Secretory products from human adipocytes impair endothelial function via nuclear factor kappaB

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.

Hyperoxaluria Induces Endothelial Dysfunction in Preglomerular Arteries: Involvement of Oxidative Stress

Urolithiasis is a worldwide problem and a risk factor for kidney injury. Oxidative stress-associated renal endothelial dysfunction secondary to urolithiasis could be a key pathogenic factor, similar to obesity and diabetes-related nephropathy. The aim of the present study was to characterize urolithiasis-related endothelial dysfunction in a hyperoxaluria rat model of renal lithiasis. Experimental approach: Endothelial dysfunction was assessed in preglomerular arteries isolated from control rats and in which 0.75% ethylene glycol was administered in drinking water. Renal interlobar arteries were mounted in microvascular myographs for functional studies; superoxide generation was measured by chemiluminescence and mRNA and protein expression by RT-PCR and immunofluorescence, respectively. Selective inhibitors were used to study the influence of the different ROS sources, xanthine oxidase, COX-2, Nox1, Nox2 and Nox4. Inflammatory vascular response was also studied by measuring the RNAm expression of NF-κB, MCP-1 and TNFα by RT-PCR. Results: Endothelium-dependent vasodilator responses were impaired in the preglomerular arteries of the hyperoxaluric group along with higher superoxide generation in the renal cortex and vascular inflammation developed by MCP-1 and promoted by NF-κB. The xanthine oxidase inhibitor allopurinol restored the endothelial relaxations and returned superoxide generation to basal values. Nox1 and Nox2 mRNA were up-regulated in arteries from the hyperoxaluric group, and Nox1 and Nox2 selective inhibitors also restored the impaired vasodilator responses and normalized NADPH oxidase-dependent higher superoxide values of renal cortex from the hyperoxaluric group. Conclusions: The current data support that hyperoxaluria induces oxidative stress-mediated endothelial dysfunction and inflammatory response in renal preglomerular arteries which is promoted by the xanthine oxidase, Nox1 and Nox2 pathways.

Astragaloside IV prevents high glucose‑induced cell apoptosis and inflammatory reactions through inhibition of the JNK pathway in human umbilical vein endothelial cells

Endothelial dysfunction is a key pathophysiological step in early stage diabetes mellitus (DM) macrovascular complications and is also crucial in the inflammatory mechanisms of macrovascular complications. However, there is currently no effective intervention to improve endothelial dysfunction associated with DM macrovascular complications. Astragaloside IV (AS-IV), which can be extracted from the traditional Chinese medicine Astragalus membranaceus, has potential therapeutic effects on DM and its complications. The present study evaluated the effect of AS-IV on high glucose-induced human umbilical vein endothelial cell (HUVEC) injury and its possible mechanism. The result indicated that AS-IV has a significant protective effect on high glucose-induced HUVEC injury. AS-IV could significantly promote cell proliferation, reduce apoptosis and decrease the protein and mRNA expression levels of tumor necrosis factor-α and interleukin-1β in HUVECs. Furthermore, AS-IV could decrease the expression of phosphorylated c-Jun NH₂-terminal kinase (JNK) phosphorylated apoptosis signal-regulating kinase 1, cytochrome c, cleaved-caspase-9, cleaved-caspase-3 and the relative ratio of B-cell lymphoma-2 associated X protein/B-cell lymphoma-2 in HUVECs. In conclusion, the present study demonstrated that AS-IV could suppress apoptosis and inflammatory reactions promoted by high glucose conditions in HUVECs by inhibiting the JNK signaling pathway. These findings suggest that AS-IV could inhibit the process of endothelial dysfunction in diabetic macrovascular complications.

The phosphodiesterase type 4 inhibitor roflumilast suppresses inflammation to improve diabetic bladder dysfunction rats

PURPOSE

To demonstrate that phosphodiesterase type 4 (PDE4) inhibitors could potentially treat diabetic bladder dysfunction (DBD) through modulation of the systemic inflammatory response.

METHODS

In this 6-week study, 60 female Sprague-Dawley rats were divided into three groups: (i) vehicle-treated control rats; (ii) vehicle-treated streptozocin (STZ)-injected rats; and (iii) roflumilast-treated STZ-injected rats. Oral roflumilast (5 mg/kg/day) was administered during the last 4 weeks of STZ injection to induce diabetes in the test group. At 6 weeks, a urodynamic study was performed in each group. The expression of nuclear factor kappa B (NF-κB), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and IL-1β in detrusor smooth muscle (DSM) was analyzed using quantitative reverse transcription-polymerase chain reaction and Western blotting.

RESULTS

A significant decrease in bodyweight and significant increases in bladder weight and blood glucose level were observed in the diabetic rats and were not ameliorated by roflumilast treatment. Cystometry showed the increased bladder capacity, voiding volume, residual urine volume, and voiding interval in the diabetic rats and the prevention of these changes by roflumilast. These changes were accompanied by significantly enhanced expression of NF-κB, TNF-α, IL-6, and IL-1β in DSM tissue from diabetic rats. Furthermore, roflumilast attenuated the expression of inflammatory factors in DSM tissue.

CONCLUSIONS

Oral treatment with roflumilast in diabetic rats improves bladder function and inhibits the expression of inflammatory factors in DSM tissue, indicating that PDE4 is a potential therapeutic target for DBD.

Hepatocyte steatosis increases the expression of adhesion molecules in endothelial cells

Background: Non-alcoholic fatty liver disease is considered a hepatic manifestation of the metabolic syndrome. It is associated with endothelial dysfunction as an early event of generalized atherosclerosis. However, it is unclear whether steatotic hepatocytes influence endothelial function directly. Objective: Explore the influence of hepatocyte steatosis on the function of endothelial cells. Methods: Oleic and palmitic acid (2:1 mixture, final concentration: 1 mM for 24 hours) was used to induce a normal adult hepatocyte strain (L-02) for transformation into steatosis cells. This was followed by oil red O staining and transmission electron microscopy (TEM) for verification. The culture solution of steatotic L-02 cells was filtered and collected, and added into the culture substrate of human umbilical vein endothelial cells (HUVECs). The expression of vascular cellular adhesion molecule -1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin in HUVECs was detected by real-time polymerase chain reaction and Western blot assays. The apoptosis and proliferation of HUVECs was determined using flow cytometry. The experimental results were compared with the controls. Results: Oil red O staining and microscopic observation showed that the cytoplasm of induced L-02 cells contained a large amount of red lipid droplets. TEM results showed that the cytoplasm had lipid accumulation, swelling mitochondria, fewer cristae, and reduced number of rough endoplasmic reticula accompanied with degranulation. However, these changes were not observed in normal L-02 cells. As to the group of HUVECs treated by the filtrate of steatosis L-02 cells, the mRNA and protein expression of VCAM-1, ICAM-1, and E-selectin was higher than that in the control group. The difference was statistically significant (p <0.01). No significant difference was found when HUVECs apoptosis and proliferation were assessed by flow cytometry. Conclusion: Secretion from steatotic hepatocytes could boost the expression of VCAM-1, ICAM-1, and E-selectin in endothelial cells, indicating that hepatocyte steatosis could induce endothelial cell dysfunction. The proliferation and apoptosis of endothelial cells did not change, suggesting that hepatocyte steatosis had no influence on the viability of endothelial cells under this condition.

Exposure to omentum adipose tissue conditioned medium from obese pregnant women promotes myometrial artery dysfunction

Aim

Underlying mechanisms of poor pregnancy outcome in obese (OB) mothers (body mass index [BMI] ≥ 30 kg/m²) are unknown. Our studies demonstrate that OB pregnant women have altered myometrial artery (MA) function related to the thromboxane and nitric oxide pathways. In obesity, increased central fat mass is associated with an altered endocrine milieu. We tested the hypothesis that in OB pregnant women the omentum, a central fat store, releases factors that promote dysfunction in normal MAs.

Methods

Myometrial and omental adipose tissue biopsies were obtained from women with uncomplicated term pregnancies. Omental adipose tissue explants from six normal weight (NW; BMI 18.5–24.9 kg/m²) and six OB (BMI ≥ 30 kg/m²) women were cultured and the conditioned medium collected and pooled to produce NW medium and OB medium. Adipokine concentrations were measured using enzyme‐linked immunosorbent assays. Wire myography was used to assess the effect of conditioned medium (NW or OB; N = 7) or leptin (100 nM; N = 5) exposure on MA responses to U46619 (thromboxane‐mimetic) and bradykinin (endothelial‐dependent vasodilator).

Results

OB medium had higher leptin and lower adiponectin levels than NW medium. U46619 and bradykinin concentration response curves shifted upwards in MAs exposed to OB medium but were unaffected by leptin.

Conclusions

Omental adipose tissue from OB pregnant women produced altered concentrations of adipokines. Acute OB medium exposure induced MA dysfunction, an effect not mirrored by exposure to leptin. These data suggest that an aberrant endocrine environment created by increased central adiposity in OB pregnant women induces vascular endothelial dysregulation, which may predispose them to a poor pregnancy outcome.

Atorvastatin antagonizes the visfatin-induced expression of inflammatory mediators via the upregulation of NF-κB activation in HCAECs

The present study investigated whether atorvastatin antagonizes the visfatin-induced expression of inflammatory mediators in human coronary artery endothelial cells (HCAECs). Several analysis methods, such as reverse transcription-quantitative polymerase chain reaction, western blot analysis and H₂DCFDA incubation, were used in the present study. The data showed that atorvastatin decreased the visfatin-induced expression of interleukin (IL)-6 and IL-8 in HCAECs. In addition, atorvastatin inhibited the visfatin-induced expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in HCAECs. In addition, the present study found that atorvastatin inhibited the visfatin-activated nuclear factor-κB (NF-κB) signal pathway by preventing extracellular signal-regulated kinase phosphorylation in HCAECs. Atorvastatin significantly inhibited visfatin-induced NF-κB activity via the upregulation of reactive oxygen species production. Atorvastatin, a visfatin antagonist (FK866) and an NF-κB inhibitor (BAY11-7082) decreased the visfatin-induced expression of inflammatory mediators via the upregulation of NF-κB activation in HCAECs. These results suggest that atorvastatin may inhibit the visfatin-induced upregulation of inflammatory mediators through blocking the NF-κB signal pathway. The findings of the present study provide a potential use for atorvastatin and visfatin in the pathogenesis of HCAEC dysfunction. This knowledge may contribute to the development of novel therapies for atherosclerosis.

Pathways commonly dysregulated in mouse and human obese adipose tissue: FAT/CD36 modulates differentiation and lipogenesis

Obesity is linked to adipose tissue hypertrophy (increased adipocyte cell size) and hyperplasia (increased cell number). Comparative analyses of gene datasets allowed us to identify 1426 genes which may represent common adipose phenotype in humans and mice. Among them we identified several adipocyte-specific genes dysregulated in obese adipose tissue, involved in either fatty acid storage (acyl CoA synthase ACSL1, hormone-sensitive lipase LIPE, aquaporin 7 AQP7, perilipin PLIN) or cell adhesion (fibronectin FN1, collagens COL1A1, COL1A3, metalloprotein MMP9, or both (scavenger receptor FAT/CD36). Using real-time analysis of cell surface occupancy on xCELLigence system we developed a new method to study lipid uptake and differentiation of mouse 3T3L1 fibroblasts and human adipose stem cells. Both processes are regulated by insulin and fatty acids such as oleic acid. We showed that fatty acid addition to culture media increased the differentiation rate and was required for full differentiation into unilocular adipocytes. Significant activation of lipogenesis, i.e. lipid accumulation, by either insulin or oleic acid was monitored in times ranging from 1 to 24 h, depending on differentiation state, whereas significant effects on adipogenesis, i.e., surperimposed lipid accumulation and gene transcriptional regulations were measured after 3 to 4 d. Combination of selected times for analysis of lipid contents, cell counts, size fractionations, and gene transcriptional regulations showed that FAT/CD36 specific inhibitor AP5258 significantly increased cell survival of oleic acid-treated mouse and human adipocytes, and partially restored the transcriptional response to oleic acid in the presence of insulin through JNK pathway. Taken together, these data open new perspectives to study the molecular mechanisms commonly dysregulated in mouse and human obesity at the level of lipogenesis linked to hypertrophy and adipogenesis linked to hyperplasia.

Relationship between toll-like receptor 4 levels in aorta and severity of atherosclerosis

OBJECTIVE

To investigate the relationship between levels of toll-like receptor 4 (TLR4) protein in aortic tissue and the severity of atherosclerosis in patients undergoing coronary artery bypass graft (CABG) surgery.

METHODS

Samples of ascending aorta and renal artery were collected from patients undergoing CABG surgery or kidney donation, respectively. TLR4 levels were determined by immunohistochemistry. Coronary angiography was performed to determine atherosclerosis severity via Gensini score.

RESULTS

TLR4 was present at high levels in aortic tissues from patients (n = 46), and was absent from renal artery tissue (controls; n = 11). There was a significant positive correlation between Gensini score and TLR4 level in the patient group.

CONCLUSIONS

TLR4 may play an important role in atherosclerosis and could be a potential therapeutic target for treatment of coronary artery disease. Discarded aortic tissue obtained during CABG surgery provides a new approach to the study of the pathogenesis of atherosclerosis.

Maternal obesity impairs specific regulatory pathways in human myometrial arteries

Obese women (body mass index ≥30 kg/m(2)) are at greater risk than normal weight women of pregnancy complications associated with maternal and infant morbidity, particularly the development of cardiovascular disease and metabolic disorders in later life; why this occurs is unknown. Nonpregnant, obese individuals exhibit systemic vascular endothelial dysfunction. We tested the hypothesis that obese pregnant women have altered myometrial arterial function compared to pregnant women of normal (18-24 kg/m(2)) and overweight (25-29 kg/m(2)) body mass index. Responses to vasoconstrictors, U46619 (thromboxane mimetic) and arginine vasopressin, and vasodilators, bradykinin and the nitric oxide donor sodium nitroprusside, were assessed by wire myography in myometrial arteries from normal weight (n = 18), overweight (n = 18), and obese (n = 20) women with uncomplicated pregnancies. Thromboxane-prostanoid receptor expression was assessed using immunostaining in myometrial arteries of normal weight and obese women. Vasoconstriction and vasodilatation were impaired in myometrial arteries from obese women with otherwise uncomplicated pregnancies. Disparate agonist responses suggest that vascular function in obese women is not globally dysregulated but may be specific to thromboxane and nitric oxide pathways. Because obesity rates are escalating, it is important to identify the mechanisms underlying impaired vascular function and establish why some obese women compensate for vascular dysfunction and some do not. Future studies are needed to determine whether central adiposity results in an altered endocrine milieu that may promote vascular dysfunction by altering the function of perivascular adipose tissue.

Endothelial cells from visceral adipose tissue disrupt adipocyte functions in a three-dimensional setting: partial rescue by angiopoietin-1

During obesity, chronic inflammation of human white adipose tissue (WAT) is associated with metabolic and vascular alterations. Endothelial cells from visceral WAT (VAT-ECs) exhibit a proinflammatory and senescent phenotype and could alter adipocyte functions. We aimed to determine the contribution of VAT-ECs to adipocyte dysfunction related to inflammation and to rescue these alterations by anti-inflammatory strategies. We developed an original three-dimensional setting allowing maintenance of unilocular adipocyte functions. Coculture experiments demonstrated that VAT-ECs provoked a decrease in the lipolytic activity, adipokine secretion, and insulin sensitivity of adipocytes from obese subjects, as well as an increased production of several inflammatory molecules. Interleukin (IL)-6 and IL-1β were identified as potential actors in these adipocyte alterations. The inflammatory burst was not observed in cocultured cells from lean subjects. Interestingly, pericytes, in functional interactions with ECs, exhibited a proinflammatory phenotype with diminished angiopoietin-1 (Ang-1) secretion in WAT from obese subjects. Using the anti-inflammatory Ang-1, we corrected some deleterious effects of WAT-ECs on adipocytes, improving lipolytic activity and insulin sensitivity and reducing the secretion of proinflammatory molecules. In conclusion, we identified a negative impact of VAT-ECs on adipocyte functions during human obesity. Therapeutic options targeting EC inflammation could prevent adipocyte alterations that contribute to obesity comorbidities.

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.

Resistin level in coronary artery disease and heart failure: the central role of kidney function

OBJECTIVES

The aim of this study was to evaluate resistin levels in patients with coronary artery disease (CAD) with or without chronic heart failure, in order to define its independent predictor.

METHODS

One hundred and seven outpatients with CAD were enrolled in the study and divided into three groups: CAD without left-ventricular systolic dysfunction (group 1); CAD with left-ventricular dysfunction without heart failure symptoms (group 2); CAD with overt heart failure (group 3). Plasma resistin was determined by ELISA.

RESULTS

Resistin progressively increased from group 1 (10.7±5.0 ng/ml) to groups 2 (11.8±5.8 ng/ml) and 3 (17.0±6.8 ng/ml), with the difference reaching statistical significance in group 3 versus groups 1 and 2 (P=0.001). A multivariable model of analysis demonstrated that the best predictor of plasma resistin level was the estimated glomerular filtration rate (P<0.001), indicating that reduction of kidney function was the main cause of the adipokine increase observed in patients with CAD and overt heart failure.

CONCLUSIONS

Our data confirm the rise of resistin plasma levels previously described in patients affected by chronic heart failure; however, in our study, this relationship seemed to be mediated mainly by the level of kidney function, and only partially by the severity of ventricular dysfunction.

Effects of lipoic acid on lipolysis in 3T3-L1 adipocytes

Lipoic acid (LA) is a naturally occurring compound with beneficial effects on obesity. The aim of this study was to evaluate its effects on lipolysis in 3T3-L1 adipocytes and the mechanisms involved. Our results revealed that LA induced a dose- and time-dependent lipolytic action, which was reversed by pretreatment with the c-Jun N-terminal kinase inhibitor SP600125, the PKA inhibitor H89, and the AMP-activated protein kinase activator AICAR. In contrast, the PI3K/Akt inhibitor LY294002 and the PDE3B antagonist cilostamide enhanced LA-induced lipolysis. LA treatment for 1 h did not modify total protein content of hormone-sensitive lipase (HSL) but significantly increased the phosphorylation of HSL at Ser(563) and at Ser(660), which was reversed by H89. LA treatment also induced a marked increase in PKA-mediated perilipin phosphorylation. LA did not significantly modify the protein levels of adipose triglyceride lipase or its activator comparative gene identification 58 (CGI-58) and inhibitor G(0)/G(1) switch gene 2 (G0S2). Furthermore, LA caused a significant inhibition of adipose-specific phospholipase A2 (AdPLA) protein and mRNA levels in parallel with a decrease in the amount of prostaglandin E(2) released and an increase in cAMP content. Together, these data suggest that the lipolytic actions of LA are mainly mediated by phosphorylation of HSL through cAMP-mediated activation of protein kinase A probably through the inhibition of AdPLA and prostaglandin E(2).

Endothelial dysfunction in cardiovascular and endocrine-metabolic diseases: an update

The endothelium plays a vital role in maintaining circulatory homeostasis by the release of relaxing and contracting factors. Any change in this balance may result in a process known as endothelial dysfunction that leads to impaired control of vascular tone and contributes to the pathogenesis of some cardiovascular and endocrine/metabolic diseases. Reduced endothelium-derived nitric oxide (NO) bioavailability and increased production of thromboxane A2, prostaglandin H2 and superoxide anion in conductance and resistance arteries are commonly associated with endothelial dysfunction in hypertensive, diabetic and obese animals, resulting in reduced endothelium-dependent vasodilatation and in increased vasoconstrictor responses. In addition, recent studies have demonstrated the role of enhanced overactivation of β-adrenergic receptors inducing vascular cytokine production and endothelial NO synthase (eNOS) uncoupling that seem to be the mechanisms underlying endothelial dysfunction in hypertension, heart failure and in endocrine-metabolic disorders. However, some adaptive mechanisms can occur in the initial stages of hypertension, such as increased NO production by eNOS. The present review focuses on the role of NO bioavailability, eNOS uncoupling, cyclooxygenase-derived products and pro-inflammatory factors on the endothelial dysfunction that occurs in hypertension, sympathetic hyperactivity, diabetes mellitus, and obesity. These are cardiovascular and endocrine-metabolic diseases of high incidence and mortality around the world, especially in developing countries and endothelial dysfunction contributes to triggering, maintenance and worsening of these pathological situations.

Translational evidence of endothelial damage in obese individuals: inflammatory and prothrombotic responses

BACKGROUND

 Obesity is associated with an increased atherothrombotic morbidity/mortality risk. However, there is no direct evidence of subclinical activation of the endothelium in obese subjects without other major cardiometabolic risk factors.

OBJECTIVES

 We applied a translational approach to investigate endothelial activation occurring in response to the components secreted by visceral and subcutaneous adipose tissue and their corresponding cell fractions obtained from obese subjects without other major cardiometabolic risk factors, as compared with non-obese controls.

METHODS

 Fat pads and cell fractions were incubated with serum-free medium to obtain their secretomes, which were analyzed by protein arrays. Endothelial cells (ECs) were exposed to the different secretomes to evaluate changes in gene expression, composition and reactivity of the extracellular matrix (ECM), and cell growth and viability.

RESULTS

 ECs incubated in the presence of obese secretomes displayed increased proliferation, altered cell morphology, augmented expression of VCAM-1, ICAM-1, and von Willebrand factor, and higher ECM reactivity towards circulating platelets. The visceral secretomes, especially the stromal one, induced the strongest expression of these markers, together with a more reactive ECM. These changes occurred through nuclear factor-κB (NF-κB) activation.

CONCLUSION

 This is the first translational study demonstrating that the cytokines secreted by the adipose tissue from obese individuals without other major cardiometabolic complications have a hazardous effect on the endothelium, through activation of the NF-κB pathway.

Cardiovascular dysfunction in obesity and new diagnostic imaging techniques: the role of noninvasive image methods

Obesity is a major public health problem affecting adults and children in both developed and developing countries. This condition often leads to metabolic syndrome, which increases the risk of cardiovascular disease. A large number of studies have been carried out to understand the pathogenesis of cardiovascular dysfunction in obese patients. Endothelial dysfunction plays a key role in the progression of atherosclerosis and the development of coronary artery disease, hypertension and congestive heart failure. Noninvasive methods in the field of cardiovascular imaging, such as measuring intima-media thickness, flow-mediated dilatation, tissue Doppler, and strain, and strain rate, constitute new tools for the early detection of cardiac and vascular dysfunction. These techniques will certainly enable a better evaluation of initial cardiovascular injury and allow the correct, timely management of obese patients. The present review summarizes the main aspects of cardiovascular dysfunction in obesity and discusses the application of recent noninvasive imaging methods for the early detection of cardiovascular alterations.

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

Hyperplasia and hypertrophy of fat cells can be found in obesity and increased adiposity is associated with endothelial dysfunction as an early event of atherosclerosis. However, it is unclear whether human adipocytes directly influence endothelial protein secretion. To study the crosstalk between fat and endothelial cells, human umbilical venous endothelial cells (HUVECs) were cultured in infranatants (Adipo) of primary differentiated human adipocytes. Interestingly, significantly increased secretion of 23 cytokines and chemokines from HUVECs was detected in four independent experiments after Adipo stimulation by protein array analysis detecting a total of 174 different proteins. Among those, time-dependent Adipo-induced upregulation of cytokine secretion in HUVECs was confirmed by ELISA for interleukin (IL)-8, monokine induced by gamma interferon, macrophage inflammatory protein (MIP)-1beta, MIP-3alpha, monocyte chemoattractant protein-1, and IL-6. Factors besides adiponectin, leptin, resistin, and tumor necrosis factor alpha appear to mediate these stimulatory effects. Our findings suggest that endothelial cell secretion is significantly influenced towards a proinflammatory pattern by adipocyte-secreted factors.

Nuclear factor-{kappa}B activation contributes to vascular endothelial dysfunction via oxidative stress in overweight/obese middle-aged and older humans

BACKGROUND

We tested the hypothesis that nuclear factor-kappaB (NF-kappaB) activity contributes to vascular endothelial dysfunction with aging and obesity in humans.

METHODS AND RESULTS

We conducted a randomized, double-blind, placebo-controlled crossover study in 14 nondiabetic overweight or obese (body mass index > or =25 kg/m(2)) middle-aged and older (age 52 to 68 years) adults. Salsalate (nonacetylated salicylate, 4500 mg/d), a compound that inhibits NF-kappaB activity, or placebo was administered for 4-day periods. Plasma salicylate concentrations reached the midtherapeutic range (21.8+/-1.1 mg/100 mL, P< or =0.0001 versus placebo) by day 4 of salsalate treatment. Salsalate increased expression of the inhibitor of NF-kappaB and reduced total and nuclear expression of NF-kappaB in endothelial cells obtained from the subjects (all P<0.05). Salsalate increased brachial artery flow-mediated dilation by 74% (from 4.0+/-0.4% to 6.6+/-0.5%, P<0.001) but did not affect endothelium-independent dilation (P=0.83). The change in brachial artery flow-mediated dilation with salsalate was inversely related to baseline flow-mediated dilation (r=-0.77, P<0.01). Infusion of vitamin C increased brachial artery flow-mediated dilation during placebo (P<0.001) but not after salsalate (P=0.23). Salsalate reduced nitrotyrosine (P=0.06) and expression of NADPH oxidase p47(phox) (P<0.05) in endothelial cells obtained from the subjects but did not influence circulating or endothelial cell inflammatory proteins.

CONCLUSIONS

Our findings provide the first direct evidence that NF-kappaB, in part via stimulation of oxidative stress, plays an important role in mediating vascular endothelial dysfunction in overweight and obese middle-aged and older humans.

Visfatin enhances ICAM-1 and VCAM-1 expression through ROS-dependent NF-kappaB activation in endothelial cells

Visfatin has recently been identified as a novel visceral adipokine which may be involved in obesity-related vascular disorders. However, it is not known whether visfatin directly contributes to endothelial dysfunction. Here, we investigated the effect of visfatin on vascular inflammation, a key step in a variety of vascular diseases. Visfatin induced leukocyte adhesion to endothelial cells and the aortic endothelium by induction of the cell adhesion molecules, ICAM-1 and VCAM-1. Promoter analysis revealed that visfatin-mediated induction of CAMs is mainly regulated by nuclear factor-kappaB (NF-kappaB). Visfatin stimulated IkappaBalpha phosphorylation, nuclear translocation of the p65 subunit of NF-kappaB, and NF-kappaB DNA binding activity in HMECs. Furthermore, visfatin increased ROS generation, and visfatin-induced CAMs expression and NF-kappaB activation were abrogated in the presence of the direct scavenger of ROS. Taken together, our results demonstrate that visfatin is a vascular inflammatory molecule that increases expression of the inflammatory CAMs, ICAM-1 and VCAM-1, through ROS-dependent NF-kappaB activation in endothelial cells.