: Lessons from Children with Chronic Kidney Disease

Hypertension is the most common complication of chronic kidney disease (CKD) in children, having a strong association with subsequential cardiovascular disease (CVD). In pediatric CKD, a considerable percentage of children with hypertension are undiagnosed or undertreated. Prior research has evaluated structural and functional markers of subclinical CVD and biomarkers in adults with CKD, while ideal biomarkers in pediatrics are still insufficiently studied. The ultimate goal of this review is to summarize what is currently known about state of hypertension, cardiovascular risk factors, and potential CVD markers/biomarkers in children with pre-dialysis CKD. We discuss omics-related biomarkers and the pathophysiologic processes of endothelial dysfunction, kidney injury, oxidative stress and inflammation that are classified by specific biomarkers. Moreover, we illustrate the existing challenges and highlight the paucity of pediatric CKD research to evaluate these CVD biomarkers for future clinical pediatric practice. Thus, achieving clinical utility of CVD biomarkers for use in pediatric CKD remains a significant challenge requiring additional efforts.

Arterial Stiffness and Chronic Kidney Disease Progression in Children

BACKGROUND AND OBJECTIVES

CKD has been linked to increased arterial stiffness in adults, but data in children with CKD remain conflicting. We aimed to investigate the longitudinal dynamics and determinants of pulse wave velocity in children with CKD and its association with CKD progression.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed an analysis of the Cardiovascular Comorbidity in Children with Chronic Kidney Disease (4C) study, which prospectively followed children aged 6-17 years with CKD stages 3-5. Follow-up was censored at the time of KRT initiation. Two separate analyses were performed: with absolute pulse wave velocity (primary outcome) and with pulse wave velocity standardized to height (z score; restricted to participants ≤17 years) as a sensitivity analysis.

RESULTS

In total, 667 patients with a mean baseline eGFR of 27 ml/min per 1.73 m2 were included. Pulse wave velocity above the 95th percentile was observed in 124 (20%) patients at baseline. Absolute pulse wave velocity increased gradually over the median follow-up of 2.7 (interquartile range, 0.7-4.4) years, whereas pulse wave velocity z score remained relatively stable. Absolute pulse wave velocity over time associated with time; older age; higher mean arterial pressure, LDL cholesterol, and albuminuria; and lower ferritin. Pulse wave velocity z score (n=628) was associated with the same variables and additionally, with higher diastolic BP z score, lower height z score, younger age, and girls. Of 628 patients, 369 reached the composite end point of CKD progression (50% eGFR loss, eGFR <10 ml/min per 1.73 m2, or the start of KRT) during a median follow-up of 2.4 (interquartile range, 0.9-4.6) years. Pulse wave velocity z score did not associate with CKD progression by univariable or multivariable proportional hazard analysis correcting for the established predictors eGFR, proteinuria, and BP.

CONCLUSIONS

Pulse wave velocity is increased in children with CKD but does not associate with eGFR or CKD progression.

Hydrogen Sulfide-to-Thiosulfate Ratio Associated with Blood Pressure Abnormalities in Pediatric CKD

Identifying children with chronic kidney disease (CKD) at high risk of cardiovascular disease (CVD) and ensuring they receive appropriate treatment can prevent CVD events and mortality later in life. Hydrogen sulfide (H2S) is a gaseous signaling molecule participating in CVD and CKD. Thiosulfate is not only an oxidation product of H2S but is also a H2S donor. We examined whether H2S, thiosulfate, and their combined ratio have differential associations with CVD risk markers in 56 children and adolescents aged 6–18 years with CKD stages G1–G4. Up to two-thirds of CKD children showed higher BP load on 24 h ambulatory blood pressure monitoring (ABPM), even in the early stage. CKD children with ABPM abnormalities had a higher H2S-to-thiosulfate ratio, while H2S-related parameters were not affected by the severity of CKD. The H2S-to-thiosulfate ratio was positively correlated with 24 h systolic BP (SBP), nighttime SBP, and carotid artery intima-media thickness (cIMT). After adjusting for confounders, H2S was negatively associated with LV mass, thiosulfate was positively associated with 24-DBP, and the H2S-to-thiosulfate ratio was positively correlated with nighttime SBP and cIMT. Our data demonstrate differential associations in circulating H2S, thiosulfate, and their combined ratio with CVD risk in childhood CKD. Further studies are required to determine whether targeting the H2S signaling pathway can develop novel therapeutic strategies against CVD in this high-risk population.

Complement Factor H and Related Proteins as Markers of Cardiovascular Risk in Pediatric Chronic Kidney Disease

Cardiovascular disease (CVD) is the main cause of mortality among chronic kidney disease (CKD) patients, both in adults and in children. Hypertension is one of the risk factors of CVD. For early detection of subclinical CVD in pediatric CKD, 24 h ambulatory blood pressure monitoring (ABPM), cardiosonography, and arterial stiffness assessment were evaluated. CAKUT (congenital anomalies of the kidney and urinary tract) are the main etiologies of pediatric CKD. Previously, by a proteomic approach, we identified complement factor H (CFH) and related proteins differentially expressed between children with CAKUT and non-CAKUT CKD. In this study, we aimed to evaluate whether CFH, CFH-related protein-2 (CFHR2), and CFH-related protein-3 (CFHR3) were related to CVD risk in children with CKD. This study included 102 subjects aged 6 to 18 years old. The non-CAKUT group had higher plasma CFHR3 levels than the CAKUT group (p = 0.046). CFHR3 was negatively correlated with LV mass (p = 0.009). CFHR2 was higher in children with CKD with 24 h hypertension in the ABPM profile (p < 0.05). In addition, children with non-CAKUT CKD with day-time hypertension (p = 0.036) and increased BP load (p = 0.018) displayed a lower plasma CFHR3 level. Our results highlight that CFH and related proteins play a role for CVD in children with CKD. Early assessment of CFH, CFHR2, and CFHR3 may have clinical utility in discriminating CV risk in children with CKD with different etiologies.

Metabolomics of Arterial Stiffness

Arterial stiffness (AS) is one of the earliest detectable signs of structural and functional alterations of the vessel wall and an independent predictor of cardiovascular events and death. The emerging field of metabolomics can be utilized to detect a wide spectrum of intermediates and products of metabolism in body fluids that can be involved in the pathogenesis of AS. Research over the past decade has reinforced this idea by linking AS to circulating acylcarnitines, glycerophospholipids, sphingolipids, and amino acids, among other metabolite species. Some of these metabolites influence AS through traditional cardiovascular risk factors (e.g., high blood pressure, high blood cholesterol, diabetes, smoking), while others seem to act independently through both known and unknown pathophysiological mechanisms. We propose the term 'arteriometabolomics' to indicate the research that applies metabolomics methods to study AS. The 'arteriometabolomics' approach has the potential to allow more personalized cardiovascular risk stratification, disease monitoring, and treatment selection. One of its major goals is to uncover the causal metabolic pathways of AS. Such pathways could represent valuable treatment targets in vascular ageing.

Dimethylarginines in Children after Anti-Neoplastic Treatment

Background and Objectives: According to a recent Cochrane systematic review, renal impairment can develop in 0–84% of childhood cancer survivors in the future. The renal function impairment in this patient group can be related to nephrectomy, nephrotoxic agents therapy, abdominal radiotherapy, and combinations of these treatment methods. In this study, in a population of patients after anti-neoplastic therapy, with particular emphasis on patients after Wilms’ tumour treatment, we compared new substances which play role in the chronic kidney disease (CKD) pathogenesis (asymmetric dimethylarginine—ADMA, symmetric dimethylarginine—SDMA) with standard renal function markers (e.g., creatinine and cystatin C in serum, creatinine in urine, etc.) to assess the usefulness of the former. Materials and Methods: Eighty-four children, without CKD, bilateral kidney tumours, congenital kidney defects, or urinary tract infections, with a minimum time of 1 year after ending anti-neoplastic treatment, aged between 17 and 215 months, were divided into three groups: group 1—patients after nephroblastoma treatment (n = 21), group 2—after other solid tumours treatment (n = 44), and group 3—after lymphoproliferative neoplasms treatment (n = 19). The patients’ medical histories were taken and physical examinations were performed. Concentrations of blood urea nitrogen (BUN), creatinine, cystatin C, C-reactive protein (CRP), ADMA, and SDMA in blood and albumin in urine were measured, and a general urine analysis was performed. The SDMA/ADMA ratio, albumin–creatine ratio, and estimated glomerular filtration rate (eGFR) were calculated. eGFR was estimated by three equations recommended to the paediatric population by the KDIGO from 2012: the Schwartz equation (eGFR1), equation with creatinine and urea nitrogen (eGFR2), and equation with cystatin C (eGFR3). Results: Both the eGFR1 and eGFR2 values were significantly lower in group 1 than in group 3 (eGFR1: 93.3 (83.1–102.3) vs. 116.5 (96.8–126.9) mL/min/1.73 m², p = 0.02; eGFR2: 82.7 (±14.4) vs. 94.4 (±11.9) mL/min/1.73 m², p = 0.02). Additionally, there were weak positive correlations between SDMA and creatinine (p < 0.05, r = 0.24), and cystatin C (p < 0.05, r = 0.32) and weak negative correlations between SDMA and eGFR1 (p < 0.05, r = −0.25), eGFR2 (p < 0.05, r = −0.24), and eGFR3 (p < 0.05, r = −0.32). Conclusions: The usefulness of ADMA and SDMA in the diagnosis of renal functional impairment should be assessed in further studies. eGFR, calculated according to equations recommended for children, should be used in routine paediatric practice.

Resveratrol Butyrate Ester Protects Adenine-Treated Rats against Hypertension and Kidney Disease by Regulating the Gut–Kidney Axis

Despite recent advances in pharma-nutritional management, chronic kidney disease (CKD) remains an increasingly prevalent disorder. Resveratrol, a pleiotropic phytochemical, has been found to reduce the risk for several chronic diseases. Considering the low bioavailability of resveratrol, we recently synthesized resveratrol butyrate ester (RBE) via the esterification of resveratrol with butyrate. The aim of this study was to examine the effectiveness of RBE as regards protection from hypertension and kidney damage and explore the underlying mechanisms using a young rat adenine-induced CKD model. Three-week-old male Sprague Dawley rats received regular or 0.5% adenine chow for three weeks. Three groups of adenine-fed CKD rats (N = 8/group) received resveratrol (50 mg/L), or a low dose (25 mg/L) or high dose (50 mg/L) of RBE in drinking water from week 6 to week 12. As compared with the controls, adenine-treated rats had markedly increased creatinine levels and blood pressure, which was associated with renal hypertrophy and decreased creatinine clearance. Treatment with resveratrol or a low or high dose of RBE, similarly protected adenine-fed rats against hypertension and kidney damage. CKD-induced hypertension is associated with an altered gut microbiota profile, dysregulated renal short chain fatty acid (SCFA) receptor expression, activation of the aryl hydrocarbon receptor (AhR) signaling pathway, and reduced nitric oxide bioavailability. We found gut microbiota compositions were shaped differentially by resveratrol and RBE treatment in adenine-treated CKD rats. The beneficial effect of high-dose RBE was associated with reduced renal expression of SCFA G protein-coupled receptor 41 (GPR41) and olfactory receptor 78 (Olfr78), antagonizing the AhR signaling pathway, and increased abundance of beneficial bacteria such as genera Akkermansia, Blautia, and Enterococcus. Our study provided the first evidence documenting RBE as a novel phytochemical supplement targeting the gut–kidney axis to protect against adenine-induced kidney damage and hypertension.

Asymmetric Dimethylarginine (ADMA) in Pediatric Renal Diseases: From Pathophysiological Phenomenon to Clinical Biomarker and Beyond

Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide (NO) synthase inhibitor, inhibits NO synthesis and contributes to the pathogenesis of many human diseases. In adults, ADMA has been identified as a biomarker for chronic kidney disease (CKD) progression and cardiovascular risk. However, little attention is given to translating the adult experience into the pediatric clinical setting. In the current review, we summarize circulating and urinary ADMA reported thus far in clinical studies relating to kidney disease in children and adolescents, as well as systematize the knowledge on pathophysiological role of ADMA in the kidneys. The aim of this review is also to show the various analytical methods for measuring ADMA and the issues tht need to be addressed before transforming to clinical practice in pediatric medicine. The last task is to suggest that ADMA may not only be suitable as a diagnostic or prognostic biomarker, but also a promising therapeutic strategy to treat pediatric kidney disease in the future.

Fat Mass Index Associated with Blood Pressure Abnormalities in Children with Chronic Kidney Disease

Cardiovascular disease (CVD) risk factors are present early in life in children with chronic kidney disease (CKD), consequently cardiovascular morbidity presents in early adulthood. However, risk factors of CVD have been rarely addressed in children with early stage of CKD. This study included 63 children and adolescents aged 8- to 18 years-old with CKD stage G1–G4. Cardiovascular assessments consisted of 24-h ambulatory blood pressure monitoring (ABPM), arterial stiffness index, and echocardiography. We also applied dual-energy x-ray absorptiometry (DXA) scanning to analyze percentage body fat (PBF), lean body mass index (LBMI), fat mass index (FMI), and the android to gynoid fat ratio (A/G ratio). Up to 63.5% of CKD children had abnormal changes in BP detected by ABPM. CKD children with abnormal ABPM were older, had higher numbers of CKD stage G2 to G4, hyperuricemia, obesity, and higher FMI z-score and A/G ratio compared to individuals with normal ABPM (all p < 0.05). Among these factors, only FMI z-score showed an independent association with abnormal ABPM using multivariate logistic regression analysis (p = 0.037). Our data highlight that body fat plays a key role for an abnormal ABPM in CKD children. The assessment of FMI may have clinical utility in discriminating CV risk in children and adolescents with early stages of CKD.

Endothelial dysfunction in children with chronic kidney disease

BACKGROUND AND OBJECTIVE

Cardiovascular disease (CVD) is the main cause of death in children with chronic kidney disease (CKD). Inflammation and endothelial dysfunction (ED) are found in the majority of these patients and are factors associated to CVD. Flow mediated dilatation (FMD) is a surrogate marker validated for evaluating ED. Our objective was to identify risk factors associated to ED in children with CKD.

MATERIALS AND METHODS

Children 2-16 years of age were studied. Clinical information and biochemical variables were gathered, including intact parathyroid hormone (iPTH), interleukins 6 and 1b, high sensitivity C reactive protein (hsCRP), reduced glutathione, nitric oxide, malondialdehyde and homocysteine. FMD was measured, and considered altered if <7%.

RESULTS

Included were 129 patients aged 13.1 ± 2.6 years. FMD < 7% was found in 69 (52.7%). Patients with altered FMD had higher levels of triglycerides and hsCRP than those with normal FMD (145.5 mg/dl vs. 120.0 mg/dl, P = .042, y 1.24 U/L vs. 0.55 U/L, P = .007, respectively), as well as higher frequency of low iPTH (19.1% vs. 4.9%, P = .036). Levels of hsCRP correlated significantly with FMD (Rho = -0.28, P = .003). Patients with low iPTH (OR = 4.41, 95%CI 1.13-17.27, P = .033) and increased hsCRP (OR = 2.89, 95%CI 1.16-7.17, P = .022) had higher adjusted risk of having FMD < 7%.

CONCLUSIONS

Hypertriglyceridemia, inflammation and low iPTH associated significantly with altered FMD. They are frequent, treatable risk factors for CVD.

Pathophysiology and consequences of arterial stiffness in children with chronic kidney disease

Changes in arterial structure and function are seen early in the course of chronic kidney disease (CKD) and have been causally associated with cardiovascular (CV) morbidity. Numerous potential injuries encompassing both traditional and uremia-specific CV risk factors can induce structural arterial changes and accelerate arterial stiffening. When the buffering capacity of the normally elastic arteries is reduced, damage to vulnerable microcirculatory beds can occur. Moreover, the resultant increase to cardiac afterload contributes to the development of left ventricular hypertrophy and cardiac dysfunction. Adult studies have linked arterial stiffness with increased risk of mortality, CV events, cognitive decline, and CKD progression. Pulse wave velocity (PWV) is currently the gold standard of arterial stiffness assessment but its measurement in children is challenging due to technical difficulties and physiologic aspects related to growth and poor standardization between algorithms for calculating PWV. Nevertheless, studies in pediatric CKD have reported increased arterial stiffness in children with advanced CKD, on dialysis, and after kidney transplantation. Development of arterial stiffness in children with CKD is closely related to mineral-bone disease and hypertension, but other factors may also play a significant role. The clinical relevance of accelerated arterial stiffness in childhood on cardiovascular outcomes in adult life remains unclear, and prospective studies are needed. In this review we discuss mechanisms leading to arterial stiffness in CKD and its clinical implications, along with issues surrounding the technical aspects of arterial stiffness assessment in children.

Endothelial dysfunction in children with chronic kidney disease

BACKGROUND AND OBJECTIVE

Cardiovascular disease is the main cause of death in children with chronic kidney disease. Inflammation and endothelial dysfunction are found in the majority of these patients and are factors associated to cardiovascular disease. Flow mediated dilatation (FMD) is a surrogate marker validated for evaluating endothelial dysfunction. Our objective was to identify risk factors associated to endothelial dysfunction in children with chronic kidney disease.

MATERIALS AND METHODS

Children 2-16 years of age were studied. Clinical information and biochemical variables were gathered, including intact parathyroid hormone (iPTH), interleukins 6 and 1β, high sensitivity C reactive protein (hsCRP), reduced glutathione, nitric oxide, malondialdehyde and homocysteine. FMD was measured, and considered altered if<7%.

RESULTS

Included were 129 patients aged 13.1±2.6 years. FMD<7% was found in 69 (52.7%). Patients with altered FMD had higher levels of triglycerides and hsCRP than those with normal FMD (145.5 vs. 120.0mg/dL, P=.042, and 1.24 vs. 0.55U/L, P=.007, respectively), as well as higher frequency of low iPTH (19.1 vs. 4.9%, P=.036). Levels of hsCRP correlated significantly with FMD (Rho=-0.28, P=.003). Patients with low iPTH (OR 4.41, 95% CI 1.13-17.27, P=.033) and increased hsCRP (OR 2.89, 95% CI 1.16-7.17, P=.022) had higher adjusted risk of having FMD<7%.

CONCLUSIONS

Hypertriglyceridemia, inflammation and low iPTH associated significantly with altered FMD. They are frequent, treatable risk factors for cardiovascular disease.

Cardiovascular Disease Risk in Children With Chronic Kidney Disease: Impact of Apolipoprotein C-II and Apolipoprotein C-III

Cardiovascular disease (CVD) is an evolving process that begins in the early stages of chronic kidney disease (CKD) in children. Several surrogate markers, such as ambulatory blood pressure monitoring (ABPM), left ventricular (LV) mass, and arterial stiffness assessment, allow for the early detection of subclinical CVD in pediatric CKD. Four groups of plasma samples (n = 3/group) from congenital anomalies of the kidney and urinary tract (CAKUT), as well as non-CAKUT patients with or without BP abnormalities, were studied to screen differentially expressed proteins using isobaric tags for relative and absolute protein quantification (iTRAQ)-based proteomics. As a result, 20 differentially expressed proteins associated with hypertension in children with CKD were discovered. Among them, apolipoprotein C-II (apoC-II) was found to have the highest abundance among the CKD patients with hypertension. As such, we hypothesized that apoC-II and apolipoprotein C-III (apoC-III) levels were related to BP abnormalities and CVD in children suffering from mild-to-moderate CKD. We examined their associations with surrogate markers of CV risk in 88 pediatric patients with CKD stages G1-G4. Children with CKD stages G2-G4 had a higher plasma apoC-II level than G1 patients (6.35 vs. 5.05 mg/dl, p < 0.05). We observed that ABPM abnormalities, LV mass, and arterial stiffness parameters were greater in CKD children who had stages G2-G4 than in those who had stage G1 (all p < 0.05). Plasma levels of apoC-II and apoC-III were positively correlated with total cholesterol, triglyceride, and low-density lipoprotein (LDL) (all p < 0.001). In multivariate linear regression analyses, apoC-II was correlated with a high LV mass index and an abnormal ABPM profile, and apoC-III was correlated with 24-h hypertension (r = 0.303, p = 0.003) and asleep hypertension (r = 0.379, p < 0.001). Early evaluations of apoC-II and apoC-III, ABPM, and surrogate markers of CV risk will aid in early preventative interventions to reduce the risk of CV in youths suffering from CKD.

Cardiovascular Risk in Children: Focus on Pathophysiological Aspects

Cardiovascular diseases are the leading cause of death, disability, and health care costs in industrialized countries. In general, cardiovascular diseases occur in adulthood, but cardiovascular damage, including stiffening of the arteries, begins very early. Already in the first decade of life, alterations that will favor the formation of atherosclerotic plaques may be present. Cardiovascular risk factors, associated with genetic predisposition, may trigger a sequence of pathophysiological changes which are associated with the progression of the atherosclerosis process. In this frame, the role of obesity has been increasingly emphasized. Different mechanisms linking obesity to cardiovascular disease have been postulated. Endothelial dysfunction and subclinical inflammation seem to be related to the worsening of cardiovascular risk factors in obese subjects and might have an essential role in the development of insulin resistance and the initiation and progression of atherosclerotic lesions. Excess weight, and in particular visceral adiposity, are associated with hypertrophy and hyperplasia of the adipocytes, increased secretion of adipokines and inflammatory cytokines and increase in serum uric acid levels. The list of obesity-related biomarkers associated with cardiovascular damage is rapidly expanding and their importance has already been described in children as well. Pathophysiological changes involved in determining early cardiovascular damage starting from childhood are discussed in this Special Issue.

Fluid-electrolyte homeostasis requires histone deacetylase function

Histone deacetylase (HDAC) enzymes regulate transcription through epigenetic modification of chromatin structure, but their specific functions in the kidney remain elusive. We discovered that the human kidney expresses class I HDACs. Kidney medulla-specific inhibition of class I HDACs in the rat during high-salt feeding results in hypertension, polyuria, hypokalemia, and nitric oxide deficiency. Three new inducible murine models were used to determine that HDAC1 and HDAC2 in the kidney epithelium are necessary for maintaining epithelial integrity and maintaining fluid-electrolyte balance during increased dietary sodium intake. Moreover, single-nucleus RNA-sequencing determined that epithelial HDAC1 and HDAC2 are necessary for expression of many sodium or water transporters and channels. In performing a systematic review and meta-analysis of serious adverse events associated with clinical HDAC inhibitor use, we found that HDAC inhibitors increased the odds ratio of experiencing fluid-electrolyte disorders, such as hypokalemia. This study provides insight on the mechanisms of potential serious adverse events with HDAC inhibitors, which may be fatal to critically ill patients. In conclusion, kidney tubular HDACs provide a link between the environment, such as consumption of high-salt diets, and regulation of homeostatic mechanisms to remain in fluid-electrolyte balance.

Association between Acrylamide Metabolites and Cardiovascular Risk in Children With Early Stages of Chronic Kidney Disease

Cardiovascular disease (CVD) begins early in children with chronic kidney disease (CKD). Reduced nitric oxide (NO) bioavailability has been associated with increased CVD in CKD patients. Children tend to have more exposure to acrylamide, one of the most common toxins in food. We aimed to determine whether urinary levels of acrylamide metabolites N-acetyl-S-(2-carbamoylethyl)-cysteine (AAMA) and N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-cysteine (GAMA) are associated with CV risk markers in children with CKD. Data on 112 children and adolescents ages three to 18 years old with CKD stage G1-G4 are reported. We observed that 24 h ambulatory blood pressure monitoring (ABPM) abnormalities were greater, and left ventricular (LV) mass and ambulatory arterial stiffness index (AASI) were higher in children with CKD stage G2-G4 versus G1. Patients with CKD stage G2-G4 had a lower urinary acrylamide level, but a higher AAMA-to-GAMA ratio than those with CKD stage G1. Urinary acrylamide level was negatively associated with high systolic blood pressure (SBP) and diastolic BP (DBP) load on 24 h ABPM. Lower urinary levels of acrylamide, AAMA, and GAMA were correlated with LV mass. Additionally, GAMA are superior to AAMA related to NO-related parameters, namely citrulline and symmetric dimethylarginine (SDMA). This study suggests that determinations of urinary acrylamide level and its metabolites in the early stages of pediatric CKD may identify patients at risk of CVD. Further studies should clarify mechanisms underlying acrylamide exposure to define the treatment for protection against CVD.

Association of Trimethylamine, Trimethylamine N-oxide, and Dimethylamine with Cardiovascular Risk in Children with Chronic Kidney Disease

Chronic kidney disease (CKD) is associated with high risk for cardiovascular disease (CVD). Gut microbiota-dependent metabolites trimethylamine (TMA), trimethylamine N-oxide (TMAO), and dimethylamine (DMA) have been linked to CKD and CVD. We examined whether these methylamines are correlated with cardiovascular risk in CKD children. A total of 115 children and adolescents with CKD stage G1-G4 were enrolled in this cross-sectional study. Children with CKD stage G2-G4 had higher plasma levels of DMA, TMA, and TMAO, but lower urinary levels of DMA and TMAO than those with CKD stage G1. Up to 53% of CKD children and adolescents had blood pressure (BP) abnormalities on 24-h ambulatory BP monitoring (ABPM). Plasma TMA and DMA levels inversely associated with high BP load as well as estimated glomerular filtration rate (eGFR). Additionally, CKD children with an abnormal ABPM profile had decreased abundance of phylum Cyanobacteria, genera Subdoligranulum, Faecalibacterium, Ruminococcus, and Akkermansia. TMA and DMA are superior to TMAO when related to high BP load and other CV risk factors in children and adolescents with early-stage CKD. Our findings highlight that gut microbiota-dependent methylamines are related to BP abnormalities and CV risk in pediatric CKD. Further studies should determine whether these microbial markers can identify children at risk for CKD progression.