Circulating concentrations of high-molecular-weight adiponectin are increased following Roux-en-Y gastric bypass surgery

Salivary Adiponectin and Albumin Levels on the Gingival Conditions of Patients Undergoing Bariatric Surgery: A Cohort Study

This study analyzed the salivary proteomics, adiponectin and albumin, related to weight loss and periodontitis in patients undergoing bariatric surgery. This study included fourteen patients with morbid obesity (body mass index, BMI > 40 kg/m²) who underwent bariatric surgery Roux-en-Y gastric bypass (RYGB) in System Health Public in Brazil. Data on demographic and anthropometric measures were extracted from medical records preoperatively and 6 and 12 months post-surgery. The variables assessed were: probing pocket depth (PPD), clinical attachment loss (CAL), bleeding on probing (BOP), and stimulated whole-mouth saliva. In this study, saliva samples were analyzed by electrophoresis and immunoblotting. The ELISA kit was used to measure the MMP8 levels to determine potential markers for obesity. Adiponectin and albumin levels were also evaluated. Weight loss was associated with significant changes in patients' periodontal clinical data. Although 7 out of 10 periodontal patients showed an increase in salivary adiponectin levels after root planning treatment, when analyzed by Western blotting, the increase was not statistically significant (21.1 ± 4.8 to 26.3 ± 9.4 arbitrary units, p > 0.99). There was no correlation between albumin levels and salivary adiponectin pre-surgery, nor 6 months or 12 months after surgery. Weight loss was not improved by low-grade inflammation in bariatric patients, since albumin levels were similar between periods. Periodontitis is an inflammatory disease that is modulated by several factors, among which adiponectin plays an important role for the treatment of periodontal disease.

Effects of Roux-en-Y gastric bypass on the metabolic profile and systemic inflammatory status of women with metabolic syndrome: randomized controlled clinical trial

BACKGROUND

Obesity remains a public health problem worldwide. The high prevalence of this condition in the population raises further concerns, considering that comorbidities are often associated with obesity. Among the comorbidities closely associated with obesity, metabolic syndrome (MS) is particularly important, which potentially increases the risk of manifestation of other disorders, such as the prothrombotic and systemic pro-inflammatory states.

METHODS

A randomized, controlled clinical trial was performed involving female patients (n = 32) aged between 18 and 65 years, with a clinical diagnosis of MS, with severe obesity undergoing Roux-en-Y gastric bypass (RYGB). The study design followed the Consolidated Standards of Reporting Trials statement (CONSORT). Lipid profile, blood glucose and adipokines (adiponectin, leptin, and resistin) and (cytokines IL-1β, IL-6, IL-17, IL-23, and TNF-α) in blood plasma samples were evaluated before and six months after RYGB.

RESULTS

Patients undergoing RYGB (BSG) showed a significant improvement from preoperative grade III obesity to postoperative grade I obesity. The results showed that while HDL levels increased, the other parameters showed a significant reduction in their postoperative values when compared not only to the values observed before surgery in the BSG group, but also to the values obtained in the control group (CG). As for systemic inflammatory markers adiponectin, leptin, resistin, IL-1β, IL-6, IL-17, IL-23 and TNF- α it was observed that the levels of resistin and IL-17 in the second evaluation increased significantly when compared to the levels observed in the first evaluation in the CG. In the BSG group, while the levels of adiponectin increased, the levels of the other markers showed significant reductions in the postoperative period, in relation to the respective preoperative levels. The analysis of Spearman's correlation coefficient showed a significant positive correlation between IL-17 and IL-23 in the preoperative period, significant positive correlations between TNF-α and IL-6, TNF-α and IL-17, IL-6 and IL-17, and IL-17 and IL-23 were observed postoperatively.

CONCLUSIONS

According to our results, the reduction of anthropometric measurements induced by RYGB, significantly improves not only the plasma biochemical parameters (lipid profile and glycemia), but also the systemic inflammatory status of severely obese patients with MS. Trials registration NCT02409160.

Effect of presurgical aerobic exercise on cardiometabolic health 30 days after bariatric surgery

We evaluated the effect of preoperative standard medical care (SC) vs. unsupervised aerobic exercise combined with SC (EX + SC) on cardiometabolic health and quality of life (QoL) 30 days after bariatric surgery. Bariatric patients (n = 14, age: 42.3 ± 2.5 years, body mass index: 45.1 ± 2.5 kg/m2 ) were match-paired to presurgical SC (n = 7) or EX + SC (n = 7; walking 30 min/day, 5 day/week, 65-85% HRpeak ) for 30 days. Body composition, peak cardiorespiratory fitness (VO2 peak), QoL, inflammation (adiponectin, leptin, cytokeratin-18), and a 120 min mixed meal tolerance test was performed to assess aortic waveforms (augmentation index, AIx@75), insulin sensitivity, and glucose total area under the curve (tAUC) at the time of surgery (post-intervention) and 30 days post-surgery. EX + SC had significantly higher high molecular weight (HMW) adiponectin (p = 0.01) and ratio of HMW to total adiponectin (p = 0.04) than SC at 30 days post-surgery, although they significantly (p = 0.006; ES = 1.86) decreased total time spent in moderate to vigorous physical activity (MVPA). SC had a significantly greater increase in VO2 peak (p = 0.02; ES = 1.54) and decrease in 120 min AIx@75 (p = 0.02; ES = 1.78) than EX + SC during the post-surgical period. The increase in MVPA was associated with a reduction in cytokeratin-18 (r = -0.67, p = 0.02). Increased VO2 peak was associated with increased activity/mobility QoL domain (r = 0.52, p = 0.05) and decreased 120 min AIx@75 (r = -0.61, p = 0.03) from surgery to post-surgery. Preoperative EX + SC did not maintain more favorable cardiometabolic health 30 days post-operation in this pilot study. However, changes in MVPA appear important for QoL and should be considered in future work.

Homeostasis Disrupted and Restored-A Fresh Look at the Mechanism and Treatment of Obesity During COVID-19

The prevalence of obesity in the United States approaches half of the adult population. The COVID-19 pandemic endangers the health of obese individuals. In addition, the metabolic syndrome poses a challenge to the health of obese adults. Bariatric surgery and diet restore metabolic homeostasis in obese individuals; however, it is still unclear which strategy is most effective. For example, intermittent fasting improves insulin sensitivity and diet alone decreases visceral adipose tissue at a disproportionately high rate compared to weight loss. Bariatric surgery causes rapid remission of type 2 diabetes and increases incretins for long-term remission of insulin resistance before meaningful weight loss has occurred. Malabsorptive surgeries have provided insight into the mechanism of altering metabolic parameters, but strong evidence to determine the duration of their effects is yet to be established. When determining the best method of weight loss, metabolic parameters, target weight loss, and risk-benefit analysis must be considered carefully. In this review, we address the pros and cons for the optimal way to restore metabolic homeostasis.

Adiponectin as a Potential Biomarker for Pregnancy Disorders

Adiponectin is an adipocyte-derived hormone that plays a critical role in energy homeostasis, mainly attributed to its insulin-sensitizing properties. Accumulating studies have reported that adiponectin concentrations are decreased during metabolic diseases, such as obesity and type 2 diabetes, with an emerging body of evidence providing support for its use as a biomarker for pregnancy complications. The identification of maternal factors that could predict the outcome of compromised pregnancies could act as valuable tools that allow the early recognition of high-risk pregnancies, facilitating close follow-up and prevention of pregnancy complications in mother and child. In this review we consider the role of adiponectin as a potential biomarker of disorders associated with pregnancy. We discuss common disorders associated with pregnancy (gestational diabetes mellitus, preeclampsia, preterm birth and abnormal intrauterine growth) and highlight studies that have investigated the potential of adiponectin to serve as biomarkers for these disorders. We conclude the review by recommending strategies to consider for future research.

Impact of Bariatric Surgery in Reducing Macrovascular Complications in Severely Obese T2DM Patients

BACKGROUND

Evidence from real-world studies have suggested a reduced rate of macrovascular complications following bariatric surgery. We undertook this meta-analysis to investigate the impact of bariatric surgery on macrovascular disease outcomes in severely obese type 2 diabetes mellitus (T2DM) patients.

METHODS

An extensive literature search was performed in PubMed from inception until March 2020. All cohort studies assessing the association between bariatric surgery and macrovascular complications in severely obese T2DM patients were included. Two independent reviewers screened the articles, extracted data, and assessed the quality using the Newcastle-Ottawa Scale. The primary outcome was to assess the impact of bariatric surgery and the risk of macrovascular complications. Statistical analysis was performed using Review Manager 5.3.

RESULTS

This meta-analysis comprised of five studies including 49,211 participants (75% female), of which 14,434 underwent bariatric surgery and 34,777 underwent usual care. Participants who underwent bariatric surgery had a significantly lower risk of macrovascular complications as compared to those with non-surgical interventions (RR: 0.50 [95% CI: 0.35-0.73], p = 0.0003). In the subgroup analysis, based on the geographical regions, studies conducted in the USA showed a higher reduction (RR: 0.41 [95% CI: 0.32-0.53], p < 0.00001) in macrovascular complications as compared to other parts of the world. The risk of all-cause mortality was also significantly lower in patients with bariatric surgery (RR 0.39 [95% CI: 0.30-0.50], p < 0.00001).

CONCLUSION

Bariatric surgery was associated with a 50% reduction in macrovascular complications along with 61% reduction in risk of all-cause mortality in morbidly obese T2DM patients.

Obesity-Related Changes in High-Density Lipoprotein Metabolism and Function

In obese individuals, atherogenic dyslipidemia is a very common and important factor in the increased risk of cardiovascular disease. Adiposity-associated dyslipidemia is characterized by low high-density lipoprotein cholesterol (HDL-C) levels and an increase in triglyceride-rich lipoproteins. Several factors and mechanisms are involved in lowering HDL-C levels in the obese state and HDL quantity and quality is closely related to adiponectin levels and the bioactive lipid sphingosine-1-phosphate. Recent studies have shown that obesity profoundly alters HDL metabolism, resulting in altered HDL subclass distribution, composition, and function. Importantly, weight loss through gastric bypass surgery and Mediterranean diet, especially when enriched with virgin olive oil, is associated with increased HDL-C levels and significantly improved metrics of HDL function. A thorough understanding of the underlying mechanisms is crucial for a better understanding of the impact of obesity on lipoprotein metabolism and for the development of appropriate therapeutic approaches. The objective of this review article was to summarize the newly identified changes in the metabolism, composition, and function of HDL in obesity and to discuss possible pathophysiological consequences.

Potential involvement of adiponectin in obesity-associated erosive esophagitis

A strong causal relationship between obesity and erosive esophagitis has been proposed. Obesity may affect the pathogenesis of erosive esophagitis through adipokines as well as acid reflux. We evaluated the involvement of adiponectin in obesity-associated erosive esophagitis. In total, 1,902 patients who underwent endoscopy during medical check-ups were selected for study. Variables including the body mass index (BMI) and adiponectin level were compared between subjects with erosive esophagitis and normal controls. The subjects were classified by quartiles (Qs) of adiponectin level. Q4 was the reference group. The median adiponectin level differed by gender (men, 5.3 µg/ml vs women, 9.3 µg/ml; p<0.001). As the severity of erosive esophagitis increased in men, the BMI increased (p<0.001) while the adiponectin level decreased (p = 0.026). The multivariate odds ratio for erosive esophagitis was 1.79 for Q1, 1.73 for Q2, 2.34 for obesity, and 27.40 for hiatal hernia in men. When classified by obesity, the multivariate odds ratio for erosive esophagitis was 1.94 for Q1, 2.10 for Q2, and 18.47 for hiatal hernia only in obese men. In women, there were no trends in BMI, adiponectin levels, or severity of erosive esophagitis. We demonstrated that low adiponectin levels are involved in obesity-associated erosive esophagitis in men but not women.

Adiponectin and Its Isoforms in Pathophysiology

Adiponectin circulates in blood in multiple isoforms. High molecular weight (HMW) adiponectin is thought to be most biologically active and promotes glucose uptake, insulin sensitivity, and fatty acid oxidation. In obesity, adiponectin isoform formation is disrupted, leading to an inverse association between metabolic disease and HMW and total adiponectin. Adiponectin isoforms also function as acute-phase reactants influencing inflammation in acute and chronic disease. Interestingly, adiponectin and mortality have a U-shaped association. Unfortunately, data concerning adiponectin and its pathophysiologic function conflict. This is predominantly due to difficulties in adequate measurement of adiponectin isoforms and lack of a gold standard. In this review we provide a general overview of the formation and function of adiponectin and its isoforms under physiologic conditions. We highlight the ways adiponectin isoform formation is disrupted in obesity and its ensuing pathologic conditions. Furthermore, we will elaborate on the role of adiponectin isoforms as inflammatory proteins with respect to cardiac and kidney disease and discuss the association of adiponectin with mortality. Finally, we will provide a historical perspective on the measurement of adiponectin isoforms, current limitations, and future challenges.

A study of high-, middle- and low-molecular weight adiponectin in urine as a surrogate marker for early diabetic nephropathy using ultrasensitive immune complex transfer enzyme immunoassay

Background

For the early identification of patients at risk of developing diabetic nephropathy, we have developed an ultrasensitive immune complex transfer enzyme immunoassay to measure adiponectin in urine.

Methods

We developed immune complex transfer enzyme immunoassay for adiponectin and measured urinary adiponectin from 70 healthy subjects, 35 obese non-diabetic subjects and 20 patients with diabetes.

Results

The urinary adiponectin concentrations in patients with diabetes (3.3 ± 10.7 ng/mg creatinine) were significantly higher than those in obese subjects (0.54 ± 0.44; P < 0.01) and healthy subjects (0.46 ± 0.42; P < 0.001). The gel filtration elution profile of urine from healthy subjects showed traces of four immunoreactive peaks (high-, medium-, low-molecular weight and monomer molecules), despite the majority of blood adiponectin being high-molecular weight. However, urinary adiponectin molecules were more frequent in low-molecular weight as the estimate glomerular filtration rate decreased. Furthermore, as blood glucose concentrations rose, middle-molecular weight and high-molecular weight increased in urine. Further, urinary adiponectin concentrations correlated with estimate glomerular filtration rate ( r = −0.61, P < 0.001), but not urinary albumin. In addition, our analysis showed a significantly ( P < 0.001) higher value for urinary adiponectin in the G2 stage of chronic kidney disease classification where urinary albumin is not elevated.

Conclusion

Adiponectin increases in urine as renal function decreases, and urinary adiponectin may be useful as a surrogate marker for diabetic nephropathy risk.

Acute Vitamin D₃ Supplementation in Severe Obesity: Evaluation of Multimeric Adiponectin

Obesity predisposes to vitamin D deficiency (VDD) and glucose abnormalities. It is currently debated if vitamin D administration may improve glucose homeostasis by interacting with modulators of insulin sensitivity, such as adiponectin and its oligomers. In a 4-week inpatient study on a metabolic rehabilitation program, consisting of individualized caloric restriction and aerobic physical exercise in obese subjects with VDD, we assessed the acute effects of 600,000 IU cholecalciferol given per os VD group, 12 subjects; body mass index (BMI) 42.7 ± 1.3 kg/m²) or placebo per os (PL group, 12 subjects, BMI 39.8 ± 0.9 kg/m²) on high (HWM-A), medium (MMW-A), and low molecular weight adiponectin (LMW-A), as quantified by western immunoblot (WIB) and ELISA. During the 4-week study, dieting promoted a similar magnitude of weight loss in VD and PL groups. Compared to the PL group, cholecalciferol administration increased 25(OH)Vit D levels (p < 0.001) and promoted a significant increase of HMW-A expression analyzed by WIB (p = 0.02). In parallel, a significant decrease of leptin/HMW-A ratio (p < 0.05), a biomarker of metabolic homeostasis, was observed. During the study, changes of MMW-A and LMW-A occurred independently of cholecalciferol administration, and were likely explained by weight loss. At odds with these findings, the ELISA assessment of adiponectin oligomers showed no modifications in the VD group or PL group. Current findings suggest that acute cholecalciferol administration selectively modifies HMW-A and the leptin/HMW-A ratio.

Effect of Laparoscopic Sleeve Gastrectomy on Fasting Gastrointestinal, Pancreatic, and Adipose-Derived Hormones and on Non-Esterified Fatty Acids

BACKGROUND

Alterations in gastrointestinal, pancreatic, and adipose hormone levels may have a greater role in weight loss than initially appreciated. The laparoscopic sleeve gastrectomy (LSG) operation is now the most frequently performed bariatric operation in many countries, but there are relatively few data regarding its molecular effects. We sought to characterize the effect of LSG on fasting plasma levels of selected hormones and on non-esterified fatty acids (NEFA), and to compare these to levels in non-obese control individuals.

MATERIALS AND METHODS

The levels of nine plasma hormones were measured using a multiplex bead-based assay at baseline and at 3 months after operation in 11 obese patients undergoing LSG. NEFA levels were also measured. The levels were compared to those for 22 age- and sex-matched non-obese individuals.

RESULTS

At baseline, obese patients showed significantly higher expression of C-peptide, insulin, and leptin and significantly lower ghrelin, glucose-dependent insulinotropic peptide (GIP), and resistin compared to non-obese controls (p < 0.05). LSG resulted in a reduction in BMI from 42.5 ± 6.47 kg/m2 at operation to 35.2 ± 5.14 kg/m2 at 3 months (42 % mean excess weight loss, p < 0.001). LSG led to a significant decrease in ghrelin, glucagon-like peptide-1 (GLP-1), glucagon, leptin, plasminogen activator inhibitor-1 (PAI-1), and NEFA.

CONCLUSION

LSG induces marked early changes in the fasting levels of factors thought to be important regulators of obesity and metabolic health. These changes differ somewhat from the findings for operations with a malabsorptive component, suggesting that subtle differences exist in the mechanisms of weight loss between LSG and other bariatric operations.

Peripheral signals mediate the beneficial effects of gastric surgery in obesity

Obesity is nowadays a public health problem both in the industrialized world and developing countries. The different treatments to fight against obesity are not very successful with the exception of gastric surgery. The mechanism behind the achievement of this procedure remains unclear although the modifications in the pattern of gastrointestinal hormones production appear to be responsible for the beneficial effect. The gastrointestinal tract has emerged in the last time as an endocrine organ in charge of response to the different stimulus related to nutritional status by the modulation of more than 30 signals acting at central level to modulate food intake and body weight. The production of some of these gastric derived signals has been proved to be altered in obesity (ghrelin, CCK, and GLP-1). In fact, bariatric surgery modifies the production of both gastrointestinal and adipose tissue peripheral signals beyond the gut microbiota composition. Through this paper the main peripheral signals altered in obesity will be reviewed together with their modifications after bariatric surgery.

Effects of Roux-en-Y gastric bypass on fasting and postprandial inflammation-related parameters in obese subjects with normal glucose tolerance and in obese subjects with type 2 diabetes

BACKGROUND

Obesity is characterized by low grade inflammation and an altered secretion of inflammatory cytokines from the adipose tissue. Weight loss has shown to reduce inflammation; however, changes in cytokine profiles during massive weight loss are not well described. The present study explored the hypothesis that Roux-en-Y gastric bypass (RYGB) reduces circulating levels of pro-inflammatory cytokines, while increasing anti-inflammatory cytokines in obese subjects with type 2 diabetes (T2D) and in obese normal glucose tolerant (NGT) subjects.

METHODS

Thirteen obese subjects with T2D [weight; 129 ± 14 kg, glycated hemoglobin (HbA1c); 7.0 ± 0.9%, body mass index (BMI); 43.2 ± 5.3 kg/m(2), mean ± SD] and twelve matched obese NGT subjects [weight; 127 ± 15 kg, HbA1c; 5.5 ± 0.4%, BMI; 41.5 ± 4.8 kg/m(2), mean ± SD] were examined before, one week, three months, and one year after surgery. Interleukin (IL)-6, leptin, adiponectin, IL-8, transforming growth factor beta (TGF-β), and the incretin hormone glucagon-like peptide-1 (GLP-1) were measured in the fasting state and during a liquid meal. Insulin resistance was evaluated by HOMA-IR.

RESULTS

Weight loss did not differ between the two groups. Before surgery, HbA1c was higher and HOMA-IR lower in T2D patients, however, converged to the values of NGT subjects one year after surgery. Circulating cytokine concentrations did not differ between the two groups at any time point. One week after surgery, circulating IL-6 and IL-8 were increased, while adiponectin and leptin were reduced compared with pre-surgical concentrations. Three months after surgery, IL-8 was increased, leptin was reduced, and no change was observed for IL-6, TGF-β, and adiponectin. One year after surgery, concentrations of IL-6, TGF-β, and leptin were significantly reduced compared to before surgery, while adiponectin was significantly increased.

CONCLUSIONS

One year after RYGB, fasting concentrations of IL-6 and leptin were reduced, while no changes were observed in IL-8. TGF-β was decreased and adiponectin increased in both T2D and NGT obese subjects. This study is the first to examine IL-8 and TGF-β in obese subject after RYGB. Resolution of inflammation could offer a potential explanation for the health improvement associated with major weight loss after bariatric surgery.

TRIAL REGISTRATION

http://www.clinicaltrials.gov (NCT01579981).

Adipose tissue immune response: novel triggers and consequences for chronic inflammatory conditions

Adipose tissue inflammation mediates the association between excessive body fat accumulation and several chronic inflammatory diseases. A high prevalence of obesity-associated adipose tissue inflammation was observed not only in patients with cardiovascular conditions but also in patients with inflammatory bowel diseases, abdominal aortic aneurysm, or cardiorenal syndrome. In addition to excessive caloric intake, other triggers promote visceral adipose tissue inflammation followed by chronic, low-grade systemic inflammation. The infiltration and accumulation of immune cells in the inflamed and hypertrophied adipose tissue promote the production of inflammatory cytokines, contributing to target organ damages. This comorbidity seems to delimit subgroups of individuals with systemic adipose tissue inflammation and more severe chronic inflammatory diseases that are refractory to conventional treatment. This review highlights the association between adipose tissue immune response and the pathophysiology of visceral adiposity-related chronic inflammatory diseases, while suggesting several new therapeutic strategies.

Metabolic surgery: action via hormonal milieu changes, changes in bile acids or gut microbiota? A summary of the literature

Obesity and type 2 diabetes remain epidemic problems. Different bariatric surgical techniques causes weight loss and diabetes remission to varying degrees. The underlying mechanisms of the beneficial effects of bariatric surgery are complex, and include changes in diet and behaviour, as well as changes in hormones, bile acid flow, and gut bacteria. We summarized the effects of multiple different bariatric procedures, and their resulting effects on several hormones (leptin, ghrelin, adiponectin, glucagon-like peptide 1 (GLP-1), peptide YY, and glucagon), bile acid changes in the gut and the serum, and resulting changes to the gut microbiome. As much as possible, we have tried to incorporate multiple studies to try to explain underlying mechanistic changes. What emerges from the data is a picture of clear differences between restrictive and metabolic procedures. The latter, in particular the roux-en-Y gastric bypass, induces large and distinctive changes in most measured fat and gut hormones, including early and sustained increase in GLP-1, possible through intestinal bile acid signalling. The changes in bile flow and the gut microbiome are causally inseparable so far, but new studies show that each contributes to the effects of weight loss and diabetes resolution.

Adipose tissue depot and cell size dependency of adiponectin synthesis and secretion in human obesity

Adiponectin is an insulin sensitizing fat cell (FC) hormone whose levels are related to adipose tissue (AT) mass and depot distribution. We hypothesized that the nature of AT expansion (hypertrophy vs. hyperplasia) contributes to obesity-related reductions in serum adiponectin and that this effect is influenced by the regional distribution of AT to subcutaneous (S) and visceral (V) depots. Thirteen obese subjects provided paired AT biopsies. Serum total and high molecular weight (HMW) adiponectin levels were determined by ELISA. Secretion was quantified following 24-h explant culture. FC size, number, % large, and % small FC were determined by microscopic analysis. Secretion of total adiponectin was highest by SAT (P = 0.008) and correlated more strongly with serum adiponectin (total: P = 0.015, r = 0.77; HMW: P = 0.005, r = 0.83) than did secretion by VAT (P = 0.05, r = 0.66 for both). FC size was greatest in SAT and correlated negatively with both serum (total: P = 0.01, r = −0.74; HMW: P = 0.03, r = −0.69) and secreted (total: P = 0.05, r = −0.72; HMW: P = 0.02, r = −0.87) adiponectin. The % small FC in SAT correlated positively with both serum (total: P = 0.006, r = 0.87; HMW: P = 0.009, r = 0.79) and secreted (total: P = 0.03, r = 0.75; HMW: P = 0.01, r = 0.92) adiponectin. VAT FC size correlated negatively with serum HMW adiponectin (P = 0.01, r = −0.76) but not with any measure of secretion. VAT had the greatest % small FC, which related positively to serum HMW (P = 0.004, r = 0.81) and to secreted total adiponectin (P = 0.02, r = 0.78). These studies indicate that differences in fat cell size and depot distribution of AT expansion are important influences on adiponectin in obesity.

Adiponectin oligomers as potential indicators of adipose tissue improvement in obese subjects

OBJECTIVE

Adiponectin is an adipocytokine that exerts beneficial effects on obesity and related disorders by two receptors (ADIPORs). Adiponectin is produced as a monomer that circulates in serum as different oligomers. The oligomerization state and the tissue expression of adiponectin and ADIPORs are linked to its biological activities. In this study, the levels of total adiponectin and its oligomers were evaluated in relation to obesity and surgical weight loss. The expression of adiponectin and ADIPORs was analyzed in visceral and subcutaneous adipose tissues of obese patients.

DESIGN AND METHODS

In 25 obese patients and 44 age- and sex-matched controls, the serum levels of adiponectin and its oligomers were measured and compared by ELISA, western blotting, and gel filtration. The expression of adiponectin and ADIPORs in both adipose tissues was evaluated by real-time quantitative PCR and western blotting.

RESULTS

The amount of each adiponectin oligomer, including the monomer, increases after weight loss. The reduced circulating levels of adiponectin and its oligomers are not associated with the adipose tissue depot-specific expression of adiponectin and ADIPORs.

CONCLUSIONS

Our results suggest that in patients, adiposity is associated with the serum concentrations of adiponectin and its oligomers but not with adipose tissue depot-specific expression of adiponectin and ADIPORs. In particular, the increase in adiponectin monomer levels could probably be related to the improvement of the whole-body energy metabolism then being involved in the improvement of adipose tissue function after weight loss. This work indicates the importance of assessing the whole adiponectin oligomeric profile as further potential indicators of adipose tissue functions in obesity.

Short-term effects of fish and fish oil consumption on total and high molecular weight adiponectin levels in overweight and obese adults

OBJECTIVE

Fish or fish oil consumption may increase levels of total and high molecular weight (HMW) adiponectin, a hormone associated with anti-inflammatory and insulin-sensitising effects, however it is not known if the effects of the food and supplement are the same. The aim of this study was to compare the effect of consuming fish and fish oil supplements on plasma total and HMW adiponectin concentrations in overweight human participants.

MATERIALS/METHODS

29 overweight and obese participants underwent a two week run-in period, followed by a four week isocaloric dietary intervention which provided 1.8 g of long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) in the form of either fish or fish oil supplements. Primary outcomes were changes in plasma total and HMW adiponectin. Secondary outcomes were changes in anthropometric variables, plasma insulin and glucose levels, and dietary intakes.

RESULTS

Changes in plasma HMW adiponectin during the intervention period were significantly different between groups (p=0.009). Mean HMW adiponectin increased by 0.29 μg/mL in the 'fish' group and decreased by 0.60 μg/mL in the 'supplement' group. There were no significant changes in other anthropometric and biochemical variables. Dietary data suggested the 'fish' group significantly increased their fish (p=0.001) and dietary LC n-3 PUFA (p=0.001) consumption over the course of the study.

CONCLUSIONS

Short-term consumption of fish and fish oil supplements did not have the same effects on HMW adiponectin levels. The impact of fish intake on HMW adiponectin levels may not be mediated by its LC n-3 PUFA content alone.

Clues from bariatric surgery: reversing insulin resistance to heal the heart

Obesity is a state of metabolic dysregulation of the whole organism and a major contributing factor to the epidemic of insulin resistant diabetes. The nonpharmacologic treatment of obesity with bariatric surgery results in a dramatic and almost instantaneous reversal of insulin resistance. The present review collectively addresses the evidence for this phenomenon in the literature and discusses potential metabolic and neurohumoral mechanisms. We propose that nutrient restriction lowers the cell's defense mechanisms for nutrient overload in insulin responsive organs.

Adiponectin: a key playmaker adipocytokine in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and can progress to cirrhosis, liver failure, and hepatocellular carcinoma. In the last two decades, the prevalence of NAFLD has been growing in most developed countries, mainly as a consequence of its close association with obesity and diabetes mellitus. The exact pathogenesis of NAFLD and especially the mechanisms leading to disease progression have not been completely understood. Adipocytes produce and secrete several bioactive substances known as adipocytokines which are implicated in the pathogenesis of the disease. Among them, adiponectin is an insulin-sensitizing adipocytokine possessing multiple beneficial effects on obesity-related medical complication. This review focuses on the role of adiponectin in NAFLD pathogenesis and its potential use as a diagnostic tool but also as therapeutic target for NAFLD management.

Effect of weight reduction following bariatric surgery on serum visfatin and adiponectin levels in morbidly obese subjects

OBJECTIVE

Adipokines are signaling and mediator proteins secreted from adipose tissue. A novel adipokine, visfatin, was reported as a protein which was mainly expressed in visceral adipose tissue. Controversial results have been shown regarding the changes of adipokines following weight reduction. So we investigated the effects of weight reduction on serum concentrations of adiponectin and visfatin in morbidly obese subjects.

METHODS

35 severely obese patients (26 females and 9 males), aged 15-58 years, were studied. Anthropometric parameters and biochemical parameters as well as adiponectin and visfatin were analyzed before and 6 weeks after weight reduction.

RESULTS

Anthropometric indices decreased significantly. Blood levels of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride were reduced significantly. The reduction of visfatin and the elevation of adiponectin were significant as well. However, other parameters like fasting glucose and insulin did not change. Moreover, we could not find any significant correlation between the change of serum visfatin and that of adiponectin.

CONCLUSIONS

6-week weight reduction after bariatric surgery resulted in decreased serum visfatin and increased adiponectin levels. However, we cannot find any significant correlation between changes of adiponectin, visfatin, BMI, waist circumference, and insulin resistance. Further studies with different design are suggested to clarify these associations.

Low circulating adropin concentrations with obesity and aging correlate with risk factors for metabolic disease and increase after gastric bypass surgery in humans

CONTEXT

Mouse studies suggest that adropin, a peptide hormone, is required for metabolic homeostasis and prevention of obesity-associated insulin resistance. Whether obesity and insulin resistance are associated with low plasma adropin levels in humans is not known.

OBJECTIVES

Our objective was to investigate the hypothesis that obesity and indicators of insulin resistance are associated with low adropin levels and determine whether weight loss regulates adropin levels.

DESIGN AND PARTICIPANTS

Plasma was obtained from 85 female [age 21-67 yr, body mass index (BMI) 19.4-71.5 kg/m2] and 45 male (age 18-70 yr, BMI 19.1-62.6 kg/m2) volunteers for other clinical studies. The impact of Roux-en-Y gastric bypass was investigated in 19 obese females (BMI 37-65 kg/m2) using samples collected at baseline and 1-12 months after surgery.

RESULTS

Adropin levels correlate negatively with BMI (r=-0.335, P<0.001) and age (r=-0.263, P=0.003). Age-adjusted adropin levels are higher in males [4.1 ng/ml; 95% confidence interval (CI)=3.6-4.6 ng/ml] than females (3.0 ng/ml; 95% CI=2.6-3.4 ng/ml) (P=0.001). In all subjects, lower age-adjusted adropin levels were observed in overweight (3.3 ng/ml; 95% CI=2.8-3.8 ng/ml, P=0.033) and obese (2.7 ng/ml; 95% CI=2.1-3.3 ng/ml, P=0.001) compared with healthy-weight subjects (4.1 ng/ml; 95% CI=3.6-4.5 ng/ml). This effect was gender specific (weight category×gender, P<0.001) and was observed in males only. Aging and diagnosis with two or more metabolic syndrome risk factors was associated with low adropin levels, irrespective of sex. Adropin concentrations increased after Roux-en-Y gastric bypass, peaking 3 months after surgery (P<0.01).

CONCLUSIONS

Although males exhibit higher adropin levels that are reduced by obesity, aging and markers of insulin resistance are associated with low plasma adropin irrespective of sex.

Partial small bowel resection with sleeve gastrectomy increases adiponectin levels and improves glucose homeostasis in obese rodents with type 2 diabetes

BACKGROUND

The aim of this study was to examine the effect of small bowel resection with and without sleeve gastrectomy on glucose homeostasis in an obese rodent model of type 2 diabetes.

METHODS

Zucker diabetic fatty rats were randomized into three surgical groups: Sham, small bowel resection, and small bowel resection with sleeve gastrectomy (BRSG). Weight and fasting glucose levels were measured at randomization and monitored after surgery. Oral glucose tolerance testing was performed at baseline and 45 days after surgery to assess glucose homeostasis and peptide changes.

RESULTS

At baseline, all animals exhibited impaired glucose tolerance and showed no difference in weight or fasting (area under the curve) AUC(glucose). At sacrifice, Sham animals weighed more than BRSG animals (p = 0.047). At day 45, the Sham group experienced a significant increase in AUC(glucose) compared to baseline (p = 0.02), whereas there was no difference in AUC(glucose) in either surgical group at any time point: BR (p = 0.58) and BRSG (p = 0.56). Single-factor ANOVA showed a significant difference in AUC(glucose) of p = 0.004 between groups postoperatively: Sham (50,745 ± 11,170) versus BR (23,865 ± 432.6) (p = 0.01); Sham versus BRSG (28,710 ± 3188.8) (p = 0.02). There was no difference in plasma insulin, GLP-1, or adiponectin levels before surgery, although 45 days following surgery adiponectin levels where higher in the BRSG group (p = 0.004).

CONCLUSIONS

Partial small bowel resection improved glucose tolerance independent of weight. The combination of small bowel resection and sleeve gastrectomy leads to an increase in adiponectin levels, which may contribute to improved glucose homeostasis.

Mechanisms of improved glycaemic control after Roux-en-Y gastric bypass

Roux-en-Y gastric bypass (RYGB) greatly improves glycaemic control in morbidly obese patients with type 2 diabetes, in many even before significant weight loss. Understanding the responsible mechanisms may contribute to our knowledge of the pathophysiology of type 2 diabetes and help identify new drug targets or improve surgical techniques. This review summarises the present knowledge based on pathophysiological studies published during the last decade. Taken together, two main mechanisms seem to be responsible for the early improvement in glycaemic control after RYGB: (1) an increase in hepatic insulin sensitivity induced, at least in part, by energy restriction and (2) improved beta cell function associated with an exaggerated postprandial glucagon-like peptide 1 secretion owing to the altered transit of nutrients. Later a weight loss induced improvement in peripheral insulin sensitivity follows.

Role of Gut-Related Peptides and Other Hormones in the Amelioration of Type 2 Diabetes after Roux-en-Y Gastric Bypass Surgery

Bariatric surgery is currently the most effective and durable therapy for obesity. Roux-en-Y gastric bypass surgery, the most commonly performed procedure worldwide, causes substantial weight loss and improvement in several comorbidities associated with obesity, especially type 2 diabetes. Several mechanisms are proposed to explain the improvement in glucose metabolism after RYGB surgery: the caloric restriction and weight loss per se, the improvement in insulin resistance and beta cell function, and finally the alterations in the various gastrointestinal hormones and adipokines that have been shown to play an important role in glucose homeostasis. However, the timing, exact changes of these hormones, and the relative importance of these changes in the metabolic improvement postbariatric surgery remain to be further clarified. This paper reviews the various changes post-RYGB in adipokines and gut peptides in subjects with T2D.

Omental gene expression of adiponectin correlates with degree of insulin sensitivity before and after gastric bypass surgery

BACKGROUND

Circulating adiponectin is known to correlate negatively with insulin resistance in patients with obesity and diabetes. The aim of this study was to assess the effect of gastric bypass (GB) surgery on adiponectin gene expression in subcutaneous and omental adipose tissues.

METHODS

Adipose tissues and plasma were obtained from 25 subjects undergoing GB surgery, 15 non-obese subjects, and 12 subjects after GB surgery. Real-time quantitative reverse transcription polymerase chain reaction was used for analysis of the adipose tissues. Adiponectin expression was normalized for glyceraldehyde 3-phosphate dehydrogenase and expressed as percentage of subject-matched subcutaneous expression which was given an arbitrary value of 100%. Insulin resistance was assessed by the homeostatic model assessment (HOMA). Circulating adiponectin was assayed by ELISA.

RESULTS

Omental adiponectin gene expression was fivefold higher in subjects after GB when compared with age-matched morbidly obese subjects before GB (P < 0.01). There were no statistical differences in omental adiponectin gene expression observed in subjects after GB and age-matched non-obese subjects. For the entire cohort of subjects, there was a significant negative correlation between omental adiponectin expression and insulin resistance expressed by HOMA values (r = -0.62, P < 0.001). Circulating adiponectin was significantly lower (P < 0.05) in the obese group than in the non-obese and post-GB groups.

CONCLUSIONS

Omental adiponectin gene expression significantly increases after GB surgery reaching levels equal to age-matched non-obese subjects. Omental adiponectin expression has a significant negative correlation with the insulin resistance status.

Serum leptin levels are inversely correlated with omental gene expression of adiponectin and markedly decreased after gastric bypass surgery

BACKGROUND

Adipose tissue is the most abundant endocrine tissue in the body, producing leptin, a hormone important in regulating hunger, and adiponectin, a hormone involved in insulin sensitivity and inflammation. This study aimed to assess the impact of gastric bypass surgery (GBS) on leptin levels and its relation to the adipose tissue expression of adiponectin.

METHODS

Omental and subcutaneous adipose tissue and serum were obtained from 40 obese patients undergoing GBS, from 13 patients 1 year or more after GBS, and from 16 non-obese individuals with a body mass index of 20 to 29 kg/m(2). Adiponectin gene expression was measured by quantitative real-time polymerase chain reaction, and the gene expression was normalized for the GAPDH gene. Serum leptin and adiponectin were measured by a high-sensitivity enzymatic assay.

RESULTS

Leptin levels were significantly lower in the post-GBS patients (19.8 ± 6.7) than in the pre-GBS patients (59.0 ± 5.1; P = 0.0001), and similar to those in the non-obese control subjects (18.2 ± 4; P = 0.8). Univariate analysis showed an inverse correlation between serum leptin levels and omental adiponectin gene expression (r = -0.32; P = 0.01).

CONCLUSIONS

Gastric bypass surgery results in resolution of the leptin resistance status that characterizes obese subjects. The study also demonstrated a significant correlation between leptin and adiponectin. This correlation provides preliminary evidence for studying a potential adiponectin-leptin cross-talking that may represent one of the physiologic pathways responsible for the regulation of food intake in humans.

Metabolic surgery-principles and current concepts

INTRODUCTION

In the almost six decades of bariatric surgery, a variety of surgical approaches to treating morbid obesity have been developed.

HISTORY AND EVOLUTION

Rather than prior techniques being continually superseded by new ones, a broad choice of surgical solutions based on restrictive, malabsorptive, humoral effects, or combinations thereof, is now available. In fact, in recent years, the advent of surgically modifying human metabolism promises new approaches to ameliorate traditionally medically treated metabolic entities, i.e., diabetes, even in the non-obese. The understanding of the various metabolic effects have led to a paradigm shift from bariatric surgery as a solely weight-reducing procedure to metabolic surgery affecting whole body metabolism.

CONCLUSION

The bariatric surgeon now faces the challenge and opportunity of selecting the most suitable technique for each individual case. To assist in such decision-making, this review, Metabolic surgery-principles and current concepts, is presented, tracing the historical development; describing the various surgical techniques; elucidating the mechanisms by which glycemic control can be achieved that involve favorable changes in insulin secretion and insulin sensitivity, gut hormones, adipokines, energy expenditure, appetite, and preference for low glycemic index foods; as well as exploring the fascinating future potential of this new interdisciplinary field.

Weight loss and changes in salivary ghrelin and adiponectin: comparison between sleeve gastrectomy and Roux-en-Y gastric bypass and gastric banding

BACKGROUND

Weight loss is associated with increased levels of adiponectin with a greater increase observed following Roux-en-Y gastric bypass (RYGB) compared to restrictive procedures. However, currently there are no data on changes in adiponectin following laparoscopic sleeve gastrectomy (LSG). Ghrelin was reported to be also produced by the salivary glands. There are also no data available regarding its changes following bariatric surgery.

METHODS

The present study examined weight loss, and salivary ghrelin and HMW adiponectin levels in 43 morbidly obese subjects undergoing three different types of bariatric surgery.

RESULTS

We found that weight loss following LSG is superior to laparoscopic adjustable gastric banding (LAGB) and comparable to RYGB at 12 months after surgery. Although blood glucose decreased similarly following all three procedures, fasting insulin continuously declined only in LSG and RYGB patients. Changes in both fasting and postprandial salivary ghrelin greatly varied between all three procedures with no similarities to changes in serum ghrelin reported in the literature. HMW adiponectin significantly increased following LSG, and this increase was more marked than in LAGB patients and almost identical compared to RYGB.

CONCLUSIONS

Weight loss following LSG is comparable to RYGB in the short term. Changes in HMW adiponectin are comparable following LSG and RYGB which may further contribute to the successful results after LSG. Furthermore, the results of the present study support the hypothesis that there is an autonomous production of ghrelin in salivary glands irrespective of nutritional status and weight loss.

Distinct adiponectin profiles might contribute to differences in susceptibility to type 2 diabetes in dogs and humans

Dogs develop obesity-associated insulin resistance but not type 2 diabetes mellitus. Low adiponectin is associated with progression to type 2 diabetes in obese humans. The aims of this study were to compare total and high molecular weight (HMW) adiponectin and the ratio of HMW to total adiponectin (S(A)) between dogs and humans and to examine whether total or HMW adiponectin or both are associated with insulin resistance in naturally occurring obese dogs. We compared adiponectin profiles between 10 lean dogs and 10 lean humans and between 6 lean dogs and 6 age- and sex-matched, client-owned obese dogs. Total adiponectin was measured with assays validated in each species. We measured S(A) with velocity centrifugation on sucrose gradients. The effect of total and HMW adiponectin concentrations on MINMOD-estimated insulin sensitivity was assessed with linear regression. Lean dogs had total and HMW adiponectin concentrations three to four times higher than lean humans (total: dogs 32 ± 5.6 mg/L, humans 10 ± 1.3 mg/L, P<0.001; HMW: dogs 25 ± 4.5 mg/L, humans 6 ± 1.3 mg/L, P<0.001) and a higher S(A) (dogs: 0.78 ± 0.05; humans: 0.54 ± 0.08, P = 0.002). Adiponectin concentrations and S(A) were not lower in obese dogs (0.76 ± 0.05 in both groups; P=1). Total adiponectin, HMW adiponectin, and S(A) were not associated with insulin sensitivity in dogs. We propose that differences in adiponectin profiles between humans and dogs might contribute to the propensity of humans but not dogs to develop type 2 diabetes. Dogs with chronic, naturally occurring obesity do not have selectively reduced HMW adiponectin, and adiponectin does not appear to be important in the development of canine obesity-associated insulin resistance.

Obesity, metabolic syndrome and esophageal adenocarcinoma: epidemiology, etiology and new targets

BACKGROUND

Rates of distal and junctional adenocarcinomas are increasing in Western countries.

METHODS

Systematic review of epidemiological evidence linking obesity to esophageal adenocarcinoma (EA) was performed for studies published from 2005 to 2010. The current understanding of obesity's role in the etiology and potential dysplastic progression of Barrett's esophagus (BE) to EA is reviewed.

RESULTS

Accumulating epidemiological studies provide evidence of obesity's role as a driving force behind the increasing rates of EA. The simplest construct is that obesity promotes reflux, causing chronic inflammation and BE, predisposing to adenocarcinoma. However, as obesity is positively associated with the prevalence of many cancers, other mechanisms are important. A link may exist between fat distribution patterns and the risk of BE and EA. Altered metabolic profiles in the metabolic syndrome (MetS) may be a key factor in cell cycle/genetic abnormalities that mark the progression of BE towards cancer. Research highlighting a unique role of MetS in the length of BE, and its association with systemic inflammation and insulin resistance is discussed, as well as adipokine receptor expression in both BE and esophageal epithelium, and how MetS and the systemic response impacts on key regulators of inflammation and tumorigenesis. CONCLUSIONS/IMPACT: Obesity is positively associated with EA. The systemic inflammatory state consequent on the altered metabolism of obese patients, and the associated impact of adipocytokines and pro-coagulant factors released by adipocytes in central fat, may underlie obesity's relationship to this cancer. Novel therapeutic agents that may antagonize adipo-cytokines and potentially offer a promising role in cancer therapy are discussed.

Effects of weight loss, induced by gastric bypass surgery, on HDL remodeling in obese women

Plasma lipoproteins and glucose homeostasis were evaluated after marked weight loss before and over 12 months following Roux-en-Y gastric-bypass (RYGBP) surgery in 19 morbidly obese women. Standard lipids, remnant-lipoprotein cholesterol (RLP-C); HDL-triglyceride (TG); apolipoproteins (apo) A-I, A-II, E, and A-I-containing HDL subpopulations; lecithin-cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP) mass and activity; plasma glucose and insulin levels were measured before and at 1, 3, 6, and 12 months after GBP surgery. Baseline concentrations of TG, RLP-C, glucose, and insulin were significantly higher in obese than in normal-weight, age-matched women, whereas HDL cholesterol (HDL-C), apoA-I, apoA-II, alpha-1 and alpha-2 levels were significantly lower. Over 1 year, significant decreases of body mass index, glucose, insulin, TG, RLP-C, HDL-TG, and prebeta-1 levels were observed with significant increases of HDL-C and alpha-1 levels (all P < 0.05). Changes of fat mass were correlated with those of LDL cholesterol (P = 0.018) and LCAT mass (P = 0.011), but not with CETP mass (P = 0.265). Changes of fasting plasma glucose concentrations were inversely correlated with those of CETP mass (P = 0.005) and alpha-1 level (P = 0.004). Changes of fasting plasma insulin concentrations were positively correlated with those of LCAT mass (P = 0.043) and inversely with changes of alpha-1 (P = 0.03) and alpha-2 (P = 0.05) concentrations. These results demonstrate beneficial changes in HDL remodeling following substantial weight loss induced by RYGBP surgery and that these changes are associated with improvement of glucose homeostasis in these patients.

Roux-en-Y gastric bypass alters tumor necrosis factor-α but not adiponectin signaling in immediate postoperative period in obese rats

BACKGROUND

Adiponectin has anti-inflammatory properties and is increased with weight loss. Tumor necrosis factor (TNF)-α is a pro-inflammatory cytokine that negatively regulates adiponectin. Previously, we have demonstrated that Roux-en-Y gastric bypass (RYGB) induces weight loss and improves steatosis in obese rats. We hypothesized that RYGB would alter the interplay of TNF-α and adiponectin signaling in the postoperative period.

METHODS

Obese Sprague-Dawley male rats that had undergone RYGB (n = 5) or sham (n = 4) were euthanatized at 9 weeks postoperatively. The adiponectin levels from serial serum samples were measured by enzyme-linked immunosorbent assay. Adiponectin, adiponectin receptor 2, and TNF-α mRNA from adipose and liver samples were quantified by reverse transcriptase-polymerase chain reaction. Data are presented as mean ± standard deviation; using a t test, P <.05 was significant.

RESULTS

RYGB did not change the serum adiponectin, adipose tissue adiponectin mRNA, or hepatic adiponectin receptor 2 levels compared with the levels in the sham-operated rats (P >.05). However, the TNF-α mRNA levels had decreased in the adipose tissue (P >.05) but remained unchanged in the liver compared with the sham controls (P >.05).

CONCLUSION

Surgically-induced weight loss in a rat model of RYGB did not increase adiponectin signaling in the immediate postoperative period but was associated with decreased pro-inflammatory signaling in the adipose tissue. During this period, pro-inflammatory signaling might play a more important role than adiponectin. Additional studies with longer follow-up are necessary to determine whether adiponectin plays a role in weight loss and improvement of steatosis after RYGB.

Overcoming metabolic syndrome in severe obesity: adiponectin as a marker of insulin sensitivity and HDL-cholesterol improvements after gastric bypass

OBJECTIVE

To assess the relationship between adiponectin and metabolic parameters in severely obese women during surgical-induced weight loss.

METHODS

Nineteen lean (CT - BMI:21.2 +/- 0.3 kg.m(2)), 14 overweight/class II obese (OB/OW - BMI: 29.7 +/- 0.7 kg/m(2)) and 8 morbidly obese (OBIII - BMI: 56.4 +/- 3.6 kg/m(2)) were evaluated by hyperinsulinemic-euglycemic clamp, adiponectin, and lipids. OBIII were evaluated at 5th and 16th month post-operatively.

RESULTS

Compared to lean, obese groups had lower adiponectin (OB/OW: 9.4 +/- 0.9, OBIII: 7.1 +/- 1.3 versus 12.2 +/- 0.9 ng/dL; p < 0.01), lower HDL-cholesterol (OB/OW:1.05 +/- 0.05, OBIII: 0.88 +/- 0.04 versus 1.22 +/- 0.07 mmol/L; p < 0.01) and insulin resistance-IR (glucose uptake, M-value - OB/OW: 43.6 +/- 2.7, OBIII: 32.4 +/- 3.2 versus 20.0 +/- 1.8 umol/kgFFM.min; p < 0.001). Considering all subjects, adiponectin levels were inversely correlated to BMI and waist circumference, and directly to M-value and HDL-cholesterol (p < 0.01). During weight loss, improvements in IR (Study III: 36.1 +/- 3.9 umol/kg/FFM.min, p < 0.0001), adiponectin (11.8 +/- 1.4 ng/dL, p = 0.006) and HDL-cholesterol were observed (1.10 +/- 0.04 mmol/L, p = 0.007). Moreover, HDL-cholesterol improvement was significantly and independently related to variations of adiponectin and BMI (r(2) = 0.86; p < 0.0002).

CONCLUSIONS

The improvements of IR and adiponectin were related to surgical-induced weight loss, suggesting an important role of adiponectin in HDL-cholesterol regulation.

Protective roles of adiponectin in obesity-related fatty liver diseases: mechanisms and therapeutic implications

Adiponectin is an insulin-sensitizing adipokine possessing multiple beneficial effects on obesity-related medical complications. This adipokine is secreted from adipocytes into the circulation as three oligomeric isoforms, including trimer, hexamer and the high molecular weight (HMW) oligomeric complex. Each oligomeric isoform of adiponectin possesses distinct biological properties and activates different signaling pathways in various target tissues. The hepato-protective activities have been demonstrated by many clinical and experimental studies. The decreased level of serum adiponectin represents an independent risk factor for nonalcoholic fatty liver disease (NAFLD) and liver dysfunctions in humans. In animals, elevation of circulating adiponectin by either pharmacological or genetic approaches leads to a significant alleviation of hepatomegaly, steatosis and necro-inflammation associated with various liver diseases. In adiponectin knockout mice, there is a pre-existing condition of hepatic steatosis and mitochondria dysfunction, which might contribute to the increased vulnerabilities of these mice to the secondary liver injuries induced by obesity and other conditions. This review aims to summarize recent advances on delineation of the structural, molecular and cellular mechanisms underlying the hepato-protective properties of adiponectin.

A review of weight loss following Roux-en-Y gastric bypass vs restrictive bariatric surgery: impact on adiponectin and insulin

BACKGROUND

Bariatric surgery is a common procedure often used to ameliorate comorbidities associated with obesity, including type 2 diabetes. Substantial weight loss leads to alterations in inflammation and insulin sensitivity as well as numerous metabolic and physiologic pathways. Several inflammatory markers have been evaluated, yet adiponectin, an anti-inflammatory adipokine, has not been fully investigated. Adiponectin may play a key role as a mediator between obesity and inflammation, as lower blood levels are more commonly associated with obesity and type 2 diabetes and because adiponectin lessens insulin resistance. This review evaluates outcome variables from patients who underwent Roux-en-Y gastric bypass (RYGB) or restrictive bariatric surgery to compare and contrast any differential surgical impacts on weight loss, adiponectin, and insulin.

METHODS

A systematic literature review was conducted using a PubMed search. Published studies from 1999 to 2009 that measured blood levels of adiponectin and insulin in bariatric surgery patients prior to and at least 6 months after surgery were included.

RESULTS

Eighteen studies met inclusion criteria for evaluation. RYGB surgery compared to restrictive surgery led to significantly greater weight loss and improvements in adiponectin and insulin sensitivity. Despite significant weight loss, many patients did not achieve "healthy" body mass index or normalization of inflammatory markers.

CONCLUSIONS

While RYGB surgery appears to more favorably influence body weight and inflammatory markers, data are insufficient to fully understand the impact of bariatric surgery on changes in adiponectin and insulin and related health implications. Long-term research is needed to more thoroughly evaluate inflammatory outcomes following these two bariatric surgery procedures.

Serum bile acid along with plasma incretins and serum high-molecular weight adiponectin levels are increased after bariatric surgery

Bariatric surgery has been shown to improve glucose tolerance, although the mechanism has not been fully elucidated. Animal studies have suggested important roles of bile acid (BA) as a regulator of energy homeostasis and glucose metabolism. However, little is known about its role in humans. We investigated the longitudinal changes of BA, incretins, and adipokines after significant weight reduction in 34 Japanese adults with morbid obesity who underwent laparoscopic bariatric surgery. In subjects who underwent malabsorptive or restrictive surgery, body mass index had markedly decreased from 43.0 +/- 6.5 (SD) to 37.8 +/- 5.7 kg/m(2) and from 45.3 +/- 11.2 to 41.5 +/- 10.5 kg/m(2), respectively, at 1 month after surgery. Glycated hemoglobin decreased from 6.1% +/- 1.5% to 5.2% +/- 0.4% and from 6.2% +/- 1.3% to 5.4% +/- 0.7%, and total BA level increased from 3.1 +/- 3.5 to 7.2 +/- 5.3 mumol/L and from 3.2 +/- 2.6 to 9.4 +/- 10.0 mumol/L, respectively. At baseline, serum concentration of primary BA was positively correlated with plasma gastric inhibitory polypeptide level (r = 0.548, P = .001); and change in primary BA level was positively correlated with changes in plasma gastric inhibitory polypeptide (r = 0.626, P = .001) and serum immunoreactive insulin level (r = 0.592, P = .002) at 1 month after surgery. Furthermore, plasma glucagon-like peptide-1 and serum high-molecular weight adiponectin levels increased in both surgeries. These hormonal changes might explain the mechanism(s) of improved glucose tolerance after bariatric surgery in morbidly obese subjects.

Unique profile of chicken adiponectin, a predominantly heavy molecular weight multimer, and relationship to visceral adiposity

Adiponectin, a 30-kDa adipokine hormone, circulates as heavy, medium, and light molecular weight isoforms in mammals. Plasma heavy molecular weight (HMW) adiponectin isoform levels are inversely correlated with the incidence of type 2 diabetes in humans. The objectives of the present study were to characterize adiponectin protein and quantify plasma adiponectin levels in chickens, which are naturally hyperglycemic relative to mammals. Using gel filtration column chromatography and Western blot analysis under nonreducing and non-heat-denaturing native conditions, adiponectin in chicken plasma, and adipose tissue is predominantly a multimeric HMW isoform that is larger than 669 kDa mass. Under reducing conditions and heating to 70-100 C, however, a majority of the multimeric adiponectin in chicken plasma and adipose tissue was reduced to oligomeric and/or monomeric forms. Immunoprecipitation and elution under neutral pH preserved the HMW adiponectin multimer, whereas brief exposure to acidic pH led to dissociation of HMW multimer into multiple oligomers. Mass spectrometric analysis of chicken adiponectin revealed the presence of hydroxyproline and differential glycosylation of hydroxylysine residues in the collagenous domain. An enzyme immunoassay was developed and validated for quantifying plasma adiponectin in chickens. Plasma adiponectin levels were found to be significantly lower in 8- compared with 4-wk-old male chickens and inversely related to abdominal fat pad mass. Collectively, our results provide novel evidence that adiponectin in chicken plasma and tissues is predominantly a HMW multimer, suggesting the presence of unique multimerization and stabilization mechanisms in the chicken that favors preponderance of HMW adiponectin over other oligomers.

Inhibition of protein tyrosine phosphatase-1B with antisense oligonucleotides improves insulin sensitivity and increases adiponectin concentrations in monkeys

Protein tyrosine phosphatase (PTP)-1B antagonizes insulin signaling and is a potential therapeutic target for insulin resistance associated with obesity and type 2 diabetes. To date, studies of PTP-1B have been limited by the availability of specific antagonists; however, treatment of rodents with antisense oligonucleotides (ASOs) directed against PTP-1B improves insulin sensitivity, inhibits lipogenic gene expression, and reduces triglyceride accumulation in liver and adipose tissue. Here we investigated ASO-mediated PTP-1B inhibition in primates. First, PTP-1B ASO (ISIS 113715) dose-dependently inhibited PTP-1B mRNA and protein expression in cultured monkey hepatocytes. Subcutaneous administration of ISIS 113715 reduced PTP-1B mRNA expression in liver and adipose tissue of normal-weight monkeys by 40-50% and improved insulin sensitivity during an iv glucose tolerance test (IVGTT). In obese, insulin-resistant rhesus monkeys, treatment with 20 mg/kg ISIS 113715 for 4 wk reduced fasting concentrations of insulin and glucose and reduced insulin responses during an IVGTT. In these animals, adiponectin concentrations were also increased by 70%, most of which was an increase of high-molecular-weight oligomers. These effects were not observed in monkeys on a lower, dose-escalation regimen (1-10 mg/kg over 9 wk). Overall, the increase of adiponectin concentrations during ISIS 113715 treatment was correlated with the lowering of insulin responses during IVGTT (r = -0.47, P = 0.042). These results indicate that inhibition of PTP-1B with ASOs such as ISIS 113715 may be a viable approach for the treatment and prevention of obesity-associated insulin resistance and type 2 diabetes because they potently increase adiponectin concentrations in addition to improving insulin sensitivity.

Secretion of adiponectin multimeric complexes from adipose tissue explants is not modified by very low calorie diet

OBJECTIVE

Adiponectin is a protein abundantly secreted by the adipose tissue (AT). Plasma adiponectin levels are decreased in obese, insulin-resistant, and type 2 diabetic patients. Various multimeric complexes, i.e. high-, middle-, and low-molecular weight isoforms (HMW, MMW and LMW), are present in plasma. Here, we investigated the effect of weight reducing diet on the distribution of adiponectin isoforms in plasma and on their secretion in AT explants from obese subjects.

DESIGN

A total of 20 obese subjects (age 37.8+/-7.3 years, body mass index 33.9+/-5.0 kg/m(2)) underwent eight weeks of very low-calorie diet (VLCD). A needle biopsy of subcutaneous abdominal AT and blood samples were taken before and after dietary intervention. AT explants were incubated in culture medium for 4 h. ELISA assay and western blot analyses were used to identify adiponectin complexes in culture media and in plasma.

RESULTS

The distribution of adiponectin polymers in plasma was different from that secreted in human AT explants. Before VLCD, the relative amount of HMW isoform was 75.5+/-9.1% of total adiponectin in culture media and 52.2+/-11.2% in plasma. Despite the diet-induced weight loss and improvement of insulin sensitivity, VLCD neither induced change in total adiponectin level nor in the ratio of HMW to total adiponectin in plasma and in culture media of AT explants.

CONCLUSIONS

The profile of adiponectin polymeric isoforms secreted by AT explants into culture media differs from the plasma profile. A dietary intervention leading to weight loss and improvement of insulin sensitivity was not associated with modifications of AT secretion of total or HMW adiponectin.

Adiponectin multimers in maternal plasma

OBJECTIVE

Adiponectin is an anti-diabetic, anti-atherogenic, anti-inflammatory, and angiogenic adipokine that circulates in oligomeric complexes including: low molecular weight (LMW) trimers, medium molecular weight (MMW) hexamers, and high molecular weight (HMW) isoforms. The aim of this study was to determine whether there are changes in adiponectin multimers in pregnancy and as a function of maternal weight.

STUDY DESIGN

In this cross-sectional study, plasma concentrations of total, HMW, MMW, and LMW adiponectin were determined in women included in three groups: (1) normal pregnant women of normal body mass index (BMI) (n = 466), (2) overweight pregnant women (BMI >or=25; n = 257), and (3) non-pregnant women of normal weight (n = 40). Blood samples were collected once from each woman between 11 and 42 weeks of gestation. Plasma adiponectin multimer concentrations were determined by enzyme-linked immunosorbent assay (ELISA). Non-parametric statistics were used for analysis.

RESULTS

(1) The median HMW adiponectin concentration and the median HMW/total adiponectin ratio were significantly higher, and the median LMW adiponectin concentration was significantly lower in pregnant women than in non-pregnant women. (2) Among pregnant women, the median plasma concentration of total, HMW, and MMW adiponectin was significantly higher in normal weight women than in overweight patients. (3) Maternal HMW was the most prevalent adiponectin multimer regardless of gestational age or BMI status. (4) There were no significant differences in the median concentration of total, MMW, and LMW adiponectin and their relative distribution with advancing gestation.

CONCLUSION

Human pregnancy is characterized by quantitative and qualitative changes in adiponectin multimers, especially the most active isoform, HMW adiponectin.

Increase in high molecular weight adiponectin by bariatric surgery-induced weight loss

AIM

To determine the changes in adiponectin multimers upon marked weight loss.

METHODS

Plasma samples were obtained preoperatively and 3, 6, 12 and 24 months after surgery from 12 obese subjects undergoing weight loss-inducing bariatric surgery. Seven non-operated obese subjects served as controls. Plasma levels of adiponectin multimers were determined by protease digestion and Enzyme-Linked ImmunoSorbent Assay (ELISA) detection. In addition, adiponectin multimers were assessed by western blotting.

RESULTS

In patients with weight loss after surgery but not in controls, total adiponectin and high molecular weight (HMW) adiponectin steadily increased during the observation period. Twenty-four months after surgery, the increase in total and HMW adiponectin was 2.2 +/- 0.46 and 1.4 +/- 0.3 microg/ml, respectively. In contrast, plasma concentrations of middle and low molecular weight adiponectin remained unchanged.

CONCLUSIONS

The increase in plasma adiponectin levels observed 24 months after bariatric surgery depended on continuous weight loss and was completely attributable to the HMW complex.

Adiponectin multimers and metabolic syndrome traits: relative adiponectin resistance in African Americans

African Americans (AAs) tend to have lower total adiponectin levels compared to European Americans (EA); however, it is not known whether race affects adiponectin multimer distribution and their relationships to metabolic traits. We measured total adiponectin, high molecular weight (HMW), low molecular weight (LMW) (i.e., hexamer), and trimer adiponectin in 132 normoglycemic premenopausal women (75 AAs, 57 EAs), together with measures of total and abdominal fat, plasma lipids, insulin sensitivity (S(i)), and genetic admixture estimates. We found that lower total adiponectin in AAs was explained by reduced LMW, and trimer forms because levels of HMW did not differ between races. In EAs, HMW was highly correlated with multiple metabolic syndrome traits. In contrast, the LMW and trimer forms were most highly correlated with metabolic traits in AAs, including abdominal adiposity, lipids, and S(i). At similar levels of visceral adiposity, AAs exhibited significantly lower LMW adiponectin than EAs. Similarly, at comparable levels of HMW and LMW adiponectin, AAs were more insulin resistant than their EA counterparts. In conclusion, (i) serum adiponectin is lower in AAs predominantly as a result of reduced concentrations of LMW and trimers multimeric forms; (ii) LMW and trimer, not HMW, are most broadly correlated with metabolic traits in AAs. Thus, HMW adiponectin may exert less bioactivity in explaining the metabolic syndrome trait cluster in populations of predominant African genetic background.