Obesity-related glomerulopathy: pathogenesis, pathologic, clinical characteristics and treatment

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.

Relationship of body mass index and kidney outcomes in patients with primary glomerulonephritis: A systematic review and meta-analysis

BACKGROUND

Primary glomerulonephritis, is a major contributor to the development of chronic kidney disease and end-stage renal disease. Previous studies on the relationship between overweight/obesity with primary glomerulonephritis in the chronic kidney disease was inconsistent. This study aimed to systematically review and meta-analyze the relationship between body mass index and adverse kidney outcomes in patients with primary glomerulonephritis.

METHODS

PubMed, Embase, the Cochrane Library, and the China National Knowledge Infrastructure were searched. Patients were divided into an overweight/obesity group (group O) and a non-overweight/obesity group (group N) according to their body mass index values.

RESULTS

Twenty-six studies with 11,038 patients were selected. Patients in group O had deteriorated baseline characteristics, including worse baseline estimated glomerular filtration rate (weighted mean differences [WMD] = -5.99), higher Scr (WMD = 7.34), uric acid (WMD = 47.53), 24-hour proteinuria (WMD = 0.40), and a higher prevalence rate of hypertension (odds ratio, OR = 2.70) and diabetes mellitus (OR = 2.644). On the histopathologic level, patients in group O had a significantly lower total glomerular number (WMD = -2.30); however, no difference was observed in mesangial cell proliferation, endocapillary hypercellularity, crescents, sclerosis, and tubular atrophy/interstitial fibrosis between the 2 groups. The incidence of adverse renal outcomes in the 2 groups was similar (OR = 0.96). The meta-analysis of hazard ratios from Cox regressions indicated a strong association between overweight/obesity and poor renal outcomes in glomerulonephritis (HR = 1.17).

CONCLUSION

Overweight/obesity glomerulonephritis patients had remarkably poor baseline clinicopathological characteristics. Being overweight or obesity would likely impact the progression of primary glomerulonephritis but not serious enough to contribute to significant poor renal outcomes, which could be prevented by aggressive therapy.

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.

Kidney and liver fat accumulation: from imaging to clinical consequences

BACKGROUND

Recent studies indicate that accumulation of adipose tissue in various organs such as liver and kidney may contribute to the pathophysiology of metabolic syndrome. We aim to investigate the association between kidney and liver adipose tissue accumulation, assessed by the magnetic resonance imaging (MRI) proton density fat fraction technique, along with its relation to clinical and biochemical parameters.

METHODS

We included 51 volunteers with phenotypical features of metabolic syndrome (mean age = 34 years, mean body-mass index = 26.4 kg/m2) in our study in which liver and kidney adipose tissue accumulation was assessed via MRI-proton density fat fraction along with multiple other clinical and biochemical parameters such as estimated glomerular filtration rate (eGFR), urine albumin-to-creatinine ratio, serum lipid profile, liver function tests and body-mass index (BMI).

RESULTS

Our results from the univariate linear regression analysis indicate that both the kidney and liver scores were positively correlated with markers such as BMI, urine albumin-to-creatinine ratio, triglycerides (p < 0.001) and negatively correlated with eGFR (p < 0.05). In multivariate analysis, urine albumin-to-creatinine ratio (p < 0.05), triglycerides (p < 0.01), eGFR (p < 0.05) and BMI (p < 0.001) were found to be independently associated with kidney and liver fat accumulation, respectively (R2 = 0.64; R2 = 0.89). There was also a positive correlation between kidney and liver fat accumulation.

CONCLUSION

We have found a significant association between adipose tissue accumulation in liver and kidney and the parameters of metabolic syndrome. Moreover, the presence of a strong association between kidney and liver fat accumulation and kidney function parameters such as urine albumin-to-creatinine ratio and eGFR may be an indicator of the clinical significance of parenchymal fat accumulation.

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.

Management of traditional risk factors for the development and progression of chronic kidney disease

Chronic kidney disease (CKD) and its downstream complications (i.e. cardiovascular) are a major source of morbidity worldwide. Additionally, deaths due to CKD or CKD-attributable cardiovascular disease account for a sizeable proportion of global mortality. However, the advent of new pharmacotherapies, diagnostic tools, and global initiatives are directing greater attention to kidney health in the public health agenda, including the implementation of effective strategies that (i) prevent kidney disease, (ii) provide early CKD detection, and (iii) ameliorate CKD progression and its related complications. In this Review, we discuss major risk factors for incident CKD and CKD progression categorized across cardiovascular (i.e. hypertension, dyslipidemia, cardiorenal syndrome), endocrine (i.e. diabetes mellitus, hypothyroidism, testosterone), lifestyle (i.e. obesity, dietary factors, smoking), and genetic/environmental (i.e. CKDu/Mesoamerican nephropathy, APOL1, herbal nephropathy) domains, as well as scope, mechanistic underpinnings, and management.

The Fatty Kidney and Beyond: A Silent Epidemic

As the prevalence of obesity rises in the United States, so does the incidence of obesity-related kidney disease. Obesity itself is an independent risk factor for chronic kidney disease where the pathophysiology is complex, involving altered hemodynamics, renin-angiotensin-aldosterone system overactivation, and adipokines leading to inflammation and fibrosis. Obesity-related kidney disease comprises both obesity-related glomerulopathy and fatty kidney disease. Obesity-related glomerulopathy is a consequence of glomerular hyperfiltration and often presents clinically with subnephrotic proteinuria and pathologically with glomerulomegaly with or without focal glomerulosclerosis. Fatty kidney disease is the effect of renal ectopic fat contributing to chronic kidney disease. Whether the renal ectopic fat is a distinct clinical entity or a pathologic mechanism contributing to obesity-related glomerulopathy, the treatment paradigm of weight and proteinuria reduction remains the same. We present the pathophysiology behind obesity-related kidney disease, clinical outcomes, and treatment strategies, which include lifestyle interventions, use of renin-angiotensin-aldosterone system inhibitors, glucagon-like peptide 1 receptor agonists, sodium-glucose co-transporter-2 inhibitors, and bariatric surgery. With old and novel therapeutics, we are attempting to stave off the silent epidemic that obesity-related kidney disease is becoming.

Correlation Between the Variability of Different Obesity Indices and Diabetic Kidney Disease: A Retrospective Cohort Study Based on Populations in Taiwan

Purpose

To investigate the association of five obesity indices and the variability of these indices with diabetic kidney disease (DKD) in patients with type 2 diabetes and compare the predictive validity of these markers for the risk of DKD in this large longitudinal cohort study.

Patients and Methods

A total of 2659 patients with type 2 diabetes who did not have DKD were enrolled between 2006 and 2019 at Lee's United Clinic in Taiwan. Data were collected for each subject, including demographic data, personal medical history, clinical parameters and calculated Body mass index (BMI), visceral adiposity index (VAI), lipid accumulation product (LAP), body roundness index (BRI) and variability of five obesity indices. Cox regression analysis was performed to determine the relationship between different obesity indicators and DKD risk. Cox's proportional hazards model was evaluated the predictive effect of obesity indices on DKD.

Results

The risk of developing DKD increased with an increase in the BRI, LAP, VAI, WC and BMI (all P trend<0.05), and the variability of VAI was significantly associated with DKD [HR=1.132, 95% CI (1.001, 1.281)] after adjusting for corresponding variables. BRI had the strongest predictive effect on DKD. BRI had the best predictive performance, with AUC of 0.807, 0.663 and 0.673 at 1, 3 and 5 years, respectively. Cox regression analysis of risk factors for DKD in patients stratified by BRI quartiles showed that patients in the Q4 group had the highest risk of developing DKD [HR=1.356, 95% CI (1.131, 1.626)].

Conclusion

BMI, WC, VAI, LAP, BRI and VAI variability were associated with a significant increase in the risk of DKD events, and BRI was superior and alternative obesity index for predicting DKD.

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.

Folate Deficiency Enhanced Inflammation and Exacerbated Renal Fibrosis in High-Fat High-Fructose Diet-Fed Mice

The prevalence of obesity and chronic kidney disease (CKD) is increasing simultaneously and rapidly worldwide. Our previous study showed that folate deficiency increased lipid accumulation and leptin production of adipocytes. Whether folate plays a role in CKD, particularly obesity-related nephropathy remains unclear. To investigate the effects of folate deficiency on CKD in diet-induced obese mice, four groups of male C57BL/6 mice were fed either a normal-fat diet (NF) with folate (NF+f); NF without folate (NF-f); high-fat high-fructose diet (HFF) with folate (HFF+f); or HFF without folate (HFF-f) for 12 months during the study. The results showed that HFF increased not only body weight, fasting blood glucose, total cholesterol (TC), low-density lipoprotein (LDL)-cholesterol, and blood pressure, but also cytokines levels, such as interleukin (IL)-2, interferon (IFN)-γ, IL-17A/F, IL-6, monocyte chemoattractant protein (MCP)-1, and transforming growth factor (TGF)-β1. The indicators of kidney failure including urinary protein, neutrophil gelatinase-associated lipocalin (NGAL), renal type I and IV collagen deposits and leptin content, and serum creatinine were also increased by HFF. Folate-deficient diets further elevated serum TC, LDL-cholesterol, IL-6, tumor necrosis factor (TNF)-α, MCP-1, TGF-β1, and leptin, but decreased IL-10 level, and thus exacerbated renal fibrosis. To investigate the possible mechanisms of folate deficiency on renal injury, phosphorylation of pro-fibrosis signaling molecules, including signal transducer and activator of transcription (STAT)3 and small mothers against decapentaplegic (Smad)2/3, were assayed. Both HFF and folate deficiency significantly increased the phosphorylation of STAT3 and Smad2/3, suggesting synergistic effects of HFF-f on chronic renal inflammation and fibrosis. In conclusion, the results demonstrated that folate deficiency might aggravate inflammatory status and enhance renal fibrosis.

Association between remnant cholesterol and chronic kidney disease in Chinese hypertensive patients

Background

Remnant cholesterol (RC) and chronic kidney disease (CKD) have not been definitively linked in individuals with different characteristics. This study aims to investigate the relationship between serum RC level and CKD and examine possible effect modifiers in Chinese patients with hypertension.

Methods

Our study is based on the Chinese H-type Hypertension Project, which is an observational registry study conducted in real-world settings. The outcome was CKD, defined as an estimated glomerular filtration rate of less than 60 ml/min·1.73 m2. Multivariate logistic regression and smooth curve fitting were used to analyze the association between RC and CKD. Subgroup analyses were subsequently conducted to examine the effects of other variables.

Results

The mean age of the 13,024 patients with hypertension at baseline was 63.8 ± 9.4 years, and 46.8% were male. A conspicuous linear positive association was observed between RC level and CKD (per SD increment; odds ratio [OR], 1.15; 95% confidence interval [CI], 1.08-1.23). Compared with the lowest quartile group of RC, the risk of CKD was 53% higher (OR, 1.53; 95% CI, 1.26-1.86) in the highest quartile group. Furthermore, a stronger positive association between RC level and CKD was found among participants with a higher body mass index (BMI <24 vs. ≥24 kg/m2; P-interaction = 0.034) or current non-smokers (smoker vs. non-smoker; P-interaction = 0.024).

Conclusions

Among Chinese adults with hypertension, RC level was positively associated with CKD, particularly in those with a BMI of ≥24 kg/m2 and current non-smokers. These findings may help improve lipid management regimens in patients with hypertension.

Anti-obesity effects of Camellia (Camellia oleifera Abel) oil treatment on high-fat diet-induced obesity in C57BL/6J mice

PURPOSE

In the current study, we investigated the effects of camellia oil and camellia oil infused with herbs (Camellia oleifera Abel) on obesity in obese mice fed a high-fat diet (HFD).

METHODS

The antioxidant activity of camellia oil in scavenging free radicals was investigated. Additionally, body and organ weight changes, serum and liver marker parameters, antioxidant enzyme activities, liver and epididymal fat histology, protein and gene expression associated with lipogenesis and hyperglycemia effect on adenosine monophosphate-activated protein kinase (AMPK) phosphorylation, were examined in HFD-induced obese mice.

RESULTS

The hepatic steatosis and epididymal fat were significantly reduced by the oral administration of camellia oil and herb-infused camellia oil. Moreover, hepatic and serum marker parameters such as total cholesterol, insulin, triglycerides, tumor necrosis factor-α, adiponectin, thiobarbituric acid reactive substances, aspartate aminotransferase, and alanine transaminase were beneficially impacted. Additionally, the activity of antioxidant enzymes also increased. Camellia oil and herb-infused camellia oil treatments reduced the expression of genes linked to hyperglycemia and lipogenesis via activation of AMPK phosphorylation.

CONCLUSION

For many people, exercise poses an obstacle in the daily routine due to lack of ease, difficulty in maintaining consistency, and hard work. Camellia oil combined with herbs has anti-obesity and antihyperglycemic effects. These findings indicate that treatment with herb-infused camellia oil is most beneficial for elderly individuals who do not prefer frequent exercise.

The Potential of Cylindromatosis (CYLD) as a Therapeutic Target in Oxidative Stress-Associated Pathologies: A Comprehensive Evaluation

Oxidative stress (OS) arises as a consequence of an imbalance between the formation of reactive oxygen species (ROS) and the capacity of antioxidant defense mechanisms to neutralize them. Excessive ROS production can lead to the damage of critical biomolecules, such as lipids, proteins, and DNA, ultimately contributing to the onset and progression of a multitude of diseases, including atherosclerosis, chronic obstructive pulmonary disease, Alzheimer's disease, and cancer. Cylindromatosis (CYLD), initially identified as a gene linked to familial cylindromatosis, has a well-established and increasingly well-characterized function in tumor inhibition and anti-inflammatory processes. Nevertheless, burgeoning evidence suggests that CYLD, as a conserved deubiquitination enzyme, also plays a pivotal role in various key signaling pathways and is implicated in the pathogenesis of numerous diseases driven by oxidative stress. In this review, we systematically examine the current research on the function and pathogenesis of CYLD in diseases instigated by oxidative stress. Therapeutic interventions targeting CYLD may hold significant promise for the treatment and management of oxidative stress-induced human diseases.

Functional and morphological renal changes in a Göttingen Minipig model of obesity-related and diabetic nephropathy

Obesity-related glomerulopathy and diabetic nephropathy (DN) are serious complications to metabolic syndrome and diabetes. The purpose was to study effects of a fat, fructose and cholesterol-rich (FFC) diet with and without salt in order to induce hypertension on kidney function and morphology in Göttingen Minipigs with and without diabetes. Male Göttingen Minipigs were divided into 4 groups: SD (standard diet, n = 8), FFC (FFC diet, n = 16), FFC-DIA (FFC diet + diabetes, n = 14), FFC-DIA + S (FFC diet with extra salt + diabetes, n = 14). Blood and urine biomarkers, glomerular filtration rate (GFR), blood pressure (BP) and resistive index (RI) were evaluated after 6-7 months (T1) and 12-13 months (T2). Histology, electron microscopy and gene expression (excluding FFC-DIA + S) were evaluated at T2. All groups fed FFC-diet displayed obesity, increased GFR and RI, glomerulomegaly, mesangial expansion (ME) and glomerular basement membrane (GBM) thickening. Diabetes on top of FFC diet led to increased plasma glucose and urea and proteinuria and tended to exacerbate the glomerulomegaly, ME and GBM thickening. Four genes (CDKN1A, NPHS2, ACE, SLC2A1) were significantly deregulated in FFC and/or FFC-DIA compared to SD. No effects on BP were observed. Göttingen Minipigs fed FFC diet displayed some of the renal early changes seen in human obesity. Presence of diabetes on top of FFC diet exacerbated the findings and lead to changes resembling the early phases of human DN.

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

BACKGROUND AND AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

Anti-Obesity Effects of Formulated Biscuits Supplemented with Date's Fiber; Agro-Waste Products Used as a Potent Functional Food

Superabundant date fruit production in Al-Qassim in the Kingdom of Saudi Arabia (KSA), a plentiful region for producing date syrup resulting in massive amounts of date fiber (DF), causes environmental issues with what is considered dietary waste. However, no food producer or researcher has thought of the valorization of DF by extracting the crude polysaccharides that can be converted to nanoparticles (flours) to increase its functional group and enhance its functionality. Using the DF was the primary goal, with the new biscuits used within the current study investigated as a potent integrated approach for controlling obesity levels and its effects. Obesity is one of the most important human problems worldwide, connected to many metabolic diseases, e.g., diabetes mellitus and cardiovascular disease. Its prevalence has recently increased among Saudi children and adolescents. An investigation of the biological effects of the formulated products was carried out by feeding the formulated biscuits with different DF levels (5, 10 and 15%) to obese albino rats, in addition to positive and negative control groups, to evaluate the effect of a reduced calorie product on controlling their body weight and health stats (lipid profile, blood sugars, kidney and liver functions). The collected data showed that the most positive results were obtained from rats fed diets supplemented with 10% DF biscuits. All TCHO, TrGs, HDL, and HDL were decreased to the best levels in this group compared to the positive control group (148.23, 145.30, 37.50, and 81.67 vs. 238.37, 199.07, 62.57, and 135.99, respectively). To conclude, DF supplementation presented anti-obesity properties in animal models; however, more epidemiological trials are needed.

MC-LR Aggravates Liver Lipid Metabolism Disorders in Obese Mice Fed a High-Fat Diet via PI3K/AKT/mTOR/SREBP1 Signaling Pathway

Obesity, a metabolic disease caused by excessive fat accumulation in the body, has attracted worldwide attention. Microcystin-LR (MC-LR) is a hepatotoxic cyanotoxin which has been reportedly to cause lipid metabolism disorder. In this study, C57BL/6J mice were fed a high-fat diet (HFD) for eight weeks to build obese an animal model, and subsequently, the obese mice were fed MC-LR for another eight weeks, and we aimed to determine how MC-LR exposure affects the liver lipid metabolism in high-fat-diet-induced obese mice. The results show that MC-LR increased the obese mice serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT), indicating damaged liver function. The lipid parameters include serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and liver TG, which were all increased, whilst the high-density lipoprotein cholesterol (HDL-c) was decreased. Furthermore, after MC-LR treatment, histopathological observation revealed that the number of red lipid droplets increased, and that steatosis was more severe in the obese mice. In addition, the lipid synthesis-related genes were increased and the fatty acid β-oxidation-related genes were decreased in the obese mice after MC-LR exposure. Meanwhile, the protein expression levels of phosphorylation phosphatidylinositol 3-kinase (p-PI3K), phosphorylation protein kinase B (p-AKT), phosphorylation mammalian target of rapamycin (p-mTOR), and sterol regulatory element binding protein 1c (SREBP1-c) were increased; similarly, the p-PI3K/PI3K, p-AKT/AKT, p-mTOR/mTOR, and SREBP1/β-actin were significantly up-regulated in obese mice after being exposed to MC-LR, and the activated PI3K/AKT/mTOR/SREBP1 signaling pathway. In addition, MC-LR exposure reduced the activity of superoxide dismutase (SOD) and increased the level of malondialdehyde (MDA) in the obese mice's serum. In summary, the MC-LR could aggravate the HFD-induced obese mice liver lipid metabolism disorder by activating the PI3K/AKT/mTOR/SREBP1 signaling pathway to hepatocytes, increasing the SREBP1-c-regulated key enzymes for lipid synthesis, and blocking fatty acid β-oxidation.

Cardiovascular Disease Risk Reduction and Body Mass Index

PURPOSE OF REVIEW

Anti-hypertensive and lipid lowering therapy addresses only half of the cardiovascular disease risk in patients with body mass index > 30 kg/m², i.e., obesity. We examine newer aspects of obesity pathobiology that underlie the partial effectiveness of anti-hypertensive lipid lowering therapy for the reduction of cardiovascular disease risk in obesity.

RECENT FINDINGS

Obesity-related insulin resistance, vascular endothelium dysfunction, increased sympathetic nervous system/renin-angiotensin-aldosterone system activity, and glomerulopathy lead to type 2 diabetes, coronary atherosclerosis, and chronic disease kidney disease that besides hypertension and dyslipidemia increase cardiovascular disease risk. Obesity increases cardiovascular disease risk through multiple pathways. Optimal reduction of cardiovascular disease risk in patients with obesity is likely to require therapy targeted at both obesity and obesity-associated conditions.

ACE2 deficiency exacerbates obesity-related glomerulopathy through its role in regulating lipid metabolism

Obesity-related glomerulopathy is a secondary glomerular disease and its incidence has been increased globally in parallel with the obesity epidemic. ORG emerged as a growing cause of end-stage renal disease in recent years. Unbalanced production of adipokines at the adipose tissue as well as low-grade inflammatory processes play central roles in ORG progression. ORG mouse model with ACE2-knockout was generated and kidney injury was evaluated by biochemistry and histological staining assays. Protein and mRNA expressions were quantified by ELISA, western blot or qRT-PCR methods. ACE2 deficiency aggravated ORG-related renal injuries and stimulated both lipid accumulation and inflammatory responses. Further, Nrf2 pathway was deactivated upon ACE2-knockout. By contrast, ACE2 overexpression reactivated Nrf2 pathway and ameliorated ORG symptoms by decreasing fat deposition and reducing inflammatory responses. Our data demonstrated that ACE2 exerted the beneficial effects by acting through Nrf2 signaling pathway, suggesting the protective role of ACE2 against lipid accumulation and inflammatory responses in ORG pathogenesis.

Effect of weight change after renal transplantation on outcomes of graft survival

BACKGROUND AND OBJECTIVE

After kidney transplantation, there is an overall increase in weight, which may increase the risk of chronic kidney disease (CKD) and graft loss. But, not all patients gain weight, and the impact on the graft of this different evolution has not been well studied. The objective was to determine the causes of this different evolution and its effect on the graft.

PATIENTS AND METHODS

Retrospective single-center cohort study of 201 patients followed up after transplantation, analyzing the determinants of the variation in weight at one year using logistic regression, and its effect on graft survival at the end of follow-up using Cox regression.

RESULTS

Globally, there was an average weight gain of 4.5 kg in the first year, but 26.6% lost weight. 37.2% increased their BMI, while 9.5% decreased it. The determinants of the different evolution of weight were age (OR for every 10 years: 0.6, p = 0.002), previous dialysis modality (ref. hemodialysis) (OR 0.3, p = 0.003), and BMI before transplantation (OR 0.9, p = 0.017). The different evolution of weight did not influence the final situation of the graft. The BMI at one year did influence as a continuous variable (HR 1.3, p = 0.003), and obesity, with a worse evolution (HR 7.0, p = 0.025).

CONCLUSIONS

Although not all patients gain weight after kidney transplantation, the different evolution of weight does not influence graft survival.

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

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

Fatty kidney: A possible future for chronic kidney disease research

BACKGROUND

Metabolic syndrome is a growing twenty-first century pandemic associated with multiple clinical comorbidities ranging from cardiovascular diseases, non-alcoholic fatty liver disease and polycystic ovary syndrome to kidney dysfunction. A novel area of research investigates the concept of fatty kidney in the pathogenesis of chronic kidney disease, especially in patients with diabetes mellitus or metabolic syndrome.

AIM

To review the most updated literature on fatty kidney and provide future research, diagnostic and therapeutic perspectives on a disease increasingly affecting the contemporary world.

MATERIALS AND METHOD

We performed an extensive literature search through three databases including Embase (Elsevier) and the Cochrane Central Register of Controlled Trials (Wiley) and PubMed/Medline Web of Science in November 2021 by using the following terms and their combinations: 'fatty kidney', 'ectopic fat', 'chronic kidney disease', 'cardiovascular event', 'cardio-metabolic risk', 'albuminuria' and 'metabolic syndrome'. Each study has been individually assessed by the authors.

RESULTS

Oxidative stress and inflammation, Klotho deficiency, endoplasmic reticulum stress, mitochondrial dysfunction and disruption of cellular energy balance appear to be the main pathophysiological mechanisms leading to tissue damage following fat accumulation. Despite the lack of large-scale comprehensive studies in this novel field of research, current clinical trials demonstrate fatty kidney as an independent risk factor for the development of chronic kidney disease and cardiovascular events.

CONCLUSION

The requirement for future studies investigating the pathophysiology, clinical outcomes and therapeutics of fatty kidney is clear.

A nationwide analysis of renal and patient outcomes for adults with lupus nephritis in Japan

BACKGROUND

The prognosis of lupus nephritis (LN) has improved following the introduction of effective immunosuppressive therapy and progress in supportive care. This study examined recent renal and patient prognosis for adults with LN in Japan.

METHODS

We conducted a nationwide retrospective cohort study of LN patients who received a renal biopsy between 2007 and 2012 that were registered in the Japan Renal Biopsy Registry. Of 623 registered adults with LN from 25 institutions and their affiliated or community hospitals, 489 were eligible for this study.

RESULTS

The median age at renal biopsy was 39 years, and 82.2% of patients were female. Renal biopsies were performed in 348 patients with new-onset LN, 106 with relapse LN, and 35 with refractory LN. The distribution of ISN/RPS 2003 Classes was as follows: I 1.6%; II 5.3%; III (± V) 27.0%; IV (± V) 47.0%; V 18.4%; VI 0.6%. During the median observation period of 63.8 months, 36 patients (7.3%) reached a doubling of serum creatinine or end-stage kidney disease (ESKD), and 28 patients (5.7%) died. The 5 year renal and patient survival rates were 93.9% and 94.7%, respectively. Multivariate analysis revealed body mass index (BMI) and estimated glomerular filtration rate (eGFR) were independent risk factors for a doubling of serum creatinine in ESKD. Age and eGFR were independent risk factors for death.

CONCLUSION

Recent prognosis for adults with LN are relatively good in Japan. Risk factors for impaired renal function are BMI and eGFR at renal biopsy, while age and eGFR are risk factors for death.

Chronic constant light exposure aggravates high fat diet-induced renal injury in rats

Obesity-related kidney disease is now recognized as a global health issue, with a substantial number of patients developing progressive renal failure and end-stage renal disease. Interestingly, recent studies indicate light pollution is a novel environmental risk factor for chronic kidney disease. However, the impact of light pollution on obesity-related kidney disease remains largely unknown, with its underlying mechanism insufficiently explained. Renal hypoxia induced factor 1α (HIF1α) is critical in the development of glomerulosclerosis and renal fibrosis. The present study explored effects of constant light exposure on high fat diet (HFD) -induced renal injury and its association with HIF1α signal pathway. Thirty-two male Sprague Dawley rats were divided into four groups according to diet (HFD or normal chow diet) and light cycles (light/dark or constant light). After 16 weeks treatment, rats were sacrificed and pathophysiological assessments were performed. In normal chow fed rats, constant light exposure led to glucose abnormalities and dyslipidemia. In HFD fed rats, constant light exposure exacerbated obesity, glucose abnormalities, insulin resistance, dyslipidemia, renal functional decline, proteinuria, glomerulomegaly, renal inflammation and fibrosis. And, constant light exposure caused an increase in HIF1α and a decrease in prolyl hydroxylase domain 1 (PHD1) and PHD2 expression in kidneys of HFD-fed rats. Then, we demonstrated that BMAL1 bound directly to the promoters of PHD1 in mouse podocyte clone 5 cell line (MPC5) by ChIP assays. In conclusion, chronic constant light exposure aggravates HFD-induced renal injuries in rats, and it is associated with activation of HIF1α signal pathway.

Diabetes duration and types of diabetes treatment in data-driven clusters of patients with diabetes

BACKGROUND

This study aimed to cluster patients with diabetes and explore the association between duration of diabetes and diabetes treatment choices in each cluster.

METHODS

A Two-Step cluster analysis was performed on 1332 Chinese patients with diabetes based on six parameters (glutamate decarboxylase antibodies, age at disease onset, body mass index, glycosylated hemoglobin, homeostatic model assessment 2 to estimate β-cell function and insulin resistance). Associations between the duration of diabetes and diabetes treatment choices in each cluster of patients were analyzed using Kaplan-Meier survival curves and logistic regression models.

RESULTS

The following five replicable clusters were identified: severe autoimmune diabetes (SAID), severe insulin-deficient diabetes (SIDD), severe insulin-resistant diabetes (SIRD), mild obesity-related diabetes (MOD), and mild age-related diabetes (MARD). There were significant differences in blood pressure, blood lipids, and diabetes-related complications among the clusters (all P < 0.05). Early in the course of disease (≤5 years), compared with the other subgroups, the SIRD, MOD, and MARD populations were more likely to receive non-insulin hypoglycemic agents for glycemic control. Among the non-insulin hypoglycemic drug options, SIRD had higher rates of receiving metformin, alpha-glucosidase inhibitor (AGI), and glucagon-like peptide-1 drug; the MOD and MARD groups both received metformin, AGI and sodium-glucose cotransporter 2 inhibitor (SGLT-2i) drug ratio was higher. While the SAID and SIDD groups were more inclined to receive insulin therapy than the other subgroups, with SAID being more pronounced. With prolonged disease course (>5 years), only the MOD group was able to accept non-insulin hypoglycemic drugs to control the blood sugar levels, and most of them are still treated with metformin, AGI, and SGLT-2i drugs. While the other four groups required insulin therapy, with SIDD being the most pronounced.

CONCLUSIONS

Clustering of patients with diabetes with a data-driven approach yields consistent results. Each diabetes cluster has significantly different disease characteristics and risk of diabetes complications. With the development of the disease course, each cluster receives different hypoglycemic treatments.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Effects of female obesity on conception, pregnancy and the health of offspring

As we all know, female obesity has become a global epidemic, which is usually accompanied with endocrine and metabolic disorders. Obese women are more likely to experience reproductive problems, including infertility, embryonic developmental defects and abnormality in offspring. Female obesity is a complex multifactorial condition, where there are many mechanisms involved in the effects of overweight and obesity on the development of these reproductive disorders. The insulin resistance, hyperinsulinaemia and hyperandrogenism, lipotoxicity and inflammation are important mechanisms. However, the precise mechanism concerning their correlation is still unclear. Fortunately, weight loss methods have been found to reverse the effects of maternal obesity on the fertility, fetus and offspring.

Enhanced prediction of renal function decline by replacing waist circumference with "A Body Shape Index (ABSI)" in diagnosing metabolic syndrome: a retrospective cohort study in Japan

Background

Abdominal obesity as a risk factor for diagnosing metabolic syndrome (MetS) is conventionally evaluated using waist circumference (WC), although WC does not necessarily reflect visceral adiposity.

Objective

To examine whether replacing WC with “A Body Shape Index (ABSI)”, an abdominal obesity index calculated by dividing WC by an allometric regression of weight and height, in MetS diagnosis is useful for predicting renal function decline.

Subjects/Methods

In total, 5438 Japanese urban residents (median age 48 years) who participated in a public health screening program for 4 consecutive years were enrolled. Systemic arterial stiffness was assessed by cardio-ankle vascular index (CAVI). The predictability of the new-onset renal function decline (eGFR < 60 mL/min/1.73 m²) by replacing high WC with high ABSI (ABSI ≥ 0.080) was examined using three sets of MetS diagnostic criteria: Japanese, IDF and NCEP-ATPIII.

Results

In Japanese and NCEP-ATPIII criteria, MetS diagnosed using ABSI (ABSI-MetS) was associated with significantly higher age-adjusted CAVI compared to non-MetS, whereas MetS diagnosed using WC (WC-MetS) showed no association. Kaplan–Meier analysis of the rate of new-onset renal function decline over 4 years (total 8.7%) showed remarkable higher rate in subjects with ABSI-MetS than in those without (log-rank test p < 0.001), but almost no difference between subjects with and without WC-MetS (p = 0.014–0.617). In gender-specific Cox-proportional hazards analyses including age, proteinuria, and treatments of metabolic disorders as confounders, ABSI-MetS (Japanese criteria for both sexes, IDF criteria for men) contributed independently to the new-onset renal function decline. Of these, the contribution of IDF ABSI-MetS disappeared after adjustment by high CAVI in the subsequent analysis.

Conclusion

In this study, replacing WC with ABSI in MetS diagnostic criteria more efficiently predicted subjects at risk of renal function decline and arterial stiffening.

IκB kinase promotes Nrf2 ubiquitination and degradation by phosphorylating cylindromatosis, aggravating oxidative stress injury in obesity-related nephropathy

BACKGROUND

Obesity-related nephropathy (ORN) has become one of the leading causes of end-stage renal disease and has tripled over the past decade. Previous studies have demonstrated that decreased reactive oxygen species production may contribute to improving ORN by ameliorating oxidative stress injury. Here, IκB kinase (IKK) was hypothesized to inactivate the deubiquitination activity of cylindromatosis (CYLD) by activating the phosphorylation of CYLD, thus promoting the ubiquitination of NF-E2-related factor 2 (Nrf2) and further aggravating oxidative stress injury of the kidney in ORN. This study was aimed to confirm this hypothesis.

METHODS

Haematoxylin and eosin (HE), periodic acid-Schiff (PAS) and Oil Red O staining were performed to assess histopathology. Dihydroethidium (DHE) staining and MDA, SOD, CAT, and GSH-PX assessments were performed to measure reactive oxygen species (ROS) production. Immunohistochemical (IHC) staining, qRT-PCR and/or western blotting were performed to assess the expression of related genes. JC-1 assays were used to measure the mitochondrial membrane potential (ΔΨm) of treated HK-2 cells. Co-immunoprecipitation experiments (Co-IP) were used to analyse the interaction between CYLD and Nrf2 in ORN.

RESULTS

ORN in vivo and in vitro models were successfully constructed, and oxidative stress injury was detected in the model tissues and cells. Compared with the control groups, the phosphorylation level of CYLD increased while Nrf2 levels decreased in ORN model cells. An IKK inhibitor reduced lipid deposition, ROS production, CYLD phosphorylation levels and ΔΨm in vitro, which were reversed by knockdown of CYLD. Nrf2 directly bound to CYLD and was ubiquitinated in ORN cells. The proteasome inhibitor MG132 activated the Nrf2/ARE signalling pathway, thereby reversing the promoting effect of CYLD knockdown on oxidative stress.

CONCLUSION

IKK inactivates the deubiquitination activity of CYLD by activating the phosphorylation of CYLD, thus promoting the ubiquitination of Nrf2 and further aggravating oxidative stress injury of the kidney in ORN. This observation provided a feasible basis for the treatment of kidney damage caused by ORN.

Obesity and chronic kidney disease: prevalence, mechanism, and management

The prevalence of childhood obesity is increasing worldwide at an alarming rate. While obesity is known to increase a variety of cardiovascular and metabolic diseases, it also acts as a risk factor for the development and progression of chronic kidney disease (CKD). During childhood and adolescence, severe obesity is associated with an increased prevalence and incidence of the early stages of kidney disease. Importantly, children born to obese mothers are also at increased risk of developing obesity and CKD later in life. The potential mechanisms underlying the association between obesity and CKD include hemodynamic factors, metabolic effects, and lipid nephrotoxicity. Weight reduction via increased physical activity, caloric restriction, treatment with angiotensin-converting enzyme inhibitors, and judicious bariatric surgery can be used to control obesity and obesity-related kidney disease. Preventive strategies to halt the obesity epidemic in the healthcare community are needed to reduce the widespread deleterious consequences of obesity including CKD development and progression.

Improvement of Renal Function After Bariatric Surgery: a Systematic Review and Meta-analysis

BACKGROUND/OBJECTIVE

The effect of bariatric surgery in renal function varies and the postoperative benefit time point remains unclear. We aim to assess the changes of renal function after bariatric surgery (BS) in different postoperative periods and subgroups.

METHODS

We searched the databases of PubMed and Cochrane from inception to December 14, 2020. Articles included in the study were drawn from all recipients of BS that provided assessments of renal function pre and post-surgery. Meta-analysis was performed to compare glomerular filtration rate (GFR), serum creatinine, albumin-to-creatinine ratio (ACR), and albuminuria before and after BS.

RESULTS

The study included 49 articles involving 8515 patients. Compared with pre-operative renal function, the overall analysis showed that bariatric surgery significantly reduced serum creatinine levels, ACR, and albuminuria. There was significant increase of GFR in the CKD subgroup, yet a noticeable decrease in the hyperfiltration subgroup. The most significant improvement in GFR was seen 6-12 months after BS, while ACR dropped most dramatically 12-24 months after BS.

CONCLUSIONS

Bariatric surgery can improve renal function in obese patients with kidney dysfunction, especially 1 year after surgery.

Effect of weight change after renal transplantation on outcomes of graft survival

BACKGROUND AND OBJECTIVE

After kidney transplantation, there is an overall increase in weight, which may increase the risk of chronic kidney disease (CKD) and graft loss. But, not all patients gain weight, and the impact on the graft of this different evolution has not been well studied. The objective was to determine the causes of this different evolution and its effect on the graft.

PATIENTS AND METHODS

Retrospective single-center cohort study of 201 patients followed up after transplantation, analyzing the determinants of the variation in weight at one year using logistic regression, and its effect on graft survival at the end of follow-up using Cox regression.

RESULTS

Globally, there was an average weight gain of 4.5kg in the first year, but 26.6% lost weight. 37.2% increased their BMI, while 9.5% decreased it. The determinants of the different evolution of weight were age (OR for every 10 years: 0.6, P=.002), previous dialysis modality (ref. hemodialysis) (OR 0.3, P=.003), and BMI before transplantation (OR 0.9, P=.017). The different evolution of weight did not influence the final situation of the graft. The BMI at one year did influence as a continuous variable (HR 1.3, P=.003), and obesity, with a worse evolution (HR 7.0, P=.025).

CONCLUSIONS

Although not all patients gain weight after kidney transplantation, the different evolution of weight does not influence graft survival.

Differences between Obese and Non-Obese Children and Adolescents Regarding Their Oral Status and Blood Markers of Kidney Diseases

(1) Background: A rarely discussed effect of obesity-related glomerulopathy (ORG) may slowly lead to irreversible glomerular damage and the development of chronic kidney disease. These patients need to undertake medical care, but whether they should be included in intensive oral care is still not mandatory. The study aimed to assess a relationship between renal, metabolic, and oral health indicators among pediatric patients affected by simple obesity. (2) Methods: 45 children and adolescents with simple obesity hospitalized (BMI 34.1 ± 4.8 kg/m², age 15.4 ± 2.3) and compared with 41 aged-matched healthy controls (BMI 16.4 ± 2.4 kg/m², age 15.4 ± 2.7). Echocardiography, 24-h ambulatory blood pressure monitoring, ultrasound exam with Doppler, and laboratory tests including kidney and metabolic markers were performed. Oral status was examined regarding the occurrence of carious lesions using decay missing filling teeth (DMFT), gingivitis as bleeding on probing (BOP), and bacterial colonization as plaque control record (PCR). (3) Results: The strongest correlation was revealed between BMI and concentration of uric acid, cystatin C, GFR estimated by the Filler formula (r = 0.74; r = 0.48; r = -0.52), and between oral variables such as PCR and BOP (r = 0.54; r = 0.58). Children and adolescents with obesity demonstrated untreated dental caries, less efficient in plaque control and gingivitis. (4) Conclusions: No specific relation to markers of kidney disease were found; however, more frequent gingivitis/bacterial colonization and significant differences in oral status between obese and non-obese patients were revealed. Susceptibility to inflammation may be conducive to developing metabolic syndrome and kidney damage in the form of obesity-related glomerulopathy and contribute to future dental caries. Uric acid seems to indicate metabolic syndrome and cardiovascular complications (LVMI > 95 percentiles). Cystatin C and uric acid might aspire to be early markers of kidney damage leading to obesity-related glomerulopathy.

Adiponectin protects obesity-related glomerulopathy by inhibiting ROS/NF-κB/NLRP3 inflammation pathway

BACKGROUND

Adiponectin is an adipocytokine that plays a key regulatory role in glucose and lipid metabolism in obesity. The prevalence of obesity has led to an increase in the incidence of obesity-related glomerulopathy (ORG). This study aimed to identify the protective role of adiponectin in ORG.

METHODS

Small-interfering RNA (siRNA) against the gene encoding adiponectin was transfected into podocytes. The oxidative stress level was determined using a fluorometric assay. Apoptosis was analyzed by flow cytometry. The expressions of podocyte markers and pyrin domain containing protein 3 (NLRP3) inflammasome-related proteins were measured by qRT-PCR, immunohistochemistry, and Western blot.

RESULTS

Podocytes treated with palmitic acid (PA) showed downregulated expressions of podocyte markers, increased apoptosis, upregulated levels of NLRP3 inflammasome-related proteins, increased production of inflammatory cytokines (IL-18 and IL-1β), and induced activation of NF-κB as compared to the vehicle-treated controls. Decreased adiponectin expression was observed in the serum samples from high fat diet (HFD)-fed mice. Decreased podocin expression and upregulated NLRP3 expression were observed in the kidney samples from high fat diet (HFD)-fed mice. Treatment with adiponectin or the NLRP3 inflammasome inhibitor, MCC950, protected cultured podocytes against podocyte apoptosis and inflammation. Treatment with adiponectin protected mouse kidney tissues against decreased podocin expression and upregulated NLRP3 expression. The knockout of adiponectin gene by siRNA increased ROS production, resulting in the activation of NLRP3 inflammasome and the phosphorylation of NF-κB in podocytes. Pyrrolidine dithiocarbamate, an NF-κB inhibitor, prevented adiponectin from ameliorating FFA-induced podocyte injury and NLRP3 activation.

CONCLUSIONS

Our study showed that adiponectin ameliorated PA-induced podocyte injury in vitro and HFD-induced injury in vivo via inhibiting the ROS/NF-κB/NLRP3 pathway. These data suggest the potential use of adiponectin for the prevention and treatment of ORG.

Successful Reuse of Kidney Graft After Early Recurrence of Primary Focal and Segmental Glomerulosclerosis

Primary focal and segmental glomerulosclerosis (FSGS) frequently recurs after transplantation and is associated with a poor prognosis. We describe here the successful kidney graft reuse in an adult recipient, 8 months after early primary FSGS recurrence resistant to all available therapeutics. Patient 1, a 23-year-old man, followed for kidney failure secondary to primary FSGS, was first transplanted in 2018 with a deceased donor graft. Unfortunately, we observed an immediate recurrence of biopsy-proven primary FSGS. After 4 lines of treatment (intravenous cyclosporine+corticosteroids, plasma exchanges, immunoadsorption, and rituximab), the patient was still highly nephrotic and kidney function was slowly deteriorating. After approval from both the patient and the health authority (Biomedicine Agency), the graft was detransplanted 8 months after transplantation and reimplanted in patient 2, a 78-year-old nonimmunized and anephric recipient (bi-nephrectomy 2 years previously for bilateral renal carcinoma). We observed immediate kidney function and progressive resolution of proteinuria (serum creatinine of 1.2mg/dL and proteinuria of 0.1 g/d 1 year later). Biopsies performed after surgery showed persistent FSGS lesions with a decrease in overall foot-process effacement. To our knowledge, this is the first reported case showing that kidney graft transfer may still be a viable option for refractory primary FSGS several months after transplantation.

Oral administration of camellia oil ameliorates obesity and modifies the gut microbiota composition in mice fed a high-fat diet

Obesity, which is often caused by adipocyte metabolism dysfunction, is rapidly becoming a serious global health issue. Studies in the literature have shown that camellia oil (Camellia oleifera Abel) exerted potential lipid regulation and other multiple biological activities. Here, we aimed to investigate the effects of camellia oil on obese mice induced by a high-fat diet and to explore gut microbiota alterations after camellia oil intervention. The results showed that oral administration of camellia oil dramatically attenuated the fat deposits, serum levels of the total cholesterol, triacylglycerol, low-density lipoprotein cholesterol, fasting plasma glucose, the atherosclerosis index, the hepatic steatosis and inflammation in high-fat diet-induced obese mice. Meanwhile, the high-density lipoprotein cholesterol level in obese mice was enhanced after the camellia oil treatment. Furthermore, 16S rRNA analysis showed that certain aspects of the gut microbiota, especially the gut microbiota diversity and the relative abundance of Actinobacteria, Coriobacteriaceae, Lactobacillus and Anoxybacillus, were significantly increased by camellia oil treatment while the ratio of Firmicutes to Bacteroidetes was decreased. Taken together, our finding suggested that camellia oil was a potential dietary supplement and functional food for ameliorating fat deposits, hyperglycemia and fatty liver, probably by modifying the gut microbiota composition.

Emodin Attenuated the Kidney Damage of High-Fat-Diet Mice via the Upregulation of Glucagon-Like Peptide-1 Receptor

Objective

Secretion of glucagon-like peptide 1 (GLP-1) and its effect on target organs were impaired in individuals with obesity. However, its mechanism needs to be further studied. We aim to explore the roles of the receptor of GLP-1 (GLP-1R) involved in high-fat-diet- (HFD-) induced kidney damage improved by emodin.

Methods

Male C57bl/6 mice were fed with HFD diet and therapied by emodin. NRK-52E cells were cultured and treated with palmitic acid or low-density lipoprotein cholesterol (LDL-C). Emodin was used to remedy the NRK-52E cell damage. GW9662 was administrated to block the function of peroxisome proliferator-activated receptor γ (PPAR-γ). GLP-1 in the plasma was measured by ELISA. PPAR-γ and GLP-1R in the kidney and NRK-52E cells were detected by western blotting. The interaction between PPAR-γ protein and GLP-1R promoter regions was observed by chromatin immunoprecipitation (ChIP).

Results

Postprandial GLP-1 levels in plasma, as well as PPAR-γ and GLP-1R, decreased in kidney tissue of HFD mice, while they were reserved by emodin treatment. Although PPAR-γ and GLP-1R were not downregulated by LDL-C, they were suppressed by palmitic acid. Interestingly, GLP-1R mRNA was detected by PCR in the mixture pulled down with PPAR-γ antibody. Additionally, downregulation of PPAR-γ and GLP-1R by palmitic acid was remanded by emodin. Moreover, GW9662, an inhibitor of PPAR-γ, abolished the protective effect of emodin.

Conclusion

The kidney damage of HFD mice seems to be alleviated by emodin via the upregulation of GLP-1R in kidney tissue.

A Nephrologist Perspective on Obesity: From Kidney Injury to Clinical Management

Obesity is one of the epidemics of our era. Its prevalence is higher than 30% in the U.S. and it is estimated to increase by 50% in 2030. Obesity is associated with a higher risk of all-cause mortality and it is known to be a cause of chronic kidney disease (CKD). Typically, obesity-related glomerulopathy (ORG) is ascribed to renal hemodynamic changes that lead to hyperfiltration, albuminuria and, finally, impairment in glomerular filtration rate due to glomerulosclerosis. Though not only hemodynamics are responsible for ORG: adipokines could cause local effects on mesangial and tubular cells and podocytes promoting maladaptive responses to hyperfiltration. Furthermore, hypertension and type 2 diabetes mellitus, two conditions generally associated with obesity, are both amplifiers of obesity injury in the renal parenchyma, as well as complications of overweight. As in the native kidney, obesity is also related to worse outcomes in kidney transplantation. Despite its impact in CKD and cardiovascular morbility and mortality, therapeutic strategies to fight against obesity-related CKD were limited for decades to renin-angiotensin blockade and bariatric surgery for patients who accomplished very restrictive criteria. Last years, different drugs have been approved or are under study for the treatment of obesity. Glucagon-like peptide-1 receptor agonists are promising in obesity-related CKD since they have shown benefits in terms of losing weight in obese patients, as well as preventing the onset of macroalbuminuria and slowing the decline of eGFR in type 2 diabetes. These new families of glucose-lowering drugs are a new frontier to be crossed by nephrologists to stop obesity-related CKD progression.

Perirenal Adipose Tissue-Current Knowledge and Future Opportunities

The perirenal adipose tissue (PRAT), a component of visceral adipose tissue, has been recently recognized as an important factor that contributes to the maintenance of the cardiovascular system and kidney homeostasis. PRAT is a complex microenvironment consisting of a mixture of white adipocytes and dormant and active brown adipocytes, associated with predipocytes, sympathetic nerve endings, vascular structures, and different types of inflammatory cells. In this review, we summarize the current knowledge about PRAT and discuss its role as a major contributing factor in the pathogenesis of hypertension, obesity, chronic renal diseases, and involvement in tumor progression. The new perspectives of PRAT as an endocrine organ and recent knowledge regarding the possible activation of dormant brown adipocytes are nowadays considered as new areas of research in obesity, in close correlation with renal and cardiovascular pathology. Supplementary PRAT complex intervention in tumor progression may reveal new pathways involved in carcinogenesis and, implicitly, may identify additional targets for tailored cancer therapy.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Effect of Conventional Medical Therapy or Laparoscopic Sleeve Gastrectomy on Urinary Albumin in Japanese Subjects with Severe Obesity: An Observational Study

INTRODUCTION

In patients with severe obesity, albuminuria can be improved by both conventional medical therapy and bariatric surgery. The purpose of this study was to compare the impact of weight loss achieved through conventional medical therapy or laparoscopic sleeve gastrectomy (LSG) on albuminuria in Japanese subjects with severe obesity and identify the factors involved.

METHODS

We retrospectively evaluated the clinical characteristics including the urinary albumin/creatinine ratio (UACR) of 340 consecutive subjects with a body mass index ≥35 who received LSG (n = 242) or medical therapy (n = 98) between 2010 and 2018 and were followed for at least 12 months.

RESULTS

The baseline of the UACR was not different between the 2 groups. At the 12-month follow-up, total weight loss (TWL) and decreases in glycosylated hemoglobin (HbA1c) and loge UACR were greater in the LSG group than in the medical therapy group (body weight; -35.7 kg vs. -8.0 kg, p < 0.001, HbA1c; -1.4% vs. -0.7%, p < 0.001, loge UACR; -0.3 vs. 0.9, p < 0.001). The rate of complete remission of diabetes was significantly higher in the LSG group than in the medical therapy group. At 12 and 36 months (n = 111 in the medical therapy group, n = 56 in the LSG group at 36 months), loge UACR increased in the medical therapy group, while it remained unchanged or decreased in the LSG group. In subjects with microalbuminuria and macroalbuminuria, changes in the loge UACR correlated with percent total body weight loss (%TWL) in both groups at 12 months. Percent TWL contributed independently to the change in the loge UACR, irrespective of whether LSG was performed. In receiver-operating characteristic analysis, a weight loss of 7.8% predicted a decrease in the UACR (∆UACR <0 at 12 months).

CONCLUSION

Our analysis suggests that albuminuria may increase over time if only medical therapy is continued. To improve albuminuria, weight loss may be more important than whether LSG is performed.

Relation of Maximum Lifetime Body Mass Index with Age at Hemodialysis Initiation and Vascular Complications in Japan

OBJECTIVE

The aim of this study was to investigate the association of the maximum lifetime body mass index (max BMI) with hemodialysis initiation and comorbidities in Japanese hemodialysis patients.

METHODS

In a retrospective cross-sectional study on 724 hemodialysis patients, max BMI, age at hemodialysis initiation, and comorbidities including sleep apnea syndrome, cerebro-cardiovascular diseases, and proliferative diabetic retinopathy (PDR) were analyzed. Early hemodialysis initiation was defined as age <50 years.

RESULT

Diabetes patients showed a higher max BMI and prevalence of atherosclerotic diseases than nondiabetes patients, despite almost the same age at hemodialysis initiation. Patients with early hemodialysis initiation showed higher male ratio, prevalence of PDR, and max BMI than those with later initiation, despite almost equal prevalence of diabetes. Receiver-operating characteristic curve analysis determined a max BMI of 28.4 kg/m2 as a reliable cutoff value for predicting early hemodialysis initiation, and this parameter was identified as an independent predictor of early hemodialysis initiation using bivariate logistic regression analysis. Vitrectomy for PDR also tended to contribute independently to early hemodialysis initiation.

CONCLUSION

A high max BMI contributed to early hemodialysis initiation independent of diabetes. Furthermore, PDR was associated with a high max BMI and early hemodialysis initiation. These results suggest that weight reduction in young chronic kidney disease patients with obesity may prevent hemodialysis and blindness.

Bariatric Surgery Improves Renal Function: a Large Inner-City Population Outcome Study

BACKGROUND

Bariatric surgery is associated with improved renal dysfunction in general population studies. The study examined the effects of bariatric surgery on renal function in a predominantly Hispanic and African American population at a community hospital in New York, USA.

METHODS

This retrospective study analyzed prospectively collected bariatric surgical data from 2247 patients (89% female) who underwent bariatric surgery at a single center. Changes in glomerular filtration rate (eGFR), urine albumin-creatinine ratio (UACR), micro- and macroalbuminuria, and hyperfiltration, which were measured preoperatively and then yearly for 3 years postoperatively, were evaluated with t tests and logistic regression analysis, after adjusting for confounding variables. The mean age of the patients at surgery was 37.1 years; the mean preoperative body mass index was 45 ± 7 kg/m².

RESULTS

The results obtained 3 years postoperatively showed the following significant improvements compared with the preoperative values: mean UACR decreased from 40.3 to 11.1 mg/g, mean eGFR improved from 79.4 to 87.3 mL/min, the prevalence of microalbuminuria decreased from 13.7 to 6.2%, the prevalence of macroalbuminuria decreased from 2.5 to 0%, and the prevalence of hyperfiltration decreased from 4.4 to 2.7% (all P < .0001). In adjusted multivariate regression analysis, these results remained significant after adjusting for age, sex, race, type of surgery, and presence of diabetes mellitus or hypertension.

CONCLUSION

In this large study at an inner-city hospital, bariatric surgery was associated with significant improvements in renal dysfunction parameters. These results could assist with informed decisions regarding indications for bariatric surgery.

Podocytopathies

Podocytopathies are kidney diseases in which direct or indirect podocyte injury drives proteinuria or nephrotic syndrome. In children and young adults, genetic variants in >50 podocyte-expressed genes, syndromal non-podocyte-specific genes and phenocopies with other underlying genetic abnormalities cause podocytopathies associated with steroid-resistant nephrotic syndrome or severe proteinuria. A variety of genetic variants likely contribute to disease development. Among genes with non-Mendelian inheritance, variants in APOL1 have the largest effect size. In addition to genetic variants, environmental triggers such as immune-related, infection-related, toxic and haemodynamic factors and obesity are also important causes of podocyte injury and frequently combine to cause various degrees of proteinuria in children and adults. Typical manifestations on kidney biopsy are minimal change lesions and focal segmental glomerulosclerosis lesions. Standard treatment for primary podocytopathies manifesting with focal segmental glomerulosclerosis lesions includes glucocorticoids and other immunosuppressive drugs; individuals not responding with a resolution of proteinuria have a poor renal prognosis. Renin-angiotensin system antagonists help to control proteinuria and slow the progression of fibrosis. Symptomatic management may include the use of diuretics, statins, infection prophylaxis and anticoagulation. This Primer discusses a shift in paradigm from patient stratification based on kidney biopsy findings towards personalized management based on clinical, morphological and genetic data as well as pathophysiological understanding.

Sulforaphane suppresses obesity-related glomerulopathy-induced damage by enhancing autophagy via Nrf2

AIMS

Obesity-related glomerulopathy (ORG) is characterized by glomerulomegaly with or without focal and segmental glomerulosclerosis lesions. Isothiocyanate sulforaphane (SFN) can protect kidneys from ORG-related damages. In this study, we investigated the effects of SFN as a preventive therapy or intervention for ORG to reveal its mechanism of action.

MAIN METHODS

We established a mouse obesity model with preventive SFN or N-acetylcysteine treatment for 2 months. Thereafter, we used nuclear factor erythroid 2-related factor 2-deficient (Nrf2^-/-) and wild type mice in our ORG model with SFN treatment. Finally, we generated a corresponding mouse podocyte model in vitro. The body weight, wet weight of perirenal-and peritesticular fat, and urinary albumin/creatinine ratio were assessed. We used periodic acid-Schiff staining and electron microscopy to assess the function of the kidneys and podocytes. In addition, we evaluated the expression of Nrf2 and podocyte-specific proteins by western blotting.

KEY FINDINGS

Treatment with SFN reduced body weight, organ-associated fat weight, and urinary albumin/creatinine ratio in both the preventive treatment and disease intervention regimens. SFN treated mice exhibited higher expression levels of podocyte-specific proteins and better podocyte function. However, treatment with SFN did not affect these parameters in obese Nrf2^-/- mice. Light chain 3 of microtubule-associated protein 1-II and metallothionein had higher expression in the wild type than in the Nrf2^-/- mice.

SIGNIFICANCE

Treatment with SFN limited ORG-induced damage by enhancing podocyte autophagy via Nrf2.