Obesity-related Glomerulopathy Research Articles

Butyrate attenuates high-fat diet induced glomerulopathy through GPR43-Sirt3 pathway.

The incidence of obesity related glomerulopathy (ORG) is rising worldwide with very limited treatment methods. Paralleled with the gut-kidney axis theory, beneficial effects of butyrate, one of short-chain fatty acids produced by gut microbiota, on metabolism and certain kidney diseases have gained growing attention. However, the effects of butyrate on ORG and its underlying mechanism are largely unexplored. In this study, a mice model of ORG was established with high-fat diet (HFD) feeding for 16 weeks, and sodium butyrate treatment was initiated at the 8th week. Podocytes injury, oxidative stress, and mitochondria function were evaluated in mice kidney and validated in vitro in palmitic acid (PA) treated-MPC5 cells. Further, the molecular mechanisms of butyrate on podocytes were explored. Compared with controls, sodium butyrate treatment alleviated kidney injuries and renal oxidative stress in HFD-fed mice. In MPC5 cells, butyrate ameliorated PA-induced podocyte damage and helped maintain the structure and function of the mitochondria. Moreover, the effects of butyrate on podocytes were mediated via GPR43-Sirt3 signal pathway, as evidenced by the diminished effects of butyrate with the intervention of GPR43 or Sirt3 inhibitors. In summary, we conclude that butyrate has therapeutic potential for the treatment of ORG. It attenuates HFD-induced ORG and podocytes injuries through the activation of GPR43-Sirt3 signaling pathway.

Obesity Nephropathy: A Current Overview

The obesity pandemic is a public health problem that is evolving at high speed with both functional and vital outcomes. Recently, many studies have shown that obesity is a driver of chronic kidney disease onset and progression. The mechanisms underlying this fact are multiple including inflammation, oxidative stress, insuline resistance and hemodynamic change with inappropriate RAAS and SNS activation; occuring on a particularly genetic basis of individual predisposition. In this field, Obesity-related glomerulopathy is characterized by glomerulomegaly with localized and segmental glomerulosclerosis lesions. Main symptoms are non specific, dominated by microproteinuria, rarely nephrotic syndrome and a slowed decline in glomerular filtration rate. As for treatment, it starts essentially with lifestyle interventions targeting a meaningful and sustainable weight loss, accompanied by antiobesity medications (AOMS) including RAAS blockers, SGLT2inhibitors and since very recently, long-acting glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RA) which were shown to be effective in managing weight loss in non-chronic kidney disease (CKD) patients. Preliminary results of more definitive studies in CKD patients are currently being finalized. Bariatric surgery could reduce the risk of mortality in obese CKD patients; it is recommended for patients with severe morbid obesity, poor tolerance to AOMS, particularly GLP RA, or those whose long-term medication costs represent a barrier to sustainable results. In this review, we summarize epidemiological data on obesity nephropathy, its pathophysiological mechanisms, clinical features and perspectives on its treatment.

A Minimal Change: Obesity-Related Glomerulopathy (ORG) and Intermittent Nonsteroidal Anti-inflammatory Drug (NSAID) Use as a Precursor to Minimal Change Disease in an Adult Patient

A Minimal Change: Obesity-Related Glomerulopathy (ORG) and Intermittent Nonsteroidal Anti-inflammatory Drug (NSAID) Use as a Precursor to Minimal Change Disease in an Adult Patient

Obesity-Related Glomerulopathy: Epidemiology, Pathogenesis, and Current Treatments

Obesity-related glomerulopathy (ORG) is a kidney disease characterized by glomerulomegaly with or without focal segmental glomerulosclerosis. With the increase in worldwide obesity rates, the number of ORG patients has also risen rapidly. Approximately 10% of ORG patients have been found to progress to the end stage of renal disease 6.2 years after diagnosis. The pathogenesis of ORG is complex, involving altered renal hemodynamics, activation of the renin–angiotensin–aldosterone system, insulin resistance, and abnormal lipid metabolism and adipokines. Despite the numerous strategies to lose weight as treatment for ORG, ranging from lifestyle and diet changes to bariatric surgery and medications, approved and marketed weight-loss drugs often have potential side effects and perform below expectations. Recently, new glucose-lowering drugs that also reduce body weight and improve kidney function have garnered attention. In particular, several large clinical trials have confirmed the efficacy and safety of sodium–glucose cotransporter 2 inhibitors and glucagon-like peptide-1 receptor agonists in reducing weight and preserving kidney function. This article provides a brief review of the epidemiology, pathogenesis, and treatment strategies of ORG.

Renoprotective effects of empagliflozin in high-fat diet-induced obesity-related glomerulopathy by regulation of gut-kidney axis.

The increasing prevalence of obesity-related glomerulopathy (ORG) poses a significant threat to public health. Sodium-glucose cotransporter-2 (SGLT2) inhibitors effectively reduce body weight and total fat mass in individuals with obesity and halt the progression of ORG. However, the underlying mechanisms of their reno-protective effects in ORG remain unclear. We established a high-fat diet-induced ORG model using C57BL/6J mice, which were divided into three groups: normal chow diet (NCD group), high-fat diet (HFD) mice treated with placebo (ORG group), and HFD mice treated with empagliflozin (EMPA group). We conducted 16S ribosomal RNA gene sequencing of feces and analyzed metabolites from kidney, feces, liver, and serum samples. ORG mice showed increased urinary albumin creatinine ratio, cholesterol, triglyceride levels, and glomerular diameter compared with NCD mice (all P < 0.05). EMPA treatment significantly alleviated these parameters (all P < 0.05). Multitissue metabolomics analysis revealed lipid metabolic reprogramming in ORG mice, which was significantly altered by EMPA treatment. MetOrigin analysis showed a close association between EMPA-related lipid metabolic pathways and gut microbiota alterations, characterized by reduced abundances of Firmicutes and Desulfovibrio and increased abundance of Akkermansia (all P < 0.05). The metabolic homeostasis of ORG mice, especially in lipid metabolism, was disrupted and closely associated with gut microbiota alterations, contributing to the progression of ORG. EMPA treatment improved kidney function and morphology by regulating lipid metabolism through the gut-kidney axis, highlighting a novel therapeutic approach for ORG. NEW & NOTEWORTHY Our study uncovered that empagliflozin (EMPA) potentially protects renal function and morphology in obesity-related glomerulopathy (ORG) mice by regulating the gut-kidney axis. EMPA's reno-protective effects in ORG mice are associated with the lipid metabolism, especially in glycerophospholipid metabolism and the pantothenate/CoA synthesis pathways. EMPA's modulation of gut microbiota appears to be pivotal in suppressing glycerol 3-phosphate and CoA synthesis. The insights into gut microbiota-host metabolic interactions offer a novel therapeutic approach for ORG.

The Kidney in Obesity: Current Evidence, Perspectives and Controversies.

As obesity and chronic kidney disease (CKD) remain a public health issue, we aim to elaborate on their complex relationship regarding pathogenetic mechanisms and therapeutic potential as well. The purpose of this review is to enhance our understanding of the interplay between obesity and CKD in order to timely diagnose and treat obesity-related CKD. Obesity and CKD pose significant intertwined challenges to global health, affecting a substantial portion of the population worldwide. Obesity is recognized as an independent risk factor, intricately contributing to CKD pathogenesis through mechanisms such as lipotoxicity, chronic inflammation, and insulin resistance. Recent evidence highlights additional factors including hemodynamic changes and intestinal dysbiosis that exacerbate kidney dysfunction in obese individuals, leading to histologic alterations known as obesity-related glomerulopathy (ORG). This narrative review synthesizes current knowledge on the prevalence, pathophysiology, clinical manifestations, and diagnostic strategies of obesity-related kidney disease. Furthermore, it explores mechanistic insights to delineate current therapeutic approaches, future directions for managing this condition and controversies. By elucidating the multifaceted interactions between obesity and kidney health, this review aims to inform clinical practice and stimulate further research to address this global health epidemic effectively.

Podocyte density as a predictor of long-term kidney outcome in obesity-related glomerulopathy

Glomerulomegaly and focal segmental glomerulosclerosis are histopathological hallmarks of obesity-related glomerulopathy (ORG). Podocyte injury and subsequent depletion are regarded as key processes in the development of these glomerular lesions in patients with ORG, but their impact on long-term kidney outcome is undetermined. Here, we correlated clinicopathological findings and podocyte depletion retrospectively in patients with ORG. Relative (podocyte density) and absolute (podocyte number per glomerulus) measures of podocyte depletion were estimated using model-based stereology in 46 patients with ORG. The combined endpoint of kidney outcomes was defined as a 30% decline in estimated glomerular filtration rate (eGFR) or kidney failure. Patients with lower podocyte density were predominantly male and had larger body surface area, greater proteinuria, fewer non-sclerotic glomeruli, larger glomeruli and higher single-nephron eGFR. During a median follow-up of 4.1 years, 18 (39%) patients reached endpoint. Kidney survival in patients with lower podocyte density was significantly worse than in patients with higher podocyte density. However, there was no difference in kidney survival between patient groups based on podocyte number per glomerulus. Cox hazard analysis showed that podocyte density, but not podocyte number per glomerulus, was associated with the kidney outcomes after adjustment for clinicopathological confounders. Thus, our study demonstrates that a relative depletion of podocytes better predicts long-term kidney outcomes than does absolute depletion of podocytes. Hence, the findings implicate mismatch between glomerular enlargement and podocyte number as a crucial determinant of disease progression in ORG.

Integrated miRNA-mRNA Analysis Reveals Critical miRNAs and Targets in Diet-Induced Obesity-Related Glomerulopathy.

This study aimed to investigate obesity-related glomerulopathy (ORG) at cellular, structural, and transcriptomic levels. Thirty Wistar rats were randomized into two groups: 15 rats were fed with a standard diet (SD-rats), and 15 rats were fed with a high-fat diet (HFD-rats). After 10 weeks, the weight, kidney function, histological features, and transcriptomic changes were assessed. HFD-rats gained significantly more weight (55.8% vs. 29.2%; p < 0.001) and albuminuria (10,384.04 ng/mL vs. 5845.45 ng/mL; p < 0.001) compared to SD-rats. HFD-rats exhibited early stages of ORG, with predominant mesangial matrix increase and podocyte hypertrophy (PH). These lesions correlated with differentially expressed (DE) genes and miRNAs. Functional analysis showed that miR-205, which was DE in both the kidneys and urine of HFD-rats, negatively regulated the PTEN gene, promoting lipid endocytosis in podocytes. The downregulation of PTEN was proved through a higher PTEN/nephrin ratio in the SD-rats and the presence of lipid vacuoles in HFD-podocytes. This study has found a specific targetome of miRNAs and gene expression in early stages of ORG. Also, it emphasizes the potential value of miR-205 as a urinary biomarker for detecting podocyte injury in ORG, offering a tool for early diagnosis, and opening new avenues for future therapeutic research of obesity-related glomerulopathy.

Obesity and kidney disease

The obesity epidemic has led to an increased prevalence of obesity-related glomerulopathy (ORG). This disease is characte-rized by proteinuria, glomerulomegaly, progressive glomerulosclerosis and a decline in renal function. Individuals with obesity frequently display arterial hypertension and diabetes mellitus, exacerbating renal damage. The pathogenesis involves overactivation of the RAAS (Renin-Angiotensin-Aldosterone System), glomerular hyperfiltration, an inflammatory state with oxidative stress, hyperinsulinemia-induced hemodynamic alterations and lipotoxicity. Additionally, obesity represents a significant risk factor for kidney stone formation, further contributing to renal damage. The management of obesity-induced nephropathy primarily involves weight reduction strategies and optimized control of blood pressure and metabolic factors. Early detection is crucial to counteract the progression of kidney disease. Noteworthy, obesity significantly complicates the implementation of renal replacement procedures, including kidney transplantation, and increases the rate of complications. In summary, there are many reasons why obesity should gain attention in the field of nephrology.

#1493 Upregulated miR-205 as a biomarker of diet-induced obesity-related glomerulopathy

Abstract Background and Aims Obesity is a modifiable risk factor for the development and progression of chronic kidney disease (CKD). Pathways through which obesity might cause renal disease are not completely understood, as not all obese subjects develop CKD. In terms of deepening the knowledge of the preliminary steps of obesity-related renal damage, our group has developed a diet-induced obese murine model with obesity related glomerulopathy (ORG). The objective of this study was to investigate ORG at a cellular, structural and transcriptomic level as a way to discover the triggering pathogenic phenomena of ORG and evaluate potential biomarkers. Method Thirty Wistar rats were randomized into two groups: control rats (n = 15), which were fed with standard diet (SD) and study rats (n = 15), which were fed with high-fat diet (HFD). After 10 weeks, weight, parameters of kidney function, renal histological features, transcriptomic changes, miRNA and mRNA isolation were compared. Results HFD gained significantly more weight (55.8%) than SD(29.2%), p = 0.001. Albuminuria was also significantly higher in HFD (10,384.04) compared with SD (5,845.45), p = 0.001. HFD rats showed typical lesions of early-stages of ORG, with a predominance of mesangial matrix increase (MMI) and podocyte hypertrophy (PH). All histologic lesions correlated with genes differentially expressed (DE) in kidneys of HFD group and, both MMI and PH, also correlated with specific miRNAs DE in the urine of HFD group. The functional analysis showed 4 miRNAs DE in the kidneys of HFD group that negatively regulates PTEN gene, which promotes podocyte endocytosis of lipids in ORG. The electronic microscope confirmed the spaces of lipid vacuoles in the podocytes of HFD rats. Between those 4 miRNAs DE, miR-205 was also found to be upregulated in the urine of HFD group. Conclusion Wistar rats fed with HFD for 10 weeks developed early-stages of ORG, with a specific targetome of miRNAs and gene expression. The upregulation of miR-205 in kidney and its isolation in urine is associated with lipid endocytosis of podocytes, which takes place in the early-stages of ORG and could become a plausible biomarker of early-stages of ORG and open new avenues for future therapeutics research.

EGR3 reduces podocyte inflammatory damage in obesity related glomerulopathy by inhibiting the PRMT1/p-STAT3 pathway.

Obesity related glomerulopathy (ORG) is induced by obesity, but the pathogenesis remains unclear. This study aims to investigate the expression of early growth response protein 3 (EGR3) in the renal cortex tissues of ORG patients and high-fat diet-induced obese mice, and to further explore the molecular mechanism of EGR3 in inhibiting palmitic acid (PA) induced human podocyte inflammatory damage. Renal cortex tissues were collected from ORG patients (n=6) who have been excluded from kidney damage caused by other diseases and confirmed by histopathology, and from obese mice induced by high-fat diet (n=10). Human and mouse podocytes were intervened with 150 μmol/L PA for 48 hours. EGR3 was overexpressed or silenced in human podocytes. Enzyme linked immunosorbent assay (ELISA) was used to detcet the levels of interleukin-6 (IL-6) and interleukin-1β (IL-1β). Real-time RT-PCR was used to detect the mRNA expressions of EGR3, podocytes molecular markers nephrosis 1 (NPHS1), nephrosis 2 (NPHS2), podocalyxin (PODXL), and podoplanin (PDPN). RNA-seq was performed to detect differentially expressed genes (DEGs) after human podocytes overexpressing EGR3 and treated with 150 μmol/L PA compared with the control group. Co-immunoprecipitation (Co-IP) combined with liquid chromatography tandem mass spectrometry (LC-MS) was used to detect potential interacting proteins of EGR3 and the intersected with the RNA-seq results. Co-IP confirmed the interaction between EGR3 and protein arginine methyltransferases 1 (PRMT1), after silencing EGR3 and PRMT1 inhibitor intervention, the secretion of IL-6 and IL-1β in PA-induced podocytes was detected. Western blotting was used to detect the expression of phosphorylated signal transducer and activator of transcription 3 (p-STAT3) after overexpression or silencing of EGR3. EGR3 was significantly upregulated in renal cortex tissues of ORG patients and high-fat diet-induced obese mice (both P<0.01). In addition, after treating with 150 μmol/L PA for 48 hours, the expression of EGR3 in human and mouse podocytes was significantly upregulated (both P<0.05). Overexpression or silencing of EGR3 in human podocytes inhibited or promoted the secretion of IL-6 and IL-1β in the cell culture supernatant after PA intervention, respectively, and upregulated or downregulated the expression of NPHS1, PODXL, NPHS2,and PDPN (all P<0.05). RNA-seq showed a total of 988 DEGs, and Co-IP+LC-MS identified a total of 238 proteins that may interact with EGR3. Co-IP confirmed that PRMT1 was an interacting protein with EGR3. Furthermore, PRMT1 inhibitors could partially reduce PA-induced IL-6 and IL-1β secretion after EGR3 silencing in human podocytes (both P<0.05). Overexpression or silencing of EGR3 negatively regulated the expression of PRMT1 and p-STAT3. EGR3 may reduce ORG podocyte inflammatory damage by inhibiting the PRMT1/p-STAT3 pathway.

Obesity-related glomerulopathy is associated with elevated WT1 expression in podocytes.

The prevalence of obesity is increasing worldwide at an alarming rate. In addition to the increased incidence of cardiovascular and metabolic diseases, obesity is the most potent risk factor for developing chronic kidney disease (CKD). Although systemic events such as hemodynamic factors, metabolic effects, and lipotoxicity were implicated in the pathophysiology of obesity-related glomerulopathy (ORG) and kidney dysfunction, the precise mechanisms underlying the association between obesity and CKD remain unexplored. In this study, we employed spontaneous WNIN/Ob rats to investigate the molecular events that promote ORG. Further, we fed a high-fat diet to mice and analyzed the incidence of ORG. Kidney functional parameters, micro-anatomical manifestations, and podocyte morphology were investigated in both experimental animal models. Gene expression analysis in the rodents was compared with human subjects by data mining using Nephroseq and Kidney Precision Medicine Project database. WNIN/Ob rats were presented with proteinuria and several glomerular deformities, such as adaptive glomerulosclerosis, decreased expression of podocyte-specific markers, and effacement of podocyte foot process. Similarly, high-fat-fed mice also showed glomerular injury and proteinuria. Both experimental animal models showed increased expression of podocyte-specific transcription factor WT1. The altered expression of putative targets of WT1 such as E-cadherin, podocin (reduced), and α-SMA (increased) suggests elevated expression of WT1 in podocytes elicits mesenchymal phenotype. Curated data from CKD patients revealed increased expression of WT1 in the podocytes and its precursors, parietal epithelial cells. WT1 is crucial during nephron development and has minimal expression in adult podocytes. Our study discovered elevated expression of WT1 in podocytes in obesity settings. Our analysis suggests a novel function for WT1 in the pathogenesis of ORG; however, the precise mechanism of WT1 induction and its involvement in podocyte pathobiology needs further investigation.

Obesity-related glomerulopathy: recent advances in inflammatory mechanisms and related treatments.

Obesity-related glomerulopathy, which is an obesity-triggered kidney damage, has become a significant threat to human health. Several studies have recently highlighted the critical role of inflammation in obesity-related glomerulopathy development. Additionally, excess adipose tissue and adipocytes in patients with obesity produce various inflammatory factors that cause systemic low-grade inflammation with consequent damage to vascular endothelial cells, exacerbating glomerular injury. Therefore, we conducted a comprehensive review of obesity-related glomerulopathy and addressed the critical role of obesity-induced chronic inflammation in obesity-related glomerulopathy pathogenesis and progression, which leads to tubular damage and proteinuria, ultimately impairing renal function. The relationship between obesity and obesity-related glomerulopathy is facilitated by a network of various inflammation-associated cells (including macrophages, lymphocytes, and mast cells) and a series of inflammatory mediators (such as tumor necrosis factor α, interleukin 6, leptin, adiponectin, resistin, chemokines, adhesion molecules, and plasminogen activator inhibitor 1) and their inflammatory pathways. Furthermore, we discuss a recently discovered relationship between micronutrients and obesity-related glomerulopathy inflammation and the important role of micronutrients in the body's anti-inflammatory response. Therefore, assessing these inflammatory molecules and pathways will provide a strong theoretical basis for developing therapeutic strategies based on anti-inflammatory effects to prevent or delay the onset of kidney injury.

Diagnostic value of renal biopsy in anti-phospholipase A2 receptor antibody-positive patients with proteinuria in China

Renal biopsy remains the gold standard for diagnosing membranous nephropathy (MN). Recent studies have suggested that renal biopsy can be replaced with the serum phospholipase A2 receptor (PLA2R) antibody test for MN diagnosis in patients with nephrotic syndrome. However, this test has not been validated in the Chinese population. In this study, we investigated whether renal biopsy provides additional diagnostic information on patients with proteinuria who are seropositive for PLA2R antibodies (SAb +). We retrospectively reviewed the clinicopathological characteristics of SAb + adult patients (aged ≥ 18 years) with proteinuria (≥ 0.5 g/24 h) assessed at the Department of Nephrology, the First Affiliated Hospital of Zhengzhou University, from June 2021 to March 2022. Among a total of 801 SAb + patients who received renal biopsy, those with incomplete pathological data, diabetes or any potential cause of secondary MN were excluded. Among the 491 remaining patients, 474 had primary MN (PMN), 16 had atypical MN (AMN, 9 patients with “full house” and 2 patients with HBsAg + /HBcAg + immunofluorescence results), and 1 had focal segmental glomerulosclerosis. In patients with an eGFR of ≥ 60 mL/min/1.73 m2 (n = 451), 436 had PMN, and 71 (16.3%) exhibited additional biopsy findings, with obesity-related glomerulopathy being the most common. In patients with an impaired eGFR (n = 40), 38 had PMN, and 31 (81.6%) showed additional findings, with acute tubular injury being the most common. In conclusion, anti-PLA2R antibody positivity is highly predictive of PMN in Chinese adults but often coexists with other pathological diagnoses. The advantages of renal biopsy for detecting other pathologies should be weighed against the potential risks of the biopsy procedure.

Insulin Resistance, Obesity, and Lipotoxicity.

Lipotoxicity, originally used to describe the destructive effects of excess fat accumulation on glucose metabolism, causes functional impairments in several metabolic pathways, both in adipose tissue and peripheral organs, like liver, heart, pancreas, and muscle. Ectopic lipid accumulation in the kidneys, liver, and heart has important clinical counterparts like diabetic nephropathy in type 2 diabetes mellitus, obesity-related glomerulopathy, nonalcoholic fatty liver disease, and cardiomyopathy. Insulin resistance due to lipotoxicity indirectly lead to reproductive system disorders, like polycystic ovary syndrome. Lipotoxicity has roles in insulin resistance and pancreatic beta-cell dysfunction. Increased circulating levels of lipids and the metabolic alterations in fatty acid utilization and intracellular signaling have been related to insulin resistance in muscle and liver. Different pathways, like novel protein kinase c pathways and the JNK-1 pathway, are involved as the mechanisms of how lipotoxicity leads to insulin resistance in nonadipose tissue organs, such as liver and muscle. Mitochondrial dysfunction plays a role in the pathogenesis of insulin resistance. Endoplasmic reticulum stress, through mainly increased oxidative stress, also plays an important role in the etiology of insulin resistance, especially seen in non-alcoholic fatty liver disease. Visceral adiposity and insulin resistance both increase the cardiometabolic risk, and lipotoxicity seems to play a crucial role in the pathophysiology of these associations.

Free fatty acids cause podocytes dysfunction and inflammation

The mechanisms underlying obesity-related kidney disease are not well understood. Growing evidence suggests that free fatty acids (FFAs), a cause of oxidative stress, play an important role in obesity and its related complications. So, we decided to investigate, in a human-conditioned immortalized podocyte cell line, the capacity of physiopathological concentrations of 27nM of nonconjugated palmitate to induce intracellular reactive oxygen species (ROS) production, podocytes endoplasmic reticulum (ER) stress, podocytes inflammation, and mitochondrial dysfunction. A conditionally immortalized human podocyte cell line was exposed to different percentages of palmitate conjugated to bovine serum albumin (BSA) for 24h. We observed that palmitate, at the same concentrations seen in obese patients, caused overproduction of ROS in human podocytes and this oxidative stress induces dysfunctions in podocytes like inflammation and changes in profibrotic and lipotoxic markers. High-mobility group box 1 (HMGB1) is likely known to be a major mediator of ROS damaging effects, as its pharmacological inhibition prevents all ROS effects on podocytes. Our study shows how, in podocytes, an unbounded fraction of 27nM of palmitate can induce dysfunctions similar to that observed in obesity-related glomerulopathy (ORG). These results could contribute to elucidating underlying mechanisms contributing to the ORG pathogenesis.

Podocyte Density, Rather than Podocyte Number per Glomerulus, Is Associated with Kidney Outcomes in Obesity-Related Glomerulopathy

Podocyte Density, Rather than Podocyte Number per Glomerulus, Is Associated with Kidney Outcomes in Obesity-Related Glomerulopathy

The Impact of Early-Stage Chronic Kidney Disease on Weight Loss Outcomes After Gastric Bypass

PurposeWeight loss achieved through bariatric metabolic surgery was demonstrated to be effective at reversing chronic kidney dysfunction associated with obesity-related glomerulopathy. However, robust data on how pre-operative kidney status impacts on bariatric metabolic surgery weight loss outcomes is still lacking. The aim of this study was to evaluate the impact of kidney dysfunction on weight loss outcomes after bariatric metabolic surgery.MethodsPatients with obesity to be submitted to gastric bypass surgery underwent a pre-operative evaluation of creatinine clearance, estimated glomerular filtration rate (eGFR), proteinuria, and albuminuria in 24-hour urine. Body mass index (BMI), % total weight loss (%TWL), and % excess BMI loss (%EBMIL) were assessed at 6 and 12 months after surgery.ResultsBefore surgery, patients (N=127) had a mean BMI of 39.6 ± 3.0 kg/m2, and 56.7% (n=72) had a creatinine clearance > 130 mL/min, 23.6% (n= 30) presented proteinuria > 150 mg/24h, and 15.0% (n= 19) presented albuminuria > 30 mg/24h. After surgery, the mean BMI was 27.7 kg/m2 and 25.0 kg/m2 at 6 and 12 months, respectively (p<0.0001). The %TWL was lower in patients with pre-operative eGFR < percentile 25 (34.4 ± 5.8% vs 39.4 ± 4.9%, p=0.0007, at 12 months). There were no significant correlations between weight loss metrics and pre-operative creatinine clearance rate, proteinuria, or albuminuria.ConclusionEarly-stage chronic kidney disease (G2) has a negative impact on short-term weight loss outcomes after bariatric metabolic surgery, albeit in a magnitude inferior to the clinically relevant threshold.Graphical abstract

Single-cell transcriptomic analysis reveals transcript enrichment in oxidative phosphorylation, fluid sheer stress, and inflammatory pathways in obesity-related glomerulopathy

Obesity-related glomerulopathy (ORG) is an independent risk factor for chronic kidney disease and even progression to end-stage renal disease. Efforts have been undertaken to elucidate the mechanisms underlying the development of ORG and substantial advances have been made in the treatment of ORG, but relatively little is known about cell-specific changes in gene expression. To define the transcriptomic landscape at single-cell resolution, we analyzed kidney samples from four patients with ORG and three obese control subjects without kidney disease using single-cell RNA sequencing. We report for the first time that immune cells, including T cells and B cells, are decreased in ORG patients. Further analysis indicated that SPP1 was significantly up-regulated in T cells and B cells. This gene is related to inflammation and cell proliferation. Analysis of differential gene expression in glomerular cells (endothelial cells, mesangial cells, and podocytes) showed that these cell types were mainly enriched in genes related to oxidative phosphorylation, cell adhesion, thermogenesis, and inflammatory pathways (PI3K-Akt signaling, MAPK signaling). Furthermore, we found that the podocytes of ORG patients were enriched in genes related to the fluid shear stress pathway. Moreover, an evaluation of cell-cell communications revealed that there were interactions between glomerular parietal epithelial cells and other cells in ORG patients, with major interactions between parietal epithelial cells and podocytes. Altogether, our identification of molecular events, cell types, and differentially expressed genes may facilitate the development of new preventive or therapeutic approaches for ORG.

Targeting Renal Proximal Tubule Cells in Obesity-Related Glomerulopathy.

As a metabolic disorder, obesity can cause secondary kidney damage, which is called obesity-related glomerulopathy (ORG). As the incidence of obesity increases worldwide, so does the incidence of end-stage renal disease (ESRD) caused by ORGs. However, there is still a lack of effective strategies to prevent and delay the occurrence and development of ORG. Therefore, a deeper understanding and elaboration of the pathogenesis of ORG is conducive to the development of therapeutic drugs for ORG. Here, we review the characteristics of pathological lesions of ORG and describe the roles of lipid metabolism disorders and mitochondrial oxidative stress in the development of ORG. Finally, we summarize the current available drugs or compounds for the treatment of ORG and suggested that ameliorating renal lipid metabolism and mitochondrial function may be potential therapeutic targets for ORG.