Leptin induces vascular permeability and synergistically stimulates angiogenesis with FGF-2 and VEGF

Adipocytokines and CD34 progenitor cells in Alzheimer's disease

Background

Alzheimer's disease (AD) and atherosclerosis share common vascular risk factors such as arterial hypertension and hypercholesterolemia. Adipocytokines and CD34⁺ progenitor cells are associated with the progression and prognosis of atherosclerotic diseases. Their role in AD is not adequately elucidated.

Methods and Findings

In the present study, we measured in 41 patients with early AD and 37 age- and weight-matched healthy controls blood concentrations of adiponectin and leptin by enzyme linked immunoabsorbent assay and of CD34⁺ progenitor cells using flow cytometry. We found significantly lower plasma levels of leptin in AD patients compared with the controls, whereas plasma levels of adiponectin did not show any significant differences (AD vs. control (mean±SD): leptin:8.9±5.6 ng/mL vs.16.3±15.5 ng/mL;P = 0.038; adiponectin:18.5±18.1 µg/mL vs.16.7±8.9 µg/mL;P = 0.641). In contrast, circulating CD34⁺ cells were significantly upregulated in AD patients (mean absolute cell count±SD:253±51 vs. 203±37; P = 0.02) and showed an inverse correlation with plasma levels of leptin (r = −0.248; P = 0.037).

In logistic regression analysis, decreased leptin concentration (P = 0.021) and increased number of CD34⁺ cells (P = 0.036) were both significantly associated with the presence of AD. According to multifactorial analysis of covariance, leptin serum levels were a significant independent predictor for the number of CD34⁺ cells (P = 0.002).

Conclusions

Our findings suggest that low plasma levels of leptin and increased numbers of CD34⁺ progenitor cells are both associated with AD. In addition, the results of our study provide first evidence that increased leptin plasma levels are associated with a reduced number of CD34⁺ progenitor cells in AD patients. These findings point towards a combined involvement of leptin and CD34⁺ progenitor cells in the pathogenesis of AD. Thus, plasma levels of leptin and circulating CD34⁺ progenitor cells could represent an important molecular link between atherosclerotic diseases and AD. Further studies should clarify the pathophysiological role of both adipocytokines and progenitor cells in AD and possible diagnostic and therapeutic applications.

Vascular endothelial growth factor receptor-2 couples cyclo-oxygenase-2 with pro-angiogenic actions of leptin on human endothelial cells

Background

The adipocyte-derived hormone leptin influences the behaviour of a wide range of cell types and is now recognised as a pro-angiogenic and pro-inflammatory factor. In the vasculature, these effects are mediated in part through its direct leptin receptor (ObRb)-driven actions on endothelial cells (ECs) but the mechanisms responsible for these activities have not been established. In this study we sought to more fully define the molecular links between inflammatory and angiogenic responses of leptin-stimulated human ECs.

Methodology/Principal Findings

Immunoblotting studies showed that leptin increased cyclo-oxygenase-2 (COX-2) expression (but not COX-1) in cultured human umbilical vein ECs (HUVEC) through pathways that depend upon activation of both p38 mitogen-activated protein kinase (p38^MAPK) and Akt, and stimulated rapid phosphorylation of vascular endothelial growth factor receptor 2 (VEGFR2) on Tyr¹¹⁷⁵. Phosphorylation of VEGFR2, p38^MAPK and Akt, and COX-2 induction in cells challenged with leptin were blocked by a specific leptin peptide receptor antagonist. Pharmacological inhibitors of COX-2, the phosphatidylinositol 3-kinase (PI3K)/Akt pathway and p38^MAPK abrogated leptin-induced EC proliferation (assessed by quantifying 5-bromo-2′-deoxyuridine incorporation, calcein fluorescence and propidium iodide staining), slowed the increased migration rate of leptin-stimulated cells (in vitro wound healing assay) and inhibited leptin-induced capillary-like tube formation by HUVEC on Matrigel. Inhibition of VEGFR2 tyrosine kinase activity reduced leptin-stimulated p38^MAPK and Akt activation, COX-2 induction, and pro-angiogenic EC responses, and blockade of VEGFR2 or COX-2 activities abolished leptin-driven neo-angiogenesis in a chick chorioallantoic membrane vascularisation assay in vivo.

Conclusions/Significance

We conclude that a functional endothelial p38^MAPK/Akt/COX-2 signalling axis is required for leptin's pro-angiogenic actions and that this is regulated upstream by ObRb-dependent activation of VEGFR2. These studies identify a new function for VEGFR2 as a mediator of leptin-stimulated COX-2 expression and angiogenesis and have implications for understanding leptin's regulation of the vasculature in both non-obese and obese individuals.

Metabolic syndrome and mammographic density: the Study of Women's Health Across the Nation

The metabolic syndrome (MetS) is associated with an increase in breast cancer risk. In our study, we evaluated whether the MetS was associated with an increase in percent mammographic density (MD), a breast cancer risk factor. We used linear regression and mixed models to examine the cross-sectional and longitudinal associations of the MetS and components of the MetS to percent MD in 790 premenopausal and early perimenopausal women enrolled in the Study of Women's Health Across the Nation (SWAN). In cross-sectional analyses adjusted for body mass index (BMI), modest inverse associations were observed between percent MD and the MetS [β = -2.5, standard error (SE) = 1.9, p = 0.19], abdominal adiposity (β = -4.8, SE = 1.9, p = 0.01) and raised glucose (β = -3.7, SE = 2.4, p = 0.12). In longitudinal models adjusted for covariates including age and BMI, abdominal adiposity (β = 0.34, SE = 0.17, p = 0.05) was significantly positively associated with slower annual decline in percent MD with time. In conclusion, our results do not support the hypothesis that the MetS increases breast cancer risk via a mechanism reflected by an increase in percent MD.

Growth arrest-specific protein 6 receptor antagonism impairs adipocyte differentiation and adipose tissue development in mice

A low-molecular-weight receptor tyrosine kinase inhibitor, 1-(6,7-dihydro-5H-benzo(6,7)cyclohepta(1,2-c)pyridazin-3-yl)-N3-((7-pyrrolidin-1-yl)-6,7,8,9-tetrahydro-5H-benzo(7)annulene-2-yl)-1H-1,2,4-triazole-3,5-diamine (R428) with high affinity and selectivity for the growth arrest-specific protein 6 (GAS6) receptor Axl was used to study a potential role of GAS6 signaling in adiposity. In vitro, R428 caused a concentration-dependent inhibition of preadipocyte differentiation into mature adipocytes, as evidenced by reduced lipid uptake. Inhibition of Axl-mediated signaling was confirmed by reduced levels of phospho-Akt activity. In vivo, oral administration of R428 for 5 weeks to mice kept on a high-fat diet resulted in significantly reduced weight gain and subcutaneous and gonadal fat mass. This was associated with marked adipocyte hypotrophy, enhanced macrophage infiltration, and apoptosis. Thus, affecting GAS6 signaling through receptor antagonism using a low-molecular-weight Axl antagonist impairs adipocyte differentiation and reduces adipose tissue development in a murine model of nutritionally induced obesity.

Leptin pro-angiogenic signature in breast cancer is linked to IL-1 signalling

BACKGROUND

Leptin and interleukin-1 (IL-1) upregulate vascular endothelial growth factor (VEGF), promote angiogenesis and are related to worse prognosis of breast cancer. However, it is unknown whether leptin regulates IL-1, and whether these effects are related to leptin-induction of VEGF/VEGFR2 in breast cancer.

METHODS

Several genetic and pharmacological approaches were used to determine the mechanisms involved in leptin regulation of IL-1 system (IL-1α, IL-1β, IL-1Ra and IL-1R tI) and the impact of IL-1 signalling on leptin-induced VEGF/VEGFR2 expression in mouse mammary cancer 4T1 cells (a model that resembles invasive and highly metastatic human breast cancer).

RESULTS

Leptin increased protein and mRNA levels of all components of the IL-1 system. IL-1 upregulation involved leptin activation of JAK2/STAT3, MAPK/ERK 1/2, PI-3K/AKT1, PKC, p38 and JNK. Leptin-induced phosphorylation of mTOR/4E-BP1 increased IL-1β and IL-1Ra expression, but downregulated IL-1α. Leptin upregulation of IL-1α promoter was linked to SP1 and NF-κB transcription factors. In addition, leptin receptor (Ob-Rb) was upregulated by leptin. Interestingly, leptin upregulation of VEGF/VEGFR2 was partially mediated by IL-1/IL-1R tI signalling.

CONCLUSIONS

We show for the first time that leptin induces several signalling pathways to upregulate the translational and transcriptional expression of IL-1 system in breast cancer cells. Moreover, leptin upregulation of VEGF/VEGFR2 was impaired by IL-1 signalling blockade. These data suggest that leptin pro-angiogenic signature in breast cancer is linked to, or regulated, in part by IL-1 signalling.

Matrix metalloproteinase inhibition impairs murine adipose tissue development independently of leptin

Administration of Tolylsam, a MMP inhibitor with relative specificity for gelatinases, at a dose of 100 mg/kg/day to leptin-deficient (ob/ob) mice kept on high fat diet for 15 weeks, was associated with significantly reduced weight gain as compared to controls (p < 0.0005), resulting in lower body weight (p < 0.0005) at the end of the experiments. Food intake, physical activity and body temperature were not affected. Subcutaneous (SC) (2.9 ± 0.1g vs. 3.4 ± 0.2g in controls; p < 0.05) and gonadal (GON) (3.4 ± 0.1g vs. 3.7 ± 0.1g in controls; p = NS) fat mass were reduced by Tolylsam treatment. Reduced MMP-2 (gelatinase A) activity in adipose tissue extracts was confirmed by zymography. Mild adipocyte hypotrophy was observed in treated SC and GON adipose tissues. Blood vessel density was significantly reduced in Tolylsam treated SC (p < 0.05) and GON (p < 0.005) adipose tissues. Sirius red staining revealed comparable collagen content in both SC and GON fat of treated mice, whereas collagen disorganization (ratio thick/thin fibers) was also similar. Thus, gelatinase inhibition in mice with leptin deficiency resulted in lower body and fat pad weights, associated with mild adipocyte hypotrophy. This indicates that MMP inhibition may impair adipose tissue development independently of leptin.

Fumagillin reduces adipose tissue formation in murine models of nutritionally induced obesity

The effect of fumagillin (a methionine aminopeptidase-type 2 (Met-AP2) inhibitor, with antiangiogenic properties) was investigated in murine models of diet-induced obesity. Eleven-week-old male C57Bl/6 mice (group 1) were given fumagillin by oral gavage at a dose of 1 mg/kg/day during 4 weeks while fed a high-fat diet (HFD) (20.1 kJ/g), and control mice (group 2) received solvent and were pair-fed. At the end of the experiment, body weights in group 1 were significantly lower as compared to group 2 (P < 0.0005). The subcutaneous (SC) and gonadal (GON) fat mass was also significantly lower in group 1 (P < 0.005 and P < 0.05, respectively). Adipocytes were smaller in adipose tissues of mice in group 1, associated with higher adipocyte density. Blood vessel density normalized to adipocyte density was lower in group 1 adipose tissues. However, in mice with established obesity monitored to maintain the same body weight and fat mass as controls, short-term fumagillin administration was also associated with adipocyte hypotrophy (P = 0.01) without affecting blood vessel size or density. Thus, treatment with fumagillin impaired diet-induced obesity in mice, associated with adipocyte hypotrophy but without marked effect on adipose tissue angiogenesis.

The role of leptin in the respiratory system: an overview

Since its cloning in 1994, leptin has emerged in the literature as a pleiotropic hormone whose actions extend from immune system homeostasis to reproduction and angiogenesis. Recent investigations have identified the lung as a leptin responsive and producing organ, while extensive research has been published concerning the role of leptin in the respiratory system. Animal studies have provided evidence indicating that leptin is a stimulant of ventilation, whereas researchers have proposed an important role for leptin in lung maturation and development. Studies further suggest a significant impact of leptin on specific respiratory diseases, including obstructive sleep apnoea-hypopnoea syndrome, asthma, COPD and lung cancer. However, as new investigations are under way, the picture is becoming more complex. The scope of this review is to decode the existing data concerning the actions of leptin in the lung and provide a detailed description of leptin's involvement in the most common disorders of the respiratory system.

Effects of dietary fat on spontaneous metastasis of Lewis lung carcinoma in mice

The present study assessed the effects of dietary fat on spontaneous metastasis of Lewis lung carcinoma in mice. Three-week old male C57BL/6 mice were fed the AIN-93G diet or a 45% fat diet (% kcal.) for 7 weeks before they were subcutaneously injected with 2.5 × 10⁵ viable carcinoma cells. The primary tumor was resected 2 weeks later, and mice were maintained on their respective diets for an additional 2 weeks. The high-fat diet significantly increased body weight and abdominal adipose weight compared to the AIN-93G diet. Feeding mice the 45% fat diet resulted in a two-fold increase in the number of lung metastases (P < 0.05), a 35% increase in tumor cross-sectional area, and a 50% increase in tumor volume compared to mice fed the AIN-93G diet. There were no differences in plasma concentrations of TIMP-1, IL-1β, VEGF and MCP-1 in non-tumor-bearing mice fed the AIN-93G diet or the high-fat diet, but significant increases in these cytokines in tumor-bearing mice fed the AIN-93G diet compared to the non-tumor-bearing mice fed the same diet (P < 0.05 for each comparison). Further significant increases in these cytokines in tumor-bearing mice fed the 45% fat diet compared to the same tumor-bearing mice fed the AIN-93G diet (P < 0.05 for each comparison). The high-fat diet significantly increased plasma leptin and significantly decreased plasma adiponectin compared to the AIN-93G diet in both non-tumor-bearing and tumor-bearing mice. Results of the present study demonstrated that the high-fat diet enhanced spontaneous metastasis of Lewis lung carcinoma in mice and that this aggressiveness was accompanied with significant increases in plasma concentrations of angiogenic cytokines, suggesting that dietary fat affects metastasis by promoting angiogenic processes.

Microvascular responses to cardiovascular risk factors

Hypertension, hypercholesterolemia, diabetes, and obesity are among a growing list of conditions that have been designated as major risk factors for cardiovascular disease (CVD). While CVD risk factors are well known to enhance the development of atherosclerotic lesions in large arteries, there is also evidence that the structure and function of microscopic blood vessels can be profoundly altered by these conditions. The diverse responses of the microvasculature to CVD risk factors include oxidative stress, enhanced leukocyte- and platelet-endothelial cell adhesion, impaired endothelial barrier function, altered capillary proliferation, enhanced thrombosis, and vasomotor dysfunction. Emerging evidence indicates that a low-grade systemic inflammatory response that results from risk factor-induced cell activation and cell-cell interactions may underlie the phenotypic changes induced by risk factor exposure. A consequence of the altered microvascular phenotype and systemic inflammatory response is an enhanced vulnerability of tissues to the deleterious effects of secondary oxidative and inflammatory stresses, such as ischemia and reperfusion. Future efforts to develop therapies that prevent the harmful effects of risk factor-induced inflammation should focus on the microcirculation.

Obesity promotes melanoma tumor growth: role of leptin

Epidemiological studies suggest that obesity increases the risk of developing several cancers, including melanoma. Obesity increases the expression of angiogenic factors, such as leptin, that may contribute to tumor growth. However, a direct cause and effect relationship between obesity and tumor growth has not been clearly established and the role of leptin in accelerating tumor growth is unclear. Our objective in the present study was to examine the rate of melanoma tumor growth in lean and obese mice with leptin deficiency or high levels of plasma leptin. We injected 1 x 10(6) B16F10 melanoma cells subcutaneously into lean wild type (WT), obese melanocortin receptor 4 knockout (MC4R(-/-)), which have high leptin levels, obese leptin-deficient (ob(-/-)), pair fed lean ob(-/-), and lean ob(+/-) mice. Mean body weights were 29.7 +/- 0.3 g (WT), 46.3 +/- 1.9 g (MC4R(-/-)), 63.7 +/- 0.9 g (ob(-/-)), 30.5 +/- 1.0 g (pair fed ob(-/-)) and 31.6 +/- 1.7 g (ob(+/-)). Tumors were much larger in the obese leptin deficient ob(-/-) (5.1 +/- 0.9 g) and obese MC4R(-/-) (5.1 +/- 0.7 g) than in lean WT (1.9 +/- 0.3 g) and ob(+/-) (2.8 +/- 0.7 g) mice. Prevention of obesity by pair feeding ob(-/-) mice dramatically reduced tumor weight (0.95 +/- 0.2 g) to a level that was significantly lower than in WT mice of the same weight. Tumor VEGF levels were the highest in the obese mouse tumors (p < 0.05), regardless of the host leptin levels. Except for the lean ob(+/-), MC4R(-/-) and ob(-/-) melanomas had the highest VEGF receptor 1 and VEGF receptor 2 protein expression (p < 0.01 and p < 0.05), respectively. These results indicate that obesity markedly increases melanoma tumor growth rate by mechanisms that may involve upregulation of VEGF pathways. Although tumor growth does not require host leptin, melanoma tumor growth may be accelerated by leptin.

Cellulite: nature and aetiopathogenesis

Only a limited number of studies on cellulite have been published in the international literature and many of them reach somewhat antithetical conclusions. Consequently, it is not yet possible to reconcile the extreme differences of opinion which have lingered on for years concerning the nature of this disorder, as well as its origin and even the most basic aspects of its histopathological classification. It does not even have a recognized name: in fact, the term 'cellulitis' is used in scientific English to indicate a spreading gangrenous infection of the subcutaneous cellular tissue. The other terms used from time to time [panniculitis, lipodystrophy, edematofibrosclerotic panniculitis (EFP), liposclerosis, lipoedema, etc.] have quite different morphological and pathogenetic connotations in general. Over the last few decades, three major conflicting theories have emerged in relation to the ethiopathogenesis of cellulite. These indicate, respectively, the following causes: 1. Oedema caused by excessive hydrophilia of the intercellular matrix. 2. A homeostatic alteration on a regional microcirculatory level; this pathogenetic theory is summarized in a synthetic and self-explanatory denomination: EFP. 3. A peculiar anatomical conformation of the subcutaneous tissue of women, different from male morphology. These theories must all now be updated in the light of recent advances on the sophisticated and composite physiopathology of the adipose organ - which acts not only as a control device which regulates the systematic equilibrium of energy and modulates the food intake and the metabolism of other tissue substrate through a multiple glandular secretion of hormones and parahormones.

Tenomodulin gene and obesity-related phenotypes

Different cells of adipose tissue secrete compounds which regulate various biological processes. Changes in body weight, body composition, and amount of fat mass can alter the secretory profile and function of adipose tissue. Comparison of adipose tissue mRNA expression profiles before versus after weight loss or between obese and lean subjects has promoted the identification of novel adipokines. Weight loss decreases the expression of the tenomodulin (TNMD) mRNA in the adipose tissue, and the expression level is strongly correlated with body mass index. TNMD (locus Xq22) is expressed in both adipocyte and stromal vascular fraction of adipose tissue. Tenomodulin inhibits angiogenesis, but its specific function in adipose tissue is still unknown. We have reported modest association between TNMD sequence variation and different obesity-related phenotypes, including anthropometric measurements, inflammation, glucose and lipid metabolism, and age-related macular degeneration. In this review, the potential mechanisms that could link TNMD with the pathogenesis of obesity and related disorders are discussed.

Psoriasis and systemic inflammatory diseases: potential mechanistic links between skin disease and co-morbid conditions

Psoriasis is now classified as an immune-mediated inflammatory disease (IMID) of the skin. It is being recognized that patients with various IMIDs, including psoriasis, are at higher risk of developing "systemic" co-morbidities, e.g., cardiovascular disease (CVD), metabolic syndrome, and overt diabetes. In non-psoriatic individuals, the pathophysiology of obesity, aberrant adipocyte metabolism, diabetes, and CVDs involves immune-mediated or inflammatory pathways. IMIDs may impact these co-morbid conditions through shared genetic risks, common environmental factors, or common inflammatory pathways that are co-expressed in IMIDs and target organs. Given that pathogenic immune pathways in psoriasis are now well worked out and a large number of inflammatory mediators have been identified in skin lesions, in this review we will consider possible mechanistic links between skin inflammation and increased risks of (1) obesity or metabolic alterations and (2) CVD. In particular, we will discuss how well-established risk factors for CVD can originate from inflammation in other tissues.

Effect of preoperative single-dose corticosteroid administration on postoperative morbidity following esophagectomy

BACKGROUND

Eight clinical trials involving the administration of preoperative i.v. methylprednisolone have been undertaken in order to decrease the considerable inflammatory response to esophageal resection, in an effort to decrease the supposedly associated morbidity and mortality

METHOD

A meta-analysis was performed for eight clinical end-points. Due to quality problems in seven of the eight included studies, a Bayesian meta-analysis using a skeptical prior derived from the results of the classical analysis was also performed.

RESULTS

The end-points including any organ dysfunction (OR = 0.30), respiratory complication (OR = 0.41), sepsis (OR = 0.37), liver dysfunction (OR = 18), cardiovascular dysfunction (OR = 0.28), and surgical anastomotic leak (OR = 0.42) were significantly decreased by methylprednisolone pretreatment. Following the Bayesian analysis, despite the use of skeptical priors, there is a 95% probability to obtain a relative risk reduction of at least 23% to 54%, depending of the end-point, by methylprednisolone pretreatment.

CONCLUSION

We are in the presence of a potential benefit that cannot be accepted at face value due to the quality problems of the included studies. But in the presence of a remaining potential benefit after a Bayesian analysis starting from a skeptical prior, the best option would be the planning of a large multicenter prospective randomized study.

Angiogenesis and development of adipose tissue

Obesity is a common disorder and related diseases, such as diabetes, atherosclerosis, hypertension, cardiovascular disease and cancer, are a major cause of mortality and morbidity in Western-type societies. Development of obesity is associated with substantial modulation of adipose tissue structure. The plasticity of the adipose tissue is reflected by its remarkable ability to expand or to reduce in size throughout adult lifespan. The expansion of adipose tissue is linked to the development of its vasculature. Indeed, adipogenesis is tightly associated with angiogenesis, as shown by the findings that adipose tissue explants trigger blood vessel formation, whereas in turn adipose tissue endothelial cells promote preadipocyte differentiation. Different components have been identified that play a role in adipose tissue associated angiogenesis. Modulation of angiogenesis may have the potential to impair adipose tissue development and thus may provide a novel therapeutic approach for prevention and treatment of obesity.

Adipose angiogenesis: quantitative methods to study microvessel growth, regression and remodeling in vivo

Genetic and diet-induced rodent obesity models provide outstanding opportunities to study the role of angiogenesis and vascular remodeling in modulation of adipogenesis and obesity. In this study, we describe methods to quantitatively study adipose angiogenesis and vascular remodeling on the basis of immunohistochemical analyses. Fresh white adipose tissue or brown adipose tissue are prepared for whole mount, cryosectioned and paraffin-embedded samples, followed by staining with specific markers such as platelet endothelial cell adhesion molecule-1 (PECAM-1)/CD31, CD34, isolectin B4 or alpha-smooth muscle actin. Adipocytes are visualized by staining lipid droplets with 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene-3-dodecanoic acid (BODIPY) 558/568 C(12). This protocol may take 2-5 d to obtain results. In the view of the crucial roles of vasculature in modulation of adipogenesis and obesity, this protocol is valuable for studying the molecular mechanisms of angiogenesis in obese adipose tissues and for assessing the anti-obesity activity of angiogenesis modulators.

The adverse effects of obesity on conception and implantation

Whilst many multiparous women are obese (body mass index >30 kg/m(2)), obesity has been associated with impaired fecundity; however, the mechanism which links obesity to reduced fertility remains to be fully elucidated. Obese women, particularly those with central obesity, are less likely to conceive per cycle. Obese women suffer perturbations to the hypothalamic-pituitary-ovarian axis, menstrual cycle disturbance and are up to three times more likely to suffer oligo-/anovulation. A fine hormonal balance regulates follicular development and oocyte maturation, and it has been observed that obesity can alter the hormonal milieu. Leptin, a hormone produced by adipocytes, is elevated in obese women, and raised leptin has been associated with impaired fecundity. Obesity impairs ovulation but has also been observed to detrimentally affect endometrial development and implantation. The expression of polycystic ovary syndrome (PCOS) is regulated, in part, by weight, and so obese women with PCOS often have a more severe phenotype and experience more subfertility. Obesity also impairs the response of women to assisted conception treatments. Weight loss through lifestyle modification or bariatric surgery has been demonstrated to restore menstrual cyclicity and ovulation and improve the likelihood of conception. In this article, we will discuss the effect of obesity upon key reproductive mechanisms and its relation to fertility treatments.

Fat depot-specific differences in angiogenic growth factor gene expression and its relation to adipocyte size in cattle

Adipocytes derived from different anatomical sites vary in the expression of adipocytokines and growth factor genes. Adipogenesis is tightly associated with angiogenesis, although the regional variation of angiogenic growth factor gene expression in adipose tissues remains unclear. In this experiment, we studied the fat depot-specific differences (subcutaneous, intramuscular, intermuscular, renal, and mesenteric) in the expression of angiogenic growth factor mRNA [vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), fibroblast growth factor-10 (FGF-10), hepatocyte growth factor (HGF), and leptin], as well as the relationship between angiogenic growth factor mRNA level and adipocyte size in bovine adipose tissues. Intermuscular, renal, and mesenteric adipose tissues expressed significantly higher VEGF, FGF-2, and leptin mRNA levels than did subcutaneous and intramuscular adipose tissues. Mesenteric adipose tissue also expressed higher FGF-10 mRNA levels than did subcutaneous and intramuscular adipose tissues. There was no significant difference in the expression of HGF mRNA among adipose tissue depots. A significant correlation existed between adipocyte size and VEGF, FGF-2, FGF-10, and leptin mRNA levels. These results indicate that fat depot-specific difference in angiogenic growth factor gene expression results from the difference in adipocyte size.

Adipose tissue angiogenesis as a therapeutic target for obesity and metabolic diseases

Current pharmacotherapeutic options for treating obesity and related metabolic disorders remain limited and ineffective. Emerging evidence shows that modulators of angiogenesis affect the expansion and metabolism of fat mass by regulating the growth and remodelling of the adipose tissue vasculature. Pharmacological manipulation of adipose tissue neovascularization by angiogenic stimulators and inhibitors might therefore offer a novel therapeutic option for the treatment of obesity and related metabolic disorders. This Perspective discusses recent progress in understanding the molecular mechanisms that control adipose tissue angiogenesis and in defining potential new vascular targets and approaches for the treatment of this group of diseases.

Leptin levels in thyroid cancer

BACKGROUND

Leptin has physiological roles in multiple systems, and has possible effects on several carcinogenesis steps. The aim of this study was to investigate the leptin levels in thyroid papillary carcinoma (TPC) patients.

METHODS

Forty-three female TPC patients and 30 healthy female control subjects were recruited for the study. TPC was diagnosed by fine needle aspiration biopsy. TPC patients had a bilateral total thyroidectomy operation and their leptin levels were measured before and 20 days after the operation.

RESULTS

Serum leptin levels of TPC patients were higher than in control group subjects (21.15 +/- 14.12 ng/mL vs. 9.89 +/- 0.21 ng/mL, p < 0.05). The leptin levels decreased after total thyroidectomy (13.92 +/- 10.55 ng/mL) compared to prethyroidectomy levels (22.94 +/- 14.67 ng/mL) in 34 patients who came to the follow-up visit (p < 0.05). However, the decreased post-thyroidectomy levels of leptin were still statistically significantly higher than the control group levels. Multivariate regression analysis showed that the leptin levels in TPC patients were not related to age, menopausal status or pathologic occult status but were directly related to the cancer group.

CONCLUSION

Leptin levels were elevated in thyroid cancer, decreased after total thyroidectomy, and might be associated with thyroid papillary carcinogenesis.

Adiponectin induced placental cell apoptosis could be mediated via the ADIPOR1-receptor in pre-eclampsia with IUGR

AIMS

Adiponectin and leptin are members of the adipocytokine family. Adiponectin promotes and leptin inhibits apoptosis and both are regulators of angiogenesis. Adipocytokines and their receptors are expressed in the placenta, and in the pre-eclamptic (PE) mother the serum levels of both are higher than in healthy ones. Our aim was to study the expression of adiponectin, leptin, their receptor genes and apoptosis in severely PE and normal placentas.

METHODS

The study group comprised 13 PE mothers and their 16 healthy controls. Placental biopsies were taken during cesarean section, the RNA was extracted and micro-array study was performed, followed by PCR and apoptosis studies.

RESULTS

The placental expression level of the leptin and adiponectin receptor 1 genes was significantly higher in PE mothers than in controls. No significant changes were observed in the levels of the adiponectin, adiponectin receptor 2 and Leptin receptor genes. The expression of the Adiponectin gene was low. The rate of apoptosis was higher in the PE placentas.

CONCLUSIONS

The activity of placental adipocytokines and their receptor genes in severe PE may suggest an important role in placental angiogenesis. Placental apoptosis induced by adiponectin could be mediated via the ADIPOR1-receptor.

Angiogenic Effect of Leptin in the Quail Chorioallantoic Membrane

Leptin, the product ofobgene, beside its key role in the control of body weight and food consumption, can be involved in the control of embryonic development. Leptin administrationin ovoaccelerated the embryonic and post-embryonic development in Japanese quail. Although the mechanisms of leptin effects on growth and development acceleration are not clear, stimulation of angiogenesis represents one of plausible explanations. Therefore, the aim of the present study was to investigate the pro-angiogenic effect of leptinin vivoin the quail chorioallantoic membrane (CAM). The recombinant murine leptin (10, 100, and 1000 ng) was applied eitherex ovoon the CAM surface ofex ovoincubated embryos at embryonic day 7 (ED7) orin ovointo the egg albumen at ED5. Changes in blood vessels were quantified by the fractal analysis providing the fractal dimension (Df) estimate. Leptin administeredin ovowas more efficient in stimulation of angiogenesis than theex ovotreatment, since 10 ng dose elicited significantly higher (P< 0.001) stimulation of vessel development of the CAM under the air cell than it did afterex ovocultivation. Our study confirmed that exogenously applied leptin was able to stimulate angiogenesis in CAM. Leptin-mediated stimulation of angiogenesis may improve nutrient utilization from the yolk and explain at least partially the accelerating effect of leptin on avian embryo growth and development.

The vasa vasorum in diseased and nondiseased arteries

The vasa vasorum form a network of microvasculature that originate primarily in the adventitial layer of large arteries. These vessels supply oxygen and nutrients to the outer layers of the arterial wall. The expansion of the vasa vasorum to the second order is associated with neovascularization related to progression of atherosclerosis. Immunohistological analysis of human plaques from autopsied aortas have defined plaque progression and show a significant correlation with vasa vasorum neovascularization. Recent technological advances in microcomputed tomography have enabled investigation of vasa vasorum structure and function in nondiseased large arteries from pigs and dogs. Smaller mammals, particularly mice with genetic modifications that enable disease development, have been used extensively to study the vasa vasorum in diseased vessels. Despite the fact that most mouse models that are used to study atherosclerosis are unable to develop plaque to the extent found in humans, studies in both humans and mice underscore the importance of angiogenic vasa vasorum in progression of atherosclerosis. Those who have examined the vasa vasorum in occluded vessels of nondiseased pigs and dogs find that inhibition of the vasa vasorum makes the animals atheroprone. Atherosclerosis is a multifactorial disease. There is increasing evidence that factors, produced in response to changes in the arterial wall, collaborate with the vasa vasorum to enhance the disease process.

Estrogen exposure, obesity and thyroid disease in women with severe pulmonary hypertension

Severe pulmonary hypertension is a lethal group of disorders which preferentially afflicts women. It appears that in recent years the patient profile has shifted towards older, obese, and postmenopausal women, suggesting that endocrine factors may be important. Several studies have revealed an increased prevalence of thyroid disease in these patients, but no studies have evaluated for a coexistence of endocrine factors. In particular, no studies have attempted to evaluate for concurrent thyroid disease, obesity and long-term estrogen exposure in patients.

88 patients attending the Pulmonary Hypertension Association 8th International meeting completed a questionnaire and were interviewed. Information was collected regarding reproductive history, height, weight, and previous diagnosis of thyroid disease.

46% met criteria for obesity. 41% reported a diagnosis of thyroid disease. 81% of women reported prior use of hormone therapy. 70% reported greater than 10 years of exogenous hormone use. 74% of female patients reported two or more of potentially disease modifying endocrine factors (obesity, thyroid disease or estrogen therapy).

The coexistent high prevalence in our cohort of exogenous estrogen exposure, thyroid disease and obesity suggests that an interaction of multiple endocrine factors might contribute to the pathogenesis of pulmonary hypertension and may represent epigenetic modifiers in genetically-susceptible individuals.

Expression of angiogenic regulators, VEGF and leptin, is regulated by the EGF/PI3K/STAT3 pathway in colorectal cancer cells

Both leptin and vascular endothelial growth factor (VEGF) are growth and angiogenic cytokines that are upregulated in different types of cancer and have been implicated in neoplastic progression. Here we investigated the molecular mechanism by which leptin and VEGF expression are regulated in colon cancer by epidermal growth factor (EGF). In colon cancer cell line HT-29, EGF induced the binding of signal transducer and activator transcription 3 (STAT3) to STAT3 consensus motifs within the VEGF and leptin promoters and stimulated leptin and VEGF mRNA and protein synthesis. All these EGF effects were significantly blocked when HT-29 cells were treated with an inhibitor of the phosphoinositide 3-kinase (PI3K) pathway, LY294002, or with small interfering RNA (siRNA) targeting STAT3. Thus, our study identified the EGF/PI3K/STAT3 signaling as an essential pathway regulating VEGF and leptin expression in EGF-responsive colon cancer cells. This suggests that STAT3 pathways might constitute attractive pharmaceutical targets in colon cancer patients where anti-EGF receptor drugs are ineffective.

Leptin and its receptor are overexpressed in brain tumors and correlate with the degree of malignancy

Although leptin and its receptor (ObR) have emerged as important cancer biomarkers, the role of the leptin system in brain tumor development remains unknown. We screened 87 human brain tumor biopsies using immunohistochemistry and detected leptin and ObR in 55.2% and 60.9% cases, respectively. In contrast, leptin and ObR were absent in 14 samples of normal brain tissue. The presence of leptin correlated with ObR with overall concordance 80.5%. The leptin/ObR system was highly expressed in glioblastomas and anaplastic astrocytomas, while lower expression of both markers was noted in low-grade astrocytomas and gangliogliomas. The association between leptin/ObR and the degree of tumor malignancy was highly significant (P < 0.001). Using double immunofluorescence of glioblastoma tissues, we found co-expression of leptin with ObR and with the proliferation marker Ki-67 in 87% and 64% of cells, respectively. The leptin/ObR-positive tissues also expressed activated forms of STAT3 and Akt. In line with this finding, ObR-positive glioblastoma cells responded to leptin with cell growth and induction of the STAT3 and Akt pathways as well as inactivation of the cell cycle suppressor Rb. In summary, our data demonstrate that the leptin/ObR system is expressed in malignant brain tumors and might be involved in tumor progression.

Enhanced proliferation of human umbilical vein endothelial cells and differentiation of 3T3-L1 adipocytes in coculture

The interactions between adipocytes and endothelial cells in adipose tissue development are poorly understood. In this study, we characterized the growth and differentiation of 3T3-L1 preadipocytes and human umbilical vein endothelial cells (HUVECs) in planar and collagen gel cocultures. In planar coculture, preadipocyte proliferation was up to three times as great as in the control culture with only preadipocytes, where the increase was proportional to the HUVEC fraction in the seeding mixture. In the collagen gel coculture, triglyceride (TG) content (per adipocyte) was up to 3.4 times as much as in the control with only adipocytes. This effect depended on the total density and composition of the seeding mixture, with the largest increase observed at the highest density (2 x 10(6) cells/mL collagen) and preadipocyte:HUVEC ratio (90:10) tested in this study. Immunostaining showed that the collagen gel coculture also supported the elongation of endothelial cells. Blockade of vascular endothelial growth factor receptor 2 (VEGFR2) abolished the adipogenesis- and neovascularization-related effects of the coculture. Taken together, our results indicate that endothelial cell-mediated enhancement of adipocyte differentiation requires the activation of VEGFR2.

Angiogenesis, adipokines and breast cancer

The prevalence of overweight and obesity is rapidly increasing world wide. Numerous epidemiological studies have shown that obesity is a risk factor for postmenopausal breast cancer and relapse. However, the biological factors that drive the growth and progression of these tumors and how obesity contributes to the tumor microenvironment are poorly understood. Tumor development and metastasis are dependent on the process of angiogenesis or the formation of new blood vessels. More importantly, a ready supply of adipose tissue-derived angiogenic adipokines, notably VEGF and leptin, and the production of inflammatory cytokines by infiltrating macrophages that occurs in adipose tissues with obesity, promotes the paracrine stimulation of vascular endothelial cell growth needed for adipogenesis, while maintaining a microenvironment that is favorable for breast tumorigenesis.

Phase II study of sunitinib in men with advanced prostate cancer

BACKGROUND

This study explored the efficacy and tolerability of sunitinib, an inhibitor of tyrosine kinase receptors, in men with castration-resistant prostate cancer (CRPC).

METHODS

Men with no prior chemotherapy (group A) and men with docetaxel (Taxotere)-resistant prostate cancer (group B) were treated with sunitinib. The primary end point was confirmed 50% prostate-specific antigen (PSA) decline. Secondary end points included objective response rate and safety. Serum-soluble biomarkers were measured.

RESULTS

Seventeen men were enrolled in each group. One confirmed PSA response was observed in each group, and an additional eight men and seven men had stable PSA at week 12 in groups A and B, respectively. Improvements in imaging were observed in the absence of post-treatment PSA declines. Common adverse effects included fatigue, nausea, diarrhea, myelosuppression and transaminase elevation. Significant changes following sunitinib treatment were observed in serum-soluble biomarkers including soluble vascular endothelial growth factor receptor-2, platelet-derived growth factor aa, placental growth factor and leptin.

CONCLUSIONS

Sunitinib monotherapy resulted in few confirmed 50% post-treatment declines in PSA in men with CRPC. Serum markers of angiogenesis confirmed on-target effects of sunitinib. Assessments of radiographic disease status were often discordant with changes in PSA, indicating that alternate end points are important in future trials.

Mechanisms of lymphatic metastasis in human colorectal adenocarcinoma

The invasion of lymphatic vessels by colorectal cancer (CRC) and its subsequent spread to draining lymph nodes is a key determinant of prognosis in this common and frequently fatal malignancy. Although tumoural lymphangiogenesis is assumed to contribute to this process, review of the current literature fails to support any notion of a simple correlation between lymphatic vessel density and CRC metastasis. Furthermore, attempts to correlate the expression of various lymphangiogenic growth factors, most notably VEGF-C and VEGF-D, with the lymphatic metastasis of CRC have provided contradictory results. Recent evidence from animal and human models of tumour metastasis suggests that complex functional and biochemical interactions between the microvasculature of tumours and other cell types within the tumour microenvironment may play a pivotal role in the behaviour of commonly metastasizing tumours. Indeed, previous insights into tumoural blood vessels have provided candidate markers of tumoural angiogenesis that are currently the subject of intense investigation as future therapeutic targets. In this review article we survey the current evidence relating lymphangiogenesis and lymphangiogenic growth factor production to metastasis by CRC, and attempt to provide some insight into the apparent discrepancies within the literature. In particular, we also discuss some new and provocative insights into the properties of tumoural lymphatics suggesting that they have specific expression profiles distinct from those of normal lymphatic vessels and that appear to promote metastasis. These findings raise the exciting prospect of future biomarkers of lymphatic metastasis and identify potential targets for new generation anti-tumour therapies.

Glomerular endothelial cell fenestrations: an integral component of the glomerular filtration barrier

Glomerular endothelial cell (GEnC) fenestrations are analogous to podocyte filtration slits, but their important contribution to the glomerular filtration barrier has not received corresponding attention. GEnC fenestrations are transcytoplasmic holes, specialized for their unique role as a prerequisite for filtration across the glomerular capillary wall. Glomerular filtration rate is dependent on the fractional area of the fenestrations and, through the glycocalyx they contain, GEnC fenestrations are important in restriction of protein passage. Hence, dysregulation of GEnC fenestrations may be associated with both renal failure and proteinuria, and the pathophysiological importance of GEnC fenestrations is well characterized in conditions such as preeclampsia. Recent evidence suggests a wider significance in repair of glomerular injury and in common, yet serious, conditions, including diabetic nephropathy. Study of endothelial cell fenestrations is challenging because of limited availability of suitable in vitro models and by the requirement for electron microscopy to image these sub-100-nm structures. However, extensive evidence, from glomerular development in rodents to in vitro studies in human GEnC, points to vascular endothelial growth factor (VEGF) as a key inducer of fenestrations. In systemic endothelial fenestrations, the intracellular pathways through which VEGF acts to induce fenestrations include a key role for the fenestral diaphragm protein plasmalemmal vesicle-associated protein-1 (PV-1). The role of PV-1 in GEnC is less clear, not least because of controversy over existence of GEnC fenestral diaphragms. In this article, the structure-function relationships of GEnC fenestrations will be evaluated in depth, their role in health and disease explored, and the outlook for future study and therapeutic implications of these peculiar structures will be approached.

Angiogenesis in the New Zealand obese mouse model fed with high fat diet

Background

Obesity and its complications lead to vascular injury, atherosclerosis, diabetes and pathological angiogenesis. One of the models to study the obesity and its entanglements is the New Zealand Obese mice model. Aim of this study was to check the effect of high fat diet on changes in biochemical parameters as well as on process of angiogenesis in NZO mice.

Methods

NZO mice were fed with standard (ST) or high fat (HF) diet for seven weeks. Body weight and serum biochemical parameters were monitored. The PECAM1 positive vessel-like structures immunostaining, as well as the gene expression of the matrigel penetrating cells by microarray (confirmed by real-time PCR method) were analyzed.

Results

Mice fed with HF diet developed obesity. Number of newly created vessels with lumen was correlated with hyperglycemia and animal weight gain. The number of PECAM1 positive cells in matrigel tended to increase during HF diet. Microarray results revealed changes in gene expression (activation of the oxidative stress and insulin resistance, inhibition of apoptosis and cell differentiation), however without markers of endothelial cell network maturation.

Conclusion

Observed changes in the NZO mice on HF diet argue for the hyperglycemia related activation of angiogenesis, leading to the formation of pathological, immature network.

Regulation of Microvascular Function by Adipose Tissue in Obesity and Type 2 Diabetes: Evidence of an Adipose-Vascular Loop

In recent years, the general concept has emerged that chronic low-grade inflammation is the condition linking excessive development of adipose tissue and obesity-associated pathologies such as type 2 diabetes and cardiovascular diseases. Obesity and type 2 diabetes are characterized by a diminished production of protective factors such as adiponectin and increased detrimental adipocytokines such as leptin, resistin, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNFα), and monocyte chemoattractant protein-1 (MCP-1) by adipose tissue. Moreover, the evidence that the growth of the fat mass is associated with an accumulation of adipose tissue macrophages and T-lymphocytes has raised the hypothesis that the development of an inflammatory process within the growing fat mass is a primary event involved in the genesis of systemic metabolic and vascular alterations. This crosstalk of adipocyte, macrophage, lymphocyte, endothelial cells, and vascular smooth muscle cells contribute to the production of various cytokines, chemokines, and hormone-like factors, which actively participate in the regulation of vascular function by an endocrine and/or paracrine pattern. Thus, the signaling from perivascular adipose to the blood vessels is emerging as a potential therapeutic target for obesity and diabetes-associated vascular dysfunction.

Regulation of angiogenesis by oxygen and metabolism

Blood vessels form an important interface between the environment and the organism by carrying oxygen and nutrients to all cells and thus determining cellular metabolism. It is therefore not surprising that oxygen and metabolism influence the development of the vascular network. Here, we discuss recent insights regarding the emerging crosstalk between angiogenesis and metabolism. We will highlight advances in how oxygen and metabolism regulate angiogenesis as well as how angiogenic factors in turn also regulate metabolism.

Different transcriptional control of metabolism and extracellular matrix in visceral and subcutaneous fat of obese and rimonabant treated mice

BACKGROUND

The visceral (VAT) and subcutaneous (SCAT) adipose tissues play different roles in physiology and obesity. The molecular mechanisms underlying their expansion in obesity and following body weight reduction are poorly defined.

METHODOLOGY

C57Bl/6 mice fed a high fat diet (HFD) for 6 months developed low, medium, or high body weight as compared to normal chow fed mice. Mice from each groups were then treated with the cannabinoid receptor 1 antagonist rimonabant or vehicle for 24 days to normalize their body weight. Transcriptomic data for visceral and subcutaneous adipose tissues from each group of mice were obtained and analyzed to identify: i) genes regulated by HFD irrespective of body weight, ii) genes whose expression correlated with body weight, iii) the biological processes activated in each tissue using gene set enrichment analysis (GSEA), iv) the transcriptional programs affected by rimonabant.

PRINCIPAL FINDINGS

In VAT, "metabolic" genes encoding enzymes for lipid and steroid biosynthesis and glucose catabolism were down-regulated irrespective of body weight whereas "structure" genes controlling cell architecture and tissue remodeling had expression levels correlated with body weight. In SCAT, the identified "metabolic" and "structure" genes were mostly different from those identified in VAT and were regulated irrespective of body weight. GSEA indicated active adipogenesis in both tissues but a more prominent involvement of tissue stroma in VAT than in SCAT. Rimonabant treatment normalized most gene expression but further reduced oxidative phosphorylation gene expression in SCAT but not in VAT.

CONCLUSION

VAT and SCAT show strikingly different gene expression programs in response to high fat diet and rimonabant treatment. Our results may lead to identification of therapeutic targets acting on specific fat depots to control obesity.

Association of body mass index with severity of endometriosis in Korean women

OBJECTIVE

To investigate the relationship between endometriosis severity and body mass index (BMI).

METHODS

Of 481 women seen for endometriosis at a university hospital in Korea, 153 had stage I, 113 had stage II, 110 had stage III, and 105 had stage IV disease. The patients' BMIs were categorized according to World Health Organization criteria for Asian-Pacific populations.

RESULTS

Women with early or mild endometriosis (stages I or II) had a significantly higher BMI than those with advanced disease (stages III or IV) (P<0.001). After adjusting for age, parity, and menstrual factors, an association between BMI and disease stage remained significant (P<0.001).

CONCLUSION

Women with advanced-stage endometriosis had lower BMIs than those with minimal or mild disease, and BMI was significantly associated with disease severity.

Angiogenesis associated with visceral and subcutaneous adipose tissue in severe human obesity

OBJECTIVE

The expansion of adipose tissue is linked to the development of its vasculature. However, the regulation of adipose tissue angiogenesis in humans has not been extensively studied. Our aim was to compare the angiogenesis associated with subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) from the same obese patients in an in vivo model.

RESEARCH DESIGN AND METHODS

Adipose tissue samples from visceral (VAT) and subcutaneous (SAT) sites, obtained from 36 obese patients (mean BMI 46.5 kg/m(2)) during bariatric surgery, were layered on chick chorioallantoïc membrane (CAM).

RESULTS

Both SAT and VAT expressed angiogenic factors without significant difference for vascular endothelial growth factor (VEGF) expression. Adipose tissue layered on CAM stimulated angiogenesis. Angiogenic stimulation was macroscopically detectable, with engulfment of the samples, in 39% and was evidenced by angiography in 59% of the samples. A connection between CAM and adipose tissue vessels was evidenced by immunohistochemistry, with recruitment of both avian and human endothelial cells. The angiogenic potency of adipose tissue was not related to its localization (with an angiogenic stimulation in 60% of SAT samples and 61% of VAT samples) or to adipocyte size or inflammatory infiltrate assessed in adipose samples before the graft on CAM. Stimulation of angiogenesis by adipose tissue was nearly abolished by bevacizumab, which specifically targets human VEGF.

CONCLUSIONS

We have established a model to study the regulation of angiogenesis by human adipose tissue. This model highlighted the role of VEGF in angiogenesis in both SAT and VAT.

Impaired leptin activity in New Zealand Obese mice: model of angiogenesis

Leptin is prompt to drive angiogenesis, effecting proper vascularisation. Tissue remodeling (including adipose organ) is associated with the angiogenic response. The aim of this study was to investigate the effect of hyperleptinemia on angiogenesis in subcutaneous (s.c.) in vivo matrigel model in mice on a high fat (HF) diet. HF promoted adipose tissue accumulation and biochemical changes resembling metabolic syndrome. However, the impact of this dietary treatment on angiogenesis, measured in s.c. matrigel model was not significant. Changes in leptin concentration were not accompanied by significant angiogenic response. This lack of leptin activity and impaired signal transduction at the molecular level suggests malfunction of the leptin receptor in NZO mice.

Effects of weight loss after bariatric surgery for morbid obesity on vascular endothelial growth factor-A, adipocytokines, and insulin

BACKGROUND

Adipocytes regulate blood vessel formation, and in turn endothelial cells promote preadipocyte differentiation through the expression of proangiogenic factors, such as vascular endothelial growth factor (VEGF)-A. Some adipocytokines and hormones also have an effect on vascular development.

OBJECTIVES

Our objectives were to analyze the relationship between weight and circulating VEGF-A in morbidly obese subjects before and after bariatric surgery, and investigate the relationship between circulating VEGF-A and certain adipocytokines and hormones regulating adipocytes.

METHODS

A total of 45 morbidly obese women and nine lean females were included in the study. Patients underwent bariatric surgery: vertical banded gastroplasty (n=17), gastric bypass (n=17), and biliopancreatic diversion (n=11). Serum samples for VEGF-A, adiponectin, leptin, ghrelin, and insulin were obtained preoperatively and 9-12 months after surgery.

RESULTS

Obese patients showed significantly higher VEGF-A levels than controls (306.3+/-170.3 vs. 187.6+/-91.9 pg/ml; P=0.04), decreasing to 246.1+/-160.4 after surgery (P<0.001), with no differences among surgical procedures. In controls there was an inverse correlation between VEGF-A and ghrelin (r=-0.85; P<.01), but not in obese patients. Leptin and insulin concentrations were increased in obese patients, with a significant decrease shown after weight loss with surgery. Conversely, adiponectin concentrations were lower in obese patients, with a significant increase shown after weight loss with surgery. Ghrelin was higher in controls than obese patients, decreasing after gastric bypass and biliopancreatic diversion, but not after vertical banded gastroplasty.

CONCLUSION

Serum VEGF-A levels are significantly higher in obese patients than in lean controls, decreasing after weight loss with bariatric surgery, behaving similarly to other hormones related to adipose mass like leptin and insulin.

Quantitative and morphometric evaluation of the angiogenic effects of leptin

Angiogenesis is a dynamic process that requires an interaction of pro-and antiangiogenic factors. It is known that the cytokine leptin stimulates endothelial cell growth and angiogenesis, but further quantitative analysis is necessary to understand leptin angiogenic effects. The quail chorioallantoic membrane (CAM) assay has been used to study angiogenesis in vivo by focusing on morphometric parameters that quantify vascular complexity and density. We quantify the angiogenic activity of leptin using the CAM assay by digital morphometry and a computer-assisted image analysis to evaluate more precisely vessel length, diameter, branching, and tortuousity. CAM images are obtained from ex ovo cultures of E8-E9 quail embryos. MATLAB and custom software are used for our analysis. The effects of leptin, vascular endothelial growth factor-165 (VEGF(165)), and their corresponding neutralizing antibodies are compared. Our results show that CAM treated with leptin and VEGF(165) has a significant increase in vascular complexity and density. A corresponding decrease is observed using neutralizing antibodies. Notably, leptin induced more significant changes than VEGF in vessel length and tortuousity. Conversely, VEGF induced a greater increase in vessel branching than leptin. These results underscore the importance of using multiparametric quantitative methods to assess several aspects of angiogenesis and enable us to understand the proangiogenic effects of leptin.

The expression of adiponectin receptors and the effects of adiponectin and leptin on airway smooth muscle cells

PURPOSE

Obesity is a major risk factor for asthma and it influences airway smooth muscle function and responsiveness. Adiponectin is inversely associated with obesity and its action is mediated through at least 2 cell membrane receptors (AdipoR1 and AdipoR2). Leptin is positively associated with obesity. We investigated whether human airway smooth muscle (ASM) cells express adiponectin receptors and whether adiponectin and leptin regulate human ASM cell proliferation and vascular endothelial growth factor (VEGF) release.

MATERIALS AND METHODS

Human ASM cells were growth- arrested in serum-deprived medium for 48 hours and then stimulated with PDGF, adiponectin and leptin. After 48 hours of stimulation, proliferation was determined using a cell proliferation ELISA kit. Human AdipoR1 and -R2 mRNA expressions were determined by RT-PCR using human- specific AdipoR1 and -R2 primers. Concentrations of VEGF, monocyte chemotactic protein (MCP)-1 and macrophage inflammatory protein (MIP)-1alpha in cell culture supernatant were determined by ELISA.

RESULTS

Both AdipoR1 and AdipoR2 mRNA were expressed in the cultured human ASM cells. However, adiponectin did not suppress PDGF-enhanced ASM cell proliferation, nor did leptin promote ASM cell proliferation. Leptin promoted VEGF release by human ASM cells, while adiponectin did not influence VEGF release. Neither leptin nor adiponectin influenced MCP-1 secretion from human ASM cells. Adiponectin and MIP-1alpha were not secreted by human ASM cells.

CONCLUSION

Human ASM cells expressed adiponectin receptors. However, adiponectin did not regulate human ASM cell proliferation or VEGF release, while leptin stimulated VEGF release by human ASM cells.

A novel gene expression profile in lymphatics associated with tumor growth and nodal metastasis

Invasion of lymphatic vessels is a key step in the metastasis of primary tumors to draining lymph nodes. Although the process is enhanced by tumor lymphangiogenesis, it is unclear whether this is a consequence of increased lymphatic vessel number, altered lymphatic vessel properties, or both. Here we have addressed the question by comparing the RNA profiles of primary lymphatic endothelial cells (LEC) isolated from the vasculature of normal tissue and from highly metastatic T-241/vascular endothelial growth factor (VEGF)-C fibrosarcomas implanted in C57BL/6 mice. Our findings reveal significant differences in expression of some 792 genes (i.e., >or=2-fold up- or down-regulated, P <or= 0.05) that code for a variety of proteins including components of endothelial junctions, subendothelial matrix, and vessel growth/patterning. The tumor LEC profile, validated by immunohistochemical staining, is distinct from that of normal, inflammatory cytokine, or mitogen-activated LEC, characterized by elevated expression of such functionally significant molecules as the tight junction regulatory protein endothelial specific adhesion molecule (ESAM), the transforming growth factor-beta coreceptor Endoglin (CD105), the angiogenesis-associated leptin receptor, and the immunoinhibitory receptor CD200, and reduced expression of subendothelial matrix proteins including collagens, fibrillin, and biglycan. Moreover, we show similar induction of ESAM, Endoglin, and leptin receptor within tumor lymphatics in a series of human head and neck and colorectal carcinomas, and uncover a dramatic correlation between ESAM expression and nodal metastasis that identifies this marker as a possible prognostic indicator. These findings reveal a remarkable degree of phenotypic plasticity in cancer lymphatics and provide new insight into the processes of lymphatic invasion and lymph node metastasis.

Material-based deployment enhances efficacy of endothelial progenitor cells

Cell-based therapies are attractive for revascularizing and regenerating tissues and organs, but clinical trials of endothelial progenitor cell transplantation have not resulted in consistent benefit. We propose a different approach in which a material delivery system is used to create a depot of vascular progenitor cells in vivo that exit over time to repopulate the damaged tissue and participate in regeneration of a vascular network. Microenvironmental conditions sufficient to maintain the viability and outward migration of outgrowth endothelial cells (OECs) have been delineated, and a material incorporating these signals improved engraftment of transplanted cells in ischemic murine hindlimb musculature, and increased blood vessel densities from 260 to 670 vessels per mm(2), compared with direct cell injection. Further, material deployment dramatically improved the efficacy of these cells in salvaging ischemic murine limbs, whereas bolus OEC delivery was ineffective in preventing toe necrosis and foot loss. Finally, material deployment of a combination of OECs with another cell population commonly isolated from peripheral or cord blood, endothelial progenitor cells (EPCs) returned perfusion to normal levels in 40 days, and prevented toe and foot necrosis. Direct injection of an EPC/OEC combination was minimally effective in improving limb perfusion, and untreated limbs underwent autoamputation in 3 days. These results demonstrate that vascular progenitor cell utility is highly dependent on the mode of delivery, and suggest that one can create new vascular beds for a variety of applications with this material-controlled deployment of cells.

Leptin-leptin receptor are involved in angiogenesis in human hepatocellular carcinoma

Recent evidence in vitro and in vivo indicates that leptin, an adipose tissue-secreted hormone which is involved in the regulation of satiety, metabolic rate and thermogenesis, is implicated in angiogenesis. However, the role of leptin-mediated angiogenesis in hepatic carcinogenesis has not yet been completely elucidated. In this study, we have correlated microvascular density and leptin/leptin receptor (Ob-R) expression in endothelial and tumor cells with the histopathological type in human hepatocellular carcinoma (HCC). For this purpose, specimens of 40 primary HCC were submitted to immunohistochemical investigation using anti-CD31, anti-leptin and anti-Ob-R antibodies. Poorly-differentiated HCC had a higher degree of vascularization than other stages and leptin/Ob-R expression in both tumor and endothelial cells increased in parallel with the grade of malignancy and was highly correlated with the degree of angiogenesis. In the chick embryo chorioallantoic membrane in vivo assay, HCC biopsy specimens induced a strong angiogenic response, which was counteracted by an anti-leptin antibody. Taken together, these findings indicate that leptin/Ob-R correlate with angiogenesis and tumor progression in patients with HCC and that an anti-leptin antibody exerts an angiostatic activity in HCC.