Background: We aimed to describe risk factors for gastrointestinal (GI) bleeding and endoscopic findings in patients with hereditary hemorrhagic telangiectasia (HHT). Methods: This is a prospective study from a referral HHT unit. Endoscopic tests were performed when there was suspicion of GI bleeding, and patients were divided as follows: with, without, and with unsuspected GI involvement. Results: 67 (27.9%) patients with, 28 (11.7%) patients without, and 145 (60.4%) with unsuspected GI involvement were included. Age, tobacco use, endoglin (ENG) mutation, and hemoglobin were associated with GI involvement. Telangiectases were mostly in the stomach and duodenum, but 18.5% of patients with normal esophagogastroduodenoscopy (EGD) had GI involvement in video capsule endoscopy (VCE). Telangiectases ≤ 3 mm and ≤10 per location were most common. Among patients with GI disease, those with hemoglobin < 8 g/dL or transfusion requirements (65.7%) were older and had higher epistaxis severity score (ESS) and larger telangiectases (>3 mm). After a mean follow-up of 34.2 months, patients with GI involvement required more transfusions and more emergency department and hospital admissions, with no differences in mortality. Conclusions: Risk factors for GI involvement have been identified. Patients with GI involvement and severe anemia had larger telangiectases and higher ESS. VCE should be considered in patients with suspicion of GI bleeding, even if EGD is normal.

BACKGROUND: Distinct endothelial cell cycle states (early G1 versus late G1) provide different “windows of opportunity” to enable the differential expression of genes that regulate venous versus arterial specification, respectively. Endothelial cell cycle control and arteriovenous identities are disrupted in vascular malformations including arteriovenous shunts, the hallmark of hereditary hemorrhagic telangiectasia (HHT). To date, the mechanistic link between endothelial cell cycle regulation and the development of arteriovenous malformations (AVMs) in HHT is not known. METHODS: We used BMP (bone morphogenetic protein) 9/10 blocking antibodies and endothelial-specific deletion of activin A receptor like type 1 ( Alk1 ) to induce HHT in Fucci (fluorescent ubiquitination-based cell cycle indicator) 2 mice to assess endothelial cell cycle states in AVMs. We also assessed the therapeutic potential of inducing endothelial cell cycle G1 state in HHT to prevent AVMs by repurposing the Food and Drug Administration–approved CDK (cyclin-dependent kinase) 4/6 inhibitor (CDK4/6i) palbociclib. RESULTS: We found that endothelial cell cycle state and associated gene expressions are dysregulated during the pathogenesis of vascular malformations in HHT. We also showed that palbociclib treatment prevented AVM development induced by BMP9/10 inhibition and Alk1 genetic deletion. Mechanistically, endothelial cell late G1 state induced by palbociclib modulates the expression of genes regulating arteriovenous identity, endothelial cell migration, metabolism, and VEGF-A (vascular endothelial growth factor A) and BMP9 signaling that collectively contribute to the prevention of vascular malformations. CONCLUSIONS: This study provides new insights into molecular mechanisms leading to HHT by defining how endothelial cell cycle is dysregulated in AVMs because of BMP9/10 and Alk1 signaling deficiencies, and how restoration of endothelial cell cycle control may be used to treat AVMs in patients with HHT.

Hereditary hemorrhagic telangiectasia (HHT) is a rare vascular disease inherited in an autosomal dominant manner. Disease-causing variants in endoglin (ENG) and activin A receptor type II-like 1 (ACVRL1) genes are detected in around 90% of the patients; also 2% of patients harbor pathogenic variants at SMAD4 and GDF2. Importantly, the genetic cause of 8% of patients with clinical HHT remains unknown. Here, we present new putative genetic drivers of HHT. To identify new HHT genetic drivers, we performed exome sequencing of 19 HHT patients and relatives with unknown HHT genetic etiology. We applied a multistep filtration strategy to catalog deleterious variants and prioritize gene candidates based on their known relevance in endothelial cell biology. Additionally, we performed in vitro validation of one of the identified variants. We identified variants in the INHA, HIF1A, JAK2, DNM2, POSTN, ANGPTL4, FOXO1 and SMAD6 genes as putative drivers in HHT. We have identified the SMAD6 p.(Glu407Lys) variant in one of the families; this is a loss-of-function variant leading to the activation of the BMP/TGFβ signaling in endothelial cells. Variants in these genes should be considered for genetic testing in patients with HHT phenotype and negative for ACVRL1/ENG mutations.

Adrenomedullin (AM) is a vasoactive peptide mostly secreted by endothelial cells with an important role in preserving endothelial integrity. The relationship between AM and hereditary hemorrhagic telangiectasia (HHT) is unknown. We aimed to compare the serum levels and tissue expression of AM between HHT patients and controls. Serum AM levels were measured by radioimmunoassay and compared between control and HHT groups. AM levels were also compared among HHT subgroups according to clinical characteristics. The single nucleotide polymorphism (SNP) rs4910118 was assessed by restriction analysis and sequencing. AM immunohistochemistry was performed on biopsies of cutaneous telangiectasia from eight HHT patients and on the healthy skin from five patients in the control group. Forty-five HHT patients and 50 healthy controls were included, mean age (SD) was 50.7 (14.9) years and 46.4 (9.9) years (p = 0.102), respectively. HHT patients were mostly female (60% vs 38%, p = 0.032). Median [Q1-Q3] serum AM levels were 68.3 [58.1-80.6] pg/mL in the HHT group and 47.7 [43.2-53.8] pg/mL in controls (p<0.001), with an optimal AM cut-off according to Youden's J statistic of 55.32 pg/mL (J:0.729). Serum AM levels were similar in the HHT subgroups. No patient with HHT had the SNP rs4910118. AM immunoreactivity was found with high intensity in the abnormal blood vessels of HHT biopsies. We detected higher AM serum levels and tissue expression in patients with HHT than in healthy controls. The role of AM in HHT, and whether AM may constitute a novel biomarker and therapeutic target, needs further investigation.

The aim was to describe three patients with hemorrhagic hereditary telangiectasia (HHT) requiring liver transplantation (LT) and to perform a systematic review focusing on surgical complications and long-term follow-up. Unrestricted searches of the Medline and Embase databases were performed through February 2022. Forty-five studies were selected including 80 patients plus the three new reported patients, 68 (81.9%) were female and mean age was 50 (27–72) years. Main indications for LT were high-output cardiac failure (n = 40; 48.2%), ischemic cholangitis (n = 19; 22.9%), and a combination of both conditions (n = 13;15.6%). Mean cold ischemic time and red blood cell units transfused during LT were 554 (300–941) minutes and 11.4 (0–88) units, respectively. Complications within 30 days were described in 28 (33.7%) patients, mainly bleeding complications in 13 patients, hepatic artery (HA) thrombosis in four and hepatic vein thrombosis in one. Mean follow-up was 76.4 (1–288) months, and during it, four new patients developed thrombotic complications in HA, HA aneurysm, celiac artery, and the portal–splenic–mesenteric vein. HHT relapse in the transplant allograft was detected in 13 (17.1%) patients after 1–19 years (including two fatal recurrences). Overall mortality was 12%. In conclusion, previous assessment of HA anatomy and hyperdynamic circulatory state could reduce LT complications. The risk of relapse in the hepatic graft supports a multidisciplinary follow-up for HHT patients with LT.

Herein, we present the first described hereditary hemorrhagic telangiectasia (HHT) patient treated with aflibercept for severe GI involvement after tachyphylaxis to bevacizumab, with promising results. HHT is a rare genetic disease characterized by systemic vascular malformations. Gastrointestinal telangiectasia is one of the major involvements that can produce chronic severe iron-deficiency anemia. Nowadays, support treatment with iron replacement therapy, red blood cell transfusions, and antiangiogenic drugs—mainly bevacizumab, a monoclonal antibody against vascular endothelial growth factor (VEGF)—are the main therapeutic options for this complication. The evidence of alternative drugs in patients with failure to this approach, such as tachyphylaxis to bevacizumab, is scarce. Aflibercept is a VEGF inhibitor with antiangiogenic properties approved for the treatment of different types of cancer and ocular neovascularization diseases.