Pregnant women show a low level of protein S (PS) in plasma,which is known to be a risk for deep venous thrombosis. 17␤-Estradiol (E 2 ), an estrogen that increases in concentration in the late stages of pregnancy, regulates the expression of various genes via the estrogen receptor (ER). Here, we investigated the molecular mechanisms behind the reduction in PS levels caused by E 2 in HepG2-ER␣ cells, which stably express ER␣, and also the genomic ER signaling pathway, which modulates the liganddependent repression of the PS␣ gene (PROS1). We observed that E 2 repressed the production of mRNA and antigen of PS. A luciferase reporter assay revealed that E 2 down-regulated PROS1 promoter activity and that this E 2 -dependent repression disappeared upon the deletion or mutation of two adjacent GCrich motifs in the promoter. An electrophoretic mobility shift assay and DNA pulldown assay revealed that the GC-rich motifs were associated with Sp1, Sp3, and ER␣. In a chromatin immunoprecipitation assay, we found ER␣-Sp protein-promoter interaction involved in the E 2 -dependent repression of PROS1 transcription. Furthermore, we demonstrated that E 2 treatment recruited RIP140 and the NCoR-SMRT-HDAC3 complex to the PROS1 promoter, which hypoacetylated chromatin. Taken together, this suggested that E 2 might repress PROS1 transcription depending upon ER␣-Sp1 recruiting transcriptional repressors in HepG2-ER␣ cells and, consequently, that high levels of E 2 leading to reduced levels of plasma PS would be a risk for deep venous thrombosis in pregnant women.

Type 2A von Willebrand disease (VWD) is characterized by decreased platelet-dependent function of von Willebrand factor (VWF); this in turn is associated with an absence of high-molecular-weight multimers. Sequence analysis of the VWF gene from two unrelated type 2A VWD patients showed an identical, novel, heterozygous T-->G transversion at nucleotide 4508, resulting in the substitution of L1503R in the VWF A2 domain. This substitution, which was not found in 60 unrelated normal individuals, was introduced into a full-length VWF cDNA and subsequently expressed in 293T cells. Only trace amount of the mutant VWF protein was secreted but most of the same was retained in 293T cells. Co-transfection experiment of both wild-type and mutant plasmids indicated the dominant-negative mechanism of disease development; as more of mutant DNA was transfected, VWF secretion was impaired in the media, whereas more of VWF was stored in the cell lysates. Molecular dynamic simulations of structural changes induced by L1503R indicated that the mean value of all-atom root-mean-squared-deviation was shifted from those with wild type or another mutation L1503Q that has been reported to be a group II mutation, which is susceptible to ADAMTS13 proteolysis. Protein instability of L1503R may be responsible for its intracellular retention and perhaps the larger VWF multimers, containing more mutant VWF subunits, are likely to be mal-processed and retained within the cell.

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Background: Type 3 von Willebrand disease (VWD) is characterized by a complete loss type of von Willebrand Factor (VWF) with the rarest disease frequency and hemorrhagic symptom is the most severe among other VWD types. The development of alloantibodies directed against VWF occurs in approximately 10% of patients with type 3 VWD. In this study, we found the VWF gene alterations and established blood outgrowth endothelial cells (BOECs) a from a Japanese type 3 VWD patient with an anti-VWF inhibitors. Case: A 5-year-old woman suffered from epistaxis, purpura and easy bruising and has been diagnosed as VWD. Her plasma level of FVIII:C was 1.8% and VWF:Ag and VWF:RCo was <5% and <10%, respectively. Her plasma lacked VWF multimers, indicating that she had type 3 VWD. To treat her frequent muco-cutaneous bleeding, purified plasma-derived FVIII/VWF concentrates were administrated followed by inhibitor development. After about 20ED of FVIII/VWF concentrates, an anaphylactic symptom comprised of cough, dyspnea, and wheezing developed at the time of dosing. An high titer inhibitory antibody against VWF was confirmed by a Bethesda assay based on a assay of VWF:RCo. Her younger sister also had type 3 VWD. Methods: Patients samples were collected after the written informed consent has bee obtained. We performed MLPA for genetic deletion or insertion. Then we amplified the all exons including the exon/intron boundaries of the VWF gene by PCR using allele-specific primers, and analyzed DNA sequences of the patient. Peripheral blood mononuclear cells were obtained from the patient and BOECs were then established. Briefly, buffy coat mononuclear cells were isolated and seeded onto a 6-well tissue culture plate precoated with type 1 rat tail collagen at 37°C, 5% CO2, in a humidified incubator. Medium was changed daily for 7 days and then every other day until the first passage. The endothelial identity of the BOECs was confirmed by flow cytometric and immunofluorescence analyses using endothelial markers with antibodies to CD31, VE-Cadherin (CD144) and VEGFR-2 (CD309). Results: The large deletion and insertion of VWF gene were not found. Direct sequencing showed the propositus and her sister were compound heterozygous for an E2341X (c.7021G>T) mutation in exon41 and a Y2631X (c.7892-7893insA) mutation in exon48. These were therefore two novel nonsense mutations and normal VWF polypeptides could not be translated. Flow cytometric analysis indicated that established BOECs expressed cell surface CD31 and CD309, whereas CD34 was not detected. By immunofluorescence analysis of fixed BOECs, VWF signal was remarkably reduced from the patient, in spite of normal VE-Cadherin expression. VWF specific ELISA was performed for both cell supernatant and lysates of patient’s BOECs but immunodetectable VWF was not secreted. Discussion: We identified two novel nonsense mutations causing type3 VWD. BOECs established from the patient reproduced the phenotype of the disease, suggesting that BOEC analysis is useful for studying the molecular pathogenesis of von Willebrand disease. Disclosures No relevant conflicts of interest to declare.

Background FVIIIa acts as a cofactor in the intrinsic pathway in which FIXa activates FX. ACE910 is a FIXa/FX-recognizing bispecific antibody that was designed to be a replacement for FVIIIa. Because of its nature, ACE910 is not affected by FVIII inhibitor. A clinical trial is now being conducted for the potential effect in the prophylactic treatment for bleeding hemophilia A patients. Here we present the perioperative care of a patient who had incidentally suffered from appendicitis and underwent an emergency surgery during the clinical trial. Methods Plasma ACE910 concentration and FXIa-triggered thrombin generation assay (TGA) was obtained in the central measurement of the trial. An activated partial thromboplastin time (APTT), and the tissue factor (TF)-triggered TGA were conducted at our laboratory. TF-triggered TGA was performed by means of calibrated automated thrombogram (Thrombinoscope BV), in accordance with the manufacturer's instructions. We used PPP-reagent LOWTM and FluCa-KitTM in Fluoroscan Ascent FLTM (Thermo Fisher Scientific Inc.) and monitored the thrombin generation for 2 hours, set at an excitation wavelength of 390 nm and an emission wavelength of 460 nm, and ThrombinoscopeTM software (Thrombinoscope BV). ROTEM® was performed as manufactured (Tem Innovations GmbH). Case The patient is a 60-year-old man suffering from hemophilia A without inhibitors and had severe hemophilic arthropathy in the number of target joints. Even after biweekly prophylaxis had been introduced by 2000 units of rFVIII concentrates, the annualized bleeding rate remained to be 10.1 In November 2013, ACE910 was introduced by way of subcutaneous administration and the initial dose was 3 mg/kg, followed by weekly administration of 1 mg/kg. After that, he had not had any of joint or soft tissue bleeding. In the 63rd week after the initial administration, he had severe abdominal pain and diagnosed as acute appendicitis that required emergency surgery. His APTT was consistently normal since ACE910 administration, we selected to undergo the surgery without any additional FVIII replacement, although his previous product was set up to be administrated any time on demand. ACE910 had been administered as scheduled earlier on the day of the diagnosis of acute appendicitis, followed by the emergency appendectomy. Results The appendectomy was performed by pararectal incision. Although the patient's appendix was necrosed and perforated, it was easy to stop bleeding during surgery and the total amount of bleeding was only 45 mL. On postoperative day 11, a small amount of bleeding was found after the removal of drainage catheter placed subfascially, however, the bleeding stopped immediately after the bleeding site was sutured. No other issues on bleeding were found. Trough levels of plasma ACE910 concentration were maintained at 27-41 µg/mL during the period between the 12th week after the initiation of ACE910 and the time of preoperative stage. In FXIa-triggered TGA, lag time was remarkably improved after the initiation of ACE910 and remained stable throughout the course of emergency surgery (Table 1). Although peak thrombin levels were slightly decreased a week after surgery, APTT and several In-TEM values by ROTEM® remained at almost normal levels (Table 2). Discussion and Conclusion We successfully conducted the hemostatic management for appendicitis in the perioperative period without any additional administration of FVIII concentrate. The patient showed less bleeding under ACE910 prophylaxis. To date there are little information on appropriate use of FVIII concentrate in patients with acute bleeding or major surgery who are under ACE910 prophylaxis. Generally in bleeding hemophilic patients with major surgery, the loss of clotting factors due to hemodilution by fluid replacement should also be carefully monitored. In such condition, the optimum ACE910 concentration could not be well interpreted, however, the careful monitoring might be required especially in highly invasive surgeries. In our experience, TF-triggered TGA demonstrated a marginal change only between postoperative days 7 and 13, although it is not totally known whether these changes were affected by ACE910 pharmacodynamics. Further researches are needed to explore the suitable biomarkers to indicate hemostasis of hemophilic patients under the administration of ACE910. Disclosures Suzuki: Baxalta: Honoraria; Bayer Healthcare: Honoraria; Novo Nordisk Pharma: Honoraria. Kiyoi:Novartis Pharma K.K.: Research Funding; MSD K.K.: Research Funding; Pfizer Inc.: Research Funding; Takeda Pharmaceutical Co., Ltd.: Research Funding; Yakult Honsha Co.,Ltd.: Research Funding; Alexion Pharmaceuticals: Research Funding; Teijin Ltd.: Research Funding; Taisho Toyama Pharmaceutical Co., Ltd.: Research Funding; Eisai Co., Ltd.: Research Funding; Astellas Pharma Inc.: Consultancy, Research Funding; Japan Blood Products Organization: Research Funding; Nippon Shinyaku Co., Ltd.: Research Funding; FUJIFILM RI Pharma Co.,Ltd.: Research Funding; Nippon Boehringer Ingelheim Co., Ltd.: Research Funding; FUJIFILM Corporation: Patents & Royalties, Research Funding; Zenyaku Kogyo Co., Ltd.: Research Funding; Sumitomo Dainippon Pharma Co., Ltd.: Research Funding; Kyowa Hakko Kirin Co., Ltd.: Consultancy, Research Funding; Bristol-Myers Squibb: Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding; Mochida Pharmaceutical Co., Ltd.: Research Funding. Kasai:Chugai Pharmaceutical Co., Ltd.: Employment. Matsushita:Asahi Kasei Pharma: Honoraria, Research Funding, Speakers Bureau; Sysmex: Speakers Bureau; Octapharma AG: Honoraria; Kyowa-Kirin: Honoraria, Research Funding; CLS-Behling: Research Funding; Biogen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bayer Healthcare: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Seamens: Speakers Bureau; Nihon Pharmaceutical: Honoraria, Research Funding, Speakers Bureau; Kaketsuken: Honoraria, Research Funding, Speakers Bureau; Eisai: Research Funding; Baxalta: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Japan Blood Products Organization: Honoraria, Research Funding; Novartis Pharma: Honoraria, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novo Nordisk Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Chugai Pharmaceutical Co., Ltd.: Research Funding.

Von Willebrand factor (VWF) is synthesized in megakaryocytes and endothelial cells (ECs) and has two main roles: to carry and protect coagulation factor VIII (FVIII) from degradation by forming VWF-FVIII complex; and to mediate platelet adhesion and aggregation at sites of vascular injury. Previous research using the HEK293 cell line revealed that the VWF K1362 mutation interacted directly with platelet glycoprotein Ib (GPIb). Vwf K1362A knock-in (KI) mice were therefore generated to verify the in vivo function of residue 1362 in binding to platelet GPIb. The Cre-loxP system was employed to introduce the Vwf K1362A mutation systemically in mice. In blood coagulation analysis, the VWF antigen (VWF:Ag) of Lys1362Ala KI homozygous (homo) mice was below the sensitivity of detection by enzyme-linked immunosorbent assay. FVIII activities (FVIII:C) were 47.9 ± 0.3 and 3.3 ± 0.3% (K1362A heterozygous (hetero) and K1362A KI homo mice, respectively) compared to wild-type mice. Immunohistochemical staining analysis revealed that VWF protein did not exist in ECs of K1362A KI homo mice. These results indicated that VWF protein synthesis of K1362A was impaired after transcription in mice. K1362 seems to represent a very important position not only for VWF function, but also for VWF synthesis in mice.

Background Von Willebrand factor (VWF) is a multimeric glycoprotein that plays important roles in hemostasis and thrombosis. C‐terminal interchain‐disulfide bonds in the cystine knot (CK) domain are essential for VWF dimerization. Previous studies have reported that missense variants of cysteine in the CK domain disrupt the intrachain‐disulfide bond and cause type 3 von Willebrand disease (VWD). However, type 3 VWD‐associated noncysteine substitution variants in the CK domain have not been reported. Objective To investigate the molecular mechanism of a novel non‐cysteine variant in the CK domain, VWF c.8254 G>A (p.Gly2752Ser), which was identified in a patient with type 3 VWD as homozygous. Methods Genetic analysis was performed by whole exome sequencing and Sanger sequencing. VWF multimer analysis was performed using SDS‐agarose electrophoresis. VWF production and subcellular localization were analyzed using ex vivo endothelial colony forming cells (ECFCs) and an in vitro recombinant VWF (rVWF) expression system. Results The patient was homozygous for VWF‐Gly2752Ser. Plasma VWF enzyme‐linked immunosorbent assay showed that the VWF antigen level of the patient was 1.2% compared with healthy subjects. A tiny amount of VWF was identified in the patient's ECFC. Multimer analysis revealed that the circulating VWF‐Gly2752Ser presented only low molecular weight multimers. Subcellular localization analysis of VWF‐Gly2752Ser‐transfected cell lines showed that rVWF‐Gly2752Ser was severely impaired in its ER‐to‐Golgi trafficking. Conclusion VWF‐Gly2752Ser causes severe secretory impairment because of its dimerization failure. This is the first report of a VWF variant with a noncysteine substitution in the CK domain that causes type 3 VWD.

Background: Von Willebrand disease (VWD) is the most common inherited bleeding disorder characterized by quantitative and/or qualitative von Willebrand factor (VWF) abnormalities. VWF gene is a large gene consists of 52 exons, wheras its pseudogene corresponds to exons 23-34 that makes the analysis much complicated. In this study, we performed genetic analyses of the VWF gene from 20 Japanese VWD patients, aimed to find the causative genetic mutations by using various techniques including the exome sequencing approach, and to explore the diversity of yet unknown VWD pathogenetic mechanisms. Methods: Patients' samples were collected after the written informed consent has been obtained. First, we analyzed exon 28 of VWF genes from peripheral blood genomic DNA of the patients by PCR using allele-specific primers, and analyzed DNA sequences of the patients by Sanger sequencing method. If patients show the type 3 phenotype, the possibility of deletion or insertion of the gene was taken into consideration, then MLPA method was selected. In cases the gene mutation was not detected by exon 28 sequencing or MLPA, we analyzed all exons of VWF by Sanger method. In selected patients, the exome sequencing was employed by using the next-generation sequencer Hi-Seq 2500 (Illumina) and exomes were captured using SureSelect XT Human All Exon V5+UTRs kit (Agilent Technologies). Results: Twenty VWD cases were studied. As a result of the VWF exon 28 sequencing, we identified causative gene mutation in 12 cases (10 cases were type 2, 2 cases were type 1). Gene mutations found in exon 28 were p.R1308C, p.R1315C, p.V1316M, p.R1334W, p.A1461D, p.L1503R, p.S1506L, p.R1597Q, p.G1609R. In one case and her sister of type 3, MLPA could not detect the large deletions or insertions. Sanger sequencing showed the they were compound heterozygous for an p.E2341X (c.7021G>T) mutation in exon 41 and a p.Y2631X (c.7892-7893insA) mutation in exon 48. In another case of type 3, we used exome sequencing and found a novel homozygous gene mutation p.G2752S (c.8254G>A) in exon 52. The mutation was confirmed by Sanger sequencing and the propositus was homozygote for the mutation, while the parents and two sons had the same mutation in the heterozygote. In the multimer analysis of plasma, multimers larger than the dimer in size were hardly visible, but there was a faint monomer band was present in the plasma. Multimeric patterns of his family were normal. Discussion: We analyzed the VWF genes of 20 VWD cases and identified causative gene mutations in 14 cases including three novel mutations (p.E2341X, p.Y2631X, p.G2752S). We previously demonstrated BOECs established from the type 3 patient (p.E2341X and p.Y2631X) reproduced the phenotype of the disease (ASH 2014). Meanwhile, G2752S mutation is located in CTCK domain, therefore possibly it affects the VWF dimer formation. However, the causative gene mutations were not detected in 6 cases (5 cases were type 1, 1 case was type 2) by exome sequencing. Although previous observations have pointed out that causative VWF gene mutations are not detectable in about 30 % of entire type 1 cases, a newer approach would be needed to elucidate molecular pathogenesis of VWD. Disclosures Suzuki: Baxalta: Honoraria; Novo Nordisk Pharma: Honoraria; Bayer Healthcare: Honoraria. Matsushita:Biogen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Baxalta: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bayer Healthcare: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Asahi Kasei Pharma: Honoraria, Research Funding, Speakers Bureau; Kaketsuken: Honoraria, Research Funding, Speakers Bureau; Seamens: Speakers Bureau; Japan Blood Products Organization: Honoraria, Research Funding; Kyowa-Kirin: Honoraria, Research Funding; Novartis Pharma: Honoraria, Speakers Bureau; Sysmex: Speakers Bureau; Chugai Pharmaceutical Co., Ltd.: Research Funding; Novo Nordisk Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Eisai: Research Funding; Nihon Pharmaceutical: Honoraria, Research Funding, Speakers Bureau; Octapharma AG: Honoraria; CLS-Behling: Research Funding.