Bazedoxifene, a new orphan drug for the treatment of bleeding in hereditary haemorrhagic 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.

Hereditary Hemorrhagic Telangiectasia With Multiple Ear, Nose, and Throat (ENT) Manifestations: A Case Report

Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is a rare autosomal dominant multisystem disorder. It is a mucocutaneous and fibrovascular dysplasia, the diagnosis of which is based on the fulfillment of the four Curaçao criteria: 1) recurrent epistaxis; 2) dermatovascular mucosal telangiectasias at characteristic sites: skin of the face, ears, fingertips, lips, tongue, and oral and nasal cavity; 3) arteriovenous malformations (AVMs) of visceral organs and central nervous system; and 4) family history: diagnosis of HHT in a first-degree relative. We describe a case of a 76-year-old patient who presented to our department with clinical manifestations of HHT in the skin (face, fingertips), lips, hard palate, tongue, ears, and nasal cavities. Individual and family history was obtained, as well as clinical laboratory examination, pan-endoscopy of the ear, nose, and throat (ENT) systems, and treatment of active foci of bleeding from the above areas. The otolaryngologist may be the first doctor to suspect Rendu-Osler-Weber syndrome and the one responsible for treating patients with HHT since recurrent epistaxis is the most frequent (90-96% of patients) and the earlier manifestation of the disease and the main reason for the arrival of these patients in the Emergency Department. The purpose of this study is to present a clinical case of Rendu-Osler-Weber syndrome with multiple ENT manifestations, as well as a review of the literature on their management and treatment.

[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.

Pathogenesis and therapy of arteriovenous malformations: A case report and narrative review

Arteriovenous malformations (AVMs) are abnormal communications between arteries and veins that lack intervening capillary beds. They have been described in almost every organ in the body, emerging sporadically or as part of well-described syndromes. Hereditary hemorrhagic telangiectasia (HHT) is a rare, progressive, and lifelong disease characterized by AVMs and recurrent hemorrhaging. In the last 2 decades, significant advances have been made in understanding the pathogenesis of this condition. The accumulation of knowledge has led to a natural evolution of therapy, from open surgery to endovascular procedures, and now to a role for medications in certain AVMs. Here, we review a case of HHT and describe the most up-to-date clinical practice, including diagnosis of HHT, subtypes of HHT, and medical therapy.

Intermixed arteriovenous malformation and hemangioblastoma: case report and literature review

We report the third presentation of an intermixed arteriovenous malformation and hemangioblastoma. The rare occurrence of the diagnostic histologic features of both a neoplasm and vascular malformation in a single lesion is more common in gliomas, as angioglioma, and is termed an 'intermixed' lesion. We review the literature concerning the developmental biology of each lesion, and potential interplay in the formation of an intermixed vascular neoplasm and vascular malformation. The roles of cellular origin, genetic susceptibility, favourable microenvironment, altered local gene expression and key regulatory pathways are reviewed. Our review supports angiography and genetic profiling in intermixed lesions to inform management strategies. Consideration should be given to multimodality therapeutic interventions as required, including microsurgical resection, stereotactic radiosurgery and further research to exploit emerging molecular targets.

Novel Use of Tamoxifen to Reduce Recurrent Gastrointestinal Bleeding in Patients with Left Ventricular Assist Devices

Gastrointestinal bleeding (GIB) is a frequent complication in patients with continuous-flow left ventricular assist devices (LVAD). We retrospectively evaluated eight patients implanted with a HeartWare LVAD between July 2017 and June 2020 who experienced at least one episode of GIB and were started on tamoxifen 20 mg once daily for secondary prevention. Tamoxifen was associated with a significant decrease in major GIB from a median of 3 (IQR 1.4-7) events/patient-year pre-tamoxifen initiation to 0 (IQR 0-0.9) events/patient-year post-tamoxifen initiation (p = 0.02). Transfusion of packed red blood cells also decreased from 16.8 (IQR 9.9-30.6) units/patient-year pre-tamoxifen initiation to 1.5 (IQR 0-7.5) units/patient-year post-tamoxifen (p = 0.04). Tamoxifen was well tolerated and no thromboembolic complications were observed. This small cohort study suggests that tamoxifen is associated with reduced GIB and transfusion requirements, with no apparent increase in thrombotic risk. A larger, randomized study is warranted to confirm the results of this exploratory analysis. Graphical abstract.

Raloxifene and n-Acetylcysteine Ameliorate TGF-Signalling in Fibroblasts from Patients with Recessive Dominant Epidermolysis Bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe skin disease caused by mutation of the COL7A1 gene. RDEB is associated with high levels of TGF-β1, which is likely to be involved in the fibrosis that develops in this disease. Endoglin (CD105) is a type III coreceptor for TGF-β1 and its overexpression in fibroblasts deregulates physiological Smad/Alk1/Alk5 signalling, repressing the synthesis of TGF-β1 and extracellular matrix (ECM) proteins. Raloxifene is a specific estrogen receptor modulator designated as an orphan drug for hereditary hemorrhagic telangiectasia, a rare vascular disease. Raloxifene stimulates endoglin synthesis, which could attenuate fibrosis. By contrast, the antioxidant N-acetylcysteine may have therapeutic value to rectify inflammation, fibrosis and endothelial dysfunction. Thus, we present here a repurposing strategy based on the molecular and functional screening of fibroblasts from RDEB patients with these drugs, leading us to propose the repositioning of these two well-known drugs currently in clinical use, raloxifene and N-acetylcysteine, to counteract fibrosis and inflammation in RDEB. Both compounds modulate the profibrotic events that may ultimately be responsible for the clinical manifestations in RDEB, suggesting that these findings may also be relevant for other diseases in which fibrosis is an important pathophysiological event.

Overexpression of Activin Receptor-Like Kinase 1 in Endothelial Cells Suppresses Development of Arteriovenous Malformations in Mouse Models of Hereditary Hemorrhagic Telangiectasia

RATIONALE

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disease caused by mutations in ENG, ALK1, or SMAD4. Since proteins from all 3 HHT genes are components of signal transduction of TGF-β (transforming growth factor β) family members, it has been hypothesized that HHT is a disease caused by defects in the ENG-ALK1-SMAD4 linear signaling. However, in vivo evidence supporting this hypothesis is scarce.

OBJECTIVE

We tested this hypothesis and investigated the therapeutic effects and potential risks of induced-ALK1 or -ENG overexpression (OE) for HHT.

METHODS AND RESULTS

We generated a novel mouse allele (ROSA26^Alk1) in which HA (human influenza hemagglutinin)-tagged ALK1 and bicistronic eGFP expression are induced by Cre activity. We examined whether ALK1-OE using the ROSA26^Alk1 allele could suppress the development of arteriovenous malformations (AVMs) in wounded adult skin and developing retinas of Alk1- and Eng-inducible knockout (iKO) mice. We also used a similar approach to investigate whether ENG-OE could rescue AVMs. Biochemical and immunofluorescence analyses confirmed the Cre-dependent OE of the ALK1-HA transgene. We could not detect any pathological signs in ALK1-OE mice up to 3 months after induction. ALK1-OE prevented the development of retinal AVMs and wound-induced skin AVMs in Eng-iKO as well as Alk1-iKO mice. ALK1-OE normalized expression of SMAD and NOTCH target genes in ENG-deficient endothelial cells (ECs) and restored the effect of BMP9 (bone morphogenetic protein 9) on suppression of phosphor-AKT levels in these endothelial cells. On the other hand, ENG-OE could not inhibit the AVM development in Alk1-iKO models.

CONCLUSIONS

These data support the notion that ENG and ALK1 form a linear signaling pathway for the formation of a proper arteriovenous network during angiogenesis. We suggest that ALK1 OE or activation can be an effective therapeutic strategy for HHT. Further research is required to study whether this therapy could be translated into treatment for humans.

Safety and Efficacy of Blue Light Laser Treatment in Hereditary Hemorrhagic Telangiectasia

BACKGROUND AND OBJECTIVES

Hereditary hemorrhagic telangiectasia (HHT) is a hereditary condition that is associated with arteriovenous malformations. A common site for these malformations is the nasal mucosa, which is associated with severe epistaxis and debilitation for affected patients. We evaluated the efficacy and safety of blue light laser technology in treating these endonasal manifestations in a retrospective chart analysis. Additionally, we compared blue light laser technology to bipolar coagulation in an animal model.

STUDY DESIGN/MATERIALS AND METHODS

We performed a retrospective chart analysis of all patients that were diagnosed with HHT and received endonasal blue light laser treatment between 10/2017 and 04/2019. In addition, we performed bipolar or blue light laser coagulation of all macroscopically visible vessels on thyroid gland lobes (n = 4) from Dunkin-Hartley Guinea Pigs. Hematoxylin-eosin (HE) staining was then used to visualize depth and area of coagulation surrounding these vessels.

RESULTS

One hundred and fifty-one treatments in 23 patients were analyzed. Under regular blue light laser treatment, quality of life (QOL), indicated on a visual analog scale from 1 to 10, gradually increased significantly from 5.6 ± 0.5 (before the first treatment) to 7.5 ± 0.9 (after the second treatment). Following this, QOL remained steady throughout additional treatments. Adverse effects were not recorded. HE staining showed that coagulation depth (162 ± 56 vs. 586 ± 192 µm) and area (74 ± 35 vs. 1015 ± 449 µm² ) were significantly lower after laser treatment.

CONCLUSION

Blue light laser therapy is safe and efficient in treating HHT. Damage to the surrounding tissue is significantly lower compared with bipolar coagulation. © 2020 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.

Review of Pharmacological Strategies with Repurposed Drugs for Hereditary Hemorrhagic Telangiectasia Related Bleeding

The diagnosis of hereditary hemorrhagic telangiectasia (HHT) is based on the Curaçao criteria: epistaxis, telangiectases, arteriovenous malformations in internal organs, and family history. Genetically speaking, more than 90% of HHT patients show mutations in ENG or ACVRL1/ALK1 genes, both belonging to the TGF-β/BMP9 signaling pathway. Despite clear knowledge of the symptoms and genes of the disease, we still lack a definite cure for HHT, having just palliative measures and pharmacological trials. Among the former, two strategies are: intervention at "ground zero" to minimize by iron and blood transfusions in order to counteract anemia. Among the later, along the last 15 years, three different strategies have been tested: (1) To favor coagulation with antifibrinolytic agents (tranexamic acid); (2) to increase transcription of ENG and ALK1 with specific estrogen-receptor modulators (bazedoxifene or raloxifene), antioxidants (N-acetylcysteine, resveratrol), or immunosuppressants (tacrolimus); and (3) to impair the abnormal angiogenic process with antibodies (bevacizumab) or blocking drugs like etamsylate, and propranolol. This manuscript reviews the main strategies and sums up the clinical trials developed with drugs alleviating HHT.

Topically Applied Etamsylate: A New Orphan Drug for HHT-Derived Epistaxis (Antiangiogenesis through FGF Pathway Inhibition)

Hereditary hemorrhagic telangiectasia (HHT) is a vascular dysplasia characterized by recurrent and spontaneous epistaxis (nose bleeds), telangiectases on skin and mucosa, internal organ arteriovenous malformations, and dominant autosomal inheritance. Mutations in Endoglin and ACVRL1 / ALK1 , genes mainly expressed in endothelium, are responsible in 90% of the cases for the pathology. These genes are involved in the transforming growth factor-β(TGF-β) signaling pathway. Epistaxis remains as one of the most common symptoms impairing the quality of life of patients, becoming life-threatening in some cases. Different strategies have been used to decrease nose bleeds, among them is antiangiogenesis. The two main angiogenic pathways in endothelial cells depend on vascular endothelial growth factor and fibroblast growth factor (FGF). The present work has used etamsylate, the diethylamine salt of the 2,5-dihydroxybenzene sulfonate anion, also known as dobesilate, as a FGF signaling inhibitor. In endothelial cells, in vitro experiments show that etamsylate acts as an antiangiogenic factor, inhibiting wound healing and matrigel tubulogenesis. Moreover, etamsylate decreases phosphorylation of Akt and ERK1/2. A pilot clinical trial (EudraCT: 2016–003982–24) was performed with 12 HHT patients using a topical spray of etamsylate twice a day for 4 weeks. The epistaxis severity score (HHT-ESS) and other pertinent parameters were registered in the clinical trial. The significant reduction in the ESS scale, together with the lack of significant side effects, allowed the designation of topical etamsylate as a new orphan drug for epistaxis in HHT (EMA/OD/135/18).

Sclerotherapy and Topical Nasal Propranolol: An Effective and Safe Therapy for HHT-Epistaxis

OBJECTIVES

Epistaxis is the most frequent clinical manifestation of hereditary hemorrhagic telangiectasia (HHT). Several topical, systemic, and surgical treatments have been tried, but none have been completely effective. The aim of the present study is to evaluate whether a combined treatment sclerotherapy and topical therapy with propranolol 0.5% nasal formulation would reduce the epistaxis due to HHT and improve patient's quality of life.

METHODS

An observational cross-sectional study was carried out. The primary outcome measure was frequency and severity of epistaxis as measured by the epistaxis severity score (ESS) at baseline (4 weeks before therapy) and at least 4 weeks after the treatment was implemented. Quality of life was analyzed using EuroQol-5D (EQ-5D) scale and visual analogue (VAS) scale before and after treatment.

RESULTS

A total of 38 consecutive patients subjected to the combined treatment were evaluated (mean age: 57.2 years, standard deviation [SD] = 13.9; 60.5% women). The mean time of treatment was 37.1 weeks (SD = 14.9). Combined therapy significantly reduces frequency and severity of epistaxis, with an ESS improvement of 5 points from 6.9 ± 2.6 to 1.9 ± 1.3 (P < 0.05); however, the EQ-5D scale increased from 0.66 ± 0.27 to 0.93 ± 0.12 (P < 0.05). The difference in VAS means showed an increase from 44.6 ± 28.3 to 82.5 ± 12.5 (P < 0.05). The increases in quality of life are in line with the drop in ESS.

CONCLUSION

The study demonstrated that combined therapy (sclerotherapy and topical nasal propranolol) significantly reduced the epistaxis due to HHT and increased patients' quality of life.

LEVEL OF EVIDENCE

2c Laryngoscope, 129:2216-2223, 2019.

Pharmacologic normalization of pathogenic dosage underlying genetic diseases: an overview of the literature and path forward

Most monogenic disorders are caused by a pathologic deficit or excess of a single transcript and/or protein. Given that small molecules, including drugs, can affect levels of mRNA and protein, the pharmacologic normalization of such pathogenic dosage represents a possible therapeutic approach for such conditions. Here, we review the literature exploring pharmacologic modulation of mRNA and/or protein levels for disorders with paralogous modifier genes, for haploinsufficient disorders (insufficient gene-product), as well as toxic gain-of-function disorders (surplus or pathologic gene-product). We also discuss challenges facing the development of rare disease therapy by pharmacologic modulation of mRNA and protein. Finally, we lay out guiding principles for selection of disorders which may be amenable to this approach.

Systematic screening in hereditary hemorrhagic telangiectasia: a review

PURPOSE OF REVIEW

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant inherited disease characterized by telangiectasia and arteriovenous malformations (AVMs). To date, five genetic types of HHT and one combined juvenile polyposis syndrome and HHT are known. Clinical and genetic screening of patients suspected with HHT is recommended to confirm the diagnosis and to prevent complications associated with HHT. The aim of this article is to give an overview of the evidence and to formulate a recommendation for clinicians concerning screening for HHT.

RECENT FINDINGS

Complications of HHT such as stroke, brain abscess and intracranial hemorrhage are caused by pulmonary and cerebral AVMs (CAVMs) and can often be prevented by screening and treatment when possible. Screening and treatment of these AVMs will result in an increased life expectancy comparable with that of the general population as opposed to unscreened and untreated HHT patients.

SUMMARY

Screening of HHT patients and their first-degree relatives is recommended to prevent severe complications including stroke, brain abscess and intracranial hemorrhage.

Cannabidiol Increases Proliferation, Migration, Tubulogenesis, and Integrity of Human Brain Endothelial Cells through TRPV2 Activation

The effect of cannabidiol (CBD), a high-affinity agonist of the transient receptor potential vanilloid-2 (TRPV2) channel, has been poorly investigated in human brain microvessel endothelial cells (BMEC) forming the blood-brain barrier (BBB). TRPV2 expression and its role on Ca²⁺ cellular dynamics, trans-endothelial electrical resistance (TEER), cell viability and growth, migration, and tubulogenesis were evaluated in human primary cultures of BMEC (hPBMEC) or in the human cerebral microvessel endothelial hCMEC/D3 cell line. Abundant TRPV2 expression was measured in hCMEC/D3 and hPBMEC by qRT-PCR, Western blotting, nontargeted proteomics, and cellular immunofluorescence studies. Intracellular Ca²⁺ levels were increased by heat and CBD and blocked by the nonspecific TRP antagonist ruthenium red (RR) and the selective TRPV2 inhibitor tranilast (TNL) or by silencing cells with TRPV2 siRNA. CBD dose-dependently induced the hCMEC/D3 cell number (EC₅₀ 0.3 ± 0.1 μM), and this effect was fully abolished by TNL or TRPV2 siRNA. A wound healing assay showed that CBD induced cell migration, which was also inhibited by TNL or TRPV2 siRNA. Tubulogenesis of hCMEC/D3 cells in 3D matrigel cultures was significantly increased by 41 and 73% after a 7 or 24 h CBD treatment, respectively, and abolished by TNL. CBD also increased the TEER of hPBMEC monolayers cultured in transwell, and this was blocked by TNL. Our results show that CBD, at extracellular concentrations close to those observed in plasma of patients treated by CBD, induces proliferation, migration, tubulogenesis, and TEER increase in human brain endothelial cells, suggesting CBD might be a potent target for modulating the human BBB.

Medical Treatment for Epistaxis in Hereditary Hemorrhagic Telangiectasia: A Meta-analysis

Objectives

The aim of this study (PROSPERO ID: CRD42017081952) was to evaluate medical treatment for epistaxis from hereditary hemorrhagic telangiectasia (HHT).

Data Sources

PubMed, Embase, Scopus, and Cochrane Library databases were interrogated from their inceptions to November 2017.

Review Methods

Randomized clinical trials comparing medical treatment with placebo for epistaxis of HHT were included. We used a random-effects model to synthesize overall effects. Heterogeneity was evaluated with the I2 statistic.

Results

Eight studies were identified after systematic searching. The use of bevacizumab (BV), tranexamic acid, and estrogen, regardless of the route of administration, had no significant influence on frequency of episodes. Tamoxifen was superior to placebo in both frequency and severity of epistaxis. For duration of epistaxis, nasal spray BV, oral or nasal spray tranexamic acid, and nasal spray estrogen had no significant differences versus placebo, but patients receiving submucosal BV showed lower duration of epistaxis (mean difference: −219.00 min/mo, 95% CI: −271.90 to −166.10). Medical treatment for HHT had no significant changes of mean hemoglobin concentration (pooled mean difference: −0.23 mg/dL, 95% CI: −0.65 to 0.20, I2 = 0%) or quality of life (pooled standardized mean difference: 0.07, 95% CI: −0.16 to 0.30, I2 = 0%).

Conclusions

Only limited evidence provides a benefit on frequency of epistaxis by treatment with tamoxifen and duration of epistaxis by treatment with submucosal BV among patients with HHT. Mean hemoglobin concentration and quality of life were not influenced by medical treatment.

Computerized registry of patients with hemorrhagic hereditary telangiectasia (RiHHTa Registry) in Spain: Objectives, methods, and preliminary results

INTRODUCTION

Hereditary hemorrhagic telangiectasia (HHT) is a rare disease with autosomal dominant inheritance that causes systemic vascular affectation.

MATERIAL AND METHOD

After development a multicentric Spanish national registry, called RiHHTa, main clinical manifestations and diagnostic procedures of the first patients introduced are described.

RESULTS

141 patients were included, of which 91 (64.5%) were women. The mean age at diagnosis was 42 years. Mutations in the ACVRL1 gene predominated over the ENG gene. The initial symptom was recurrent epistaxis in 130 (92.2%) patients and in three (2.1%), brain abscess. Pulmonary arteriovenous (AV) fistula were detected in 36 (45%) of the 79 patients who underwent thoracic CT angiography. The contrast echocardiography detected very few bubbles (grade I) or none, in 36 (45%) of these 79 affected patients. In 43 (67.2%) of the 64 patients with an abdominal CT angiography, hepatic vascular malformations were detected, mostly telangiectasias, AV and arterio-portal fistula, and extrahepatic in 14 (10%) subjects. More than half of the patients were screened for the presence of brain arteriovenous malformations which was found in 3.9% of them. The upper part of the intestinal tube was the most (95%) affected region.

CONCLUSION

The RiHHTa Registry allows improving the management of patients with HHT. An inadequate use of thoracic CT angiography and the usefulness of abdominal CT angiography has been detected in order to define subtypes of hepatic vascular involvement and detect extrahepatic vascular involvement.

ALK1 signaling in development and disease: new paradigms

Activin A receptor like type 1 (ALK1) is a transmembrane serine/threonine receptor kinase in the transforming growth factor-beta receptor family that is expressed on endothelial cells. Defects in ALK1 signaling cause the autosomal dominant vascular disorder, hereditary hemorrhagic telangiectasia (HHT), which is characterized by development of direct connections between arteries and veins, or arteriovenous malformations (AVMs). Although previous studies have implicated ALK1 in various aspects of sprouting angiogenesis, including tip/stalk cell selection, migration, and proliferation, recent work suggests an intriguing role for ALK1 in transducing a flow-based signal that governs directed endothelial cell migration within patent, perfused vessels. In this review, we present an updated view of the mechanism of ALK1 signaling, put forth a unified hypothesis to explain the cellular missteps that lead to AVMs associated with ALK1 deficiency, and discuss emerging roles for ALK1 signaling in diseases beyond HHT.

Endoglin and alk1 as therapeutic targets for hereditary hemorrhagic telangiectasia

INTRODUCTION

Hereditary Haemorrhagic Telangiectasia (HHT) is as an autosomal dominant trait characterized by frequent nose bleeds, mucocutaneous telangiectases, arteriovenous malformations (AVMs) of the lung, liver and brain, and gastrointestinal bleedings due to telangiectases. HHT is originated by mutations in genes whose encoded proteins are involved in the transforming growth factor β (TGF-β) family signalling of vascular endothelial cells. In spite of the great advances in the diagnosis as well as in the molecular, cellular and animal models of HHT, the current treatments remain just at the palliative level. Areas covered: Pathogenic mutations in genes coding for the TGF-β receptors endoglin (ENG) (HHT1) or the activin receptor-like kinase-1 (ACVRL1 or ALK1) (HHT2), are responsible for more than 80% of patients with HHT. Therefore, ENG and ALK1 are the main potential therapeutic targets for HHT and the focus of this review. The current status of the preclinical and clinical studies, including the anti-angiogenic strategy, have been addressed. Expert opinion: Endoglin and ALK1 are attractive therapeutic targets in HHT. Because haploinsufficiency is the pathogenic mechanism in HHT, several therapeutic approaches able to enhance protein expression and/or function of endoglin and ALK1 are keys to find novel and efficient treatments for the disease.

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.

Not lost in translation: Emerging clinical importance of the G protein-coupled estrogen receptor GPER

It has been 20years that the G protein-coupled estrogen receptor (GPER) was cloned as the orphan receptor GPR30 from multiple cellular sources, including vascular endothelial cells. Here, I will provide an overview of estrogen biology and the historical background leading to the discovery of rapid vascular estrogen signaling. I will also review the recent advances in the understanding of the mechanisms underlying GPER function, its role in physiology and disease, some of the currently available GPER-targeting drugs approved for clinical use such as SERMs (selective estrogen receptor modulators) and SERDs (selective estrogen receptor downregulators). Many of currently used drugs such as tamoxifen, raloxifene, or faslodex™/fulvestrant were discovered targeting GPER many years after they had been introduced to the clinics for entirely different purposes. This has important implications for the clinical use of these drugs and their modes of action, which I have termed 'reverse translational medicine'. In addition, environmental pollutants known as 'endocrine disruptors' have been found to bind to GPER. This article also discusses recent evidence in these areas as well as opportunities in translational clinical medicine and GPER research, including medical genetics, personalized medicine, prevention, and its theranostic use.