Metabolic Surgery to Treat Obesity in Diabetic Kidney Disease, Chronic Kidney Disease, and End-Stage Kidney Disease; What Are the Unanswered Questions?

Obesity and Metabolic Health in CKD

Obesity is a worldwide epidemic with a future projected growth of 40% over 10 years. Obesity increases the risk of diabetes, hypertension, and cardiovascular disease, and it also leads to higher risk of CKD, through both direct and indirect mechanisms. Although obesity is a feature of overnutrition and is associated with poor outcomes in the general population, obese individuals with CKD often display complex metabolic patterns such as sarcopenic obesity, and obesity can be associated with better survival in individuals with advanced CKD. Weight loss interventions are proven to improve glycemic control and cardiovascular risk factors, and successful weight loss is associated with improved albuminuria in patients with preexisting CKD. The long-term effects of weight loss interventions on kidney function and on survival in patients with CKD are less well studied, and hence, such interventions should be individualized.

Renal effects and safety of tirzepatide in subjects with and without diabetes: A systematic review and meta-analysis

BACKGROUND

Type 2 diabetes (T2D), as well as obesity, are risk factors for chronic kidney disease (CKD) and end-stage renal disease. The renal impacts of glucose-lowering and weight-lowering drugs and their potential benefits in preventing CKD often guide clinicians in choosing them appropriately. Only limited data based on randomized controlled trials (RCTs) is currently available on the renal effects and safety profile of tirzepatide.

AIM

To explore the renal benefits and safety of tirzepatide vs controls.

METHODS

RCTs involving patients receiving tirzepatide for any indication in the intervention arm and placebo or active comparator in the control arm were searched through multiple electronic databases. The co-primary outcomes were percent change from baseline (CFB) in urine albumin-to-creatinine ratio (UACR) and absolute CFB in estimated glomerular filtration rate (eGFR; in mL/min/1.73 m2); the secondary outcome was tirzepatide's renal safety profile. RevMan web was used to conduct meta-analysis using random-effects models. Outcomes were presented as mean differences (MD) or risk ratios with 95% confidence intervals.

RESULTS

Fifteen RCTs (n = 14471) with mostly low risk of bias (RoB) were included. Over 26-72 weeks, tirzepatide 10 mg [MD -26.95% (-40.13, -13.76), P < 0.0001] and 15 mg [MD -18.03% (-28.58, -7.47), P = 0.0008] were superior to placebo in percent reductions of UACR. Tirzepatide, at all doses, outperformed insulin in percent reductions of UACR. Compared to the placebo, the percent UACR reduction was greater in subjects with T2D than those with obesity but without T2D (MD -33.25% vs -7.93%; P = 0.001). The CFB in eGFR with all doses of tirzepatide was comparable [5 mg: MD 0.36 (-1.41, 2.14); 10 mg: MD 1.17 (-0.22, 2.56); 15 mg: MD 1.42 (-0.04, 2.88)]; P > 0.05 for all] vs insulin. Tirzepatide (pooled and separate doses) did not increase the risks of adverse renal events, urinary tract infection, nephrolithiasis, acute kidney injury, and renal cancer compared to the placebo, insulin, and glucagon-like peptide-1 receptor agonists.

CONCLUSION

Short-term data from RCTs with low RoB suggests that tirzepatide positively impacts UACR without detrimental effects on eGFR in subjects with T2D and obesity without T2D, with a reassuring renal safety profile. Larger RCTs are warranted to prove the longer-term renal benefits of tirzepatide, which might also prevent eGFR decline and worsening of CKD.

Relationship between BMI, indicators of lipid metabolism and diabetic neuropathy: a Mendelian randomization study

BACKGROUND

To identify the relationship between BMI or lipid metabolism and diabetic neuropathy using a Mendelian randomization (MR) study.

METHODS

Body constitution-related phenotypes, namely BMI (kg/m2), total cholesterol (TC), and triglyceride (TG), were investigated in this study. Despite the disparate origins of these data, all were accessible through the IEU OPEN GWAS database ( https://gwas.mrcieu.ac.uk/ ). Instrumental variables and F-statistics for each exposure-outcome pair were determined in weighted mode, weighted median, MR-Egger and Inverse-Variance Weighted (IVW) MR analyses. The p-value threshold was consistently set at 5.00E-08, following established methodology. The preliminary analysis utilized the IVW method to explore potential causal relationships between body constitution-related phenotypes and diabetic neuropathy. Inverse variance weighting, a technique amalgamating random variables, assigns weights inversely proportional to each variable's variance, commonly used for merging findings from independent studies. The weighted median method provides a causal estimate even when up to 50% of the instruments are invalid, enhancing robustness. The weighted mode method identifies the most common causal effect, reducing bias when some instruments exhibit horizontal pleiotropy. The Wald ratio method was utilized to calculate exposure-outcome effects, employing a range of methodologies to ensure result accuracy across different scenarios. This study addresses the critical gap in understanding the causal relationship between BMI, lipid metabolism, and diabetic neuropathy (DN). Employing a MR approach, it highlights BMI as a predictive factor for DN progression, providing insights into potential risk management strategies.

RESULTS

IVW analysis showed that BMI (P = 0.033, OR = 2.53, 95% CI 1.08-5.96) and triglycerides level (P = 0.593, OR = 1.11, 95% CI 0.77-1.60) were positively associated with the initiation of DN, indicating that the values of BMI and triglycerides are potentially the risk factors in DN development. Additionally, TC was negatively associated with the DN (P = 0.069, OR = 0.72, 95% CI = 0.50-1.03).The forest plot of advanced analysis between BMI and DN relationship indicated a positive correlation between increasing BMI and the risk of DN. In addition, it is evident that with the increase in BMI, the risk of diabetic polyneuropathy also rises. This research demonstrates a positive association between BMI and DN risk (P = 0.033, OR = 2.53, 95% CI = 1.08-5.96). However, no significant correlation was observed between triglycerides (P = 0.593) or total cholesterol (P = 0.069) and DN development, underscoring the complex interplay between lipid metabolism and DN.

CONCLUSION

This research demonstrates a positive association between the risk of DN and BMI, while no significant correlation exists between TG or TC and the development of DN. These results imply that BMI may serve as a predictive factor for the progression of DN.

Preoperative Laparoscopic Sleeve Gastrectomy Improves Weight Loss Potential in Morbidly Obese Voluntary Kidney Donors

BACKGROUND

This was a retrospective study aimed at evaluating the efficacy of laparoscopic sleeve gastrectomy (LSG) as a strategy for weight loss in obese prospective voluntary kidney donors who were unable to achieve weight reduction through lifestyle changes.

METHODS

This retrospective study included living kidney donors who underwent LSG as a strategy for weight loss in obese prospective voluntary kidney donors between 2012 and 2022. Prospective donors who were initially rejected due to obesity underwent LSG after pretransplantation evaluation. Changes in weight, body mass index (BMI), and laboratory parameters (hemogram, kidney function tests, liver function tests, fasting and postprandial glycemia, HbA1c, and lipid profile measurements) were recorded before bariatric surgery and before nephrectomy.

RESULTS

Of the 16 candidates who underwent LSG, one did not proceed with donor nephrectomy due to the intended recipient's death. Among the remaining 15 subjects, the average interval between bariatric surgery and donor nephrectomy was 165.95 ± 48.86 days. There was a significant decrease in BMI following bariatric surgery (P < .0001); the mean BMI before bariatric surgery was 40.94 ± 4.53 kg/m², and before nephrectomy, it was 30.91 ± 3.87 kg/m2. The mean weight loss was 22.64 ± 5.75 kg.

CONCLUSION

This study supports LSG as an effective approach for obese individuals who are potential kidney donors to achieve weight loss, mitigate obesity-associated risks, and become successful kidney donors.

Ten tips on how to manage obesity in the presence of CKD

Patients with chronic kidney disease are frequently facing the challenge of weight reduction. Finding a weight loss strategy is on the one hand essential to reduce the co-morbidity risks in CKD but remains complex due to the metabolic abnormalities with declining renal function. Here, we provide ten tips to support our CKD patients on their journey, focussing on dietary and behavioural habits and health professional supportive therapies.

Mid- and long-term renal outcomes after metabolic surgery in a multi-center, multi-ethnic Asian cohort with T2DM

Background

Metabolic surgery is recognized for its effectiveness in weight loss and improving outcomes for individuals with type 2 diabetes mellitus (T2DM). However, its impact on renal function, especially in multi-ethnic Asian populations, remains underexplored. This study investigates mid- and long-term renal outcomes following metabolic surgery in Asian patients with T2DM.

Methods

This retrospective cohort study utilized data from the Asian Diabetes Surgery Study (ADSS), involving T2DM patients aged 20-79 who underwent metabolic surgery from 2008 to 2015. The primary outcome was the change in estimated glomerular filtration rate (eGFR) at 1, 3, and 5 years post-surgery, with adjustments for confounders. Secondary outcomes included changes in chronic kidney disease (CKD) stages and the relationship between weight loss and eGFR changes. Data were analyzed using univariate and multivariable regression analyses, along with the McNemar test.

Results

The study included 1513 patients with a mean age of 42.7 years. The results revealed that a significant improvement in eGFR was observed at 1-year post-surgery (112.4 ± 32.0 ml/min/1.73 m², P < .001), with a shift toward less severe CKD stages. However, this improvement was not sustained at 3 and 5 years. No significant correlation was found between weight loss and eGFR changes at 1-year follow-up.

Conclusion

Metabolic surgery significantly improves renal function at 1 year postoperatively in Asian individuals with T2DM, highlighting its potential benefits beyond glycemic control and weight loss. The long-term effects on renal function require further investigation.

Association between clinical and laboratory factors and response to sodium-glucose cotransporter 2 inhibitors in patients with type 2 diabetes: a retrospective observational study

BACKGROUND

This study aimed to investigate the association between clinical and laboratory parameters and response to therapy with sodium-glucose cotransporter 2 inhibitors (SGLT2i) in patients with type 2 diabetes mellitus (T2D).

RESEARCH DESIGN AND METHODS

We retrospectively analyzed the medical records of people with T2D in whom SGLT2i was started. Clinical and laboratory parameters were recorded before, 3 and 6 months after starting treatment. Specific criteria were applied to classify participants into good and poor responders in terms of weight loss (primary outcome) and glycemic control (secondary outcome), separately.

RESULTS

Fifty individuals (64% men) with a mean age of 65.8 ± 8.5 years were included in the analysis. 86% and 64% of the participants were classified into good response categories for glycemic control and weight loss, respectively. Good responders in terms of glycemic control had lower high-density lipoprotein cholesterol levels at baseline compared to poor responders (43.3 vs 57.4 mg/dl, p = 0.044). In the logistic regression analysis, a higher baseline weight was associated with a better response to therapy in terms of weight loss (p = 0.04).

CONCLUSIONS

Our findings suggest that specific clinical and laboratory parameters are associated with response to SGLT2i treatment and can contribute to a more personalized approach to T2D care.

The impact of weight loss on renal function in individuals with obesity and type 2 diabetes: a comprehensive review

Obesity and Type 2 Diabetes (T2D) are two highly prevalent diseases that exhibit a complex interplay between them. Obesity serves as a primary risk factor for the development of T2D, and conversely, individuals with T2D often exhibit comorbid obesity. Renal dysfunction emerges as a critical consequence of the convergence of obesity and Type 2 Diabetes, contributing significantly to the overall burden of complications associated with these conditions. Recognizing the profound implications of renal dysfunction in individuals contending with both obesity and Type 2 Diabetes, interventions targeting weight loss have gained prominence as potential therapeutic avenues. Weight loss not only addresses the primary risk factor of obesity but also holds the promise of mitigating the progression of Type 2 Diabetes and its associated renal complications. This comprehensive review aims to explore the impact of weight loss on renal function in individuals contending with the convergence of obesity and T2D.

A Systems Nephrology Approach to Diabetic Kidney Disease Research and Practice

BACKGROUND

Diagnosis and staging of diabetic kidney disease (DKD) via the serial assessment of routine laboratory indices lacks the granularity required to resolve the heterogeneous disease mechanisms driving progression in the individual patient. A systems nephrology approach may help resolve mechanisms underlying this clinically apparent heterogeneity, paving a way for targeted treatment of DKD.

SUMMARY

Given the limited access to kidney tissue in routine clinical care of patients with DKD, data derived from renal tissue in preclinical model systems, including animal and in vitro models, can play a central role in the development of a targeted systems-based approach to DKD. Multi-centre prospective cohort studies, including the Kidney Precision Medicine Project (KPMP) and the European Nephrectomy Biobank (ENBiBA) project, will improve access to human diabetic kidney tissue for research purposes. Integration of diverse data domains from such initiatives including clinical phenotypic data, renal and retinal imaging biomarkers, histopathological and ultrastructural data, and an array of molecular omics (transcriptomics, proteomics, etc.) alongside multi-dimensional data from preclinical modelling offers exciting opportunities to unravel individual-level mechanisms underlying progressive DKD. The application of machine and deep learning approaches may particularly enhance insights derived from imaging and histopathological/ultrastructural data domains.

KEY MESSAGES

Integration of data from multiple model systems (in vitro, animal models, and patients) and from diverse domains (clinical phenotypic, imaging, histopathological/ultrastructural, and molecular omics) offers potential to create a precision medicine approach to DKD care wherein the right treatments are offered to the right patients at the right time.

Combination of Risks of BMI and Health-Related Lifestyles on Kidney Function in the Prediabetic Japanese Population: A Prospective Cohort Study

Diabetic overweight patients are more likely to show the progression of kidney damage than the general population. The majority of people in the early stages of kidney damage do not recognize the importance of risk modification, mainly due to the asymptomatic nature of the disease. This study aimed to examine specific risk combinations of lifestyle and BMI regarding the deterioration of kidney function and to explore whether there are gender-based differences among the prediabetic population. Prediabetic participants with normal kidney function were identified via annual health examination from April 2016 to March 2019. The information on health status and lifestyle was collected at enrollment. The study subjects were followed until March 2021 to observe the progression of kidney damage. There were 2241 participants enrolled in this study. Smoking (HR = 3.5, p < 0.001), eating snacks (HR = 3.2, p < 0.001), not engaging in regular exercise (HR = 2.9, p < 0.001), and not having adequate sleep (HR = 3.0, p < 0.001) showed accelerated risks for kidney damage progression among the prediabetic population in males. These lifestyle effects were not observed in females. In conclusion, risk-based modification of lifestyle behavior is important to prevent kidney function damage among the overweight prediabetic population in males.

Diet Management of Patients with Chronic Kidney Disease in Bariatric Surgery

Morbid obesity is considered a civilization disease of the 21st century. Not only does obesity increase mortality, but it is also the most important cause of the shortening life expectancy in the modern world. Obesity is associated with many metabolic abnormalities: dyslipidemia, hyperglycemia, cardiovascular diseases, and others. An increasing number of patients diagnosed with chronic kidney disease (CKD) are obese. Numerous additional disorders associated with impaired kidney function make it difficult to conduct slimming therapy and may also be associated with a greater number of complications than in people with normal kidney function. Currently available treatments for obesity include lifestyle modification, pharmacotherapy, and bariatric surgery (BS). There are no precise recommendations on how to reduce excess body weight in patients with CKD treated conservatively, undergoing chronic dialysis, or after kidney transplantation. The aim of this study was to analyze studies on the bariatric treatment of obesity in this group of people, as well as to compare the recommendations typical for bariatrics and CKD.

Dietary restriction and medical therapy drives PPARα-regulated improvements in early diabetic kidney disease in male rats

The attenuation of diabetic kidney disease (DKD) by metabolic surgery is enhanced by pharmacotherapy promoting renal fatty acid oxidation (FAO). Using the Zucker Diabetic Fatty and Zucker Diabetic Sprague Dawley rat models of DKD, we conducted studies to determine if these effects could be replicated with a non-invasive bariatric mimetic intervention. Metabolic control and renal injury were compared in rats undergoing a dietary restriction plus medical therapy protocol (DMT; fenofibrate, liraglutide, metformin, ramipril, and rosuvastatin) and ad libitum-fed controls. The global renal cortical transcriptome and urinary 1H-NMR metabolomic profiles were also compared. Kidney cell type-specific and medication-specific transcriptomic responses were explored through in silico deconvolution. Transcriptomic and metabolomic correlates of improvements in kidney structure were defined using a molecular morphometric approach. The DMT protocol led to ∼20% weight loss, normalized metabolic parameters and was associated with reductions in indices of glomerular and proximal tubular injury. The transcriptomic response to DMT was dominated by changes in fenofibrate- and peroxisome proliferator-activated receptor-α (PPARα)-governed peroxisomal and mitochondrial FAO transcripts localizing to the proximal tubule. DMT induced urinary excretion of PPARα-regulated metabolites involved in nicotinamide metabolism and reversed DKD-associated changes in the urinary excretion of tricarboxylic acid (TCA) cycle intermediates. FAO transcripts and urinary nicotinamide and TCA cycle metabolites were moderately to strongly correlated with improvements in glomerular and proximal tubular injury. Weight loss plus pharmacological PPARα agonism is a promising means of attenuating DKD.

Bariatric surgery for diabetic comorbidities: A focus on hepatic, cardiac and renal fibrosis

Continuously rising trends in diabetes render this disease spectrum an epidemic proportion worldwide. As the disease progresses, the pathological effects of diabetes may impair the normal function of several vital organs, eventually leading to increase the risk of other diabetic comorbidities with advanced fibrosis such as non-alcoholic fatty liver disease, diabetic cardiomyopathy, and diabetic kidney disease. Currently, lifestyle changes and drug therapies of hypoglycemic and lipid-lowering are effective in improving multi-organ function, but therapeutic efficacy is difficult to maintain due to poor compliance and drug reactions. Bariatric surgery, including sleeve gastrectomy and Roux-en-Y gastric bypass surgery, has shown better results in terms of prognosis for diabetes through long-term follow-up. Moreover, bariatric surgery has significant long-term benefits on the function of the heart, liver, kidneys, and other organs through mechanisms associated with reversal of tissue fibrosis. The aim of this review is to describe the impact of type 2 diabetes mellitus on hepatic, cardiac and renal fibrosis and to summarize the potential mechanisms by which bariatric surgery improves multiple organ function, particularly reversal of fibrosis.

Successful therapeutic strategy for a patient with obese end-stage kidney disease by simultaneous laparoscopic sleeve gastrectomy and implantation of a buried peritoneal dialysis catheter: A case report

For morbidly obese patients with end-stage kidney disease (ESKD), there are often difficulties in accessing, implementing, and maintaining kidney replacement therapy (KRT). Although recent weight-loss surgery has the potential to solve these problems, its therapeutic strategy and appropriate perioperative management for morbidly obese patients with ESKD have not been established. Here, we describe the case history of a 47-year-old man diagnosed with ESKD due to obesity-related glomerulopathy with an uncorrected estimated glomerular filtration rate (eGFR) of 16.1 ml/min. He hoped for kidney transplantation but was not eligible due to his high body mass index (BMI) (36.9 kg/m²). Therefore, a combination strategy for both attaining weight loss and preparing for KRT was needed. We performed modified laparoscopic sleeve gastrectomy (LSG) combined with a buried catheter for peritoneal dialysis (PD), which resulted in reduction of multiple surgical invasions while simultaneously preparing for PD. After these operations, his body mass dropped to below 30.0 kg/m², making him a candidate for kidney transplantation, while maintaining PD. Finally, he was able to have kidney transplantation with success. Collectively, in this case, our novel therapeutic approach was able to avoid multiple surgeries, to assist catheter insertion by laparoscopy, and to provide optimal KRT for an obese patient with ESKD. Simultaneous LSG and implantation of a buried PD catheter may be a promising strategy for morbidly obese patients with ESKD.

Pretransplant BMI Significantly Affects Perioperative Course and Graft Survival after Kidney Transplantation: A Retrospective Analysis

Background. The number of kidney transplant recipients (KTRs) with overweight and obesity is increasing. It was shown that obesity is related to inferior patient and graft survival. We aimed to analyze intraoperative parameters and postoperative short and long-term course of kidney transplantation (KT) in body mass index (BMI)-stratified cohorts of KTRs. Methods. A retrospective analysis of a prospectively built database of 433 KTRs from 2014 to 2017 from a single transplant center was performed. The objective of the study was to analyze the association between BMI at the time of transplantation with intraoperative parameters, adverse events in early postoperative course, and the overall mortality and graft loss in BMI-stratified cohorts: normal (18.5 and 24.9 kg/m2), overweight (25−29.9 kg/m2) and obese (≥30 kg/m2). Results. Obesity was related to longer total procedure time (p = 0.0025) and longer warm ischemia time (p = 0.0003). The postoperative course in obese patients was complicated by higher incidence of DGF (delayed graft function), early surgical complications (defined as surgical complications <30 days from KT), reoperation rate, vascular complications, incidence of lymphocele and wound dehiscence. There was no difference between the normal weight and overweight KTRs. The one-month kidney function (p = 0.0001) and allograft survival (p = 0.029) were significantly inferior in obese patients with no difference between normal weight and overweight patients. One-year death-censored graft survival was better in patients with BMI < 30 (88.6 vs. 94.8% p = 0.05). BMI was a significant predictor of graft loss in univariate (p = 0.04) but not in multivariate analysis (p = 0.09). Conclusion. Pretransplant obesity significantly affects the intraoperative and postoperative course of kidney transplantation and graft function and survival. The course of transplantation of overweight is comparable to normal BMI KTRs, and presumably pretransplant weight reduction to the BMI < 30 kg/m2 may improve the short-term postoperative course of transplantation as well as may improve graft survival. Thus, pretransplant weight reduction in obese KTRs may significantly improve the results of kidney transplantation. Metabolic surgery may play a role in improving results of KT.

Urinary Metabolomic Changes Accompanying Albuminuria Remission following Gastric Bypass Surgery for Type 2 Diabetic Kidney Disease

In the Microvascular Outcomes after Metabolic Surgery randomised clinical trial (MOMS RCT, NCT01821508), combined metabolic surgery (gastric bypass) plus medical therapy (CSM) was superior to medical therapy alone (MTA) as a means of achieving albuminuria remission at 2-year follow-up in patients with obesity and early diabetic kidney disease (DKD). In the present study, we assessed the urinary ¹H-NMR metabolome in a subgroup of patients from both arms of the MOMS RCT at baseline and 6-month follow-up. Whilst CSM and MTA both reduced the urinary excretion of sugars, CSM generated a distinctive urinary metabolomic profile characterised by increases in host–microbial co-metabolites (N-phenylacetylglycine, trimethylamine N-oxide, and 4-aminobutyrate (GABA)) and amino acids (arginine and glutamine). Furthermore, reductions in aromatic amino acids (phenylalanine and tyrosine), as well as branched-chain amino acids (BCAAs) and related catabolites (valine, leucine, 3-hydroxyisobutyrate, 3-hydroxyisovalerate, and 3-methyl-2-oxovalerate), were observed following CSM but not MTA. Improvements in BMI did not correlate with improvements in metabolic and renal indices following CSM. Conversely, urinary metabolites changed by CSM at 6 months were moderately to strongly correlated with improvements in blood pressure, glycaemia, triglycerides, and albuminuria up to 24 months following treatment initiation, highlighting the potential involvement of these shifts in the urinary metabolomic profile in the metabolic and renoprotective effects of CSM.

Medications Activating Tubular Fatty Acid Oxidation Enhance the Protective Effects of Roux-en-Y Gastric Bypass Surgery in a Rat Model of Early Diabetic Kidney Disease

Background

Roux-en-Y gastric bypass surgery (RYGB) improves biochemical and histological parameters of diabetic kidney disease (DKD). Targeted adjunct medical therapy may enhance renoprotection following RYGB.

Methods

The effects of RYGB and RYGB plus fenofibrate, metformin, ramipril, and rosuvastatin (RYGB-FMRR) on metabolic control and histological and ultrastructural indices of glomerular and proximal tubular injury were compared in the Zucker Diabetic Sprague Dawley (ZDSD) rat model of DKD. Renal cortical transcriptomic (RNA-sequencing) and urinary metabolomic (1H-NMR spectroscopy) responses were profiled and integrated. Transcripts were assigned to kidney cell types through in silico deconvolution in kidney single-nucleus RNA-sequencing and microdissected tubular epithelial cell proteomics datasets. Medication-specific transcriptomic responses following RYGB-FMRR were explored using a network pharmacology approach. Omic correlates of improvements in structural and ultrastructural indices of renal injury were defined using a molecular morphometric approach.

Results

RYGB-FMRR was superior to RYGB alone with respect to metabolic control, albuminuria, and histological and ultrastructural indices of glomerular injury. RYGB-FMRR reversed DKD-associated changes in mitochondrial morphology in the proximal tubule to a greater extent than RYGB. Attenuation of transcriptomic pathway level activation of pro-fibrotic responses was greater after RYGB-FMRR than RYGB. Fenofibrate was found to be the principal medication effector of gene expression changes following RYGB-FMRR, which led to the transcriptional induction of PPARα-regulated genes that are predominantly expressed in the proximal tubule and which regulate peroxisomal and mitochondrial fatty acid oxidation (FAO). After omics integration, expression of these FAO transcripts positively correlated with urinary levels of PPARα-regulated nicotinamide metabolites and negatively correlated with urinary tricarboxylic acid (TCA) cycle intermediates. Changes in FAO transcripts and nicotinamide and TCA cycle metabolites following RYGB-FMRR correlated strongly with improvements in glomerular and proximal tubular injury.

Conclusions

Integrative multi-omic analyses point to PPARα-stimulated FAO in the proximal tubule as a dominant effector of treatment response to combined surgical and medical therapy in experimental DKD. Synergism between RYGB and pharmacological stimulation of FAO represents a promising combinatorial approach to the treatment of DKD in the setting of obesity.

Diabetic kidney disease in children and adolescents: an update

Diabetic kidney disease (DKD), previously encountered predominantly in adult patients, is rapidly gaining center stage as a childhood morbidity and one that pediatric nephrologists are likely to encounter with increasing frequency. This is in large part due to the obesity epidemic and the consequent rise in type 2 diabetes in children and adolescents, as well as the more aggressive diabetes phenotype in today's youth with more rapid β-cell decline and faster development and progression of diabetes-related complications along with lower responsiveness to the treatments used in adults. DKD, an end-organ complication of diabetes, is at the very least a marker of, and more likely a predisposing factor for, the development of adverse cardiovascular outcomes and premature mortality in children with diabetes. On an optimistic note, several new therapeutic approaches are now available for the management of diabetes in adults, such as GLP1 receptor agonists, SGLT2 inhibitors, and DPP4 inhibitors, that have also been shown to have a favorable impact on cardiorenal outcomes. Also promising is the success of very low-energy diets in inducing remission of diabetes in adults. However, the addition of these pharmacological and dietary approaches to the management toolbox of diabetes and DKD in children and adolescents awaits thorough assessment of their safety and efficacy in this population. This review outlines the scope of diabetes and DKD, and new developments that may favorably impact the management of children and young adults with diabetes and DKD.

Pharmacotherapy to delay the progression of diabetic kidney disease in people with type 2 diabetes: past, present and future

Diabetic kidney disease (DKD) is a leading cause of morbidity and mortality among people living with diabetes, and is one of the most important causes of end stage renal disease worldwide. In order to reduce progression of DKD, important management goals include treatment of hypertension, glycaemia and control of cardiovascular risk factors such as lipids, diet, smoking and exercise. Use of angiotensin converting enzyme inhibitors or angiotensin receptor blockers has an established role in prevention of progression of DKD. A number of other agents such as endothelin-1 receptor antagonists and bardoxolone have had disappointing results. Recent studies have, however, suggested that newer antidiabetic agents such as sodium-glucose transporter-2 inhibitors (SGLT-2i) and glucagon-like peptide-1 analogues have specific beneficial effects in patients with DKD. Indeed most recent guidance suggest that SGLT-2i drugs should be used early in DKD, irrespective of glucose control. A number of pathways are hypothesised for the development and progression of DKD, and have opened up a number of newer potential therapeutic targets. This article aims to discuss management of DKD with respect to seminal trials from the past, more recent trials informing the present and potential new therapeutic options that may be available in the future.

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.

Effects of obesity and weight-loss surgery shift the microbiome and impact alloimmune responses

PURPOSE OF REVIEW

Obesity is a worldwide health problem with increasing rates in both children and adults. Bariatric surgery (BS) represents the only effective long-term treatment. Beneficial effects of BS may be mediated through shifts of the gut microbiome. Here, we introduce data linking the microbiome to alloimmune responses.

RECENT FINDINGS

The rapid development of microbiome sequencing technologies in addition to the availability of gnotobiotic facilities have enabled mechanistic investigations on modulations of alloimmune responses through microbiomes. BS has been shown to improve comorbidities and chronic inflammation caused by obesity. Changes in microbiota and microbiota-related metabolites may play a role. Patients either listed or having received a transplant have undergone weight loss surgery, thus allowing to dissect mechanisms of microbial shifts to alloimmunity.

SUMMARY

Weight loss and BS have the potential to improve transplant outcomes by ameliorating alloimmune responses. Those effects may be carried out through alterations of the gut microbiome.

Prevalence of chronic kidney disease and end-stage renal disease in a bariatric versus nonbariatric population: a retrospective analysis of the U.S. National Inpatient Sample database

BACKGROUND

In the past five 5 years our team has studied the effects of bariatric surgery on chronic kidney disease (CKD) at our institution.

OBJECTIVES

The objective of this study was to assess the impact of bariatric surgery (BaS) on the prevalence and likelihood of CKD and end-stage renal disease (ESRD) nationwide.

SETTING

Academic hospital, United States.

METHODS

We conducted a retrospective analysis of the U.S. National Inpatient Sample (NIS) database for the years 2010-2015 and compared. Univariate and multivariable analysis were performed to assess the impact of BaS on the point prevalence and the probability of CKD and ESRD. Similarly, a multivariable logistic regression was conducted to measure the impact of the most important risk factors for CKD exclusively in a severely obese population.

RESULTS

Data on 296,041 BaS cases and 2,004,804 severely obese controls was extracted from the NIS database and relative to controls, all baseline CKD risk factors were less common among bariatric surgery cases. Nonetheless, even after adjusting for all CKD risk factors, controls exhibited marked increases in the odds of CKD-stage III (odds ratio [OR] 3.10 [3.05-3.14], P < .0001) and modes increase for ESRD (OR 1.13 [1.09-1.18], P < .0001). Overall, even after adjusting for risk factors we observed that the rate of CKD is significantly higher in the control group, 12% when compared with 5.3% in the bariatric surgery group (P < .0001).

CONCLUSION

In this retrospective, case control study of a large, representative national sample of patients with severe obesity, BaS was found to be associated with significantly reduced point-prevalence and likelihood for CKD when adjusted for baseline CKD risk factors as compared with patients with obesity who did not undergo BaS. Overall, BaS resulted in a reduced rate and a moderate decrease in the likelihood of ESRD.

Downregulation of Salusin-β protects renal tubular epithelial cells against high glucose-induced inflammation, oxidative stress, apoptosis and lipid accumulation via suppressing miR-155-5p

Diabetic nephropathy (DN) is the main contributor to the excess mortality for patients suffering from diabetes. Here, C57BL/6 mice received 4 weeks of high-fat diet and intraperitoneal injection of STZ (100 mg/kg). Mice with random blood glucose level ≥16.7 mmol/L and positive urine protein were recognized as successful DN model. To construct an in vitro model, HK-2 cells were incubated with 30 mM glucose. RT-qPCR and western blot were employed to measure Salusin-β levels in kidney tissues of DN mice and HG-induced HK-2 cells. Meanwhile, RT-qPCR was performed to detect miR-155-5p level in kidney tissues of DN mice and HG-induced HK-2 cells. TNF-α, IL-6, IL-1β, ROS, SOD and CAT levels were assessed using commercial assay kits. Furthermore, apoptosis of HK-2 cells was assessed via flow cytometric analysis and TUNEL staining. In addition, intracellular lipid accumulation and total cholesterol levels were detected using Oil red O staining and TC ELISA kit. Herein, Salusin-β and miR-155-5p levels were distinctly upregulated in kidney tissues of DN mice and HG-induced HK-2 cells. Downregulation of Salusin-β reduced miR-155-5p expression. Salusin-β silencing dramatically relieved inflammatory and oxidative injury, suppressed apoptosis as well as lipid accumulation induced by HG in HK-2 cells. Besides, miR-155-5p elevation partially abrogated the alleviating effects Salusin-β silencing on HG-induced RTEC injury. In summary, downregulation of Salusin-β protected HK-2 cells against HG-induced inflammation, oxidative stress, apoptosis and ameliorated lipid accumulation through suppressing miR-155-5p, which indicated that Salusin-β could be a potential therapeutic drug for DN.

Obesity-related indices are associated with albuminuria and advanced kidney disease in type 2 diabetes mellitus

Obesity is an important risk factor for the development of diseases including diabetes, hypertension, and cardiovascular disease. However, few reports have investigated the relationships between these obesity-related indices and diabetic nephropathy. The aim of this study was to evaluate associations between obesity-related markers with albuminuria and advanced kidney disease in patients with type 2 diabetes mellitus (DM). Obesity-related indices including body mass index (BMI), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), body roundness index (BRI), conicity index (CI), lipid accumulation product (LAP), visceral adiposity index (VAI), body adiposity index (BAI), abdominal volume index (AVI), body shape index (BSI), and triglyceride glucose (TyG) index were measured. Albuminuria was defined as a urine albumin/creatinine ratio of ≥30 mg/g. Advanced kidney disease was defined as an estimated glomerular filtration rate (eGFR) <30 ml/min/1.73 m². A total of 1872 patients with type 2 DM (mean age 64.0 ± 11.3 years, 809 males and 1063 females) were enrolled. In multivariable analysis, 11 high obesity-related indices (BMI, WHR, WHtR, LAP, BRI, CI, VAI, BAI, AVI, ABSI, and TyG index) were significantly associated with albuminuria. In addition, high BMI, WHR, WHtR, LAP, BRI, CI, VAI, and AVI were significantly associated with eGFR <30 ml/min/1.73 m². The results of this study showed that various obesity-related indices were significantly associated with albuminuria and advanced kidney disease in patients with type 2 DM. Screening may be considered in public health programs to recognize and take appropriate steps to prevent subsequent complications.

Comparison of eGFR formulas in determining chronic kidney disease stage in bariatric patients and the impact on perioperative outcomes

BACKGROUND

Chronic kidney disease (CKD) independently increases the risk of 30-day adverse outcomes following metabolic and bariatric surgery (MBS). However, no studies have evaluated the stage of CKD at which increased perioperative risk is manifested. Here, we correlate 30-day major morbidities after MBS with extent of renal disease based on CKD Stage.

OBJECTIVES

To determine the impact of CKD stage on perioperative outcomes after bariatric surgery.

SETTING

Academic Hospital.

METHODS

From the 2017 Metabolic and Bariatric Surgery Quality Improvement Program (MBSAQIP) database, we identified patients with CKD who underwent sleeve gastrectomy or laparoscopic gastric bypass surgery. Glomerular filtration rates (GFRs) were calculated and cohorts were generated based on CKD Stage. Complication rates and rates of morbidity and mortality were compared between stages, and strengths of correlation were calculated.

RESULTS

GFR and CKD Stage were calculated for 150,283 patients. There was a significant increase in the risk of major morbidity at each progressive stage of CKD (P < .001 for all compared stages). There was a strong positive linear correlation between increasing CKD Stage and total morbidity (r² = .983), including reoperation ( r² = .784), readmission (r² = .936), unplanned ICU transfer (r² = .853), and aggregate complications such as pulmonary (r² = .900), bleeding (r² = .878), or progressive worsening of renal function (r² = .845). In logistic regression, for every 10-point decrease in GFR, odds of total morbidity increased by 6%.

CONCLUSION

An increased risk of perioperative complications may be seen in early stages of CKD, and risk is compounded in more advanced stages. Bariatric surgical candidates should be counseled on their increased risk of surgical complications even with mild CKD, and the benefits of bariatric surgery should be carefully weighed against significantly increased risks of complications in severe CKD.

Association between Adiposity Indexes and Kidney Disease: Findings from the Longitudinal Study of Adult Health (Elsa-Brazil)

INTRODUCTION

Chronic kidney disease (CKD) is a public health problem and it is associated with a high risk of mortality. Overweight and obesity are known as independent risk factors for CKD.

OBJECTIVE

To investigate the association between adiposity indexes and kidney disease.

METHODS

This study included 14,636 adults from ELSA-Brazil. Outcome variables: altered glomerular filtration rate (GFR), categorized as yes (GFR <60 mL/min/1.73 m²) and no (GFR ≥60 mL/min/1.73 m²), albuminuria, estimated by albumin-creatinine ratio and categorized as yes (≥30 mg/g) and no (<30 mg/g), and presence of chronic kidney disease (CKD) (altered GFR and/or albuminuria). Exposure variables: obesity and overweight (body mass index (BMI)≥30 and ≥25 kg/m², respectively), high waist circumference (WC) (≥102 cm in men and ≥88 cm in women), high waist-to-hip ratio (WHR) (≥0.90 in men and ≥0.85 in women), and high waist-to-height ratio (WHtR) (≥0.5). To estimate the association between main exposures and outcomes, logistic regression analyses were performed using models adjusted for sociodemographic variables (age, gender, race/skin color, education), behavioral (smoking, physical activity, alcohol consumption), components of the metabolic syndrome (HDL cholesterol, triglycerides, hypertension, diabetes mellitus) and history of cardiovascular disease (myocardial infarction, angina or heart failure).

RESULTS

Individuals with obesity, high WC, WHR and WHtR were more prone to albuminuria when compared to individuals with normal values for these measures. It was also observed that these altered measures were positively associated with the presence of CKD.

CONCLUSION

Adiposity indexes have a direct and significant association with albuminuria and CKD.

The Impact of CKD on Perioperative Risk and Mortality after Bariatric Surgery

Background

Twenty percent of patients with CKD in the United States have a body mass index (BMI) ≥35 kg/m². Bariatric surgery reduces progression of CKD to ESKD, but the risk of perioperative complications remains a concern.

Methods

The 24-month data spanning 2017-2018 were obtained from the Metabolic and Bariatric Surgery Quality Improvement Program (MBSAQIP) database and analyzed. Surgical complications were assessed on the basis of the length of hospital stay, mortality, reoperation, readmission, surgical site infection (SSI), and worsening of kidney function during the first 30 days after surgery.

Results

The 277,948 patients who had primary bariatric procedures were 44±11.9 (mean ± SD) years old, 79.6% were women, and 71.2% were White. Mean BMI was 45.7±7.6 kg/m². Compared with patients with an eGFR≥90 ml/min per BSA, those with stage 5 CKD/ESKD were 1.91 times more likely to be readmitted within 30 days of a bariatric procedure (95% CI, 1.37 to 2.67; P<0.001). Similarly, length of hospital stay beyond 2 days was 2.05-fold (95% CI, 1.64 to 2.56; P<0.001) higher and risk of deep incisional SSI was 6.92-fold (95% CI, 1.62 to 29.52; P=0.009) higher for those with stage 5 CKD/ESKD. Risk of early postoperative mortality increased with declining preoperative eGFR, such that patients with stage 3b CKD were 3.27 (95% CI, 1.82 to 5.89; P<0.001) times more likely to die compared with those with normal kidney function. However, absolute mortality rates remained relatively low at 0.53% in those with stage 3b CKD. Furthermore, absolute mortality rates were <0.5% in those with stages 4 and 5 CKD, and these advanced CKD stages were not independently associated with an increased risk of early postoperative mortality.

Conclusions

Increased severity of kidney disease was associated with increased complications after bariatric surgery. However, even for the population with advanced CKD, the absolute rates of postoperative complications were low. The mounting evidence for bariatric surgery as a renoprotective intervention in people with and without established kidney disease suggests that bariatric surgery should be considered a safe and effective option for patients with CKD.

Obesity is common in chronic kidney disease and associates with greater antihypertensive usage and proteinuria: evidence from a cross-sectional study in a tertiary nephrology centre

Obesity is a treatable risk factor for chronic kidney disease progression. We audited the reporting of body-mass index in nephrology outpatient clinics to establish the characteristics of individuals with obesity in nephrology practice. Body-mass index, clinical information and biochemical measures were recorded for patients attending clinics between 3^rd August, 2018 and 18^th January, 2019. Inferential statistics and Pearson correlations were used to investigate relationships between body-mass index, type 2 diabetes, hypertension and proteinuria. Mean ± SD BMI was 28.6 ± 5.8 kg/m² (n = 374). Overweight and obesity class 1 were more common in males (P = .02). Amongst n = 123 individuals with obesity and chronic kidney disease, mean ± SD age, n (%) female and median[IQR] eGFR were 64.1 ± 14.2 years, 52 (42.3%) and 29.0[20.5] mL/min/BSA, respectively. A positive correlation between increasing body-mass index and proteinuria was observed in such patients (r = 0.21, P = .03), which was stronger in males and those with CKD stages 4 and 5. Mean body-mass index was 2.3 kg/m² higher in those treated with 4-5 versus 0-1 antihypertensives (P = .03). Amongst n = 59 patients with obesity, chronic kidney disease and type 2 diabetes, 2 (3.5%) and 0 (0%) were prescribed a GLP-1 receptor analogue and SGLT2-inhibitor, respectively. Our data provides a strong rationale not only for measuring body-mass index but also for acting on the information in nephrology practice, although prospective studies are required to guide treatment decisions in people with obesity and chronic kidney disease.

Parallel assessment of albuminuria and plasma sTNFR1 in people with type 2 diabetes and advanced chronic kidney disease provides accurate prognostication of the risks of renal decline and death

Identification of people with diabetes and chronic kidney disease at high-risk of early mortality is a priority to guide intensification of therapy. We aimed to investigate the complementary prognostic value of baseline urine albumin-to-creatinine ratio (uACR) and plasma soluble tumour necrosis factor receptor-1 (sTNFR1) with respect to early mortality and renal functional decline in a population with type 2 diabetes and advanced chronic kidney disease. We measured plasma sTNFR1 in people with type 2 diabetes (HbA1c ≥ 48 mmol/mol) at 2 hospital sites in Dublin between October 15th, 2014 and July 17th, 2015. In a subgroup of patients with advanced chronic kidney disease at baseline (estimated glomerular filtration rate (eGFR) ≤ 60 mL/min/BSA) (n = 118), we collected clinical and longitudinal laboratory data to investigate relationships between sTNFR1 and renal and mortality endpoints by multivariable linear mixed-effects models and Cox proportional hazards regression models. The cohort was 64% male and 97% Caucasian. Mean age was 74 years, with a median type 2 diabetes duration of 16 years. Mean CKD-EPI eGFR was 42 mL/min/BSA and median [IQR] uACR was 3 [11] mg/mmol. Twenty-three (39%) people in quartiles 3 and 4 for plasma sTNFR1 died over 4-year follow-up. After adjustment for clinical variables, annual CKD-EPI eGFR decreased by - 0.56 mL/min/BSA/year for each logarithm unit increase in baseline uACR, corresponding to an annual loss of renal function of 3% per year. Furthermore, elevated uACR, but not sTNFR1, increased the risk of ≥ 40% decline in CKD-EPI eGFR (HR 1.5, p = 0.001) and doubling of serum creatinine (HR 2.0, p < 0.001). Plasma sTNFR1 did not predict a more negative trajectory in eGFR slope. However, for those people in quartiles 3 and 4 for plasma sTNFR1, an increased risk of incident mortality was detected (HR 4.9, p = 0.02). No such association was detected for uACR. In this elderly cohort of patients with type 2 diabetes and chronic kidney disease, sTNFR1 predicted short-to-medium term mortality risk but not risk of progressive renal functional decline. In contrast, parallel assessment of uACR predicted renal functional decline but not mortality, highlighting the complementary prognostic information provided by both parameters.