Association between obesity and kidney disease: a systematic review and meta-analysis

Everolimus Is Associated With Less Weight Gain Than Tacrolimus 2 Years After Liver Transplantation: Results of a Randomized Multicenter Study

Background

Weight gain early after transplant is a risk factor for posttransplant metabolic syndrome (PTMS), cardiovascular events, and renal insufficiency. The impact of mammalian target of rapamycin inhibition on posttransplant weight gain and the development of PTMS components postliver transplantation were examined in a randomized, controlled study.

Methods

After a run-in period, patients (N = 719) were randomized at 30 ± 5 days posttransplant in a 1:1:1 ratio to 3 treatment groups: (i) everolimus (EVR) + reduced tacrolimus (TAC) (n = 245); (ii) TAC control (n = 243) or (iii) TAC elimination (n = 231). In this post hoc analysis, weight change at 12 and 24 months was compared between groups. Vital signs, lipids, and laboratory parameters at 12 and 24 months and rates of PTMS were assessed.

Results

Mean increase in weight from baseline was higher at month 12 in the TAC control arm (8.15 ± 9.27 kg) than in the EVR + reduced TAC (5.88 ± 12.60 kg, P = 0.056) and the TAC elimination arms (4.76 ± 9.94 kg, P = 0.007). At month 24, the TAC control arm displayed a significantly greater weight increase (9.54 ± 10.21 kg) than either the EVR + reduced TAC (6.69 ± 8.37 kg, P = 0.011) or the TAC elimination groups (6.01 ± 9.98 kg, P = 0.024). Rates of PTMS were similar for the EVR + reduced TAC (71.8%), TAC elimination (70.3%) and TAC control (67.4%) arms (P = NS).

Conclusions

EVR with reduced-exposure TAC attenuated weight gain at 1 and 2 years posttransplant compared with a standard TAC immunosuppression regimen. Rates of PTMS were comparable between EVR-containing and TAC control regimens.

In this randomized controlled trial, liver recipients on tacrolimus reduced or eliminated immunosuppressions gain less weight at 1 and 2 years. Whereas, the chances of developing posttransplant metabolic syndrome not affected. The role of everolimus in this regard remains unclear.

Immunologic and endocrine functions of adipose tissue: implications for kidney disease

Excess adiposity can induce adverse sequelae in multiple cell types and organ systems. The transition from the lean to the obese state is characterized by fundamental cellular changes at the level of the adipocyte. These changes affect the local microenvironment within the respective adipose tissue but can also affect nonadipose systems. Adipocytes within fat pads respond to chronic nutrient excess through hyperplasia or hypertrophy, which can differentially affect interorgan crosstalk between various adipose depots and other organs. This crosstalk is dependent on the unique ability of the adipocyte to coordinate metabolic adjustments throughout the body and to integrate responses to maintain metabolic homeostasis. These actions occur through the release of free fatty acids and metabolites during times of energy need - a process that is altered in the obese state. In addition, adipocytes release a wide array of signalling molecules, such as sphingolipids, as well as inflammatory and hormonal factors (adipokines) that are critical for interorgan crosstalk. The interactions of adipose tissue with the kidney - referred to as the adipo-renal axis - are important for normal kidney function as well as the response of the kidney to injury. Here, we discuss the mechanistic basis of this interorgan crosstalk, which clearly has great therapeutic potential given the increasing rates of chronic kidney disease secondary to obesity and type 2 diabetes mellitus.

Effect of Hepatitis C Treatment with Ombitasvir/Paritaprevir/R + Dasabuvir on Renal, Cardiovascular and Metabolic Extrahepatic Manifestations: A Post-Hoc Analysis of Phase 3 Clinical Trials

INTRODUCTION

We analyzed phase 3 trial data of ombitasvir/paritaprevir/ritonavir and dasabuvir (3D) ± ribavirin (RBV) in genotype 1 chronic hepatitis C patients to investigate the impact of 3D ± RBV on renal, cardiovascular and metabolic extrahepatic manifestations (EHMs), including persistency 52 weeks post treatment and differential impact by EHM disease severity.

METHODS

Estimated glomerular filtration rate (eGFR), fasting triglyceride and fasting glucose values from clinical trials were used to assess renal, cardiovascular and metabolic EHMs, respectively. Two placebo-controlled trials were used to study the effect of treatment, while the pooled sample of treated patients was used to study the persistency and differential effect of treatment by baseline EHM disease severity, as defined by baseline values of respective EHM biomarkers. Changes in EHM outcomes from baseline were assessed with mixed models adjusting for patient baseline demographic and clinical characteristics.

RESULTS

Treatment with 3D ± RBV resulted in statistically significant declines from baseline of triglycerides and glucose and no statistical change in eGFR. By 52 weeks post treatment patients with elevated triglycerides (-35.3 mg/dl), pre-diabetes (-4.4 mg/dl), diabetes (-34.2 mg/dl) and CKD stage 3 (+1.6 ml/min/1.73 m2) at baseline experienced a statistically significant improvement in their respective EHM values. Patients with CKD stages 2, 4 and 5 experienced no statistically significant change in eGFR from baseline.

CONCLUSION

Treatment with 3D ± RBV resulted in improvement or no worsening of cardiovascular, metabolic and renal EHM markers, especially in patients with severe EHMs at baseline, which persisted until 52 weeks post treatment.

FUNDING

Abbvie Inc.

[Obesity-related glomerulopathy: Mechanisms of development, clinical course]

Obesity and overweight are recognized as epidemics of non-communicable diseases in the 21st century. The kidneys are a target organ for obesity, damage to which is considered to be an independent risk factor for the development of renal failure. Obesity-related glomerulopathy (OGP) is one of the types of renal injury in obesity, which is characterized by the development of proteinuria in patients with a body mass index (BMI) of >30 kg/m2 in the absence of other causes of kidney damage. The pathogenesis of OGP is multifactorial. It is associated with intrarenal hemodynamic disorders - the development of renal hyperfiltration, the damaging action of adipose tissue hormones (hyperleptinemia, activation of the renin-angiotensin-aldosterone system, decreased production of adiponectin); with ectopic lipid accumulation in the kidney. The morphological pattern of OGP is characterized by a low glomerular density (oligonephronia) that leads to glomerular and tubular hypertrophy; by the development of perihilar focal segmental glomerulosclerosis (FSGS), obvious podocyte damages, and the development of a fatty kidney. The clinical picture of OGP is characterized by the slow and gradual development of albuminuria, not exceeding Stage A3 (300-1999 mg/day). Approximately one-third of patients develop partial nephrotic syndrome with massive proteinuria, but without edema and hypoproteinemia. Complete nephrotic syndrome is observed in not more than 6% of patients with OGP. In the course of the disease, 50% of patients develop hypertension and more than 80% do dyslipidemia. Stages IV-V chronic kidney disease may develop 20-30 years after the disease occurs.

Overweight and Obesity Are Predictors of Progression in Early Autosomal Dominant Polycystic Kidney Disease

The association of overweight/obesity with disease progression in patients with autosomal dominant polycystic kidney disease (ADPKD) remains untested. We hypothesized that overweight/obesity associates with faster progression in early-stage ADPKD. Overall, 441 nondiabetic participants with ADPKD and an eGFR>60 ml/min per 1.73 m² who participated in the Halt Progression of Polycystic Kidney Disease Study A were categorized on the basis of body mass index (BMI; calculated using nonkidney and nonliver weight) as normal weight (18.5-24.9 kg/m²; reference; n=192), overweight (25.0-29.9 kg/m²; n=168), or obese (≥30 kg/m²; n=81). We evaluated the longitudinal (5-year) association of overweight/obesity with change in total kidney volume (TKV) by magnetic resonance imaging using linear regression and multinomial logistic regression models. Among participants, mean±SD age was 37±8 years, annual percent change in TKV was 7.4%±5.1%, and BMI was 26.3±4.9 kg/m² The annual percent change in TKV increased with increasing BMI category (normal weight: 6.1%±4.7%, overweight: 7.9%±4.8%, obese: 9.4%±6.2%; P<0.001). In the fully adjusted model, higher BMI associated with greater annual percent change in TKV (β=0.79; 95% confidence interval [95% CI], 0.18 to 1.39, per 5-unit increase in BMI). Overweight and obesity associated with increased odds of annual percent change in TKV ≥7% compared with <5% (overweight: odds ratio, 2.02; 95% CI, 1.15 to 3.56; obese: odds ratio, 3.76; 95% CI, 1.81 to 7.80). Obesity also independently associated with greater eGFR decline (slope) versus normal weight (fully adjusted β =-0.08; 95% CI, -0.15 to -0.02). In conclusion, overweight and, particularly, obesity are strongly and independently associated with rate of progression in early-stage ADPKD.

Association between obesity and risk of chronic kidney disease: A nationwide Cohort study in Taiwan

BACKGROUND AND AIMS

Increased body fat relates to enhanced inflammatory cytokine production, which, in turn, activates the renin-angiotensin-aldosterone system and increases the risk of chronic kidney disease (CKD). Herein, we aimed to examine the association between obesity and the risk of CKD in a population-representative cohort in Taiwan.

METHODS AND RESULTS

A multistage systematic sampling process was applied in the National Health Interview Survey (NHIS) 2000, 2005, and 2009. Participants were interviewed by a standardized face-to-face questionnaire to obtain information on their demographics, socioeconomic status, lifestyle factors, and body mass index (BMI). The BMI values were classified as follows: underweight (<18.5 kg/m²), normal (18.5-23.9 kg/m²), overweight (24-26.9 kg/m²), and obesity (≥27 kg/m²). The NHIS dataset was linked to National Health Insurance claims data to identify the incidence of CKD. Univariate and multivariate Cox proportional hazard models with competing risks were used to investigate the association between BMI and CKD incidence. We analyzed 45,012 subjects (mean age, 42.03 years; 50.09% males). During 374,254 person-years of follow-up, a total of 1913 new-onset CKD cases were identified. Kaplan-Meier curves comparing the four BMI groups revealed a significant difference (p < 0.01, log-rank test). After controlling for confounding factors, the relative risk of incident CKD was significantly higher in the obese group compared to the normal-weight group (adjusted hazard ratio = 1.32; 95% confidence interval: 1.17-1.49), with a significant linear trend (p < 0.01).

CONCLUSION

Obesity was suggested as an independent risk factor for CKD. Further studies focusing on the effect of losing weight on CKD prevention are warranted.

Obesity, weight change, and chronic kidney disease in patients with type 2 diabetes mellitus: A longitudinal study in Taiwan

BACKGROUND

The aim of the present study was to investigate relationships between the risk of chronic kidney disease (CKD) and obesity and weight changes in Asian patients with type 2 diabetes.

METHODS

At baseline (2003-05), 1187 diabetic patients aged 30-70 years were recruited to the study, with follow-up surveys completed in 2008, 2009, and 2010. Chronic kidney disease was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min per 1.73 m² ; body mass index (BMI) was categorised as normal (18.5-22.9 kg/m² ), overweight (23-27.4 kg/m² ), or obese (≥27.5 kg/m² ); waist circumference (WC) ≥80 cm for women and ≥90 cm for men was taken to indicate abdominal obesity. Changes in weight and WC were calculated from baseline to each follow-up survey. Relative risk (RR) and 95% confidence intervals (CIs) of CKD were estimated. To estimate the risk for incident CKD, associations were examined in patients without CKD at baseline (n = 881).

RESULTS

Over 7 years of follow-up, obesity (RR 1.48; 95% CI 1.08-2.04; P = 0.015) and high WC (RR 1.23; 95% CI 1.00-1.52; P = 0.049) were associated with CKD after adjusting for covariates. Among participants without CKD at baseline, those who gained >10% weight (RR 1.43; 95% CI 1.07-1.90; P = 0.015) and in whom WC increased >15% (RR 1.37; 95% CI 1.01-1.85; P = 0.045) had a higher risk of incident CKD than those who remained stable (±5% changes in weight or WC).

CONCLUSIONS

Diabetic patients who are obese and those with excessive central fat were more likely to have CKD. Large weight gain (>10%) and increases in WC (>15%) independently predicted incident CKD.

Predictors of Perioperative Acute Kidney Injury in Obese Patients Undergoing Laparoscopic Bariatric Surgery: a Single-Centre Retrospective Cohort Study

BACKGROUND

Obesity has been associated with increased risk of perioperative acute kidney injury (AKI). We aim to establish the incidence of AKI among patients undergoing laparoscopic bariatric surgery and identify potential risk factors.

METHODS

Records of 1230 patients who underwent laparoscopic bariatric surgery in a tertiary centre from 1 December 2009 to 31 January 2014 were retrospectively studied. AKI diagnosis was made by comparing the baseline and post-operative serum creatinine to determine the presence of predefined significant change based on the Kidney Disease: Improving Global Outcomes (KDIGO) definition. Univariate analyses were performed to determine significant clinical factors, and multiple logistic regression analysis was subsequently done to determine independent predictors of AKI.

RESULTS

Thirty-five (2.9 %) patients developed AKI during the first 72 h post-surgery. Multivariate logistic regression analysis revealed impaired renal function (OR 10.429, 95 % CI 3.560 to 30.552), use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers (OR 3.038, 95 % CI 1.352 to 6.824), and body mass index (OR 1.048, 95 % CI 1.005 to 1.093) as independent predictors of perioperative acute kidney injury in the obese patients who underwent laparoscopic bariatric surgery.

CONCLUSIONS

We found that the incidence of perioperative AKI among patients who underwent laparoscopic bariatric surgery is at 2.9 %. Impaired renal function, use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers and raised body mass index were found to be independent predictors of AKI. Patients with these risk factors could be considered at risk for developing perioperative AKI, and extra perioperative vigilance should be undertaken.

Silymarin protects against renal injury through normalization of lipid metabolism and mitochondrial biogenesis in high fat-fed mice

Obesity is associated with an increased risk of chronic kidney diseases and the conventional treatment with renin-angiotensin-aldosterone system (RAAS) inhibitors is not enough to prevent renal injury and prolong the progression of disease. Recently, silymarin has shown protective effects on renal tissue injury, but the underlying mechanisms remain elusive. The goal of this study was to investigate the potential capacity of silymarin to prevent renal injury during obesity induced by high fat diet (HFD) in mice. In vivo, male C57BL/6 mice received HFD (60% of total calories) for 12 weeks, randomized and treated orally with vehicle saline or silymarin (30mg/kg body weight/d) for 4 weeks. In vitro, human proximal tubular epithelial cells (HK2) were exposed to 300μM palmitic acid (PA) for 36h followed by silymarin administration at different concentrations. The administration of silymarin significantly ameliorated HFD induced glucose metabolic disorders, oxidative stress and pathological alterations in the kidney. Silymarin significantly mitigated renal lipid accumulation, fatty acid β-oxidation and mitochondrial biogenesis in HFD mice and PA treated HK2 cells. Furthermore, silymarin partly restored mitochondrial membrane potential of HK2 cells after PA exposure. In conclusion, silymarin can improve oxidative stress and preserve mitochondrial dysfunction in the kidney, potentially via preventing accumulation of renal lipids and fatty acid β-oxidation.

Proximal Tubular Cannabinoid-1 Receptor Regulates Obesity-Induced CKD

Obesity-related structural and functional changes in the kidney develop early in the course of obesity and occur independently of hypertension, diabetes, and dyslipidemia. Activating the renal cannabinoid-1 receptor (CB₁R) induces nephropathy, whereas CB₁R blockade improves kidney function. Whether these effects are mediated via a specific cell type within the kidney remains unknown. Here, we show that specific deletion of CB₁R in the renal proximal tubule cells did not protect the mice from obesity, but markedly attenuated the obesity-induced lipid accumulation in the kidney and renal dysfunction, injury, inflammation, and fibrosis. These effects associated with increased activation of liver kinase B1 and the energy sensor AMP-activated protein kinase, as well as enhanced fatty acid β-oxidation. Collectively, these findings indicate that renal proximal tubule cell CB₁R contributes to the pathogenesis of obesity-induced renal lipotoxicity and nephropathy by regulating the liver kinase B1/AMP-activated protein kinase signaling pathway.

Dietary Approaches in the Management of Diabetic Patients with Kidney Disease

Chronic kidney disease (CKD) is one of the most prevalent complications of diabetes, and patients with diabetic kidney disease (DKD) have a substantially higher risk of cardiovascular disease and death compared to their non-diabetic CKD counterparts. In addition to pharmacologic management strategies, nutritional and dietary interventions in DKD are an essential aspect of management with the potential for ameliorating kidney function decline and preventing the development of other end-organ complications. Among DKD patients with non-dialysis dependent CKD, expert panels recommend lower dietary protein intake of 0.8 g/kg of body weight/day, while higher dietary protein intake (>1.2 g/kg of body weight/day) is advised among diabetic end-stage renal disease patients receiving maintenance dialysis to counteract protein catabolism, dialysate amino acid and protein losses, and protein-energy wasting. Carbohydrates from sugars should be limited to less than 10% of energy intake, and it is also suggested that higher polyunsaturated and monounsaturated fat consumption in lieu of saturated fatty acids, trans-fat, and cholesterol are associated with more favorable outcomes. While guidelines recommend dietary sodium restriction to less than 1.5-2.3 g/day, excessively low sodium intake may be associated with hyponatremia as well as impaired glucose metabolism and insulin sensitivity. As patients with advanced DKD progressing to end-stage renal disease may be prone to the "burnt-out diabetes" phenomenon (i.e., spontaneous resolution of hypoglycemia and frequent hypoglycemic episodes), further studies in this population are particularly needed to determine the safety and efficacy of dietary restrictions in this population.

[Gender features of cardiovascular events in patients with chronic glomerulonephritis at the pre-dialysis stage of the disease]

AIM

To identify the gender differences of cardiovascular events in patients with chronic glomerulonephritis (CGN) at the pre-dialysis stage of chronic kidney disease (CKD).

SUBJECTS AND METHODS

A total of 170 patients (median age 40±11 years) with CGN who did not receive hemodialysis were examined. According to gender, all patients were divided into 2 groups: 1) 66 female patients with CGN; 2) 104 male patients with CGN. All the patients underwent general clinical examination and transthoracic echocardiography.

RESULTS

In the male group, body weight (70.2±12.3 vs 61.1±12.6 kg; p=0.000), daily proteinuria [2.286 (1.230-3.541) vs. 1.421 (0.703-2.408) g; p=0.021], aortic diameter (3.43±0.36 vs 3.15±0.32 cm; p=0.000), left atrial size (3.80±0.55 vs 3.52±0.49 cm; p=0.000), indexed left ventricular mass (LVM) (223.5±57.5 vs 205.5±54.6 g/m2, p=0.044) were significantly higher than those in the female group. Changes (atherocalcification) in the aortic valve structures were more common in the men than in the women (48% vs 22.7%; p=0.001), whereas the women were more frequently observed to have reverse blood flow along the right ventricle.

CONCLUSION

In the men with CGN at the pre-dialysis stage of CKD, the increment in LVM index is associated with proteinuria and increases in right ventricle size, frequency of atherosclerotic changes in the aortic valve, and left atrial longitudinal size.

Mast Cell and M1 Macrophage Infiltration and Local Pro-Inflammatory Factors Were Attenuated with Incretin-Based Therapies in Obesity-Related Glomerulopathy

Background: The global increase of obesity parallels the obesity-related glomerulopathy (ORG) epidemic. Dipeptidyl peptidase 4 inhibitors and glucagon-like peptide-1 receptor agonists were well recognized to attenuate renal injury independent of glucose control in diabetic nephropathy. There are limited studies focusing on their effects on ORG. We explored the effects of incretin-based therapies on early ORG and the inflammatory responses involved mainly concentrated on mast cell (MC) and macrophage (M) infiltration and local pro-inflammatory factors.

Methods: ORG rat models were induced by high-fat diet and then divided into ORG vehicle, vildagliptin (3 mg/kg/day, qd) and liraglutide (200 μg/kg, bid) treated groups. After 8 weeks of treatments, albuminuria, glomerular histology, renal inflammatory cell infiltration, and pro-inflammatory factors were analyzed.

Results: Early ORG model was demonstrated by albuminuria, glomerulomegaly, foot process fusion, and mesangial and endothelial mild proliferation. Incretin-based therapies limited body weight gain and improved insulin sensitivity. ORG was alleviated, manifested by decreased average glomerular area, attenuated mesangial and endothelial cell proliferation, and revived cell-to-cell propagation of podocytes, which contributed to reduced albuminuria. Compared with ORG vehicle, MC and M1 macrophage (pro-inflammatory) infiltration and M1/M2 ratio were significantly decreased; M2 macrophage (anti-inflammatory) was not significantly increased after incretin-based treatments. Tumor necrosis factor-α (TNF-α) and IL-6 in renal cortex were significantly downregulated, while transforming growth factor-β1 (TGF-β1) remained unchanged.

Conclusions: Incretin-based treatments could alleviate high-fat diet-induced ORG partly through the systemic insulin sensitivity improvement and the attenuated local inflammation, mainly by the decrease of MC and M1 macrophage infiltration and reduction of TNF-α and IL-6.

Sex differences in vascular stiffness and relationship to the risk of renal functional decline in patients with type 2 diabetes

BACKGROUND

Recent data suggest that the higher risk of end-stage renal disease in women compared with men is associated with waist circumference. We investigated whether vascular stiffness which is linked to visceral fat accumulation is gender specific and associated with a loss in renal function.

METHODS

We studied 166 patients with type 2 diabetes at high risk of progressive renal disease. A vascular stiffness index was derived from measurement of the peripheral arterial pulse waveform using infrared finger photoplethysmography. Multiple regression analysis was used to examine the relationship between vascular stiffness and traditional clinical and biochemical renal disease risk factors.

RESULTS

Women were of similar mean (standard deviation) age [61.6 (6.8) vs 60.0 (8.3) years; p = 0.444] and duration of diabetes [9.8 (7.2) vs 10.9 (8.1) years; p = 0.885] compared to men. Waist circumference was significantly associated with vascular stiffness [regression coefficient B = 0.15 (95% confidence interval: 0.06-2.24); p = 0.001]. There was a negative slope parameter for the relationship between glomerular filtration rate and vascular stiffness [ B = -0.15 (95% confidence interval: -0.22 to -0.09); p < 0.001] in women only.

CONCLUSION

In this cohort, early renal functional decline in women is linked to increased vascular stiffness which may be associated with visceral fat accumulation as determined by waist circumference.

High dietary phosphorus density is a risk factor for incident chronic kidney disease development in diabetic subjects: a community-based prospective cohort study

Background: High serum phosphorus concentrations are associated with an increased risk of cardiovascular disease and progression of chronic kidney disease (CKD). However, the relation between dietary phosphorus intake and CKD development has not been well evaluated.Objective: In this study, we investigated the impact of dietary phosphorus density on the development of incident CKD in a cohort of subjects with normal renal function.Design: Data were retrieved from the Korean Genome and Epidemiology Study, a prospective community-based cohort study. The study cohort consisted of subjects aged 40-69 y, who were followed up biennially from 2001 to 2014. A total of 873 subjects with diabetes mellitus (DM) and 5846 subjects without DM (non-DM) were included in the final analysis. The primary endpoint was incident CKD, defined as a composite of estimated glomerular filtration rate <60 mL · min^-1 · 1.73 m^-2 and/or the development of proteinuria.Results: In the DM and non-DM groups, the mean ages of the participants were 55.6 ± 8.7 and 51.4 ± 8.6 y, the numbers of male subjects were 454 (52.0%) and 2784 (47.6%), and the mean estimated glomerular filtration rates were 91.6 ± 14.0 and 94.5 ± 14.0 mL · min^-1 · 1.73 m^-2, respectively. The mean values of dietary phosphorus density, defined as the ratio of a single-day dietary phosphorus amount to the total daily calorie intake, were 0.51 ± 0.08 mg/kcal in the DM group and 0.51 ± 0.07 mg/kcal in the non-DM group. During the follow-up, CKD newly developed in 283 (32.4%) and 792 subjects (13.5%) in the DM and non-DM groups, respectively. When the subjects were divided into quartiles according to the dietary phosphorus density in each group, the highest quartile was significantly associated with the development of incident CKD by multiple Cox proportional hazard analysis in the DM group (P = 0.02) but not in the non-DM group (P = 0.72).Conclusions: High dietary phosphorus density is associated with an increased risk of CKD development in DM patients with normal renal function. The causality in this association needs to be tested in a randomized controlled trial.

Increased body mass index is a risk factor for end-stage renal disease in the Chinese Singapore population

The relationship between body mass index (BMI) and end-stage renal disease (ESRD) is confounded by co-morbidities associated with both conditions. Furthermore, the association at low range BMI is controversial. We studied this association in the Singapore Chinese Health Study, a population-based prospective cohort that recruited Singaporean Chinese men and women 45-74 years of age from 1993 to 1998. Self-reported weight, height, lifestyle factors, usual diet, and medical history were collected via an interviewer-administered questionnaire. Incident ESRD cases were identified via record linkage with the nationwide ESRD registry. The computed Cox proportional hazard regression was adjusted for potential risk factors. After an average follow-up of 15.5 years, 827 incident ESRD cases were identified. Compared with a normal BMI of 18.5 to under 23 kg/m², the hazard ratios and (95% confidence intervals) of ESRD risk for BMIs under 18.5, 23 to under 27.5, and 27.5 kg/m² or more were 0.54 (0.37-0.79), 1.40 (1.20-1.64) and 2.13 (1.74-2.59), respectively. This significantly trended, linear, dose-dependent association was only present among those with no history of diabetes, hypertension, coronary heart disease, and stroke at baseline, but not significantly among those with any of these co-morbidities. Thus, BMI itself is a risk factor for ESRD in the general population and this association is present in those without pre-existing diabetes, hypertension, coronary heart disease, and stroke.

Cardiovascular risk factors and incident albuminuria in screen-detected type 2 diabetes

BACKGROUND

It is unclear whether cardiovascular risk factor modification influences the development of renal disease in people with type 2 diabetes identified through screening. We determined predictors of albuminuria 5 years after a diagnosis of screen-detected diabetes within the ADDITION-Europe study, a pragmatic cardiovascular outcome trial of multifactorial cardiovascular risk management.

METHODS

In 1826 participants with newly diagnosed, screen-detected diabetes without albuminuria, we explored associations between risk of new albuminuria (≥2.5 mg mmol-1 for males and ≥3.5 mg mmol-1 for females) and (1) baseline cardio-metabolic risk factors and (2) changes from baseline to 1 year in systolic blood pressure (ΔSBP) and glycated haemoglobin (ΔHbA1c ) using logistic regression.

RESULTS

Albuminuria developed in 268 (15%) participants; baseline body mass index and active smoking were independently associated with new onset albuminuria in 5 years after detection of diabetes. In a model adjusted for age, gender, baseline HbA1c and blood pressure, a 1% decrease in HbA1c and 5-mm Hg decrease in SBP during the first year were independently associated with lower risks of albuminuria (odds ratio), 95% confidence interval: 0.76, 0.62 to 0.91 and 0.94, 0.88 to 1.01, respectively. Further adjustment did not materially change these estimates. There was no interaction between ΔSBP and ΔHbA1c in relation to albuminuria risk, suggesting likely additive effects on renal microvascular disease.

CONCLUSIONS

Baseline measurements and changes in HbA1c and SBP a year after diagnosis of diabetes through screening independently associate with new onset albuminuria 4 years later. Established multifactorial treatment for diabetes applies to cases identified through screening.

The emerging role of the endocannabinoid system in the pathogenesis and treatment of kidney diseases

Endocannabinoids (eCBs) are endogenous lipid ligands that bind to cannabinoid receptors that also mediate the effects of marijuana. The eCB system is comprised of eCBs, anandamide, and 2-arachidonoyl glycerol, their cannabinoid-1 and cannabinoid-2 receptors (CB1 and CB2, respectively), and the enzymes involved in their biosynthesis and degradation. It is present in both the central nervous system and peripheral organs including the kidney. The current review focuses on the role of the eCB system in normal kidney function and various diseases, such as diabetes and obesity, that directly contributes to the development of renal pathologies. Normally, activation of the CB1 receptor regulates renal vascular hemodynamics and stimulates the transport of ions and proteins in different nephron compartments. In various mouse and rat models of obesity and type 1 and 2 diabetes mellitus, eCBs generated in various renal cells activate CB1 receptors and contribute to the development of oxidative stress, inflammation, and renal fibrosis. These effects can be chronically ameliorated by CB1 receptor blockers. In contrast, activation of the renal CB2 receptors reduces the deleterious effects of these chronic diseases. Because the therapeutic potential of globally acting CB1 receptor antagonists in these conditions is limited due to their neuropsychiatric adverse effects, the recent development of peripherally restricted CB1 receptor antagonists may represent a novel pharmacological approach in treating renal diseases.

Estimating Negative Effect of Abdominal Obesity on Mildly Decreased Kidney Function Using a Novel Index of Body-Fat Distribution

Abdominal obesity is a major risk factor of chronic kidney disease (CKD). Conventional obesity-related indicators, included body mass index (BMI), waist circumference (WC), and conicity index (C-index), have some limitations. We examined the usefulness of trunk/body fat mass ratio (T/Br) to predict negative effect of abnormal fat distribution on excretory kidney function. We analyzed anthropometric, biochemical and densitometric data from a nation-wide, population-based, case-control study (the Korean National Health and Nutrition Examination Survey [KNHANES] IV and V). A total of 11,319 participants were divided into 2 groups according to estimated glomerular filtration rate (eGFR, mL·min⁻¹·1.73 m⁻²) as follows: Group I (n = 7,980), eGFR ≥ 90 and ≤ 120; and group II (n = 3,339), eGFR ≥ 60 and < 90. Linear regression analysis revealed that T/Br was closely related to eGFR (β = -0.3173, P < 0.001), and the correlation remained significant after adjustment for age, gender, BMI, WC, C-index, systolic blood pressure (BP), hemoglobin, and smoking amount (β = -0.0987, P < 0.001). Logistic regression analysis showed that T/Br (odds ratio [OR] = 1.046; 95% confidence interval [CI] = 1.039-1.054) was significantly associated with early decline of kidney function, and adjustment for age, gender, BMI, C-index, systolic BP, hemoglobin, serum glucose level, high-density lipoprotein (HDL)-cholesterol, and smoking amount did not reduce the association (OR = 1.020; 95% CI = 1.007-1.033). T/Br is useful in estimating the negative impact of abdominal obesity on the kidney function.

Precocious obesity predisposes the development of more severe cisplatin-induced acute kidney injury in young adult mice

Obesity and its consequences can damage the kidney over time. However, less is known about the impact of developing overweight/obesity during childhood on the kidney in adulthood and the renal impact of a superimposed acute kidney injury (AKI). This study evaluated the effect of obesity induced by a high-fat diet initiated soon after weaning on the adult life of mice and their response to superimposed nephrotoxic effects of cisplatin. C57BL/6 post-weaning mice (3 weeks old) were divided into a control group (CT, n = 12) and a high-fat diet group (HF, n = 12). After 9 weeks, animals were further divided into the following groups: CT, CT treated with a single dose of cisplatin (CTCis, 20 mg/kg, i.p.), HF and HF treated with cisplatin (HFCis). The HF group exhibited higher body weight gain compatible with a moderate obesity. Obese mice presented increased visceral adiposity, hyperkalemia, sodium retention, glomerular hyperfiltration and proteinuria, without any significant changes in blood pressure and glycemia. AKI induced by cisplatin was exacerbated in obese animals with a 92% reduction in the GFR versus a 31% decrease in the CTCis group; this sharp decline resulted in severely elevated serum creatinine and urea levels. Acute tubular necrosis induced by cisplatin was worsened in obese mice. The HFCis group exhibited robust systemic and intrarenal inflammation that was significantly higher than that in the CTCis group; the HFCis group also showed a higher degree of renal oxidative stress. In conclusion, the moderate degree of obesity induced shortly after weaning resulted in mild early renal alterations, however, obese young animals were prone to develop a much more severe AKI induced by cisplatin.

Diabetes and kidney disease: the role of sodium-glucose cotransporter-2 (SGLT-2) and SGLT-2 inhibitors in modifying disease outcomes

Patients with type 2 diabetes (T2D) often have coexisting chronic kidney disease (CKD). However, healthy renal function is crucial in maintaining glucose homeostasis, assuring that almost all of the filtered glucose is reabsorbed by the sodium glucose cotransporters (SGLTs) SGLT-1 and SGLT-2. In diabetes, an increased amount of glucose is filtered by the kidneys and SGLT-2 is upregulated, leading to increased glucose absorption and worsening hyperglycemia. Prolonged hyperglycemia contributes to the development of CKD by inducing metabolic and hemodynamic changes in the kidneys. Due to the importance of SGLT-2 in regulating glucose levels, investigation into SGLT-2 inhibitors was initiated as a glucose-dependent mechanism to control hyperglycemia, and there are three agents currently approved for use in the United States: dapagliflozin, canagliflozin, and empagliflozin. SGLT-2 inhibitors have been shown to reduce glycated hemoglobin (A1C), weight, and blood pressure, which not only affects glycemic control, but may also help slow the progression of renal disease by impacting the underlying mechanisms of kidney injury. In addition, SGLT-2 inhibitors have shown reductions in albuminuria, uric acid, and an increase in magnesium. Caution is advised when prescribing SGLT-2 inhibitors to patients with moderately impaired renal function and those at risk for volume depletion and hypotension. Published data on slowing of the development, as well as progression of CKD, is a hopeful indicator for the possible renal protection potential of this drug class. This narrative review provides an in-depth discussion of the interplay between diabetes, SGLT-2 inhibitors, and factors that affect kidney function.

The dual roles of obesity in chronic kidney disease: a review of the current literature

PURPOSE OF REVIEW

Obesity is a major risk factor for the development of de novo chronic kidney disease (CKD). However, once kidney disease is acquired, obesity is paradoxically linked with greater survival, especially in those with advanced CKD. This review examines current evidence for obesity as a risk factor for incident CKD, studies of obesity and mortality across various CKD populations, and potential mechanisms underlying the 'obesity paradox' in kidney disease.

RECENT FINDINGS

Large cohort studies show that overweight body habitus, especially in the context of metabolic syndrome, is associated with higher risk of incident CKD. Emerging data also suggest weight-loss interventions retard or reverse early CKD progression, whereas in hemodialysis patients weight-loss paradoxically heralds poor outcomes. Although the pathogenesis of CKD in obesity remains unclear, studies indicate that excess body fat leads to kidney disease via indirect and direct mechanisms. Meta-analyses suggest that overweight and obese BMI ranges are counterintuitively associated with lower mortality in advanced predialysis and dialysis-dependent CKD patients, whereas a pooled analysis observed that higher pretransplantation BMI was associated with higher mortality in kidney transplantation recipients.

SUMMARY

In addition to its role as a risk factor for de novo CKD, there appears to be a consistent association between obesity and lower mortality in those with established CKD, particularly among hemodialysis patients, suggesting that the reverse epidemiology of obesity is biologically plausible.

Long-Term Body Mass Index Trends After Living-Donor Nephrectomy

OBJECTIVES

As the demand for kidney transplant allografts has increased, many centers are expanding the upper limit of acceptable body mass index for kidney donors. However, obesity is a risk factor for developing renal disease. Our goal was to quantify body mass index trends in donor nephrectomy patients and to institute nutrition counseling to promote sustainable weight loss to reduce the risk of metabolic syndrome-derived renal dysfunction.

MATERIALS AND METHODS

Ninety patients who underwent donor nephrectomy between 2007 and 2012 consented to having height and weight data collected at multiple time points. After data collection, each patient underwent a standardized nutrition counseling session. One year later, body mass index was reassessed.

RESULTS

Preoperatively, 52% of the patients were overweight or obese. The percentage of overweight and obese patients remained stable for 2 years after surgery. However, at 3, 4, and 5 years after surgery, these rates increased to 59%, 69%, and 91%. Each patient was counseled about obesity-related comorbidities and provided information about lifestyle modification. One year later, 94% of previously overweight patients and 82% of previously obese patients had a decrease in mean body mass index from 27.2 ± 4.0 kg/m2 to 25.1 ± 3.6 kg/m2.

CONCLUSIONS

Living-donor nephrectomy patients are at risk of developing obesity, similar to the adult population. Nutrition counseling may be beneficial to help normalize body mass index in patients who have become overweight or obese to potentially prevent obesity-related comorbidities. All patients were evaluated by a nutrition specialist after surgery to review our donor nephrectomy nutrition brochure. Body mass index monitoring and primary care follow-up appear to be appropriate surveillance methods.

A systematic review and meta-analysis suggests obesity predicts onset of chronic kidney disease in the general population

Obesity and chronic kidney disease (CKD) are public health priorities that share core pathophysiological mechanisms. However, whether high body mass index (BMI) increases risk of CKD de novo remains ill-defined. To evaluate the role of BMI in predicting CKD onset in the general adult population, we performed a systematic review and meta-analysis of PubMed and ISI Web of Science databases articles published between January 2000 and August 2016 without language restriction. We selected studies in adult individuals from a general population with normal renal function at baseline that reported the risk of low estimated glomerular filtration (eGFR) (under 60 mL/min/1.73m²) and/or albuminuria (1+ at dipstick or an albumin creatinine ratio of 3.4 mg/mmol or more) as hazard ratio, odds ratio or relative risk related to obesity, overweight, or BMI as continuous value. A total of 39 cohorts covering 630, 677 participants with a mean follow-up of 6.8 years were selected. Obesity increased the relative risk, 95% confidence interval and heterogeneity (I²) of developing low eGFR (1.28, 1.07-1.54, [I²: 95.0%]) and albuminuria (1.51, 1.36-1.67, [I²: 62.7%]). Increase of BMI unit was also associated with higher risk of low eGFR (1.02, 1.01-1.03, [I²: 24.3%]) and albuminuria (1.02, 1.00-1.04, [I²: 0%]). Conversely, overweight did not predict onset of either low eGFR (1.06, 0.94-1.21, [I²: 50.0%]) or albuminuria (1.24, 0.98-1.58, [I²: 49.4%]). Thus, a high BMI predicts onset of albuminuria without kidney failure (CKD stages 1-2) as well as CKD stages 3 and higher, the effect being significant only in obese individuals. Hence, our findings may have implications to improve risk stratification and recommendations on body weight control in the general population.

Bariatric Surgery and Kidney-Related Outcomes

The prevalence of severe obesity in both the general and the chronic kidney disease (CKD) populations continues to rise, with more than one-fifth of CKD patients in the United States having a body mass index of ≥35 kg/m². Severe obesity has significant renal consequences, including increased risk of end-stage renal disease (ESRD) and nephrolithiasis. Bariatric surgery represents an effective method for achieving sustained weight loss, and evidence from randomized controlled trials suggests that bariatric surgery is also effective in improving blood pressure, reducing hyperglycemia, and even inducing diabetes remission. There is also observational evidence suggesting that bariatric surgery may diminish the long-term risk of kidney function decline and ESRD. Bariatric surgery appears to be relatively safe in patients with CKD, with postoperative complications only slightly higher than in the general bariatric surgery population. The use of bariatric surgery in patients with CKD might help prevent progression to ESRD or enable selected ESRD patients with severe obesity to become candidates for kidney transplantation. However, there are also renal risks in bariatric surgery, namely, acute kidney injury, nephrolithiasis, and, in rare cases, oxalate nephropathy, particularly in types of surgery involving higher degrees of malabsorption. Although bariatric surgery may improve long-term kidney outcomes, this potential benefit remains unproved and must be balanced with potential adverse events.

The Renal Pathology of Obesity

Obesity causes various structural, hemodynamic, and metabolic alterations in the kidney. Most of these are likely to be compensatory responses to the systemic increase in metabolic demand that is seen with obesity. In some cases, however, renal injury becomes clinically apparent as a result of compensatory failure. Obesity-related glomerulopathy is the best known of such disease states. Factors that may sensitize obese individuals to renal compensatory failure and associated injury include the severity and number of obesity-associated conditions or complications, including components of metabolic syndrome, and the mismatch of body size to nephron mass, due to nephron reductions of congenital or acquired origin.

Contribution of Four Comorbid Conditions to Racial/Ethnic Disparities in Mortality Risk

INTRODUCTION

The prevalence of key forms of morbidity such as obesity, diabetes, and chronic kidney disease have increased dramatically in the U.S. and elsewhere for decades. Hypertension is etiologically related but its prevalence has been reduced through improved treatment. These diseases are known to have higher than expected rates of comorbidity, but it is not known whether and how these cluster together differentially by race, nor the degree to which they contribute to racial disparities in mortality.

METHODS

Using data from the National Health Interview Survey mortality follow-up (1997-2009, analyzed in 2016), this paper modeled interdependencies between each combination of these four types of morbidity, overall and net of demographic, socioeconomic, and behavioral controls. It then analyzed whether these diseases mediate the relationship between race/ethnicity and mortality risk using discrete time complementary log-log survival models.

RESULTS

American Indians and blacks had significantly elevated rates of comorbidity compared with whites, and Asians' and Pacific Islanders' rates were often significantly lower than whites'. Controlling for these diseases significantly moderated the mortality risk disparity between African American, Hispanic, and Asian/Pacific Islanders and whites. This remained true when individual health behaviors and neighborhood fixed effects were statistically adjusted for. Notably, the full controls model statistically eliminated the association between African American race and mortality risk.

CONCLUSIONS

These diseases contribute significantly to racial/ethnic mortality disparities, particularly between blacks and whites. Future research should consider the mediating role of these diseases for the relationship between social conditions and mortality risks.

Beginning the trajectory to ESKD in adult life: albuminuria in Australian aboriginal children and adolescents

BACKGROUND

Globally, disadvantaged populations suffer a high burden of chronic kidney disease (CKD). The trajectory to CKD during childhood and adolescence remains unclear due to a paucity of longitudinal studies.

METHODS

This was a prospective, population-based cohort study in which since 2002 we have followed 3418 children (1469 non-Aboriginal and 1949 Aboriginal) attending participating schools across New South Wales (NSW), Australia. The albumin:creatinine ratio was measured by dipstick every 2 years together with the body mass index (BMI) and blood pressure. We used multivariable logistic generalised estimating equation models to examine whether Aboriginal children had a higher prevalence of albuminuria compared with non-Aboriginal children with increasing age and to identify potential risk factors.

RESULTS

The mean age at enrolment was 10.6 years, at which time 14.2 % of the children were obese and 16.0 % overweight, with 11.5 % found to have albuminuria. Over 8 years (11,387 participant-years) of follow-up the prevalence of albuminuria increased to 18.5 %, overweight to 16.1 % and obesity to 17.2 %. The BMI standard deviation score (SDS) was found to have a differential effect on the risk of albuminuria in Aboriginal and non-Aboriginal children (P interaction < 0.01). The prevalence of albuminuria decreased as the BMI SDS increased in both groups of children, but it increased more in non-Aboriginal children, leading to a 2.5 % higher prevalence of albuminuria in overweight Aboriginal children (95 % confidence interval 1.0-4.2 %).

CONCLUSION

Compared with non-Aboriginal children, Aboriginal children are of higher risk of albuminuria when overweight or obese. We hypothesise that overweight and obesity are key contributors to the development of adult onset CKD among Aboriginal Australians, which needs further exploration in future studies.

Obesity increases the risk of end-stage renal disease among living kidney donors

Determining candidacy for live kidney donation among obese individuals remains challenging. Among healthy non-donors, body mass index (BMI) above 30 is associated with a 16% increase in risk of end-stage renal disease (ESRD). However, the impact on the ESRD risk attributable to donation and living with only one kidney remains unknown. Here we studied the risk of ESRD associated with obesity at the time of donation among 119 769 live kidney donors in the United States. Maximum follow-up was 20 years. Obese (BMI above 30) live kidney donors were more likely male, African American, and had higher blood pressure. Estimated risk of ESRD 20 years after donation was 93.9 per 10 000 for obese; significantly greater than the 39.7 per 10 000 for non-obese live kidney donors. Adjusted for age, sex, ethnicity, blood pressure, baseline estimated glomerular filtration rate, and relationship to recipient, obese live kidney donors had a significant 86% increased risk of ESRD compared to their non-obese counterparts (adjusted hazard ratio 1.86; 95% confidence interval 1.05-3.30). For each unit increase in BMI above 27 kg/m² there was an associated significant 7% increase in ESRD risk (1.07, 1.02-1.12). The impact of obesity on ESRD risk was similar for male and female donors, African American and Caucasian donors, and across the baseline estimated glomerular filtration rate spectrum. These findings may help to inform selection criteria and discussions with persons considering living kidney donation.

Estimated GFR Before and After Bariatric Surgery in CKD

BACKGROUND

Several reviews have recently detailed the beneficial effects of weight loss surgery for kidney function. However, these studies have a number of limitations, including small sample size, few done in chronic kidney disease (CKD) stages 3 and 4, and many not including the main bariatric surgery procedures used in the United States today.

STUDY DESIGN

This was an observational retrospective cohort study comparing propensity score-matched bariatric surgery patients and nonsurgery control patients who were referred for, but did not have, surgery. Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy were also compared using propensity matching.

SETTING & PARTICIPANTS

Patients (714 surgery patients; 714 controls) were from a large integrated health care system, a mean of 58±8 (SD) years old, and mostly women (77%) and non-Hispanic whites (56%) and had diabetes mellitus (66%) and/or hypertension (91%).

PREDICTOR

Predictors at the time of surgery or referral to surgery were age, sex, race/ethnicity, weight, and presence of diabetes and/or hypertension.

OUTCOMES

The primary outcome for this study was change in estimated glomerular filtration rate (eGFR) from serum creatinine level over a median 3-year follow-up period.

MEASUREMENTS

Serum creatinine was used to calculate eGFR using the CKD-EPI (CKD Epidemiology Collaboration) creatinine equation.

RESULTS

Surgery patients had 9.84 (95% CI, 8.05-11.62) mL/min/1.73m² greater eGFRs than controls at a median 3 years' follow-up and RYGB patients had 6.60 (95% CI, 3.42-9.78) mL/min/1.73m² greater eGFRs than sleeve gastrectomy patients during the same period.

LIMITATIONS

This study is limited by its nonrandomized observational study design, estimation of GFR, and large changes in muscle mass, which may affect serum creatinine level independent of changes in kidney function.

CONCLUSIONS

Bariatric surgery, especially the RYGB procedure, results in significant improvements for up to 3 years in eGFRs for patients with CKD stages 3 and 4.

Association between prediabetes and risk of chronic kidney disease: a systematic review and meta-analysis

AIMS

To assess the effect of prediabetes (impaired fasting glucose and/or impaired glucose tolerance) on the incidence of chronic kidney disease.

METHODS

PubMed and EMBASE were searched (for studies published up to March 2015). Effects estimated from cohort studies reporting the relationship of prediabetes to incident chronic kidney disease [kidney damage (microalbuminuria, albuminuria or proteinuria) and/or decreased glomerular filtration rate] were pooled using a random-effects model meta-analysis.

RESULTS

Nine cohort studies with a total of 185 452, mainly Asian and white, participants were followed for a total of 835 146 person-years. In eight cohort studies defining impaired fasting glucose as fasting glucose 6.1-6.9 mmol/l, the summary relative risk of chronic kidney disease after adjustment for established risk factors was 1.11 (95% CI 1.02-1.21). When a study defining impaired fasting glucose as fasting glucose 5.6-6.9 mmol/dl was added, the overall relative risk of chronic kidney disease was 1.12 (95% CI 1.02-1.21). Exclusion of the only study with information on impaired glucose tolerance did not change the relative risk (1.12; 95% CI 1.02-1.21). There was no evidence of publication bias (P value for Egger test = 0.12).

CONCLUSION

Prediabetes is modestly associated with an increase in chronic kidney disease risk, but this remains to be robustly confirmed. Chronic kidney disease screening among people with prediabetes, and aggressive management of prediabetes in those with chronic kidney disease may be warranted.

Kidney outcomes three years after bariatric surgery in severely obese adolescents

A significant number of severely obese adolescents undergoing bariatric surgery have evidence of early kidney damage. To determine if kidney injury is reversible following bariatric surgery, we investigated renal outcomes in the Teen-Longitudinal Assessment of Bariatric Surgery cohort, a prospective multicenter study of 242 severely obese adolescents undergoing bariatric surgery. Primary outcomes of urine albumin-to-creatinine ratio and cystatin C-based estimated glomerular filtration rate (eGFR) were evaluated preoperatively and up to 3 years following bariatric surgery. At surgery, mean age of participants was 17 years and median body mass index (BMI) was 51 kg/m². In those with decreased kidney function at baseline (eGFR under 90 mL/min/1.73m²), mean eGFR significantly improved from 76 to 102 mL/min/1.73m² at three-year follow-up. Similarly, participants with albuminuria (albumin-to-creatinine ratio of 30 mg/g and more) at baseline demonstrated significant improvement following surgery: geometric mean of ACR was 74 mg/g at baseline and decreased to 17 mg/g at three years. Those with normal renal function and no albuminuria at baseline remained stable throughout the study period. Among individuals with a BMI of 40 kg/m² and more at follow-up, increased BMI was associated with significantly lower eGFR, while no association was observed in those with a BMI under 40 kg/m². In adjusted analysis, eGFR increased by 3.9 mL/min/1.73m² for each 10-unit loss of BMI. Early kidney abnormalities improved following bariatric surgery in adolescents with evidence of preoperative kidney disease. Thus, kidney disease should be considered as a selection criteria for bariatric surgery in severely obese adolescents who fail conventional weight management.

Chronic kidney disease and high eGFR according to body composition phenotype in adults with normal BMI

BACKGROUND AND AIMS

Body composition contributes to the risk of chronic kidney disease (CKD) and glomerular hyperfiltration. In adults with normal body mass index (BMI), the relationships of body composition with CKD and high estimated glomerular filtration rate (eGFR) are largely unknown.

METHODS AND RESULTS

We analyzed 10,734 adults from the Korean National Health and Nutrition Examination Survey (KNHANES), whose body mass index (BMI) was within the normal range (18.5-24.9 kg/m²). Body composition was categorized into four phenotypes (normal, sarcopenia alone, obesity alone, and sarcopenic obesity) based on appendicular lean mass index (ALMI) and total body fat percentage (TBF%) measured by dual-energy X-ray absorptiometry (DXA). We examined the relationship of CKD and high eGFR (eGFR ≥ 120 ml/min per 1.73 m²) with body composition phenotypes. Sarcopenia alone (14.3%), obesity alone (16.0%), and sarcopenic obesity (10.7%) were prevalent. The association between sarcopenia alone and eGFR was J-shaped, while that between sarcopenic obesity and eGFR was U-shaped. In multivariate logistic regression analysis compared with the normal phenotype, sarcopenic obesity had an elevated odds ratio (OR) for CKD (OR: 1.59, 95% CI: 1.16-2.19). Sarcopenia alone (OR: 1.87; 95% CI: 1.41-2.47) and sarcopenic obesity (OR: 2.37, 95% CI: 1.68-3.36) had elevated OR for high eGFR.

CONCLUSION

These findings suggest that decreased muscle mass and coexistence with excess adiposity show associations with CKD and high eGFR even in adults with normal BMI. Body composition measured by DXA could provide information on the relationship of body composition with CKD and high eGFR.

Naringenin ameliorates renal and platelet purinergic signalling alterations in high-cholesterol fed rats through the suppression of ROS and NF-κB signaling pathways

Naringenin (NGEN) is a natural flavonoid aglycone of naringin that has been reported to have a wide range of pharmacological properties, such as antioxidant activity and free radical scavenging capacity. The aim of this study was to investigate the protective effect of NGEN on oxidative and inflammatory parameters, as well as to evaluate the hydrolysis of adenine nucleotides in kidney and platelet membranes of rats exposed to a hypercholesterolemic diet (HCD) for 90 days. Kidney oxidative stress and mRNA expression of the ectonucleoside triphosphate diphosphohydrolases (NTPDases), ecto-5'-nucleotidase (CD73), inducible NO synthase (iNOS), tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6) and the nuclear factor kappa B (NF-κB) genes were evaluated by real time RT-PCR. The co-administration of NGEN (50 mg kg(-1)) for 90 days significantly prevented renal failure in HCD rats as indicated by an improvement of renal markers. Histopathological observation findings are also consistent with these effects. Moreover, NGEN (50 mg kg(-1)) significantly decreased the lipid profile and inhibited pro-oxidant and inflammation marker levels in the kidney of HCD rats. Furthermore, the NTPDase activities were significantly decreased in platelets and kidney membranes of HCD-treated rats and these alterations were improved by NGEN. In conclusion, this study suggests that naringenin can potentially improve the renal failure and platelet alterations observed in rats fed a hypercholesterolemic diet probably through its antioxidant effects.

An Analysis of Anthropometric Indicators and Modifiable Lifestyle Parameters Associated with Hypertensive Nephropathy

The surge in prevalence of chronic noncommunicable diseases like hypertension and chronic kidney disease has been linked with modifiable lifestyle practices and increased body fat. This study sought to compare the association between different modifiable lifestyle practices, adiposity indices, renal function parameters, and hypertension as well as the predictive implications for levels of these parameters in target cardiac organ damage among an urban Ghanaian hypertensive population. Using a hospital-based case-control study design, 241 Ghanaian indigenes from the Kumasi metropolis were recruited for this study. The case group was made up of 180 hypertensives and 61 normotensives served as controls. In addition to sociodemographic data, standard haemodynamic, anthropometric, renal function, and cardiac organ damage assessments were done. The prevalence of chronic kidney disease (CKD) ranged from 13.3% to 16.6% depending on the equation used in estimating the glomerular filtration rate (eGFR). Percentage cluster distribution by chronic kidney disease was observed to be significantly tilted toward the upper quartiles (3rd and 4th) of the haemodynamic parameters measured. Chronic kidney disease was significantly higher among self-reported smokers and alcoholic hypertensives. In this urban population, adiposity was associated with hypertension and renal insufficiency. Chronic kidney disease was associated with hypertension and cardiac abnormalities.

Consequences of morbid obesity on the kidney. Where are we going?

Obesity and morbid obesity are modifiable risk factors for the development and progression of kidney disease. Obesity has reached epidemic proportions and is currently an important health problem in Europe, so it is necessary to develop therapeutic and preventive strategies. The obesity-related glomerulopathy has been defined as a secondary form of focal segmental glomerulosclerosis, and its most characteristic feature is glomerulomegaly. The renal evolution of patients with obesity-related glomerulopathy (ORG) who have not been treated is unfavourable. However, morbidly obese patients with ORG that underwent bariatric surgery and drastic weight loss had a better outcome. Many inflammatory factors have been implicated in the pathogenic mechanism of renal disease in obesity. Hypoadiponectinaemia, hyperleptinaemia and hyperaldosteronism have been associated with glomerular injury in obese patients. The application of modern techniques has provided important insights that increase the current understanding of ORG. However, further investigation is needed.

Prevalence of Chronic Kidney Disease in Turkish Adults With Obesity and Metabolic Syndrome: A Post Hoc Analysis from Chronic Renal Disease in Turkey Study

BACKGROUND

Obesity confers an increased risk of chronic kidney disease (CKD), which is increased further by accompanying metabolic abnormalities.

OBJECTIVE

To investigate the relationship of the risk of CKD with obesity and metabolic syndrome (MS) in adults by means of post hoc analysis of data from the Chronic Renal Disease in Turkey (CREDIT) study.

METHODS

The anthropometric measurements of a total of 9,100 adult participants in the CREDIT study were included in the analyses. Subjects were classified according to the presence or absence of obesity (body mass index [BMI] > 30) and MS. Logistic regression analyses were used to estimate odds ratio for CKD. Effect modification analyses were also performed.

RESULTS

The prevalence of obesity was 20.6% and that of MS was 31.3%. The prevalence of CKD was higher among obese subjects compared to those with a normal BMI (20.5% vs. 14%; P < .001). The odds ratio (OR) for CKD was 1.296 (95% confidence interval [CI], 1.121-1.498) for subjects who were overweight, 1.718 (95% CI, 1.444-2.044) for those with class I obesity, 1.983 (95% CI, 1.489-2.641) for those with class II obesity and 2.799 (95% CI, 1.719-4.557) for subjects with extreme obesity (P < .001 for each subgroup) compared to subjects with a normal BMI. CKD was significantly more prevalent in subjects with MS (21.9% vs. 12.3%, P < .001). The OR for CKD was higher in obese subjects with MS (adjusted OR, 1.321; 95% CI, 1.109-1.573; P = .002).

CONCLUSION

The stratification of obese individuals based on their metabolic phenotype is important for prevention and treatment of CKD.

Emerging co-morbidities of obstructive sleep apnea: cognition, kidney disease, and cancer

Obstructive sleep apnea (OSA) causes daytime fatigue and sleepiness, and has an established relationship with cardiovascular and metabolic disease. Recent years have seen the emergence of an evidence base linking OSA with an increased risk of degenerative neurological disease and associated cognitive impairment, an accelerated rate of decline in kidney function with an increased risk of clinically significant chronic kidney disease (CKD), and with a significantly higher rate of cancer incidence and death. This review evaluates the evidence base linking OSA with these seemingly unrelated co-morbidities, and explores potential mechanistic links underpinning their development in patients with OSA, including intermittent hypoxia (IH), sleep fragmentation, sympathetic excitation, and immune dysregulation.

Urinary Netrin-1: A New Biomarker for the Early Diagnosis of Renal Damage in Obese Children

OBJECTIVE

Urinary netrin-1 is a new marker to demonstrate early tubular damage. The aim of this study was to determine whether urinary netrin-1 is increased in obese children.

METHODS

A total of 68 normoalbuminuric and normotensive obese patients and 65 controls were included in the study. Urine samples were collected for assessment of urinary phosphorus, sodium, potassium, creatinine, albumin, and netrin-1. Blood samples were collected for measurements of fasting glucose, insulin, lipid, phosphorus, sodium, potassium, and creatinine levels. Homeostatic model assessment insulin resistance index was calculated.

RESULTS

Gender and age were similar between obese and control groups (12.01±3.03 vs. 11.7±3.2 years, p=0.568 and 33 vs. 35 girls, p=0.543, respectively). Obese patients had significantly higher netrin-1 excretion than the controls (841.68±673.17 vs. 228.94±137.25 pg/mg creatinine, p=0.000). Urinary netrin-1 level was significantly higher in obese subjects with insulin resistance compared to those without insulin resistance (1142±1181 vs. 604.9±589.91 pg/mg creatinine, p=0.001).

CONCLUSION

In normotensive and normoalbuminuric obese children, urinary netrin-1 level can increase before onset of albuminuria. Urinary netrin-1 excretion appears to be affected predominantly by insulin resistance and hyperinsulinemia. Urinary netrin-1 may be a new biomarker for determining early tubular injury in obese children.

Paternal High Fat Diet in Rats Leads to Renal Accumulation of Lipid and Tubular Changes in Adult Offspring

Along with diabetes and obesity, chronic kidney disease (CKD) is increasing across the globe. Although some data support an effect of maternal obesity on offspring kidney, the impact of paternal obesity is unknown; thus, we have studied the effect of paternal obesity prior to conception. Male Sprague Dawley rats were fed chow diet or high fat diet (HFD) for 13-14 weeks before mating with chow-fed females. Male offspring were weaned onto chow and killed at 27 weeks for renal gene expression and histology. Fathers on HFD were 30% heavier than Controls at mating. At 27 weeks of age offspring of obese fathers weighed 10% less; kidney triglyceride content was significantly increased (5.35 ± 0.84 vs. 2.99 ± 0.47 μg/mg, p < 0.05, n = 8 litters per group. Histological analysis of the kidney demonstrated signs of tubule damage, with significantly greater loss of brush border, and increased cell sloughing in offspring of obese compared to Control fathers. Acat1, involved in entry of fatty acid for beta-oxidation, was significantly upregulated, possibly to counteract increased triglyceride storage. However other genes involved in lipid metabolism, inflammation and kidney injury showed no changes. Paternal obesity was associated with renal triglyceride accumulation and histological changes in tubules, suggesting a mild renal insult in offspring, who may be at risk of developing CKD.

Organic Cation Transporter 2 Overexpression May Confer an Increased Risk of Gentamicin-Induced Nephrotoxicity

Nephrotoxicity is a relevant limitation of gentamicin, and obese patients have an increased risk for gentamicin-induced kidney injury. This damage is thought to depend on the accumulation of the drug in the renal cortex. Obese rats showed substantially higher levels of gentamicin in the kidney than did lean animals. This study characterized the role of organic cation transporters (OCTs) in gentamicin transport and elucidated their possible contribution in the increased renal accumulation of gentamicin in obesity. The mRNA and protein expression levels of the organic cation transporters Oct2 (Slc22a2) and Oct3 (Slc22a3) were increased in kidney samples from obese mice fed a high-fat diet. Similarly, OCT2 (∼2-fold) and OCT3 (∼3-fold) showed increased protein expression in the kidneys of obese patients compared with those of nonobese individuals. Using HEK293 cells overexpressing the different OCTs, human OCT2 was found to transport [(3)H]gentamicin with unique sigmoidal kinetics typical of homotropic positive cooperativity (autoactivation). In mouse primary proximal tubular cells, [(3)H]gentamicin uptake was reduced by approximately 40% when the cells were coincubated with the OCT2 substrate metformin. The basolateral localization of OCT2 suggests that gentamicin can enter proximal tubular cells from the blood side, probably as part of a slow tubular secretion process that may influence intracellular drug concentrations and exposure time. Increased expression of OCT2 may explain the higher accumulation of gentamicin, thereby conferring an increased risk of renal toxicity in obese patients.

The influence of body composition on renal function in patients with coronary artery disease and its prognostic significance: a retrospective cohort study

Objective

We try to analyse the effect of renal functions on death in CAD patients with different body compositions.

Methods

A retrospective analysis was conducted in 2989 consecutive patients with CAD confirmed by coronary angiography were enrolled and were grouped into two categories: basically preserved renal function (PRF) (eGFR ≥60 ml/min) and obviously reduced renal function (RRF) (eGFR <60 ml/min). The influence of renal insufficiency on mortality of CAD was detected in every tertile of body composition, including body mass index (BMI), body fat (BF) and lean mass index (LMI). The end points were all-cause mortality.

Results

The mean follow-up time was 29.1 ± 12.5 months and death events occurred in 271 cases. The percentage of patients with RRF was positively correlated with BF and inversely correlated with the LMI, but no relationship to BMI. The survival curves showed that the risk of death was significantly higher in the RRF patients in all subgroups stratified using BMI, BF, or LMI (log rank test, all p < 0.001). The COX multivariate regression analysis showed that the risk of death was significantly higher in the RRF patients with high BF (HR 1.95, CI 1.25–3.05) and low LMI (HR 1.82, CI 1.19–2.79). Meanwhile, risk of death was significantly higher in RRF patients with a high BMI (HR 2.08, CI 1.22–3.55) or low BMI (HR 1.98, CI 1.28–3.08) but this risk was not significant in patients with a medium BMI (HR 1.12, 0.65–1.94). The subgroup analysis of patients with acute coronary syndrome (ACS) showed similar results.

Conclusions

For patients with CAD, renal insufficiency was positively correlated with BF, inversely correlated with LMI, and unrelated to BMI. The effect of renal insufficiency on the risk of death of CAD was related to body composition.

From chronic kidney disease to kidney transplantation: The impact of obesity and its treatment modalities

Obesity is associated with worse short-term outcomes after kidney transplantation but the effect on long-term outcomes is unknown. Although some studies have reported worse outcomes for obese recipients when compared to recipients with a BMI in the normal range, obese recipients who receive a transplant have better outcomes than those who remain wait-listed. Whether transplant candidates should be advised to lose weight before or after transplant has been debated and this is mainly due to the gap in the literature linking pre-transplant weight loss with better outcomes post-transplantation. The issue is further complicated by the use of BMI as a metric of body fat, the obesity paradox in dialysis patients and the different ethical viewpoints of utility versus equity. Measures used to reduce weight loss, including orlistat and bariatric surgery (in particular those with a malabsorptive component), have been associated with enteric hyperoxaluria with consequent risk of nephrolithiasis and oxalate nephropathy. In this review, we discuss the evidence regarding the use of weight loss measures in the kidney transplant candidate and recipient with a view to recommending whether weight loss should be pursued before or after kidney transplantation.