Inflammation and oxidative stress in obesity-related glomerulopathy

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.

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

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

Oxidative Stress Contributes to Slit Diaphragm Defects Caused by Disruption of Endocytosis

Introduction

Podocyte slit diaphragms are an important component of the glomerular filtration barrier. Podocyte injury frequently includes defects in slit diaphragms, and various mechanisms for these defects have been described, including altered endocytic trafficking of slit diaphragm proteins or oxidative stress. However, the potential relationship between endocytosis and oxidative stress in the context of slit diaphragm integrity has not been extensively considered.

Methods

To examine the potential relationships between endocytosis, oxidative stress, and slit diaphragm integrity, we induced genetic or pharmacological disruption of endocytosis in Drosophila nephrocytes (the insect orthologue of podocytes) and cultured human podocytes. We then employed immunofluorescence microscopy to analyze protein localization and levels, and to quantify signal from reactive oxygen species (ROS) dyes. Immunoprecipitation from podocyte cell lysates was used to examine effects on slit diaphragm protein complex formation (i.e., nephrin/podocin and nephrin/ZO-1).

Results

Disruption of endocytosis in nephrocytes and podocytes led to slit diaphragm defects, elevated levels of ROS (oxidative stress), and activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway. In nephrocytes with defective endocytosis, perturbation of Nrf2 signaling exacerbated slit diaphragm defects. Conversely, overexpression of Nrf2 target genes catalase or glucose-6-phosphate dehydrogenase (G6PD) significantly ameliorated slit diaphragm defects caused by disruption of endocytosis.

Conclusion

Oxidative stress is an important consequence of defective endocytosis and contributes to the defects in slit diaphragm integrity associated with disruption of endocytic trafficking.

Benefits of Chronic Administration of a Carbohydrate-Free Diet on Biochemical and Morphometric Parameters in a Rat Model of Diet-Induced Metabolic Syndrome

Carbohydrate intake restriction positively affects markers related to metabolic syndrome (MS). However, the effects of long-term carbohydrate-free diets (CFD) have yet to be studied. The main objective of this study was to report the effects on biochemical and morphometric parameters in a rat model of MS. Male Wistar rats were initially divided into two groups: the standard diet group (SD, n = 20); and the MS group (n = 30) fed a high-glucose diet. Ten animals from each group were sacrificed after 20 weeks on their respective diets to verify MS development. The remaining MS animals were divided into two subgroups: one continued with the MS diet (n = 10); and the other transitioned to a carbohydrate-free diet (MS + CFD group, n = 10) for 20 more weeks. At week 40, parameters, including glucose, insulin, lipid profile, ketone bodies, C-reactive protein (CRP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, creatinine, liver and muscle glycogen, and serum, hepatic, renal, and pancreatic malondialdehyde (MDA) levels were assessed. Transitioning to CFD resulted in decreased caloric intake and body weight, with normalized parameters including MDA, insulin, lipid profile, ALT, liver glycogen, creatinine, and CRP levels. This shift effectively reversed the MS-induced alterations, except for glycemia and uremia, likely influenced by the diet's high protein content stimulating gluconeogenesis. This research underscores the potential benefits of long-term carbohydrate restriction in mitigating MS-related markers.

Regulation of NLRP3 Inflammasome Activation and Inflammatory Exosome Release in Podocytes by Acid Sphingomyelinase During Obesity

The activation of nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome has been reported to importantly contribute to glomerular inflammation and injury under different pathological conditions such as obesity. However, the mechanism mediating NLRP3 inflammasome activation in podocytes and subsequent glomerular injury remains poorly understood. Given that the ceramide signaling pathway has been reported to be implicated in obesity-related glomerulopathy (ORG), the present study was designed to test whether the ceramide-producing enzyme, acid sphingomyelinase (ASM), determines NLRP3 inflammasome activation and inflammatory exosome release in podocytes leading to glomerular inflammation and injury during ORG. In Smpd1trg/Podocre mice, podocyte-specific overexpression of Smpd1 gene which encodes ASM significantly exaggerated high-fat diet (HFD)-induced NLRP3 inflammasome activation in podocytes and immune cell infiltration in glomeruli compared to WT/WT mice. Smpd1 gene deletion, however, blocked these pathological changes induced by HFD in Smpd1-/- mice. Accompanied with NLRP3 inflammasome activation and glomerular inflammation, urinary excretion of exosomes containing podocyte marker and NLRP3 inflammasome products (IL-1β and IL-18) in Smpd1trg/Podocre mice on the HFD was much higher than that in WT/WT mice. In contrast, Smpd1-/- mice on the HDF had significantly lower urinary exosome excretion than WT/WT mice. Correspondingly, HFD-induced podocyte injury, glomerular sclerosis, and proteinuria were more severe in Smpd1trg/Podocre mice, but milder in Smpd1-/- mice compared to WT/WT mice. Using podocytes isolated from these mice, we demonstrated that visfatin, a prototype pro-inflammatory adipokine, induced NLRP3 inflammasome activation and enrichment of multivesicular bodies (MVBs) containing IL-1β in podocytes, which was much stronger in podocytes from Smpd1trg/Podocre mice, but weaker in those from Smpd1-/- mice than WT/WT podocytes. By quantitative analysis of exosomes, it was found that upon visfatin stimulation, podocytes from Smpd1trg/Podocre mice released much more exosomes containing NLRP3 inflammasome products, but podocytes from Smpd1-/- mice released much less exosomes compared to WT/WT podocytes. Super-resolution microscopy demonstrated that visfatin inhibited lysosome-MVB interaction in podocytes, indicating impaired MVB degradation by lysosome. The inhibition of lysosome-MVB interaction by visfatin was amplified by Smpd1 gene overexpression but attenuated by Smpd1 gene deletion. Taken together, our results suggest that ASM in podocytes is a crucial regulator of NLRP3 inflammasome activation and inflammatory exosome release that instigate glomerular inflammation and injury during obesity.

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.

Crataeva nurvala Bark (Capparidaceae) Extract Modulates Oxidative Stress-Related Gene Expression, Restores Antioxidant Enzymes, and Prevents Oxidative Stress in the Kidney and Heart of 2K1C Rats

Objective

Crataeva nurvala is a medicinal plant, which contains a wide range of polyphenolic and bioactive compounds. The aim of the study was to evaluate the renal-protective activity of Crataeva nurvala in two-kidney, one-clip (2K1C) rats.

Methods

In this study, the ethanol extract of Crataeva nurvala bark at a dose of 100 mg/kg was orally used to treat 2K1C rats for four weeks. At the end of the experiment, all rats were sacrificed and tissue samples were collected for further biochemical and histological assessments.

Results

This investigation showed that Crataeva nurvala treatment prevented the kidney dysfunction in 2K1C rats. Uric acid and creatinine concentration and CK-MB activities increased in 2K1C rats which were normalized by Crataeva nurvala. 2K1C rats also showed increased oxidative stress, depicted by the elevated level of MDA, NO, and APOP in plasma and tissues. Oxidative stress parameters declined in 2K1C rats by the treatment of Crataeva nurvala. These results could be attributed to the restoration of antioxidant enzyme activities such as catalase and SOD. Crataeva nurvala extracts also upregulated antioxidant gene expression in the kidneys of 2K1C rats. Moreover, several anti-inflammatory genes were suppressed by Crataeva nurvala treatment in 2K1C rats. Furthermore, fibrosis and collagen deposition in the kidneys were also lowered by the treatment of the Crataeva nurvala extract.

Conclusion

The experimental data suggest that the Crataeva nurvala extract protected renal damage and oxidative stress, probably by restoring antioxidant enzymes activities in 2K1C rats.

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.

Serum leptin levels in patients with chronic kidney disease and hypertensive heart disease: An observational cross-sectional study

Background and Aim

Adipocytes secrete a peptide hormone called leptin, which plays a crucial role in controlling appetite and energy expenditure. Alterations in leptin concentrations are associated with CKD-related cardiovascular problems such as hypertensive heart disease (HHD). Despite the link, data on the precise function of leptin in people with CKD and HHD is scant.

Methods

An observational cross-sectional study involving a total of 108 participants (72 CKD patients with HHD and 36 healthy controls). Their demographic and anthropometric information was collected using a standardized questionnaire. Certain clinical measures such as blood pressure and body mass index (BMI) were assessed. Fasting blood samples were analyzed for levels of plasma glucose (FPG), lipids, creatinine, and leptin. Data were analyzed with SPSS v23.

Results

Leptin, FPG, creatinine and triglyceride levels were all significantly higher in CKD patients with HHD compared to controls (p < 0.01 for all). Furthermore, advanced CKD status (being in stage 5), having a 6-year diagnosis of HHD, being female, having a higher BMI, and elevation in levels of HDL and FPG contributed significantly to the variance in serum leptin levels in the case group (β = 0.37, 0.22, 0.19, 0.18, 0.27, 0.28; p < 0.05 for all). In the control group, the female gender had the biggest unique effect on circulating leptin levels, followed by BMI and eGFR (β = 0.71, 0.34, -0.22; p < 0.01 for all).

Conclusion

Patients with CKD who also had HHD reported considerably higher circulating leptin levels. Significantly higher blood leptin levels were shown to be associated with CKD stage 5 in the case group. These results are consistent with the role of leptin in the metabolic complexity seen in CKD patients. There needs to be more research into treatments that aim to lower leptin levels in CKD patients with HHD.

Chrysin improves diabetic nephropathy by regulating the AMPK-mediated lipid metabolism in HFD/STZ-induced DN mice

Diabetic nephropathy (DN) is a highly prevalent and severe diabetic complication. It is urgent to explore high efficiency and minor side effects therapy for DN. Chrysin is a natural flavonoid with various biological activities found in honey and propolis, and has considerable potential to improve DN. The study was designed to explore the effects and the specific underlying mechanism of chrysin for DN in high-fat-diet (HFD) and streptozotocin (STZ) induced DN mice. Firstly, the study revealed that chrysin effectively improved obesity, insulin resistance (IR), renal function, and pathological injury in DN mice. Secondly, the study found that chrysin improved the key indices and markers of lipid accumulation, oxidative stress, and inflammation which are closely related to the development or progression of DN. Moreover, chrysin markedly modulated lipid metabolism by regulating Adenosine 5' monophosphate-activated protein kinase (AMPK) and essential downstream proteins. Furthermore, AMPK inhibitor (Dorsomorphin) intervention partially suppressed the positive effects of chrysin on all testing indicators, indicating that activated AMPK is crucial for chrysin action on DN. The present study demonstrated that chrysin may improve DN by regulating lipid metabolism, and activated AMPK plays a critical role in the regulation of chrysin. PRACTICAL APPLICATIONS: The study verified the positive effects of chrysin on obesity, insulin resistance, kidney injury, renal function, lipid accumulation, inflammation, and oxidative stress, which are closely related to the development or progression of diabetic nephropathy (DN). Moreover, we explored that chrysin improves DN by regulating AMPK-mediated lipid metabolism. Furthermore, the AMPK inhibitor was used to confirm that activated AMPK plays a critical role in the effects of chrysin. These results could offer a full explanation and a potential option for adjuvant therapy of DN diabetes with chrysin.

Dietary calcium regulates the risk renal injury in high fat diet induced obese rats by regulating renal lipid metabolism, oxidative stress and inflammation

CONTEXT

The antiobesity effect of dietary calcium by preventing fat accumulation and weight gain was well established from several epidemiological and animal studies.

OBJECTIVE

To evaluate the effect of dietary calcium against obesity-associated with renal injury in high fat diet induced obese rats. Materials and Methods: Obesity was induced by high fat diet (HFD) and then given either low or high calcium HFD (0.25% and 1.0%) for another 30 days.

RESULTS

The results showed that 1.0% high calcium group was effective in reducing renal lipogenesis activity, lipid accumulation, fatty acid synthase (FAS) activity, acetyl coenzyme A carboxylase (ACC) expression, oxidative stress, inflammation and increased the adenosine monophosphate kinase (AMPK) expression.

DISCUSSION AND CONCLUSION

Downregulation of renal lipid accumulation by high calcium diet through AMPK mediated lipogenesis activity, oxidative stress and the inflammatory response seemed to prevent the renal injury in high fat diet (HFD) induced obese rats.

Obesity and Chronic Kidney Disease A Current Review

Background

Obesity poses significant challenges to healthcare globally, particularly through its bi-directional relationship with co-morbid metabolic conditions such as type 2 diabetes and hypertension. There is also emerging evidence of an association between obesity and chronic kidney disease (CKD) which is less well characterized.

Methods

A literature search of electronic libraries was conducted to identify and present a narrative review of the interplay between obesity and CKD.

Findings

Obesity may predispose to CKD directly as it is linked to the histopathological finding of obesity-related glomerulopathy and indirectly through its widely recognized complications such as atherosclerosis, hypertension, and type 2 diabetes. The biochemical and endocrine products of adipose tissue contribute to pathophysiological processes such as inflammation, oxidative stress, endothelial dysfunction, and proteinuria. The prevention and management of obesity may prove critical in counteracting both the development and advancement of CKD. Moreover, measures of abdominal adiposity such as waist circumference, are generally associated with worse morbidity and mortality in individuals receiving maintenance hemodialysis.

Conclusion

Obesity is a risk factor for the onset and progression of CKD and should be recognized as a potential target for a preventative public health approach to reduce CKD rates within the general population. Future research should focus on the use of glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter 2 inhibitors in patients with CKD and obesity due to their multi-faceted actions on major outcomes.

Obesity-related glomerulopathy: Current approaches and future perspectives

Obesity-related glomerulopathy (ORG) is a silent comorbidity which is increasing in incidence as the obesity epidemic escalates. ORG is associated with serious health consequences including chronic kidney disease, end-stage renal disease (ESRD), and increased mortality. Although the pathogenic mechanisms involved in the development of ORG are not fully understood, glomerular hemodynamic changes, renin-angiotensin-aldosterone system (RAAS) overactivation, insulin-resistance, inflammation and ectopic lipid accumulation seem to play a major role. Despite albuminuria being commonly used for the non-invasive evaluation of ORG, promising biomarkers of early kidney injury that are emerging, as well as new approaches with proteomics and metabolomics, might permit an earlier diagnosis of this disease. In addition, the assessment of ectopic kidney fat by renal imaging could be a useful tool to detect and evaluate the progression of ORG. Weight loss interventions appear to be effective in ORG, although large-scale trials are needed. RAAS blockade has a renoprotective effect in patients with ORG, but even so, a significant proportion of patients with ORG will eventually progress to ESRD despite therapeutic efforts. It is noteworthy that certain antidiabetic agents such as sodium-glucose cotransporter 2 inhibitors (SGLT2i) or glucagon-like peptide-1 receptor agonists (GLP-1 RAs) could be useful in the treatment of ORG through different pleiotropic effects. In this article, we review current approaches and future perspectives in the care and treatment of ORG.

Kidney injury and oxidative damage alleviation by Zingiber officinale: pharmacokinetics and protective approach in a combined murine model of osteoporosis

Ginger (Zingiber officinale) is considered as a nutraceutical spice, which possesses several health promotion and benefits. This study was carried out to investigate the phyto-chemical composition, the antioxidant capacities, the drug-likeness, and pharmacokinetic properties of ginger extract on kidney injury-associated osteoporosis in rats. Phenolic and flavonoid contents were assessed by standard chemical analysis methods and HPLC. In vivo protective effect was based on the use of female rats to evaluate the effect on renal injury as a result of combined osteoporosis using biochemical markers, oxidative status, and histological analyses. Results showed that ZO contained appreciable amounts of phenolics and flavonoids and it exhibited high scavenging activity. Ovariectomy-associated corticotherapy induced severe renal injury marked by altered biochemical markers (creatinine, urea, and uric acid), reduced GFR, significative oxidative damage signs, and disrupted antioxidant status in the combined osteoporotic rats. The histopathological examination revealed structural modifications of kidney tissues. However, all these changes were reversed following the use of ZO. These results confirm the renoprotective and antioxidant potential of ginger against renal injuries in osteoporotic rats.

Anti-Obesity Action of Boerhavia diffusa in Rats against High-Fat Diet-Induced Obesity by Blocking the Cannabinoid Receptors

Obesity, type 2 diabetes, and cardiovascular illnesses have known risk factors in the pathophysiology of an unhealthy diet. Obesity now affects almost a third of the world’s population and is widely seen as a side effect of the Industrial Revolution. The current study aimed to determine natural phytoconstituents that have a significant role in the management of obesity. In this view, we have selected the plant Boerhavia diffusa which has different pharmacological actions and is traditionally used to treat sickness caused by lifestyle modification. The methanolic extract of the plant material was prepared and then further fractionated by means of solvents (n-hexane, chloroform, n-butanol, and water). The absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis was done by taking the active constituent of the plant (Punarnavine, Boeravinone B, and Eupalitin). The molecular docking analysis of these compounds is also performed by targeting the cannabinoid receptor (CR). Structural analysis of the best complex was done using the Discovery Studio visualizer tool. High-performance thin-layer chromatography (HPTLC) analysis was done by using a solvent system (chloroform and methanol in a ratio of 8:2). The in vivo study was done on the Sprague–Dawley (SD) rats treated with a high-fat diet to induce obesity and different parameters such as body weight, behavioral activity, organ fat pad weight, lipid profile, and liver biomarkers (AST, ALT, BUN, and creatinine) were estimated. The result of the study suggested that the phytoconstituents of B. diffusa upon molecular docking revealed the possible binding mechanisms with the CR and thus show potent anti-obesity action.

Period circadian clock 3 inhibits palmitic acid-induced oxidative stress and inflammatory factor secretion in podocytes

OBJECTIVES

High fat-induced podocyte injury is one of the important factors leading to obesity related nephropathy (ORG), but the mechanism is not clear. This study aims to explore the mechanism of period circadian clock 3 (PER3) in the oxidative stress and inflammation induced by palmitic acid (PA) in podocytes.

METHODS

The C57BL/6J mice were fed with chow and high-fat diet for 16 weeks. The PER3 expression in kidney tissues were detected in the normal body weight group and the obesity group. The PER3 mRNA and protein expression were detected after the podocytes were induced with different concentrations (0, 50, 150 and 300 μmol/L) of PA for 48 h. The PER3 mRNA and protein expression were detected after the podocytes were induced with 150 μmol/L PA for 0, 24, 36, and 48 h. Triglyceride (TG) levels were examined in the PA group, the adenovirus (ad)-PER3+PA group, and the siRNA-PER+PA group after the podocytes were transfected by Ad-PER3 or small interfering RNA (siRNA)-PER3 for 48 h and subsequently were induced with 150 μmol/L PA for 48 h. The differential gene expression was detected using RNA sequencing (RNA-seq) after podocytes were transfected by siRNA-PER3 (siRNA-PER3 group) and siRNA-control (siRNA-control group), respectively. The mRNA levels of nephrin, podocin, podocalyxin, podoplanin, superoxide dismutase 1 (SOD1), glutathione peroxidase 1 (GPX1), catalase (CAT), and the levels of malondialdehyde (MDA), glutathione (GSH), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β) and interleukin-2 (IL-2) were detected after podocytes were transfected with Ad-PER3 or Ad-control for 48 h and then they were induced by 150 μmol/L PA for 48 h.

RESULTS

The PER3 was down-regulated in the obesity group compared with the normal body weight group (P<0.05), and the PER3 was significantly down-regulated after the podocytes were treated with 150 μmol/L for 48 h compared with 0, 24, and 36 h (all P<0.01). The TG contents were significantly decreased in the Ad-PER3+PA group compared with the PA group (P<0.05). On the contrary, TG contents were increased in the siRNA-PER3+PA group compared with the PA group (P<0.05). The RNA-seq results showed that: compared with the siRNA-control group, the differential genes in the siRNA-PER3 group were enriched in different pathways including oxidative phosphorylation, TNF signaling pathway, extracellular matrix receptor interaction, fatty acid metabolism, and fatty acid degradation (all P<0.05). The podocyte marker genes (nephrin, podocin, podocalyxin and podoplanin), oxidative stress (SOD1, GPX1, CAT and GSH), and inflammation factors (TNF-α, IL-6, IL-1β and IL-2) were significantly down-regulated in the Ad-PER3+PA group compared with the PA group (all P<0.05).

CONCLUSIONS

PER3 can decrease the PA-induced oxidative stress and inflammatory factor secretion via inhibiting the lipogenesis in podocytes.

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.

Bariatric Surgery Improves Renal Function in Patients With Obesity

Background

Obesity affects 93.3 million adults in the United States and is a predisposing factor for the development and progression of chronic kidney disease (CKD). The objective of this study is to examine the association between weight loss and renal function in participants undergoing bariatric surgery following a 12-week multidisciplinary, community-based weight loss program.

Methodology

This is a retrospective chart review of participants who voluntarily enrolled in a 12-week multidisciplinary weight loss program prior to bariatric surgery from 2009 to 2018. The primary outcome was to assess the association between weight loss and renal function in participants undergoing bariatric surgery. Secondary outcomes included changes in hemoglobin A1c, lipids, fasting glucose, and blood pressure.

Results

Among the 55 participants, baseline glomerular filtration rate (GFR) was 49 mL/min/m², 80% were female, and the average baseline weight was 131 kg. At one-year post-intervention, 69% of patients improved in the CKD stage, with 45% of the participants improving from stage 3A to stage 2. GFR improved to 15 mL/min/1.73m² (p = 0.025), and there was a negative correlation (r_s = -0.3556) between weight and GFR (p = 0.013). Participants with hyperlipidemia had a 12 mL/min/1.73m² rise in GFR, while participants without the diagnosis at one year had a 24 mL/min/1.73m² rise in GFR (p = 0.007).

Conclusions

This study demonstrated improved renal function and reduced progression of CKD following a combined lifestyle and surgical intervention, indicating the importance of a comprehensive approach for the management of the chronic disease.

Associations between obesity, weight change and decreased renal function in Korean type 2 diabetic patients: a longitudinal follow-up study

BACKGROUND

We aimed to examine the associations between the risk of decreased renal function, obesity, and weight changes in Korean type 2 diabetic patients with normal renal function.

METHODS

Type 2 diabetic patients (n = 1060) who visited the diabetic clinic at Soonchunhyang University Bucheon Hospital between 2001 and 2007 with follow up surveys completed in 2016 to 2017 were recruited into the study. Decreased renal function was defined as an estimated glomerular filtration rate < 60 mL/min/1.73 m². Weight change was calculated between baseline and each follow-up survey. Multivariate analysis was used to evaluate the longitudinal association of baseline obesity and weight changes with the risk of decreased renal function.

RESULTS

This study revealed that baseline obesity was associated with the risk of decreased renal function after adjusting for clinical variables in type 2 diabetic patients (odds ratio [OR] 1.40; 95% confidence intervals [CI] 1.08-2.04; p = 0.025). Follow-up (mean = 12 years) revealed that weight gain > 10% was associated with the risk of decreased renal function after adjusting for clinical variables in type 2 diabetic patients with normal renal function at baseline (OR 1.43; CI 1.11-2.00; p = 0.016). Weight loss was not associated with the risk of decreased renal function in type 2 diabetic patients with normal renal function at baseline.

CONCLUSIONS

Baseline obesity was associated with the increased risk of decreased renal function in Korean type 2 diabetic patients with normal renal function. Weight gain > 10% independently predicted the risk of decreased renal function. Large prospective studies are needed to clarify causal associations between obesity, weight change, and decreased renal function in patients with type 2 diabetes.

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.

The Protective Effects of Butorphanol on Pulmonary Function of Patients with Obesity Undergoing Laparoscopic Bariatric Surgery: a Double-Blind Randomized Controlled Trial

BACKGROUND

Obesity is a risk factor for postoperative pulmonary complications (PPCs). Recent studies have reported the pulmonary protective role of the kappa opioid receptor (KOR). Butorphanol is a narcotic with strong KOR agonist action, and the role in pulmonary protection is uncertain. Here, we hypothesized that butorphanol exerts protective effects on pulmonary function in patients with obesity undergoing laparoscopic bariatric surgery.

METHODS

Patients with a body mass index ≥ 30 kg/m² scheduled for laparoscopic bariatric surgery were randomized to receive butorphanol or normal saline. Butorphanol was administered as an initial loading dose of 10 μg/kg at 5 min before induction followed by 5 μg/(kg h) during surgery. The primary outcome was arterial-alveolar oxygen tension ratio (a/A ratio). Secondary outcomes included other pulmonary variables, biomarkers reflecting pulmonary injury, and incidence of PPCs within 7 days after surgery.

RESULTS

Patients in the butorphanol group had a significantly higher a/A ratio at 1 h after the operation began (68 ± 7 vs. 55 ± 8, P < 0.001), end of the operation (73 ± 8 vs. 59 ± 7, P < 0.001), and 1 h after extubation (83 ± 9 vs. 70 ± 5, P < 0.001) compared with those in the control group. In addition, in the butorphanol group, dead space to tidal volume ratios were significantly lower than those in the control group at the same time points (all P < 0.001). In the control group, the levels of biomarkers reflecting pulmonary injury were significantly higher than those in the butorphanol group at 3 h, 6 h, 12 h, and 24 h postoperatively (P < 0.001). The incidence of PPCs was similar in both groups.

CONCLUSION

Butorphanol administration protected pulmonary function by improving oxygenation and reducing dead space ventilation in patients with obesity undergoing laparoscopic bariatric surgery. Butorphanol may therefore provide clinical benefits in patients with obesity.

Effect of spexin on renal dysfunction in experimentally obese rats: potential mitigating mechanisms via galanin receptor-2

This study declared effect of spexin (SPX) on renal dysfunction in obese rats and its potential mitigating mechanisms which could mediated via galanin receptor-2 (GALR-2). Thirty two 32 Wistar male rats were arranged into four groups: control, high fat/fructose diet (HFFD), HFFD + SPX and HFFD + M871 (galanin receptor 2 antagonist)+SPX. At the termination of the experiment, urine volume, body mass index, Lee index and mean arterial blood pressure were assessed. Renal function was evaluated. Lipid profile, fasting glucose, insulin, insulin resistance and SPX levels were estimated. Also, renal histopathological, immunohistochemical and relative gene expression of renal tissue were done. Also, renal protein carbonyl, reduced glutathione, interferon gamma, monocyte chemoattractant protein-1, interleukin-10 and hydroxyproline were determined.Our results explored that SPX treatment prominently mitigated the metabolic changes and renal dysfunction induced by HFFD via GALR-2. SPX improved insulin resistance, dyslipidemia, renal oxidative stress, inflammation, apoptosis, and fibrosis. So, SPX can be considered as prospective therapeutic agent for treating renal dysfunction.

Curcumin analogue C66 attenuates obesity-induced renal injury by inhibiting chronic inflammation

Obesity has been recognized as a major risk factor for the development of chronic kidney disease, which is accompanied by increased renal inflammation, fibrosis, and apoptosis. C66 is a curcumin derivative that exerts anti-inflammatory effects by inhibiting the JNK pathway and prevents diabetic nephropathy. The present study investigates the possible protective effect of C66 on high-fat diet (HFD)-induced obesity-related glomerulopathy. Mice were fed with HFD for 8 weeks while some were treated with C66 every 2 days for 11 weeks. The HFD-fed mice developed renal dysfunction, as well as elevated triglyceride and cholesterol. Kidneys of the HFD-fed mice showed marked glomerular injuries, apoptosis, and inflammation with markedly increased cytokine production. Interestingly, treating HFD-fed mice with C66 remarkably reversed these pathological changes via inhibiting inflammation and NF-κB/JNK activation. In cultured mesangial cells, Palmitic Acid was able to activate the pro-fibrotic mechanisms, apoptosis, inflammatory response, and NF-κB and JNK signaling pathways, all of which could be attenuated by C66 treatment. In all, we demonstrated that curcumin analogue C66 attenuates obesity-induced renal injury by inhibiting chronic inflammation and apoptosis via targeting NF-κB and JNK. Our data suggest that C66 can be potentially used to prevent obesity-associated renal diseases warranting future investigations.

Obesity-like metabolic effects of high-carbohydrate or high-fat diets consumption in metabolic and renal functions

Present study investigated which diet, high-carbohydrate (HCD) or high-fat (HFD), most effectively induces classical characteristics of obesity in mice. Mice were fed commercial chow (control), an HCD, or an HFD for 12 weeks. HFD and HCD increased body weight, fat mass, and glycaemia, whereas the HFD augmented insulinemia. In the kidney, the HFD caused albuminuria, and reductions in fractional Na⁺ excretion, Thromboxane B2 (TXB2) excretion, and urinary flow, whereas the HCD reduced glomerular filtration, plasma osmolality, and TXB2 and Prostaglandin E2 excretion. The consumption of HFD and HCD modified parameters that indicate histopathological changes, such as proliferation (proliferating-cell-nuclear antigen), inflammation (c-Jun N-terminal-protein), and epithelial-mesenchymal transition (vimentin, and desmin) in renal tissue, but the HCD group presents fewer signals of glomerular hypertrophy or tubule degeneration. In summary, the HCD generated the metabolic and renal changes required for an obesity model, but with a delay in the development of these modifications concerning the HFD.

End-of-Procedure Volume Responsiveness Defined by the Passive Leg Raise Test Is Not Associated With Acute Kidney Injury After Cardiopulmonary Bypass

OBJECTIVES

Renal hypoperfusion is a common mechanism of cardiac surgery-related acute kidney injury (CS-AKI). However, the optimal amount of volume resuscitation to correct systemic hypoperfusion and prevent the postoperative development of CS-AKI has been a subject of debate. The goal of this study was to assess the association of volume responsiveness determined by stroke volume variation using the passive leg raise test (PLRT) at chest closure, with the development of CS-AKI according to the Kidney Disease Improving Global Outcomes criteria.

DESIGN

Single-center, prospective observational study.

SETTING

Tertiary hospital.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 131 patients were studied from January 2015 until May 2017. All patients underwent cardiac surgery that required cardiopulmonary bypass. Volume responsiveness was assessed at chest closure using the PRLT. Stroke volume variation from the sitting to the recumbent positions was measured by transesophageal echocardiography. Fluid responsiveness was defined as an increase of >12% of stroke volume from sitting to recumbent positions. A total of 82 (68.3%) patients were fluid-responsive versus 38 (31.6%) who were fluid-unresponsive. CS-AKI occurred in 30% of patients. There was no difference in CS-AKI between fluid-responsive and fluid-nonresponsive groups. However, CS-AKI was associated independently with an increases in body mass index and preoperative diastolic blood pressure. CS-AKI also was associated with prolonged intensive care unit length of stay.

CONCLUSION

End-of-procedure volume responsiveness is not associated with a high risk for postoperative CS-AKI.

Pharmaceutical and Nutraceutical Potential Applications of Sargassum fulvellum

Sargassum fulvellum is a brown seaweed of the Sargassaceae family which has been demonstrated to exhibit antipyretic, analgesic, antiedema, antimicrobial, antioxidant, antitumor, neuroprotective, anticoagulative, anti-inflammatory, and hepatoprotective activities. It has been widely used as a food additive and as a medicine in oriental medicine to treat lumps, dropsy, swelling, testicular pains, and urinary problems. S. fulvellum has been identified as a potential producer of a wide spectrum of natural compounds such as carotenoids, fucoidans, and phlorotannins, showing different biological activities in various industrial applications including pharmaceutical, nutraceutical, cosmeceutical, and functional food. However, the promising health effects associated with the extracts and compounds isolated from S. fulvellum have not been reviewed to date. The present review thus focuses on the biological activity of S. fulvellum as reported by previous publications, which include antioxidant, anticoagulant, anti-inflammatory, neuroprotective, immunomodulatory, antidiabetic, and anticancer effects. Thus, this review might serve to increase the utilization of this invaluable natural source as a potential component in pharmaceutical and nutraceutical applications.

Exenatide once weekly decreases urinary albumin excretion in patients with type 2 diabetes and elevated albuminuria: Pooled analysis of randomized active controlled clinical trials

AIMS

To examine the albuminuria-lowering effect of exenatide once weekly (EQW) compared with active glucose-lowering comparators in patients with type 2 diabetes and elevated urinary albumin-to-creatinine ratio (uACR).

METHODS

Six randomized double-blind and open-label phase III studies were pooled in a post hoc, exploratory analysis to evaluate the efficacy and safety of EQW versus non-glucagon-like peptide-1 receptor agonist comparators in patients with type 2 diabetes and baseline uACR ≥30 mg/g. Treatment groups were EQW versus all comparators pooled. Efficacy outcomes were percent change from baseline to week 26/28 in uACR and absolute change in glycated haemoglobin (HbA1c), systolic blood pressure (SBP), body weight and estimated glomerular filtration rate (eGFR).

RESULTS

Baseline characteristics were generally similar between the two treatment groups (EQW: N = 194, all comparators: N = 274). Relative to the comparator group, EQW changed albuminuria by -26.2% (95% confidence interval [CI] -39.5 to -10). Similar improvements were observed with EQW versus oral glucose-lowering drugs (-29.6% [95% CI -47.6 to -5.3) or insulin (-23.8% [95% CI -41.8 to -0.2]). The effect of EQW on uACR was independent of baseline renin-angiotensin system inhibitor usage. Adjusted mean decreases in HbA1c, SBP and body weight were more pronounced in the EQW versus the comparator group. Adjustment for changes in HbA1c, eGFR and SBP did not substantially affect the uACR-lowering effect of EQW. When also adjusting for changes in body weight, the uACR-lowering effect was reduced to (-13.0% [95% CI -29.9 to 7.8]).

CONCLUSION

Exenatide once weekly reduced uACR in patients with type 2 diabetes and elevated albuminuria compared to commonly used glucose-lowering drugs.

Renal and Cardiovascular Outcomes After Weight Loss From Gastric Bypass Surgery in Type 2 Diabetes: Cardiorenal Risk Reductions Exceed Atherosclerotic Benefits

OBJECTIVE

We examined detailed renal and cardiovascular (CV) outcomes after gastric bypass (GBP) surgery in people with obesity and type 2 diabetes mellitus (T2DM), across several renal function categories, in a nationwide cohort study.

RESEARCH DESIGN AND METHODS

We linked data from the National Diabetes Register and the Scandinavian Obesity Surgery Register with four national databases holding information on socioeconomic variables, medications, hospitalizations, and causes of death and matched 5,321 individuals with T2DM who had undergone GBP with 5,321 who had not (age 18-65 years, mean BMI >40 kg/m², mean follow-up >4.5 years). The risks of postoperative outcomes were assessed with Cox regression models.

RESULTS

During the first years postsurgery, there were small reductions in creatinine and albuminuria and stable estimated glomerular filtration rate (eGFR) in the GBP group. The incidence rates of most outcomes relating to renal function, CV disease, and mortality were lower after GBP, being particularly marked for heart failure (hazard ratio [HR] 0.33 [95% CI 0.24, 0.46]) and CV mortality (HR 0.36 [(95% CI 0.22, 0.58]). The risk of a composite of severe renal disease or halved eGFR was 0.56 (95% CI 0.44, 0.71), whereas nonfatal CV risk was lowered less (HR 0.82 [95% CI 0.70, 0.97]) after GBP. Risks for key outcomes were generally lower after GBP in all eGFR strata, including in individuals with eGFR <30 mL/min/1.73 m².

CONCLUSIONS

Our data suggest robust benefits for renal outcomes, heart failure, and CV mortality after GBP in individuals with obesity and T2DM. These results suggest that marked weight loss yields important benefits, particularly on the cardiorenal axis (including slowing progression to end-stage renal disease), whatever the baseline renal function status.

Potential role of estradiol in ovariectomy-induced derangement of renal endocrine functions

Menopause is an important physiological event associated with structural and functional changes in the kidneys. An animal model of bilateral ovariectomy was used to study the effects of estrogen depletion, replacement and antiestrogen on renal structure and endocrine function. Sixty female rats were divided into six groups; group I was the control group, the remaining five groups underwent ovariectomy: group II received no treatment. The other groups received estradiol in group III, tamoxifen in group IV, estradiol followed by tamoxifen in group V and tamoxifen followed by estradiol in group VI. Serum creatinine, blood urea nitrogen, and endocrine functions of kidney were measured. Tissue samples were examined both microscopically for beta estrogen receptors and ultrastructurally for cell changes. Groups II, IV & VI showed a significant increase in creatinine, blood urea nitrogen, renal malondialdehyde, renal erythropoietin, plasma renin and plasma prostaglandin E2 and a significant decrease in renal antioxidants and serum vitamin D3. Groups III &V had a significant decrease in creatinine, blood urea nitrogen, renal malondialdehyde and renal erythropoietin with an increase in renal antioxidants, plasma prostaglandin E2 and serum vitamin D3. Histopathological and ultrastructural examinations revealed atrophic tubular changes in group II. The changes were less marked in groups III &V and more extensive in groups IV & VI. Estrogen receptor beta staining showed progressively increased expression in the absence of estrogen. Structural and most endocrine functions of the kidney were significantly affected by estradiol deficiency. Estradiol replacement exhibited a protective effect on renal tissue and endocrine functions.

Resveratrol alleviates obesity-associated podocyte injury in ovariectomized obese rats

Obesity-associated podocyte injury increases in parallel with inflammatory responses. Resveratrol, as an anti-inflammatory and antioxidative agent, has been proven to be effective in obesity. The purpose of the present study was to investigate the function of resveratrol in the early stages of podocyte injury in ovariectomized rats fed a high-fat diet (HFD). The 3-month-old female Wistar rats were randomly divided into four groups: Sham operation with a standard diet; sham operation with a HFD; ovariectomy with a HFD (O+H); and ovariectomy plus HFD treatment with resveratrol (40 mg/kg/day) (O+H+R). Following 12 weeks, the weights of the rats were measured and serum was obtained to measure the levels of 17β-estradiol (E2), serum lipids, serum creatinine, fasting blood glucose (FBG) and insulin. Periodic acid-schiff staining was used to detect renal pathological changes. Meanwhile, the expression of the podocyte-associated proteins nephrin and Wilms' tumor-1 was investigated using immunohistochemical staining, and the levels of tumor necrosis factor-α, interleukin-6 and monocyte chemotactic protein-1 in renal tissues were determined using western blotting. Compared with the O+H group, resveratrol significantly reduced the body weight, serum levels of total cholesterol, low-density lipoprotein cholesterol, FBG and insulin resistance, and increased the levels of E2 in obese rats with an ovariectomy combined with an HFD (P<0.05). Compared with the O+H group, although the O+H+R group had no significant changes in renal pathology, the changes in the levels of podocyte-associated proteins and inflammatory markers were significantly reversed (P<0.05). These results suggest that resveratrol may attenuate early podocyte injury by improving lipid metabolism and insulin sensitivity, and subsequently inhibiting inflammatory responses in obese rats induced by an ovariectomy with a HFD.

Purinergic 2X7 Receptor is Involved in the Podocyte Damage of Obesity-Related Glomerulopathy via Activating Nucleotide-Binding and Oligomerization Domain-Like Receptor Protein 3 Inflammasome

Background:

The nucleotide-binding and oligomerization domain-like receptor protein 3 (NLRP3) inflammasome composed of NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), and caspase-1 is engaged in the inflammatory response of many kidney diseases and can be activated by purinergic 2X7 receptor (P2X7R). This study was conducted to explore whether P2X7R plays a pathogenic role in the podocyte damage of obesity-related glomerulopathy (ORG) and whether this role is mediated by the activation of NLRP3 inflammasome.

Methods:

A mouse model of ORG was established by high-fat diet feeding. The conditionally immortalized mouse podocytes were cultured with leptin or with leptin and P2X7R antagonist (KN-62 or A438079). The mRNA and protein expression of the P2X7R and NLRP3 inflammasome components including NLRP3, ASC, and caspase-1, as well as the podocyte-associated molecules including nephrin, podocin, and desmin in mouse renal cortex or cultured mouse podocytes were tested by real-time-polymerase chain reaction and Western blot analysis, respectively.

Results:

The significantly upregulated expression of P2X7R and NLRP3 inflammasome components and the NLRP3 inflammasome activation were observed in the renal cortex (in fact their location in podocytes was proved by confocal microscopy) of ORG mice in vivo, which were accompanied with the morphological changes of podocyte damage and the expression changes of podocyte-associated molecules. Similar changes in the expression of P2X7R and NLRP3 inflammasome components as well as in the expression of podocyte-associated molecules were also observed in the cultured podocyte studies treated by leptin in vitro, and all of the above changes were significantly attenuated by the P2X7R antagonist KN-62 or A438079.

Conclusions:

P2X7R could trigger the activation of NLRP3 inflammasome, and the activated P2X7R/NLRP3 inflammasome in podocytes might be involved in the podocyte damage of ORG.

Coptidis Rhizoma inhibits NLRP3 inflammasome activation and alleviates renal damage in early obesity-related glomerulopathy

BACKGROUND

Obese subjects have been considered to be in a state of chronic, low-grade systemic inflammation. Excess fat accumulation and persistent inflammation may promote renal dysfunction, to cause chronic kidney disease (CKD) and even end-stage kidney failure. Coptidis Rhizoma is a classical traditional Chinese herb well known for its hypoglycemic and hypolipidemic properties. The mechanism is partially associated with its anti-inflammatory effect. However, this effect is rarely investigated in obesity and obesity-related glomerulopathy (ORG).

PURPOSE

The current study was designed to evaluate the effect of Coptidis Rhizoma on ORG. It also aimed to determine whether this renal protection effect of Coptidis Rhizoma was related to the inhibition of NLRP3 inflammasome in ORG.

METHODS

Coptidis Rhizoma concentrated granules were prepared and the main components were identified by 3D-High Performance Liquid Chromatography (3D-HPLC) assay. The animal model of early stage ORG was established in obesity-prone (OP) rats by high protein and high fat diet feeding for 12 weeks. The treatment with Coptidis Rhizoma at different dosages was administered by intragastric infusion simultaneously. Then body weight, kidney weight, plasma lipid profiles, 24 h urine protein/albumin content and kidney histology were measured. Inflammatory biomarkers were examined both in the rat plasma and renal cortex. The gene expressions of NLRP3 inflammasome complex and NF-κB in renal tissues were also measured.

RESULTS

Coptidis Rhizoma alleviated dyslipidemia and reduced the renal weight of the rats with ORG. Meanwhile, urinary albumin to creatinine ratio and creatinine clearance rate were significantly improved. Coptidis Rhizoma also attenuated glomerular hypertrophy, mesangial hyperplasia, and effacement of podocyte foot in renal tissues of ORG rats. In addition, Coptidis Rhizoma intervention decreased the levels of proinflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-18) both in plasma and renal tissue. The gene expression of NLRP3 inflammasome was down-regulated and NF-κB activity was also inhibited by Coptidis Rhizoma in renal tissues of ORG rats.

CONCLUSION

Coptidis Rhizoma can ameliorate early renal damage in ORG rats and the mechanisms appear to be related to the inhibition of NLRP3 inflammasome complex.

Renal Protective Effects of N-Acetyl-Seryl-Aspartyl-Lysyl-Proline (Ac-SDKP) in Obese Rats on a High-Salt Diet

BACKGROUND

Obesity is a public health problem, associated with salt sensitive hypertension, kidney inflammation, and fibrosis. N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a tetra peptide with anti-inflammatory and anti-fibrotic properties. However, its effect on preventing kidney damage in obesity is unknown. We hypothesized that Zucker obese (ZO) rats on a high-salt (HS) diet develop renal damage, inflammation, fibrosis, and this is prevented with Ac-SDKP treatment.

METHODS

Zucker lean (ZL) and ZO rats (8 weeks old) were treated with Ac-SDKP (1.6 mg/kg/day) while maintained on either a normal-salt (NS; 0.4%) or HS (4%) diet for 8 weeks. Systolic blood pressure (SBP), albuminuria, renal inflammation, and fibrosis were evaluated.

RESULTS

HS diet increased macrophage infiltration in the kidneys of both ZL and ZO rats but was significantly higher in ZO rats receiving the HS diet (ZL + NS, 13.9 ± 1.3 vs. ZL + HS, 19.14 ± 1.5 and ZO + NS, 25.5 ± 1.4 vs. ZO + HS, 87.8 ± 10.8 cells/mm2; P < 0.05). Ac-SDKP prevented macrophage infiltration in ZO rats (ZO + HS + Ac-SDKP, 32.18 ± 2.4 cells/mm2; P < 0.05). Similarly, glomerulosclerosis, cortical, and medullary interstitial fibrosis were increased in ZO rats fed the HS diet, and Ac-SDKP attenuated these alterations (P < 0.05). SBP was increased in ZO rats fed the HS diet (ZO + NS, 121.3 ± 8.9 vs. ZO + HS, 164 ± 6.9 mm Hg; P < 0.05), and it was significantly decreased with Ac-SDKP treatment (ZO + HS + Ac-SDKP, 144.05 ± 14.1 mm Hg; P = 0.004). Albuminuria was higher in ZO rats than in ZL rats; however, neither HS nor Ac-SDKP treatment affected it.

CONCLUSIONS

Ac-SDKP treatment in ZO rats fed a HS diet prevented renal damage by reducing inflammation, fibrosis, and SBP.

Adipokine Profiling in Adult Women With Central Obesity and Hypertension

Central obesity and hypertension are common risk factors for the metabolic syndrome, cardiovascular and renal diseases. Studies have shown that it is more difficult to control blood pressure and prevent end-organ damage in obese individuals with hypertension compared to their non-obese counterparts, especially among women. Obese females have a 6 times higher risk of developing hypertension than non-obese females while obese males are at a 1.5 times higher risk of developing hypertension, compared to their non-obese counterparts. Indeed, the inter-relationship between obesity and hypertension is unclear. Adipokines have been proposed to play a mediating role in the relationship between obesity and hypertension and are involved in the pathogenesis of metabolic diseases. Therefore, this study sought to determine the role of adipokines (adiponectin, plasminogen activator inhibitor-1, leptin, and tumor necrosis factor-α) in hypertensive Hong Kong Chinese women with central obesity. A total of 387 women aged 58 ± 11 years who were examined with a 2 × 2 factorial design for central obesity (waist circumference ≥ 80 cm) and hypertension (blood pressure ≥ 140/90 mmHg), were recruited from a pool of 1,492 Hong Kong Chinese adults who were previously screened for metabolic syndrome. Subjects with hyperglycemia, hypertriglyceridemia, and dyslipidemia were excluded to eliminate confounding effects. Our findings revealed that hypertensive women with central obesity had a lower anti-inflammatory status (adiponectin) and a higher pro-inflammatory status (TNF-α) than obese alone or hypertensive alone women. Also, women with central obesity had higher circulatory PAI-1 and leptin concentrations than their non-obese counterparts. We conclude that obesity may shift toward a more pro-inflammatory state and may become more severe in the presence of hypertension or vice versa.

Lipoxin A4 may attenuate the progression of obesity-related glomerulopathy by inhibiting NF-κB and ERK/p38 MAPK-dependent inflammation

OBJECTIVES

To investigate the effects of lipoxin A4 (LXA4) on inflammatory responses in obesity-related glomerulopathy (ORG) mouse model and its potential mechanisms.

METHODS

Male C57BL/6 mice were randomly divided into 4 groups: normal, model, LXA4, and LXA4/Boc-2 groups (n = 8). Mice in LXA4 group were intraperitoneally injected with LXA4 (40 ng/kg) once daily for 3 days following 12 weeks of high-fat diet (HFD) feeding. LXA4 receptor antagonist, Boc-2, was administered in LXA4/Boc-2 group prior to LXA4 treatment to block the effects of LXA4. Renal morphology and function impairment were determined. Inflammation was tested by measuring serum and mRNA levels of pro-inflammatory cytokines and chemokines. HFD-induced activation of nuclear factor-kappa B (NF-κB) and phosphorylation of mitogen-activated protein kinases (MAPKs) were investigated by immunohistochemistry and western blot.

RESULTS

HFD-feeding caused significant renal injury, pathological changes and inflammation in model group mice. LXA4 injection significantly alleviated HFD-induced effects on renal morphology and functions, as demonstrated by lower kidney index, glomerular diameter, 24 h urine protein, urinary albumin creatinine ratio and renal histomorphology. Moreover, HFD-induced accumulation of pro-inflammatory cytokines and chemokines were obviously attenuated by LXA4 administration, so did the HFD-induced activation of NF-κB and ERK/p38 MAPK pathways. However, these effects were markedly abrogated by BOC-2 pretreatment.

CONCLUSION

LXA4 significantly attenuated HFD-induced renal inflammation and injury in ORG models, and these effects may be associated with the inhibition of activation of NF-κB and ERK/p38 MAPK pathways. The findings of our study may shed light on LXA4 showed a potential therapeutic application in ORG.

EGFR mediates hyperlipidemia-induced renal injury via regulating inflammation and oxidative stress: the detrimental role and mechanism of EGFR activation

Previous studies have implicated inflammation, oxidative stress, and fibrosis as key factors in the development of obesity-induced kidney diseases. Epidermal growth factor receptor (EGFR) plays an important role in cancer development. Recently, the EGFR pathway has been increasingly implicated in chronic cardiovascular diseases via regulating inflammation and oxidative stress. However, it is unclear if EGFR is involved in obesity-related kidney injury. Using ApoE-/- and C57BL/6 mice models and two specific EGFR inhibitors, we investigated the potential effects of EGFR inhibition in the treatment of obesity-related nephropathy and found that EGFR inhibition alleviates renal inflammation, oxidative stress and fibrosis. In NRK-52E cells, we also elucidated the mechanism behind hyperlipidemia-induced EGFR activation. We observed that c-Src and EGFR forms a complex, and following PA stimulation, it is the successive phosphorylation, not formation, of the c-Src/EGFR complex that results in the subsequent cascade activation. Second, we found that TLR4 regulates the activation EGFR pathway mainly through the phosphorylation of the c-Src/EGFR complex. These results demonstrate the detrimental role of EGFR in the pathogenesis of obesity-related nephropathy, provide a new understanding of the mechanism behind hyperlipidemia/FFA-induced EGFR activation, and support the use of EGFR inhibitors in the treatment of obesity-induced kidney diseases.

Ameliorative Effect of Ecklonia cava Polyphenol Extract on Renal Inflammation Associated with Aberrant Energy Metabolism and Oxidative Stress in High Fat Diet-Induced Obese Mice

Immoderate fat accumulation causes both oxidative stress and inflammation, which can induce kidney damage in obesity. Previously, Ecklonia cava has shown anti-inflammatory and antioxidative effects. Our group aimed to investigate whether E. cava polyphenol extract (ECPE) improves renal damage in high fat diet (HFD)-induced obese mice through regulation of not only energy metabolism but also oxidative stress and inflammation. After obesity induction by HFD, the mice were treated with different dosages of ECPE (100 or 500 mg/kg/day) by gavage for 12 weeks. ECPE treatment lowered the protein levels related to lipid accumulation (SREBP1c, ACC & FAS), inflammation (NLRP3 inflammasome, NFκB, MCP-1, TNF-α & CRP), and oxidative stress (Nrf2, HO-1, MnSOD, NQO1, GPx, 4-HNE and protein carbonyls) in HFD induced obese mice. Moreover, ECPE supplementation significantly up-regulated renal SIRT1, PGC-1α, and AMPK, which are associated with renal energy metabolism. Consequently, the results provide novel insights into the anti-inflammatory roles of ECPE in obesity-induced renal inflammation.

Role of the Renal Microcirculation in Progression of Chronic Kidney Injury in Obesity

BACKGROUND

Obesity is largely responsible for the growing incidence and prevalence of diabetes, cardiovascular and renal diseases. Current strategies to prevent and treat obesity and its consequences have been insufficient to reverse the ongoing trends. Lifestyle modification or pharmacological therapies often produce modest weight loss which is not sustained and recurrence of obesity is frequently observed, leading to progression of target organ damage in many obese subjects. Therefore, research efforts have focused not only on the factors that regulate energy balance, but also on understanding mechanisms of target organ injury in obesity. Summary and Key Message: Microvascular (MV) disease plays a pivotal role in progressive kidney injury from different etiologies such as hypertension, diabetes, and atherosclerosis, which are all important consequences of chronic obesity. The MV networks are anatomical units that are closely adapted to specific functions of nutrition and removal of waste in every organ. Damage of the small vessels in several tissues and organs has been reported in obesity and may increase cardio-renal risk. However, the mechanisms by which obesity and its attendant cardiovascular and metabolic consequences interact to cause renal MV injury and chronic kidney disease are still unclear, although substantial progress has been made in recent years. This review addresses potential mechanisms and consequences of obesity-induced renal MV injury as well as current treatments that may provide protection of the renal microcirculation and slow progressive kidney injury in obesity.

Metabolic and Hormonal Determinants of Glomerular Filtration Rate and Renal Hemodynamics in Severely Obese Individuals

OBJECTIVE

Renal function is often compromised in severe obesity. A true measurement of glomerular filtration rate (GFR) is unusual, and how estimation formulae (EstForm) perform in such individuals is unclear. We characterized renal function and hemodynamics in severely obese individuals, assessing the reliability of EstForm.

METHODS

We measured GFR (mGFR) by iohexol plasma clearance, renal plasma flow (RPF) by 123I-ortho-iodo-hippurate, basal and stimulated vascular renal indices, endothelium-dependent and -independent vasodilation using flow-mediated dilation (FMD) as well as metabolic and hormonal profile in morbid, otherwise healthy, obese subjects.

RESULTS

Compared with mGFR, the better performing EstForm was CKD-EPI (5.3 ml/min/1.73 m2 bias by Bland-Altman analysis). mGFR was directly related with RPF, total and incremental glucose AUC, and inversely with PTH and h8 cortisol. Patients with mGFR below the median shown significantly higher PTH and lower vitamin D3. Basal or dynamic renal resistive index, FMD, pulse wave velocity were not related with mGFR. In an adjusted regression model, renal diameter and plasma flow remained related with mGFR (R2 = 0.67), accounting for 15% and 21% of mGFR variance, respectively.

CONCLUSIONS

CKD-EPI formula should be preferred in morbid obesity; glucose increments during oral glucose tolerance test correlate with hyperfiltration; RPF and diameter are independent determinants of mGFR; slightly high PTH values, frequent in obesity, might influence mGFR.

Combination of melatonin and certain drugs for treatment of diabetic nephropathy in streptozotocin-induced diabetes in rats

Diabetic nephropathy is a major complication of diabetes and a leading cause of end-stage renal failure in many developed countries. The study aimed to evaluate the efficiency of certain drugs and melatonin in the treatment of nephropathy secondary to diabetes. Diabetes was induced in rats by a single intraperitoneal injection of streptozotocin (50 mg/kg body weight). Three days after induction of diabetes (460-500 mg/dl), rats were treated daily for 60 days with Rowatinex, melatonin, Rowatinex + melatonin, Amosar (Losartan Potassium) (LSP) and LSP + melatonin. The evaluations were made by measuring blood urea nitrogen (BUN), serum uric acid, serum creatinine, urine creatinine, creatinine clearance, nitric oxide, malondialdehyde, superoxide dismutase, glutathione, total antioxidant capacity, kidney injury molecule-1, heat shock protein-70, caspase-3, transforming growth factor β1, and DNA degradation by comet assay and total protein contents. The histopathological picture of the kidneys and pancreases was confirmed in our results. Diabetic rats showed drastic changes in all the measured parameters. Treatment with melatonin and the selected drugs revealed amelioration levels with variable degrees. In conclusion, the combination of LSP and melatonin had the most potent effect on treating the deleterious action of diabetes on rat kidney.

The kidney in obesity

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

The antioxidative effects of three lactobacilli on high-fat diet induced obese mice

In this paper, three Lactobacillus strains (L. coryniformis subsp. torquens T3, L. paracasei subsp. paracasei M5 and L. paracasei subsp. paracasei X12) isolated in our laboratory were investigated for antioxidant activity in vitro and in vivo.

Farnesoid X Receptor Protects against Kidney Injury in Uninephrectomized Obese Mice

Activation of the farnesoid X receptor (FXR) has indicated a therapeutic potential for this nuclear bile acid receptor in the prevention of diabetic nephropathy and obesity-induced renal damage. Here, we investigated the protective role of FXR against kidney damage induced by obesity in mice that had undergone uninephrectomy, a model resembling the clinical situation of kidney donation by obese individuals. Mice fed a high-fat diet developed the core features of metabolic syndrome, with subsequent renal lipid accumulation and renal injury, including glomerulosclerosis, interstitial fibrosis, and albuminuria. The effects were accentuated by uninephrectomy. In human renal biopsies, staining of 4-hydroxynonenal (4-HNE), glucose-regulated protein 78 (Grp78), and C/EBP-homologous protein, markers of endoplasmic reticulum stress, was more prominent in the proximal tubules of 15 obese patients compared with 16 non-obese patients. In mice treated with the FXR agonist obeticholic acid, renal injury, renal lipid accumulation, apoptosis, and changes in lipid peroxidation were attenuated. Moreover, disturbed mitochondrial function was ameliorated and the mitochondrial respiratory chain recovered following obeticholic acid treatment. Culturing renal proximal tubular cells with free fatty acid and FXR agonists showed that FXR activation protected cells from free fatty acid-induced oxidative stress and endoplasmic reticulum stress, as denoted by a reduction in the level of reactive oxygen species staining and Grp78 immunostaining, respectively. Several genes involved in glutathione metabolism were induced by FXR activation in the remnant kidney, which was consistent with a decreased glutathione disulfide/glutathione ratio. In summary, FXR activation maintains endogenous glutathione homeostasis and protects the kidney in uninephrectomized mice from obesity-induced injury.

Obesity increases the risk of renal involvement in children with Henoch-Schönlein purpura

The main aim of this study was to evaluate the relationship between obesity and renal involvement in children with Henoch-Schönlein purpura (HSP). A retrospective study of 141 pediatric patients with HSP was conducted in our hospital. The clinical data of all patients were collected from the electronic medical record management system from January 2010 to June 2014. The possible risk factors of renal involvement, especially obesity, were analyzed using univariate and multivariate analyses. Renal involvement occurred in 45/141 of the patients. A univariate analysis showed that an age more than 7 years at onset, persistent purpura, obesity, time from symptoms onset to diagnosis more than 14 days, and decreased C3 all increased the risk of renal involvement in HSP. The forward stepwise logistic regression analysis indicated obesity (odds ratio (OR) 4.43, 95 % confidence interval (CI) 1.896 to 10.358), age more than 7 years at onset (OR 2.81, 95 % CI 1.142 to 6.907), and persistent purpura (OR 2.57, 95 % CI 1.119 to 5.909) were independent risk factors for renal involvement.

CONCLUSIONS

Our results show that obesity can increase the hazard of renal involvement in children with HSP and reconfirm that older age at onset and persistent purpura are the independent risk factors for renal involvement.

WHAT IS KNOWN

• There have been some reports that obesity was associated with the development of renal injury. • It is not clear whether obesity can increase the risk of renal involvement in children with HSP. What is New: • The main finding of this study is that obesity can increase the hazard of renal involvement in children with HSP.