Hyperinsulinemia in pediatric patients with chronic kidney disease: the role of tumor necrosis factor-alpha

Exploring systemic inflammation in children with chronic kidney disease: correlates of interleukin 6

BACKGROUND

Systemic inflammation (SI) is linked to chronic kidney disease (CKD) progression and multiple complications. Data regarding SI biomarkers in pediatric patients are scarce. This case-control and cross-sectional study investigates the correlation of neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), total iron binding capacity (TIBC) and serum albumin to serum interleukin-6 (IL-6).

METHODS

NLR and PLR were measured in 53 patients (median age: 12.9 years), including 17 on dialysis and 36 with a median glomerular filtration rate of 39 ml/min/1.73m2, and in 25 age and sex-matched healthy controls. Iron profile, serum albumin and IL-6 were measured in the patient group. IL-6 levels > 3rd quartile were classified as high.

RESULTS

Patients presented higher NLR and PLR and particularly those on dialysis (p < 0.001 and p = 0.001). We observed a significant correlation between natural logarithm (ln) of IL-6 (lnIL-6) and NLR (rs = 0.344, p = 0.014), serum albumin (rs = -0.350, p = 0.011) and TIBC (rs = -0.345, p = 0.012) after adjustment for CKD stage, while the correlation between lnIL-6 and PLR was not significant (rs = 0.206, p = 0.151). Combination of NLR, serum albumin and TIBC predicted high IL-6 (13 patients) with an AUC of 0.771 (95% CI 0.608-0.943). Pairing of NLR ≥ 1.7 and TIBC ≤ 300 μg/dL exhibited the highest sensitivity (76.9%), while incorporating serum albumin ≤ 3.8 g/dL along with them achieved the highest specificity (95%) for detecting high IL-6 levels.

CONCLUSION

Both NLR and PLR levels increase in CKD, especially in patients on chronic dialysis. NLR, rather than PLR, along with TIBC and serum albumin, are associated with IL-6 in pediatric CKD.

Association between relative fat mass, uric acid, and insulin resistance in children with chronic kidney disease

INTRODUCTION

This cross-sectional study investigates the association between insulin resistance (IR) and serum uric acid (sUA) and relative fat (RFM) and lean mass (RLM) profiles in children with chronic kidney disease (CKD).

MATERIAL AND METHODS

RLM and RFM were assessed by bioimpedance spectroscopy in 41 children and adolescents. Normal weight obesity (NWO) was defined as normal height-age body mass index and RFM >85th percentile, according to age and sex. Homeostatic model assessment of insulin resistance (HOMA-IR) level >95th percentile, according to sex and pubertal stage, and sUA >7 mg/dl were used to define IR and hyperuricemia, respectively.

RESULTS

High RFM (15 patients) and NWO (7 patients) were associated with higher HOMA-IR in total (p < 0.001) and normal-weight patients (p = 0.004), respectively. RFM was positively and RLM negatively correlated to HOMA-IR (rs = 0.500, p = 0.001 and rs = -0.539, p < 0.001, respectively) and sUA (rs = 0.370, p = 0.017 and rs = -0.325, p = 0.038, respectively), while sUA was positively correlated to HOMA-IR (rs = 0.337, p = 0.031). Hyperuricemia (16 patients) was positively associated with higher RFM and HOMA-IR (p = 0.001 and p = 0.010, respectively). The correlation between sUA and HOMA-IR lost significance after adjustment for RFM. In logistic regression analysis, a 5% increase in RFM was associated with IR (11 patients) independently of the age, sex, sUA, and CKD stage in both total (OR 2.174, 95% CI 1.115-4.225) and normal-weight (OR 3.504, 95% CI 1.110-11.123) patients.

CONCLUSION

Children with high RFM, including those presenting NWO, are at risk for IR regardless of CKD stage. RFM is probably the mediator of the link between sUA and IR.

Cardiovascular risks in chronic kidney disease pediatric patients

One of the common factors for the premature death in children is advanced chronic kidney disease (CKD). Most often cardiovascular disease (CVD) is the reason for mortality. The cardiovascular (CV) morbidity starts early in the disease process and renal transplanted children (CKD-T) are also at risk. The present review is focused on the current views of the cardiovascular risks during CKD in pediatric patients. Variable data sources for the latest literature collection were explored which mainly included PubMed and Google Scholar. The most important risk factors for subclinical CVD were a young age, elevated BMI and systolic blood pressure z-scores as well as a low GFR and present albuminuria. Increasing blood pressure and BMI over follow-up were also important cardiac risk factors longitudinally. The present review concludes that altered cardiac function and remodeling are a concurrent part of the CKD process, start early in the disease development, and persist after renal transplantation. The findings suggest that children with CKD or CKD-T are at high risk for future CVD where younger patients with elevated BMI and slightly increased blood pressures, as well as present albuminuria, are those at greatest risk, thus indicating targets for future interventions.

The systemic nature of CKD

The accurate definition and staging of chronic kidney disease (CKD) is one of the major achievements of modern nephrology. Intensive research is now being undertaken to unravel the risk factors and pathophysiologic underpinnings of this disease. In particular, the relationships between the kidney and other organs have been comprehensively investigated in experimental and clinical studies in the last two decades. Owing to technological and analytical limitations, these links have been studied with a reductionist approach focusing on two organs at a time, such as the heart and the kidney or the bone and the kidney. Here, we discuss studies that highlight the complex and systemic nature of CKD. Energy balance, innate immunity and neuroendocrine signalling are highly integrated biological phenomena. The diseased kidney disrupts such integration and generates a high-risk phenotype with a clinical profile encompassing inflammation, protein-energy wasting, altered function of the autonomic and central nervous systems and cardiopulmonary, vascular and bone diseases. A systems biology approach to CKD using omics techniques will hopefully enable in-depth study of the pathophysiology of this systemic disease, and has the potential to unravel critical pathways that can be targeted for CKD prevention and therapy.

Green Tea Polyphenol Epigallocatechin-3-gallate Suppresses Toll-like Receptor 4 Expression via Up-regulation of E3 Ubiquitin-protein Ligase RNF216

Toll-like receptor 4 (TLR4) plays an essential role in innate immunity through inflammatory cytokine induction. Recent studies demonstrated that the abnormal activation of TLR4 has a pivotal role in obesity-induced inflammation, which is associated with several diseases, including hyperinsulinemia, hypertriglyceridemia, and cardiovascular disease. Here we demonstrate that (-)-epigallocatechin-3-O-gallate, a natural agonist of the 67-kDa laminin receptor (67LR), suppressed TLR4 expression through E3 ubiquitin-protein ring finger protein 216 (RNF216) up-regulation. Our data indicate cyclic GMP mediates 67LR agonist-dependent RNF216 up-regulation. Moreover, we show that the highly absorbent 67LR agonist (-)-epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG3″Me) significantly attenuated TLR4 expression in the adipose tissue. EGCG3″Me completely inhibited the high-fat/high-sucrose (HF/HS)-induced up-regulation of tumor necrosis factor α in adipose tissue and serum monocyte chemoattractant protein-1 increase. Furthermore, this agonist intake prevented HF/HS-induced hyperinsulinemia and hypertriglyceridemia. Taken together, 67LR presents an attractive target for the relief of obesity-induced inflammation.

Fetuin-A and Ghrelin Levels in Children with End Stage Renal Disease and the Effect of a Single Hemodialysis Session on Them

BACKGROUND

Fetuin-A and ghrelin have been implicated in cardiovascular diseases and mortality among end stage renal disease patients. The exact mechanisms have not been fully elucidated. There is robust data supporting an association between ghrelin and various cardiovascular conditions, and some common processes such as inflammation, oxidative stress, and endoplasmic reticulum stress have been implicated.

AIM

This study was conducted to assay serum fetuin-A and ghrelin in chronic renal failure pediatric patients and to study changes in their level that may occur after a single hemodialysis.

MATERIAL AND METHODS

Forty nine pediatric patients suffering from ESRD on maintenance hemodialysis (HD), 20 patients with chronic renal failure (CRF) not on dialysis and 35 healthy subjects as control group were included. The mean age of the study population was 10.58 ± 3.94, 10.62 ± 3.24 and 10.61 ± 3.97 years respectively. Serum fetuin-A and plasma acyl ghrelin levels were measured by using ELISA method.

RESULTS

The present study revealed that predialysis serum fetuin-A level was significantly increased in pediatric HD patients compared with the normal population, while ghrelin levels were significantly reduced. Furthermore, serum levels of fetuin-A decreased significantly after a single HD session.

CONCLUSION

Our study concluded that fetuin-A and acyl ghrelin may play a role in inflammatory process among HD pediatric patients which may account for cardiovascular insults and mortality but their use as biochemical markers among ESRD pediatric patients have limitations due to wide fluctuations.

Left ventricular diastolic dysfunction by tissue Doppler echocardiography in pediatric chronic kidney disease

BACKGROUND

Myocardial dysfunction is common in chronic kidney disease (CKD) and related to poor outcomes. New non-invasive methods to assess cardiac function have been introduced, but comparative studies evaluating their clinical usefulness in pediatric CKD are lacking. We studied left ventricular (LV) function in pediatric CKD and renal transplant patients, comparing conventional pulse-wave Doppler echocardiography (cPWD) with newer tissue Doppler imaging (TDI) and relating the results to known cardiovascular risk factors.

METHODS

The study included 34 children/adolescents with CKD stages 2-5, 44 renal transplant patients and 19 patients with a normal renal function. The mean age was 11.4 (range 0.8-18.8) years.

RESULTS

Both patient groups had significantly lower LV diastolic function than those with a normal renal function. The most sensitive determinants were TDI E'/A' and cPWD E/TDI E' ratios. In a stepwise linear regression analysis, high blood pressure, young age and the presence of albuminuria all independently predicted LV diastolic function.

CONCLUSIONS

Our study confirms the high prevalence of LV diastolic dysfunction in pediatric CKD patients and following renal transplantation, where TDI appears to be more sensitive than cPWD in assessing early myocardial dysfunction. Our results also underline the importance of preventive measures, such as rigorous blood pressure control, in pediatric CKD.

Glucose intolerance: is it a risk factor for cardiovascular disease in children with chronic kidney disease?

A total of 66 children and adolescents with chronic kidney disease (CKD) (20 pre-dialysis patients and 46 chronic dialysis patients) were evaluated to address the prevalence of abnormalities in glucose and insulin metabolism and their association with cardiovascular disease. Glucose intolerance was assessed using an oral glucose tolerance test; insulin resistance was estimated by the homeostasis model assessment of insulin resistance (HOMA-IR). Carotid artery intima-media thickness (IMT) and left ventricular hypertrophy (LVH) were examined as early markers of cardiovascular disease. Thirty-four patients (7 pre-dialysis, 27 dialysis) exhibited an abnormal glucose tolerance; however, ten patients (7 pre-dialysis, 3 dialysis) were insulin-resistant. Height-specific standard deviation scores of carotid artery IMT were above normal in three of the pre-dialysis patients (15%) and in 34 of the dialysis patients (74%). LVH was present in seven pre-dialysis (35%) and 34 dialysis patients (74%). In addition, two of the pre-dialysis patients (10%) and 18 of the dialysis patients (39%) had severe LVH. The prevalence of both increased carotid artery IMT and LVH were similar in patients with or without glucose intolerance in both groups, but severe LVH was more prevalent in pre-dialysis patients with glucose intolerance (p = 0.042). The multivariate analyses showed that neither carotid artery IMT nor LVM index was predicted by serum glucose levels or HOMA-IR. In conclusion, children with CKD are at a high risk of glucose intolerance and also have a greater risk of subclinical cardiovascular disease (CVD). However, the presence of glucose intolerance does not appear to be an independent risk factor for increased carotid artery IMT or LVH.

High prevalence of the metabolic syndrome and associated left ventricular hypertrophy in pediatric renal transplant recipients

The goal of this study was to estimate prevalence of the metabolic syndrome and its association with cardiac abnormalities in children with kidney transplant. A multi-center retrospective review of demographic, clinical, laboratory, and echocardiographic parameters at time of and at one-yr post-transplant was conducted in 234 pediatric recipients between 2000 and 2006. Eighty-eight patients (37.6%) met criteria for metabolic syndrome. Among 55 overweight patients, 40% had metabolic syndrome. Among 51 obese patients, 74.5% had metabolic syndrome. A total of 181 (71.0%) patients had complete data at both time points: prevalence of metabolic syndrome at time of transplant was 18.8%, compared with 37.0% at one-yr post-transplant (p < 0.0001). Among 147 patients without metabolic syndrome at time of transplant, 41 (27.9%) had developed metabolic syndrome by one-yr post-transplant. A total of patients from four centers had routine echocardiogram at one-yr post-transplant. LVH was significantly more common in those with metabolic syndrome (55%) than in those without (32%) (OR 2.6, 95% CI 1.2-5.9).

IN CONCLUSION

metabolic syndrome is common at time of pediatric kidney transplant, and prevalence rises sharply at one-yr post-transplant. The presence of metabolic syndrome is strongly associated with LVH in these patients.

Cytokines, atherogenesis, and hypercatabolism in chronic kidney disease: a dreadful triad

The term cytokine clusters denotes a copious family of molecules and correspondent receptors implicated in numerous processes mediating health and disease. In the context of chronic kidney disease (CKD), generation and metabolism of most of these cytokines are disturbed. Available evidence suggests that cytokine imbalances contribute to the progression of common CKD complications, such as atherosclerosis, mineral-bone disease, and protein-energy wasting via pleiotropic effects. The belief that cytokine CKD research is solely represented by interleukins (IL) and tumor-necrosis factors (TNF) (mainly IL-6 and TNF-alpha) is a common misconception among nephrologists. We here explore recent findings concerning the pathophysiological role of various cytokines in uremic complications, and discuss how cytokines could be used as novel potential therapeutic targets in CKD. At the same time, we provide a brief overview of current discoveries in the main transforming growth factors and chemokines.

Cardiovascular disease in CKD in children: update on risk factors, risk assessment, and management

In young adults with onset of chronic kidney disease in childhood, cardiovascular disease is the most common cause of death. The likely reason for increased cardiovascular disease in these patients is a high prevalence of traditional and uremia-related cardiovascular disease risk factors during childhood chronic kidney disease. Early markers of cardiomyopathy, such as left ventricular hypertrophy and left ventricular dysfunction, and early markers of atherosclerosis, such as increased carotid artery intima-media thickness, carotid arterial wall stiffness, and coronary artery calcification, frequently are found in this patient population. The purpose of this review is to provide an update of recent advances in the understanding and management of cardiovascular disease risks in this population.

Flow-mediated vasodilatation of the brachial artery in children with chronic kidney disease

We sought to determine flow-mediated vasodilatation (FMD) of the brachial artery and to assess the relationship of FMD with multiple demographic, clinical and biochemical parameters and cardiac and vascular structure and function in children with chronic kidney disease (CKD) stages 2-4. Forty-three patients, aged 6-20 years, with CKD [mean glomerular filtration rate (GFR) 47 +/- 21 ml/min per 1.73 m2 body surface area, range 16-89 ml/min per 1.73 m2] and 34 healthy age-matched controls were included and studied cross-sectionally between 2001 and 2005. The peak FMD was similar in the CKD and control subjects (mean 6.3% vs 6.7%, P = 0.85). However, abnormally low FMD (< 1.1%) was found in ten (23%) children with CKD. Among children with CKD, those with low FMD were younger, shorter, lighter, and had lower body mass index (BMI) than children with normal FMD, but the difference reached statistical significance only for weight and BMI. Serum triglyceride levels were significantly lower in those with low FMD; otherwise, the two groups were similar with respect to multiple clinical and biochemical parameters. Cardiac and vascular structure was similar in children with normal and low FMD. In conclusion, children with CKD stage 2-4 appear to have increased prevalence of decreased FMD of the brachial artery. However, our study identified few significant factors associated with low FMD in children with CKD.

Insulin and its role in chronic kidney disease

The body's resistance to the actions of insulin (type II diabetes defect) results in compensatory increased production and secretion by the pancreas and leads to hyperinsulinemia in order to maintain euglycemia. When insulin secretion cannot be increased adequately (type I diabetes defect) to overcome insulin resistance in maintaining glucose homeostasis, hyperglycemia and glucose intolerance ensues. Insulin resistance and glucose intolerance has been well recognized in patients with advanced chronic kidney diseases (CKD). The etiology may involve uremic toxins from protein catabolism, vitamin D deficiency, metabolic acidosis, anemia, poor physical fitness, inflammation, and cachexia. Glucose and insulin abnormalities in nondiabetic CKD patients are implicated in the pathogenesis of hyperlipidemia and may represent important risk factors for accelerated atherosclerosis in these patients. Insulin secretion inadequacy has been associated with growth retardation in adolescents with CKD. Normal adolescents demonstrate an increase in insulin secretion as they go into puberty. It seems that the puberty growth spurt in adolescents both with normal health and renal failure may require increased insulin secretion as one of its hormonal requirements. Finally, insulin resistance has been associated with CKD. Whether insulin resistance is an antecedent of CKD or a consequence of impaired kidney function has been a subject of debate. The goal of this review was to provide an update of the literature on insulin pathophysiology in CKD, current understanding of its mechanisms, and epidemiological association of insulin resistance and CKD.