Obesity-related Kidney Disease Research Articles

Obesity, kidney and metabolic bariatric surgery: a surgeon’s narrative review

Excess body weight impacts kidney function in individuals with severe obesity, primarily through metabolic alterations in adipocytes, especially in visceral adipose tissue. The relationship between persistent sterile inflammation associated with obesity and the progression of obesity-related kidney disease to chronic kidney disease (CKD) is an area of growing interest. The beneficial effects of weight loss on the prevention of kidney disease and the improvement of kidney function in individuals with obesity have been well documented. Currently, the most effective weight loss strategy is metabolic bariatric surgery (MBS), which has been proven to not only prevent the progression of CKD but also reverse it. However, awareness and understanding of the impact of obesity on the kidney should also extend to the severely obese population with clinically normal renal function. The purpose of this review is to outline the current knowledge on the pathophysiology of obesity-induced kidney damage, the effects of MBS on renal function in severely obese individuals with or without CKD, and provide the current evidence on perioperative management strategies for CKD patients, including diet and nutrition.

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.

Organelle communication maintains mitochondrial and endosomal homeostasis during podocyte lipotoxicity.

Organelle stress exacerbates podocyte injury, contributing to perturbed lipid metabolism. Simultaneous organelle stresses can occur in the kidney in the diseased state; therefore, a thorough analysis of organelle communication is crucial for understanding the progression of kidney diseases. Although organelles closely interact with one another at membrane contact sites, limited studies have explored their involvement in kidney homeostasis. The endoplasmic reticulum (ER) protein, PDZ domain-containing 8 (PDZD8), is implicated in multiple-organelle-tethering processes and cellular lipid homeostasis. In this study, we aimed to elucidate the role of organelle communication in podocyte injury using podocyte-specific Pdzd8-knockout mice. Our findings demonstrated that Pdzd8 deletion exacerbated podocyte injury in an accelerated obesity-related kidney disease model. Proteomic analysis of isolated glomeruli revealed that Pdzd8 deletion exacerbated mitochondrial and endosomal dysfunction during podocyte lipotoxicity. Additionally, electron microscopy revealed the accumulation of abnormal, fatty endosomes in Pdzd8-deficient podocytes during obesity-related kidney diseases. Lipidomic analysis indicated that glucosylceramide accumulated in Pdzd8-deficient podocytes, owing to accelerated production and decelerated degradation. Thus, the organelle-tethering factor, PDZD8, plays a crucial role in maintaining mitochondrial and endosomal homeostasis during podocyte lipotoxicity. Collectively, our findings highlight the importance of organelle communication at the 3-way junction among the ER, mitochondria, and endosomes in preserving podocyte homeostasis.

Liraglutide alleviates high-fat diet-induced kidney injury in mice by regulating the CaMKKβ/AMPK pathway

Objective Liraglutide, a glucagon-like peptide-1 receptor agonist, has been shown to regulate blood sugar and control body weight, but its ability to treat obesity-related nephropathy has been poorly studied. Therefore, this study was designed to observe the characteristics and potential mechanism of liraglutide against obesity-related kidney disease. Methods Thirty-six C57BL/6J male mice were randomly divided into six groups (n = 6 per group). Obesity-related nephropathy was induced in mice by continuous feeding of high-fat diet (HFD) for 12 weeks. After 12 weeks, liraglutide (0.6 mg/kg) and AMP-activated protein kinase (AMPK) agonists bortezomib (200 μg/kg) were injected for 12 weeks, respectively. Enzyme-linked immunosorbent assay was employed to detect the levels of total cholesterol, triglycerides, low-density lipoprotein cholesterol, blood urea nitrogen, creatinine in serum, as well as urinary protein in urine. Besides, hematoxylin–eosin staining and periodic acid-Schiff staining were used to observe the pathological changes of kidney tissue; immunohistochemistry, western blot, and real-time quantitative PCR to assess the calmodulin-dependent protein kinase kinase beta (CaMKKβ)/AMPK signaling pathway activation. Results Liraglutide significantly reduced serum lipid loading, improved kidney function, and relieved kidney histopathological damage and glycogen deposition in the mouse model of obesity-related kidney disease induced by HFD. In addition, liraglutide also significantly inhibited the CaMKKβ/AMPK signaling pathway in kidney tissue of HFD-induced mice. However, bortezomib partially reversed the therapeutic effect of liraglutide on HDF-induced nephropathy in mice. Conclusions Liraglutide has a therapeutic effect on obesity-related kidney disease, and such an effect may be achieved by inhibiting the CaMKKβ/AMPK signaling pathway in kidney tissue.

Clinical characteristics and treatment compounds of obesity-related kidney injury

Disorders in energy homeostasis can lead to various metabolic diseases, particularly obesity. The obesity epidemic has led to an increased incidence of obesity-related nephropathy (ORN), a distinct entity characterized by proteinuria, glomerulomegaly, progressive glomerulosclerosis, and renal function decline. Obesity and its associated renal damage are common in clinical practice, and their incidence is increasing and attracting great attention. There is a great need to identify safe and effective therapeutic modalities, and therapeutics using chemical compounds and natural products are receiving increasing attention. However, the summary is lacking about the specific effects and mechanisms of action of compounds in the treatment of ORN. In this review, we summarize the important clinical features and compound treatment strategies for obesity and obesity-induced kidney injury. We also summarize the pathologic and clinical features of ORN as well as its pathogenesis and potential therapeutics targeting renal inflammation, oxidative stress, insulin resistance, fibrosis, kidney lipid accumulation, and dysregulated autophagy. In addition, detailed information on natural and synthetic compounds used for the treatment of obesity-related kidney disease is summarized. The synthesis of detailed information aims to contribute to a deeper understanding of the clinical treatment modalities for obesity-related kidney diseases, fostering the anticipation of novel insights in this domain.

#1382 Kidney outcomes after bariatric surgery: a population-based cohort study

Abstract Background and Aims Obesity is associated with nephrolithiasis, chronic kidney disease (CKD), and kidney failure. Bariatric surgeries, including Roux en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), are effective treatments of severe obesity and may mitigate obesity-related kidney diseases such as CKD and kidney failure, but could on the other hand induce hyperoxaluria and nephrolithiasis, posing a potential risk to the kidneys. We examined the risk of nephrolithiasis, acute kidney injury (AKI), CKD, and kidney failure after bariatric surgery. Method We included individuals undergoing bariatric surgery (RYGB or SG) in Denmark between 2006 and 2018 using population-based registries. These individuals were age- and sex-matched 1:5 to a background general population cohort and a cohort with hospital-diagnosed obesity. Nephrolithiasis was identified by diagnosis codes within the Danish National Patient Registry (DNPR). AKI was defined as an increase in serum creatinine (sCr) of ≥26.5 µmol/L within 48 hours or a relative increase of ≥1.5 times within seven days or from a median outpatient baseline value. CKD was defined as the presence of two outpatient eGFR samples below 60 ml/min/1.73 m2, with a minimum interval of three months between each measurement. Kidney failure was defined by recordings of kidney transplantation or chronic dialysis in DNPR. One- and ten-year cumulative incidences (risks) were computed for each cohort accounting for the competing risk of death. Rates of incident nephrolithiasis, AKI, incident CKD, and incident kidney failure in post-bariatric-surgery patients were compared with the background population cohort and obesity cohort using multivariable Cox regression adjusting for age, sex, and Charlson Comorbidity Index (CCI)-score. Results We included 18,827 individuals with bariatric surgery (17,200 with RYGB and 1,627 with SG). Median follow-up was 8.1 years (5.2-9.2), 8.0 years (4.6-9.1), and 7.9 years (4.2-9.1) for the overall bariatric cohort, the background population cohort, and the obesity cohort, respectively. Within the bariatric cohort, the ten-year risk of nephrolithiasis was 2.8%, the one-year risk of AKI was 2.7%, while the ten-year risks of CKD, and kidney failure were 0.2% and 0.1%, respectively. When comparing the post-bariatric-surgery cohort with the general population cohort, the adjusted hazard ratio (HR) was 2.92 (95% CI; 2.61, 3.27) for nephrolithiasis, 2.60 (95% CI; 2.06, 3.28) for AKI, 0.36 (95% CI; 0.18, 0.73) for CKD, and 0.81 (95% CI; 0.49, 1.32) for kidney failure. Compared with the obesity cohort, the adjusted HRs for adverse events were at 1.73 (95% CI: 1.56, 1.91) for nephrolithiasis, 1.63 (95% CI; 1.38, 1.92) for AKI, 0.41 (95% CI; 0.26, 0.66) for CKD, and 0.65 (95% CI; 0.42, 0.98) for kidney failure. Conclusion Individuals with bariatric surgery had a higher ten-year rate of nephrolithiasis and a higher one-year rate of AKI, but reduced rates of CKD and kidney failure within ten years after surgery compared with both the background cohort and the obesity cohort.

Transcriptome analysis provides insights into high fat diet-induced kidney injury and moderate intensity continuous training-mediated protective effects

Although physics exercise has been utilized to prevent and treat a variety of metabolic diseases, its role in obesity-related kidney diseases remains poorly understood. In this study, we assessed the protective potential of moderate intensity continuous training (MICT) against high fat diet (HFD)-induced kidney injury and found that MICT could significantly reduce obesity indexes (body weight, serum glucose, total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol) and kidney injury indexes (serum creatinine and the expression of Kim-1 mRNA) in HFD-fed mice. PAS staining and Masson staining displayed that MICT maintained the morphological structure of kidney subunits and reduced kidney fibrosis in HFD-fed mice. By kidney RNA-seq, we identified several genes and pathways (Cd9, Foxq1, Mier3, TGF-β signaling pathway etc.) that might underlie HFD-induced kidney injury and MICT-mediated protective effects. In conclusion, this study revealed the protective role of MICT in HFD-induced kidney injury and suggested potential targets for the prevention and treatment of obesity-related kidney diseases.

Relationship of Serum Kallistatin Level With Arterial Stiffness and Metabolic Parameters in Obesity-Related Chronic Kidney Disease.

We investigated the relationship between serum kallistatin and kidney disease and proteinuria in nondiabetic obesity-related chronic kidney disease and observed the effects on arterial stiffness. We included 40 patients with nondiabetic obesity-related chronic kidney disease followed in our nephrology clinic and a control group of 40 participants without chronic kidney disease matched by age, sex, and mean body mass index (measured as weight in kilograms divided by height in meters squared). Pulse-wave velocity and augmentation index were measured oscillometrically by pulse-wave analysis (Mobil-O-Graph) by the same operator. Serum kallistatin levels were measured by sandwich enzyme-linked immunosorbent assay. Mean age of patients was 51 ± 7.5 years (range, 29-62 years), and 40% were female. Mean body mass index was 35 ± 3.1. Four patients (10%) had morbid obesity; 21 (52.5%) had hypertension. Glomerular filtration rate (42 ± 18 vs 83 ± 15 mL/min/1.73 m², respectively; P < .001) were significantly lower. However proteinuria (671 ± 1031 vs 80 ± 30 mg/d, respectively; P < .001) were significantly higher in patients than in controls. Also, serum kallistatin and arterial stiffness were significantly higher in patients (P < .05).''The Pulse Wave Velocity was higher in patients with hypertension (P = .01); GFR was lower (P < .01); serum uric acid level was higher (P < .001); and neutrophil-to-lymphocyte ratio (P < .05), C-reactive protein level (P < .05), and serum kallistatin level were higher (P < .05). Serum kallistatin levels increase in patients with obesity-related kidney disease. Especially hypertension and hyperuricemia are associated with an increase in serum kallistatin.

The New Challenge of Obesity - Obesity-Associated Nephropathy.

In recent years, obesity has become one of the major diseases that affect human health and consume human health resources, especially when it causes comorbidities such as hypertension, diabetes, cardiovascular disease and kidney disease. Many studies have demonstrated that obesity is associated with the development of chronic kidney disease and can exacerbate the progression of end-stage renal disease. This review described the mechanisms associated with the development of obesity-associated nephropathy and the current relevant therapeutic modalities, with the aim of finding new therapeutic targets for obesity-associated nephropathy. The mechanisms of obesity-induced renal injury include, in addition to the traditional alterations in renal hemodynamics, the involvement of various mechanisms such as macrophage infiltration in adipose tissue, alterations in adipokines (leptin and adiponectin), and ectopic deposition of lipids. At present, there is no "point-to-point" treatment for obesity-induced kidney injury. The renin-angiotensin-aldosterone system (RAAS) inhibitors, sodium-dependent glucose transporter 2 (SGLT-2) inhibitors and bariatric surgery described in this review can reduce urinary protein to varying degrees and delay the progression of kidney disease. In addition, recent studies on the therapeutic effects of intestinal flora on obesity may reduce the incidence of obesity-related kidney disease from the perspective of primary prevention. Both of these interventions have their own advantages and disadvantages, so the continuous search for the mechanism of obesity-induced related kidney disease will be extremely helpful for the future treatment of obesity-related kidney disease.

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.

ACT001 Alleviates chronic kidney injury induced by a high-fat diet in mice through the GPR43/AMPK pathway

BackgroundRoughly 10 -15% of global populace suffer from Chronic Kidney Disease(CKD). A major secondary disease that can progress to end-stage renal disease (ESRD) is obesity-associated kidney disease (ORG). Although clinical management strategies are currently available, morbidity and mortality rates are increasing. Thus, new solutions are needed. Intestinal permeability, systemic inflammation, and aberrant intestinal metabolites have all been linked to ORG.PurposeACT001 has anti-inflammatory, redox-regulatory and antitumour activities. The current study was designed to examine how ACT001 affects ORG and analyze the fundamental processes.MethodsA high-fat diet (HFD) was used to generate ORG in female C57BL/6 J mice.ORG mice were divided into three groups at random: HFD, HFD + ACT001, HFD + polyphosphocholine (PPC). To assess renal and colonic damage, periodic acid-Schiff (PAS) and hematoxylin–eosin (HE) staining were used. Following that, renal inflammation, oxidative stress, lipid deposition, colonic inflammation, and intestinal permeability were evaluated by protein blotting, polymerase chain reaction (PCR), immunohistochemistry, and immunofluorescence staining. Lastly, the SCFAs content was assessed by gas chromatographymass spectrometry.ResultsMice in the HFD group displayed more severe albuminuria, glomerular hypertrophy, renal oxidative damage, inflammation, and lipid accumulation than mice with the normal diet (ND) group, as well as lower levels of intestinal SCFA valproic acid, colonic inflammation, and tight junction protein downregulation. ACT001 treatment restores the content of valproic acid in intestinal SCFAs, promotes the binding of SCFAs to renal GPR43, activates the AMPK signalling pathway. Therefore, it promotes the Nrf2-Keap1 signalling pathway and inhibits the NF-κB signalling pathway. SCFAs, additionally, augment colonic GPR43 concentrations, diminishing NLRP3 inflammasome expression and restoring ZO-1 and occludin protein levels.ConclusionThis study is the first to look at ACT001's potential as a treatment for obesity-related kidney disease. Regulating GPR43 and AMPK signalling pathways, By controlling the GPR43 and AMPK signalling pathways, ACT001 improves colitis and the intestinal mucosal barrier, decreases renal lipid deposition, and suppresses inflammation and oxidative stress in the kidneys. According to this study, ACT001 could be a viable ORG therapy option.

Obesity-Related Kidney Disease: Current Understanding and Future Perspectives.

Obesity is a serious chronic disease and an independent risk factor for the new onset and progression of chronic kidney disease (CKD). CKD prevalence is expected to increase, at least partly due to the continuous rise in the prevalence of obesity. The concept of obesity-related kidney disease (OKD) has been introduced to describe the still incompletely understood interplay between obesity, CKD, and other cardiometabolic conditions, including risk factors for OKD and cardiovascular disease, such as diabetes and hypertension. Current therapeutics target obesity and CKD individually. Non-pharmacological interventions play a major part, but the efficacy and clinical applicability of lifestyle changes and metabolic surgery remain debatable, because the strategies do not benefit everyone, and it remains questionable whether lifestyle changes can be sustained in the long term. Pharmacological interventions, such as sodium-glucose co-transporter 2 inhibitors and the non-steroidal mineralocorticoid receptor antagonist finerenone, provide kidney protection but have limited or no impact on body weight. Medicines based on glucagon-like peptide-1 (GLP-1) induce clinically relevant weight loss and may also offer kidney benefits. An urgent medical need remains for investigations to better understand the intertwined pathophysiologies in OKD, paving the way for the best possible therapeutic strategies in this increasingly prevalent disease complex.

Kidney Considerations in Pediatric Obesity.

Chronic kidney disease (CKD) is a common condition and a major cause of morbidity and mortality in adults, but children and adolescents are also at risk for early kidney injury and development of CKD. Obesity contributes both directly and indirectly to the development of CKD. The purpose of this review is to describe obesity-related kidney disease (ORKD) and diabetic kidney disease (DKD) and their impact in the pediatric population. Although obesity-related CKD in childhood and adolescence is uncommon, nascent kidney damage may magnify the lifetime risk of CKD. Glomerular hyperfiltration is an early phenotype of both ORKD and DKD and typically manifests prior to albuminuria and progressive decline in GFR. Novel treatments for obesity and type 2 diabetes exerting protective effects on the kidneys are being investigated for use in the pediatric population. It is important to understand the impact of obesity on the kidneys more fully in the pediatric population to help detect injury earlier and intervene prior to the onset of irreversible progression of disease and to guide future research in this area.

Glomerular hyperfiltration and hypertrophy: an evaluation of maximum values in pathological indicators to discriminate "diseased" from "normal".

The success of sodium-glucose cotransporter 2 inhibitors and bariatric surgery in patients with chronic kidney disease has highlighted the importance of glomerular hyperfiltration and hypertrophy in the progression of kidney disease. Sustained glomerular hyperfiltration and hypertrophy can lead to glomerular injury and progressive kidney damage. This article explores the relationship between obesity and chronic kidney disease, focusing on the roles of glomerular hyperfiltration and hypertrophy as hallmarks of obesity-related kidney disease. The pathological mechanisms underlying this association include adipose tissue inflammation, dyslipidemia, insulin resistance, chronic systemic inflammation, oxidative stress, and overactivation of the sympathetic nervous system, as well as the renin-angiotensin aldosterone system. This article explains how glomerular hyperfiltration results from increased renal blood flow and intraglomerular hypertension, inducing mechanical stress on the filtration barrier and post-filtration structures. Injured glomeruli increase in size before sclerosing and collapsing. Therefore, using extreme values, such as the maximal glomerular diameter, could improve the understanding of the data distribution and allow for better kidney failure predictions. This review provides important insights into the mechanisms underlying glomerular hyperfiltration and hypertrophy and highlights the need for further research using glomerular size, including maximum glomerular profile, calculated using needle biopsy specimens.

The protective role of peroxisome proliferator-activated receptor gamma in lipotoxic podocytes

Podocytes are specialized epithelial cells that maintain the glomerular filtration barrier. These cells are susceptible to lipotoxicity in the obese state and irreversibly lost during kidney disease leading to proteinuria and renal injury. PPARγ is a nuclear receptor whose activation can be renoprotective. This study examined the role of PPARγ in the lipotoxic podocyte using a PPARγ knockout (PPARγKO) cell line and since the activation of PPARγ by Thiazolidinediones (TZD) is limited by their side effects, it explored other alternative therapies to prevent podocyte lipotoxic damage.Wild-type and PPARγKO podocytes were exposed to the fatty acid palmitic acid (PA) and treated with the TZD (Pioglitazone) and/or the Retinoid X receptor (RXR) agonist Bexarotene (BX).It revealed that podocyte PPARγ is essential for podocyte function. PPARγ deletion reduced key podocyte proteins including podocin and nephrin while increasing basal levels of oxidative and ER stress causing apoptosis and cell death. A combination therapy of low-dose TZD and BX activated both the PPARγ and RXR receptors reducing PA-induced podocyte damage. This study confirms the crucial role of PPARγ in podocyte biology and that their activation in combination therapy of TZD and BX may be beneficial in the treatment of obesity-related kidney disease.

Obesity-related proximal tubulopathy: an emerging threat to kidney health

Our previous studies have demonstrated that lipid overload leads to lysosomal dysfunction and autophagic stagnation in kidney proximal tubular epithelial cells (PTECs), which contributes to the renal lipotoxicity and eventually leading to the development of an obesity-related kidney disease. Here we identified that TFEB (transcription factor EB) is a modulator of PTECs lipotoxicity. Exposure to saturated fatty acid enhanced TFEB dephosphorylation and nuclear translocation in PTECs. In a mouse model fed with a high-fat diet (HFD), activated TFEB counteracted phospholipid accumulation in lysosomes by promoting lysosomal exocytosis in PTECs. Conversely, HFD-fed, PTECs-specific tfeb−/− deficient mice exhibited increased phospholipid accumulation and autophagic stagnation, which made kidney vulnerable to injury following ischemia-reperfusion. Moreover, a higher body mass index was correlated to reductions in TFEB nuclear translocation in PTECs of chronic kidney disease patients. These data suggest that PTECs are involved in the pathogenesis of obesity-related kidney disease, which is called obesity-related proximal tubulopathy.Abbreviations: EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; GAP: GTPase activating protein; HFD: high-fat diet; I/R: ischemia-reperfusion; LMP: lysosomal membrane permeabilization; LRP2: low density lipoprotein receptor-related protein 2; MLBs: multilamellar bodies; MTORC1: mechanistic target of rapamycin kinase complex 1; ORT: obesity-related proximal tubulopathy; PA: palmitic acid; PTEC: proximal tubular epithelial cell; RRAG: Ras related GTP binding; RPS6KB1, ribosomal protein S6 kinase B1; TFEB: transcription factor EB.

TFEB-mediated lysosomal exocytosis alleviates high-fat diet-induced lipotoxicity in the kidney.

Obesity is a major risk factor for end-stage kidney disease. We previously found that lysosomal dysfunction and impaired autophagic flux contribute to lipotoxicity in obesity-related kidney disease, in both humans and experimental animal models. However, the regulatory factors involved in countering renal lipotoxicity are largely unknown. Here, we found that palmitic acid strongly promoted dephosphorylation and nuclear translocation of transcription factor EB (TFEB) by inhibiting the mechanistic target of rapamycin kinase complex 1 pathway in a Rag GTPase-dependent manner, though these effects gradually diminished after extended treatment. We then investigated the role of TFEB in the pathogenesis of obesity-related kidney disease. Proximal tubular epithelial cell-specific (PTEC-specific) Tfeb-deficient mice fed a high-fat diet (HFD) exhibited greater phospholipid accumulation in enlarged lysosomes, which manifested as multilamellar bodies (MLBs). Activated TFEB mediated lysosomal exocytosis of phospholipids, which helped reduce MLB accumulation in PTECs. Furthermore, HFD-fed, PTEC-specific Tfeb-deficient mice showed autophagic stagnation and exacerbated injury upon renal ischemia/reperfusion. Finally, higher body mass index was associated with increased vacuolation and decreased nuclear TFEB in the proximal tubules of patients with chronic kidney disease. These results indicate a critical role of TFEB-mediated lysosomal exocytosis in counteracting renal lipotoxicity.

Obesity-related kidney disease: Beyond hypertension and insulin-resistance.

Chronic kidney disease (CKD) causes considerable morbidity, mortality, and health expenditures worldwide. Obesity is a significant risk factor for CKD development, partially explained by the high prevalence of diabetes mellitus and hypertension in obese patients. However, adipocytes also possess potent endocrine functions, secreting a myriad of cytokines and adipokines that contribute to insulin resistance and induce a chronic low-grade inflammatory state thereby damaging the kidney. CKD development itself is associated with various metabolic alterations that exacerbate adipose tissue dysfunction and insulin resistance. This adipose-renal axis is a major focus of current research, given the rising incidence of CKD and obesity. Cellular senescence is a biologic hallmark of aging, and age is another significant risk factor for obesity and CKD. An elevated senescent cell burden in adipose tissue predicts renal dysfunction in animal models, and senotherapies may alleviate these phenotypes. In this review, we discuss the direct mechanisms by which adipose tissue contributes to CKD development, emphasizing the potential clinical importance of such pathways in augmenting the care of CKD.

Nutrient-sensing mTORC1 and AMPK pathways in chronic kidney diseases.

Nutrients such as glucose, amino acids and lipids are fundamental sources for the maintenance of essential cellular processes and homeostasis in all organisms. The nutrient-sensing kinases mechanistic target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) are expressed in many cell types and have key roles in the control of cell growth, proliferation, differentiation, metabolism and survival, ultimately contributing to the physiological development and functions of various organs, including the kidney. Dysregulation of these kinases leads to many human health problems, including cancer, neurodegenerative diseases, metabolic disorders and kidney diseases. In the kidney, physiological levels of mTOR and AMPK activity are required to support kidney cell growth and differentiation and to maintain kidney cell integrity and normal nephron function, including transport of electrolytes, water and glucose. mTOR forms two functional multi-protein kinase complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Hyperactivation of mTORC1 leads to podocyte and tubular cell dysfunction and vulnerability to injury, thereby contributing to the development of chronic kidney diseases, including diabetic kidney disease, obesity-related kidney disease and polycystic kidney disease. Emerging evidence suggests that targeting mTOR and/or AMPK could be an effective therapeutic approach to controlling or preventing these diseases.

Obesity and chronic kidney disease.

The prevalence of obesity has increased dramatically during the past decades, which has been a major health problem. Since 1975, the number of people with obesity worldwide has nearly tripled. An increasing number of studies find obesity as a driver of chronic kidney disease (CKD) progression, and the mechanisms are complex and include hemodynamic changes, inflammation, oxidative stress, and activation of the renin-angiotensin-aldosterone system (RAAS). Obesity-related kidney disease is characterized by glomerulomegaly, which is often accompanied by localized and segmental glomerulosclerosis lesions. In these patients, the early symptoms are atypical, with microproteinuria being the main clinical manifestation and nephrotic syndrome being rare. Weight loss and RAAS blockers have a protective effect on obesity-related CKD, but even so, a significant proportion of patients eventually progress to end-stage renal disease despite treatment. Thus, it is critical to comprehend the mechanisms underlying obesity-related CKD to create new tactics for slowing or stopping disease progression. In this review, we summarize current knowledge on the mechanisms of obesity-related kidney disease, its pathological changes, and future perspectives on its treatment.