How to manage patients with hereditary haemorrhagic telangiectasia

Generation of a Syngeneic Heterozygous ACVRL1(wt/mut) Knockout iPS Cell Line for the In Vitro Study of HHT2-Associated Angiogenesis

Hereditary hemorrhagic telangiectasia (HHT) type 2 is an autosomal dominant disease in which one allele of the ACVRL1 gene is mutated. Patients exhibit disturbances in TGF-beta/BMP-dependent angiogenesis and, clinically, often present with severe nosebleeds as well as a reduced quality of life. The aim of our study was to use CRISPR/Cas9 to knockout ACVRL1 in normal induced pluripotent stem cells (iPSCs) and evaluate the effects on TGF-beta- and BMP-related gene expression as well as angiogenesis. The CRISPR/Cas9 knockout of the ACVRL1 gene was carried out in previously characterized wild-type (ACVRL1^wt/wt) iPSCs. An HHT type 2 iPS cell line was generated via a single-allele knockout (ACVRL1^wt/mut) in wild-type (ACVRL1^wt/wt) iPSCs, resulting in a heterozygous 17 bp frameshift deletion in the ACVRL1 gene [NG_009549.1:g.13707_13723del; NM_000020.3:c.1137_1153del]. After the generation of embryoid bodies (EBs), endothelial differentiation was induced via adding 4 ng/mL BMP4, 2% B27, and 10 ng/mL VEGF. Endothelial differentiation was monitored via immunocytochemistry. An analysis of 151 TGF-beta/BMP-related genes was performed via RT-qPCR through the use of mRNA derived from single iPS cell cultures as well as endothelial cells derived from EBs after endothelial differentiation. Differential TGF-beta/BMP gene expression was observed between ACVRL1^wt/wt and ACVRL1^wt/mut iPSCs as well as endothelial cells. EBs derived from CRISPR/Cas9-designed ACVRL1 mutant HHT type 2 iPSCs, together with their isogenic wild-type iPSC counterparts, can serve as valuable resources for HHT type 2 in vitro studies.

[Hereditary hemorrhagic telangiectasia]

Hereditary hemorrhagic telangiectasia, also known as Rendu-Osler - Weber disease, is a rare, autosomal dominant vascular disease, with prevalence of 1/5,000. The condition is characterized by muco-cutaneous telangiectasias, which are responsible for a hemorrhagic syndrome of variable severity, as well as arteriovenous malformations (AVMs) appearing in the lungs, the liver, and the nervous system. They can be the source of shunts, which may be associated with high morbidity (neurological ischemic stroke, brain abscess, high-output heart failure, biliary ischemia…). It is therefore crucial to establish a clinical diagnosis using the Curaçao criteria or molecular diagnosis based on genetic analysis of the ENG, ACVRL1, SMAD4 and GDF2 genes. In most cases, multidisciplinary management allows patients to have normal life expectancy. Advances in interventional radiology and better understanding of the pathophysiology of angiogenesis have resulted in improved therapeutic management. Anti-angiogenic treatments, such as bevacizumab (BVZ, an anti-VEGF antibody), have proven to be effective in cases involving bleeding complications and severe liver damage with cardiac repercussions. Other anti-angiogenic agents are currently being investigated, including tyrosine kinase inhibitors.

Functional Alterations Involved in Increased Bleeding in Hereditary Hemorrhagic Telangiectasia Mouse Models

Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal-dominant genetic disorder involving defects in two predominant genes known as endoglin (ENG; HHT-1) and activin receptor-like kinase 1 (ACVRL1/ALK1; HHT-2). It is characterized by mucocutaneous telangiectases that, due to their fragility, frequently break causing recurrent epistaxis and gastrointestinal bleeding. Because of the severity of hemorrhages, the study of the hemostasis involved in these vascular ruptures is critical to find therapies for this disease. Our results demonstrate that HHT patients with high bleeding, as determined by a high Epistaxis Severity Score (ESS), do not have prolonged clotting times or alterations in clotting factors. Considering that coagulation is only one of the processes involved in hemostasis, the main objective of this study was to investigate the overall mechanisms of hemostasis in HHT-1 (Eng^+/−) and HHT-2 (Alk1^+/−) mouse models, which do not show HHT vascular phenotypes in the meaning of spontaneous bleeding. In Eng^+/− mice, the results of in vivo and in vitro assays suggest deficient platelet-endothelium interactions that impair a robust and stable thrombus formation. Consequently, the thrombus could be torn off and dragged by the mechanical force exerted by the bloodstream, leading to the reappearance of hemorrhages. In Alk1^+/− mice, an overactivation of the fibrinolysis system was observed. These results support the idea that endoglin and Alk1 haploinsufficiency leads to a common phenotype of impaired hemostasis, but through different mechanisms. This contribution opens new therapeutic approaches to HHT patients' epistaxis.

[Epistaxis-overview and current aspects]

Nosebleeds (epistaxis) are usually minor. Medical intervention is only necessary in about 6% of cases. The source of bleeding is frequently located in the anterior region of the nose (Kiesselbach's plexus). The estimated lifetime prevalence of epistaxis is 60%. Diffuse epistaxis is often a manifestation of systemic disease. Epistaxis is the leading symptom of Rendu-Osler-Weber disease (hereditary hemorrhagic telangiectasia, HHT). If intervention is required, the first-choice of treatment is bidigital compression for several minutes. Common therapeutic measures include local hemostasis using electrocoagulation or chemical agents, e.g., silver nitrate. Resorbable anterior nasal tampons or tampons with a smooth surface are also frequently employed. In case of failed surgical closure of the sphenopalatine artery, angiographic embolization is the method of choice.

[Implementation and development of a center for hereditary hemorrhagic telangiectasia]

OBJECTIVE

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare and systemic disorder which is characterized by recurrent epistaxis, mucocutaneous telangiectases, and visceral arteriovenous malformations (AVM). An interdisciplinary concept is recommended.

MATERIAL AND METHODS

We performed a retrospective review of consecutive patients who were referred to our newly established HHT Center of Excellence (HHT COE) for evaluation and treatment between April 2014 and August 2019.

RESULTS

A network of over 20 departments was established at the University Hospital Essen. In 261 of the 282 patients (93 %), who were referred to the hospital's COE, the HHT diagnosis was at least possible. Most patients suffered from several symptoms (epistaxis and / or telangiectasia: > 80 %, visceral involvement: 65 %) and received a variety of treatments, often in a multidisciplinary setting. Alongside this direct treatment, the COE leader manages the coordination of the center and its public relations, which involves more than 900 e-mails per year. International collaboration and exchanges of expertise within the European Reference Network on Rare Multisystemic Vascular Diseases (VASCERN) can improve the treatment of patients with HHT particularly where these cases are complex.

CONCLUSIONS

An HHT COE provides an interdisciplinary network where highly specialized diagnostic and therapeutic processes can be updated and optimized continuously.

[An hereditary hemorrhagic telangiectasia of late revealed by a cerebral venous thrombosis: A case report]

INTRODUCTION

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disease characterized by the triad of nose bleeding, telangiectasia and familial heredity.

CASE REPORT

We report the case of a patient who had idiopathic venous cerebral thrombosis complicated by a cerebral infarction treated with warfarin. In the context of a psoas hematoma by warfarine overdose and immobilization, the patient had deep vein thrombosis of the left lower limb with pulmonary embolism revealing a pulmonary arteriovenous malformation. After a reexamination, the patient clinical phenotype of HHT was confirmed genetically. The patient was treated with rivaroxaban allowing clinical improvement and partial recanalization of all thrombosis after six months. Thrombotic overisk has already been studied in HHT patients but the use of anticoagulants is at higher risk in these patients. However this patient experienced no adverse event with rivaroxaban.

CONCLUSION

This is the first case described of cerebral venous thrombosis treated with rivaroxaban revealing an HHT.

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.

Identification of two distinct hereditary hemorrhagic telangiectasia patient subsets with different hepatic perfusion properties by combination of contrast-enhanced ultrasound (CEUS) with perfusion imaging quantification

Background

Hereditary hemorrhagic telangiectasia (HHT) is marked by arteriovenous fusion comprising hepatic vascular malformations (HVaMs) with the chance of bleeding.

Aims

We investigated HVaMs in HHT patients by combination of contrast-enhanced ultrasound (CEUS) with perfusion imaging quantification to be able to sub-classify a high risk cohort of asymptomatic HHT patients.

Methods

The imaging characteristics on CEUS in 34 patients (aged 21–84 years; mean 58.9) with HHT were retrospectively evaluated. Real-time contrast harmonic imaging, sulfur hexafluoride-filled microbubbles and motion adjustment were utilized. Cine loops of the liver were digital stored, perfusion was quantified using a software reading DICOM data`s.

Results

HVaMs were diagnosed in 31 out of 34 patients. Significant uppermost peak enhancement (PE), wash-in area under the curve (WiAUC) and wash-in perfusion index (WiPI) were identified in the shunt region (100%), next in the hilar region (PE 32.6%; WiAUC 33.9%; WiPI 34.1%), and the lowest in the hepatic parenchyma (PE 10.2%; WiAUC 12.0%; WiPI 9.5%). The perfusion parameters in the shunt region compared to the other regions were significantly increased in one subgroup of patients. Consistent with this, the intrahepatic portal vein diameter and Buscarini grading was significantly higher, while portal vein peak velocity was significantly lower in this patient subset. By statistical analysis, we could correlate PE and WiPI to these clinical parameters, while WiAUC showed no clinical association.

Conclusions

For the first time we combined CEUS findings with motion adjustment software to quantitative determine perfusion parameters of a cohort of HHT patients. Hereby, we could identify a subset of HHT patients with two markedly increased parameter values in the shunt region compared to the hilus/hepatic parenchyma. This could contribute to sub-classify a high-risk group of HHT patients with therapeutic indication.

Treatment with low-dose tacrolimus inhibits bleeding complications in a patient with hereditary hemorrhagic telangiectasia and pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) can be found in patients suffering from a loss-of-function mutation of the gene encoding for the activin receptor-like kinase 1 (ALK-1), a bone morphogenetic protein (BMP) type 1 receptor. Interestingly, ALK-1 mutations also lead to hereditary hemorrhagic telangiectasia (HHT), an autosomal dominant disease characterized by arteriovenous malformations (AVMs) leading to potentially life-threatening bleeding complications such as epistaxis. Current therapeutic options for both diseases are limited and often only temporary or accompanied by severe side effects. Here, we report of a patient with a mutation of the ALK-1 gene suffering from both HHT and PAH. Recently, it was shown that tacrolimus increased ALK-1 signaling and had beneficial effects in selected end-stage PAH patients. We thus hypothesized that treatment with tacrolimus may prevent disease progression in this patient. Surprisingly, treatment with low-dose tacrolimus dramatically improved his HHT-associated epistaxis but did not attenuate progression of PAH.

Thalidomide for the Management of Bleeding Episodes in Patients with Hereditary Hemorrhagic Telangiectasia: Effects on Epistaxis Severity Score and Quality of Life

Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominantly inherited disorder characterized by bleeding episodes. These episodes tend to happen spontaneously and reduce the quality of life. Patients are often unresponsive to local measures. With the pathophysiological role of angiogenesis in HHT, antiangiogenic drugs including thalidomide are used to control bleeding episodes. In our study, we evaluated 6 patients with HHT, calculating their Epistaxis Severity Score (ESS) and performing a quality of life assessment with the 36-Item Short Form Health Survey Questionnaire (SF-36), and we studied the alterations of these evaluations with thalidomide treatment. Three patients were male and three were female. Mean age was 60.50 years. No side effects were observed during the treatment period. Improvements of certain SF-36 dimensions including physical functioning, physical component summary, and mental component summary and of the ESS were observed after treatment. Thalidomide may be effective to control bleeding episodes with a reasonable tolerance profile in patients with HHT.

Advances in the Medical Management of Vascular Anomalies

Vascular anomalies comprise a spectrum of diseases that are broadly classified as tumors and malformations. Diagnosis is often challenging, given a wide range of clinical presentations with overlapping signs and symptoms. Accurate diagnosis is critical to determine prognosis and to generate a management plan, which frequently involves multiple subspecialists during different phases of treatment. An updated classification system provides structure and clear, consistent terminology, allowing for improved diagnosis, provider communication, and collaboration. Historically, treatment of vascular anomalies was primarily surgical and medical therapies were limited or ineffective. Recent discoveries of pharmacologic agents effective in treating vascular anomalies have broadened our medical therapeutic options, limiting the need for unnecessary or high-risk procedures and improving patients' quality of life.

Asymptomatic pulmonary arteriovenous malformations in children with hereditary hemorrhagic telangiectasia

BACKGROUND

Children with Hereditary Hemorrhagic Telangiectasia (HHT) may have pulmonary arteriovenous malformations (AVMs), which can lead to symptoms of shortness of breath, exercise intolerance, clubbing, cyanosis and hemoptysis. However, some patients with pulmonary AVMs may be asymptomatic, placing them at risk for complications such as stroke or brain abscess if they are not identified and treated. This study examines the incidence of signs and symptoms associated with pulmonary AVMs in children with HHT known to have pulmonary AVMs.

METHOD

Sixty-one children with HHT and documented pulmonary AVMs were questioned for any symptoms possibly associated with their pulmonary AVMs, prior to embolization.

RESULTS

The results show that the majority of these children were asymptomatic (56%), and their AVMs were discovered by routine screening. Those who did experience symptoms most often complained of shortness of breath and exercise intolerance, although there was a tendency to blame other conditions, such as asthma or deconditioning (being out of shape), for these symptoms. Migraine headaches were common in those with pulmonary AVMs, regardless of whether they were symptomatic or not (17 of 61 children, 28%), although they were more common in those who were symptomatic (10 of 27, 37%) versus those who were asymptomatic (7 of 34, 21%).

CONCLUSION

Children with HHT and pulmonary AVMs are often asymptomatic. Routine screening for the presence of AVMs should be performed regardless of symptomatology.

Randomized controlled trial comparing Nd:YAG laser photocoagulation and bipolar electrocautery in the management of epistaxis

The objective of this study is to evaluate the efficacy and degree of comfort of Nd:YAG laser photocoagulation compared to bipolar electrocautery in the management of epistaxis. Seventy-two consecutive patients with a history of epistaxis were randomly assigned to receive treatment in an outpatient setting consisting of either bipolar electrocautery (group 1) or Nd:YAG laser photocoagulation (group 2). The study was conducted in university-affiliated teaching hospital. Seventy-two consecutive patients who suffered from anterior epistaxis and presented to the Otolaryngology Department at the Eye, Ear, Nose and Throat Hospital, Fudan University, between June 2015 and August 2015. The following outcome measures were assessed: bleeding intensity, bleeding frequency 4 and 16 weeks after treatment (0 = no bleeding, 1 = reduced bleeding, 2 = the same, and 3 = worse), participant perception of discomfort during treatment (grade 0-10, where 10 is the worst pain), and therapy duration and complications. At 16 weeks, 91% of the laser patients versus 91% of the bipolar electrocautery patients had no reported bleeding. The outcome scores at 4 and 16 weeks after treatment showed no significant difference between the two groups (P = 0.5 and P = 0.98, respectively; P > 0.05). The median pain levels experienced during the office laser and bipolar electrocautery procedures were 3.0 and 4.0, respectively, and the median durations of the laser and electrocautery therapies were 3.0 and 4.0, respectively. Neither groups had complications. It can be concluded that Nd:YAG laser photocoagulation and bipolar electrocautery are both effective in the treatment of epistaxis. These two therapies are recommended. As a whole, these two therapies, performed in an office setting, are timely, efficacious, and well tolerated in the treatment of epistaxis.

Mutation affecting the proximal promoter of Endoglin as the origin of hereditary hemorrhagic telangiectasia type 1

Background

Hereditary hemorrhagic telangiectasia (HHT) is a vascular multi-organ system disorder. Its diagnostic criteria include epistaxis, telangiectases in mucocutaneous sites, arteriovenous malformations (AVMs), and familial inheritance. HHT is transmitted as an autosomal dominant condition, caused in 85% of cases by mutations in either Endoglin (ENG) or Activin receptor-like kinase (ACVRL1/ACVRL1/ALK1) genes. Pathogenic mutations have been described in exons, splice junctions and, in a few cases with ENG mutations, in the proximal promoter, which creates a new ATG start site. However, no mutations affecting transcription regulation have been described to date in HHT, and this type of mutation is rarely identified in the literature on rare diseases.

Methods

Sequencing data from a family with HHT lead to single nucleotide change, c.-58G > A. The functionality and pathogenicity of this change was analyzed by in vitro mutagenesis, quantitative PCR and Gel shift assay. Student t test was used for statistical significance.

Results

A single nucleotide change, c.-58G > A, in the proximal ENG promoter co-segregated with HHT clinical features in an HHT family. This mutation was present in the proband and in 2 other symptomatic members, whereas 2 asymptomatic relatives did not harbor the mutation. Analysis of RNA from activated monocytes from the probands and the healthy brother revealed reduced ENG mRNA expression in the HHT patient (p = 0.005). Site-directed mutagenesis of the ENG promoter resulted in a three-fold decrease in luciferase activity of the mutant c.-58A allele compared to wild type (p = 0.005). Finally, gel shift assay identified a DNA-protein specific complex.

Conclusions

The novel ENG c.-58G > A substitution in the ENG promoter co-segregates with HHT symptoms in a family and appears to affect the transcriptional regulation of the gene, resulting in reduced ENG expression. ENG c.-58G > A may therefore be a pathogenic HHT mutation leading to haploinsufficiency of Endoglin and HHT symptoms. To the best of our knowledge, this is the first report of a pathogenic mutation in HHT involving the binding site for a transcription factor in the promoter of ENG.

Macro- and microcirculation patterns of intrahepatic blood flow changes in patients with hereditary hemorrhagic telangiectasia

AIM

To evaluated vascular dynamic processes in the liver of hereditary hemorrhagic telangiectasia (HHT) patients by ultrasound (US) considering quantitative analytic methods.

METHODS

The imaging features on US and contrast-enhanced ultrasound (CEUS) in 18 patients diagnosed with HHT were retrospectively analyzed. Regarding CEUS, real-time contrast harmonic imaging and sulfur hexafluoride-filled microbubbles were used.

RESULTS

HVaMs were identified in all 18 patients. By US, the two major Caselitz criteria could be detected in 55.6% patients. "Color spots" were detected in 72.2% of the cases. Respecting sonographic grading criteria by Buscarini, grade 3 could be demonstrated most frequent (40%). By CEUS, all the patients showed quick and early hyperenhancement during the arterial phase. Significant lowest time to peak (TTP) and highest area under the curve (AUC) values were identified in the hepatic artery (TTP: 69.8%; AUC: 100%) and highest TTP and lowest AUC in the hepatic parenchyma and the portal vein.

CONCLUSION

For the first time we analyzed CEUS findings of a group of HHT patients regarding macro- and microcirculation. Our data demonstrate significant differences in TTP and AUC values in the four selected regions: hepatic artery, shunt region, portal vein and hepatic parenchyma.

Splenic Involvement in Hereditary Hemorrhagic Telangiectasia

A 33-year-old man who presented with prolonged epigastric pain was referred to our hospital. He had experienced recurrent epistaxis and had a family history of hereditary hemorrhagic telangiectasia. Computed tomography and magnetic resonance imaging revealed splenomegaly and a 9 cm hypervascular mass in his spleen. Computed tomography also showed a pulmonary arteriovenous malformation and heterogeneous enhancement of the liver parenchyma, suggesting the presence of arteriosystemic shunts and telangiectases. Based on these findings, the patient was definitely diagnosed with hereditary hemorrhagic telangiectasia according to Curaçao criteria. He underwent splenectomy, and his symptoms disappeared after surgery. Pathological examination of the resected specimen revealed that the hypervascular lesion of the spleen was not a tumor but was composed of abnormal vessels associated with hereditary hemorrhagic telangiectasia. Symptomatic splenic involvement may be a rare manifestation of hereditary hemorrhagic telangiectasia but can be revealed by imaging modalities.