Vascular permeability factor: a tumor-derived polypeptide that induces endothelial cell and monocyte procoagulant activity, and promotes monocyte migration

A review concerning the breast cancer-related tumour microenvironment

Breast cancer (BC) is currently the most common malignant tumour in women and one of the leading causes of their death around the world. New and increasingly personalised diagnostic and therapeutic tools have been introduced over the last few decades, along with significant advances regarding the study and knowledge related to BC. The tumour microenvironment (TME) refers to the tumour cell-associated cellular and molecular environment which can influence conditions affecting tumour development and progression. The TME is composed of immune cells, stromal cells, extracellular matrix (ECM) and signalling molecules secreted by these different cell types. Ever deeper understanding of TME composition changes during tumour development and progression will enable new and more innovative therapeutic strategies to become developed for targeting tumours during specific stages of its evolution. This review summarises the role of BC-related TME components and their influence on tumour progression and the development of resistance to therapy. In addition, an account on the modifications in BC-related TME components associated with therapy is given, and the completed or ongoing clinical trials related to this topic are presented.

Elevated VEGF-A Levels in the Aqueous Humor of Patients With Primary Open Angle Glaucoma

BACKGROUND/AIM

The purpose of the current study was to compare the vascular endothelial growth factor-A (VEGF-A) levels in the aqueous humor of patients with primary open angle glaucoma (POAG) and non-glaucomatous eyes and reveal any potential statistically significant correlations.

PATIENTS AND METHODS

This was an observational cross-sectional study. Aqueous humor samples (50-100 μl) were collected under aseptic conditions, from the anterior chamber at the start of glaucoma or cataract surgery. The levels of VEGF-A were measured using a multiplex bead-based immunoassay.

RESULTS

Aqueous humor samples were obtained from 76 participants: 39 with POAG and 36 with age-related cataracts as controls. VEGF-A levels were significantly elevated in the POAG group (166.37±110.04 pg/ml, p=0.011) compared to the control group (119.02±49.09 pg/ml). The receiver operating characteristic (ROC) analysis showed that VEGF-A had significant prognostic ability for POAG (AUC=0.67; p=0.006). An optimal cut-off for VEGF-A was found to be 148.5 pg/ml with a sensitivity of 54%, specificity of 81.1%, positive prognostic value (PPV) of 75% and negative prognostic value (NPV) of 62.5%. Logistic regression analysis showed that after adjusting for sex and age, patients with VEGF-A higher than 148.5 pg/ml had almost 10 times greater likelihood for POAG.

CONCLUSION

VEGF-A is elevated in patients with POAG and can potentially have a prognostic ability for these patients.

EML4-ALK fusion protein in Lung cancer cells enhances venous thrombogenicity through the pERK1/2-AP-1-tissue factor axis

BACKGROUND

Accumulating evidence links the echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase (ALK) rearrangement to venous thromboembolism (VTE) in non-small cell lung cancer (NSCLC) patients. However, the corresponding mechanisms remain unclear.

METHOD

High-throughput sequencing analysis of H3122 human ALK-positive NSCLC cells treated with ALK inhibitor/ dimethyl sulfoxide (DMSO) was performed to identify coagulation-associated differential genes between EML4-ALK fusion protein inhibited cells and control cells. Sequentially, we confirmed its expression in NSCLC patients' tissues and in the plasma of a subcutaneous xenograft mouse model. An inferior vena cava (IVC) ligation model was used to assess clot formation potential. Additionally, pathways involved in tissue factor (TF) regulation were explored in ALK-positive cell lines H3122 and H2228. Statistical significance was determined by Student t-test and one-way ANOVA using SPSS.

RESULTS

Sequencing analysis identified a significant downregulation of TF after inhibiting EML4-ALK fusion protein activity in H3122 cells. In clinical NSCLC cases, TF expression was increased especially in ALK-positive NSCLC tissues. Meanwhile, H3122 and H2228 with high TF expression exhibited shorter plasma clotting time and higher TF activity versus ALK-negative H1299 and A549 in cell culture supernatant. Mice bearing H2228 tumor showed a higher concentration of tumor-derived TF and TF activity in plasma and the highest adjusted IVC clot weights. Limiting EML4-ALK protein phosphorylation downregulated extracellular regulated protein kinases 1/2 (ERK1/2)-activating the protein-1(AP-1) signaling pathway and thus attenuated TF expression.

CONCLUSION

EML4-ALK fusion protein may enhance venous thrombogenicity by regulating coagulation factor TF expression. There was potential involvement of the pERK1/2-AP-1 pathway in this process.

VEGF levels in the aqueous humor of patients with primary open angle glaucoma: A systematic review and a meta-analysis

PURPOSE

To compare the VEGF levels in the aqueous humor of patients with Primary Open Angle Glaucoma (POAG) and non-glaucomatous eyes and reveal any potential statistically significant correlations.

METHODS

We searched PubMed, from inception to December 31, 2021. Key search terms included VEGF and Glaucoma. All relevant studies that evaluated the VEGF levels in patients with POAG and in the control group were included in this systematic review. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis of Diagnostic Test Accuracy Studies (PRISMA-DTA) guidelines were followed. Data were extracted independently by 2 authors. Heterogeneity was statistically quantified by Q, H, and I2 statistics, and a meta-analysis was performed using the random-effects model.

RESULTS

Seven cross-sectional studies were included in the meta-analysis. 144 eyes were enrolled in the POAG group and 162 eyes in the control group. The random effect model showed no statistically significant difference between the two groups (SMD =0.284, 95% CI = -0.173 to 0.741; P = 0.223), but we noticed a trend towards elevated VEGF levels in the aqueous humor of POAG patients. Significant heterogeneity was detected (I2 = 74.1%, P = 0.001).

CONCLUSIONS

This systematic review and meta-analysis indicates a trend towards elevated VEGF-A levels in the aqueous humor of patients with POAG and suggests a potential neuroprotective role of VEGF in patients with POAG. Future studies are required to evaluate the exact role of VEGF in POAG.

Biomarkers of endothelial dysfunction are associated with poor outcome in COVID-19 patients: A systematic review and meta-analysis

Numerous studies have linked coronavirus disease 2019 (COVID-19) with endothelial dysfunction and reported elevated levels of endothelial biomarkers in this disease. We conducted a systematic review and meta-analysis of the published evidence in this respect. A systematic literature search of PubMed and Scopus databases was performed to find studies investigating biomarkers of endothelial dysfunction in COVID-19 patients. Pooled standardized mean differences and their 95% confidence intervals were calculated for each biomarker using random effect model. 74 studies with 7668 patients were included. In comparison to patients with good outcome, those with poor outcome had higher levels of von Willebrand factor (vWF) (SMD: 0.83, 95% CI: 0.59-1.07, p < 0.00001), vWF:ADAMTS13 (1.23, (0.77-1.7), p < 0.00001), angiopoietin-2 (Ang-2) (1.06 (0.6-1.51), p < 0.0001), E-selectin (1.09 (0.55-1.63), p < 0.0001), P-selectin (0.59 (0.24-0.94), p = 0.001), syndecan-1 (0.99 (0.6-1.37), p < 0.00001), mid-regional pro-adrenomedullin (MR-proADM) (1.52 (1.35-1.68), p < 0.00001), vascular endothelial growth factor (0.27 (0.02-0.53), p = 0.03), soluble fms-like tyrosine kinase-1 (sFLT-1) (1.93 (0.65-3.21), p = 0.03) and lower levels of ADAMTS13 antigen (-0.69 (-0.9 to -0.47) p < 0.00001) and activity (-0.84 (-1.06 to -0.61) p < 0.0000). Plasminogen activator inhibitor-1 and tissue plasminogen activator levels were not different between the two groups (p < 0.05). There were elevated levels of endothelial dysfunction biomarkers in COVID-19 patients with poor outcome, indicating their possible role in disease severity and prognosis. In particular, MR-proADM, vWF, syndecan-1 and sFLT-1 showed a significant association with poor outcome in these patients.

Reduced Angiopoietin Factor 2 Levels Are Correlated with Better Cardiac Function and Prognosis in Valvular Heart Disease

INTRODUCTION

There are few circulating biomarkers for valvular heart disease. Angiopoietin (Ang) 1, Ang2, and vascular endothelial growth factor are important inflammation-associated cytokines. The aim of this study was to investigate the clinical significance and association of Ang1, Ang2, and vascular endothelial growth factor in valvular heart disease.

METHODS

This is a retrospective study; a total of 62 individuals (valvular heart disease patients [n=42] and healthy controls [n=20]) were included. Plasma levels of Ang1, Ang2, and vascular endothelial growth factor were detected by enzyme-linked immunosorbent assays. We retrospectively collected the baseline characteristics and short-term outcomes; logistic regression was performed to identify predictor for short-term mortality.

RESULTS

Ang2 was significantly decreased in the valvular heart disease group compared with the healthy control group (P=0.023), while no significant difference was observed in the Ang1 and vascular endothelial growth factor levels. The Ang2 level of New York Heart Association (NYHA) I/II patients - but not NYHA III/IV patients - was significantly decreased compared with that of healthy control individuals (NYHA I/II: P=0.017; NYHA III/IV: P=0.485). Univariable logistic regression analysis indicated that Ang2 was a significant independent predictor for short-term mortality (odds ratio 18.75, P=0.033, 95% confidence interval 8.08-102.33). Ang1 was negatively correlated with Ang2 (P=0.032, Pearson's correlation coefficient =-0.317) and was positively correlated with vascular endothelial growth factor (P=0.019, Pearson's correlation coefficient = 0.359).

CONCLUSION

Ang2 might serve as a therapeutic and prognostic target for valvular heart disease.

The Intricate Role of Non-Coding RNAs in Sepsis-Associated Disseminated Intravascular Coagulation

Disseminated Intravascular Coagulation (DIC) is a type of tissue and organ dysregulation in sepsis, due mainly to the effect of the inflammation on the coagulation system. Unfortunately, the underlying molecular mechanisms that lead to this disorder are not fully understood. Moreover, current biomarkers for DIC, including biological and clinical parameters, generally provide a poor diagnosis and prognosis. In recent years, non-coding RNAs have been studied as promising and robust biomarkers for a variety of diseases. Thus, their potential in the diagnosis and prognosis of DIC should be further studied. Specifically, the relationship between the coagulation cascade and non-coding RNAs should be established. In this review, microRNAs, long non-coding RNAs, and circular RNAs are studied in relation to DIC. Specifically, the axis between these non-coding RNAs and the corresponding affected pathway has been identified, including inflammation, alteration of the coagulation cascade, and endothelial damage. The main affected pathway identified is PI3K/AKT/mTOR axis, where several ncRNAs participate in its regulation, including miR-122-5p which is sponged by circ_0005963, ciRS-122, and circPTN, and miR-19a-3p which is modulated by circ_0000096 and circ_0063425. Additionally, both miR-223 and miR-24 were found to affect the PI3K/AKT pathway and were regulated by lncGAS5 and lncKCNQ1OT1, respectively. Thus, this work provides a useful pipeline of inter-connected ncRNAs that future research on their impact on DIC can further explore.

Thrombosis, cancer, and COVID-19

Cancer and coronavirus disease 2019 (COVID-19) have unusual similarities: they both result in a markedly elevated risk of thrombosis, exceptionally high D-dimer levels, and the failure of anticoagulation therapy in some cases. Cancer patients are more vulnerable to COVID-19 infection and have a higher mortality rate. Science has uncovered much about SARS-CoV-2, and made extraordinary and unprecedented progress on the development of various treatment strategies and COVID-19 vaccines. In this review, we discuss known data on cancer-associated thrombosis (CAT), SARS-CoV-2 infection, and COVID-19 vaccines and discuss considerations for managing CAT in patients with COVID-19. Cancer patients should be given priority for COVID-19 vaccination; however, they may demonstrate a weaker immune response to COVID-19 vaccines than the general population. Currently, the Centers for Disease Control and Prevention recommends an additional dose and booster shot of the COVID-19 vaccine after the primary series in patients undergoing active cancer treatment for solid tumors or hematological cancers, recipients of stem cell transplant within the last 2 years, those taking immunosuppressive medications, and those undergoing active treatment with high-dose corticosteroids or other drugs that suppress the immune response. The mainstay of thrombosis treatment in patients with cancer and COVID-19 is anticoagulation therapy.

Dicer Enhances Bevacizumab-Related Inhibition of Hepatocellular Carcinoma via Blocking the Vascular Endothelial Growth Factor Pathway

Purpose

Vascular endothelial growth factor (VEGF) family members contribute greatly to the development and angiogenesis of hypervascular hepatocellular carcinoma (HCC). We have previously shown that Dicer inhibited HCC growth. In this study, we aimed to determine the relationship between Dicer and VEGF in HCC.

Methods

Gain-of-function studies were performed to determine the effect of different treatments on the proliferation, migration, and invasion of HCC cells. Expression of VEGF-A in xenograft tumor tissues was analysed using Western blotting, and that of CD31 using immunohistochemical analysis.

Results

We found that Dicer inhibited proliferation, migration and invasion of HCC cells by suppressing VEGF-A expression. Interestingly, VEGF-A165, which is the most prominent VEGF-A isoform, counteracted Dicer-induced inhibition of HCC cells. In addition, a monoclonal anti-VEGF antibody (bevacizumab) enhanced Dicer-induced inhibition of HCC in vitro and in vivo. Further, immunohistochemical analysis of CD31 indicated bevacizumab and Dicer synergized to reduce tumor microvessel density.

Conclusion

Our data demonstrated that Dicer enhanced bevacizumab-related inhibition of HCC cell via the VEGF pathway; therefore, Dicer in coordination with bevacizumab may provide another potential approach for HCC therapy.

Coagulation in Lymphatic System

The lymphatic system maintains homeostasis of the internal environment between the cells in tissues and the blood circulation. The coagulation state of lymph is determined by conditions of coagulation factors and lymphatic vessels. Internal obliteration, external compression or abnormally increased lymphatic pressure may predispose to localized lymphatic coagulation. In physiological conditions, an imbalance of antithrombin and thrombokinase reduces lymphatic thrombosis. However, the release of factor X by lymphatic endothelium injury may trigger coagulation casacade, causing blockage of lymphatic vessels and lymphedema. Heterogeneity of lymphatic vessels in various tissues may lead to distinct levels and patterns of coagulation in specific lymphatic vessels. The quantitative and qualitative measurement of clotting characteristic reveals longer time for clotting to occur in the lymph than in the blood. Cancer, infections, amyloidosis and lymph node dissection may trigger thrombosis in the lymphatic vessels. In contrast to venous or arterial thrombosis, lymphatic thrombosis has rarely been reported, and its actual prevalence is likely underestimated. In this review, we summarize the mechanisms of coagulation in lymphatic system, and discuss the lymphatic thrombosis-related diseases.

Serum VEGF-C as an evaluation marker of disease activity in adult-onset Still's disease

In view of the possible involvement of vascular endothelial growth factor-C (VEGF-C) in pathogenesis of adult-onset Still's disease (AOSD) based on our previous genome-wide association study (GWAS) results, the primary objective of this study, therefore, was to investigate the correlations between the content of VEGF-C in serum and clinical and biochemical markers of AOSD. Blood samples were collected from 80 patients with AOSD, 26 with rheumatoid arthritis (RA), 30 with systemic lupus erythematosus (SLE) and 31 healthy control subjects. The serum VEGF-C levels were determined using an enzyme-linked immunosorbent assay (ELISA). Statistical analysis and comparisons were conducted. A significantly higher serum VEGF-C level was observed in patients with AOSD than in HC. Serum VEGF-C levels had high AUC value of 0.8145 for distinguishing AOSD group from healthy group with sensitivity of 0.7097 and specificity of 0.8250. It also showed good diagnostic value to differentiate AOSD from other autoinflammatory diseases with sensitivity of 0.7500 and specificity of 0.5500. AOSD patients with fever, arthralgia, skin rash, sore throat, lymphadenopathy, splenomegaly hepatomegaly and pleuritis, had a higher level than those who did not have these symptoms (p = 0.0012, p = 0.0092, p = 0.0056, p = 0.0123, p = 0.0068, p = 0.0030, p = 0.0020, and p = 0.0018, respectively). The serum VEGF-C levels were also positively correlated with laboratory features and several cytokines related to AOSD disease activity. In conclusion, our study unveiled a close association between serum VEGF-C levels and AOSD including disease activity and clinical hematological manifestations, suggesting the potential utility of VEGF-C as a candidate biomarker to assess disease activity in AOSD.

IgA Vasculitis: Etiology, Treatment, Biomarkers and Epigenetic Changes

IgA, previously called Henoch-Schönlein vasculitis, is an essential immune component that drives the host immune response to the external environment. As IgA has the unique characteristic of a flexible response to broad types of microorganisms, it sometimes causes an autoreactive response in the host human body. IgA vasculitis and related organ dysfunction are representative IgA-mediated autoimmune diseases; bacterial and viral infections often trigger IgA vasculitis. Recent drug developments and the presence of COVID-19 have revealed that these agents can also trigger IgA vasculitis. These findings provide a novel understanding of the pathogenesis of IgA vasculitis. In this review, we focus on the characteristics of IgA and symptoms of IgA vasculitis and other organ dysfunction. We also mention the therapeutic approach, biomarkers, novel triggers for IgA vasculitis, and epigenetic modifications in patients with IgA vasculitis.

Snake venom vascular endothelial growth factors (svVEGFs): Unravelling their molecular structure, functions, and research potential

Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis, a physiological process characterized by the formation of new vessels from a preexisting endothelium. VEGF has also been implicated in pathologic states, such as neoplasias, intraocular neovascular disorders, among other conditions. VEGFs are distributed in seven different families: VEGF-A, B, C, D, and PIGF (placental growth factor), which are identified in mammals; VEGF-E, which are encountered in viruses; and VEGF-F or svVEGF (snake venom VEGF) described in snake venoms. This is the pioneer review of svVEGF family, exploring its distribution among the snake venoms, molecular structure, main functions, and potential applications.

Macrophage Biology and Mechanisms of Immune Suppression in Breast Cancer

Macrophages are crucial innate immune cells that maintain tissue homeostasis and defend against pathogens; however, their infiltration into tumors has been associated with adverse outcomes. Tumor-associated macrophages (TAMs) represent a significant component of the inflammatory infiltrate in breast tumors, and extensive infiltration of TAMs has been linked to poor prognosis in breast cancer. Here, we detail how TAMs impede a productive tumor immunity cycle by limiting antigen presentation and reducing activation of cytotoxic T lymphocytes (CTLs) while simultaneously supporting tumor cell survival, angiogenesis, and metastasis. There is an urgent need to overcome TAM-mediated immune suppression for durable anti-tumor immunity in breast cancer. To date, failure to fully characterize TAM biology and classify multiple subsets has hindered advancement in therapeutic targeting. In this regard, the complexity of TAMs has recently taken center stage owing to their subset diversity and tightly regulated molecular and metabolic phenotypes. In this review, we reveal major gaps in our knowledge of the functional and phenotypic characterization of TAM subsets associated with breast cancer, before and after treatment. Future work to characterize TAM subsets, location, and crosstalk with neighboring cells will be critical to counteract TAM pro-tumor functions and to identify novel TAM-modulating strategies and combinations that are likely to enhance current therapies and overcome chemo- and immuno-therapy resistance.

The Role of VEGF Receptors as Molecular Target in Nuclear Medicine for Cancer Diagnosis and Combination Therapy

Simple Summary

The rapid development of diagnostic and therapeutic methods of the cancer treatment causes that these diseases are becoming better known and the fight against them is more and more effective. Substantial contribution in this development has nuclear medicine that enables very early cancer diagnosis and early start of the so-called targeted therapy. This therapeutic concept compared to the currently used chemotherapy, causes much fewer undesirable side effects, due to targeting a specific lesion in the body. This review article discusses the possible applications of radionuclide-labelled tracers (peptides, antibodies or synthetic organic molecules) that can visualise cancer cells through pathological blood vessel system in close tumour microenvironment. Hence, at a very early step of oncological disease, targeted therapy can involve in tumour formation and growth.

Abstract

One approach to anticancer treatment is targeted anti-angiogenic therapy (AAT) based on prevention of blood vessel formation around the developing cancer cells. It is known that vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptors (VEGFRs) play a pivotal role in angiogenesis process; hence, application of angiogenesis inhibitors can be an effective approach in anticancer combination therapeutic strategies. Currently, several types of molecules have been utilised in targeted VEGF/VEGFR anticancer therapy, including human VEGF ligands themselves and their derivatives, anti-VEGF or anti-VEGFR monoclonal antibodies, VEGF binding peptides and small molecular inhibitors of VEGFR tyrosine kinases. These molecules labelled with diagnostic or therapeutic radionuclides can become, respectively, diagnostic or therapeutic receptor radiopharmaceuticals. In targeted anti-angiogenic therapy, diagnostic radioagents play a unique role, allowing the determination of the emerging tumour, to monitor the course of treatment, to predict the treatment outcomes and, first of all, to refer patients for AAT. This review provides an overview of design, synthesis and study of radiolabelled VEGF/VEGFR targeting and imaging agents to date. Additionally, we will briefly discuss their physicochemical properties and possible application in combination targeted radionuclide tumour therapy.

Protease-activated receptor 1 as a potential therapeutic target for COVID-19

Acute respiratory disease caused by a novel coronavirus (SARS-CoV-2) has spread all over the world, since its discovery in 2019, Wuhan, China. This disease is called COVID-19 and already killed over 1 million people worldwide. The clinical symptoms include fever, dry cough, dyspnea, headache, dizziness, generalized weakness, vomiting, and diarrhea. Unfortunately, so far, there is no validated vaccine, and its management consists mainly of supportive care. Venous thrombosis and pulmonary embolism are highly prevalent in patients suffering from severe COVID-19. In fact, a prothrombotic state seems to be present in most fatal cases of the disease. SARS-CoV-2 leads to the production of proinflammatory cytokines, causing immune-mediated tissue damage, disruption of the endothelial barrier, and uncontrolled thrombogenesis. Thrombin is the key regulator of coagulation and fibrin formation. In severe COVID-19, a dysfunctional of physiological anticoagulant mechanisms leads to a progressive increase of thrombin activity, which is associated with acute respiratory distress syndrome development and a poor prognosis. Protease-activated receptor type 1 (PAR1) is the main thrombin receptor and may represent an essential link between coagulation and inflammation in the pathophysiology of COVID-19. In this review, we discuss the potential role of PAR1 inhibition and regulation in COVID-19 treatment.

Growth factors in the fetus and pre-adolescent offspring of hyperglycemic rats

BACKGROUND

Maternal hyperglycemia influences childhood metabolic syndrome, including obesity and hyperglycemia. We tested the hypothesis that the maternal hyperglycemia influences growth factors in the fetal and pre-adolescent offspring.

METHODS

Hyperglycemia was induced in pregnant rats on embryonic day (E)16 using streptozocin followed by implantation with insulin or placebo pellets at embryonic day 18 (E18). Fetuses at E20 and pre-adolescent pups at postnatal day 14 (P14) were studied: (1) normal untreated controls (CTL) at E20; (2) hyperglycemic placebo-treated (HPT) at E20; (3) hyperglycemic insulin-treated (HIT) at E20; (4) CTL at P14; and (5) HIT at P14. Fetal and pre-adolescent growth factors were determined.

RESULTS

Biomarkers of hypoxia were elevated in the HPT group at E20. This group did not survive to term. Maternal insulin improved fetal survival despite lower fetal body weight at E20, however, at normal birth (postnatal day 0 (P0)) and at P14, body weights and blood glucose were higher than CTL. These high levels correlated with aberrant growth factors. Maternal hyperglycemia influenced glucose-6-phosphate dehydrogenase, glucagon, insulin, interleukin-10, and leptin genes.

CONCLUSIONS

The impact of maternal hyperglycemia on pre-adolescent glucose and body weight was not a consequence of maternal overnutrition. This suggests an independent link which may affect offspring metabolic health in later life.

The innate immune system in diabetic retinopathy

The prevalence of diabetes has been rising steadily in the past half-century, along with the burden of its associated complications, including diabetic retinopathy (DR). DR is currently the most common cause of vision loss in working-age adults in the United States. Historically, DR has been diagnosed and classified clinically based on what is visible by fundoscopy; that is vasculature alterations. However, recent technological advances have confirmed pathology of the neuroretina prior to any detectable vascular changes. These, coupled with molecular studies, and the positive impact of anti-inflammatory therapeutics in DR patients have highlighted the central involvement of the innate immune system. Reminiscent of the systemic impact of diabetes, immune dysregulation has become increasingly identified as a key element of the pathophysiology of DR by interfering with normal homeostatic systems. This review uses the growing body of literature across various model systems to demonstrate the clear involvement of all three pillars of the immune system: immune-competent cells, mediators, and the complement system. It also demonstrates how the relative contribution of each of these requires more extensive analysis, including in human tissues over the continuum of disease progression. Finally, although this review demonstrates how the complex interactions of the immune system pose many more questions than answers, the intimately connected nature of the three pillars of the immune system may also point to possible new targets to reverse or even halt reverse retinopathy.

Altered astrocytic function in experimental neuroinflammation and multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) that affects about 2.5 million people worldwide. In MS, the patients' immune system starts to attack the myelin sheath, leading to demyelination, neurodegeneration, and, ultimately, loss of vital neurological functions such as walking. There is currently no cure for MS and the available treatments only slow the initial phases of the disease. The later-disease mechanisms are poorly understood and do not directly correlate with the activity of immune system cells, the main target of the available treatments. Instead, evidence suggests that disease progression and disability are better correlated with the maintenance of a persistent low-grade inflammation inside the CNS, driven by local glial cells, like astrocytes and microglia. Depending on the context, astrocytes can (a) exacerbate inflammation or (b) promote immunosuppression and tissue repair. In this review, we will address the present knowledge that exists regarding the role of astrocytes in MS and experimental animal models of the disease.

Platelets and Metastasis: New Implications of an Old Interplay

During the process of hematogenous metastasis, tumor cells interact with platelets and their precursors megakaryocytes, providing a selection driver for the metastatic phenotype. Cancer cells have evolved a plethora of mechanisms to engage platelet activation and aggregation. Platelet coating of tumor cells in the blood stream promotes the successful completion of multiple steps of the metastatic cascade. Along the same lines, clinical evidence suggests that anti-coagulant therapy might be associated with reduced risk of metastatic disease and better prognosis in cancer patients. Here, we review experimental and clinical literature concerning the contribution of platelets and megakaryocytes to cancer metastasis and provide insights into the clinical relevance of anti-coagulant therapy in cancer treatment.

Gene-activated dermal equivalents to accelerate healing of diabetic chronic wounds by regulating inflammation and promoting angiogenesis

Diabetic chronic wound, characterized by prolonged inflammation and impaired angiogenesis, has become one of the most serious challenges in clinic and pose a significant healthcare burden worldwide. Although a great variety of wound dressings have been developed, few of encouraged achievements were obtained so far. In this study, the gene-activated strategy was applied to enhance sustained expression of vascular endothelial growth factor (VEGF) and achieve better healing outcomes by regulating inflammation and promoting angiogenesis. The gene-activated bilayer dermal equivalents (Ga-BDEs), which has good biocompatibility, were fabricated by loading the nano-sized complexes of Lipofectamine 2000/plasmid DNA-encoding VEGF into a collagen-chitosan scaffold/silicone membrane bilayer dermal equivalent. The DNA complexes were released in a sustained manner and showed the effective transfection capacities to up-regulate the expression of VEGF in vitro. To overcome cutaneous contraction of rodents and mimic the wound healing mechanisms of the human, a reformative rat model of full-thickness diabetic chronic wound was adopted. Under the treatment of Ga-BDEs, speeding wound healing was observed, which is accompanied by the accelerated infiltration and phenotype shift of macrophages and enhanced angiogenesis in early and late healing phases, respectively. These proved that Ga-BDEs possess the functions of immunomodulation and pro-angiogenesis simultaneously. Subsequently, the better regeneration outcomes, including deposition of oriented collagen and fast reepithelialization, were achieved. All these results indicated that, being different from traditional pro-angiogenic concept, the up-regulated expression of VEGF by Ga-BDEs in a sustained manner shows versatile potentials for promoting the healing of diabetic chronic wounds.

Mast cells and angiogenesis in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease, characterized by multiple demyelination of axons in both white and gray matter in the Central Nervous System (CNS). There is increasing evidence to support the notion that angiogenesis and chronic inflammation are mutually related. Different immune cells, including monocytes-macrophages, lymphocytes, neutrophils, mast cells (MCs) and dendritic cells are able to secrete an array of angiogenic cytokines, which promote growth, migration, and activation of endothelial cells. MCs play various roles in MS pathogenesis, influencing the innate immune response in peripheral tissues and in CNS. The aim of this review article is to discuss the role of MCs in MS pathogenesis with particular reference to the involvement of these inflammatory cells in the angiogenic processes occurring during MS.

The in vitro effect of VEGF receptor inhibition on primary alveolar osteoblast nodule formation

BACKGROUND

Vascular endothelial growth factor (VEGF) is a master regulator and is required for the effective coupling of angiogenesis and osteogenesis supporting both skeletal development and postnatal bone repair. A direct role for VEGF in intramembranous-derived osteoblast growth and differentiation is not clear. We investigated the expression of primary alveolar osteoblast VEGF receptors and the subsequent effects on mineralization and nodule formation in vitro following VEGFR inhibition.

METHODS

Primary human alveolar osteoblasts (HAOBs) were cultured in the presence of VEGF receptor inhibitors, exogenous VEGF or the bisphosphonate, zoledronic acid. VEGF, VEGFR1 and VEGFR2 mRNA expression and nodule formation following 21 days of culture. VEGFR1 protein expression was examined using immunofluorescence after 48 h.

RESULTS

The HAOBs expressed high levels of VEGF and VEGFR1 protein but VEGFR2 was not detected. The VEGFR1/2 inhibitors, ZM306416 and KRN633, lead to a dose-dependent decrease in mineralization. Treatment with zoledronic acid showed no difference in HAOB VEGF receptor expression.

CONCLUSION

VEGF/VEGFR1 pathway appears to be important for intramembranous-derived osteoblast differentiation and maturation in vitro.

Bi-layer blood vessel mimicking microfluidic platform for antitumor drug screening based on co-culturing 3D tumor spheroids and endothelial layers

Two-dimensional (2D) cell culture is not ideal for traditional drug screening, because 2D culture does not accurately mimic the physiological microenvironment of tumor cells. Thus, a drug-screening system which more closely mimics the microenvironment of in vivo tumors is necessary. Here, we present a biomimicking bilayer microfluidic device that can facilitate antitumor drug screening. The microfluidic device consists of two polydimethylsiloxane (PDMS) pieces with channels which are separated by a semipermeable membrane to allow water, oxygen, and nutrition supply, while preventing cell migration. The channels embedded on the two PDMS pieces overlap each other over a long distance to ensure a larger exchange area to mimic the blood vessel-tumor model. High concentrations of endothelial cells (EC) are first seeded onto the membrane through the apical channel, and after a two-day culture, a confluent EC monolayer forms. Tumor spheroid-laden Matrigel is then seeded into the basal channel. After the Matrigel is cured, the device is ready for drug testing. Paclitaxel is used as the model drug for testing. Confocal microscopy and ImageJ are used to assess the efficacy of different concentrations of paclitaxel, and optical coherence tomography (OCT) is employed to determine the tumor volumetric change after the drug treatment. The results indicate that the proposed bilayer microfluidic device in combination with confocal and OCT optical characterization provide an efficient platform for antitumor drug testing.

Maternal Flt-1 and endoglin expression by circulating monocyte subtype and polarization in preeclampsia and fetal growth restriction

Objective

Circulating levels of the anti-angiogenic factors sFlt-1 and sEndoglin are elevated in preeclampsia (PE) and fetal growth restriction (FGR), mainly secreted from placental trophoblast. This study aims to identify the contributory role of monocyte Flt-1 and endoglin expression in PE and FGR.

Study design

A prospective cross-sectional study was conducted and patients recruited from four clinical groups including normal pregnancy, PE, FGR and PE + FGR. Peripheral blood samples and cord blood were collected from 54 pregnant women between 24–40 weeks of gestation. Monocyte subset distribution was assessed using CD14 and CD16 expression and the surface expression of Flt-1, endoglin, CD86 and CD163 assessed by flow cytometry. We compared these factors between (1) clinical groups. (2) monocyte subset (3) monocyte polarization and (4) gestational age.

Results

Across all clinical groups, Flt-1 was mainly expressed by classical and intermediate monocytes, but no differences between clinical groups were observed. Surface expression of endoglin was higher on intermediate and non-classical monocytes and decreased in PE + FGR total monocytes. Flt-1 and endoglin expression correlated with increasing gestational age as well as higher CD86/CD163 ratio favouring M1 polarisation. The fetal monocyte endoglin expression was increased in FGR.

Conclusion

We conclude that monocyte Flt-1 and endoglin expression increase with gestational age and with M1 polarization suggesting their upregulation with inflammatory changes in monocytes. Endoglin expression by M1 monocytes may play a part in increased cardiovascular risk associated with preeclampsia. Endoglin expression on fetal monocytes is increased in FGR as a likely response to placental injury.

Biomarkers of Endothelial Dysfunction in Women With Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of childbearing age. The criteria required for the diagnosis identify various phenotypes, with different reproductive, metabolic, and cardiovascular (CV) risk characteristics. Emerging evidence links adipocyte-secreted hormones as candidates in the pathogenesis of endothelial dysfunction in PCOS, independently of additional risk factors. The aim of this review was to collect, analyze, and qualitatively resynthesize evidence on biomarkers of endothelial dysfunction (visfatin, vascular endothelial growth factor [VEGF], matrix metalloproteinase 9 [MMP-9]) in women with PCOS. Women with PCOS exhibit (a) increased plasma visfatin concentrations compared with controls with a similar body mass index; (b) increased VEGF production along with chronic, mild inflammation; and (c) increased MMP-9 concentrations, which might be related to either excessive CV risk or abnormalities of ovarian extracellular matrix remodeling, multiple cyst formation, follicular atresia, and chronic anovulation. As PCOS has been associated with CV risk, early identification of endothelial dysfunction is clinically relevant.

Vascular Endothelial Growth Factor, from Basic Research to Clinical Applications

Judah Folkman's landmark discovery in the 1970s showing that tumors, growing beyond a few millimeters in diameter, depend on de novo vascularization triggered by specific growth factors released by tumor cells encountering hypoxia [...].

Cancer-Associated Thrombosis: An Overview of Mechanisms, Risk Factors, and Treatment

Cancer-associated thrombosis is a major cause of mortality in cancer patients, the most common type being venous thromboembolism (VTE). Several risk factors for developing VTE also coexist with cancer patients, such as chemotherapy and immobilisation, contributing to the increased risk cancer patients have of developing VTE compared with non-cancer patients. Cancer cells are capable of activating the coagulation cascade and other prothrombotic properties of host cells, and many anticancer treatments themselves are being described as additional mechanisms for promoting VTE. This review will give an overview of the main thrombotic complications in cancer patients and outline the risk factors for cancer patients developing cancer-associated thrombosis, focusing on VTE as it is the most common complication observed in cancer patients. The multiple mechanisms involved in cancer-associated thrombosis, including the role of anticancer drugs, and a brief outline of the current treatment for cancer-associated thrombosis will also be discussed.

Stromal vascular fraction cells plus sustained release VEGF/Ang-1-PLGA microspheres improve fat graft survival in mice

Autologous fat transplantation is increasingly applied in plastic and reconstructive surgery. Stromal vascular fraction cells (SVFs) combined with angiogenic factors, such as VEGF (vascular endothelial growth factor A) and Ang-1 (angiogenin-1), can improve angiogenesis, which is a critical factor for graft survival. However, direct transplant with such a mixture is insufficient owing to the short half-life of angiogenic factors. In this study, we evaluated whether a double sustained release system of VEGF/ANG-1-PLGA (poly (lactic-co-glycolic acid)) microspheres plus SVFs can improve angiogenesis and graft survival after autologous fat transplantation. VEGF/ANG-1-PLGA-sustained release microspheres were fabricated by a modified double emulsion-solvent evaporation technique. Human aspirated fat was mixed with SVF suspension plus VEGF/ANG-1 sustained release microspheres (Group C), SVF suspension (Group B) alone, or Dulbecco's modified Eagle's medium as the control (Group A). Eighteen immunocompromised nude mice were injected with these three mixtures subcutaneously at random positions. After 8 weeks, the mean volume of grafts was greater in the SVFs plus VEGF/ANG-1-PLGA group than in the control and SVFs groups (1.08 ± 0.069 ml vs. 0.62 ± 0.036 ml, and 0.83 ± 0.059 ml, respectively). Histological assessments showed that lower fibrosis, but greater microvascular density in the SVFs plus VEGF/ANG-1-PLGA group than in the other groups, though the SVFs group also had an appropriate capillary density and reduced fibrosis. Our findings indicate that SVFs plus VEGF/ANG-1-PLGA-sustained release microspheres can improve angiogenesis and graft survival after autologous fat transplantation.

Microvascular permeability of skeletal muscle after eccentric contraction-induced muscle injury: in vivo imaging using two-photon laser scanning microscopy

Via modulation of endothelial integrity and vascular permeability in response to damage, skeletal muscle microvessels play a crucial permissive role in tissue leukocyte invasion. However, direct visual evidence of altered microvascular permeability of skeletal muscle has not been technically feasible, impairing mechanistic understanding of these responses. Two-photon laser scanning microscopy (TPLSM) allows three-dimensional in vivo imaging of skeletal muscle microcirculation. We hypothesized that the regulation of microvascular permeability in vivo is temporally related to acute inflammatory and regenerative processes following muscle injury. To test our hypothesis, tibialis anterior muscles of anesthetized male Wistar rats were subjected to eccentric contractions (ECCs) via electrical stimulation. The skeletal muscle microcirculation was imaged by an intravenously infused fluorescent dye (rhodamine B isothiocyanate-dextran) to assess microvascular permeability via TPLSM 1, 3, and 7 days after ECC. Immunohistochemistry on serial muscle sections was performed to determine the proportion of VEGF-A-positive muscle fibers in the damaged muscle. Compared with control rats, the volumetrically determined interstitial leakage of fluorescent dye (5.1 ± 1.4, 5.3 ± 1.2 vs. 0.51 ± 0.14 μm3 × 106; P < 0.05, days 1 and 3, respectively, vs. control) and percentage of VEGF-A-positive fibers in the damaged muscle (10 ± 0.4%, 22 ± 1.1% vs. 0%; days 1 and 3, respectively, vs. control) were significantly higher on days 1 and 3 after ECC. The interstitial leakage volume returned to control by day 7. These results suggest that microvascular hyperpermeability assessed by in vivo TPLSM imaging is associated with ECC-induced muscle damage and increased VEGF expression.

NEW & NOTEWORTHY This investigation employed a novel in vivo imaging technique for skeletal muscle microcirculation using two-photon laser scanning microscopy that enabled microvascular permeability to be assessed by four-dimensional image analysis. By combining in vivo imaging and histological analysis, we found the temporal profile of microvascular hyperpermeability to be related to that of eccentric contraction-induced skeletal muscle injury and pronounced novel myocyte VEGF expression.

Mosquito saliva alone has profound effects on the human immune system

Mosquito saliva is a very complex concoction of >100 proteins, many of which have unknown functions. The effects of mosquito saliva proteins injected into our skin during blood feeding have been studied mainly in mouse models of injection or biting, with many of these systems producing results that may not be relevant to human disease. Here, we describe the numerous effects that mosquito bites have on human immune cells in mice engrafted with human hematopoietic stem cells. We used flow cytometry and multiplex cytokine bead array assays, with detailed statistical analyses, to detect small but significant variations in immune cell functions after 4 mosquitoes fed on humanized mice footpads. After preliminary analyses, at different early times after biting, we focused on assessing innate immune and subsequent cellular responses at 6 hours, 24 hours and 7 days after mosquito bites. We detected both Th1 and Th2 human immune responses, and delayed effects on cytokine levels in the blood, and immune cell compositions in the skin and bone marrow, up to 7 days post-bites. These are the first measurements of this kind, with human immune responses in whole animals, bitten by living mosquitoes, versus previous studies using incomplete mouse models and salivary gland extracts or needle injected saliva. The results have major implications for the study of hematophagous insect saliva, its effects on the human immune system, with or without pathogen transmission, and the possibility of determining which of these proteins to target for vaccination, in attempts to block transmission of numerous tropical diseases.

Platelets and cancer angiogenesis nexus

There has been remarkable insight into the importance of platelets in a wide range of pathophysiologic events, including inflammation and cancer progression. Thrombocytosis in cancer patients is a common finding. Tumor cells induce platelet activation and subsequent aggregation through direct and indirect mechanisms. Platelets are recognized to contribute to metastatic dissemination. There is plenty of evidence that components of the hemostatic system contribute to the process of angiogenesis. Furthermore, there are accumulated data on the substantial influence of blood platelets in the process of blood vessel formation during malignancy. Platelets appear to be the main physiologic transporters of proangiogenic and antiangiogenic factors. Moreover, they influence the process of angiogenesis through platelet-derived microparticles, microRNA, lipids, and variety of surface receptors. Platelets contribute to early and late stages of angiogenesis. Available data support the overall stimulatory effect of platelets on tumor angiogenesis. It raises the possibility that interfering with platelet function may be an effective antineoplastic treatment strategy.

Angiogenic factor-driven inflammation promotes extravasation of human proangiogenic monocytes to tumours

Recruitment of circulating monocytes is critical for tumour angiogenesis. However, how human monocyte subpopulations extravasate to tumours is unclear. Here we show mechanisms of extravasation of human CD14^dimCD16⁺ patrolling and CD14⁺CD16⁺ intermediate proangiogenic monocytes (HPMo), using human tumour xenograft models and live imaging of transmigration. IFNγ promotes an increase of the chemokine CX3CL1 on vessel lumen, imposing continuous crawling to HPMo and making these monocytes insensitive to chemokines required for their extravasation. Expression of the angiogenic factor VEGF and the inflammatory cytokine TNF by tumour cells enables HPMo extravasation by inducing GATA3-mediated repression of CX3CL1 expression. Recruited HPMo boosts angiogenesis by secreting MMP9 leading to release of matrix-bound VEGF-A, which amplifies the entry of more HPMo into tumours. Uncovering the extravasation cascade of HPMo sets the stage for future tumour therapies.

Circulating myeloid cells can leave the vasculature to infiltrate tumours and are thought to contribute to tumour angiogenesis. Here the authors live image monocytes that migrate to xenograft tumours and map an extravasation cascade of human proangiogenic monocytes into the tumour.

PAR1 agonists stimulate APC-like endothelial cytoprotection and confer resistance to thromboinflammatory injury

Stimulation of protease-activated receptor 1 (PAR1) on endothelium by activated protein C (APC) is protective in several animal models of disease, and APC has been used clinically in severe sepsis and wound healing. Clinical use of APC, however, is limited by its immunogenicity and its anticoagulant activity. We show that a class of small molecules termed "parmodulins" that act at the cytosolic face of PAR1 stimulates APC-like cytoprotective signaling in endothelium. Parmodulins block thrombin generation in response to inflammatory mediators and inhibit platelet accumulation on endothelium cultured under flow. Evaluation of the antithrombotic mechanism showed that parmodulins induce cytoprotective signaling through Gβγ, activating a PI3K/Akt pathway and eliciting a genetic program that includes suppression of NF-κB-mediated transcriptional activation and up-regulation of select cytoprotective transcripts. STC1 is among the up-regulated transcripts, and knockdown of stanniocalin-1 blocks the protective effects of both parmodulins and APC. Induction of this signaling pathway in vivo protects against thromboinflammatory injury in blood vessels. Small-molecule activation of endothelial cytoprotection through PAR1 represents an approach for treatment of thromboinflammatory disease and provides proof-of-principle for the strategy of targeting the cytoplasmic surface of GPCRs to achieve pathway selective signaling.

Negative Regulators of Angiogenesis, Ocular Vascular Homeostasis, and Pathogenesis and Treatment of Exudative AMD

Angiogenesis, the formation of new blood vessels from pre-existing capillaries, is very tightly regulated and normally does not occur except during developmental and reparative processes. This tight regulation is maintained by a balanced production of positive and negative regulators, and alterations under pathological conditions such as retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration can lead to growth of new and abnormal blood vessels. Although the role of proangiogenic factors such as vascular endothelial growth factor has been extensively studied, little is known about the roles of negative regulators of angiogenesis in the pathogenesis of these diseases. Here, we will discuss the role of thrombospondin-1 (TSP1), one of the first known endogenous inhibitors of angiogenesis, in ocular vascular homeostasis, and how its alterations may contribute to the pathogenesis of age-related macular degeneration and choroidal neovascularization. We will also discuss its potential utility as a therapeutic target for treatment of ocular diseases with a neovascular component.

Balance between angiogenic and anti-angiogenic isoforms of VEGF-A is associated with the complexity and severity of coronary artery disease

INTRODUCTION

Assessing the complexity of coronary artery disease (CAD) is clinically important. Vascular endothelial growth factor A (VEGF-A) is a powerful and the most important regulator of angiogenesis. It has been reported that the anti-angiogenic isoform of VEGF-A (VEGF-A₁₆₅b) inhibits angiogenesis. The purpose of this study was to evaluate the relationship between the complexities of CAD using the Syntax score (SS) and the levels of circulating total VEGF-A or VEGF-A₁₆₅b.

METHODS

A total of 268 patients who underwent percutaneous coronary intervention (PCI) were enrolled. Of these, 73 patients without acute coronary syndrome or previous revascularization were included in this study. These subjects were divided into two groups according to the SS. Circulating total VEGF-A and VEGF-A₁₆₅b levels were measured using an enzyme-linked immunosorbent assay.

RESULTS

Circulating levels of total VEGF-A were significantly higher in the SS>22 (high SS) group than in the SS≤22 (low SS) group (p=0.018). Moreover, the ratio of VEGF-A₁₆₅b to total VEGF-A was significantly lower for the high SS group (p=0.004). The levels of total VEGF-A independently predicted high SS after adjusting for other significant variables among patients who underwent PCI (odds ratio, 1.004; 95% CI, 1.001 to 1.006; p=0.01).

CONCLUSIONS

These data indicated that high SS was associated with circulating levels of total VEGF-A and the ratio of VEGF-A₁₆₅b to total VEGF-A in patients with complex CAD.

Hypoxia Modulates Epithelial Permeability via Regulation of Vascular Endothelial Growth Factor in Airway Epithelia

Hypoxia resulting from occlusion of the sinus ostium is known to be one of the major pathogenic mechanisms of sinusitis. Hypoxia-inducible factor (HIF)-1 is a widely known transcription factor that induces the cellular response to hypoxic conditions and activates the transcription of several genes, including vascular endothelial growth factor (VEGF). We hypothesized that induced permeability caused by hypoxia is a major pathophysiologic mechanism of upper airway diseases, such as sinusitis. The aim of this study was to investigate the mechanism of hypoxia-induced hyperpermeability, which mediates increased paracellular permeability and enhanced microbial invasiveness in the airway epithelium. We show that expression of VEGF mRNA and protein and HIF-1α protein increased as a function of time under hypoxia in normal human nasal epithelial cells. Our results also indicate that VEGF expression was induced by transfection with a mammalian expression vector encoding HIF-1 but down-regulated by transfection with small interfering RNA specific for HIF-1α under hypoxic conditions. Results of a transepithelial permeability assay measuring transepithelial electrical resistance indicated that permeability was increased as a function of time under hypoxia and was rescued by anti-VEGF monoclonal antibody (bevacizumab) and small interfering RNA specific for HIF-1α. We detected up-regulated HIF-1α and VEGF expression in mucosal epithelium samples from patients with sinusitis compared with normal mucosal epithelium using Western blotting and immunohistochemical staining. In conclusion, we suggest that the hypoxia-HIF-1α-VEGF axis plays an important role in hyperpermeability of airway epithelial cells, implying a role in the pathophysiology of upper respiratory tract diseases, such as sinusitis.

Accumulation of tissue factor in endothelial cells induces cell apoptosis, mediated through p38 and p53 activation

We previously reported that high levels of tissue factor (TF) can induce cellular apoptosis in endothelial cells. In this study, TF-mediated mechanisms of induction of apoptosis were explored. Endothelial cells were transfected to express wild-type TF. Additionally, cells were transfected to express Asp253-substituted, or Ala253-substitued TF to enhance or prevent TF release, respectively. Alternatively, cells were pre-incubated with TF-rich and TF-poor microvesicles. Cell proliferation, apoptosis and the expression of cyclin D1, p53, bax and p21 were measured following activation of cells with PAR2-agonist peptide. Greatest levels of cell proliferation and cyclin D1 expression were observed in cells expressing wild-type or Asp253-substituted TF. In contrast, increased cellular apoptosis was observed in cells expressing Ala253-substituted TF, or cells pre-incubated with TF-rich microvesicles. The level of p53 protein, p53-phosphorylation at ser33, p53 nuclear localisation and transcriptional activity, but not p53 mRNA, were increased in cells expressing wild-type and Ala253-substituted TF, or in cells pre-incubated with TF-rich microvesicles. However, the expression of bax and p21 mRNA, and Bax protein were only increased in cells pre-incubated with TF-rich microvesicle and in cells expressing Ala253-substituted TF. Inhibition of the transcriptional activity of p53 using pifithrin-α suppressed the expression of Bax. Finally, siRNA- mediated suppression of p38α, or inhibition using SB202190 significantly reduced the p53 protein levels, p53 nuclear localisation and transcriptional activity, suppressed Bax expression and prevented cellular apoptosis. In conclusion, accumulation of TF within endothelial cells, or sequestered from the surrounding can induce cellular apoptosis through mechanisms mediated by p38, and involves the stabilisation of p53.

In Vitro Effects of High-Intensity Laser Photobiomodulation on Equine Bone Marrow-Derived Mesenchymal Stem Cell Viability and Cytokine Expression

OBJECTIVE

This study aimed to examine the influence of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser irradiation on equine bone marrow-derived mesenchymal stem cell (MSC) viability, proliferation, and cytokine expression in vitro.

BACKGROUND

Photobiomodulation of cells using monochromatic light is a technique designed to influence cellular processes. Previous studies have shown dose-dependent effects of low-level laser irradiation on cell proliferation and cytokine expression in a range of cell types and species. Evidence for the influence of 1064 nm wavelength near-infrared irradiation on MSCs is sparse, and high-energy doses have shown inhibitory effects.

METHODS

MSC cultures from six horses were exposed to 1064 nm irradiation with an energy density of 9.77 J/cm² and a mean output power of 13.0 W for 10 sec. MSC viability and proliferation were evaluated through flow cytometry and real-time live cell analysis. Gene expression and cytokine production in the first 24 h after irradiation were analyzed through polymerase chain reaction (PCR), multiplex assay, and enzyme-linked immunosorbent assay.

RESULTS

No difference in viability was detected between irradiated and control MSCs. Irradiated cells demonstrated slightly lower proliferation rates, but remained within 3.5% confluence of control cells. Twenty-four hours after irradiation, irradiated MSCs demonstrated a significant increase in expression of interleukin (IL)-10 and vascular endothelial growth factor (VEGF) compared with control MSCs.

CONCLUSIONS

Under these irradiation parameters, equine MSCs remained viable and expressed increased concentrations of IL-10 and VEGF. IL-10 has an anti-inflammatory action by inhibiting the synthesis of proinflammatory cytokines at the transcriptional level. This response to 1064 nm irradiation shows promise in the photobiomodulation of MSCs to enhance their therapeutic properties.

Irradiated VEGF164-modified tumor cell vaccine protected mice from the parental tumor challenge

Vascular endothelial growth factor (VEGF) is an important regulating molecule of angiogenesis in tumor formation and progression. Cancer cells always secrete VEGF to stimulate angiogenesis that facilitate growth and invasion of the tumor. In this study, we established a VEGF164 overexpressing LL/2 lung cancer cell model and found that the postirradiated VEGF164-modified tumor cells protected the host against the challenge with LL/2 wild-type tumor cells. Histochemical assay showed that there were large areas of tumor necrosis with macrophage infiltration in the mice vaccinated with the VEGF164-modified tumor vaccine. T-cells isolated from the vaccinated mice showed cytotoxicity against the parental tumor cells in a dose-dependent manner. Meanwhile, sera from the mice vaccinated with LL/2-VEGF164 showed higher titers of antibodies against parental tumor cells compared with the nonvaccinated groups. Our results indicated that VEGF164-modified tumor vaccine could modulate host antitumor immune response and hold therapeutic potential for cancer.

Myeloid cells contribute indirectly to VEGF expression upon hypoxia via activation of Müller cells

Anti-VEGF-directed therapies have been a milestone for treating retinal vascular diseases. Depletion of monocyte lineage cells suppresses pathological neovascularization in the oxygen-induced retinopathy mouse model. However, the question whether myeloid-derived VEGF-A expression is responsible for the pathogenesis in oxygen-induced retinopathy remained unknown. We analyzed LysMCre-driven myeloid cell-specific VEGF-A knockout mice as well as mice with complete depletion of circulating macrophages through clodronate-liposome treatment in the oxygen-induced retinopathy model by immunohistochemistry, qPCR, and flow cytometry. Furthermore, we analyzed VEGF-A mRNA expression in MIO-M1 cells alone and in co-culture with BV-2 cells in vitro. The myeloid cell-specific VEGF-A knockout did not change relative retinal VEGF-A mRNA levels, the relative avascular area or macrophage/granulocyte numbers in oxygen-induced retinopathy and under normoxic conditions. We observed an insignificantly attenuated pathology in systemically clodronate-liposome treated knockouts but evident VEGF-A expression in activated Müller cells on immunohistochemically stained sections. MIO-M1 cells had significantly higher expression levels of VEGF-A in co-culture with BV-2 cells compared to cultivating MIO-M1 cells alone. Our data show that myeloid-derived cells contribute to pathological neovascularization in oxygen-induced retinopathy through activation of VEGF-A expression in Müller cells.

The VEGF-A inhibitor sFLT-1 improves renal function by reducing endothelial activation and inflammation in a mouse model of type 1 diabetes

AIMS/HYPOTHESIS

Animal models of diabetic nephropathy show increased levels of glomerular vascular endothelial growth factor (VEGF)-A, and several studies have shown that inhibiting VEGF-A in animal models of diabetes can prevent albuminuria and glomerular hypertrophy. However, in those studies, treatment was initiated before the onset of kidney damage. Therefore, the aim of this study was to investigate whether transfecting mice with the VEGF-A inhibitor sFlt-1 (encoding soluble fms-related tyrosine kinase 1) can reverse pre-existing kidney damage in a mouse model of type 1 diabetes. In addition, we investigated whether transfection with sFlt-1 can reduce endothelial activation and inflammation in these mice.

METHODS

Subgroups of untreated 8-week-old female C57BL/6J control (n = 5) and diabetic mice (n = 7) were euthanised 5 weeks after the start of the experiment in order to determine the degree of kidney damage prior to treatment with sFLT-1. Diabetes was induced with three i.p. injections of streptozotocin (75 mg/kg) administered at 2 day intervals. Diabetic nephropathy was then investigated in diabetic mice transfected with sFlt-1 (n = 6); non-diabetic, non-transfected control mice (n = 5); non-diabetic control mice transfected with sFlt-1(n = 10); and non-transfected diabetic mice (n = 6). These mice were euthanised at the end of week 15. Transfection with sFlt-1 was performed in week 6.

RESULTS

We found that transfection with sFlt-1 significantly reduced kidney damage by normalising albuminuria, glomerular hypertrophy and mesangial matrix content (i.e. glomerular collagen type IV protein levels) (p < 0.001). We also found that transfection with sFlt-1 reduced endothelial activation (p < 0.001), glomerular macrophage infiltration (p < 0.001) and glomerular TNF-α protein levels (p < 0.001). Finally, sFLT-1 decreased VEGF-A-induced endothelial activation in vitro (p < 0.001).

CONCLUSIONS/INTERPRETATION

These results suggest that sFLT-1 might be beneficial in treating diabetic nephropathy by inhibiting VEGF-A, thereby reducing endothelial activation and glomerular inflammation, and ultimately reversing kidney damage.

Limb ischemia and vessel regeneration: Is there a role for VEGF?

Vascular endothelial growth factor (VEGF), as an endothelial cell-specific mitogen, is crucial for new blood vessels formation. Atherosclerosis affecting the cardiovascular system causes ischemia and functio laesa in tissues supplied by the occluded vessels. When such a situation occurs in the lower extremities, it causes critical limb ischemia (CLI) often requiring leg amputation. Low oxygen tension leads to upregulation of hypoxia-regulated genes (i.e. VEGF), that should help to restore the impaired blood flow. In CLI these rescue mechanisms are, however, often inefficient. Moreover, there are many contradictory reports showing either induction, no changes or even down-regulation of VEGF in specimens taken from patients with CLI, as well as in samples collected from animals subjected to hindlimb ischemia. Additionally, taking into account numerous experimental and clinical data demonstrating rather insufficient therapeutic potential of VEGF, we called into question the role of this protein in limb ischemia and vessel regeneration. In this review we are also summarizing several aspects which can influence VEGF expression and its measurement in the ischemic tissues.

Role of Vascular Endothelial Growth Factor–A in Recurrent Respiratory Papillomatosis

Vascular endothelial growth factor–A (VEGF-A) is known to play an important role in the angiogenic response essential for tumor growth in a variety of human and experimental tumors. This study was designed to investigate whether VEGF-A may play a role in the pathogenesis of recurrent respiratory papillomatosis (RRP). A retrospective study with institutional review board approval was performed at a tertiary care medical center on 12 patients with a history of laryngeal RRP. Their ages at the time of initial diagnosis ranged from 19 to 96 months (mean, 56 months). All patients had involvement of right and left true vocal cords. All patients required multiple endoscopic procedures (range, 4 to 66; mean, 12). Normal pediatric larynx samples from 5 autopsy patients were used as controls. Formalin-fixed, paraffin-embedded sections of laryngeal squamous papillomas from the 12 patients with a diagnosis of RRP and the 5 control patients were examined by in situ hybridization for the presence of messenger RNA (mRNA) for VEGF-A and vascular endothelial growth factor receptor 1 (VEGFR-1) and vascular endothelial growth factor receptor 2 (VEGFR-2). The biopsy specimens were from the true vocal cord (N = 10) or subglottis (N = 2) in the patients with RRP and consisted of large sections of larynx including the true vocal cord in the control patients (N = 5). Strong expression of VEGF-A mRNA was noted in the squamous epithelium of papillomas of all 12 patients. Strong expression of VEGFR-1 and VEGFR-2 was noted in the endothelial cells of the underlying vessels in all 12 patients. Neither strong labeling of VEGF-A mRNA nor labeling of its receptors was noted in the control patients. We conclude that the angiogenic growth factor VEGF-A is strongly expressed in the epithelium of squamous papillomas in RRP. Also, VEGFR-1 and VEGFR-2 mRNAs are strongly expressed by underlying vascular endothelial cells, suggesting an important role in the pathogenesis of RRP.