The effect of obesity on chronic kidney disease

Does Metabolic Syndrome and Its Components Have Prognostic Significance for Renal and Cardiovascular Outcomes in IgA Nephropathy?

BACKGROUND

Patients with IgA nephropathy (IgAN), a chronic kidney disease (CKD), are significantly more likely to have cardiovascular (CV) mortality and morbidity than the general population. The occurrence of metabolic syndrome (MetS) and metabolic risk factors are independent risk factors for CV disease and renal progression. The purpose of this study was to determine how metabolic characteristics in a homogeneous population of CKD patients relate to prognosis.

METHODS

A total of 145 patients with CKD stages 1-4 diagnosed with IgA nephropathy (92 men and 53 women, aged 54.7 ± 13 years) were examined and monitored for a median of 190 months. All-cause mortality and any CV event, such as stroke, myocardial infarction, revascularization (CV), end-stage renal disease, and renal replacement therapy (renal), have been included in the composite endpoints (CV and renal).

RESULTS

Patients with MetS had significantly more primary endpoint events (23/65 patients vs. 15/60 patients, p < 0.001) compared to the non-MetS group. The MetS group had a statistically significant increase in both primary renal and CV endpoints (18/65 vs. 10/60, p = 0.001), and in CV endpoint events (7/65 vs. 6/60, p = 0.029) among the secondary endpoints (CV and renal separately). Based on Cox regression analysis, the main endpoint independent predictors of survival were dyslipidemia, eGFR, hemoglobin, urine albuminuria, and diabetes mellitus. Independent predictors of secondary renal endpoints were dyslipidemia, hemoglobin, urine albumin, and eGFR. Predictors of secondary cardiovascular endpoints were gender, BMI, and diabetes. When Kaplan-Meier curves were analyzed at the combined endpoints (CV and renal) or each endpoint independently, significant differences were seen between MetS and non-MetS. With more MetS components, the primary endpoint rate increased significantly (MetS comp. 0 vs. MetS comp. 2+, primary endpoints, p = 0.012).

CONCLUSIONS

Our results show that the metabolic profile has a prognostic role not only for renal endpoints but also for CV endpoints in IgAN. BMI, hyperuricemia, hypertension, and diabetes have a predictive value for the prognosis of IgA nephropathy.

Punica granatum L. Polyphenolic Extract as an Antioxidant to Prevent Kidney Injury in Metabolic Syndrome Rats

Introduction

Obesity and metabolic syndrome (MetS) constitute a rapidly increasing health problem and contribute to the development of multiple comorbidities like acute and chronic kidney disease. Insulin resistance, inappropriate lipolysis, and excess of free fatty acids (FFAs) are associated with glomerulus hyperfiltration and atherosclerosis. The important component of MetS, oxidative stress, is also involved in the destabilization of kidney function and the progression of kidney injury. Natural polyphenols have the ability to reduce the harmful effect of reactive oxygen and nitrogen species (ROS/RNS). Extract derived from Punica granatum L. is rich in punicalagin that demonstrates positive effects in MetS and its associated diseases. The aim of the study was to investigate the effect of bioactive substances of pomegranate peel to kidney damage associated with the MetS.

Methods

In this study, we compared biomarkers of oxidative stress in kidney tissue of adult male Zucker Diabetic Fatty (ZDF) rats with MetS and healthy controls that were treated with Punica granatum L. extract at a dose of 100 or 200 mg/kg. Additionally, we evaluated the effect of polyphenolic extract on kidney injury markers and remodeling. The concentration of ROS/RNS, oxLDL, glutathione (GSH), kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), metalloproteinase 2 and 9 (MMP-2, MMP-9), and the activity of superoxide dismutase (SOD) and catalase (CAT) were measured.

Results

The data showed significant differences in oxidative stress markers between treated and untreated MetS rats. ROS/RNS levels, oxLDL concentration, and SOD activity were lower, whereas CAT activity was higher in rats with MetS receiving polyphenolic extract. After administration of the extract, markers for kidney injury (NGAL, KIM-1) decreased.

Conclusion

Our study confirmed the usefulness of pomegranate polyphenols in the treatment of MetS and the prevention of kidney damage. However, further, more detailed research is required to establish the mechanism of polyphenol protection.

The association between obesity and vitamin D deficiency modifies the progression of kidney disease after ischemia/reperfusion injury

Acute kidney injury (AKI) alters renal hemodynamics, leading to tubular injury, activating pathways of inflammation, proliferation, and cell death. The initial damage caused to renal tissue after an ischemia/reperfusion (I/R) injury exerts an important role in the pathogenesis of the course of AKI, as well as in the predisposition to chronic kidney disease. Vitamin D deficiency has been considered a risk factor for kidney disease and it is associated with tubulointerstitial damage, contributing to the progression of kidney disease. Obesity is directly related to diabetes mellitus and hypertension, the main metabolic disorders responsible for the progression of kidney disease. Furthermore, the expansion of adipose tissue is described as an important factor for increased secretion of pro-inflammatory cytokines and their respective influence on the progression of kidney disease. We aimed to investigate the influence of vitamin D deficiency and obesity on the progression of renal disease in a murine model of renal I/R. Male Wistar rats underwent renal I/R surgery on day 45 and followed until day 90 of the protocol. We allocated the animals to four groups according to each diet received: standard (SD), vitamin D-depleted (VDD), high fat (HFD), or high fat vitamin D-depleted (HFDV). At the end of 90 days, we observed almost undetectable levels of vitamin D in the VDD and HFDV groups. In addition, HFD and HFDV groups presented alterations in the anthropometric and metabolic profile. The combination of vitamin D deficiency and obesity contributed to alterations of functional and hemodynamic parameters observed in the HFDV group. Moreover, this combination favored the exacerbation of the inflammatory process and the renal expression of extracellular matrix proteins and phenotypic alteration markers, resulting in an enlargement of the tubulointerstitial compartment. All these changes were associated with an increased renal expression of transforming growth factor β and reduced expression of the vitamin D receptor. Our results show that the synergistic effect of obesity and vitamin D deficiency exacerbated the hemodynamic and morphological changes present in the evolution of renal disease induced by I/R.

Dynapenic-abdominal obesity as an independent risk factor for chronic kidney disease in postmenopausal women: a population-based cohort study

OBJECTIVE

Low muscle strength and obesity lead to a higher risk of chronic kidney disease (CKD). Perimenopause is associated with a natural decline in muscle strength and an increase in visceral adiposity. Dynapenic obesity, which is the coexistence of low muscle strength and obesity, is expected to synergistically increase the prevalence of CKD in postmenopausal women. The aim of this study was to determine combined associations of dynapenia and obesity with CKD in postmenopausal women.

METHODS

This study used data from the Korean National Health and Nutrition Examination Survey, 2016 to 2019. The study included 4,525 postmenopausal women aged 42 to 80 years that were classified into four groups based on waist circumference (≥85 cm) and hand grip strength (<18 kg): normal, dynapenic, obese, or dynapenic-obese. According to the Kidney Disease: Improving Global Outcomes, we defined CKD as an estimated glomerular filtration rate <60 mL/min per 1.73 m2. Complex sample logistic regression models were conducted to determine the relationships among coexistence of dynapenia, abdominal obesity, and the risk of CKD.

RESULTS

Dynapenic-abdominal obese group displayed lower estimated glomerular filtration rate levels than other groups (P < 0.05 for all data). The prevalence rates of CKD were 15.5%, 7.8%, 6.2%, and 2.4% in the dynapenic-abdominal obese, dynapenic, abdominal obese, and normal groups, respectively (P < 0.001). Complex sample logistic regression analyses, after adjusting for age, height, health behaviors, and comorbidities, showed that the odds ratio for CKD with respect to dynapenic-abdominal obesity was 1.82 (95% confidence interval, 1.19-2.79) and to abdominal obesity was 1.54 (95% confidence interval, 1.07-2.22) than in the normal group.

CONCLUSIONS

This study demonstrated that dynapenic-abdominal obesity, as determined by low handgrip strength and high waist circumference values, was associated with increased risk of CKD in postmenopausal women.

Ceftazidime dosing in obese patients: is it time for more?

INTRODUCTION

Ceftazidime is used for the treatment of many bacterial infections, including severe P. aeruginosa infections. Like other beta-lactams, inter-individual variability in ceftazidime pharmacokinetics has been described. Due to its related pathophysiological modifications, obesity might influence ceftazidime pharmacokinetics.

AREAS COVERED

The objective of this review is to assess the current state of knowledge about the impact of obesity on ceftazidime treatment. A literature search was conducted on PubMed-MEDLINE (2016-2021) to retrieve pharmacokinetic studies published in English, matching the terms 'ceftazidime' AND 'pharmacokinetics.'

EXPERT OPINION

The impact of obesity on pharmacokinetics is generally poorly known, mainly because obese patients are often excluded from clinical studies. However, the published literature clearly shows that obese patients have significantly lower ceftazidime concentrations. This could be explained by increased volume of distribution and clearance. This low exposure represents a major factor of therapeutic failure, potentially fatal for critically ill patients. While further studies would be useful to better assess the magnitude and understanding of this variability, the use of higher doses of ceftazidime is needed in obese patients. Moreover, therapeutic drug monitoring for dose adaptation is of major interest for these patients, as the efficacy of ceftazidime seems to be directly related to its plasma concentration.

Chronic Kidney Disease, Metabolic Syndrome and Cardiovascular Risk: Insights and Associated Mechanistic Pathways

Abstract:

This study is a narrative review that aims to address the conceptual, characteristic, pathophysiological, and mechanistic aspects that define the profile of metabolic syndrome and chronic kidney disease. The objective was to investigate current knowledge and elucidate, through discussions on the topic, the main interrelated paths. This review was carried out unsystematically, from March to May 2020, by means of a survey of the literature indexed in the PubMed, Web of Science, and Scopus (Elsevier®) databases. The scientific materials collected showed that the cross-talk between the diseases in question is mainly based on the conditions of resistance to insulin action, endothelial dysfunction, activation pathways of the Renin-Angiotensin-Aldosterone system and adipokine imbalance, also emphasizing the influence of atherosclerotic events in kidney damage. Furthermore, it was reinforced the fact that inflammatory processes play an important role in the worsening and evolution of the clinical condition of patients, especially when they have underlying pathologies chronically treated for subclinical inflammation. It is expected that a greater number of original researches will propose to investigate other possible interactions, with a view to standardized treatment of these diseases or nutritional management.

Periodontitis exacerbates the renal degenerative effects of obesity in rats

BACKGROUND/OBJECTIVES

Obesity and periodontitis are systemic subclinical inflammatory diseases with established negative renal effects. The aim of this animal study was to thoroughly investigate the possible effects of these two diseases on renal structure and function.

METHODS

Thirty-two male Sprague Dawley rats were divided into four groups: control (C), obesity (Ob), experimental periodontitis (Ep), and Ob + Ep. The first 16 weeks of the experiment were aimed for the induction of obesity and the last 5 weeks for the induction of periodontitis. Throughout the experimental period, the C and Ep groups were fed standard rat chow, while the Ob groups (Ob and Ob + Ep) were fed high-fat rat chow. Right after the establishment of obesity, periodontal tissue destruction was achieved by placing 3.0 silk sutures in sub-paramarginal position around the cervices of mandibular right-left first molar teeth and preserving them for 5 weeks. On the last day of the 22^nd week, following blood collection, all rats were euthanized, and kidneys and mandibles were collected. Alveolar bone loss was measured on microcomputed tomographic slices. Histopathological evaluations (light microscopy, semi-quantitative analysis of renal corpuscle area, and immunohistochemical analysis of caspase-3 activity) were done on right kidneys and biochemical evaluations (malonyl-aldehyde [MDA], glutathione [GSH], total oxidant status [TOS], total antioxidant status [TAS], oxidative stress [OSI], tumor necrosis factor-α [TNF-α], interleukin-1β [IL-1β], matrix metalloproteinase [MMP]-8, MMP-9, and cathepsin D [CtD] levels) were done on left kidneys. Renal functional status was evaluated with levels of serum creatinine, urea, and cystatin C.

RESULTS

Periodontal bone loss was significantly higher in the Ep and Ob + Ep groups, compared with the C and Ob groups (p < .05). All parameters except TAS and GSH were highest in the Ob + Ep group, and the differences were statistically significant compared with the control group (p < .05). Although the mean TAS and GSH levels were lower in the Ob + Ep group than the other groups, the differences were not statistically significant (p > .05). While the atypical glomeruli score was significantly higher in the Ob + Ep group than in all other groups (p < .05), the acute tubular necrosis and histopathological scores were significantly different only compared with the control group (p < .05).

CONCLUSION

This experimental study showed that the negative effects of the co-existence of periodontitis and obesity on inflammatory stress and apoptotic changes in the kidneys together with the functional parameters were significantly more severe, compared with the presence of one of these diseases alone. TNF-α could have a central role in the periodontitis and obesity-related structural and functional renal changes.

Low-carbohydrate ketogenic diets in body weight control: A recurrent plaguing issue of fad diets?

The most appropriate type of diets to maintain or lose body weight over the medium to long term has been a matter of controversy and debates for more than half a century. Both voluntarily and coercive food restriction, resulting in negative energy and macronutrient balance and hence weight loss, have not been designed to be maintained for the long term. By contrast, when a classical and traditional type of alimentation is consumed in ad lib conditions (e.g., the Mediterranean "diet"), it generally provides an appropriate nutritional density of essential macronutrients and micronutrients; it is hence appropriate for long-term use, and it provides several benefits for health if the compliance of the individuals is maintained over time. In this short review, we focus on four specific aspects: first, the need to agree on a clear definition of what is "low" versus "high" in terms of total carbohydrate intake and total fat intakes, both generally inversely related, in a representative individual with a certain lifestyle and a certain body morphology; second, the importance of discussing the duration over which it could be prescribed, that is, acute versus chronic conditions, focusing on the comparison between the fashion and often ephemeral low-carbohydrate diet (acute) with the well-recognized traditional Mediterranean type of alimentation (chronic), which includes lifestyle changes; third, the particular metabolic characteristics induced by the low-carbohydrate (high fat) diet, namely, the scramble up of ketone bodies production. The recent debate on ketogenic diets concern whether or not, in iso-energetic conditions, low-carbohydrate diets would significantly enhance energy expenditure. This is an issue that is more "academic" than practical, on the ground that the putative difference of 100-150 kcal/day or so (in the recent studies) is not negligible but within the inherent error of the methodology used to track total energy expenditure in free living conditions by the doubly labeled water technique. Fourth, the potential medical risks and shortcomings of ingesting (over the long term) low-carbohydrate ketogenic diets could exacerbate underlying renal dysfunction, consecutive to the joint combination of high-fat, high-protein diets, particularly in individuals with obesity. This particular diet promotes metabolic acidosis and renal hyperfiltration, which ultimately may contribute to a significant reduction in life expectancy in middle-age people.

Bariatric Surgery Is Protective Against Renal Function Decline in Severely Obese Patients in the Long-Term

PURPOSE

This study aims to assess the long-term renal effects of bariatric surgery (BS) in severely obese patients over a follow-up period of up to 11 years.

MATERIALS AND METHODS

In a retrospective cohort study including 102 patients, patients were stratified by eGFR at baseline and divided into three groups: (1) reduced, (2) normal, and (3) increased filtration rate. Adjustments for age- and sex-related decline in eGFR were performed. We used uni- and multivariate regression analysis to identify variables that were thought to determine change in eGFR.

RESULTS

Over a median follow-up of 8.5 years (interquartile range 2.7), eGFR declined from 96.1 ± 20.7 to 84.9 ± 21.0 ml/min (p < 0.001). Among patients with (1), eGFR remained stable (69.1 ± 19.3 ml/min). Among patients with (2), eGFR declined from 99.7 ± 13.3 ml/min to 88.7 ± 19.4 ml/min (p < 0.001). Among patients with (3), eGFR decreased to normal levels (94.2 ± 17.7 ml/min, p < 0.001). Age- and sex-adjusted eGFR increased (6.4 ± 14.4 ml/min; p < 0.05) among patients with reduced filtration rate. Among patients with normal filtration rate, adjusted eGFR remained stable during follow-up (-1.3 ± 15.2 ml/min; n.s.). Among patients with increased filtration rate, adjusted eGFR decreased and remained within the normal range (-13.2 ± 12.2 ml/min; p < 0.001). Change in eGFR showed a negative correlation with eGFR at baseline (B = -0.31; p < 0.001), change in LDL-cholesterol (B = -0.09; p < 0.05), and a negative correlation with treatment requiring hypertension (B = -9.36; p = 0.001).

CONCLUSION

BS is protective against renal function decline in severely obese patients in the long term.

New predictive equations to estimate resting energy expenditure of non-dialysis dependent chronic kidney disease patients

BACKGROUND

Determination of resting energy expenditure (REE) is an important step for the nutritional and medical care of patients with chronic kidney disease (CKD). Methods such as indirect calorimetry or traditional predictive equations are costly or inaccurate to estimate REE of CKD patients. We aimed to develop and validate predictive equations to estimate the REE of non-dialysis dependent-CKD patients.

METHODS

A database comprising REE measured by indirect calorimetry (mREE) of 170 non-dialysis dependent-CKD patients was used to develop (n = 119) and validate (n = 51) a new REE-predictive equation. Fat free mass (FFM) was assessed by anthropometry and by bioelectrical impedance (BIA).

RESULTS

The multiple regression analysis generated three equations: (1) REE (kcal/day) = 854 + 7.4*Weight + 179*Sex - 3.3*Age + 2.1 *eGFR + 26 (if DM) (R² = 0.424); (2) REE (kcal/day) = 678.3 + 14.07*FFM.ant + 54.8*Sex - 2*Age + 2.5*eGFR + 140.7* (if DM) (R² = 0.449); (3) REE (kcal/day) = 668 + 17.1*FFM.BIA - 2.7*Age - 92.7*Sex + 1.3*eGFR - 152.3 (if DM) (R² = 0.45). The estimated REE (eREE) was not different from the mREE (P = 0.181), a high ICC was found and the mean difference between mREE and eREE was not different from zero for the three equations in the validation group. eREE accuracy between 90 and 110% was observed in 55.3%, 62.5% and 61% of the patients for Eqs. (1), (2) and (3), respectively.

CONCLUSION

The equations showed acceptable accuracy for REE prediction making them a valuable tool to support practitioners to provide more reliable energy recommendations for this group of patients.

Potentially obesogenic diets alter metabolic and neurobehavioural parameters in Wistar rats: a comparison between two dietary models

BACKGROUND

Clinical studies related to the obesity pandemic have intensified in recent years, being the animal studies are also considered of great relevance. However, despite the fact that many diets have been reported in the literature to induce obesity in animal models, there is still a gap regarding evidence of the efficacy of these models, considering not only changes in somatic parameters, but also the triggering of comorbidities associated with obesity. In this scenario, the aim of this study was to compare the effectiveness of western and cafeteria diets as obesity-inducing protocols, focusing on the evaluation of metabolic, somatic, oxidative, histological and behavioural parameters of Wistar rats.

METHODS

The rats were fed a control (CON), western (WTD) or cafeteria (CAF) diet for 16 weeks.

RESULTS

The CAF diet caused anxiogenic-like behaviour. Body mass (BMI), Lee and adiposity indices increased in the CAF group. CAF and WTD diets reduced glucose and insulin tolerance, caused dyslipidemia, increased lipid peroxidation and decrease antioxidant capacity in the liver, kidneys and brain. The WTD and CAF groups shows greater IL-6 protein expression in adipose tissue, developed hepatic steatosis and ischaemic neurons, whereas interstitial nephritis was observed only in the CAF group.

CONCLUSION

The CAF diet was most effective in inducing obesity, as shown both by the somatic parameters and by the greater number of obesity-related metabolic and neurobehavioural disorders in the evaluated rats.

Assessment of renal impairment using estimated glomerular filtration rate among type 2 diabetes mellitus patients in North-East Ethiopia: a cross-sectional study

BACKGROUND

Chronic kidney disease (CKD) is the known cause of morbidity and mortality among diabetes mellitus (DM) patients. Targeted screening of renal impairment based on estimated glomerular filtration rate (eGFR) among DM patients has potential benefits in early identification and treatment of CKD. Hence, this study was aimed to estimate the magnitude of renal impairment using eGFR among type 2 DM patients.

METHODS

An institution-based cross-sectional study was conducted from February-1 to April 30/2020 among 422 type 2 DM patients in Northeast Ethiopia. Data were collected by the semi-structured questioner and serum creatinine measurement. The collected data were edited into Epi-data manager version 4.4.1.0, and the analysis was performed by SPSS-25. The Simplified Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology (CKD-EPI), and Cockcroft-Gault (C-G) equations were used to calculate eGFR.

RESULTS

Of all study participants, 82(19.4%), 92(21.8%), and 103(24.4%) had eGFR < 60 ml/min/1.73 m², according to the MDRD, CKD-EPI, and C-G equations, respectively. Female sex, (MDRD:AOR = 4.44, 95%CI:1.97-9.97, CKD-EPI:AOR = 3.17, 95%CI:1.27-6.17, and C-G:AOR = 2.65, 95%CI:1.35-5.21), duration ≥ 10 years (MDRD:AOR = 3.38, 95%CI:1.45-7.92, CKD-EPI:AOR = 3.09, 95%CI:1.07-7.77, and C-G:AOR = 2.92, 95%CI:1.29-6.61), age ˃60 years (MDRD:AOR = 2.29, 95%CI:1.09-4.77, CKD-EPI:AOR = 4.12, 95%CI:1.68-6.78, and C-G: AOR = 3.42, 95%CI:1.77-6.60), hypertension (MDRD:AOR = 3.12, 95%CI:1.51-6.45, CKD-EPI: AOR = 4.21,95%CI:2.07-7.98, and C-G:AOR = 3.99, 95%CI:2.08-7.65), poor glycemic control (MDRD:AOR = 2.82, 95%CI:1.13-7.05, and C-G:AOR = 2.34, 95%CI:1.09-5.04), and body mass index (MDRD:AOR = 1.11, 95%CI:1.01-1.22, and CKD-EPI:AOR = 2.43, 95%CI:1.27-5.76) were significantly associated with renal impairment.

CONCLUSION

Renal impairment was prevalent among type 2 DM patients. Older age, female sex, duration, hypertension, poor glycemic control, and BMI were significantly associated with renal impairment.

Nobiletin ameliorates high-fat diet-induced vascular and renal changes by reducing inflammation with modulating AdipoR1 and TGF-β1 expression in rats

AIMS

We investigate the effect of nobiletin on vascular and renal alterations and possible mechanisms involved in high-fat diet (HFD)-fed rats.

MAIN METHODS

Male Sprague-Dawley rats were fed a HFD with fructose 15% in drinking water for 16 weeks. HFD-fed rats were treated with nobiletin (20 or 40 mg/kg/day) or vehicle for the last 4 weeks.

KEY FINDINGS

HFD-fed rats treated with nobiletin was significantly reduced obesity, hypertension, dyslipidemia and hyperinsulinemia. Nobiletin improved vascular endothelial function, restored creatinine clearance, and reduced plasma urea and creatinine levels, as well as urinary protein excretion. Nobiletin markedly alleviated vascular medial cross-sectional area (CSA) and collagen deposition, glomerular extracellular matrix (ECM) accumulation, and renal fibrosis. Nobiletin significantly elevated plasma adiponectin levels, together with upregulated adiponectin receptor 1 (AdipoR1) and suppressed transforming growth factor-β1 (TGF-β1) expression in kidney. In addition, an increase of plasma tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) was significantly attenuated after nobiletin treatment.

SIGNIFICANCE

Our results suggest that nobiletin attenuates HFD-induced vascular and renal alterations in rats, which is possibly related to the modulation of AdipoR1 and TGF-β1expression, and suppression of inflammation.

Body Composition and Biochemical Markers of Nutrition in Non-dialysis-Dependent Chronic Kidney Disease Patients

The aim of this study was to examine the body composition in stages 3b to 5 of chronic kidney disease. There were 149 patients included in the study, with the mean age of 65.5 ± 16.5 years, body mass index (BMI) of 29.4 ± 5.6 kg/m², and estimated glomerular filtration rate (eGFR) of 23.2 ± 9.3/min/1.73m². They remained with dialysis. Body composition was measured using bioimpedance spectroscopy, and handgrip strength was measured with a hydraulic dynamometer. The main biochemical markers assessed consisted of serum protein, albumin, prealbumin, high-sensitivity C-reactive protein (hsCRP), and interleukin (IL)-6 content. We found that 39% of patients were overweight and 41% were obese. Obesity was more prevalent in stage 3b of chronic kidney disease than in stages 4-5 in women and in patients older than 60 years of age. Thirty-eight percent of the study population were sarcopenic, of whom 20% presented a sarcopenic obesity phenotype. There were significant associations between lean tissue index (LTI) and serum prealbumin content and handgrip strength. Fat tissue index (FTI) was associated and hsCRP, serum protein, body mass index (BMI), waist-hip ratio, and waist-to-height ratio. There were inverse associations between FTI-LTI and LTI-age. We conclude that the prevalence of obesity in non-dialysis-dependent patients with chronic kidney disease is higher than that in the general population. Earlier stages of chronic kidney disease are associated with a higher prevalence of obesity.

Body mass index is an independent predictive factor for kidney function evaluated by glomerular filtration rate in a community-dwelling population

BACKGROUND

The effects of overweight and obesity on kidney function have since been identified and become a subject of increased study and concern. But the association between body mass index (BMI) and estimated glomerular filtration rate (eGFR) is not well characterized. The aim of this study was to determine the relationship between BMI and eGFR.

METHODS

To better understand the relationship between BMI and kidney function, we investigated the association between BMI and eGFR using both the baseline BMI level and the follow-up eGFR level and investigated the relationship between the change in BMI and the change in eGFR in 1447 patients from a 4.8-year prospective study in Beijing, People's Republic of China.

RESULTS

In multiple linear regression analysis, age, antihypertensive treatment, and BMI were negatively associated with the follow-up eGFR levels in all participants (R = -0.622, -0.926, and -0.266, respectively; P < 0.05), or in the elderly (R = -0.883, -1.035, and -0.630, respectively; P < 0.05); sex was found to be associated with the follow-up eGFR levels independently not only in all participants (R = 6.783; P < 0.001), but also in the elderly (R = 3.518; P < 0.05). In addition, the change in eGFR levels was positively related to age, the change in LDL-C, the change in TC, and the change in SBP, but negatively related to the change in BMI and the change in HDL-C (all P < 0.05).

CONCLUSIONS

The present study clearly indicated that BMI is an independent predictive factor for kidney function evaluated by the eGFR level during a median 4.8 years of follow-up in Chinese population.

LEVEL OF EVIDENCE

Level III, prospective cohort study.

Nutritional Aspects in Diabetic CKD Patients on Tertiary Care

Background and objectives: Diabetes is largely prevalent in the chronic kidney disease (CKD) population. Both conditions have metabolic and nutritional abnormalities that affect body composition and the presence of diabetes makes the dietary management of CKD patients more difficult. The aim of this study was to assess peculiar nutritional and functional aspects of diabetic patients in an adult/elderly CKD population, and their predictive significance. Materials and methods: This prospective cohort study included 144 out-patients aged >55 years, affected by stage 3b-4 CKD, on tertiary care clinic; 48 (40 males) were type 2 diabetics and 96 (80 males) were nondiabetics. The two groups have similar age, gender, and residual renal function (30 ± 9 vs. 31 ± 11 mL/min×1.73). All patients underwent a comprehensive nutritional and functional assessment and were followed for 31 ± 14 months. Results: Diabetic CKD patients showed higher waist circumference and fat body mass, lower muscle mass, and lower number of steps per day and average daily METs. Meanwhile, resting energy expenditure (REE), as assessed by indirect calorimetry, and dietary energy intake were similar as well as hand-grip and 6 min walking test. Diabetic patients did not show a greater risk for all-cause mortality and renal death with respect to nondiabetics. Middle arm muscle circumference, phase angle, serum cholesterol, and serum albumin were negatively related to the risk of mortality and renal death after adjustment for eGFR. Conclusions: CKD diabetic patients differed from nondiabetics for a greater fat mass, lower muscle mass, and lower physical activity levels. This occurred at the same REE and dietary energy intake. The outcome of diabetic or nondiabetic CKD patients on tertiary care management was similar in terms of risk for mortality or renal death. Given the same residual renal function, low levels of muscle mass, phase angle, serum albumin, and cholesterol were predictive of poor outcome. Overall, a malnutrition phenotype represents a major predictor of poor outcome in diabetic and nondiabetic CKD patients.

Kidney osteoclast factors and matrix metalloproteinase expression in a mice model of diet-induced obesity and diabetes

The role of RANKL/RANK/OPG system on bone remodeling is well known, and there is evidence that it is also important to cardiovascular and kidney pathology, although the underlying mechanisms are not elucidated so far. Thus, we investigated in a mice model of diet-induced obesity and diabetes if renal histopathological changes are associated with the expression of RANKL/RANK/OPG system and matrix metalloproteinases (MMPs). Three months old C57BL/6 mice were fed with control (C) AIN93 M diet or high-fat high sucrose (HFHS) diets for 21 weeks (CEUA/UFF #647/15). The two groups presented weight gain, but it was higher in the HFHS group compared to the C group (+35%, P = 0.0001). The HFHS group also had increased epididymal, inguinal and retroperitoneal fat pad weight (+121%, P = 0.0006; +287%, P = 0.0007 and; +286%, P < 0.0001, respectively), and hyperglycemia (+43%, P = 0.02). The kidney of some HFHS fed mice displayed mononuclear inflammatory cell infiltrate (40%), perivascular fibrosis (20%), and focal tubule mineralization (20%). Glomeruli hypertrophy was not detected. Unexpectedly, OPG, RANK, MMP-2, and MMP-9 expression was not altered in HFHS groups (Western blot analysis). In conclusion, the expression of RANKL/RANK/OPG system proteins and MMPs was not influenced by diet-induced obesity and diabetes in the kidney of male C57BL/6 mice, although some adverse histopathological remodeling is noticed in the renal tissue.

Prebiotic prevents impaired kidney and renal Oat3 functions in obese rats

Obesity is health issue worldwide, which can lead to kidney dysfunction. Prebiotics are non-digestible foods that have beneficial effects on health. This study aimed to investigate the effects of xylooligosaccharide (XOS) on renal function, renal organic anion transporter 3 (Oat3) and the mechanisms involved. High-fat diet was provided for 12 weeks in male Wistar rats. After that, the rats were divided into normal diet (ND); normal diet treated with XOS (NDX); high-fat diet (HF) and high-fat diet treated with XOS (HFX). XOS was given daily at a dose of 1000 mg for 12 weeks. At week 24, HF rats showed a significant increase in obesity and insulin resistance associated with podocyte injury, increased microalbuminuria, decreased creatinine clearance and impaired Oat3 function. These alterations were improved by XOS supplementation. Renal MDA level and the expression of AT1R, NOX4, p67^phox, 4-HNE, phosphorylated PKCα and ERK1/2 were significantly decreased after XOS treatment. In addition, Nrf2-Keap1 pathway, SOD2 and GCLC expression as well as renal apoptosis were also significantly reduced by XOS. These data suggest that XOS could indirectly restore renal function and Oat3 function via the reduction of oxidative stress and apoptosis through the modulating of AT1R-PKCα-NOXs activation in obese insulin-resistant rats. These attenuations were instigated by the improvement of obesity, hyperlipidemia and insulin resistance.

Obesity and chronic kidney disease: A population-based study among South Koreans

Obesity and chronic kidney disease (CKD) are major global health problems. There are very little data concerning the prevalence and its associated factors of obesity in non-dialyzed patients who have different stages of CKD. Therefore, in this study, we examined the prevalence of obesity and its associated factors according to the stages of CKD. We used nationwide representative data from the Korean National Health and Nutrition Examination Survey, which was conducted over a 7-year period from 2008 to 2014 by the Korea Centers for Disease Control and Prevention. The results indicated that: (1) general obesity and abdominal obesity were more prevalent in patients with CKD compared to those without CKD; (2) the prevalence of general obesity and abdominal obesity was highest in stage 2 CKD; (3) stages 3a and 3b were the factors associated with general obesity, and stage 3a was significantly associated with abdominal obesity; (4) the association between general obesity/abdominal obesity and CKD disappeared in people with advanced stage 4/5 CKD; and (5) the presence of comorbidities contributed to the development of both general obesity and abdominal obesity. The findings of this study might support the idea that weight loss is a good potential intervention for the prevention of disease progression in moderate CKD (stage 3), but not severe CKD (stage 4/5).

Association between syndecan-1 and renal function in adolescents with excess weight: evidence of subclinical kidney disease and endothelial dysfunction

Excess weight (overweight and obesity) is associated with kidney and cardiovascular disease. The aim of this study was to investigate the association between syndecan-1 and renal function among adolescents with excess weight. A total of 56 students from a public school at Fortaleza, CE, Brazil, were investigated. The adolescents were submitted to anthropometric evaluation, including weight, height, blood pressure and body mass index. Blood and urine samples were collected for the determination of serum lipids (total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, triglycerides), and the endothelial injury biomarker syndecan-1. Participants' mean age was 16±1 years (range 14-19 years), and 68% were females. Overweight was observed in 4 cases (7.1%) and obesity in 7 (12.5%). Changes in serum lipid levels were more frequent in the overweight group. A positive correlation between syndecan-1 and serum creatinine (r=0.5, P=0.001) and triglycerides (r=0.37, P=0.004), and a negative correlation with glomerular filtration rate (r=-0.33, P=0.02) were found. These findings suggest that adolescents with excess weight present incipient changes at the cellular level that make them more vulnerable to the development of kidney and cardiovascular diseases.

Obesity markers associated to albuminuria in a primary care center in Lima, Perú

OBJECTIVE

To evaluate the association between three obesity markers, body mass index (BMI), abdominal circumference (AC), waist to height ratio (WHtR), and albuminuria in adults seen in a primary health care center specialized in chronic diseases in Lima, Perú.

METHODS

A cross-sectional, descriptive, retrospective study in adults who attended a primary health care center specialized in chronic diseases in 2011. Patients were divided into four categories: healthy subjects and patients with high blood pressure, with type 2 diabetes mellitus (T2DM), and with both diseases (HBP+T2DM). The main outcome was presence of albuminuria, defined as urine albumin levels higher than 30mg/day. Exposure variables included the following obesity markers: body mass index (BMI), waist-to-height ratio (WHtR), and abdominal circumference (AC). Other covariates considered included sex and age. Crude and adjusted Poisson regressions were performed to estimate prevalence ratios (PRs) and their respective 95% confidence intervals (95% CIs). Areas under the curve were calculated for each indicator, stratified by sex.

RESULTS

Data from 1,214 patients, 41% of them male, were analyzed, and albuminuria was found in 14.2%. Albuminuria was found to be associated to AC and WHtR, but not to BMI. All three parameters assessed had similar areas under the curve. The optimum cut-off points found for BMI and AC in females were higher than conventional (32.7kg/m² and 93cm respectively), while the values in males were lower than conventional (27.9kg/m² and 100cm respectively). For WHtR, however, the optimum cut-off point was higher in both sexes. The higher index in females was for BMI, followed by AC and WHtR. In males, the higher index was for WHtR, followed by AC and BMI.

CONCLUSIONS

AC and WHtR were found to be directly associated to albuminuria, while BMI was not associated to albuminuria. Areas under the curve were similar for all three markers. The optimum cut-off points for BMI and AC were higher than the conventional ones in females and lower in males.

The Kidney: An Organ in the Front Line of Oxidative Stress-Associated Pathologies

Both acute kidney injury (AKI) and chronic kidney disease (CKD) are major causes of renal failure in humans and are associated with high incidences of morbidity and mortality rates. AKI and CKD are closely interconnected, and fueled by the obesity and diabetes epidemic, their prevalence is alarmingly increasing to the point that it currently represents a major heath issue worldwide. The kidney is an organ that is particularly sensitive to redox imbalance, resulting in excessive production of reactive oxygen species. Oxidative stress is viewed as a critical pathogenic factor implicated in the initiation, development, and progression of most renal diseases. This Forum discusses the redox-dependent factors and mechanisms accounting for the perturbation of renal function and circulation in the context of the major kidney pathologies linked to hypertension, diabetes, and cancer. Antioxid. Redox Signal. 25, 639-641.

Delayed treatment with fenofibrate protects against high-fat diet-induced kidney injury in mice: the possible role of AMPK autophagy

Fenofibrate activates not only peroxisome proliferator-activated receptor-α (PPARα) but also adenosine monophosphate-activated protein kinase (AMPK). AMPK-mediated cellular responses protect kidney from high-fat diet (HFD)-induced injury, and autophagy resulting from AMPK activation has been regarded as a stress-response mechanism. Thus the present study examined the role of AMPK and autophagy in the renotherapeutic effects of fenofibrate. C57BL/6J mice were divided into three groups: normal diet (ND), HFD, and HFD + fenofibrate (HFD + FF). Fenofibrate was administered 4 wk after the initiation of the HFD when renal injury was initiated. Mouse proximal tubule cells (mProx24) were used to clarify the role of AMPK. Feeding mice with HFD for 12 wk induced insulin resistance and kidney injury such as albuminuria, glomerulosclerosis, tubular injury, and inflammation, which were effectively inhibited by fenofibrate. In addition, fenofibrate treatment resulted in the activation of renal AMPK, upregulation of fatty acid oxidation (FAO) enzymes and antioxidants, and induction of autophagy in the HFD mice. In mProx24 cells, fenofibrate activated AMPK in a concentration-dependent manner, upregulated FAO enzymes and antioxidants, and induced autophagy, all of which were inhibited by treatment of compound C, an AMPK inhibitor. Fenofibrate-induced autophagy was also significantly blocked by AMPKα1 siRNA but not by PPARα siRNA. Collectively, these results demonstrate that delayed treatment with fenofibrate has a therapeutic effect on HFD-induced kidney injury, at least in part, through the activation of AMPK and induction of subsequent downstream effectors: autophagy, FAO enzymes, and antioxidants.

Glycated haemoglobin A1c is associated with low-grade albuminuria in Chinese adults

BACKGROUND AND OBJECTIVE

Diabetes is a strong risk factor for cardiovascular diseases, whereas few studies have investigated simultaneously the associations of glycated haemoglobin A1c (HbA1c), fasting blood glucose (fasting plasma glucose (FPG)) and 2 h postload blood glucose (2 h PG) with low-grade albuminuria, which is an earlier marker of cardiovascular diseases in the general population. Our study aimed to investigate and compare associations of HbA1c, FPG, and 2 h PG levels with risks of low-grade albuminuria in the middle-aged and elderly Chinese.

DESIGN AND METHODS

This was a cross-sectional study involving 9188 participants aged 40 years or older. All participants underwent a standard 75 g oral glucose tolerance test. Low-grade albuminuria was defined as the highest quartile of urinary albumin-to-creatinine ratio (ACR) (>6.10 mg/g in males and >8.76 mg/g in females) in respondents without microalbuminuria or macroalbuminuria.

RESULTS

HbA1c, FPG and 2 h PG were all significantly correlated with urinary ACR after adjustment for confounders (all p values <0.0001). After adjustment for HbA1c, the relationships of FPG and 2 h PG with ACR reduced to null. HbA1c levels were still significantly associated with ACR after further adjustment for FPG and 2 h PG. Multiple logistic regression showed that risks of low-grade albuminuria were positively associated with HbA1c levels in a dose-response manner. Compared with participants with HbA1c ≤ 37 mmol/mol (5.5%), ORs (95% CIs) for low-grade albuminuria were 1.05 (0.94 to 1.18), 1.25 (1.04 to 1.50), 1.40 (1.04 to 1.90) and 2.21 (1.61 to 3.03) for HbA1c categories of 38-42 mmol/mol (5.6-6.0%), 43-48 mmol/mol (6.1-6.5%), 49-53 mmol/mol (6.6-7.0%), and >53 mmol/mol (7.0%), respectively (p for trend <0.0001).

CONCLUSIONS

HbA1c, but not FPG or 2 h PG, was independently associated with an increased risk of low-grade albuminuria in the middle-aged and elderly Chinese.

Renal protective effects of induction of haem oxygenase-1 combined with increased adiponectin on the glomerular vascular endothelial growth factor-nitric oxide axis in obese rats

What is the central question of this study? This study aimed to investigate whether induction of haem oxygenase-1 (HO-1) can protect the kidneys of obese rats by regulating the glomerular vascular endothelial growth factor-nitric oxide (VEGF-NO) axis by increasing the adiponectin concentrations. What is the main finding and its importance? Induction of HO-1 reduces the degree of microalbuminuria and has renal protective effects by improving endothelial function and regulating the uncoupled glomerular VEGF-NO axis in diet-induced obese rats. The mechanism may be related to increased activation of the HO-1-adiponectin axis. The glomerular vascular endothelial growth factor-nitric oxide (VEGF-NO) axis plays a critical role in maintenance of normal kidney function in obesity. Induction of haem oxygenase-1 (HO-1) may result in a parallel increase in adiponectin secretion. The aim of this study was to investigate whether induction of HO-1 could protect the kidneys of obese rats by regulating the glomerular VEGF-NO axis by increasing adiponectin levels. Rats received high-fat diets and were injected with either cobalt protoporphyrin to induce HO-1 or stannous protoporphyrin to inhibit HO-1. Blood and urine samples were collected. Endothelial function was determined by measuring the endothelium-dependent vasodilatation of the aorta. Renal tissues were collected for CD34 immunohistochemistry. The glomerular VEGF-NO axis and the AMP kinase-phosphoinositide 3-kinase (PI3K)/Akt-endothelial nitric oxide synthase pathway were measured. Induction of HO-1 by cobalt protoporphyrin decreased microalbuminuria, plasma free fatty acids, serum high-sensitivity C-reactive protein and malondialdehyde levels and increased serum adiponectin levels compared with the untreated obese rats. Severe impairment of endothelium-dependent vasodilatation was observed in the obese rats, which was improved to some extent by HO-1 induction. Induction of HO-1 reduced glomerular CD34 expression and production of reactive oxygen species in obese rats. Obese rats showed increased glomerular VEGF expression and reduced NO levels. This uncoupling of the glomerular VEGF-NO axis was improved to some extent by induction of HO-1, with enhancement of p-AMP kinase, p-Akt and phospho-endothelial nitric oxide synthase in obese rats. These results indicate that induction of HO-1 with cobalt protoporphyrin reduces the degree of microalbuminuria and has renal protective effects by improving endothelial dysfunction and regulating the glomerular VEGF-NO axis in diet-induced obese rats by increasing adiponectin levels.

Chronic kidney disease among overweight and obesity with and without metabolic syndrome in an urban Chinese cohort

BACKGROUND

It is widely accepted that metabolic syndrome is associated with an increased risk of chronic kidney disease (CKD). To investigate whether coexisting metabolic syndrome is a necessary condition for CKD in overweight and obese.

METHODS

A cohort study of 6852 Chinese individuals from August 2007 to December 2012. Examinations included a questionnaire, physical measurements, and blood sampling. Hazard ratios for incident CKD were estimated according to combinations of BMI category and absence or presence of metabolic syndrome.

RESULTS

For CKD, multivariable adjusted hazard ratios vs. normal weight individuals without metabolic syndrome were 1.31 (95% CI, 0.89-1.92) in overweight and 2.39 (95% CI, 1.27-4.52) in obese without metabolic syndrome and 1.54 (95% CI, 1.18-3.95) in normal weight, 2.06 (95% CI, 1.27-3.36) in overweight, and 2.77 (95% CI, 1.42-4.31) in obese with metabolic syndrome. There were no interactions between BMI and absence or presence of metabolic syndrome on risk of CKD when BMI was categorized (normal weight, overweight, obese) (P = 0.17). Among individuals both with and without metabolic syndrome there were increasing cumulative incidences of CKD from normal weight through overweight to obese individuals (log-rank trend P = 0.04 to P < 0.001). Although the multivariable adjusted hazard ratio for CKD in individuals with vs. without metabolic syndrome was 1.82 (95% CI, 1.20-2.78) within overweight and obese individuals (log-rank P = 0.005), only 26.1% of the increased risk observed for BMI is explained by metabolic syndrome.

CONCLUSIONS

These findings suggest overweight and obesity are risk factors for CKD regardless of the presence or absence of metabolic syndrome.

Association of Demographic and Socioeconomic Factors With Risk Factors for Chronic Kidney Disease

Objectives:

The goal of this study was to examine the association of various demographic and socioeconomic factors with risk factors for chronic kidney disease (CKD).

Methods:

We used nationally representative pooled data from the Korea National Health and Nutrition Examination Survey (KNHANES), 2007–2013. We estimated the glomerular filtration rate (GFR) using the Modification of Diet in Renal Disease equation. We defined CKD as a GFR <60 mL/min/1.73 m², and 1304 of the 45 208 individuals included in the KNHANES were found to have CKD by this definition. The outcome variable was whether individual subjects adhered to the CKD prevention and management guidelines recommended by the Korea Centers for Disease Control and Prevention. The guidelines suggest that individuals maintain a normal weight, abstain from alcohol consumption and smoking, manage diabetes and hypertension, and engage in regular exercise in order to prevent and manage CKD.

Results:

This study found that individuals with CKD were more likely to be obese and have hypertension or diabetes than individuals without CKD. In particular, male and less-educated CKD patients were less likely to adhere to the guidelines.

Conclusions:

Although the prevalence of CKD, as indicated by the KNHANES data, decreased from 2007 to 2013, the prevalence of most risk factors associated with CKD fluctuated over the same time period. Since a variety of demographic and socioeconomic factors are related to the successful implementation of guidelines for preventing and managing CKD, individually tailored prevention activities should be developed.

Effect of pentoxifylline on microalbuminuria in diabetic patients: a randomized controlled trial

Background. Pentoxifylline is a nonspecific phosphodiesterase inhibitor with anti-inflammatory properties. Human studies have proved its antiproteinuric effect in patients with glomerular diseases, but this study was designed to assess the effects of add-on pentoxifylline to available treatment on reduction of microalbuminuria in diabetic patients without glomerular diseases. Methods. In a double-blind placebo-controlled, randomized study we evaluated the influence of pentoxifylline on microalbuminuria in type 2 diabetic patients. 40 diabetic patients with estimated glomerular filtration rate (eGFR) of more than 60 mL/min/1.73 m(2) in eight weeks and microalbuminuria were randomized to two groups which will receive pentoxifylline 1200 mg/day or placebo added to regular medications for 6 months. albuminuria; eGFR was evaluated at three- and six-month follow-up period. Results. Baseline characteristics were similar between the two groups. At six months, the mean estimated GFR and albuminuria were not different between two groups at 3- and 6-month follow-up. Trend of albumin to creatinine ratio, systolic and diastolic blood pressure, and eGFR in both groups were decreased, but no significant differences were noted between two groups (P value > 0.05). Conclusion. Pentoxifylline has not a significant additive antimicroalbuminuric effect compared with placebo in patients with type 2 diabetes with early stage of kidney disease; however, further clinical investigations are necessary to be done.

Contextual poverty, nutrition, and chronic kidney disease

Nutrition plays an important role in CKD outcomes. One of the strongest factors that affects nutrition is socioeconomic status as evidenced by the large body of epidemiologic data showing that income and education are directly associated with diet quality. Apart from individual-level markers of socioeconomic status such as income and education, contextual factors such as availability of and transportation to food outlets that provide healthy food options and the density of fast-food restaurants within particular regions markedly affect the ability of individuals to comply with nutrition recommendations. This is particularly true for nutrition guidelines most specific to individuals with CKD such as the consumption of protein, saturated fat, sodium, and phosphorus, all of which have been shown to affect CKD health and are influenced by the availability of healthy food options within individual neighborhood food environments. Because of the strong association of contextual poverty with the diet quality, any serious attempt to improve the diet of CKD patients must include a discussion of the environmental barriers that each individual faces in trying to access healthy foods, and health care providers should take account of these barriers when tailoring specific recommendations.

Obesity in kidney disease: A heavyweight opponent

Obesity is an important worldwide challenge that must be faced in most developed and developing countries because of unhealthy nutritional habits. The consequences of obesity and being overweight are observed in different organs, but the kidney is one of the most affected. Excess adipose tissue causes hemodynamic alterations in the kidney that can result in renal disease. However, obesity is also commonly associated with other comorbidities such as chronic inflammation, hypertension and diabetes. This association of several aggravating factors is still a matter of concern in clinical and basic research because the pathophysiologic mechanisms surrounding chronic kidney disease development in obese patients remain unclear. This review will discuss the consequences of obesity in the context of renal injury.

Metabolic syndrome and chronic kidney disease in an adult Korean population: results from the Korean National Health Screening

Background

This study was aimed to examine the prevalence of metabolic syndrome (MS) and chronic kidney disease (CKD), and the association between MS and its components with CKD in Korea.

Methods

We excluded diabetes to appreciate the real impact of MS and performed a cross-sectional study using the general health screening data of 10,253,085 (48.86±13.83 years, men 56.18%) participants (age, ≥20 years) from the Korean National Health Screening 2011. CKD was defined as dipstick proteinuria ≥1 or an estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m².

Results

The prevalence of CKD was 6.15% (men, 5.37%; women, 7.15%). Further, 22.25% study population had MS (abdominal obesity, 27.98%; hypertriglyceridemia, 30.09%; low high-density cholesterol levels, 19.74%; high blood pressure, 43.45%; and high fasting glucose levels, 30.44%). Multivariate-adjusted analysis indicated that proteinuria risk increased in participants with MS (odds ratio [OR] 1.884, 95% confidence interval [CI] 1.867–1.902, P<0.001). The presence of MS was associated with eGFR<60 mL/min/1.73 m² (OR 1.364, 95% CI 1.355–1.373, P<0.001). MS individual components were also associated with an increased CKD risk. The strength of association between MS and the development of CKD increase as the number of components increased from 1 to 5. In sub-analysis by men and women, MS and its each components were a significant determinant for CKD.

Conclusions

MS and its individual components can predict the risk of prevalent CKD for men and women.

Perirenal fat associated with microalbuminuria in obese rats

PURPOSE

To determine whether perirenal fat is associated with increased urinary albumin excretion and whether perirenal fat affects renal vascular endothelial function in obese rats.

METHODS

Wistar rats were randomly divided into normal and obesity group, which were fed with normal and high-fat diet, respectively. Blood and urine samples were collected. Endothelial function of the aorta was determined by measuring endothelium-dependent vasodilatation. Renal tissues were collected for CD34 immunohistochemistry and free fatty acids (FFA) measurement. Levels of glomerular nitric oxide (NO) and reactive oxygen species (ROS) were measured.

RESULTS

After 24 weeks, plasma FFA, high-sensitivity C-reactive protein, and malondialdehyde levels were elevated and were significantly higher in renal venous blood than in jugular venous blood in obese rats. Urinary albumin/creatinine ratio, glomerular CD34 expression, glomerular ROS level, and renal cortex FFA levels were higher in obese rats. Endothelial dysfunction was more severe in the infra-renal aorta than in the thoracic aorta in obese rats. Plasma adiponectin and glomerular NO levels were lower in obese rats.

CONCLUSION

Perirenal fat is associated with increased urinary albumin excretion in obese rats. The mechanism may be renal vascular endothelial dysfunction caused by increased oxidative stress and activation of inflammatory molecular pathways due to elevated FFA and low adiponectin levels.

Suramin: a potential therapy for diabetic nephropathy

Objective

To determine whether delayed administration of a single dose of suramin, a drug that has been used extensively in humans to treat trypanosomiasis, attenuates renal injury in a leptin receptor deficient C57BLKS/J db/db type 2 diabetic nephropathy (T2DN) mouse model.

Research Design and Methods

Groups of female non-diabetic (control) db/m and diabetic db/db mice of 8 and 16 weeks of age, respectively, were treated with suramin (10 mg/kg) or saline i.v. All animals were euthanized one week later. Measurements in mice 1 week following treatment included the following: body weight; blood glucose; urinary protein excretion; pathological lesions in glomeruli and proximal tubules; changes in protein expression of pro-inflammatory transcription factor nuclear factor κB (NF-κB) and intracellular adhesion molecule-1 (ICAM-1), profibrotic transforming growth factor-β1 (TGF-β1), phospho-SMAD-3 and alpha-smooth muscle actin (α-SMA); and immunohistochemical analysis of leukocyte infiltration and collagen 1A2 (COL1A2) deposition.

Results

Immunoblot analysis revealed increased NF-κB, ICAM-1, TGF-β1, phospho-SMAD-3, and α-SMA proteins in both 9 and 17 week db/db mice as compared to db/m control mice. Immunohistochemical analysis revealed moderate leukocyte infiltration and collagen 1A2 (COL1A2) deposition in 9 week db/db mice that was increased in the 17 week db/db mice. Importantly, suramin significantly decreased expression of all these markers in 9 week db/db mice and partially decreased in 17 week db/db mice without altering body weight, blood glucose or urinary protein excretion. There was no difference in creatinine clearance between 9 week db/m and db/db mice ± suramin. Importantly, in the 17 week db/db mice suramin intervention reversed the impaired creatinine clearance and overt histological damage.

Conclusions

Delayed administration of a single dose of suramin in a model of T2DN attenuated inflammation and fibrosis as well as improved renal function, supporting the use of suramin in T2DN.

Correlation of ultrasonographic measurement of intrarenal arterial resistance index with microalbuminuria in nonhypertensive, nondiabetic obese patients

PURPOSE

To determine whether intrarenal arterial resistance index (RI) value is related to increased urinary albumin excretion and whether RI value is an independent good indicator to evaluate early renal damage in nonhypertensive, nondiabetic obese subjects.

METHODS

Sixty-four nonhypertensive, nondiabetic obese patients (OB) and 35 age- and sex-matched normal healthy subjects were involved in this study. Clinical characteristics and blood biochemistry of all the subjects were measured. Urinary albumin/creatinine ratio (ACR) and sonographic evaluation of renal blood flow were determined.

RESULTS

ACR and interlobar arterial RI were significantly higher in obese patients than those of normal healthy subjects. Interlobar arterial RI value was higher in patients with microalbuminuria than those with normoalbuminuria. Correlation analysis showed interlobar artery RI value had a positive correlation with ACR (r = 0.615, p < 0.01) and plasma free fatty acids (FFAs, r = 0.407, p < 0.01). ACR had a positive correlation with BMI (r = 0.380, p < 0.01), waist circumference (r = 0.414, p < 0.01), plasma FFAs (r = 0.537, p < 0.01). Multivariate regression analyses showed that ACR was best predicted by interlobar artery RI value even when body mass index, waist circumference, FFAs, and high-sensitive C reaction protein were added in the statistical analysis.

CONCLUSIONS

Interlobar arterial RI may be an independent predictor of microalbuminuria in nonhypertensive, nondiabetic obese patients, and interlobar arterial RI could be a useful tool for assessment early renal damage in obese patients.

Telmisartan attenuates diabetic nephropathy by suppressing oxidative stress in db/db mice

BACKGROUND/AIMS

Telmisartan, an angiotensin II type 1 receptor blocker, is widely used to treat hypertension and kidney diseases, including diabetic nephropathy, because of its renoprotective effects. However, the mechanism by which telmisartan prevents proteinuria and renal dysfunction in diabetic nephropathy is still unclear. In this study, we examined the effects of telmisartan against diabetic nephropathy in db/db mice.

METHODS

Telmisartan was administered at a dose of 5 mg/kg/day for 3 weeks to db/db (diabetic) and db/m (control) mice. Urinary albumin excretion, renal histology, and the gene expression of oxidative stress and inflammatory markers in renal tissue were determined. To evaluate the effects of telmisartan on reactive oxygen species (ROS) production, superoxide was detected by dihydroethidium (DHE) staining in vivo and in vitro.

RESULTS

Telmisartan reduced albuminuria, mesangial matrix expansion, macrophage infiltration, and the expression of ROS markers (NADPH oxidase 4- and 8-hydroxydeoxyguanosine) and inflammatory cytokines (monocyte chemoattractant protein-1, osteopontin, and transforming growth factor-β) in the kidney. DHE staining showed that telmisartan decreased ROS generation in the kidney and in cultured mesangial and proximal tubular epithelial cells.

CONCLUSIONS

Taken together, these findings indicate that telmisartan protects against diabetic nephropathy by reducing diabetes-induced oxidative stress.

Metabolic syndrome and other cardiovascular risk factors associated with the progression of IgA nephropathy

Background

The metabolic syndrome is associated with modest but independent and additive risk of new onset chronic kidney disease (CKD) in several studies. The purpose of our study was to determine whether metabolic syndrome and other cardiovascular risk factors (hyperuricaemia and smoking) are associated with the progression of IgA nephropathy (IgAN).

Methods

Two hundred and twenty three IgAN patients (107 with and 116 without metabolic syndrome) were examined. The primary renal end point was doubling of serum creatinine; secondary end points were reaching eGFR of ≤ 60 ml/min/1,73m² or eGFR of ≤30 ml/min/1.73 m², and end-stage renal disease, ESRD (the composite of serum creatinine ≥500 μmol/l, initiation of dialysis treatment or transplantation). The association of metabolic syndrome with renal end points was examined using the Kaplan-Meier method and Cox models.

Results

Metabolic syndrome established at the diagnosis or during follow-up of IgAN patients was significantly associated with the primary renal end point (unadjusted hazard ratio of doubling of serum creatinine, 95% confidence interval: 1.96 (1.17–1.33, p = 0.011). The association remained significant after adjustment for confounders: 1.70 (1.02–3.83, p = 0.040). Results were similar for secondary end points except ESRD which was not associated with the presence of metabolic syndrome. Hyperuricaemia and smoking were independent risk factors of progression. Survival curves stratified on metabolic syndrome status showed significant differences for the end points (p = 0.017–0.001) except for ESRD.

Conclusions

Early diagnosis and treatment of metabolic syndrome, hyperuricaemia and smoking may be an additional cost-effective strategy for preventing the progression of IgAN.