Endoglin deficiency impairs VEGFR2 but not FGFR1 or TIE2 activation and alters VEGF-mediated cellular responses in human primary endothelial cells.

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disease characterized by vascular dysplasia. Mutations of the endoglin (ENG) gene that encodes a co-receptor of the transforming growth factor ß1 signaling pathway cause type I HHT. ENG is primarily expressed in endothelial cells (ECs), but its interaction with other key angiogenic pathways to control angiogenesis has not been well addressed. The aim of this study is to investigate ENG interplay with VEGFR2, FGFR1 and TIE2 in primary human ECs. ENG was knocked-down with siRNA in human umbilical vein ECs (HUVECs) and human lung microvascular ECs (HMVEC-L). Gene expression was measured by RT-qPCR and Western blotting. Cell signaling pathway activation was analyzed by detecting phosphor-ERK and phosphor-AKT levels. Cell migration and apoptosis were assessed using the Boyden chamber assay and the CCK-8 Kit, respectively. Loss of ENG in HUVECs led to significantly reduced expression of VEGFR2 but not TIE2 or FGFR1, which was also confirmed in HMVEC-L. HUVECs lacking ENG had significantly lower levels of active Rac1 and a substantial reduction of the transcription factor Sp1, an activator of VEGFR2 transcription, in nuclei. Furthermore, VEGF- but not bFGF- or angiopoietin-1-induced phosphor-ERK and phosphor-AKT were suppressed in ENG deficient HUVECs. Functional analysis revealed that ENG knockdown inhibited cell migratory but enhanced anti-apoptotic activity induced by VEGF. In contrast, bFGF, angiopoietin-1 and -2 induced HUVEC migration and anti-apoptotic activities were not affected by ENG knockdown. In conclusion, ENG deficiency alters the VEGF/VEGFR2 pathway, which may play a role in HHT pathogenesis.

Homozygous GDF2 nonsense mutations result in a loss of circulating BMP9 and BMP10 and are associated with either PAH or an "HHT-like" syndrome in children.

BACKGROUND: Disrupted endothelial BMP9/10 signaling may contribute to the pathophysiology of both hereditary hemorrhagic telangiectasia (HHT) and pulmonary arterial hypertension (PAH), yet loss of circulating BMP9 has not been confirmed in individuals with ultra-rare homozygous GDF2 (BMP9 gene) nonsense mutations. We studied two pediatric patients homozygous for GDF2 (BMP9 gene) nonsense mutations: one with PAH (c.[76C>T];[76C>T] or p.[Gln26Ter];[Gln26Ter] and a new individual with pulmonary arteriovenous malformations (PAVMs; c.[835G>T];[835G>T] or p.[Glu279Ter];[Glu279Ter]); both with facial telangiectases. METHODS: Plasma samples were assayed for BMP9 and BMP10 by ELISA. In parallel, serum BMP activity was assayed using an endothelial BRE-luciferase reporter cell line (HMEC1-BRE). Proteins were expressed for assessment of secretion and processing. RESULTS: Plasma levels of both BMP9 and BMP10 were undetectable in the two homozygous index cases and this corresponded to low serum-derived endothelial BMP activity in the patients. Measured BMP9 and BMP10 levels were reduced in the asymptomatic heterozygous p.[Glu279Ter] parents, but serum activity was normal. Although expression studies suggested alternate translation can be initiated at Met57 in the p.[Gln26Ter] mutant, this does not result in secretion of functional BMP9. CONCLUSION: Collectively, these data show that homozygous GDF2 mutations, leading to a loss of circulating BMP9 and BMP10, can cause either pediatric PAH and/or "HHT-like" telangiectases and PAVMs. Although patients reported to date have manifestations that overlap with those of HHT, none meet the Curaçao criteria for HHT and seem distinct from HHT in terms of the location and appearance of telangiectases, and a tendency for tiny, diffuse PAVMs.

Hereditary haemorrhagic telangiectasia and pregnancy: a review of the literature.

BACKGROUND: Hereditary haemorrhagic telangiectasia (HHT) is a dominantly inherited genetic vascular disorder that has prevalence of 1:5000 to 1:8000, and which is characterised by recurrent epistaxis, cutaneous telangiectasia, and arteriovenous malformations (AVMs) that affect many organs including the lungs, gastrointestinal tract, liver, and central nervous system. The aim here was to carry out a review of the literature on HHT complications during pregnancy in order to guide management decisions. MAIN BODY: A literature review was carried out to analyse all publications on complications that occurred during pregnancy in women with HHT. The PubMed/Medline and Scopus databases were searched. The complications observed in HHT women during pregnancy were then described. The authors identified 5 case series and 31 case reports that describe the evolution of 1577 pregnancies in 630 women with HHT. The overall maternal death rate described in the case series was estimated at 1.0% of pregnancies in the case series and 2 maternal deaths occurred in 31 pregnancy case reports. Severe maternal complications occurred in 2.7 to 6.8% of pregnancies in the case series. Severe complications occurred mostly in the second and third trimester in non-diagnosed and non-screened HHT patients. Severe complications were related to visceral involvement. The most frequent complications were related to pulmonary arteriovenous malformations (PAVMs) (haemothorax (n = 10), haemoptysis (n = 4), and severe hypoxaemia (n = 3)). Neurological complications were related to PAVMs in one case (right to left shunt) and to cerebral arteriovenous malformations (CAVM) and intracranial haemorrhage in 2 cases. Complications were related to hepatic arteriovenous malformations (HAVMs) in 8 cases (acutely decompensated heart failure due to hepatic involvement (n = 1), dyspnoea related to heart failure (n = 5), and hepatobiliary necrosis (n = 2)). CONCLUSION: Based on the literature review, most pregnancies in HHT women occur normally. However, these pregnancies should be considered high-risk, given the potential life-threatening events related to AVM rupture. Furthermore, there is currently no international consensus regarding the medical follow-up of pregnancy in women with HHT and the aim here was to carry out a review of the literature in order to guide screening and management decisions for this rare disease.

[A Case of Ruptured Cerebral Arteriovenous Malformation Associated with Hereditary Hemorrhagic Telangiectasia].

BACKGROUND: Patients with hereditary hemorrhagic telangiectasia(HHT)are known to have high rates of cerebral arteriovenous malformations(AVMs). Compared to patients with sporadic AVMs, patients with HHT are less likely to present with ruptured AVMs. CASE REPORT: A 14-year-old male patient presented with headache that had lasted for 2 days. CT revealed an intracerebral hemorrhage in the right parietal lobe, and enhanced CT revealed an AVM in the upper part of the hematoma. The size of the nidus was 20 mm, and its feeders were the right superior internal parietal artery and a branch of the anterior cerebral artery. In addition, the AVM had no deep drainer. We also found another AVM in the right temporal lobe and identified telangiectasia of the nose using digital subtraction angiography. We suspected HHT and performed whole body CT, which revealed an arteriovenous fistula in the right lung and a hematoma-like lesion in the spleen. Thus, we diagnosed the patient with HHT. His ruptured AVM was removed electively. CONCLUSION: We report a case of HHT that presented as an intracerebral hemorrhage in a patient. Based on our case study findings, it is necessary to perform long-term follow-up not only for brain AVMs but also for visceral vascular malformations in such patients, as well as perform HHT screening for families. Although such cases are rare, some features of HHT must be considered to accurately diagnose suspected HHT.

Hereditary hemorrhagic telangiectasia: diagnosis and management from the hematologist's perspective.

Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is an autosomal dominant disorder that causes abnormal blood vessel formation. The diagnosis of hereditary hemorrhagic telangiectasia is clinical, based on the Curaçao criteria. Genetic mutations that have been identified include ENG, ACVRL1/ALK1, and MADH4/SMAD4, among others. Patients with HHT may have telangiectasias and arteriovenous malformations in various organs and suffer from many complications including bleeding, anemia, iron deficiency, and high-output heart failure. Families with the same mutation exhibit considerable phenotypic variation. Optimal treatment is best delivered via a multidisciplinary approach with appropriate diagnosis, screening and local and/or systemic management of lesions. Anti-angiogenic agents such as bevacizumab have emerged as a promising systemic therapy in reducing bleeding complications but are not curative. Other pharmacological agents include iron supplementation, antifibrinolytics and hormonal treatment. This review discusses the biology of HHT, management issues that face the practising hematologist, and considerations of future directions in HHT treatment.

Bone Morphogenetic Proteins in Vascular Homeostasis and Disease.

It is well established that control of vascular morphogenesis and homeostasis is regulated by vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), Delta-like 4 (Dll4), angiopoietin, and ephrin signaling. It has become clear that signaling by bone morphogenetic proteins (BMPs), which have a long history of studies in bone and early heart development, are also essential for regulating vascular function. Indeed, mutations that cause deregulated BMP signaling are linked to two human vascular diseases, hereditary hemorrhagic telangiectasia and pulmonary arterial hypertension. These observations are corroborated by data obtained with vascular cells in cell culture and in mouse models. BMPs are required for normal endothelial cell differentiation and for venous/arterial and lymphatic specification. In adult life, BMP signaling orchestrates neo-angiogenesis as well as vascular inflammation, remodeling, and calcification responses to shear and oxidative stress. This review emphasizes the pivotal role of BMPs in the vascular system, based on studies of mouse models and human vascular disorders.

TGF-ß Signaling in Control of Cardiovascular Function.

Genetic studies in animals and humans indicate that gene mutations that functionally perturb transforming growth factor ß (TGF-ß) signaling are linked to specific hereditary vascular syndromes, including Osler-Rendu-Weber disease or hereditary hemorrhagic telangiectasia and Marfan syndrome. Disturbed TGF-ß signaling can also cause nonhereditary disorders like atherosclerosis and cardiac fibrosis. Accordingly, cell culture studies using endothelial cells or smooth muscle cells (SMCs), cultured alone or together in two- or three-dimensional cell culture assays, on plastic or embedded in matrix, have shown that TGF-ß has a pivotal effect on endothelial and SMC proliferation, differentiation, migration, tube formation, and sprouting. Moreover, TGF-ß can stimulate endothelial-to-mesenchymal transition, a process shown to be of key importance in heart valve cushion formation and in various pathological vascular processes. Here, we discuss the roles of TGF-ß in vasculogenesis, angiogenesis, and lymphangiogenesis and the deregulation of TGF-ß signaling in cardiovascular diseases.

A case of hereditary hemorrhagic telangiectasia with hepatic encephalopathy due to portal hepatic venous shunt.

An 86-year-old male who was able to perform all activities of daily living (ADL) was diagnosed with hereditary hemorrhagic telangiectasia (HHT) at 70 years of age. Following his diagnosis, he had been receiving treatment at our hospital. After the sudden onset of a consciousness disorder, he was admitted to our hospital's emergency department with asterixis, a high serum ammonia level, and hepatic encephalopathy. After angiography, he was diagnosed with hepatic encephalopathy due to portal hepatic venous shunts. HHT is characterized by abnormal blood vessel construction and the formation of peripheral vasodilatation and shunt blood vessels. Although rare, portal hepatic venous shunts may sometimes cause hepatic encephalopathy. The extent of this shunt increases with age. As Japan is an increasingly aging society, the number of HHT patients with hepatic encephalopathy is likely to increase markedly in the future.

Enfermedad de Rendu Osler Weber: presentación de un caso / Rendu Osler Weber disease: one case report

Fundamento: la telangiectasia hemorrágica hereditaria o enfermedad de Rendu-Osler-Weber es una enfermedad autosómica dominante caracterizada por la presencia de múltiples telangiectasias en piel y mucosas, asociadas a malformaciones arteriovenosas de distintos órganos, incluidos pulmones, sistema gastrointestinal y sistema nervioso central. Su pronóstico es incierto, con un diagnóstico y tratamiento precoz es posible mejorar la calidad de vida del paciente y lograr una expectativa de vida similar a la de la población general.Objetivo: presentar un caso con el diagnóstico de telangiectasia hemorrágica hereditaria.Caso Clínico: paciente femenina de 64 años de edad con diagnóstico de telangiectasia hemorrágica hace 17 años, con episodios de epistaxis frecuente, antecedentes familiares de la enfermedad (padre, tíos paternos y hermanos), que ingresa en el servicio de cuidados intermedios con cuadro de epistaxis y manifestaciones clínicas de anemia aguda, lesiones nodulares en manos, dedos y pabellón auricular, con telangiectasias en la lengua.Conclusiones: la telangiectasia hemorrágica hereditaria es una enfermedad poco frecuente pero existen reportes de casos a nivel mundia(AU)

Background: hereditary haemorrhagic telangiectasia (HHT) or Rendu Osler Weber Sickness is a dominant autosomic illness characterized by the presence of multiple telangiectasias on skin and mucus, associated to arterovenous malformations in different organs, including lungs, central nervous system and gastrointestinal system. Its prognosis is uncertain. It is possible to improve the quality of life by diagnosing and treating it early, therefore a life expectancy similar to the general population can be reached.Objetive: to present a case with a diagnosis of HHT.Clinical case: A sixty-four-year-old female patient with a diagnosis of HHT 17 years ago, with episodes of frequent epistaxis and a family history of HHT (father, uncles on the father´s side and brothers) is admitted to the ICU with clinical manifestations, acute anemia and nodule lesions on her hands, fingers and auricular pavillion, with telangiectasias on the tongue.Conclusion: HHT is not a common illness but there are cases reported all over the world(AU)

Bevacizumab in the treatment of hereditary hemorrhagic telangiectasia.

INTRODUCTION: Hereditary hemorrhagic telangiectasia (HHT) is a rare multisystem vascular disorder characterized by epistaxis, mucocutaneous telangiectases and visceral arteriovenous malformations predisposing to shunting and hemorrhage. Angiogenesis has been implicated in the pathogenesis of HHT and therefore angiogenesis inhibitors appear to be the most promising agents. A literature search was performed to identify all articles reporting bevacizumab , a recombinant humanized monoclonal antibody that inhibits vascular endothelial growth factor (VEGF). We focused on the HHT pathogenesis, mechanism of action of the drug, its impact on the HHT symptoms and safety profile. AREAS COVERED: Systemic intravenous administration of bevacizumab improves the frequency and intensity of epistaxis, gastrointestinal (GI) bleeding episodes and liver arteriovenous malformations consequences. The safety profile of the systematic administration of the drug appears to be excellent with hypertension as the unique adverse effect reported so far. Its intranasal administration significantly decreases frequency and severity of nosebleeds and blood transfusion requirements. EXPERT OPINION: In the absence of randomized controlled trials in HHT, criteria of selecting patients and formal recommendations for treatment are lacking. For life-threatening epistaxis requiring blood transfusion, topical treatment with bevacizumab may be beneficial. Systemic treatment with bevacizumab is promising in symptomatic patients with organ involvement and life-threatening conditions.

Telangiectasia hemorrágica hereditaria: aspectos otorrinolaringologías / Hereditary hemorrhagic telangiectasia: ENT aspects

La telangiectasia hemorrágica hereditaria es una displasia vascular multisistémica caracterizada por el desarrollo de telangiectasias mucocutáneas y malformaciones arteriovenosas viscerales. Una de sus manifestaciones clínicas más frecuentes es la epistaxis recurrente, que se presenta en más del 90% de los pacientes, por lo que el otorrinolarin-gólogo debiera estar familiarizado con el diagnóstico y manejo de esta patología. Debido al carácter genético de la enfermedad, el manejo del sangrado nasal en estos pacientes es difícil. Existen diversas alternativas terapéuticas, farmacológicas y quirúrgicas, descritas para disminuir el número y gravedad de los episodios de epistaxis.

Hereditary hemorrhagic telangiectasia is a multisystemic vascular dysplasia, characterized by the development of mucocutaneoustelangiectasias and visceral arteriovenous malformations. One of its most frequent clinical manifestations is recurrent epistaxis, presenting in up to 90%% of these patients, so the otorhinolaryngologist should be familiarized with its diagnosis and management. Due to the genetic character of this disease, the management of nasal bleeding in these patients is difficult. There are several therapeutic alternatives, both pharmacological and surgical, described to decrease the number and severity of the episodes of epistaxis.

Interaction between alk1 and blood flow in the development of arteriovenous malformations.

Arteriovenous malformations (AVMs) are fragile direct connections between arteries and veins that arise during times of active angiogenesis. To understand the etiology of AVMs and the role of blood flow in their development, we analyzed AVM development in zebrafish embryos harboring a mutation in activin receptor-like kinase I (alk1), which encodes a TGFß family type I receptor implicated in the human vascular disorder hereditary hemorrhagic telangiectasia type 2 (HHT2). Our analyses demonstrate that increases in arterial caliber, which stem in part from increased cell number and in part from decreased cell density, precede AVM development, and that AVMs represent enlargement and stabilization of normally transient arteriovenous connections. Whereas initial increases in endothelial cell number are independent of blood flow, later increases, as well as AVMs, are dependent on flow. Furthermore, we demonstrate that alk1 expression requires blood flow, and despite normal levels of shear stress, some flow-responsive genes are dysregulated in alk1 mutant arterial endothelial cells. Taken together, our results suggest that Alk1 plays a role in transducing hemodynamic forces into a biochemical signal required to limit nascent vessel caliber, and support a novel two-step model for HHT-associated AVM development in which pathological arterial enlargement and consequent altered blood flow precipitate a flow-dependent adaptive response involving retention of normally transient arteriovenous connections, thereby generating AVMs.

Hereditary hemorrhagic telangiectasia: rare cause of pulmonary hypertension?

A 73-year-old woman was admitted to the emergency room with predominantly right-sided heart failure and anemia. Following clinical and imagiological evaluation, a diagnosis of pulmonary hypertension (PH) associated with Hereditary Hemorrhagic Telangiectasia (HHT) was confirmed. The initial response to bosentan plus sildenafil was good, including improvement in functional class and reduction of edema, allowing her to be discharged. Unfortunately, the patient died, due to her underlying condition, before the effects of the combination treatment could be fully assessed. PH should be considered in patients with HTT and screening for pulmonary hypertension should be performed in these patients and their relatives.

Hereditary hemorrhagic telangiectasia: from molecular biology to patient care.

SUMMARY: Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder characterized by severe and recurrent nosebleeds, mucocutaneous telangiectases, and, in some cases, life-threatening visceral arteriovenous malformations of various types, including pulmonary, hepatic, cerebral, and spinal. Gastrointestinal telangiectases are frequent and may cause severe bleeding. HHT type 1 results from mutations in ENG on chromosome 9 (coding for endoglin), and HHT type 2 results from mutations in ACVRL1 on chromosome 12 (coding for activin receptor-like kinase 1). Mutations of either of these two genes account for most clinical cases. In addition, mutations in MADH4 (encoding SMAD4), which cause a juvenile polyposis/HHT overlap syndrome, have been described, and recently, an HHT3 locus on chromosome 5 (5q31.3-5q32) has been reported. The mutated genes in HHT encode proteins that modulate transforming growth factor-beta superfamily signaling in vascular endothelial cells. Management of patients has changed considerably in the last 20 years, in terms of both treatment and the prevention of complications. The goal of this review was to describe the underlying molecular and cellular physiopathology, explore clinical and genetic diagnostic strategies for HHT, and present clinical management recommendations in order to treat symptomatic disease and to screen for vascular malformations.

Telangiectasia hereditária hemorrágica: causa rara de hipertensão pulmonar? / Hereditary hemorrhagic telangiectasia: rare cause of pulmonary hypertension?

Uma mulher de 73 anos foi admitida ao Pronto-Socorro com insuficiência cardíaca predominantemente direita e anemia. Após avaliação clínica e imagenológica, um diagnóstico de hipertensão pulmonar (HP) associado com telangiectasia hemorrágica hereditária (THH) foi confirmado. A resposta inicial à terapia com bosentan mais sildenafil foi boa, incluindo melhora na Classe Funcional e redução do edema, permitindo que ela recebesse alta hospitalar. Infelizmente, a paciente faleceu devido à sua condição básica, antes que o efeito do tratamento combinado pudesse ser completamente avaliado. A HP deve ser considerada em pacientes com THH e o screening para HP deve ser conduzido nesses pacientes e em seus familiares.

A 73-year-old woman was admitted to the emergency room with predominantly right-sided heart failure and anemia. Following clinical and imagiological evaluation, a diagnosis of pulmonary hypertension (PH) associated with Hereditary Hemorrhagic Telangiectasia (HHT) was confirmed. The initial response to bosentan plus sildenafil was good, including improvement in functional class and reduction of edema, allowing her to be discharged. Unfortunately, the patient died, due to her underlying condition, before the effects of the combination treatment could be fully assessed. PH should be considered in patients with HTT and screening for pulmonary hypertension should be performed in these patients and their relatives.

A newborn with hereditary haemorrhagic telangiectasia and an unusually severe phenotype.

UNLABELLED: Hereditary haemorrhagic telangiectasia (HHT), associated with arteriovenous malformations, is a genetic disease of the vascular system with a frequency of approx. 1:10,000. Genetic diagnosis serves to identify individuals at risk of developing the disease and is a useful tool for genetic counselling purposes. QUESTIONS UNDER STUDY: Here we report on a child presenting severe arteriovenous malformations leading to heart failure. Her mother and grandmother present fewer symptoms of hereditary haemorrhagic telangiectasia. In this study we identify the cause of HHT in the family. METHODS: Clinical examination, PCR, DNA sequencing, quantitative PCR, Southern blot, xray, ultrasound, cardiac catheterisation and angiocardiography. RESULTS: Initially the sequence variant in c.392C>T in the endoglin gene was detected in the grandmother, but not in other affected family members. Further analyses revealed a deletion of exon 1 of endoglin, segregating with the phenotype. CONCLUSIONS: This report points out the need for careful evaluation of molecular genetic findings, particularly in diseases with highly variable phenotype.

Hereditary hemorrhagic telangiectasia. Genetics, pathogenesis, clinical manifestation and management.

Hereditary hemorrhagic telangiectasia HHT, Morbus Osler or Osler-Weber-Rendu syndrome OMIM 187300, is an autosomal dominant disorder characterized by epistaxis, telangiectasia, multi-systemic vascular dysplasia and clinical presentation of wide variation. The pathogenesis involves dilated post-capillary venules or telangiectases in the mucus membrane of various organs as well as larger arteriovenous malformations. Genetic heterogeneity of HHT is confirmed; 2 disease loci, ACVRL1 and ENG genes, have been identified and characterized. The 2 major types of the disease, HHT1 and HHT2, are attributed to mutations in the ENG and ACVRL1 genes. ENG and ACVRL1 genes code for proteins, namely endoglin and activin-receptor-like kinase 1 ALK-1, which are members of the TGF-beta receptor family, are essential for maintaining vascular integrity. Another gene has been implicated in HHT; the HHT3 locus linked to chromosome 5. In the last 2 decades, the genetics, pathogenesis, clinical manifestations and management of HHT have been extensively researched. At this stage, it is deemed appropriate to review the wealth of information accumulated on the topic. Better understanding of the functions of endoglin, ALK-1, and other proteins involved in the pathogenesis of HHT should facilitate better management of patients with this disorder.