Secretory products from human adipocytes stimulate proinflammatory cytokine secretion from human endothelial cells

The Role of Epicardial Adipose Tissue in Acute Coronary Syndromes, Post-Infarct Remodeling and Cardiac Regeneration

Epicardial adipose tissue (EAT) is a fat deposit surrounding the heart and located under the visceral layer of the pericardium. Due to its unique features, the contribution of EAT to the pathogenesis of cardiovascular and metabolic disorders is extensively studied. Especially, EAT can be associated with the onset and development of coronary artery disease, myocardial infarction and post-infarct heart failure which all are significant problems for public health. In this article, we focus on the mechanisms of how EAT impacts acute coronary syndromes. Particular emphasis was placed on the role of inflammation and adipokines secreted by EAT. Moreover, we present how EAT affects the remodeling of the heart following myocardial infarction. We further review the role of EAT as a source of stem cells for cardiac regeneration. In addition, we describe the imaging assessment of EAT, its prognostic value, and its correlation with the clinical characteristics of patients.

Children who appeared or remained overweight or obese predict a higher follow-up blood pressure and higher risk of hypertension: a 6-year longitudinal study in Yantai, China

Few longitudinal studies have examined the effect of weight status change on blood pressure change over time and incidence of hypertension among Chinese children. The longitudinal study enrolled 17,702 Chinese children aged 7 years in Yantai in 2014 as baseline, with a continuous 5 years of follow-up to 2019. Generalized estimating equation model was fitted to examine the main and interaction effects of weight status change and time with blood pressure and the incidence of hypertension. Compared with the participants who remained normal weight, the participants who remained overweight or obese had higher systolic blood pressure (SBP) (β = 2.89, p < 0.001) and diastolic blood pressure (DBP) (β = 1.79, p < 0.001). Significant interactions were identified between weight status change and time with SBP (χ2interaction = 697.77, p < 0.001) and DBP (χ2interaction = 270.49, p < 0.001). The odds ratio (OR) and 95% confidence interval (CI) of hypertension were 1.70 (1.59-1.82) for participants who appeared overweight or obese, 2.26 (2.14-2.40) for participants who remained overweight or obese, compared with the participants who remained normal weight. Those who switched from overweight or obesity to normal weight had almost the same risk of developing hypertension (OR = 1.13, 95% CI: 1.02 to 1.26) as children who remained normal weight. Children who appeared or remained overweight or obese predict a higher follow-up blood pressure and higher risk of hypertension, whereas losing weight could reduce blood pressure and the risk of hypertension. Children who appeared or remained overweight or obese predict a higher follow-up blood pressure and higher risk of hypertension, whereas losing weight could reduce blood pressure and the risk of hypertension.

Role of Chemerin and Perivascular Adipose Tissue Characteristics on Cardiovascular Risk Assessment by Arterial Stiffness Markers in Patients with Morbid Obesity

BACKGROUND AND OBJECTIVE

The development of arterial stiffness (AS) in obesity is a multifactorial and complex process. The pleomorphic actions of adipokines and their local activity in perivascular adipose tissue (PVAT) are potential modulators of AS appearance and progression. We aimed to assess the correlations between two adipokines (chemerin, adiponectin), PVAT morphological changes (adipocyte size, blood vessel wall thickness) and AS parameters in the special subgroup of patients with morbid obesity.

MATERIAL AND METHODS

We enrolled 25 patients with morbid obesity and 25 non-obese patients, who were age- and gender-matched, untreated for cardiovascular risk factors, and admitted to hospital for laparoscopic surgical procedures (bariatric surgery for morbid obesity and non-inflammatory benign pathology surgery for non-obese patients). Before the surgical procedures, we evaluated demographic and anthropometric data and biochemical parameters including the studied adipokines. Arterial stiffness was evaluated using a Medexpert ArteriographTM TL2 device. In both groups, adipocyte size and vascular wall thickness as well as local adiponectin activity were analyzed in PVAT from intraoperative biopsies.

RESULTS

In our study, adiponectin (p = 0.0003), chemerin (p = 0.0001) and their ratio (p = 0.005) had statistically significant higher mean values in patients with morbid obesity compared to normal-weight patients. In patients with morbid obesity there were significant correlations between chemerin and AS parameters such as aortic pulse wave velocity (p = 0.006) and subendocardial viability index (p = 0.009). In the same group adipocyte size was significantly correlated with another AS parameter, namely, aortic systolic blood pressure (p = 0.030). In normal-weight patients, blood vessel wall thickness positively correlated with AS parameters such as brachial (p = 0.023) and aortic augmentation index (p = 0.023). An important finding was the negative adipoR1 and adipoR2 immunoexpression in PVAT adipocytes of patients with morbid obesity. Additionally, we found significant correlations between blood vessel wall thickness and blood fasting glucose (p < 0.05) in both groups.

CONCLUSIONS

Chemerin and adipocyte size could be predictive biomarkers for AS in patients with morbid obesity. Given the small number of patients included, our results need further validation.

Adipose Tissue Paracrine-, Autocrine-, and Matrix-Dependent Signaling during the Development and Progression of Obesity

Obesity is an ever-increasing phenomenon, with 42% of Americans being considered obese (BMI ≥ 30) and 9.2% being considered morbidly obese (BMI ≥ 40) as of 2016. With obesity being characterized by an abundance of adipose tissue expansion, abnormal tissue remodeling is a typical consequence. Importantly, this pathological tissue expansion is associated with many alterations in the cellular populations and phenotypes within the tissue, lending to cellular, paracrine, mechanical, and metabolic alterations that have local and systemic effects, including diabetes and cardiovascular disease. In particular, vascular dynamics shift during the progression of obesity, providing signaling cues that drive metabolic dysfunction. In this review, paracrine-, autocrine-, and matrix-dependent signaling between adipocytes and endothelial cells is discussed in the context of the development and progression of obesity and its consequential diseases, including adipose fibrosis, diabetes, and cardiovascular disease.

Paracrine Role of the Endothelium in Metabolic Homeostasis in Health and Nutrient Excess

The vascular endothelium traditionally viewed as a simple physical barrier between the circulation and tissue is now well-established as a key organ mediating whole organism homeostasis by release of a portfolio of anti-inflammatory and pro-inflammatory vasoactive molecules. Healthy endothelium releases anti-inflammatory signaling molecules such as nitric oxide and prostacyclin; in contrast, diseased endothelium secretes pro-inflammatory signals such as reactive oxygen species, endothelin-1 and tumor necrosis factor-alpha (TNFα). Endothelial dysfunction, which has now been identified as a hallmark of different components of the cardiometabolic syndrome including obesity, type 2 diabetes and hypertension, initiates and drives the progression of tissue damage in these disorders. Recently it has become apparent that, in addition to vasoactive molecules, the vascular endothelium has the potential to secrete a diverse range of small molecules and proteins mediating metabolic processes in adipose tissue (AT), liver, skeletal muscle and the pancreas. AT plays a pivotal role in orchestrating whole-body energy homeostasis and AT dysfunction, characterized by local and systemic inflammation, is central to the metabolic complications of obesity. Thus, understanding and targeting the crosstalk between the endothelium and AT may generate novel therapeutic opportunities for the cardiometabolic syndrome. Here, we provide an overview of the role of the endothelial secretome in controlling the function of AT. The endothelial-derived metabolic regulatory factors are grouped and discussed based on their physical properties and their downstream signaling effects. In addition, we focus on the therapeutic potential of these regulatory factors in treating cardiometabolic syndrome, and discuss areas of future study of potential translatable and clinical significance. The vascular endothelium is emerging as an important paracrine/endocrine organ that secretes regulatory factors in response to nutritional and environmental cues. Endothelial dysfunction may result in imbalanced secretion of these regulatory factors and contribute to the progression of AT and whole body metabolic dysfunction. As the vascular endothelium is the first responder to local nutritional changes and adipocyte-derived signals, future work elucidating the changes in the endothelial secretome is crucial to improve our understanding of the pathophysiology of cardiometabolic disease, and in aiding our development of new therapeutic strategies to treat and prevent cardiometabolic syndrome.

Association of Adipose Tissue and Adipokines with Development of Obesity-Induced Liver Cancer

Obesity is rapidly dispersing all around the world and is closely associated with a high risk of metabolic diseases such as insulin resistance, dyslipidemia, and nonalcoholic fatty liver disease (NAFLD), leading to carcinogenesis, especially hepatocellular carcinoma (HCC). It results from an imbalance between food intake and energy expenditure, leading to an excessive accumulation of adipose tissue (AT). Adipocytes play a substantial role in the tumor microenvironment through the secretion of several adipokines, affecting cancer progression, metastasis, and chemoresistance via diverse signaling pathways. AT is considered an endocrine organ owing to its ability to secrete adipokines, such as leptin, adiponectin, resistin, and a plethora of inflammatory cytokines, which modulate insulin sensitivity and trigger chronic low-grade inflammation in different organs. Even though the precise mechanisms are still unfolding, it is now established that the dysregulated secretion of adipokines by AT contributes to the development of obesity-related metabolic disorders. This review focuses on several obesity-associated adipokines and their impact on obesity-related metabolic diseases, subsequent metabolic complications, and progression to HCC, as well as their role as potential therapeutic targets. The field is rapidly developing, and further research is still required to fully understand the underlying mechanisms for the metabolic actions of adipokines and their role in obesity-associated HCC.

Investigating the Role of Myeloperoxidase and Angiopoietin-like Protein 6 in Obesity and Diabetes

Myeloperoxidase (MPO) is positively associated with obesity and diet-induced insulin resistance. Angiopoietin-like protein 6 (ANGPTL6) regulates metabolic processes and counteract obesity through increased energy expenditure. This study aims to evaluate the plasma MPO and ANGPTL6 levels in obese and diabetic individuals as well as MPO association with biochemical markers of obesity. A total of 238 participants were enrolled, including 137 control and 101 type 2 diabetes (T2D) patients. ANGPTL6 and MPO levels and other biomarkers were measured via ELISA. ANGPTL6 levels were significantly higher in the diabetic population and obese individuals. When the group was stratified based on T2D, ANGPTL6 levels were significantly higher in obese-diabetic participants compared with non-obese-diabetics, but obese-non-diabetic individuals had similar ANGPTL6 levels to their controls. MPO levels were higher in obese compared with non-obese participants but did not differ between T2D and control participants. MPO levels were upregulated in obese compared with non-obese in both diabetics and non-diabetics. MPO was positively associated with ANGPTL6, triglyceride, BMI, TNF-alpha, high-sensitivity C-reactive protein, interleukin-6, and plasminogen activator inhibitor-1. Taken together, our findings suggest that both MPO and ANGPTL6 may regulate obesity, although MPO exerts this effect independent of diabetes while ANGPTL6 may have a modulatory role in diabetes.

Plasma levels of adiponectin and chemerin are associated with early stage of atherosclerosis in older adults with type 2 diabetes mellitus

OBJECTIVE

Adipokines, such as adiponectin and chemerin, regulate fat metabolism and are critical for the development of atherosclerosis. Investigating the correlations of adiponectin and chemerin with atherosclerosis in older adults with type 2 diabetes mellitus (T2DM) will shed light on the search for new markers for early diagnosis of diabetic atherosclerosis.

METHODS

A total of 120 older T2DM patients and nine healthy controls were enrolled in this study. The clinical parameters, such as brachial-ankle pulse wave velocity (ba-PWV), adiponectin, and chemerin, were examined and recorded. T2DM subjects were divided into three groups according to ba-PWV level (high, medium, or low). The data were processed and analyzed by identical methods.

RESULTS

Significantly higher chemerin and lower adiponectin levels were detected in the plasma of T2DM patients than in healthy controls. The plasma levels of chemerin and adiponectin were negatively correlated in T2DM patients. Moreover, chemerin and adiponectin were significantly correlated with body mass index, ankle-brachial index, insulin, and ba-PWV. Multiple linear regression analysis revealed that chemerin and adiponectin were independently affecting ba-PWV.

CONCLUSION

Adiponectin and chemerin are potential markers for diagnosis and monitoring of early stage of atherosclerosis in older adults with T2DM. Further clinical investigations are required to confirm these markers.

Isolated vitamin D supplementation improves the immune-inflammatory biomarkers in younger postmenopausal women: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

The aim of this study was to evaluate the effect of vitamin D (VitD) supplementation on immune-inflammatory biomarkers in younger postmenopausal women.

METHODS

In this double-blind, placebo-controlled trial, 160 postmenopausal women aged 50 to 65 years with amenorrhea ≥12 months were randomized into two groups: VitD group, oral supplementation with 1000 IU VitD3/day (n = 80) or placebo group (n = 80). The intervention time was 9 months, and the women were assessed at baseline and endpoint. Serum levels of interleukins (ILs)-1β, IL-5, IL-6, IL-10, IL-12ρ70, IL-17α, tumor necrosis factor-alpha, and interferon-gamma were determined by immunoassay. Plasma concentrations of 25-hydroxyvitamin D [25(OH)D] were measured by high-performance liquid chromatography. Per-protocol analysis was adopted as the statistical method using a gamma distribution and repeated measures design, followed by Wald's multiple comparisons test.

RESULTS

The two groups were similar at baseline in terms of clinical and laboratory parameters. After 9 months, there was a significant increase of 25(OH)D levels in the VitD group (+45.4%, P < 0.001) and a decrease (-18.5%, P = 0.049) in the placebo group. A significant decrease in IL-5, IL-12p70, IL-17α, tumor necrosis factor-alpha, and interferon-gamma levels was observed in the VitD group (P < 0.05). IL-5 and IL-6 levels were significantly lower in the VitD group compared to the placebo group (P < 0.05). There were no significant intervention effects on serum IL-1β or IL-10 levels in either group (P > 0.05).

CONCLUSIONS

In younger postmenopausal women, isolated supplementation with 1000 IU of VitD3 for 9 months was associated with a reduction in proinflammatory biomarkers.

Obesity and cancer: the role of adipose tissue and adipo-cytokines-induced chronic inflammation

Adipose tissue in addition to its ability to keep lipids is now recognized as a real organ with both metabolic and endocrine functions. Recent studies demonstrated that in obese animals is established a status of adipocyte hypoxia and in this hypoxic state interaction between adipocytes and stromal vascular cells contribute to tumor development and progression. In several tumors such as breast, colon, liver and prostate, obesity represents a poor predictor of clinical outcomes. Dysfunctional adipose tissue in obesity releases a disturbed profile of adipokines with elevated levels of pro-inflammatory factors and a consequent alteration of key signaling mediators which may be an active local player in establishing the peritumoral environment promoting tumor growth and progression. Therefore, adipose tissue hypoxia might contribute to cancer risk in the obese population. To date the precise mechanisms behind this obesity-cancer link is not yet fully understood. In the light of information provided in this review that aims to identify the key mechanisms underlying the link between obesity and cancer we support that inflammatory state specific of obesity may be important in obesity-cancer link.

Assessment of oxidative stress and inflammation in prediabetes-A hospital based cross-sectional study

BACKGROUND AND AIM

Prediabetes is associated with dysglycemia, obesity, inflammation and endothelial dysfunction, contributing towards the pathogenesis of cardiovascular diseases rendering them vulnerable for the same. The current study intended to explore the risk of cardiovascular disease (CVD) related with prediabetes by assessing oxidative stress and inflammation using serum interleukin-6 (IL-6), myeloperoxidase (MPO) and urine microalbumin (MA) and their correlation with fasting plasma glucose (FPG) and physical measurements.

MATERIALS AND METHODS

Based on FPG values, 80 subjects were grouped into prediabetes and healthy controls. IL-6 and MPO were estimated in serum sample whereas MA was estimated in random urine sample.

RESULTS

Prediabetes group had significantly increased (p<0.05) mean anthropometric measurements and IL-6, MPO and MA as compared to healthy controls. MPO had significant correlation with FPG (r-0.388) in the prediabetes group. IL-6 and MPO showed a positive correlation with body mass index (BMI (r-0.339, r-0.327)), waist circumference (WC (r-484, r-0.493)) and waist-to-hip ratio (WHR (r-0.430, r-0.493)) while MA did not correlate with FPG and anthropometric measurements.

CONCLUSION

This study suggests that prediabetes is associated with central adiposity, inflammation and oxidative stress predisposing them to an increased risk for CVD.

Serum Leptin Levels and the Risk of Stroke: The Framingham Study

BACKGROUND AND PURPOSE

Leptin is a major adipokine that regulates weight balance and energy homeostasis. There is inconsistent evidence linking circulating leptin levels to risk of stroke. We tested the hypothesis that leptin levels are associated with risk of incident stroke in an elderly community based sample.

METHODS

Serum leptin levels were assayed in 757 stroke free individuals (mean age, 79 years; 62% women) from the Framingham Original Cohort at the 22nd examination cycle (1990-1994). Incidence of all -stroke and ischemic stroke were prospectively ascertained.

RESULTS

During a mean follow up of 10 years, 119 individuals developed stroke (99 ischemic strokes). In multivariable Cox regression models, log leptin levels were not associated with incidence of all -stroke or ischemic stroke (hazard ratios per SD increment in log leptin 0.90 [0.73-1.09] and 0.89 [0.72-1.11], respectively). The results were suggestive for potential effect modification by waist/hip ratio for the association between leptin and stroke (P=0.03). Adjusting for age, sex, and established stroke risk factors, analysis stratified by waist/hip ratio quartiles revealed a lower incidence of first-ever all-stroke and ischemic stroke associated with higher leptin levels among only subjects in the top waist/hip ratio quartile (hazard ratio, 0.64 [0.43, 0.95] versus 0.98 [0.77, 1.25] for incident all-stroke and 0.61 [0.39, 0.95] versus 0.96 [0.74, 1.26] for ischemic stroke).

CONCLUSIONS

Leptin levels were not directly related to the risk of incident stroke overall but there was an inverse association with stroke in the top waist/hip ratio quartile. Further investigations are required to confirm these findings and explore possible mechanisms for the observed association.

Association between IL-6 concentration and diabetes-related variables in DM1 patients with and without microvascular complications

Interleukin 6 (IL-6) plays an important role in the initiation and acceleration of chronic inflammation and could contribute to development of microvascular complications in patients with type 1 diabetes (DM1). Therefore, this study was aimed to investigate the association between concentration of IL-6 in relation to glucose control, lipid profile, and body mass index (BMI) in 69 DM1 patients subdivided according to the absence or presence of microvascular complications. BMI, level of fasting plasma glucose (FPG), and concentrations of total cholesterol (TCH), LDL cholesterol (LDL-C), and IL-6 were higher in DM1 patients compared to the control group. In DM1 patients, IL-6 concentration was positively correlated with level of FPG, LDL-C, TCH concentrations, and BMI. These correlations were stronger in the subgroup of patients with microvascular complications. In addition, BMI independently influences IL-6 concentration in DM1 patients. In conclusion, elevated IL-6 concentration is associated with diabetes-related variables which could accelerate progression of microvascular complications in DM1 patients.

Hemin therapy suppresses inflammation and retroperitoneal adipocyte hypertrophy to improve glucose metabolism in obese rats co-morbid with insulin-resistant type-2 diabetes

AIM

Visceral adiposity and impaired glucose metabolism are common patho-physiological features in patients co-morbid with obesity and type-2 diabetes. We investigated the effects of the heme-oxygenase (HO) inducer hemin and the HO blocker stannous-mesoporphyrin (SnMP) on glucose metabolism, adipocyte hypertrophy and pro-inflammatory cytokines/mediators in Zucker diabetic fatty (ZDF) rats, a model characterized by obesity and type-2 diabetes.

METHODS

Histological, morphological/morphometrical, Western immunoblotting, enzyme immunoassay, ELISA and spectrophotometric analysis were used.

RESULTS

Treatment with hemin enhanced HO-1, HO activity and cGMP, but suppressed retroperitoneal adiposity and abated the elevated levels of macrophage-chemoattractant protein-1 (MCP-1), ICAM-1, tumour necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), IL-1β, NF-κB, c-Jun-NH2-terminal-kinase (JNK) and activating-protein (AP-1), with parallel reduction of adipocyte hypertrophy. Correspondingly, important proteins of lipid metabolism and insulin-signalling such as lipoprotein lipase (LPL), insulin-receptor substrate-1 (IRS-1), GLUT4, PKB/Akt, adiponectin, the insulin-sensitizing and anti-inflammatory protein and adenosine-monophosphate-activated protein kinase (AMPK) were significantly enhanced in hemin-treated ZDF rats.

CONCLUSION

Elevated retroperitoneal adiposity and the high levels of MCP-1, ICAM-1, TNF-α, IL-6, IL-1β, NF-κB, JNK and AP-1 in untreated ZDF are patho-physiological factors that exacerbate inflammatory insults, aggravate adipocyte hypertrophy, with corresponding reduction of adiponectin and deregulation of insulin-signalling and lipid metabolism. Therefore, the suppression of MCP-1, ICAM-1, TNF-α, IL-6, IL-1β, NF-κB, JNK, AP-1 and adipocyte hypertrophy, with the associated enhancement of LPL, adiponectin, AMPK, IRS-1, GLUT4, PKB/Akt and cGMP in hemin-treated ZDF are among the multifaceted mechanisms by which the HO system combats inflammation to potentiate insulin signalling and improve glucose and lipid metabolism. Thus, HO inducers may be explored in the search of novel remedies against the co-morbidities of obesity, dysfunctional lipid metabolism and impaired glucose metabolism.

Involvement of leptin in the progression of experimentally induced peritoneal fibrosis in mice

Leptin is a hormone mainly produced by white adipose cells, and regulates body fat and food intake by acting on hypothalamus. Leptin receptor is expressed not only in the hypothalamus but in a variety of peripheral tissues, suggesting that leptin has pleiotropic functions. In this study, we investigated the effect of leptin on the progression of peritoneal fibrosis induced by intraperitoneal injection of chlorhexidine gluconate (CG) every other day for 2 or 3 weeks in mice. This study was conducted in male C57BL/6 mice and leptin-deficient ob/ob mice. Peritoneal fluid, blood, and peritoneal tissues were collected 15 or 22 days after CG injection. CG injection increased the level of leptin in serum and peritoneal fluid with thickening of submesothelial compact zone in wild type mice, but CG-injected ob/ob mice attenuate peritoneal fibrosis, and markedly reduced the number of myofibroblasts, infiltrating macrophages, and blood vessels in the thickened submesothelial area. The 2-week leptin administration induced a more thickened peritoneum in the CG-injected C57BL/6 mice than in the PBS group. Our results indicate that an upregulation of leptin appears to play a role in fibrosis and inflammation during peritoneal injury, and reducing leptin may be a therapeutically potential for peritoneal fibrosis.

Evidence for visfatin as an independent predictor of endothelial dysfunction in polycystic ovary syndrome

OBJECTIVE

Emerging evidence links adipocyte-secreted hormones, in particular adiponectin and visfatin, to cardiovascular pathology. Although adipocytokines dysregulation is common in polycystic ovary syndrome (PCOS) within the context of obesity and insulin resistance, their participation in the process of vascular injury remains elusive.

DESIGN AND METHODS

This prospective, case-control study enrolled 102 young women (69 patients with PCOS and 33 eumenorrheic age-matched controls); serum adiponectin, resistin and visfatin, testosterone, SHBG, lipids, glucose, insulin, the homeostasis model assessment of insulin resistance (HOMA-IR) and high-sensitivity C-reactive protein (hs-CRP) were simultaneously measured in all participants. Body composition analysis was performed using dual X-ray absorptiometry. Endothelium impairment was assessed by carotid artery intimae-media thickness (CIMT) and brachial artery flow-mediated vasodilatation (FMD), respectively.

RESULTS

In PCOS, both univariate and multivariate analyses evidenced that circulating visfatin was significantly related to free testosterone (P = 0·024) and brachial artery FMD (P = 0·008; P < 0·01 in multivariate analyses). By every visfatin tertile, a stepwise decrease in FMD was observed in all and PCOS only (P = 0·036), not confounded by age, body mass index, total body fat mass, testosterone, SHBG or HOMA-IR. Multiple regression analysis retained visfatin and free testosterone as independent predictors of FMD, explaining about 20% of FMD variability. Adiponectin correlated with CIMT and hs-CRP, but the association was driven by age, body mass and body fat. No relationship between resistin and endothelial markers was found.

CONCLUSION

Visfatin may be a candidate to play a role in the pathogenesis of endothelial dysfunction in PCOS, independently of additional risk factors.

Adipokines: biofactors from white adipose tissue. A complex hub among inflammation, metabolism, and immunity

Until the identification of leptin, the first adipokine discovered in 1994, adipose tissue was considered only as an energy storage tissue. However, it is now clear that adipose tissue is an endocrine/paracrine/autocrine organ, which plays a relevant role in physiopathology of several inflammatory diseases. Actually, it is mainly involved not only in the low-grade inflammatory status in obesity but also in other relevant inflammatory conditions and autoimmune disorders. In this review article, we discuss the main biological activities of leptin, adiponectin, lipocalin-2, resistin, and visfatin, as well as their contributions to certain inflammatory conditions.

Interferon-gamma induced adipose tissue inflammation is linked to endothelial dysfunction in type 2 diabetic mice

Interferon-gamma (IFNγ) has previously been associated with immuno-mediated inflammation in diet-induced obesity and type 1 diabetes. This study sought to define the role of IFNγ-induced adipose tissue inflammation in endothelial dysfunction in type 2 diabetes. We examined mesenteric adipose tissue (MAT) inflammation, and endothelial function of small mesenteric artery (SMA) in control mice (m Lepr(db)), diabetic mice (Lepr(db)), m Lepr(db) treated with IFNγ, and Lepr(db) treated with anti-IFNγ or anti-monocyte chemoattractant protein-1 (anti-MCP-1). mRNA and protein expression of IFNγ and MCP-1 were increased in MAT of Lepr(db), accompanied by increased T-lymphocyte and macrophage infiltration. Anti-IFNγ reduced MAT inflammatory cell infiltration and inflammatory cytokine expression in Lepr(db), while IFNγ treatment showed the opposite effects in m Lepr(db). Acetylcholine (ACh)-induced vasorelaxation of SMA was impaired in Lepr(db) versus m Lepr(db), but sodium nitroprusside (SNP)-induced vasorelaxation was comparable. Both anti-IFNγ and anti-MCP-1 improved endothelial function of Lepr(db), while IFNγ treatment impaired endothelial function of m Lepr(db). Superoxide production was higher in both MAT and SMA of Lepr(db) mice, and anti-IFNγ reduced MAT and SMA superoxide production. Macrophage accumulation in the adventitia of SMA, and mRNA expression of MCP-1 in SMA were increased in Lepr(db) and IFNγ-treated m Lepr(db), but reduced in anti-IFNγ treated Lepr(db). These findings suggest IFNγ has a key role in the regulation of visceral adipose tissue inflammatory response and endothelial dysfunction in type 2 diabetes.

Leptin and resistin induce increased procoagulability in diabetes mellitus

BACKGROUND

Patients with diabetes mellitus (DM) suffer from an increased risk of cardiovascular events caused by thrombotic conditions. Adipose tissue might play a crucial role in this pathogenesis by synthesis of procoagulant mediators. This study was performed to elucidate the role of the adipocytokines leptin and resistin in the development of hypercoagulability and hypofibrinolysis under diabetic conditions.

METHODS

Sixty two patients with or without DM were included in our study to measure leptin, resistin and tissue factor (TF) plasma concentrations. Moreover, flow chamber experiments were performed to assess factor Xa and plasmin activity on the surface of HUVECs. Western blot and real-time PCR were performed to determine mRNA and protein expression of main factors of the coagulation and fibrinolytic system.

RESULTS

Patients with diabetes showed increased levels of leptin and resistin (leptin: 25.69±13.9 vs. 15.98±17.5 ng/mL, p<0.05; resistin: 2.61±0.6 vs. 1.19±0.7 ng/mL, p<0.05), which were positively correlated with TF. In vitro, leptin and resistin induced increased factor Xa activity (leptin: 4.29±0.57-fold, p<0.05; resistin 4.19±0.7-fold, p<0.05 vs. control) on HUVECs as also reflected by elevated TF mRNA and protein expression. Moreover, stimulatory (plasminogen activator inhibitor 1) and inhibitory (tissue plasminogen activator) mediators of the fibrinolytic cascade were induced by leptin and resistin, leading to a balanced plasmin activity regulation.

CONCLUSIONS

Leptin and resistin lead to a procoagulant state in HUVECs by inducing TF expression. This mechanism might be one explanation for the prothrombotic state observed under diabetic conditions.

Early alterations in vascular contractility associated to changes in fatty acid composition and oxidative stress markers in perivascular adipose tissue

Aim

To test the early effect of fructose-induced changes in fatty acid composition and oxidative stress markers in perivascular adipose tissue (PVAT) upon vascular contractility.

Methods

Adult male Wistar rats were fed a commercial diet without (CD) or with 10% fructose (FRD) in the drinking water for 3 weeks. We measured plasma metabolic parameters, lipid composition and oxidative stress markers in aortic PVAT. Vascular contractility was measured in aortic rings sequentially, stimulated with serotonin (5-HT) and high K⁺-induced depolarization using intact and thereafter PVAT-deprived rings.

Results

Comparable body weights were recorded in both groups. FRD rats had increased plasma triglyceride and fructosamine levels. Their PVAT had an increased saturated to mono- or poly-unsaturated fatty acid ratio, a significant decrease in total superoxide dismutase and glutathione peroxidase activities and in the total content of glutathione. Conversely, lipid peroxidation (TBARS), nitric oxide content, and gluthathione reductase activity were significantly higher, indicating an increase in oxidative stress. In aortic rings, removal of PVAT increased serotonin-induced contractions, but the effect was significantly lower in rings from FRD rats. This effect was no longer observed when the two contractions were performed in PVAT-deprived rings. PVAT did not affect the contractions triggered by high K⁺-induced depolarization either in CD or FRD rats.

Conclusions

FRD induces multiple metabolic and endocrine systemic alterations which also alter PVAT and the vascular relaxant properties of this tissue. The changes in PVAT would affect its paracrine modulation of vascular function.

Peritoneal adipocytes and their role in inflammation during peritoneal dialysis

Adipose tissue is a major site of chronic inflammation associated with peritoneal dialysis (PD) frequently complicating peritonitis. Adiposity-associated inflammation plays a significant contributory role in the development of chronic inflammation in patients undergoing maintenance PD. However, the molecular and cellular mechanisms of this link remain uncertain. Adipose tissue synthesizes different adipokines and cytokines that orchestrate and regulate inflammation, insulin action, and glucose metabolism locally and systemically. In return, inflammation retards adipocyte differentiation and further exacerbates adipose dysfunction and inflammation. An understanding of the inflammatory roles played by adipose tissue during PD and the healing mechanism of injured mesothelium will help to devise new therapeutic approach to slow the progression of peritoneal damage during peritoneal dialysis. This article reviews the roles of peritoneal adipose tissue in chronic peritoneal inflammation under PD and in serosal repair during PD.

Gene expression changes in mononuclear cells in patients with metabolic syndrome after acute intake of phenol-rich virgin olive oil

Background

Previous studies have shown that acute intake of high-phenol virgin olive oil reduces pro-inflammatory, pro-oxidant and pro-thrombotic markers compared with low phenols virgin olive oil, but it still remains unclear whether effects attributed to its phenolic fraction are exerted at transcriptional level in vivo. To achieve this goal, we aimed at identifying expression changes in genes which could be mediated by virgin olive oil phenol compounds in the human.

Results

Postprandial gene expression microarray analysis was performed on peripheral blood mononuclear cells during postprandial period. Two virgin olive oil-based breakfasts with high (398 ppm) and low (70 ppm) content of phenolic compounds were administered to 20 patients suffering from metabolic syndrome following a double-blinded, randomized, crossover design. To eliminate the potential effect that might exist in their usual dietary habits, all subjects followed a similar low-fat, carbohydrate rich diet during the study period. Microarray analysis identified 98 differentially expressed genes (79 underexpressed and 19 overexpressed) when comparing the intake of phenol-rich olive oil with low-phenol olive oil. Many of these genes seem linked to obesity, dyslipemia and type 2 diabetes mellitus. Among these, several genes seem involved in inflammatory processes mediated by transcription factor NF-κB, activator protein-1 transcription factor complex AP-1, cytokines, mitogen-activated protein kinases MAPKs or arachidonic acid pathways.

Conclusion

This study shows that intake of virgin olive oil based breakfast, which is rich in phenol compounds is able to repress in vivo expression of several pro-inflammatory genes, thereby switching activity of peripheral blood mononuclear cells to a less deleterious inflammatory profile. These results provide at least a partial molecular basis for reduced risk of cardiovascular disease observed in Mediterranean countries, where virgin olive oil represents a main source of dietary fat. Admittedly, other lifestyle factors are also likely to contribute to lowered risk of cardiovascular disease in this region.

Increased expression and secretion of resistin in epicardial adipose tissue of patients with acute coronary syndrome

The purpose of this study was to test the hypothesis that specific epicardial adipose tissue (EAT) proinflammatory adipokines might be implicated in acute coronary syndrome (ACS). We compared expression and protein secretion of several EAT adipokines of male ACS with those of matched stable coronary artery disease (CAD) patients and controls with angiographically normal coronary arteries. The effect of supernatant of cultured EAT on endothelial cell permeability in vitro was also evaluated in the three study groups. EAT of ACS patients showed significantly higher gene expression and protein secretion of resistin than patients with stable CAD. Interleukin-6, plasminogen activator inhibitor-1, and monocyte chemoattractant protein-1 genes were also significantly overexpressed in ACS compared with the control group but not when compared with stable CAD. Immunofluorescence of EAT sections revealed a significantly greater number of CD68(+) cells in ACS patients than stable CAD and control groups. The permeability of endothelial cells in vitro was significantly increased after exposure to supernatant of cultured EAT from ACS, but not control or stable CAD groups, and this effect was normalized by anti-resistin antiserum. We found that EAT of patients with ACS is characterized by increased expression and secretion of resistin and associated with increased in vitro endothelial cell permeability.

Social stress, visceral obesity, and coronary artery atherosclerosis: product of a primate adaptation

Abdominal obesity is prevalent and often accompanied by an array of metabolic perturbations including elevated blood pressure, dyslipidemia, impaired glucose tolerance or insulin resistance, a prothrombotic state, and a proinflammatory state, together referred to as the metabolic syndrome. The metabolic syndrome greatly increases coronary heart disease (CHD) risk. Social stress also increases CHD although the mechanisms through which this occurs are not completely understood. Chronic stress may result in sustained glucocorticoid production, which is thought to promote visceral obesity. Thus, one hypothesis is that social stress may cause visceral fat deposition and the metabolic syndrome, which, in turn increases CHD. CHD is caused by coronary artery atherosclerosis (CAA) and its sequelae. Cynomolgus monkeys (Macaca fascicularis) are a well-established models of CAA. Social subordination may be stressful to cynomolgus monkeys and result in hypercortisolemia and exacerbated CAA in females. Herein is reviewed a body of literature which suggests that social stress increases visceral fat deposition in cynomolgus monkeys, that subordinate females are more likely than dominants to have visceral obesity, that females with visceral obesity have behavioral and physiological characteristics consistent with a stressed state, and that females with high ratios of visceral to subcutaneous abdominal fat develop more CAA. While these relationships have been most extensively studied in cynomolgus macaques, obesity-related metabolic disturbances are also observed in other primate species. Taken together, these observations support the view that the current obesity epidemic is the result of a primate adaptation involving the coevolution with encephalization of elaborate physiological systems to protect against starvation and defend stored body fat in order to feed a large and metabolically demanding brain. Social stress may be engaging these same physiological systems, increasing the visceral deposition of fat and its sequelae, which increase CHD risk.

Leptin, adiponectin, their ratio and risk of Coronary Heart Disease: results from the MONICA/KORA Augsburg Study 1984-2002

OBJECTIVE

Despite modulating a number of metabolic processes linked to atherosclerosis, including glucose regulation, hematopoiesis, fatty acid catabolism and angiogenesis, the potential association of adiponectin and leptin with coronary heart disease is still a matter of controversy.

METHODS

We conducted a population-based case-cohort study within the MONICA/KORA Augsburg studies. Serum levels of adipokines were measured in 333 case subjects with incident CHD and 1,728 non-case subjects selected from a source population of 9300 middle-aged men and women. Mean follow-up was 10.8+/-4.6 years. We sought to analyze the association of leptin and adiponectin and their ratio with CHD.

RESULTS

After adjustment for various confounding factors the hazard ratios and 95% confidence intervals comparing tertile extremes were 0.79 (0.53-1.17) for leptin (top vs bottom tertile) and 0.87 (0. 62-1.23) for adiponectin (bottom vs top tertile), respectively. Furthermore, the ratio of leptin/adiponectin also showed no association with CHD (HR 1.01 (0.68-1.51)).

CONCLUSIONS

The present study reports the association of leptin and adiponectin with incident CHD in a large population-based cohort. In contrast to fairly strong associations previously reported, our findings indicate no clinically relevant association between leptin, adiponectin and their ratio with the risk of CHD after adjustment for potential confounders.