Building Blood Vessels-One Rho GTPase at a Time

Tumor-induced endothelial RhoA activation mediates tumor cell transendothelial migration and metastasis

The endothelial barrier plays an active role in transendothelial tumor cell migration during metastasis, however, the endothelial regulatory elements of this step remain obscure. Here we show that endothelial RhoA activation is a determining factor during this process. Breast tumor cell-induced endothelial RhoA activation is the combined outcome of paracrine IL-8-dependent and cell-to-cell contact β 1 integrin-mediated mechanisms, with elements of this pathway correlating with clinical data. Endothelial-specific RhoA blockade or in vivo deficiency inhibited the transendothelial migration and metastatic potential of human breast tumor and three murine syngeneic tumor cell lines, similar to the pharmacological blockade of the downstream RhoA pathway. These findings highlight endothelial RhoA as a potent, universal target in the tumor microenvironment for anti-metastatic treatment of solid tumors.

Intramyocardial Sprouting Tip Cells Specify Coronary Arterialization

BACKGROUND

The elaborate patterning of coronary arteries critically supports the high metabolic activity of the beating heart. How coronary endothelial cells coordinate hierarchical vascular remodeling and achieve arteriovenous specification remains largely unknown. Understanding the molecular and cellular cues that pattern coronary arteries is crucial to develop innovative therapeutic strategies that restore functional perfusion within the ischemic heart.

METHODS

Single-cell transcriptomics and histological validation were used to delineate heterogeneous transcriptional states of the developing and mature coronary endothelium with a focus on sprouting endothelium and arterial cell specification. Genetic lineage tracing and high-resolution 3-dimensional imaging were used to characterize the origin and mechanisms of coronary angiogenic sprouting, as well as to fate-map selective endothelial lineages. Integration of single-cell transcriptomic data from ischemic adult mouse hearts and human embryonic data served to assess the conservation of transcriptional states across development, disease, and species.

RESULTS

We discover that coronary arteries originate from cells that have previously transitioned through a specific tip cell phenotype. We identify nonoverlapping intramyocardial and subepicardial tip cell populations with differential gene expression profiles and regulatory pathways. Esm1-lineage tracing confirmed that intramyocardial tip cells selectively contribute to coronary arteries and endocardial tunnels, but not veins. Notably, prearterial cells are detected from development stages to adulthood, increasingly in response to ischemic injury, and in human embryos, suggesting that tip cell-to-artery specification is a conserved mechanism.

CONCLUSIONS

A tip cell-to-artery specification mechanism drives arterialization of the intramyocardial plexus and endocardial tunnels throughout life and is reactivated upon ischemic injury. Differential sprouting programs govern the formation and specification of the venous and arterial coronary plexus.

PLEKHG1: New Potential Candidate Gene for Periventricular White Matter Abnormalities

Hypoxic-ischemic brain damage presents a significant neurological challenge, often manifesting during the perinatal period. Specifically, periventricular leukomalacia (PVL) is emerging as a notable contributor to cerebral palsy and intellectual disabilities. It compromises cerebral microcirculation, resulting in insufficient oxygen or blood flow to the periventricular region of the brain. As widely documented, these pathological conditions can be caused by several factors encompassing preterm birth (4-5% of the total cases), as well single cotwin abortion and genetic variants such as those associated with GTPase pathways. Whole exome sequencing (WES) analysis identified a de novo causative variant within the pleckstrin homology domain-containing family G member 1 (PLEKHG1) gene in a patient presenting with PVL. The PLEKHG1 gene is ubiquitously expressed, showing high expression patterns in brain tissues. PLEKHG1 is part of a family of Rho guanine nucleotide exchange factors, and the protein is essential for cell division control protein 42 (CDC42) activation in the GTPase pathway. CDC42 is a key small GTPase of the Rho-subfamily, regulating various cellular functions such as cell morphology, migration, endocytosis, and cell cycle progression. The molecular mechanism involving PLEKHG1 and CDC42 has an intriguing role in the reorientation of cells in the vascular endothelium, thus suggesting that disruption responses to mechanical stress in endothelial cells may be involved in the formation of white matter lesions. Significantly, CDC42 association with white matter abnormalities is underscored by its MIM phenotype number. In contrast, although PLEKHG1 has been recently associated with patients showing white matter hyperintensities, it currently lacks a MIM phenotype number. Additionally, in silico analyses classified the identified variant as pathogenic. Although the patient was born prematurely and subsequently to dichorionic gestation, during which its cotwin died, we suggest that the variant described can strongly contribute to PVL. The aim of the current study is to establish a plausible association between the PLEKHG1 gene and PVL.

Defining the Functional Influence of Endothelial Cell-Expressed Oncogenic Activating Mutations on Vascular Morphogenesis and Capillary Assembly

This study sought to define key molecules and signals controlling major steps in vascular morphogenesis, and how these signals regulate pericyte recruitment and pericyte-induced basement membrane deposition. The morphogenic impact of endothelial cell (EC) expression of activating mutants of Kirsten rat sarcoma virus (kRas), mitogen-activated protein kinase 1 (Mek1), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), Akt serine/threonine kinase 1 (Akt1), Ras homolog enriched in brain (Rheb) Janus kinase 2 (Jak2), or signal transducer and activator of transcription 3 (Stat3) expression versus controls was evaluated, along with EC signaling events, pharmacologic inhibitor assays, and siRNA suppression experiments. Primary stimulators of EC lumen formation included kRas, Akt1, and Mek1, whereas PIK3CA and Akt1 stimulated a specialized type of cystic lumen formation. In contrast, the key drivers of EC sprouting behavior were Jak2, Stat3, Mek1, PIK3CA, and mammalian target of rapamycin (mTor). These conclusions are further supported by pharmacologic inhibitor and siRNA suppression experiments. EC expression of active Akt1, kRas, and PIK3CA led to markedly dysregulated lumen formation coupled to strongly inhibited pericyte recruitment and basement membrane deposition. For example, activated Akt1 expression in ECs excessively stimulated lumen formation, decreased EC sprouting behavior, and showed minimal pericyte recruitment with reduced mRNA expression of platelet-derived growth factor-BB, platelet-derived growth factor-DD, and endothelin-1, critical EC-derived factors known to stimulate pericyte invasion. The study identified key signals controlling fundamental steps in capillary morphogenesis and maturation and provided mechanistic details on why EC activating mutations induced a capillary deficiency state with abnormal lumens, impaired pericyte recruitment, and basement deposition: predisposing stimuli for the development of vascular malformations.

Rhogef17: A novel target for endothelial barrier function

ARHGEF17 encodes the protein RhoGEF17, which is highly expressed in vascular endothelial cells. It is a guanine nucleotide exchange factor (GEF) that accelerates the exchange of GDP with GTP on many small GTPases through its Dbl homology (DH) domain, enabling the activation of Rho-GTPases such as RhoA, RhoB, and RhoC. Rho GTPase-regulated changes in the actin cytoskeleton and cell adhesion kinetics are the main mechanisms mediating many endothelial cell (EC) alterations, including cell morphology, migration, and division changes, which profoundly affect EC barrier function. This review focuses on ARHGEF17 expression, activation and biological functions in ECs, linking its regulation of cellular morphology, migration, mitosis and other cellular behaviors to disease onset and progression. Understanding ARHGEF17 mechanisms of action will contribute to the design of therapeutic approaches targeting RhoGEF17, a potential drug target for the treatment of various endothelium-related diseases, Such as vascular inflammation, carcinogenesis and transendothelial metastasis of tumors.

Lipocalin 10 is essential for protection against inflammation-triggered vascular leakage by activating LDL receptor-related protein 2-slingshot homologue 1 signalling pathway

AIMS

Systemic inflammation occurs commonly during many human disease settings and increases vascular permeability, leading to organ failure, and lethal outcomes. Lipocalin 10 (Lcn10), a poorly characterized member of the lipocalin family, is remarkably altered in the cardiovascular system of human patients with inflammatory conditions. Nonetheless, whether Lcn10 regulates inflammation-induced endothelial permeability remains unknown.

METHODS AND RESULTS

Systemic inflammation models were induced using mice by injection of endotoxin lipopolysaccharide (LPS) or caecal ligation and puncture (CLP) surgery. We observed that the expression of Lcn10 was dynamically altered only in endothelial cells (ECs), but not in either fibroblasts or cardiomyocytes isolated from mouse hearts following the LPS challenge or CLP surgery. Using in vitro gain- and loss-of-function approaches and an in vivo global knockout mouse model, we discovered that Lcn10 negatively regulated endothelial permeability upon inflammatory stimuli. Loss of Lcn10 augmented vascular leakage, leading to severe organ damage and higher mortality following LPS challenge, compared to wild-type controls. By contrast, overexpression of Lcn10 in ECs displayed opposite effects. A mechanistic analysis revealed that both endogenous and exogenous elevation of Lcn10 in ECs could activate slingshot homologue 1 (Ssh1)-Cofilin signalling cascade, a key axis known to control actin filament dynamics. Accordingly, a reduced formation of stress fibre and increased generation of cortical actin band were exhibited in Lcn10-ECs, when compared to controls upon endotoxin insults. Furthermore, we identified that Lcn10 interacted with LDL receptor-related protein 2 (LRP2) in ECs, which acted as an upstream factor of the Ssh1-Confilin signalling. Finally, injection of recombinant Lcn10 protein into endotoxic mice showed therapeutic effects against inflammation-induced vascular leakage.

CONCLUSION

This study identifies Lcn10 as a novel regulator of EC function and illustrates a new link in the Lcn10-LRP2-Ssh1 axis to controlling endothelial barrier integrity. Our findings may provide novel strategies for the treatment of inflammation-related diseases.

Endothelium and Subendothelial Matrix Mechanics Modulate Cancer Cell Transendothelial Migration

Cancer cell extravasation, a key step in the metastatic cascade, involves cancer cell arrest on the endothelium, transendothelial migration (TEM), followed by the invasion into the subendothelial extracellular matrix (ECM) of distant tissues. While cancer research has mostly focused on the biomechanical interactions between tumor cells (TCs) and ECM, particularly at the primary tumor site, very little is known about the mechanical properties of endothelial cells and the subendothelial ECM and how they contribute to the extravasation process. Here, an integrated experimental and theoretical framework is developed to investigate the mechanical crosstalk between TCs, endothelium and subendothelial ECM during in vitro cancer cell extravasation. It is found that cancer cell actin-rich protrusions generate complex push-pull forces to initiate and drive TEM, while transmigration success also relies on the forces generated by the endothelium. Consequently, mechanical properties of the subendothelial ECM and endothelial actomyosin contractility that mediate the endothelial forces also impact the endothelium's resistance to cancer cell transmigration. These results indicate that mechanical features of distant tissues, including force interactions between the endothelium and the subendothelial ECM, are key determinants of metastatic organotropism.

Effects of biomechanical and biochemical stimuli on angio- and vasculogenesis in a complex microvasculature-on-chip

The endothelium of blood vessels is a vital organ that reacts differently to subtle changes in stiffness and mechanical forces exerted on its environment (extracellular matrix (ECM)). Upon alteration of these biomechanical cues, endothelial cells initiate signaling pathways that govern vascular remodeling. The emerging organs-on-chip technologies allow the mimicking of complex microvasculature networks, identifying the combined or singular effects of these biomechanical or biochemical stimuli. Here, we present a microvasculature-on-chip model to investigate the singular effect of ECM stiffness and mechanical cyclic stretch on vascular development. Following two different approaches for vascular growth, the effect of ECM stiffness on sprouting angiogenesis and the effect of cyclic stretch on endothelial vasculogenesis are studied. Our results indicate that ECM hydrogel stiffness controls the size of the patterned vasculature and the density of sprouting angiogenesis. RNA sequencing shows that the cellular response to stretching is characterized by the upregulation of certain genes such as ANGPTL4+5, PDE1A, and PLEC.

In vivo dissection of Rhoa function in vascular development using zebrafish

The small monomeric GTPase RHOA acts as a master regulator of signal transduction cascades by activating effectors of cellular signaling, including the Rho-associated protein kinases ROCK1/2. Previous in vitro cell culture studies suggest that RHOA can regulate many critical aspects of vascular endothelial cell (EC) biology, including focal adhesion, stress fiber formation, and angiogenesis. However, the specific in vivo roles of RHOA during vascular development and homeostasis are still not well understood. In this study, we examine the in vivo functions of RHOA in regulating vascular development and integrity in zebrafish. We use zebrafish RHOA-ortholog (rhoaa) mutants, transgenic embryos expressing wild type, dominant negative, or constitutively active forms of rhoaa in ECs, pharmacological inhibitors of RHOA and ROCK1/2, and Rock1 and Rock2a/b dgRNP-injected zebrafish embryos to study the in vivo consequences of RHOA gain- and loss-of-function in the vascular endothelium. Our findings document roles for RHOA in vascular integrity, developmental angiogenesis, and vascular morphogenesis in vivo, showing that either too much or too little RHOA activity leads to vascular dysfunction.

Active RhoA Exerts an Inhibitory Effect on the Homeostasis and Angiogenic Capacity of Human Endothelial Cells

Background

The small GTPase RhoA (Ras homolog gene family, member A) regulates a variety of cellular processes, including cell motility, proliferation, survival, and permeability. In addition, there are reports indicating that RhoA‐ROCK (rho associated coiled‐coil containing protein kinase) activation is essential for VEGF (vascular endothelial growth factor)‐mediated angiogenesis, whereas other work suggests VEGF‐antagonistic effects of the RhoA‐ROCK axis.

Methods and Results

To elucidate this issue, we examined human umbilical vein endothelial cells and human coronary artery endothelial cells after stable overexpression (lentiviral transduction) of constitutively active (G14V/Q63L), dominant‐negative (T19N), or wild‐type RhoA using a series of in vitro angiogenesis assays (proliferation, migration, tube formation, angiogenic sprouting, endothelial cell viability) and a human umbilical vein endothelial cells xenograft assay in immune‐incompetent NOD scid gamma mice in vivo. Here, we report that expression of active and wild‐type RhoA but not dominant‐negative RhoA significantly inhibited endothelial cell proliferation, migration, tube formation, and angiogenic sprouting in vitro. Moreover, active RhoA increased endothelial cell death in vitro and decreased human umbilical vein endothelial cell‐related angiogenesis in vivo. Inhibition of RhoA by C3 transferase antagonized the inhibitory effects of RhoA and strongly enhanced VEGF‐induced angiogenic sprouting in control‐treated cells. In contrast, inhibition of RhoA effectors ROCK1/2 and LIMK1/2 (LIM domain kinase 1/2) did not significantly affect RhoA‐related effects, but increased angiogenic sprouting and migration of control‐treated cells. In agreement with these data, VEGF did not activate RhoA in human umbilical vein endothelial cells as measured by a Förster resonance energy transfer–based biosensor. Furthermore, global transcriptome and subsequent bioinformatic gene ontology enrichment analyses revealed that constitutively active RhoA induced a differentially expressed gene pattern that was enriched for gene ontology biological process terms associated with mitotic nuclear division, cell proliferation, cell motility, and cell adhesion, which included a significant decrease in VEGFR‐2 (vascular endothelial growth factor receptor 2) and NOS3 (nitric oxide synthase 3) expression.

Conclusions

Our data demonstrate that increased RhoA activity has the potential to trigger endothelial dysfunction and antiangiogenic effects independently of its well‐characterized downstream effectors ROCK and LIMK.

Trafficking in blood vessel development

Blood vessels demonstrate a multitude of complex signaling programs that work in concert to produce functional vasculature networks during development. A known, but less widely studied, area of endothelial cell regulation is vesicular trafficking, also termed sorting. After moving through the Golgi apparatus, proteins are shuttled to organelles, plugged into membranes, recycled, or degraded depending on the internal and extrinsic cues. A snapshot of these protein-sorting systems can be viewed as a trafficking signature that is not only unique to endothelial tissue, but critically important for blood vessel form and function. In this review, we will cover how vesicular trafficking impacts various aspects of angiogenesis, such as sprouting, lumen formation, vessel stabilization, and secretion, emphasizing the role of Rab GTPase family members and their various effectors.

Control of dynamic cell behaviors during angiogenesis and anastomosis by Rasip1

Organ morphogenesis is driven by a wealth of tightly orchestrated cellular behaviors, which ensure proper organ assembly and function. Many of these cell activities involve cell-cell interactions and remodeling of the F-actin cytoskeleton. Here, we analyze the requirement for Rasip1 (Ras-interacting protein 1), an endothelial-specific regulator of junctional dynamics, during blood vessel formation. Phenotype analysis of rasip1 mutants in zebrafish embryos reveals distinct functions of Rasip1 during sprouting angiogenesis, anastomosis and lumen formation. During angiogenic sprouting, loss of Rasip1 causes cell pairing defects due to a destabilization of tricellular junctions, indicating that stable tricellular junctions are essential to maintain multicellular organization within the sprout. During anastomosis, Rasip1 is required to establish a stable apical membrane compartment; rasip1 mutants display ectopic, reticulated junctions and the apical compartment is frequently collapsed. Loss of Ccm1 and Heg1 function mimics the junctional defects of rasip1 mutants. Furthermore, downregulation of ccm1 and heg1 leads to a delocalization of Rasip1 at cell junctions, indicating that junctional tethering of Rasip1 is required for its function in junction formation and stabilization during sprouting angiogenesis.

Summary:In vivo analysis of rasip1 mutants reveals multiple roles for Rasip1 during angiogenic sprouting, anastomosis and lumen formation, including stabilization of tricellular junctions to permit coordinated cell rearrangements and multicellular tube formation.

Pitavastatin stimulates retinal angiogenesis via HMG-CoA reductase-independent activation of RhoA-mediated pathways and focal adhesion

BACKGROUND

Excessive angiogenesis of the retina is a key component of irreversible causes of blindness in many ocular diseases. Pitavastatin is a cholesterol-lowering drug used to reduce the risk of cardiovascular diseases. Various studies have shown the effects of pitavastatin on angiogenesis but the conclusions are contradictory. The effects of pitavastatin on retinal angiogenesis have not been revealed. This study investigated the effects of pitavastatin at clinically relevant concentrations on retinal angiogenesis and its underlying mechanisms using retinal microvascular endothelial cells (RMECs).

METHODS

The effects of pitavastatin on retinal angiogenesis were determined using in vitro model of retinal angiogenesis, endothelial cell migration, adhesion, proliferation, and apoptosis assays. The mechanism studies were conducted using immunoblotting and stress fiber staining.

RESULTS

Pitavastatin stimulated capillary network formation of RMECs in a similar manner as vascular endothelial growth factor (VEGF) and lipopolysaccharide (LPS). Pitavastatin also increased RMEC migration, adhesion to Matrigel, growth, and survival. The combination of pitavastatin with VEGF or LPS was more effective than VEGF or LPS alone in stimulating biological activities of RMECs, suggesting that pitavastatin can enhance the stimulatory effects of VEGF and LPS on retinal angiogenesis. Pitavastatin acted on RMECs in a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase-independent manner. In contrast, pitavastatin activated pro-angiogenic microenvironment via promoting the secretion of VEGF and stimulated retinal angiogenesis via multiple mechanisms including activation of RhoA-mediated pathways, induction of focal adhesion complex formation, and activation of ERK pathway.

CONCLUSION

Our work provides a preclinical evidence on the pro-angiogenic effect of pitavastatin in retina via multiple mechanisms that are irrelevant to mevalonate pathway.

The C-type lectin CD93 controls endothelial cell migration via activation of the Rho family of small GTPases

Endothelial cell migration is essential to angiogenesis, enabling the outgrowth of new blood vessels both in physiological and pathological contexts. Migration requires the activation of several signaling pathways, the elucidation of which expands the opportunity to develop new drugs to be used in antiangiogenic therapy. In the proliferating endothelium, the interaction between the transmembrane glycoprotein CD93 and the extracellular matrix activates signaling pathways that regulate cell adhesion, migration, and vascular maturation. Here we identify a pathway, comprising CD93, the adaptor proteins Cbl and Crk, and the small GTPases Rac1, Cdc42, and RhoA, which we propose acts as a regulator of cytoskeletal movements responsible for endothelial cell migration. In this framework, phosphorylation of Cbl on tyrosine 774 leads to the interaction with Crk, which acts as a downstream integrator in the CD93-mediated signaling regulating cell polarity and migration. Moreover, confocal microscopy analyses of GTPase biosensors show that CD93 drives coordinated activation of Rho-proteins at the cell edge of migratory endothelial cells. In conclusion, together with the demonstration of the key contribution of CD93 to the migratory process in living cells, these findings suggest that the signaling triggered by CD93 converges to the activation and modulation of the Rho GTPase signaling pathways regulating cell dynamics.

MAGI1 localizes to mature focal adhesion and modulates endothelial cell adhesion, migration and angiogenesis

MAGI1 is an intracellular adaptor protein that stabilizes cell junctions and regulates epithelial and endothelial integrity. Here, we report that that in endothelial cells MAGI1 colocalizes with paxillin, β3-integrin, talin 1, tensin 3 and α-4-actinin at mature focal adhesions and actin stress fibers, and regulates their dynamics. Downregulation of MAGI1 reduces focal adhesion formation and maturation, cell spreading, actin stress fiber formation and RhoA/Rac1 activation. MAGI1 silencing increases phosphorylation of paxillin at Y118, an indicator of focal adhesion turnover. MAGI1 promotes integrin-dependent endothelial cells adhesion to ECM, reduces invasion and tubulogenesisin vitro and suppresses angiogenesis  in vivo. Our results identify MAGI1 as anovel component of focal adhesions, and regulator of focal adhesion dynamics, cell adhesion, invasion and angiogenesis.

Cellular mitosis predicts vessel stability in a mechanochemical model of sprouting angiogenesis

Angiogenesis, the formation of new vessels, occurs in both developmental and pathological contexts. Prior research has investigated vessel formation to identify cellular phenotypes and dynamics associated with angiogenic disease. One major family of proteins involved in angiogenesis are the Rho GTPases, which govern function related to cellular elongation, migration, and proliferation. Using a mechanochemical model coupling Rho GTPase activity and cellular and intercellular mechanics, we investigate the role of cellular mitosis on sprouting angiogenesis. Mitosis-GTPase synchronization was not a strong predictor of GTPase and thus vessel signaling instability, whereas the location of mitotic events was predicted to alter GTPase cycling instabilities. Our model predicts that middle stalk cells undergoing mitosis introduce irregular dynamics in GTPase cycling and may provide a source of aberrant angiogenesis. We also find that cellular and junctional tension exhibit spatial heterogeneity through the vessel, and that tension feedback, specifically in stalk cells, tends to increase the maximum forces generated in the vessel.

Chronic Empagliflozin Treatment Reduces Myocardial Infarct Size in Nondiabetic Mice Through STAT-3-Mediated Protection on Microvascular Endothelial Cells and Reduction of Oxidative Stress

Aims: Empagliflozin (EMPA) demonstrates cardioprotective effects on diabetic myocardium but its infarct-sparing effects in normoglycemia remain unspecified. We investigated the acute and chronic effect of EMPA on infarct size after ischemia-reperfusion (I/R) injury and the mechanisms of cardioprotection in nondiabetic mice. Results: Chronic oral administration of EMPA (6 weeks) reduced myocardial infarct size after 30 min/2 h I/R (26.5% ± 3.9% vs 45.8% ± 3.3% in the control group, p < 0.01). Body weight, blood pressure, glucose levels, and cardiac function remained unchanged between groups. Acute administration of EMPA 24 or 4 h before I/R did not affect infarct size. Chronic EMPA treatment led to a significant reduction of oxidative stress biomarkers. STAT-3 (signal transducer and activator of transcription 3) was activated by Y(705) phosphorylation at the 10th minute of R, but it remained unchanged at 2 h of R and in the acute administration protocols. Proteomic analysis was employed to investigate signaling intermediates and revealed that chronic EMPA treatment regulates several pathways at reperfusion, including oxidative stress and integrin-related proteins that were further evaluated. Superoxide dismutase and vascular endothelial growth factor were increased throughout reperfusion. EMPA pretreatment (24 h) increased the viability of human microvascular endothelial cells in normoxia and on 3 h hypoxia/1 h reoxygenation and reduced reactive oxygen species production. In EMPA-treated murine hearts, CD31-/VEGFR2-positive endothelial cells and the pSTAT-3(Y705) signal derived from endothelial cells were boosted at early reperfusion. Innovation: Chronic EMPA administration reduces infarct size in healthy mice via the STAT-3 pathway and increases the survival of endothelial cells. Conclusion: Chronic but not acute administration of EMPA reduces infarct size through STAT-3 activation independently of diabetes mellitus.

Effect of anti-IL17 and/or Rho-kinase inhibitor treatments on vascular remodeling induced by chronic allergic pulmonary inflammation

Background and aims:

Expansion and morphological dysregulation of the bronchial vascular network occurs in asthmatic airways. Interleukin (IL) -17 and Rho-kinase (ROCK) are known to act in inflammation control and remodeling. Modulation of Rho-kinase proteins and IL-17 may be a promising approach for the treatment of asthma through the control of angiogenesis. Our objective was to analyze the effects of treatment with anti-IL17 and/or Rho-kinase inhibitor on vascular changes in mice with chronic allergic pulmonary inflammation.

Methods:

Sixty-four BALB/c mice, with pulmonary inflammation induced by ovalbumin were treated with anti-IL17A (7.5/µg per dose, intraperitoneal) and/or Rho-kinase inhibitor (Y-27632-10 mg/kg, intranasal), 1 h before each ovalbumin challenge (22, 24, 26, and 28/days). Control animals were made to inhale saline. At the end of the protocol, lungs were removed, and morphometric analysis was performed to quantify vascular inflammatory, remodeling, and oxidative stress responses.

Results:

Anti-IL17 or Rho-kinase inhibitor reduced the number of CD4⁺, CD8⁺, dendritic cells, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, Rho-kinase 1 and 2, transforming growth factor (TGF-β), vascular endothelial growth factor (VEGF), nuclear factor (NF)-KappaB, iNOS, metalloproteinase (MMP)-9, MMP-12, metalloproteinase inhibitor-1 (TIMP-1), FOXP-3, signal transducer and activator of transcription 1 (STAT1) and phospho-STAT1-positive cells, and actin, endothelin-1, isoprostane, biglycan, decorin, fibronectin and the collagen fibers volume fraction compared with the ovalbumin group (p < 0.05). The combination treatment, when compared with anti-IL17, resulted in potentiation of decrease in the number of IL1β- and dendritic cells-positive cells. When we compared the OVA-RHO inhibitor-anti-IL17 with OVA-RHO inhibitor we found a reduction in the number of CD8⁺ and IL-17, TGF-β, and phospho-STAT1-positive cells and endothelin-1 in the vessels (p < 0.05). There was an attenuation in the number of ROCK 2-positive cells in the group with the combined treatment when compared with anti-IL17 or Rho-kinase inhibitor-treated groups (p < 0.05).

Conclusion:

We observed no difference in angiogenesis after treatment with Rho-kinase inhibitor and anti-IL17. Although the treatments did not show differences in angiogenesis, they showed differences in the markers involved in the angiogenesis process contributing to inflammation control and vascular remodeling.

The reviews of this paper are available via the supplemental material section.

Lysolipids in Vascular Development, Biology, and Disease

Membrane phospholipid metabolism forms lysophospholipids, which possess unique biochemical and biophysical properties that influence membrane structure and dynamics. However, lysophospholipids also function as ligands for G-protein-coupled receptors that influence embryonic development, postnatal physiology, and disease. The 2 most well-studied species-lysophosphatidic acid and S1P (sphingosine 1-phosphate)-are particularly relevant to vascular development, physiology, and cardiovascular diseases. This review summarizes the role of lysophosphatidic acid and S1P in vascular developmental processes, endothelial cell biology, and their roles in cardiovascular disease processes. In addition, we also point out the apparent connections between lysophospholipid biology and the Wnt (int/wingless family) pathway, an evolutionarily conserved fundamental developmental signaling system. The discovery that components of the lysophospholipid signaling system are key genetic determinants of cardiovascular disease has warranted current and future research in this field. As pharmacological approaches to modulate lysophospholipid signaling have entered the clinical sphere, new findings in this field promise to influence novel therapeutic strategies in cardiovascular diseases.

Phosphoinositide Signaling and Mechanotransduction in Cardiovascular Biology and Disease

Phosphoinositides, which are membrane-bound phospholipids, are critical signaling molecules located at the interface between the extracellular matrix, cell membrane, and cytoskeleton. Phosphoinositides are essential regulators of many biological and cellular processes, including but not limited to cell migration, proliferation, survival, and differentiation, as well as cytoskeletal rearrangements and actin dynamics. Over the years, a multitude of studies have uniquely implicated phosphoinositide signaling as being crucial in cardiovascular biology and a dominant force in the development of cardiovascular disease and its progression. Independently, the cellular transduction of mechanical forces or mechanotransduction in cardiovascular cells is widely accepted to be critical to their homeostasis and can drive aberrant cellular phenotypes and resultant cardiovascular disease. Given the versatility and diversity of phosphoinositide signaling in the cardiovascular system and the dominant regulation of cardiovascular cell functions by mechanotransduction, the molecular mechanistic overlap and extent to which these two major signaling modalities converge in cardiovascular cells remain unclear. In this review, we discuss and synthesize recent findings that rightfully connect phosphoinositide signaling to cellular mechanotransduction in the context of cardiovascular biology and disease, and we specifically focus on phosphatidylinositol-4,5-phosphate, phosphatidylinositol-4-phosphate 5-kinase, phosphatidylinositol-3,4,5-phosphate, and phosphatidylinositol 3-kinase. Throughout the review, we discuss how specific phosphoinositide subspecies have been shown to mediate biomechanically sensitive cytoskeletal remodeling in cardiovascular cells. Additionally, we discuss the direct interaction of phosphoinositides with mechanically sensitive membrane-bound ion channels in response to mechanical stimuli. Furthermore, we explore the role of phosphoinositide subspecies in association with critical downstream effectors of mechanical signaling in cardiovascular biology and disease.

Rho GTPases: Big Players in Breast Cancer Initiation, Metastasis and Therapeutic Responses

Rho GTPases, a family of the Ras GTPase superfamily, are key regulators of the actin cytoskeleton. They were originally thought to primarily affect cell migration and invasion; however, recent advances in our understanding of the biology and function of Rho GTPases have demonstrated their diverse roles within the cell, including membrane trafficking, gene transcription, migration, invasion, adhesion, survival and growth. As these processes are critically involved in cancer initiation, metastasis and therapeutic responses, it is not surprising that studies have demonstrated important roles of Rho GTPases in cancer. Although the majority of data indicates an oncogenic role of Rho GTPases, tumor suppressor functions of Rho GTPases have also been revealed, suggesting a context and cell-type specific function for Rho GTPases in cancer. This review aims to summarize recent progresses in our understanding of the regulation and functions of Rho GTPases, specifically in the context of breast cancer. The potential of Rho GTPases as therapeutic targets and prognostic tools for breast cancer patients are also discussed.

Microfluidic lumen-based systems for advancing tubular organ modeling

Microfluidic lumen-based systems are microscale models that recapitulate the anatomy and physiology of tubular organs. These technologies can mimic human pathophysiology and predict drug response, having profound implications for drug discovery and development. Herein, we review progress in the development of microfluidic lumen-based models from the 2000s to the present. The core of the review discusses models for mimicking blood vessels, the respiratory tract, the gastrointestinal tract, renal tubules, and liver sinusoids, and their application to modeling organ-specific diseases. We also highlight emerging application areas, such as the lymphatic system, and close the review discussing potential future directions.

α1AMP-Activated Protein Kinase Protects against Lipopolysaccharide-Induced Endothelial Barrier Disruption via Junctional Reinforcement and Activation of the p38 MAPK/HSP27 Pathway

Vascular hyperpermeability is a determinant factor in the pathophysiology of sepsis. While, AMP-activated protein kinase (AMPK) is known to play a role in maintaining endothelial barrier function in this condition. Therefore, we investigated the underlying molecular mechanisms of this protective effect. α1AMPK expression and/or activity was modulated in human dermal microvascular endothelial cells using either α1AMPK-targeting small interfering RNA or the direct pharmacological AMPK activator 991, prior to lipopolysaccharide (LPS) treatment. Western blotting was used to analyze the expression and/or phosphorylation of proteins that compose cellular junctions (zonula occludens-1 (ZO-1), vascular endothelial cadherin (VE-Cad), connexin 43 (Cx43)) or that regulate actin cytoskeleton (p38 MAPK; heat shock protein 27 (HSP27)). Functional endothelial permeability was assessed by in vitro Transwell assays, and quantification of cellular junctions in the plasma membrane was assessed by immunofluorescence. Actin cytoskeleton remodeling was evaluated through actin fluorescent staining. We consequently demonstrate that α1AMPK deficiency is associated with reduced expression of CX43, ZO-1, and VE-Cad, and that the drastic loss of CX43 is likely responsible for the subsequent decreased expression and localization of ZO-1 and VE-Cad in the plasma membrane. Moreover, α1AMPK activation by 991 protects against LPS-induced endothelial barrier disruption by reinforcing cortical actin cytoskeleton. This is due to a mechanism that involves the phosphorylation of p38 MAPK and HSP27, which is nonetheless independent of the small GTPase Rac1. This results in a drastic decrease of LPS-induced hyperpermeability. We conclude that α1AMPK activators that are suitable for clinical use may provide a specific therapeutic intervention that limits sepsis-induced vascular leakage.

Endothelial Progenitor Cell-Derived Extracellular Vesicles: A Novel Candidate for Regenerative Medicine and Disease Treatment

Extracellular vesicles (EVs) are a heterogeneous group of membranous structures, which can be secreted by most cell types. As a product of paracrine secretion, EVs are considered to be a regulatory mediator for intercellular communication. There are many bioactive cargos in EVs, such as proteins, lipids, and nucleic acids. As the precursor cell of vascular endothelial cells (ECs), endothelial progenitor cells (EPCs) are first discovered in peripheral blood. With the development of studies about the functions of EPCs, an increasing number of researchers focus on EPC-derived EVs (EPC-EVs). EPC-EVs exert key functions for promoting angiogenesis in regenerative medicine and show significant therapeutic effects on a variety of diseases such as circulatory diseases, kidney diseases, diabetes, bone diseases, and tissue/organ damages. This article reviews the current knowledge on the role of EPC-EVs in regenerative medicine and disease treatment, discussing the main challenges and future directions in this field.

The uPAR System as a Potential Therapeutic Target in the Diseased Eye

Dysregulation of vascular networks is characteristic of eye diseases associated with retinal cell degeneration and visual loss. Visual impairment is also the consequence of photoreceptor degeneration in inherited eye diseases with a major inflammatory component, but without angiogenic profile. Among the pathways with high impact on vascular/degenerative diseases of the eye, a central role is played by a system formed by the ligand urokinase-type plasminogen activator (uPA) and its receptor uPAR. The uPAR system, although extensively investigated in tumors, still remains a key issue in vascular diseases of the eye and even less studied in inherited retinal pathologies such as retinitis pigmantosa (RP). Its spectrum of action has been extended far beyond a classical pro-angiogenic function and has emerged as a central actor in inflammation. Preclinical studies in more prevalent eye diseases characterized by neovascular formation, as in retinopathy of prematurity, wet macular degeneration and rubeosis iridis or vasopermeability excess as in diabetic retinopathy, suggest a critical role of increased uPAR signaling indicating the potentiality of its modulation to counteract neovessel formation and microvascular dysfunction. The additional observation that the uPAR system plays a major role in RP by limiting the inflammatory cascade triggered by rod degeneration rises further questions about its role in the diseased eye.