Synthetic Fibrin-Derived Bβ15-42 Peptide Delays Thrombus Resolution in a Mouse Model

Objective: Thrombus resolution is driven by leukocyte recruitment and thrombus angiogenesis. An effective inhibition of leukocyte transmigration in vitro is mediated by naturally occurring peptide Bβ 15-42 , which is a competitive inhibitor of the interaction between the N-terminus of the fibrin beta chain and vascular endothelial cadherin. We investigated the effect of Bβ 15-42 on thrombus resolution in a murine stagnant flow venous thrombosis model and studied Bβ 15-42 levels in venous thrombus of human patients. Approach and Results: We investigated 2 mouse models of subtotal inferior vena cava ligation. In the first model, we ligated the inferior vena cava. In the second model, we additionally ligated all visible inferior vena cava side and back branches. Study groups of 8 to 12 weeks old BALB/c mice were then injected intraperitoneal twice daily with 2.4 mg/kg of Bβ 15-42 , unrelated control peptide or saline. Bβ 15-42 attenuated thrombus resolution after inferior vena cava ligation. We observed decreased numbers of thrombus macrophages and microvessels and less urokinase-type plasminogen activator expression in mice that were injected with Bβ 15-42 . Mechanistic experiments demonstrated that Bβ 15-42 blocks monocyte transmigration through an endothelial cell monolayer. Measurements of Bβ 15-42 in red clot and plasma of chronic thromboembolic pulmonary hypertension cases indicated high concentrations compared with controls. Conclusions: Our data suggest that excess of the fibrin fragment Bβ 15-42 misguides thrombus resolution, presumably by inhibiting vascular endothelial cadherin-mediated leukocyte migration during early thrombus organization.

Enhanced endothelial barrier function by monoclonal antibody activation of vascular endothelial cadherin

Excessive vascular permeability is a serious complication of many inflammatory disease conditions. We have developed monoclonal antibodies that inhibit increases in endothelial monolayer permeability induced by several signaling factors by activating VE-cadherin mediated adhesion and stabilizing cell junctions. These antibodies and/or the mechanisms they reveal may lead to important therapeutics to treat vascular leakiness and inflammation.

Pathological Angiogenesis Requires Syndecan-4 for Efficient VEGFA-Induced VE-Cadherin Internalization

Objective: VEGFA (Vascular endothelial growth factor A) and its receptor VEGFR2 (vascular endothelial growth factor receptor 2) drive angiogenesis in several pathologies, including diabetic retinopathy, wet age-related macular degeneration, and cancer. Studies suggest roles for HSPGs (heparan sulfate proteoglycans) in this process, although the nature of this involvement remains elusive. Here, we set to establish the role of the HSPG SDC4 (syndecan-4) in pathological angiogenesis. Approach and Results: We report that angiogenesis is impaired in mice null for SDC4 in models of neovascular eye disease and tumor development. Our work demonstrates that SDC4 is the only SDC whose gene expression is upregulated during pathological angiogenesis and is selectively enriched on immature vessels in retinas from diabetic retinopathy patients. Combining in vivo and tissue culture models, we identified SDC4 as a downstream mediator of functional angiogenic responses to VEGFA. We found that SDC4 resides at endothelial cell junctions, interacts with vascular endothelial cadherin, and is required for its internalization in response to VEGFA. Finally, we show that pathological angiogenic responses are inhibited in a model of wet age-related macular degeneration by targeting SDC4. Conclusions: We show that SDC4 is a downstream mediator of VEGFA-induced vascular endothelial cadherin internalization during pathological angiogenesis and a potential target for antiangiogenic therapies.

Pulmonary vascular proliferation in patients with severe COVID-19: an autopsy study

Diffuse alveolar damage and thrombi are the most common lung histopathological lesions reported in patients with severe COVID-19. Although some studies have suggested increased pulmonary angiogenesis, the presence of vascular proliferation in COVID-19 lungs has not been well characterised. Glomeruloid-like microscopic foci and/or coalescent vascular proliferations measuring up to 2 cm were present in the lung of 14 out of 16 autopsied patients. These lesions expressed CD31, CD34 and vascular endothelial cadherin. Platelet-derived growth factor receptor-β immunohistochemistry and dual immunostaining for CD34/smooth muscle actin demonstrated the presence of pericytes. These vascular alterations may contribute to the severe and refractory hypoxaemia that is common in patients with severe COVID-19.

Auraptene Enhances Junction Assembly in Cerebrovascular Endothelial Cells by Promoting Resilience to Mitochondrial Stress through Activation of Antioxidant Enzymes and mtUPR

Junctional proteins in cerebrovascular endothelial cells are essential for maintaining the barrier function of the blood-brain barrier (BBB), thus protecting the brain from the infiltration of pathogens. The present study showed that the potential therapeutic natural compound auraptene (AUR) enhances junction assembly in cerebrovascular endothelial cells by inducing antioxidant enzymes and the mitochondrial unfolded protein response (mtUPR). Treatment of mouse cerebrovascular endothelial cells with AUR enhanced the expression of junctional proteins, such as occludin, zonula occludens-1 (ZO-1) and vascular endothelial cadherin (VE-cadherin), by increasing the levels of mRNA encoding antioxidant enzymes. AUR treatment also resulted in the depolarization of mitochondrial membrane potential and activation of mtUPR. The ability of AUR to protect against ischemic conditions was further assessed using cells deprived of oxygen and glucose. Pretreatment of these cells with AUR protected against damage to junctional proteins, including occludin, claudin-5, ZO-1 and VE-cadherin, accompanied by a stress resilience response regulated by levels of ATF5, LONP1 and HSP60 mRNAs. Collectively, these results indicate that AUR promotes resilience against oxidative stress and improves junction assembly, suggesting that AUR may help maintain intact barriers in cerebrovascular endothelial cells.

Stealthy Nanoparticles Protecting Endothelium Barrier from Leakiness by Resisting the Absorption of VE-cadherin

Nanomaterial induced endothelial cells leakiness (NanoEL) is caused because nanomaterials enter the interstitial space of endothelial cells and disrupt the endothelial cell-cell interactions by interacting with vascular endothelial cadherin (VE-cad)....