Molecular and Cellular Characterization of Primary Endothelial Cells from a Familial Cavernomatosis Patient

Cerebral cavernous malformation (CCM) or familial cavernomatosis is a rare, autosomal dominant, inherited disease characterized by the presence of vascular malformations consisting of blood vessels with an abnormal structure in the form of clusters. Based on the altered gene (CCM1/Krit1, CCM2, CCM3) and its origin (spontaneous or familial), different types of this disease can be found. In this work we have isolated and cultivated primary endothelial cells (ECs) from peripheral blood of a type 1 CCM patient. Differential functional and gene expression profiles of these cells were analyzed and compared to primary ECs from a healthy donor. The mutation of the familial index case consisted of a heterozygous point mutation in the position +1 splicing consensus between exons 15 and 16, causing failure in RNA processing and in the final protein. Furthermore, gene expression analysis by quantitative PCR revealed a decreased expression of genes involved in intercellular junction formation, angiogenesis, and vascular homeostasis. Cell biology analysis showed that CCM1 ECs were impaired in angiogenesis and cell migration. Taken together, the results obtained suggest that the alterations found in CCM1 ECs are already present in the heterozygous condition, suffering from vascular impairment and somewhat predisposed to vascular damage.

Mutation in Chek2 triggers von Hippel-Lindau hemangioblastoma growth

PURPOSE

Von Hippel-Lindau (VHL) is a rare inherited disease mainly characterized by the growth of tumours, predominantly hemangioblastomas (Hbs) in the CNS and retina, and renal carcinomas. The natural history of VHL disease is variable, differing in the age of onset and its penetrance, even among relatives. Unfortunately, sometimes VHL shows more severe than average: the onset starts in adolescence, and surgeries are required almost every year. In these cases, the factor that triggers the appearance and growth of Hbs usually remains unknown, although additional mutations are suspected.

METHODS

We present the case of a VHL patient whose first surgery was at 13 years of age. Then, along his next 8 years, he has undergone 5 surgeries for resection of 10 CNS Hbs. To clarify this severe VHL condition, DNA from a CNS Hb and white blood cells (WBC) was sequenced using next-generation sequencing technology.

RESULTS

Massive DNA sequencing of the WBC (germ line) revealed a pathogenic mutation in CHEK2 and the complete loss of a VHL allele (both tumour suppressors). Moreover, in the tumour sample, several mutations, in BRAF1 and PTPN11 were found. Familiar segregation studies showed that CHEK2 mutation was in the maternal lineage, while VHL was inherited by paternal lineage.

CONCLUSIONS

Finally, clinical history correlated to the different genotypes in the family, concluding that the severity of these VHL manifestations are due to both, VHL-and-CHEK2 mutations. This case report aims to notice the importance of deeper genetic analyses, in inherited rare diseases, to uncover non-expected mutations.

The Role of Propranolol as a Repurposed Drug in Rare Vascular Diseases

Rare Diseases (RD) are defined by their prevalence in less than 5 in 10,000 of the general population. Considered individually, each RD may seem insignificant, but together they add up to more than 7000 different diseases. Research in RD is not attractive for pharmaceutical companies since it is unlikely to recover development costs for medicines aimed to small numbers of patients. Since most of these diseases are life threatening, this fact underscores the urgent need for treatments. Drug repurposing consists of identifying new uses for approved drugs outside the scope of the original medical indication. It is an alternative option in drug development and represents a viable and risk-managed strategy to develop for RDs. In 2008, the “off label” therapeutic benefits of propranolol were described in the benign tumor Infantile Hemangioma. Propranolol, initially prescribed for high blood pressure, irregular heart rate, essential tremor, and anxiety, has, in the last decade, shown increasing evidence of its antiangiogenic, pro-apoptotic, vasoconstrictor and anti-inflammatory properties in different RDs, including vascular or oncological pathologies. This review highlights the finished and ongoing trials in which propranolol has arisen as a good repurposing drug for improving the health condition in RDs.

Blockade of β2-Adrenergic Receptor Reduces Inflammation and Oxidative Stress in Clear Cell Renal Cell Carcinoma

Von Hippel-Lindau (VHL) syndrome is a rare inherited cancer disease where the lack of VHL protein triggers the development of multisystemic tumors such us retinal hemangioblastomas (HBs), CNS-HBs, and clear cell renal cell carcinoma (ccRCC). Since standard therapies in VHL have shown limited response, leaving surgery as the only possible treatment, targeting of the β2-adrenergic receptor (ADRB2) has shown therapeutic antitumor benefits on VHL-retinal HBs (clinical trial), VHL-CNS HBs, and VHL-ccRCC (in vitro and in vivo). In the present study, we wanted to look deep into the effects of the ADRB2 blockers propranolol and ICI-118,551 on two main aspects of cancer progression: (i) the changes on the inflammatory response of ccRCC cells; and (ii) the modulation on the Warburg effect (glycolytic metabolism), concretely, on the expression of genes involved in the cell reactive oxygen species (ROS) balance and levels. Accordingly, in vitro studies with primary VHL-ccRCC and 786-O cells measuring ROS levels, ROS-expression of detoxifying enzymes, and the expression of p65/NF-κB targets by RT-PCR were carried out. Furthermore, histological analyses of ccRCC samples from heterotopic mouse xenografts were performed. The obtained results show that ADRB2 blockade in ccRCC cells reduces the level of oxidative stress and stabilizes the inflammatory response. Thus, these data further support the idea of targeting ADRB2 as a promising strategy for the treatment of VHL and other non-VHL tumors.

CIBERER: Spanish National Network for Research on Rare Diseases: a highly productive collaborative initiative

CIBER (Center for Biomedical Network Research; Centro de Investigación Biomédica En Red) is a public national consortium created in 2006 under the umbrella of the Spanish National Institute of Health Carlos III (ISCIII). This innovative research structure comprises 11 different specific areas dedicated to the main public health priorities in the National Health System. CIBERER, the thematic area of CIBER focused on rare diseases (RDs) currently consists of 75 research groups belonging to universities, research centers, and hospitals of the entire country. CIBERER's mission is to be a center prioritizing and favoring collaboration and cooperation between biomedical and clinical research groups, with special emphasis on the aspects of genetic, molecular, biochemical, and cellular research of RDs. This research is the basis for providing new tools for the diagnosis and therapy of low‐prevalence diseases, in line with the International Rare Diseases Research Consortium (IRDiRC) objectives, thus favoring translational research between the scientific environment of the laboratory and the clinical setting of health centers. In this article, we intend to review CIBERER's 15‐year journey and summarize the main results obtained in terms of internationalization, scientific production, contributions toward the discovery of new therapies and novel genes associated to diseases, cooperation with patients' associations and many other topics related to RD research.

The Endothelial Landscape and Its Role in Von Hippel-Lindau Disease

Von Hippel–Lindau disease (VHL) is a rare hereditary disease characterized by the predisposal to develop different types of highly vascularized tumors. VHL patients carry a VHL mutation that causes partial lack of functional VHL protein (pVHL) in all cells, and a total lack thereof in cells harboring a second hit mutation. Absence of pVHL generates a prolonged state of pseudo-hypoxia in the cell due to accumulation of hypoxia inducible factor, an important transcription factor regulating pro-tumorigenic genes. The work here presented focuses on characterizing the endothelium of VHL patients, by means of blood outgrowth endothelial cells (BOECs). Transcriptome analysis of VHL-derived BOECs, further supported by in vitro assays, shows that these cells are at a disadvantage, as evidenced by loss of cell adhesion capacity, angiogenesis defects, and immune response and oxidative metabolic gene downregulation, which induce oxidative stress. These results suggest that the endothelium of VHL patients is functionally compromised and more susceptible to tumor development. These findings contribute to shedding light on the vascular landscape of VHL patients preceding the second hit mutation in the VHL gene. This knowledge could be useful in searching for new therapies for these patients and other vascular diseases.

Sclerotherapy on Demand with Polidocanol to Treat HHT Nosebleeds

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

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.

CLN5 in heterozygosis may protect against the development of tumors in a VHL patient

Von Hippel-Lindau syndrome (VHL) is a rare disease of dominant inheritance that increases susceptibility to tumor development, with a complete penetrance at the age of 60. In this report, we present the unprecedented case of a VHL carrier who remains healthy at 72. Under the course of this study, it was discovered that this patient carries a mutation for a second rare disease, Neuronal Ceroid Lipofuscinosis (NCL or CNL). We hypothesize that the CLN mutation she carries offers a protective effect, preventing tumor development in the cells potentially suffering a VHL second hit mutation. To test this hypothesis, we ran a series of molecular experiments and confirmed that cell viability of primary endothelial cells decreases upon CLN5 silencing. Our results further elucidate the cell biology implications of two rare diseases interacting.

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).

Evaluation of the safety and effectiveness of oral propranolol in patients with von Hippel-Lindau disease and retinal hemangioblastomas: phase III clinical trial

Background

von Hippel-Lindau disease (VHL) is a multisystem cancer syndrome caused by mutations in the VHL gene. Retinal hemangioblastoma is one of the most common tumours, and when it appears near the optic nerve, its treatment is challenging and risky. To date, no treatment has proven effective in changing the course of the disease. This study was designed to evaluate the safety and effectiveness of propranolol in controlling these tumours.

Methods

Seven patients were included. All patients took a daily dose of 120 mg of propranolol for 1 year. Clinical variables were assessed at baseline, and at 1, 3, 6, 9 and 12 months. The primary endpoint of the study was the number and size of retinal hemangioblastomas. On every visit, retinal outcomes and blood biomarkers (such as vascular endothelial growth factor (VEGF) and miR210) were analysed.

Results

Number and size of retinal hemangioblastomas remained stable in all patients. All of them had initially increased levels of VEGF and miR210. There was a gradual reabsorption of retinal exudation in two patients, correlating with a progressive decrease of both biomarkers. The only adverse effect reported was hypotension in one patient.

Conclusions

Propranolol could be used to treat retinal hemangioblastomas in VHL patients, although more studies are needed to determine the ideal dose and long-term effect. VEGF and miR210 should be explored as biomarkers of disease activity. As far as we know, these are the first biomarkers proposed to monitor the VHL disease activity.

Trial registration number

2014-003671-30.

Case Report: Propranolol increases the therapeutic response to temozolomide in a patient with metastatic paraganglioma

This case report presents the clinical evolution and management of a patient with a hereditary paraganglioma syndrome. This disease is characterized by rare tumors of neural crest origin that are symmetrically distributed along the paravertebral axis from the base of the skull and neck to the pelvis. In addition, these patients may develop renal cancer, gastrointestinal stromal tumors, pituitary adenomas, and bone metastasis in some cases. To date no successful therapeutic treatment has been reported. Total resection with postoperative radiotherapy and chemotherapy have been advocated, especially for the multiple metastasis. Here we show how the combination of high doses of the beta blocker propranolol (3 mg/Kg/day) and the DNA intercalating agent, temozolomide, has been successful in the treatment of a SDHA metastatic paraganglioma.

Repurposing propranolol as a drug for the treatment of retinal haemangioblastomas in von Hippel-Lindau disease

BACKGROUND

Von Hippel-Lindau (VHL) disease is a rare oncological disease with an incidence of 1:36,000, and is characterized by the growth of different types of tumours. Haemangioblastomas in the central nervous system (CNS) and retina, renal carcinoma and pheochromocytomas are the most common tumours. The absence of treatment for VHL leads to the need of repeated surgeries as the only option for these patients. Targeting VHL-derived tumours with drugs with reduced side effects is urgent to avoid repeated CNS surgeries. Recent reports have demonstrated that propranolol, a β-blocker used for the treatment of hypertension and other cardiac and neurological diseases, is the best option for infantile hemangioma (IH). Propranolol could be an efficient treatment to control haemangioblastoma growth in VHL disease given its antiangiogenic effects that were recently demonstrated by us. The main objective of the present study was the assessment of the efficacy and safety of propranolol on retinal haemangioblastoma in von Hippel-Lindau disease (VHL).

METHODS

7 VHL patients, from different regions of Spain, affected from juxtapapillary or peripheral haemangioblastomas were administered 120 mg propranolol daily. Patients were evaluated every 3 months for 12 months, at Virgen de la Salud Hospital (Toledo). The patients had juxtapapillary or peripheral haemangioblastomas but had refused standard treatments.

RESULTS

Propranolol was initiated with a progressive increase up to a final dose of 120 mg daily. All tumours remained stable, and no new tumours appeared. The reabsorption of retinal exudation was noted in the two patients having exudates. No adverse effects were recorded. VEGF and miRNA 210 levels were monitored in the plasma of patients as possible biomarkers of VHL. These levels decreased in all cases from the first month of treatment.

CONCLUSIONS

Although more studies are necessary, the results of this work suggest that propranolol is a drug to be considered in the treatment of VHL patients with retinal haemangioblastomas. VEGF and miRNA 210 could be used as biomarkers of the VHL disease activity.

TRIAL REGISTRATION

The study has a clinical trial design and was registered at EU Clinical Trials Register and Spanish Clinical Studies Registry, EudraCT Number: 2014-003671-30 . Registered 2 September 2014.

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.

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-β 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).

Propranolol reduces viability and induces apoptosis in hemangioblastoma cells from von Hippel-Lindau patients

BACKGROUND

Von Hippel-Lindau (VHL) disease is a rare oncological disease with an incidence of 1:36,000, and is characterized by the growth of different types of tumors: hemangioblastomas in the central nervous system (CNS) and retina, renal carcinoma, pheochromocytomas, pancreatic serous cystadenoma, and endolymphatic sac tumors. These tumors do not express VHL protein (pVHL). pVHL ubiquitinates hypoxia inducible factor (HIF) protein for degradation by the proteasome; in the absence of VHL, HIF translocates to the nucleus to activate the expression of its target genes. Targeting VHL-derived tumors with drugs that have reduced side effects is urgent to avoid repeat CNS surgeries. Recent reports have shown that propranolol, a β-blocker used for the treatment of hypertension and other cardiac and neurological diseases, is the best option for infantile hemangioma (IH). Propranolol could be an efficient treatment to control hemangioblastoma growth in VHL disease because of its antiangiogenic effects demonstrated in IH and the hypothetical impact on HIF levels.

METHODS

HeLa 9X (HRE) hypoxia responsive element cell line and primary hemangioblastoma-derived cells were subjected to propranolol treatment and cell viability and apoptosis were evaluated. HIF1-α and Hif-2α expression after propranolol treatment was analyzed by western blotting. Quantitative PCR was performed to study the mRNA expression of HIF target genes. Vascular endothelial growth factor (VEGF) was measured in culture supernatants by immunoassay.

RESULTS

Propranolol downregulated HIF-dependent transcription in HeLa 9XHRE cells. Under hypoxic conditions, propranolol decreased the expression of HIF target genes in hemangioblastoma cells, which stopped proliferating and died following long-term treatment. These results suggests that propranolol treatment promoted reduced HIF protein expression and corresponding downregulation of HIF target genes, and inhibited cell proliferation in parallel with induction of cell death by apoptosis.

CONCLUSIONS

Our results suggest that propranolol could reduce the growth of HIF-dependent tumors and may thus be a promising treatment to delay surgery in VHL patients.

Research on potential biomarkers in hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a genetically heterogeneous disorder, involving mutations in two predominant genes known as Endoglin (ENG; HHT1) and activin receptor-like kinase 1 (ACVRL1/ALK1; HHT2), as well as in some less frequent genes, such as MADH4/SMAD4 (JP-HHT) or BMP9/GDF2 (HHT5). The diagnosis of HHT patients currently remains at the clinical level, according to the “Curaçao criteria,” whereas the molecular diagnosis is used to confirm or rule out suspected HHT cases, especially when a well characterized index case is present in the family or in an isolated population. Unfortunately, many suspected patients do not present a clear HHT diagnosis or do not show pathogenic mutations in HHT genes, prompting the need to investigate additional biomarkers of the disease. Here, several HHT biomarkers and novel methodological approaches developed during the last years will be reviewed. On one hand, products detected in plasma or serum samples: soluble proteins (vascular endothelial growth factor, transforming growth factor β1, soluble endoglin, angiopoietin-2) and microRNA variants (miR-27a, miR-205, miR-210). On the other hand, differential HHT gene expression fingerprinting, next generation sequencing of a panel of genes involved in HHT, and infrared spectroscopy combined with artificial neural network patterns will also be reviewed. All these biomarkers might help to improve and refine HHT diagnosis by distinguishing from the non-HHT population.

Propranolol as antiangiogenic candidate for the therapy of hereditary haemorrhagic telangiectasia

The β-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-β1 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.

Immunosuppressor FK506 increases endoglin and activin receptor-like kinase 1 expression and modulates transforming growth factor-β1 signaling in endothelial cells

Hereditary hemorrhagic 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 in internal organs. Patients show severe epistaxis, and/or gastrointestinal bleeding, both of which notably interfere with their quality of life. There are two predominant types of HHT caused by mutations in endoglin (ENG) and ACVRL1/activin receptor-like kinase 1 (ALK1) genes, named HHT1 and HHT2, respectively. ENG and ALK1 code for proteins involved in the transforming growth factor (TGF)-β1 signaling pathway, and it is widely accepted that HHT pathogenicity results from haploinsufficiency. No cure for HHT has been found, so identification of drugs able to increase the expression of these genes is essential when proposing new therapies. We report the efficacy of tacrolimus (FK506) in increasing ENG and ALK1 expression. The rationale comes from a case report of a patient with HHT who received a liver transplantation after hepatic failure due to a liver arteriovenous malformation. The liver was transplanted, and the immunosuppressor FK506 was used to prevent the rejection. After the first month of FK506 treatment, the internal and external telangiectases, epistaxes, and anemia disappeared. Here, we find that the immunosuppressor FK506 increases the protein and mRNA expression of ENG and ALK1 in cultured endothelial cells and enhances the TGF-β1/ALK1 signaling pathway and endothelial cell functions like tubulogenesis and migration. These results suggest that the mechanism of action of FK506 involves a partial correction of endoglin and ALK1 haploinsufficiency and may therefore be an interesting drug for use in patients with HHT who undergo transplantation.

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.

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.