Oestrogen increases haematopoietic stem-cell self-renewal in females and during pregnancy.

Sexually dimorphic mammalian tissues, including sexual organs and the brain, contain stem cells that are directly or indirectly regulated by sex hormones. An important question is whether stem cells also exhibit sex differences in physiological function and hormonal regulation in tissues that do not show sex-specific morphological differences. The terminal differentiation and function of some haematopoietic cells are regulated by sex hormones, but haematopoietic stem-cell function is thought to be similar in both sexes. Here we show that mouse haematopoietic stem cells exhibit sex differences in cell-cycle regulation by oestrogen. Haematopoietic stem cells in female mice divide significantly more frequently than in male mice. This difference depends on the ovaries but not the testes. Administration of oestradiol, a hormone produced mainly in the ovaries, increased haematopoietic stem-cell division in males and females. Oestrogen levels increased during pregnancy, increasing haematopoietic stem-cell division, haematopoietic stem-cell frequency, cellularity, and erythropoiesis in the spleen. Haematopoietic stem cells expressed high levels of oestrogen receptor-α (ERα). Conditional deletion of ERα from haematopoietic stem cells reduced haematopoietic stem-cell division in female, but not male, mice and attenuated the increases in haematopoietic stem-cell division, haematopoietic stem-cell frequency, and erythropoiesis during pregnancy. Oestrogen/ERα signalling promotes haematopoietic stem-cell self-renewal, expanding splenic haematopoietic stem cells and erythropoiesis during pregnancy.

Clinical Risk Factors of Thromboembolic and Major Bleeding Events for Patients with Atrial Fibrillation Treated with Rivaroxaban in Japan.

BACKGROUND: It is important to understand the risk of thromboembolism and bleeding in patients with nonvalvular atrial fibrillation (NVAF) receiving direct oral anticoagulants; however, data on risk factors in Japanese patients are limited. METHODS: XAPASS (Xarelto Post-Authorization Safety and Effectiveness Study in Japanese Patients with Atrial Fibrillation) is a prospective observational study examining the safety and effectiveness of rivaroxaban in Japanese real-world clinical practice. We investigated risk factors for stroke/noncentral nervous system systemic embolism (non-CNS SE)/myocardial infarction (MI) and major bleeding using 1-year follow-up data. Associations between baseline characteristics and outcomes were examined by Cox regression analysis. RESULTS: During April 2012-June 2014, 11,308 patients newly started with rivaroxaban treatment were enrolled. Of 9578 patients with 1-year data fixed as of September 2017, 6220 patients who received appropriate dosages of rivaroxaban for their creatinine clearance were included in the present safety outcomes subanalysis, and 6198 were included in the effectiveness outcomes analysis. Stroke/non-CNS SE/MI was observed in 97 of 6198 patients (1.6%, 1.8 events/100 patient-years), and major bleeding occurred in 102 of 6220 patients (1.6%, 1.9 events/100 patient-years). Age greater than or equal to 75 years (hazard ratio [HR]: 2.27; [95% confidence interval (CI): 1.49, 3.47]), prior ischemic stroke/transient ischemic attack (2.08; [1.38, 3.13]), and antiplatelet use (3.23; [1.83, 5.70]) were associated with stroke/non-CNS SE/MI. Creatinine clearance less than 50 mL/min (HR: 1.86; [95% CI: 1.26, 2.75]), diabetes (1.55; [1.02, 2.35]), and antiplatelet use (3.04; [1.70, 5.45]) were associated with major bleeding. CONCLUSIONS: These results would help physicians to assess risks in Japanese patients with NVAF receiving rivaroxaban.

Real-World Outcomes of Rivaroxaban Treatment in Patients with Both Nonvalvular Atrial Fibrillation and a History of Ischemic Stroke/Transient Ischemic Attack.

INTRODUCTION: Prior stroke is a risk factor for stroke and bleeding during anticoagulation in patients with atrial fibrillation (AF). Although rivaroxaban is widely prescribed to reduce their risk of stroke in patients with nonvalvular AF (NVAF), the real-world evidence on rivaroxaban treatment is limited. We aimed to examine the outcomes of rivaroxaban treatment in NVAF patients with prior ischemic stroke/transient ischemic attack (TIA) by using the data of the Xarelto Post-Authorization Safety and Effectiveness Study in Japanese -Patients with AF, a prospective, single-arm, observational study. METHODS: The clinical outcomes of 9,578 patients who completed the 1-year follow-up were evaluated. Safety and effectiveness outcomes were compared between patients with and without prior ischemic stroke/TIA. RESULTS: Among the patients, 2,153 (22.5%) had prior ischemic stroke/TIA. They were significantly older and had lower body weight, lower creatinine clearance, higher CHADS2, CHA2DS2-VASc, and modified HAS-BLED scores as compared to those without prior ischemic stroke/TIA. Any bleeding (9.1 vs. 7.2 events per 100 patient-years), major bleeding (2.3 vs. 1.6 events per 100 patient-years), and stroke/non-central nervous system systemic embolism/myocardial infarction (3.4 vs. 1.3 events per 100 patient-years) were more frequent in patients with prior ischemic stroke/TIA. Stepwise regression analysis suggested that body weight of ≤50 kg and diabetes mellitus were predictive of major bleeding in patients with prior ischemic stroke/TIA. CONCLUSIONS: Safety and effectiveness event rates were higher in patients with prior ischemic stroke/TIA than those without. This might be explained by differences in several risk profiles including age, body weight, renal function, and risk scores such as CHADS2 between the groups. Clinicaltrials.gov: NCT01582737.

Vericiguat Use in Patients with Heart Failure in Real-World Settings during the First Year after the Drug Authorization in Japan.

Background: Vericiguat was developed to treat patients with heart failure (HF). Currently, limited data are available to characterize vericiguat-treated patients in real-world clinical settings. Methods: This retrospective cohort study was done using a Japanese hospital administrative database to describe the use of vericiguat in patients with HF in real-world settings. Adult patients diagnosed with HF prescribed vericiguat between 1 July 2021 and 30 September 2022 were included. Patient characteristics at the initiation of vericiguat treatment, patterns of HF medication use, and vericiguat dose titrations were assessed within the first 90 days of treatment. Results: The study included 829 patients who were initiated on vericiguat therapy. The mean age was 75.5 years and 69.0% were male. Hypertension, coronary artery disease, and diabetes mellitus were present in 91.7, 71.3, and 60.1% of patients, respectively. Most patients had previously received HF medications, with high percentages using angiotensin-receptor blocker neprilysin inhibitors (ARNI; 43.9%) and sodium-glucose cotransporter-2 inhibitors (54.4%). During the first 90 days of vericiguat treatment, 65.8% of the patients were uptitrated from their starting dose, and 32.3% had reached the maximal daily dose. The median time to reach the maximal daily dose was 34 days. The multivariable model identified that initiating vericiguat treatment in an outpatient setting and using ARNI before initiating vericiguat treatment were factors significantly associated with reaching the maximal daily dose of vericiguat at any given time, whereas older age, chronic kidney disease, hyperkalemia, and anemia were not associated. Conclusions: These findings provide early insights into the use of vericiguat, which aid in optimizing the combinations and/or sequences of HF treatment incorporating vericiguat therapy.

Initiation and continuation of pharmacological therapies in patients hospitalized for heart failure in Japan.

Currently, the utilization patterns of medications for heart failure (HF) after worsening HF events remain unelucidated in Japan. Here, we conducted a retrospective cohort study evaluating the changes in HF drug utilization patterns in 6 months before and after hospitalizations for HF. The adherence to newly initiated HF medications was evaluated based on the proportion of days covered (PDC) and persistence as continuous treatment episodes among new users. The study included 9091 patients hospitalized for HF between January 2016 and September 2019, including 2735 (30.1%) patients who were newly prescribed at least one HF medication after hospitalization. Despite increases in the use of foundational HF therapy (beta-blockers, angiotensin-converting-enzyme inhibitors/angiotensin receptor blockers, or mineralocorticoid receptor antagonists), 35.6% and 7.6% of patients were treated with the HF foundational monotherapy or diuretics alone after hospitalization, respectively. The mean PDC of newly initiated HF medications ranged from 0.57 for thiazide diuretics to 0.77 for sodium-glucose cotransporter-2 inhibitors. Continuous use of HF medications during the first year after initiation was observed in 30-60% of patients. The mean PDC and one-year continuous HF medication use were consistently lower in patients aged ≥ 75 years and in patients with a history of HF hospitalization for all HF medication classes except for tolvaptan and digoxin. Despite the guideline recommendations of HF pharmacotherapy, both treatment and adherence were suboptimal after HF hospitalization, especially in vulnerable populations such as older patients and those with prior HF hospitalizations.

Polydom/SVEP1 is a ligand for integrin α9ß1.

A variety of proteins, including tenascin-C and osteopontin, have been identified as ligands for integrin α9ß1. However, their affinities for integrin α9ß1 are apparently much lower than those of other integrins (e.g. α3ß1, α5ß1, and α8ß1) for their specific ligands, leaving the possibility that physiological ligands for integrin α9ß1 still remain unidentified. In this study, we found that polydom (also named SVEP1) mediates cell adhesion in an integrin α9ß1-dependent manner and binds directly to recombinant integrin α9ß1 with an affinity that far exceeds those of the known ligands. Using a series of recombinant polydom proteins with N-terminal deletions, we mapped the integrin-binding site to the 21st complement control protein domain. Alanine-scanning mutagenesis revealed that the EDDMMEVPY sequence (amino acids 2636-2644) in the 21st complement control protein domain was involved in the binding to integrin α9ß1 and that Glu(2641) was the critical acidic residue for the integrin binding. The importance of this sequence was further confirmed by integrin binding inhibition assays using synthetic peptides. Immunohistochemical analyses of mouse embryonic tissues showed that polydom colocalized with integrin α9 in the stomach, intestine, and other organs. Furthermore, in situ integrin α9ß1 binding assays using frozen mouse tissues showed that polydom accounts for most, but not all, of the integrin α9ß1 ligands in tissues. Taken together, the present findings indicate that polydom is a hitherto unknown ligand for integrin α9ß1 that functions as a physiological ligand in vivo.

HIG1, a novel regulator of mitochondrial γ-secretase, maintains normal mitochondrial function.

The γ-secretase complex (which contains presenilins, nicastrin, anterior pharynx defective-1, and presenilin enhancer-2) cleaves type I transmembrane proteins, including Notch and amyloid precursor protein. Dysregulated γ-secretase activity has been implicated in the pathogenesis of Alzheimer's disease, stroke, atherosclerosis, and cancer. Tight regulation of γ-secretase activity is required for normal physiology. Here, we isolated HIG1 (hypoxia inducible gene 1, domain member 1A) from a functional screen of γ-secretase inhibitory genes. HIG1 was highly expressed in the brain. Interestingly, HIG1 was localized to the mitochondria and was directly bound to γ-secretase components on the mitochondrial membrane in SK-N-SH neuroblastoma cells. Overexpresssion of HIG1 attenuated hypoxia-induced γ-secretase activation on the mitochondrial membrane and the accumulation of intracellular amyloid ß. This accumulation was accompanied by hypoxia-induced mitochondrial dysfunction. The latter half domain of HIG1 was required for binding to the γ-secretase complex and suppression of γ-secretase activity. Moreover, depletion of HIG1 increased γ-secretase activation and enhanced hypoxia-induced mitochondrial dysfunction. In summary, HIG1 is a novel modulator of the mitochondrial γ-secretase complex, and may play a role in the maintenance of normal mitochondrial function.

Real-world outcomes of rivaroxaban treatment in patients with nonvalvular atrial fibrillation and worsening renal function.

BACKGROUND: Rivaroxaban is a direct oral anticoagulant administered to reduce the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation (NVAF). The Xarelto Post-Authorization Safety and Effectiveness Study in Japanese Patients with Atrial Fibrillation (XAPASS) was a prospective, observational, post-marketing surveillance study that examined the safety and effectiveness of rivaroxaban in routine clinical practice. This sub-analysis of the XAPASS investigated the outcomes of patients with worsening renal function (WRF). METHODS: The XAPASS included 11,308 patients with NVAF who began treatment with rivaroxaban. Of 9578 patients who completed 1-year follow-up, the 7509 patients, for whom the change in creatinine clearance could be assessed, were included in the present analysis. Patients with WRF were those with a decrease in creatinine clearance of ≥20% from enrollment to any time point; patients with stable renal function (SRF) were those without such a decrease. Outcomes in patients with WRF versus SRF were compared at 1 year. RESULTS: We identified 1229 patients with WRF and 6280 patients with SRF. Patients with WRF were older and had higher mean CHADS2 and modified HAS-BLED scores compared to patients with SRF. The incidence rates of any bleeding (hazard ratio: 1.12; 95% confidence interval: 0.88-1.41), major bleeding (1.20; 0.75-1.90), and the composite endpoint stroke/systemic embolism/myocardial infarction (1.06; 0.65-1.71) were similar between the two groups. CONCLUSIONS: No association between WRF and occurrence of any bleeding, major bleeding, and stroke/systemic embolism/myocardial infarction was observed in patients with AF on rivaroxaban treatment during 1-year follow-up in real-world clinical practice. Clinicaltrials.gov: NCT01582737.

Real-world outcomes of the Xarelto Post-Authorization Safety & Effectiveness Study in Japanese Patients with Atrial Fibrillation (XAPASS).

BACKGROUND: Although the efficacy and safety of the factor Xa inhibitor rivaroxaban for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation (NVAF) were shown in global and Japanese phase III clinical trials, safety and effectiveness data from unselected patients in everyday clinical practice are limited. The objective of the XAPASS (Xarelto Post-Authorization Safety & Effectiveness Study in Japanese Patients with Atrial Fibrillation) is to investigate the safety and effectiveness of rivaroxaban in Japanese real-world clinical practice. METHODS: The XAPASS is a prospective, single-arm, real-world observational study mandated by the Japanese authority as post-marketing surveillance. In total, 11,308 patients with NVAF who began treatment with rivaroxaban were enrolled from April 2012 to June 2014, and 9578 patients were analyzed to examine the one-year outcomes. RESULTS: The mean treatment duration was 300±119 days. The patients' age was 73.2±9.8 years, and their CHADS2 score was 2.2±1.3. Any bleeding and major bleeding occurred in 602 patients (7.6 events per 100 patient-years) and 143 patients (1.8 events per 100 patient-years), respectively. Stroke/non-central nervous system systemic embolism/myocardial infarction was observed in 144 patients (1.8 events per 100 patient-years). CONCLUSIONS: Real-world outcomes of the XAPASS showed incidence rates of major bleeding and thromboembolic events, suggesting that rivaroxaban is safe and effective in Japanese daily clinical practice (Clinicaltrials.gov: NCT01582737).

Lineage tracing of murine adult hematopoietic stem cells reveals active contribution to steady-state hematopoiesis.

Characterization of hematopoietic stem cells (HSCs) has advanced largely owing to transplantation assays, in which the developmental potential of HSCs is assessed generally in nonhomeostatic conditions. These studies established that adult HSCs extensively contribute to multilineage hematopoietic regeneration upon transplantation. On the contrary, recent studies performing lineage tracing of HSCs under homeostatic conditions have shown that adult HSCs may contribute far less to steady-state hematopoiesis than would be anticipated based on transplantation assays. Here, we used 2 independent HSC-lineage-tracing models to examine the contribution of adult HSCs to steady-state hematopoiesis. We show that adult HSCs contribute robustly to steady-state hematopoiesis, exhibiting faster efflux toward the myeloid lineages compared with lymphoid lineages. Platelets were robustly labeled by HSCs, reaching the same level of labeling as HSCs by 1 year of chase. Our results support the view that adult HSCs contribute to the continuous influx of blood cells during steady-state hematopoiesis.

Design and baseline characteristics of the Xarelto Post-Authorization Safety & Effectiveness Study in Japanese Patients with Atrial Fibrillation (XAPASS).

Background: The phase III Japanese Rivaroxaban Once-Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (J-ROCKET AF) showed that the rivaroxaban group had a lower event rate of intracranial bleeding than the warfarin group and that rivaroxaban was noninferior to warfarin for the principal safety outcome. However, safety and effectiveness data from unselected patients with AF in everyday clinical practice in Japan are lacking. Methods: The Xarelto Post-Authorization Safety & Effectiveness Study in Japanese Patients with Atrial Fibrillation (XAPASS) is a real-world, prospective, single-arm, observational study mandated by the Japanese authority as postmarketing surveillance. XAPASS involves patients with nonvalvular AF prescribed rivaroxaban. The principal safety outcome is a composite of major and nonmajor bleeding events, and the primary effectiveness outcome is the incidence of ischemic stroke, hemorrhagic stroke, noncentral nervous system systemic embolism, and myocardial infarction. Results: In total, 11 308 patients were enrolled from April 2012 to June 2014. Their age was 73.1 ± 9.9 years, and their CHADS 2 score was 2.2 ± 1.3. Female patients, patients aged ≥75 years, patients with a body weight of ≤50 kg, and patients with a creatinine clearance of <50 mL/min constituted 38.1%, 48.7%, 19.5%, and 23.9% of all patients, respectively. Almost half (53.2%) of patients were prescribed other anticoagulants before starting rivaroxaban. Conclusions: Data from this study will supplement those from the J-ROCKET AF and provide practical information for the optimal use of rivaroxaban for stroke prevention in Japanese patients with AF (Clinicaltrials.gov: NCT01582737).

Regulation of alternative polyadenylation by Nkx2-5 and Xrn2 during mouse heart development.

Transcription factors organize gene expression profiles by regulating promoter activity. However, the role of transcription factors after transcription initiation is poorly understood. Here, we show that the homeoprotein Nkx2-5 and the 5'-3' exonuclease Xrn2 are involved in the regulation of alternative polyadenylation (APA) during mouse heart development. Nkx2-5 occupied not only the transcription start sites (TSSs) but also the downstream regions of genes, serving to connect these regions in primary embryonic cardiomyocytes (eCMs). Nkx2-5 deficiency affected Xrn2 binding to target loci and resulted in increases in RNA polymerase II (RNAPII) occupancy and in the expression of mRNAs with long 3'untranslated regions (3' UTRs) from genes related to heart development. siRNA-mediated suppression of Nkx2-5 and Xrn2 led to heart looping anomaly. Moreover, Nkx2-5 genetically interacts with Xrn2 because Nkx2-5(+/-)Xrn2(+/-), but neither Nkx2-5(+/-)nor Xrn2(+/-), newborns exhibited a defect in ventricular septum formation, suggesting that the association between Nkx2-5 and Xrn2 is essential for heart development. Our results indicate that Nkx2-5 regulates not only the initiation but also the usage of poly(A) sites during heart development. Our findings suggest that tissue-specific transcription factors is involved in the regulation of APA.

The transcription factors Tbx18 and Wt1 control the epicardial epithelial-mesenchymal transition through bi-directional regulation of Slug in murine primary epicardial cells.

During cardiac development, a subpopulation of epicardial cells migrates into the heart as part of the epicardial epithelial-mesenchymal transition (EMT) and differentiates into smooth muscle cells and fibroblasts. However, the roles of transcription factors in the epicardial EMT are poorly understood. Here, we show that two transcription factors expressed in the developing epicardium, T-box18 (Tbx18) and Wilms' tumor 1 homolog (Wt1), bi-directionally control the epicardial EMT through their effects on Slug expression in murine primary epicardial cells. Knockdown of Wt1 induced the epicardial EMT, which was accompanied by an increase in the migration and expression of N-cadherin and a decrease in the expression of ZO-1 as an epithelial marker. By contrast, knockdown of Tbx18 inhibited the mesenchymal transition induced by TGFß1 treatment and Wt1 knockdown. The expression of Slug but not Snail decreased as a result of Tbx18 knockdown, but Slug expression increased following knockdown of Wt1. Knockdown of Slug also attenuated the epicardial EMT induced by TGFß1 treatment and Wt1 knockdown. Furthermore, in normal murine mammary gland-C7 (NMuMG-C7) cells, Tbx18 acted to increase Slug expression, while Wt1 acted to decrease Slug expression. Chromatin immunoprecipitation and promoter assay revealed that Tbx18 and Wt1 directly bound to the Slug promoter region and regulated Slug expression. These results provide new insights into the regulatory mechanisms that control the epicardial EMT.

Basement membrane assembly of the integrin α8ß1 ligand nephronectin requires Fraser syndrome-associated proteins.

Dysfunction of the basement membrane protein QBRICK provokes Fraser syndrome, which results in renal dysmorphogenesis, cryptophthalmos, syndactyly, and dystrophic epidermolysis bullosa through unknown mechanisms. Here, we show that integrin α8ß1 binding to basement membranes was significantly impaired in Qbrick-null mice. This impaired integrin α8ß1 binding was not a direct consequence of the loss of QBRICK, which itself is a ligand of integrin α8ß1, because knock-in mice with a mutation in the integrin-binding site of QBRICK developed normally and do not exhibit any defects in integrin α8ß1 binding. Instead, the loss of QBRICK significantly diminished the expression of nephronectin, an integrin α8ß1 ligand necessary for renal development. In vivo, nephronectin associated with QBRICK and localized at the sublamina densa region, where QBRICK was also located. Collectively, these findings indicate that QBRICK facilitates the integrin α8ß1-dependent interactions of cells with basement membranes by regulating the basement membrane assembly of nephronectin and explain why renal defects occur in Fraser syndrome.