Correlation of the leptin:adiponectin ratio with measures of insulin resistance in non-diabetic individuals

Diabetes mellitus and gynecologic cancer: molecular mechanisms, epidemiological, clinical and prognostic perspectives

INTRODUCTION

Diabetes mellitus, the prevalence of which has increased dramatically worldwide, may put patients at a higher risk of cancer. The aim of our study is the clarification of the possible mechanisms linking diabetes mellitus and gynecological cancer and their epidemiological relationship.

MATERIALS AND METHODS

This is a narrative review of the current literature, following a search on MEDLINE and the Cochrane Library, from their inception until January 2012. Articles investigating gynecologic cancer (endometrial, ovarian, and breast) incidence in diabetic patients were extracted.

RESULTS

The strong evidence for a positive association between diabetes mellitus and the risk for cancer indicates that energy intake in excess to energy expenditure, or the sequelae thereof, is involved in gynecological carcinogenesis. This risk may be further heightened by glucose which can directly promote the production of tumor cells by functioning as a source of energy. Insulin resistance accompanied by secondary hyperinsulinemia is hypothezised to have a mitogenic effect. Steroid hormones are in addition potent regulators of the balance between cellular differentiation, proliferation, and apoptosis. Inflammatory pathways may also be implicated, as a correlation seems to exist between diabetes mellitus and breast or endometrial carcinoma pathogenesis, although an analogous correlation with ovarian carcinoma is still under investigation. Antidiabetic agents have been correlated with elevated cancer risk, while metformin seems to lower the risk.

CONCLUSION

Diabetes mellitus is associated with an elevation in gynecologic cancer risk. Moreover, there are many studies exploring the prognosis of patients with diabetes and gynecological cancer, the outcome and the overall survival in well-regulated patients.

SFRP5 hepatic expression is associated with non-alcoholic liver disease in morbidly obese women

BACKGROUND AND AIMS

Secreted frizzled-related protein 5 (SFRP5) was recently described as a new adipokine protective for hepatic steatosis and other obesity-related complications in the mouse model. To date, SFRP5 expression in non-alcoholic fatty liver disease (NAFLD) has not been fully assessed in humans. We measured circulating SFRP5 levels and its expression in liver and adipose tissue, and evaluated its association with NAFLD in morbidly obese women.

MATERIAL AND METHODS

Fifty-four morbidly obese women undergoing bariatric surgery were included in the study. Liver biopsies were used for histology and hepatic triglyceride content quantification. Circulating SFRP5 levels were measured through enzyme-linked immunoabsorbent assay, and SFRP5 expression was performed in hepatic and adipose tissue (subcutaneous and visceral).

RESULTS

Although circulating SFRP5 levels showed a tendency to decrease with NAFLD progression, no significant differences were observed among non-alcoholic steatosis, steatohepatitis, and control subjects. Hepatic SFRP5 expression showed a negative correlation with hepatic triglyceride content (r = -0.349, P = 0.016 for mRNA and r = -0.291, P = 0.040 for SRFP5 protein) and ALT serum levels (r = -0.437, P = 0.001 for SRFP5 protein). In addition, hepatic SFRP5 protein levels were significantly lower in NASH than in control subjects (P = 0.006).

CONCLUSION

This is the first study reporting an association of hepatic SFRP5 expression with NAFLD in humans.

Diminished satellite cells and elevated adipogenic gene expression in muscle as caused by ovariectomy are averted by low-magnitude mechanical signals

Age-related degeneration of the musculoskeletal system, accelerated by menopause, is further complicated by increased systemic and muscular adiposity. The purpose of this study was to identify at the molecular, cellular, and tissue levels the impact of ovariectomy on adiposity and satellite cell populations in mice and whether mechanical signals could influence any outcomes. Eight-week-old C57BL/6 mice were ovariectomized, with one half subjected to low-intensity vibration (LIV; 0.3 g/90 Hz, 15 min/day, 5 day/wk; n = 10) for 6 wk and the others sham vibrated (OVX; n = 10). Data are compared with age-matched, intact controls (AC; n = 10). In vivo μCT analysis showed that OVX mice gained 43% total (P < 0.001) and 125% visceral adiposity (P < 0.001) compared with their baseline after 6 wk, whereas LIV gained only 21% total (P = 0.01) and 70% visceral adiposity (P < 0.01). Relative to AC, expression of adipogenic genes (PPARγ, FABP4, PPARδ, and FoxO1) was upregulated in OVX muscle (P < 0.05), whereas LIV reduced these levels (P < 0.05). Adipogenic gene expression was inversely related to the percentage of total and reserve satellite cell populations in the muscle, with both declining in OVX compared with AC (-21 and -28%, respectively, P < 0.01). LIV mitigated these declines (-11 and -17%, respectively). These results provide further evidence of the negative consequences of estrogen depletion and demonstrate that mechanical signals have the potential to interrupt subsequent adipogenic gene expression and satellite cell suppression, emphasizing the importance of physical signals in protecting musculoskeletal integrity and slowing the fat phenotype.

Role of thymol on hyperglycemia and hyperlipidemia in high fat diet-induced type 2 diabetic C57BL/6J mice

Thymol is a monoterpene phenol with many pharmacological activities, but their anti- hyperglycemic and anti-hyperlipidemic activities are not yet explored. This study evaluates the beneficial effects of thymol on plasma, hepatic lipids and hyperglycaemic effects in high-fat diet (HFD) induced type 2 diabetes in C57BL/6J mice. These mice were fed continuously with high fat diet (fat- 35.8%) for 10 weeks and subjected to intragastric administration of various doses (10mg, 20mg and 40mg/kg body weight (BW)) of thymol daily for the subsequent 5 weeks. Body weight (BW), food intake, plasma glucose, insulin, insulin resistance, HbA1c, leptin and adiponectin were significantly decreased and there was an increase in food efficacy ratio. Thymol supplementation were significantly lowered the concentration of plasma triglyceride (TG), total cholesterol (TC), free fatty acids (FFAs), low density lipoprotein (LDL) and increased high density lipoprotein (HDL) cholesterol as compared to the HFD induced diabetic group due to lipid enzymatic activity. Also, the hepatic lipid contents such as triglycerides, total cholesterol, free fatty acid and phospholipids (PL) were significantly lowered in the thymol supplemented groups. As compared to other two tested doses of 10mg and 20mg, thymol (40mg/kg BW) were showed significant protective effect on the parameters studied. Thus, indicate thymol protects C57BL/6J mice against HFD due to its anti-hyperglycaemic and anti-hyperlipidemic activity. The above outcome concludes that thymol may exhibit promising anti-diabetic activity.

Obesity, insulin resistance and comorbidities? Mechanisms of association

Overall excess of fat, usually defined by the body mass index, is associated with metabolic (e.g. glucose intolerance, type 2 diabetes mellitus (T2DM), dyslipidemia) and non-metabolic disorders (e.g. neoplasias, polycystic ovary syndrome, non-alcoholic fat liver disease, glomerulopathy, bone fragility etc.). However, more than its total amount, the distribution of adipose tissue throughout the body is a better predictor of the risk to the development of those disorders. Fat accumulation in the abdominal area and in non-adipose tissue (ectopic fat), for example, is associated with increased risk to develop metabolic and non-metabolic derangements. On the other hand, observations suggest that individuals who present peripheral adiposity, characterized by large hip and thigh circumferences, have better glucose tolerance, reduced incidence of T2DM and of metabolic syndrome. Insulin resistance (IR) is one of the main culprits in the association between obesity, particularly visceral, and metabolic as well as non-metabolic diseases. In this review we will highlight the current pathophysiological and molecular mechanisms possibly involved in the link between increased VAT, ectopic fat, IR and comorbidities. We will also provide some insights in the identification of these abnormalities.

GlycA, a biomarker of inflammatory glycoproteins, is more closely related to the leptin/adiponectin ratio than to glucose tolerance status

OBJECTIVES

Plasma GlycA is a recently developed biomarker whose nuclear magnetic resonance signal originates from glycosylated acute-phase proteins. The aim of our study was to determine potential relationships between GlycA and adiposity, insulin resistance (HOMA(ir)), high sensitive C-reactive protein (hs-CRP), leptin, adiponectin, and the leptin/adiponectin ratio, and to test whether GlycA is elevated in subjects with impaired fasting glucose (IFG) and type 2 diabetes mellitus (T2DM).

DESIGN AND METHODS

Plasma GlycA, hs-CRP, leptin, adiponectin, the leptin/adiponectin ratio, and insulin resistance (HOMA(ir)) were measured in 103 fasting subjects (30 with normal fasting glucose, 25 with IFG and 48 with T2DM).

RESULTS

In all subjects combined, plasma GlycA was correlated positively with body mass index (BMI), HOMA(ir), hs-CRP, leptin and the leptin/adiponectin ratio, and inversely with adiponectin (p < 0.05 to p < 0.001). GlycA did not significantly vary according to glucose tolerance category (p = 0.060). GlycA was related positively to the leptin/adiponectin ratio (p = 0.049), independent of BMI (p = 0.056) and HOMA(ir) (p = 0.50).

CONCLUSIONS

High plasma GlycA reflects a pro-inflammatory state. Adipose tissue-associated inflammatory processes could contribute to increased circulating levels of glycosylated acute-phase proteins.

Soluble receptor for advanced glycation end products as a potential biomarker to predict weight loss and improvement of insulin sensitivity by a very low calorie diet of obese human subjects

INTRODUCTION

Obesity is associated with low-grade systemic inflammation which is thought to trigger the development of comorbidities such as type 2 diabetes. The soluble receptor for advanced glycation end products (sRAGE) belongs to the innate immune system and has been linked to obesity, recently. The aim of the present study was to examine whether serum sRAGE concentrations are related to the grade of weight loss and improvement of insulin resistance due to a very low calorie diet (VLCD).

METHODS

22 severe obese subjects (Median Body Mass Index (BMI): 44.5kg/m(2)) were included in a dietary intervention study of 6month, consisting of a very low calorie formula diet phase (VLCD: 800kcal/d) for 12 weeks and a following 12 week weight maintenance phase. Fasting glucose, fasting insulin, adiponectin, leptin and sRAGE were determined from sera. Insulin sensitivity was estimated by Homeostasis Model Assessment (HOMA) index and leptin-to-adiponectin-ratio (LAR).

RESULTS

Mean body weight reduction by VLCD accounted to 21.7kg with a significant improvement of insulin resistance. At baseline, sRAGE serum levels were significantly inversely related to BMI (rS=-0.642, p=0.001) and HOMA (rS=-0.419, p=0.041). Of interest, sRAGE serum levels at baseline were significantly lower in study subjects with greater reduction of BMI (p=0.017). In addition, a significantly greater HOMA reduction was observed in subjects with lower sRAGE serum levels at baseline (p=0.006). Finally, correlation analysis revealed, that changes of sRAGE serum levels were significantly correlated to changes of BMI (rS=-0.650, p=0.022) during intervention.

CONCLUSION

Anti-inflammatory sRAGE might be a potential future biomarker to predict weight loss and improvement of insulin resistance by a VLCD whereby lower baseline sRAGE serum levels indicate a better outcome of the dietary intervention.

Association of adipokines and joint biomarkers with cartilage-modifying effects of weight loss in obese subjects

OBJECTIVES

To determine (1) the effects of weight loss in obese subjects on six adipokines and joint biomarkers; and (2) the relationship between changes in these markers with changes in cartilage outcomes.

DESIGN

Plasma levels of adiponectin, leptin, IL-6, COMP, MMP-3 and urine levels of CTX-II were measured at baseline and 12 months from 75 obese subjects enrolled in two weight-loss programs. Magnetic resonance imaging (MRI) was used to assess cartilage volume and thickness. Associations between weight loss, cartilage outcomes and markers were adjusted for age, gender, baseline BMI, presence of clinical knee OA, with and without weight loss percent.

RESULTS

Mean weight loss was 13.0 ± 9.5%. Greater weight loss percentage was associated with an increase in adiponectin (β = 0.019, 95% CI 0.012 to 0.026,) and a decrease in leptin (β = -1.09, 95% CI -1.37 to -0.82). Multiple regression analysis saw an increase in adiponectin associated with reduced loss of medial tibial cartilage volume (β = 14.4, CI 2.6 to 26.3) and medial femoral cartilage volume (β = 18.1, 95% CI 4.4 to 31.8). Decrease in leptin was associated with reduced loss of medial femoral volume (β = -4.1, 95% CI -6.8 to -1.4) and lateral femoral volume (β = -1.8, 95% CI -3.7 to 0.0). When weight loss percent was included in the model, only the relationships between COMP and cartilage volume remained statistically significant.

CONCLUSIONS

Adiponectin and leptin may be associated with cartilage loss. Further work will determine the relative contributions of metabolic and mechanical factors in the obesity-related joint changes.

Dietary exposure to the endocrine disruptor tolylfluanid promotes global metabolic dysfunction in male mice

Environmental endocrine disruptors are implicated as putative contributors to the burgeoning metabolic disease epidemic. Tolylfluanid (TF) is a commonly detected fungicide in Europe, and previous in vitro and ex vivo work has identified it as a potent endocrine disruptor with the capacity to promote adipocyte differentiation and induce adipocytic insulin resistance, effects likely resulting from activation of glucocorticoid receptor signaling. The present study extends these findings to an in vivo mouse model of dietary TF exposure. After 12 weeks of consumption of a normal chow diet supplemented with 100 parts per million TF, mice exhibited increased body weight gain and an increase in total fat mass, with a specific augmentation in visceral adipose depots. This increased adipose accumulation is proposed to occur through a reduction in lipolytic and fatty acid oxidation gene expression. Dietary TF exposure induced glucose intolerance, insulin resistance, and metabolic inflexibility, while also disrupting diurnal rhythms of energy expenditure and food consumption. Adipose tissue endocrine function was also impaired with a reduction in serum adiponectin levels. Moreover, adipocytes from TF-exposed mice exhibited reduced insulin sensitivity, an effect likely mediated through a specific down-regulation of insulin receptor substrate-1 expression, mirroring effects of ex vivo TF exposure. Finally, gene set enrichment analysis revealed an increase in adipose glucocorticoid receptor signaling with TF treatment. Taken together, these findings identify TF as a novel in vivo endocrine disruptor and obesogen in mice, with dietary exposure leading to alterations in energy homeostasis that recapitulate many features of the metabolic syndrome.

Endocrine determinants of changes in insulin sensitivity and insulin secretion during a weight cycle in healthy men

Objective

Changes in insulin sensitivity (IS) and insulin secretion occur with perturbations in energy balance and glycemic load (GL) of the diet that may precede the development of insulin resistance and hyperinsulinemia. Determinants of changes in IS and insulin secretion with weight cycling in non-obese healthy subjects remain unclear.

Methods

In a 6wk controlled 2-stage randomized dietary intervention 32 healthy men (26±4y, BMI: 24±2kg/m²) followed 1wk of overfeeding (OF), 3wks of caloric restriction (CR) containing either 50% or 65% carbohydrate (CHO) and 2wks of refeeding (RF) with the same amount of CHO but either low or high glycaemic index at ±50% energy requirement. Measures of IS (basal: HOMA-index, postprandial: Matsuda-ISI), insulin secretion (early: Stumvoll-index, total: tAUC-insulin/tAUC-glucose) and potential endocrine determinants (ghrelin, leptin, adiponectin, thyroid hormone levels, 24h-urinary catecholamine excretion) were assessed.

Results

IS improved and insulin secretion decreased due to CR and normalized upon RF. Weight loss-induced improvements in basal and postprandial IS were associated with decreases in leptin and increases in ghrelin levels, respectively (r = 0.36 and r = 0.62, p<0.05). Weight regain-induced decrease in postprandial IS correlated with increases in adiponectin, fT3, TSH, GL of the diet and a decrease in ghrelin levels (r-values between -0.40 and 0.83, p<0.05) whereas increases in early and total insulin secretion were associated with a decrease in leptin/adiponectin-ratio (r = -0.52 and r = -0.46, p<0.05) and a decrease in fT4 (r = -0.38, p<0.05 for total insulin secretion only). After controlling for GL associations between RF-induced decrease in postprandial IS and increases in fT3 and TSH levels were no longer significant.

Conclusion

Weight cycling induced changes in IS and insulin secretion were associated with changes in all measured hormones, except for catecholamine excretion. While leptin, adiponectin and ghrelin seem to be the major endocrine determinants of IS, leptin/adiponectin-ratio and fT4 levels may impact changes in insulin secretion with weight cycling.

Trial Registration

ClinicalTrials.gov NCT01737034

A clerodane diterpene inhibit adipogenesis by cell cycle arrest and ameliorate obesity in C57BL/6 mice

A clerodane diterpene, 16α-Hydroxycleroda-3, 13 (14) Z-dien-15, 16-olide (compound 1) isolated from Polyalthia longifolia had previously been reported as a new structural class of HMG-CoA reductase inhibitor apart from statins. Statins are known to be anti-adipogenic in nature. The distant structural similarity between compound 1 and lovastatin (polyketide class of compound) prompted us to investigate effects of diterpene compound 1 on adipogenesis and thereby obesity. High content microscopy proved diterpene compound 1 exhibits better anti-adipogenic activity and less toxicity in differentiating adipocytes. Moreover, it reduced expression levels of PPARγ, C/EBPα and GLUT4 during differentiation in a time and concentration dependent manner. Diterpene compound 1 during early differentiation reduced MDI induced-Akt/mTOR phosphorylation and expression of cell cycle proteins, and thereby halted mitotic clonal expansion, the decisive factor in early adipogenesis. Further, its anti-adipogenic activity was validated in murine mesenchymal cell-line C3H10T1/2 and human mesenchymal stem cell models of adipogenic differentiation. When compound 1 was administered along with HFD, for another 8 weeks in 2 month HFD fed overweight mice (with BMI > 30 and impaired glucose tolerance), it attenuated weight gain and epididymal fat accumulation. It improved body glucose tolerance, reduced HFD induced increase in total cholesterol and leptin/adiponectin ratio. All these effects were comparable with standard anti-obesity drug Orlistat with added edge of potently decreasing circulating triglyceride levels comparable with normal chow fed group. Histological analysis shows that compound 1 inhibit adipocyte hypertrophy and decreased steatosis in hepatocytes. Both in vivo and in vitro results demonstrate a potential value of compound 1 as a novel anti-adipogenic and anti-obesity agent.

Lifestyle-induced decrease in fat mass improves adiponectin secretion in obese adults

PURPOSE

Several studies have identified relationships between weight loss and adipokine levels; however, none have looked at the combined effect of aerobic exercise training with the consumption of a low- or a high-glycemic diet. We examined the effects of 12 wk of aerobic exercise combined with either a low-glycemic index diet (∼40 U) plus exercise (LoGIX) or a high-glycemic index diet (∼80 U) diet plus exercise (HiGIX) on plasma leptin and adiponectin (total and high molecular weight [HMW]) in 27 older obese adults (age = 65 ± 0.5 yr, body mass index = 34.5 ± 0.7 kg·m).

METHODS

Insulin sensitivity was calculated from an oral glucose tolerance test. Fasting HMW adiponectin and leptin were quantified from plasma samples obtained before the insulin sensitivity index obtained from the oral glucose tolerance test. Glucose and insulin measures were obtained before and every 30 min during the test. Dual-energy x-ray absorptiometry and computerized tomography were used to determine body composition and to quantify subcutaneous and visceral abdominal adiposity, respectively.

RESULTS

Fasting leptin was significantly decreased in both groups (LoGIX: preintervention = 33.8 ± 4.7, postintervention = 19.2 ± 4.5; HiGIX: preintervention = 27.9 ± 4.2, postintervention = 11.9 ± 2.2 ng·mL; P = 0.004), and HMW adiponectin was significantly increased (LoGIX: preintervention = 1606.9 ± 34.6, postintervention = 3502.3 ± 57; HiGIX: preintervention = 3704.8 ± 38.1, postintervention = 4284.3 ± 52.8 pg·mL; P = 0.003) after the 12-wk intervention. Total body fat was reduced after both interventions. Visceral fat mass was inversely correlated with HMW adiponectin, whereas subcutaneous fat correlated with leptin.

CONCLUSIONS

The data suggest that exercise training, independent of dietary glycemic index, favorably alters HMW adiponectin and leptin secretion and that a reduction in visceral fat mass is a key factor regulating HMW adiponectin in older obese persons.

Adipokines, inflammation, insulin resistance, and carotid atherosclerosis in patients with rheumatoid arthritis

Introduction

Cardiovascular (CV) morbidity and mortality are increased in patients with rheumatoid arthritis (RA). Inflammation is thought to be an important factor in accelerated atherosclerosis in RA, whereas insulin resistance is a known risk factor for atherosclerosis in RA. We hypothesised that adipokines could be a link between inflammation, insulin resistance, and atherosclerosis in RA.

Methods

The common carotid artery (CCA) intima-media thickness (IMT), CCA resistive index (RI), and carotid plaques were measured by ultrasonography in 192 patients with RA. Insulin resistance was assessed by the homeostasis model assessment for insulin resistance (HOMA-IR). Serum adiponectin, leptin, resistin, tumor necrosis factor-α, and interleukin (IL)-6 concentrations were determined.

Results

The CCA RI was associated with CCA IMT and the estimated total plaque volume after adjustment for conventional CV risk factors. Among adipokines, resistin and IL-6 were correlated with inflammatory parameters. Leptin and leptin:adiponectin (L:A) ratio were correlated with metabolic risk factors, including HOMA-IR. And L:A ratio was related to the CCA RI after adjustment for conventional and nonconventional CV risk factors, including HOMA-IR, erythrocyte sedimentation rate and C-reactive protein.

Conclusion

L:A ratio was associated with HOMA-IR and carotid RI. L:A ratio might be an independent factor for predicting cardiovascular risk in patients with RA.

Insulin resistance and adipokine levels correlate with early atherosclerosis - a study in prediabetic patients

Cardiovascular risk of prediabetes is still subject to controversies. We analyzed the associations between insulin resistance, adipokines and incipient atherosclerosis estimated by intima-media thickness (IMT) in a cross-sectional study on 122 prediabetic subjects without clinical signs of atherosclerotic disease. Homeostasis model assessment of insulin resistance (HOMA-IR, calculated as fasting insulin × fasting plasma glucose / 22.5), adiponectin, leptin, leptin-to-adiponectin ratio, carotid and femoral IMT were evaluated. We also assessed other parameters related to insulin resistance and adipokines (HbA_1c, anthropometric and lipid parameters), as they may also influence atherosclerosis. Carotid IMT was correlated to adiponectin and leptin-to-adiponectin ratio (all p < 0.05), but not with HOMA-IR or leptin, while femoral IMT showed no relationship with these factors. After adjusting for leptin, leptin-to-adiponectin ratio, triglycerides, HDL-cholesterol, cholesterol-to-HDL ratio, triglycerides-to-HDL ratio and HbA_1c, IMT values became correlated with HOMA-IR. Adjustment for HOMA-IR induced the appearance of new correlations between adipokines and both IMT values. In conclusion, insulin resistance and adipokines seem related to IMT in prediabetic subjects without clinical signs of arterial obstruction.

The association of asthma, nasal allergies, and positive skin prick tests with obesity, leptin, and adiponectin

BACKGROUND

Cross-sectional and longitudinal reports show that obese adults have more asthma than non-obese adults. A proposed mechanism is via effects of adipokines (leptin and adiponectin) on the immune system.

OBJECTIVE

We wished to measure the associations of asthma and other atopic diseases with serum adipokine levels and to find whether the associations with asthma were strong enough to rule out the possibility that they are secondary to the association of fatness measures with asthma.

METHODS

The Global Asthma and Allergy Network of Excellence (GA(2) LEN) clinical follow-up survey is a clinical survey, embedded in a larger multi-centre cross-sectional postal survey, involving, with a case/control design, enrichment of the sample with subjects with asthma and chronic rhinosinusitis (CRS). We recorded serum leptin or adiponectin in 845 men and 1110 women in 15 centres and also anthropometric measures of fatness including body mass index and waist/hip ratio, current asthma, and specific skin prick and IgE sensitisation. We used inverse sampling-probability-weighted rank and regression statistics to measure population associations of disease outcomes with adipokines in males and females, adjusting for confounders (area, age, smoking history, and number of elder siblings) and also mutually adjusting associations with adipokines and fatness measures.

RESULTS

One thousand nine hundred and fifty-five subjects aged 16-77 years had information on leptin or adiponectin levels. Leptin and leptin/adiponectin ratio were positively associated with the level of asthma, especially in females (Somers' D of leptin by asthma score, 0.20; 95% CI, 0.08-0.30; P = 0.00079). These associations were attenuated after adjusting for confounders and became non-significant after additionally adjusting for fatness measures and multiple comparisons.

CONCLUSIONS AND CLINICAL RELEVANCE

Asthma levels are positively associated with serum leptin. However, we cannot rule out the possibility that this association is secondary to associations of both with fatness measures.

Fine-tuned iron availability is essential to achieve optimal adipocyte differentiation and mitochondrial biogenesis

AIMS/HYPOTHESIS

Adipose tissue from obese and insulin-resistant individuals showed altered expression of several iron-related genes in a recent study, suggesting that iron might have an important role in adipogenesis. To investigate this possible role, we aimed to characterise the effects of iron on adipocyte differentiation.

METHODS

Intracellular iron deficiency was achieved using two independent approaches: deferoxamine administration (20 and 100 μmol/l) and transferrin knockdown (TF KD). The effects of added FeSO4, holo-transferrin and palmitate were studied during human and 3T3-L1 adipocyte differentiation. Finally, the relationship between iron-related and mitochondrial-related genes was investigated in human adipose tissue.

RESULTS

Most adipose tissue iron-related genes were predominantly expressed in adipocytes compared with stromal vascular cells. Of note, transferrin gene and protein expression increased significantly during adipocyte differentiation. Both deferoxamine and TF KD severely blunted adipocyte differentiation in parallel with increased inflammatory mRNAs. These effects were reversed in a dose-dependent manner after iron supplementation. Palmitate administration also led to a state of functional intracellular iron deficiency, with decreased Tf gene expression and iron uptake during adipocyte differentiation, which was reversed with transferrin co-treatment. On the other hand, iron in excess impaired differentiation, but this antiadipogenic effect was less pronounced than under iron chelation. Of interest, expression of several genes involved in mitochondrial biogenesis occurred in parallel with expression of iron-related genes both during adipogenesis and in human adipose tissue.

CONCLUSIONS/INTERPRETATION

Precise and fine-tuned iron availability is essential to achieve optimal adipocyte differentiation, possibly modulating adipocyte mitochondrial biogenesis.

SFRP5 correlates with obesity and metabolic syndrome and increases after weight loss in children

OBJECTIVE

Secreted frizzled-related protein 5 (SFRP5) is a novel anti-inflammatory adipokine, which has been shown as a mediator between obesity and its comorbidities. The aim of this study was to evaluate the associations of SFRP5 with metabolic syndrome (MetS) and the effects of lifestyle interventions on circulating SFRP5 levels in children.

DESIGN

A cross-sectional study was conducted among 111 obese children and 49 lean controls, and a lifestyle intervention was performed in a subgroup of 31 obese children for 6 months. Anthropometric parameters, clinical data and circulating SFRP5 levels were measured at baseline and after lifestyle intervention.

RESULTS

Secreted frizzled-related protein 5 was significantly lower in obese children, especially in those with MetS, and negatively correlated with body mass index (BMI), waist circumference and homeostasis model assessment of insulin resistance. Independent of other well-known risk factors, SFRP5 was a significant predictor of MetS in children. In the longitudinal study, lifestyle intervention led to significant weight loss and higher SFRP5 levels. Furthermore, changes in BMI significantly correlated with the rising magnitude of SFRP5.

CONCLUSIONS

Serum SFRP5 is regulated by weight status and seems to be correlated with metabolic disorders in children.

Increased leptin/adiponectin ratio and free leptin index are markers of insulin resistance in obese girls during pubertal development

BACKGROUND

Modifications in body fat in obese patients during puberty determine changes in adipokines that affect insulin sensitivity.

AIMS

We hypothesized that the leptin/adiponectin (L/A) ratio and free leptin index (FLI) are good markers of insulin resistance (IR) and total body fat (TBF) during pubertal development.

METHODS

A prospective study of 32 obese girls (OG) and age-matched control girls (CG) was performed. OG were divided into those that maintained a weight loss (WL) of >1 SD of initial body mass index (BMI) (WL group, n = 25) and those without WL (NWL group, n = 7). Oral glucose tolerance tests (OGTT) were performed to evaluate IR. Correlations of adipokines, L/A, and FLI with BMI, waist circumference, percentage of TBF (%TBF) and IR were performed over pubertal development.

RESULTS

The L/A ratio and FLI were increased in OG at baseline. Both indexes decreased in the WL group as puberty progressed, with no change in CG or NWL. In the WL group, a correlation between L/A and FLI with OGTT and %TBF, and L/A and homeostasis model assessment (HOMA) was found throughout the study.

CONCLUSION

The L/A ratio and FLI are good markers to follow changes in IR and %TBF after WL during puberty. Insulin more accurately reflects the changes in IR than HOMA.

Fast food fever: reviewing the impacts of the Western diet on immunity

While numerous changes in human lifestyle constitute modern life, our diet has been gaining attention as a potential contributor to the increase in immune-mediated diseases. The Western diet is characterized by an over consumption and reduced variety of refined sugars, salt, and saturated fat. Herein our objective is to detail the mechanisms for the Western diet's impact on immune function. The manuscript reviews the impacts and mechanisms of harm for our over-indulgence in sugar, salt, and fat, as well as the data outlining the impacts of artificial sweeteners, gluten, and genetically modified foods; attention is given to revealing where the literature on the immune impacts of macronutrients is limited to either animal or in vitro models versus where human trials exist. Detailed attention is given to the dietary impact on the gut microbiome and the mechanisms by which our poor dietary choices are encoded into our gut, our genes, and are passed to our offspring. While today's modern diet may provide beneficial protection from micro- and macronutrient deficiencies, our over abundance of calories and the macronutrients that compose our diet may all lead to increased inflammation, reduced control of infection, increased rates of cancer, and increased risk for allergic and auto-inflammatory disease.

Leptin-to-Adiponectin Ratio is Related to Low Grade Inflammation and Insulin Resistance Independent of Obesity in Non-Diabetic Taiwanese: A Cross-Sectional Cohort Study

BACKGROUND

Leptin and adiponectin are secreted from adipose tissue and exert opposing effects on C-reactive protein (CRP) levels and insulin resistance. As hypertrophic adipocytes secrete more leptin and less adiponectin, the leptin-to adiponectin ratio (LAR) has been proposed as a useful measure of insulin resistance and vascular risk. We investigated whether LAR may serve as a better predictor than either leptin or adiponectin alone for low-grade inflammation and insulin resistance independent of obesity in a non-diabetic Taiwanese population.

METHODS

This study included 568 non-diabetic Taiwanese individuals (297 men, 271 women). CRP, leptin and adiponectin were measured using enzyme-linked immunosorbent assay. The degree of insulin resistance was determined using the homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

In the receiver operator characteristic analysis, the area under the curve of LAR in predicting individuals with elevated CRP and insulin resistance was significantly greater than that for either leptin (p = 0.0035 vs. elevated CRP, p < 0.0001 vs. insulin resistance) or adiponectin alone (p = 0.0131 vs. elevated CRP, p = 0.0006 vs. insulin resistance), suggesting that LAR might be a better predictor of individuals with low grade inflammation and insulin resistance. In the multivariable analysis adjusted for age, gender, smoking status, and components of metabolic syndrome, LAR was still strongly associated with levels of CRP (p < 0.001, all participants; p = 0.002, nonobese individuals; p < 0.001, obese individuals) and HOMA-IR index (p < 0.001, all participants, obese and nonobese individuals).

CONCLUSIONS

The LAR is related to low grade inflammation and insulin resistance independent of obesity in non-diabetic Taiwanese, and the strength of associations between LAR with CRP and HOMA-IR are greater than the association with leptin or adiponectin alone.

KEY WORDS

Adiponectin; C-reactive protein; Insulin resistance; Leptin; Obesity.

B Lymphocyte Stimulator (BLyS) is expressed in human adipocytes in vivo and is related to obesity but not to insulin resistance

Inflammation and metabolism have been shown to be evolutionary linked and increasing evidence exists that pro-inflammatory factors are involved in the pathogenesis of obesity and type 2 diabetes. Until now, most data suggest that within adipose tissue these factors are secreted by cells of the innate immune system, e. g. macrophages. In the present study we demonstrate that B lymphocyte stimulator (BLyS) is increased in human obesity. In contrast to several pro-inflammatory factors, we found the source of BLyS in human adipose tissue to be the adipocytes rather than immune cells. In grade 3 obese human subjects, expression of BLyS in vivo in adipose tissue is significantly increased (p<0.001). Furthermore, BLyS serum levels are elevated in grade 3 human obesity (862.5+222.0 pg/ml vs. 543.7+60.7 pg/ml in lean controls, p<0.001) and are positively correlated to the BMI (r = 0.43, p<0.0002). In the present study, bariatric surgery significantly altered serum BLyS concentrations. In contrast, weight loss due to a very-low-calorie-formula-diet (800 kcal/d) had no such effect. To examine metabolic activity of BLyS, in a translational research approach, insulin sensitivity was measured in human subjects in vivo before and after treatment with the human recombinant anti-BLyS antibody belimumab. Since BLyS is known to promote B-cell proliferation and immunoglobulin secretion, the present data suggest that adipocytes of grade 3 obese human subjects are able to activate the adaptive immune system, suggesting that in metabolic inflammation in humans both, innate and adaptive immunity, are of pathophysiological relevance.

Retinol binding protein 4 concentrations relate to enhanced atherosclerosis in obese patients with rheumatoid arthritis

Background

Retinol binding protein 4 (RBP) enhances metabolic risk and atherogenesis. Whether RBP4 contributes to cardiovascular risk in rheumatoid arthritis (RA) is unknown.

Methods

We assessed RBP4 concentrations and those of endothelial activation molecules including E-selectin, vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 by ELISA, and the common carotid artery intima-media thickness (cIMT) and carotid artery plaque by ultrasound in 217 (112 black and 105 white) patients with RA. Relationships were identified in potential confounder and mediator adjusted mixed regression models.

Results

RBP4 concentrations were associated with systolic and mean blood pressure, and those of glucose and E-selectin (partial R = −0.207 (p = 0.003), −0.195 (p = 0.006), −0.155 (p = 0.03) and −0.191 (p = 0.007), respectively in all patients); these RBP4-cardiovascular risk relations were mostly reproduced in patients with but not without adverse traditional or non-traditional cardiovascular risk profiles. RBP4 concentrations were not associated with atherosclerosis in all patients, but related independently to cIMT (partial R = 0.297, p = 0.03) and plaque (OR (95%CI) = 2.95 (1.31–6.68), p = 0.008) in those with generalized obesity, as well as with plaque in those with abdominal obesity (OR (95%CI) = 1.95 (1.12–3.42), p = 0.01).

Conclusion

In the present study, RBP4 concentrations were inversely associated with metabolic risk and endothelial activation in RA. This requires further investigation. RBP4 concentrations were related to enhanced atherosclerosis in patients with generalized or/and abdominal obesity.

The caffeoylquinic acid-rich Pandanus tectorius fruit extract increases insulin sensitivity and regulates hepatic glucose and lipid metabolism in diabetic db/db mice

Caffeoylquinic acids (CQAs) are widely distributed in various foods. While some CQAs have been shown to possess antihyperglycemic activities, whether it is beneficial for diabetes patients to ingest CQA-rich foods has still to be known. In this work, the antihyperglycemic and antihyperlipidemic effects of CQA-rich Pandanus tectorius fruit extract (PTF) was investigated in diabetic db/db mice. Treatment with PTF (200 mg/kg) significantly decreased body weight and fasting glucose level, alleviated hyperinsulinism and hyperlipidemia and declined glucose area under the curve in oral glucose tolerance test and insulin tolerance test. The elevated levels of serum proinflammatory cytokines and islet hypertrophy in db/db mice were remarkably attenuated by PTF treatment. Biochemical analysis showed that administration of PTF significantly stimulated the phosphorylation of AMP-activated protein kinase (AMPK) and Akt substract of 160 kDa (AS160), and enhanced the expression and translocation of glucose transporter type 4 (GLUT4) in skeletal muscles. It also increased the activity of hexokinase, decreased the expression of glucose 6-phosphatase and phosphoenolpyruvate carboxykinase and switched the transcription of several key lipid metabolic genes in the liver, which, in turn, improved hepatic glucose and lipid profiles as determined by nuclear magnetic resonance-based metabolomics. Overall, the CQA-rich PTF is beneficial for the treatment of diabetes. It may alleviate hyperglycemia and dyslipidemia via activation of AMPK-AS160-GLUT4 pathway in skeletal muscles and inhibition of gluconeogenesis and lipogenesis in the liver.

Effects of short-term nonperiodized, linear periodized and daily undulating periodized resistance training on plasma adiponectin, leptin and insulin resistance

OBJECTIVES

Resistance training (RT) had a positive effect on musculoskeletal, cardiovascular, and type 2 diabetes disease. Knowing about the influence of different types of RT on the adipokines involved in the insulin regulation could be useful for the treatment of insulin resistance or diabetes. Therefore, the purpose of this study was to compare the effects of nonperiodized vs. periodized RT on plasma adiponectin, leptin and insulin resistance index in overweight men.

DESIGN AND METHODS

Thirty two sedentary overweight men (mean ± SD; age, 23.4 ± 0.6 years) were allocated to one of the following (n=8) groups: control group (CON), nonperiodized (NP), linear periodized (LP) and daily undulating periodized (DUP) training groups. Subjects in training groups performed RT protocols 3daysperweek for 8 weeks. Blood samples were taken before and 72 h after the training period and were analyzed for plasma adiponectin, leptin, glucose, and insulin.

RESULTS

Insulin resistance decreased in all training groups but significant differences were only found between DUP and CON groups (P<0.05). However, after 8 weeks of RT no significant changes were observed in plasma adiponectin and leptin concentrations. Body fat percent and waist to hip ratio (WHR) decreased significantly (P<0.05) following training, whereas, no significant changes were detected in body mass and BMI (P>0.05). The maximum strength (1RM) for bench press and leg press increased after RT in all training groups (P<0.05).

CONCLUSIONS

Short-term periodized RT protocols can be an efficient training strategy for improving insulin resistance and muscular strength in overweight men, while, they have no significant influence on adiponectin and leptin.

Exploring glycosuria as a mechanism for weight and fat mass reduction. A pilot study with remogliflozin etabonate and sergliflozin etabonate in healthy obese subjects

Inhibitors of sodium-dependent glucose co-transporter 2 (SGLT2) increase glucose excretion in the urine and improve blood glucose in Type 2 diabetes mellitus. Glycosuria provides an energy and osmotic drain that could alter body composition. We therefore conducted a pilot study comparing the effects on body composition of two SGLT2 inhibitors, remogliflozin etabonate (RE) 250 mg TID (n = 9) and sergliflozin etabonate (SE) (1000 mg TID) (n = 9), with placebo (n = 12) in obese non-diabetic subjects. Both drugs were well tolerated during 8 weeks of dosing, and the most common adverse event was headache. No urinary tract infections were observed, but there was one case of vaginal candidiasis in the RE group. As expected, RE and SE increased urine glucose excretion, with no change in the placebo group. All the subjects lost weight over 8 weeks, irrespective of treatment assignment. There was a reduction in TBW measured by D₂O dilution in the RE group that was significantly greater than placebo (1.4 kg, p = 0.029). This was corroborated by calculation of fat-free mass using a quantitative magnetic resonance technique. All but one subject had a measurable decrease in fat mass. There was significant between-subject variability of weight and fat loss, and no statistically significant differences were observed between groups. Despite a lack of a difference in weight and fat mass loss, the leptin/adiponectin ratio, a measure of insulin resistance, was significantly decreased in the RE group when compared to placebo and SE, suggesting that this SGTL-2 inhibitor may improve metabolic health independent of a change in fat mass.

The macrophage-specific serum marker, soluble CD163, is increased in obesity and reduced after dietary-induced weight loss

OBJECTIVE

Soluble CD163 (sCD163) is a new macrophage-specific serum marker elevated in inflammatory conditions. sCD163 is elevated in obesity and found to be a strong predictor of the development of type 2 diabetes. We investigated whether dietary intervention and moderate exercise was related to changes in sCD163 and how sCD163 is associated to insulin resistance in obesity.

DESIGN AND METHODS

Ninety-six obese subjects were enrolled: 62 followed a very low energy diet (VLED) program for 8 weeks followed by 3-4 weeks of weight stabilization, 20 followed a moderate exercise program for 12 weeks, and 14 were included without any intervention. Fasting blood samples and anthropometric measures were taken at baseline and after intervention. Thirty-six lean subjects were included in a control group.

RESULTS

sCD163 was significantly higher in obese subjects (2.3 ± 1.0 mg/l) compared with lean (1.6 ± 0.4 mg/l, P < 0.001). Weight loss (11%) induced by VLED resulted in a reduction and partial normalization of sCD163 to 2.0 ± 0.9 mg/l (P < 0.001). Exercise for 12 weeks had no effect on sCD163. At baseline, sCD163 was significantly correlated with BMI (r = 0.46), waist circumference (r = 0.40), insulin resistance measured by the homeostasis model assessment (HOMA-IR; r = 0.41; all P < 0.001), and the leptin-to-adiponectin ratio (r = 0.28, P < 0.05). In a multivariate linear regression analysis with various inflammatory markers, sCD163 (β = 0.25), adiponectin (β = -0.24), and high sensitivity C-reactive protein (hs-CRP; β = 0.20) remained independently and significantly associated to HOMA-IR (all P < 0.05). After further adjustment for waist circumference, only sCD163 was associated with HOMA-IR (P < 0.05).

CONCLUSION

The macrophage-specific serum marker sCD163 is increased in obesity and partially normalized by dietary-induced weight loss but not by moderate exercise. Furthermore, we confirm that sCD163 is a good marker for obesity-related insulin resistance.

Sedentary time and markers of chronic low-grade inflammation in a high risk population

Background

Sedentary behaviour has been identified as a distinct risk factor for several health outcomes. Nevertheless, little research has been conducted into the underlying mechanisms driving these observations. This study aimed to investigate the association of objectively measured sedentary time and breaks in sedentary time with markers of chronic low-grade inflammation and adiposity in a population at a high risk of type 2 diabetes mellitus.

Methods

This study reports data from an ongoing diabetes prevention programme conducted in Leicestershire, UK. High risk individuals were recruited from 10 primary care practices. Sedentary time (<25counts per 15s) was measured using Actigraph GT3X accelerometers (15s epochs). A break was considered as any interruption in sedentary time (≥25counts per 15s). Biochemical outcomes included interleukin-6 (IL-6), C-reactive protein (CRP), leptin, adiponectin and leptin:adiponectin ratio (LAR). A sensitivity analysis investigated whether results were affected by removing participants with a CRP level >10 mg/L, as this can be indicative of acute inflammation.

Results

558 participants (age = 63.6±7.7years; male = 64.7%) had complete adipokine and accelerometer data. Following adjustment for various confounders, sedentary time was detrimentally associated with CRP (β = 0.176±0.057, p = 0.002), IL-6 (β = 0.242±0.056, p = <0.001), leptin (β = 0.146±0.043, p = <0.001) and LAR (β = 0.208±0.052, p = <0.001). Associations were attenuated after further adjustment for moderate-to-vigorous physical activity (MVPA) with only IL-6 (β = 0.231±0.073, p = 0.002) remaining significant; this result was unaffected after further adjustment for body mass index and glycosylated haemoglobin (HbA_1c). Similarly, breaks in sedentary time were significantly inversely associated with IL-6 (β = −0.094±0.047, p = 0.045) and leptin (β = −0.075±0.037, p = 0.039); however, these associations were attenuated after adjustment for accelerometer derived variables. Excluding individuals with a CRP level >10 mg/L consistently attenuated the significant associations across all markers of inflammation.

Conclusion

These novel findings from a high risk population recruited through primary care suggest that sedentary behaviour may influence markers associated with inflammation, independent of MVPA, glycaemia and adiposity.

Serum leptin, adiponectin and endometrial cancer risk in Chinese women

Objective

To investigate the relationship between serum concentrations of leptin or adiponectin, and endometrial carcinoma in Chinese women.

Methods

We conducted a case-control study of a total of 516 Chinese women to detect the relationships between serum concentrations of leptin or adiponectin, and endometrial carcinoma in Chinese women. The study subject constituted 206 cases of endometrial cancer and 310 normal controls.

Results

Patients with endometrial carcinoma had higher serum leptin concentrations than controls (28.8±2.2 ug/L vs. 19.8±1.4 ug/L; p<0.001). The adiponectin levels in patients were lower than in controls with borderline statistical significance (2,330.7±180.5 ug/L vs. 2,583.9±147.2 ug/L; p=0.078). Logistic regression analysis confirmed the associations between leptin or adiponectin, and endometrial carcinoma after adjustment for age, body mass index, fasting insulin, serum glucose, cholesterol, triglycerides, and high-density lipoprotein cholesterol (odds ratio for the top tertile vs. the bottom tertile: leptin 2.05; 95% confidence interval [CI], 1.28 to 3.29; p<0.001; adiponectin 0.52; 95% CI, 0.32 to 0.83; p<0.001).

Conclusion

Increased leptin or decreased adiponectin levels are associated with endometrial carcinoma.

Metabolic syndrome and skin: psoriasis and beyond

Metabolic syndrome (Met S) is a clustering of risk factors comprising of abdominal obesity, dyslipidemia, elevated blood pressure, and abnormal glucose tolerance. The prevalence of Met S has been increasing in the last few years throughout the world. Psoriasis has consistently been associated with Met S as well as its various components. However, the association is no longer limited to psoriasis alone. Various dermatological conditions such as lichen planus, androgenetic alopecia, systemic lupus erythematosus, skin tags, acanthosis nigricans, and even cutaneous malignancies have also been found to be associated with this syndrome. Though chronic inflammation is thought to be the bridging link, the role of oxidative stress and endocrine abnormalities has recently been proposed in bringing them together.

Predicting portal hypertension and variceal bleeding using non-invasive measurements of metabolic variables

BACKGROUND & AIM

This study assessed the involvement of metabolic factors (anthropometric indices, insulin resistance (IR) and adipocytokines) in the prediction of portal hypertension, esophageal varices and risk of variceal bleeding in cirrhotic patients.

MATERIAL AND METHODS

Two prospective and retrospective cohorts of cirrhotic patients were selected (n = 357). The first prospective cohort (n = 280) enrolled consecutively in three centers, underwent upper gastrointestinal endoscopy, seeking evidence of esophageal varices. Clinical, anthropometric, liver function tests, ultrasonographic, and metabolic features were recorded at the time of endoscopy, patients were followed-up every 6 months until death, liver transplantation or variceal bleeding. The second retrospective cohort (n = 48 patients) had measurements of the hepatic venous pressure gradient (HVPG). Statistical analyses of the data were with the SPSS package.

RESULTS

The presence of esophageal varices was independently associated with lower platelet count, raised HOMA index and adiponectin levels. This relationship extended to subset analysis in patients with Child A cirrhosis. HOMA index and adiponectin levels significantly correlated with HVPG. Beside Child-Pugh class, variceal size and glucagonemia, HOMA index but not adiponectin and leptin plasma levels were associated with higher risk of variceal bleeding.

CONCLUSION

In patients with cirrhosis, HOMA score correlates with HVPG and independently predict clinical outcomes. Three simple markers i.e. platelet count, IR assessed by HOMA-IR and adiponectin significantly predict the presence of esophageal varices in cirrhotic patients.

Circulating adipokine levels and endometrial cancer risk in the prostate, lung, colorectal, and ovarian cancer screening trial

BACKGROUND

Circulating adipokine levels may be associated with endometrial cancer risk, yet few studies have evaluated these markers prospectively.

METHODS

We conducted a nested case-control study of postmenopausal women in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (n = 78,216), including 167 incident endometrial cancer cases and 327 controls that were matched on age, study center, race, study year of diagnosis, year of blood draw, time of day of blood draw, and menopausal hormone therapy (MHT) use. Adipokine and estradiol levels were categorized into tertiles (T). ORs and 95% confidence intervals (CIs) for the associations of adiponectin, leptin, and visfatin with endometrial cancer risk were estimated by conditional logistic regression, adjusting for known endometrial cancer risk factors, including body mass index (BMI) and circulating estradiol levels.

RESULTS

Adiponectin levels were inversely associated with risk of endometrial cancer [ORT3vsT1 = 0.48; 95% CI, 0.29-0.80); Ptrend < 0.01], whereas elevated leptin levels showed a positive association [2.77 (1.60-4.79); Ptrend < 0.01]. These results remained significant after adjustment for estradiol, but not after further adjustment for BMI. When analyses were restricted to non-MHT users, associations of adiponectin and leptin were stronger and remained significant after adjustment for estradiol and BMI [0.25 (0.08-0.75); Ptrend = 0.01 and 4.72 (1.15-19.38); Ptrend = 0.02, respectively]. Nonsignificant positive associations were observed for visfatin.

CONCLUSION

Adipokines may influence endometrial cancer risk through pathways other than estrogen-mediated cell growth in postmenopausal women not currently on MHT.

IMPACT

Understanding how adipokines influence endometrial cancer risk may help to elucidate biological mechanisms important for the observed obesity-endometrial cancer association.

Metabolic and psychological response to 7-day fasting in obese patients with and without metabolic syndrome

BACKGROUND

Extended modified fasting is a frequently practiced tradition in Europe. It is claimed to improve the cardiometabolic state and physical and psychological well-being by an evolutionary co-developed adaptation response. We aimed to investigate the cardiometabolic and psychological effects of a 7-day fast and differences of these responses between patients with or without metabolic syndrome (MetS).

METHODS

We investigated 30 female subjects (49.0 ± 8.1 years, BMI 30.4 ± 6.7 kg/m(2)) with (n = 12) and without (n = 18) MetS. All subjects participated in a 7-day fast according to Buchinger with a nutritional energy intake of 300 kcal/day and stepwise reintroduction of solid food thereafter. Outcomes were assessed baseline and after fasting and included measures of metabolic and glucoregulatory control, adipokines as well as psychological well-being as assessed by Profile of Mood States (POMS) and Hospital Anxiety and Depression Scale (HADS).

RESULTS

Mean weight decreased from 85.4 ± 18.8 kg to 79.7 ± 18.2 kg accompanied by systolic/diastolic blood pressure (BP) reduction of -16.2 mm Hg (95% CI: -9.1; -23.3 mm Hg) and -6.0 mm Hg (95% CI: -1.8; -10.3 mm Hg), each p < 0.001 and p = 0.005. Fasting led to marked decreases of levels of LDL-cholesterol, leptin, and insulin and increases of levels of adiponectin, leptin receptors, and resistin. Fasting-induced mood enhancement was reflected by decreased anxiety, depression, fatigue, and improved vigor. Patients with MetS showed some greater changes in B P, LDL-cholesterol, triglycerides, adiponectin, leptin, and sleep quality. Fasting was well-tolerated.

CONCLUSIONS

Our results point to marked beneficial responses to 7-day modified fasting and a potential role in the prevention of the MetS. Randomized trials with longer observation periods should test the clinical effectiveness of fasting in metabolic diseases.

Hypoadiponectinaemia in nonalcoholic fatty liver disease obese women is associated with infrequent intake of dietary sucrose and fatty foods

BACKGROUND

The present study aimed to investigate the relationship between adiponectinaemia and food intake among obese women with nonalcoholic fatty liver disease (NAFLD).

METHODS

In total, 60 obese women were examined by abdominal ultrasound for liver steatosis and subcutaneous and visceral adiposity. A standard interview (including questions about alcohol intake, medical history and physical activity), a physical examination (including height, weight, body mass index, waist and hip circumferences, waist-to-hip ratio, and body composition) and biochemical and clinical parameters (including serum glucose and insulin, homeostatic model assessment insulin resistance, lipid profile, aminotransferases, C-reactive protein, adiponectin, leptin, resistin, tumour necrosis factor-α, interleukin-6 levels and blood pressure) were performed. Food intake was evaluated by a qualitative food frequency questionnaire.

RESULTS

Twenty-four NAFLD patients and thirty-six controls were analysed. The Mann-Whitney test showed lower adiponectin levels in the liver disease group compared to controls (P < 0.05). The Pearson correlation coefficient indicated that adiponectinaemia was negatively correlated with lipid profile and serum tumour necrosis factor-α (P = 0.05) and was positively associated with adiposity measures and serum leptin (P < 0.05). By simple linear regression, all of these variables predicted serum adiponectin levels. Chi-squared and Fisher's exact tests indicated that, in both groups, food intake showed no differences, although sucrose and fatty foods were associated with lower adiponectin levels in the liver disease group (P < 0.05 and P < 0.05, respectively), as well as in the control group (P = 0.05 and P < 0.05, respectively).

CONCLUSIONS

Hypoadiponectinaemia in NAFLD was associated with dietary sucrose and fatty food intake, emphasising the important role of diet in the occurrence of this disease.

Lipid accumulation in overweight type 2 diabetic subjects: relationships with insulin sensitivity and adipokines

Adipokines are known to play a fundamental role in the etiology of obesity, that is, in the impaired balance between increased feeding and decreased energy expenditure. While the adipokine-induced changes of insulin resistance in obese diabetic and nondiabetic subjects are well known, the possible role of fat source in modulating insulin sensitivity (IS) remains controversial. The aim of our study was to explore in overweight type 2 diabetic patients (T2DM) with metabolic syndrome IS in different energy storage conditions (basal and dynamic) for relating it to leptin and adiponectin. Sixteen T2DM (5/11 F/M; 59 ± 2 years; 29.5 ± 1.1 kg/m(2)) and 16 control (CNT 5/11; 54 ± 2; 29.1 ± 1.0) underwent an oral glucose tolerance test. Fasting IS was measured by QUICKI, while the dynamic one with OGIS. The insulinogenic index (IGI) described beta cell function. Also, the lipid accumulation product parameter (LAP) was assessed. LAP accounts for visceral abdominal fat and triglycerides, and it is known to be related to IS. Possible interrelationships between LAP and adipokines were explored. In T2DM and CNT, adiponectin (7.4 ± 0.5 vs. 7.8 ± 0.9 μg/mL), leptin (13.3 ± 3.0 vs. 12.4 ± 2.6 ng/mL), and QUICKI (0.33 ± 0.01 vs. 0.33 ± 0.01) were not different (P > 0.40), at variance with OGIS (317 ± 11 vs. 406 ± 13 mL/min/m(2); P = 0.006) and IGI (0.029 ± 0.005 vs. 0.185 ± 0.029 × 10(3) pmolI/mmolG; P = 0.00001). LAP was 85 ± 15 cm × mg/dL in T2DM and 74 ± 10 in CNT (P > 0.1), correlated with OGIS in all subjects (R = -0.42, P = 0.02) and QUICKI (R = -0.56, P = 0.025) in T2DM. Leptin correlated with QUICKI (R = -0.45, P = 0.009), and adiponectin correlated with OGIS (R = 0.43, P = 0.015). In overweight T2DM, insulin sensitivity in basal condition appears to be multifaceted with respect to the dynamic one, because it should be more fat-related. Insulin sensitivity appears to be incompletely described by functions of fasting glucose and insulin values alone and the use of other indices, such as LAP could be suggested.

The effect of intermittent energy and carbohydrate restriction v. daily energy restriction on weight loss and metabolic disease risk markers in overweight women

Intermittent energy restriction may result in greater improvements in insulin sensitivity and weight control than daily energy restriction (DER). We tested two intermittent energy and carbohydrate restriction (IECR) regimens, including one which allowed ad libitum protein and fat (IECR+PF). Overweight women (n 115) aged 20 and 69 years with a family history of breast cancer were randomised to an overall 25 % energy restriction, either as an IECR (2500-2717 kJ/d, < 40 g carbohydrate/d for 2 d/week) or a 25 % DER (approximately 6000 kJ/d for 7 d/week) or an IECR+PF for a 3-month weight-loss period and 1 month of weight maintenance (IECR or IECR+PF for 1 d/week). Insulin resistance reduced with the IECR diets (mean - 0·34 (95% CI - 0·66, - 0·02) units) and the IECR+PF diet (mean - 0·38 (95% CI - 0·75, - 0·01) units). Reductions with the IECR diets were significantly greater compared with the DER diet (mean 0·2 (95% CI - 0·19, 0·66) μU/unit, P= 0·02). Both IECR groups had greater reductions in body fat compared with the DER group (IECR: mean - 3·7 (95% CI - 2·5, - 4·9) kg, P= 0·007; IECR+PF: mean - 3·7 (95% CI - 2·8, - 4·7) kg, P= 0·019; DER: mean - 2·0 (95% CI - 1·0, 3·0) kg). During the weight maintenance phase, 1 d of IECR or IECR+PF per week maintained the reductions in insulin resistance and weight. In the short term, IECR is superior to DER with respect to improved insulin sensitivity and body fat reduction. Longer-term studies into the safety and effectiveness of IECR diets are warranted.

Adiponectin/leptin ratio and insulin resistance in pregnancy

Objective

Pregnancy is characterized by progressive insulin resistance. The present study evaluated whether the adiponectin/leptin ratio is associated with insulin resistance in pregnancy, since this ratio has been shown to be associated with insulin resistance in obesity, type 2 diabetes mellitus, metabolic syndrome and polycystic ovary syndrome.

Methods

In this cross-sectional study, adiponectin and leptin concentrations were measured in pregnant women using enzyme-linked immunosorbent assays. Insulin resistance was assessed using the homeostasis model assessment of insulin resistance (HOMA–IR).

Results

Mean ± SD age of the participants ( n = 74) was 30.76 ± 4.27 years, mean ± SD gestational age was 26.81 ± 3.52 weeks and median body mass index (BMI) before pregnancy was 22.68 kg/m2 (interquartile range 20.75–26.79 kg/m2). There was a significant correlation between the HOMA–IR and leptin concentration, but not between the HOMA–IR and adiponectin concentration. There was a significant inverse correlation between the HOMA–IR and adiponectin/leptin ratio. The adiponectin/leptin ratio was inversely correlated with BMI before pregnancy.

Conclusion

The adiponection/leptin ratio inversely correlates with HOMA–IR in pregnancy.

Systemic inflammation and lung function impairment in morbidly obese subjects with the metabolic syndrome

BACKGROUND

Obesity and asthma are associated. There is a relationship between lung function impairment and the metabolic syndrome. Whether this relationship also exists in the morbidly obese patients is still unknown. Hypothesis. Low-grade systemic inflammation associated with the metabolic syndrome causes inflammation in the lungs and, hence, lung function impairment.

METHODS

This is cross-sectional study of morbidly obese patients undergoing preoperative screening for bariatric surgery. Metabolic syndrome was assessed according to the revised NCEP-ATP III criteria.

RESULTS

A total of 452 patients were included. Patients with the metabolic syndrome (n = 293) had significantly higher blood monocyte (mean 5.3 versus 4.9, P = 0.044) and eosinophil percentages (median 1.0 versus 0.8, P = 0.002), while the total leukocyte count did not differ between the groups. The FEV1/FVC ratio was significantly lower in patients with the metabolic syndrome (76.7% versus 78.2%, P = 0.032). Blood eosinophils were associated with FEV1/FVC ratio (adj. B -0.113, P = 0.018).

CONCLUSION

Although the difference in FEV1/FVC ratio between the groups is relatively small, in this cross-sectional study, and its clinical relevance may be limited, these data indicate that the presence of the metabolic syndrome may influence lung function impairment, through the induction of relative eosinophilia.

Intrahepatic Lipid Content and Insulin Resistance Are More Strongly Associated with Impaired NEFA Suppression after Oral Glucose Loading Than with Fasting NEFA Levels in Healthy Older Individuals

Introduction. The mechanisms underlying the association between insulin resistance and intrahepatic lipid (IHL) accumulation are not completely understood. We sought to determine whether this association was explained by differences in fasting non-esterified fatty acid (NEFA) levels and/or NEFA suppression after oral glucose loading. Materials and Methods. We performed a cross-sectional analysis of 70 healthy participants in the Hertfordshire Physical Activity Trial (39 males, age 71.3 ± 2.4 years) who underwent oral glucose tolerance testing with glucose, insulin, and NEFA levels measured over two hours. IHL was quantified with magnetic resonance spectroscopy. Insulin sensitivity was measured with the oral glucose insulin sensitivity (OGIS) model, the leptin: adiponectin ratio (LAR), and the homeostasis model assessment (HOMA). Results. Measures of insulin sensitivity were not associated with fasting NEFA levels, but OGIS was strongly associated with NEFA suppression at 30 minutes and strongly inversely associated with IHL. Moreover, LAR was strongly inversely associated with NEFA suppression and strongly associated with IHL. This latter association (beta = 1.11 [1.01, 1.21], P = 0.026) was explained by reduced NEFA suppression (P = 0.24 after adjustment). Conclusions. Impaired postprandial NEFA suppression, but not fasting NEFA, contributes to the strong and well-established association between whole body insulin resistance and liver fat accumulation.

Metabolic risk susceptibility in men is partially related to adiponectin/leptin ratio

BACKGROUND

High adiponectin/leptin ratio may be protective from metabolic risks imparted by high triglyceride, low HDL, and insulin resistance.

METHODS

This cross-sectional study examines plasma adipokine levels in 428 adult men who were subgrouped according to low (<6.5  μ g/mL)and high (≥6.5  μ g/mL)adiponectin levels or a low or high ratio of adiponectin/leptin.

RESULTS

Men with high adiponectin/leptin ratio had lower plasma triglyceride and higher HDL cholesterol than those with low ratio. Similarly, those with high adiponectin/leptin ratio had lower TG/HDL cholesterol ratio and HOMA2-IR than those with low ratio. In contrast, levels of adiponectin or the ratio of adiponectin/leptin did not associate with systolic blood pressure. But the ratio of adiponectin/leptin decreased progressively with the increase in the number of risk factors for metabolic syndrome.

CONCLUSION

Adipokine levels may reflect adipose tissue triglyceride storage capacity and insulin sensitivity. Leptin is an index of fat mass, and adiponectin is a biomarker of triglyceride metabolism and insulin sensitivity. Men with high adiponectin/leptin ratios have better triglyceride profile and insulin sensitivity than men with a low ratio regardless of waist girth.

The plasma leptin/adiponectin ratio predicts first cardiovascular event in men: a prospective nested case-control study

OBJECTIVE

The plasma leptin/adiponectin (L/A) ratio has been proposed as a preferential marker of atherosclerosis susceptibility compared to leptin and adiponectin alone. We determined the extent to which the L/A ratio predicts incident cardiovascular disease (CVD) taking account of clinical risk factors, microalbuminuria, the total cholesterol/HDL cholesterol (TC/HDL-C ratio), triglycerides, high sensitive C-reactive protein (hs-CRP) and insulin sensitivity (homeostasis model assessment (HOMA(ir))).

METHODS

A community-based prospective nested case-control study was carried out in 103 non-diabetic men who developed a first cardiovascular event (cases) and 106 male control subjects (no clinically manifest CVD and no lipid lowering drug use at baseline; median follow-up of 3.0 and 10.5 years, respectively). Plasma leptin, adiponectin, the leptin/adipnectin (L/A) ratio, as well as hs-CRP, HOMA(ir) and the TC/HDL-C ratio were determined at baseline.

RESULTS

Plasma leptin levels and the L/A ratio were higher in cases vs. controls (p=0.002 for both), but the difference in adiponectin was not significant (p=0.10). Age-adjusted incident CVD was associated with plasma leptin, adiponectin and the L/A ratio (p=0.045 to p=0.001). The relationships of incident CVD with plasma leptin (p=0.19) and adiponectin (p=0.073) lost statistical significance after additional adjustment for smoking, waist circumference, hypertension, microalbuminuria, the TC/HDL-C ratio, hs-CRP and HOMA(ir). In this fully adjusted analysis, the L/A ratio remained predictive of incident CVD (hazard ratio: 1.40 (95% CI 1.05-1.87), p=0.024).

CONCLUSION

This study suggests that the L/A ratio may be a preferential marker of a first cardiovascular event in men compared to plasma leptin and adiponectin levels alone.

Adipokines, ghrelin and obesity-associated insulin resistance in nondiabetic patients with acute coronary syndrome

Altered glucose metabolism negatively modulates outcome in acute coronary syndromes (ACS). Insulin resistance is commonly associated with increasing BMI in the general population and these associations may involve obesity-related changes in circulating ghrelin and adipokines. We aimed at investigating interactions between BMI, insulin resistance and ACS and their associations with plasma ghrelin and adipokine concentrations. Homeostasis model assessment of insulin resistance (HOMA(IR))-insulin resistance index, plasma adiponectin, leptin, total (T-Ghrelin), acylated (Acyl-Ghrelin), and desacylated ghrelin (Desacyl-Ghrelin) were measured in 60 nondiabetic ACS patients and 44 subjects without ACS matched for age, sex, and BMI. Compared with non-ACS, ACS patients had similar HOMA(IR) and plasma adipokines, but lower T- and Desacyl-Ghrelin and higher Acyl-Ghrelin. Obesity (BMI > 30) was associated with higher HOMA(IR), lower adiponectin, and higher leptin (P < 0.05) similarly in ACS and non-ACS subjects. In ACS (n = 60) HOMA(IR) remained associated negatively with adiponectin and positively with leptin independently of BMI and c-reactive protein (CRP) (P < 0.05). On the other hand, low T- and Desacyl-Ghrelin with high Acyl-Ghrelin characterized both obese and non-obese ACS patients and were not associated with HOMA(IR). In conclusion, in ACS patients, obesity and obesity-related changes in plasma leptin and adiponectin are associated with and likely contribute to negatively modulate insulin resistance. ACS per se does not however enhance the negative impact of obesity on insulin sensitivity. High acylated and low desacylated ghrelin characterize ACS patients independently of obesity, but are not associated with insulin sensitivity.

Case-control study of markers of insulin resistance and endometrial cancer risk

Markers of insulin resistance such as the adiponectin:leptin ratio (A:L) and the homeostasis model assessment ratio (HOMA-IR) are associated with obesity and hyperinsulinemia, both established risk factors for endometrial cancer, and may therefore be informative regarding endometrial cancer risk. This study investigated the association between endometrial cancer risk and markers of insulin resistance, namely adiponectin, leptin, the A:L ratio, insulin, fasting glucose, and the HOMA-IR. We analyzed data from 541 incident endometrial cancer cases and 961 frequency age-matched controls in a population-based case-control study in Alberta, Canada from 2002 to 2006. Participants completed interview-administered questionnaires were assessed for anthropometric measures, and provided 8-h fasting blood samples either pre- or postoperatively. Blood was analyzed for concentrations of leptin, adiponectin, and insulin by immunoassay, and fasting plasma glucose levels were determined by fluorimetric quantitative determination. Compared with the lowest quartile, the highest quartile of insulin and HOMA-IR was associated with 64% (95% confidence intervals (CI): 1.12-2.40) and 72% (95% CI: 1.17-2.53) increased risks of endometrial cancer, respectively, and the highest quartile of adiponectin was associated with a 45% (95% CI: 0.37-0.80) decreased risk after multivariable adjustments. Null associations were observed between fasting glucose, leptin and A:L, and endometrial cancer risk. This population-based study provides evidence for a role of insulin resistance in endometrial cancer etiology and may provide one possible pathway whereby obesity increases the risk of this common cancer. Interventions aimed at decreasing both obesity and insulin resistance may decrease endometrial cancer risk.