BMP Receptor Inhibition Enhances Tissue Repair in Endoglin Heterozygous Mice.

Hereditary hemorrhagic telangiectasia type 1 (HHT1) is a severe vascular disorder caused by mutations in the TGFß/BMP co-receptor endoglin. Endoglin haploinsufficiency results in vascular malformations and impaired neoangiogenesis. Furthermore, HHT1 patients display an impaired immune response. To date it is not fully understood how endoglin haploinsufficient immune cells contribute to HHT1 pathology. Therefore, we investigated the immune response during tissue repair in Eng+/- mice, a model for HHT1. Eng+/- mice exhibited prolonged infiltration of macrophages after experimentally induced myocardial infarction. Moreover, there was an increased number of inflammatory M1-like macrophages (Ly6Chigh/CD206-) at the expense of reparative M2-like macrophages (Ly6Clow/CD206+). Interestingly, HHT1 patients also showed an increased number of inflammatory macrophages. In vitro analysis revealed that TGFß-induced differentiation of Eng+/- monocytes into M2-like macrophages was blunted. Inhibiting BMP signaling by treating monocytes with LDN-193189 normalized their differentiation. Finally, LDN treatment improved heart function after MI and enhanced vascularization in both wild type and Eng+/- mice. The beneficial effect of LDN was also observed in the hind limb ischemia model. While blood flow recovery was hampered in vehicle-treated animals, LDN treatment improved tissue perfusion recovery in Eng+/- mice. In conclusion, BMPR kinase inhibition restored HHT1 macrophage imbalance in vitro and improved tissue repair after ischemic injury in Eng+/- mice.

Immunological abnormalities associated with hereditary haemorrhagic telangiectasia.

OBJECTIVE: Hereditary haemorrhagic telangiectasia (HHT) is a genetic disorder related to mutations in one of the coreceptors to the transforming growth factor-ß superfamily (ALK1 or endoglin). Besides the obvious vascular symptoms (epistaxis and arteriovenous malformations), patients have an unexplained high risk of severe bacterial infections. The aim of the study was to assess the main immunological functions of patients with HHT using the standard biological tests for primary immunodeficiencies. DESIGN, SETTING AND SUBJECTS: A prospective single-centre study of 42 consecutive adult patients with an established diagnosis of HHT was conducted at the National French HHT Reference Center (Lyon). Lymphocyte subpopulations and proliferation capacity, immunoglobulin levels and neutrophil and monocyte phagocytosis, oxidative burst and chemotaxis were assessed. RESULTS: Innate immunity was not altered in patients with HHT. With regard to adaptive immunity, significant changes were seen in immunological parameters: primarily, a lymphopenia in patients with HHT compared with healthy control subjects affecting mean CD4 (642 cells µL(-1) vs. 832 cells µL(-1) , P < 0.001), CD8 (295 cells µL(-1) vs. 501 cells µL(-1) , P < 0.0001) and natural killer (NK) cells (169 cells µL(-1) vs. 221 cells µL(-1) , P < 0.01), associated with increased levels of immunoglobulins G and A. This lymphopenia mainly concerned naïve T cells. Proliferation capacities of lymphocytes were normal. Lymphopenic patients had a higher frequency of iron supplementation but no increase in infection rate. Lower levels of immunoglobulin M and a higher rate of pulmonary arteriovenous malformations were found amongst patients with a history of severe infection. CONCLUSIONS: Patients with HHT exhibit immunological abnormalities including T CD4, T CD8 and NK cell lymphopenia and increased levels of immunoglobulins G and A. The observed low level of immunoglobulin M requires further investigation to determine whether it is a specific risk factor for infection in HHT.

Loss-of-Function in SMAD4 Might Not Be Critical for Human Natural Killer Cell Responsiveness to TGF-ß.

We characterized the NK cell phenotype and function in three family members with Hereditary Hemorrhagic Telangiectasia (HHT) due to heterozygous SMAD4 mutations. Loss-of-function mutation in this gene did not induce developmental effects to alter CD56bright or CD56dim NK cell subset proportions in peripheral blood; and did not result in major differences in either their IL-15-induced proliferation, or their cytokine secretion response to TGF-ß1. These data suggest that SMAD4 plays a redundant role in downstream TGF-ß signaling in NK cells.

Bevacizumab for Epistaxis in Hereditary Hemorrhagic Telangiectasia: An Evidence-based Review.

Objective Epistaxis is a primary complaint in 90% to 96% of patients with hereditary hemorrhagic telangiectasia (HHT). Numerous surgical and medical treatments aim to decrease the frequency and severity of epistaxis in this patient population. Bevacizumab is a recombinant, humanized monoclonal antibody to vascular endothelial growth factor, an angiogenic factor elevated in HHT. It has been used in several forms to treat epistaxis in HHT but thus far, evidence-based recommendations are limited. Study Design Systematic review with evidence-based recommendations. Methods A systematic review of the literature following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed using Embase, MEDLINE, MEDLINE In-Process/Epub, and Cochrane databases. English language abstracts were reviewed for relevance. Results Eleven manuscripts met inclusion criteria and were analyzed. Submucosal injection, submucosal injection plus laser coagulation, intravenous (IV), and topical formulations of bevacizumab were evaluated for their therapeutic impact on epistaxis in patients with HHT. Three randomized controlled trials failed to show topical bevacizumab to be more effective in controlling epistaxis than saline or other moisturizers. Conclusions The use of submucosal and IV bevacizumab shows promise, but further study is necessary to determine the true efficacy in the treatment of epistaxis as only grade C level exists currently. Based on the available literature, the use of topical bevacizumab is not recommended (grade B).

Involvement of the transforming growth factor beta in the pathogenesis of hereditary hemorrhagic telangiectasia.

Hereditary hemorrhagic telangiectasia (HHT) is characterized by vessel alterations such as dilatation of postcapillary venules and arterio-venous communications, which account for the major clinical manifestations of the disease. Two types of HHT have been characterized HHT-1 and HHT-2, respectively, depending the former on endoglin mutations and the latter on activin receptor-like kinase 1 (ALK-1) mutations. Both endoglin and ALK-1 bind to the transforming growth factor (TGF) superfamily which, physiologically, regulates the activities of endothelial cells and also those related to the extracellular matrix. In this review, the salient features of TGF-beta will be outlined with special reference to its activity on the immune system and on tumorigenesis. Furthermore, the involvement of TGF-beta in the pathogenesis of some gastrointestinal diseases will be discussed and, in particular, in the course of liver disease, Helicobacter pylori infection and inflammatory bowel disease. In the light of these data and of animal model of HHT, the potential risk of developing other diseases in HHT patients will be discussed.

Ablation of T-helper 1 cell derived cytokines and of monocyte-derived tumor necrosis factor-alpha in hereditary hemorrhagic telangiectasia: immunological consequences and clinical considerations.

Experimental evidences on the adaptive immune response in patients with hereditary hemorragic telagiectasia (HHT) are lacking. Here, we report in 9 patients with HHT a multiple deficit involving the intracellular expression of T helper (h)1-derived cytokines [Interferon (IFN)-gamma, Interleukin (IL)-2 and Tumor Necrosis Factor (TNF)-alpha] and of monocyte-derived TNF-alpha. On the other hand, percentages of Th2-derived cytokines (IL-4, IL-5 and IL-10) were normal or, in some cases, above normality. Quite interestingly, monocyte-derived IL-10 was detectable in 5 out of 9 patients in a percentage of cells comparable to controls or exceeding normal levels. Taken together, these data point out, in HHT, an ablation of Th1-responses, while Th2-type cytokines are preserved, thus exerting either a suppressive effect on Th1-cells (via IL-4 and IL-10) or an antiinflammatory response on monocyte-derived TNF-alpha (via IL-10). Furthermore, monocyte-derived IL-10 may also contribute to the antiinflammatory activity seen in HHT. According to current literature even if patients with HHT do not exhibit certain diseases, such as autoimmune diseases, cancer and abnormal responses to pathogens, the observed immune deficits need to be diagnosed and therapeutically corrected.

Patients with Hereditary Hemorrhagic Telangectasia (HHT) exhibit a deficit of polymorphonuclear cell and monocyte oxidative burst and phagocytosis: a possible correlation with altered adaptive immune responsiveness in HHT.

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare genetic disease characterized by mutations occurring in the endoglin and ALK-1, two receptors of transforming growth factor-beta1. From a pathogenic point of view, a possible involvement of the immune system in HHT has been suggested since a mononuclear cell infiltrate was found around the area of telangiectases. Up until now, no information has been available about the role played by leukocytes in HHT and the mechanisms elicited by secretion of their mediators. However, the fact that a deficit of adaptive immunity in HHT has been reported in a companion paper in this issue will represent a great contribution to the understanding of HHT pathogenesis. The purpose of this study was to evaluate whether patients with HHT manifest also alterations in the innate immune response. Therefore, the phenotype of T, B and natural killer lymphocytes, serum immunoglobulin levels, phagocytosis and oxidative burst activity exerted by polymorphonuclear cells (PMN) and monocytes (MO) were analyzed in 22 patients. Twenty individuals demonstrated single or multiple deficits of PMN and MO functions, while the immunophenotype of lymphocytes and serum concentrations of immunoglobulins were normal. To the best of our knowledge, this is the first demonstration of a reduction in PMN and MO functions in HHT, thus suggesting a higher susceptibility to infectious complications in these patients. The relationship between innate immune deficits and T helper 1 and monocyte-derived cytokine dysfunction in HHT, as previously reported, is discussed.

A mouse model of hereditary hemorrhagic telangiectasia generated by transmammary-delivered immunoblocking of BMP9 and BMP10.

Hereditary hemorrhagic telangiectasia (HHT) is a potentially life-threatening genetic vascular disorder caused by loss-of-function mutations in the genes encoding activin receptor-like kinase 1 (ALK1), endoglin, Smad4, and bone morphogenetic protein 9 (BMP9). Injections of mouse neonates with BMP9/10 blocking antibodies lead to HHT-like vascular defects in the postnatal retinal angiogenesis model. Mothers and their newborns share the same immunity through the transfer of maternal antibodies during lactation. Here, we investigated whether the transmammary delivery route could improve the ease and consistency of administering anti-BMP9/10 antibodies in the postnatal retinal angiogenesis model. We found that anti-BMP9/10 antibodies, when intraperitoneally injected into lactating dams, are efficiently transferred into the blood circulation of lactationally-exposed neonatal pups. Strikingly, pups receiving anti-BMP9/10 antibodies via lactation displayed consistent and robust vascular pathology in the retina, which included hypervascularization and defects in arteriovenous specification, as well as the presence of multiple and massive arteriovenous malformations. Furthermore, RNA-Seq analyses of neonatal retinas identified an increase in the key pro-angiogenic factor, angiopoietin-2, as the most significant change in gene expression triggered by the transmammary delivery of anti-BMP9/10 antibodies. Transmammary-delivered BMP9/10 immunoblocking in the mouse neonatal retina is therefore a practical, noninvasive, reliable, and robust model of HHT vascular pathology.

Intravenous bevacizumab for complications of hereditary hemorrhagic telangiectasia: a review of the literature.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is a multisystem disease that is marked by mutations regulating vasculature formation. Epistaxis is the most commonly reported symptom, but gastrointestinal bleeding, anemia, hepatic issues, and pulmonary disease are also common. There is a growing body of evidence in the literature concerning using the monoclonal antibody against vascular endothelial growth factor (VEGF), bevacizumab, in patients with HHT. This treatment is gaining support for managing HHT because it directly inhibits the VEGF proteins that can be elevated as a result of the HHT mutations. We reviewed the current literature on the outcomes from intravenous bevacizumab treatment for HHT with a focus on epistaxis outcomes. METHODS: A systematic review of the literature was performed using Ovid MEDLINE, Scopus, and Cochrane databases. English citations, both national and international, were reviewed and filtered for relevance. RESULTS: Eighteen studies were included in this review. The majority of citations were case reports. All studies reported improvements. Specifically, 14 reported improvements in epistaxis, and 11 reported hemoglobin improvement following intravenous (IV) bevacizumab. Lack of uniformity in data presentation prevented a meta-analysis. CONCLUSION: This is the first systematic review analyzing the data involving HHT patients treated with bevacizumab. The results show that patients treated with bevacizumab have global improvements as well as specific improvements in hemoglobin levels. Although all of the studies reported improvements, there are several limitations, including inconsistencies in outcome reporting. A large, randomized, controlled study is needed to further investigate hemorrhage and epistaxis outcomes in HHT patients treated with intravenous bevacizumab.

Effects of dilution and prolonged storage with preservative in a polyethylene container on Bevacizumab (Avastin™) for topical delivery as a nasal spray in anti-hereditary hemorrhagic telangiectasia and related therapies.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular dysplasia and severe, recurrent epistaxis is a common clinical phenotype associated with HHT. An intranasal treatment regime of diluted Avastin™ (Bevacizumab; recombinant humanized anti-vascular epithelial growth factor immunoglobin G1) using apulsatile nasal irrigator has proven efficacious in clinical practice. However, concerns regarding the stability of Avastin™ following dilution and prolonged storage in standard containers used for drug delivery, such as polyethylene bottles, have so far prevented a more widespread clinical use. Compatibility with the preservative benzalkonium chloride was also unknown. OBJECTIVE: This study aimed at determining, whether dilution, prolonged refrigerated storage and the presence of the preservative benzalkonium chloride - as required for novel Avastin™ formulations - affected the biochemical and electrochemical properties of the drug. METHODS: We performed a detailed biochemical and electrochemical analysis of Avastin™, including native and sodium dodecyl sulfate polyacrylamide gel electrophoresis, enzyme-linked immunosorbent assay and isoelectric focusing. RESULTS: We did not detect any evidence of degeneration or aggregation following dilution and prolonged, refrigerated storage or from the presence of benzalkonium chloride. All biochemical and electrochemical properties of Avastin™ after dilution and prolonged, refrigerated storage were undistinguishable from control. CONCLUSIONS: Our data provide important insight into the stability of Avastin™ and allow the consideration of novel Avastin™ formulations, including its use in a metered-dose nasal spray for the treatment of HHT and other applications.

Hereditary haemorrhagic telangiectasia: a rare disease as a model for the study of human atherosclerosis.

Hereditary Haemorrhagic Telangiectasia (HHT) or Rendu-Osler-Weber syndrome is an autosomal dominant disease characterized by local angiodysplasia affecting different organism districts. From a clinical viewpoint, HHT patients suffer from epistaxis, mucocutaneous telangiectases and arteriovenous malformations in various organs. Mutations in two known genes (ENG and ALK1) account for the majority of HHT patients. Additional loci are predicted, but the underlying genes are still to be identified. Moreover, SMAD4 mutations have been reported to cause JP-HHT combined syndrome. Both endoglin and ALK-1 bind to various growth factors in the context of the Transforming Growth Factors (TGF)-beta superfamily and their expression is restricted to vascular endothelial cells and very few other cell types, such as activated monocytes. Endoglin and ALK1 mutations are thought to affect endothelial cell metabolism, angiogenesis and vascular remodelling, even if the precise mechanism leading to the HHT lesions is still obscure. Endoglin is also overexpressed in smooth muscle cells of atherosclerotic plaques, suggesting a role for this protein in atherogenesis and plaque progression, as well as in other cardiovascular diseases. Recently, we demonstrated that HHT adult patients display several deficits of both innate and adaptive immune system. Here, we investigated the function of immune cells in HHT pediatric patients. Our results clearly show that HHT children have a normal functionally immune system, and suggest that HHT patients become immunocompromised host during their lifetime, likely due to a precocious immunosenescence. Moreover, the relationship between immune responsiveness in HHT and atherosclerosis are discussed.

A new antibody specificity, anti-Rga, reacting with a red cell and serum antigen.

A new antibody specificity, anti-Rga, which detects an inherited antigen on red cells and in serum, reacts with 97% of individuals in the British population.

[Pulmonary arteriovenous fistula with Rendu-Osler-Weber disease and its HLA typing--a review and report of 87 cases of fistula].

Seven cases with pulmonary arteriovenous fistula (PAVF) in our hospital were reviewed on clinical data and HLA antigens. Furthermore, 80 reported cases of PAVF in Japan were summarized about the association with Rendu-Osler-Weber disease (Osler disease). Thirty-six (41%) of the total 87 cases had Osler disease. Fistulas were single in 46 cases and multiple in 41; unilateral in 56 and bilateral in 31. Operations were performed in 61 cases, embolizations in 8 and no therapy in 18. The frequency of the bilateral fistulas and multiple ones was significantly higher in cases with Osler disease (n = 36) than in those without Osler disease (n = 51) (p < 0.025). In our 7 cases, 6 had Osler disease. Aggregation of platelets was decreased in one case. Contralateral fistulas were recurred in another case 8 years after surgery. Three cases with Osler disease had the HLA halotype A26Bw6Bw61 which did not coincide with that in previous reports. We concluded that various HLA halotypes might exist in Osler disease.

Hereditary hemorrhagic telangiectasy (HHT) and HLA.

Linkage between HHT and 10 genetic marker systems was investigated in a family with 7 affected members. The analysis supports the previously suggested linkage between HLA and HHT (theta = .17).

[Differential diagnosis of Osler's telangiectasia and the CREST syndrome: significance of centromere antibodies]. / Zur Differentialdiagnose von Teleangiektasien bei M. Osler and CREST-Syndrom: Bedeutung von Zentromerantikörpern.

The case of a 75-year-old female patient with angiomas and telangiectasia of the face and fingers mimicking Osler's disease (telangiectasia hereditaria hemorrhagica) is reported, in whom the presence of anticentromere antibodies and additional clinical signs led to the final diagnosis of CREST syndrome.

Pseudothrombocytopenia: a cold autoantibody against platelet glycoprotein GP IIb.

Increased binding of IgM to donor platelets was detected in serum of a patient demonstrating the phenomenon of pseudothrombocytopenia. The elevated IgM binding was dependent on EDTA concentration and temperature, and could not be demonstrated when platelets of patients with Glanzmann's disease were used. Immunoblotting and crossed immunoelectrophoresis showed that the IgM antibody reacted with platelet glycoprotein GP IIb. Evidence is presented that the antigenic binding site on GP IIb is made accessible to the antibody by means of the effect of EDTA on the Ca2+ dependent GP IIb/IIIa complex.