Executive summary of the 11th HHT international scientific conference

Randomized, double-blind, placebo-controlled, crossover trial of oral doxycycline for epistaxis in hereditary hemorrhagic telangiectasia

Background

Vascular malformations in hereditary hemorrhagic telangiectasia (HHT) lead to chronic recurrent bleeding, hemorrhage, stroke, heart failure, and liver disease. There is great interest in identifying novel therapies for epistaxis in HHT given its associated morbidity and impact on quality of life. We aimed to measure the effectiveness of oral doxycycline for the treatment of epistaxis and explore mechanisms of action on angiogenic, inflammatory and pathway markers in HHT using a randomized controlled trial.

Methods

13 HHT patients with epistaxis were recruited from the Toronto HHT Center at St. Michael’s Hospital. Recruitment was stopped early due to COVID-19-related limitations. The study duration was 24 months. Patients were randomly assigned to the treatment-first or placebo-first study arm. We compared the change in weekly epistaxis duration and frequency, biomarkers, blood measurements, and intravenous iron infusion and blood transfusion requirements between treatment and placebo.

Results

There was no significant difference in the change in weekly epistaxis duration (p = 0.136) or frequency (p = 0.261) between treatment and placebo. There was no significant difference in the levels of MMP-9, VEGF, ANG-2, IL-6 or ENG with treatment. Hemoglobin levels were significantly higher (p = 0.0499) during treatment. Ferritin levels were not significantly different between treatment and placebo. There was no significant difference in RBC transfusions between treatment periods (p = 0.299).

Conclusion

Overall, our study did not demonstrate effectiveness of doxycycline as a treatment for epistaxis in patients with HHT, though the study was underpowered. Secondary analyses provided new observations which may help guide future trials in HHT.

Trial Registration ClinicalTrials.gov, NCT03397004. Registered 11 January 2018 – Prospectively registered, https://clinicaltrials.gov/ct2/show/NCT03397004

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02539-8.

[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.

Higher prevalence of splenic artery aneurysms in hereditary hemorrhagic telangiectasia: Vascular implications and risk factors

BACKGROUND

Splenic artery aneurysm (SAA) is a rare but potentially fatal condition. Rupture results in 25% mortality up to 75% in pregnant women with 95% fetal mortality. Brief reports suggest an increased risk of developing SAA in patients with HHT.

METHODS

We analyzed enhanced multidetector CT data in 186 HHT patients matched (gender and ± 5 year old) with 186 controls. We screened for SAA and recorded diameter of splenic and hepatic arteries and hepatic, pancreatic and splenic parenchymal involvements. We determined by univariate and multivariate analysis, the relationship with age, sex, genetic status, cardiovascular risk factors (CVRF) and visceral involvement.

RESULTS

SAA concerned 24.7% of HHT patients and 5.4% of controls, p<0.001. Factors associated with increased risk of SAA in HHT were female gender (p = 0.04, OR = 2.12, IC 95% = 1.03-4.50), age (p = 0.0003, OR = 1.04, 95% CI = 1.02-1.06) and pancreatic parenchymal involvement (p = 0.04, OR = 2.13, 95% CI = 1.01-4.49), but not type of mutation, hepatic or splenic parenchymal involvements, splenic size or splenic artery diameter or CVRF.

CONCLUSIONS

We found a 4.57 higher rate of SAA in HHT patients without evidence of splenic high output related disease or increased CVRF. These results suggest the presence of a vascular intrinsic involvement. It should lead to screening all HHT patients for SAA. The vasculopathy hypothesis could require a change in management as screening of all systemic arteries and even the aorta and to further research in the field.

Clinical features and treatment of hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disorder characterized by vascular dysplasia, including typically systemic telangiectases and arteriovenous malformations (AVMs). Due to its variable clinical manifestations, HHT patients often seek medical care from different medical subspecialties and thus experience delays in diagnosis and treatment.This study is designed to analyze the clinical features and treatment options for patients with HHT.Hospitalized patients with a definitive diagnosis of HHT from November 1973 to July 2016 in Peking Union Medical College Hospital were identified after reviewing medical records and electronic databases. Further follow-up data of these patients were collected from outpatient clinical visits and/or telephone interviews.We identified a total of 20 patients, 7 males and 13 females. The mean age was 42.4 ± 20.3 years. Epistaxis (18/20) was the most common presentation, followed by telangiectases of the oral buccal mucosa, tongue and/or lips (14/20), pulmonary AVMs (12/19), hepatic AVMs (9/17), gastrointestinal telangiectases (9/9), and encephalic AVMs (1/12). The correct diagnosis of HHT was delayed on average by about 26.4 ± 17.0 years from the onset of HHT-related clinical signs and symptoms. Although epistaxis is usually presented in childhood (mean age 11 ± 7.1 years), gastrointestinal telangiectasia was often encountered in late middle age (mean age 55.4 ± 12.8 years). Bleeding and anemia were the most common complications. Molecular analysis was conducted in 4 patients. Only 1 patient was found to have a single-base deletion in ENG gene. The mean duration of follow-up of the patients was 41.8 months. The efficacy of locoregional therapy was of limited value and short-lived. Two patients were treated systemically with thalidomide, and their symptoms of epistaxis, melena, and anemia were notably improved.Patients with HHT have variable clinical characteristics, and their diagnoses were delayed on average by about 26 years. An experienced multidisciplinary team is needed for the early diagnosis and optimal management of patients with HHT. Thalidomide may be an effective choice to alleviate the bleeding symptoms of patients with HHT.

Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) describes the presenting manifestations of a disorder that is characterized by pathologic blood vessels. HHT is inherited as an autosomal dominant trait with variable penetrance. The abnormal vascular structures (dysplasias) can affect all the organs in the human body. The link between a physical stimulus and new lesion development has been established for mucosal trauma owing to nasal airflow turbulence, for ultraviolet exposure to the fingers, and for mechanical trauma to the dominant hand. The pressing question then is whether HHT treatment constitutes a stimulus that is sufficient to trigger new lesion development.

Vascular deficiency of Smad4 causes arteriovenous malformations: a mouse model of Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder that leads to abnormal connections between arteries and veins termed arteriovenous malformations (AVM). Mutations in TGFβ pathway members ALK1, ENG and SMAD4 lead to HHT. However, a Smad4 mouse model of HHT does not currently exist. We aimed to create and characterize a Smad4 endothelial cell (EC)-specific, inducible knockout mouse (Smad4^f/f;Cdh5-Cre^ERT2) that could be used to study AVM development in HHT. We found that postnatal ablation of Smad4 caused various vascular defects, including the formation of distinct AVMs in the neonate retina. Our analyses demonstrated that increased EC proliferation and size, altered mural cell coverage and distorted artery-vein gene expression are associated with Smad4 deficiency in the vasculature. Furthermore, we show that depletion of Smad4 leads to decreased Vegfr2 expression, and concurrent loss of endothelial Smad4 and Vegfr2 in vivo leads to AVM enlargement. Our work provides a new model in which to study HHT-associated phenotypes and links the TGFβ and VEGF signaling pathways in AVM pathogenesis.

Pazopanib effective for bevacizumab-unresponsive epistaxis in hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) most commonly manifests with nasal mucosal telangiectasias, and vascular endothelial growth factor (VEGF) plays a significant role in this angiodysplasia. We describe a patient with HHT with epistaxis recalcitrant to several endonasal procedures and six cycles of intravenous bevacizumab, for which he was dependent on iron infusions and packed red blood cells transfusions. He then started pazopanib at 100 mg with dramatic improvements in epistaxis and normalization of hemoglobin and iron levels, without replenishment needs for 12 months. This is the first report on the efficacy of pazopanib with high selectivity for abrogating VEGF receptor-2 signaling in HHT, and needs to be explored further. Laryngoscope, 128:2234-2236, 2018.

Blood-brain barrier-on-a-chip: Microphysiological systems that capture the complexity of the blood-central nervous system interface

The blood-brain barrier is a dynamic and highly organized structure that strictly regulates the molecules allowed to cross the brain vasculature into the central nervous system. The blood-brain barrier pathology has been associated with a number of central nervous system diseases, including vascular malformations, stroke/vascular dementia, Alzheimer's disease, multiple sclerosis, and various neurological tumors including glioblastoma multiforme. There is a compelling need for representative models of this critical interface. Current research relies heavily on animal models (mostly mice) or on two-dimensional (2D) in vitro models, neither of which fully capture the complexities of the human blood-brain barrier. Physiological differences between humans and mice make translation to the clinic problematic, while monolayer cultures cannot capture the inherently three-dimensional (3D) nature of the blood-brain barrier, which includes close association of the abluminal side of the endothelium with astrocyte foot-processes and pericytes. Here we discuss the central nervous system diseases associated with blood-brain barrier pathology, recent advances in the development of novel 3D blood-brain barrier -on-a-chip systems that better mimic the physiological complexity and structure of human blood-brain barrier, and provide an outlook on how these blood-brain barrier-on-a-chip systems can be used for central nervous system disease modeling. Impact statement The field of microphysiological systems is rapidly evolving as new technologies are introduced and our understanding of organ physiology develops. In this review, we focus on Blood-Brain Barrier (BBB) models, with a particular emphasis on how they relate to neurological disorders such as Alzheimer's disease, multiple sclerosis, stroke, cancer, and vascular malformations. We emphasize the importance of capturing the three-dimensional nature of the brain and the unique architecture of the BBB - something that until recently had not been well modeled by in vitro systems. Our hope is that this review will provide a launch pad for new ideas and methodologies that can provide us with truly physiological BBB models capable of yielding new insights into the function of this critical interface.

Central nervous system manganese induced lesions and clinical consequences in patients with hereditary hemorrhagic telangiectasia

BACKGROUND

Around 47-74% of patients with hereditary hemorrhagic telangiectasia (HHT) have hepatic vascular malformations (HVMs); magnetic resonance images (MRI) of the central nervous system (CNS) might show in T1 sequences a hyper-intensity signal in different areas, mainly in the basal ganglia (BG) as consequence of manganese (Mn) deposits as observed in cirrhotic patients. These patients might suffer from different neuropsychiatric disorders (hepatic encephalopathy). In HHT patients, even in the presence of hepatic shunts, hepatocellular function is usually preserved. Additionally, Mn shares iron absorption mechanisms, transferrin and CNS transferrin receptors. In iron deficiency conditions, the Mn may harbor transferrin and access BG. The objectives were to describe frequency of BG Mn deposit-induced lesions (BGMnIL) in HHT patients, its relationship with iron deficiency anemia (IDA) and HVMs. Finally, explore the association between neuropsychological and motor consequences. We performed a cross-sectional study. We determined HHT patients with or without BG-MnIL by the MRI screening of the CNS. We included all patients with lesions and a random sample of those without lesions. All patients underwent standardized and validated neuropsychological assessment to evaluate BG actions. Results were analyzed with multiple logistic regression, adjusting for potential confounders.

RESULTS

Among 307 participants from a cohort included in the Institutional HHT Registry, 179 patients had MRI performed and Curaçao Criteria ≥3. The prevalence of BG-MnIL was 34.6% (95%CI 27.69-42.09). While neuropsychological symptoms were present in all patients, BG-MnIL patients performed poorly in three of the neuropsychological tests (serial dotting, line tracing time, number connection test A). HVMs frequency in BG-MnIL was 95.1%, versus 71.4% in those without lesions (p < 0.001). IDA frequency was 90.3% versus 54% (p < 0.001). When IDA is present, estimated risk for BG-MnIL is remarkably high (OR 7.73, 95%CI 2.23-26.73). After adjustment for possible confounders (gender, age, presence of HVMs), IDA was still associated with increased risk of BG-MnIL (adjusted OR 6.32, 95% CI 2.32-17.20; p < 0.001).

CONCLUSIONS

Physicians should assess BG-MnIL in HHT patients in CNS-MRI. IDA and HVMs present increased risk of lesions. Patients with BG-MnIL have neuropsychological impairment, and they might benefit from sparing IDA, or undergoing future therapeutic options.

TRIAL REGISTRATION

NCT01761981 . Registered January 3^rd 2013.

Non-invasive CT screening for pulmonary arteriovenous malformations in children with confirmed hereditary hemorrhagic telangiectasia: Results from two pediatric centers

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant genetic disorder that is caused by mutations in mainly two genes, that is ENG, encoding endoglin (HHT1), or ACVRL1, encoding activin receptor-like kinase 1 (ALK-1/HHT2). HHT is characterized by recurrent epistaxis, mucocutaneous telangiectasia, and vascular visceral dysplasia responsible for visceral arteriovenous malformations (AVM).

AIM

to report the experience of two university hospitals (Trousseau, Paris, and CHIC, Creteil) with screening children for HHT and pulmonary AVM (PAVM) using high resolution computed tomography (HRCT).

METHODS

parents with confirmed HHT were offered to have their children screened for the mutation identified in their family, and informed consent was obtained. Children carrying the same mutation as their parents underwent HRCT of the chest without contrast.

RESULTS

between 2008 and 2015, 99 children were screened for HHT mutations. Mutations were identified in 59 patients, that is 24 HHT1 and 35 HHT2. Radiologic and clinical screening was possible in 52 patients (21 HHT-1 and 31 HHT-2). Among those, PAVM was identified in 13 patients (25%; n = 8 HHT1; n = 5 HHT2), and four of them required embolization therapy.

CONCLUSION

This study highlights the usefulness of genetic screening in children with known HHT family. It also suggests that a non-invasive protocol such as HRTC is an efficient approach to detect non-symptomatic lesions that are present early on in children carrying the ENG (HHT1), but also the ACVRL1 mutations (HHT2). Pediatr Pulmonol. 2017;52:642-649. © 2017 Wiley Periodicals, Inc.

Hereditary haemorrhagic telangiectasia: to transplant or not to transplant - is there a right time for liver transplantation?

BACKGROUND & AIMS

Hereditary haemorrhagic telangiectasia is characterized by arterio-venous malformations (AVM). It frequently involves the liver without clinical symptoms, but may lead to biliary ischaemia, portal hypertension, or fatal high-output heart failure. The indication of liver transplantation is controversial.

METHODS

Herein, we report the case of a 65-year-old female patient with a 'double Osler syndrome' consisting of hereditary haemorrhagic telangiectasia (HHT) and type I hereditary angioedema diagnosed at the age of 25 and 22 years respectively.

RESULTS

Hereditary angioedema was treated with danazol for several decades until multiple hypoechogenic liver masses were detected. Albeit danazol treatment was replaced by C1 esterase inhibitor infusions, hepatocellular carcinoma was diagnosed at the age of 64 and the patient was listed for liver transplantation. HHT was marked by recurrent epistaxis until the age of 63 when severe intestinal bleeding occurred. At the age of 65, severe dyspnoea (NYHA class IV) developed and rapidly progressive high-output cardiac failure was diagnosed. Despite argon plasma coagulation to control bleeding from intestinal angiodysplasia, and treatment with bevacizumab to inhibit angiogenesis, the patient died from severe gastrointestinal bleeding associated with cardiogenic shock at the age of 66 before being transplanted.

CONCLUSION

The indication to list this patient for liver transplantation was debated several times before the diagnosis of hepatocellular carcinoma because of good general condition and low MELD score. Precise guidelines for screening and management of patients with hepatic HHT need to be better defined.

A mouse model of hereditary hemorrhagic telangiectasia generated by transmammary-delivered immunoblocking of BMP9 and BMP10

Hereditary hemorrhagic telangiectasia (HHT) is a potentially life-threatening genetic vascular disorder caused by loss-of-function mutations in the genes encoding activin receptor-like kinase 1 (ALK1), endoglin, Smad4, and bone morphogenetic protein 9 (BMP9). Injections of mouse neonates with BMP9/10 blocking antibodies lead to HHT-like vascular defects in the postnatal retinal angiogenesis model. Mothers and their newborns share the same immunity through the transfer of maternal antibodies during lactation. Here, we investigated whether the transmammary delivery route could improve the ease and consistency of administering anti-BMP9/10 antibodies in the postnatal retinal angiogenesis model. We found that anti-BMP9/10 antibodies, when intraperitoneally injected into lactating dams, are efficiently transferred into the blood circulation of lactationally-exposed neonatal pups. Strikingly, pups receiving anti-BMP9/10 antibodies via lactation displayed consistent and robust vascular pathology in the retina, which included hypervascularization and defects in arteriovenous specification, as well as the presence of multiple and massive arteriovenous malformations. Furthermore, RNA-Seq analyses of neonatal retinas identified an increase in the key pro-angiogenic factor, angiopoietin-2, as the most significant change in gene expression triggered by the transmammary delivery of anti-BMP9/10 antibodies. Transmammary-delivered BMP9/10 immunoblocking in the mouse neonatal retina is therefore a practical, noninvasive, reliable, and robust model of HHT vascular pathology.

Small bowel adenocarcinoma arising in a patient with hereditary hemorrhagic telangiectasia: A case report

Patients with hereditary hemorrhagic telangiectasia (HHT) are reportedly at a lower overall risk of malignancies, and small bowel adenocarcinoma (SBA) arising in a HHT patient is extremely rare. In this study, the case of a 37-year-old female with HHT who developed a poorly differentiated jejunal adenocarcinoma five years after ileocecal resection for multiple colonic adenomas is presented. The patient underwent curative resection of the cancer invading the ileum and the mesentery of the transverse colon, but had to overcome critical complications perioperatively, stemming from HHT-associated peripheral capillary dilatation and arteriovenous malformation, including nosebleeds and possible infusion-induced air embolism through pulmonary shunts. The patient subsequently received adjuvant chemotherapy including capecitabine and oxaliplatin for 6 months, and currently remains alive without any evidence of recurrence 12 months after the second surgery. This patient with SBA was an instructive case demonstrating the necessity of careful attention during major surgery in HHT.

BMP signaling in vascular biology and dysfunction

The vascular system is critical for developmental growth, tissue homeostasis and repair but also for tumor development. Bone morphogenetic protein (BMP) signaling has recently emerged as a fundamental pathway of the endothelium by regulating cardiovascular and lymphatic development and by being causative for several vascular dysfunctions. Two vascular disorders have been directly linked to impaired BMP signaling: pulmonary arterial hypertension and hereditary hemorrhagic telangiectasia. Endothelial BMP signaling critically depends on the cellular context, which includes among others vascular heterogeneity, exposure to flow, and the intertwining with other signaling cascades (Notch, WNT, Hippo and hypoxia). The purpose of this review is to highlight the most recent findings illustrating the clear need for reconsidering the role of BMPs in vascular biology.