Obesity, metabolic health, and the risk of end-stage renal disease

Kidney consequences of obesity

Herein, we review the devastating consequences of the worldwide obesity epidemic on kidney health and outcomes. We submit that the obesity epidemic is the most pressing public health crisis facing the nephrology community today. A historical approach has been undertaken, wherein major breakthroughs in the recognition and understanding of obesity-related kidney disease (ORKD) are highlighted. We begin with a description of the worldwide obesity epidemic followed by an account of the discovery and characterization of ORKD. A detailed summary of the pathophysiology of ORKD disease is presented, wherein we set forth the following two propositions: first, ORKD is due to a maladaptive response to caloric surplus; and second, this maladaptive response causes kidney damage via hemodynamic (hyperfiltration), hormonal (adipokine dysregulation), and lipotoxic pathways. Each of these pathways is described, with particular emphasis on the relatively recent discovery that the final stage of cellular injury in ORKD is mitochondrial oxidative damage. The prevention and treatment of ORKD are then discussed, including environmental, behavioral, pharmacologic, and surgical options. Finally, we conclude with suggestions for future research to improve early recognition and treatment of ORKD.

Insights into renal damage in hyperuricemia: Focus on renal protection (Review)

The incidence of hyperuricemia has increased recently, posing a serious threat to public health. Hyperuricemia is associated with an increased risk of gout, chronic kidney disease (CKD), obesity, metabolic syndrome, type 2 diabetes mellitus, hypertension, hypertriglyceridaemia, metabolic dysfunction‑associated steatotic liver disease, acute kidney injury, coronary heart disease and cardiovascular disease (CVD). These diseases are commonly accompanied by varying degrees of kidney damage. A number of randomized controlled clinical trials have investigated the effectiveness of UA‑lowering therapies in preventing kidney disease progression. The present review provided fundamental insights into the pathogenesis, principles and therapeutic approaches for managing hyperuricemia in patients with aforementioned diseases and assesses the effect of uric acid‑lowering therapy on diabetic nephropathy, systemic lupus erythematosus, CKD, CVD and obesity progression.

Obesity, Metabolic Health, and Diabetic Complications in People With Type 1 Diabetes

AIM

The concept of metabolically healthy obesity (MHO) has not been studied in type 1 diabetes (T1D). By analysing datasets from the DCCT/EDIC study, we compared the development of diabetic complications by obesity and metabolic health over 30 years of follow up.

MATERIALS AND METHODS

Insulin resistance was calculated by estimated glucose disposal rate (eGDR). The participants (n = 1127) were then divided into four groups based on time-weighted mean body mass index and mean eGDR: metabolically healthy non-obesity (MHN, n = 874), metabolically unhealthy non-obesity (MUN, n = 66), MHO (n = 146) and metabolically unhealthy obesity (MUO, n = 41). Diabetic complications and cardiovascular events were compared across the four groups.

RESULTS

MUO and MUN groups had significantly higher risk for peripheral neuropathy (p = 0.001 in MUO and p < 0.001 in MUN vs. MHN), cardiac autonomic neuropathy (p < 0.001 in both MUO and MUN vs. MHN), retinopathy (p = 0.001 in MUO and p < 0.001 in MUN vs. MHN) and microalbuminuria (p < 0.001 in both MUO and MUN vs. MHN) than MHN group. Moreover, MUO and MUN groups had significantly higher risks (HR [95%CI]) in any cardiovascular events (2.78 [1.51-5.11] and 1.88 [1.05-3.36]) and major atherosclerotic cardiovascular events (2.72 [1.16-6.37] and 2.31 [1.05-5.10]) compared to MHN group. However, the risk of these complications and cardiovascular events (except peripheral neuropathy and cardiac autonomic neuropathy) in MHO group was not different from that in MHN group.

CONCLUSIONS

This study highlights the importance of metabolic health represented by insulin resistance in the development of diabetic complications and cardiovascular events in T1D beyond their weight status.

Approaches to patients with obesity and CKD: focus on nutrition and surgery

Obesity is recognized as a public health challenge. During the last three decades, the global age-standardized prevalence increased from 8.8% to 18.5% in women and from 4.8% to 14.0% in men, with an absolute current number of 878 million obese subjects. Obesity significantly increases per se the risk of developing disability and chronic diseases, including chronic kidney disease (CKD). Specifically, obesity acts as a major, modifiable cause of CKD onset and progression toward kidney failure; as such, it is considered by the International Society of Nephrology a major health priority. This review analyses the effectiveness, safety and practicability of non-pharmacological anti-obesity interventions in CKD as the different patient phenotypes that may take advantage of personalized approaches.

Analysis of the impact of obesity on the prognosis of IgA nephropathy according to renal function and sex

BACKGROUND

Few studies have observed the direct effect of obesity on renal prognoses in immunoglobulin A nephropathy (IgAN) or separately evaluated its effects according to sex. We aimed to evaluate the direct and indirect effects of obesity on the renal outcomes of IgAN and observe these effects separately according to renal function and sex.

METHODS

We extracted patients with body mass index (BMI) descriptions from a multicenter retrospective cohort analysis in Japan, and excluded those with < 30 days of follow-up, diabetes mellitus, and steroid treatment. Patients were divided into normal (n = 720; 18.5 ≤ BMI < 25) and obese (n = 212; BMI ≥ 25) groups, which were then compared. The endpoints were a 1.5-fold increase in serum creatinine levels and the initiation of renal replacement therapy.

RESULTS

The obese group was older, included more males, and was more likely have hypertension, dyslipidemia, proteinuria, tubular atrophy, and lower renal function than the normal group. Patients with an eGFR < 60 mL/min/1.73 m2 had well-matched characteristics between the groups; however, hypertension, low high-density lipoprotein cholesterol, and hypertriglyceridemia were more common in the obese group. Obesity contributed to tubular atrophy, even when adjusted for renal function. In addition, it contributed to proteinuria only in females. However, obesity itself was not a significant prognostic factor.

CONCLUSIONS

Although no independent effect on renal prognosis was observed during the study period, the obese group had more risk factors for IgAN progression and obesity contributed to tubular atrophy and female proteinuria. Our results suggest that separately analyzing the prognostic effect of obesity according to sex is important.

The hidden impact: the rate of nicotine metabolism and kidney health

Objectives

The effects of nicotine metabolism on the kidneys of healthy individuals have not been determined. The nicotine metabolite ratio (NMR) indicates the rate of nicotine metabolism and is linked to smoking behaviors and responses to tobacco treatments. We conducted this study in order to investigated the relationship between nicotine metabolite ratio (NMR) and kidney function.

Methods

An analysis of cross-sectional data of adults was conducted using a population survey dataset (National Health and Nutrition Examination Survey Data 2013/2018 of the United States). A weighted multivariate regression analysis was conducted to estimate the correlation between NMR and kidney function. Furthermore, we apply fitting smooth curves to make the relationship between NMR and estimated glomerular filtration rate (eGFR) more visualized.

Results

The research included a total of 16153 participants. Weighted multivariate regression analyses adjusted for possible variables showed a negative relationship between NMR and estimated glomerular filtration rate (eGFR).The β (95%CI) of the regression equation between NMR and eGFR was -2.24 (-2.92, -1.55), the trend testing showed consistent results. NMR is positively correlated with urinary albumin creatinine ratio (uACR), but it is not statistically significant. A stratified analysis found a negative correlation between NMR and eGFR in all age, gender and diabetes subgroups, the results were not statistically significant among Mexican Americans and other races. Notably, each unit rise in NMR corresponded to a 4.54 ml/min·1.73m² lower eGFR in diabetic participants and a 6.04 ml/min·1.73m² lower eGFR in those aged 60 and above.

Conclusions

Our study shows that nicotine metabolite ratio is negatively associated with kidney function among most adults. It will be necessary to conduct more well-designed prospective clinical trials in order to determine the exact causal interactions between NMR and kidney function. Specific mechanisms also need to be further explored in basic experiments.

Metabolically healthy obesity and chronic kidney disease risk: exploring the dynamics

Obesity represents a prevalent global health concern with significant implications for various diseases, including chronic kidney disease (CKD). Within this landscape, the phenomenon of metabolically healthy obesity has emerged, challenging traditional notions about the health risks associated with excess weight. While traditional CKD risk factors involve obesity, metabolic syndrome, diabetes, and hypertension, the metabolically healthy obese (MHO) subgroup disrupts these assumptions. Our main objective in this study is to integrate existing literature on CKD in MHO individuals. In this endeavor, we delve into the pathophysiological foundations, the transition between obesity phenotypes and their impact on renal health, examine the implications of their metabolic resilience on mortality within a renal context, and explore potential management strategies specifically designed for MHO individuals. Offering a comprehensive overview of the pathophysiology, we cover various factors contributing to the risk of CKD in the metabolically healthy obese setting, including inflammation, cytokines, hemodynamics, and the renin-angiotensin-aldosterone system, gastrointestinal microbiota, diet, exercise, adipose distribution, and lipotoxicity. Through this synthesis, we aim to provide a comprehensive understanding of the risk of CKD in those classified as MHO.

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.

Excess body weight, duration of insulin and antihypertensive therapy slow down the rate of progression of chronic kidney disease in type 2 diabetes

Objective: to study and clinically substantiate the relationship between overweight and the dynamics of CKD progression in patients with type 2 diabetes of different age groups using the diagnostic parameter Index of glomerular filtration rate reduction. Material and methods: a single-stage cross-sectional observational study of clinical indicators in a population sample of patients with type 2 diabetes of different age groups was performed, patterns of relationships, significance of differences in mean values and measures of influence (OR (95%CI)) were studied between the indicators of BMI, the stage of obesity and the presence of a diagnosis of obesity in the anamnesis and the original calculated diagnostic parameter, the Index of glomerular filtration rate reduction (RI_GFR), which allows to give an objective quantitative characteristic of the rate of progression of CKD. Results: significant correlations were established between RI_GFR and indicators of age, BMI, DM experience and duration of insulin therapy, a significant inverse relationship with BMI was noted only in the older group; when analyzing differences in the average values of clinical indicators in the groups of rapid and slow progression of CKD, divided by the threshold value of RI_GFR, significant factors affecting the rate of progression were determined CKD: DM experience, duration of insulin therapy, BMI; the logistic regression analysis determined the measure of the influence of the above factors on the dynamics of GFR reduction, confirmed its significance; when analyzing the factors of drug treatment in the elderly group, it was revealed that an integrated approach to the appointment of antihypertensive therapy (prescribing drugs of three or more groups) significantly reduces the risk of rapid progression of CKD. Conclusions: the most significant risk factors for the high rate of progression of CKD in patients with type 2 diabetes and overweight in the general sample and in patients of the older age group are the length of diabetes and duration of insulin therapy; the dynamics of GFR reduction in patients with type 2 diabetes of different age groups is interrelated with BMI, and in patients with overweight CKD progresses more slowly; an integrated approach to prescribing antihypertensive therapy (prescribing drugs of three or more groups) in elderly patients with type 2 diabetes significantly reduces the risk of rapid progression of CKD.

Predictors of functional impairment and mortality in patients on maintenance hemodialysis

INTRODUCTION

Numerous factors impact the mortality and functional abilities of patients with end-stage renal disease (ESRD) receiving maintenance hemodialysis (MHD). We aimed to determine the mortality rate at 1 year of MHD, identify predictors of mortality, and assess functional impairments concerning activities of daily living (ADLs) and instrumental ADL (IADL).

METHODS

Our study was prospective, observational cohort study that enrolled patients receiving MHD. We collected demographic, clinical, and laboratory data. We also assessed ADLs and IADLs for daily performance.

RESULTS

Our study included 167 patients with a mean age of 51.6 ± 13.1 years, and 56.9% were male. Of these, 80 (47.9%) were diabetic, and 145 (86.8%) were hypertensive. The mortality rate after 1 year of MHD was 10.8%, and cardiovascular causes accounted for over 70% of total deaths. Sudden cardiac death was the most frequent cause (38.9%), followed by cardiogenic shock (22.2%). Older age and low parathormone levels (<300 pg/mL) were significantly associated with higher mortality rates. Mean ADL and IADL scores were 4.5 ± 1.3 and 6.3 ± 2.7, respectively. Eighteen (10.8%) and 56 (33.5%) patients had low ADL and IADL scores, respectively. Although statistically insignificant, a higher proportion of non-survivors exhibited low IADL and ADL scores. Older age, longer diabetes duration, and higher BMI levels were significantly associated with lower IADL scores.

CONCLUSIONS

Older age and suppressed PTH levels are predictors of mortality in ESRD patients receiving MHD. These patients require regular follow-ups to rule out cardiovascular morbidity. Functional impairment is prevalent but remains underdiagnosed in MHD patients. It should be monitored regularly to improve quality of life in ESRD.

Kidney damage predictors in children with metabolically healthy and metabolically unhealthy obesity phenotype

BACKGROUND

Obesity and kidney damage have been closely linked in adults, but little is still known in childhood.

OBJECTIVE

To identify predictors of kidney damage in children with metabolically healthy (MHO) and metabolically unhealthy (MUO) obesity phenotypes.

METHODS

We retrospectively examined 396 children with obesity (mean age 10.72 ± 2.71 years, body mass index-standard deviation score, BMI-SDS, 2.23 ± 0.57) stratified according to metabolic phenotypes. Kidney damage was defined as the presence of reduced estimated glomerular filtration rate (eGFR < 90 mL/min/1.73m2) and/or albuminuria (≥ 30 mg/g urinary creatinine).

RESULTS

Kidney damage was found in 20.9% of the study population. Children with kidney damage had higher BMI-SDS, homeostasis model assessment of insulin resistance (HOMA-IR), and inflammation markers levels and increased prevalence of non-alcoholic fatty liver disease (NAFLD) than those without kidney damage (all p < 0.005). MUO and MHO subjects had respectively an odds ratio (OR) to show kidney damage of of 1.92 (95%CI:1.22-3.01; p = 0.005) and 1.05 (95%CI:1.00-1.09; p = 0.028) after adjustments. Moreover, we found that only HOMA-IR was closely associated to kidney damage in MUO group (OR = 2.07;95%CI:1.20-3.57; p = 0.007), while HOMA-IR (OR = 1.15;95%CI:1.02-1.29; p = 0.011) and uric acid (OR = 1.15;95% CI:1.02-1.30; p = 0.010) were the only significant risk factors for kidney damage in MHO group.

CONCLUSION

An increased risk of kidney damage has been observed in children with obesity and in particular in those with MUO phenotype. As their role on kidney function, HOMA-IR should be monitored in MUO children and both HOMA-IR and uric acid in MHO children.

Metabolic health status and renal disorders: a cross-sectional study

Previous surveys suggests that body mass index (BMI) may be positively related to development of chronic kidney disease (CKD). However, this association might be altered by metabolic syndrome. Therefore, we aimed to evaluate the association of metabolic health status with CKD. The present cross-sectional study was carried out on 3322 representative sample of Iranian adults. Metabolic syndrome was identified based on the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) and BMI was assessed by anthropometric measurements. Estimated glomerular filtration rate (eGFR) was calculated by modification of diet in renal disease-Chronic Kidney Disease Epidemiology Collaboration (MDRD-EPI) formula. Subjects were categorized into four phenotypes: metabolically healthy normal weight (MHNW), metabolically healthy overweight and obesity (MHO), metabolically unhealthy normal weight (MUHNW), and metabolically unhealthy overweight and obesity (MUHO). Based on multivariate-adjusted models, the risk of CKD was significantly higher in MUHO compared with MHNW (OR: 1.48; p < 0.05). Although MUHNW and MUHO were associated with lower eGFR and albuminuria, the significant association was not observed in case of hematuria. Furthermore, subjects with kidney stones tended to be in MHO (OR: 1.42; p < 0.05) and MUHO phenotypes (OR: 1.64; p < 0.05), in comparison to the MHNW phenotype. The odds of kidney disorders were higher in adults with metabolic syndrome, regardless of BMI. However, this relationship might be strengthened by the concomitance of metabolic syndrome and obesity. To verify our findings, clarify the causality, and elucidate the underlying mechanisms, further research are warranted.

Cardiometabolic risk management: insights from a European Society of Cardiology Cardiovascular Round Table

Metabolic comorbidities are common in patients with cardiorenal disease; they can cause atherosclerotic cardiovascular disease (ASCVD), speed progression, and adversely affect prognosis. Common comorbidities are Type 2 diabetes mellitus (T2DM), obesity/overweight, chronic kidney disease (CKD), and chronic liver disease. The cardiovascular system, kidneys, and liver are linked to many of the same risk factors (e.g. dyslipidaemia, hypertension, tobacco use, diabetes, and central/truncal obesity), and shared metabolic and functional abnormalities lead to damage throughout these organs via overlapping pathophysiological pathways. The COVID-19 pandemic has further complicated the management of cardiometabolic diseases. Obesity, T2DM, CKD, and liver disease are associated with increased risk of poor outcomes of COVID-19 infection, and conversely, COVID-19 can lead to worsening of pre-existing ASCVD. The high rates of these comorbidities highlight the need to improve recognition and treatment of ASCVD in patients with obesity, insulin resistance or T2DM, chronic liver diseases, and CKD and equally, to improve recognition and treatment of these diseases in patients with ASCVD. Strategies to prevent and manage cardiometabolic diseases include lifestyle modification, pharmacotherapy, and surgery. There is a need for more programmes at the societal level to encourage a healthy diet and physical activity. Many pharmacotherapies offer mechanism-based approaches that can target multiple pathophysiological pathways across diseases. These include sodium-glucose cotransporter-2 inhibitors, glucagon-like peptide-1 receptor agonists, selective mineralocorticoid receptor antagonists, and combined glucose-dependent insulinotropic peptide/glucagon-like peptide-1 receptor agonist. Non-surgical and surgical weight loss strategies can improve cardiometabolic disorders in individuals living with obesity. New biomarkers under investigation may help in the early identification of individuals at risk and reveal new treatment targets.

Underweight status and development of end-stage kidney disease: A nationwide population-based study

BACKGROUND

Underweight status increases the risk of cardiovascular disease and mortality in the general population. However, whether underweight status is associated with an increased risk of developing end-stage kidney disease is unknown.

METHODS

A total of 9 845 420 participants aged ≥20 years who underwent health checkups were identified from the Korean National Health Insurance Service database and analysed. Individuals with underweight (body mass index [BMI] < 18.5 kg/m2 ) and obesity (BMI ≥ 25 kg/m2 ) were categorized according to the World Health Organization recommendations for Asian populations.

RESULTS

During a mean follow-up period of 9.2 ± 1.1 years, 26 406 participants were diagnosed with end-stage kidney disease. After fully adjusting for other potential predictors, the moderate to severe underweight group (<17 kg/m2 ) had a significantly higher risk of end-stage kidney disease than that of the reference (normal) weight group (adjusted hazard ratio, 1.563; 95% confidence interval, 1.337-1.828), and competing risk analysis to address the competing risk of death also showed the similar results (adjusted hazard ratio, 1.228; 95% confidence interval, 1.042-1.448). Compared with that of the reference BMI group (24-25 kg/m2 ), the adjusted hazard ratios for end-stage kidney disease increased as the BMI decreased by 1 kg/m2 . In the sensitivity analysis, sustained underweight status or progression to underweight status over two repeated health checkups, when compared with normal weight status, had a higher hazard ratio for end-stage kidney disease.

CONCLUSIONS

Underweight status is associated with an increased risk of end-stage kidney disease, and this association gradually strengthens as BMI decreases.

Metabolically healthy obesity is associated with higher risk of both hyperfiltration and mildly reduced estimated glomerular filtration rate: the role of serum uric acid in a cross-sectional study

BACKGROUND

The impact of metabolically healthy obesity (MHO) on kidney dysfunction remains debatable. Moreover, few studies have focused on the early stages of kidney dysfunction indicated by hyperfiltration and mildly reduced eGFR. Thus, we aimed to investigate the association between the MHO and early kidney dysfunction, which is represented by hyperfiltration and mildly reduced estimated glomerular filtration rate (eGFR), and to further explore whether serum uric acid affects this association.

METHODS

This cross-sectional study enrolled 1188 residents aged ≥ 40 years old from Yonghong Communities. Metabolically healthy phenotypes were categorized based on Adult Treatment Panel III criteria. Obesity was defined as body mass index (BMI) ≥ 25 kg/m². Mildly reduced eGFR was defined as being in the range 60 < eGFR ≤ 90 ml/min/1.73m². Hyperfiltration was defined as eGFR > 95th percentile after adjusting for sex, age, weight, and height.

RESULTS

Overall, MHO accounted for 12.8% of total participants and 24.6% of obese participants. Compared to metabolically healthy non-obesity (MHNO), MHO was significantly associated with an increased risk of mildly reduced eGFR (odds ratio [OR] = 1.85, 95% confidence interval [CI]  1.13-3.01) and hyperfiltration (OR = 2.28, 95% CI 1.03-5.09). However, upon further adjusting for uric acid, the association between the MHO phenotype and mildly reduced eGFR was reduced to null. Compared with MHNO/non-hyperuricemia, MHO/non-hyperuricemia was associated with an increased risk of mildly reduced eGFR (OR = 2.04, 95% CI  1.17-3.58), whereas MHO/hyperuricemia was associated with an observably increased risk (OR = 3.07, 95% CI  1.34-7.01).

CONCLUSIONS

MHO was associated with an increased risk of early kidney dysfunction, and the serum uric acid partially mediated this association. Further prospective studies are warranted to clarify the causality.

The Effect of Metabolic Syndrome and Its Individual Components on Renal Function: A Meta-Analysis

BACKGROUND

Observational studies have reported inconsistent findings in the relationship between metabolic syndrome (MetS), its components, and loss of renal function, mainly including eGFR decline, new-onset CKD, and ESRD. This meta-analysis was performed to investigate their potential associations.

METHODS

PubMed and EMBASE were systematically searched from their inception to 21 July 2022. Observational cohort studies in English assessing the risk of renal dysfunction in individuals with MetS were identified. Risk estimates and their 95% confidence intervals (CIs) were extracted and pooled using the random-effects approach.

RESULTS

A total of 32 studies with 413,621 participants were included in the meta-analysis. MetS contributed to higher risks of renal dysfunction (RR = 1.50, 95% CI = 1.39-1.61) and, specifically, rapid decline in eGFR (RR 1.31, 95% CI 1.13-1.51), new-onset CKD (RR 1.47, 95% CI 1.37-1.58), as well as ESRD (RR 1.55, 95% CI 1.08-2.22). Moreover, all individual components of MetS were significantly associated with renal dysfunction, while elevated BP conveyed the highest risk (RR = 1.37, 95% CI = 1.29-1.46), impaired fasting glucose with the lowest and diabetic-dependent risk (RR = 1.20, 95% CI = 1.09-1.33).

CONCLUSIONS

Individuals with MetS and its components are at higher risk of renal dysfunction.

The risk for chronic kidney disease in metabolically healthy obese patients: A systematic review and meta-analysis

BACKGROUND

Chronic kidney disease (CKD) is associated with obesity and metabolic syndrome. Nevertheless, the association of CKD with phenotype referred as metabolically healthy obese or overweight is unclear. In this this systematic review and meta-analysis, we investigate the relationships between obesity and CKD independent of metabolic syndrome by appraising published evidence in studies focusing on metabolically healthy obese people.

MATERIALS AND METHODS

We performed a literature search through three databases Embase (Elsevier), the Cochrane Central Register of Controlled Trials (Wiley) and PubMed/Medline Web of Science up to March 2022 with the following terms: "chronic kidney disease", "kidney function", "obesity", "metabolic syndrome", "metabolically healthy obesity", "metabolically healthy overweight". Metabolically unhealthy was defined an individual having at least 3 of the following: abdominal obesity, high blood pressure, hypertriglyceridemia, low HDL cholesterol and hyperglycaemia. We used Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) for reporting. Prospective, retrospective, randomized and nonrandomized studies fitting the search criteria were included in our results.

RESULTS

Our final analysis included 16 studies with a total number of 4.965.285 participants. There is considerable heterogeneity in terms of study design, participant characteristics and number of participants across individual studies. In comparison to healthy normal weight patients, the risk was progressively higher in overweight (RR 1.29, 95% CI 1.27 to 1.32, p < 0.001) and obese patients (RR 1.47, 95% CI 1.31 to 1.65, p < 0.001).

CONCLUSION

Metabolically healthy overweight and obese individuals have higher risk of CKD compared to individuals without weight excess.

Association of obesity with the development of end stage renal disease in IgA nephropathy patients

BACKGROUND AND AIM

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. We aimed to evaluate whether obesity is a risk factor for IgAN patients.

METHODS

A total of 1054 biopsy-proven IgAN patients were analyzed in this retrospective study. Patients were divided into four groups according to their body weight index (BMI) at the period of renal biopsy: underweight group (BMI< 18.5, N=75), normal weight group (18.5≤BMI<24, N=587), overweight group (24≤BMI<28, N=291) and obesity group (28≤BMI, N=101). The endpoint of our study was end stage renal disease (ESRD: eGFR <15 mL/min/1.73 m² or having renal replacement treatment). Kaplan-Meier analyses and Cox proportional hazard models were performed to evaluate renal survival. Propensity-score matching (PSM) was performed to get the matched cohort to evaluate the role of obesity in IgAN patients. Besides, the effect modification of obesity and hypertension in IgAN patients was clarified by the synergy index.

RESULTS

IgAN patients complicated with obesity had more severe renal dysfunction at the time of renal biopsy than those with optimal body weight. In addition, patients with obesity tended to have higher risk of metabolic disorders, such as hyperuricemia (64.4% vs 37%, p<0.001), hypertriglyceridemia (71.3% vs 32.5%, p<0.001) and hypercholesterolemia (46.5% vs 35.6%, p=0.036). It was observed that obesity patients had higher rate of unhealthy behaviors, such as smoking (27.7% vs 16.4%, p=0.006) and alcohol drinking (29.7% vs 19.9%, p=0.027). Although obesity was not confirmed as an independent risk factor for IgAN patients, we found that IgAN patients with obesity presented with higher incidence of hypertension, as well as lower event-free renal survival rate (log-rank p < 0.001), especially in patients with 24-h urine protein ≥ 1g (log-rank p =0.002). In addition, the synergy index showed that there was positive interaction between obesity and hypertension in IgAN.

CONCLUSION

Obesity is an important risk factor for IgAN patients when combined with hypertension. Hypertension appears to be common in obese IgAN patients.

Expectations in children with glomerular diseases from SGLT2 inhibitors

Chronic kidney disease (CKD) is a global public healthcare concern in the pediatric population, where glomerulopathies represent the second most common cause. Although classification and diagnosis of glomerulopathies still rely mostly on histopathological patterns, patient stratification should complement information supplied by kidney biopsy with clinical data and etiological criteria. Genetic determinants of glomerular injury are particularly relevant in children, with important implications for prognosis and treatment. Targeted therapies addressing the primary cause of the disease are available for a limited number of glomerular diseases. Consequently, in the majority of cases, the treatment of glomerulopathies is actually the treatment of CKD. The efficacy of the currently available strategies is limited, but new prospects evolve. Although the exact mechanisms of action are still under investigation, accumulating data in adults demonstrate the efficacy of sodium-glucose transporter 2 inhibitors (SGLT2i) in slowing the progression of CKD due to diabetic and non-diabetic kidney disease. SGLT2i has proved effective on other comorbidities, such as obesity, glycemic control, and cardiovascular risk that frequently accompany CKD. The use of SGLT2i is not yet approved in children. However, no pathophysiological clues theoretically exclude their application. The hallmark of pediatric CKD is the inevitable imbalance between the metabolic needs of a growing child and the functional capacity of a failing kidney to handle those needs. In this view, developing better strategies to address any modifiable progressor in kidney disease is mandatory, especially considering the long lifespan typical of the pediatric population. By improving the hemodynamic adaptation of the kidney and providing additional beneficial effects on the overall complications of CKD, SGLT2i is a candidate as a potentially innovative drug for the treatment of CKD and glomerular diseases in children.

Preventive and Therapeutic Effects of Krill Oil on Obesity and Obesity-Induced Metabolic Syndromes in High-Fat Diet-Fed Mice

Obesity increases the risks of metabolic syndromes including nonalcoholic fatty liver disease (NAFLD), diabetic dyslipidemia, and chronic kidney disease. Dietary krill oil (KO) has shown antioxidant and anti-inflammatory properties, thereby being a therapeutic potential for obesity-induced metabolic syndromes. Thus, the effects of KO on lipid metabolic alteration were examined in a high-fat diet (HFD)-fed mice model. The HFD model (n = 10 per group) received an oral gavage with distilled water as a control, metformin at 250 mg/kg, and KO at 400, 200, and 100 mg/kg for 12 weeks. The HFD-induced weight gain and fat deposition were significantly reduced in the KO treatments compared with the control. Blood levels were lower in parameters for NAFLD (e.g., alanine aminotransferase, and triglyceride), type 2 diabetes (e.g., glucose and insulin), and renal dysfunction (e.g., blood urea nitrogen and creatinine) by the KO treatments. The KO inhibited lipid synthesis through the modification of gene expressions in the liver and adipose tissues and adipokine-mediated pathways. Furthermore, KO showed hepatic antioxidant activities and glucose lowering effects. Histopathological analyses revealed that the KO ameliorated the hepatic steatosis, pancreatic endocrine/exocrine alteration, adipose tissue hypertrophy, and renal steatosis. These analyses suggest that KO may be promising for inhibiting obesity and metabolic syndromes.

The Association of Excess Body Weight with Risk of ESKD Is Mediated Through Insulin Resistance, Hypertension, and Hyperuricemia

BACKGROUND

Insulin resistance, hypertension, hyperuricemia, and hypercholesterolemia are hypothesized to be important intermediates in the relationship between excess body weight and CKD risk. However, the magnitude of the total effect of excess body weight on ESKD mediated through these four pathways remains to be quantified.

METHODS

We applied a model for analysis of correlated mediators to population-based data from 100,269 Austrian individuals (mean age 46.4 years). Association of body mass index (BMI) was coalesced with ESKD risk into direct association. Indirect associations were mediated through the triglyceride-glucose (TyG) index (as an indicator of insulin resistance), mean arterial pressure (MAP), uric acid (UA), and total cholesterol (TC).

RESULTS

Mean follow-up was 23.1 years with 463 (0.5%) incident ESKD cases. An unhealthy metabolic profile (prevalence 32.4%) was associated with a markedly increased ESKD risk (multivariably adjusted hazard ratio (aHR), 3.57; 95% CI, 2.89 to 4.40), independent of BMI. A 5-kg/m2 higher BMI was associated with a 57% increased ESKD risk (aHRtotal association, 1.57; 1.38 to 1.77). Of this association, 99% (76% to 140%) arose from all mediators jointly; 33% (22% to 49%) through TyG index; 34% (24% to 50%) through MAP; 30% (21% to 45%) through UA; and 2% (-1% to 4%) through TC. The remaining direct association was nonsignificant (aHRdirect association, 1.01; 0.88 to 1.14).

CONCLUSIONS

TyG index, MAP, and UA, but not TC, mediate the association of BMI with ESKD in middle-aged adults. Our findings highlight that in addition to weight reduction, the control of metabolic risk factors might be essential in mitigating the adverse effects of BMI on kidney function.

Obesity-related glomerulopathy: Current approaches and future perspectives

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

Higher Neutrophil-To-Lymphocyte Ratio Was Associated with Increased Risk of Chronic Kidney Disease in Overweight/Obese but Not Normal-Weight Individuals

Background: Inflammation has been proposed to play potential roles in the development and progression of chronic kidney disease (CKD). We evaluated the relationship of neutrophil-to-lymphocyte ratio (NLR), a systemic inflammation marker, with CKD in normal-weight and overweight/obese adults. Methods: This cross-sectional study included 2846 apparently healthy adults who underwent a health examination between August 2000 and April 2002. Normal-weight was defined as a body mass index (BMI, kg/m2) of 18.5−24, while overweight/obesity was defined as a BMI of ≥24. CKD was defined as an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m2. Logistic and linear regression analysis was performed to explore the NLR−CKD relationship. Results: Of the 2846 participants (1777 men and 1069 women), there were 348 CKD individuals (12.3%), with 262 (14.7%) men and 86 (8%) women. A total of 1011 men (56.9%) and 408 women (38.2%) were overweight or obese. Compared with the normal-weight participants, CKD prevalence was higher in the overweight/obese women (6.1% vs. 11.3%, p = 0.002), but not in the overweight/obese men (14.5% vs. 14.9%, p = 0.793). CKD percentages in the NLR quartile groups were 9.4%, 11.5%, 15.4%, and 22.7% in men (p < 0.0001) and 6.4%, 7.1%, 10.5%, and 8.2% in women (p = 0.2291). After adjustment for confounders, each increment of one unit of NLR was associated with a higher CKD risk in the overweight/obese men (adjusted odds ratio (OR) = 1.37, 95% confidence interval (CI) = 1.03−1.82, p = 0.03) and women (adjusted OR = 1.77, 95% CI = 1.08−2.90, p = 0.023), whereas NLR was not associated with CKD in normal-weight men or women. Further, in the overweight/obese participants with an eGFR of 50−70 mL/min/1.73 m2, univariable linear regression analysis revealed a significant negative correlation between NLR and eGFR for men (p = 0.004) and women (p = 0.009). Conclusions: It was found that higher NLR was associated with an increased CKD risk in overweight/obese but not in normal-weight men and women in an adult health examination dataset. Our study suggests a role of NLR for CKD prediction in overweight/obese individuals.

Prognostic Value of Triglyceride to High-Density Lipoprotein Cholesterol Ratio (TG/HDL-C) in IgA Nephropathy Patients

BACKGROUND

The triglycerides to high-density lipoprotein cholesterol (TG/HDL-C) ratio is an easy-to-use atherogenic and prognostic marker which has attracted increasing attention these days. However, whether TG/HDL-C correlate with outcomes in IgA nephropathy (IgAN) patients remains unknown. To clarify these issues, we conducted this study.

METHODS

A total of 1146 patients from West China Hospital of Sichuan University were retrospectively analysed between 2008 and 2018.The demographic, clinical and pathological data of all patients at the time of biopsy were collected. Then, patients were divided into the high TG/HDL group (TG/HDL ≥ 1.495, N=382) and the low TG/HDL group (TG/HDL-C < 1.495, N=764) based on the optimal cut-off value of the TG/HDL-C using receive operating curve. Cox proportional hazard models and Kaplan-Meier curves were used to evaluate the renal outcomes of IgAN.

RESULTS

The median age of the patients was 33 (26-42) years, and 44.5% were men. By correlation analysis, we found that the TG/HDL-C ratio was negatively correlated with the eGFR (r = 0.250, P < 0.001) but positively correlated with proteinuria (r = 0.230, P< 0.001), BMI (r=0.380, P<0.001) and serum uric (r =0.308, P< 0.001). Patients with a higher TG/HDL-C ratio tended to have hypertension [odds ratio (OR), 1.987; 95% CI, 1.527-2.587; P<0.001] and more severe pathologic lesions with tubular atrophy/interstitial fibrosis (OR, 1.610; 95% CI, 1.203-2.154; P=0.001). During a median follow-up period of 54.1 (35.6-73.2) months, a high TG/HDL ratio was strongly associated with worse renal survival in IgAN patients (log-rank: P <0.001). Multivariate Cox analysis demonstrated that a high TG/HDL-C ratio (HR 1.775, 95% CI 1.056-2.798; P=0.029) was an independent predictive marker to ESRD.

CONCLUSION

In this study, we addressed the importance of TG/HDL-C ratio as a predictive marker for IgAN progression.

Evaluation of microalbuminuria in obesity phenotypes

BACKGROUND:

Obesity is a universal health issue of the present time. Nearly 2 billion people were estimated to be either overweight or obese in 2020, with nearly 3.4 million deaths worldwide. Proteinuria is now widely known to be a significant predictor of renal pathologies including end-stage renal disease. This study aimed to assess the relationship between the presence of microalbuminuria (MA) in obese individuals.

MATERIALS AND METHODS:

This cross-sectional study was conducted among patients attending the outpatient department of Jawaharlal Nehru Medical College and Acharya Vinoba Bhave Rural Hospital, Sawangi (Meghe), Wardha. From the subjects meeting the study criteria, selected 150 individuals with BMI ≥ 25 that formed the obese group. Obese individuals were further subdivided as metabolic healthy obese (MHO) and metabolic abnormal obese (MAO) based on metablic syndrome criteria. From the non-obese patients (BMI≤25), one age and gender matched control was selected for each obese subject. All subjects were tested for MA by dipstick method. Data was analyzed using SPSS and Chi-square test was performed to test for statistical significance.

RESULTS:

The study reflected the association of MA in the groups studied. The metabolic abnormal obese group was noted as having the highest percentage of positive cases (53.7%) of MA, followed by the MHO group (31.3%). A significant association of prevalence of MA was seen in MHO and MAO obese individuals (P < 0.001). MA was present in the urine samples of 26 (31.3%) obese subjects in the MHO group, 36 (53.7%) in the MAO group, and 8 (5.3%) in the control population.

CONCLUSION:

Both MHO and MAO subgroups of obese individuals showed higher proportion of MA indicating adverse renal function. Therefore, primary prophylactic measures such as health education and lifestyle modification should be promoted for the obese to reduce their body weight and thereby possibly reduce the risk of future obesity-related renal complications.

Combination Effects of Metformin and a Mixture of Lemon Balm and Dandelion on High-Fat Diet-Induced Metabolic Alterations in Mice

Metformin, the first-line drug for type 2 diabetes mellitus (T2DM), has additional effects on improvements of nonalcoholic fatty liver disease (NAFLD); however, there are no treatments for both T2DM and NAFLD. Previous studies have shown hepatoprotective effects of a mixture of lemon balm and dandelion (LD) through its antioxidant and anti-steatosis properties. Thus, combination effects of metformin and LD were examined in a high-fat diet (HFD)-induced metabolic disease mouse model. The model received an oral administration of distilled water, monotherapies of metformin and LD, or a metformin combination with LD for 12 weeks. The HFD-induced weight gain and body fat deposition were reduced more by the combination than either monotherapy. Blood parameters for NAFLD (i.e., alanine aminotransferase and triglyceride), T2DM (i.e., glucose and insulin), and renal functions (i.e., blood urea nitrogen and creatinine) were reduced in the combination. The combination further enhanced hepatic antioxidant activities, and improved insulin resistance via the AMP-activated protein kinase and lipid metabolism pathways. Histopathological analyses revealed that the metformin combination ameliorated the hepatic hypertrophy/steatosis, pancreatic endocrine/exocrine alteration, fat tissue hypertrophy, and renal steatosis, more than either monotherapy. These results suggest that metformin combined with LD can be promising for preventing and treating metabolic diseases involving insulin resistance.

Association of metabolic syndrome traits with urinary biomarkers in Japanese adults

BACKGROUND

Although metabolic syndrome traits are risk factors for chronic kidney disease, few studies have examined their association with urinary biomarkers.

METHODS

Urinary biomarkers, including A-megalin, C-megalin, podocalyxin, albumin, α₁-microglobulin, β₂-microglobulin, and N-acetyl-β-D-glucosaminidase, were cross-sectionally assessed in 347 individuals (52.7% men) with a urine albumin-to-creatinine ratio (ACR)  < 300 mg/g in a health checkup. Metabolic syndrome traits were adopted from the National Cholesterol Education Program (third revision) of the Adult Treatment Panel criteria modified for Asians.

RESULTS

Participants had a mean body mass index, estimated glomerular filtration rate (eGFR), and median ACR of 23.0 kg/m², 74.8 mL/min/1.73 m², and 7.5 mg/g, respectively. In age- and sex-adjusted logistic regression analysis, A-megalin and albumin were significantly associated with the clustering number of metabolic syndrome traits (3 or more). After further adjustment with eGFR, higher quartiles of A-megalin and albumin were each independently associated with the clustering number of metabolic syndrome traits (adjusted odds ratio for A-megalin: 1.30 per quartile, 95% CI 1.03-1.64; albumin: 1.42 per quartile, 95% CI 1.12-1.79).

CONCLUSIONS

Both urinary A-megalin and albumin are associated with the clustering number of metabolic syndrome traits. Further research on urinary A-megalin is warranted to examine its role as a potential marker of kidney damage from metabolic risk factors.

Correlation of Body Mass Index with Clinicopathologic Parameters in Patients with Idiopathic Membranous Nephropathy

OBJECTIVE

To investigate the association between body mass index (BMI) and clinicopathologic parameters in patients with idiopathic membranous nephropathy (IMN).

METHODS

This study was retrospective and included patients with biopsy-proven IMN from 2018 to 2021 in Hebei General Hospital. Patients were categorized into two groups based on BMI. Clinical and histopathologic data were analyzed at the time of renal biopsy. Pathological data included immunofluorescence staining, glomerulosclerosis (GS, 0-2), mesangial cell proliferation (MCP, 0-1), tubular atrophy (TA, 0-1), interstitial fibrosis (IF, 0-1), vascular wall thickness (VWT, 0-1) and a combination score (GMTIV) graded from 0 to 5.

RESULTS

Our study revealed that the obese group had a higher prevalence of hypertension and diabetes than the overweight/normal weight group (P=0.001, P=0.002). Systolic blood pressure (P=0.005), diastolic blood pressure (P<0.001), haemoglobin (P=0.006), triglycerides (P<0.001), serum uric acid (P=0.05), 24 h urine proteinuria concentration (UP) (P=0.012), MCP (P=0.042), IF (P=0.033), and GMITV (P=0.033) score were higher in obese group compared to the other group, while the high-density lipoprotein-cholesterol (P=0.034) and immunoglobulin A deposition score (P=0.005) were lower. Factors significantly associated with UP were the ratio of lymphocyte count to white blood cell count, serum pre-albumin, immunoglobulin G, microscopic hematuria, anti-phospholipase A2 receptor (anti-PLA2R), C3 deposit on multivariable analysis (adjusted R ²=0.343). Binary logistic regression analysis illustrated that MCP was correlated to BMI (OR=2.528, P=0.036). Ordinal logistic regression analysis demonstrated that GMTIV was associated with BMI (OR=1.114, P=0.010) and C3 deposit (OR=1.655, P=0.001).

CONCLUSION

High BMI was associated with MCP and GMTIV score in IMN patients. Obesity may play an essential role in mesangial lesions of IMN. This study emphasized the relation between BMI and histological parameters under the universal usage of anti-PLA2R antibodies for diagnosis and prognosis in IMN.

Impact of Obesity in Kidney Diseases

The clinical consequences of obesity on the kidneys, with or without metabolic abnormalities, involve both renal function and structures. The mechanisms linking obesity and renal damage are well understood, including several effector mechanisms with interconnected pathways. Higher prevalence of urinary albumin excretion, sub-nephrotic syndrome, nephrolithiasis, increased risk of developing CKD, and progression to ESKD have been identified as being associated with obesity and having a relevant clinical impact. Moreover, renal replacement therapy and kidney transplantation are also influenced by obesity. Losing weight is key in limiting the impact that obesity produces on the kidneys by reducing albuminuria/proteinuria, declining rate of eGFR deterioration, delaying the development of CKD and ESKD, and improving the outcome of a renal transplant. Weight reduction may also contribute to appropriate control of cardiometabolic risk factors such as hypertension, metabolic syndrome, diabetes, and dyslipidemia which may be protective not only in renal damage but also cardiovascular disease. Lifestyle changes, some drugs, and bariatric surgery have demonstrated the benefits.

Obesity related risk for chronic kidney disease progression and cardiovascular disease after propensity score matching

INTRODUCTION

Obesity is a major health problem worldwide. It carries a markedly increased risk for multiple diseases such as type 2 diabetes mellitus, hypertension, cardiovascular disease (CVD) and chronic kidney disease (CKD). To complicate an already difficult topic a new subtype of obesity has been defined lately, the metabolically healthy obese. Our study aimed to clarify the association between obesity, metabolic syndrome and kidney disease progression.

METHODS

Observational retrospective single centre study including 212 patients with stage 3-4 CKD with no previous history of rapid kidney disease progression. Patients were divided according to BMI status and presence of metabolic syndrome. Anthropometric, clinical and laboratory data were collected to follow-up. Propensity score matching was performed for age, albuminuria and baseline renal function. During follow-up renal and cardiovascular events were recorded.

RESULTS

After a mean follow-up of 88.44±36.07 months a total of 18 patients reached the renal outcome in the non-obese group and 21 in the obese group. Differences were not statistically significant (log rank=0.21: p=0.64). Multiple Cox regression analysis showed that obesity was not predictor for worse renal outcomes [HR 1.01, 95% CI 0.45-2.24; p=0.97]. When stratifying the sample according to baseline metabolic syndrome and obesity presence there was no difference in renal survival (log rank=0.852; p=0.35) A total of 48 cardiovascular events were registered: seventeen in the non-obese group and thirty-one in the obese group. Differences in event-free time between both groups were statistically significant (log rank=4.44;p=0.035), especially after four years of follow-up. After stratifying for MS and obesity presence at baseline the event-free time differences where again statistically significant (log rank=16.86;p=0.001), specially for the obese patients with metabolic syndrome.

CONCLUSIONS

Obesity has little impact on chronic kidney disease progression despite the presence or absence of metabolic syndrome in a cohort matched for age, baseline renal function and albuminuria. Obesity conferred greater cardiovascular risk when combined with metabolic syndrome.

KDOQI US Commentary on the 2020 KDIGO Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation

Evaluation of patients for kidney transplant candidacy is a comprehensive process that involves a detailed assessment of medical and surgical issues, psychosocial factors, and patients' physical and cognitive abilities with an aim of balancing the benefits of transplantation and potential risks of surgery and long-term immunosuppression. There is considerable variability among transplant centers in their approach to evaluation and decision-making regarding transplant candidacy. The 2020 KDIGO (Kidney Disease: Improving Guidelines Outcome) clinical practice guideline on the evaluation and management of candidates for kidney transplantation provides practice recommendations that can serve as a useful reference guide to transplant professionals. The guideline, covering a broad range of topics, was developed by an international group of experts from transplant and nephrology through a review of literature published until May 2019. A work group of US transplant nephrologists convened by NKF-KDOQI (National Kidney Foundation-Kidney Disease Quality Initiative) chose key topics for this commentary with a goal of presenting a broad discussion to the US transplant community. Each section of this article has a summary of the key KDIGO guideline recommendations, followed by a brief commentary on the recommendations, their clinical utility, and potential implementation challenges. The KDOQI work group agrees broadly with the KDIGO recommendations but also recognizes and highlights the decision-making challenges that arise from lack of high-quality evidence and the need to balance equity with utility of organ transplantation.

Effects of Ethanol Extracts from Grateloupia elliptica, a Red Seaweed, and Its Chlorophyll Derivative on 3T3-L1 Adipocytes: Suppression of Lipid Accumulation through Downregulation of Adipogenic Protein Expression

Grateloupia elliptica (G. elliptica) is a red seaweed with antioxidant, antidiabetic, anticancer, anti-inflammatory, and anticoagulant activities. However, the anti-obesity activity of G. elliptica has not been fully investigated. Therefore, the effect of G. elliptica ethanol extract on the suppression of intracellular lipid accumulation in 3T3-L1 cells by Oil Red O staining (ORO) was evaluated. Among the eight red seaweeds tested, G. elliptica 60% ethanol extract (GEE) exhibited the highest inhibition of lipid accumulation. GEE was the only extract to successfully suppress lipid accumulation among ethanol extracts from eight red seaweeds. In this study, we successfully isolated chlorophyll derivative (CD) from the ethyl acetate fraction (EA) of GEE by high-performance liquid chromatography and evaluated their inhibitory effect on intracellular lipid accumulation in 3T3-L1 adipocytes. CD significantly suppressed intracellular lipid accumulation. In addition, CD suppressed adipogenic protein expression such as sterol regulatory element-binding protein-1 (SREBP-1), peroxisome proliferator-activated receptor-γ (PPAR-γ), CCAAT/enhancer-binding protein-α (C/EBP-α), and fatty acid binding protein 4 (FABP4). Taken together, our results indicate that CD from GEE inhibits lipid accumulation by suppressing adipogenesis via the downregulation of adipogenic protein expressions in the differentiated adipocytes. Therefore, chlorophyll from G. elliptica has a beneficial effect on lipid metabolism and it could be utilized as a potential therapeutic agent for preventing obesity.

Association between weight status, metabolic syndrome, and chronic kidney disease among middle-aged and elderly Chinese

BACKGROUND AND AIMS

Obesity often initiates or coexists with certain metabolic abnormalities. This study sought to examine the independent and joint relations of weight and metabolic syndrome (MetS) with incident chronic kidney disease (CKD) among Chinese elderly people.

METHODS AND RESULTS

A total of 15,229 participants (mean age: 62.8 years) from the Dongfeng-Tongji cohort with complete baseline questionnaire and medical examination data were followed from 2008 to 2010 to 2013. All participants were categorized into four phenotypes: metabolically healthy non-overweight/obesity (MHNO), metabolically healthy overweight/obesity (MHO), metabolically unhealthy non-overweight/obesity (MUNO), metabolically unhealthy overweight/obesity (MUO). Multivariable-adjusted logistic regression models were applied to estimate the odds ratios (ORs) and confidence intervals (CIs) of four phenotypes with the risk of incident CKD, which was defined as estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m². A total of 1151 CKD cases were identified during a mean of 4.6-year follow-up. After adjusting for potential confounders, both overweight/obesity and MetS were associated with higher risk of CKD, and the ORs (95% CI) were 1.32 (1.15-1.52) and 1.50 (1.31-1.73), respectively. The risk of CKD was progressively higher in MHO (1.31, 1.09-1.57), MUNO (1.54, 1.22-1.93), and MUO (2.05, 1.73-2.42) as compared with MHNO phenotype, without significant multiplicative interaction between overweight/obesity and MetS (P_interaction = 0.906). These associations were slightly stronger among those aged >60 years or with baseline diabetes.

CONCLUSION

Both overweight/obesity and MetS were associated with an increased risk of CKD. It is worth noting that MHO and MUNO also have an elevated risk. Maintaining both normal weight and healthy metabolic profile is recommended.

Liraglutide protects against high-fat diet-induced kidney injury by ameliorating apoptosis

BACKGROUND

Obesity is associated with the development and progression of chronic kidney disease. Emerging evidence suggests that glucagon-like peptide-1 receptor agonist could reduce renal damage and albuminuria. Sirtuin 1 (SIRT1) was considered as a crucial regulator in metabolism-related kidney disease. Herein, the role of SIRT1 in liraglutide-ameliorated high-fat diet (HFD)-induced kidney injury was illustrated.

METHODS

Male C57BL/6 mice were fed HFD for 20 weeks to induce kidney injury that was then treated with liraglutide for 8 weeks to estimate its protective effect on the kidney. Also, the mechanism of the drug in SV40 MES 13 (SV40) mouse mesangial cells was elucidated.

RESULTS

Liraglutide treatment ameliorated HFD-induced metabolic disorders, including hyperglycemia, increasing body weight, and insulin resistance. In addition, kidney weight, urine albumin-to-creatinine, and kidney morphological changes such as vacuolated tubules, glomerulomegaly, thickened glomerular basement membrane, and tubulointerstitial fibrosis were also significantly ameliorated. Furthermore, apoptotic cells and apoptosis markers were downregulated in the kidney of liraglutide-treated mice. In addition, the expression of SIRT1 protein was upregulated, whereas thioredoxin-interacting protein (TXNIP), which serves as a mediator of oxidative stress and apoptosis in metabolism disease, was downregulated by liraglutide. In SV40 cells, the effect of liraglutide on reversing the upregulation of cleaved caspase-3 induced by high glucose (30 mM) was hampered when SIRT1 was knocked down; also, the downregulation of TXNIP by liraglutide was blocked.

CONCLUSIONS

Liraglutide might have a beneficial effect on metabolism-related kidney damage by inhibiting apoptosis via activation of SIRT1 and suppression of TXNIP pathway.

The Impact of Obesity on the Severity of Clinicopathologic Parameters in Patients with IgA Nephropathy

Several studies reported the effect of obesity on the progression of IgA nephropathy (IgAN). However, the impact of obesity on the clinicopathologic presentation of IgAN remains uncertain. This is a retrospective cross-sectional study from eight university hospitals in South Korea. Patients were categorized into three groups using the Asia-Pacific obesity classification based on body mass index (BMI). Clinical and histopathologic data at the time of renal biopsy were analyzed. Among 537 patients with IgAN, the obese group was more hypertensive and had lower estimated glomerular filtration rate and more proteinuria than other groups. The histologic scores for mesangial matrix expansion (MME), interstitial fibrosis, tubular atrophy, and mesangial C3 deposition differed significantly between the three groups. Among these histopathologic parameters, BMI was independently positively associated with MME score on multivariable linear regression analysis (p = 0.028). Using multivariable logistic regression analysis, the obese group was independently associated with higher MME scores compared to the normal weight/overweight group (p = 0.020). However, BMI was not independently associated with estimated glomerular filtration rate or proteinuria on multivariable analysis. Obesity was independently associated with severe MME in patients with IgAN. Obesity may play an important pathogenetic role in mesangial lesions seen in IgAN.

Association of smoking with incident CKD risk in the general population: A community-based cohort study

BACKGROUND

Chronic kidney disease (CKD) is a public health problem, and an unfavorable lifestyle has been suggested as a modifiable risk factor for CKD. Cigarette smoking is closely associated with cardiovascular disease and cancers; however, there is a lack of evidence to prove that smoking is harmful for kidney health. Therefore, we aimed to determine the relationship between cigarette smoking and CKD among healthy middle-aged adults.

METHODS

Using the database from the Korean Genome and Epidemiology Study, we analyzed 8,661 participants after excluding those with baseline estimated glomerular filtration rate (eGFR)<60 ml/min/1.72 m2 or proteinuria. Exposure of interest was smoking status: never-, former-, and current-smokers. Primary outcome was incident CKD defined as eGFR <60 ml/min/1.73 m2 or newly developed proteinuria.

RESULTS

The mean age of the subjects was 52 years, and 47.6% of them were males. There were 551 (6.4%) and 1,255 (14.5%) subjects with diabetes and hypertension, respectively. The mean eGFR was 93.0 ml/min/1.73 m2. Among the participants, 5,140 (59.3%), 1,336 (15.4%), and 2,185 (25.2%) were never-smokers, former-smokers, and current-smokers, respectively. During a median follow-up of 11.6 years, incident CKD developed in 1,941 (22.4%) subjects with a crude incidence rate of 25.1 (24.0-26.2) per 1,000 person-years. The multivariable Cox regression analysis after adjustment of confounding factors showed hazard ratios (95% confidence interval) of 1.13 (0.95-1.35) and 1.26 (1.07-1.48) for CKD development in the former- and current-smokers, compared with never-smokers.

CONCLUSION

This study showed that smoking was associated with a higher risk of incident CKD among healthy middle-aged adults.

Metabolic abnormalities, but not obesity per se, associated with chronic kidney disease in a Taiwanese population

BACKGROUND AND AIMS

It is inconclusive whether obesity itself or metabolic abnormalities are linked to chronic kidney disease (CKD). The aim of this study was to examine the association between different subtypes of obesity and metabolic abnormalities with CKD in adults.

METHODS AND RESULTS

This study enrolled 14,983 eligible subjects stratified into metabolically healthy normal weight (MHNW), metabolically healthy overweight (MHOW), metabolically healthy obesity (MHO), metabolically unhealthy normal weight (MUNW), metabolically unhealthy overweight (MUOW), and metabolically unhealthy obesity (MUO) according to body mass index and metabolic syndrome status (ATP-III criteria). The metabolic healthy phenotype was defined as the absence of both metabolic syndrome and any known diabetes, coronary artery disease, stroke, hypertension or dyslipidemia. Early and advanced CKD were defined as eGFR<60, proteinuria, or structural abnormalities as detected by renal sonography. The prevalence of CKD was 2.5, 3.0, 4.0, 10.6, 9.5, and 10.5% in subjects with MHNW, MHOW, MHO, MUNW, MUOW, and MUO, respectively. In the multivariate analysis, the MUNW (OR:2.22, P < 0.001), MUOW (OR:2.22, P < 0.001), and MUO (OR:2.45, P < 0.001) groups were associated with early CKD. For advanced CKD, the OR was 2.56 (P < 0.001), 2.31 (P < 0.001), and 3.49 (P < 0.001) in the MUNW, MUOW, and MUO groups, respectively. The associated risks of early and advanced CKD were not significant in the MHOW and MHO group. MUOW and MUO were associated with higher risk of CKD compared with MHOW and MHO after adjusting other variables.

CONCLUSIONS

Metabolic abnormalities, but neither overweight nor obesity, were associated with a higher risk of CKD in adults.

High Cardiovascular Risk Profile in Young Patients on the Kidney Transplant Waiting List

BACKGROUND

Cardiovascular complications are the leading causes of morbidity and mortality in patients with end-stage renal disease. The risk profile very often contributes to their death while on the waiting list. Most studies have been carried out in older patients with end-stage renal disease, reflecting the general dialysis population. The aim of this study was to analyze the risk profile in young patients with advanced chronic kidney disease on the kidney transplant waiting list.

METHODS

This was a retrospective, single-center study of 748 patients on the kidney transplant waiting list at the University Hospital Essen, Germany. Clinical and laboratory parameters were collected between 2015 and 2016.

RESULTS

Of 748 patients (62% male), the median age was 48 years. Hypertension, coronary heart disease, and diabetes mellitus were the leading comorbidities, and their frequency rose significantly with age. Their median laboratory values did not differ significantly depending on age except for albumin. Hyperuricemia was quite common in our population with a prevalence of about 75% in women and 50% in men throughout all age groups. A total of 26.6% of the patients between 18 and 35 years of age had advanced anemia (hemoglobin < 10 g/dL), and thus they were affected most frequently. Elevated C-reactive protein serum levels were observed in 37.2% of the patients. Regarding the lipid profile, we observed that HDL cholesterol was within the normal range in only among 51.9% of men and 44.3% of women.

CONCLUSIONS

Cardiovascular risk factors are quite common in our cohort and affect young patients similarly.

Obesity and long-term mortality risk among living kidney donors

BACKGROUND

Body mass index of living kidney donors has increased substantially. Determining candidacy for live kidney donation among obese individuals is challenging because many donation-related risks among this subgroup remain unquantified, including even basic postdonation mortality.

METHODS

We used data from the Scientific Registry of Transplant Recipients linked to data from the Centers for Medicare and Medicaid Services to study long-term mortality risk associated with being obese at the time of kidney donation among 119,769 live kidney donors (1987-2013). Donors were followed for a maximum of 20 years (interquartile range 6.0-16.0). Cox proportional hazards estimated the risk of postdonation mortality by obesity status at donation. Multiple imputation accounted for missing obesity data.

RESULTS

Obese (body mass index ≥ 30) living kidney donors were more likely male, African American, and had higher blood pressure. The estimated risk of mortality 20 years after donation was 304.3/10,000 for obese and 208.9/10,000 for nonobese living kidney donors. Adjusting for age, sex, race/ethnicity, blood pressure, baseline estimated glomerular filtration rate, relationship to recipient, smoking, and year of donation, obese living kidney donors had a 30% increased risk of long-term mortality compared with their nonobese counterparts (adjusted hazard ratio: 1.32, 95% CI: 1.09-1.60, P = .006). The impact of obesity on mortality risk did not differ significantly by sex, race or ethnicity, biologic relationship, baseline estimated glomerular filtration rate, or among donors who did and did not develop postdonation kidney failure.

CONCLUSION

These findings may help to inform selection criteria and discussions with obese persons considering living kidney donation.

FATTY KIDNEY DISEASE: A NEW RENAL AND ENDOCRINE CLINICAL ENTITY? DESCRIBING THE ROLE OF THE KIDNEY IN OBESITY, METABOLIC SYNDROME, AND TYPE 2 DIABETES

Objective: To determine whether fatty kidney disease deserves be designated as a distinct clinical entity similar to fatty liver disease. Methods: Analysis and interpretation of the literature in a novel conceptual framework. Results: The kidney contributes to hyperglycemia, hypertension, inflammatory cytokines, and thus to diabetes and metabolic syndrome. Fat accumulation in and around the kidney drives this process and contributes to progression of chronic kidney disease itself. Weight loss improves these complications of fatty kidney. Diagnosis currently must be inferred from comorbidities but ultimately should be made by imaging once the importance of fatty kidney disease is established, much like fatty liver disease. Conclusion: Fatty kidney disease merits designation as a specific clinical entity similar to fatty liver disease. Greater attention to this may help encourage research into ameliorating the negative consequences of fatty kidney disease and developing new therapies. Abbreviations: BP = blood pressure; CKD = chronic kidney disease; CT = computed tomography; ESRD = end-stage renal disease; FFA = free fatty acid; FKD = fatty kidney disease; GFR = glomerular filtration rate; MetS = metabolic syndrome; MRI = magnetic resonance imaging; NAFLD = nonalcoholic fatty liver disease; RAAS = renin-angiotensin system; SGLT2 = sodium-glucose cotransporter 2; SNS = sympathetic nervous system; T2D = type 2 diabetes; TG = triglyceride.

Renal biopsy findings in patients with extreme obesity: more heterogeneous than you think

The number of obese and morbidly obese patients is increasing and so is the burden of renal disease in these patients. In a large series of biopsies from the morbidly obese patient population, Choung et al. show that there is heterogeneity in the renal disease affecting this population. It is imperative that the underlying renal disease in obese patients be correctly diagnosed for optimal management.

The spectrum of kidney biopsy findings in patients with morbid obesity

Morbid obesity, defined as body mass index (BMI) ≥40 kg/m², affects approximately 8% of United States adults and is a recognized risk factor for chronic kidney disease (CKD). We present the first focused biopsy-based study exploring the range of kidney diseases in this population. Among 3263 native kidney biopsies interpreted at Columbia University in 2017, we identified 248 biopsies from morbidly obese patients. In this cohort with median age of 53.5 years, 56% were female and median BMI was 44.0 kg/m². Diabetes and hypertension were present in 47% and 81% of patients, respectively. Median estimated glomerular filtration rate (eGFR) was 30 ml/min/1.73 m², and most patients had nephrotic range proteinuria. Obesity related glomerulopathy (ORG), defined as focal segmental glomerulosclerosis with glomerulomegaly or glomerulomegaly alone, was detected in 73 patients, including 29 with ORG alone and 44 with ORG plus another kidney disease. In contrast, 167 patients had other kidney diseases alone, without ORG, most commonly (in descending order) diabetic nephropathy, acute tubular necrosis, hypertensive nephrosclerosis, IgA nephropathy, membranous nephropathy, and lupus nephritis. In 49% of patients, kidney biopsy yielded a diagnosis predicted to change patient management. The strongest predictor of non-ORG lesions was eGFR <30 ml/min per 1.73 m², and presentation with nephrotic syndrome or acute kidney injury (with or without background CKD) was more common in non-ORG than ORG. The findings reveal an unexpectedly broad spectrum of kidney pathology beyond metabolic syndrome-associated disorders and highlight the importance of kidney biopsy to guide management and prognosis in the morbidly obese population.

Association of high body mass index with development of interstitial fibrosis in patients with IgA nephropathy

Background

The worldwide prevalence of obesity is increasing. Obesity is associated with a variety of chronic diseases, including chronic kidney disease. Several studies suggested that body mass index (BMI) could be an independent risk factor for progression of IgA nephropathy (IgAN). However, whether high BMI is associated with progression of IgAN remains uncertain.

Methods

This retrospective study included patients with biopsy proven IgAN from 2006 to 2017 in Sichuan Provincial People’s Hospital. BMI was categorized according to the WHO Asian guideline: underweight (< 18.5 kg/m²), normal weight (18.5-25 kg/m²), overweight (25-28 kg/m²) and obese (≥28 kg/m²). The main outcome was development of end-stage renal disease (ESRD) or a decline in eGFR by at least 30%. The association of BMI and IgAN progression was determined by propensity-score-matched cohort analysis.

Results

Four hundred eighty one patients with IgAN were finally enrolled in this study. The mean age was 37 ± 11 years and 40.3% were men. There was no significant difference in clinical and pathological characteristics among the four-group patients categorized by BMI. After matching with propensity scores, no significant correlation between BMI and renal outcomes was seen. However, compared with the reference group (18.5≦BMI≦25 kg/m²), being overweight (odd ratio [OR], 2.28; 95%CI: 1.06–4.88; P = 0.034) and obese (OR, 3.43; 95%CI: 1.06–11.04; P = 0.039) was associated with a high risk of interstitial fibrosis. In the cross figure demonstrating the association of BMI subgroup and interstitial fibrosis on renal outcomes, ORs of interstitial fibrosis groups were higher than those of no interstitial fibrosis. Compared with other BMI subgroups, patients with 18.5-25 kg/m² had lowest ORs.

Conclusions

High BMI and interstitial fibrosis were associated with progression of IgAN. Interstitial fibrosis appears to be common in IgAN patients with elevated BMI.

Changes in obese metabolic phenotypes over time and risk of incident chronic kidney disease

AIM

To examine the association between metabolically healthy obese (MHO) phenotype and incident chronic kidney disease (CKD) and study whether changes in metabolic phenotypes over time could affect CKD risk.

METHODS

A total of 8589 subjects from the Korean Genome and Epidemiology Study were categorized into four groups based on the presence of obesity and metabolic abnormalities (MA). The primary endpoint was an onset of incident CKD defined as an estimated glomerular filtration rate of ≤ 60 mL/min/1.73 m² . Multivariable Cox analysis and time-varying Cox analysis were performed to delineate the relationship between obese metabolic phenotypes and incident CKD after adjustment for sociodemographic factors and clinical and laboratory parameters.

RESULTS

During a mean follow-up duration of 9.3 years, CKD occurred in 782 (9.1%) participants. In the multivariable Cox model, the hazard ratio (HR) for incident CKD in the MHO, metabolically abnormal non-obese (MANO), and metabolically abnormal obese (MAO) groups was 1.42 (P = 0.002), 1.45 (P < 0.001), and 1.77 (P < 0.001), respectively, compared with the metabolically healthy non-obese (MHNO) group. Time-varying analysis with these four phenotypes as time-varying exposures showed the same results. Furthermore, subjects with persistent MHO through follow-up were at a 2.0-fold increased risk of CKD (P < 0.001). 41.0% of subjects experienced phenotype changes during follow-up. Over the long term, the MHO group had a higher proportion of transition to the MA phenotype and unfavourable metabolic profiles than the MHNO group. Among MHO subjects, those who transitioned to MAO were at a 4.1-fold increased risk of incident CKD than those who regressed to MHNO. In addition, transition to MHO from other groups carried a higher risk of CKD than persistent MHNO.

CONCLUSION

MHO subjects are at increased risk for incident CKD.

Losartan Alleviates Renal Fibrosis and Inhibits Endothelial-to-Mesenchymal Transition (EMT) Under High-Fat Diet-Induced Hyperglycemia

The endothelial-to-mesenchymal transition (EMT) of glomerular vascular endothelial cells is considered to be pivotal in diabetic nephropathy (DN). The risk of DN can be decreased by losartan, but the potential molecular mechanism(s) are not fully understood. Extensive data show that the EMT occurs in proximal tubular endothelial cells resulting in an endothelial phenotype switch (fibrotic matrix accumulation), consequently enhancing the development of renal interstitial fibrosis. Here, we found that losartan significantly ameliorated DN-induced renal fibrosis progression via inhibition of the EMT in mice. In vivo experiments suggested that losartan significantly alleviated microalbuminuria and pathologic changes under high-fat diet-induced hyperglycemia. Immunohistochemistry indicated that losartan suppressed the EMT in glomeruli. In addition, losartan decreased oxidative stress damage and inhibited the transforming growth factor (TGF)-β1/Smad pathway. Furthermore, consistent changes were detected in vitro where losartan markedly inhibited the EMT and TGF-β1/Smad pathway induced by high glucose in glomerular endothelial cells. Together, these results suggested that losartan could alleviate the EMT in glomeruli via inhibition of oxidative stress damage and the TGF-β1/Smad signaling pathway under hyperglycemia.

Long-term risk for end-stage kidney disease and death in a large population-based cohort

Knowledge of metabolic risk factors for end-stage kidney disease (ESKD) in the general population is limited when considering the competing event death in risk analysis. The aim of our prospective observational study was to investigate how blood pressure and metabolic factors might influence the risks for ESKD and death before ESKD in a large Austrian population-based cohort with long-term follow-up. 177,255 participants (53.8% women; mean age 42.5 years) were recruited between 1988 and 2005 and linked to the Austrian Dialysis and Transplant Registry and the National Mortality Registry. Over a mean follow-up of 16 years 358 participants reached ESKD and 19,512 participants died. Applying fully adjusted cause-specific Cox proportional hazards models elevated fasting blood glucose, hypertension, hypertrigylceridemia and hypercholesterolemia were associated with a higher relative risk for ESKD than for death before ESKD, whereas elevated γ-glutamyltransferase was associated with an increased relative risk of death but not ESKD. Results were similar using continuous or categorical exposure variable measures in the general cohort but differed in selected high-risk populations. These findings might help improve the design of renal risk factor modification trials and kidney disease awareness and prevention programs in the general population, which may ultimately decrease the burden of ESKD.

Relationship between body mass index and renal function deterioration among the Taiwanese chronic kidney disease population

This study investigated the characteristics of patients with different chronic kidney disease (CKD) stages according to various body mass index (BMI) categories and determined the influence of BMI in renal function deterioration. We conducted a multicenter, longitudinal cohort study based on the Epidemiology and Risk Factors Surveillance of CKD project (2008–2013) and National Health Insurance Research Database (2001–2013). A total of 7357 patients with CKD aged 20–85 years from 14 hospitals were included in the study. A higher male sex, diabetes mellitus (DM) and hypertension were noted among overweight and obese CKD patients, while more cancer prevalence was noted among underweight CKD patients. Charlson comorbidity index was significantly higher and correlated with BMI among late CKD patients. Patients with BMI < 18.5 kg/m² exhibited non-significantly higher events of eGFR decline events in both early and late CKD stages than other BMI groups. BMI alone is not a determinant of CKD progression among our Taiwanese CKD patients. Obesity should be re-defined and body weight manipulation should be individualized in CKD patients.