Elevated serum leptin, adiponectin and leptin to adiponectin ratio is associated with chronic kidney disease in Asian adults

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.

Identification of risk factors and development of a predictive model for chronic kidney disease in patients with obesity: a four-year cohort study

OBJECTIVE

The sneaky onset and dismal prognosis of chronic kidney disease (CKD) make it an important public health issue. Obesity-related kidney illness has garnered more attention in recent times. Establishing and validating a risk prediction model for chronic renal illness in overweight or obese adults was the goal of this investigation.

METHODS

Data from the China Health and Retirement Longitudinal Study were used for analysis. The definition of CKD was reduced renal function (eGFR < 60 mL/min/1.73 m²), while overweight and obesity were characterized through a body mass index exceeding 24 kg/m². The dataset was divided into derivation and validation cohorts using a 7:3 ratio. With respect to the derivation cohort, we constructed a prediction model using LASSO analysis and multivariate logistic regression. The model's performance was evaluated using Hosmer-Lemeshow tests, calibration curves, decision curve analysis, and receiver operating characteristic (ROC) curves. The validation cohort's model was subjected to additional assessment.

RESULTS

The study was based on survey data from 2011 to 2015 and comprised 3246 individuals who were overweight or obese, with 2274 being part of the derivation cohort and 972 being part of the validation cohort. The research constructed a prediction model that included age, sex, fasting blood glucose, glycated hemoglobin, triglyceride, hypertension, and BMI. The validation cohort's area under the ROC curve was 0.812 (95% CI = 0.763, 0.859) while the derivation cohort's was 0.789 (95% CI = 0.754, 0.831). Hosmer-Lemeshow tests were utilized to evaluate the model's accuracy in the validation and derivation cohorts (P = 0.681 and 0.547, respectively). The calibration curve showed a high level of consistency between the actual observations and the projected outcomes. According to decision curve analysis, the model offered significant net advantages.

CONCLUSIONS

The forecasting model established in this research has predictive value for CKD in patients with overweight or obesity. These findings could help doctors conduct early detection and intervention in clinical practice and further improve patient prognosis.

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

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

Obesity-related hypertension and chronic kidney disease: from evaluation to management

With the recent obesity pandemic, obesity-related hypertension and its complications (e.g., heart failure, coronary disease, and chronic kidney disease [CKD]) are gaining attention in clinical and research fields. Obesity-related hypertension frequently precedes the onset of CKD and aggravates its progression. In this review, we discuss the role of visceral fat in the pathophysiology of obesity-related hypertension and the potential therapeutic strategies for its prevention and management. Various factors, including the sympathetic nervous system, renin-angiotensin-aldosterone system, and inflammatory pathways, are intricately involved in the pathogenesis of obesity-related hypertension. These factors individually and jointly contribute to the development of hypertension (usually sodium-sensitive or resistant hypertension) and, ultimately, to the progression of CKD. From a clinical standpoint, a decline in renal function in advanced CKD further makes blood pressure control challenging since only a few options are available for blood pressure-lowering medications. Proactive lifestyle modification, pharmacological treatment for obesity, and bariatric surgery can be considered for obesity control and management. Furthermore, intensive blood pressure control is required to prevent and halt the development and progression of CKD.

Adiponectin-leptin ratio as a marker of cardio-metabolic risk in Indian children and youth with type 1 diabetes

OBJECTIVES

Adiponectin/leptin ratio (ALR) is a promising novel marker of cardio-metabolic risk in patients with metabolic syndrome. Our aim was to study the association of adiponectin-leptin ratio with markers of obesity and adiposity and also to assess its usefulness as a marker of increased cardiometabolic risk (CMR) in Indian children and youth with type 1 diabetes mellitus.

METHODS

This observational study included 79 children and youth with type 1 diabetes (T1DM) (10-21 years) having disease duration>6 months. Demographic data and laboratory findings were obtained from patients' records. Patients with ALR<1 were categorised as having increased CMR and those with ALR>1 were categorised as having no CMR.

RESULTS

ALR showed a significant negative correlation with body mass index (BMI), waist and hip circumference and body fat percentage (p<0.05). Body fat percentage was the single most important predictor of ALR. Children and youth with increased CMR had higher weight, BMI, waist and hip circumferences and body fat percentage as compared to those with no CMR (p<0.05). In T1DM children with dyslipidemia, ALR was significantly lower as compared to those without dyslipidemia (p<0.05).

CONCLUSIONS

ALR may be a useful marker for adiposity and increased cardiometabolic risk in Indian children and youth with type 1 diabetes mellitus.

The liver-kidney axis: Is serum leptin a potential link in non-alcoholic fatty liver disease-associated chronic kidney disease?

BACKGROUND AND STUDY AIMS

Non-alcoholic fatty liver disease (NAFLD) is an independent risk factor for chronic kidney disease (CKD). Previous studies argued that leptin levels increase significantly with the progression of CKD. But the association between leptin and CKD has not been investigated in patients with NAFLD. Therefore, we conducted this study to establish whether increased leptin level is associated with CKD in NAFLD patients.

PATIENTS AND METHODS

In our prospective study with a follow up period of six months thirty-five teetotaller biopsy-proven NAFLD patients were divided as groups with mild, versus advanced, fibrosis. Liver fibrosis was also assessed with Fibroscan. Serum leptin levels were measured by radioimmunoassay. For insulin resistance we used the homeostasis model assessment method (HOMA-IR). For the kidney function, we used the abbreviated formula Modification of Diet in Renal Disease (MDRD) formula, which estimates GFR. For statistical analysis, Student's-t test, Mann-Whitney test, linear regression-binary logistic regression analyses and the ROC curve analysis were used.

RESULTS

Advanced fibrosis and increased HOMA-IR were risk factors for decreased eGFR. Leptin correlated inversely with advanced fibrosis (p: 0.03) and low leptin was a risk factor for CKD (p: 0.02). In ROC curve analysis, advanced fibrosis and low leptin were risk factors for decreased eGFR (p: 0.007 and 0.004, respectively). Low leptin level was dependently associated with decreased eGFR.

CONCLUSION

Advanced fibrosis in NAFLD patients is a risk factor for CKD. Leptin correlated inversely with advanced fibrosis. Unlike the previous studies, which were not performed in NAFLD patients, we found decreased leptin in NAFLD patients with decreased eGFR. Low leptin level was found to be a dependent predictor for differentiating NAFLD patients with high risk for CKD.

Obesity and renal disease: Benefits of bariatric surgery

The prevalence of obesity, a preventable and reversible condition with a high impact on health, continues to rise, especially after the COVID-19 pandemic. Severe overweight is well recognized as a risk factor for diabetes and hypertension, among other conditions, that may increase cardiovascular risk. Obesity has grown simultaneously with a rise in the prevalence of chronic kidney disease, and a pathophysiological link has been established, which explains its role in generating the conditions to facilitate the emergence and maximize the impact of the risk factors of chronic kidney disease and its progression to more advanced stages. Knowing the mechanisms involved and having different tools to reverse the overweight and its consequences, bariatric surgery has arisen as a useful and efficient method, complementary or alternative to others, such as lifestyle changes and/or pharmacotherapy. In a detailed review, the mechanisms involved in the renal consequences of obesity, the impact on risk factors, and the potential benefit of bariatric surgery at different stages of the disease and its progression are exposed and analyzed. Although the observational evidence supports the value of bariatric surgery as a renoprotective measure in individuals with obesity, diabetic or not, randomized studies are expected to establish evidence-based recommendations that demonstrate its positive risk-benefit balance as a complementary or alternative therapeutic tool.

New Insights into Adiponectin and Leptin Roles in Chronic Kidney Disease

Chronic kidney disease (CKD) is commonly associated with a high burden of comorbidities and poor clinical outcomes. Malnutrition–inflammation–atherosclerosis syndrome is common in the more severe stages of CKD, suggesting a close interplay for these three comorbid conditions. Both malnutrition and obesity are associated with a disturbed adipokine profile and inflammation, contributing to a higher risk of cardiovascular disease (CVD) events. Adiponectin and leptin have important roles in carbohydrate and lipid metabolism, and in the inflammatory process. The effects of adiponectin and leptin alterations in CKD, which are usually increased, and their association with the different comorbidities found in CKD, will be focused on to understand their crosstalk with the risk of CVD events. Nonetheless, although adiponectin and leptin contribute to a higher risk of CVD events, further studies are warranted to fully clarify their roles, especially when different comorbidities exist.

Adiponectin and Leptin as Biomarkers of Disease Activity and Metabolic Disorders in Rheumatoid Arthritis Patients

Background

Rheumatoid arthritis (RA) is an autoimmune disease, characterized by inflammation of multiple joints, resulting in irreversible cartilage and bone destruction. Chronic disease activity may be associated with metabolic disorders and premature atherosclerosis. Adipokines are involved not only in metabolism regulation, but also in inflammatory and immune response.

Aim

This study is designed to explore relationships between adipokines (adiponectin, leptin) and metabolic parameters, as well as disease activity, in patients with chronic RA.

Methods

This cross-sectional study enrolled 109 patients with RA. The clinical assessment was performed including tender and swollen joint counts, Disease Activity Score 28 (DAS28), body mass index (BMI). The following laboratory parameters were performed: erythrocyte sedimentation rate, C-reactive protein, glucose, lipid profile, creatinine. Serum levels of adiponectin and leptin were assessed by enzyme-linked immunosorbent assay (ELISA).

Results

The mean adiponectin and leptin serum concentrations remained within normal ranges. Both, adiponectin and leptin levels were not associated with current disease activity markers (clinical and laboratory), and type of treatment. Significant relationships were found between adipokines and metabolic parameters, as well as with coexistent conditions and RA characteristics. Higher leptin levels were noticed in patients with hypertension. In the multiple linear regression analysis, correlations were confirmed. Adiponectin was positively correlated with HDL-C (b = 0.37, p < 0.001), age (b = 0.39, p< 0.001), and negatively with glucose (b = -0.17, p = 0.03). Leptin was positively correlated with BMI (b = 0.58, p < 0.001), and negatively with estimated glomerular filtration rate (eGFR) (b = -0.30, p < 0.001).

Conclusion

The results of this study show the value of adipokines as indicators of metabolic disorders, rather than inflammatory markers in patients with chronic RA, treated with immunosuppressive or biological drugs. High leptin level may indicate poor prognostic factors, kidney and cardiovascular complications. Adiponectin seems to be protective against metabolic disorders in chronic RA.

Genetically predicted adiponectin causally reduces the risk of chronic kidney disease, a bilateral and multivariable mendelian randomization study

Background: It is not clarified whether the elevation of adiponectin is the results of kidney damage, or the cause of kidney function injury. To explore the causal association of adiponectin on estimated glomerular filtration rate (eGFR) and chronic kidney disease (CKD), this study was performed.

Materials and methods: The genetic association of adiponectin were retrieved from one genome-wide association studies with 39,883 participants. The summary-level statistics regarding the eGFR (133,413 participants) and CKD (12,385 CKD cases and 104,780 controls) were retrieved from the CKDGen consortium in the European ancestry. Single-variable Mendelian randomization (MR), bilateral and multivariable MR analyses were used to verify the causal association between adiponectin, eGFR, and CKD.

Results: Genetically predicted adiponectin reduces the risk of CKD (OR = 0.71, 95% CI = 0.57–0.89, p = 0.002) and increases the eGFR (β = 0.014, 95% CI = 0.001–0.026, p = 0.034) by the inverse variance weighting (IVW) estimator. These findings remain consistent in the sensitivity analyses. No heterogeneity and pleiotropy were detected in this study (P for MR-Egger 0.617, P for global test &gt; 0.05, and P for Cochran’s Q statistics = 0.617). The bilateral MR identified no causal association of CKD on adiponectin (OR = 1.01, 95% CI = 0.96–1.07, p = 0.658), nor did it support the association of eGFR on adiponectin (OR = 0.86, 95% CI = 0.68–1.09, p = 0.207) by the IVW estimator. All the sensitivity analyses reported similar findings (p &gt; 0.05). Additionally, after adjusting for cigarette consumption, alcohol consumption, body mass index, low density lipoprotein, and total cholesterol, the ORs for CKD are 0.70 (95% CI = 0.55–0.90, p = 0.005), 0.75 (95% CI = 0.58–0.97, p = 0.027), 0.82 (95% CI = 0.68–0.99, p = 0.039), 0.74 (95% CI = 0.59–0.93, p = 0.011), and 0.79 (95% CI = 0.61–0.95, p = 0.018), respectively.

Conclusion: Using genetic data, this study provides novel causal evidence that adiponectin can protect the kidney function and further reduce the risk of CKD.

Serum concentrations of leptin and adiponectin in dogs with chronic kidney disease

BACKGROUND

An imbalance in adipokines is associated with the progression of chronic kidney disease (CKD) in humans. However, alterations in adipokines in dogs with CKD remain unclear.

OBJECTIVES

To examine whether adipokine concentrations in serum differ between healthy dogs and dogs with CKD and to determine the correlation between serum adipokine concentrations and CKD severity in dogs.

ANIMALS

Twenty dogs with CKD and 10 healthy dogs.

METHODS

In this cross-sectional study, serum concentrations of leptin, adiponectin, interleukin (IL)-6, IL-10, IL-18, and tumor necrosis factor (TNF)-α were measured in healthy dogs and dogs with CKD, which were classified according to the International Renal Interest Society guidelines.

RESULTS

Serum leptin concentrations were positively correlated with systolic arterial blood pressure (r = .41), creatinine concentrations (r = .39), and symmetric dimethylarginine concentrations (r = .73). Serum adiponectin concentrations (median [range]) in CKD dogs with borderline or non-proteinuric (20.25 [14.9-45.8] ng/mL) were significantly higher than those in proteinuric CKD dogs (13.95 [6.4-22.1] ng/mL; P = .01). Serum IL-6 (median [range]; 43.27 [24.30-537.30] vs 25.63 [6.83-61.03] pg/mL; P = .02), IL-18 (median [range]; 25.98 [11.52-280.55] vs 10.77 [3.53-38.45] pg/mL; P = .01), and TNF-α (median [range]) concentrations (11.44 [8.54-38.45] vs 6.105 [3.97-30.68] pg/mL; P = .02) were significantly different between proteinuric and borderline or non-proteinuric CKD dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

leptin and adiponectin concentrations in serum might be associated with severity of CKD and proteinuria in dogs with CKD, respectively.

Pro-Inflammatory Profile of Adipokines in Obesity Contributes to Pathogenesis, Nutritional Disorders, and Cardiovascular Risk in Chronic Kidney Disease

Obesity is a disease which leads to the development of many other disorders. Excessive accumulation of lipids in adipose tissue (AT) leads to metabolic changes, including hypertrophy of adipocytes, macrophage migration, changes in the composition of immune cells, and impaired secretion of adipokines. Adipokines are cytokines produced by AT and greatly influence human health. Obesity and the pro-inflammatory profile of adipokines lead to the development of chronic kidney disease (CKD) through different mechanisms. In obesity and adipokine profile, there are gender differences that characterize the male gender as more susceptible to metabolic disorders accompanying obesity, including impaired renal function. The relationship between impaired adipokine secretion and renal disease is two-sided. In the developed CKD, the concentration of adipokines in the serum is additionally disturbed due to their insufficient excretion by the excretory system caused by renal pathology. Increased levels of adipokines affect the nutritional status and cardiovascular risk (CVR) of patients with CKD. This article aims to systematize the current knowledge on the influence of obesity, AT, and adipokine secretion disorders on the pathogenesis of CKD and their influence on nutritional status and CVR in patients with CKD.

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.

The associations of leptin and adiponectin with the metabolic syndrome in an Indonesian and a Dutch population

BACKGROUND AND AIMS

At the same BMI, Asian populations develop cardiometabolic complications earlier than Western populations. We hypothesized that a different secretion of the adipocyte-derived hormones leptin and adiponectin plays a role and investigated the associations of the two hormones with the metabolic syndrome (MetS) in an Indonesian and a Dutch population.

METHODS AND RESULTS

We performed cross-sectional analyses of the Netherlands Epidemiology of Obesity Study (n = 6602) and the SUGAR Scientific Programme Indonesia-Netherlands Study (n = 1461). We examined sex-stratified associations of leptin and adiponectin with MetS, using multivariate logistic regression including adjustment for total body fat. The mean (SD) leptin (mcg/L) were 4.7 (6.0) in Indonesian men, 18.6 (12.0) in Indonesian women, 9.1 (7.7) in Dutch men, and 23.4 (17.4) in Dutch women. The mean (SD) adiponectin (mg/L) were 5.7 (5.4), 7.5 (7.1), 6.6 (3.3), and 11.3 (4.9), respectively. Within the same BMI category, leptin concentrations were similar in the two populations, whereas adiponectin was lower in the Indonesian population. Per SD of leptin, adjusted prevalence odds ratios (ORs, 95%CI) of MetS were 0.9 (0.6-1.2) in Indonesian men, 1.1 (0.9-1.4) in Indonesian women, 2.2 (1.6-2.8) in Dutch men, and 1.2 (1.0-1.5) in Dutch women. Per SD of adiponectin, the ORs were 0.9 (0.7-1.2), 0.8 (0.7-1.0), 0.6 (0.6-0.8), and 0.4 (0.4-0.5), respectively.

CONCLUSIONS

Despite lower adiponectin levels, adiponectin was not related to the MetS in the Indonesian population and can not explain their increased cardiometabolic risk at the same BMI.

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.

Vitamin D deficiency is not associated with increased oxidative stress in chronic kidney disease pre-dialysis patients

INTRODUCTION

The progressive decline in 25-hydroxyvitamin D [25(OH)D] in chronic kidney disease (CKD) limits the kidney ability of synthesizing the vitamin. Vitamin D deficiency as defined by KDIGO (25(OH)D <20 ng/mL) is prevalent in CKD patients and associated to oxidative stress (OS). We studied a possible association between vitamin D deficiency and OS in pre-dialysis patients.

METHODS

A cross-sectional study with 206 CKD patients was carried out. Laboratory tests for 25(OH)D, 1,25(OH)2D, inflammatory markers, and OS were added to routine tests including creatinine, albumin, calcium, phosphorus, alkaline phosphatase, iPTH, glucose, hemoglobin, uric acid, total cholesterol, LDL, HDL, and triglycerides.

RESULTS

Vitamin D deficiency was present in 55 CKD patients and normal vitamin D levels were seen in 149 patients. There was a significant association between vitamin D and estimated glomerular filtration rate (eGRF). Homocysteine levels were best predicted by eGRF, sex, and age; high sensitivity C-reactive protein (hsCRP) by staging and BMI; nitric oxide metabolites (NOx) were increased in late disease; leptin was influenced by BMI and higher in women than man; and adiponectin levels were higher in women.

CONCLUSIONS

OS biomarkers were not correlated with vitamin D deficiency but increased NOx were seen in stages 4-5 CKD patients. Even though a relatively large number of CKD patients was included and a broad number of OS and inflammatory biomarkers were used in this studied we failed to find an association between vitamin D levels and eGRF. More studies are needed to evaluate the influence of vitamin D status in OS in pre-dialysis CKD patients.

Adipocytokines: Are they the Theory of Everything?

INTRODUCTION

Adipose tissue secretes various bioactive peptides/proteins, immune molecules and inflammatory mediators which are known as adipokines or adipocytokines. Adipokines play important roles in the maintenance of energy homeostasis, appetite, glucose and lipid metabolism, insulin sensitivity, angiogenesis, immunity and inflammation. Enormous number of studies from all over the world proved that adipocytokines are involved in the pathogenesis of diseases affecting nearly all body systems, which raises the question whether we can always blame adipocytokines as the triggering factor of every disease that may hit the body.

OBJECTIVE

Our review targeted the role played by adipocytokines in the pathogenesis of different diseases affecting different body systems including diabetes mellitus, kidney diseases, gynecological diseases, rheumatologic disorders, cancers, Alzheimer's, depression, muscle disorders, liver diseases, cardiovascular and lung diseases.

METHODOLOGY

We cited more than 33 recent literature reviews that discussed the role played by adipocytokines in the pathogenesis of different diseases affecting different body systems.

CONCLUSION

More evidence is being discovered to date about the role played by adipocytokines in more diseases and extra research is needed to explore hidden roles played by adipokine imbalance on disease pathogenesis.

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.

Impact of interval walking training managed through smart mobile devices on albuminuria and leptin/adiponectin ratio in patients with type 2 diabetes

Background

Interval walking training has demonstrated more pronounced positive effects on physical fitness and metabolism in type 2 diabetes (T2D), compared to continuous walking. One of the pathogenic mechanisms of T2D is associated with derangements in leptin/adiponectin axis, which might predispose affected individuals to vascular inflammation and albuminuria. The aim of this study was to investigate the effects of interval walking training delivered through smart mobile devices upon albuminuria and leptin/adiponectin ratio in patients with T2D.

Methods

Patients with T2D aged 35–75 were randomized into control (n = 26) and interval training (IT, n = 14) groups. Patients in IT group had to perform three 60‐min interval walking sessions (3 min intervals of slow and fast walking with the intensity of 40% and 70% of the peak energy expenditure) per week delivered by smartphone application for four months. The adherence to training was monitored remotely. Outcome measures were albuminuria, leptin/adiponectin ratio, obesity indicators, and glycaemic control. Leptin and adiponectin concentration was measured in serum samples by Luminex technology.

Results

In the IT group compared to control group, we observed a statistically significant decrease in albuminuria (p = .002) and leptin/adiponectin ratio (p = .01), as well as a decrease in HbA1c close to statistical significance (p = .09). In IT group, changes in leptin/adiponectin ratio correlated significantly with changes in hip circumference (p = .024).

Conclusion

Interval walking training is beneficial for vascular health in T2D via impact on albuminuria and leptin/adiponectin ratio.

Increased Expression of the Leptin Gene in Adipose Tissue of Patients with Chronic Kidney Disease-The Possible Role of an Abnormal Serum Fatty Acid Profile

Chronic kidney disease (CKD) is associated with an increased level of leptin and an abnormal fatty acid (FA) profile in the serum. However, there are no data on the associations between them, and the reason for increased serum levels in patients with CKD is not well elucidated. Recently, we found that a CKD-related abnormal FA profile caused significant changes in the expression of genes involved in lipid metabolism in hepatocytes. The aim of this study was to examine whether leptin gene expression in subcutaneous adipose tissue (SAT) of patients with CKD may contribute to increased serum levels of this adipokine and whether the abnormal serum FA profile observed in CKD patients has an impact on leptin gene expression in adipocytes. The FA profile was measured in serum samples from patients with CKD and controls by GC–MS. The relative mRNA levels of leptin were measured in SAT by Real-Time PCR. Moreover, the effect of the CKD-related abnormal FA profile on leptin gene expression was studied in in vitro cultured 3T3-L1 adipocytes. Patients with CKD had higher concentrations of serum leptin than controls and higher expression level of the leptin gene in SAT. They also had increased serum monounsaturated FAs and decreased polyunsaturated FAs. The incubation of adipocytes with FAs isolated from CKD patients resulted in an increase of the levels of leptin mRNA. Increased leptin gene expression in SAT may contribute to elevated concentrations of these adipokine in patients with CKD. CKD-related alterations of the FA profile may contribute to elevated serum leptin concentrations in patients with CKD by increasing the gene expression of this adipokine in SAT.

Analysis of serum inflammatory mediators in type 2 diabetic patients and their influence on renal function

Aim

To evaluate the serum concentrations of inflammatory mediators in patients with type 2 diabetes mellitus (T2DM) with or without renal alteration (RA) function.

Methods

Serum samples from 76 patients with T2DM and 24 healthy individuals were selected. Patients with T2DM were divided into two groups according to eGFR (> or < 60mL/min/1.73m²). Cytokines, chemokines and adipokines levels were evaluated using the Multiplex immunoassay and ELISA.

Results

TNFR1 and leptin were higher in the T2DM group with RA than in the T2DM group without RA and control group. All patients with T2DM showed increased resistin, IL-8, and MIP-1α compared to the control group. Adiponectin were higher and IL-4 decreased in the T2DM group with RA compared to the control group. eGFR positively correlated with IL-4 and negatively with TNFR1, TNFR2, and leptin in patients with T2DM. In the T2DM group with RA, eGFR was negatively correlated with TNFR1 and resistin. TNFR1 was positively correlated with resistin and leptin, as well as resistin with IL-8 and leptin.

Conclusion

Increased levels of TNFR1, adipokines, chemokines and decrease of IL-4 play important role in the inflammatory process developed in T2DM and decreased renal function. We also suggest that TNFR1 is a strong predictor of renal dysfunction in patients with T2DM.

Adiponectin in renal fibrosis

Renal fibrosis is an inevitable consequence of parenchymal scarring and is the common final pathway that mediates almost all progressive renal diseases. Adiponectin, a hormone produced by adipose tissue, possesses potent anti-insulin, anti-inflammatory, and anti-fibrotic properties. Reportedly, adiponectin serves as an important messenger that facilitates complex interactions between adipose tissue and other metabolically related organs. In recent years, a growing body of evidence supports adiponectin involvement in renal fibrosis. These studies provide a deeper understanding of the molecular mechanism of action of adiponectin in renal fibrosis and also offer a potential preventive and therapeutic target for renal fibrosis. In this review, the physiological role of adiponectin is briefly introduced, and then the mechanism of adiponectin-mediated renal fibrosis and the related signaling pathways are described. Finally, we summarize the findings regarding the clinical value of adiponectin in renal fibrotic diseases and prospected its application potential.

Selected cardiovascular risk factors in early stages of chronic kidney disease

Cardiovascular diseases, including hypertension, congestive heart failure, myocardial infarction, stroke and atherosclerosis, are common in patients with chronic kidney disease. Aside from the standard biomarkers, measured to determine cardiovascular risk, new ones have emerged: markers of oxidative stress, apoptosis, inflammation, vascular endothelium dysfunction, atherosclerosis, organ calcification and fibrosis. Unfortunately, their utility for routine clinical application remains to be elucidated. A causal relationship between new markers and cardiovascular diseases in patients with chronic kidney disease remains to be established. First of all, there is a lack of large, randomized trials. Moreover, most studies focus on patients with end-stage renal disease as well as on dialysed patients. In such patients, cardiovascular diseases are already present and advanced while early detection of cardiovascular disease risk factor in patients with early-stages of chronic kidney disease would allow more precise prognosis and, as a result, changes in treatment algorithm. In this article, we conduct a comprehensive review of literature for publications relating to cardiovascular risk factors in patients with early-stages of chronic kidney disease. Overall, there are many encouraging advances in detection of cardiovascular risk factors that are making the future more promising for patients suffering from chronic kidney disease.

Association of serum adiponectin level with cystatin C in male patients with obstructive sleep apnea syndrome

PURPOSE

Obstructive sleep apnea syndrome (OSAS) was suggested to exert an effect on renal function. However, the specific mechanism was still unknown. We try to find the association among OSAS, adiponectin, and cystatin C and the effect of adiponectin on renal function in OSAS patients.

METHODS

Seventeen healthy men and seventy-three men which only had OSAS were included in the end. Apnea-hypopnea index (AHI), oxygen desaturation index (ODI), the percentage of total sleep time spent with SpO₂ < 90% (T90%), lowest O₂ saturation (LaSO₂), Epworth Sleepiness Scale (ESS) score, serum adiponectin, and high-sensitive C-reactive protein (hsCRP) were detected in all subjects, and renal function was evaluated with creatinine, cystatin C, and estimated glomerular filtration rate (eGFR).

RESULTS

Demographic data, creatinine, and eGFR did not differ among the studied groups. Decreased serum adiponectin levels were associated with severe OSAS. OSAS patients had a higher hsCRP and cystatin C than those without OSAS. Serum adiponectin levels had a negative association with cystatin C. After adjusted for confounders, adiponectin, hsCRP, and ODI had a significant prediction on the cystatin C (β = - 0.218, p = 0.011; β = 0.226, p = 0.037; and β = 0.231, p = 0.029).

CONCLUSIONS

Decreased serum adiponectin was associated with increased cystatin C in male OSAS patients. These results suggest that serum adiponectin might be a regulatory factor for renal function in OSAS.

Obesity is not associated with progression to end stage renal disease in patients with biopsy-proven glomerular diseases

Background

Body mass index (BMI) is associated with renal disease progression in unspecified CKD. The relationship between BMI and primary glomerular disease (GN) may be more complex. We aimed to evaluate the association between BMI and renal disease progression in patients with primary glomerular disease (GN).

Methods

This was a single-centre retrospective cohort study performed in adult patients with biopsy-proven primary GN (excluding minimal change disease) from January 2000 to December 2015, with follow-up data until June 2017. BMI at time of biopsy was categorised as ≤25 kg/m², > 25 to ≤30 kg/m² and > 30 kg/m². We used univariate and multivariate survival analyses to evaluate factors associated with progression to a composite endpoint of stage 5 CKD or renal replacement therapy (Major Adverse Renal Event - MARE) censoring for competing risk of death using Fine and Gray subdistribution hazards model.

Results

We included 560 patients with biopsy-proven primary GN and available BMI data: 66.1% were male with median age 54.8 (IQR 41.1–66.2) years and BMI 28.2 (IQR 24.9–32.1) kg/m². Those with BMI 25-30 kg/m² (n = 210) and with BMI > 30 kg/m² (n = 207) were older (p = 0.007) with higher systolic and diastolic blood pressures (p = 0.02 and 0.004 respectively) than those with BMI < 25 kg/m² (n = 132). There was a greater proportion of focal segmental glomerulosclerosis in those with higher BMI (3.9% in BMI < 25 kg/m², 7.9% in BMI 25–30 kg/m² and 10.7% in BMI > 30 kg/m² of biopsies (p = 0.01)), but similar proportions of other GN diagnoses across BMI groups. Baseline eGFR (p = 0.40) and uPCR (p = 0.17) were similar across BMI groups. There was no interaction between BMI and time to MARE (log-rank p = 0.98) or death (log-rank p = 0.42). Censoring for competing risk of death, factors associated with progression to MARE were: younger age, lower baseline eGFR and higher uPCR, but not BMI (SHR 0.99, 95%CI 0.97–1.01, p = 0.31) nor blood pressure or GN diagnosis.

Conclusion

BMI was not associated with progression to MARE in this patient cohort with primary GN. Efforts should be directed to managing other known risk factors for CKD progression.

Mechanisms of Adiponectin Action: Implication of Adiponectin Receptor Agonism in Diabetic Kidney Disease

Adiponectin, an adipokine secreted by adipocytes, exerts favorable effects in the milieu of diabetes and metabolic syndrome through its anti-inflammatory, antifibrotic, and antioxidant effects. It mediates fatty acid metabolism by inducing AMP-activated protein kinase (AMPK) phosphorylation and increasing peroxisome proliferative-activated receptor (PPAR)-α expression through adiponectin receptor (AdipoR)1 and AdipoR2, respectively, which in turn activate PPAR gamma coactivator 1 alpha (PGC-1α), increase the phosphorylation of acyl CoA oxidase, and upregulate the uncoupling proteins involved in energy consumption. Moreover, adiponectin potently stimulates ceramidase activity associated with its two receptors and enhances ceramide catabolism and the formation of its anti-apoptotic metabolite, sphingosine 1 phosphate (S1P), independently of AMPK. Low circulating adiponectin levels in obese patients with a risk of insulin resistance, type 2 diabetes, and cardiovascular diseases, and increased adiponectin expression in the state of albuminuria suggest a protective and compensatory role for adiponectin in mitigating further renal injury during the development of overt diabetic kidney disease (DKD). We propose AdipoRon, an orally active synthetic adiponectin receptor agonist as a promising drug for restoration of DKD without inducing systemic adverse effects. Its renoprotective role against lipotoxicity and oxidative stress by enhancing the AMPK/PPARα pathway and ceramidase activity through AdipoRs is revealed here.

Adiponectin as a novel biomarker for liver fibrosis

Adiponectin is known to play primary roles in the regulation of systemic glucose homeostasis and lipid metabolism. Interestingly, emerging evidence indicates beneficial effects of adiponectin on liver fibrosis; however, the exact mechanisms of this action remain unclear. Herein, we aimed to summarize the recent findings regarding the role of adiponectin in liver fibrogenesis and update the current comprehensive knowledge regarding usefulness of adiponectin-based treatments in liver fibrosis. Adiponectin has been demonstrated to have an anti-fibrotic action in the liver by blocking the activation of hepatic stellate cell-mediated adenosine monophosphate-activated protein kinase and peroxisome proliferator-activated receptor-alpha pathways, which in turn diminish the expression of pro-fibrotic genes. In addition, hyperadiponectinemia was noted in patients with various chronic liver diseases (CLDs)-related liver fibrosis. An increase in circulating adiponectin levels was also found to be associated with the development of liver fibrosis, indicating a role of adiponectin as a non-invasive biomarker for predicting the progression of liver fibrosis. It is therefore reasonable to speculate that adiponectin may be developed as a new therapeutic candidate for the treatment of liver fibrosis. Nonetheless, future observations are still necessary to fully elucidate the extent of the effects of adiponectin on liver fibrotic outcomes, in order to modify adiponectin as an anti-fibrotic therapy that would speed up fibrosis reversal in patients with CLD.

Relation of multi-marker panel to incident chronic kidney disease and rapid kidney function decline in African Americans: the Jackson Heart Study

Background

Few investigations have evaluated the incremental usefulness of multiple biomarkers representing varying physiological pathways for predicting risk of renal outcomes in African Americans.

Design, setting, participants, and measurements

We related a multi-marker panel to incident chronic kidney disease (CKD) and rapid kidney function decline (RKFD) in 2813 Jackson Heart Study participants without prevalent CKD at exam 1 (2000–2004) and with complete assays at exam 1 for 9 biomarkers: adiponectin, aldosterone, B-natriuretic peptide [BNP], cortisol, high sensitivity C-reactive protein (hsCRP), endothelin, homocysteine, plasma renin activity and mass. Incident CKD was defined as estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² at exam 3 while RKFD was defined as eGFR ≥30% loss between exams 1 and 3 (8.2 median years). We employed multiple logistic regression model to describe association between the panel and incident CKD and RKFD and used backward elimination strategy to estimate the most parsimonious biomarker model while controlling for conventional risk factors.

Results

The multi-marker panel predicted the risk for both incident CKD (odds ratios [OR], 2.72; 95% confidence intervals [CI], 1.63, 4.56; P = 0.001) and RKFD (2.61; 95% CI, 1.67, 4.08; P < 0.001). Per standard deviation increase in log biomarker concentrations were significantly (multivariable adjusted odds ratios, [95% confidence interval], p-value) associated with incident CKD: plasma adiponectin (1.24 [1.07, 1.44], p = 0.005) and leptin (1.3 [1.06, 1.61], p = 0.011), and with RKFD: plasma adiponectin (1.22 [1.06, 1.40], p = 0.006); hsCRP (1.17 [1.01, 1.36], p = 0.031) and aldosterone (0.85 [0.74, 0.96], p = 0.012). Moderate levels (3rd quartile) of aldosterone were inversely associated with incident CKD (0.54 [0.35, 0.82], p = 0.004) while leptin was associated with RKFD (1.64 [1.10, 2.44], p = 0.015). Biomarkers improved CKD risk prediction (P = 0.003) but not RKFD risk prediction (P = 0.10).

Conclusion

In this community-based sample of African Americans, a multi-marker panel added only moderate predictive improvement compared to conventional risk factors.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1026-y) contains supplementary material, which is available to authorized users.

Adiponectin is valuable in the diagnosis of acute heart failure with renal insufficiency

Acute heart failure (AHF) is a major public health issue due to its high incidence and poor prognosis; thus, efficient and timely diagnosis is critical for improving the prognosis and lowering the mortality rate. Amino-terminal pro-brain natriuretic peptide (NT-proBNP) is widely used in the diagnosis of AHF; however, its efficacy is controversial in diagnosing AHF with renal insufficiency. There were numerous studies reporting the association of adiponectin (ADPN) and heart diseases. Therefore, the present study aimed to investigate whether ADPN is helpful in identifying AHF with renal insufficiency. A total of 407 participants (218 AHF patients and 189 controls) were enrolled into the current study. The plasma levels of ADPN and NT-proBNP were measured using a sandwich enzyme-linked immunosorbent assay and an electrochemiluminescence immunoassay, respectively. In addition, these levels were compared among the various New York Health Association classes, as well as the ischemic and non-ischemic AHF cases. The correlation between the two biomarkers and the renal function was analyzed by Spearman's correlation, while the diagnostic efficiency of ADPN and NT-proBNP was evaluated in AHF patients with and without renal insufficiency. The results revealed that NT-proBNP exhibited a higher diagnostic efficiency as compared with ADPN in patients without renal insufficiency [area under the receiver operating characteristic curve (AUC), 0.905 vs. 0.775]. By contrast, the ADPN presented a better diagnostic value in comparison with NT-proBNP in AHF with renal insufficiency (AUC, 0.872 vs. 0.828). Therefore, a combination of these two biomarkers may provide an excellent efficacy in the diagnosis of AHF with renal insufficiency (AUC, 0.904; sensitivity, 71.2%; specificity, 98.3%). In conclusion, ADPN is a valuable biomarker for diagnosing AHF, particularly in patients with impaired renal function.

Lipodystrophy Increases the Risk of CKD Development in HIV-Positive Patients in Switzerland: The LIPOKID Study

Introduction

Antiretroviral therapy has improved the life expectancy of patients living with HIV. However, lipodystrophy syndrome (LD) remains prevalent, affecting mostly patients treated with first-generation antiretroviral drugs. This syndrome is characterized by changes in body fat distribution with or without associated metabolic changes. Here, we studied whether clinically evaluated LD is independently associated with chronic kidney disease (CKD) development (sustained estimated glomerular filtration rate [eGFR] < 60 ml/min per 1.73 m²) in HIV-positive patients.

Methods

We conducted a prospective cohort study (the LIPOKID Study) among all the patients from the Swiss HIV Cohort Study (SHCS) with an eGFR >60 ml/min per 1.73 m² upon their entry into the cohort with more than 3 months of follow-up from January 2002 to August 2016. Cox regression models were used to estimate the association between LD and CKD development.

Results

Among the 5384 patients included, 1341 (24.9%) developed LD during the follow-up. The mean follow-up time was 72.3 months (SD ±48.4). In total, 252 patients (4.7%) reached the primary endpoint after a median time of 51.3 months (±SD 39.9 months) from inclusion. A diagnosis of LD significantly increased the risk of an eGFR on univariate analysis (hazard ratio [HR] = 2.72; 95% confidence interval [95% CI] = 2.07−3.58; P < 0.001) and remained significantly higher after adjustment for known HIV and non-HIV risk factors for CKD (HR = 2.37; 95% CI = 1.67−3.36; P < 0.001). The effect of LD on CKD was not mediated through the use of nephrotoxic antiretroviral drugs.

Conclusion

Lipodystrophy syndrome is independently associated with CKD after adjustment for previously reported risk factors.

Validating the association between plasma tumour necrosis factor receptor 1 levels and the presence of renal injury and functional decline in patients with Type 2 diabetes

AIMS

Elevated plasma soluble tumour necrosis factor receptor 1 (TNFR1) predicts long-term progression of chronic kidney disease. We investigated the association between elevated TNFR1 and the presence of renal disease in patients with Type 2 diabetes mellitus registering a haemoglobin A1c (HbA1c) >48mmol/mol despite medical therapy.

METHODS

Using sensitivity, specificity and regression analyses we interrogated the association between plasma TNFR1 and presence of chronic kidney disease as assessed by the presence of microalbuminuria and/or an estimated glomerular filtration rate of less than 60ml/min/1.73m² (stages 3-5 chronic kidney disease). The association of TNFR1 with C-reactive protein and leptin-adiponectin ratio as plasma markers of systemic inflammation and adipose stress respectively was also investigated.

RESULTS

Upper quartile TNFR1 is independently associated with elevated urinary albumin-creatinine ratios, reductions in eGFR and strongly predicts the presence of stages 3-5 chronic kidney disease in regression modelling. Elevated TNFR1 levels are associated with increased plasma C-reactive protein and augmented leptin-adiponectin ratio.

CONCLUSIONS

Our study confirms plasma TNFR1 as a surrogate of renal structural and functional impairment in patients with type 2 diabetes mellitus. Association of TNFR1 with markers of systemic inflammation and adipose stress indicates that TNFR1 may be a biomarker of these processes as components of the pathogenesis of diabetic kidney disease.

Leptin, An Adipokine With Central Importance in the Global Obesity Problem

Leptin has central importance in the global obesity and cardiovascular disease problem. Leptin is principally secreted by adipocytes and acts in the hypothalamus to suppress appetite and food intake, increase energy expenditure, and regulate body weight. Based on clinical translation of specific and networked actions, leptin affects the cardiovascular system and may be a marker and driver of cardiometabolic risk factors with interventions that are actionable by cardiologists. Leptin subnetwork analysis demonstrates a statistically significant role for ethnoculturally and socioeconomically appropriate lifestyle intervention in cardiovascular disease. Emergent mechanistic components and potential diagnostic or therapeutic targets include hexokinase 3, urocortins, clusterin, sialic acid-binding immunoglobulin-like lectin 6, C-reactive protein, platelet glycoprotein VI, albumin, pentraxin 3, ghrelin, obestatin prepropeptide, leptin receptor, neuropeptide Y, and corticotropin-releasing factor receptor 1. Emergent associated symptoms include weight change, eating disorders, vascular necrosis, chronic fatigue, and chest pain. Leptin-targeted therapies are reported for lipodystrophy and leptin deficiency, but they are investigational for leptin resistance, obesity, and other chronic diseases.

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.

Association of adiposity with hemoglobin levels in patients with chronic kidney disease not on dialysis

Background

In the general population, adiposity influences erythropoiesis and iron metabolism. We aimed to assess the relationships between adiposity [estimated by body mass index (BMI) and abdominal circumference (AC)] and biomarkers of erythropoiesis in patients with chronic kidney disease (CKD) not on dialysis.

Methods

A total of 2322 patients from the Chronic Kidney Disease Japan Cohort study were included. Patients were grouped according to BMI (low: < 18.5 kg/m², normal: 18.5–24.5 kg/m², and high: ≥ 25 kg/m²) and AC categories (large: ≥ 90 cm for men and ≥ 80 cm for women; small: < 90 cm and < 80 cm, respectively). Body composition and laboratory data were assessed at baseline, and at 1 and 2 years of follow-up.

Results

Multivariate regression analysis of the 3 time-points showed that high BMI and large AC in male patients were significantly associated with higher hemoglobin levels. Hemoglobin levels were lower in female patients with low BMI and small AC than that in female patients with normal BMI and large AC, respectively; however, hemoglobin levels plateaued above a threshold of 25 kg/m² for BMI and 80 cm for AC. While BMI and AC were positively associated with C-reactive protein levels, they were not associated with levels of transferrin saturation, ferritin, and erythropoietin in multivariate models.

Conclusions

Body composition appears to be associated with erythropoiesis; however, adiposity may be only associated with increased erythropoiesis in male patients. In addition, body composition does not appear to hamper iron metabolism in CKD patients not on dialysis.

Electronic supplementary material

The online version of this article (10.1007/s10157-017-1501-y) contains supplementary material, which is available to authorized users.

Association of the anti-angiogenic factor secreted protein and rich in cysteine (SPARC) with vascular complications among Chinese type 2 diabetic patients in Singapore

AIMS

This study evaluated the association of the anti-angiogenic SPARC with known angiogenesis-associated factors and diabetes-related micro- and macro-vascular complications in a Singapore Chinese cohort with type 2 diabetes (T2DM).

METHODS

Plasma SPARC was measured by immunoassay in 438 T2DM adults (mean age:58±11years).

RESULTS

Higher SPARC levels in subjects stratified by SPARC tertiles displayed decreased pro-angiogenic adiponectin, osteopontin, vascular cell adhesion molecule (VCAM)-1 and matrix metalloproteinase (MMP)-2 concentrations (all p<0.05). The anti-angiogenic pigment epithelium-derived factor (PEDF) level was not statistically different among the SPARC tertiles. Age-adjusted partial correlation revealed significant associations of SPARC with adiponectin, osteopontin, VCAM-1, MMP-2, and PEDF (all p<0.05). Lower SPARC was accompanied by less favorable estimated glomerular filtration rate (eGFR) and carotid-femoral pulse wave velocity (PWV) readings (all p<0.05). Conversely, ankle-brachial index (ABI) reduced with increasing SPARC (p=0.048). The eGFR (B=0.834, p=0.019), PWV (B=-7.925, p=0.009), and ABI (B=-142.160, p=0.010) remained as determinants of SPARC after confounder adjustment. Moreover, individuals in the lowest SPARC tertile had increased odds of aortic stiffness (OR=1.900, 95% CI=1.103-3.274) but reduced odds of peripheral arterial disease (OR=0.400, 95% CI=0.175-0.919). However, SPARC was not independently associated with chronic kidney disease.

CONCLUSIONS

The anti-angiogenic SPARC may be associated with the pathophysiology of diabetes-related macrovascular complications.

Association of Increased Serum Leptin with Ameliorated Anemia and Malnutrition in Stage 5 Chronic Kidney Disease Patients after Parathyroidectomy

Leptin is an adipokine that regulates various metabolism, but its association with secondary hyperparathyroidism (SHPT), a clinical manifestation of chronic kidney disease-mineral and bone disorder (CKD-MBD), remains obscure. Parathyroidectomy (PTX) is recommended for severe SHPT patients. Here, the associations between circulating leptin and clinical characteristics in CKD patients were investigated. Effects of PTX on leptin production were analyzed in vivo and in vitro. Controls and CKD patients had approximate serum leptin levels in that a larger proportion of CKD patients with body mass index (BMI) <23 kg/m². Serum leptin was related to anemia, albumin, and bone metabolism disorders in CKD patients. Lower intact parathyroid hormone (PTH) was related with higher leptin in PTX patients group. Severe SHPT inhibited uremia-enhanced leptin production in 3T3-L1 adipocytes, which was attenuated after PTX. High levels of PTH were found to reduce Akt phosphorylation and leptin production in vitro but high levels of calcium and phosphorus were not. Successful PTX was found to improve anemia and malnutrition in severe SHPT patients, and this was correlated with increased circulating leptin levels via up-regulated Akt signaling in adipocytes. These findings indicated the therapeutic potential of leptin and related target pathway for improving survival and quality of life in CKD.

The role of adipokines in chronic inflammation

Adipose tissue has traditionally been defined as connective tissue that stores excess calories in the form of triacylglycerol. However, the physiologic functions attributed to adipose tissue are expanding, and it is now well established that adipose tissue is an endocrine gland. Among the endocrine factors elaborated by adipose tissue are the adipokines; hormones, similar in structure to cytokines, produced by adipose tissue in response to changes in adipocyte triacylglycerol storage and local and systemic inflammation. They inform the host regarding long-term energy storage and have a profound influence on reproductive function, blood pressure regulation, energy homeostasis, the immune response, and many other physiologic processes. The adipokines possess pro- and anti-inflammatory properties and play a critical role in integrating systemic metabolism with immune function. In calorie restriction and starvation, proinflammatory adipokines decline and anti-inflammatory adipokines increase, which informs the host of energy deficits and contributes to the suppression of immune function. In individuals with normal metabolic status, there is a balance of pro- and anti-inflammatory adipokines. This balance shifts to favor proinflammatory mediators as adipose tissue expands during the development of obesity. As a consequence, the proinflammatory status of adipose tissue contributes to a chronic low-grade state of inflammation and metabolic disorders associated with obesity. These disturbances are associated with an increased risk of metabolic disease, type 2 diabetes, cardiovascular disease, and many other pathological conditions. This review focuses on the impact of energy homeostasis on the adipokines in immune function.

Association of serum leptin and adiponectin with anthropomorphic indices of obesity, blood lipids and insulin resistance in a Sub-Saharan African population

BACKGROUND

There is little data on the metabolic effects of adipokines in sub-Saharan African populations. This study aimed to explore the potential relationship of leptin and adiponectin, with obesity, plasma lipids and insulin resistance in a Cameroonian population.

METHODS

We enrolled 167 men and 309 women aged ≥18 years from the general population in Cameroon. Data were collected on waist circumference (WC), body mass index (BMI), waist-to-hip ratio (WHR), body fat (BF%), fasting blood glucose, plasma lipids, adiponectin, leptin, insulin and homeostasis model for assessment of insulin resistance (HOMA-IR). Pearson's correlation and multiple stepwise linear regression analyses were used to determine correlates of leptin and adiponectin serum levels.

RESULTS

The prevalence of obesity was higher in women compared to men (p < 0.0001), and Central obesity which is more prevalent particularly in women (WC = 42.4%, WHR = 42.3%), is almost for 90% comparable to %BF (42.7%). Adiponectin negatively with BMI (r = -0.294, p < 0.0001), WC (r = -0.294, p < 0.0001), %BF (r = -0.122, p = 0.028), WHR (r = -0.143, p = 0.009), triglycerides (r = -0.141, p = 0.011), HOMA-IR (r = -0.145, p = 0.027) and insulin (r = -0.130, p = 0.048). Leptin positively correlated with BMI (r = 0.628), WC (r = 0.530), BF% (r = 0.720), (all p < 0.0001); with DBP (r = 0.112, p = 0.043), total cholesterol (r = 0.324, p < 0.0001), LDL-cholesterol (r = 0.298, p < 0.0001), insulin (r = 0.320, p < 0.001 and HOMA-IR (r = 0.272, p < 0.0001). In multiple stepwise regression analysis, adiponectin was negatively associated with WC (β = -0.38, p = 0.001) and BF% (β = 0.33, p < 0.0001), while leptin was positively associated with BF% (β = 0.60, p < 0.0001), total cholesterol (β = 0.11, p = 0.02) and HOMA-IR (β = 0.11, p = 0.02). When controlled for gender, HOMA-IR was found significantly associated to adiponectin (β = 0.13, p = 0.046), but not BF%, while the association previously found between leptin and HOMA-IR disappeared; BMI and WC were significantly associated with leptin (β = 0.18, p = 0.04 & β = 0.19, p = 0.02 respectively).

CONCLUSION

This study, which includes a population who was not receiving potentially confounding medications, confirms the associations previously observed of adiponectin with reduced adiposity especially central adiposity and improved insulin sensitivity. Confirmatory associations were also observed between leptin and obesity, blood lipids and insulin resistance for the first time in an African population. Gender was significant covariate interacting with insulin sensitivity/insulin resistance and obesity indexes associations in this population.

The role of adipokines in ischemic stroke risk stratification

Background

Adiponectin, leptin, and resistin are the most well-studied adipokines and play important roles in the regulation of glucose metabolism, subclinical inflammation, and cardiovascular homeostasis. Accordingly, measurement of adipokine levels might be useful in cardiovascular risk stratification. Moreover, the study of single-nucleotide polymorphisms of genes that encode these adipokines might also represent a valuable predictive tool in cardiovascular disease prevention strategies.

Aims

To summarize the biologic role of the adipokines adiponectin, leptin, and resistin and the prognostic value of their serum levels regarding the occurrence and outcome of ischemic stroke. We also discuss the relationship of single-nucleotide polymorphisms of the adiponectin, leptin genes, and the −420C > G polymorphism of resistin gene with stroke risk.

Summary of review

Several studies in the general population evaluated the association between these adipokines and stroke risk, yielding conflicting results. There are more limited data regarding the effect of these adipokines on stroke severity and outcome. A small number of studies also assessed the predictive role of single-nucleotide polymorphisms of the adiponectin, leptin, and resistin genes regarding stroke risk, but the findings were also controversial.

Conclusions

It is unclear whether adiponectin, leptin, and resistin levels or the single-nucleotide polymorphisms of their encoding genes are independently associated with stroke risk. However, given the role of these adipokines in the pathogenesis of atherosclerosis, larger prospective studies, both in the general population and in patients with a history of stroke, are needed to determine whether the measurement of serum levels of these adipokines or the evaluation of single-nucleotide polymorphisms in their encoding genes could improve stroke risk prediction. If this relationship is proven, therapeutic interventions targeting adipokine levels might represent a novel approach to reduce stroke-related mortality and disability.

Associations of serum adiponectin with markers of cardio-metabolic disease risk in Indigenous Australian adults with good health, diabetes and chronic kidney disease

The higher serum adiponectin concentrations observed in females are often attributed to differences in adiposity or sex hormones. There is little data describing adiponectin in Indigenous Australians, and no studies examining its association with cardio-metabolic disease risk markers and chronic kidney disease (CKD).

AIM

To describe the relationship of serum adiponectin with cardio-metabolic disease risk markers and kidney function in a community-based sample of Indigenous Australian adults, with particular reference to sex-specific differences.

METHODS

A cross-sectional analysis of a community-based volunteer sample of 548 Indigenous Australian adults (62% female), stratified into five cardio-metabolic risk groups ranging from good health (strata-1) to high cardio-metabolic risk and low measured glomerular filtration rate (mGFR, <60ml/min/1.73m²) (strata-5). We examined serum adiponectin concentrations with cardio-metabolic risk markers, albuminuria and mGFR.

RESULTS

Indigenous Australian females had a lower than expected adiponectin concentration (3.5μg/ml), which was higher than males in strata 1-4 (as in other populations), but not in strata-5 (mGFR<60, p=0.19), and higher leptin: adiponectin ratio than other populations (7.8ng/μg - strata-1, healthy females; 12.2ng/μg - strata-3, females with diabetes and mGFR≥90). Female-gender, HDL-cholesterol (positive), mGFR and waist: hip ratio (WHR) (inverse) were independently associated with log-adiponectin when mGFR≥60; when mGFR<60, female-gender was associated with 0.27 units lower log-adiponectin.

CONCLUSION

Female-gender was not associated with higher adiponectin concentrations in Indigenous Australians with mGFR<60ml/min/1.73m². High WHR was frequent in both genders, and inversely associated with adiponectin. Longitudinal studies are needed to examine relationships of serum adiponectin, obesity and cardiovascular disease events in Indigenous Australians.