VEGF-B signaling impairs endothelial glucose transcytosis by decreasing membrane cholesterol content

Thrombolysis exacerbates cerebrovascular injury after ischemic stroke via a VEGF-B dependent effect on adipose lipolysis

Cerebrovascular injuries leading to edema and hemorrhage after ischemic stroke are common. The mechanisms underlying these events and how they are connected to known risk factors for poor outcome, like obesity and diabetes, is relatively unknown. Herein we demonstrate that increased adipose tissue lipolysis is a dominating risk factor for the development of a compromised cerebrovasculature in ischemic stroke. Reducing adipose lipolysis by VEGF-B antagonism improved vascular integrity by reducing ectopic cerebrovascular lipid deposition. Thrombolytic therapy in ischemic stroke using tissue plasminogen activator (tPA) leads to increased risk of hemorrhagic complications, substantially limiting the use of thrombolytic therapy. We provide evidence that thrombolysis with tPA promotes adipose tissue lipolysis, leading to a rise in plasma fatty acids and lipid accumulation in the ischemic cerebrovasculature after stroke. VEGF-B blockade improved the efficacy and safety of thrombolysis suggesting the potential use of anti-VEGF-B therapy to extend the therapeutic window for stroke management.

Regulation of fatty acid delivery to metastases by tumor endothelium

Tumor metastasis, the main cause of death in cancer patients, requires outgrowth of tumor cells after their dissemination and residence in microscopic niches. Nutrient sufficiency is a determinant of such outgrowth1. Fatty acids (FA) can be metabolized by cancer cells for their energetic and anabolic needs but impair the cytotoxicity of T cells in the tumor microenvironment (TME)2,3, thereby supporting metastatic progression. However, despite the important role of FA in metastatic outgrowth, the regulation of intratumoral FA is poorly understood. In this report, we show that tumor endothelium actively promotes tumor growth and restricts anti-tumor cytolysis by transferring FA into developing metastatic tumors. This process uses transendothelial fatty acid transport via endosome cargo trafficking in a mechanism that requires mTORC1 activity. Thus, tumor burden was significantly reduced upon endothelial-specific targeted deletion of Raptor, a unique component of the mTORC1 complex (RptorECKO). In vivo trafficking of a fluorescent palmitic acid analog to tumor cells and T cells was reduced in RptorECKO lung metastatic tumors, which correlated with improved markers of T cell cytotoxicity. Combination of anti-PD1 with RAD001/everolimus, at a low dose that selectively inhibits mTORC1 in endothelial cells4, impaired FA uptake in T cells and reduced metastatic disease, corresponding to improved anti-tumor immunity. These findings describe a novel mechanism of transendothelial fatty acid transfer into the TME during metastatic outgrowth and highlight a target for future development of therapeutic strategies.

Exercise mitigates flow recirculation and activates metabolic transducer SCD1 to catalyze vascular protective metabolites

Exercise promotes pulsatile shear stress in the arterial circulation and ameliorates cardiometabolic diseases. However, exercise-mediated metabolic transducers for vascular protection remain under-investigated. Untargeted metabolomic analysis demonstrated that wild-type mice undergoing voluntary wheel running exercise expressed increased endothelial stearoyl-CoA desaturase 1 (SCD1) that catalyzes anti-inflammatory lipid metabolites, namely, oleic (OA) and palmitoleic acids (PA), to mitigate NF-κB-mediated inflammatory responses. In silico analysis revealed that exercise augmented time-averaged wall shear stress but mitigated flow recirculation and oscillatory shear index in the lesser curvature of the mouse aortic arch. Following exercise, endothelial Scd1-deleted mice (Ldlr-/- Scd1EC-/-) on high-fat diet developed persistent VCAM1-positive endothelium in the lesser curvature and the descending aorta, whereas SCD1 overexpression via adenovirus transfection mitigated endoplasmic reticulum stress and inflammatory biomarkers. Single-cell transcriptomics of the aorta identified Scd1-positive and Vcam1-negative endothelial subclusters interacting with other candidate genes. Thus, exercise mitigates flow recirculation and activates endothelial SCD1 to catalyze OA and PA for vascular endothelial protection.

Vascular Endothelial Growth Factor-D (VEGF-D): An Angiogenesis Bypass in Malignant Tumors

Vascular endothelial growth factors (VEGFs) are the key regulators of vasculogenesis in normal and oncological development. VEGF-A is the most studied angiogenic factor secreted by malignant tumor cells under hypoxic and inflammatory stress, which made VEGF-A a rational target for anticancer therapy. However, inhibition of VEGF-A by monoclonal antibody drugs led to the upregulation of VEGF-D. VEGF-D was primarily described as a lymphangiogenic factor; however, VEGF-D's blood angiogenic potential comparable to VEGF-A has already been demonstrated in glioblastoma and colorectal carcinoma. These findings suggested a role for VEGF-D in facilitating malignant tumor growth by bypassing the anti-VEGF-A antiangiogenic therapy. Owing to its high mitogenic ability, higher affinity for VEGFR-2, and higher expression in cancer, VEGF-D might even be a stronger angiogenic driver and, hence, a better therapeutic target than VEGF-A. In this review, we summarized the angiogenic role of VEGF-D in blood vasculogenesis and its targetability as an antiangiogenic therapy in cancer.

Obesity-induced changes in cancer cells and their microenvironment: Mechanisms and therapeutic perspectives to manage dysregulated lipid metabolism

Obesity has been closely related to cancer progression, recurrence, metastasis, and treatment resistance. We aim to review recent progress in the knowledge on the obese macroenvironment and the generated adipose tumor microenvironment (TME) inducing lipid metabolic dysregulation and their influence on carcinogenic processes. Visceral white adipose tissue expansion during obesity exerts systemic or macroenvironmental effects on tumor initiation, growth, and invasion by promoting inflammation, hyperinsulinemia, growth-factor release, and dyslipidemia. The dynamic relationship between cancer and stromal cells of the obese adipose TME is critical for cancer cell survival and proliferation as well. Experimental evidence shows that secreted paracrine signals from cancer cells can induce lipolysis in cancer-associated adipocytes, causing them to release free fatty acids and acquire a fibroblast-like phenotype. Such adipocyte delipidation and phenotypic change is accompanied by an increased secretion of cytokines by cancer-associated adipocytes and tumor-associated macrophages in the TME. Mechanistically, the availability of adipose TME free fatty acids and tumorigenic cytokines concomitant with the activation of angiogenic processes creates an environment that favors a shift in the cancer cells toward an aggressive phenotype associated with increased invasiveness. We conclude that restoring the aberrant metabolic alterations in the host macroenvironment and in adipose TME of obese subjects would be a therapeutic option to prevent cancer development. Several dietary, lipid-based, and oral antidiabetic pharmacological therapies could potentially prevent tumorigenic processes associated with the dysregulated lipid metabolism closely linked to obesity.

Expansion and collapse of VEGF diversity in major clades of the animal kingdom

Together with the platelet-derived growth factors (PDGFs), the vascular endothelial growth factors (VEGFs) form the PDGF/VEGF subgroup among cystine knot growth factors. The evolutionary relationships within this subgroup have not been examined thoroughly to date. Here, we comprehensively analyze the PDGF/VEGF growth factors throughout all animal phyla and propose a phylogenetic tree. Vertebrate whole-genome duplications play a role in expanding PDGF/VEGF diversity, but several limited duplications are necessary to account for the temporal pattern of emergence. The phylogenetically oldest PDGF/VEGF-like growth factor likely featured a C-terminus with a BR3P signature, a hallmark of the modern-day lymphangiogenic growth factors VEGF-C and VEGF-D. Some younger VEGF genes, such as VEGFB and PGF, appeared completely absent in important vertebrate clades such as birds and amphibia, respectively. In contrast, individual PDGF/VEGF gene duplications frequently occurred in fish on top of the known fish-specific whole-genome duplications. The lack of precise counterparts for human genes poses limitations but also offers opportunities for research using organisms that diverge considerably from humans. Sources for the graphical abstract: 326 MYA and older [1]; 72-240 MYA [2]; 235-65 MYA [3].

Atherosclerosis, Diabetes Mellitus, and Cancer: Common Epidemiology, Shared Mechanisms, and Future Management

The involvement of cardiovascular disease in cancer onset and development represents a contemporary interest in basic science. It has been recognized, from the most recent research, that metabolic syndrome-related conditions, ranging from atherosclerosis to diabetes, elicit many pathways regulating lipid metabolism and lipid signaling that are also linked to the same framework of multiple potential mechanisms for inducing cancer. Otherwise, dyslipidemia and endothelial cell dysfunction in atherosclerosis may present common or even interdependent changes, similar to oncogenic molecules elevated in many forms of cancer. However, whether endothelial cell dysfunction in atherosclerotic disease provides signals that promote the pre-clinical onset and proliferation of malignant cells is an issue that requires further understanding, even though more questions are presented with every answer. Here, we highlight the molecular mechanisms that point to a causal link between lipid metabolism and glucose homeostasis in metabolic syndrome-related atherosclerotic disease with the development of cancer. The knowledge of these breakthrough mechanisms may pave the way for the application of new therapeutic targets and for implementing interventions in clinical practice.

Exercise Mitigates Flow Recirculation and Activates Mechanosensitive Transcriptome to Uncover Endothelial SCD1-Catalyzed Anti-Inflammatory Metabolites

Exercise modulates vascular plasticity in multiple organ systems; however, the metabolomic transducers underlying exercise and vascular protection in the disturbed flow-prone vasculature remain under-investigated. We simulated exercise-augmented pulsatile shear stress (PSS) to mitigate flow recirculation in the lesser curvature of the aortic arch. When human aortic endothelial cells (HAECs) were subjected to PSS ( τ _ave = 50 dyne·cm ^-2 , ∂τ/∂t = 71 dyne·cm ^-2 ·s ^-1 , 1 Hz), untargeted metabolomic analysis revealed that Stearoyl-CoA Desaturase (SCD1) in the endoplasmic reticulum (ER) catalyzed the fatty acid metabolite, oleic acid (OA), to mitigate inflammatory mediators. Following 24 hours of exercise, wild-type C57BL/6J mice developed elevated SCD1-catalyzed lipid metabolites in the plasma, including OA and palmitoleic acid (PA). Exercise over a 2-week period increased endothelial SCD1 in the ER. Exercise further modulated the time-averaged wall shear stress (TAWSS or τ _ave) and oscillatory shear index (OSI _ave ), upregulated Scd1 and attenuated VCAM1 expression in the disturbed flow-prone aortic arch in Ldlr ^-/- mice on high-fat diet but not in Ldlr ^-/- Scd1 ^EC-/- mice. Scd1 overexpression via recombinant adenovirus also mitigated ER stress. Single cell transcriptomic analysis of the mouse aorta revealed interconnection of Scd1 with mechanosensitive genes, namely Irs2 , Acox1 and Adipor2 that modulate lipid metabolism pathways. Taken together, exercise modulates PSS ( τ _ave and OSI _ave ) to activate SCD1 as a metabolomic transducer to ameliorate inflammation in the disturbed flow-prone vasculature.

The Role of VEGF Family in Lipid Metabolism

The vascular endothelial growth factor (VEGF) family plays a major role in tumors and ophthalmic diseases. However, increasingly more data reported its potential in regulating lipids. With its biological functions mainly expressed in lymphatic vessels, some factors in the families, like VEGF-A and VEGF-C, have been proved to regulate intestinal absorption of lipids by affecting chylous ducts. Other effects, including regulating lipoprotein lipase (LPL), endothelial lipase (EL), and recombinant syndecan 1 (SDC1), have also been confirmed. However, given the scant-related studies, further research should be conducted to examine the concrete mechanisms and provide pragmatic ways to apply them in the clinic. The VEGF family may treat dyslipidemia in specific ways that are different from common methods and concurrently contribute to the treatment of other metabolic diseases, like diabetes and obesity.

Therapeutic Potential of VEGF-B in Coronary Heart Disease and Heart Failure: Dream or Vision?

Coronary heart disease (CHD) is the leading cause of death around the world. Based on the roles of vascular endothelial growth factor (VEGF) family members to regulate blood and lymphatic vessels and metabolic functions, several therapeutic approaches have been attempted during the last decade. However proangiogenic therapies based on classical VEGF-A have been disappointing. Therefore, it has become important to focus on other VEGFs such as VEGF-B, which is a novel member of the VEGF family. Recent studies have shown the very promising potential of the VEGF-B to treat CHD and heart failure. The aim of this review article is to present the role of VEGF-B in endothelial biology and as a potential therapeutic agent for CHD and heart failure. In addition, key differences between the VEGF-A and VEGF-B effects on endothelial functions are demonstrated.

Macrophage acetyl-CoA carboxylase regulates acute inflammation through control of glucose and lipid metabolism

Acetyl-CoA carboxylase (ACC) regulates lipid synthesis; however, its role in inflammatory regulation in macrophages remains unclear. We generated mice that are deficient in both ACC isoforms in myeloid cells. ACC deficiency altered the lipidomic, transcriptomic, and bioenergetic profile of bone marrow-derived macrophages, resulting in a blunted response to proinflammatory stimulation. In response to lipopolysaccharide (LPS), ACC is required for the early metabolic switch to glycolysis and remodeling of the macrophage lipidome. ACC deficiency also resulted in impaired macrophage innate immune functions, including bacterial clearance. Myeloid-specific deletion or pharmacological inhibition of ACC in mice attenuated LPS-induced expression of proinflammatory cytokines interleukin-6 (IL-6) and IL-1β, while pharmacological inhibition of ACC increased susceptibility to bacterial peritonitis in wild-type mice. Together, we identify a critical role for ACC in metabolic regulation of the innate immune response in macrophages, and thus a clinically relevant, unexpected consequence of pharmacological ACC inhibition.

Reducing VEGFB expression regulates the balance of glucose and lipid metabolism in mice via VEGFR1

In recent years, studies have demonstrated that vascular endothelial growth factor B (VEGFB) can affect the metabolism of fatty acids and glucose, and it is expected to become a target for the diagnosis and treatment of metabolic diseases such as obesity and diabetes. At present, the specific mechanism that VEGFB regulates lipid and glucose metabolism balance is not completely understood. The present study used systemic VEGFB gene-knockout mice to investigate the effects of downregulation of the VEGFB gene on lipid metabolism and insulin secretion, and to explore the mechanism of the VEGFB pathway involved in the regulation of glucose and lipid metabolism. The morphological changes in the liver and pancreas of mice after VEGFB gene deletion were observed under a light microscope and a scanning electron microscope, and the effects of VEGFB gene deletion on lipid metabolism and blood glucose balance were detected by a serological technique. The detection indexes included total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol. Simultaneously, fasting blood glucose, glycosylated hemoglobin A1c (HbA1c), fasting insulin and glucagon were measured. Insulin sensitivity was assessed by using the insulin tolerance tests and glucose tolerance tests, and function of β-cell islets was evaluated by using the insulin resistance index (HOMA-IR) and pancreatic β-cell secretion index (HOMA-β). Τhe protein expression changes of vascular endothelial growth factor receptor 1 (VEGFR1) and vascular endothelial growth factor receptor 2 (VEGFR2) in mouse islets were detected by western blotting and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) after the VEGFB gene was knocked down to analyze the mechanism of VEGFB that may be involved in glucose and lipid metabolism. It was observed that after VEGFB was knocked down, mouse hepatocytes exhibited steatosis and increased secretory vesicles in islet cells. The lipid metabolism indexes such as TG, TC and LDL increased significantly; however, the levels of FBS, postprandial blood glucose and HbA1c decreased, whereas the glucose tolerance increased. Serum insulin secretion increased and HOMA-IR decreased since VEGFB was knocked down. Western blotting and RT-qPCR results revealed that the expression levels of VEGFR1 and neuropilin-1 decreased after the VEGFB gene was knocked down, while the expression levels of VEGFA and VEGFR2 increased. The absence of VEGFB may be involved in the regulation of glucose and lipid metabolism in mice by activating the VEGFA/VEGFR2 signaling pathway. VEGFB is expected to become a new target for the treatment of metabolic diseases such as obesity and diabetes. At present, the mechanism of VEGFB involved in regulating lipid metabolism and glucose metabolism is not completely clear. It was identified that downregulating VEGFB improved lipid metabolism and insulin resistance. The role of VEGFB/VEGFR1 pathway and other family members in regulating glucose and lipid metabolism was detected, which provided a theoretical and experimental basis for VEGFB to affect the regulation of glucose and lipid metabolism balance.

Serum vascular endothelial growth factor b and metabolic syndrome incidence in the population based cohort Di@bet.es study

Background/Objectives

Although vascular endothelial growth factor b (VEGFb) might have an impact on the development of obesity, diabetes and related disorders, the possible relationship between VEGFb serum levels and the incidence of these metabolic complications in humans is still unknown. The aim of our study was to evaluate the association between VEGFb serum levels and the new-onset of metabolic syndrome (MS) and its components in the Spanish adult population after 7.5 years of follow-up.

Subjects/Methods

A total of 908 subjects from the Di@bet.es cohort study without MS at cross-sectional stage according to International Diabetes Federation (IDF) or Adult Treatment Panel III (ATP-III) criteria were included. Additionally, five sub-populations were grouped according to the absence of each MS component at baseline. Socio-demographic, anthropometric and clinical data were recorded. The Short Form of International Physical Activity Questionnaire (SF-IPAQ) was used to estimate physical activity. A fasting blood extraction and an oral glucose tolerance test were performed. Serum determinations of glucose, lipids, hsCRP and insulin were made. VEGFb levels were determined and categorized according to the 75th percentile of the variable. New cases of MS and its components were defined according to ATPIII and IDF criteria.

Results

A total of 181 or 146 people developed MS defined by IDF or ATP-III criteria respectively. Serum triglyceride levels, hs-CRP and systolic blood pressure at the baseline study were significantly different according to the VEGFb categories. Adjusted logistic regression analysis showed that the likelihood of developing MS and abdominal obesity was statistically reduced in subjects included in the higher VEGFb category.

Conclusion

Low serum levels of VEGFb may be considered as early indicators of incident MS and abdominal obesity in the Spanish adult population free of MS, independently of other important predictor variables.

The Role of the VEGF Family in Atherosclerosis Development and Its Potential as Treatment Targets

The vascular endothelial growth factor (VEGF) family, the crucial regulator of angiogenesis, lymphangiogenesis, lipid metabolism and inflammation, is involved in the development of atherosclerosis and further CVDs (cardiovascular diseases). This review discusses the general regulation and functions of VEGFs, their role in lipid metabolism and atherosclerosis development and progression. These functions present the great potential of applying the VEGF family as a target in the treatment of atherosclerosis and related CVDs. In addition, we discuss several modern anti-atherosclerosis VEGFs-targeted experimental procedures, drugs and natural compounds, which could significantly improve the efficiency of atherosclerosis and related CVDs' treatment.

Adenoviral VEGF-B186R127S gene transfer induces angiogenesis and improves perfusion in ischemic heart

Vascular endothelial growth factor B (VEGF-B) is an interesting therapeutic candidate for coronary artery disease. However, it can also cause ventricular arrhythmias, potentially preventing its use in clinics. We cloned VEGF-B isoforms with different receptor binding profiles to clarify the roles of VEGFR-1 and Nrp-1 in angiogenesis and to see if angiogenic properties can be maintained while avoiding side effects. VEGF-B constructs were studied in vivo using adenovirus (Ad)-mediated intramyocardial gene transfers into the normoxic and ischemic porcine heart (n = 51). It was found that the unprocessed isoform VEGF-B186R127S is as efficient angiogenic growth factor as the native VEGF-B186 in normoxic and ischemic heart. In addition, AdVEGF-B186R127S increased myocardial perfusion reserve by 22% in ischemic heart without any side effects. AdVEGF-B127 (VEGFR-1 and Nrp-1 ligand) and AdVEGF-B109 (VEGFR-1 ligand) did not induce angiogenesis. Thus, VEGF-B186 is angiogenic only before its proteolytic processing to VEGF-B127. Only the VEGF-B186 C-terminal fragment was associated with arrhythmias.

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AdVEGF-B186R127S induces angiogenesis and improves perfusion in the ischemic heart

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No significant side effects were observed after AdVEGF-B186R127S therapy

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VEGF-B186 is angiogenic only prior to its proteolytic processing

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C-terminal fragment of VEGF-B186 is associated with ventricular arrhythmias

The Role of the VEGF Family in Coronary Heart Disease

The vascular endothelial growth factor (VEGF) family, the regulator of blood and lymphatic vessels, is mostly investigated in the tumor and ophthalmic field. However, the functions it enjoys can also interfere with the development of atherosclerosis (AS) and further diseases like coronary heart disease (CHD). The source, regulating mechanisms including upregulation and downregulation, target cells/tissues, and known functions about VEGF-A, VEGF-B, VEGF-C, and VEGF-D are covered in the review. VEGF-A can regulate angiogenesis, vascular permeability, and inflammation by binding with VEGFR-1 and VEGFR-2. VEGF-B can regulate angiogenesis, redox, and apoptosis by binding with VEGFR-1. VEGF-C can regulate inflammation, lymphangiogenesis, angiogenesis, apoptosis, and fibrogenesis by binding with VEGFR-2 and VEGFR-3. VEGF-D can regulate lymphangiogenesis, angiogenesis, fibrogenesis, and apoptosis by binding with VEGFR-2 and VEGFR-3. These functions present great potential of applying the VEGF family for treating CHD. For instance, angiogenesis can compensate for hypoxia and ischemia by growing novel blood vessels. Lymphangiogenesis can degrade inflammation by providing exits for accumulated inflammatory cytokines. Anti-apoptosis can protect myocardium from impairment after myocardial infarction (MI). Fibrogenesis can promote myocardial fibrosis after MI to benefit cardiac recovery. In addition, all these factors have been confirmed to keep a link with lipid metabolism, the research about which is still in the early stage and exact mechanisms are relatively obscure. Because few reviews have been published about the summarized role of the VEGF family for treating CHD, the aim of this review article is to present an overview of the available evidence supporting it and give hints for further research.

Development of Novel Therapeutics Targeting the Blood-Brain Barrier: From Barrier to Carrier

The blood-brain barrier (BBB) is a highly specialized neurovascular unit, initially described as an intact barrier to prevent toxins, pathogens, and potentially harmful substances from entering the brain. An intact BBB is also critical for the maintenance of normal neuronal function. In cerebral vascular diseases and neurological disorders, the BBB can be disrupted, contributing to disease progression. While restoration of BBB integrity serves as a robust biomarker of better clinical outcomes, the restrictive nature of the intact BBB presents a major hurdle for delivery of therapeutics into the brain. Recent studies show that the BBB is actively engaged in crosstalk between neuronal and the circulatory systems, which defines another important role of the BBB: as an interfacing conduit that mediates communication between two sides of the BBB. This role has been subject to extensive investigation for brain-targeted drug delivery and shows promising results. The dual roles of the BBB make it a unique target for drug development. Here, recent developments and novel strategies to target the BBB for therapeutic purposes are reviewed, from both barrier and carrier perspectives.

Vascular endothelial growth factor B exerts lipid-lowering effect by activating AMPK via VEGFR1

As an ambiguous member of vascular endothelial growth factor family, VEGF-B has long been poorly understood in its function. Recent researches showed VEGF-B isoforms exerted their metabolic effect through indirectly activating the VEGF-A/VEGFR2 pathway. Here, we report the lipid-lowing effect of VEGF-B via VEGFR1. We investigated the effect of VEGF-B on lipid metabolism in vivo and in vitro approaches. Treatment of mice with VEGF-B recombinant protein repressed HFD-induced body weight gain. This treatment also alleviated obesity associated hyperlipidemia and fatty liver disease. In the muscle and liver of VEGF-B-treated HFD mice were observed increased protein expression of carnitine palmitoyltransferase-1 (CPT-1) and the phosphorylation of ACC and AMP-activated protein kinase (AMPK). This effect was confirmed in HepG2 cells incubated with VEFG-B in which the increased AMPK activation and CPT-1 expression occurs due to activation of Calcium/calmodulin-dependent Protein Kinase β (CaMKKβ) by VEFG-B. VEGF-B increased expression of key genes responsible for lipid oxidation while reducing those for fatty acid synthesis in vivo and in vitro. In addition, the selective inhibitor of VEGFR1 blocked the lipid clearance effect of VEGF-B in HepG2. Our study unraveled unknown role of VEGF-B/VEGFR1 signaling in regulating lipid metabolism. Furthermore, our findings indicate that VEGF-B may have beneficial effects for the treatment of dyslipidemia.

Trans-endothelial trafficking of metabolic substrates and its importance in cardio-metabolic disease

The endothelium acts as a gatekeeper, controlling the movement of biomolecules between the circulation and underlying tissues. Although conditions of metabolic stress are traditionally considered as causes of endothelial dysfunction, a principal driver of cardiovascular disease, accumulating evidence suggests that endothelial cells are also active players in maintaining local metabolic homeostasis, in part, through regulating the supply of metabolic substrates, including lipids and glucose, to energy-demanding organs. Therefore, endothelial dysfunction, in terms of altered trans-endothelial trafficking of these substrates, may in fact be an early contributor towards the establishment of metabolic dysfunction and subsequent cardiovascular disease. Understanding the molecular mechanisms that underpin substrate trafficking through the endothelium represents an important area within the vascular and metabolism fields that may offer an opportunity for identifying novel therapeutic targets. This mini-review summarises the emerging mechanisms regulating the trafficking of lipids and glucose through the endothelial barrier and how this may impact on the development of cardio-metabolic disease.

Obesity-Related Fatty Acid and Cholesterol Metabolism in Cancer-Associated Host Cells

Obesity-derived disturbances in fatty acid and cholesterol metabolism are linked to numerous diseases, including various types of malignancy. In tumor cells, metabolic alterations have been long recognized and intensively studied. However, metabolic changes in host cells in the tumor microenvironment and their contribution to tumor development have been largely overlooked. During the last decade, research advances show that fatty acid oxidation, cholesterol metabolism, and lipid accumulation play critical roles in cancer-associated host cells such as endothelial cells, lymph endothelial cells, cancer-associated fibroblasts, tumor-associated myeloid cells, and tumor-associated lymphocytes. In addition to anti-angiogenic therapies and immunotherapy that have been practiced in the clinic, metabolic regulation is considered another promising cancer therapy targeting non-tumor host cells. Understanding the obesity-associated metabolism changes in cancer-associated host cells may ultimately be translated into therapeutic options that benefit cancer patients. In this mini-review, we briefly summarize the lipid metabolism associated with obesity and its role in host cells in the tumor microenvironment. We also discuss the current understanding of the molecular pathways involved and future perspectives to benefit from this metabolic complexity.

The Endothelium: An Active Regulator of Lipid and Glucose Homeostasis

The vascular endothelium serves as a dynamic barrier that separates blood from interstitia. Endothelial cells (ECs) respond rapidly to changes in the circulation and actively regulate vessel tone, permeability, and platelet functions. ECs also secrete angiocrine factors that dictate the function of adjacent parenchymal cells in an organ-specific manner. Endothelial dysfunction is considered as a hallmark of metabolic diseases. However, there is emerging evidence that ECs modulate the transfer of nutrients and hormones to parenchymal cells in response to alterations in metabolic profile. As such, a causal role for ECs in systemic metabolic dysregulation can be envisaged. This review summarizes recent progress in the understanding of regulated fatty acid, glucose, and insulin transport across the endothelium and discusses its pathophysiological implications.

VEGF-B signaling impairs endothelial glucose transcytosis by decreasing membrane cholesterol content

Regulation of endothelial nutrient transport is poorly understood. Vascular endothelial growth factor B (VEGF‐B) signaling in endothelial cells promotes uptake and transcytosis of fatty acids from the bloodstream to the underlying tissue, advancing pathological lipid accumulation and lipotoxicity in diabetic complications. Here, we demonstrate that VEGF‐B limits endothelial glucose transport independent of fatty acid uptake. Specifically, VEGF‐B signaling impairs recycling of low‐density lipoprotein receptor (LDLR) to the plasma membrane, leading to reduced cholesterol uptake and membrane cholesterol loading. Reduced cholesterol levels in the membrane leads to a decrease in glucose transporter 1 (GLUT1)‐dependent endothelial glucose uptake. Inhibiting VEGF‐B in vivo reconstitutes membrane cholesterol levels and restores glucose uptake, which is of particular relevance for conditions involving insulin resistance and diabetic complications. In summary, our study reveals a mechanism whereby VEGF‐B regulates endothelial nutrient uptake and highlights the impact of membrane cholesterol for regulation of endothelial glucose transport.