Obesity and renal disease: not all fat is created equal and not all obesity is harmful to the kidneys

The Impact of Exercise Training Plus Dietary Interventions on Ectopic Fat in Population with Overweight/Obesity with and without Chronic Disease: A Systematic Review, Meta-analysis, and Metaregression of Randomized Clinical Trials

Background

The growing prevalence of obesity and related chronic diseases has led to increased interest in interventions targeting ectopic fat reduction to which its accumulation is linked to metabolic dysfunction.

Objectives

This study aimed to evaluate the effects of combined exercise training combined with dietary interventions compared with dietary interventions alone on ectopic fat [visceral fat area (VFA), liver fat, intramuscular fat (IMF), pancreatic fat, renal sinus fat, and pericardial and epicardial fats] in adults with overweight and obesity, both with and without chronic diseases.

Methods

Web of Science, Scopus, and PubMed were searched for original articles up to 1 March, 2024, that included exercise compared with control interventions on body weight and ectopic fat in adults with overweight or obesity. Weighted mean differences (WMD) for body weight, liver fat, pancreatic fat, and renal sinus fat and standardized mean differences (SMD) for VFA, IMF, pericardial and epicardial fats, and 95% confidence intervals were determined using random-effects models.

Results

Thirty-two studies, including 1488 participants and 38 intervention groups, met the inclusion criteria. The combined intervention of exercise and diet did not reduce body weight (WMD = -0.23 kg, P = 0.180), liver fat (WMD = 0.05%, P = 0.730), IMF (SMD = -0.08, P = 0.640), pericardial and epicardial fats (SMD = -0.12, P = 0.280), pancreatic fat (WMD = -0.24%, P = 0.370), and renal sinus fat (WMD = 0.01 cm2, P = 0.170) when compared with a diet-only group. Interestingly, exercise combined with diet significantly reduced VFA in participants with obesity (SMD = -0.12, P = 0.040) and healthy males (SMD = -0.33, P = 0.001) when compared with a diet-only group.

Conclusions

The findings suggest that combined exercise and dietary interventions did not lead to significant reductions in most ectopic fat depots when compared with diet alone. However, a modest reduction in VFA was observed in participants with obesity and healthy males. These results highlight the nuanced impact of exercise in combination with dietary interventions and the need to consider specific fat depots and participant characteristics in obesity management strategies.The trial was registered at PROSPERO as CRD42024546770.

Preliminary quantitative analysis of renal sinus fat dysfunction in T2DM patients using MRI fat fraction and R2* mapping

Purpose

To quantitatively analyze renal sinus fat (RSF) dysfunction in type 2 diabetes mellitus (T2DM) patients using magnetic resonance imaging (MRI) fat fraction (FF) and R2* mapping.

Methods

The inpatients who underwent 1.5 T MRI examination (including MRI FF and R2* mapping) of the abdomen from January 2017 to December 2023 were enrolled. The RSF volume, FF and R2* of the right and left kidneys and the mean values were measured. Associations between mean FF and R2* value of RSF and T2DM were assessed with logistic regression. Receiver operating characteristic (ROC) curve was applied to calculate area under the curve (AUC) for the parameters to identify T2DM patients. Partial correlation coefficients after controlling for age, sex, and BMI were computed to analyze the correlations among the mean RSF volume, FF and R2*.

Results

A total of 186 participants were finally enrolled in this study including 38 patients in T2DM group and 148 patients in non-T2DM group. Univariate logistic regression analyses showed the significant correlations of mean RSF FF (OR: 1.111, 95%CI: 1.054 - 1.171), P < 0.001) and R2* (OR: 1.120, 95%CI: 1.013 - 1.237), P = 0.027) with T2DM. Multivariate analysis showed that mean RSF FF (OR: 1.231, 95% CI: 1.098 - 1.380) is independently associated with T2DM after adjusting for age, sex and BMI. The AUC of mean RSF FF was 0.701 (0.630 - 0.766) with the sensitivity and specificity of 57.89% and 75.68%, respectively, when using 34.40% as the cut-off value. The AUC of mean RSF R2* was 0.616 (0.542 - 0.686) with the sensitivity and specificity of 68.42% and 58.11%, respectively, when using 21.97 Hz as the cut-off value. Furthermore, mean RSF FF presents significantly higher diagnostic efficacy for T2DM than R2* (P < 0.05). And combining mean RSF FF and R2* improved the diagnostic performance (AUC = 0.729).

Conclusion

Mean RSF FF and R2* were significantly associated with T2DM, and mean RSF FF was the independent risk factor of T2DM. This finding indicates the hypertrophy of adipocytes and excessive iron deposition and hypoxia in RSF, which may represent dysfunction of RSF for T2DM.

Longitudinal relationship between baseline Weight-Adjusted Waist Index and stroke risk over 8 years in Chinese adults aged 45 and older: a prospective cohort study

Background

This study explores the longitudinal relationship between the Weight-Adjusted Waist Index (WWI), an innovative obesity metric, and stroke incidence in aged 45 and older Chinese adults.

Methods

Data from 9,725 individuals aged 45 years and older were analyzed from the China Health and Retirement Longitudinal Study (2011-2020). Baseline characteristics were analyzed across different quartiles of the WWI. Stroke incidents were determined through self-reported doctor diagnoses. Multivariate logistic regression analyses and curve fitting assessed the WWI-stroke risk relationship, adjusting for various demographic, lifestyle, and health-related factors.

Results

Higher WWI quartiles were associated with older age and higher prevalence of stroke and adverse health conditions. In the fully adjusted model, participants in the highest WWI quartile had an odds ratio of 1.52 (95% CI: 1.19, 1.92) for stroke compared to the lowest quartile. Curve fitting revealed a linear relationship between WWI and stroke risk, consistent across various demographic and clinical subgroups.

Conclusion

Higher WWI is linked to an increased risk of stroke in aged 45 and older Chinese adults over an eight-year period. WWI may serve as an effective tool for predicting long-term stroke risk within this population. However, the study is limited by the reliance on self-reported stroke diagnoses and the presence of potential residual confounding factors.

Association between the lipid accumulation product and chronic kidney disease among adults in the United States

The objective of this research was to explore the potential association between lipid accumulation product (LAP) and chronic kidney disease (CKD) among adult population of United States (US). Using cross-sectional data from the 2013 to 2018 National Health and Nutrition Examination Survey (NHANES), we explored the association of LAP with CKD, low estimated glomerular filtration rate (eGFR), and albuminuria. This analysis encompassed multivariate logistic regression analyses, smoothed curve fitting, subgroup analyses, and interaction tests. We found a significant positive association between higher ln-transformed LAP (LAP was transformed using a natural logarithm) and the prevalence of CKD, low-eGFR and albuminuria. Notably, this association of ln-transformed LAP with CKD and albuminuria was significantly influenced by diabetes status and sex (P for interaction < 0.05), while no significant interaction was observed regarding the association with low-eGFR (P for interaction > 0.05). Additionally, in model 3 (adjusted for all included covariates except eGFR and urinary albumin-creatinine ratio (UACR)), a nonlinear relationship was identified between ln-transformed LAP and the presence of both CKD and albuminuria, with inflection points of 4.57 and 4.49, respectively. This indicates that this correlation is more pronounced on the right of the inflection point. In conclusion, the findings indicate a significant association between LAP and the prevalence of CKD in US adults.

Cardiometabolic comorbidities and complications of obesity and chronic kidney disease (CKD)

Obesity and chronic kidney disease are two ongoing progressive clinical pandemics of major public health and clinical care significance. Because of their growing prevalence, chronic indolent course and consequent complications both these conditions place significant burden on the health care delivery system especially in developed countries like the United States. Beyond the chance coexistence of both of these conditions in the same patient based on high prevalence it is now apparent that obesity is associated with and likely has a direct causal role in the onset, progression and severity of chronic kidney disease. The causes and underlying pathophysiology of this are myriad, complicated and multi-faceted. In this review, continuing the theme of this special edition of the journal on " The Cross roads between Endocrinology and Nephrology" we review the epidemiology of obesity related chronic kidney disease (ORCKD), and its various underlying causes and pathophysiology. In addition, we delve into the consequent comorbidities and complications associated with ORCKD with particular emphasis on the cardio metabolic consequences and then review the current body of evidence for available strategies for chronic kidney disease modulation in ORCKD as well as the potential unique role of weight reduction and management strategies in its improvement and risk reduction.

Obesity Metabolic Phenotypes and Unplanned Readmission Risk in Diabetic Kidney Disease: An Observational Study from the Nationwide Readmission Database

BACKGROUND AND AIM

Obesity is a potentially modifiable factor for reducing readmissions, with heterogeneity that varies according to the metabolic status. Our objective was to examine the independent or mutual relationship between obesity and metabolic abnormalities and diabetic kidney disease (DKD)-related hospitalizations.

METHODS

493,570 subjects with DKD were enrolled in the 2018 Nationwide Readmission Database (NRD, United States). The at-risk population was reclassified into refined obesity subtypes based on the body mass index (BMI) classification of metabolic abnormalities (hypertension and/or dyslipidemia) to investigate the 180 d readmission risk and hospitalization costs related to DKD.

RESULTS

The overall readmission rate was 34.1%. Patients with metabolic abnormalities, regardless of obesity, had a significantly higher risk of readmission compared to non-obese counterparts (adjusted HR, 1.11 [95% CI, 1.07-1.14]; 1.12 [95% CI, 1.08-1.15]). Hypertension appeared to be the only metabolic factor associated with readmission among individuals with DKD. Obesity without metabolic abnormalities was independently associated with readmission (adjusted HR,1.08 [1.01,1.14]), especially among males and those >65 years (adjusted HR,1.10 [1.01-1.21]; 1.20 [1.10-1.31]). Women or those ≤65 years with metabolic abnormalities (all p <0.050) had elevated readmission rates, regardless of obesity; however, no such trend was observed in obese subjects without metabolic abnormalities (adjusted HR, 1.06 [0.98,1.16]). Additionally, obesity and metabolic abnormalities were associated with elevated hospitalization costs (all p <0.0001).

CONCLUSIONS

Increased BMI and hypertension are positively associated with readmissions and related costs among patients with DKD, which should be considered in future studies.

Urgent needs of caregiving in ageing populations with Alzheimer's disease and other chronic conditions: Support our loved ones

The ageing process begins at birth. It is a life-long process, and its exact origins are still unknown. Several hypotheses attempt to describe the normal ageing process, including hormonal imbalance, formation of reactive oxygen species, DNA methylation & DNA damage accumulation, loss of proteostasis, epigenetic alterations, mitochondrial dysfunction, senescence, inflammation, and stem cell depletion. With increased lifespan in elderly individuals, the prevalence of age-related diseases including, cancer, diabetes, obesity, hypertension, Alzheimer's, Alzheimer's disease and related dementias, Parkinson's, and other mental illnesses are increased. These increased age-related illnesses, put tremendous pressure & burden on caregivers, family members, and friends who are living with patients with age-related diseases. As medical needs evolve, the caregiver is expected to experience an increase in duties and challenges, which may result in stress on themselves, and impact their own family life. In the current article, we assess the biological mechanisms of ageing and its effect on body systems, exploring lifestyle and ageing, with a specific focus on age-related disorders. We also discussed the history of caregiving and specific challenges faced by caregivers in the presence of multiple comorbidities. We also assessed innovative approaches to funding caregiving, and efforts to improve the medical system to better organize chronic care efforts, while improving the skill and efficiency of both informal and formal caregivers. We also discussed the role of caregiving in end-of-life care. Our critical analysis strongly suggests that there is an urgent need for caregiving in aged populations and support from local, state, and federal agencies.

Extracellular Matrix Expression in Human Pancreatic Fat Cells of Patients with Normal Glucose Regulation, Prediabetes and Type 2 Diabetes

Previously, we found that human pancreatic preadipocytes (PPAs) and islets influence each other and that the crosstalk with the fatty liver via the hepatokine fetuin-A/palmitate induces inflammatory responses. Here, we examined whether the mRNA-expression of pancreatic extracellular matrix (ECM)-forming and -degrading components differ in PPAs from individuals with normal glucose regulation (PPAs-NGR), prediabetes (PPAs-PD), and type 2 diabetes (PPAs-T2D), and whether fetuin-A/palmitate impacts ECM-formation/degradation and associated monocyte invasion. Human pancreatic resections were analyzed (immuno)histologically. PPAs were studied for mRNA expression by real-time PCR and protein secretion by Luminex analysis. Furthermore, co-cultures with human islets and monocyte migration assays in Transwell plates were conducted. We found that in comparison with NGR-PPAs, TIMP-2 mRNA levels were lower in PPAs-PD, and TGF-β1 mRNA levels were higher in PPAs-T2D. Fetuin-A/palmitate reduced fibronectin, decorin, TIMP-1/-2 and TGF-ß1 mRNA levels. Only fibronectin was strongly downregulated by fetuin-A/palmitate independently of the glycemic status. Co-culturing of PPAs with islets increased TIMP-1 mRNA expression in islets. Fetuin-A/palmitate increased MMP-1, usherin and dermatopontin mRNA-levels in co-cultured islets. A transmigration assay showed increased monocyte migration towards PPAs, which was enhanced by fetuin-A/palmitate. This was more pronounced in PPAs-T2D. The expression of distinct ECM components differs in PPAs-PD and PPAs-T2D compared to PPAs-NGR, suggesting that ECM alterations can occur even in mild hyperglycemia. Fetuin-A/palmitate impacts on ECM formation/degradation in PPAs and co-cultured islets. Fetuin-A/palmitate also enhances monocyte migration, a process which might impact on matrix turnover.

The heterogeneity of metabolic syndrome presentation and challenges this causes in its pharmacological management: a narrative review focusing on principal risk modifiers

INTRODUCTION

Metabolic syndrome (MetS), i.e. the cluster of cardiometabolic risk factors comprising visceral obesity, impaired glucose metabolism, arterial hypertension and atherogenic dyslipidemia, is prevalent globally and exacts a heavy toll on health care expenditures.

AREAS COVERED

The pathophenotypes of individual traits of the MetS in adults are discussed first, with strong emphasis on nonalcoholic fatty liver disease (NAFLD) and sex differences. Next, I discuss recent studies on phenotypic and outcome heterogeneity of the MetS, highlighting the role of NAFLD, sex, reproductive status, and depressive disorders. In the second half of the article, the therapeutic implications of the variable MetS types and features are analyzed, focusing on the most recent developments, and guidelines.

EXPERT OPINION

I have identified physiological, pathological, social and medical sources of phenotypical heterogeneity in the MetS and its constitutive traits. Improved understanding of these variables may be utilized in the setting of future precision medicine approaches in the field of metabolic disorders and target organ damage.

Diagnostic value of visceral adiposity index in chronic kidney disease: a meta-analysis

AIMS

Several studies have revealed inconsistencies about the predictive properties of visceral adiposity index (VAI) in identifying chronic kidney disease (CKD). To date, it is unclear whether the VAI is a valuable diagnostic tool for CKD. This study intended to evaluate the predictive properties of the VAI in identifying CKD.

METHODS

The PubMed, Embase, Web of Science, and Cochrane databases were searched for all studies that met our criteria from the earliest available article until November 2022. Articles were assessed for quality using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). The heterogeneity was explored with the Cochran Q test and I² test. Publication bias was detected using Deek's Funnel plot. Review Manager 5.3, Meta-disc 1.4, and STATA 15.0 were used for our study.

RESULTS

Seven studies involving 65,504 participants met our selection criteria and were therefore included in the analysis. Pooled sensitivity (Sen), specificity (Spe), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and area under the curve (AUC) were 0.67 (95%CI: 0.54-0.77), 0.75 (95%CI: 0.65-0.83), 2.7 (95%CI: 1.7-4.2), 0.44 (95%CI: 0.29-0.66), 6 (95%CI:3.00-14.00) and 0.77 (95%CI: 0.74-0.81), respectively. Subgroup analysis indicated that mean age of subjects was the potential source of heterogeneity. The Fagan diagram found that the predictive properties of CKD were 73% when the pretest probability was set to 50%.

CONCLUSIONS

The VAI is a valuable agent in predicting CKD and may be helpful in the detection of CKD. More studies are needed for further validation.

Obesity-Related Chronic Kidney Disease: Principal Mechanisms and New Approaches in Nutritional Management

Obesity is the epidemic of our era and its incidence is supposed to increase by more than 30% by 2030. It is commonly defined as a chronic and metabolic disease with an excessive accumulation of body fat in relation to fat-free mass, both in terms of quantity and distribution at specific points on the body. The effects of obesity have an important impact on different clinical areas, particularly endocrinology, cardiology, and nephrology. Indeed, increased rates of obesity have been associated with increased risk of cardiovascular disease (CVD), cancer, type 2 diabetes (T2D), dyslipidemia, hypertension, renal diseases, and neurocognitive impairment. Obesity-related chronic kidney disease (CKD) has been ascribed to intrarenal fat accumulation along the proximal tubule, glomeruli, renal sinus, and around the kidney capsule, and to hemodynamic changes with hyperfiltration, albuminuria, and impaired glomerular filtration rate. In addition, hypertension, dyslipidemia, and diabetes, which arise as a consequence of overweight, contribute to amplifying renal dysfunction in both the native and transplanted kidney. Overall, several mechanisms are closely related to the onset and progression of CKD in the general population, including changes in renal hemodynamics, neurohumoral pathways, renal adiposity, local and systemic inflammation, dysbiosis of microbiota, insulin resistance, and fibrotic process. Unfortunately, there are no clinical practice guidelines for the management of patients with obesity-related CKD. Therefore, dietary management is based on the clinical practice guidelines for the nutritional care of adults with CKD, developed and published by the National Kidney Foundation, Kidney Disease Outcome Quality Initiative and common recommendations for the healthy population. Optimal nutritional management of these patients should follow the guidelines of the Mediterranean diet, which is known to be associated with a lower incidence of CVD and beneficial effects on chronic diseases such as diabetes, obesity, and cognitive health. Mediterranean-style diets are often unsuccessful in promoting efficient weight loss, especially in patients with altered glucose metabolism. For this purpose, this review also discusses the use of non-classical weight loss approaches in CKD, including intermittent fasting and ketogenic diet to contrast the onset and progression of obesity-related CKD.

Association of weight-adjusted-waist index with all-cause and cardiovascular mortality in China: A prospective cohort study

BACKGROUND AND AIMS

As a new simple anthropometric index, the weight-adjusted-waist index (WWI) appears to be superior to body mass index (BMI) and waist circumference (WC) in assessing both muscle and fat mass. We aimed to explore the association of WWI with all-cause and cardiovascular mortality in southern China.

METHODS AND RESULTS

A total of 12,447 participants (mean age, 59.0 ± 13.3 years; 40.6% men) in Jiangxi Province from the China Hypertension Survey study were included. WWI was defined as WC divided by the square root of weight. The outcome was all-cause and cardiovascular mortality. During a median follow-up of 5.6 years, 838 all-cause deaths occurred, with 390 cardiovascular deaths. Overall, there was a nonlinear positive relationship of WWI with all-cause and cardiovascular mortality. Accordingly, compared with participants in quartiles 1-3 (<11.2 cm/√kg), a significant higher risk of all-cause mortality (HR: 1.36, 95% CI: 1.17, 1.58) and cardiovascular mortality (HR: 1.43, 95% CI: 1.15, 1.77) were found in quartile 4 (≥11.2 cm/√kg). Further adjustment for BMI and WC did not substantially alter the results. No significant interactions were found in any of the subgroups (sex, age, area, physical activity, current smoking, current alcohol drinking, hypertension, and stroke).

CONCLUSION

Higher WWI levels (≥11.2 cm/√kg) were associated with increased the risk of all-cause and cardiovascular mortality in southern China. These findings, if confirmed by further studies, suggested that WWI may serve as a simple and effective anthropometric index in clinical practice.

Changes in Kidney Fat upon Dietary-Induced Weight Loss

As the metabolic role of kidney fat remains unclear, we investigated the effects of dietary weight loss on kidney fat content (KFC) and its connection to kidney function and metabolism. Overweight or obese participants (n = 137) of a dietary intervention trial were classified into quartiles of weight loss in a post hoc manner. Kidney sinus (KSF) and cortex fat (KCF) were measured by magnetic resonance imaging at baseline, week 12 and week 50. Weight loss effects on KFC were evaluated by linear mixed models. Repeated measures correlations between KFC, other body fat measures and metabolic biomarkers were obtained. KSF, but not KCF, decreased significantly across weight loss quartiles at week 12 (quartile 4: -21.3%; p = 0.02) and 50 (-22.0%, p = 0.001), which remained significant after adjusting for VAT. There were smaller improvements regarding creatinine (-2.5%, p = 0.02) at week 12, but not week 50. KSF, but not KCF, correlated with visceral (r_rm = 0.38) and subcutaneous fat volumes (r_rm = 0.31) and liver fat content (r_rm = 0.32), as well as diastolic blood pressure and biomarkers of lipid, glucose and liver metabolism. Dietary weight loss is associated with decreases in KSF, but not KCF, which suggests that KSF may be the metabolically relevant ectopic fat depot of the kidney. KSF may be targeted for obesity-related disease prevention.

Obesity Without Metabolic Abnormality and Incident CKD: A Population-Based British Cohort Study

RATIONALE & OBJECTIVE

Metabolically healthy obesity (obesity without any metabolic abnormality) is not considered to be associated with increased risk of morbidity and mortality. We examined and quantified the association between metabolically healthy overweight/obesity and the risk of incident chronic kidney disease (CKD) in a British primary care population.

STUDY DESIGN

Retrospective population-based cohort study.

SETTING & PARTICIPANTS

4,447,955 of the 5,182,908 adults in The Health Improvement Network (THIN) database (United Kingdom, 1995-2015) with a recorded body mass index (BMI) at the time of registration date who were free of CKD and cardiovascular disease.

EXPOSURE

11 body size phenotypes were created, defined by BMI categories (underweight, normal weight, overweight, and obesity) and 3 metabolic abnormalities (diabetes, hypertension, and dyslipidemia).

OUTCOME

Incident CKD defined as a recorded code for kidney replacement therapy, a recorded diagnosis of CKD, or by an estimated glomerular filtration rate of<60mL/min/1.73m² for≥90 days, or a urinary albumin-creatinine ratio>3mg/mmol for≥90 days.

RESULTS

Of the 4.5 million individuals, 1,040,921 (23.4%) and 588,909 (13.2%) had metabolically healthy overweight and metabolically healthy obesity, respectively. During a mean follow-up interval of 5.4±4.3 (SD) years, compared with individuals with a metabolically healthy normal weight (n=1,656,231), there was a higher risk of incident CKD among those who had metabolically healthy overweight (adjusted HR, 1.30 [95% CI, 1.28-1.33]) and metabolically healthy obesity (adjusted HR, 1.66 [95% CI, 1.62-1.70]). The association was stronger in those younger than 65 years of age. In all BMI categories, there was greater risk of incident CKD with a greater number of metabolic abnormalities in a graded manner.

LIMITATIONS

Potential misclassification of metabolic status due to delayed diagnosis and residual confounding due to unmeasured factors.

CONCLUSIONS

Overweight and obesity without metabolic abnormality are associated with a higher risk of incident CKD compared with those with normal body weight and no metabolic abnormality.

Promoting resolution in kidney disease: are we nearly there yet?

PURPOSE OF REVIEW

Nephrology lacks effective therapeutics for many of the presentations and diseases seen in clinical practice. In recent decades, we have come to understand the central place of inflammation in initiating and propagating kidney disease, and, research in more recent years has established that the resolution of inflammation is a highly regulated and active process. With this, has evolved an appreciation that this aspect of the host inflammatory response is defective in kidney disease and led to consideration of a therapeutic paradigm aiming to harness the activity of the molecular drivers of the resolution phase of inflammation. Fatty-acid-derived Specialized pro-resolving mediators (SPMs), partly responsible for resolution of inflammation have gained traction as potential therapeutics.

RECENT FINDINGS

We describe our current understanding of SPMs for this purpose in acute and chronic kidney disease. These studies cement the place of inflammation and its defective resolution in the pathogenesis of kidney disease, and highlight new avenues for therapy.

SUMMARY

Targeting resolution of inflammation is a viable approach to treating kidney disease. We optimistically look forward to translating these experimental advances into tractable therapeutics to treat kidney disease.

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.

Obesity, transplantation, and bariatric surgery: An evolving solution for a growing epidemic

The increasing obesity epidemic has major implications in the realm of transplantation. Patients with obesity face barriers in access to transplant and unique challenges in perioperative and postoperative outcomes. Because of comorbidities associated with obesity, along with the underlying end-stage organ disease leading to transplant candidacy, these patients may not even be referred for transplant evaluation, much less be waitlisted or actually undergo transplant. However, the use of bariatric surgery in this population can help optimize the transplant candidacy of patients with obesity and end-stage organ disease and improve perioperative and postoperative outcomes. We review the impact of obesity on kidney, liver, and cardiothoracic transplant candidates and recipients and explore potential interventions to address obesity in these populations.

Relationship of visceral adiposity index with new-onset proteinuria in hypertensive patients

BACKGROUND & AIMS

Visceral adiposity index (VAI) is a sex-specific surrogate marker of adipose tissue distribution and function. Little is known about the longitudinal relationship between VAI and proteinuria. This study aimed to examine the prospective relationship of baseline VAI with new-onset of proteinuria in hypertensive patients without major cardiovascular diseases.

METHODS

A total of 10 699 hypertensive patients without proteinuria (negative urine dipstick reading) at baseline from the renal sub-study of the China Stroke Primary Prevention Trial (CSPPT) were included. Participants were randomly assigned to a double-blind daily treatment with 10 mg enalapril and 0.8 mg folic acid or 10 mg enalapril alone. Participants were followed every 3 months after randomization. The primary outcome was new-onset proteinuria, defined as a urine dipstick reading of ≥1+ at the exit visit. The secondary outcome was progression of proteinuria, defined as a urine dipstick reading of trace or ≥1+ at the exit visit.

RESULTS

During a median follow-up duration of 4.4 years, a total of 396 (3.7%) participants developed new-onset proteinuria, while 1236 (11.6%) participants met progression of proteinuria. When VAI was categorized into quartiles, compared with participants in quartile 1-3 (<2.99), a significantly higher risk of new-onset proteinuria (OR, 1.43; 95%CI: 1.07-1.91) and progression of proteinuria (OR, 1.23; 95%CI: 1.03-1.46) was found in those in quartile 4 (≥2.99). Moreover, the positive association was consistent in participants with or without general obesity, abdominal obesity, and dyslipidemia (all P-interactions > 0.05).

CONCLUSIONS

There was a positive association between VAI levels and the risk of new-onset proteinuria in hypertensive patients.

Impact of Transition in Metabolic Health and Obesity on the Incident Chronic Kidney Disease: A Nationwide Cohort Study

CONTEXT

Metabolically healthy obesity (MHO) is a dynamic condition.

OBJECTIVE

To evaluate the risk of chronic kidney disease (CKD) among people with MHO according to its longitudinal change.

DESIGN

Observational study.

SETTING

A nationwide population-based cohort.

PARTICIPANTS

A total of 514 866 people from the Korean National Health Insurance Service-National Sample Cohort.

INTERVENTION

The initial presence and changes of obesity (using body mass index [BMI] and waist circumference [WC]) and metabolic health status.

MAIN OUTCOME MEASURE

Incident CKD from 2011 to 2015.

RESULTS

Of the people classified as MHO at baseline (BMI criteria), 47.6% remained as MHO in 2011 and 2012, whereas 12.1%, 5.5%, and 34.8% were classified as metabolically healthy, non-obese (MHNO), metabolically unhealthy, non-obese, and metabolically unhealthy, obese, respectively. The risk of incident CKD in the baseline MHO group was higher than that in the MHNO group (hazard ratio, 1.23; 95% confidence interval, 1.12-1.36). However, when transition was taken into account, people who converted to MHNO were not at increased risk (hazard ratio, 0.98; 95% confidence interval, 0.72-1.32), whereas the stable MHO group and the groups that evolved to metabolically unhealthy status had a higher risk of incident CKD than the stable MHNO group. When the risk was analyzed using WC criteria, it showed a similar pattern to BMI criteria except for the stable MHO group.

CONCLUSIONS

MHO was a dynamic condition, and people with MHO constituted a heterogeneous group. Although the MHO phenotype was generally associated with incident CKD, maintenance of metabolic health and weight reduction might alleviate the risk of CKD.

Impact of different ectopic fat depots on cardiovascular and metabolic diseases

A growing body of evidence is pointing out the pathophysiological role of fat accumulation in different organs. Ectopic fat depots within heart, liver, skeletal muscle, kidney, and pancreas as well as around blood vessels might be more associated to cardiometabolic risk than classical variables, such as body mass index. Among different mechanisms, lipid metabolism appears to be particularly influenced by ectopic fat depots. Indeed, intracellular accumulation of nonesterified fatty acids, and triglycerides promotes endoplasmic reticulum stress, mitochondrial uncoupling, oxidative stress, and altered membrane composition/function, finally promoting inflammatory response and cell death. The dysfunctional adipose tissue was shown to induce both local and systemic effects, with relevant clinical consequences. Epicardial fat and myocardial steatosis have been associated with the development of atrial fibrillation and ventricular dysfunction. Similarly perivascular adipose tissue appears to trigger atherosclerosis and hypertension. Nonalcoholic fatty liver disease has been recognized both as the hepatic manifestation of metabolic syndrome and as a cardiovascular (CV) risk factor. Importantly, the renal sinus fat emerged as a potential player in kidney dysfunction. Finally, both skeletal muscle and pancreatic fat depots have been indicated as potential endocrine modulators of insulin resistance. Considering the global rise in the prevalence of obesity, the understanding of mechanisms underlying ectopic fat accumulation represents an urgent need, with potential clinical implications for CV risk stratification. Here, we attempt to update the current knowledge of the different ectopic fat depots, focusing on underlying mechanisms and potential clinical implications.

Association of longitudinal risk profile trajectory clusters with adipose tissue depots measured by magnetic resonance imaging

The objective of the study was to identify associations of longitudinal trajectories of traditional cardiometabolic risk factors with abdominal and ectopic adipose tissue depots measured by magnetic resonance imaging (MRI). We measured total abdominal, visceral, and subcutaneous adipose tissue in liter and intrahepatic, intrapancreatic and renal sinus fat as fat fractions by MRI in 325 individuals free of cardiovascular disease at Exam 3 of a population-based cohort. We related these MRI measurements at Exam 3 to longitudinal risk profile trajectory clusters, based on risk factor measurements from Exam 3, Exam 2 (seven years prior to MRI) and Exam 1 (14 years prior to MRI). Based on the levels and longitudinal trajectories of several risk factors (blood pressure, lipid profile, anthropometric measurements, HbA1c), we identified three different trajectory clusters. These clusters displayed a graded association with all adipose tissue traits after adjustment for potential confounders (e.g. visceral adipose tissue: β_ClusterII = 1.30 l, 95%-CI:[0.84 l;1.75 l], β_ClusterIII = 3.32 l[2.74 l;3.90 l]; intrahepatic: Estimate_ClusterII = 1.54[1.27,1.86], Estimate_ClusterIII = 2.48[1.93,3.16]. Associations remained statistically significant after additional adjustment for the risk factor levels at Exam 1 or Exam 3, respectively. Trajectory clusters provided additional information in explaining variation in the different fat compartments beyond risk factor profiles obtained at individual exams. In conclusion, sustained high risk factor levels and unfavorable trajectories are associated with high levels of adipose tissue; however, the association with cardiometabolic risk factors varies substantially between different ectopic adipose tissues. Trajectory clusters, covering longitudinal risk profiles, provide additional information beyond single-point risk profiles. This emphasizes the need to incorporate longitudinal information in cardiometabolic risk estimation.

Cardiovascular risk in chronic kidney disease: what is new in the pathogenesis and treatment?

The prevalence of chronic kidney disease (CKD) has increased markedly over past decades due to the aging of the worldwide population. Despite the progress in the prevention and treatment, the cardiovascular (CV) morbidity and mortality remain high among patients with CKD. Although CKD is a progressive and irreversible condition, it is possible to slow decreasing kidney function, as well as the development and progression of associated with kidney disease comorbidities. Diabetes mellitus has become major cause of CKD worldwide. It is estimated that the prevalence of diabetes will increase from 425 million worldwide in 2017 to 629 million by 2045, substantially the percentage of diabetic nephropathy among CKD patients is set to rise markedly. The results of multicenter trials concerning novel antidiabetic drugs suggest that efficacy in reducing CV risk is independent of the improvement in glycemic control. This review discusses underlying causes of high CV risk and strategies reducing individual burden among CKD patients.

The protective effect of human renal sinus fat on glomerular cells is reversed by the hepatokine fetuin-A

Renal sinus fat (RSF) is a perivascular fat compartment located around renal arteries. In this in vitro and in vivo study we hypothesized that the hepatokine fetuin-A may impair renal function in non alcoholic fatty liver disease (NAFLD) by altering inflammatory signalling in RSF. To study effects of the crosstalk between fetuin-A, RSF and kidney, human renal sinus fat cells (RSFC) were isolated and cocultured with human endothelial cells (EC) or podocytes (PO). RSFC caused downregulation of proinflammatory and upregulation of regenerative factors in cocultured EC and PO, indicating a protective influence of RFSC. However, fetuin-A inverted these benign effects of RSFC from an anti- to a proinflammatory status. RSF was quantified by magnetic resonance imaging and liver fat content by ¹H-MR spectroscopy in 449 individuals at risk for type 2 diabetes. Impaired renal function was determined via urinary albumin/creatinine-ratio (uACR). RSF did not correlate with uACR in subjects without NAFLD (n = 212, p = 0.94), but correlated positively in subjects with NAFLD (n = 105, p = 0.0005). Estimated glomerular filtration rate (eGRF) was inversely correlated with RSF, suggesting lower eGFR for subjects with higher RSF (r = 0.24, p < 0.0001). In conclusion, our data suggest that in the presence of NAFLD elevated fetuin-A levels may impair renal function by RSF-induced proinflammatory signalling in glomerular cells.

The Diet and Haemodialysis Dyad: Three Eras, Four Open Questions and Four Paradoxes. A Narrative Review, Towards a Personalized, Patient-Centered Approach

The history of dialysis and diet can be viewed as a series of battles waged against potential threats to patients' lives. In the early years of dialysis, potassium was identified as "the killer", and the lists patients were given of forbidden foods included most plant-derived nourishment. As soon as dialysis became more efficient and survival increased, hyperphosphatemia, was identified as the enemy, generating an even longer list of banned aliments. Conversely, the "third era" finds us combating protein-energy wasting. This review discusses four questions and four paradoxes, regarding the diet-dialysis dyad: are the "magic numbers" of nutritional requirements (calories: 30-35 kcal/kg; proteins > 1.2 g/kg) still valid? Are the guidelines based on the metabolic needs of patients on "conventional" thrice-weekly bicarbonate dialysis applicable to different dialysis schedules, including daily dialysis or haemodiafiltration? The quantity of phosphate and potassium contained in processed and preserved foods may be significantly different from those in untreated foods: what are we eating? Is malnutrition one condition or a combination of conditions? The paradoxes: obesity is associated with higher survival in dialysis, losing weight is associated with mortality, but high BMI is a contraindication for kidney transplantation; it is difficult to limit phosphate intake when a patient is on a high-protein diet, such as the ones usually prescribed on dialysis; low serum albumin is associated with low dialysis efficiency and reduced survival, but on haemodiafiltration, high efficiency is coupled with albumin losses; banning plant derived food may limit consumption of "vascular healthy" food in a vulnerable population. Tailored approaches and agreed practices are needed so that we can identify attainable goals and pursue them in our fragile haemodialysis populations.

Metabolically healthy obesity and incident chronic kidney disease: The role of systemic inflammation in a prospective study

OBJECTIVE

To investigate the association between the metabolically healthy obesity (MHO) phenotype and incident chronic kidney disease (CKD) in a Chinese population and whether systemic inflammation affects this association.

METHODS

A cohort study was performed with 2,491 Chinese adults. Body mass index ≥ 25.0 kg/m² was defined as obesity. CKD was defined as estimated glomerular filtration rate < 60 mL/min per 1.73 m² or urinary albumin-to-creatinine ratio ≥ 30 mg/g. High-sensitivity C-reactive protein (hsCRP) was used as a surrogate marker of systemic inflammation.

RESULTS

Over a median follow-up period of 3.9 years, 243 of 2,491 participants developed incident CKD (9.8%). Compared with metabolically healthy nonobesity (MHNO), MHO was associated with incident CKD (odds ratio [OR] = 1.65, 95% confidence interval [CI] 1.01-2.69), but not after adjustment for hsCRP. The MHO/hsCRP ≥ 0.20 mg/L group, but not the MHO/hsCRP < 0.20 mg/L group, had an increased OR for incident CKD (OR = 2.66, 95% CI 1.37-5.14), with the MHNO/hsCRP < 0.20 mg/L group as the reference.

CONCLUSIONS

MHO was significantly associated with incident CKD, and the level of systemic inflammation partially explained this association.

Clinical Aspects of Glucose Metabolism and Chronic Disease

The burden of chronic disease is an emerging world health problem. Advances made in the treatment of individual disease states often fail to consider multimorbidity patterns in clinical research models. Adjusting for age as a confounder ignores its contribution as a powerful risk factor for most chronic diseases. Sarcopenia is an age-related loss of skeletal muscle mass, which is accelerated by chronic inflammation and its resulting cascade of cytokines. Skeletal muscle loss results in insulin resistance, hyperglycemia, and altered mitochondrial glucose signaling pathways. Vascular disease in the brain may alter blood-brain barrier function, allowing transport of substances into the brain which adversely affect the "astrocyte-centric" subunit. Neurogenesis that provides neuronal plasticity is impaired in the diabetic brain, while insulin resistance markers such as insulin-like growth factor (IGF-1) and insulin receptor substrate (IRS-1) are associated with poor cognitive performance. Advanced glycation end products generated by chronic hyperglycemia are found in postmortem AD brain. Intranasal insulin administration, a preferential route for CNS delivery, improved cognitive function in healthy adults, without affecting circulating levels of insulin or glucose. Exercise has demonstrated a neuroprotective effect through induction of antioxidative enzymes, neurotrophic, and vascular endothelial growth factors. Sarcopenia appears to be a dynamic process and is potentially reversible with attention to nutrition and cardiovascular fitness. Early detection and intervention may slow the progression of multimortality disease states and should be a focus of worldwide health systems.

Visceral Adiposity Index and Lipid Accumulation Product Index: Two Alternate Body Indices to Identify Chronic Kidney Disease among the Rural Population in Northeast China

We aimed to compare the relative strength of the association between anthropometric obesity indices and chronic kidney disease (CKD). Another objective was to examine whether the visceral adiposity index (VAI) and lipid accumulation product index (LAPI) can identify CKD in the rural population of China. There were 5168 males and 6024 females involved in this cross-sectional study, and 237 participants (2.12%) suffered from CKD. Obesity indices included body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), VAI and LAPI. VAI and LAPI were calculated with triglyceride (TG), high-density lipoprotein (HDL), BMI and WC. VAI = [WC/39.68 + (1.88 × BMI)] × (TG /1.03) × (1.31/ HDL) for males; VAI = [WC/36.58 + (1.89 × BMI)] × (TG/0.81) × (1.52/HDL) for females. LAPI = (WC-65) × TG for males, LAPI = (WC-58) × TG for females. CKD was defined as an estimated glomerular filtration rate (eGFR) of less than 60 mL/min per 1.73 m². The prevalence of CKD increased across quartiles for WHtR, VAI and LAPI. A multivariate logistic regression analysis of the presence of CKD for the highest quartile vs. the lowest quartile of each anthropometric measure showed that the VAI was the best predictor of CKD in females (OR: 4.21, 95% CI: 2.09–8.47, p < 0.001). VAI showed the highest AUC for CKD (AUC: 0.68, 95% CI: 0.65–0.72) and LAPI came second (AUC: 0.66, 95% CI: 0.61–0.70) in females compared with BMI (both p-values < 0.001). However, compared with the traditional index of the BMI, the anthropometric measures VAI, LAPI, WC, and WHtR had no statistically significant capacity to predict CKD in males. Our results showed that both VAI and LAPI were significantly associated with CKD in the rural population of northeast China. Furthermore, VAI and LAPI were superior to BMI, WC and WHtR for predicting CKD only in females.

The impact of insulin resistance on the kidney and vasculature

Insulin resistance is a systemic disorder that affects many organs and insulin-regulated pathways. The disorder is characterized by a reduced action of insulin despite increased insulin concentrations (hyperinsulinaemia). The effects of insulin on the kidney and vasculature differ in part from the effects on classical insulin target organs. Insulin causes vasodilation by enhancing endothelial nitric oxide production through activation of the phosphatidylinositol 3-kinase pathway. In insulin-resistant states, this pathway is impaired and the mitogen-activated protein kinase pathway stimulates vasoconstriction. The action of insulin on perivascular fat tissue and the subsequent effects on the vascular wall are not fully understood, but the hepatokine fetuin-A, which is released by fatty liver, might promote the proinflammatory effects of perivascular fat. The strong association of salt-sensitive arterial hypertension with insulin resistance indicates an involvement of the kidney in the insulin resistance syndrome. The insulin receptor is expressed on renal tubular cells and podocytes and insulin signalling has important roles in podocyte viability and tubular function. Renal sodium transport is preserved in insulin resistance and contributes to the salt-sensitivity of blood pressure in hyperinsulinaemia. Therapeutically, renal and vascular insulin resistance can be improved by an integrated holistic approach aimed at restoring overall insulin sensitivity and improving insulin signalling.

Novel phenotypes of prediabetes?

This article describes phenotypes observed in a prediabetic population (i.e. a population with increased risk for type 2 diabetes) from data collected at the University hospital of Tübingen. We discuss the impact of genetic variation on insulin secretion, in particular the effect on compensatory hypersecretion, and the incretin-resistant phenotype of carriers of the gene variant TCF7L2 is described. Imaging studies used to characterise subphenotypes of fat distribution, metabolically healthy obesity and metabolically unhealthy obesity are described. Also discussed are ectopic fat stores in liver and pancreas that determine the phenotype of metabolically healthy and unhealthy fatty liver and the recently recognised phenotype of fatty pancreas. The metabolic impact of perivascular adipose tissue and pancreatic fat is discussed. The role of hepatokines, particularly that of fetuin-A, in the crosstalk between these organs is described. Finally, the role of brain insulin resistance in the development of the different prediabetes phenotypes is discussed.

Association between Obese Phenotype and Mildly Reduced eGFR among the General Population from Rural Northeast China

Obesity contributes to reduced kidney function; however, whether this is due to obesity itself or the metabolic abnormalities that accompany it is unclear. Besides, most previous studies enrolled participants with moderate or severe stage of chronic kidney disease. In the present study, we aim to investigate the possible relationship between obesity, metabolic abnormalities and mildly reduced estimated glomerular filtration rate (eGFR). A total of 11,127 Chinese participants (age ≥ 35 years) were enrolled in a survey conducted from January 2012 to August 2013. eGFR 60–90 mL/min/1.73 m² was defined as mildly reduced eGFR. Obese phenotype was divided into four types: metabolically healthy non-obese (MHNO), metabolically healthy obese (MHO), metabolically abnormal non-obese (MANO) and metabolically abnormal obese (MAO). Among all participants, 1941 (17.4%) of them had mildly reduced eGFR (16.7% for men and 18.1% for women, p = 0.025). The prevalence of obese phenotype was 22.5% for MHNO, 9.1% for MHO, 32.1% for MANO and 36.4% for MAO. The prevalence of mildly reduced eGFR was 9.0% among MHNO, 7.0% among MHO, 22.6% among MANO and 20.7% among MAO (p < 0.001). Multivariate logistic regression analysis revealed that obese phenotype did not statically contributed to mildly reduced eGFR (MHO: OR = 1.107, p = 0.662; MANO: OR = 0.800, p = 0.127; MAO: OR = 1.119, p = 0.525). However, gender (OR = 1.475, p < 0.001), aging (OR = 1.283, p < 0.001), dyslipidemia (OR = 1.544, 95%CI: 1.315, 1.814, p < 0.001) and hyperglycemia (OR = 1.247, 95%CI: 1.068, 1.455, p = 0.005) was associated with increased risk of mild reduced eGFR. Among the general population from rural Northeast China, mildly reduced eGFR was associated with metabolic disorders like dyslipidemia and hyperglycemia, but not obesity.

The kidney in obesity

Body mass index has been found to be the second most important contributor to relative risk for developing end state renal disease (ESRD), after proteinuria. The impact of obesity on the kidney includes a wide spectrum, from characteristic pathologic lesions to increment in urinary albumin excretion (UAE) and proteinuria/or decrease in glomerular filtration rate (GFR). The cause of renal disease associated to obesity is not well understood, but two relevant elements emerge. The first is the presence of obesity-related glomerulopathy, and the second is the fat deposit in the kidney with impact on renal haemodynamics and intrarenal regulation. The mechanisms linking obesity and renal damage are complex and include haemodynamic changes, inflammation, oxidative stress, apoptosis, and finally renal scarring. The protection of kidney damage needs to combine weight reduction with the proper control of the cardiometabolic risk factors associated, hypertension, metabolic syndrome, diabetes and dyslipidaemia. The search for specific treatments merits future research.

Molecular insights into the role of white adipose tissue in metabolically unhealthy normal weight and metabolically healthy obese individuals

Obesity is a risk factor for the development of type 2 diabetes and cardiovascular disease. However, it is now recognized that a subset of individuals have reduced cardiometabolic risk despite being obese. Paradoxically, a subset of lean individuals is reported to have high risk for cardiometabolic complications. These distinct subgroups of individuals are referred to as metabolically unhealthy normal weight (MUNW) and metabolically healthy obese (MHO). Although the clinical relevance of these subgroups remains debated, evidence shows a critical role for white adipose tissue (WAT) function in the development of these phenotypes. The goal of this review is to provide an overview of our current state of knowledge regarding the molecular and metabolic characteristics of WAT associated with MUNW and MHO. In particular, we discuss the link between different WAT depots, immune cell infiltration, and adipokine production with MUNW and MHO. Furthermore, we also highlight recent molecular insights made with genomic technologies showing that processes such as oxidative phosphorylation, branched-chain amino acid catabolism, and fatty acid β-oxidation differ between these phenotypes. This review provides evidence that WAT function is closely linked with cardiometabolic risk independent of obesity and thus contributes to the development of MUNW and MHO.