Are there any new reliable markers to detect renal injury in obese children?

Body mass index and implications for pediatric kidney health: a cross-sectional study with urinary biomarkers

BACKGROUND

Extremes of unhealthy body weight, particularly obesity, are known to increase the risk of chronic kidney diseases. However, the current knowledge of kidney health outcomes associated with unhealthy body weight remains incomprehensive, especially in pediatrics. Therefore, the present study aimed to evaluate body mass index (BMI) and its potential associations with kidney health in a selected subset of school students in Sri Lanka.

METHODS

This cross-sectional study was conducted among students of both sexes in the range of 11-18 years of age (N = 1078) in education zones with no reported cases of chronic kidney disease of uncertain etiology. Based on sex- and age-specific BMI percentiles (LMS method), the participants were classified into five BMI groups (severely thin, thin, healthy, overweight, and obese) for measurement of urinary biomarkers of kidney injury: kidney injury molecule (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and albumin creatinine ratio (ACR).

RESULTS

The median urinary levels of NGAL, ACR, and particularly KIM-1, which is a more sensitive indicator of kidney injury, showed no significant differences across the BMI strata. Importantly, moderate correlations of BMI with KIM-1 and NGAL were identified in severely thin girls.

CONCLUSIONS

According to the present study, these findings do not produce plausibly strong evidence to establish a potential association of BMI with altered kidney function in the studied pediatric communities. Particularly, a likelihood of abnormal kidney health outcomes associated with undernutrition is apparent in severely thin girls. However, in-depth studies are warranted to develop a comprehensive understanding of the associations of nutritional status with pediatric kidney health in Sri Lanka. A higher resolution version of the Graphical abstract is available as Supplementary information.

Lipid metabolism and renal function markers in obese adolescents

AIM OF THE STUDY

To investigate the relationship of renal function markers and lipid metabolism parameters in obese adolescents.

MATERIAL AND METHODS

The study comprised 76 children aged 11-17 years, hospitalised due to: obesity (group I - 19 children) or obesity accompanied by obesity-induced hypertension (group II - 30 children) or normosthenic children with a diagnosed tension headaches (control group - 27 children). A subgroup with metabolic syndrome (MS - 16 children) was also separated. Renal function was assessed on the basis of: serum creatinine concentration, glomerular filtration rate estimated using Schwartz eqation (eGFR), determination of plasma and urinary neutrophil gelatinase-associated lipocalin and cystatin C. On the basis of statistical analysis, it was checked whether renal function markers depend on lipid metabolism parameters.

RESULTS

In the study groups mean creatinine concentrations were significantly higher and eGFR values significantly lower than in the control group, but they remained within norm. Differences in plasma and urinary neutrophil gelatinase-associated lipocalin concentrations were not significant. Mean cystatin C concentrations were significantly higher in the group of obese children. Multiple linear regression analysis showed that the most important predictor was: LDL-C for urinary neutrophil gelatinase-associated lipocalin (R2 = 0.42) and TG for eGFR (R2 = 0.44) concentrations in group I; cholesterol for creatinine concentrations in MS group (R2 = 0.44).

CONCLUSIONS

Renal function of the obese adolescents included in the study was normal and the associations with lipid metabolism were poorly expressed.

The Effect of a Comprehensive Life-Style Intervention Program of Diet and Exercise on Four Bone-Derived Proteins, FGF-23, Osteopontin, NGAL and Sclerostin, in Overweight or Obese Children and Adolescents

The adipose and bone tissues demonstrate considerable interconnected endocrine function. In the present study, we determined the concentrations of fibroblast growth factor-23 (FGF-23), osteopontin, neutrophil gelatinase-associated lipocalin (NGAL) and sclerostin in 345 children and adolescents who were overweight or obese (mean age ± SD mean: 10.36 ± 0.16 years; 172 males, 173 females; 181 prepubertal; and 164 pubertal) before and after their participation in a comprehensive life-style intervention program of diet and exercise for one year. Following the one-year life-style interventions, there was a significant decrease in BMI (p < 0.01), FGF-23 (p < 0.05), osteopontin (p < 0.01) and NGAL (p < 0.01), and an increase in sclerostin (p < 0.01) concentrations. BMI z-score (b = 0.242, p < 0.05) and fat mass (b = 0.431, p < 0.05) were the best positive predictors and waist-to-height ratio (WHtR) (b = −0.344, p < 0.05) was the best negative predictor of the change of osteopontin. NGAL concentrations correlated positively with HbA1C (b = 0.326, p < 0.05), WHtR (b = 0.439, p < 0.05) and HOMA-IR (b = 0.401, p < 0.05), while BMI (b = 0.264, p < 0.05), fat mass (b = 1.207, p < 0.05), HDL (b = 0.359, p < 0.05) and waist circumference (b = 0.263, p < 0.05) were the best positive predictors of NGAL. These results indicate that FGF-23, osteopontin, NGAL and sclerostin are associated with being overweight or obese and are altered in relation to alterations in BMI. They also indicate a crosstalk between adipose tissue and bone tissue and may play a role as potential biomarkers of glucose metabolism. Further studies are required to delineate the physiological mechanisms underlying this association in children and adolescents.

Obesity-related glomerulopathy: Current approaches and future perspectives

Obesity-related glomerulopathy (ORG) is a silent comorbidity which is increasing in incidence as the obesity epidemic escalates. ORG is associated with serious health consequences including chronic kidney disease, end-stage renal disease (ESRD), and increased mortality. Although the pathogenic mechanisms involved in the development of ORG are not fully understood, glomerular hemodynamic changes, renin-angiotensin-aldosterone system (RAAS) overactivation, insulin-resistance, inflammation and ectopic lipid accumulation seem to play a major role. Despite albuminuria being commonly used for the non-invasive evaluation of ORG, promising biomarkers of early kidney injury that are emerging, as well as new approaches with proteomics and metabolomics, might permit an earlier diagnosis of this disease. In addition, the assessment of ectopic kidney fat by renal imaging could be a useful tool to detect and evaluate the progression of ORG. Weight loss interventions appear to be effective in ORG, although large-scale trials are needed. RAAS blockade has a renoprotective effect in patients with ORG, but even so, a significant proportion of patients with ORG will eventually progress to ESRD despite therapeutic efforts. It is noteworthy that certain antidiabetic agents such as sodium-glucose cotransporter 2 inhibitors (SGLT2i) or glucagon-like peptide-1 receptor agonists (GLP-1 RAs) could be useful in the treatment of ORG through different pleiotropic effects. In this article, we review current approaches and future perspectives in the care and treatment of ORG.

High Glycated Hemoglobin Instead of High Body Mass Index Might Increase the Urine N-Acetyl-β-D-glucosaminidase Con-Centration in Children and Adolescents with Diabetes Mellitus

Children with diabetes, and particularly those with obesity, have poor glycemic control. They are thus at higher risk of early microvascular complications. Renal tubulointerstitial markers are integral to evaluating diabetic nephropathy. Various biomarkers have been proposed, but their role in the obese pediatric population is uncertain. We investigated renal injury markers in children with diabetes, according to obesity, and determined their role as early predictors of diabetic nephropathy. Fifty-three children and adolescents, diagnosed with either type 1 or 2 diabetes mellitus, and 43 control children, aged 7-18 years, were included. Clinical and laboratory characteristics, including six renal injury markers, were compared among subjects according to body mass index and presence of diabetes mellitus. Urine neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, and N-acetyl-β-D-glucosaminidase (NAG) showed significant difference between controls and diabetic children, whereas urine NAG was the only biomarker that was significantly lower either in non-obese or obese controls as compared to diabetic children. Urine NGAL, KIM-1, and NAG showed significant correlations with both HbA1c and urine ACR, whereas only urine NAG was significantly correlated with HbA1c even when groups were subdivided based on the presence of either obesity or diabetes. After adjusting for age, sex, body mass index, duration of known diabetes, and urine albumin-to-creatinine ratio, HbA1c remained a significant risk factor for elevated urine NAG. Urine NAG could be a useful indicator of tubulointerstitial damage in children with diabetes in the pre-albuminuric state. Tighter glycemic control appears to be crucial for avoiding early progression to diabetic nephropathy.

Creatinine-based GFR-estimating equations in children with overweight and obesity

BACKGROUND

With the increasing prevalence of childhood obesity and related development of chronic kidney disease (CKD), there is a critical need to understand how best to assess kidney function in children with obesity. Since serum creatinine (SCr) is recommended as marker of first choice for GFR estimation, we evaluated and compared creatinine-based GFR equations in children with overweight and obesity.

METHODS

Six hundred children with overweight and obesity (53.5% female; mean age 12.20 ± 3.28 years; mean BMI z-score 3.31 ± 0.75) were included from the Centre for Overweight Adolescent and Children's Healthcare (COACH).

RESULTS

Serum creatinine (SCr), normalized using Q-age polynomials obtained from reference values, results in median and mean SCr/Q value close to "1" for all age groups, and 96.5% of the children have a SCr/Q within the reference band [0.67-1.33], corresponding to the 2.5th and 97.5th percentile. eGFR CKiD (bedside Schwartz equation) and Schwartz-Lyon decreased with age, whereas eGFR EKFC and modified CKD-EPI40 showed no age-dependency, but the distribution of eGFR values was not symmetrical. eGFR CKiD under 25 (CKiDU25) demonstrated no age-dependency but major sex differences were observed. eGFR FAS age, FAS height, and adjusted-creatinine revised Lund-Malmö (LMR18) showed a relatively symmetrical distribution and no age-dependency.

CONCLUSIONS

Serum creatinine (SCr) values of children with overweight and obesity are mostly within the reference range for children. Normalization of SCr using reference Q-age polynomials works very well in this cohort. After evaluation of the different equations, we suggest that FAS age, FAS height, and LMR18 are the preferred creatinine-based GFR-estimating equations in children with overweight and obesity.

CLINICALTRIAL

gov; Registration Number: NCT02091544. A higher resolution version of the Graphical abstract is available as Supplementary information.

Urinary NGAL is a Potential Biomarker for Early Renal Injury in Insulin Resistant Obese Non-diabetic Children

OBJECTIVE

Neutrophil gelatinase-associated lipocalin (NGAL) is one of the new biomarkers for detecting acute renal injury. There are studies showing the relationship between NGAL and renal injury in obese children. The aim of this study was to investigate whether urinary levels of NGAL, kidney injury molecule-1, and serum cystatin C are increased in insulin resistance (IR) patients before the development of diabetes.

METHODS

Cross-sectional, case-controlled study that included non-diabetic obese children and adolescent patients with IR and a non-diabetic obese control group with no IR, who attended a tertiary center pediatric endocrinology outpatient clinic between 2016-2018. Those with diabetes mellitus and/or known renal disease were excluded. NGAL and creatinine (Cr) levels were evaluated in the morning spot urine from all participants. Serum renal function was evaluated.

RESULTS

Thirty-six control and 63 IR patients were included in the study, of whom 68 (68.7%) were girls. The mean age of all participants was 13.12±2.64 years and no statistically significant difference was found between the two groups in terms of age or gender distribution. Median (range) spot urinary NGAL (u-NGAL) values in the IR group were significantly higher at 26.35 (7.01-108.7) ng/mL than in the control group at 19.5 (3.45-88.14) ng/mL (p=0.018). NGAL/Cr ratio was also significantly higher in the IR group compared to the control group (p=0.018).

CONCLUSION

Obese pediatric patients with IR were shown to have elevated levels of u-NGAL, a marker of renal injury. u-NGAL examination may show early renal injury before development of diabetes.

Assessment of urinary podocalyxin as a marker of glomerular injury in obesity-related kidney disease in children and adolescents with obesity compared to urinary albumin creatinine ratio

Obesity increases the risk of chronic kidney disease in children. Our aim was to assess urinary podocalyxin (PCX) in children and adolescents with obesity as a potential marker of obesity-related kidney disease (ORKD). The current case-control study included 128 children with obesity compared to 60 non-obese age and sex matched controls. Study population were subjected to full history taking as well as thorough physical examination. Urine samples for albumin creatinine ratio (uACR) and PCX were collected from the study population as well as blood samples for assessment of serum creatinine and fasting lipid profile. A statistically significant difference was found between cases and controls regarding urinary PCX (P < .001) and uACR (P = .021). A statistically significant positive correlation was found between uACR and weight SD score (SDS), body mass index SDS, waist circumference, estimated glomerular filtration rate, triglycerides (TG) as well as urinary PCX, whilst urinary PCX correlated significantly with obesity duration and uACR. Cases with microalbuminuria had a statistically significant higher waist circumference, waist-hip ratio, fat percentage, TG and urinary PCX compared to those with normal uACR (P = .042, .034, .05, .018 and .036 respectively). Urinary PCX showed 83.3% sensitivity and 74% specificity in detection of albuminuria. Urinary PCX was increased significantly in children with obesity making it a potential sensitive marker of ORKD in children.

Anthocyanin-rich fraction from black rice, Oryza sativa L. var. indica "Luem Pua," bran extract attenuates kidney injury induced by high-fat diet involving oxidative stress and apoptosis in obese rats

Obesity is acknowledged as being a world health problem and increases the risk of several chronic diseases including chronic kidney disease. High-fat diet consumption and obesity-related renal disease show a close correlation with increased oxidative stress. Black rice bran extract, (BRE) Oryza sativa L. variety "Luem Pua" contains a high anthocyanin content. This study evaluated the effects of an anthocyanin-rich fraction from BRE on renal function and oxidative stress in obese rats. Male Wistar rats were fed a normal diet (ND) or high-fat diet (HF) for 16 weeks. After this, the rats were given either vehicle (HF), BRE 100 (HF100) or BRE 200 mg/kg/day (HF200) orally for 8 weeks. The HF rats had increased body weight, visceral fat weight, plasma glucose, cholesterol and triglycerides. These parameters were normalized following HF100 administration and showed a decreasing trend with HF200. Serum creatinine and renal cortical MDA were increased in the HF group but these effects were attenuated by BRE. Negative kidney injury and histopathology changes were observed following a HF, but treatment with BRE reversed these deleterious effects. These results suggest that BRE could be used as a food supplement to improve metabolic disturbance and prevent kidney dysfunction in cases of obesity.

Development of a multiplex mass spectrometry method for simultaneous quantification of urinary proteins related to respiratory health

Respiratory health of children is a health priority. Club cell protein (CC16) is an interesting biomarker of lung diseases and adverse effects towards the airway epithelium integrity. Osteopontin (OPN) and nuclear factor-kappa B (NF-κB) also play a role in respiratory health. The use of urine as biomarker source is useful in studies involving children but necessitates proper adjustment for physiological confounders influencing the urinary excretion, potentially characterized with beta-2-microglobulin (β2M), retinol binding protein 4 (RBP4) or myoglobin (MYO), as well as adjustment for possible renal dysfunction, characterized by human serum albumin (HSA). The simultaneous quantification of all these proteins in urine could facilitate children's health monitoring. A multiple reaction monitoring method (MRM) was developed and validated for the relative quantification of the seven mentioned urinary proteins. A total of nine proteotypic peptides were selected and used for the relative quantification of the seven proteins. The MRM method was completely validated for all proteins and partially for OPN. LOQ's ranged from 0.3 to 42.8 ng/ml, a good reproducibility and a good linearity were obtained across the analytical measurement range (r² > 0.98). The method yielded varying correlations (r² of 0.78, 0.71, 0.34 and 0.15 for CC16, β2M, RBP4 and HSA respectively) with available immunoassay data. It also allowed the identification and successful quantification of β2M and RBP4 as a protein candidate for adjustment of renal handling and dysfunction. All proteins were detected in the urine samples except for MYO and NF-κB. Our validated MRM-method is able to simultaneously quantify in urine biomarkers of airway epithelium integrity and biomarkers of variation in renal function and urinary dilution. This will allow to investigate further in future studies if urine can be used as a good surrogate source for biomarkers of airway epithelium integrity, and to understand the complex relationship between cause and effect in children's respiratory health monitoring.

Urine NGAL and KIM-1: tubular injury markers in acute lymphoblastic leukemia survivors

Introduction

Nephrotoxicity is a potential adverse effect of anticancer treatment in childhood. Cytostatics, abdominal radiotherapy, total body irradiation (TBI) and some agents used in supportive care may induce acute kidney injury (AKI) or lead to chronic kidney disease (CKD). The aim of this study was to test the hypothesis whether urinary kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) are increased in acute lymphoblastic leukemia (ALL) survivors.

Method

The study cohort consisted of 86 patients (42 females) previously treated for ALL. The median time after cessation of treatment was 6.55 (IQR: 1.96–9.93) years and median age at the time of study: 12 (IQR: 6.76–16.00). The control group included 53 healthy peers. Immunoenzymatic ELISA commercial kits were used to measure urine KIM-1 and NGAL levels.

Results

The median levels of urine uNGAL (p < 0.05), uNGAL/creatinine (cr.) ratio (p < 0.0001) and uKIM-1/creatinine ratio (p < 0.0001) were significantly higher in ALL survivors in comparison with healthy controls. Female patients had significantly higher levels of NGAL and NGAL/cr. than males (mean 8.42 ± 7.1 vs. 4.59 ± 4.5 ng/mL and 86.57 ± 77 vs. 37.7 ± 37 ng/mg, respectively; p < 0.01). Of all the study participants, 11 (13%) presented eGFR below 90 mL/min/1.73 m². The NGAL/cr. ratio seemed to be the best predictor of decreased eGFR (AUC = 0.65). The cumulative dose of methotrexate and cyclophosphamide did not predict the values of the urine NGAL, NGAL/cr., KIM-1/cr. and eGFR.

Five years after the end of treatment, the patients had higher levels of uKIM-1 (1.02 ± 0.8 vs. 0.62 ± 0.6 ng/mL, p < 0.01), uNGAL (7.9 ± 6.7 vs. 4.6 ± 5 ng/mL, p < 0.01) and lower eGFR (114 ± 29 vs. 134 ± 35 mL/min/1.73 m², p < 0.01) in comparison with ALL survivors with the observation period of less than 5 years.

Conclusion

We demonstrated that ALL survivors have higher levels of urine NGAL, NGAL/cr. and uKIM-1/cr. ratio as compared to the control group. Further long-term follow-up studies are necessary to assess the significance of the NGAL and KIM-1 and their relationship to kidney damage after anticancer treatment in childhood.

Cross-shift change of acute kidney injury biomarkers in sugarcane farmers and cutters

Sugarcane farmers and cutters have been reported to be at high risk of acute kidney injury. This cross-sectional study aimed to assess acute kidney injury biomarkers, and cross-shift change among 150 sugarcane cutters and 98 sugarcane farmers in Thailand. Physical health examination, environmental measurements, and measured urinary neutrophil gelatinase-associated lipocalin (NGAL) were assessed. Cross-shift change of urine creatinine (uCr), albumin creatinine ratio (ACR), and NGAL between sugarcane farmers and cutters was compared. Factors influencing abnormal post-shift ACR and NGAL were analyzed by binary logistic regression adjusted with covariates. Sugarcane cutters were significantly more likely to take nonsteroidal anti-inflammatory drugs (NSAID) and herbs to relieve pain than sugarcane farmers. Males were more likely to be current smokers and drinkers although 62% of cutters and 56% of farmers were female. Sugarcane farmers and cutters had similar post-shift estimated glomerular filtration rate (eGFR) and ACR levels. Cross-shift measurements showed that both sugarcane cutters and sugarcane farmers had significantly higher post-shift geometric mean (GM) urinary NGAL, but that the cross-shift changes of NGAL were significantly higher for sugarcane cutters (182%) vs. sugarcane farmers (112%). Water intake less than recommendation of subjects was a significant predictor of a higher risk for an abnormal post-shift ACR after controlling for covariates, while being a sugarcane cutter was a predictor of a lower risk of an abnormal risk of a post-shift NGAL after controlling for covariates. Measurements of heat stress (WBGT plus workload) found that sugarcane cutters exceeded recommended exposures while sugarcane farmers were compliance to the TLV. These findings suggest that to protect sugarcane farmers and cutters, preventative measures are needed.

Osteopontin: The Molecular Bridge between Fat and Cardiac-Renal Disorders

Osteopontin (OPN) is a multifaceted matricellular protein, with well-recognized roles in both the physiological and pathological processes in the body. OPN is expressed in the main organs and cell types, in which it induces different biological actions. During physiological conditioning, OPN acts as both an intracellular protein and soluble excreted cytokine, regulating tissue remodeling and immune-infiltrate in adipose tissue the heart and the kidney. In contrast, the increased expression of OPN has been correlated with the severity of the cardiovascular and renal outcomes associated with obesity. Indeed, OPN expression is at the “cross roads” of visceral fat extension, cardiovascular diseases (CVDs) and renal disorders, in which OPN orchestrates the molecular interactions, leading to chronic low-grade inflammation. The common factor associated with OPN overexpression in adipose, cardiac and renal tissues seems attributable to the concomitant increase in visceral fat size and the increase in infiltrated OPN⁺ macrophages. This review underlines the current knowledge on the molecular interactions between obesity and the cardiac–renal disorders ruled by OPN.

SHORT TERM EFFECT OF LAPAROSCOPIC SLEEVE GASTRECTOMY ON CLINICAL, RENAL PARAMETERS AND URINARY NGAL LEVELS IN DIABETIC AND NON DIABETIC OBESITY

Background

Although diseases such as diabetes, hypertension, obstructive sleep apnea and hyperlipidemia are clearly documented as obesity associated diseases, it is not well-known whether obesity causes renal pathologies. The aim of the present study was to evaluate the effect of weight loss following laparoscopic sleeve gastrectomy on clinical, renal parameters and urinary Neutrophil gelatinase-associated lipocalin (NGAL) levels in diabetic and non-diabetic obese patients.

Methods

Nineteen morbidly obese patients (10 diabetic and 9 non diabetic) who underwent laparoscopic sleeve gastrectomy were evaluated clinically (anthropometric measurements) and biochemically before surgery and at 6 months from surgery.

Results

Significant decreases in weight, BMI, FPG, PPG and HbA1c levels were observed in the diabetic group when the baseline and 6th month parameters of the patients were compared. There was also a significant decrease in SBP and DBP. At 6^th month following laparoscopic sleeve gastrectomy, renal parameters such as creatinine, mAlb/creatinine, NGAL/creatinine did not differ in the diabetic group. In the nondiabetic group, serum creatinine levels were significantly decreased, but other renal parameters such as mAlb/creatinine and NGAL/creatinine were not significantly different.

Conclusions

Our findings revealed significant decreases in weight, body mass index and glycemic parameters after sleeve gastrectomy in diabetic and non-diabetic patients, while no significant alteration was noted in renal functions, urinary NGAL and microalbumin levels.

Corticosteroids significantly increase cystatin C levels in the plasma by promoting cystatin C production in rats

Background: Several studies have shown that non-renal factors such as corticosteroids may increase plasma cystatin C levels without affecting kidney function. However, the mechanisms underlying this are unclear. We hypothesized that corticosteroids may increase cystatin C levels in the plasma by promoting its production in tissues. In the present study, we aimed to test our hypothesis in rats by investigating the effect of corticosteroids on cystatin C production in tissues and the glomerular filtration rate (GFR), as measured by the gold standard method (i.e., inulin clearance). Results: Dexamethasone treatment was associated with much higher concentrations of cystatin C in all organ tissue homogenates tested. Dexamethasone increased plasma cystatin C levels in rats, without any decrease in renal inulin clearance. The impact of dexamethasone on plasma and organ tissue cystatin C levels was abolished by RU486, indicating the effect was glucocorticoid receptor-mediated. Conclusions: Our study provides direct evidence that corticosteroids may increase cystatin C levels in the plasma by promoting its production, without any decrease in GFR.