The Renal Pathology of Obesity: Structure-Function Correlations

Fenoxaprop-P-ethyl herbicide induces biochemical, histopathological, and immunohistochemical alterations in the kidneys and testes of rats

BACKGROUND

Pesticide use, a global practice in agriculture, contributes to environmental contamination and poses significant health risks. This study investigates the impact of Fenoxaprop-P-ethyl (FPE), a chiral herbicide, on renal function and male fertility in albino rats.

MATERIALS AND METHODS

The study was conducted on 8-week-old male albino rats subjected to an experimental protocol as follows: the control group, a vehicle group, and two FPE-treated groups: one given 26 mg/kg and the other 157.5 mg/kg (1/20 LD₅₀) for 30 days. Blood samples were collected for biochemical analysis, and oxidative stress markers, comet assay assessment, histopathological examination, and immunohistochemical analysis were performed on renal and testicular tissues.

RESULTS

The study shows that FPE-treated rats experience a dose-dependent increase in renal biomarkers, along with redox imbalance, and DNA damage, with kidney tissue alterations and increased expression of inflammatory cytokine tumor necrosis factor-alpha and fibrogenic marker transforming growth factor beta 1. Additionally, FPE-treated rats experience reduced sex hormones, along with redox imbalance, DNA damage, with testicular spermatogenic layer damage, and decreased proliferating cell nuclear antigen expression.

CONCLUSION

Sub-chronic exposure to FPE induces renal damage, inflammation, and fibrosis, accompanied by disruptions in male reproductive health. The study emphasizes the intricate relationship between oxidative stress, hormonal imbalance, and reproductive dysfunction.

DATA AVAILABILITY

Not applicable.

Metabolic dysfunction-associated kidney disease: pathogenesis and clinical manifestations

In recent years, there have been significant changes in the lifestyle and dietary habits of the population characterized by an increased intake of high-calorie food and a sedentary lifestyle without physical activity. The increased prevalence of overweight and obesity has led to metabolic dysfunction and related complications, such as cardiovascular disease and chronic kidney disease. The purpose of this review is to highlight the importance, clinical features, and pathogenesis of metabolic dysfunction-associated kidney disease (MDAKD). MDAKD is a term that describes kidney disease arising from metabolic dysfunction, often in the context of metabolic syndrome, and is characterized by the presence of chronic kidney disease in individuals with metabolic abnormalities such as obesity, insulin resistance, diabetes mellitus, dyslipidemia, and hypertension. MDAKD includes diabetic kidney disease, obesity-related kidney disease, and, increasingly, other less common kidney diseases where metabolic dysfunction may affect disease progression. MDAKD is part of a spectrum of diseases whose pathogenesis is driven by metabolic dysfunction and has recently led to the proposal of a new nomenclature including metabolic dysfunction-associated steatotic liver disease and cardio-kidney-metabolic syndrome. The new terminology of MDAKD places additional emphasis on the pathogenic role of metabolic dysfunction in kidney disease.

Investigation of the role and mechanism of dapagliflozin in mitigating renal injury in rats afflicted with diabetic kidney disease

The etiology of diabetic kidney disease (DKD) is multifaceted, with hyperglycemia, inflammation, oxidative stress, and fibrosis recognized as key contributors to renal damage in individuals with DKD. Clinical evidence suggests that dapagliflozin not only reduces blood glucose levels but also demonstrates superior efficacy in ameliorating pancreatic islet cell injury while preserving cardiac and renal function. However, the precise underlying mechanism has been poorly elucidated in the current literature. In this study, a DKD rat model was established by administering a single intraperitoneal injection of streptozotocin (STZ) to investigate the renoprotective properties of dapagliflozin and its underlying mechanisms. The findings of this study indicate that dapagliflozin enhanced pancreatic islet cell function, lowered blood glucose levels, and significantly reduced biochemical markers and renal pathological damage in DKD rats. Dapagliflozin also exerted anti-inflammatory, antioxidant, and antifibrotic effects by inhibiting the activation of the p38 MAPK/NF-κB pathway, enhancing the activity of the SIRT1/Akt/GSK-3β/Nrf2/HO-1 signaling pathway, and inhibiting the over-activation of the TGF-β1/Smad2/3 signaling pathway. These effects led to a reduction in renal injury and improved renal function in DKD rats.

Nutritional assessment and medical dietary therapy for management of obesity in patients with non-dialysis chronic kidney disease: a practical guide for endocrinologist, nutritionists and nephrologists. A consensus statement from the Italian society of endocrinology (SIE), working group of the club nutrition-hormones and metabolism; the Italian society of nutraceuticals (SINut), club ketodiets and nutraceuticals "KetoNut-SINut"; and the Italian society of nephrology (SIN)

PURPOSE

Chronic kidney disease (CKD) is a serious health concern with an estimated prevalence of about 13.4% worldwide. It is cause and consequence of various comorbidities, including cardiovascular diseases. In parallel, common pathological conditions closely related to ageing and unhealthy dietary habits increase the risk of CKD development and progression, including type 2 diabetes and obesity. Among these, obesity is either independent risk factor for new onset kidney disease or accelerates the rate of decline of kidney function by multiple mechanisms. Therefore, the role of diets aimed at attaining weight loss in patients with obesity is clearly essential to prevent CKD as to slow disease progression. Various dietary approaches have been licensed for the medical dietary therapy in CKD, including low-protein diet and Mediterranean diet. Interestingly, emerging evidence also support the use of low-carbohydrate/ketogenic diet (LCD/KD) in these patients. More specifically, LCD/KDs may efficiently promote weight loss, improve metabolic parameters, and reduce inflammation and oxidative stress, resulting in a dietary strategy that act globally in managing collateral conditions that are directly and indirectly related to the kidney function.

CONCLUSION

This consensus statement from the Italian Society of Endocrinology (SIE), working group of the Club Nutrition - Hormones and Metabolism; the Italian Society of Nutraceuticals (SINut), Club Ketodiets and Nutraceuticals "KetoNut-SINut"; and the Italian Society of Nephrology (SIN) is intended to be a guide for Endocrinologist, Nutritionists and Nephrologist who deal with the management of patients with obesity with non-dialysis CKD providing a practical guidance on assessing nutritional status and prescribing the optimal diet in order to best manage obesity to prevent CKD and its progression to dialysis.

Obesity-related renal dysfunction: gender-specific influence of visceral adiposity and early impact of metabolic and bariatric surgery

Introduction

Renal dysfunction is a recognized complication of obesity with an incompletely characterized pathophysiology. Improvement of glomerular filtration rate (GFR) after metabolic and bariatric surgery (MBS) has been reported across all classes of renal function. Inter-gender differences with regard to correlates of renal function have been described, but the influence of body composition is an understudied area. We aimed to explore determinants of renal function in obesity and to assess its variations after MBS, with a focus on body composition parameters in males and females, respectively.

Materials methods

We conducted a retrospective study on 196 patients who underwent laparoscopic sleeve gastrectomy, evaluated preoperatively and 6 months after the intervention. Recorded data included clinical and biochemical assessment, as well as body composition estimation via dual-energy X-ray absorptiometry. Serum creatinine-based formulas were used for the estimation of GFR.

Results

We included a total of 196 patients (80 males and 116 females), with a mean age of 41.43 ± 10.79. Median baseline body mass index was 42.6 (6.61) kg/m2 and 6 months excess weight loss (EWL) reached 71.43 ± 17.18%, in females, estimated GFR correlated negatively with visceral adipose tissue (VAT) mass (rho=-.368) and this correlation was stronger in females with type 2 diabetes mellitus. Moreover, women in the third VAT mass tertile were 5 times more likely to have reduced GFR compared to the first tertile. Renal function improved after MBS across all classes of filtration. In males, this improvement correlated with EWL (rho=.358) and lean mass variation (rho=-.412), while in females it correlated with VAT mass variation (rho=-.266).

Conclusions

Our results are consistent with previous findings on the positive impact of MBS on renal function and suggest a more prominent impact of visceral adiposity on GFR in females.

New Perspectives on Obesity-Associated Nephropathy from Pathophysiology to Therapeutics: Revealing the Promise of GLP-1 RA Therapy

Obesity represents a substantial risk factor for a multitude of metabolic disorders, which seriously threatens human life and health. As the global obesity epidemic intensifies, obesity-related nephropathy (ORN) has attracted great attention. ORN arises from both physical/mechanical and non-physical insults to the glomerular and tubular structures precipitated by obesity, culminating in structural impairments and functional aberrations within the kidneys. Physical injury factors include changes in renal hemodynamics, renal compression, and mechanical stretching of podocytes. Non-physical injury factors include overactivation of the RAAS system, insulin resistance, lipotoxicity, inflammation, and dysregulation of bile acid metabolism. Exploring molecules that target modulation of physical or nonphysical injury factors is a potential approach to ORN treatment. ORN is characterized clinically by microproteinuria and pathologically by glomerulomegaly, which is atypical and makes early diagnosis difficult. Investigating early diagnostic markers for ORN thus emerges as a critical direction for future research. Additionally, there is no specific drug for ORN in clinical treatment, which mainly focuses on weight reduction, mitigating proteinuria, and preserving renal function. In our review, we delineate a progressive therapeutic approach involving enhancements in lifestyle, pharmacotherapy, and bariatric surgery. Our emphasis underscores glucagon-like peptide-1 receptor agonists (GLP-1 RAs) as poised to emerge as pivotal therapeutic modalities for ORN in forthcoming clinical avenues.

Prevalence and metabolic risk factors of chronic kidney disease among a Mexican adult population: a cross-sectional study in primary healthcare medical units

Introduction

The intricate relationship between obesity and chronic kidney disease (CKD) progression underscores a significant public health challenge. Obesity is strongly linked to the onset of several health conditions, including arterial hypertension (AHTN), metabolic syndrome, diabetes, dyslipidemia, and hyperuricemia. Understanding the connection between CKD and obesity is crucial for addressing their complex interplay in public health strategies.

Objective

This research aimed to determine the prevalence of CKD in a population with high obesity rates and evaluate the associated metabolic risk factors.

Material and Methods

In this cross-sectional study conducted from January 2017 to December 2019 we included 3,901 participants of both sexes aged ≥20 years who were selected from primary healthcare medical units of the Mexican Social Security Institute (IMSS) in Michoacan, Mexico. We measured the participants' weight, height, systolic and diastolic blood pressure, glucose, creatinine, total cholesterol, triglycerides, HDL-c, LDL-c, and uric acid. We estimated the glomerular filtration rate using the Collaborative Chronic Kidney Disease Epidemiology (CKD-EPI) equation.

Results

Among the population studied, 50.6% were women and 49.4% were men, with a mean age of 49 years (range: 23-90). The prevalence of CKD was 21.9%. Factors significantly associated with an increased risk of CKD included age ≥60 years (OR = 11.70, 95% CI [9.83-15.93]), overweight (OR = 4.19, 95% CI [2.88-6.11]), obesity (OR = 13.31, 95% CI [11.12-15.93]), abdominal obesity (OR = 9.25, 95% CI [7.13-11.99]), AHTN (OR = 20.63, 95% CI [17.02-25.02]), impaired fasting glucose (IFG) (OR = 2.73, 95% CI [2.31-3.23]), type 2 diabetes (T2D) (OR = 14.30, 95% CI [11.14-18.37]), total cholesterol (TC) ≥200 mg/dL (OR = 6.04, 95% CI [5.11-7.14]), triglycerides (TG) ≥150 mg/dL (OR = 5.63, 95% CI 4.76-6.66), HDL-c <40 mg/dL (OR = 4.458, 95% CI [3.74-5.31]), LDL-c ≥130 mg/dL (OR = 6.06, 95% CI [5.12-7.18]), and serum uric acid levels ≥6 mg/dL in women and ≥7 mg/dL in men (OR = 8.18, 95% CI [6.92-9.68]), (p < 0.0001). These factors independently contribute to the development of CKD.

Conclusions

This study underscores the intricate relationship between obesity and CKD, revealing a high prevalence of CKD. Obesity, including overweight, abdominal obesity, AHTN, IFG, T2D, dyslipidemia, and hyperuricemia emerged as significant metabolic risk factors for CKD. Early identification of these risk factors is crucial for effective intervention strategies. Public health policies should integrate both pharmacological and non-pharmacological approaches to address obesity-related conditions and prevent kidney damage directly.

Proximal tubule hypertrophy and hyperfunction: a novel pathophysiological feature in disease states

The role of proximal tubules (PTs), a major component of the renal tubular structure in the renal cortex, has been examined extensively. Along with its physiological role in the reabsorption of various molecules, including electrolytes, amino acids and monosaccharides, transcellular transport of different hormones and regulation of homeostasis, pathological events affecting PTs may underlie multiple disease states. PT hypertrophy or a hyperfunctioning state, despite being a compensatory mechanism at first in response to various stimuli or alterations at tubular transport proteins, have been shown to be critical pathophysiological events leading to multiple disorders, including diabetes mellitus, obesity, metabolic syndrome and congestive heart failure. Moreover, pharmacotherapeutic agents have primarily targeted PTs, including sodium-glucose cotransporter 2, urate transporters and carbonic anhydrase enzymes. In this narrative review, we focus on the physiological role of PTs in healthy states and the current understanding of the PT pathologies leading to disease states and potential therapeutic targets.

The New Challenge of Obesity - Obesity-Associated Nephropathy

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

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

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

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.

The Fat Kidney

PURPOSE OF REVIEW

The purpose of this review is to summarize the current evidence on the role of obesity in the development and progression of chronic kidney disease and the current evidence on nutritional, pharmacological, and surgical strategies for the management of individuals with obesity and chronic kidney disease.

RECENT FINDINGS

Obesity can hurt the kidney via direct pathways, through the production of pro-inflammatory adipocytokines, and indirectly due to systemic complications of obesity, including type 2 diabetes mellitus and hypertension. In particular, obesity can damage the kidney through alterations in renal hemodynamics resulting in glomerular hyperfiltration, proteinuria and, finally, impairment in glomerular filtratation rate. Several strategies are available for weight loss and maintenance, such as the modification of lifestyle (diet and physical activity), anti-obesity drugs, and surgery therapy, but there are no clinical practice guidelines to manage subjects with obesity and chronic kidney disease. Obesity is an independent risk factor for the progression of chronic kidney disease. In subjects with obesity, weight loss can slow down the progression of renal failure with a significant reduction in proteinuria and improvement in glomerular filtratation rate. Specifically, in the management of subjects with obesity and chronic renal disease, it has been shown that bariatric surgery can prevent the decline in renal function, while further clinical studies are needed to evaluate the efficacy and safety on the kidney of weight reducing agents and the very low-calorie ketogenic diet.

Obesity and chronic kidney disease

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

The Beneficial Effects of Bariatric-Surgery-Induced Weight Loss on Renal Function

Obesity represents an independent risk factor for the development of chronic kidney disease (CKD), leading to specific histopathological alterations, known as obesity-related glomerulopathy. Bariatric surgery is the most effective means of inducing and maintaining sustained weight loss. Furthermore, in the context of bariatric-surgery-induced weight loss, a reduction in the proinflammatory state and an improvement in the adipokine profile occur, which may also contribute to the improvement of renal function following bariatric surgery. However, the assessment of renal function in the context of obesity and following marked weight loss is difficult, since the formulas adopted to estimate glomerular function use biomarkers whose production is dependent on muscle mass (creatinine) or adipose tissue mass and inflammation (cystatin-c). Thus, following bariatric surgery, the extent to which reductions in plasma concentrations reflect the actual improvement in renal function is not clear. Despite this limitation, the available literature suggests that in patients with hyperfiltration at baseline, GFR is reduced following bariatric surgery, whereas GFR is increased in patients with decreased GFR at baseline. These findings are also confirmed in the few studies that have used measured rather than estimated GFR. Albuminuria is also decreased following bariatric surgery. Moreover, bariatric surgery seems superior in achieving the remission of albuminuria and early CKD than the best medical treatment. In this article, we discuss the pathophysiology of renal complications in obesity, review the mechanisms through which weight loss induces improvements in renal function, and provide an overview of the renal outcomes following bariatric surgery.

Pulse pressure and the risk of renal hyperfiltration in young adults: Results from Korea National Health and Nutrition Examination Survey (2010–2019)

Background

High pulse pressure (PP) is associated with increased risk of decline of kidney function. However, little is known about the association between PP and RHF in young adults. This study aimed to evaluate the association between PP and RHF in healthy young adults.

Methods

Data were retrieved from the Korea National Health and Nutrition Examination Survey from 2010 to 2019. A total of 10,365 participants aged 19–39 years with no hypertension and normal kidney function were analyzed. RHF was defined as logarithm transformed estimated glomerular filtration rate (eGFR) with residuals >90th percentile after adjustment for sex, logarithm transformed age, weight, and height. Participants were divided into tertile based on PP levels.

Results

The prevalence of RHF was higher in higher PP tertile group (6.6, 10.5, and 12.7% in T1, T2, and T3; P for trend < 0.001). In multivariable logistic regression analyses, the risk for RHF was increased in higher PP tertiles compared to the lowest tertile [odds ratio (OR), 1.42; 95% confidence interval (CI), 1.19–1.69 in T2; OR, 1.44; 95% CI, 1.20–1.73 in T3]. When PP levels were treated as continuous variable, the risk of RHF was increased 2.36 per 1.0 increase of PP (P < 0.001). In subgroup analyses stratified sex, histories of diabetes or dyslipidemia, and isolated systolic hypertension or isolated diastolic hypertension, there were no significant interactions with PP for the risk for RHF, suggesting that high PP was associated with increased risk of RHF regardless of subgroups. However, the subgroup with BMI showed significant interaction with PP for the risk of RHF, indicating that participants with BMI ≥ 25 kg/m² were at higher risk of RHF with increasing PP levels than those with BMI < 25 kg/m² (OR, 1.89; 95% CI, 1.25–2.87 in BMI < 25 kg/m²; OR, 3.16; 95% CI, 1.74–5.73 in BMI ≥ 25 kg/m²; P for interaction = 0.01).

Conclusion

High PP is associated with an increased risk of RHF in healthy young adults and this association is prominent in obese young adults. The assessment of PP and associated RHF may give benefit to early detect the potential risk of CKD development in young adults.

Examining the evidence for weight management in individuals with type 2 diabetes

The obesity epidemic has been linked to the worsening diabetes epidemic. Despite this, weight reduction for individuals with obesity is seen as a secondary, or even tertiary, consideration in the treatment of type 2 diabetes (T2D). The aim of this review is to examine the benefits of weight management in individuals with T2D. A literature review of current available published data on the benefits of weight reduction in individuals with T2D was conducted. In individuals with T2D who have obesity or overweight, modest and sustained weight reduction results in improvement in glycaemic control and decreased utilization of glucose-lowering medication. A total body weight loss of 5% or higher reduces HbA1c levels and contributes to mitigating risk factors of cardiovascular disease, such as hyperlipidaemia and hypertension, as well as other disease-related complications of obesity. Progressive improvements in glycaemic control and cardiometabolic risk factors can occur when the total body weight loss increases to 10% or more. In the approach to treating patients with T2D and obesity, prioritizing weight management and the use of therapeutics that offer glycaemic control as well as the additional weight loss should be emphasized given their potential to attenuate the progression and severity of T2D.