Carmelo Bernabeu

Background/Objectives: Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant vascular dysplasia characterized by recurrent epistaxis, anemia, and visceral arteriovenous malformations. Epistaxis is the most frequent and disabling manifestation, with limited effective pharmacological options. Propranolol, a non-selective beta-blocker with vasoconstrictive and antiangiogenic properties, has shown benefit in other vascular anomalies but remains scarcely studied in HHT. This study aimed to evaluate the effect of oral propranolol on nasal bleeding in patients with HHT. Methods: A retrospective observational study including 151 adults with HHT (44 treated with propranolol, 107 untreated) was conducted using data from an Institutional HHT Registry from a referral center. Baseline demographic and clinical variables were recorded. Outcomes at 6 months included changes in hemoglobin, adherence to nasal hygiene, use of bleeding-related therapies, and improvement in epistaxis frequency and intensity according to the Sadick–Bergler scale. Logistic regression models were adjusted for confounders and indication bias using inverse probability of treatment weighting (IPTW). Results: After IPTW adjustment, propranolol was significantly associated with reduced frequency of epistaxis (adjusted OR: 3.8; 95% CI: 1.3–11.2; p = 0.016), while no effect was observed on intensity. Hemoglobin levels increased modestly in both groups without a significant difference. Patients without propranolol showed greater antifibrinolytic use, whereas adherence to nasal care remained stable among treated patients. Conclusions: Oral propranolol reduced nasal bleeding frequency in HHT, even among patients with greater baseline severity. Given its accessibility, safety, and potential to lessen treatment burden, it may represent a valuable adjunct therapy. This study represents the largest cohort of HHT patients treated with propranolol reported to date. Randomized trials including standardized bleeding scores and patient-reported outcomes are warranted to confirm clinical and quality-of-life benefits.

Background/Objectives: Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant vascular dysplasia characterized by recurrent epistaxis, anemia, and visceral arteriovenous malformations. Epistaxis is the most frequent and disabling manifestation, with limited effective pharmacological options. Propranolol, a non-selective beta-blocker with vasoconstrictive and antiangiogenic properties, has shown benefit in other vascular anomalies but remains scarcely studied in HHT. This study aimed to evaluate the effect of oral propranolol on nasal bleeding in patients with HHT. Methods: A retrospective observational study including 151 adults with HHT (44 treated with propranolol, 107 untreated) was conducted using data from an Institutional HHT Registry from a referral center. Baseline demographic and clinical variables were recorded. Outcomes at 6 months included changes in hemoglobin, adherence to nasal hygiene, use of bleeding-related therapies, and improvement in epistaxis frequency and intensity according to the Sadick–Bergler scale. Logistic regression models were adjusted for confounders and indication bias using inverse probability of treatment weighting (IPTW). Results: After IPTW adjustment, propranolol was significantly associated with reduced frequency of epistaxis (adjusted OR 3.8; 95% CI 1.3-11.2; p = 0.016), while no effect was observed on intensity. Hemoglobin levels increased modestly in both groups without significant difference. Patients without propranolol showed greater antifibrinolytic use, whereas adherence to nasal care remained stable among treated patients. Conclusions: Oral propranolol reduced nasal bleeding frequency in HHT, even among patients with greater baseline severity. Given its accessibility, safety, and potential to lessen treatment burden, it may represent a valuable adjunct therapy. Randomized trials including standardized bleeding scores and patient-reported outcomes are warranted to confirm clinical and quality-of-life benefits.

Hereditary Hemorrhagic Telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a vascular disorder with a global prevalence ranging from 1:5000 to 1:8000. It most commonly manifests through nosebleeds, which can be frequent and severe, exposing patients to major iron losses, anemia, and considerable physical and emotional distress. To date, no drug has received the FDA or EMA approval for preventing or treating HHT associated epistaxis, limiting access to therapies and intensifying the burden on patients and clinicians. Based on peer-reviewed evidence, the Second International HHT Guidelines provided a stepwise approach to help physicians manage HHT-related epistaxis highlighting the role of anti-fibrinolytic and systemic antiangiogenic drugs. However, experience from clinical practice and trials indicates marked variability in patient responses, and none of the recommended approaches has demonstrated sufficient placebo-controlled efficacy to gain regulatory approval. Striking insights in HHT physiopathology shed light on complex dysregulated signaling pathways with a triggering role not only by angiogenesis as widely recognized, but also by inflammation, injury and other stimuli, pointing to novel therapeutic targets. This review outlines current recommendations for preventing and managing nosebleeds in HHT patients, highlights the latest insights into the development of telangiectasic lesions, and discusses potential therapeutic treatments currently under clinical investigation.

Most of the canonical Arg-Gly-Asp (RGD)-containing integrin ligands are extracellular matrix proteins, such as fibronectin, vitronectin and fibrinogen, which regulate cell-ECM adhesion processes. However, during the last years, several reports have demonstrated the existence of non-canonical RGD-containing integrin ligands that are cell surface transmembrane proteins. At variance with the canonical extracellular matrix integrin ligands, the RGD-containing cell surface integrin ligands are involved in cell–cell adhesion processes and function as “integrin counter-receptors”. We propose in this review grouping these transmembrane proteins, which include endoglin, cadherin-5, cadherin-6, cadherin-17, ADAM15, and L1CAM, under the newly coined acronym RGD-ICRs (RGD-containing Integrin Counter-Receptors). We present and discuss the structure of RGD-ICRs, their RGD-based interactions with integrins, the specific signaling pathways triggered in different cell types, as well as their pathophysiological involvement. It can be postulated that RGD-ICRs constitute an emerging group of non-canonical RGD-based integrin counter-receptors. In spite of being encoded by different and independent genes and involved in different pathophysiological processes, all of them appear to have undergone a strong evolutionary convergence in order to acquire the same functional capacity to bind integrins via the RGD motif. Importantly, these RGD-ICRs are also emerging as novel biomarkers and therapeutic targets, with promising clinical potential in a wide array of pathologies. Graphical Abstract

Increased levels of soluble endoglin (sEng) are found in serum, plasma, and urine of preeclampsia patients. sEng is released from membrane-bound endoglin through the proteolytic activity of metalloproteases, but its structural heterogeneity suggests the involvement of additional proteases. Considering the roles of thrombin and sEng in preeclampsia pathogenesis, we investigated whether thrombin cleaves endoglin. Sequence analysis revealed a conserved peptide in endoglin similar to the α-thrombin cleavage site of protease-activated receptor-1. Western blot analysis of plasma from preeclamptic women showed endoglin fragments consistent with thrombin-mediated cleavage. Incubation of purified endoglin with thrombin generated specific fragments, whose N- and C-terminal sequencing confirmed the predicted cleavage sites. Furthermore, thrombin treatment of endoglin-expressing cells released sEng and reduced cell surface endoglin. These findings suggest that multiple protease-targeted cleavage sites lead to the generation of sEng fragments, which may reflect endothelial dysfunction and preeclampsia progression.

The 2015 ACMG/AMP standards and guidelines for interpretation of sequence variants are widely used by laboratories, including for variant curation of the hereditary hemorrhagic telangiectasia (HHT) genes. However, the need for gene- and disease-specific modifications and specifications of these general guidelines to optimize and standardize variant classification was recognized at the time of publication. With this goal, the ClinGen HHT variant curation expert panel was formed. Here, we describe our recommended HHT-specific variant classification criteria and the outcomes from pilot testing of 30 variants of the ENG and ACVRL1 genes. Eight of the original ACMG/AMP rules were determined to not be applicable for ENG- or ACVRL1-related HHT or were previously recommended by ClinGen for removal, two rules were unmodified, and the remaining 18 rules were modified according to HHT specifications or previous ClinGen general recommendations. This study demonstrates the importance of HHT-specific criteria in the optimization and standardization of HHT variant classification and conflicting classification resolution.