Comprehensive analysis of metabolic changes in spontaneously hypertensive rats

OBJECTIVES

Hypertension is a chronic disease with multiple causative factors that involve metabolic disturbances and can cause various complications. However, the metabolic characteristics of hypertension at different stages are still unclear. This study aimed to explore the metabolic changes induced by hypertension at different ages.

METHODS

Spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) rats were divided into four groups according to age: 5-week-old SHR (n = 6), 5-week-old WKY rats (n = 6), 32-week-old SHR (n = 6), and 32-week-old WKY rats (n = 6). Metabolites were analyzed in primary tissues (serum, heart, lung, kidney, brain, and brown adipose) using a non-targeted metabolomics approach.

RESULTS

Thirty-five metabolites and nine related metabolic pathways were identified in 5-week-old SHR, mainly related to the metabolism of amino acids. Fifty-one metabolites and seven related metabolic pathways were identified in the 32-week-old SHR, involving glycolysis, lipid, and amino acid metabolisms.

CONCLUSION

This experiment elucidates the metabolic profile of SHR at different ages and provides a basis for predicting and diagnosing hypertension. It also provides a reference for the pathogenesis of hypertension.

LncRNA SNHG8 regulates the migration and angiogenesis of pHUVECs induced by high glucose via the TRPM7/ERK1/2 signaling axis

This study aimed to evaluate the regulatory effect and molecular mechanism of long noncoding RNA small nucleolus RNA host gene 8 (LncRNA SNHG8) in the migration and angiogenesis of primary human umbilical vein endothelial cells (pHUVECs) under high-glucose (HG) conditions. The HG-induced endothelial injury model was established in vitro.The cell model of silencing SNHG8, overexpressing SNHG8, and silencing TRPM7 was established by transfecting SNHG8-siRNA, SNHG8 plasmid and TRPM7-siRNA into cells with liposomes.The SNHG8 level was determined through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The expression levels of transient receptor potential melastatin 7 (TRPM7), endothelial nitric oxide synthase (eNOS), p-eNOS, extracellular signal-regulated kinase 1/2(ERK1/2), and p-ERK1/2 were assessed through western blot. Nitric oxide (NO) levels were measured with DAF-FM. pHUVEC migration was examined through wound healing and Transwell assay, and pHUVEC angiogenesis was observed through a tube formation assay. Results showed that HG promoted the expression of lncRNA SNHG8 and TRPM7 and decreased the ratio of p-eNOS/eNOS and p-ERK1/2/ERK1/2 in pHUVECs . NO production, migration , and angiogenesis were inhibited in pHUVECs under HG conditions. Silencing lncRNA SNHG8 and TRPM7 could significantly reverse the HG-induced decrease in eNOS activation, NO production , migration, and angiogenesis . SNHG8 and U0126 (ERK pathway inhibitor) overexpression enhanced the HG effects, whereas using U0126 did not affect the TRPM7 expression. In conclusion, lncRNA SNHG8 participates in HG-induced endothelial cell injury and likely regulates NO production, migration, and angiogenesis of pHUVECs via the TRPM7/ERK1/2 signaling axis.

Effects of propranolol on glucose metabolism in hemangioma-derived endothelial cells

Infantile hemangioma (IH) is the most common benign tumor in children. Propranolol is the first-line treatment for IH, but the underlying mechanism of propranolol treatment in IH is not completely understood. Integrated transcriptional and metabolic analyses were performed to investigate the metabolic changes in hemangioma-derived endothelial cells (HemECs) after propranolol treatment. The findings were then further validated through independent cell experiments using a Seahorse XFp analyzer, Western blotting, immunohistochemistry and mitochondrial functional assays. Thirty-four differentially expressed metabolites, including the glycolysis metabolites glucose 6-phosphate, fructose 6-phosphate and fructose 1,6-bisphosphate, were identified by targeted metabolomics. A KEGG pathway enrichment analysis showed that the disturbances in these metabolites were highly related to glucose metabolism-related pathways, including the pentose phosphate pathway, the Warburg effect, glycolysis and the citric acid cycle. Transcriptional analysis revealed that metabolism-related pathways, including glycine, serine and threonine metabolism, tyrosine metabolism, and glutathione metabolism, were highly enriched. Moreover, integration of the metabolomic and transcriptomic data revealed that glucose metabolism-related pathways, particularly glycolysis, were altered after propranolol treatment. Cell experiments demonstrated that HemECs exhibited higher levels of glycolysis than human umbilical vein ECs (HUVECs) and that propranolol suppressed glycolysis in HemECs. In conclusion, propranolol inhibited glucose metabolism in HemECs by suppressing glucose metabolic pathways, particularly glycolysis.

Metabolomics and Biomarkers in Retinal and Choroidal Vascular Diseases

The retina is one of the most important structures in the eye, and the vascular health of the retina and choroid is critical to visual function. Metabolomics provides an analytical approach to endogenous small molecule metabolites in organisms, summarizes the results of “gene-environment interactions”, and is an ideal analytical tool to obtain “biomarkers” related to disease information. This study discusses the metabolic changes in neovascular diseases involving the retina and discusses the progress of the study from the perspective of metabolomics design and analysis. This study advocates a comparative strategy based on existing studies, which encompasses optimization of the performance of newly identified biomarkers and the consideration of the basis of existing studies, which facilitates quality control of newly discovered biomarkers and is recommended as an additional reference strategy for new biomarker discovery. Finally, by describing the metabolic mechanisms of retinal and choroidal neovascularization, based on the results of existing studies, this study provides potential opportunities to find new therapeutic approaches.

Inducing vascular normalization: A promising strategy for immunotherapy

In solid tumors, the vasculature is highly abnormal in structure and function, resulting in the formation of an immunosuppressive tumor microenvironment by limiting immune cells infiltration into tumors. Vascular normalization is receiving much attention as an alternative strategy to anti-angiogenic therapy, and its potential therapeutic targets include signaling pathways, angiogenesis-related genes, and metabolic pathways. Endothelial cells play an important role in the formation of blood vessel structure and function, and their metabolic processes drive blood vessel sprouting in parallel with the control of genetic signals in cancer. The feedback loop between vascular normalization and immunotherapy has been discussed extensively in many reviews. In this review, we summarize the impact of aberrant tumor vascular structure and function on drug delivery, metastasis, and anti-tumor immune responses. In addition, we present evidences for the mutual regulation of immune vasculature. Based on the importance of endothelial metabolism in controlling angiogenesis, we elucidate the crosstalk between endothelial cells and immune cells from the perspective of metabolic pathways and propose that targeting abnormal endothelial metabolism to achieve vascular normalization can be an alternative strategy for cancer treatment, which provides a new theoretical basis for future research on the combination of vascular normalization and immunotherapy.

Paeoniflorin Inhibits EMT and Angiogenesis in Human Glioblastoma via K63-Linked C-Met Polyubiquitination-Dependent Autophagic Degradation

Epithelial-to-mesenchymal transition (EMT) and angiogenesis have emerged as two pivotal events in cancer progression. Paeoniflorin has been widely studied in experimental models and clinical trials for cancer treatment because of its anti-cancer property. However, the underlying mechanisms of paeoniflorin in EMT and angiogenesis in glioblastoma was not fully elucidated. The present study aimed to investigate whether paeoniflorin inhibits EMT and angiogenesis, which involving c-Met suppression, while exploring the potential ways of c-Met degradation. In our study, we found that paeoniflorin inhibited EMT via downregulating c-Met signaling in glioblastoma cells. Furthermore, overexpressing c-Met in glioblastoma cells abolished the effects of paeoniflorin on EMT. Moreover, paeoniflorin showed anti-angiogenic effects by suppressing cell proliferation, migration, invasion and tube formation through downregulating c-Met in human umbilical vein endothelial cells (HUVECs). And c-Met overexpression in HUVECs offset the effects of paeoniflorin on angiogenesis. Additionally, paeoniflorin induced autophagy activation involving mTOR/P70S6K/S6 signaling and promoted c-Met autophagic degradation, a process dependent on K63-linked c-Met polyubiquitination. Finally, paeoniflorin suppressed mesenchymal makers (snail, vimentin, N-cadherin) and inhibited angiogenesis via the identical mechanism in an orthotopic xenograft mouse model. The in vitro and in vivo experiments showed that paeoniflorin treatment inhibited EMT, angiogenesis and activated autophagy. What’s more, for the first time, we identified c-Met may be a potential target of paeoniflorin and demonstrated paeoniflorin downregulated c-Met via K63-linked c-Met polyubiquitination-dependent autophagic degradation. Collectively, these findings indicated that paeoniflorin inhibits EMT and angiogenesis via K63-linked c-Met polyubiquitination-dependent autophagic degradation in human glioblastoma.

Tetrahedral framework nucleic acids-based delivery promotes intracellular transfer of healing peptides and accelerates diabetic would healing

Objectives

Peptide‐based therapeutics are natural candidates to desirable wound healing. However, enzymatic surroundings largely limit its stability and bioavailability. Here, we developed a tetrahedral framework nucleic acids(tFNA)‐based peptide delivery system, that is, p@tFNAs, to address deficiencies of healing peptide stability and intracellular delivery in diabetic wound healing.

Materials and Methods

AGEs (advanced glycation end products) were used to treat endothelial cell to simulate cell injury in diabetic microenvironment. The effects and related mechanisms of p@tFNAs on endothelial cell proliferation, migration, angiogenesis and ROS (reactive oxygen species) production have been comprehensively studied. The wound healing model in diabetic mice was photographically and histologically investigated in vivo.

Results

Efficient delivery of healing peptide by the framework(tFNA) was verified. p@tFNAs helped overcome the angiogenic obstacles induced by AGEs via ERK1/2 phosphorylation. In the meantime, p@tFNA exhibited its antioxidative property to achieve ROS balance. As a result, p@tFNA improved angiogenesis and diabetic wound healing in vitro and in vivo.

Conclusions

Our findings demonstrate that p@tFNA could be a novel therapeutic strategy for diabetic wound healing. Moreover, a new method for intracellular delivery of peptides was also constructed.

Hotspots and Frontiers in Inflammatory Tumor Microenvironment Research: A Scientometric and Visualization Analysis

Methods: Articles on inflammatory tumor microenvironment were retrieved from the Web of Science Core Collection, and the characteristics of the articles were analyzed by CiteSpace software.

Background: The inflammatory tumor microenvironment is an essential feature of the tumor microenvironment. The way in which it promotes or inhibits tumor progression plays an important role in the outcome of a tumor treatment. This research aims to explore a scientific collaboration network, describe evolution of hotspots, and predict future trends through bibliometric analysis.

Results: A total of 3,534 papers published by 390 institutions in 81 countries/regions were screened, and the annual quantity has been increasing rapidly in the past decades. United States was the leading country and has the most productive institutions in this field. The research topics were mainly focused on inflammation and immunity mediated by crucial factors as well as the mechanisms of angiogenesis. Additionally, the development and application of nanoparticles is currently a novel research frontier with bright prospect.

Conclusion: The present scientometric study provides an overview of inflammatory tumor microenvironment research over the previous decades using quantitative and qualitative methods, and the findings of this study can provide references for researchers focusing on tumor treatment.

Rethinking growth factors: the case of BMP9 during vessel maturation

Angiogenesis is an essential process for correct development and physiology. This mechanism is tightly regulated by many signals that activate several pathways, which are constantly interacting with each other. There is mounting evidence that BMP9/ALK1 pathway is essential for a correct vessel maturation. Alterations in this pathway lead to the development of hereditary haemorrhagic telangiectasias. However, little was known about the BMP9 signalling cascade until the last years. Recent reports have shown that while BMP9 arrests cell cycle, it promotes the activation of anabolic pathways to enhance endothelial maturation. In light of this evidence, a new criterion for the classification of cytokines is proposed here, based on the physiological objective of the activation of anabolic routes. Whether this activation by a growth factor is needed to sustain mitosis or to promote a specific function such as matrix formation is a critical characteristic that needs to be considered to classify growth factors. Hence, the state-of-the-art of BMP9/ALK1 signalling is reviewed here, as well as its implications in normal and pathogenic angiogenesis.

Single-cell transcriptome profiling reveals vascular endothelial cell heterogeneity in human skin

Vascular endothelial cells (ECs) are increasingly recognized as active players in intercellular crosstalk more than passive linings of a conduit for nutrition delivery. Yet, their functional roles and heterogeneity in skin remain uncharacterized. We have used single-cell RNA sequencing (scRNA-seq) as a profiling strategy to investigate the tissue-specific features and intra-tissue heterogeneity in dermal ECs at single-cell level.

Methods: Skin tissues collected from 10 donors were subjected to scRNA-seq. Human dermal EC atlas of over 23,000 single-cell transcriptomes was obtained and further analyzed. Arteriovenous markers discovered in scRNA-seq were validated in human skin samples via immunofluorescence. To illustrate tissue-specific characteristics of dermal ECs, ECs from other human tissues were extracted from previously reported data and compared with our transcriptomic data.

Results: In comparison with ECs from other human tissues, dermal ECs possess unique characteristics in metabolism, cytokine signaling, chemotaxis, and cell adhesions. Within dermal ECs, 5 major subtypes were identified, which varied in molecular signatures and biological activities. Metabolic transcriptome analysis revealed a preference for oxidative phosphorylation in arteriole ECs when compared to capillary and venule ECs. Capillary ECs abundantly expressed HLA-II molecules, suggesting its immune-surveillance role. Post-capillary venule ECs, with high levels of adhesion molecules, were equipped with the capacity in immune cell arrest, adhesion, and infiltration.

Conclusion: Our study provides a comprehensive characterization of EC features and heterogeneity in human dermis and sets the stage for future research in identifying disease-specific alterations of dermal ECs in various dermatoses.

COCO/DAND5 inhibits developmental and pathological ocular angiogenesis

Neovascularization contributes to multiple visual disorders including age-related macular degeneration (AMD) and retinopathy of prematurity. Current therapies for treating ocular angiogenesis are centered on the inhibition of vascular endothelial growth factor (VEGF). While clinically effective, some AMD patients are refractory or develop resistance to anti-VEGF therapies and concerns of increased risks of developing geographic atrophy following long-term treatment have been raised. Identification of alternative pathways to inhibit pathological angiogenesis is thus important. We have identified a novel inhibitor of angiogenesis, COCO, a member of the Cerberus-related DAN protein family. We demonstrate that COCO inhibits sprouting, migration and cellular proliferation of cultured endothelial cells. Intravitreal injections of COCO inhibited retinal vascularization during development and in models of retinopathy of prematurity. COCO equally abrogated angiogenesis in models of choroidal neovascularization. Mechanistically, COCO inhibited TGFβ and BMP pathways and altered energy metabolism and redox balance of endothelial cells. Together, these data show that COCO is an inhibitor of retinal and choroidal angiogenesis, possibly representing a therapeutic option for the treatment of neovascular ocular diseases.

An Amplified Fatty Acid-Binding Protein Gene Cluster in Prostate Cancer: Emerging Roles in Lipid Metabolism and Metastasis

Treatment for early stage and localized prostate cancer (PCa) is highly effective. Patient survival, however, drops dramatically upon metastasis due to drug resistance and cancer recurrence. The molecular mechanisms underlying PCa metastasis are complex and remain unclear. It is therefore crucial to decipher the key genetic alterations and relevant molecular pathways driving PCa metastatic progression so that predictive biomarkers and precise therapeutic targets can be developed. Through PCa cohort analysis, we found that a fatty acid-binding protein (FABP) gene cluster (containing five FABP family members) is preferentially amplified and overexpressed in metastatic PCa. All five FABP genes reside on chromosome 8 at 8q21.13, a chromosomal region frequently amplified in PCa. There is emerging evidence that these FABPs promote metastasis through distinct biological actions and molecular pathways. In this review, we discuss how these FABPs may serve as drivers/promoters for PCa metastatic transformation using patient cohort analysis combined with a review of the literature.

S-adenosylmethionine administration inhibits levodopa-induced vascular endothelial growth factor-A expression

Background: Studies have demonstrated that S-adenosylmethionine could effectively affect the clinical wearing-off phenomena of levodopa, an antiparkinsonian agent; however, the detailed mechanisms for this effect need to be further clarified.

Results: S-adenosylmethionine and levodopa had opposite effects on the protein stability of vascular endothelial growth factor-A. The analysis of tube formation and cell viability also showed the nonconforming functions of S-adenosylmethionine and levodopa on cell angiogenesis and proliferation. Meanwhile, S-adenosylmethionine could significantly abolish the increased angiogenesis and cell viability induced by levodopa. S-adenosylmethionine resulted in G1/S phase arrest, with decreased cyclin dependent kinase 4/6 and increased p16, a specific cyclin dependent kinase inhibitor. Mechanically, the different effects of levodopa and S-adenosylmethionine were dependent on the phosphorylation and activation of extracellular signal-regulated kinase. S-adenosylmethionine could be fitted into the predicted docking pocket in the crystal structure of vascular endothelial growth factor-A, enhancing its acetylation level and reducing half-life.

Conclusions: These observations suggested that methyl donor S-adenosylmethionine could act as a potential agent against vascular endothelial growth factor-A-related diseases induced by levodopa treatment.

Methods: We performed in vitro cytological analyses to assess whether S-adenosylmethionine intake could influence levodopa-induced vascular endothelial growth factor-A expression in human umbilical vein endothelial cells.

Novel Anti-inflammatory Effects of Canagliflozin Involving Hexokinase II in Lipopolysaccharide-Stimulated Human Coronary Artery Endothelial Cells

Purpose

Vascular inflammation and disturbed metabolism are observed in heart failure and type 2 diabetes mellitus. Glycolytic enzyme hexokinase II (HKII) is upregulated by inflammation. We hypothesized that SGLT2 inhibitors Canagliflozin (Cana), Empagliflozin (Empa) or Dapagliflozin (Dapa) reduces inflammation via HKII in endothelial cells, and that HKII-dependent inflammation is determined by ERK1/2, NF-κB. and/or AMPK activity in lipopolysaccharide (LPS)-stimulated human coronary artery endothelial cells (HCAECs).

Methods

HCAECs were pre-incubated with 3 μM or 10 μM Cana, 1 μM, 3 μM or 10 μM Empa or 0.5 μM, 3 μM or 10 μM Dapa (16 h) and subjected to 3 h LPS (1 μg/mL). HKII was silenced via siRNA transfection. Interleukin-6 (IL-6) release was measured by ELISA. Protein levels of HK I and II, ERK1/2, AMPK and NF-κB were detected using infra-red western blot.

Results

LPS increased IL-6 release and ERK1/2 phosphorylation; Cana prevented these pro-inflammatory responses (IL-6: pg/ml, control 46 ± 2, LPS 280 ± 154 p < 0.01 vs. control, LPS + Cana 96 ± 40, p < 0.05 vs. LPS). Cana reduced HKII expression (HKII/GAPDH, control 0.91 ± 0.16, Cana 0.71 ± 0.13 p < 0.05 vs. control, LPS 1.02 ± 0.25, LPS + Cana 0.82 ± 0.24 p < 0.05 vs. LPS). Empa and Dapa were without effect on IL-6 release and HKII expression in the model used. Knockdown of HKII by 37% resulted caused partial loss of Cana-mediated IL-6 reduction (pg/ml, control 35 ± 5, LPS 188 ± 115 p < 0.05 vs. control, LPS + Cana 124 ± 75) and ERK1/2 activation by LPS. In LPS-stimulated HCAECs, Cana, but not Empa or Dapa, activated AMPK. AMPK activator A769662 reduced IL-6 release.

Conclusion

Cana conveys anti-inflammatory actions in LPS-treated HCAECs through 1) reductions in HKII and ERK1/2 phosphorylation and 2) AMPK activation. These data suggest a novel anti-inflammatory mechanism of Cana through HKII.

Electronic supplementary material

The online version of this article (10.1007/s10557-020-07083-w) contains supplementary material, which is available to authorized users.

Antiangiogenic Effect of Graphene Oxide in Primary Human Endothelial Cells

In this work, we exploited an integrated approach combining systematic analysis of cytotoxicity, angiogenic potential, and metabolomics to shed light on the effects of graphene oxide (GO) on primary human endothelial Huvec cells. Contrary to the outcomes observed in immortalized cell lines able to internalize a similar amount of GO, significant toxicity was found in Huvec cells at high GO concentrations (25 and 50 μg/mL). In particular, we found that the steric hindrance of GO intracellular aggregates perturbed the correct assembly of cytoskeleton and distribution of mitochondria. This was found to be primarily associated with oxidative stress and impairment of cell migration, affecting the formation of capillary-like structures. In addition, preliminary metabolomics characterization demonstrated that GO affects the consumption of niacinamide, a precursor of energy carriers, and several amino acids involved in the regulation of angiogenesis. Our findings suggest that GO acts at different cellular levels, both directly and indirectly. More precisely, the combination of the physical hindrance of internalized GO aggregates, induction of oxidative stress, and alteration of some metabolic pathways leads to a significant antiangiogenic effect in primary human endothelial cells.

Sex differences in murine myocutaneous flap revascularization

Sex differences in susceptibility to ischemia/reperfusion injury have been documented in humans. Premenopausal women have a lower risk of ischemic heart disease than age-matched men, whereas after menopause, the risk is similar or even higher in women. However, little is known about the effects of sex on myocutaneous ischemia/reperfusion. To explore sex differences in wound revascularization, we utilized a murine myocutaneous flap model of graded ischemia. A cranial-based, peninsular-shaped, myocutaneous flap was surgically created on the dorsum of male and female mice. Physiological, pathological, immunohistochemical, and molecular parameters were analyzed. Flaps created on female mice were re-attached to the recipient site resulting in nearly complete viability at post-operative day 10. In contrast, distal full-thickness myocutaneous necrosis was evident at 10 days post-surgery in male mice. Over the 10 day study interval, laser speckle imaging documented functional revascularization in all flap regions in female mice, but minimal distal flap reperfusion in male mice. Day 10 immunostained histologic sections confirmed significant increases in distal flap vessel count and vascular surface area in female compared to male mice. RT-PCR demonstrated significant differences in growth factor and metabolic gene expression between female and male mice at day 10. In conclusion, in a graded-ischemia wound healing model, flap revascularization was more effective in female mice. The recognition and identification of sex-specific wound healing differences may lead to a better understanding of the underlying mechanisms of myocutaneous revascularization and drive novel discovery to improve soft tissue wound healing following tissue transfer for traumatic injury and cancer resection.

Context-dependent regulation of endothelial cell metabolism: differential effects of the PPARβ/δ agonist GW0742 and VEGF-A

Peroxisome proliferator activated receptor β/δ (PPARβ/δ) has pro-angiogenic functions, but whether PPARβ/δ modulates endothelial cell metabolism to support the dynamic phenotype remains to be established. This study characterised the metabolic response of HUVEC to the PPARβ/δ agonist, GW0742, and compared these effects with those induced by VEGF-A. In HUVEC monolayers, flux analysis revealed that VEGF-A promoted glycolysis at the expense of fatty acid oxidation (FAO), whereas GW0742 reduced both glycolysis and FAO. Only VEGF-A stimulated HUVEC migration and proliferation whereas both GW0742 and VEGF-A promoted tubulogenesis. Studies using inhibitors of PPARβ/δ or sirtuin-1 showed that the tubulogenic effect of GW0742, but not VEGF-A, was PPARβ/δ- and sirtuin-1-dependent. HUVEC were reliant on glycolysis and FAO, and inhibition of either pathway disrupted cell growth and proliferation. VEGF-A was a potent inducer of glycolysis in tubulogenic HUVEC, while FAO was maintained. In contrast, GW0742-induced tubulogenesis was associated with enhanced FAO and a modest increase in glycolysis. These novel data reveal a context-dependent regulation of endothelial metabolism by GW0742, where metabolic activity is reduced in monolayers but enhanced during tubulogenesis. These findings expand our understanding of PPARβ/δ in the endothelium and support the targeting of PPARβ/δ in regulating EC behaviour and boosting tissue maintenance and repair.

Overview of Brain-to-Gut Axis Exposed to Chronic CNS Bacterial Infection(s) and a Predictive Urinary Metabolic Profile of a Brain Infected by Mycobacterium tuberculosis

A new paradigm in neuroscience has recently emerged - the brain-gut axis (BGA). The contemporary focus in this paradigm has been gut → brain ("bottom-up"), in which the gut-microbiome, and its perturbations, affects one's psychological state-of-mind and behavior, and is pivotal in neurodegenerative disorders. The emerging brain → gut ("top-down") concept, the subject of this review, proposes that dysfunctional brain health can alter the gut-microbiome. Feedback of this alternative bidirectional highway subsequently aggravates the neurological pathology. This paradigm shift, however, focuses upon non-communicable neurological diseases (progressive neuroinflammation). What of infectious diseases, in which pathogenic bacteria penetrate the blood-brain barrier and interact with the brain, and what is this effect on the BGA in bacterial infection(s) that cause chronic neuroinflammation? Persistent immune activity in the CNS due to chronic neuroinflammation can lead to irreversible neurodegeneration and neuronal death. The properties of cerebrospinal fluid (CSF), such as immunological markers, are used to diagnose brain disorders. But what of metabolic markers for such purposes? If a BGA exists, then chronic CNS bacterial infection(s) should theoretically be reflected in the urine. The premise here is that chronic CNS bacterial infection(s) will affect the gut-microbiome and that perturbed metabolism in both the CNS and gut will release metabolites into the blood that are filtered (kidneys) and excreted in the urine. Here we assess the literature on the effects of chronic neuroinflammatory diseases on the gut-microbiome caused by bacterial infection(s) of the CNS, in the context of information attained via metabolomics-based studies of urine. Furthermore, we take a severe chronic neuroinflammatory infectious disease - tuberculous meningitis (TBM), caused by Mycobacterium tuberculosis, and examine three previously validated CSF immunological biomarkers - vascular endothelial growth factor, interferon-gamma and myeloperoxidase - in terms of the expected changes in normal brain metabolism. We then model the downstream metabolic effects expected, predicting pivotal altered metabolic pathways that would be reflected in the urinary profiles of TBM subjects. Our cascading metabolic model should be adjustable to account for other types of CNS bacterial infection(s) associated with chronic neuroinflammation, typically prevalent, and difficult to distinguish from TBM, in the resource-constrained settings of poor communities.

Endothelial Glycocalyx Hyaluronan: Regulation and Role in Prevention of Diabetic Complications

The endothelial glycocalyx is critically involved in vascular integrity and homeostasis, by regulating vascular permeability, regulating mechanotransduction, and reducing inflammation and coagulation. The turnover of the glycocalyx is dynamic to fine-tune these processes. This is in particular true for its main structural component, hyaluronan (HA). Degradation and shedding of the glycocalyx by enzymes, such as hyaluronidase 1 and hyaluronidase 2, are responsible for regulation of the glycocalyx thickness and hence access of circulating cells and factors to the endothelial cell membrane and its receptors. This degradation process will at the same time also allow for resynthesis and adaptive chemical modification of the glycocalyx. The (re)synthesis of HA is dependent on the availability of its sugar substrates, thus linking glycocalyx biology directly to cellular glucose metabolism. It is therefore of particular interest to consider the consequences of dysregulated cellular glucose in diabetes for glycocalyx biology and its implications for endothelial function. This review summarizes the metabolic regulation of endothelial glycocalyx HA and its potential as a therapeutic target in diabetic vascular complications.

Anti-Angiogenic Effects of Phytochemicals on miRNA Regulating Breast Cancer Progression

Several phytochemicals have been identified for their role in modifying miRNA regulating tumor progression. miRNAs modulate the expression of several oncogenes and tumor suppressor genes including the genes that regulate tumor angiogenesis. Hypoxia inducible factor-1 alpha (HIF-1α) signaling is a central axis that activates oncogenic signaling and acts as a metabolic switch in endothelial cell (EC) driven tumor angiogenesis. Tumor angiogenesis driven by metabolic reprogramming of EC is crucial for tumor progression and metastasis in many different cancers, including breast cancers, and has been linked to aberrant miRNA expression profiles. In the current article, we identify different miRNAs that regulate tumor angiogenesis in the context of oncogenic signaling and metabolic reprogramming in ECs and review how selected phytochemicals could modulate miRNA levels to induce an anti-angiogenic action in breast cancer. Studies involving genistein, epigallocatechin gallate (EGCG) and resveratrol demonstrate the regulation of miRNA-21, miRNA-221/222 and miRNA-27, which are prognostic markers in triple negative breast cancers (TNBCs). Modulating the metabolic pathway is a novel strategy for controlling tumor angiogenesis and tumor growth. Cardamonin, curcumin and resveratrol exhibit their anti-angiogenic property by targeting the miRNAs that regulate EC metabolism. Here we suggest that using phytochemicals to target miRNAs, which in turn suppresses tumor angiogenesis, should have the potential to inhibit tumor growth, progression, invasion and metastasis and may be developed into an effective therapeutic strategy for the treatment of many different cancers where tumor angiogenesis plays a significant role in tumor growth and progression.

Predictive Approach Identifies Molecular Targets and Interventions to Restore Angiogenesis in Wounds With Delayed Healing

Impaired angiogenesis is a hallmark of wounds with delayed healing, and currently used therapies to restore angiogenesis have limited efficacy. Here, we employ a computational simulation-based approach to identify influential molecular and cellular processes, as well as protein targets, whose modulation may stimulate angiogenesis in wounds. We developed a mathematical model that captures the time courses for platelets, 9 cell types, 29 proteins, and oxygen, which are involved in inflammation, proliferation, and angiogenesis during wound healing. We validated our model using previously published experimental data. By performing global sensitivity analysis on thousands of simulated wound-healing scenarios, we identified six processes (among the 133 modeled in total) whose modulation may improve angiogenesis in wounds. By simulating knockouts of 25 modeled proteins and by simulating different wound-oxygenation levels, we identified four proteins [namely, transforming growth factor (TGF)-β, vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), and angiopoietin-2 (ANG-2)], as well as oxygen, as therapeutic targets for stimulating angiogenesis in wounds. Our modeling results indicated that simultaneous inhibition of TGF-β and supplementation of either FGF-2 or ANG-2 could be more effective in stimulating wound angiogenesis than the modulation of either protein alone. Our findings suggest experimentally testable intervention strategies to restore angiogenesis in wounds with delayed healing.

The Placental Growth Factor Pathway and Its Potential Role in Macular Degenerative Disease

There is growing evidence that placental growth factor (PlGF) is an important player in multiple pathologies, including tumorigenesis, inflammatory disorders and degenerative retinopathies. PlGF is a member of the vascular endothelial growth factor (VEGF) family and in the retina, binding of this growth factor to specific receptors is associated with pathological angiogenesis, vascular leakage, neurodegeneration and inflammation. Although they share some receptor signalling pathways, many of the actions of PlGF are distinct from VEGF and this has revealed the enticing prospect that it could be a useful therapeutic target for treating early and late stages of diabetic retinopathy (DR) and neovascular age-related macular degeneration (AMD). Recent research suggests that modulation of PlGF could also be important in the geographic atrophy (GA) form of late AMD by protecting the outer retina and the retinal pigment epithelium (RPE). This review discusses PlGF and its signalling pathways and highlights the potential of blocking the bioactivity of this growth factor to treat irreversible visual loss due to the two main forms of AMD.

Anti-angiogenic Therapy for Retinal Disease

Recent breakthroughs in our understanding of the molecular pathophysiology of retinal vascular disease have allowed us to specifically target pathological angiogenesis while minimizing damage to the neurosensory retina. This is perhaps best exemplified by the development of therapies targeting the potent angiogenic growth factor and vascular permeability mediator, vascular endothelial growth factor (VEGF). Anti-VEGF therapies, initially introduced for the treatment of choroidal neovascularization in patients with age-related macular degeneration, have also had a dramatic impact on the management of retinal vascular disease and are currently an indispensable component for the treatment of macular edema in patients with diabetic eye disease and retinal vein occlusions. Emerging evidence supports expanding the use of therapies targeting VEGF for the treatment of retinal neovascularization in patients with diabetic retinopathy and retinopathy of prematurity. However, VEGF is among a growing list of angiogenic and vascular hyperpermeability factors that promote retinal vascular disease. Many of these mediators are expressed in response to stabilization of a single family of transcription factors, the hypoxia-inducible factors (HIFs), that regulate the expression of these angiogenic stimulators. Here we review the basic principles driving pathological angiogenesis and discuss the current state of retinal anti-angiogenic pharmacotherapy as well as future directions.

Heterogeneous Pulmonary Response After Tracheal Occlusion: Clues to Fetal Lung Growth

BACKGROUND

Understanding inconsistent clinical outcomes in infants with severe congenital diaphragmatic hernia (CDH) after tracheal occlusion (TO) is a crucial step for advancing neonatal care. The objective of this study is to explore the heterogeneous airspace morphometry and the metabolic landscape changes in fetal lungs after TO.

METHODS

Fetal lungs on days 1 and 4 after TO were examined using mass spectrometry-based metabolomics, fluorescence lifetime imaging microscopy (FLIM), the number of airspaces, and tissue-to-airspace ratio (TAR).

RESULTS

Two morphometric areas were identified in TO lungs compared with controls (more small airspaces at day 1 and a higher number of enlarged airspaces at day 4). Global metabolomics analysis revealed a significant upregulation of glycolysis and a suppression of the tricarboxylic acid cycle in day 4 TO lungs compared with day 1 TO lungs. In addition, there was a significant increase in polyamines involved in cell growth and proliferation. Locally, FLIM analysis on day 1 TO lungs demonstrated two types of heterogeneous zones-similar to control and with increased oxidative phosphorylation. FLIM on day 4 TO lungs demonstrated appearance of zones with enlarged airspaces and a metabolic shift toward glycolysis, accompanied by a decrease in the FLIM "lipid-surfactant" signal.

CONCLUSIONS

In normal fetal lungs, we report a novel temporal pattern of varied morphometric and metabolic changes. Initially, there is formation of zones with small airspaces, followed by airspace enlargement over time. Metabolically day 1 TO lungs have zones with increased oxidative phosphorylation, whereas day 4 TO lungs have a shift toward glycolysis in the enlarged airspaces. Based on our observations, we speculate that the "best responders" to tracheal occlusion should have bigger lungs with small airspaces and normal surfactant production.

Loss of Estrogen-Related Receptor Alpha Facilitates Angiogenesis in Endothelial Cells

Estrogen-related receptors (ERRs) have emerged as major metabolic regulators in various tissues. However, their expression and function in the vasculature remains unknown. Here, we report the transcriptional program and cellular function of ERRα in endothelial cells (ECs), a cell type with a multifaceted role in vasculature. Of the three ERR subtypes, ECs exclusively express ERRα. Gene expression profiling of ECs lacking ERRα revealed that ERRα predominantly acts as a transcriptional repressor, targeting genes linked with angiogenesis, cell migration, and cell adhesion. ERRα-deficient ECs exhibit decreased proliferation but increased migration and tube formation. ERRα depletion increased basal as well as vascular endothelial growth factor A (VEGFA)- and ANG1/2-stimulated angiogenic sprouting in endothelial spheroids. Moreover, retinal angiogenesis is enhanced in ERRα knockout mice compared to that in wild-type mice. Surprisingly, ERRα is dispensable for the regulation of its classic targets, such as metabolism, mitochondrial biogenesis, and cellular respiration in the ECs. ERRα is enriched at the promoters of angiogenic, migratory, and cell adhesion genes. Further, VEGFA increased ERRα recruitment to angiogenesis-associated genes and simultaneously decreased their expression. Despite increasing its gene occupancy, proangiogenic stimuli decrease ERRα expression in ECs. Our work shows that endothelial ERRα plays a repressive role in angiogenesis and potentially fine-tunes growth factor-mediated angiogenesis.

Phostine 3.1a as a pharmacological compound with antiangiogenic properties against diseases with excess vascularization

Angiogenesis is a complex process leading to the growth of new blood vessels from existing vasculature, triggered by local proangiogenic factors such as VEGF. An excess of angiogenesis is a recurrent feature of various pathologic conditions such as tumor growth. Phostines are a family of synthetic glycomimetic compounds that exhibit anticancer properties, and the lead compound 3-hydroxy-4,5-bis-benzyloxy-6-benzyloxymethyl-2-phenyl2-oxo-2λ5-[1,2]oxaphosphinane (PST 3.1a) shows antiglioblastoma properties both in vitro and in vivo. In the present study, we assessed the effect of PST 3.1a on angiogenesis and endothelial metabolism. In vitro, PST 3.1a (10 µM) inhibited all steps that regulate angiogenesis, including migration, proliferation, adhesion, and tube formation. In vivo, PST 3.1a reduced intersegmental vessel formation and vascularization of the subintestinal plexus in zebrafish embryos and also altered pathologic angiogenesis and glioblastoma progression in vivo. Mechanistically, PST 3.1a altered interaction of VEGF receptor 2 and glycosylation-regulating protein galectin-1, a key component regulating angiogenesis associated with tumor resistance. Thus, these data show that use of PST 3.1a is an innovative approach to target angiogenesis.-Bousseau, S., Marchand, M., Soleti, R., Vergori, L., Hilairet, G., Recoquillon, S., Le Mao, M., Gueguen, N., Khiati, S., Clarion, L., Bakalara, N., Martinez, M. C., Germain, S., Lenaers, G., Andriantsitohaina, R. Phostine 3.1a as a pharmacological compound with antiangiogenic properties against diseases with excess vascularization.

Pro-angiogenic Role of Danqi Pill Through Activating Fatty Acids Oxidation Pathway Against Coronary Artery Disease

Coronary artery disease (CAD) is one of the leading causes of deaths worldwide. Energy metabolism disorders, including a reduction in fatty acids oxidation and upregulation of glycolysis pathway, are involved in the process of CAD. Therapeutic angiogenesis has become a promising treatment for CAD. Traditional Chinese medicines, such as Danqi Pill (DQP), have been proven to be effective in treating CAD in China for many years. However, the pro-angiogenic effects of DQP based on fatty acids oxidation are still unknown and the mechanism is worthy of investigation. In this study, left anterior descending (LAD) coronary artery was ligated to induce the CAD models in vivo, and cardiac functions were examined using echocardiography. Human umbilical vein endothelial cells (HUVEC) were subjected to H₂O₂-induced oxidative stress in vitro. The effects of DQP on CAD rat models and in vitro HUVEC were detected. Our results showed that DQP had cardio-protective effects in rat model. The intensity of capillaries in the marginal area of infarction of the rat heart was increased remarkably in DQP group, and the expression of PPARα and VEGF-2 were increased. The key enzymes involved in the transportation and intake of fatty acids, including CPT1A and CD36, both increased. In H₂O₂-induced endothelial cells injury models, DQP also showed protective roles and promoted capillary-like tube formation. DQP up-regulated key enzymes in fatty acids oxidation in H₂O₂-treated HUVEC. In addition, inhibition of CPT1A compromised the pro-angiogenic effects of DQP. In conclusion, fatty acids oxidation axis PPARα-CD36-CPT1A was involved in the pro-angiogenic roles of DQP against CAD. Cardiac CPT1A may serve as a target in therapeutic angiogenesis in clinics.

Role of amino acid metabolism in angiogenesis

The role of endothelial metabolism represents a crucial element governing the formation and the differentiation of blood vessels, termed angiogenesis. Besides glycolysis and fatty acid oxidation, endothelial cells rely on specific amino acids to proliferate, migrate, and survive. In this review we focus on the metabolism of those amino acids and the intermediates that hold an established function within angiogenesis and endothelial pathophysiology. We also discuss recent work which provides a rationale for specific amino acid-restricted diets and its beneficial effects on vascular tissues, including extending the life span and preventing the development of a variety of diseases.

Angiogenesis revisited from a metabolic perspective: role and therapeutic implications of endothelial cell metabolism

Endothelial cell (EC) metabolism has lately emerged as a novel and promising therapeutic target to block vascular dysregulation associated with diseases like cancer and blinding eye disease. Glycolysis, fatty acid oxidation (FAO) and, more recently, glutamine/asparagine metabolism emerged as key regulators of EC metabolism, able to impact angiogenesis in health and disease. ECs are highly glycolytic as they require ATP and biomass for vessel sprouting. Notably, a regulator of the glycolytic pathway, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3, controls vessel sprouting during the angiogenic switch and its inhibition in tumour ECs leads to vessel normalization, thereby reducing metastasis and ameliorating chemotherapy. Moreover, FAO promotes EC proliferation through DNA synthesis, and plays an essential role in lymphangiogenesis via epigenetic regulation of histone acetylation. Pathological angiogenesis was decreased upon blockade of carnitine palmitoyltransferase 1, a regulator of FAO in ECs. More recently, metabolism of glutamine, in conjunction with asparagine, was reported to maintain EC sprouting through TCA anaplerosis, redox homeostasis, mTOR activation and endoplasmic stress control. Inactivation or blockade of glutaminase 1, which hydrolyses glutamine into ammonia and glutamate, impairs angiogenesis in health and disease, while silencing of asparagine synthetase reduces vessel sprouting in vitro. In this review, we summarize recent insights into EC metabolism and discuss therapeutic implications of targeting EC metabolism.

Pharmacological strategies to inhibit intra-plaque angiogenesis in atherosclerosis

Atherosclerosis is a complex multifactorial disease that affects large and medium-sized arteries. Rupture of atherosclerotic plaques and subsequent acute cardiovascular complications remain a leading cause of death and morbidity in the Western world. There is a considerable difference in safety profile between a stable and a vulnerable, rupture-prone lesion. The need for plaque-stabilizing therapies is high, and for a long time the lack of a suitable animal model mimicking advanced human atherosclerotic plaques made it very difficult to make progress in this area. Evidence from human plaques indicates that intra-plaque (IP) angiogenesis promotes atherosclerosis and plaque destabilization. Although neovascularization has been widely investigated in cancer, studies on the pharmacological inhibition of this phenomenon in atherosclerosis are scarce, mainly due to the lack of an appropriate animal model. By using ApoE^-/- Fbn1^C1039G+/- mice, a novel model of vulnerable plaques, we were able to investigate the effect of pharmacological inhibition of various mechanisms of IP angiogenesis on plaque destabilization and atherogenesis. In the present review, we discuss the following potential pharmacological strategies to inhibit IP angiogenesis: (1) inhibition of vascular endothelial growth factor signalling, (2) inhibition of glycolytic flux, and (3) inhibition of fatty acid oxidation. On the long run, IP neovascularization might be applicable as a therapeutic target to induce plaque stabilization on top of lipid-lowering treatment.

Angiogenic Factors produced by Hypoxic Cells are a leading driver of Anastomoses in Sprouting Angiogenesis-a computational study

Angiogenesis - the growth of new blood vessels from a pre-existing vasculature - is key in both physiological processes and on several pathological scenarios such as cancer progression or diabetic retinopathy. For the new vascular networks to be functional, it is required that the growing sprouts merge either with an existing functional mature vessel or with another growing sprout. This process is called anastomosis. We present a systematic 2D and 3D computational study of vessel growth in a tissue to address the capability of angiogenic factor gradients to drive anastomosis formation. We consider that these growth factors are produced only by tissue cells in hypoxia, i.e. until nearby vessels merge and become capable of carrying blood and irrigating their vicinity. We demonstrate that this increased production of angiogenic factors by hypoxic cells is able to promote vessel anastomoses events in both 2D and 3D. The simulations also verify that the morphology of these networks has an increased resilience toward variations in the endothelial cell's proliferation and chemotactic response. The distribution of tissue cells and the concentration of the growth factors they produce are the major factors in determining the final morphology of the network.

A New Perspective on the Heterogeneity of Cancer Glycolysis

Tumors are dynamic metabolic systems which highly augmented metabolic fluxes and nutrient needs to support cellular proliferation and physiological function. For many years, a central hallmark of tumor metabolism has emphasized a uniformly elevated aerobic glycolysis as a critical feature of tumorigenecity. This led to extensive efforts of targeting glycolysis in human cancers. However, clinical attempts to target glycolysis and glucose metabolism have proven to be challenging. Recent advancements revealing a high degree of metabolic heterogeneity and plasticity embedded among various human cancers may paint a new picture of metabolic targeting for cancer therapies with a renewed interest in glucose metabolism. In this review, we will discuss diverse oncogenic and molecular alterations that drive distinct and heterogeneous glucose metabolism in cancers. We will also discuss a new perspective on how aberrantly altered glycolysis in response to oncogenic signaling is further influenced and remodeled by dynamic metabolic interaction with surrounding tumor-associated stromal cells.

Tumor angiogenesis revisited: Regulators and clinical implications

Since Judah Folkman hypothesized in 1971 that angiogenesis is required for solid tumor growth, numerous studies have been conducted to unravel the angiogenesis process, analyze its role in primary tumor growth, metastasis and angiogenic diseases, and to develop inhibitors of proangiogenic factors. These studies have led in 2004 to the approval of the first antiangiogenic agent (bevacizumab, a humanized antibody targeting vascular endothelial growth factor) for the treatment of patients with metastatic colorectal cancer. This approval launched great expectations for the use of antiangiogenic therapy for malignant diseases. However, these expectations have not been met and, as knowledge of blood vessel formation accumulates, many of the original paradigms no longer hold. Therefore, the regulators and clinical implications of angiogenesis need to be revisited. In this review, we discuss recently identified angiogenesis mediators and pathways, new concepts that have emerged over the past 10 years, tumor resistance and toxicity associated with the use of currently available antiangiogenic treatment and potentially new targets and/or approaches for malignant and nonmalignant neovascular diseases.

Angiogenesis in metabolic-vascular disease

Angiogenesis, literally formation of new blood vessels, is the main process through which the vascular system expands during embryonic and postnatal development. Endothelial cells, which constitute the inner lining of all blood vessels, are typically in a quiescent state in the healthy adult organism. However, in vascular and metabolic diseases, the endothelium becomes unstable and dysfunctional. The resulting tissue hypoxia may thereby induce pathological angiogenesis, which is a hallmark of disease conditions like cancer or diabetic retinopathy. However, recent evidence suggests that angiogenesis is also a major player in the context of further metabolic diseases, especially in obesity. In particular, deregulated angiogenesis is linked with adipose tissue dysfunction and insulin resistance. On the other hand, signalling pathways, such as the PI3K pathway, may regulate metabolic activities in the endothelium. Endothelial cell metabolism emerges as an important regulator of angiogenesis. This review summarises the role of angiogenesis in metabolic-vascular disease, with specific focus on the role of angiogenesis in obesity-related metabolic dysfunction and on signaling pathways, especially PI3K, linking cell metabolism to endothelial function.

The Glycolytic Enzyme PFKFB3 Is Involved in Estrogen-Mediated Angiogenesis via GPER1

The endogenous estrogen 17β-estradiol (E2) is a key factor in promoting endothelial healing and angiogenesis. Recently, proangiogenic signals including vascular endothelial growth factor and others have been shown to converge in endothelial cell metabolism. Because inhibition of the glycolytic enzyme activator phosphofructokinase-2/fructose-2,6-bisphosphatase 3 (PFKFB3) reduces pathologic angiogenesis and estrogen receptor (ER) signaling stimulates glucose uptake and glycolysis by inducing PFKFB3 in breast cancer, we hypothesized that E2 triggers angiogenesis in endothelial cells via rapid ER signaling that requires PFKFB3 as a downstream effector. We report that treatment with the selective G protein-coupled estrogen receptor (GPER1) agonist G-1 (10^-10 to 10^-7 M) mimicked the chemotactic and proangiogenic effect of E2 as measured in a number of short-term angiogenesis assays in human umbilical vein endothelial cells (HUVECs); in addition, E2 treatment upregulated PFKFB3 expression in a time- and concentration-dependent manner. Such an effect peaked at 3 hours and was also induced by G-1 and abolished by pretreatment with the GPER1 antagonist G-15 or GPER1 siRNA, consistent with engagement of membrane ER. Experiments with the PFKFB3 inhibitor 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one showed that PFKFB3 activity was required for estrogen-mediated HUVEC migration via GPER1. In conclusion, E2-induced angiogenesis was mediated at least in part by the membrane GPER1 and required upregulation of the glycolytic activator PFKFB3 in HUVECs. These findings unravel a previously unrecognized mechanism of estrogen-dependent endocrine-metabolic crosstalk in HUVECs and may have implications in angiogenesis occurring in ischemic or hypoxic tissues.

Vessel pruning or healing: endothelial metabolism as a novel target?

INTRODUCTION

Antiangiogenic drugs were originally designed to starve tumors by cutting off their vascular supply. Unfortunately, when these agents are used as monotherapy or in combination with chemotherapy, they provide only modest survival benefits in the order of weeks to months in most cancer patients. Strategies normalizing the disorganized tumor vasculature offer the potential to increase tumor perfusion and oxygenation, and to improve the efficacy of radio-, chemo- and immunotherapy, while reducing metastasis. Areas covered: This review discusses tumor vascular normalization (TVN) as an alternative strategy for anti-angiogenic cancer treatment. We summarize (pre)-clinical strategies that have been developed to normalize tumor vessels as well as their potential to enhance standard therapy. Notably, we describe how targeting endothelial cell metabolism offers new possibilities for antiangiogenic therapy through evoking TVN. Expert opinion: Several drugs targeting VEGF signaling are now clinically used for antiangiogenic cancer treatment. However, excessive blood vessel pruning impedes perfusion and causes tumor hypoxia, known to promote cancer cell dissemination and impair radio-, chemo- and immunotherapy. Normalized vessels lessen tumor hypoxia, impair cancer cell intravasation and enhance anticancer treatment. New data indicate that targeting endothelial cell metabolism is an alternative strategy of antiangiogenic cancer treatment via promotion of TVN.

Suggested Mechanisms of Tracheal Occlusion Mediated Accelerated Fetal Lung Growth: A Case for Heterogeneous Topological Zones

In this article, we report an up-to-date summary on tracheal occlusion (TO) as an approach to drive accelerated lung growth and strive to review the different maternal- and fetal-derived local and systemic signals and mechanisms that may play a significant biological role in lung growth and formation of heterogeneous topological zones following TO. Pulmonary hypoplasia is a condition whereby branching morphogenesis and embryonic pulmonary vascular development are globally affected and is classically seen in congenital diaphragmatic hernia. TO is an innovative approach aimed at driving accelerated lung growth in the most severe forms of diaphragmatic hernia and has been shown to result in improved neonatal outcomes. Currently, most research on mechanisms of TO-induced lung growth is focused on mechanical forces and is viewed from the perspective of homogeneous changes within the lung. We suggest that the key principle in understanding changes in fetal lungs after TO is taking into account formation of unique variable topological zones. Following TO, fetal lungs might temporarily look like a dynamically changing topologic mosaic with varying proliferation rates, dissimilar scale of vasculogenesis, diverse patterns of lung tissue damage, variable metabolic landscape, and different structures. The reasons for this dynamic topological mosaic pattern may include distinct degree of increased hydrostatic pressure in different parts of the lung, dissimilar degree of tissue stress/damage and responses to this damage, and incomparable patterns of altered lung zones with variable response to systemic maternal and fetal factors, among others. The local interaction between these factors and their accompanying processes in addition to the potential role of other systemic factors might lead to formation of a common vector of biological response unique to each zone. The study of the interaction between various networks formed after TO (action of mechanical forces, activation of mucosal mast cells, production and secretion of damage-associated molecular pattern substances, low-grade local pulmonary inflammation, and cardiac contraction-induced periodic agitation of lung tissue, among others) will bring us closer to an appreciation of the biological phenomenon of topological heterogeneity within the fetal lungs.