Urinary adiponectin concentration is positively associated with micro- and macro-vascular complications

Influence of birth-related maternal and neonatal factors on the levels of energy metabolism mediators in infants born at 32 or fewer weeks of gestation

BACKGROUND

Energy metabolism mediators, which include the adipokines (leptin, adiponectin, ghrelin) and insulin-like growth factor 1 [IGF-1], are hormone-like proteins, produced and expressed in the placenta and fetal membranes, with properties featuring metabolic adaptation and inflammatory processes. Due to the complexity of the metabolic adaptation of preterm neonates during the transition to extrauterine life, it becomes essential to recognize the factors that influence the alteration of the adipokines and IGF-1 levels in the early postpartum stage.This study assessed the significance of maternal-fetal-neonatal factors in predicting the levels of leptin, adiponectin, ghrelin, and IGF-1 in preterm infants born at 32 or fewer weeks of gestation, during the early stage of postnatal adaptation.

METHODS

Energy metabolism mediator levels were measured in urine samples obtained from extremely (less than 28 weeks) and very (28-32 weeks) preterm infants, within 48 h after their birth, and before the initiation of enteral nutrition. The urine samples were analyzed using enzyme-linked immunosorbent assay (ELISA) kits. The collected data included all birth-related maternal and neonatal factors such as maternal age, race/ethnicity, hypertensive disorders of pregnancy, diabetes, gravidity, parity, type of pregnancy, mode of delivery, and antenatal use of corticosteroids, antibiotics, magnesium sulfate, Apgar scores at 1 and 5 min, gestational age, and birth weight. We investigated the correlation between the levels of the tested mediators, the significance of the differences in their average levels based on the dichotomized maternal and neonatal factors, and the effect of the selected factors, in multiple regression models. Data from the regression models constructed for leptin, adiponectin, ghrelin, and IGF-1 are presented as regression coefficient β with Standard Error (SE) of β, coefficient of determination (R2), and adjusted R2. Before including the factor in regression models, we tested for the multicollinearity effect. Two-sided P values <0.05 were considered statistically significant.

RESULTS

Among the 70 studied infants, 47.1% were male, 40.6% were white, 28.6% were extremely preterm, and 18.6% were born with a weight <750 grams. Except for a mild interplay between the adiponectin and IGF-1 levels, there was no correlation between the levels of the other studied mediators. Up to 20% variation in the tested energy metabolism mediator levels was dependent on some of the birth-related maternal and neonatal characteristics. For instance, leptin levels were reduced in association with male gender (-0.493 [0.190], p < 0.02) and increased in infants born to primigravids (0.562 [0.215], p < 0.02). Adiponectin levels were increased in infants born to nulliparous as compared to multiparous women (0.400 [0.171], p < 0.03). Ghrelin levels were reduced in males (-0.057 [0.026], p < 0.04). IGF-1 levels were increased in the urine of extremely preterm neonates (0.357 [0.111], p < 0.01) and preterm infants born with an Apgar less than three at 1 min (0. 340 [p < 0.153], p < 0.04).

CONCLUSIONS

Nearly one-fifth of the variation in the urinary levels of the adipokines (leptin, adiponectin, ghrelin) and IGF-1 during the early postnatal stage in infants born at 32 or fewer weeks of gestation was predicated on one or more of the maternal and neonatal factors such as the infant's sex, extreme preterm gestation, a low Apgar score at 1 min, or birth to nulliparous women or primigravida mothers. Further studies will be required to explain the role of energy metabolism mediators in the postnatal adaptation of preterm-born infants.

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.

Comparison of urinary adiponectin in the presence of metabolic syndrome in peri- and postmenopausal women

Objectives

To find the association between urinary adiponectin and metabolic syndrome (MetS) in peri- and postmenopausal women and its potential application as a noninvasive screening for MetS.

Methods

A cross-sectional study was conducted in healthy peri- and postmenopausal women (defined by STRAW + 10 staging) aged at least 40 years who attended annual check-ups or menopause clinics were recruited. Baseline demographic data, MENQOL, anthropometric measurements, blood pressure, laboratory (FBS, total cholesterol, HDL-C, LDL-C, TG), and urinary adiponectin were collected. The MetS was diagnosed according to JIS 2009.

Results

290 peri- and postmenopausal women had participated. The prevalence of Mets among our participants was 18%. Urinary adiponectin levels were similar in peri- and postmenopausal women with and without MetS (2.6 ± 2.2 vs. 2.3 ± 1.9 ng/mL, respectively, P = 0.55). Urinary adiponectin provides no diagnostic value for MetS (AUC = 0.516).

Conclusions

Urinary adiponectin has no role in screening and diagnosing MetS in peri- and postmenopausal women. The quest toward noninvasive screening for MetS is still going on.

Distribution of serum adiponectin isoforms in pediatric patients with steroid-sensitive nephrotic syndrome

BACKGROUND

Serum adiponectin circulates in three multimeric isoforms: high-molecular-weight (HMW), middle-molecular-weight (MMW), and low-molecular-weight (LMW) isoforms. Potential change in the circulating adiponectin levels in patients with nephrotic syndrome (NS) remain unknown. This study aimed to assess the levels of total adiponectin and the distribution of its isoforms in pediatric patients with NS.

METHODS

We sequentially measured total adiponectin and each adiponectin isoform levels at the onset of NS, initial remission, and during the remission period of the disease in 31 NS patients. We also calculated the ratios of HMW (%HMW), MMW (%MMW), and LMW (%LMW) to total adiponectin incuding 51 control subjects.

RESULTS

The median of total serum adiponectin levels in patients were 36.7, 36.7, and 20.2 μg/mL at the onset, at initial remission, and during the remission period of NS, respectively. These values were significantly higher than those in control subjects. The median values of %HMW, %MMW, and %LMW values were 56.9/27.0/14.1 at the onset, 62.0/21.8/13.4 at the initial remission, and 58.1/21.7/17.5 at during the remission period of NS, respectively. Compared with control subjects, %HMW at initial remission and %MMW at the onset were high, and the %LMW values at the onset and at initial remission were low.

CONCLUSIONS

In patients with NS, total serum adiponectin levels increase at the onset of the disease, and the ratio of adiponectin isoforms changes during the course of the disease. Further studies are needed to delineate the mechanisms between proteinuria and adiponectin isoforms change.

Contrasting short-term temperature effects on the profiling of metabolic and stress hormones in non-obese healthy adults: A randomized cross-over trial

The manifestation of elevated and sustained air temperature gradient profiles in urban dwellings represents an emerging planetary health phenomenon. There is currently limited evidence about the effect of elevated air temperatures on metabolic health. The aim of this work was to assess changes in metabolic and stress hormonal profiles during a short-term stay in a mountainous, climate-cooler setting against those observed in the urban setting. A prospective, randomized, 2 x 2 cross-over trial of non-obese healthy adults in urban and mountainous areas of a Mediterranean country (Cyprus) was set up during summer, under real-life conditions. The intervention was a short-term stay (mean ± SD: 7 ± 3 days) in a mountainous, climate-cooler setting (altitude range: 650-1200 m), being ~1-h drive away from the main urban centres of Cyprus. The primary endpoint was the change in metabolic hormones levels (leptin and adiponectin) and stress hormone levels (cortisol) between the two settings. Personal air and skin temperature sensors were deployed while biospecimen were collected in each setting. A total of 41 participants between 20 and 60 years old were enrolled and randomized during July 2018, of whom 39 received the allocated intervention, 8 were lost to follow up or excluded from analysis and a total of 31 participants were analysed. A significant leptin reduction (β = -0.255; 95% CI: -0.472, -0.038; p = 0.024) was observed for non-obese healthy adults during their short-term stay in the mountainous environment. The intervention effect on adiponectin or cortisol levels was not statistically significant (β = 0.058; 95% CI: -0.237, 0.353; p = 0.702), and (β = -0.026; 95% CI: -0.530, 0.478; p = 0.920), respectively. In additional analyses, daily max skin temperature surrogate measures were significantly associated with leptin levels (β = 0.34; 95% CI: 0.051, 0.633; p = 0.024). During summer season, a short-term stay in climatologically cooler areas improved the leptin levels of non-obese healthy adults who permanently reside in urban areas of a Mediterranean country. A larger sample is needed to confirm the trial findings that could provide the rationale for such public health interventions in climate-impacted urban areas of our planet.

Renal protective effects of induction of haem oxygenase-1 combined with increased adiponectin on the glomerular vascular endothelial growth factor-nitric oxide axis in obese rats

What is the central question of this study? This study aimed to investigate whether induction of haem oxygenase-1 (HO-1) can protect the kidneys of obese rats by regulating the glomerular vascular endothelial growth factor-nitric oxide (VEGF-NO) axis by increasing the adiponectin concentrations. What is the main finding and its importance? Induction of HO-1 reduces the degree of microalbuminuria and has renal protective effects by improving endothelial function and regulating the uncoupled glomerular VEGF-NO axis in diet-induced obese rats. The mechanism may be related to increased activation of the HO-1-adiponectin axis. The glomerular vascular endothelial growth factor-nitric oxide (VEGF-NO) axis plays a critical role in maintenance of normal kidney function in obesity. Induction of haem oxygenase-1 (HO-1) may result in a parallel increase in adiponectin secretion. The aim of this study was to investigate whether induction of HO-1 could protect the kidneys of obese rats by regulating the glomerular VEGF-NO axis by increasing adiponectin levels. Rats received high-fat diets and were injected with either cobalt protoporphyrin to induce HO-1 or stannous protoporphyrin to inhibit HO-1. Blood and urine samples were collected. Endothelial function was determined by measuring the endothelium-dependent vasodilatation of the aorta. Renal tissues were collected for CD34 immunohistochemistry. The glomerular VEGF-NO axis and the AMP kinase-phosphoinositide 3-kinase (PI3K)/Akt-endothelial nitric oxide synthase pathway were measured. Induction of HO-1 by cobalt protoporphyrin decreased microalbuminuria, plasma free fatty acids, serum high-sensitivity C-reactive protein and malondialdehyde levels and increased serum adiponectin levels compared with the untreated obese rats. Severe impairment of endothelium-dependent vasodilatation was observed in the obese rats, which was improved to some extent by HO-1 induction. Induction of HO-1 reduced glomerular CD34 expression and production of reactive oxygen species in obese rats. Obese rats showed increased glomerular VEGF expression and reduced NO levels. This uncoupling of the glomerular VEGF-NO axis was improved to some extent by induction of HO-1, with enhancement of p-AMP kinase, p-Akt and phospho-endothelial nitric oxide synthase in obese rats. These results indicate that induction of HO-1 with cobalt protoporphyrin reduces the degree of microalbuminuria and has renal protective effects by improving endothelial dysfunction and regulating the glomerular VEGF-NO axis in diet-induced obese rats by increasing adiponectin levels.

Adiponectin: a manifold therapeutic target for metabolic syndrome, diabetes, and coronary disease?

Adiponectin is the most abundant peptide secreted by adipocytes, being a key component in the interrelationship between adiposity, insulin resistance and inflammation. Central obesity accompanied by insulin resistance is a key factor in the development of metabolic syndrome (MS) and future macrovascular complications. Moreover, the remarkable correlation between coronary artery disease (CAD) and alterations in glucose metabolism has raised the likelihood that atherosclerosis and type 2 diabetes mellitus (T2DM) may share a common biological background. We summarize here the current knowledge about the influence of adiponectin on insulin sensitivity and endothelial function, discussing its forthcoming prospects and potential role as a therapeutic target for MS, T2DM, and cardiovascular disease. Adiponectin is present in the circulation as a dimer, trimer or protein complex of high molecular weight hexamers, >400 kDa. AdipoR1 and AdipoR2 are its major receptors in vivo mediating the metabolic actions. Adiponectin stimulates phosphorylation and AMP (adenosin mono phosphate) kinase activation, exerting direct effects on vascular endothelium, diminishing the inflammatory response to mechanical injury and enhancing endothelium protection in cases of apolipoprotein E deficiency. Hypoadiponectinemia is consistently associated with obesity, MS, atherosclerosis, CAD, T2DM. Lifestyle correction helps to favorably modify plasma adiponectin levels. Low adiponectinemia in obese patients is raised via continued weight loss programs in both diabetic and nondiabetic individuals and is also accompanied by reductions in pro-inflammatory factors. Diet modifications, like intake of fish, omega-3 supplementation, adherence to a Mediterranean dietary pattern and coffee consumption also increase adiponectin levels. Antidiabetic and cardiovascular pharmacological agents, like glitazones, glimepiride, angiotensin converting enzyme inhibitors and angiotensin receptor blockers are also able to improve adiponectin concentration. Fibric acid derivatives, like bezafibrate and fenofibrate, have been reported to enhance adiponectin levels as well. T-cadherin, a membrane-associated adiponectin-binding protein lacking intracellular domain seems to be a main mediator of the antiatherogenic adiponectin actions. The finding of novel pharmacologic agents proficient to improve adiponectin plasma levels should be target of exhaustive research. Interesting future approaches could be the development of adiponectin-targeted drugs chemically designed to induce the activaton of its receptors and/or postreceptor signaling pathways, or the development of specific adiponectin agonists.

Urinary excretion of high molecular weight adiponectin is an independent predictor of decline of renal function in type 2 diabetes

Adiponectin and urinary adiponectin excretions have been ascribed a function in glomerular physiology and seem to indicate vascular disease in diabetes. The aim of this study was to compare the urinary excretion of albumin and adiponectin as predictors for decline of renal function in patients with type 2 diabetes and early kidney disease. Over 141 patients were screened for renal function (estimated GFR, ml/min*1.73 m(2)), albumin excretion rate (AER, mg/24 h), total as well as high molecular weight (HMW) urinary adiponectin excretion (ng/mol u-creatinine). AER and adiponectin excretion were studied as predictors of renal function after 1 year. After 1 year, 36 patients were in the upper quartile of eGFR decline and defined as progressors (delta eGFR = - 12.3 ± 6.3) while the remaining 105 patients were defined as non-progressors (delta eGFR = 1.4 ± 6.0). At baseline, HMW-adiponectin excretion was positively correlated with HbA1c (p < 0.001) and negatively with eGFR (p < 0.001), but not with AER (p = 0.14). Progressors showed increased urinary HMW-adiponectin at baseline (158[IQR41/479] vs. 65[24/168] ng/mol; p < 0.01), while total adiponectin (182[101/1534] vs. 345[118/1361] ng/mol) and AER (48[23/109] vs. 46[25/108] mg/24 h) excretion showed no differences between the groups. Multivariate logistic regression showed that HMW-adiponectin excretion was an independent predictor of renal progression in all patients (OR 1.86 [95 % CI 1.34-2.59]; p < 0.01), especially in those (n = 45) with normal AER at baseline (OR 2.16 [95 % CI 1.1-4.56]; p < 0.05). Urinary HMW-adiponectin but not AER improved the prediction of progressors in ROC analysis (AUC 0.72 [95 % CI 0.63-0.81] vs. 0.80 [95 % CI 0.71-0.90], p < 0.05). In conclusion, urinary HMW-adiponectin excretion may identify diabetes patients at increased risk for progression of kidney disease.