Complement C1q activates canonical Wnt signaling and promotes aging-related phenotypes.

Wnt signaling plays critical roles in development of various organs and pathogenesis of many diseases, and augmented Wnt signaling has recently been implicated in mammalian aging and aging-related phenotypes. We here report that complement C1q activates canonical Wnt signaling and promotes aging-associated decline in tissue regeneration. Serum C1q concentration is increased with aging, and Wnt signaling activity is augmented during aging in the serum and in multiple tissues of wild-type mice, but not in those of C1qa-deficient mice. C1q activates canonical Wnt signaling by binding to Frizzled receptors and subsequently inducing C1s-dependent cleavage of the ectodomain of Wnt coreceptor low-density lipoprotein receptor-related protein 6. Skeletal muscle regeneration in young mice is inhibited by exogenous C1q treatment, whereas aging-associated impairment of muscle regeneration is restored by C1s inhibition or C1qa gene disruption. Our findings therefore suggest the unexpected role of complement C1q in Wnt signal transduction and modulation of mammalian aging.

Oral anticoagulation after atrial fibrillation catheter ablation: benefits and risks.

BACKGROUND AND AIMS: Few recent large-scale studies have evaluated the risks and benefits of continuing oral anticoagulant (OAC) therapy after catheter ablation (CA) for atrial fibrillation (AF). This study evaluated the status of continuation of OAC therapy and the association between continuation of OAC therapy and thromboembolic and bleeding events according to the CHADS2 score. METHODS: This retrospective study included data from the Japanese nationwide administrative claims database of patients who underwent CA for AF between April 2014 and March 2021. Patients without AF recurrence assessed by administrative data of the treatment modalities were divided into two groups according to continuation of OAC therapy 6 months after the index CA. The primary outcomes were thromboembolism and major bleeding after a landmark period of 6 months. After inverse probability of treatment weighting analysis, the association between OAC continuation and outcomes was determined according to the CHADS2 score. RESULTS: Among 231 374 patients included, 69.7%, 21.6%, and 8.7% had CHADS2 scores of ≤1, 2, and ≥3, respectively. Of these, 71% continued OAC therapy at 6 months. The OAC continuation rate was higher in the high CHADS2 score group than that in the low CHADS2 score group. Among all patients, 2451 patients (0.55 per 100 person-years) had thromboembolism and 2367 (0.53 per 100 person-years) had major bleeding. In the CHADS2 score ≤1 group, the hazard ratio of the continued OAC group was 0.86 [95% confidence interval (CI): 0.74-1.01, P = .06] for thromboembolism and was 1.51 (95% CI: 1.27-1.80, P < .001) for major bleeding. In the CHADS2 score ≥3 group, the hazard ratio of the continued OAC group was 0.61 (95% CI: 0.46-0.82, P = .001) for thromboembolism and was 1.05 (95% CI: 0.71-1.56, P = 0.81) for major bleeding. CONCLUSIONS: This observational study suggests that the benefits and risks of continuing OAC therapy after CA for AF differ based on the patient's CHADS2 score. The risk of major bleeding due to OAC continuation seems to outweigh the risk reduction of thromboembolism in patients with lower thromboembolic risk.

Impact of left atrial appendage flow velocity on thrombus resolution and clinical outcomes in patients with atrial fibrillation and silent left atrial thrombi: insights from the LAT study.

AIMS: Blood stasis is crucial in developing left atrial (LA) thrombi. LA appendage peak flow velocity (LAAFV) is a quantitative parameter for estimating thromboembolic risk. However, its impact on LA thrombus resolution and clinical outcomes remains unclear. METHODS AND RESULTS: The LAT study was a multicentre observational study investigating patients with atrial fibrillation (AF) and silent LA thrombi detected by transoesophageal echocardiography (TEE). Among 17 436 TEE procedures for patients with AF, 297 patients (1.7%) had silent LA thrombi. Excluding patients without follow-up examinations, we enrolled 169 whose baseline LAAFV was available. Oral anticoagulation use increased from 85.7% at baseline to 97.0% at the final follow-up (P < 0.001). During 1 year, LA thrombus resolution was confirmed in 130 (76.9%) patients within 76 (34-138) days. Conversely, 26 had residual LA thrombi, 8 had thromboembolisms, and 5 required surgical removal. These patients with failed thrombus resolution had lower baseline LAAFV than those with successful resolution (18.0 [15.8-22.0] vs. 22.2 [17.0-35.0], P = 0.003). Despite limited predictive power (area under the curve, 0.659; P = 0.001), LAAFV ≤ 20.0 cm/s (best cut-off) significantly predicted failed LA thrombus resolution, even after adjusting for potential confounders (odds ratio, 2.72; 95% confidence interval, 1.22-6.09; P = 0.015). The incidence of adverse outcomes including ischaemic stroke/systemic embolism, major bleeding, or all-cause death was significantly higher in patients with reduced LAAFV than in those with preserved LAAFV (28.4% vs. 11.6%, log-rank P = 0.005). CONCLUSION: Failed LA thrombus resolution was not rare in patients with AF and silent LA thrombi. Reduced LAAFV was associated with failed LA thrombus resolution and adverse clinical outcomes.

Postdischarge functional outcomes in older patients with acute heart failure in Japan: the Longevity Improvement & Fair Evidence study.

BACKGROUND: The association between care needs level (CNL) at hospitalisation and postdischarge outcomes in older patients with acute heart failure (aHF) has been insufficiently investigated. METHODS: This population-based cohort study was conducted using health insurance claims and CNL data of the Longevity Improvement & Fair Evidence study. Patients aged ≥65 years, discharged after hospitalisation for aHF between April 2014 and March 2022, were identified. CNLs at hospitalisation were classified as no care needs (NCN), support level (SL) and CNL1, CNL2-3 and CNL4-5 based on total estimated daily care time as defined by national standard criteria, and varied on an ordinal scale between SL&CNL1 (low level) to CNL4-5 (fully dependent). The primary outcomes were changes in CNL and death 1 year after discharge, assessed by CNL at hospitalisation using Cox proportional hazard models. RESULTS: Of the 17 724 patients included, 7540 (42.5%), 4818 (27.2%), 3267 (18.4%) and 2099 (11.8%) had NCN, SL&CNL1, CNL2-3 and CNL4-5, respectively, at hospitalisation. One year after discharge, 4808 (27.1%), 3243 (18.3%), 2968 (16.7%), 2505 (14.1%) and 4200 (23.7%) patients had NCN, SL&CNL1, CNL2-3, CNL4-5 and death, respectively. Almost all patients' CNLs worsened after discharge. Compared to patients with NCN at hospitalisation, patients with SL&CNL1, CNL2-3 and CNL4-5 had an increased risk of all-cause death 1 year after discharge (hazard ratio [95% confidence interval]: 1.19 [1.09-1.31], 1.88 [1.71-2.06] and 2.56 [2.31-2.84], respectively). CONCLUSIONS: Older patients with aHF and high CNL at hospitalisation had a high risk of all-cause mortality in the year following discharge.

Validity of Diagnostic Algorithms for Cardiovascular Diseases in Japanese Health Insurance Claims.

BACKGROUND: We aimed to validate a claims-based diagnostic algorithm to identify hospitalized patients with acute major cardiovascular diseases (CVDs) from health insurance claims in Japan.Methods and Results: This retrospective multicenter validation study was conducted at 4 institutes, including Japanese Circulation Society-certified and uncertified hospitals in Japan. Data on patients with CVDs in departmental lists or with International Classification of Diseases, 10th Revision (ICD-10) codes for CVDs hospitalized between April 2018 and March 2019 were extracted. We examined the sensitivity and positive predictive value of a diagnostic algorithm using ICD-10 codes, medical examinations, and treatments for acute coronary syndrome (ACS), acute heart failure (HF), and acute aortic disease (AAD). We identified 409 patients with ACS (mean age 70.6 years; 24.7% female), 615 patients with acute HF (mean age 77.3 years; 46.2% female), and 122 patients with AAD (mean age 73.4 years; 36.1% female). The respective sensitivity and positive predictive value for the algorithm were 0.86 (95% confidence interval [CI] 0.82-0.89) and 0.95 (95% CI 0.92-0.97) for ACS; 0.74 (95% CI 0.70-0.77) and 0.79 (95% CI 0.76-0.83) for acute HF; and 0.86 (95% CI 0.79-0.92) and 0.83 (95% CI 0.76-0.89) for AAD. CONCLUSIONS: The validity of the diagnostic algorithm for Japanese claims data was acceptable. Our results serve as a foundation for future studies on CVDs using nationwide administrative data.

The efficacy and safety of adaptive servo-ventilation therapy for heart failure with preserved ejection fraction.

It is unclear whether adaptive servo-ventilation (ASV) therapy for heart failure with preserved ejection fraction (HFpEF) is effective. The aim of this study was to investigate the details of ASV use, and to evaluate the effectiveness and safety of ASV in real-world HFpEF patients. We retrospectively enrolled 36 HFpEF patients at nine cardiovascular centers who initiated ASV therapy during hospitalization or on outpatient basis and were able to continue using it at home from 2012 to 2017 and survived for at least one year thereafter. The number of hospitalizations for heart failure (HF) during the 12 months before and 12 months after introduction of ASV at home was compared. The median number of HF hospitalizations for each patient was significantly reduced from 1 [interquartile range: 1-2] in the 12 months before introduction of ASV to 0 [0-0] in the 12 months after introduction of ASV (p < 0.001). In subgroup analysis, reduction in heart failure hospitalization was significantly greater in female patients, patients with a body mass index < 25, and those with moderate or severe tricuspid valve regurgitation. In patients with HFpEF, the number of HF hospitalizations was significantly decreased after the introduction of ASV. HFpEF patients with female sex, BMI < 25, or moderate to severe tricuspid valve regurgitation are potential candidates who might benefit from ASV therapy.

The impact of hospital case volume on the outcomes after catheter ablation for atrial fibrillation according to the ablation technology.

INTRODUCTION: The appropriate hospital case volume for catheter ablation (CA) in patients with atrial fibrillation (AF) according to the ablation technology has not been fully examined. This study aimed to investigate the association between the hospital case volume for AF and periprocedural complications and AF recurrence. METHODS: In this retrospective cohort study, we used data from the National Database of Health Insurance Claims and Specific Health Checkups, which covers almost all healthcare insurance claims data in Japan. We included patients with AF who underwent first-time CA from April 2014 to March 2020. Using mixed-effect logistic regression, we analyzed the effect of the annual case volume for AF ablation on acute periprocedural complications and 1-year success rate off antiarrhythmic drugs according to the ablation technology (radiofrequency ablation or cryoballoon ablation). RESULTS: Among 270 116 patients, 207 839 (77%) patients underwent radiofrequency ablation and 56 648 (21%) patients underwent cryoballoon ablation. Of all patients, acute complications occurred in 5411 (2.0%) patients, and the recurrence at 1 year was 71 511 (27%). In the radiofrequency ablation group, acute complications and 1-year AF recurrence according to case volume decreased as the annual case volume increased to up to 150-200 cases/year. However, in the cryoballoon ablation group, these outcomes were similar regardless of the case volumes. CONCLUSION: The case-volume effect was noted in the radiofrequency ablation group, but not in the cryoballoon ablation group. Our results may affect the selection of ablation technology, especially in smaller case-volume hospitals.

Contemporary use of SGLT2 inhibitors in heart failure patients with diabetes mellitus: a comparison of DPP4 inhibitors in a nationwide electric health database of the superaged society.

BACKGROUND: There is a lack of recent data reflecting the actual use of sodium-glucose cotransporter-2 (SGLT2) inhibitors for heart failure (HF) and type 2 diabetes (DM) in the superaged society. The present study investigated the association between the use of SGLT2 inhibitors and one-year prognosis in patients hospitalized across a broad spectrum of HF patients with DM in the superaged society using the Nationwide Electric Health Database in Japan. METHODS: The patients hospitalized with the first episode of acute HF were identified from the National Database of Health Insurance Claims and Specific Health Checkups of Japan between April 2014 and March 2019. A cohort of 2,277 users of SGLT2 inhibitors and 41,410 users of the active comparator, dipeptidyl peptidase-4 (DPP4) inhibitors were compared. A propensity score-matched cohort study of 2,101 users of each inhibitor was also conducted. A multivariable multilevel mixed-effects survival model was conducted with adjustments, and hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated. RESULTS: Among 300,398 patients discharged with HF in 4,176 hospitals, 216,016 (71.9%) were 75 years or older, and 60,999 (20.3%) took antidiabetic medications. Among them, the patients treated with SGLT2 inhibitors were younger and had a more severe status than those treated with DPP4 inhibitors. Kaplan-Meier analysis showed that patients treated with SGLT2 inhibitors had a lower mortality risk and HF readmission. In propensity-matched cohorts, SGLT2 inhibitor use was associated with a lower risk of mortality and HF readmission than DPP-4 inhibitor use (HR [95% CI]; 0.70 [0.56, 0.89] and 0.52 [0.45, 0.61], respectively). Very elderly (≥ 75 years) patients showed similar results. Favorable effects were also observed across all age groups, including ≥ 75 years, in patients with coronary artery disease or atrial fibrillation and with concomitant ß-blocker, diuretics, or insulin. CONCLUSION: The use of SGLT2 inhibitors at discharge was associated with a lower risk of one-year mortality and HF readmission in patients across a broad spectrum of HF with DM in the superaged society. The findings further support the benefits of using SGLT2 inhibitors in very elderly HF care and complement the current evidence.

Abdominal obesity, and not general obesity, is associated with a lower 123I MIBG heart-to-mediastinum ratio in heart failure patients with preserved ejection fraction.

BACKGROUND: The relationship between general obesity or abdominal obesity (abdominal circumference of ≥85 cm in men and ≥ 90 cm in women) and the heart-to-mediastinum ratio (HMR), a measure of cardiac sympathetic innervation, on cardiac iodine-123-metaiodobenzylguanidine scintigraphy (MIBG) in patients with heart failure with preserved ejection fraction (HFpEF) has not been clarified. METHODS: A total of 239 HFpEF patients with both MIBG and abdominal circumference data were examined. We divided these patients into those with abdominal obesity and those without it. In the cardiac MIBG study, early phase image was acquired 15-20 min after injection, and late phase image was acquired 3 h after the early phase. A HMR obtained from a low-energy type collimator was converted to that obtained by a medium-energy type collimator. RESULTS: Early and late HMRs were significantly lower in those with abdominal obesity, although washout rates were not significantly different. The incidence of patients with early and late HMRs <2.2 was significantly higher in those with abdominal obesity. Multivariate linear regression analysis revealed that abdominal obesity was independently associated with early HMR (standardized ß = -0.253, P = 0.003) and late HMR (standardized ß = -0.222, P = 0.010). Multivariate logistic regression analysis revealed that abdominal obesity was independently associated with early (odds ratio [OR] [95% confidence interval {CI}] = 4.25 [2.13, 8.47], P < 0.001) and late HMR < 2.2 (OR [95% CI] = 2.06 [1.11, 3.83], P = 0.022). Elevated BMI was not significantly associated with low early and late HMR. The presence of abdominal obesity was significantly associated with low early and late HMR even in patients without elevated BMI values. CONCLUSION: Abdominal obesity, but not general obesity, in HFpEF patients was independently associated with low HMR, suggesting that visceral fat may contribute to decreased cardiac sympathetic activity in patients with HFpEF. TRIAL REGISTRATION: UMIN000021831.

Trends and Factors Associated With Cardiac Rehabilitation Participation　- Data From Japanese Nationwide Databases.

BACKGROUND: Few studies have comprehensively evaluated the trends and factors associated with CR participation across major cardiovascular diseases in Japan.Methods and Results: This study performed a nationwide cross-sectional study using the National Database of Health Insurance Claims and Specific Health Checkups of Japan and the Japanese Registry of All Cardiac and Vascular Diseases and the Diagnosis Procedure Combination database. This study described the nationwide trends and evaluated patient- and hospital-level associated factors of CR participation for patients with acute heart failure (AHF), acute coronary syndrome (ACS), acute aortic dissection (AAD), peripheral artery disease (PAD), and after cardiovascular surgery using mixed-effect logistic regression analysis. Although the annual number of patients who underwent CR has increased during the study period, the total number of patients participating in outpatient CR was lower than that of inpatient CR. The outpatient CR participation rate was lower for patients with AHF (3.5%), AAD (3.2%), and PAD (1.7%), compared with ACS (7.9%) and after surgery (9.4%). Age, sex, body mass index, Barthel index, Charlson comorbidity index, and institutional capacity were identified as significant associated factors of CR participation in inpatient and outpatient settings. CONCLUSIONS: Participation in outpatient CR was still low, and higher age, multi-comorbidity, and low institutional capacity contributed to the lower outpatient CR participation rate. Identification of the associated factors may help cardiologists to increase CR participation.

Sex Differences in the Efficacy of Pulmonary Vein Isolation Alone vs. Extensive Catheter Ablation in Patients With Persistent Atrial Fibrillation.

BACKGROUND: Women experience more severe arrhythmogenic substrates. This study hypothesized that an extensive ablation strategy, such as linear ablation and/or complex fractionated atrial electrogram (CFAE) ablation in addition to pulmonary vein isolation (PVI-plus), might be effective for women, whereas the PVI alone strategy (PVI-alone) might be sufficient for men to maintain sinus rhythm. The aim of this study was to test this hypothesis.Methods and Results: This study is a post-hoc subanalysis of the EARNEST-PVI trial focusing on sex differences in the efficacies of different ablation strategies. The EARNEST-PVI trial was a prospective, multicenter, randomized, and open-label non-inferiority trial in patients with persistent AF. The primary endpoint was recurrence of AF, atrial flutter, or atrial tachycardia. The EARNEST-PVI trial randomized 376 (76%) men (PVI-alone 186, PVI-plus 190) and 121 (24%) women (PVI-alone 63, PVI-plus 58). The event rate was significantly lower for men and numerically lower for women in the PVI-plus than the PVI-alone group, and there was no interaction between men and women (hazard ratio, 0.641; 95% confidence interval, 0.417-0.985; P value, 0.043 for men vs. hazard ratio, 0.661; 95% confidence interval, 0.352-1.240; P value, 0.197 for women; P value for interaction, 0.989). CONCLUSIONS: The superiority of the extensive ablation strategy vs. the PVI-alone strategy for persistent AF was consistent across both sexes.

Factors Associated With Prehospital Delay Among Patients With Acute Myocardial Infarction in the Era of Percutaneous Coronary Intervention　- Insights From the OACIS Registry.

BACKGROUND: The Japan Circulation Society launched the STOP-MI campaign in 2014, focusing on immediate hospital arrival for acute myocardial infarction (AMI) treatment. This study aimed to determine the factors influencing longer prehospital time among patients with AMI in Japan.Methods and Results:This study analyzed a total of 4,625 AMI patients enrolled in the Osaka Acute Coronary Insufficiency Study registry from 1998 to 2014. The prehospital time delay was defined as the time interval from the onset of initial symptoms to hospital arrival time ≥2 h. Among eligible patients, 2,927 (63.3%) had a prehospital time ≥2 h. In multivariable analyses, age 65-79 years (adjusted odds ratio [AOR] 1.19, 95% confidence interval [CI] 1.02-1.39), age ≥80 years (AOR 1.42, 95% CI 1.13-1.79), diabetes mellitus (AOR 1.33, 95% CI 1.16-1.52), and onset time of 0:00-5:59 h (AOR 1.63, 95% CI 1.37-1.95) were positively associated with prehospital time ≥2 h, whereas smoking (AOR 0.78, 95% CI 0.68-0.90) and ambulance use (AOR 0.37, 95% CI 0.32-0.43) were negatively associated with prehospital time ≥2 h. CONCLUSIONS: Older age, diabetes mellitus, and nighttime onset were associated with prehospital time delay for AMI patients, whereas smoking and ambulance use were associated with no prehospital time delay. Healthcare providers and patients could help reduce the time to get to a medical facility by being aware of these findings.

Prognostic Impact of Echocardiographic Diastolic Dysfunction on Outcomes in Patients With Heart Failure With Preserved Ejection Fraction　- Insights From the PURSUIT-HFpEF Registry.

BACKGROUND: Although diastolic dysfunction is important pathophysiology in heart failure with preserved ejection fraction (HFpEF), its prognostic impact in HFpEF patients, including those with atrial fibrillation (AF), remains to be elucidated.Methods and Results:We included the data for 863 patients (321 patients with AF) registered in a prospective multicenter observational study of patients with HFpEF. Patients were divided into 3 groups according to the 2016 ASE/EACVI recommendations. The primary endpoint was a composite of all-cause death or HF rehospitalization. Median age was 83 years, and 55.5% were female. 196 (22.7%) were classified with normal diastolic function (ND), 253 (29.3%) with indeterminate (ID) and 414 (48.0%) with diastolic dysfunction (DD). The primary endpoint occurred more frequently in patients with DD than in those with ND or ID (log-rank P<0.001 for DD vs. ND, and log-rank P=0.007 for DD vs. ID, respectively). Taking ND as the reference, multivariable Cox regression analysis revealed that DD (hazard ratio (HR): 1.57, 95% confidence interval (CI):1.06-2.32, P=0.024) was independently associated with the composite endpoint, whereas ID (HR: 1.28, 95% CI: 0.84-1.95, P=0.255) was not. DD was associated with the composite endpoint in both patients with and without AF. CONCLUSIONS: HFpEF patients classified with DD using the 2016 ASE/EACVI recommendations had worse clinical outcomes than those with ND or ID. DD may be considered a prognostic marker in patients with HFpEF regardless of AF.

Prevalence of the Japanese high bleeding risk criteria and its prognostic significance for fatal bleeding in patients with acute myocardial infarction.

BACKGROUND: The Japanese high-bleeding-risk criteria (Japanese-HBR), modified criteria of the Academic Research Consortium (ARC) HBR, has been recently proposed. We aimed to investigate the prevalence of the ARC-HBR and the Japanese-HBR, and to assess their prognostic significance in patients with acute myocardial infarction (AMI). METHODS AND RESULTS: We applied the ARC-HBR and the Japanese-HBR criteria to the OACIS prospective multicenter acute myocardial infarction registry (12,093 patients, 66 ± 12 years, 9,096 males). The primary endpoint was fatal bleeding (BARC-5). Median follow-up duration was 4.84 [inter-quartile range 1.35, 5.01] years. Prevalence of the ARC-HBR was 43.8%, while that of the Japanese-HBR was 61.8%. Cumulative incidence of fatal bleeding was higher in the ARC-HBR group than in the no ARC-HBR group at 1 year (1.3 vs. 0.6%) and at 5 years (2.0 vs. 0.7%). The Kaplan-Meier curves stratified by the Japanese-HBR criteria more prominently diverged (1.3 vs. 0.2% at 1 year; and 1.9 vs. 0.3% at 5 years). The Japanese-HBR criteria showed superior discriminative performance over the ARC-HBR criteria (C-statistics: 0.677 vs. 0.598, P < 0.001). CONCLUSIONS: In the real-world Japanese AMI registry, nearly half of the patients fulfilled the criteria of ARC-HBR, and two-thirds met the Japanese-HBR. Our findings support the validity of both ARC- and Japanese-HBR criteria in AMI patients but encourage the future application of the Japanese-HBR criteria to the Japanese AMI cohort. TRIAL REGISTRATION NUMBER: UMIN000004575.

The Effect of a Cancer History on Patients with Acute Myocardial Infarction After Percutaneous Coronary Intervention.

The effect of a history of cancer on the prognosis of patients with acute myocardial infarction (AMI) after percutaneous coronary intervention (PCI) is poorly understood.From the Osaka Acute Coronary Insufficiency Study (OACIS) registry in Osaka, Japan, we enrolled the case data of a total of 3499 patients with AMI treated with PCI between 1998 and 2014, of whom 462 had a cancer history (cancer group, 13.2%) and 3037 did not (non-cancer group, 86.8%). All of the cases were followed for up to five years from discharge.The Kaplan-Meier curve and multivariate analysis using Cox proportional hazards models revealed that all-cause mortality was significantly higher in the cancer group than in the non-cancer group (adjusted hazard ratio [HR], 2.43; P < 0.001). Deaths from cardiac, cancer, and other causes were treated as competing events, and competing analysis using the cumulative incidence function (CIF) and Fine-Gray model revealed that mortality due to cancer was higher in the cancer group than in the non-cancer group, whereas cardiac mortality was similar between the two groups. The incidences of cardiovascular events, including stroke, recurrent infarction, and heart failure requiring readmission, were also similar between the two groups, although the Kaplan-Meier analysis and univariate Cox proportional hazards model revealed that the incidence of stroke was higher in the cancer group than in the non-cancer group.A history of cancer increased all-cause and cancer mortality among patients with AMI treated with PCI, although it was not associated with cardiovascular events.

Activation of DNA Damage Response and Cellular Senescence in Cardiac Fibroblasts Limit Cardiac Fibrosis After Myocardial Infarction.

Cardiac fibrosis plays an important role in cardiac remodeling after myocardial infarction (MI). The molecular mechanisms that promote cardiac fibrosis after MI are well studied; however, the mechanisms by which the progression of cardiac fibrosis becomes attenuated after MI remain poorly understood. Recent reports show the role of cellular senescence in limiting tissue fibrosis. In the present study, we tested whether cellular senescence of cardiac fibroblasts (CFs) plays a role in attenuating the progression of cardiac fibrosis after MI. We found that the number of γH2AX-positive CFs increased up to day 7, whereas the number of proliferating CFs peaked at day 4 after MI. Senescent CFs were also observed at day 7, suggesting that attenuation of CF proliferation occurred simultaneously with the activation of the DNA damage response (DDR) system and the appearance of senescent CFs. We next cultured senescent CFs with non-senescent CFs and showed that senescent CFs suppressed proliferation of the surrounding non-senescent CFs in a juxtacrine manner. We also found that the blockade of DDR by Atm gene deletion sustained the proliferation of CFs and exacerbated the cardiac fibrosis at the early stage after MI. Our results indicate the role of DDR activation and cellular senescence in limiting cardiac fibrosis after MI. Regulation of cellular senescence in CFs may become one of the therapeutic strategies for preventing cardiac remodeling after MI.

Generation of Fabry cardiomyopathy model for drug screening using induced pluripotent stem cell-derived cardiomyocytes from a female Fabry patient.

BACKGROUND: Fabry disease is an X-linked disease caused by mutations in α-galactosidase A (GLA); these mutations result in the accumulation of its substrates, mainly globotriaosylceramide (Gb3). The accumulation of glycosphingolipids induces pathogenic changes in various organs, including the heart, and Fabry cardiomyopathy is the most frequent cause of death in patients with Fabry disease. Existing therapies to treat Fabry disease have limited efficacy, and new approaches to improve the prognosis of patients with Fabry cardiomyopathy are required. METHODS AND RESULTS: We generated induced pluripotent stem cell (iPSC) lines from a female patient and her son. Each iPSC clone from the female patient showed either deficient or normal GLA activity, which could be used as a Fabry disease model or its isogenic control, respectively. Erosion of the inactivated X chromosome developed heterogeneously among clones, and mono-allelic expression of the GLA gene was maintained for a substantial period in a subset of iPSC clones. Gb3 accumulation was observed in iPSC-derived cardiomyocytes (iPS-CMs) from GLA activity-deficient iPSCs by mass-spectrometry and immunofluorescent staining. The expression of ANP was increased, but the cell surface area was decreased in iPS-CMs from the Fabry model, suggesting that cardiomyopathic change is ongoing at the molecular level in Fabry iPS-CMs. We also established an algorithm for selecting proper Gb3 staining that could be used for high-content analysis-based drug screening. CONCLUSIONS: We generated a Fabry cardiomyopathy model and a drug screening system by using iPS-CMs from a female Fabry patient. Drug screening using our system may help discover new drugs that would improve the prognosis of patients with Fabry cardiomyopathy.

Phenotypic Screening Using Patient-Derived Induced Pluripotent Stem Cells Identified Pyr3 as a Candidate Compound for the Treatment of Infantile Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is a genetic disorder that is characterized by hypertrophy of the myocardium. Some of the patients are diagnosed for HCM during infancy, and the prognosis of infantile HCM is worse than general HCM. Nevertheless, pathophysiology of infantile HCM is less investigated and remains largely unknown. In the present study, we generated induced pluripotent stem cells (iPSCs) from two patients with infantile HCM: one with Noonan syndrome and the other with idiopathic HCM. We found that iPSC-derived cardiomyocytes (iPSC-CMs) from idiopathic HCM patient were significantly larger and showed higher diastolic intracellular calcium concentration compared with the iPSC-CMs from healthy subject. Unlike iPSC-CMs from the adult/adolescent HCM patient, arrhythmia was not observed as a disease-related phenotype in iPSC-CMs from idiopathic infantile HCM patient. Phenotypic screening revealed that Pyr3, a transient receptor potential channel 3 channel inhibitor, decreased both the cell size and diastolic intracellular calcium concentration in iPSC-CMs from both Noonan syndrome and idiopathic infantile HCM patients, suggesting that the target of Pyr3 may play a role in the pathogenesis of infantile HCM, regardless of the etiology. Further research may unveil the possibility of Pyr3 or its derivatives in the treatment of infantile HCM.

Generation of Induced Pluripotent Stem Cells From Patients With Duchenne Muscular Dystrophy and Their Induction to Cardiomyocytes.

Duchenne muscular dystrophy (DMD) is caused by mutations in the DMD gene which encodes dystrophin protein. Dystrophin defect affects cardiac muscle as well as skeletal muscle. Cardiac dysfunction is observed in all patients with DMD over 18 years of age, but there is no curative treatment for DMD cardiomyopathy. To establish novel experimental platforms which reproduce the cardiac phenotype of DMD patients, here we established iPS cell lines from T lymphocytes donated from two DMD patients, with a protocol using Sendai virus vectors. We successfully conducted the differentiation of the DMD patient-specific iPS cells into beating cardiomyocytes. DMD patient-specific iPS cells and iPS cell-derived cardiomyocytes would be a useful in vitro experimental system with which to investigate DMD cardiomyopathy.