von Willebrand factor (VWF) is best known for its key role in haemostasis, capturing platelets at sites of endothelial damage and acting as carrier for coagulation Factor VIII. The importance of VWF ...in haemostasis is illustrated by the fact that its deficiency and/or abnormality causes von Willebrand disease (VWD), the most frequent inherited bleeding disorder, whilst raised levels of VWF are associated with an increased risk of arterial thrombosis. VWF is synthesized in megakaryocytes and in endothelial cells from most, but not all, vascular districts. Besides the well characterized binding to Factor VIII and with platelet receptors, VWF can interact with a plethora of proteins, from extracellular matrix components to growth factors and even DNA, suggesting that VWF may influence multiple processes. Moreover, VWF is required for the formation of Weibel Palade Bodies (WPB), endothelial storage organelles which contain many vascular regulators. It is therefore likely that this large protein, critically located at sites of vascular injury, is able to influence several vascular functions. Indeed over the last two decades novel functions for VWF in the vasculature have been identified, including the ability to modulate blood vessel formation. Studies in a mouse models of severe VWF deficiency have shown constitutively enhanced vascular networks in selected tissues, and enhanced angiogenesis in Matrigel and in response to ischemia in the brain. Moreover, studies on circulating endothelial progenitors from patients with type 3 VWD and lack of VWF synthesis have shown enhanced in vitro angiogenesis. The ability of VWF to regulate angiogenesis has clinical implications for a subset of VWD patients with severe, intractable gastrointestinal (GI) bleeding due to vascular malformations, called angiodysplasia. These lesions, found in patients with congenital VWD and acquired von Willebrand syndrome (AVWS), can cause severe gastrointestinal bleeding, often unresponsive to conventional replacement therapy. Therefore, understanding the mechanisms through which VWF modulates blood vessel formation is likely to have direct implications for the treatment of these patients.
In vitro and in vivo studies indicate that VWF can regulate angiogenesis through multiple pathways. Strong candidates for this role are VWF binding partners, such as integrin αvβ3, and components of Weibel Palade bodies (WPB), such as Angiopoietin-2 and Galectin-3, whose storage is regulated by VWF. Several of these pathways converge on the master regulator of angiogenesis, also essential for maintaining endothelial homeostasis, namely the vascular endothelial growth factor (VEGF) pathway. Multiple regulators may act in concert, their relevance differing in congenital VWD vs acquired AVWS. Interestingly, recent studies in mouse models suggest that the roles of VWF may be tissue-specific. If confirmed, this will have important implications for the translational and clinical implications of these findings for patient with VWD. In summary, the finding that VWF is able to regulate blood vessel formation has opened a new area of research for this incredibly interesting and versatile protein, one which has profound implications for the treatment of patients with VWD and AVWS.
Randi:LFB: Other: Invited to one advisory board meeting 2018, Patents & Royalties, Research Funding, Speakers Bureau; Shire: Honoraria.
More people experience mucocutaneous bleeding (MCB), affecting tissues like skin and gums, than have hemophilia A or B. MCB is not understood as well as hemophilia. Common types of MCB include ...nosebleeds, bleeding gums, heavy menstrual bleeding, and digestive tract bleeding. Mucocutaneous inherited bleeding disorders include inherited platelet disorders, hereditary hemorrhagic telangiectasia (HHT), hypermobility spectrum disorders (HSD) and Ehlers-Danlos syndromes (EDS), von Willebrand Disease (VWD), and others. Diagnosing and treating MCB is complicated and sometimes medical providers dismiss the bleeding that patients report when they cannot find a medical explanation for it. Many people with mucocutaneous bleeding (PWMCB) do not receive the care they need; for example, women with VWD live with symptoms for, on average, 16 years before they are diagnosed in the US. This struggle to obtain care has important negative impacts on patients' physical and psychological health and their quality-of-life. The National Hemophilia Foundation (NHF), a large US bleeding disorders patient advocacy organization, set out to develop a National Research Blueprint for Inherited Bleeding Disorders focused on community priorities. They brought together a group of patients, providers, and researchers with MCB expertise to identify the research that would most improve the lives of PWMCB through targeted and accessible diagnostics and therapies. We report in this paper that research is needed to better understand the biology of MCB and to define the mechanisms of disease in these disorders. We also describe high priority research questions for each of the main disorders, novel therapeutics, and aging.
Excessive or abnormal mucocutaneous bleeding (MCB) may impact all aspects of the physical and psychosocial wellbeing of those who live with it (PWMCB). The evidence base for the optimal diagnosis and management of disorders such as inherited platelet disorders, hereditary hemorrhagic telangiectasia (HHT), hypermobility spectrum disorders (HSD), Ehlers-Danlos syndromes (EDS), and von Willebrand disease (VWD) remains thin with enormous potential for targeted research.
National Hemophilia Foundation and American Thrombosis and Hemostasis Network initiated the development of a National Research Blueprint for Inherited Bleeding Disorders with extensive all-stakeholder consultations to identify the priorities of people with inherited bleeding disorders and those who care for them. They recruited multidisciplinary expert working groups (WG) to distill community-identified priorities into concrete research questions and score their feasibility, impact, and risk.
WG2 detailed 38 high priority research questions concerning the biology of MCB, VWD, inherited qualitative platelet function defects, HDS/EDS, HHT, bleeding disorder of unknown cause, novel therapeutics, and aging.
Improving our understanding of the basic biology of MCB, large cohort longitudinal natural history studies, collaboration, and creative approaches to novel therapeutics will be important in maximizing the benefit of future research for the entire MCB community.
ABSTRACT
There is an urgent unmet need for human tissue bioassays to predict cytokine storm responses to biologics. Current bioassays that detect cytokine storm responses in vitro rely on endothelial ...cells, usually from umbilical veins or cell lines, cocultured with freshly isolated peripheral blood mononuclear cells (PBMCs) from healthy adult volunteers. These assays therefore comprise cells from 2 separate donors and carry the disadvantage of mismatched tissues and lack the advantage of personalized medicine. Current assays also do not fully delineate mild (such as Campath) and severe (such as TGN1412) cytokine storm‐inducing drugs. Here, we report a novel bioassay where endothelial cells grown from stem cells in the peripheral blood (blood outgrowth endothelial cells) and PBMCs from the same donor can be used to create an autologous coculture bioassay that responds by releasing a plethora of cytokines to authentic TGN1412 but only modestly to Campath and not to control antibodies such as Herceptin, Avastin, and Arzerra. This assay performed better than the traditional mixed donor assay in terms of cytokine release to TGN1412 and, thus, we suggest provides significant advancement and a definitive system by which biologics can be tested and paves the way for personalized medicine.—Reed, D. M., Paschalaki, K. E., Starke, R. D., Mohamed, N. A., Sharp, G., Fox, B., Eastwood, D., Bristow, A., Ball, C., Vessillier, S., Hansel, T. T., Thorpe, S. J., Randi, A. M., Stebbings, R., Mitchell, J. A. An autologous endothelial cell:peripheral blood mononuclear cell assay that detects cytokine storm responses to biologics. FASEB J. 29, 2595‐2602 (2015). www.fasebj.org
Genetic ablation of endothelial focal adhesion kinase (FAK) can inhibit pathological angiogenesis, suggesting that loss of endothelial FAK is sufficient to reduce neovascularization. Here we show ...that reduced stromal FAK expression in FAK-heterozygous mice unexpectedly enhances both B16F0 and CMT19T tumour growth and angiogenesis. We further demonstrate that cell proliferation and microvessel sprouting, but not migration, are increased in serum-stimulated FAK-heterozygous endothelial cells. FAK-heterozygous endothelial cells display an imbalance in FAK phosphorylation at pY397 and pY861 without changes in Pyk2 or Erk1/2 activity. By contrast, serum-stimulated phosphorylation of Akt is enhanced in FAK-heterozygous endothelial cells and these cells are more sensitive to Akt inhibition. Additionally, low doses of a pharmacological FAK inhibitor, although too low to affect FAK autophosphorylation in vitro, can enhance angiogenesis ex vivo and tumour growth in vivo. Our results highlight a potential novel role for FAK as a nonlinear, dose-dependent regulator of angiogenesis where heterozygous levels of FAK enhance angiogenesis.
Abstract Objective This study aimed to quantify functional status (FS) trajectories pre- and post-diagnosis of cancer, FS trajectories among cancer-free individuals, and factors affecting FS. ...Materials and Methods Self-reported FS, scored from 0 (worst) to 100 (best), of Atherosclerosis Risk in Communities (ARIC) Study cohort participants diagnosed with incident cancer (lung ( N = 303), breast ( N = 374), prostate ( N = 529), colorectal ( N = 228)), and cancer-free participants ( N = 11,155) over 15 years was examined. FS was evaluated in two ways: 1) until death or follow-up year 15 (Model 1) and 2) same as survivorship model except that a FS value of zero was used for assessments after death to follow-up year 15 (Model 2). Mean FS at discrete time points were used to generate FS trajectories. Differences in repeated measures of FS were assessed using linear growth models. Results Within one year after diagnosis, FS scores declined compared to the cancer-free group, except for prostate cancer. FS continued to decline beyond one year after lung or colorectal cancer diagnosis. FS was lower in all cancer groups, except prostate, compared to the cancer-free group (Model 1: lung − 4.76, breast − 2.28, colorectal − 2.55; Model 2: lung − 2.36, breast − 2.46, colorectal − 2.31). Predictors of decreased FS score independent of cancer diagnosis included low education, comorbidities, obesity, smoking, lack of health insurance, and age. Conclusion FS in all incident cancer groups declined during the first year post-diagnosis, which could be due to intensive treatments. Targeting factors related to FS declines could improve health outcomes for patients with cancer.
The interaction of transcription factors with specific DNA sequences is critical for activation of gene expression programs. In endothelial cells (EC), the transcription factor NF-κB is important in ...the switch from quiescence to activation, and is tightly controlled to avoid excessive inflammation and organ damage. Here we describe a novel mechanism that controls the activation of NF-κB in EC. The transcription factor Erg, the most highly expressed ETS member in resting EC, controls quiescence by repressing proinflammatory gene expression. Focusing on intercellular adhesion molecule 1(ICAM)-1 as a model, we identify two ETS binding sites (EBS −118 and −181) within the ICAM-1 promoter required for Erg-mediated repression. We show that Erg binds to both EBS −118 and EBS −181, the latter located within the NF-κB binding site. Interestingly, inhibition of Erg expression in quiescent EC results in increased NF-κB-dependent ICAM-1 expression, indicating that Erg represses basal NF-κB activity. Erg prevents NF-κB p65 from binding to the ICAM-1 promoter, suggesting a direct mechanism of interference. Gene set enrichment analysis of transcriptome profiles of Erg and NF-κB-dependent genes, together with chromatin immunoprecipitation (ChIP) studies, reveals that this mechanism is common to other proinflammatory genes, including cIAP-2 and IL-8. These results identify a role for Erg as a gatekeeper controlling vascular inflammation, thus providing an important barrier to protect against inappropriate endothelial activation.
Background: In quiescent endothelial cells, the transcription factor Erg regulates cell homeostasis by repressing expression of proinflammatory genes.
Results: Erg represses NF-κB p65-dependent transcription of ICAM-1, partly by inhibiting p65 binding to DNA.
Conclusion: Erg acts as a gatekeeper in quiescent endothelial cells to inhibit basal NF-κB activity.
Significance: Novel pathway controlling endothelial cell activation and inflammation.
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