Angiogenesis最新文献

Background

Endothelial cells (ECs) of the heart proliferate and form new vessels in response to vascular endothelial growth factor (VEGF), but VEGF has not benefited the therapy of cardiac ischemia because of its side effects. Here, we explored if deletion of the vascular steady-state homeostasis maintaining Tie1 and Tie2 receptor tyrosine kinases affects the proliferation and sprouting of cardiac ECs.

Methods

We analyzed EC proliferation and histological and immunohistochemical stainings by confocal microscopy, plus scRNA and qPCR analyses of gene expression in the heart, kidneys, and lungs of Tie1^fl/fl, Tie2^fl/fl, and Tie1^fl/fl;Tie2^fl/fl mice, in which vascular endothelial cadherin-driven CreER^T2 recombinase was used to delete Tie1, Tie2 or both receptors. These analyses were also performed in mice subjected to transverse aortic constriction (TAC). Boyden chamber assays were performed to assess the migration of cultured ECs in cultures with or without TIE receptor silencing.

Results

Genetic deletion of Tie1, Tie2, or Tie1/Tie2 in mice increased significantly the proliferation of cardiac but not renal or pulmonary ECs, as measured by EdU incorporation into DNA and quantification of the cell cycle marker cyclin D1. Tie1/Tie2 or Tie2 deletion, but not Tie1 deletion alone, induced EC sprouting in coronary vasculature and expression of endothelial tip cell markers, including expression of the FOXO1-regulated Angpt2 and Esm1 genes in cardiac versus kidney or lung ECs. Consistent with these findings, silencing of TIE2, but not TIE1, in cultured ECs resulted in increased migration of ECs. Similar results were obtained in mice subjected to TAC.

Conclusion

Deletion of Tie2 alone or together with Tie1 increases the proliferation and sprouting of cardiac, but not renal or pulmonary ECs, without to neovessel formation in the heart.

Background

Vascular endothelial growth factor (VEGF) is regarded as the essential promoter of vitreoretinal vascular diseases that threaten eyesight, such as proliferative diabetic retinopathy (PDR). Therefore, VEGF is the primary therapeutic target in these diseases, but not all patients respond adequately to VEGF inhibition. This raises the question if other factors contribute to disease modulation. PDR evolves in an interplay of pathological processes including inflammation, barrier integrity loss, aberrant angiogenesis, and metabolic dysregulation. Interleukin-6 (IL-6), recognized for its pro-inflammatory properties, was the focus of this study.

Aim

Investigate IL-6 mediated angiogenic potential and disease-relevant mechanisms in the context of VEGF driven vitreoretinal disorder.

Methods

Levels of IL-6 and soluble IL-6 receptor (sIL-6R) were quantified in patient samples using ELISA. In vitro, the functional effect and downstream signaling patterns of IL-6, sIL-6R and VEGF on vascular endothelial cells were analyzed with western blot, spheroid sprouting-, migration-, seahorse assays and LC–MS/MS.

Results

Vitreous samples from PDR patients showed elevated levels of IL-6 and its corresponding soluble IL-6 receptor (sIL-6R) compared to clinical control groups. In vitro, IL-6 trans-signaling (IL-6 + sIL-6R) leads to a pro angiogenic phenotype in human vascular endothelial cells demonstrated in migration and spheroid sprouting assays, mirroring the effects of VEGF. Interestingly, IL-6 trans- and VEGF-signaling differ in their effects on barrier integrity and metabolic profile. IL-6 trans-signaling disrupts endothelial barrier function and shows an increased mitochondrial oxygen consumption rate in the Seahorse assay, as well as lower produced lactate levels compared to VEGF. Tocilizumab, an IL-6R antibody, showed additive treatment effects to anti-VEGF therapeutics regarding angiogenesis and VEGF induced metabolic drive in vitro.

Conclusion

IL-6 trans-signaling functions as an independent promoter of vitreoretinal vascular disease and therapeutic targeting of its pathway could beneficially complement current anti-VEGF treatment protocols.

Angiogenesis, the formation of new blood vessels from pre-existing vasculature, is essential for tissue homeostasis, development, and repair. Dysregulation of this tightly regulated process contributes to a wide range of diseases, including cancer, ischemic disorders, and chronic inflammatory conditions. This review focuses on the secreted frizzled-related protein (SFRP) family, a group of pivotal yet underappreciated regulators of neovascularization. We discuss the tissue-specific expression patterns, regulatory mechanisms, and functional roles of SFRPs in both physiological and pathological vascular remodeling. Particular attention is given to their interactions with key signaling pathways, including Wnt, highlighting their context-dependent effects on angiogenesis. Drawing on extensive preclinical evidence, we position SFRPs as novel regulators of vascular remodeling and explore their potential as promising targets for therapeutic intervention. This comprehensive analysis underscores the importance of further mechanistic and clinical studies to unlock the therapeutic potential of SFRPs in vascular pathologies.

The study investigates the sex-specific effects of the pluripotency factor OCT4 deficiency in endothelial cells (ECs) on angiogenesis. OCT4 is known for its role in embryonic stem cells, but we recently found that it plays a protective role in ECs during atherosclerosis. Herein, we utilized cultured mouse aortic ECs (MAECs) and several in vivo models, including skin wounding, melanoma tumor implantation, and hindlimb ischemia, to explore the role of OCT4 in angiogenesis in both male and female mice. Our findings revealed significant sexual dimorphism in wild type mice, along with sex differences in responses to OCT4 deficiency across all three in vivo models. Male mice with endothelial Oct4 knockout had faster skin wound healing, increased vascularization, and quicker blood flow recovery after hindlimb ischemia than wild-type mice. In contrast, female mice with endothelial Oct4 knockout experienced delayed wound healing, no significant change in blood flow recovery after hindlimb ischemia, and increased tumor growth. Mechanistically, MCP1, a key angiogenic chemokine, was differentially regulated in male and female Oct4 knockout compared to wild-type MAECs, suggesting OCT4-dependent regulation of MCP1 as a critical mechanism for sex differences in angiogenic responses. RNA sequencing (RNAseq) analysis revealed distinct gene expression profiles in male and female MAECs upon OCT4 deficiency. Notably, female ECs exhibited upregulation of pro-inflammatory genes, which, although modest relative to their already elevated baseline, may contribute to the enhanced tumor growth observed in mutant females. In contrast, male ECs exhibited increased expression of cell cycle- and angiogenesis-related genes, correlating with their enhanced angiogenic responses. Overall, the research provides novel insights into the sex-specific functional role of OCT4 in ECs during angiogenesis and emphasizes the need for developing sex-specific EC-targeting therapeutic strategies for cardiovascular diseases and cancer.

Objective

Clinical evidence has indicated that pressure overload-induced cardiac hypertrophy is closely linked with adverse cardiac outcomes. Endothelial dysfunction is a key contributor to the progression of cardiac hypertrophy and heart failure (HF). Although leucine-rich repeat-containing 8A (LRRC8A) serves as a critical regulator of vascular endothelial homeostasis, its functional role in pressure overload-induced pathological hypertrophy and dysfunction remains unclear. In this study, we aimed to investigate the role and mechanism of endothelial LRRC8A in pressure overload-induced pathological hypertrophy.

Methods and results

Here, we found that LRRC8A expression was markedly downregulated in hypertrophic hearts and cardiac endothelial cells (CECs) from both patients and mice. Endothelial LRRC8A knockout mice exhibited exacerbated pathological hypertrophy and dysfunction following transverse aortic constriction (TAC) surgery. Moreover, single-cell RNA sequencing (scRNA-seq) analysis revealed that LRRC8A-deficient CECs displayed downregulation of gene programs related to angiogenesis, migration, and proliferation. Consistently, endothelial LRRC8A deficiency reduced capillary density in TAC hearts in vivo and inhibited endothelial cell (EC) tube formation, migration, and proliferation in vitro. Mechanistically, LRRC8A positively regulated the VEGF-VEGFR2 axis, interacted with VEGFR2, and promoted VEGFR2 endocytosis. Therapeutically, AAV9-ICAM2-LRRC8A gene therapy restored coronary angiogenesis and ameliorated TAC-induced hypertrophy and dysfunction.

Conclusion

Our findings identify endothelial LRRC8A as a critical regulator of coronary angiogenesis in pressure overload-induced hypertrophic hearts and indicate that it could serve as a therapeutic target for cardiac hypertrophy and HF.

Graphical abstract

Precise control of cell–cell communication networks within brain neurovascular units (NVUs) promotes normal tissue physiology. Dysregulation of these networks can lead to pathologies including uncontrolled angiogenesis, endothelial barrier disruption, and intracerebral hemorrhage (ICH). The cellular and molecular mechanisms underlying ICH pathogenesis and subsequent tissue repair processes remain poorly understood. Here we employed fixed single cell RNA profiling coupled with spatial in situ gene expression profiling to characterize NVU signaling pathways associated with ICH in Itgb8/β8 integrin mutant mice. In this model, early neonatal stages of ICH were characterized by downregulation of extracellular matrix (ECM)-associated signaling factors (Adamtsl2, Htra3, and Lama4) linked to canonical TGFβ activation and signaling in endothelial cells. Conversely, the progressive resolution of ICH involved upregulation of neuroinflammatory signaling networks (Gas6 and Axl) alongside activation of iron metabolism pathway components (Hmox1, Cp, and Slc40a1) in microglia/macrophages. Integrated computational modeling identifies additional ligand-receptor signaling networks between perivascular glial cells and angiogenic endothelial cells. Collectively, these findings illuminate the molecular signaling networks that promote NVU maturation and provide novel mechanistic insights into the pathways controlling ICH pathogenesis and repair in Itgb8 mutant mice.

Background

Hydroxychloroquine (HCQ), long used for its immunomodulatory and vasculoprotective properties in autoimmune diseases such as antiphospholipid syndrome, was among the first drugs evaluated for COVID-19. Given the prominent endothelial dysfunction and coagulopathy in severe COVID-19, we investigated whether HCQ could modulate circulating biomarkers of vascular injury.

Methods

A longitudinal analysis comparing standard of care (SoC; n = 148) with HCQ plus SoC (n = 145) was conducted within the phase 3, multicenter, open-label, randomized, adaptive, controlled trial DisCoVeRy in hospitalized patients with COVID-19 (NCT04315948), which primary outcome was clinical status at day 15, measured by the WHO 7-point ordinal scale. Biomarkers of endothelial activation and coagulopathy—angiopoietin-2, P-selectin, and D-dimer—were measured on days 1, 3, 5, 8, and 11. Linear mixed-effects models assessed the influence of HCQ and baseline severity on biomarker trajectories.

Results

Severe disease at baseline was associated with higher biomarker levels: angiopoietin-2 (p < 10⁻⁵), P-selectin (p < 10⁻⁶), and D-dimer (p < 10⁻⁷). HCQ had no effect on angiopoietin-2 levels over time (0.002 95%CI: [− 0.003;0.007], p = 0.42). P-selectin increased significantly in both non-severe and severe SoC patients, but HCQ had no effect on the slope (0.005 95%CI: [− 0.001;0.012], p = 0.12). Regarding D-dimer, neither disease severity nor HCQ significantly affected the slope (− 0.004 95%CI: [− 0.016;0.009], p = 0.57 and − 0.000 95%CI: [− 0.009;0.009], p = 0.98, respectively).

Conclusions

HCQ was not found to modify the longitudinal evolution of angiopoietin-2, P-selectin, or D-dimer in hospitalized patients with COVID-19. These findings confirm the absence of vascular benefit, reinforcing evidence against HCQ’s clinical utility in COVID-19 and underscoring the need for alternative endothelial-targeted approaches.

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare autosomal dominant vascular disorder characterized by mucocutaneous telangiectasias and visceral arteriovenous malformations (AVMs), which arise due to direct connections between arteries and veins. These vascular lesions are prone to bleeding and vascular shunts, leading to recurrent epistaxis and GI bleeding, among other systemic complications. HHT is caused by heterozygous loss-of-function mutations in genes involved in the BMP9/BMP10 signaling pathway—primarily ENG, ACVRL1 (also known as ALK1), and SMAD4—which define the major HHT subtypes (HHT1, HHT2, and HHT-JP). HHT has a global prevalence of 1 in 5000 individuals, affecting approximately 1.6 million worldwide. The 15th International HHT Scientific Conference was held in Mandelieu-la-Napoule, France, bringing together over 376 attendees from around the world, including 77 trainees, to share the latest advances in HHT research and clinical care. The conference received 225 abstract submissions, of which 49 were selected for oral presentations and 176 for poster sessions. This gathering marked a significant milestone in the field, not only for its scale but also for the depth and breadth of the scientific discussions. Key highlights included new insights into AVM biology, disease mechanisms, genetic underpinnings, and emerging therapeutic strategies. In addition to oral and poster sessions, two focused workshops provided in-depth discussion on pulmonary arterial hypertension (PAH) and HHT, a rare occurrence of two disease states where treatment for one often worsens the other, and a discussion on the evolving definition of HHT and whether it should be revised in light of recent advances in research, genetic testing, and clinical evidence beyond the Curacao criteria, which were established 25 years ago. This executive summary aims to recapitulate the key scientific and clinical findings presented at the conference and to spotlight areas of continued debate and unmet need. We hope this summary will serve as a resource for experts working in the field and as an invitation for new investigators and clinicians to engage in collaborative efforts to advance the understanding and treatment of HHT.

Angiogenesis, the formation of new blood vessels from existing ones, is essential for physiological and pathological processes such as wound healing, organ development, and tumor growth. It is a tightly regulated process influenced by both intrinsic and extrinsic factors. Emerging evidence shows a connection between biological clocks that regulate physiological rhythms and angiogenesis through the modulation of angiogenic factors like vascular growth factor (Vegfa). Thus, the clock system can directly modulate the timing and efficiency of angiogenic processes. This study aimed to investigate the role of key circadian clock genes, Bmal1 and Per2, in retinal angiogenesis. Endothelial cell-specific deletion of these genes significantly impairs vessel growth, although distinct phenotypic differences emerge between the two knockout models as angiogenesis progresses. RNA-sequencing (RNA-seq) analysis of retinal endothelial cells reveals that circadian clocks predominantly influence the expression of genes involved in cell proliferation. Notably, vascular endothelial cell (VEC) proliferation is diurnally regulated and is disrupted in Bmal1 knockout animals, leading to an increase in the number of Brn3a-positive retinal ganglion cells (RGCs). These alterations are further associated with compromised retinal circuitry and function. Thus, this study uncovers critical roles for Bmal1 and Per2 in regulating retinal angiogenesis, emphasizing the importance of circadian control of cell proliferation in vascular development and retinal function.