Optimal management of hereditary hemorrhagic telangiectasia

The ENG/VEGFα Pathway Is Likely Affected by a Nonsense Variant of Endoglin (ENG)/CD105, Causing Hereditary Hemorrhagic Telangiectasia Type 1 (HHT1) in a Chinese Family

Hereditary hemorrhagic telangiectasia (HHT), also called Rendu-Osler syndrome, is a group of rare genetic diseases characterized by autosomal dominance, multisystemic vascular dysplasia, and age-related penetrance. This includes arteriovenous malformations (AVMs) in the skin, brain, lung, liver, and mucous membranes. The correlations between the phenotype and genotype for HHT are not clear. An HHT Chinese pedigree was recruited. Whole exome sequencing (WES) analysis, Sanger verification, and co-segregation were conducted. Western blotting was performed for monitoring ENG/VEGFα signaling. As a result, a nonsense, heterozygous variant for ENG/CD105: c.G1169A:p. Trp390Ter of the proband with hereditary hemorrhagic telangiectasia type 1 (HHT1) was identified, which co-segregated with the disease in the M666 pedigree. Western blotting found that, compared with the normal levels associated with non-carrier family members, the ENG protein levels in the proband showed approximately a one-half decrease (47.4% decrease), while levels of the VEGFα protein, in the proband, showed approximately a one-quarter decrease (25.6% decrease), implying that ENG haploinsufficiency, displayed in the carrier of this variant, may affect VEGFα expression downregulation. Pearson and Spearman correlation analyses further supported TGFβ/ENG/VEGFα signaling, implying ENG regulation in the blood vessels. Thus, next-generation sequencing including WES should provide an accurate strategy for gene diagnosis, therapy, genetic counseling, and clinical management for rare genetic diseases including that in HHT1 patients.

[Iron deficiency anemia in a patient with hereditary hemorrhagic telangiectasia. Case report]

Rendu-Osler-Weber disease or hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disease. It is characterized by vascular dysplasia with the formation of telangiectasias on the skin, mucous membranes of the respiratory and digestive tracts, arteriovenous malformations (AVMs) in the internal organs, which is manifested by bleeding. Diagnosis is based on Curacao criteria: recurrent and spontaneous nosebleeds, multiple telangiectases on the characteristic localizations, AVMs in one or more of the internal organs, a family history of HHT (i.e. first-degree relative who meets these same criteria for definite HHT). Therapy is aimed at preventing and stopping gastrointestinal, nosebleeds, correction of iron deficiency anemia. A promising method of therapy is the use of angiogenesis inhibitors, in particular bevacizumab. The article presents a description of a clinical case of HHT in a 49-year-old woman with telangiectisia on the mucous membrane of the tongue, gastrointestinal tract and liver AVMs.

ANG2 Blockade Diminishes Proangiogenic Cerebrovascular Defects Associated With Models of Hereditary Hemorrhagic Telangiectasia

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a vascular disorder characterized by arteriovenous malformations and blood vessel enlargements. However, there are no effective drug therapies to combat arteriovenous malformation formation in patients with HHT. Here, we aimed to address whether elevated levels of ANG2 (angiopoietin-2) in the endothelium is a conserved feature in mouse models of the 3 major forms of HHT that could be neutralized to treat brain arteriovenous malformations and associated vascular defects. In addition, we sought to identify the angiogenic molecular signature linked to HHT.

METHODS

Cerebrovascular defects, including arteriovenous malformations and increased vessel calibers, were characterized in mouse models of the 3 common forms of HHT using transcriptomic and dye injection labeling methods.

RESULTS

Comparative RNA sequencing analyses of isolated brain endothelial cells revealed a common, but unique proangiogenic transcriptional program associated with HHT. This included a consistent upregulation in cerebrovascular expression of ANG2 and downregulation of its receptor Tyr kinase with Ig and EGF homology domains (TIE2/TEK) in HHT mice compared with controls. Furthermore, in vitro experiments revealed TEK signaling activity was hampered in an HHT setting. Pharmacological blockade of ANG2 improved brain vascular pathologies in all HHT models, albeit to varying degrees. Transcriptomic profiling further indicated that ANG2 inhibition normalized the brain vasculature by impacting a subset of genes involved in angiogenesis and cell migration processes.

CONCLUSIONS

Elevation of ANG2 in the brain vasculature is a shared trait among the mouse models of the common forms of HHT. Inhibition of ANG2 activity can significantly limit or prevent brain arteriovenous malformation formation and blood vessel enlargement in HHT mice. Thus, ANG2-targeted therapies may represent a compelling approach to treat arteriovenous malformations and vascular pathologies related to all forms of HHT.

Hereditary hemorrhagic telangiectasia in a 42-year-old Ethiopian man presenting with severe anemia and high-output heart failure: A case report with literature review

Key Clinical Messages

Hereditary hemorrhagic telangiectasia (HHT), a rare hereditary disorder, can cause recurrent massive epistaxis and gastrointestinal bleeding leading to severe anemia. Early diagnosis of HHT is essential to provide timely interventional therapies.

Abstract

HHT is a rare autosomal dominant hereditary disease that results in abnormal vasculogenesis in the skin, mucous membranes, and visceral organs such as the liver, lungs, and brain. Clinical diagnosis of HHT is made using the Curacao criteria, which include recurrent spontaneous nosebleeds, mucocutaneous telangiectasias, visceral organ involvement, and first-degree family history of HHT. Here, we report a patient with HHT from Ethiopia, who presented with recurrent epistaxis and gastrointestinal bleeding, and severe anemia requiring frequent blood transfusions as well as cauterization. The presented case is a 42-year-old Black Ethiopian man with frequent hospitalization for severe anemia and high-output heart failure requiring frequent blood transfusions. His mother had bilateral epistaxis since her early adulthood. Physical examination was significant for tachycardia, pale conjunctivae, and tiny erythematous lesions over his tongue, ejection systolic murmur and peripheral edema. Laboratory investigations revealed severe anemia with iron deficiency picture. Upper gastrointestinal endoscopy showed multiple telangiectasia spots and abdominal Doppler ultrasound showed hepatic arterio-venous malformations. He received supportive management and electrocauterization of nasal, gastric, and duodenal telangiectasias. To the best of our knowledge, this is the first case of HHT to be reported from Ethiopia. High degree of suspicion and early diagnosis of HHT is essential to start preventive screening and surveillance and provide timely interventional therapies. HHT can cause recurrent massive epistaxis and gastrointestinal bleeding leading to severe anemia and high-output heart failure. In resource limited settings, selective cauterization of telangiectasia will help to control bleeding, although it does not avoid recurrent bleeding.

Osler-Weber-Rendu syndrome: A case report on a rare vascular malformation presented with lower gastrointestinal bleeding

Osler-Weber-Rendu syndrome is an uncommon vascular disorder inherited as an autosomal dominant trait with varying penetrance and expression. A multidisciplinary approach is used for a detailed diagnostic workup and management based on the patient's symptoms at presentation.

Case report: Diagnosis of hereditary hemorrhagic telangiectasia (Osler Weber Rendu Syndrome) in a 23-year-old male presented with anemia and thrombocytopenia and its response to bevacizumab

Osler Weber Rendu Syndrome (OWS) is characterized by the development of abnormally dilated blood vessels, which manifest as arteriovenous shunts (pulmonary, gastrointestinal, hepatic, and cerebral) and mucocutaneous telangiectasias (lips, tongue, and fingertips). It is an autosomal dominant disease with a defect in transforming growth factor beta superfamily genes. This defect results in increased angiogenesis and disruption of vessel wall integrity. The disease remains underreported, with occasional history of recurrent epistaxis, iron deficiency anemia, and gastrointestinal bleeding in moderate to severe cases. Diagnosis is based on clinical presentation and confirmed by genetic testing. Various local (nasal saline, air humidification, laser ablation, and electric cauterization for epistaxis and endoscopic Argon Plasma Coagulation-APC for active GI bleeding), surgical, and systemic (tranexamic acid and antiangiogenic agents like bevacizumab and thalidomide) treatment options are used depending upon disease severity. Here, we present a case with recurrent gastrointestinal bleeding refractory to endoscopic APC ablation and thalidomide and severe symptomatic anemia requiring multiple packed red cell transfusions. The patient was ultimately started on bevacizumab, to which he had a good response and has remained in remission for 8 months as of now. This case emphasizes the need to have a low threshold of suspicion to diagnose HHT and start targeted therapy like bevacizumab early on in moderate to severe cases of HHT rather than just relying on temporizing palliative measures like ablation, cauterization, and tranexamic acid.

A challenging case of anemia, respiratory failure and seizures

BACKGROUND

Hemorrhagic Hereditary Telangiectasia (HHT), or  Rendu-Osler-Weber syndrome,  is a rare genetic disorder characterized by mucocutaneous telangiectasias and visceral arteriovenous malformations.

AIM AND METHODS

We describe the case of a 64-year old woman  in which radiology was useful to interpret an apparently unexplained constellation of symptoms.

RESULTS

Brain MRI showing ischemic stroke, pulmonary angiography demonstrating arteriovenous malformations, and capsule endoscopy detecting telangiectasias in the jejunum, along with a clinical history of recurrent epistaxis, allowed us to diagnose HHT.

CONCLUSIONS

HHT is rare and difficult to diagnose. Radiology can aid the clinical suspicion. www.actabiomedica.it.

Cardiac and Hemodynamic Manifestations of Hereditary Hemorrhagic Telangiectasia

The autosomal dominant trait hereditary hemorrhagic telangiectasia (HHT) causes multiorgan dysplastic lesions of the vasculature that can activate multiple physiological cascades leading to a broad array of cardiovascular diseases. Up to 78% of patients with HHT develop hepatic arteriovenous malformations (AVMs), which cause a hyperdynamic circulatory state secondary to hepatic/portal shunting. This condition can eventually progress to high-output cardiac failure (HOCF) with continued peripheral tissue hypoxemia. Treatment for HOCF is often limited to supportive measures (diuretics and treatment of anemia); however, recent studies using systemic bevacizumab have shown promise by substantially reducing the cardiac index. In the context of liver AVMs and high cardiac output, the pulmonary vasculature can also experience high flow. Without adequate dilation of pulmonary vessels, post-capillary pulmonary hypertension can develop. Another form of pulmonary hypertension observed in HHT, pulmonary arterial hypertension, is caused by HHT-related mutations in ENG and ACVRL1 causing congestive arteriopathy. Post-capillary pathogenesis is addressed by reducing the high-output state, whereas the pre-capillary state is treated with supportive mechanisms (diuretics, oxygen) and agents targeting pulmonary vasoreactivity: endothelin-1 receptor antagonists and phosphodiesterase-5 inhibitors. If either form of pulmonary hypertension is left untreated or proves refractory and progresses, the common hemodynamic complication is right heart failure. Targeted right heart therapies involve similar strategies to those of pulmonary arterial hypertension, with several experimental approaches under study. In this review, we describe in detail the mechanisms of pathogenesis, diagnosis, and treatment of the hemodynamic complications and associated cardiovascular diseases that may arise in patients with HHT.

Hereditary Hemorrhagic Telangiectasia and Arterio-Venous Malformations—From Diagnosis to Therapeutic Challenges

Hereditary hemorrhagic telangiectasia is a rare autosomal dominant vascular disease defined by the presence of mucosal and cutaneous telangiectasia and visceral arterio-venous malformations. The latter are abnormal capillary-free direct communications between the pulmonary and systemic circulations with the following consequences: arterial hypoxemia caused by right-to-left shunts; paradoxical embolism with transient ischemic attack or stroke and brain abscess caused by the absence of the normally filtering capillary bed; and hemoptysis or hemothorax due to the rupture of the thin-walled arterio-venous malformations (particularly during pregnancy). It is frequently underdiagnosed, commonly presenting as complications from shunting through arterio-venous malformations: dyspnea, chronic bleeding, or embolism. Arterio-venous malformations are present not only in the lungs, but can also be found in the liver, central nervous system (mainly in the brain), nasal mucosa, or the gastrointestinal tract. The first choice of therapy is embolization of the afferent arteries of the arterio-venous malformations, a minimally invasive procedure with a high efficacy, a low morbidity, and low mortality. Other therapeutic modalities are surgery (resection) or stereotactic radiosurgery (using radiation). Routine screening for arterio-venous malformations is indicated in patients diagnosed with this condition and can prevent severe complications such as acute hemorrhages, brain abscesses, or strokes. Clinicians should provide a long-term follow-up for patients with arterio-venous malformations, in an effort to detect their growth or reperfusion in case of previously treated malformations. In spite of two experts’ consensuses, it still possesses multiple therapeutic challenges for physicians, as several aspects regarding the screening and management of arterio-venous malformations still remain controversial. Multidisciplinary teams are especially useful in complex cases.

Childhood stroke

Stroke is an important cause of neurological morbidity in children; most survivors have permanent neurological deficits that affect the remainder of their life. Stroke in childhood, the focus of this Primer, is distinguished from perinatal stroke, defined as stroke before 29 days of age, because of its unique pathogenesis reflecting the maternal-fetal unit. Although approximately 15% of strokes in adults are haemorrhagic, half of incident strokes in children are haemorrhagic and half are ischaemic. The causes of childhood stroke are distinct from those in adults. Urgent brain imaging is essential to confirm the stroke diagnosis and guide decisions about hyperacute therapies. Secondary stroke prevention strongly depends on the underlying aetiology. While the past decade has seen substantial advances in paediatric stroke research, the quality of evidence for interventions, such as the rapid reperfusion therapies that have revolutionized arterial ischaemic stroke care in adults, remains low. Substantial time delays in diagnosis and treatment continue to challenge best possible care. Effective primary stroke prevention strategies in children with sickle cell disease represent a major success, yet barriers to implementation persist. The multidisciplinary members of the International Pediatric Stroke Organization are coordinating global efforts to tackle these challenges and improve the outcomes in children with cerebrovascular disease.

[Hereditary hemorrhagic telangiectasia (Rendu-Osler syndrome)]

The analysis of publications is carried out and current data concerning the etiology, pathogenesis, diagnosis, and principles of treatment of hereditary hemorrhagic telangiectasia are presented.

Predictors of heart failure symptoms in hereditary hemorrhagic telangiectasia patients with hepatic arteriovenous malformations

BACKGROUND

Hepatic arteriovenous malformations (AVMs) in hereditary hemorrhagic telangiectasia (HHT) patients are most commonly hepatic artery to hepatic venous shunts which can result in high-output heart failure. This condition can be debilitating and is a leading cause of liver transplantation in HHT patients. However, it is not known what characteristics can discriminate between asymptomatic patients and those who will develop heart failure symptoms.

RESULTS

176 patients with HHT were evaluated with computed tomography angiography (CTA) between April 2004 and February 2019 at our HHT Center of Excellence. 63/176 (35.8%) patients were found to have hepatic AVMs on CTA. 18 of these patients were excluded because of the presence of another condition which could confound evaluation of heart failure symptoms. In the remaining 45 patients included in our cohort, 25/45 (55.6%) patients were classified as asymptomatic and 20/45 (44.4%) were classified as symptomatic, and these groups were compared. In symptomatic patients, mean common hepatic artery (CHA) diameter was significantly higher (11.1 versus 8.4 mm) and mean hemoglobin levels were significantly lower (10.7 vs 12.6 g/dL). A stepwise multiple logistic regression analysis demonstrated that both CHA diameter and hemoglobin level were independent predictors of heart failure symptoms with ORs of 2.554 (95% CI 1.372-4.754) and 0.489 (95% CI 0.299-0.799), respectively. The receiver operator characteristic (ROC) curve of our analysis demonstrated an AUC of 0.906 (95% CI 0.816-0.996), sensitivity 80.0% (95% CI 55.7-93.4%), and specificity 75.0% (95% CI 52.9-89.4%).

CONCLUSIONS

CTA is an effective and easily reproducible method to evaluate hepatic involvement of HHT. Utilizing CTA, clinical, and laboratory data we determined CHA diameter and hemoglobin level were independent predictors of heart failure symptoms.

Zebrafish Vascular Mural Cell Biology: Recent Advances, Development, and Functions

Recruitment of mural cells to the vascular wall is essential for forming the vasculature as well as maintaining proper vascular functions. In recent years, zebrafish genetic tools for mural cell biology have improved substantially. Fluorescently labeled zebrafish mural cell reporter lines enable us to study, with higher spatiotemporal resolution than ever, the processes of mural cell development from their progenitors. Furthermore, recent phenotypic analysis of platelet-derived growth factor beta mutant zebrafish revealed well-conserved organotypic mural cell development and functions in vertebrates with the unique features of zebrafish. However, comprehensive reviews of zebrafish mural cells are lacking. Therefore, herein, we highlight recent advances in zebrafish mural cell tools. We also summarize the fundamental features of zebrafish mural cell development, especially at early stages, and functions.

Sclerotherapy on Demand with Polidocanol to Treat HHT Nosebleeds

Epistaxis is the most prevalent clinical symptom in Hereditary Haemorrhagic Telangiectasia (HHT), causing anaemia and decreasing the quality of life (QOL). Since 2013, in Hospital Universitario Fundación Alcorcón, more than 150 HHT patients have been treated by nose sclerotherapy on demand. This study shows the results of 105 patients treated with sclerotherapy between 2017 and 2019. HHT-ESS (epistaxis severity score) was used to measure the severity and frequency of epistaxis. QOL was determined before and after treatment by EuroQol-5D (EQ-5D) and the visual analogue scale (VAS) on the health condition. According to HHT-ESS before treatment, 22 patients presented mild, 35 moderate, and 47 severe epistaxes. Sclerotherapy significantly decreased the frequency and severity of epistaxis, with a significant drop of HHT-ESS in 4.6 points, from 6.23 ± 2.3 to 1.64 ± 1.6. Furthermore, the QOL significantly improved, the EQ-5D scale raised from 0.7 ± 0.26 pre- to 0.92 ± 0.16 post-treatment (p < 0.05). Additionally, VAS mean value showed a significant increase from 4.38 ± 2.4 to 8.35 ± 1.2. The QOL improvement was correlated with the ESS decrease. In conclusion, this study shows that on-demand sclerotherapy at the office significantly reduces HHT epistaxis as well as improved the patients' QOL.

Management of Refractory Gastrointestinal Bleeding in Hereditary Hemorrhagic Telangiectasia with Bevacizumab

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder resulting in vascular malformations of several organs including the pulmonary, cerebral, and gastrointestinal systems. One sequela is recurrent gastrointestinal (GI) bleeding. Bevacizumab (Bev) is emerging as an effective treatment of recurrent gastrointestinal bleeding in HHT. Bev is a recombinant monoclonal antibody that inhibits vascular endothelial growth factor (VEGF), an integral part of angiogenesis.

NAPG mutation in family members with hereditary hemorrhagic telangiectasia in China

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a disease characterized by arteriovenous malformations in the skin and mucous membranes. We enrolled a large pedigree comprising 32 living members, and screened for mutations responsible for HHT.

METHODS

We performed whole-exome sequencing to identify novel mutations in the pedigree after excluding three previously reported HHT-related genes using Sanger sequencing. We then performed in silico functional analysis of candidate mutations that were obtained using a variant filtering strategy to identify mutations responsible for HHT.

RESULTS

After screening the HHT-related genes, activin A receptor-like type 1 (ACVRL1), endoglin (ENG), and SMAD family member 4 (SMAD4), we did not detect any co-segregated mutations in this pedigree. Whole-exome sequencing analysis of 7 members and Sanger sequencing analysis of 16 additional members identified a mutation (c.784A > G) in the NSF attachment protein gamma (NAPG) gene that co-segregated with the disease. Functional prediction showed that the mutation was deleterious and might change the conformational stability of the NAPG protein.

CONCLUSIONS

NAPG c.784A > G may potentially lead to HHT. These results expand the current understanding of the genetic contributions to HHT pathogenesis.

Diagnosis and endovascular management of pulmonary arteriovenous malformations

Pulmonary arteriovenous malformations (PAVM) are abnormal communication of a branch of the pulmonary artery and pulmonary vein circumventing the intervening pulmonary capillaries. This results in a right-to-left (R-L) shunt and its related manifestations, which include hampered gas exchange leading to hypoxaemia, dyspnoea, paradoxical emboli leading to stroke, cerebral abscess, myocardial infarction and pulmonary haemorrhage due to rupture of the PAVM. Endovascular transcatheter embolization of the feeding vessels with coils or occlusion devices is the current standard care of treatment and preferred treatment modality. The articles aim to provide insights into the current trends in diagnosis, the current recommendations, approach and management options for patients with PAVM.

Topical Propranolol Improves Epistaxis Control in Hereditary Hemorrhagic Telangiectasia (HHT): A Randomized Double-Blind Placebo-Controlled Trial

Epistaxis is a common debilitating manifestation in hereditary hemorrhagic telangiectasia (HHT), due to mucocutaneous telangiectases. The epistaxis can be difficult to control despite available treatments. Dysregulated angiogenesis has been shown to be associated with telangiectases formation. Topical propranolol has demonstrated antiangiogenic properties. We performed a two-phase study, i.e., a double-blind placebo-controlled phase, followed by an open-label phase. The aim of the study was assessment of safety and efficacy of nasal propranolol gel in HHT-related epistaxis. Twenty participants with moderate-severe HHT-related epistaxis were randomized to eight weeks of propranolol gel 1.5%, or placebo 0.5 cc, applied to each nostril twice daily; and continued propranolol for eight weeks in an open-label study. For the propranolol group, the epistaxis severity score (ESS) improved significantly (-2.03 ± 1.7 as compared with -0.35 ± 0.68 for the placebo group, p = 0.009); hemoglobin levels improved significantly (10.5 ± 2.6 to 11.4 ± 2.02 g/dL, p = 0.009); and intravenous iron and blood transfusion requirement decreased. The change in nasal endoscopy findings was not significant. During the open-label period, the ESS score improved significantly in the former placebo group (-1.99 ± 1.41, p = 0.005). The most common adverse event was nasal mucosa burning sensation. No cardiovascular events were reported. Our results suggest that topical propranolol gel is safe and effective in HHT-related epistaxis.

Optimizing the Interventional Approach for Embolization of Pulmonary Arteriovenous Malformations in Patients With Osler-Weber-Rendu Syndrome

Techniques in vascular and interventional radiology are adapted to the ever-evolving clinical challenges that interventional operators face. In the case of rare diseases, supporting literature that guides an operator’s plan for intervention is limited. As a result, published case reports and series can be utilized to direct future intervention and potentially help others tasked with similar clinical scenarios. The proceeding case offers an interventional solution to a clinical manifestation of an otherwise rare disease, Osler-Weber-Rendu (OWR) syndrome. The supporting literature for techniques in embolization of pulmonary arteriovenous malformations (AVMs) in OWR syndrome is limited due to disease rarity. Therefore, the objective of the following case is to offer clinical insights on how to perform this procedure successfully and critique methods previously utilized.

Pulmonary arteriovenous malformation in a pediatric patient with epistaxis and hypoxemia

Hereditary hemorrhagic telangiectasia (HHT; also known as Osler-Weber-Rendu syndrome) is an inherited vascular disorder with a spectrum of clinical manifestations depending on lesion distribution. Epistaxis, mucocutaneous telangiectasia, and gastrointestinal bleeding are most common. Patients with pulmonary arteriovenous malformations are at serious risk of cerebral embolic stroke and abscess due to paradoxical embolism, indicating the need for early diagnosis and intervention. Herein, we report a 14-year-old boy who presented to his pediatrician's office with hypoxemia and personal history of epistaxis, family history of HHT, and radiologic workup demonstrating pulmonary and cerebral arteriovenous malformations. He was diagnosed with HHT and treated by endovascular embolization.

Genetic Diagnosis of Hereditary Hemorrhagic Telangiectasia: Four Novel Pathogenic Variations in Turkish Patients

Aims:

Hereditary hemorrhagic telangiectasia is an autosomal dominant disorder characterized by telangiectasia, epistaxis, and vascular malformations. Pathogenic mutations were found in ENG, AVCRL1, SMAD4, and GDF genes. In this study, we present our database of patients with hereditary hemorrhagic telangiectasia regarding the phenotype-genotype relations and discuss two novel ENG gene pathogenic variations in two unrelated families.

Methods:

Next Generation Sequencing analysis was performed on the peripheral blood of nine patients with hereditary hemorrhagic telangiectasia in four unrelated families. All patients were diagnosed with hereditary hemorrhagic telangiectasia according to the Curaçao criteria. Data on treatment and screenings of visceral involvement were recorded from files.

Results:

We have found a pathogenic variation in either the ENG or ACVRL1 gene in each family. Two novel pathogenic variations in the ENG gene, including NM_000118.3 (ENG): c.416delC (p.P139fs*24) and NM_000118.3(ENG): c.1139dupT (p.Leu380PhefsTer16), were found in the same family. The NM_000020.2(ACVRL1): c.1298C>T (p.Pro433Leu) pathogenic variation in the ACVRL1 gene in our first family and a novel heterozygous likely pathogenic NM_000020.2(ACVRL1): c.95T>C (p.Val32Ala) variation was found in our second family. Seven of the nine patients were treated with thalidomide for controlling bleeding episodes. All patients responded to thalidomide. In one patient, the response to thalidomide was lost and switched to bevacizumab.

Conclusion:

In hereditary hemorrhagic telangiectasia, certain types of mutations correlate with disease phenotypes and with next generation sequencing methods. New pathogenic variations can be revealed, which might help manage patients with hereditary hemorrhagic telangiectasia.

Systemic bevacizumab for high-output cardiac failure in hereditary hemorrhagic telangiectasia: an international survey of HHT centers

Background

Systemic bevacizumab is a novel targeted anti-angiogenic therapy for high-output cardiac failure (HOCF) in hereditary hemorrhagic telangiectasia (HHT) but published data is limited. This survey-based study measured physician-reported safety, effectiveness and current treatment practices for systemic bevacizumab in HHT-HOCF.

Methods

A 27-item survey was sent to center directors of 31 international HHT Centers of Excellence.

Results

Response rate was 74% with centers reporting 150 total patients receiving systemic bevacizumab for HHT-HOCF. Approximately two-thirds of centers had treated ≥5 patients. All centers utilize a 5 mg/kg dose for induction treatment and most administer 6 doses (range, 4–6) every 2 weeks, although maintenance regimens varied considerably. Center directors reported bevacizumab to be effective, with 55% reporting significant improvement in cardiac index and HOCF symptoms in most patients treated with bevacizumab, although normalization of cardiac parameters was uncommon. Adverse events were uncommon with three-quarters of centers reporting adverse event rates < 10%. Discontinuation for adverse events or ineffectiveness was rare. Bevacizumab was typically administered by hematologists and pulmonologists (50 and 39% of centers, respectively), with highly variable thresholds for initiation. Although half the centers reported difficulty with the insurance approval process, 70% of centers were ultimately able to obtain coverage for most or all of their patients.

Conclusions

Systemic bevacizumab is a widely-used therapy for HHT-HOCF with reasonable safety and effectiveness. HHT centers appear to vary considerably in maintenance treatment practices and disease severity thresholds for initiation of bevacizumab in HHT-related HOCF.

Rendu-Osler-Weber disease: a gastroenterologist's perspective

Hereditary hemorrhagic teleangectasia (HHT, or Rendu-Osler-Weber disease) is a rare inherited syndrome, characterized by arterio-venous malformations (AVMs or Telangiectasia). The most important and common manifestation is nose bleeds (epistaxis). The telangiectasias (small AVMs) are most evident on the lips, tongue, buccal mucosa, face, chest, and fingers, however; large arterio-venous malformations can also occur in the lungs, liver, pancreas, or brain. Telangiectasias in the upper gastrointestinal tract are known to occur, however data regarding possible small-bowel involvement is limited due to technical difficulties in visualizing the entire gastrointestinal tract. The occurrence of AVMs in the stomach and small bowel can result in chronic bleeding and anaemia. Less frequently, this may occur due to bleeding from oesophageal varices, as patients with HHT can develop hepatic parenchymal AVMs or vascular shunts which cause hepatic cirrhosis and portal hypertension. Gastroenterologists have a crucial role in the management of these patients, however difficulties remain in the detection and management of complications of HHT in the gastrointestinal tract.

Diagnostic yield of capsule endoscopy for small bowel arteriovenous malformations in patients with hereditary hemorrhagic telangiectasia: a systematic review and meta-analysis

Background and study aims  Small bowel arteriovenous malformations (AVMs) pose a bleeding risk and have traditionally been diagnosed by invasive enteroscopic procedures in patients with hereditary hemorrhagic telangiectasia (HHT). Capsule endoscopy (CE) is emerging as a safe and non-invasive alternative for small intestinal evaluation, but its diagnostic yield and utility in diagnosing small bowel AVMs in HHT patients are understudied. The aim of this study was to meta-analyze the utility of CE for diagnosing AVMs in HHT patients. Methods  A meta-analysis and systematic review of the literature on CE in HHT patients identified in the PubMed, EMBASE, Scopus, and Cochrane databases from inception to March 2018 were conducted. Summary effects were estimated using a random effects model. Results  After applying exclusion criteria, five studies (n = 124 patients) were eligible for meta-analysis. The pooled diagnostic yield for visualization of small bowel AVMs by CE was 77.0 % (95 % CI 65.8 - 85.4 %, P  < 0.001). Conclusions  CE has a good diagnostic yield for small bowel AVMs in HHT. It can be regarded as a sufficient, noninvasive diagnostic modality for identifying small bowel AVMs in HHT patients.

Peri-arterial specification of vascular mural cells from naïve mesenchyme requires Notch signaling

Mural cells (MCs) are essential for blood vessel stability and function; however, the mechanisms that regulate MC development remain incompletely understood, in particular those involved in MC specification. Here, we investigated the first steps of MC formation in zebrafish using transgenic reporters. Using pdgfrb and abcc9 reporters, we show that the onset of expression of abcc9, a pericyte marker in adult mice and zebrafish, occurs almost coincidentally with an increment in pdgfrb expression in peri-arterial mesenchymal cells, suggesting that these transcriptional changes mark the specification of MC lineage cells from naïve pdgfrb ^low mesenchymal cells. The emergence of peri-arterial pdgfrb ^high MCs required Notch signaling. We found that pdgfrb-positive cells express notch2 in addition to notch3, and although depletion of notch2 or notch3 failed to block MC emergence, embryos depleted of both notch2 and notch3 lost mesoderm- as well as neural crest-derived pdgfrb ^high MCs. Using reporters that read out Notch signaling and Notch2 receptor cleavage, we show that Notch activation in the mesenchyme precedes specification into pdgfrb ^high MCs. Taken together, these results show that Notch signaling is necessary for peri-arterial MC specification.

Bone morphogenetic protein receptor signal transduction in human disease

Bone morphogenetic proteins (BMPs) are secreted cytokines that were initially discovered on the basis of their ability to induce bone. Several decades of research have now established that these proteins function in a large variety of physiopathological processes. There are about 15 BMP family members, which signal via three transmembrane type II receptors and four transmembrane type I receptors. Mechanistically, BMP binding leads to phosphorylation of the type I receptor by the type II receptor. This activated heteromeric complex triggers intracellular signaling that is initiated by phosphorylation of receptor‐regulated SMAD1, 5, and 8 (also termed R‐SMADs). Activated R‐SMADs form heteromeric complexes with SMAD4, which engage in specific transcriptional responses. There is convergence along the signaling pathway and, besides the canonical SMAD pathway, BMP‐receptor activation can also induce non‐SMAD signaling. Each step in the pathway is fine‐tuned by positive and negative regulation and crosstalk with other signaling pathways. For example, ligand bioavailability for the receptor can be regulated by ligand‐binding proteins that sequester the ligand from interacting with receptors. Accessory co‐receptors, also known as BMP type III receptors, lack intrinsic enzymatic activity but enhance BMP signaling by presenting ligands to receptors. In this review, we discuss the role of BMP receptor signaling and how corruption of this pathway contributes to cardiovascular and musculoskeletal diseases and cancer. We describe pharmacological tools to interrogate the function of BMP receptor signaling in specific biological processes and focus on how these agents can be used as drugs to inhibit or activate the function of the receptor, thereby normalizing dysregulated BMP signaling. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

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.

The clinical characteristics and long-term prognosis of pulmonary arterial hypertension associated with hereditary hemorrhagic telangiectasia

Pulmonary arterial hypertension (PAH) is a severe complication of hereditary hemorrhagic telangiectasia (HHT); however, little is known about its clinical characteristics and prognosis. Nine newly diagnosed HHT-PAH patients were prospectively recruited between October 2007 and January 2016 and were followed up every half-year. Eighteen idiopathic pulmonary arterial hypertension (IPAH) patients, matched with HHT-PAH patients on mean pulmonary arterial pressure, pulmonary capillary wedge pressure, pulmonary vascular resistance, cardiac index, and World Health Organization (WHO) functional class (FC), were recruited. The clinical characteristics of HHT-PAH patients were described and the prognosis of these two cohorts were compared. Of HHT-PAH patients, 55.56% were WHO FC III. Kaplan–Meier survival analysis showed one- and three-year survival rates of HHT-PAH patients were 77.8% and 53.3% respectively, which were worse than matched IPAH patients (log rank: P = 0.047). HHT-PAH patients had higher red cell distribution width (14.88 ± 2.93% versus 13.19 ± 0.83%, P = 0.031), larger right ventricular anteroposterior diameter (34.67 ± 6.67 mm versus 28.56 ± 6.35 mm, P = 0.029), and lower mean corpuscular hemoglobin concentration (317.38 ± 17.71 g/L versus 335.72 ± 14.68 g/L, P = 0.011) than matched IPAH patients. Multivariate Cox proportional hazards regression analyses showed baseline total bilirubin independently predicted the mortality of HHT-PAH after adjusting by age, cardiac index, mixed venous oxygen saturation, or serum uric acid. HHT-PAH patients may have a worse prognosis than matched IPAH patients. Baseline total bilirubin may be a promising predictor for the long-term prognosis in HHT-PAH patients.

Intra-venous bevacizumab in hereditary hemorrhagic telangiectasia (HHT): A retrospective study of 46 patients

Background

Bevacizumab, an anti-VEGF monoclonal antibody, has recently emerged as a new option for severe forms of hereditary hemorrhagic telangiectasia (HHT). Its utilization in this orphan disease has rapidly spread despite the lack of randomized trials and international guidelines. The objective of this study is to report the main clinical data (baseline characteristics, dose schedule, efficacy, adverse events and deaths) of HHT patients treated by intravenous bevacizumab in France.

Methods

Retrospective observational study of HHT patients treated with bevacizumab for a severe form of the disease in the 14 centers of the French HHT network.

Results

Forty-six patients (median age: 68 years) were treated between March 2009 and May 2015. Ten patients were treated for high output cardiac failure, 20 patients for severe hemorrhages and 16 for both indications. The standard protocol (6 infusions of 5mg/kg every 2 weeks) was initially used in 89% of the cases but diverse strategies were subsequently applied. A clinical improvement was noted by the referent physician for 74% of the patients with a median effect’s duration of 6 months. Wound healing complications led to 2 amputations. Arthralgia/arthritis and arterial hypertension occurred in 5 patients each. One third of the patients were dead at the time of the final update, coherently with age and the poor prognosis of these highly symptomatic patients.

Conclusion

Intravenous bevacizumab seems to provide a clinical benefice in severe HHT patients. Precautions concerning wound healing and vascular pathologies must be respected. Prospective double blinded versus placebo trials are needed.

Topical propranolol improves epistaxis in patients with hereditary hemorrhagic telangiectasia - a preliminary report

Background

Severe epistaxis is often difficult to control in patients with hereditary hemorrhagic telangiectasia (HHT). Propranolol has been shown to have antiangiogenic properties in vitro and in vivo and is commonly used to treat hemangiomas. We present our experience with topical nasal propranolol for the treatment of moderate to severe epistaxis in patients with HHT.

Methods

Retrospective case series. Six patients with HHT were treated with 0.5 cm³ of 1.5% propranolol gel, applied to each nostril twice daily for at least 12 weeks. Outcome measures were epistaxis severity score (ESS), hemoglobin level, and number of blood transfusions prior to and while on treatment. Local and systemic side effects were recorded.

Results

The mean duration of treatment was 30 ± 5.6 weeks. A significant improvement in the ESS was found in all patients, with a mean decrease from 6.4 ± 2.1 at treatment onset to 3.5 ± 1.7 at 12 weeks (p = 0.028). Hemoglobin level increased significantly from 8.4 ± 3.1 to 11.0 ± 1.8 g/dL at 12 weeks (p = 0.043). The mean number of blood transfusions decreased from 4.5 ± 4.9 before treatment to 2.5 ± 2.9 at 12 weeks and 0.3 ± 0.8 at 24 weeks, but the difference did not reach statistical significance (p = 0.109 for both). No significant side effects of treatment were recorded.

Conclusions

These preliminary results suggest that topical propranolol may be effective for the treatment of epistaxis in patients with HHT. A prospective controlled trial is required to confirm our findings.

Nintedanib as a novel treatment option in hereditary haemorrhagic telangiectasia

A 70-year-old patient with known hereditary haemorrhagictelangiectasia (HHT) was seen regularly in our outpatient clinic. He underwent multiple therapeutical interventions, including both surgical and medical, for the treatment of recurrent epistaxis without sustained success. Due to a concurrent diagnosis of idiopathic pulmonary fibrosis, treatment with the tyrosine kinase inhibitor nintedanib was initiated, after which point the patient reported a dramatic and unanticipated improvement in his epistaxis and skin telangiectasia. On the basis of this case report, we propose that nintedanib may be a potential treatment option for refractory epistaxis in HHT.

Hereditary hemorrhagic telangiectasia and pregnancy: potential adverse events and pregnancy outcomes

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant condition with a prevalence of ~1 in 5,000 individuals. The pathophysiology of this condition centers on the lack of capillary beds between arterioles and venules, leading to direct contact between these vessels. This results in telangiectases on characteristic locations such as the face, fingers, mouth, and nasal mucosa. Visceral arteriovenous malformations (AVMs) are also observed in many patients, and these are most commonly seen in the brain, gastrointestinal tract, and lungs. Liver AVMs are present in many patients with HHT, though these individuals are usually asymptomatic; however, liver AVMs may lead to serious complications, such as high output cardiac failure. Diagnosis of HHT hinges upon fulfilling three out of four criteria: family history of the condition, mucocutaneous telangiectases, spontaneous and recurrent episodes of epistaxis, and visceral AVMs. Management is guided by international consensus guidelines and targets patients’ specific AVMs. Prognosis is good, though severe complications including hemorrhage and paradoxical emboli are possible. Novel therapeutics are being explored in clinical trials; bevacizumab and pazopanib inhibit angiogenesis, while thalidomide bolsters blood vessel maturation. Pregnancy in patients with HHT is considered high risk. While the majority of pregnancies proceed normally, severe complications have been reported in some women with HHT; these include heart failure, intracranial hemorrhage, pulmonary hemorrhage, and stroke. Such complications occur most often in the second and third trimesters when maternal changes such as peripheral vasodilation and increased cardiac output are at their maximum. Awareness of the diagnosis of HHT has been associated with improved outcomes in pregnancy. Management guidelines for pregnant patients with HHT are reviewed.

Clarification of mural cell coverage of vascular endothelial cells by live imaging of zebrafish

Mural cells (MCs) consisting of vascular smooth muscle cells and pericytes cover the endothelial cells (ECs) to regulate vascular stability and homeostasis. Here, we clarified the mechanism by which MCs develop and cover ECs by generating transgenic zebrafish lines that allow live imaging of MCs and by lineage tracing in vivo To cover cranial vessels, MCs derived from either neural crest cells or mesoderm emerged around the preformed EC tubes, proliferated and migrated along EC tubes. During their migration, the MCs moved forward by extending their processes along the inter-EC junctions, suggesting a role for inter-EC junctions as a scaffold for MC migration. In the trunk vasculature, MCs derived from mesoderm covered the ventral side of the dorsal aorta (DA), but not the posterior cardinal vein. Furthermore, the MCs migrating from the DA or emerging around intersegmental vessels (ISVs) preferentially covered arterial ISVs rather than venous ISVs, indicating that MCs mostly cover arteries during vascular development. Thus, live imaging and lineage tracing enabled us to clarify precisely how MCs cover the EC tubes and to identify the origins of MCs.

Mononuclear cells and vascular repair in HHT

Hereditary hemorrhagic telangiectasia (HHT) or Rendu–Osler–Weber disease is a rare genetic vascular disorder known for its endothelial dysplasia causing arteriovenous malformations and severe bleedings. HHT-1 and HHT-2 are the most prevalent variants and are caused by heterozygous mutations in endoglin and activin receptor-like kinase 1, respectively. An undervalued aspect of the disease is that HHT patients experience persistent inflammation. Although endothelial and mural cells have been the main research focus trying to unravel the mechanism behind the disease, wound healing is a process with a delicate balance between inflammatory and vascular cells. Inflammatory cells are part of the mononuclear cells (MNCs) fraction, and can, next to eliciting an immune response, also have angiogenic potential. This biphasic effect of MNC can hold a promising mechanism to further elucidate treatment strategies for HHT patients. Before MNC are able to contribute to repair, they need to home to and retain in ischemic and damaged tissue. Directed migration (homing) of MNCs following tissue damage is regulated by the stromal cell derived factor 1 (SDF1). MNCs that express the C-X-C chemokine receptor 4 (CXCR4) migrate toward the tightly regulated gradient of SDF1. This directed migration of monocytes and lymphocytes can be inhibited by dipeptidyl peptidase 4 (DPP4). Interestingly, MNC of HHT patients express elevated levels of DPP4 and show impaired homing toward damaged tissue. Impaired homing capacity of the MNCs might therefore contribute to the impaired angiogenesis and tissue repair observed in HHT patients. This review summarizes recent studies regarding the role of MNCs in the etiology of HHT and vascular repair, and evaluates the efficacy of DPP4 inhibition in tissue integrity and repair.