Gender-specific association of adiponectin as a predictor of progression of chronic kidney disease: the Mild to Moderate Kidney Disease Study

The role of perirenal adipose tissue deposition in chronic kidney disease progression: Mechanisms and therapeutic implications

Chronic kidney disease (CKD) represents a significant and escalating global health challenge, with morbidity and mortality rates rising steadily. Evidence increasingly implicates perirenal adipose tissue (PRAT) deposition as a contributing factor in the pathogenesis of CKD. This review explores how PRAT deposition may exert deleterious effects on renal structure and function. The anatomical proximity of PRAT to the kidneys not only potentially causes mechanical compression but also leads to the dysregulated secretion of adipokines and inflammatory mediators, such as adiponectin, leptin, visfatin, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and exosomes. Additionally, PRAT deposition may contribute to renal lipotoxicity through elevated levels of free fatty acids (FFA), triglycerides (TAG), diacylglycerol (DAG), and ceramides (Cer). PRAT deposition is also linked to the hyperactivation of the renin-angiotensin-aldosterone system (RAAS), which further exacerbates CKD progression. Recognizing PRAT deposition as an independent risk factor for CKD underscores the potential of targeting PRAT as a novel strategy for the prevention and management of CKD. This review further discusses interventions that could include measuring PRAT thickness to establish a baseline, managing metabolic risk factors that promote its deposition, and inhibiting key PRAT-induced signaling pathways.

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.

Obesity and the risk of cardiometabolic diseases

The prevalence of obesity has reached pandemic proportions, and now approximately 25% of adults in Westernized countries have obesity. Recognized as a major health concern, obesity is associated with multiple comorbidities, particularly cardiometabolic disorders. In this Review, we present obesity as an evolutionarily novel condition, summarize the epidemiological evidence on its detrimental cardiometabolic consequences and discuss the major mechanisms involved in the association between obesity and the risk of cardiometabolic diseases. We also examine the role of potential moderators of this association, with evidence for and against the so-called 'metabolically healthy obesity phenotype', the 'fatness but fitness' paradox or the 'obesity paradox'. Although maintenance of optimal cardiometabolic status should be a primary goal in individuals with obesity, losing body weight and, particularly, excess visceral adiposity seems to be necessary to minimize the risk of cardiometabolic diseases.

Serum adiponectin concentrations as a risk factor for cardiovascular complications in type 1 diabetes

AIM

By analyzing data from DCCT/EDIC study, we investigated the associations of serum adiponectin concentrations with macrovascular complications and cardiovascular events in T1D.

MATERIALS AND METHODS

Adiponectin concentrations were measured in EDIC year 8. The participants (n = 1040) were divided into four groups by quartiles of adiponectin concentrations. The association of macrovascular complications and cardiovascular events were analyzed by using multivariable regression and Cox proportional hazards models.

RESULTS

High adiponectin concentrations were associated with decreased risk of peripheral artery disease represented by ankle brachial index (ORs (95% CI): 0.22 (0.07-0.72), 0.48 (0.18-1.25), and 0.38 (0.14-0.99) in fourth, third, and second quartiles compared with first quartile), with reduced carotid intima-media thickness, and with increased LVEDV index. Moreover, high adiponectin concentrations were also associated with increased risk of any cardiovascular events (HRs (95% CI): 2.59 (1.10-6.06), 2.03 (0.90-4.59), and 1.22 (0.52-2.85)) and major atherosclerotic cardiovascular events (HRs (95% CI): 11.37 (2.04-63.43), 5.68 (1.04-31.07), and 3.76 (0.65-21.77) in fourth, third, and second quartiles compared with first quartile), however, after adjustments with LVEDV index, these associations were diminished.

CONCLUSIONS

Adiponectin may protect carotid atherosclerosis and peripheral artery disease in T1D. It may be associated with increased cardiovascular events, depending on cardiac structural changes.

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.

Association of Serum Adipokines and Resting Energy Expenditure in Patients With Chronic Kidney Disease

Background and Aim

Metabolic disorders are prevalent in patients with chronic kidney disease (CKD) and may lead to protein energy wasting (PEW). Adipokines improve connections between PEW and energy metabolism. We aimed to determine the relationship between adipokine levels and resting energy expenditure (REE) in patients with CKD.

Methods

A total of 208 patients in non-dialyzed CKD stages 3–5 were enrolled in this cross-sectional study. Serum adipokines (leptin, adiponectin, and interleukin 6 (IL-6) were measured using enzyme-linked immunosorbent assay. Patient's REE was measured using indirect calorimetry. Fat mass (FM) and lean tissue mass (LTM) were measured using multiple-frequency bioimpedance analysis. Spearman correlation analyses and multivariate linear regression models were used to assess the association between serum adipokines and REE.

Results

The mean age was 52.7 ± 14.6 years, and 26.9, 26.4, and 46.7% of our participants had CKD stages 3, 4, and 5, respectively. The median values of serum adiponectin, leptin, and IL-6 were 470.4 (range, 291.1–802.2), 238.1 (range, 187.9–418.4), and 4.0 (range, 2.4–9.5) pg/mL, respectively. The male participants had significantly lower FM% (P = 0.001) and lower leptin levels (P < 0.001) than the female participants. After adjusting for age, diabetes, high-sensitivity C-reactive protein, intact parathyroid hormone, LTM, and FM, multiple linear regression analysis revealed that serum leptin levels were significantly positively associated with REE in men rather than in women (P < 0.05). Serum adiponectin levels were inversely associated with REE in men, but this association disappeared while FM was additionally adjusted. Adiponectin levels in women were not correlated with REE (P > 0.05). IL-6 was not significantly associated with REE in either men or women.

Conclusions

A sex-specific relationship between serum adipokines (leptin and adiponectin) and REE was observed in patients with CKD stages 3–5, which was partly confounded by FM.

Plasma total adiponectin and changes in renal function in a cohort from the community: the prospective Data from an Epidemiological Study on the Insulin Resistance Syndrome study

BACKGROUND

High adiponectin levels are associated with diabetic nephropathy. Nevertheless, it is not known whether plasma adiponectin is associated with renal function decline in the general population. We evaluated whether adiponectin concentrations were associated with changes in renal function in a community cohort, the Data from an Epidemiological Study on the Insulin Resistance Syndrome (DESIR) study.

METHODS

Plasma adiponectin concentrations were measured in a random sample of 3284 people from the DESIR study, a 9-year prospective cohort from the general population. Data were analysed for three endpoints during follow-up: incidence of Stage 3 chronic kidney disease (CKD); the Kidney Disease: Improving Global Outcomes (KDIGO) criterion 'certain drop in eGFR' and rapid kidney function decline [estimated glomerular filtration rate (eGFR) slope steeper than -3 mL/min/1.73 m2/year].

RESULTS

After exclusion of participants with an eGFR <60 mL/min/1.73 m2 at baseline and those with type 2 diabetes or impaired fasting glycaemia at any time during follow-up (remaining n = 2174), there was a 113% higher risk for a rapid decline in kidney function in participants with adiponectin above the third tertile (T3) versus below the first tertile (T1) (Ptrend = 0.004) and a 53% higher risk for kidney function decline as defined by the KDIGO criterion (Ptrend = 0.04). In a cross-sectional analysis, adiponectin was positively associated with urinary albumin:creatinine ratio at baseline (P = 0.009).

CONCLUSIONS

In a healthy cohort from the general population, higher levels of plasma adiponectin were associated with decreased renal function at baseline and at follow-up. This result is similar to what is observed in people with diabetic nephropathy, in contrast with animal models of nephropathy.

Globular adiponectin inhibits osteoblastic differentiation of vascular smooth muscle cells through the PI3K/AKT and Wnt/β-catenin pathway

Lipid metabolism is closely related to the improvement of vascular calcification (VC) in chronic kidney disease (CKD). Globular adiponectin (gAd) has been reported to be involved in the development of VC in CKD, but the detailed regulatory role remains unclear. The present study is aimed to investigate the biological function and the underlying regulation mechanism of gAd in the process of VC during CKD. Vascular smooth muscle cells (VSMCs) calcification was determined by Alizarin Red S staining. Protein signaling related with VC was tested by western blotting. The expression and intracellular localization of runt-related transcription factor 2 (Runx2) was detected by immunofluorescence and uraemic rat with VC was established by a two-step nephrectomy. Combined with the results of Alizarin Red S staining, we discovered that β-glycerophosphate (β-Gp)-induced the osteoblastic differentiation of VSMCs was significantly reversed by gAd treatment. Along with the VSMCs calcification and the increase of Runx2 in β-Gp-exposed VSMCs, the activities of protein kinase B (AKT) and Wnt/β-catenin pathway were enhanced, but that were counteracted by the exposure of gAd in rat and human VSMCs. After administration with agonists of the Wnt (SKL2001) and AKT (SC79), there appeared more osteoblastic differentiation and higher expression of Runx2 in gAd-treated VSMCs, but showing lower impact in the presence of SC79 than that in the presence of SKL2001. In the in vivo experiments, intravenous injection of gAd also significantly inhibited VC and Runx2 level in uraemic rat in a dose-dependent manner, possibly through regulating Wnt/β-catenin pathway. This study demonstrates that gAd ameliorates osteoblastic differentiation of VSMCs possibly by blocking PI3K/AKT and Wnt/β-catenin signaling transduction. The findings provide an important foundation for gAd in treating VC in kidney diseases.

Low serum adiponectin level is associated with better physical health-related quality of life in chronic kidney disease

Hyperadiponectemia is paradoxically associated with renal disease progression and mortality in chronic kidney disease (CKD). Its association with health-related quality of life (HR-QOL) is unknown. This study aimed to verify the association between adiponectin and HR-QOL in Korean pre-dialysis CKD cohort. This cross-sectional study analyzed 1551 pre-dialysis CKD patients from KNOW-CKD (KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease). Participants were categorized into three tertiles (T1–T3) according to adiponectin levels. HR-QOL was assessed using SF-36. High physical component summary (PCS) and mental component summary (MCS) were defined as highest quartile of each score. Multivariate logistic regression was used to analyze odds ratio (OR) and 95% confidence interval (CI) for high PCS and MCS. Prevalence of high PCS were 33.3%, 27.5%, and 17.0% and that of high MCS were 31.7%, 24.8%, and 21.3% for T1, T2, and T3 (both p for trend < 0.001). The adjusted OR [95% CI] of T1 and T2 in reference to T3 were 1.56 [1.09–2.23] and 1.19 [0.85–1.68] for high PCS and 1.19 [0.85–1.68] and 0.94 [0.68–1.29] for high MCS. Serum adiponectin level was inversely associated with physical HR-QOL in Korean pre-dialysis CKD patients. This relationship was independent of various cardiovascular risk factors.

Relation of Adiponectin to Cardiovascular Events and Mortality in Patients With Acute Coronary Syndrome

The association between serum adiponectin levels and cardiovascular events, particularly how adiponectin predicts the development of cardiovascular events and mortality in acute coronary syndrome (ACS) patients remains unresolved. Hence, we aimed to determine whether higher adiponectin levels predict cardiovascular events and mortality in these patients. Regression analyses were performed to clarify adiponectin's ability to predict cardiovascular events and mortality among 1,641 ACS patients. Subgroup analyses were performed according to gender, age, and body mass index (BMI). The primary end point was a composite of the first all-cause death, nonfatal myocardial infarction, or nonfatal stroke event. The secondary end point was all-cause death. Hazard ratios for the primary and secondary end points per 5-µg/ml increase in adiponectin levels were 1.31 (95% confidence interval [CI], 1.13 to 1.47; p = 0.0007) and 1.32 (95% CI, 1.13 to 1.51; p = 0.001), respectively. Higher adiponectin levels were associated with increased cardiovascular events in men, patients aged ≥65 years, and those with BMI <25 kg/m². In conclusion, higher adiponectin levels were associated with increased cardiovascular events and all-cause mortality in ACS patients. Its predictive ability might be limited in women, patients aged <65 years, and patients with BMI ≥25 kg/m².

Serum anti-inflammatory and inflammatory markers have no causal impact on telomere length: a Mendelian randomization study

INTRODUCTION

The relationship between inflammatory and anti-inflammatory markers and telomere length (TL), a biological index of aging, is still poorly understood. By applying a 2-sample Mendelian randomization (MR), we investigated the causal associations between adiponectin, bilirubin, C-reactive protein (CRP), leptin, and serum uric acid (SUA) with TL.

MATERIAL AND METHODS

MR was implemented by using summary-level data from the largest ever genome-wide association studies (GWAS) conducted on our interested exposure and TL. Inverse variance weighted method (IVW), weighted median (WM)-based method, MR-Egger, MR-Robust Adjusted Profile Score (RAPS), and MR-Pleiotropy RESidual Sum and Outlier (PRESSO) were applied. Sensitivity analysis was conducted using the leave-one-out method.

RESULTS

With regard to adiponectin, CRP, leptin, and SUA levels, we found no effect on TL for all 4 types of tests (all p > 0.108). Results of the MR-Egger (p = 0.892) and IVW (p = 0.124) showed that bilirubin had no effect on telomere maintenance, whereas the results of the WM (p = 0.030) and RAPS (p = 0.022) were negative, with higher bilirubin concentrations linked to shorter TL. There was a low likelihood of heterogeneity for all the estimations, except for bilirubin (IVW p = 0.026, MR Egger p = 0.018). MR-PRESSO highlighted no outlier. For all the estimations, we observed negligible intercepts that were indicative of low likelihood of the pleiotropy (all p > 0.161). The results of leave-one-out method demonstrated that the links are not driven because of single nucleotide polymorphisms (SNPs).

CONCLUSIONS

Our results highlight that neither the anti-inflammatory nor pro-inflammatory markers tested have any significant causal effect on TL. The casual role of bilirubin on TL still needs to be investigated.

Active surveillance in prostate cancer management: where do we stand now?

Prostate cancer (PCa) is the most common cancer in men, with a steadily rising incidence, affecting on average one in six men during their lifetime. The increase in morbidity is related to the increasing overall life expectancy, prostate-specific antigen testing, implementation of new molecular markers for cancer detection and the more frequent application of multiparametric magnetic resonance imaging. There is growing evidence demonstrating that active surveillance (AS) is an alternative to immediate intervention in patients with very low- and low-risk prostate cancer. Ongoing reports from multiple studies have consistently demonstrated a very low rate of metastases and prostate cancer specific mortality in selected cohorts of patients. As a matter of fact, AS has been adopted by many institutions as a safe and effective management strategy. The aim of our review is to summarize the contemporary data on AS in patients affected with PCa with the intention to present the most clinically useful and pertinent AS protocols.

Update on the Crosstalk Between Adipose Tissue and Mineral Balance in General Population and Chronic Kidney Disease

Adipose tissue is nowadays considered as a major endocrine organ, which apart from controlling lipid metabolism, displays a significant role in energy expenditure, food intake and in the regulation of various systemic physiological processes. Adipose derived pro-inflammatory cytokines and adipokines, particularly leptin and adiponectin, provide inter-communication of adipose tissue with various metabolic pathways, ultimately resulting in a complex network of interconnected organ systems. Recent clinical and experimental research has been focused on exploring the direct interaction between adipokine profile and elements of mineral metabolism, including parathormone (PTH), fibroblast growth factor-23 (FGF23) and calcitriol. The emerging crosstalk between adipose tissue and calcium and phosphorus homeostasis suggests that metabolic disorders from one system may directly affect the other and vice versa. It is current knowledge that fat metabolism disturbance, commonly encountered in obese individuals, influences the expression of calciotriopic hormones in general population, while various clinical trials attempting to successfully achieve body fat loss by modulating mineral profile have been published. In chronic kidney disease (CKD) state, there is an increasing evidence suggesting that mineral disorders, influence adipose tissue and linked endocrine function. On the contrary, the impact of disturbed fat metabolism on CKD related mineral disorders has been also evocated in clinical studies. Recognizing the pathogenetic mechanisms of communication between adipose tissue and mineral balance is critical for understanding the effects of metabolic perturbations from the one system to the other and for identifying possible therapeutic targets in case of disrupted homeostasis in one of the two connected systems. To that end, this review aims to enlighten the recent advances regarding the interplay between mineral metabolism, fat mass and adipokine profile, based on in vitro, in vivo and clinical studies, in general population and in the course of CKD.

Is microvascular dysfunction a systemic disorder with common biomarkers found in the heart, brain, and kidneys? - A scoping review

Although microvascular dysfunction (MVD) has been well characterized in individual organs as different disease entities, clinical evidence is mounting in support of an underlying systemic process. To address this hypothesis, we systematically searched PubMed and Medline for studies in adults published between 2014 and 2019 that measured blood biomarkers of MVD in three vital organs i.e. brain, heart, and the kidney. Of the 9706 unique articles 321 met the criteria, reporting 49 biomarkers of which 16 were common to the three organs. Endothelial dysfunction, inflammation including reactive oxidation, immune activation, and coagulation were the commonly recognized pathways. Triglyceride, C-reactive protein, Cystatin C, homocysteine, uric acid, IL-6, NT-proBNP, thrombomodulin, von Willebrand Factor, and uric acid were increased in MVD of all three organs. In contrast, vitamin D was decreased. Adiponectin, asymmetric dimethylarginine, total cholesterol, high-density and low-density cholesterol were found to be variably increased or decreased in studies. We review the pathways underlying MVD in the three organs and summarize evidence supporting its systemic nature. This scoping review informs clinicians and researchers in the multi-system manifestation of MVD. Future work should focus on longitudinal investigations to evaluate the multi-system involvement of this disease.

Adiponectin in Chronic Kidney Disease

Adiponectin is the adipokine associated with insulin sensitization, reducing liver gluconeogenesis, and increasing fatty acid oxidation and glucose uptake. Adiponectin is present in the kidneys, mainly in the arterial endothelium and smooth muscle cells, as well as in the capillary endothelium, and might be considered as a marker of many negative factors in chronic kidney disease. The last few years have brought a rising body of evidence that adiponectin is a multipotential protein with anti-inflammatory, metabolic, anti-atherogenic, and reactive oxygen species (ROS) protective actions. Similarly, adiponectin has shown many positive and direct actions in kidney diseases, and among many kidney cells. Data from large cross-sectional and cohort studies showed a positive correlation between serum adiponectin and mortality in chronic kidney disease. This suggests a complex interaction between local adiponectin action, comorbidities, and uremic milieu. In this review we discuss the role of adiponectin in chronic kidney disease.

Elevated levels of adiponectin associated with major adverse cardiovascular and cerebrovascular events and mortality risk in ischemic stroke

BACKGROUND

Adiponectin plays role in multiple metabolic pathways. Previous studies in cardiovascular disease evaluated the association between adiponectin and clinical outcomes, yielding conflicting results. The aim of this study was to investigate the association of adiponectin with major adverse cardiovascular and cerebrovascular events (MACCE) and mortality in Chinese patients with first-ever acute ischemic stroke (AIS).

METHODS

This was a prospective, multicenter cohort study. From September 2009 through October 2015, all patients with AIS from 3 stroke centers in Shandong were included. Serum levels of adiponectin at admission were tested. The prognostic role of adiponectin to predict the MACCE and mortality within 3 years was evaluated by multivariable-adjusted Cox proportional hazards models.

RESULTS

This study included 4274 patients (median age 68 years [interquartile ranges {IQR}: 61-76]; 53.2% men). There were 794 deaths and 899 MACCE events. Higher serum levels of adiponectin on admission were found in patients with MACCE events and nonsurvivors (P < 0.001 and P < 0.001). In multivariable models adjusted for factors that confirmed in the univariate model, elevated serum levels of adiponectin were associated with a higher risk of MACCE (Quartile[Q]4 vs. Q1, Hazard ratio[HR] = 4.95 [95% confidence interval {CI}: 3.03-7.06]) and mortality (Q4 vs. Q1, HR = 5.63 [95% CI 3.15-7.99]). Adiponectin improved the prognostic value of the National Institutes of Health Stroke Scale (NIHSS) to predict MACCE (combined areas under the curve [AUC], 0.76; 95% CI 0.68-0.88; P = 0.001) and mortality (0.78[0.69-0.91]; P < 0.01). Subgroups analysis indicated that the prognostic role of adiponectin was more pronounced in women and patients with high levels of N-terminal-pro B-type natriuretic peptide(NT-pro BNP) (P < 0.001 and P < 0.001).

CONCLUSIONS

Elevated serum levels of adiponectin were associated with a higher risk of MACCE and mortality independent of traditional risk factors in ischemic stroke patients.

Early diagnosis with ultrasensitive ELISA

Accurate, rapid and simple detection methods are required to facilitate early diagnosis of various disorders including infectious and lifestyle diseases as well as cancer. These detection approaches reduce the window of infection, i.e., the period between infection and reliable detection. Optimally, these methods should target protein as an indicator of pathogenic microbes as well as other biomarkers. For example, although nucleic acid is easily detected by polymerase chain reaction (PCR), these markers are also present in dead microbes, and, in the case of mRNA, it is not known whether this target was successfully translated. Accordingly, early diagnostic approaches require the development of ultrasensitive protein detection methods. In this chapter, we introduce an ultrasensitive enzyme-linked immunosorbent assay (ELISA) which combines a traditional sandwich-based immunoassay with thionicotinamide adenine dinucleotide (thio-NAD) cycling. The performance characteristics of this unique approach are reviewed as well as its potential role in providing a novel and ultrasensitive diagnostic tool in the clinical laboratory.

High serum adiponectin as a biomarker of renal dysfunction: Results from the KNOW-CKD study

High serum adiponectin is noted in several conditions of chronic kidney disease (CKD) and is a predictor for end stage renal disease. However, the relationship between adiponectin level and renal disease progression is not well established. This study aimed to determine the relationship between serum adiponectin levels and CKD progression. This prospective longitudinal study included 2238 patients from the Korean Cohort Study for Outcomes in Patients with Chronic Kidney Disease. Patients were divided into quartiles according to their serum adiponectin level. Composite renal outcome was defined as one or more of the following: initiation of dialysis or transplantation, a two-fold increase in baseline serum creatinine levels, or a 50% decline in the estimated glomerular filtration rate (eGFR) during the follow-up period. A cox proportional hazard ratio model was applied to analyze the relationship between composite renal outcome and serum adiponectin levels. Serum adiponectin level was inversely associated with eGFR (p < 0.001) and positively correlated with urine albumin-creatinine ratio. The highest quartile of serum adiponectin was associated with an increased risk of adverse renal outomes (HR, 1.39; 95%CI, 1.05-1.84; p=0.021). On time-dependent receiver operating characteristic curve analysis, predictive ability of adiponectin for renal outcomes disappeared after adjusting for eGFR. Therefore, serum adiponectin may be a biomarker of renal dysfunction rather than a true risk factor in CKD progression.

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.

Plasma adiponectin is a potential biomarker for organ involvement in male Fabry disease patients

Fabry disease is an X-linked lysosomal storage disorder caused by pathogenic variants in GLA. It manifests in hemizygous males and in many heterozygous females. Cardiovascular and renal involvement are frequent. Adiponectin is a circulating hormone that has been linked to numerous disease conditions including heart and kidney failure. In the present pilot study, we investigated plasma adiponectin levels in a cohort of 56 individuals with a genetic diagnosis of Fabry disease. Adiponectin levels did not differ between patients and controls. However, in male patients, significantly decreased adiponectin levels were associated with cardiovascular manifestation, while increased levels were associated with renal involvement. Similar trends in female patients did not reach statistical significance. Lyso-Gb3, a metabolite with good diagnostic/screening performance, was not indicative of organ involvement. In combination, adiponectin and Lyso-Gb3 may be of value for identification and stratification of Fabry patients. A potential additional relevance for prognosis and monitoring should be addressed by future studies in larger cohorts.

The association of adiponectin with metabolic syndrome and clinical outcome in patients with non-diabetic chronic kidney disease

Adiponectin is the most abundant circulating adipokine, and it has insulin-sensitizing and anti-inflammatory properties. Although it has been speculated that kidney function decline associated with elevated adiponectin is attributable to decreased renal clearance and compensatory responses to adiponectin resistance, it is unclear how elevated adiponectin affects clinical outcomes in chronic kidney disease (CKD) patients and whether the effects are the same as those in the general population. Therefore, the aim of this study is to examine whether the association between serum adiponectin levels and clinical outcomes in non-diabetic CKD patients is independent of adiposity and metabolic syndrome. We enrolled 196 non-diabetic CKD patients with eGFR ranging between 10 and 60 mL/min/1.73 m2, these patients were divided into two groups based on the presence of metabolic syndrome. The primary endpoint was all-cause mortality or renal events (renal failure requiring renal replacement therapy [RRT] or 50% reduction in eGFR). During the mean follow-up period of 5 years, 48 (24.5%) incident cases of end-stage renal disease (ESRD) were observed, and 33 (16.8%) deaths occurred. The mean eGFR was 29.8 ± 12.8 mL/min/1.73m2. The baseline median adiponectin concentration in the cohort was 29.4(interquartile range, 13.3-108.7) μg/ml. Adiponectin levels were inversely related to body mass index (BMI) (r = -0.29; P < 0.001) and waist circumference (r = -0.35; P < 0.001). In the fully adjusted Cox regression model, the hazard ratios (HRs) were 2.08 (95% confidence interval [CI], 1.08-4.02; P = 0.03) for RRT and 1.66 (95% CI, 1.03-2.65; P = 0.04) for composite renal outcome. The risks remained consistent within different subgroups. However, no association was observed with mortality risk. In conclusion, higher adiponectin levels are associated with a higher risk of ESRD independent of conventional risk factors, BMI, and metabolic syndrome components.

Prospective Study of Sex-Specific Adiponectin Changes and Incident Metabolic Syndrome: The ARIRANG Study

We investigated whether changes in adiponectin levels over time predict incident metabolic syndrome (MetS) in a population-based prospective study. In total, 1110 subjects were categorized into four groups according to their sex-specific median baseline adiponectin levels and the change in adiponectin levels at follow-up: low baseline adiponectin and decreased adiponectin during follow-up (LB&DF), low baseline adiponectin and increased adiponectin during follow-up (LB&IF), high baseline adiponectin and decreased adiponectin during follow-up (HB&DF), and high baseline adiponectin and increased adiponectin during follow-up (HB&IF). During the median 2.4-year follow-up period, 180 (16.2%) subjects developed MetS. Compared to the LB&DF group, the fully adjusted hazard ratio (95% confidence interval) for incident MS was the lowest in the HB&IF group (0.33, (0.17–0.63)), followed by the HB&DF group (0.58, (0.40–0.84)) and LB&IF group (0.63, (0.41–0.93)). This phenomenon was more prominent in men than in women. Among the individual MetS components, increased adiponectin levels during follow-up were significantly associated with lower risks of incident low high density lipoprotein (HDL) cholesterol and incident high blood pressure. This finding suggests that a change in adiponectin level, as well as the baseline adiponectin level, might have a clinical role in the development of MetS among men.

Adiponectin Receptor gene Polymorphisms are Associated with Kidney Function in Elderly Japanese Populations

Aim: Adiponectin exhibits its biological effects through adiponectin receptors (AdipoR1 and AdipoR2), which are distributed in the kidneys, and activation of those receptors could prevent or ameliorate diabetic nephropathy. This study aimed to evaluate the associations between AdipoR single nucleotide polymorphisms (SNPs) and kidney function in an elderly Japanese population.

Methods: A total of 271 elderly Japanese volunteers underwent anthropometric and laboratory tests (cystatin C-based eGFR and total and high molecular weight adiponectin levels at baseline and a follow-up visit). Genotype data were obtained for the selected 7 and 5 AdipoR1 and AdipoR2 SNPs, respectively.

Results: In a cross-sectional analysis at baseline, we found a significant association between the AdipoR2 SNP rs12230440 and kidney function; eGFRcys tended to increase as the number of carriers of T alleles increased after adjustment for covariates and Bonferroni correction, although the association of the SNP and annual eGFR decline could not be identified in the longitudinal data. Regarding the variants rs16850797, rs11061925, and rs10773983, each of the allele G, allele C, and allele G showed nominally significant associations with higher eGFRcys. However, this failed to reach significance after Bonferroni correction.

Conclusion: Here, an AdipoR2 SNP was associated with kidney function, suggesting that the effects of this polymorphism on adiponectin receptor may affect kidney function in the elderly Japanese population.

Cisplatin nephrotoxicity as a model of chronic kidney disease

Cisplatin (CP)-induced nephrotoxicity is widely accepted as a model for acute kidney injury (AKI). Although cisplatin-induced chronic kidney disease (CKD) in rodent has been reported, the role of phosphate in the cisplatin-induced CKD progression is not described. In this study, we gave a single peritoneal injection of CP followed by high (2%) phosphate diet for 20 weeks. High dose CP (20 mg/Kg) led to high mortality; whereas a lower dose (10 mg/Kg) resulted in a full spectrum of AKI with tubular necrosis, azotemia, and 0% mortality 7 days after CP injection. After consuming a high phosphate diet, mice developed CKD characterized by low creatinine clearance, interstitial fibrosis, hyperphosphatemia, high plasma PTH and FGF23, low plasma 1,25(OH)₂ Vitamin D₃ and αKlotho, and classic uremic cardiovasculopathy. The CP model was robust in demonstrating the effect of aging, sexual dimorphism, and dietary phosphate on AKI and also AKI-to-CKD progression. Finally, we used the CP-high phosphate model to examine previously validated methods of genetically manipulated high αKlotho and therapy using exogenous soluble αKlotho protein supplementation. In this CP CKD model, αKlotho mitigated CKD progression, improved mineral homeostasis, and ameliorated cardiovascular disease. Taken together, CP and high phosphate nephrotoxicity is a reproducible and technically very simple model for the study of AKI, AKI-to-CKD progression, extrarenal complications of CKD, and for evaluation of therapeutic efficacy.

Role of Adiponectin in Central Nervous System Disorders

Adiponectin, the most abundant plasma adipokine, plays an important role in the regulation of glucose and lipid metabolism. Adiponectin also possesses insulin-sensitizing, anti-inflammatory, angiogenic, and vasodilatory properties which may influence central nervous system (CNS) disorders. Although initially not thought to cross the blood-brain barrier, adiponectin enters the brain through peripheral circulation. In the brain, adiponectin signaling through its receptors, AdipoR1 and AdipoR2, directly influences important brain functions such as energy homeostasis, hippocampal neurogenesis, and synaptic plasticity. Overall, based on its central and peripheral actions, recent evidence indicates that adiponectin has neuroprotective, antiatherogenic, and antidepressant effects. However, these findings are not without controversy as human observational studies report differing correlations between plasma adiponectin levels and incidence of CNS disorders. Despite these controversies, adiponectin is gaining attention as a potential therapeutic target for diverse CNS disorders, such as stroke, Alzheimer's disease, anxiety, and depression. Evidence regarding the emerging role for adiponectin in these disorders is discussed in the current review.

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.

T-cadherin gene variants are associated with nephropathy in subjects with type 1 diabetes

Background

High plasma adiponectin levels are associated with diabetic nephropathy (DN). T-cadherin gene (CDH13) variants have been shown to be associated with adiponectin levels. We investigated associations between allelic variations of CDH13 and DN in subjects with type 1 diabetes.

Methods

Two CDH13 polymorphisms were analysed in 1297 Caucasian subjects with type 1 diabetes from the 'Survival Genetic Nephropathy' (SURGENE) (n = 340, 10-year follow-up), 'Genesis France-Belgium' (GENESIS) (n = 501, 5-year follow-up for n = 462) and 'Génétique de la Néphropathie Diabétique' (GENEDIAB) (n = 456, 9-year follow-up for n = 283) cohorts. Adiponectin levels were measured in plasma samples from GENESIS and GENEDIAB cohorts.

Results

Pooled analysis of GENEDIAB and GENESIS studies showed that baseline plasma adiponectin levels were higher in subjects with established/advanced DN at inclusion (P < 0.0001) and in subjects who developed end-stage renal disease (ESRD) at follow-up (P < 0.0001). The minor allele of rs3865188 was associated with lower adiponectin levels (P = 0.006). rs11646213 [odds ratio (OR) 1.47; 95% confidence interval (CI) 1.18-1.85; P = 0.0009] and rs3865188 (OR 0.71; 95% CI 0.57-0.90; P = 0.004) were associated with baseline prevalence of established/advanced DN. These polymorphisms were also associated with the risk of ESRD (0.006 < P < 0.03). The association between rs11646213 (but not rs3865188) and renal function remained significant after adjustment for plasma adiponectin. In SURGENE, rs11646213 [hazard ratio (HR) 1.69; 95% CI 1.01-2.71; P = 0.04] and rs3865188 (HR 0.74; 95% CI 0.55-0.99; P = 0.04) were associated with risk of renal events (defined as progression to more severe DN stages).

Conclusions

Plasma adiponectin levels are associated with the prevalence of DN and the incidence of ESRD in patients with type 1 diabetes. CDH13 polymorphisms are also associated with the prevalence and incidence of DN, and with the incidence of ESRD in these patients. The association between CDH13 and DN may be due to pleiotropic effects, both dependent and independent of plasma adiponectin levels.

Adiponectin attenuates kidney injury and fibrosis in deoxycorticosterone acetate-salt and angiotensin II-induced CKD mice

Adiponectin (ApN) is a multifunctional adipokine. However, high, rather than low, concentrations of ApN are unexpectedly found in patients with chronic kidney disease (CKD) via an as yet unknown mechanism, and the role of ApN in CKD is unclear. Herein, we investigated the effect of ApN overexpression on progressive renal injury resulting from deoxycorticosterone acetate-salt (DOCA) and angiotensin II (ANG II) infusion using a transgenic, inducible ApN-overexpressing mouse model. Three groups of mice [wild type receiving no infusion (WT) and WT and cytochrome P450 1a1 (cyp1a1)-ApN transgenic mice (ApN-Tg) receiving DOCA+ANG II infusion (WT/DOCA+ANG II and ApN-Tg/DOCA+ANG II)] were assigned to receive normal food containing 0.15% of the transgene inducer indole-3-carbinol (I3C) for 3 wk. In the I3C-induced ApN-Tg/DOCA+ANG II mice, not the WT or WT/DOCA+ANG II mice, overexpression of ApN in liver resulted in 3.15-fold increases in circulating ApN compared with nontransgenic controls. Of note, the transgenic mice receiving DOCA+ANG II infusion were still hypertensive but had much less albuminuria and glomerular and tubulointerstitial fibrosis, which were associated with ameliorated podocyte injury determined by ameliorated podocyte loss and foot process effacement, and alleviated tubular injury determined by ameliorated mRNA overexpression of kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin and mRNA decreases of cubilin and megalin in tubular cells, compared with WT/DOCA+ANG II mice. In addition, renal production of NF-κB-p65, NAPDH oxidase 2, and p47 ^phox and MAPK-related cellular proliferation, which were induced in WT/DOCA+ANG II mice, were markedly reduced in ApN-Tg/DOCA+ANG II mice. These results indicate that elevated ApN in the CKD mouse model is renal protective. Enhancing ApN production or signaling may have therapeutic potential for CKD.

Adiponectin is not associated with renal function decline in community-dwelling elderly adults

Adiponectin secreted by adipocytes plays an important role in the regulation of glucose and fatty acid metabolism. Contrary to findings in patients with chronic kidney disease (CKD), no prospective data about the association of serum adiponectin with renal function decline in the general population have yet appeared. Our objective was to analyze the relationship of total and high molecular weight (HMW) adiponectin with renal function decline as measured by cystatin C in community-dwelling elderly adults without moderate or severe CKD.In a prospective observational analysis, a total of 216 healthy elderly volunteers with eGFRcys ≥60 mL/min/1.73 m underwent anthropometric and laboratory tests at baseline and at follow-up visits. A subgroup with serum samples collected 5 years apart was further analyzed.There were no differences in either total or HMW adiponectin level between subjects subsequently undergoing rapid renal function decline and subjects with normal physiologic renal function decline (P = .71, P = .81). On univariate linear regression, neither total nor HMW adiponectin were associated with annual renal function decline (β = -0.23; P = .71, β = -0.057; P = .90). Multivariate analysis did not show a significant contribution of either total or HMW adiponectin to annual renal function decline (β = -0.50; P = .46, β = 0.01; P = .98). In the logistic regression analysis, we did not observe any statistically significant association of serum adiponectin levels with rapid renal function decline or incidence of CKD.Contrary to findings in populations with CKD, neither total nor HMW adiponectin had a substantial association with renal function decline in an elderly population with eGFRcys ≥60 mL/min/1.73 m. Our results and conclusions should not be extrapolated to subjects with other characteristics.

Relationship Between Metabolic Syndrome Severity and Kidney Function as Related to Gender: A Population-Based Longitudinal Study

The purpose of this study was to explore the relationship between the metabolic syndrome severity Z-score and kidney function by gender. We also examined the estimated glomerular filtration rate in relation to other known risk factors. The study used was a population-based prospective longitudinal research design. A total of 4,838 participants (2,683 females and 2,155 males) included individuals aged >30 years who were undergoing a health examination from 2006 to 2014 in Pingzhen City, Taiwan. In the initial generalized estimated equation model analysis, which included the covariates of age of first visit, period between the first and current visit, and metabolic syndrome severity Z-score, the results indicated that the interaction between age and metabolic syndrome severity Z-score is significantly related to the estimated glomerular filtration rate for males (p = .040). For females, the interaction between age and metabolic syndrome severity Z-score was not significant, but a higher metabolic syndrome severity Z-score was significantly associated with lower estimated glomerular filtration rate (p = .001). After controlling for the confounders, unhealthy behaviors, and comorbidities, the metabolic syndrome severity Z-score was still a negative predictor of estimated glomerular filtration rate in both the male (p = .005) and female (p = .023) models.

Long-term study of the association of adipokines and glucose variability with diabetic complications

BACKGROUND/AIMS

Recent studies have suggested an important role of adipokines in the development of insulin resistance and diabetes mellitus. The clinical relevance of adipokines on long-term outcomes in patients with diabetes and chronic kidney disease is uncertain. The purpose of this study was to identify a predictable factor in patients with long-term diabetic complications.

METHODS

A total of 161 diabetic individuals were followed-up from 2002 to 2013. Circulating plasma levels of adiponectin, glypican-4, irisin, visfatin, and visit-to-visit glucose variability were measured in diabetic patients. Associations among adipokines and variable metabolic parameters and microvascular, and macrovascular complications were evaluated.

RESULTS

Plasma adiponectin and glypican-4 levels were significantly increased in patients with renal insufficiency. These adipokines were negatively associated with estimated glomerular filtration rate and positively associated with urinary albumin excretion. The relative risk of renal progression to dialysis increased independently with increasing level of adiponectin. Glypican-4 and visfatin were not predictive of any microvascular or macrovascular complications. Glucose variability increased the risk of diabetic nephropathy and cerebrovascular complications.

CONCLUSIONS

Adiponectin and glypican-4 were associated with renal function and might be able to predict renal progression. Glucose variability was a predictable factor for diabetic nephropathy and cerebrovascular complications.

The Adiponectin Paradox for All-Cause and Cardiovascular Mortality

Basic science studies have shown beneficial effects of adiponectin on glucose homeostasis, chronic low-grade inflammation, apoptosis, oxidative stress, and atherosclerotic processes, so this molecule usually has been considered a salutary adipokine. It was therefore quite unexpected that large prospective human studies suggested that adiponectin is simply a marker of glucose homeostasis, with no direct favorable effect on the risk of type 2 diabetes and cardiovascular disease. But even more unforeseen were data addressing the role of adiponectin on the risk of death. In fact, a positive, rather than the expected negative, relationship was reported between adiponectin and mortality rate across many clinical conditions, comprising diabetes. The biology underlying this paradox is unknown. Several explanations have been proposed, including adiponectin resistance and the confounding role of natriuretic peptides. In addition, preliminary genetic evidence speaks in favor of a direct role of adiponectin in increasing the risk of death. However, none of these hypotheses are based on robust data, so further efforts are needed to unravel the elusive role of adiponectin on cardiometabolic health and, most important, its paradoxical association with mortality rate.

High glucose instigates tubulointerstitial injury by stimulating hetero-dimerization of adiponectin and angiotensin II receptors

Abnormal expression and dysfunction of adiponectin and the cognate receptors are involved in diabetes and diabetic kidney disease (DKD), whereas angiotensin receptor blockers (ARBs) and angiotensin-converting enzyme inhibitors (ACEIs) alleviate diabetic albuminuria and prevent development of DKD through upregulation of adiponectin expression. Here we report that high glucose stimulates expression of angiotensin II (AngII) receptors (AT1 and AT2) in renal proximal tubular epithelial cells (NRK-52E). These receptors underwent hetero-dimerization with adiponectin receptor AdipoR1 and AdipoR2, respectively. High glucose inhibited the dimerization between AT1 and AT2. Interestingly, these hetero-dimers instigated tubulointerstitial injury by inhibiting the cytoprotective action of the adiponectin receptors. These modes of receptor-receptor hetero-dimerization may contribute to high glucose-induced renal tubulointerstitial injury and could be potential therapeutic targets.

Serum adiponectin and protein-energy wasting in predialysis chronic kidney disease

OBJECTIVE

Adiponectin (ADPN) has antiatherogenic, anti-inflammatory, and insulin-sensitizing effects. Serum ADPN levels are increased in patients with chronic kidney diseases (CKD), and higher ADPN is paradoxically a predictor of mortality in these patients. The aim of this study was to determine the association between serum ADPN levels and protein-energy wasting (PEW) in predialysis CKD.

METHOD

We examined serum ADPN concentrations and PEW in 1303 patients from the KNOW-CKD (KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease) study. PEW was defined as the presence of three or more of the following four indicators: serum albumin <3.8 g/dL, body mass index <23 kg/m², urine creatinine excretion (UCE) below the lower quartile, and daily dietary protein intake <0.6 g/kg. We analyzed the association between PEW and ADPN using a multivariate regression model after adjustment for socioeconomic factors, comorbidities, and laboratory findings.

RESULTS

Among 1303 predialysis CKD patients, 72 (5.5%) had PEW. In multivariate logistic regression analysis, higher ADPN level was associated with PEW (odds ratio, 1.04; 95% confidence interval [CI], 1.01-1.08 by 1 μg/mL ADPN). The highest ADPN quartile was associated with PEW in comparison with the lowest quartile (odds ratio, 10.54; 95% CI, 1.28-86.74). In multiple linear regression with PEW indicators, ADPN was more strongly associated with UCE (β = -2.21; 95% CI, -4.13 to -0.28; R² = 0.67).

CONCLUSION

High ADPN is independently associated with PEW. Among PEW indicators, serum ADPN is closely associated with UCE as an indirect measure of muscle mass.

The effects of adiponectin and inflammatory cytokines on diabetic vascular complications in obese and non-obese patients with type 2 diabetes mellitus

AIMS

To evaluate the associations between inflammatory cytokines and adiponectin and various vascular complications in type 2 diabetes mellitus (T2DM).

METHODS

A total of 761 patients with T2DM were divided into a non-obese group and an obese group to enable the effects of obesity and T2DM on vascular complications to be differentiated. The serum levels of circulating inflammatory cytokines, that is, tumor necrosis factor (TNF)-α, and interleukin (IL)-6, total adiponectin, and high molecular weight (HMW) adiponectin were measured, and carotid intima media thickness (IMT), the presence of carotid plaque, and the severities of retinopathy and nephropathy, were assessed.

RESULTS

The obese group had significantly lower serum total and HMW adiponectin levels than the non-obese group. In the obese group, serum levels of total and HMW adiponectin, and TNF-α were significantly higher in patients with proliferative retinopathy than in those without retinopathy after adjusting for covariates. In the non-obese group, only IL-6 levels were significantly higher in patients with proliferative retinopathy than in those without. Serum levels of total and HMW adiponectin were significantly higher in patients with macroalbuminuria than in those with normoalbuminuria. No significant difference of three cytokines levels were observed depending on the carotid IMT or the presence of plaque. Logistic regression analysis revealed that serum total adiponectin (OR=1.209, P=0.038), diabetes duration (OR=1.230, P=0.014), and HbA1c (OR=2.359, P=0.006) were significantly associated with proliferative retinopathy in the obese group.

CONCLUSION

The study shows total adiponectin may influence proliferative retinopathy in obese patient with T2DM.

Hypoadiponectinemia and the presence of metabolic syndrome in patients with chronic kidney disease: results from the KNOW-CKD study

BACKGROUND

In patients with chronic kidney disease, metabolic syndrome has been demonstrated to be the culprit behind diverse complications. Adiponectin is known to have anti-atherogenic and cardio-protective effects. Meanwhile, the relationship between adiponectin and metabolic syndrome in patients with chronic kidney disease has not been clarified. The aim of this study was to elucidate the relationship between adiponectin level and metabolic syndrome in patients with chronic kidney disease.

METHODS

The KoreaN Cohort Study for Outcome in Patients with Chronic Kidney Disease is a cohort study that enrolled subjects with chronic kidney disease throughout South Korea. From February 2011 to July 2014, data were collected from 1332 patients with chronic kidney disease.

RESULTS

The mean age of the patients was 53.5 years and 803 patients (60.7%) were men. The median adiponectin level was 10.7 μg/mL and 585 (44.3%) patients had metabolic syndrome. In multiple linear regression analysis, log adiponectin was positively associated with high-density lipoprotein cholesterol levels (β = 0.006), whereas it was negatively associated with serum albumin (β = -0.284), triglyceride (log β = -0.288), high sensitivity C-reactive protein (log β = -0.058) levels and estimated glomerular filtration rate (β = -0.005). Multiple logistic regression analysis indicated that low adiponectin level was independently associated with a higher risk of metabolic syndrome (per 1 μg/mL increase; odds ratio = 0.953, 95% confidence interval = 0.898-0.970, P < 0.001) after adjustment for multiple confounding factors.

CONCLUSIONS

Hypoadiponectinemia is independently associated with the presence of metabolic syndrome in patients with chronic kidney disease.

Subattomole detection of adiponectin in urine by ultrasensitive ELISA coupled with thio-NAD cycling

Adiponectin is a hormone secreted from adipocytes, and it demonstrates antidiabetic, anti-atherosclerotic, antiobesity and anti-inflammatory effects. However, the patterns of change in urinary adiponectin levels in various diseases remain unknown, because only trace amounts of the hormone are present in urine. In the present study, we applied an ultrasensitive ELISA coupled with thio-NAD cycling to measure urinary adiponectin levels. Spikeand-recovery tests using urine confirmed the reliability of our ultrasensitive ELISA. The limit of detection for adiponectin in urine was 2.3×10⁻¹⁹ moles/assay (1.4 pg/mL). The urinary adiponectin concentration ranged between 0.04 and 5.82 ng/mL in healthy subjects. The pilot study showed that the urinary adiponectin levels, which were corrected by the creatinine concentration, were 0.73±0.50 (ng/mg creatinine, N=6) for healthy subjects, versus 12.02±3.85 (ng/mg creatinine, N=3) for patients with diabetes mellitus (DM). That is, the urinary adiponectin levels were higher (P<0.05) in DM patients than in healthy subjects. Further, these urinary adiponectin levels tended to increase with the progression of DM accompanied with nephropathy. Our method is thus expected to provide a simple, rapid and reasonably priced test for noninvasive monitoring of the progression of DM without the requirement of special tools.

Adiponectin in children and young adults with focal segmental glomerulosclerosis

BACKGROUND

Adiponectin is an adipokine that is elevated in kidney disease. Evidence suggests that adiponectin exerts a direct effect on the podocyte and may play a role in the pathogenesis of proteinuria. The objectives of this study were to characterize serum and urine adiponectin levels over time in patients with focal segmental glomerulosclerosis (FSGS) and to evaluate the role of baseline levels of adiponectin as a predictor of clinical remission.

METHODS

This was a study of 60 individuals, ages 3-38 years, with steroid-resistant FSGS enrolled in the FSGS clinical trial. Serial measurements of serum and urine adiponectin were obtained at baseline and 26 and 52 weeks.

RESULTS

Participants were of mean age 19.4 ± 10.2 years (50% male, 33% black). Serum adiponectin (baseline mean 14.3 ± 6.6 μg/ml) and urine adiponectin:creatinine (Uadp/cr) (baseline mean 126.8 ± 178.9 μg/ml) directly correlated with proteinuria at all time points (r = 0.37-0.81; all p < 0.05). Proteinuria, hypoalbuminemia, and hyperlipidemia were significant independent predictors of greater serum adiponectin and Uadp/cr in multivariate analysis. Lower tertiles of baseline serum adiponectin were associated with greater response to treatment at 52 weeks when adjusted for age, sex, body mass index (BMI) z score, and estimated glomerular filtration rate (eGFR) [odds ratio (OR) 0.48; 95% confidence interval (CI) 0.26-0.91, p = 0.023). For log Uadp/cr, the OR for remission was 0.43 (95% CI 0.21-0.89, p = 0.02) at 52 weeks. However, when baseline urine protein:creatinine was added to the models, the relationships were no longer significant.

CONCLUSIONS

Serum and urine adiponectin levels were directly associated with proteinuria and paralleled changes in proteinuria over time in children and young adults with FSGS. Although baseline adiponectin was lower in responders, response to treatment in patients with FSGS was not associated with serum and urine adiponectin levels but, rather, was related to proteinuria.

Association of relative telomere length with progression of chronic kidney disease in two cohorts: effect modification by smoking and diabetes

Chronic kidney disease (CKD) is a highly progressive disease. We studied the association between relative telomere length (RTL) and CKD progression and tested whether this association is modified by smoking and diabetes mellitus. RTL was measured by qPCR in two prospective cohort studies, the MMKD-Study (n = 166) and the CRISIS-Study (n = 889) with a median follow-up of 4.5 and 2.8 years, respectively. Progression was defined as doubling of baseline serum creatinine (MMKD-Study) and/or end stage renal disease (both studies). 59 and 105 of the patients from MMKD and CRISIS experienced a progression of CKD. Mean standardized pooled RTL was 0.74 ± 0.29. In the meta-analysis shorter RTL at baseline showed a borderline association with CKD progression (HR = 1.07 [95%CI 1.00-1.15]; p = 0.06). We observed an effect modification of RTL and CKD progression by smoking and diabetes (p-values of interaction p = 0.02 and p = 0.09, respectively). Each 0.1 unit shorter RTL was significantly associated with an increased hazard for CKD progression in active-smokers by 44% (HR = 1.44 [1.16-1.81]; p = 0.001) and in patients with diabetes mellitus by 16% (HR = 1.16 [1.01-1.34]; p = 0.03). Estimates were adjusted for baseline age, sex, proteinuria and GFR. This study in two independent cohorts reinforces that RTL is a marker and potentially a pathogenetic factor for CKD progression.

Cardiovascular biomarkers in chronic kidney disease: state of current research and clinical applicability

The high incidence of cardiovascular events in chronic kidney disease (CKD) warrants an accurate evaluation of risk aimed at reducing the burden of disease and its consequences. The use of biomarkers to identify patients at high risk has been in use in the general population for several decades and has received mixed reactions in the medical community. Some practitioners have become staunch supporters and users while others doubt the utility of biomarkers and rarely measure them. In CKD patients numerous markers similar to those used in the general population and others more specific to the uremic population have emerged; however their utility for routine clinical application remains to be fully elucidated. The reproducibility and standardization of the serum assays are serious limitations to the broad implementation of these tests. The lack of focused research and validation in randomized trials rather than ad hoc measurement of multiple serum markers in observational studies is also cause for concern related to the clinical applicability of these markers. We review the current literature on biomarkers that may have a relevant role in field of nephrology.

Serum resistin and glomerular filtration rate in patients with type 2 diabetes

Background

High serum levels of the pro-inflammatory adipokine resistin have been associated with decreased renal function in the general population. The goal of this study was to investigate whether such association is also present among diabetic subjects, who are at increased risk of renal function loss.

Methods

The cross-sectional association between serum resistin levels and estimated glomerular filtration rate (eGFR) was investigated in 1,560 type 2 diabetic (T2D) patients of European ancestry comprised in two different cohorts: 762 patients from San Giovanni Rotondo (SGR; Italy) and 798 patients from Boston (US).

Results

Serum resistin was inversely associated with eGFR in SGR [β (SE) for one SD of resistin increment = -1.01 (0.70) ml/min/1.73m², p = 0.019] and in Boston [β (SE) = -5.31 (0.74) ml/min/1.73m², p < 0.001] samples, as well as in the two studies combined [β (SE) = -3.42 (0.52) ml/min/1.73m², p < 0.001]. The association was unaffected by adjustment for smoking habits, BMI, waist circumference, diabetes duration, HbA1c, insulin treatment, hypertension and lipid-lowering therapy: β (SE) for one SD of resistin increment = -1.07 (0.70), p = 0.02; -5.50 (0.88), p < 0.001; and -2.81 (0.55) ml/min/1.73m², p < .001, in SGR, Boston and the two studies combined, respectively. The association was significantly stronger in men than in women (p for resistin-by-gender interaction = 0.003). For each resistin SD increment, the odds of having eGFR < 0 ml/min/1.73m² increased by 22% (OR = 1.22; 95% CI 1.02–1.44; p = 0.025) in SGR sample, 69% (OR = 1.69; 95% CI 1.38–2.07; p < 0.001) in Boston sample, and 47% (OR = 1.47; 95% CI 1.29–1.68; p < 0.001) in the two studies considered together. Similar associations were observed in the adjusted model: OR 95% CI for each SD resistin increment being 1.23 (1.03–1.46), p = 0.021; 1.52 (1.20–1.92), p < 0.001; 1.33 (1.16–1.53), p < 0.001, in SGR, Boston and the two studies combined, respectively.

Conclusions

This is the first report of an association between high serum resistin and low eGFR in patients with T2D of European ancestry.

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

Background

Adiponectin and leptin, two of the key cytokines secreted by adipocytes, have been shown to be associated with cardiovascular disease. However, the association of these adipocytokines with chronic kidney disease (CKD) is not clear. We examined the association of serum adiponectin, leptin levels and leptin to adiponectin ratio (LAR) with CKD in a population-based sample of Asian adults.

Methods

We conducted a case-control study (450 CKD cases and 920 controls matched for age, sex and ethnicity) involving Chinese and Indian adults aged 40–80 years who participated in the Singapore Epidemiology of Eye Diseases Study (2007–2011). CKD was defined as an estimated glomerular filtration rate <60 mL/min/1.73m² from serum creatinine. Serum adiponectin and leptin levels were measured using commercially available ELISA. Odds ratio of CKD associated with elevated adiponectin and leptin levels were estimated using logistic regression models adjusted for age, gender, ethnicity, education, smoking, body mass index, diabetes, blood pressure, total and HDL cholesterol.

Results

CKD cases had higher levels of leptin (mean [SD] 9.7 [11.5] vs.16.9 [20.2] ng/mL, p<0.0001) and adiponectin (10.4 [7.4] vs. 9.2 [4.2], p = 0.001) compared to controls. In multi-variable models, compared to those in the lowest quartile, the OR (95% confidence interval) of CKD among those in the highest quartile were: 6.46 (3.84, 10.88), 1.94 (1.32–2.85) and 2.88 (1.78–4.64) for leptin, adiponectin and LAR. Similar associations were also observed when adiponectin and leptin were analyzed as continuous variables. This positive association of serum adiponectin, leptin and LAR with CKD was consistently present in subgroups of gender, ethnicity, diabetes, hypertension and overweight status (all P-interaction >0.1).

Conclusions

Higher levels of serum adiponectin, leptin and LAR were positively associated with CKD independent of traditional risk factors in this Asian population.

Association of adiponectin polymorphisms with the risk of diabetic nephropathy in type 2 diabetes: a meta-analysis

OBJECTIVE

Adiponectin gene polymorphisms have been reported to be associated with the risk of diabetic nephropathy (DN) in type 2 diabetes mellitus (T2DM) patients. However, the results are inconsistent.

METHODS

Electronic literature databases and reference lists of relevant articles published until December 2013 were searched as part of a systematic review and meta-analysis to clarify the association between adiponectin gene polymorphisms and DN susceptibility in T2DM. Fixed- or random-effects models were used to calculate the effect sizes of odds ratio (OR) and 95% confidence intervals (95% CI).

RESULTS

Eleven case control studies were included. Overall, a significant association was observed for rs2241766T/G polymorphisms under the recessive model (GG vs. TT+TG: OR 1.75; 95% CI 1.09-2.80; P = 0.02). For rs17300539G/A, a significant association was observed under the GA vs. GG model (OR 1.74; 95% CI 1.13-2.68; P = 0.01) and A vs. G allele model OR 1.65; 95% CI 1.13-2.41; P = 0.009). After stratification by ethnicity, we found that the rs2241766 T/G dominant model (GG+TG vs. TT: OR 1.52; 95% CI 1.12-2.07; P = 0.007), heterozygous model (TG vs. TT: OR 1.52; 95% CI 1.01-2.27; P = 0.04) and G vs. T allele (OR 1.50; 95% CI 1.07-2.10; P = 0.02) may be associated with DN risk in the Caucasian population. For rs17300593G/A, the dominant model (GA+AA vs. GG: OR 1.75; 95% CI 1.15-2.67; P = 0.009) may be associated with DN risk in the Caucasian population.

CONCLUSION

Adiponectin rs2241766T/G and rs17300593G/A rather than rs1501299G/T and rs266729C/G polymorphisms were associated with the risk of DN in T2DM, especially in the Caucasian population.

Association of serum adiponectin with diabetic microvascular complications among south Indian type 2 diabetic subjects - (CURES-133)

OBJECTIVES

To assess the association of serum adiponectin and microvascular complications of diabetes in an urban south Indian type 2 diabetic population.

DESIGN AND METHODS

Diabetic subjects [n=487] were included from Chennai Urban Rural Epidemiology Study (CURES). Four-field stereo retinal color photography was done and diabetic retinopathy (DR) was classified as non-proliferative DR (NPDR) or proliferative DR (PDR) according to the Early Treatment Diabetic Retinopathy Study grading system. Sight threatening DR (STDR) was defined as the presence of NPDR with diabetic macular edema, and/or PDR. Neuropathy was diagnosed if vibratory perception threshold of the great toe using biothesiometry exceeded ≥20V. Nephropathy was diagnosed if urinary albumin excretion (UAE) was ≥30μg/mg creatinine. Serum total adiponectin levels were measured by radioimmunoassay.

RESULTS

Subjects with any microvascular complications had significantly higher levels of adiponectin levels compared to those without the complications (geometric mean: 6.1 vs. 5.3μg/mL, p=0.004). The adiponectin level was significantly higher in subjects with DR (6.8 vs. 5.5μg/mL, p=0.004) and neuropathy (5.6 vs. 6.5μg/mL, p=0.024) compared to those without. Adiponectin levels were not significantly different in subjects with and without nephropathy. Serum adiponectin levels increased with the severity of DR [No DR - 5.5μg/mL; NPDR without DME - 6.5μg/mL; STDR - 8.3μg/mL, p=0.001]. Regression analysis revealed adiponectin to be associated with microvascular disease (presence of neuropathy and/or retinopathy and/or nephropathy) (OR: 1.44, 95% CI: 1.01-2.06, p=0.049) even after adjusting for age, gender, BMI, HbA1c, diabetes of duration, serum cholesterol and triglycerides, hypertension and medication status.

CONCLUSION

In Asian Indians with type 2 diabetes, serum adiponectin levels are associated with microvascular complications and also with the severity of retinopathy.

Adipokines protecting CKD

Increasing incidence of chronic kidney disease (CKD) which leads to end-stage renal disease (ESRD) is one of the major health issues in the modern world and requires novel strategies for treatment. Adipose tissue has been recognized to have endocrine function and secretes a variety of hormones called adipokines. Several adipokines have been implicated in the pathogenesis of CKD and may have a strong impact as a risk factor for renal decline. The aim of this review is to provide an overview of the role of adipokines in the progression of CKD, with focus on recent experimental and clinical advances.

The association of adiposity with kidney function decline among HIV-infected adults: findings from the Fat Redistribution and Metabolic Changes in HIV Infection (FRAM) study

OBJECTIVES

The aim of the study was to investigate the association of adiposity with longitudinal kidney function change in 544 HIV-infected persons in the Study of Fat Redistribution and Metabolic Change in HIV infection (FRAM) cohort over 5 years of follow-up.

METHODS

The regional distribution of muscle and adipose tissue was quantified by whole-body magnetic resonance imaging (MRI), and total adiponectin and leptin levels were measured in serum. Kidney function was assessed using the estimated glomerular filtration rate from serum cystatin C (eGFRCys), obtained at baseline and follow-up. Rapid kidney function decline was defined as annual loss of eGFRCys ≥ 3 mL/min/1.73 m(2) , and incident chronic kidney disease (CKD) was defined as eGFRCys <60 mL/min/1.73 m(2) . Multivariate regression analysis was adjusted for age, race, gender, glucose, antihypertensive use, serum albumin, baseline and change in HIV viral load.

RESULTS

At baseline, mean age was 43 years, mean eGFRCys was 86 mL/min/1.73 m(2) , and 21% of patients had albuminuria. The mean (± standard deviation) eGFRCys decline was -0.11 ± 4.87 mL/min/1.73 m(2) per year; 23% of participants had rapid kidney function decline, and 10% developed incident CKD. The lowest tertile of visceral adipose tissue and the highest tertile of adiponectin were both marginally associated with annual kidney function decline of -0.5 mL/min/1.73 m(2) each, but these associations were not statistically significant after adjustment. We found no statistically significant associations of MRI-measured regional adiposity or serum adipokines with rapid kidney function decline or incident CKD (all P-values>0.1 in adjusted models).

CONCLUSIONS

Contrary to findings in the general population, adiposity did not have a substantial association with longitudinal change in kidney function among HIV-infected persons.

Circulating adiponectin and cardiovascular mortality in patients with type 2 diabetes mellitus: evidence of sexual dimorphism

BACKGROUND

The pathogenesis of cardiovascular (CV) mortality, whose rate is increased in type 2 diabetes, is poorly understood.

METHODS

Three prospective cohorts were analyzed: 1) Gargano Heart Study (GHS; 359 patients, 58 events/1,934 person-years; py); 2) Health Professional Follow-up Study (HPFS; 833 men, 146 events/10,024 py); 3) Nurses' Health Study (NHS; 902 women, 144 events/15,074 py).

RESULTS

In GHS serum adiponectin predicted CV mortality in men (hazard ratio, HR, and 95% CI per standard deviation, SD, increment = 1.54, 1.19-2.01), but not women (HR = 0.98, 0.48-2.01).

CONCLUSIONS

This is the first report showing that high circulating adiponectin predicts increased CV mortality in men, but not in women with type 2 diabetes. Further studies are necessary to unravel the mechanisms through which adiponectin influences CV mortality in a sex-specific manner.

Impact of metabolic disturbances and malnutrition-inflammation on 6-year mortality in Japanese patients undergoing hemodialysis

Metabolic syndrome confers an increased risk of cardiovascular disease (CVD) in the general population. The relationship between adiponectins, and clinical outcomes in patients undergoing hemodialysis remains controversial. We investigated whether adiponectins, biomarkers of inflammation, nutrition status and clinical features predict the mortality of patients undergoing hemodialysis for 6 years. We measured baseline plasma total and high-molecular-weight (HMW) adiponectins, tumor necrosis factor (TNF)-α, serum high sensitivity C-reactive protein (hsCRP), and clinical characteristics including visceral fat area (VFA) and the Geriatric Nutritional Risk Index (GNRI) in 133 patients undergoing chronic hemodialysis. Forty-one of the 133 patients died during follow-up. The deceased patients were significantly older, had more prior CVD and diabetes, higher TNF-α and hsCRP levels but lower GNRI. VFA, and total and HMW adiponectin did not significantly differ between the two groups. TNF-α and hsCRP levels and GNRI score were significant for predicting all-cause and cardiovascular mortality in receiver operating curve analyses. When stratified by a GNRI score of 96, Cox proportional hazards analyses identified TNF-α as a significant predictor of all-cause mortality (hazard ratio [HR] 1.23; P = 0.038) and hsCRP as a significant predictor of all-cause and cardiovascular mortality (HR, 2.32, P = 0.003; HR 2.30, P = 0.012, respectively) after adjusting for age, sex, diabetes mellitus, and prior CVD, only in malnourished patients. These results demonstrate that malnutrition and the inflammatory markers TNF-α and hsCRP, but not metabolic markers, including VFA and adiponectins have a significant impact on 6-year all-cause and cardiovascular mortality in Japanese patients undergoing hemodialysis.