Vascular endothelial growth factor receptor-1 (VEGFR-1) signaling enhances angiogenesis in a surgical sponge model

Acute exposure to artificial light at night alters hippocampal vascular structure in mice

The structure and function of the cardiovascular system are modulated across the day by circadian rhythms, making this system susceptible to circadian rhythm disruption. Recent evidence demonstrated that short-term exposure to a pervasive circadian rhythm disruptor, artificial light at night (ALAN), increased inflammation and altered angiogenic transcripts in the hippocampi of mice. Here, we examined the effects of four nights of ALAN exposure on mouse hippocampal vascular networks. To do this, we analyzed 2D and 3D images of hippocampal vasculature and hippocampal transcriptomic profiles of mice exposed to ALAN. ALAN reduced vascular density in the CA1 and CA2/3 of female mice and the dentate gyrus of male mice. Network structure and connectivity were also impaired in the CA2/3 of female mice. These results demonstrate the rapid and potent effects of ALAN on cerebrovascular networks, highlighting the importance of ALAN mitigation in the context of health and cerebrovascular disease.

Genetics Responses to Hypoxia and Reoxygenation Stress in Larimichthys crocea Revealed via Transcriptome Analysis and Weighted Gene Co-Expression Network

Simple Summary

Hypoxia, which occurs frequently in aquaculture, can cause serious harm to all aspects of the growth, reproduction and metabolism of cultured fish. Due to the intolerance of Larimichthys crocea to hypoxia, Larimichthys crocea often floats head or even dies under hypoxic environment. However, the molecular mechanism of hypoxia tolerance in Larimichthys crocea has not been fully described. Therefore, the aim of this study was to explore the hub regulatory genes under hypoxic stress environment by transcriptome analysis of three key tissues (liver, blood and gill) in Larimichthys crocea. We identified a number of important genes that exercise different regulatory functions. Overall, this study will provide important clues to the molecular mechanisms of hypoxia tolerance in Larimichthys crocea.

Abstract

The large yellow croaker (Larimichthys crocea) is an important marine economic fish in China; however, its intolerance to hypoxia causes widespread mortality. To understand the molecular mechanisms underlying hypoxia tolerance in L. crocea, the transcriptome gene expression profiling of three different tissues (blood, gills, and liver) of L. crocea exposed to hypoxia and reoxygenation stress were performed. In parallel, the gene relationships were investigated based on weighted gene co-expression network analysis (WGCNA). Accordingly, the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed that several pathways (e.g., energy metabolism, signal transduction, oxygen transport, and osmotic regulation) may be involved in the response of L. crocea to hypoxia and reoxygenation stress. In addition, also, four key modules (darkorange, magenta, saddlebrown, and darkolivegreen) that were highly relevant to the samples were identified by WGCNA. Furthermore, some hub genes within the association module, including RPS16, EDRF1, KCNK5, SNAT2, PFKL, GSK-3β, and PIK3CD, were found. This is the first study to report the co-expression patterns of a gene network after hypoxia stress in marine fish. The results provide new clues for further research on the molecular mechanisms underlying hypoxia tolerance in L. crocea.

Extracellular Granzyme K Modulates Angiogenesis by Regulating Soluble VEGFR1 Release From Endothelial Cells

Angiogenesis is crucial for normal development and homeostasis, but also plays a role in many diseases including cardiovascular diseases, autoimmune diseases, and cancer. Granzymes are serine proteases stored in the granules of cytotoxic cells, and have predominantly been studied for their pro-apoptotic role upon delivery in target cells. A growing body of evidence is emerging that granzymes also display extracellular functions, which largely remain unknown. In the present study, we show that extracellular granzyme K (GrK) inhibits angiogenesis and triggers endothelial cells to release soluble VEGFR1 (sVEGFR1), a decoy receptor that inhibits angiogenesis by sequestering VEGF-A. GrK does not cleave off membrane-bound VEGFR1 from the cell surface, does not release potential sVEGFR1 storage pools from endothelial cells, and does not trigger sVEGFR1 release via protease activating receptor-1 (PAR-1) activation. GrK induces de novo sVEGFR1 mRNA and protein expression and subsequent release of sVEGFR1 from endothelial cells. GrK protein is detectable in human colorectal tumor tissue and its levels positively correlate with sVEGFR1 protein levels and negatively correlate with T4 intratumoral angiogenesis and tumor size. In conclusion, extracellular GrK can inhibit angiogenesis via secretion of sVEGFR1 from endothelial cells, thereby sequestering VEGF-A and impairing VEGFR signaling. Our observation that GrK positively correlates with sVEGFR1 and negatively correlates with angiogenesis in colorectal cancer, suggest that the GrK-sVEGFR1-angiogenesis axis may be a valid target for development of novel anti-angiogenic therapies in cancer.

Serum Vascular Endothelial Growth Factor and Vascular Endothelial Growth Factor Receptor-1 Levels in Patients With Fibromyalgia Syndrome

Objectives

This study aims to compare the serum vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-1 (VEGFR-1) levels between patients with fibromyalgia syndrome (FMS) and healthy controls.

Patients and methods

The study included 40 female patients (mean age 39.9±10.2 years; range, 22 to 52 years) diagnosed with primary FMS according to the American College of Rheumatology criteria (1990) and 40 healthy female volunteers (mean age 40.9±8.3 years; range, 25 to 53 years). The sociodemographic data of both groups were recorded. The disease duration and the number of tender points were recorded for patients with FMS, and venous blood samples were collected from the two groups for the measurement of serum VEGF and VEGFR-1 levels.

Results

The FMS and control groups were comparable in terms of age and body mass index (p>0.05). A comparison of the serum VEGF levels of the FMS and control groups revealed a statistically insignificant difference (p>0.05), while a comparison of the serum VEGF-1 levels of the FMS and control groups revealed a statistically significant difference (p<0.05).

Conclusion

Serum VEGFR-1 levels were higher in patients with FMS, while the serum VEGF levels of the FMS patients did not differ from those of the healthy controls.

Effect of the Recombinant Adenovirus-Mediated HIF-1 Alpha on the Expression of VEGF in the Hypoxic Brain Microvascular Endothelial Cells of Rats

OBJECTIVE

To investigate the effect of recombinant adenovirus-mediated HIF-1 alpha (HIF-1α) on the expression of vascular endothelial growth factor (VEGFA) and HIF-1α in hypoxic brain microvascular endothelial cells (BMEC) in rats.

METHODS

Primary cultured rat BMEC in vitro were treated without or with either recombinant adenovirus-mediated hypoxia-inducible factor-1 alpha (AdHIF-1α) or recombinant adenovirus empty vector (Ad) in the presence of CoCl₂ (simulating hypoxia conditions), or were grown under normoxia conditions. The expression of VEGFA and HIF-1α was analyzed at 12h, 24h, 48h and 72h incubation time, respectively. We also accessed a GEO dataset of stroke to analyze in vivo the alteration of HIF-1α and VEGFA expression, and the correlations between HIF-1α, VEGFA and CD31 mRNA levels in vascular vessels after stroke.

RESULTS

VEGFA and HIF-1α expression were significantly higher in at each time point in the AdHIF-1α than other groups (p<0.05), whereas the Ad group and hypoxia group, showed no statistically significant difference (p>0.05). Moreover, VEGFA and HIF-1α levels were significantly higher in BMEC under hypoxia conditions than normoxia conditions (p <0.05). Both HIF-1α and VEGFA expression significantly increased after stroke in vivo with 1.30 and 1.57 fold-change in log2, respectively. There were significantly positive associations between HIF-1α, VEGFA and CD31 mRNA levels in vivo after stroke.

CONCLUSION

Hypoxia-induced HIF-1α and VEGFA expression in vascular vessels, and recombinant AdHIF-1α could up-regulate VEGFA, and enhance HIF-1ααlevels in BMEC in vitro, which may play an important role in the recovery of stroke.

Propofol attenuated TNF-α-modulated occludin expression by inhibiting Hif-1α/ VEGF/ VEGFR-2/ ERK signaling pathway in hCMEC/D3 cells

Background

The levels of tight junction proteins (TJs), especially occludin, correlate with blood-brain barrier (BBB) disruption caused by inflammation in central nervous system (CNS). It has been reported that propofol, the most commonly used anesthetic, could inhibit inflammation response in CNS. In this study, we investigated the effects of tumor necrosis factor-α (TNF-α) and propofol on occludin expression in human cerebral microvascular endothelial cell line, D3 clone (hCMEC/D3 cells), and explored the underlying mechanisms.

Methods

The hCMEC/D3 cells were treated with propofol, followed by TNF-α. The expression and phosphorylation of Hif-1α, VEGF, VEGFR-2, ERK, p38MAPK and occludin were measured by Western blot analysis. The cell viability of hCMEC/D3 cells was measured by cell counting kit-8.

Results

TNF-α (10 ng/ml, 4 h) significantly decreased the expression of occludin, which was attenuated by propofol (25 μM). TNF-α induced Hif-1α/VEGF/VEGFR-2/ERK signaling pathway, while propofol could inhibit it. TNF-α induced the phosphorylation of p38MAPK, while propofol had no effect on it. In addition, the inhibitors of Hif-1α, VEGFR-2, and ERK could reduce the effect of TNF-α on occludin expression.

Conclusion

TNF-α could decrease the expression of occludin via activating Hif-1α/ VEGF/ VEGFR-2/ ERK signaling pathway, which was attenuated by propofol.

Electronic supplementary material

The online version of this article (10.1186/s12871-019-0788-5) contains supplementary material, which is available to authorized users.

Modeling angiogenesis with micro- and nanotechnology

Angiogenesis plays an important role not only in the growth and regeneration of tissues in humans but also in pathological conditions such as inflammation, degenerative disease and the formation of tumors. Angiogenesis is also vital in thick engineered tissues and constructs, such as those for the heart and bone, as these can face difficulties in successful implantation if they are insufficiently vascularized or unable to connect to the host vasculature. Considerable research has been carried out on angiogenic processes using a variety of approaches. Pathological angiogenesis has been analyzed at the cellular level through investigation of cell migration and interactions, modeling tissue level interactions between engineered blood vessels and whole organs, and elucidating signaling pathways involved in different angiogenic stimuli. Approaches to regenerative angiogenesis in ischemic tissues or wound repair focus on the vascularization of tissues, which can be broadly classified into two categories: scaffolds to direct and facilitate tissue growth and targeted delivery of genes, cells, growth factors or drugs that promote the regeneration. With technological advancement, models have been designed and fabricated to recapitulate the innate microenvironment. Moreover, engineered constructs provide not only a scaffold for tissue ingrowth but a reservoir of agents that can be controllably released for therapeutic purposes. This review summarizes the current approaches for modeling pathological and regenerative angiogenesis in the context of micro-/nanotechnology and seeks to bridge these two seemingly distant aspects of angiogenesis. The ultimate aim is to provide insights and advances from various models in the realm of angiogenesis studies that can be applied to clinical situations.

The anti-vascular endothelial growth factor receptor-1 monoclonal antibody D16F7 inhibits invasiveness of human glioblastoma and glioblastoma stem cells

BACKGROUND

Glioblastoma (GBM) is a highly migratory, invasive, and angiogenic brain tumor. Like vascular endothelial growth factor-A (VEGF-A), placental growth factor (PlGF) promotes GBM angiogenesis. VEGF-A is a ligand for both VEGF receptor-1 (VEGFR-1) and VEGFR-2, while PlGF interacts exclusively with VEGFR-1. We recently generated the novel anti-VEGFR-1 monoclonal antibody (mAb) D16F7 that diminishes VEGFR-1 homodimerization/activation without affecting VEGF-A and PlGF binding.

METHODS

In the present study, we evaluated the expression of VEGFR-1 in human GBM tissue samples (n = 42) by immunohistochemistry, in cell lines (n = 6) and GBM stem cells (GSCs) (n = 18) by qRT-PCR and/or western blot analysis. In VEGFR-1 positive GBM or GSCs we also analyzed the ability of D16F7 to inhibit GBM invasiveness in response to VEGF-A and PlGF.

RESULTS

Most of GBM specimens stained positively for VEGFR-1 and all but one GBM cell lines expressed VEGFR-1. On the other hand, in GSCs the expression of the receptor was heterogeneous. D16F7 reduced migration and invasion of VEGFR-1 positive GBM cell lines and patient-derived GSCs in response to VEGF-A and PlGF. Interestingly, this effect was also observed in VEGFR-1 positive GSCs transfected to over-express wild-type EGFR (EGFRwt⁺) or mutant EGFR (ligand binding domain-deficient EGFRvIII⁺). Furthermore, D16F7 suppressed intracellular signal transduction in VEGFR-1 over-expressing GBM cells by reducing receptor auto-phosphorylation at tyrosine 1213 and downstream Erk1/2 activation induced by receptor ligands.

CONCLUSION

The results from this study suggest that VEGFR-1 is a relevant target for GBM therapy and that D16F7-derived humanized mAbs warrant further investigation.

Spatholobi Caulis extracts promote angiogenesis in HUVECs in vitro and in zebrafish embryos in vivo via up-regulation of VEGFRs

ETHNOPHARMACOLOGICAL RELEVANCE

Spatholobi Caulis is a traditional blood-activating and stasis-dispelling herb medicine, which has been used to treat diseases related to blood stasis syndrome (BSS) by inhibiting platelet aggregation, stimulate hematopoiesis, etc. It has been demonstrated that pro-angiogenesis could improve BSS. However, the pro-angiogenic activity of Spatholobi Caulis was not well elucidated AIM OF STUDY: To determine the potential pro-angiogenic activity of Spatholobi Caulis and elucidate its underlying mechanism. The active fractions of Spatholobi Caulis were further screened.

MATERIAL AND METHODS

Gelatin precipitation and reversed-phase liquid chromatography (RPLC) were used to purify the methanol extracts of Spatholobi Caulis, respectively. The RPLC was also used to prepare fractions. Total flavonoids of purified methanol extracts of Spatholobi Caulis (PSC) were determined using ultraviolet spectrophotometry. The morphological observation of subintestinal vessel plexus (SIVs) and tyrosine kinase inhibitor II (VRI)-induced intersegmental blood vessels (ISVs) loss in transgenic zebrafish Tg(fli-1a: EGFP)y1 were selected to evaluate the pro-angiogenic activity of PSC in vivo. Cell proliferation by MTT assay and cell migration assay were used to evaluate the pro-angiogenesis effect of PSC in human umbilical vein endothelial cells (HUVECs) in vitro. Both zebrafish and HUVECs were used in screening active fractions of PSC. The mechanism of PSC promoting angiogenesis were studied by real-time PCR in zebrafish and western blotting in HUVECs.

RESULTS

Co-treatment PSC dramatically rescued VRI-induced ISVs loss in zebrafish embryos in a dose-dependent manner and 80% of the defective vascular recovered at the concentration of 30μg/ml compared with VRI-only group. PSC also concentration-dependently increased average sprouting number and diameter of SIVs in zebrafish embryo. Real-time PCR assay proved that PSC significantly restored the down regulation of VEGFRs including Flt-1, Kdr and Kdrl induced by VRI in zebrafish (P<0.001). Furthermore, PSC not only promoted proliferation and migration of normal HUVECs but also ameliorated VRI-induced HUVECs cytotoxicity. Western blotting assay showed that co-treatment of PSC increased the expression of VEGFRs and phosphorylation of MAPKs which decreased by VRI treatment. In addition, quality evaluation experiments showed that the content of total flavonoids of PSC reached 56.36% and the main pro-angiogenic fractions of PSC were F3, F4 and F5 both in zebrafish and HUVECs.

CONCLUSIONS

Our data demonstrated that PSC presented pro-angiogenic activity both in zebrafish and HUVECs, and principal pro-angiogenic active components were likely flavonoids. Thus, the current study provided evidence for the clinical usage of Spatholobi Caulis in promoting blood circulation and removing stasis in traditional Chinese medicine (TCM).