The vascular endothelial growth factor (VEGF), a homodimeric vasoactive glycoprotein, is the key mediator of angiogenesis. Angiogenesis, the formation of new blood vessels, is responsible for a wide variety of physio/pathological processes, including cardiovascular diseases (CVD). Cardiomyocytes (CM), the main cell type present in the heart, are the source and target of VEGF-A and express its receptors, VEGFR1 and VEGFR2, on their cell surface. The relationship between VEGF-A and the heart is double-sided. On the one hand, VEGF-A activates CM, inducing morphogenesis, contractility and wound healing. On the other hand, VEGF-A is produced by CM during inflammation, mechanical stress and cytokine stimulation. Moreover, high concentrations of VEGF-A have been found in patients affected by different CVD, and are often correlated with an unfavorable prognosis and disease severity. In this review, we summarized the current knowledge about the expression and effects of VEGF-A on CM and the role of VEGF-A in CVD, which are the most important cause of disability and premature death worldwide. Based on clinical studies on angiogenesis therapy conducted to date, it is possible to think that the control of angiogenesis and VEGF-A can lead to better quality and span of life of patients with heart disease.

Neutrophils are key effector cells that orchestrate inflammatory responses in the tumor microenvironment. Although neutrophil extracellular DNA traps (NETs) entrap and kill pathogens, they also contribute to chronic inflammation and cancer progression. Thyroid cancer (TC) is the most frequently occurring cancer of the endocrine system, accounting for 70% of deaths due to endocrine tumors. Although anaplastic TC (ATC) is rare among TCs, it is highly lethal. We demonstrated in a recent study that tumor-infiltrating neutrophil density correlated with TC size. Moreover, TC-derived soluble mediators modulate the human neutrophil phenotype. Our study aimed to investigate the involvement of NETs in human TC. Highly purified neutrophils from healthy donors were primed in vitro with a papillary TC or ATC cell line conditioned medium (CM) or with a normal thyroid CM as control. NET release was quantified using a High-Content Imaging System. Neutrophil viability was assessed by flow cytometry. Fluorescence microscopy, flow cytometry, and PCR were performed to determine the mitochondrial origin of ATC-induced NETs. ATC CM–primed neutrophils were cocultured with ATC cells to determine the effects exerted by NETs on cell proliferation. ATC CM induce NET release, whereas papillary TC or normal thyroid CM did not. ATC CM–induced NET production occurred in a reactive oxygen species–dependent and cell death–independent manner and was associated with mitochondrial reactive oxygen species production; the NETs contained mitochondrial DNA. ATC CM–primed neutrophils promoted ATC cell proliferation in a NET-dependent manner.

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Thymic stromal lymphopoietin (TSLP) is a pleiotropic cytokine highly expressed by epithelial cells and several innate and adaptive immune cells. TSLP exerts its biological effects by binding to a heterodimeric complex composed of TSLP receptor (TSLPR) and IL-7Rα. In humans, there are two TSLP isoforms: the short form (sfTSLP), constitutively expressed, and the long form (lfTSLP), which is upregulated in inflammation. TSLP has been implicated in the induction and progression of several experimental and human cancers. Primary human lung macrophages (HLMs), monocyte-derived macrophages (MDMs), and peripheral blood monocytes consitutively expressed sfTSLP mRNA. Incubation of HLMs, MDMs, and monocytes with lipopolysaccharide (LPS) or IL-4, but not with IL-13, induced TSLP release from HLMs. LPS, but not IL-4 or IL-13, induced CXCL8 release from HLMs. LPS, IL-4 alone or in combination with IL-13, induced the expression of lfTSLP, but not of sfTSLP from HLMs. Preincubation of HLMs with IL-4, alone or in combination with IL-13, but not IL-13 alone, synergistically enhanced TSLP release from LPS-activated macrophages. By contrast, IL-4, alone or in combination with IL-13, inhibited LPS-induced CXCL8 release from HLMs. Immunoreactive TSLP was detected in lysates of HLMs, MDMs, and monocytes. Incubation of HLMs with TSLP induced the release of proinflammatory (TNF-α), angiogenic (VEGF-A, angiopoietin 2), and lymphangiogenic (VEGF-C) factors. TSLP, TSLPR, and IL-7Rα were expressed in intratumoral and peritumoral areas of human lung cancer. sfTSLP and lfTSLP mRNAs were differentially expressed in peritumoral and intratumoral lung cancer tissues. The TSLP system, expressed in HLMs, MDMs, and monocytes, could play a role in chronic inflammatory disorders including lung cancer.

Neutrophils (PMNs) are innate immune cells with primary roles in inflammation and in host defense against infections. Both inflammatory and tumor angiogenesis are modulated by a sequential, coordinated production of angiogenic factors such as vascular endothelial growth factors (VEGFs), angiopoietins, hepatocyte growth factor (HGF), and chemokines. These factors are produced by several immune cells, including PMNs. Activation of cannabinoid receptor type-1 (CB 1) and-2 (CB 2) has been suggested as a new strategy to modulate in vitro and in vivo angiogenesis. We sought to investigate whether activation of CB 1 and CB 2 by CB agonists modulate LPS-mediated angiogenic activity of human PMNs. Highly purified PMNs were isolated from buffy coats of healthy donors. Cells were stimulated with CB 1 and CB 2 agonists/antagonists alone and/or in combination with LPS. Angiogenic factors in cell-free supernatants were measured by ELISA. The modulation of activation markers of PMNs by CB agonists was evaluated by flow cytometry. Angiogenesis in vitro was measured as tube formation by optical microscopy. Endothelial cell permeability was assessed by an in vitro vascular permeability assay. LPS-activated PMNs released VEGF-A, CXCL8, and HGF. Preincubation of PMNs with low concentrations of CB 1 and CB 2 agonists inhibited VEGF-A release induced by LPS, but did not affect CXCL8 and HGF production. The effects of CB agonists on VEGF-A release induced by LPS were reversed by preincubation with CB antagonists. CB agonists modulated in vitro angiogenesis and endothelial permeability induced by supernatants of LPS-activated PMNs through the reduction of VEGF-A. Neutrophils play a central role in the control of bacterial infections and in the outcome of sepsis. The latter condition is associated with an increase in circulating levels of VEGF-A. We demonstrated that low concentrations of CB agonists inhibit VEGF-A release from LPS-activated PMNs. These results suggest that CB agonists might represent a novel therapeutic strategy in patients with sepsis.

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The therapeutic potential of Cannabis sativa has been recognized since ancient times. Phytocannabinoids, endocannabinoids and synthetic cannabinoids activate two major G protein-coupled receptors, subtype 1 and 2 (CB1 and CB2). Cannabinoids (CBs) modulate several aspects of cancer cells, such as apoptosis, autophagy, proliferation, migration, epithelial-to-mesenchymal transition and stemness. Moreover, agonists of CB1 and CB2 receptors inhibit angiogenesis and lymphangiogenesis in vitro and in vivo. Low-grade inflammation is a hallmark of cancer in the tumor microenvironment (TME), which contains a plethora of innate and adaptive immune cells. These cells play a central role in tumor initiation and growth and the formation of metastasis. CB2 and, to a lesser extent, CB1 receptors are expressed on a variety of immune cells present in TME (e.g., T cells, macrophages, mast cells, neutrophils, NK cells, dendritic cells, monocytes, eosinophils). The activation of CB receptors modulates a variety of biological effects on cells of the adaptive and innate immune system. The expression of CB2 and CB1 on different subsets of immune cells in TME and hence in tumor development is incompletely characterized. The recent characterization of the human cannabinoid receptor CB2-Gi signaling complex will likely aid to design potent and specific CB2/CB1 ligands with therapeutic potential in cancer.

Mastocytosis is a disorder characterized by the abnormal proliferation and/or accumulation of mast cells in different organs. More than 90% of patients with systemic mastocytosis have a gain-of-function mutation in codon 816 of the KIT receptor on mast cells (MCs). The symptoms of mastocytosis patients are related to the MC-derived mediators that exert local and distant effects. MCs produce angiogenic and lymphangiogenic factors, including vascular endothelial growth factors (VEGFs) and angiopoietins (ANGPTs). Serum concentrations of VEGF-A, VEGF-C, VEGF-D, ANGPT1 and ANGPT2 were determined in 64 mastocytosis patients and 64 healthy controls. Intracellular concentrations and spontaneous release of these mediators were evaluated in the mast cell lines ROSAKIT WT and ROSA KIT D816V and in human lung mast cells (HLMCs). VEGF-A, ANGPT1, ANGPT2 and VEGF-C concentrations were higher in mastocytosis patients compared to controls. The VEGF-A, ANGPT2 and VEGF-C concentrations were correlated with the symptom severity. ANGPT1 concentrations were increased in all patients compared to controls. ANGPT2 levels were correlated with severity of clinical variants and with tryptase levels. VEGF-A, ANGPT1 and VEGF-C did not differ between indolent and advanced mastocytosis. ROSAKIT WT, ROSAKIT D816V and HLMCs contained and spontaneously released VEGFs and ANGPTs. Serum concentrations of VEGFs and ANGPTs are altered in mastocytosis patients.