Leptin stimulates proliferation and TGF-beta expression in renal glomerular endothelial cells: potential role in glomerulosclerosis [seecomments]

The sclerotic component of metabolic syndrome: Fibroblast activities may be the central common denominator driving organ function loss and death

Fibrosis is a common feature of more than 50 different diseases and the cause of more than 35% of deaths worldwide, of which liver, kidney, skin, heart and, recently, lungs are receiving the most attention. Tissue changes, resulting in loss of organ function, are both a cause and consequence of disease and outcome. Fibrosis is caused by an excess deposition of extracellular matrix proteins, which over time results in impaired organ function and organ failure, and the pathways leading to increased fibroblast activation are many. This narrative review investigated the common denominator of fibrosis, fibroblasts, and the activation of fibroblasts, in response to excess energy consumption in liver, kidney, heart, skin and lung fibrosis. Fibroblasts are the main drivers of organ function loss in lung, liver, skin, heart and kidney disease. Fibroblast activation in response to excess energy consumption results in the overproduction of a range of collagens, of which types I, III and VI seem to be the essential drivers of disease progression. Fibroblast activation may be quantified in serum, enabling profiling and selection of patients. Activation of fibroblasts results in the overproduction of collagens, which deteriorates organ function. Patient profiling of fibroblast activities in serum, quantified as collagen production, may identify an organ death trajectory, better enabling identification of the right treatment for use in different metabolic interventions. As metabolically activated patients have highly elevated risk of kidney, liver and heart failure, it is essential to identify which organ to treat first and monitor organ status to correct treatment regimes. In direct alignment with this, it is essential to identify the right patients with the right organ deterioration trajectory for enrolment in clinical studies.

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.

Adiponectin-to-leptin ratio and incident chronic kidney disease: Sex and body composition-dependent association

BACKGROUND

The association between the adiponectin-to-leptin ratio (A/L ratio) and the risk of incident chronic kidney disease (CKD) is poorly understood. This study aimed to investigate the association between A/L ratio and the risk of incident CKD and to examine whether such a relationship varied according to sex and body composition.

METHODS

In this prospective community-based cohort, participants with normal kidney function were analysed (N = 5192). The association between the A/L ratio at baseline and the risk of incident CKD, defined as two or more occasions with an estimated glomerular filtration rate of <60 mL/min/m2 or proteinuria of ≥1+ on a dipstick test during the follow-up period, was evaluated using multivariable Cox proportional hazards analyses. Subgroup analyses were conducted based on sex, body mass index (BMI) and the presence of sarcopenia.

RESULTS

The participants' mean age was 57.2 ± 8.3 years, and 53.2% were women. The A/L ratio was higher in men compared with women (1.5 [0.8-3.2] and 0.5 [0.3-0.9] μg/ng, P < 0.001). During a median follow-up of 9.8 [9.5-10.0] years, 417 incident CKD events occurred (8.7 per 1000 person-years). Men in the highest quartile of A/L ratio had a lower risk of incident CKD (adjusted hazard ratio [aHR], 0.57; 95% confidence interval [CI], 0.33-0.99) than those in the lowest quartile. Additionally, a 1.0 increase in A/L ratio was associated with a 12% decreased risk of incident CKD in men (aHR, 0.88; 95% CI, 0.80-0.97). However, no significant association was observed in women. In subgroup analysis stratified by BMI and the presence of sarcopenia, the association between a high A/L ratio and a reduced risk of incident CKD was consistent in men with a BMI < 23.0 kg/m2 and those with sarcopenia. However, no significant association was observed between men with a BMI ≥ 23.0 kg/m2 and those without sarcopenia.

CONCLUSIONS

A high A/L ratio is an independent marker of a reduced risk of incident CKD in men, especially in those with a BMI < 23.0 kg/m2 and sarcopenia.

Early Sepsis-Associated Acute Kidney Injury and Obesity

Importance

The prevalence of obesity is increasing in the intensive care unit (ICU). Although obesity is a known risk factor for chronic kidney disease, its association with early sepsis-associated acute kidney injury (SA-AKI) and their combined association with patient outcomes warrant further investigation.

Objective

To explore the association between obesity, early SA-AKI incidence, and clinical outcomes in patients with sepsis.

Design, Setting, and Participants

This nationwide, prospective cohort study analyzed patients aged 19 years or older who had sepsis and were admitted to 20 tertiary hospital ICUs in Korea between September 1, 2019, and December 31, 2021. Patients with preexisting stage 3A to 5 chronic kidney disease and those with missing body mass index (BMI) values were excluded.

Exposures

Sepsis and hospitalization in the ICU.

Main Outcomes and Measures

The primary outcome was SA-AKI incidence within 48 hours of ICU admission, and secondary outcomes were mortality and clinical recovery (survival to discharge within 30 days). Patients were categorized by BMI (calculated as weight in kilograms divided by height in meters squared), and data were analyzed by logistic regression adjusted for key characteristics and clinical factors. Multivariable fractional polynomial regression models and restricted cubic spline models were used to analyze the clinical outcomes with BMI as a continuous variable.

Results

Of the 4041 patients (median age, 73 years [IQR, 63-81 years]; 2349 [58.1%] male) included in the study, 1367 (33.8%) developed early SA-AKI. Obesity was associated with a higher incidence of SA-AKI compared with normal weight (adjusted odds ratio [AOR], 1.40; 95% CI, 1.15-1.70), as was every increase in BMI of 10 (OR, 1.75; 95% CI, 1.47-2.08). While obesity was associated with lower in-hospital mortality in patients without SA-AKI compared with their counterparts without obesity (ie, underweight, normal weight, overweight) (AOR, 0.72; 95% CI, 0.54-0.94), no difference in mortality was observed in those with SA-AKI (AOR, 0.85; 95% CI, 0.65-1.12). Although patients with obesity without SA-AKI had a greater likelihood of clinical recovery than their counterparts without obesity, clinical recovery was less likely among those with both obesity and SA-AKI.

Conclusions and Relevance

In this cohort study of patients with sepsis, obesity was associated with a higher risk of early SA-AKI and the presence of SA-AKI modified the association of obesity with clinical outcomes.

Abdominal adipose tissue and type 2 diabetic kidney disease: adipose radiology assessment, impact, and mechanisms

Diabetic kidney disease (DKD) is a significant healthcare burden worldwide that substantially increases the risk of kidney failure and cardiovascular events. To reduce the prevalence of DKD, extensive research is being conducted to determine the risk factors and consequently implement early interventions. Patients with type 2 diabetes mellitus (T2DM) are more likely to be obese. Abdominal adiposity is associated with a greater risk of kidney damage than general obesity. Abdominal adipose tissue can be divided into different fat depots according to the location and function, including visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), perirenal adipose tissue (PAT), and renal sinus adipose tissue (RSAT), which can be accurately measured by radiology techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI). Abdominal fat depots may affect the development of DKD through different mechanisms, and radiologic abdominal adipose characteristics may serve as imaging indicators of DKD risk. This review will first describe the CT/MRI-based assessment of abdominal adipose depots and subsequently describe the current studies on abdominal adipose tissue and DKD development, as well as the underlying mechanisms in patients of T2DM with DKD.

The effect of a body shape index (ABSI) and its interaction with low estimated glomerular filtration rate (eGFR) on osteoporosis in elderly Chinese

BACKGROUND

Both obesity and chronic kidney disease (CKD) contribute to osteoporosis risk, but the effect of a newly developed index (e.g., a body shape index, ABSI) of central obesity and its interaction with low estimated glomerular filtration rate (eGFR) on osteoporosis remains unknown.

METHODS

A total of 2534 Chinese individuals were enrolled in our ongoing cohort study: Osteoporosis Preventive Project. ABSI and eGFR were calculated as obesity-related indexes and renal function markers, respectively. A logistic regression model was used to estimate the association between osteoporosis and related clinical parameters (e.g., ABSI, eGFR), and to assess the additive and multiplicative interactions between risk factors and osteoporosis. Relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP) and synergy index (SI) were calculated to assess the additive interaction.

RESULTS

High ABSI was significantly associated with an increased risk of osteoporosis in participants compared with the lowest quartile of ABSI in both crude and adjusted models. Individuals in the lower quartiles of eGFR had a significantly increased risk of osteoporosis compared with those in the highest quartiles in crude models. After adding age and other variables in the model, the association was abolished. In addition, after adjusting for variables, high ABSI with low eGFR (RERI: 0.45, 95% CI: 0.15-0.75; AP: 0.39, 95% CI: 0.17-0.60) still displayed a noticeable interaction on the risk of osteoporosis. The multiplicative interactive effect between high ABSI with low eGFR on osteoporosis was statistically significant in the multivariable-adjusted model (P < 0.05).

CONCLUSION

Our study indicated that higher ABSI increases the risk of osteoporosis independently and synergistically with low eGFR in Chinese elderly adults. The findings increase our understanding of the interactions of osteoporosis risk factors and may help provide potential interventions for osteoporosis.

The Role of Inflammation in CKD

Chronic kidney disease (CKD) affects many adults worldwide. Persistent low-grade inflammation is a substantial factor in its development and progression and has correlated with increased mortality and cardiovascular problems. This low-grade inflammation is a product of dysregulation of the normal balance between pro- and anti-inflammatory markers. Various factors such as increased innate immune system activation, reactive oxygen species production, periodontal disease, dysregulation of anti-inflammatory systems and intestinal dysbiosis result in the dysregulation of this balance. Furthermore, this low-grade inflammation has down-effects such as hypertension, renal fibrosis and acceleration of renal function decline. Moreover, low-grade inflammation over time has been linked to malignancy in CKD. As CKD progresses, many patients require dialysis, which has a negative bidirectional relationship with persistent inflammation. Treatment options for inflammation in CKD are vast, including cytokine inhibitors, statins and diets. However, more research is needed to create a standardized management plan. In this review, we will examine the normal physiology of the kidney and its relationship with the immune system. We will then delve into the pathology behind persistent inflammation, the various causes of inflammation, the downstream effects of inflammation, dialysis and potential treatments for inflammation in CKD.

Expression of leptin receptor in renal tubules is sparse but implicated in leptin-dependent kidney gene expression and function

Leptin regulates energy balance via leptin receptors expressed in central and peripheral tissues, but little is known about leptin-sensitive kidney genes and the role of the tubular leptin receptor (Lepr) in response to a high-fat diet (HFD). Quantitative RT-PCR analysis of Lepr splice variants A, B, and C revealed a ratio of ∼100:10:1 in the mouse kidney cortex and medulla, with medullary levels being ∼10 times higher. Leptin replacement in ob/ob mice for 6 days reduced hyperphagia, hyperglycemia, and albuminuria, associated with normalization of kidney mRNA expression of molecular markers of glycolysis, gluconeogenesis, amino acid synthesis, and megalin. Normalization of leptin for 7 h in ob/ob mice did not normalize hyperglycemia or albuminuria. Tubular knockdown of Lepr [Pax8-Lepr knockout (KO)] and in situ hybridization revealed a minor fraction of Lepr mRNA in tubular cells compared with endothelial cells. Nevertheless, Pax8-Lepr KO mice had lower kidney weight. Moreover, while HFD-induced hyperleptinemia, increases in kidney weight and glomerular filtration rate, and a modest blood pressure lowering effect were similar compared with controls, they showed a blunted rise in albuminuria. Use of Pax8-Lepr KO and leptin replacement in ob/ob mice identified acetoacetyl-CoA synthetase and gremlin 1 as tubular Lepr-sensitive genes that are increased and reduced by leptin, respectively. In conclusion, leptin deficiency may increase albuminuria via systemic metabolic effects that impinge on kidney megalin expression, whereas hyperleptinemia may induce albuminuria by direct tubular Lepr effects. Implications of Lepr variants and the novel tubular Lepr/acetoacetyl-CoA synthetase/gremlin 1 axis remain to be determined.NEW & NOTEWORTHY This study provides new insights into kidney gene expression of leptin receptor splice variants, leptin-sensitive kidney gene expression, and the role of the leptin receptor in renal tubular cells for the response to diet-induced hyperleptinemia and obesity including albuminuria.

Association Between Obesity and Chronic Kidney Disease: Multivariable Mendelian Randomization Analysis and Observational Data From a Bariatric Surgery Cohort

Obesity is postulated to independently increase chronic kidney disease (CKD), even after adjusting for type 2 diabetes (T2D) and hypertension. Dysglycemia below T2D thresholds, frequently seen with obesity, also increases CKD risk. Whether obesity increases CKD independent of dysglycemia and hypertension is unknown and likely influences the optimal weight loss (WL) needed to reduce CKD. T2D remission rates plateau with 20-25% WL after bariatric surgery (BS), but further WL increases normoglycemia and normotension. We undertook bidirectional inverse variance weighted Mendelian randomization (IVWMR) to investigate potential independent causal associations between increased BMI and estimated glomerular filtration rate (eGFR) in CKD (CKDeGFR) (<60 mL/min/1.73 m2) and microalbuminuria (MA). In 5,337 BS patients, we assessed whether WL influences >50% decline in eGFR (primary outcome) or CKD hospitalization (secondary outcome), using <20% WL as a comparator. IVWMR results suggest that increased BMI increases CKDeGFR (b = 0.13, P = 1.64 × 10-4; odds ratio [OR] 1.14 [95% CI 1.07, 1.23]) and MA (b = 0.25; P = 2.14 × 10-4; OR 1.29 [1.13, 1.48]). After adjusting for hypertension and fasting glucose, increased BMI did not significantly increase CKDeGFR (b = -0.02; P = 0.72; OR 0.98 [0.87, 1.1]) or MA (b = 0.19; P = 0.08; OR 1.21 [0.98, 1.51]). Post-BS WL significantly reduced the primary outcome with 30 to <40% WL (hazard ratio [HR] 0.53 [95% CI 0.32, 0.87]) but not 20 to <30% WL (HR 0.72 [0.44, 1.2]) and ≥40% WL (HR 0.73 [0.41, 1.30]). For CKD hospitalization, progressive reduction was seen with increased WL, which was significant for 30 to <40% WL (HR 0.37 [0.17, 0.82]) and ≥40% WL (HR 0.24 [0.07, 0.89]) but not 20 to <30% WL (HR 0.60 [0.29, 1.23]). The data suggest that obesity is likely not an independent cause of CKD. WL thresholds previously associated with normotension and normoglycemia, likely causal mediators, may reduce CKD after BS.

Adipose tissue metabolic changes in chronic kidney disease

Adipose tissue is a complex organ whose functions go beyond being an energy reservoir to sustain proper body energy homeostasis. Functioning as an endocrine organ, the adipose tissue has an active role in the body's metabolic balance regulation through several secreted factors generally termed as adipokines. Thus, adipose tissue dysregulation in chronic kidney disease (CKD) can have a deep impact in the pathophysiology of diseases associated with metabolic dysregulation including metabolic syndrome, insulin resistance (IR), atherosclerosis, and even cachexia. CKD is a progressive disorder linked to increased morbidity and mortality. Despite being characterized by renal function loss, CKD is accompanied by metabolic disturbances such as dyslipidemia, protein energy wasting, chronic low-grade inflammation, IR, and lipid redistribution. Thus far, the mechanisms by which these changes occur and the role of adipose tissue in CKD development and progression are unclear. Further understanding of how these factors develop could have implications for the management of CKD by helping identify pharmacological targets to improve CKD outcomes.

The Role of Adipokines in the Pathogenesis of Psoriasis

Psoriasis is a chronic and immune-mediated skin condition characterized by pro-inflammatory cytokines and keratinocyte hyperproliferation. Dendritic cells, T lymphocytes, and keratinocytes represent the main cell subtypes involved in the pathogenesis of psoriasis, while the interleukin-23 (IL-23)/IL-17 pathway enhances the disease progression. Human adipose tissue is an endocrine organ, which secretes multiple proteins, known as adipokines, such as adiponectin, leptin, visfatin, or resistin. Current evidence highlights the immunomodulatory roles of adipokines, which may contribute to the progression or suppression of psoriasis. A better understanding of the complexity of psoriasis pathophysiology linked with adipokines could result in developing novel diagnostic or therapeutic strategies. This review aims to present the pathogenesis of psoriasis and the roles of adipokines in this process.

Kidney-Protective Effects of SGLT2 Inhibitors

The sodium-glucose cotransporter 2 (SGLT2) inhibitors have become an integral part of clinical practice guidelines to slow the progression of CKD in patients with and without diabetes mellitus. Although initially developed as antihyperglycemic drugs, their effect on the kidney is multifactorial resulting from profuse glycosuria and natriuresis consequent to their primary site of action. Hemodynamic and metabolic changes ensue that mediate kidney-protective effects, including ( 1 ) decreased workload of proximal tubular cells and prevention of aberrant increases in glycolysis, contributing to a decreased risk of AKI; ( 2 ) lowering of intraglomerular pressure by activating tubular glomerular feedback and reductions in BP and tissue sodium content; ( 3 ) initiation of nutrient-sensing pathways reminiscent of starvation activating ketogenesis, increased autophagy, and restoration of carbon flow through the mitochondria without production of reactive oxygen species; ( 4 ) body weight loss without a reduction in basal metabolic rate due to increases in nonshivering thermogenesis; and ( 5 ) favorable changes in quantity and characteristics of perirenal fat leading to decreased release of adipokines, which adversely affect the glomerular capillary and signal increased sympathetic outflow. Additionally, these drugs stimulate phosphate and magnesium reabsorption and increase uric acid excretion. Familiarity with kidney-specific mechanisms of action, potential changes in kidney function, and/or alterations in electrolytes and volume status, which are induced by these widely prescribed drugs, will facilitate usage in the patients for whom they are indicated.

Novel Insights in the Physiopathology and Management of Obesity-Related Kidney Disease

Obesity is recognized as an independent risk factor for the development of kidney disease, which has led to the designation of obesity-related glomerulopathy (ORG). Common renal features observed in this condition include glomerular hypertrophy, glomerulosclerosis, haemodynamic changes and glomerular filtration barrier defects. Additionally, and although less studied, obesity-related kidney disease also involves alterations in renal tubules, including tubule hypertrophy, lipid deposition and tubulointerstitial fibrosis. Although not completely understood, the harmful effects of obesity on the kidney may be mediated by different mechanisms, with alterations in adipose tissue probably playing an important role. An increase in visceral adipose tissue has classically been associated with the development of kidney damage, however, recent studies point to adipose tissue surrounding the kidney, and specifically to the fat within the renal sinus, as potentially involved in the development of ORG. In addition, new strategies for the treatment of patients with obesity-related kidney disease are focusing on the management of obesity. In this regard, some non-invasive options, such as glucagon-like peptide-1 (GLP-1) receptor agonists or sodium–glucose cotransporter-2 (SGLT2) inhibitors, are being considered for application in the clinic, not only for patients with diabetic kidney disease but as a novel pharmacological strategy for patients with ORG. In addition, bariatric surgery stands as one of the most effective options, not only for weight loss but also for the improvement of kidney outcomes in obese patients with chronic kidney disease.

Serum leptin level and incidence of CKD: a longitudinal study of adult enrolled in the Korean genome and epidemiology study(KoGES)

Background

Chronic kidney disease(CKD) is a major public health issue and is highly prevalent in the general population. Leptin is an adipose tissue-derived endocrine factor that has been associated with several metabolic factors involved in cardiovascular diseases. Several studies have investigated the association between leptin and renal diseases so far. But the results are conflicting between the studies. The objective of our study was to verify the direct association of serum leptin level with CKD development.

Methods

This prospective cohort study included 2646 adult aged 40–70 without CKD in the Korean Genome and Epidemiology Study(KoGES) across South Korea from November 2005 to February 2012. The primary outcome was the development of CKD as defined by National Kidney Foundation Kidney Disease Outcomes Quality Initiative (KDOQI). Multivariate stepwise logistic regression analysis was done to assess the independent associations, for with the incident of CKD as the dependent variable, in tertiles of leptin values.

Results

Among 1100 men and 1546 women with 2.8 mean years of follow-up, incidence of CKD was 18(1.63%) for men and 50(3.23%) for women. In the multivariate logistic regression models, individuals in the highest serum leptin tertile showed significant associations with risk of CKD after adjustment compared to the lowest tertiles in the population. The crude odds ratio for trend was 2.95(p = 0.004) for men. After adjusting for age, baseline eGFR variables showed correlation with statistical significance (OR for trend = 2.25, p = 0.037) for men. The same trends were also seen observed in all population and women also, but no statistical significance was found.

Conclusions

Higher plasma leptin levels are associated with the incidence of CKD, independent of traditional factors such as age, baseline eGFR. Our results suggest that leptin may partly explain part of the reported association between obesity and kidney disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02795-7.

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

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

Association of body mass index with kidney function and mortality in high cardiovascular risk population: A nationwide prospective cohort study

BACKGROUND

There is increasing awareness of the impact of obesity and underweight on cardiovascular (CV) disease, chronic kidney disease (CKD) and mortality. Abnormal body mass index (BMI) might be associated with worse clinical outcomes, including CKD progression, but limited evidence exists among Asian patients with high CV risk.

OBJECTIVE

To investigate the association of BMI with progressive loss of kidney function and all-cause mortality in Thai patients with high CV risk.

METHODS

In a national cohort of 5887 high CV risk subjects, we assessed the association of high BMI with the composite renal outcome (estimated glomerular filtration rate [eGFR] decline over 40%, eGFR less than 15 mL/min/1.73 m² , doubling of serum creatinine, initiation of dialysis and death related to renal causes) and with all-cause mortality in Cox proportional hazards models.

RESULTS

A total of 5887 participants (3217 male and 2670 female) with high CV risk were enrolled. Participants were classified into five groups by their baseline BMI; <20 kg/m² (n = 482), 20-24.9 kg/m² (n = 2437), 25-29.9 kg/m² (n = 2140), 30-34.9 kg/m² (n = 665) and 35 kg/m² (n = 163), respectively. On multivariate analysis of Cox proportional hazards models, adjusted for other covariates, baseline BMI ≥35 kg/m² was an independent predictor of loss of kidney function (HR 1.60, 95% CI 1.04-2.40) and all-cause mortality (HR 2.68, 95% CI 1.50-4.80). Baseline BMI <20 kg/m² was an independent predictor of all-cause mortality as well (adjusted HR 2.26, 95% CI 1.50-3.42).

CONCLUSION

In the high CV risk Thai population, a BMI of 35 kg/m² or more is associated with loss of kidney function and mortality. On the other hand, a BMI less than 20 kg/m² is also associated with all-cause mortality.

Ipragliflozin Ameliorates Diabetic Nephropathy Associated with Perirenal Adipose Expansion in Mice

Sodium glucose cotransporter-2 (SGLT2) inhibitors inhibit the development of diabetic nephropathy (DN). We determined whether changes in perirenal fat (PRAT) by a SGLT2 inhibitor ipragliflozin (Ipra) contribute to the suppression of DN development. High-fat diet (HFD)-fed mice were used as a DN model and were treated with or without Ipra for 6 weeks. Ipra treatment reduced urinary albumin excretion (UAE) and glomerular hypertrophy in HFD-fed mice. In the PRAT of Ipra-treated mice, adipocyte size was increased, and inflammation, fibrosis, and adipocyte death were suppressed. In conditioned medium made from PRAT (PRAT-CM) of Ipra-treated mice, the concentration of leptin was significantly lower than PRAT-CM of mice without Ipra treatment. Serum leptin concentration in renal vein positively correlated with UAE. PRAT-CM from HFD-fed mice showed greater cell proliferation signaling in mouse glomerular endothelial cells (GECs) than PRAT-CM from standard diet-fed mice via p38MAPK and leptin-dependent pathways, whose effects were significantly attenuated in PRAT-CM from Ipra-treated mice. These findings suggest that Ipra-induced PRAT expansion may play an important role in the improvement of DN in HFD-fed mice. In vitro experiments suggest that reduced PRAT-derived leptin by Ipra could inhibit GECs proliferation, possibly contributing to the suppression of DN development.

Obesity Without Metabolic Abnormality and Incident CKD: A Population-Based British Cohort Study

RATIONALE & OBJECTIVE

Metabolically healthy obesity (obesity without any metabolic abnormality) is not considered to be associated with increased risk of morbidity and mortality. We examined and quantified the association between metabolically healthy overweight/obesity and the risk of incident chronic kidney disease (CKD) in a British primary care population.

STUDY DESIGN

Retrospective population-based cohort study.

SETTING & PARTICIPANTS

4,447,955 of the 5,182,908 adults in The Health Improvement Network (THIN) database (United Kingdom, 1995-2015) with a recorded body mass index (BMI) at the time of registration date who were free of CKD and cardiovascular disease.

EXPOSURE

11 body size phenotypes were created, defined by BMI categories (underweight, normal weight, overweight, and obesity) and 3 metabolic abnormalities (diabetes, hypertension, and dyslipidemia).

OUTCOME

Incident CKD defined as a recorded code for kidney replacement therapy, a recorded diagnosis of CKD, or by an estimated glomerular filtration rate of<60mL/min/1.73m² for≥90 days, or a urinary albumin-creatinine ratio>3mg/mmol for≥90 days.

RESULTS

Of the 4.5 million individuals, 1,040,921 (23.4%) and 588,909 (13.2%) had metabolically healthy overweight and metabolically healthy obesity, respectively. During a mean follow-up interval of 5.4±4.3 (SD) years, compared with individuals with a metabolically healthy normal weight (n=1,656,231), there was a higher risk of incident CKD among those who had metabolically healthy overweight (adjusted HR, 1.30 [95% CI, 1.28-1.33]) and metabolically healthy obesity (adjusted HR, 1.66 [95% CI, 1.62-1.70]). The association was stronger in those younger than 65 years of age. In all BMI categories, there was greater risk of incident CKD with a greater number of metabolic abnormalities in a graded manner.

LIMITATIONS

Potential misclassification of metabolic status due to delayed diagnosis and residual confounding due to unmeasured factors.

CONCLUSIONS

Overweight and obesity without metabolic abnormality are associated with a higher risk of incident CKD compared with those with normal body weight and no metabolic abnormality.

The Causes and Potential Injurious Effects of Elevated Serum Leptin Levels in Chronic Kidney Disease Patients

Leptin is an adipokine that regulates appetite and body mass and has many other pleiotropic functions, including regulating kidney function. Increased evidence shows that chronic kidney disease (CKD) is associated with hyperleptinemia, but the reasons for this phenomenon are not fully understood. In this review, we focused on potential causes of hyperleptinemia in patients with CKD and the effects of elevated serum leptin levels on patient kidney function and cardiovascular risk. The available data indicate that the increased concentration of leptin in the blood of CKD patients may result from both decreased leptin elimination from the circulation by the kidneys (due to renal dysfunction) and increased leptin production by the adipose tissue. The overproduction of leptin by the adipose tissue could result from: (a) hyperinsulinemia; (b) chronic inflammation; and (c) significant lipid disturbances in CKD patients. Elevated leptin in CKD patients may further deteriorate kidney function and lead to increased cardiovascular risk.

Effect of Bariatric Surgery on Diagnosed Chronic Kidney Disease and Cardiovascular Events in Patients with Insulin-treated Type 2 Diabetes: a Retrospective Cohort Study from a Large UK Primary Care Database

Aims

To compare the effect of bariatric surgery on renal, chronic kidney disease (CKD) and cardiovascular (CV) outcomes among obese patients with insulin-treated type 2 diabetes (T2D) with and without microalbuminuria (i.e., uACR > 3.0 mg/mmol).

Methods

A retrospective cohort study was conducted among 11,125 active patients with T2D from The Health Improvement Network (THIN) database. Propensity score matching (up to 1:6 ratio) was used to identify patients who underwent bariatric surgery (N = 131) with a non-bariatric cohort (N = 579). Follow-up was undertaken for 10 years (6487 person-years) to compare differences in risk of cardiovascular events and in renal outcomes.

Results

For the matched cohort at baseline: mean age 52 ± 13 years (60% female); weight 116 ± 25 kg, body mass index (BMI) 41 ± 9kg/m², estimated glomerular filtration rate (eGFR); 70.4 ± 20 mL/min/1.73 m², and median albumin-creatinine ratio (uACR) 2.0 mg/mmol (interquartile range (IQR): 0.9–5.2 mg/mmol). Bariatric surgery was associated with a 54% reduction in developing CKD compared to their matched non-bariatric cohort (adjusted hazard ratio [aHR]: 0.46; 95%CI: 0.24–0.85, P = 0.02). Among patients with microalbuminuria at baseline, bariatric surgery was protective against CKD (aHR: 0.42, 95%CI: 0.18–0.99, P = 0.050). eGFR was significantly increased from baseline favouring the bariatric group during 75% of the follow-up time (calculated mean difference between groups: 4.1 mL/min/1.73 m²; P < 0.05), especially at 5-year point (74.2 vs 67.8 mL/min/1.73 m²; P < 0.001). However, no significant change was observed with non-fatal CVD episodes (aHR: 0.36, 95%CI: 0.11–1.13, P = 0.079). Albumin levels were significantly reduced throughout the 2 years following the surgery (3.9 vs 4.1 g/dL, P < 0.001). uACR and total protein levels had little or no statistical association to the intervention.

Conclusion

Bariatric surgery may protect patients with diabetes with or without microalbuminuria against the risk of CKD and with a modest protective effect on non-fatal CVD risk. Bariatric surgery is also associated with improvements in overall renal outcomes such as eGFR.

Association of the ratio of visceral-to-subcutaneous fat volume with renal function among patients with primary aldosteronism

Patients with primary aldosteronism have a higher risk of chronic kidney disease. Visceral fat tissue is hypothesized to stimulate the adrenal glands to overproduce aldosterone, and aldosterone promotes visceral fat tissue to produce inflammatory cytokines. However, it is unclear whether the volume of accumulated visceral fat tissue is associated with renal impairment among patients with hyperaldosteronism. We conducted a single-center cross-sectional study to assess the association between the estimated glomerular filtration rate and the ratio of the visceral-to-subcutaneous fat volume calculated by computed tomography. One hundred eighty patients with primary aldosteronism were enrolled. The mean ± SD age was 52.7 ± 11.0 years, and 60.0% were women. The ratio of visceral-to-subcutaneous fat volume was highly correlated with the estimated glomerular filtration rate (r = 0.49, p < 0.001). In multiple linear regression models, the ratio of visceral-to-subcutaneous fat tissue volume was significantly associated with the estimated glomerular filtration rate (estimates: -4.56 mL/min/1.73 m² per 1-SD), and there was an interaction effect between the plasma aldosterone concentration and the ratio of visceral-to-subcutaneous fat volume (p < 0.05). The group with a higher plasma aldosterone concentration exhibited a steeper decline in eGFR than the lower plasma aldosterone concentration group when the ratio increased. The ratio of visceral-to-subcutaneous fat tissue volume was an independent risk factor for renal dysfunction. This association increased in the presence of a high plasma aldosterone concentration. Clinicians should pay attention to the ratio of visceral-to-subcutaneous fat tissue volume and encourage primary aldosteronism patients to improve their lifestyle in addition to treating renin-aldosterone activity.

Collapsing focal segmental sclerosis in an HIV-negative patient

Collapsing focal segmental glomerulosclerosis (FSGS) is classically seen in HIV-infected patients and carries a dismal prognosis. It can also occur in HIV-negative patients in which case, early aggressive treatment with glucocorticoids may be helpful with improvement in both proteinuria and renal function.

Advances in understanding the role of adiponectin in renal fibrosis

Renal fibrosis is characterized by the proliferation of renal intrinsic cells, activation of renal interstitial fibroblasts and deposition of extracellular matrix (ECM), processes that lead to the progressive loss of renal function. Renal fibrosis is characterized by the proliferation of renal intrinsic cells, activation of renal interstitial fibroblasts, and septal fibrosis is recognized as a marker for the progression of chronic kidney disease, a condition that is associated with high morbidity and mortality and is a significant public health burden. Despite extensive studies, there are no effective treatments for renal fibrosis. Adiponectin (APN) is a protein mainly produced by adipocytes that has anti-inflammatory and anti-atherosclerotic effects, improves insulin resistance and provides other salutary effects. Recent studies found that APN can inhibit ECM deposition by inhibiting inflammation and oxidative stress, and by regulating the TGF-β, AMPK, MCP-1 and other signalling pathways. Many recent studies have examined the roles of these pathways in the pathogenesis of renal fibrosis. In this article, we review the pathogenic mechanism of APN in renal fibrosis and provide a theoretical basis for delaying and blocking renal fibrosis by alteration of APN activity.

Inflammatory mediators in the adipo-renal axis: leptin, adiponectin, and soluble ICAM-1

A lower 24-h urine pH (24h-pH), i.e., a higher renal excretion of free protons, at a given acid load to the body, denotes a reduction in the kidney's capacity for net acid excretion (NAE). There is increasing evidence, not only for patients with type 2 diabetes but also for healthy individuals, that higher body fatness or waist circumference (WC) has a negative impact on renal function to excrete acids (NAE). We hypothesized that adiposity-related inflammation molecules might mediate this relation between adiposity and renal acid excretion function. Twelve biomarkers of inflammation were measured in fasting blood samples from 162 adult participants (18-25 yr old) of the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) study who had undergone anthropometric measurements and collected 24-h urine samples. Both Baron and Kenny's (B&K's) steps to test mediation and causal mediation analysis were conducted to examine the potential mediatory roles of biomarkers of inflammation in the WC-24-h pH relationship after strictly controlling for laboratory-measured NAE. In B&K's mediation analysis, leptin, soluble intercellular adhesion molecule 1 (sICAM-1), and adiponectin significantly associated with the outcome 24-h pH and attenuated the WC-pH relation. In agreement herewith, causal mediation analysis estimated the "natural indirect effects" of WC on 24-h pH via leptin (P = 0.01) and adiponectin (P = 0.03) to be significant, with a trend for sICAM-1 (P = 0.09). The calculated proportions mediated by leptin, adiponectin, and sICAM-1 were 64%, 23%, and 12%, respectively. Both mediation analyses identified an inflammatory cytokine (leptin) and an anti-inflammatory cytokine (adiponectin) along with sICAM-1 as being potentially involved in mediating adiposity-related influences on renal acid excretion capacity.

The Impact of Obesity on the Severity of Clinicopathologic Parameters in Patients with IgA Nephropathy

Several studies reported the effect of obesity on the progression of IgA nephropathy (IgAN). However, the impact of obesity on the clinicopathologic presentation of IgAN remains uncertain. This is a retrospective cross-sectional study from eight university hospitals in South Korea. Patients were categorized into three groups using the Asia-Pacific obesity classification based on body mass index (BMI). Clinical and histopathologic data at the time of renal biopsy were analyzed. Among 537 patients with IgAN, the obese group was more hypertensive and had lower estimated glomerular filtration rate and more proteinuria than other groups. The histologic scores for mesangial matrix expansion (MME), interstitial fibrosis, tubular atrophy, and mesangial C3 deposition differed significantly between the three groups. Among these histopathologic parameters, BMI was independently positively associated with MME score on multivariable linear regression analysis (p = 0.028). Using multivariable logistic regression analysis, the obese group was independently associated with higher MME scores compared to the normal weight/overweight group (p = 0.020). However, BMI was not independently associated with estimated glomerular filtration rate or proteinuria on multivariable analysis. Obesity was independently associated with severe MME in patients with IgAN. Obesity may play an important pathogenetic role in mesangial lesions seen in IgAN.

Adiposity, Physical Function, and Their Associations With Insulin Resistance, Inflammation, and Adipokines in CKD

RATIONALE & OBJECTIVES

Adiposity and physical fitness levels are major drivers of cardiometabolic risk, but these relationships have not been well-characterized in chronic kidney disease (CKD). We examined the associations of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), intrahepatic fat, and physical function with inflammation, insulin resistance, and adipokine levels in patients with CKD.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

Participants with stages 3-5 CKD not receiving maintenance dialysis, followed up at one of 8 clinical sites in the Chronic Renal Insufficiency Cohort (CRIC) Study, and who underwent magnetic resonance imaging of the abdomen at an annual CRIC Study visit (n = 419).

PREDICTORS

VAT volume, SAT volume, intrahepatic fat, body mass index, waist circumference, and time taken to complete the 400-m walk test (physical function).

OUTCOMES

Markers of inflammation (interleukin 1β [IL-1β], IL-6, tumor necrosis factor receptor 1 [TNFR1], and TNFR2), insulin resistance (homeostasis model assessment of insulin resistance), and adipokine levels (adiponectin, total and high molecular weight, resistin, and leptin).

ANALYTICAL APPROACH

Multivariable linear regression of VAT and SAT volume, intrahepatic fat, and physical function with individual markers (log-transformed values), adjusting for relevant covariates.

RESULTS

Mean age of the study population was 64.3 years; 41% were women, and mean estimated glomerular filtration rate was 53.2±14.6 (SD) mL/min/1.73m². More than 85% were overweight or obese, and 40% had diabetes. Higher VAT volume, SAT volume, and liver proton density fat fraction were associated with lower levels of total and high-molecular-weight adiponectin, higher levels of leptin and insulin resistance, and lower high-density lipoprotein cholesterol and higher serum triglyceride levels. A slower 400-m walk time was associated only with higher levels of leptin, total adiponectin, plasma IL-6, and TNFR1 and did not modify the associations between fat measures and cardiometabolic risk factors.

LIMITATIONS

Lack of longitudinal data and dietary details.

CONCLUSIONS

Various measures of adiposity are associated with cardiometabolic risk factors. Physical function was also associated with the cardiometabolic risk factors studied and does not modify associations between fat measures and cardiometabolic risk factors. Longitudinal studies of the relationship between body fat and aerobic fitness with cardiovascular and kidney disease progression are warranted.

Weight-gain induced changes in renal perfusion assessed by contrast-enhanced ultrasound precede increases in urinary protein excretion suggestive of glomerular and tubular injury and normalize after weight-loss in dogs

Early detection of obesity-related glomerulopathy in humans is challenging as it might not be detected by routine biomarkers of kidney function. This study's aim was to use novel kidney biomarkers and contrast-enhanced ultrasound (CEUS) to evaluate the effect of obesity development and weight-loss on kidney function, perfusion, and injury in dogs. Sixteen healthy lean adult beagles were assigned randomly but age-matched to a control group (CG) (n = 8) fed to maintain a lean body weight (BW) for 83 weeks; or to a weight-change group (WCG) (n = 8) fed the same diet to induce obesity (week 0-47), to maintain stable obese weight (week 47-56) and to lose BW (week 56-83). At 8 time points, values of systolic blood pressure (sBP); serum creatinine (sCr); blood urea nitrogen (BUN); serum cystatin C (sCysC); urine protein-to-creatinine ratio (UPC); and urinary biomarkers of glomerular and tubular injury were measured. Glomerular filtration rate (GFR) and renal perfusion using CEUS were assayed (except for week 68). For CEUS, intensity- and time-related parameters representing blood volume and velocity were derived from imaging data, respectively. At 12-22% weight-gain, cortical time-to-peak, representing blood velocity, was shorter in the WCG vs. the CG. After 37% weight-gain, sCysC, UPC, glomerular and tubular biomarkers of injury, urinary immunoglobulin G and urinary neutrophil gelatinase-associated lipocalin, respectively, were higher in the WCG. sBP, sCr, BUN and GFR were not significantly different. After 23% weight-loss, all alterations were attenuated. Early weight-gain in dogs induced renal perfusion changes measured with CEUS, without hyperfiltration, preceding increased urinary protein excretion with potential glomerular and tubular injury. The combined use of routine biomarkers of kidney function, CEUS and site-specific urinary biomarkers might be valuable in assessing kidney health of individuals at risk for obesity-related glomerulopathy in a non-invasive manner.

Metabolic abnormalities, but not obesity per se, associated with chronic kidney disease in a Taiwanese population

BACKGROUND AND AIMS

It is inconclusive whether obesity itself or metabolic abnormalities are linked to chronic kidney disease (CKD). The aim of this study was to examine the association between different subtypes of obesity and metabolic abnormalities with CKD in adults.

METHODS AND RESULTS

This study enrolled 14,983 eligible subjects stratified into metabolically healthy normal weight (MHNW), metabolically healthy overweight (MHOW), metabolically healthy obesity (MHO), metabolically unhealthy normal weight (MUNW), metabolically unhealthy overweight (MUOW), and metabolically unhealthy obesity (MUO) according to body mass index and metabolic syndrome status (ATP-III criteria). The metabolic healthy phenotype was defined as the absence of both metabolic syndrome and any known diabetes, coronary artery disease, stroke, hypertension or dyslipidemia. Early and advanced CKD were defined as eGFR<60, proteinuria, or structural abnormalities as detected by renal sonography. The prevalence of CKD was 2.5, 3.0, 4.0, 10.6, 9.5, and 10.5% in subjects with MHNW, MHOW, MHO, MUNW, MUOW, and MUO, respectively. In the multivariate analysis, the MUNW (OR:2.22, P < 0.001), MUOW (OR:2.22, P < 0.001), and MUO (OR:2.45, P < 0.001) groups were associated with early CKD. For advanced CKD, the OR was 2.56 (P < 0.001), 2.31 (P < 0.001), and 3.49 (P < 0.001) in the MUNW, MUOW, and MUO groups, respectively. The associated risks of early and advanced CKD were not significant in the MHOW and MHO group. MUOW and MUO were associated with higher risk of CKD compared with MHOW and MHO after adjusting other variables.

CONCLUSIONS

Metabolic abnormalities, but neither overweight nor obesity, were associated with a higher risk of CKD in adults.

Effect of laparoscopic sleeve gastrectomy on renal function in obese patients

BACKGROUND

To investigate the clinical efficacy and mechanism of laparoscopic sleeve gastrectomy (LSG) in improving renal function in obese patients.

METHODS

We retrospectively reviewed the anthropometric indices (waist circumference, hip circumference and body mass index (BMI)), renal function indices (serum creatinine, urea and urinary albumin:creatinine ratio (UACR)), serum inflammatory indices (C-reactive protein, interleukin-6 and tumour necrosis factor-α) and an adipose factor (leptin) in 50 patients with obesity (BMI ≥32.5 kg/m² ) who underwent LSG in our hospital from January 2018 to January 2019.

RESULTS

Patients constituted 23 men and 27 women, with an average age of 32.5 ± 8.7 years and BMI of 43.99 ± 8.29 kg/m² . Body weight and BMI 1 month post-operatively were significantly lower than preoperatively (P < 0.05), and the renal function indices serum creatinine, urea and UACR, improved significantly 3 months post-operatively (P < 0.05). C-reactive protein, interleukin-6 and tumour necrosis factor-α levels improved significantly 3 months post-operatively (P < 0.05), while leptin levels decreased significantly 1 month post-operatively (P < 0.05). Six months post-operatively, the remission rates for type 2 diabetes mellitus, sleep apnoea syndrome and hypertension were 83.8%, 92.9% and 88.6%, respectively.

CONCLUSIONS

LSG led to body weight loss and significantly improved serum creatinine, urea and UACR values in patients with obesity, which may be related to changes in adipocytokines and inflammatory factors, post-operatively. LSG is expected to become a new treatment to prevent or treat renal insufficiency caused by obesity.

Chronic kidney disease attenuates the impact of obesity on quality of life

The impact of obesity on health-related quality of life (HRQoL) in chronic kidney disease (CKD) population has not been elucidated, despite the impairment of HRQoL in the obese among general population. We hypothesized that the impact of obesity on HRQoL might be confounded by impaired renal function in CKD population, and that CKD would attenuate the impact of obesity on HRQoL. To compare the impact of obesity on HRQoL according to kidney function, 17,001 subjects from Korea National Health and Nutrition Examination Survey (2008–2011) were categorized by estimated glomerular filtration rate (eGFR), as follows: group 1, eGFR ≥ 90 mL/min/1.73 m²; group 2, eGFR of 60–89 mL/min/1.73 m²; group 3, eGFR < 60 mL/min/1.73 m². The association between obesity parameters (body mass index, waist circumference and, truncal fat mass) and HRQoL parameters (EQ-5D index and EQ-VAS) were cross-sectionally analyzed. Despite robust correlations between obesity parameters and low EQ-5D index or EQ-VAS in general population, no significant association was observed in group 3 population. Impact of obesity on HRQoL in CKD population was only limitedly observed in the mobility domain of EQ-5D, as mobility limitation was associated with increased body mass index or waist circumference regardless of kidney function. Therefore, the impact of obesity on HRQoL seems significantly attenuated in CKD population, suggesting that the risk of obesity should not be over-estimated in patients with CKD, especially with respect to HRQoL.

Bariatric surgery and kidney disease outcomes in severely obese youth

Bariatric surgery, an emerging treatment for severely obese youth with and without T2D, provides marked improvement in insulin resistance, beta-cell function, and central adiposity. Further, preliminary data suggest that bariatric surgery also results in significant improvement in markers of obesity-related nephropathy and DKD, beyond that which can be achieved with current medical interventions. Yet, the mechanisms whereby bariatric surgery attenuates kidney disease remain unclear. This review summarizes the data on the effects of bariatric surgery on obesity-related nephropathy and DKD in youth with and without T2D, in addition to potential mechanisms underlying the nephroprotective effects of weight loss surgery and how these may differ in Roux-en-Y gastric bypass vs. vertical sleeve gastrectomy. Finally, we discuss potential future non-surgical therapies to mitigate kidney disease.

Kidney function in minority children and adolescents with metabolically healthy and unhealthy obesity

Metabolic syndrome and/or body mass index (BMI) ≥40 kg/m² are risk factors for kidney function decline in the general population. To compare creatinine (Cr), estimated glomerular filtration rate (eGFR) and blood urea nitrogen (BUN) between minority children and adolescents with metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO), a chart review was conducted on subjects aged 4 to 20 years with BMI ≥95^th percentile from July 2014 to April 2017. They were stratified into MHO and MUO groups. Cr, eGFR and BUN were studied. Total n = 277: MHO n = 105 vs MUO n = 172. Cr was higher and BUN was lower in MUO whereas eGFR did not differ between the groups. Using general linear model, we found that metabolic status predicted BUN (P = .009) but not Cr or eGFR. When age, sex and Tanner stage matched, BUN, Cr and eGFR were similar between the groups. Higher BUN in MHO could be due to higher dietary protein intake. Subjects were divided into BMI ≥40 vs <40 kg/m² , BUN and eGFR were not different. A trend towards higher Cr in those with BMI ≥40 kg/m² (P = .054) was found; the group being older and taller. After age and height matching, all outcomes were not different. Higher Cr was found in those with elevated blood pressures vs the MHO (P = .047). Those with diastolic blood pressure (DBP) ≥90^th percentile had higher Cr than those with systolic blood pressure ≥90^th percentile (P = .017). Children and adolescents with MUO, and those with BMI ≥40 kg/m² did not appear to have early diminished kidney function. Higher Cr, although in normal range, occurred in those with abnormal DBP.

Leptin in Tumor Microenvironment

Leptin is a hormone that plays a major role as mediator of long-term regulation of energy balance, suppressing food intake, and stimulating weight loss. More recently, important physiological roles other than controlling appetite and energy expenditure have been suggested for leptin, including neuroendocrine, reparative, reproductive, and immune functions. These emerging peripheral roles let hypothesize that leptin can modulate also cancer progression. Indeed, many studies have demonstrated that elevated chronic serum concentrations of leptin, frequently seen in obese subjects, represent a stimulatory signal for tumor growth. Current knowledge indicates that also different non-tumoral cells resident in tumor microenvironment may respond to leptin creating a favorable soil for cancer cells. In addition, leptin is produced also within the tumor microenvironment creating the possibility for paracrine and autocrine action. In this review, we describe the main mechanisms that regulate peripheral leptin availability and how leptin can shape tumor microenvironment.

Glomerular Collagen Deposition and Lipocalin-2 Expression Are Early Signs of Renal Injury in Prediabetic Obese Rats

Feeding rats with high-fat diet (HFD) with a single streptozotocin (STZ) injection induced obesity, slightly elevated fasting blood glucose and impaired glucose and insulin tolerance, and caused cardiac hypertrophy and mild diastolic dysfunction as published before by Koncsos et al. in 2016. Here we aimed to explore the renal consequences in the same groups of rats. Male Long-Evans rats were fed normal chow (CON; n = 9) or HFD containing 40% lard and were administered STZ at 20 mg/kg (i.p.) at week four (prediabetic rats, PRED, n = 9). At week 21 blood and urine samples were taken and kidney and liver samples were collected for histology, immunohistochemistry and for analysis of gene expression. HFD and STZ increased body weight and visceral adiposity and plasma leptin concentration. Despite hyperleptinemia, plasma C-reactive protein concentration decreased in PRED rats. Immunohistochemistry revealed elevated collagen IV protein expression in the glomeruli, and Lcn2 mRNA expression increased, while Il-1β mRNA expression decreased in both the renal cortex and medulla in PRED vs. CON rats. Kidney histology, urinary protein excretion, plasma creatinine, glomerular Feret diameter, desmin protein expression, and cortical and medullary mRNA expression of TGF-β1, Nrf2, and PPARγ were similar in CON and PRED rats. Reduced AMPKα phosphorylation of the autophagy regulator Akt was the first sign of liver damage, while plasma lipid and liver enzyme concentrations were similar. In conclusion, glomerular collagen deposition and increased lipocalin-2 expression were the early signs of kidney injury, while most biomarkers of inflammation, oxidative stress and fibrosis were negative in the kidneys of obese, prediabetic rats with mild heart and liver injury.

Role of ADAM17 in kidney disease

It is known that the renin-angiotensin system plays a major role in the pathophysiology of cardiovascular disease and renal injury. Within the renin-angiotensin system, angiotensin-converting enzyme 2 (ACE2) cleaves ANG II to generate ANG(1–7) peptide, which counteracts the adverse effects of ANG II accumulation. ACE2 can undergo cleavage or shedding to release the catalytically active ectodomain into the circulation by a disintegrin and metalloprotease (ADAM)17, also known as TNF-α-converting enzyme. ADAM17 is involved in many pathological processes such as cancer, inflammatory diseases, neurological diseases, cardiovascular diseases, atherosclerosis, diabetes, and hypertension. Clinical and experimental studies have shown that ADAM17 is involved in chronic kidney disease (CKD) with a proinflammatory and profibrotic role, suggesting that it could be an important mediator of CKD progression. ADAM17 inhibition attenuates fibrosis and inflammation, suggesting that its inhibition may be a possible new valuable therapeutic tool in fibrotic kidney disease treatment. In addition, in renal disease, some experimental studies have demonstrated that ADAM17 is differently expressed in the kidney. Thus, ADAM17 is highly expressed in distal renal tubules and increased in the whole kidney in diabetic models. In this article, we will review the role of ADAM17 under physiological and pathological conditions. We will mainly focus on the importance of ADAM17 in the context of CKD.

Biomarkers of Atrial Fibrillation in Metabolic Syndrome

Whether the increased atrial fibrillation (AF) risk in metabolic syndrome (MetS) patients is due to the syndrome as a whole or simply the sum of the risks of its individual component parts is still obscure. These two clinical entities share many pathophysiological links and thus distinction between a casual observation and a significant association is difficult. Biomarkers associated with pathogenesis of AF in the context of MetS have the ability to refine future risk prediction. In the present review we identify circulating substances that could be regarded as potential biomarkers for prediction of incident AF, or of cardiovascular events in the setting of AF in patients with MetS. Cardiac myocyte injury and stress markers (troponin and natriuretic peptides), markers of renal function (glomeral filtration rate, cystatin-C), and inflammation markers/mediators (interleukin- 6, CRP) are promising biomarkers of patients with AF and MetS.

Effects of metreleptin on proteinuria in patients with lipodystrophy

CONTEXT

Patients with lipodystrophy have high prevalence of proteinuria.

OBJECTIVE

To assess kidney disease in patients with generalized (GLD) versus partial lipodystrophy (PLD), and effects metreleptin on proteinuria in patients with lipodystrophy.

DESIGN/SETTING/PATIENTS/INTERVENTION

Prospective, open-label studies of metreleptin treatment in patients with GLD and PLD at the National Institutes of Health, Bethesda, MD.

OUTCOME MEASURES

24-hour urinary albumin and protein excretion rates, estimated glomerular filtration rate (eGFR), and creatinine clearance (CrCl) were measured at baseline and during up to 24 months of metreleptin treatment. Patients with increases in medications affecting outcome measures were excluded.

RESULTS

At baseline, patients with GLD had significantly greater albuminuria, proteinuria, eGFR, and CrCl compared to patients with PLD. CrCl was above the normal range in 69% of patients with GLD, and 39% with PLD (P=0.02). With up to 24 months of metreleptin treatment, there were significant reductions in albuminuria and proteinuria in patients with GLD, but not in those with PLD. No changes in eGFR or CrCl were observed in patients with GLD or PLD during metreleptin treatment.

CONCLUSIONS

Patients with GLD had significantly greater proteinuria than those with PLD, which improved with metreleptin treatment. The mechanisms leading to proteinuria in lipodystrophy and improvements in proteinuria with metreleptin are not clear. Hyperfiltration was also more common in GLD versus PLD but did not change with metreleptin.

Atypical cannabinoid ligands O-1602 and O-1918 administered chronically in diet-induced obesity

Atypical cannabinoid compounds O-1602 and O-1918 are ligands for the putative cannabinoid receptors G protein-coupled receptor 55 and G protein-coupled receptor 18. The role of O-1602 and O-1918 in attenuating obesity and obesity-related pathologies is unknown. Therefore, we aimed to determine the role that either compound had on body weight and body composition, renal and hepatic function in diet-induced obesity. Male Sprague-Dawley rats were fed a high-fat diet (40% digestible energy from lipids) or a standard chow diet for 10 weeks. In a separate cohort, male Sprague-Dawley rats were fed a high-fat diet for 9 weeks and then injected daily with 5 mg/kg O-1602, 1 mg/kg O-1918 or vehicle (0.9% saline/0.75% Tween 80) for a further 6 weeks. Our data demonstrated that high-fat feeding upregulates whole kidney G protein receptor 55 expression. In diet-induced obesity, we also demonstrated O-1602 reduces body weight, body fat and improves albuminuria. Despite this, treatment with O-1602 resulted in gross morphological changes in the liver and kidney. Treatment with O-1918 improved albuminuria, but did not alter body weight or fat composition. In addition, treatment with O-1918 also upregulated circulation of pro-inflammatory cytokines including IL-1α, IL-2, IL-17α, IL-18 and RANTES as well as plasma AST. Thus O-1602 and O-1918 appear not to be suitable treatments for obesity and related comorbidities, due to their effects on organ morphology and pro-inflammatory signaling in obesity.

Childhood Obesity and the Metabolic Syndrome

Obesity is a leading cause of chronic kidney disease. Children with severe obesity have an increased prevalence of early kidney abnormalities and are at high risk to develop kidney failure in adulthood. The pathophysiology of obesity-related kidney disease is incompletely understood, although the postulated mechanisms of kidney injury include hyperfiltration, adipokine dysregulation, and lipotoxic injury. An improved understanding of the long-term effects of obesity on kidney health is essential treat the growing epidemic of obesity-related kidney disease. The purpose of this article is to review the epidemiology, pathophysiology, clinical features, and management of obesity-related kidney disease in children and adolescents.

The conundrum of patients with obesity, exercise intolerance, elevated ventricular filling pressures and a measured ejection fraction in the normal range

Patients with obesity, a reduced exercise capacity, increased cardiac filling pressures and a measured left ventricular ejection fraction in the normal range do not have a homogeneous disorder, but instead, exhibit one of three phenotypes. First, many obese people exhibit sodium retention, plasma volume expansion and cardiac enlargement, and some are likely to have heart failure that is related to hypervolaemia, even though cardiac index and circulating levels of natriuretic peptides are not meaningfully increased. Second, in some middle-aged men and women (particularly those with minimal co-morbidities), levels of natriuretic peptides increase markedly and can lower systemic vascular resistance, thus leading to high-output heart failure (HOHF) and glomerular hyperfiltration. Third, older obese people, particularly women with multiple co-morbidities, exhibit the syndrome of heart failure with a preserved ejection fraction (HFpEF). Despite degrees of plasma volume expansion similar to HOHF, these patients exhibit only modestly increased ventricular dimensions and circulating levels of natriuretic peptides (despite a high prevalence of atrial fibrillation), and glomerular function is characteristically impaired. A conceptual framework is proposed to distinguish among the three phenotypes seen in obese patients with exercise intolerance, increased ventricular filling pressures and a measured left ventricular ejection fraction in the normal range, since they may respond differently to therapeutic interventions. Efforts are needed to enhance the recognition of heart failure in obese people and to ensure that clinical trials that are designed to study patients with HFpEF actually enrol those who have the disease.

The Relationship Between Increased Ratio of Visceral-to-Subcutaneous Fat Area and Renal Outcome in Chinese Adults With Type 2 Diabetes and Diabetic Kidney Disease

OBJECTIVE

Abdominal obesity is a risk factor of diabetes and hypertension. The aim of this study was to investigate the association between excessive abdominal fat and renal outcomes in patients with type 2 diabetes and diabetic kidney disease.

METHODS

Thirty-five patients with type 2 diabetes and diabetic kidney disease who were followed up on for at least 1 year were enrolled. Visceral fat area and subcutaneous fat area were assessed by computed tomography to evaluate the degree of abdominal fat. Patients were divided into 2 groups. Patients in group 1 had a ratio of visceral fat area to subcutaneous fat area (V/S ratio) <0.70 (n=16), and those in group 2 had a V/S ratio ≥0.70 (n=19) according to the second quartile. Renal outcome was defined as end-stage renal disease and initiation of renal replacement therapy.

RESULTS

At baseline, patients with a high V/S ratio had higher levels of triglycerides (p=0.060) and C-reactive protein (p=0.028), but lower high-density lipoprotein cholesterol levels (p=0.006). Strong correlations between V/S ratio and C-reactive protein (r=0.521, p=0.015) and high-density lipoprotein cholesterol (r=-0.576, p<0.001) were observed. Univariate Cox regression indicated the higher the V/S ratio, the greater the risk for a poor renal outcome (hazard ratio, 3.536; 95% confidence interval, 1.140 to 10.960; p=0.029). However, multivariate Cox analysis demonstrated that a higher V/S ratio was not an independent risk factor for progression to end-stage renal disease (hazard ratio, 2.212; 95% confidence interval, 0.543 to 9.005; p=0.268) when adjustments were made for important clinical variables.

CONCLUSION

The V/S ratio was positively correlated with C-reactive protein and high-density lipoprotein cholesterol. The higher V/S ratio was associated with a greater risk for progression to end-stage renal disease, although it did not emerge as an independent predictor of diabetic kidney disease progression.

The complex effects of adipokines in the patients with kidney disease

Kidney diseases are categorized as the highest prevalent ones with worldwide noticeable incidence. They cause accelerated cardiovascular diseases and noticeable mortalities. Adipose tissue and its messengers, adipokines, are reported to have the highest relationship with end-stage renal diseases or chronic kidney diseases. Over recent years, with shifting of scientists’ mindset from a simple overview of adipose tissue as a fat store to the complex paradigm of this issue as a multipotential secretory organ, the importance of studies on this tissue has emerged.

Transgenerational programming of nephron deficits and hypertension

Exposure to a sub-optimal environment in the womb can result in poor fetal growth and impair the normal development of organs. The kidney, specifically the process of nephrogenesis, has been shown to be impacted by many common pregnancy exposures including an inadequate diet, poor placental function, maternal stress as well as maternal smoking and alcohol consumption. This can result in offspring being born with a reduced nephron endowment, which places these individuals at increased risk of hypertension and chronic kidney disease (CKD). Of recent interest is whether this disease risk can be passed on to subsequent generations and, if so, what are the mechanisms and pathways involved. In this review, we highlight the growing body of evidence that a low birth weight and hypertension, which are both major risk factors for cardiovascular and CKD, can be transmitted across generations. However, as yet there is little data as to whether a low nephron endowment contributes to this disease transmission. The emerging data suggests transmission can occur both through both the maternal and paternal lines, which likely involves epigenetic mechanisms such chromatin remodelling (DNA methylation and histone modification) and non-coding RNA modifications. In addition, females who were born small and/or have a low nephron endowment are at an increased risk for pregnancy complications, which can influence the growth and development of the next generation. Future animal studies in this area should include examining nephron endowment across multiple generations and determining adult renal function. Clinically, long term follow-up studies of large birth cohorts need to be undertaken to more clearly determine the impact a sub-optimal environment in one generation has on the health outcomes in the second, and subsequent, generation.

Long-term risk for end-stage kidney disease and death in a large population-based cohort

Knowledge of metabolic risk factors for end-stage kidney disease (ESKD) in the general population is limited when considering the competing event death in risk analysis. The aim of our prospective observational study was to investigate how blood pressure and metabolic factors might influence the risks for ESKD and death before ESKD in a large Austrian population-based cohort with long-term follow-up. 177,255 participants (53.8% women; mean age 42.5 years) were recruited between 1988 and 2005 and linked to the Austrian Dialysis and Transplant Registry and the National Mortality Registry. Over a mean follow-up of 16 years 358 participants reached ESKD and 19,512 participants died. Applying fully adjusted cause-specific Cox proportional hazards models elevated fasting blood glucose, hypertension, hypertrigylceridemia and hypercholesterolemia were associated with a higher relative risk for ESKD than for death before ESKD, whereas elevated γ-glutamyltransferase was associated with an increased relative risk of death but not ESKD. Results were similar using continuous or categorical exposure variable measures in the general cohort but differed in selected high-risk populations. These findings might help improve the design of renal risk factor modification trials and kidney disease awareness and prevention programs in the general population, which may ultimately decrease the burden of ESKD.

Leptin in inflammation and autoimmunity

After its discovery as a key controller of metabolic function, leptin has been later extensively implicated in additional functions including important modulatory activities on the innate and adaptive immune response. This review analyzes the known implications of leptin in multiple inflammatory conditions, including autoimmune diseases, and how this knowledge could be instrumental in the design of leptin-based manipulation strategies to help restoration of abnormal immune responses.

Immunologic and endocrine functions of adipose tissue: implications for kidney disease

Excess adiposity can induce adverse sequelae in multiple cell types and organ systems. The transition from the lean to the obese state is characterized by fundamental cellular changes at the level of the adipocyte. These changes affect the local microenvironment within the respective adipose tissue but can also affect nonadipose systems. Adipocytes within fat pads respond to chronic nutrient excess through hyperplasia or hypertrophy, which can differentially affect interorgan crosstalk between various adipose depots and other organs. This crosstalk is dependent on the unique ability of the adipocyte to coordinate metabolic adjustments throughout the body and to integrate responses to maintain metabolic homeostasis. These actions occur through the release of free fatty acids and metabolites during times of energy need - a process that is altered in the obese state. In addition, adipocytes release a wide array of signalling molecules, such as sphingolipids, as well as inflammatory and hormonal factors (adipokines) that are critical for interorgan crosstalk. The interactions of adipose tissue with the kidney - referred to as the adipo-renal axis - are important for normal kidney function as well as the response of the kidney to injury. Here, we discuss the mechanistic basis of this interorgan crosstalk, which clearly has great therapeutic potential given the increasing rates of chronic kidney disease secondary to obesity and type 2 diabetes mellitus.

[Obesity-related glomerulopathy: Mechanisms of development, clinical course]

Obesity and overweight are recognized as epidemics of non-communicable diseases in the 21st century. The kidneys are a target organ for obesity, damage to which is considered to be an independent risk factor for the development of renal failure. Obesity-related glomerulopathy (OGP) is one of the types of renal injury in obesity, which is characterized by the development of proteinuria in patients with a body mass index (BMI) of >30 kg/m2 in the absence of other causes of kidney damage. The pathogenesis of OGP is multifactorial. It is associated with intrarenal hemodynamic disorders - the development of renal hyperfiltration, the damaging action of adipose tissue hormones (hyperleptinemia, activation of the renin-angiotensin-aldosterone system, decreased production of adiponectin); with ectopic lipid accumulation in the kidney. The morphological pattern of OGP is characterized by a low glomerular density (oligonephronia) that leads to glomerular and tubular hypertrophy; by the development of perihilar focal segmental glomerulosclerosis (FSGS), obvious podocyte damages, and the development of a fatty kidney. The clinical picture of OGP is characterized by the slow and gradual development of albuminuria, not exceeding Stage A3 (300-1999 mg/day). Approximately one-third of patients develop partial nephrotic syndrome with massive proteinuria, but without edema and hypoproteinemia. Complete nephrotic syndrome is observed in not more than 6% of patients with OGP. In the course of the disease, 50% of patients develop hypertension and more than 80% do dyslipidemia. Stages IV-V chronic kidney disease may develop 20-30 years after the disease occurs.