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.

Quality of life in patients with hereditary haemorrhagic telangiectasia (HHT).

BACKGROUND: There are very few studies about general quality of life parameters, standards for the description of health status and comparison with general population data on patients with Hereditary hemorrhagic telangiectasia (HHT), a rare disease in which epistaxis is a cardinal symptom. PURPOSE: To assess the quality of life in a population of Spanish patients with HHT and compare it with the general population. DESIGN AND METHODS: Between January 1st 2005 and December 31st 2013, 187 adult patients diagnosed with HHT who were admitted to the HHT Unit of the Hospital Sierrallana, completed on their first visit, the EuroQol 5D-3L (five dimensions and three levels) quality of life descriptive test and the visual analog scale (VAS). The numerical social index value was also determined and the subjective effect of the nasal epistaxis on their quality of life was estimated classified as mild, moderate or severe. RESULTS: Patients with HHT had greater problems than the general population in the five dimensions of the EuroQol 5D-3L, particularly considering pain/discomfort and anxiety/depression. In the VAS and the social index value, patients with HHT also scored lower than the general population, particularly older patients, males, and patients with HHT2. They also had values similar to those of populations with chronic illnesses. The subjective perception of the severity of epistaxis correlated strongly with the VAS and social index values. CONCLUSIONS: The quality of life of patients with HHT, estimated using the EuroQol 5D-3L scale, is affected across all dimensions. The scores are similar to those seen in cases of other chronic diseases. Older patients, males and the carriers of the ACVRL1 mutation generally have worse scores on these scales. The VAS and the social index value are index that correlate well with the severity of the clinical symptoms associated mainly with epistaxis.

Vascular diseases of the liver. Clinical Guidelines from the Catalan Society of Digestology and the Spanish Association for the Study of the Liver. / Enfermedades vasculares del hígado. Guías Clínicas de la Sociedad Catalana de Digestología y de la Asociación Española para el Estudio del Hígado.

Despite their relatively low prevalence, vascular diseases of the liver represent a significant health problem in the field of liver disease. A common characteristic shared by many such diseases is their propensity to cause portal hypertension together with increased morbidity and mortality. These diseases are often diagnosed in young patients and their delayed diagnosis and/or inappropriate treatment can greatly reduce life expectancy. This article reviews the current body of evidence concerning Budd-Chiari syndrome, non-cirrhotic portal vein thrombosis, idiopathic portal hypertension, sinusoidal obstruction syndrome, hepatic vascular malformations in hereditary haemorrhagic telangiectasia, cirrhotic portal vein thrombosis and other rarer vascular diseases including arterioportal fistulas. It also includes a section on the diagnostic imaging of vascular diseases of the liver and their treatment from a haematological standpoint (study of thrombotic diathesis and anticoagulation therapy). All recommendations are based on published studies extracted from PubMed. The quality of evidence and strength of recommendations were rated in accordance with the GRADE system (Grading of Recommendations, Assessment Development and Evaluation). In the absence of sufficient evidence, recommendations were based on the opinion of the committee that produced the guide.

MiR-205 is downregulated in hereditary hemorrhagic telangiectasia and impairs TGF-beta signaling pathways in endothelial cells.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by arteriovenous malformations and hemorrhages. This vascular disease results mainly from mutations in 2 genes involved in the TGF-ß pathway (ENG and ALK1) that are exclusively expressed by endothelial cells. The present study identified miR-27a and miR-205 as two circulating miRNAs differentially expressed in HHT patients. The plasma levels of miR-27a are elevated while those of miR-205 are reduced in both HHT1 and HHT2 patients compared to healthy controls. The role of miR-205 in endothelial cells was further investigated. Our data indicates that miR-205 expression displaces the TGF-ß balance towards the anti-angiogenic side by targeting Smad1 and Smad4. In line, overexpression of miR-205 in endothelial cells reduces proliferation, migration and tube formation while its inhibition shows opposite effects. This study not only suggests that detection of circulating miRNA (miR-27a and miR-205) could help for the screening of HHT patients but also provides a functional link between the deregulated expression of miR-205 and the HHT phenotype.

Copy number variations in endoglin locus: mapping of large deletions in Spanish families with hereditary hemorrhagic telangiectasia type 1.

BACKGROUND: The hereditary hemorrhagic telangiectasia syndrome (HHT), also known as the Rendu-Osler-Weber syndrome is a multiorganic vascular disorder inherited as an autosomal dominant trait. Diagnostic clinical criteria include: epistaxis, telangiectases in mucocutaneous and gastrointestinal sites, arteriovenous malformations (AVMs) most commonly found in pulmonary, hepatic and cerebral circulations, and familial inheritance. HHT is transmitted in 90% of the cases as an autosomal dominant condition due to mutations in either endoglin (ENG), or activin receptor-like kinase 1 (ACVRL1/ALK1) genes (HHT type 1 and 2, respectively). METHODS: We have carried out a genetic analysis of four independent Spanish families with HHT clinical criteria, which has permitted the identification of new large deletions in ENG. These mutations were first detected using the MLPA technique and subsequently, the deletion breakpoints were mapped using a customized copy number variation (CNV) microarray. The array was designed to cover the ENG gene and surrounding areas. RESULTS: All tested families carried large deletions ranging from 3-kb to 100-kb, involving the ENG gene promoter, several ENG exons, and the two downstream genes FGSH and CDK9. Interestingly, common breakpoints coincident with Alu repetitive sequences were found among these families. CONCLUSIONS: The systematic hybridization of DNA from HHT families, with deletions or duplications, to custom designed microarrays, could allow the mapping of breakpoints, coincident with repetitive Alu sequences that might act as "hot spots" in the development of chromosomal anomalies.

Local sclerotherapy with polydocanol (Aethoxysklerol®) for the treatment of Epistaxis in Rendu-Osler-Weber or Hereditary Hemorrhagic Telangiectasia (HHT): 15 years of experience.

Hereditary Haemorrhagic Telangiectasia or Rendu-Osler-Weber syndrome is a rare autosomal dominant vascular disease characterized by mucocutaneous and gastrointestinal telangiectases and localized arteriovenous malformations in lung, brain and liver. Epistaxis, due to rupture of telangiectases of the nasal mucosa, is the most frequent clinical manifestation, leading in many cases to severe impairment of the quality of life in the patients. Though several treatments have been used to reduce epistaxis, none have been completely effective, with the exception of polydocanol (Aethoxysklerol®) in submucosal or subpericondrial injections, which was first presented in 2000 with very good results. After fifteen years using polydocanol in submucosal injections on 45 patients and with nearly 300 injections, we have observed that in 95% of all cases, their nose bleeds improved with respect to frequency and quantity without any important side effects. There was just one case of septal perforation, another with increased septal perforation, and one patient who suffered from dizziness and blurred vision for a few minutes. In this paper the results obtained using this technique over a fifteen-year period will be presented and evaluated.

[Rendu-Osler disease with hepatic involvement: first transplant in Spain]. / Enfermedad de Rendu-Osler con afectación hepática: primer trasplante en España.

BACKGROUND AND OBJECTIVE: Rendu-Osler's disease (RO) is a rare systemic vascular disorder due to a fibrovascular dysplasia in the endothelium of vessels. Recurrent epistaxis is the main clinical manifestation, but arteriovenous malformations (AVMs) can involve many organs, including the liver. Hepatic involvement can develop refractory heart failure due to large shunts between the hepatic veins and the hepatic artery. Embolization and hepatic artery ligation have also demonstrated to reduce cardiac output in RO, but these therapeutic options have significant morbidity and complications such as necrosis or liver failure. CASE REPORT: We report the case of a 48 years old woman diagnosed in 1987 with RO and significant hepatic involvement, with multiple fistulas between veins and hepatic artery. In the following years she developed progressive heart failure that limited her quality of life. RESULTS: She was admitted on more times with heart failure and her dyspnea worsened progressively up to NYHA IV. At this time, an echocardiograph control showed an output cardiac about 10.6l/min. On December 2004, although the medical treatment, the worsening of the patient went on, so we finally decided to conduct a liver transplant that resolved the symptoms and the hyperdynamic circulation. Despite the fact that liver transplant has become without doubt into the best treatment for these patients in the last years. CONCLUSIONS: This is the first one done in Spain. There are different therapies available for these patients, but the indications for transplantation are greater each day, mainly due to the risks of the other options. Currently the stated guidelines are heart failure and portal hypertension refractory to medical treatment. So in these situations, liver transplantation should be proposed in the early stages of the disease and may be the only viable option.

Safety of thalidomide and bevacizumab in patients with hereditary hemorrhagic telangiectasia.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is a multisystemic inherited vascular dysplasia that leads to nosebleeds and visceral arteriovenous malformations (AVMs). Anti-angiogenic drugs thalidomide and bevacizumab have been increasingly used off-label with variable results. The HHT working group within the ERN for Rare Multisystemic Vascular Diseases (VASCERN), developed a questionnaire-based retrospective capture of adverse events (AEs) classified using the Common Terminology Criteria for Adverse Events. RESULTS: Sixty-nine HHT patients received bevacizumab, 37 (50.6%) for high output cardiac failure/hepatic AVMs, and 32 (49.4%) for bleeding; the 69 patients received bevacizumab for a mean of 11 months for a total of 63.8 person/years treatment. 67 received thalidomide, all for epistaxis and/or gastrointestinal bleeding; they received thalidomide for a mean of 13.4 months/patient for a total of 75 person/years treatment. AEs were reported in 58 patients, 33 with bevacizumab, 37 with thalidomide. 32 grade 1-3 AEs related to bevacizumab were reported with an average incidence rate of 50 per 100 person-years. 34 grade 1-3 AEs related to thalidomide were reported with an average incidence rate of 45.3 per 100 person-years. Bevacizumab AEs were more common in females (27 AEs in 46 women) than males (6 in 23, p < 0.001). Thalidomide AEs occurred at more similar rates in males (25 AEs in 41 men, 60.9%) and females (12 in 26 (46.2%), but were more common in ENG patients (17 in 17) than in ACVRL1 (14 in 34, p < 0.0001). For bevacizumab, the most common reports were of joint pains (7/69, 10%), headache (3/69, 4.4%) and proteinuria (2/69, 3%), and for thalidomide, peripheral neuropathy (12/67, 18%); drowsiness (8/67, 12%); and dizziness (6/67, 9%). Fatal adverse events were more common in males (p = 0.009), and in patients with ENG pathogenic variants (p = 0.012). One fatal AE was possibly related to bevacizumab (average incidence rate: 1.5 per 100 person-years); 3 fatal AEs were possibly related to thalidomide (average incidence rate: 4 per 100 person-years). CONCLUSIONS: With potential increase in use of Bevacizumab and Thalidomide in HHT patients, data presented support appropriate weighing of the toxicities which can arise in HHT settings and the practice recommendations for their prevention and management.

Mutation study of Spanish patients with hereditary hemorrhagic telangiectasia.

BACKGROUND: Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant and age-dependent vascular disorder characterised mainly by mutations in the Endoglin (ENG) or activin receptor-like kinase-1 (ALK1, ACVRL1) genes. METHODS: Here, we have identified 22 ALK1 mutations and 15 ENG mutations, many of which had not previously been reported, in independent Spanish families afflicted with HHT. RESULTS: We identified mutations in thirty-seven unrelated families. A detailed analysis of clinical symptoms was recorded for each patient analyzed, with a higher significant presence of pulmonary arteriovenous malformations (PAVM) in HHT1 patients over HHT2. Twenty-two mutations in ALK1 and fifteen in ENG genes were identified. Many of them, almost half, represented new mutations in ALK1 and in ENG. Missense mutations in ENG and ALK1 were localized in a tridimensional protein structure model. CONCLUSION: Overall, ALK1 mutations (HHT2) were predominant over ENG mutations (HHT1) in our Spanish population, in agreement with previous data from our country and other Mediterranean countries (France, Italy), but different to Northern Europe or North America. There was a significant increase of PAVM associated with HHT1 over HHT2 in these families.

Therapeutic action of tranexamic acid in hereditary haemorrhagic telangiectasia (HHT): regulation of ALK-1/endoglin pathway in endothelial cells.

Recurrent epistaxis is the most frequent clinical manifestation of hereditary haemorrhagic telangiectasia (HHT). Its treatment is difficult. Our objective was to assess the use of tranexamic acid (TA), an antifibrinolytic drug, for the treatment of epistaxis in HHT patients and to investigate in vitro the effects of TA over endoglin and ALK-1 expression and activity in endothelial cells. A prospective study was carried out on patients with epistaxis treated with oral TA in the HHT Unit of Sierrallana Hospital (Cantabria, Spain). Primary cultures of endothelial cells were treated with TA to measure the levels of endoglin and ALK-1 at the cell surface by flow cytometry. RNA levels were also measured by real-time PCR, and the transcriptional effects of TA on reporters for endoglin, ALK-1 and the endoglin/ALK-1 TGF-beta pathway were assessed. The results showed that the fourteen HHT patients treated orally with TA improved, and the frequency and severity of their epistaxis were decreased. No complications derived from the treatment were observed. Cultured endothelial cells incubated with TA exhibited increased levels of endoglin and ALK-1 at the protein and mRNA levels, enhanced TGF-beta signaling, and improved endothelial cell functions like tubulogenesis and migration. In summary, oral administration of TA proved beneficial for epistaxis treatment in selected patients with HHT. In addition to its already reported antifibrinolytic effects, TA stimulates the expression ofALK-1 and endoglin, as well as the activity of the ALK-1/endoglin pathway.

[Treatment of epistaxes in hereditary haemorrhagic telangiectasia (Rendu-Osler-Weber disease) with tranexamic acid]. / Tratamiento de las epistaxis en la telangiectasia hemorrágica hereditaria (enfermedad de Rendu-Osler-Weber) con ácido tranexámico.

OBJECTIVE: Recurrent epistaxis is the most frequent clinical manifestation of hereditary haemorrhagic telangiectasia (HHT). Its treatment occasionally presents difficulties as there is no consensus on the appropriate therapeutic protocol. Our objective was to explore the utility of oral tranexamic acid for the treatment of epistaxes in HHT patients. PATIENTS AND METHOD: A 3-year prospective study was carried on HHT patients with epistaxis treated with oral tranexamic acid in the HHT unit at our hospital. RESULTS: Ten patients with HHT were treated with oral tranexamic acid during the study. Most of them improved both the frequency and severity of their epistaxis and were satisfied with the treatment. No treatment-related complications were recorded. Two patients needed more aggressive treatments to control epistaxis. CONCLUSIONS: Oral tranexamic acid is useful for achieving significant reductions in epistaxis frequency and intensity in selected patients with HHT. In those presenting severe epistaxis, however, it may need to be combined with more aggressive therapies.

Mutation study of Spanish patients with hereditary hemorrhagic telangiectasia and expression analysis of Endoglin and ALK1.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant and age-dependent vascular disorder originated by mutations in Endoglin (ENG) or activin receptor-like kinase-1 (ALK1, ACVRL1) genes. The first large series HHT analysis in Spanish population has identified mutations in 17 unrelated families. Ten different mutations in ALK1 and six in ENG genes were found. Six unrelated families had a mutation in ENG gene, four representing new mutations, p.Y258fs, pV323fs, p.F279fs (c.834_837del CTTC), and p.F279fsdupC. Eleven unrelated families harboured mutations in ALK1; ten were new mutations identified as p.H328P, p.R145fs, p.G68C, p.A377T, p.H297R, p.M376T, p.C36Y, p.H328P, p.T82del and p.R47P. Overall, ALK1 mutations (HHT2) were predominant over ENG mutations (HHT1), in agreement with data reported for other Mediterranean countries (France, Italy), but at variance with Northern Europe or North America. Endoglin expression in HHT1 or HHT2 activated monocytes and blood outgrowth endothelial cells (BOECs) from older patients was well below the theoretical 50% level expected from the HHT1 haploinsufficiency model, suggesting that the pathogenic endoglin haploinsufficiency leading to the HHT phenotype is age-dependent. Interestingly, ALK1 protein levels of HHT BOECs in some missense ALK1 mutants were similar to controls. In vitro expression of these ALK1 constructs suggests that, in addition to the haploinsufficiency model, certain ALK1 mutants may inhibit the function of the wild type allele.

Blood outgrowth endothelial cells from Hereditary Haemorrhagic Telangiectasia patients reveal abnormalities compatible with vascular lesions.

OBJECTIVE: Hereditary haemorrhagic telangiectasia (HHT) is originated by mutations in endoglin (HHT1) and ALK1 (HHT2) genes. The purpose of this work was to isolate and characterize circulating endothelial cells from HHT patients. METHODS: Pure primary cultures of blood outgrowth endothelial cells (BOECs) were obtained from 50 ml of peripheral blood by selection on collagen plates with endothelial medium. RESULTS: The amount of endoglin in HHT1-BOECs is half the controls, but HHT2-BOECs are also endoglin-deficient. Since the TGF-beta/ALK1 pathway activates the endoglin promoter activity, these results suggest the involvement of ALK1 in endoglin gene expression. Endothelial TGF-beta pathways, mediated by ALK1 and ALK5, are impaired in HHT cells. HHT-BOECs show disorganized and depolymerized actin fibers, as compared to the organized stress fibers of healthy-BOECs. Functionally, HHT-BOECs have impaired tube formation, in contrast with the cord-like structures derived from normal donors. CONCLUSIONS: Decreased endoglin expression, impaired TGF-beta signalling, disorganized cytoskeleton, and failure to form cord-like structures are common characteristics of endothelial cells from HHT patients. These features may lead to fragility of small vessels and bleeding characteristic of the HHT vascular dysplasia and to a disrupted and abnormal angiogenesis, which may explain the clinical symptoms associated with this disease.

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

Hereditary haemorrhagic telangiectasia (HHT), or Rendu-Osler-Weber syndrome, is a dominant genetic vascular disorder. In HHT, blood vessels are weak and prone to bleeding, leading to epistaxis and anaemia, severely affecting patients' quality of life. Development of vascular malformations in HHT patients is originated mainly by mutations in ACVRL1/ALK1 (activin receptor-like kinase type I) or Endoglin (ENG) genes. These genes encode proteins of the TGF-ß signalling pathway in endothelial cells, controlling angiogenesis. Haploinsufficiency of these proteins is the basis of HHT pathogenicity. It was our objective to study the efficiency of Bazedoxifene, a selective estrogen receptor modulator (SERM) in HHT, looking for a decrease in epistaxis, and understanding the underlying molecular mechanism. Plasma samples of five HHT patients were collected before, and after 1 and 3 months of Bazedoxifene treatment. ENG and ALK1 expression in activated mononuclear cells derived from blood, as well as VEGF plasma levels, were measured. Quantification of Endoglin and ALK1 mRNA was done in endothelial cells derived from HHT and healthy donors, after in vitro treatment with Bazedoxifene. Angiogenesis was also measured by tubulogenesis and wound healing assays. Upon Bazedoxifene treatment, haemoglobin levels of HHT patients increased and the quantity and frequency of epistaxis decreased. Bazedoxifene increased Endoglin and ALK1 mRNA levels, in cells derived from blood samples and in cultured endothelial cells, promoting tube formation. In conclusion, Bazedoxifene seems to decrease bleeding in HHT by partial compensation of haploinsufficiency. The results shown here are the basis of a new orphan drug designation for HHT by the European Medicine Agency (EMA).

Screening pulmonary arteriovenous malformations in a large cohort of Spanish patients with hemorrhagic hereditary telangiectasia.

BACKGROUND AND OBJECTIVES: Because of the serious nature of potential complications, screening for pulmonary arteriovenous malformations is required in patients with hereditary hemorrhagic telangiectasia. The aim of this study was to evaluate the utility of contrast echocardiography and compare the performance of two contrast agents: agitated saline and Gelofusine. MATERIAL AND METHODS: Two hundred and five patients screened for PAVMs using TTCE and computed tomography (CT) performed with an interval of less than 180days. Contrast echocardiography studies were graded on a 4-point semiquantitative scale based on the amount of microbubbles seen in left heart chambers. RESULTS: Positive TTCE findings were seen in 137 (66.8%) patients, whereas CT confirmed PAVMs in 59 (43.1%). Two of 67 grade 1 patients; 18 of 42 grade 2; 17 of 22 grade 3 and all grade 4 had PAVMs on CT. Embolotherapy was feasible in 38.9% patients in grade 2 and 82.3% and 95.2% in grades 3-4. No patients in grade 1 were embolized. The mean cardiac cycle in which bubbles were first seen in the left heart in patients without and with PAVMs on CT was 6.1 and 3.9 (p<0.0001). Compared to saline, Gelofusine produced an overall increase in grade. CONCLUSIONS: No grade 1 patients had treatable PAVMs. There is a need for improvement in the selection of patients for CT in grade 2, where less than half have PAVMs on CT. The cardiac cycle may help to differentiate between patients with and without PAVMs. Gelofusine was not better than saline for PAVM screening.

[Hereditary hemorrhagic telangiectasia]. / Telangiectasia hemorrágica hereditaria.

Hereditary Hemorrhagic Telangiectasia (HHT) or Rendu-Osler-Weber disease is a genetic disorder with a dominant autosomic transmission. Its prevalence is estimated in one in 5-8,000 individuals. Two different mutations have been described involving endoglin and ALK-1 genes, resulting in HHT type 1 and 2 respectively. It is characterized by the occurrence of spontaneous and recurrent episodes of epistaxis, telangiectasias and the presence of visceral arteriovenous malformations (mainly affecting lungs, liver, brain and digestive tract) which are responsible for the clinical manifestations and constitute a basic point in the diagnostic criteria of Curaçao. The aim of this article is to review the pathogenesis, clinical aspects, screening procedures to disclose the visceral involvement and the therapeutic options of this rare disease.

Propranolol as antiangiogenic candidate for the therapy of hereditary haemorrhagic telangiectasia.

The ß-blocker propranolol, originally designed for cardiological indications (angina, cardiac arrhythmias and high blood pressure), is nowadays, considered the most efficient drug for the treatment in infantile haemangiomas (IH), a vascular tumour that affects 5-10% of all infants. However, its potential therapeutic benefits in other vascular anomalies remain to be explored. In the present work we have assessed the impact of propranolol in endothelial cell cultures to test if this drug could be used in the vascular disease hereditary haemorrhagic telangiectasia (HHT). This rare disease is the result of abnormal angiogenesis with epistaxis, mucocutaneous and gastrointestinal telangiectases, as well as arteriovenous malformations in several organs, as clinical manifestations. Mutations in Endoglin (ENG) and ACVLR1 (ALK1) genes, lead to HHT1 and HHT2, respectively. Endoglin and ALK1 are involved in the TGF-ß1 signalling pathway and play a critical role for the proper development of the blood vessels. As HHT is due to a deregulation of key angiogenic factors, inhibitors of angiogenesis have been used to normalise the nasal vasculature eliminating epistaxis derived from telangiectases. Thus, the antiangiogenic properties of propranolol were tested in endothelial cells. The drug was able to decrease cellular migration and tube formation, concomitantly with reduced RNA and protein levels of ENG and ALK1. Moreover, the drug showed apoptotic effects which could explain cell death in IH. Interestingly, propranolol showed some profibrinolytic activity, decreasing PAI-1 levels. These results suggest that local administration of propranolol in the nose mucosa to control epistaxis might be a potential therapeutic approach in HHT.

Estrogen therapy for hereditary haemorrhagic telangiectasia (HHT): Effects of raloxifene, on Endoglin and ALK1 expression in endothelial cells.

Hereditary haemorrhagic telangiectasia (HHT), or Rendu-Osler-Weber syndrome, is an autosomal dominant vascular disease. The clinical manifestations are epistaxis, mucocutaneous and gastrointestinal telangiectases, and arteriovenous malformations. There are two predominant types of HHT caused by mutations in Endoglin (ENG) and activin receptor-like kinase 1 (ALK1) (ACVRL1) genes, HHT1 and HHT2, respectively. No cure for HHT has been found and there is a current need to find new effective drug treatments for the disease. Some patients show severe epistaxis which interferes with their quality of life. We report preliminary results obtained with Raloxifene to treat epistaxis in postmenopausal HHT women diagnosed with osteoporosis. We tried to unravel the molecular mechanisms involved in the therapeutic effects of raloxifene. ENG and ACVRL1 genes code for proteins involved in the transforming growth factor beta pathway and it is widely accepted that haploinsufficiency is the origin for the pathogenicity of HHT. Therefore, identification of drugs able to increase the expression of those genes is essential to propose new therapies for HHT. In vitro results show that raloxifene increases the protein and mRNA expression of ENG and ALK1 in cultured endothelial cells. Raloxifene also stimulates the promoter activity of these genes, suggesting a transcriptional regulation of ENG and ALK1. Furthermore, Raloxifene improved endothelial cell functions like tubulogenesis and migration in agreement with the reported functional roles of Endoglin and ALK1. Our pilot study provides a further hint that oral administration of raloxifene may be beneficial for epistaxis treatment in HHT menopausal women. The molecular mechanisms of raloxifene involve counteracting the haploinsufficiency of ENG and ALK1.

A review on clinical management and pharmacological therapy on hereditary haemorrhagic telangiectasia (HHT).

Hereditary Haemorrhagic Telangiectasia (HHT) or Rendu-Osler-Weber syndrome, is an autosomal dominant rare disease characterized by localized angiodysplasia. This is manifested as epistaxis, mucocutaneous and gastrointestinal telangiectases, and arteriovenous malformations in the pulmonary, cerebral or hepatic circulation. The prevalence is between 1 in 5,000 to 8,000, although it is higher in some regions. The most frequent clinical manifestation of HHT is epistaxis, normally from light to moderate from the 4(th) decade of life. However, many patients show severe epistaxis which may interfere with their quality of life. The epistaxis is due to telangiectasia on the nasal mucosa. These are focally dilated postcapilar venules, which in advanced phases show many layers of smooth muscle cells without elastic fibers, and very frequently directly connect with dilated arterioles. As a consequence of these vascular alterations, telangiectases are very sensitive to slight trauma and even to the friction with the air when breathing, which gives rise to nose bleeds. Unfortunately, there is no optimal pharmacological treatment for the epistaxis in HHT. The use of antifibrinolytic agents for the treatment of HHT has been studied recently by our group as an effective relief for nasal and gastric haemorrhages. This work represents a systematic review and the beginning of a systematic laboratory work we are now conducting in our lab to screen for "orphan drugs" as therapeutic agents in HHT. In this context, the use of hormones, immunosuppresants and anti-angiogenic agents are under preclinical study in our laboratory.