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長尾 学大学院医学研究科 医科学専攻准教授
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- BACKGROUND: Systemic insulin resistance plays an important role in the pathogenesis of type 2 diabetes and its complications. Although impaired branched-chain amino acid (BCAA) metabolism has been reported to be involved in the development of diabetes, the relationship between cardiac BCAA metabolism and the pathogenesis of diabetic cardiomyopathy (DbCM) remains unclear. OBJECTIVES: The aim of this study was to investigate BCAA metabolism in insulin-resistant hearts by using a novel mouse model of DbCM. METHODS: The cardiac phenotypes of adipocyte-specific 3'-phosphoinositide-dependent kinase 1 (PDK1)-deficient (A-PDK1KO) mice were assessed by histological analysis and echocardiography. The metabolic characteristics and cardiac gene expression were determined by mass spectrometry or RNA sequencing, respectively. Cardiac protein expression was evaluated by Western blot analysis. RESULTS: A-PDK1KO mouse hearts exhibited hypertrophy with prominent insulin resistance, consistent with cardiac phenotypes and metabolic disturbances previously reported as DbCM characteristics. RNA sequencing revealed the activation of BCAA uptake in diabetic hearts. In addition, the key enzymes involved in cardiac BCAA catabolism were downregulated at the protein level in A-PDK1KO mice, leading to the accumulation of BCAAs in the heart. Mechanistically, the accumulation of the BCAA leucine caused cardiac hypertrophy via the activation of mammalian target of rapamycin complex 1 (mTORC1). CONCLUSIONS: A-PDK1KO mice closely mimic the cardiac phenotypes and metabolic alterations observed in human DbCM and exhibit impaired BCAA metabolism in the heart. This model may contribute to a better understanding of DbCM pathophysiology and to the development of novel therapies for this disease.2025年04月, Cardiovascular diabetology, 24(1) (1), 167 - 167, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- BACKGROUND: Although tricuspid regurgitation (TR) is no longer considered a negligible disease, its detailed status in real-world heart failure (HF) patients remains unknown. METHODS AND RESULTS: From the KUNIUMI registry, we evaluated data for 1,646 consecutive HF patients. The primary endpoint was all-cause mortality over a median follow-up period of 3.0 years (interquartile range 1.4-3.0 years). Of the 1,646 HF patients, 369 (22.4%) had moderate or greater TR; the mean (±SD) age of these patients was 82.0±8.5 years. Atrial functional TR was the most common etiology of TR in HF patients with moderate or greater TR (70.7%), and was more common in HF patients with severe than moderate TR (75.5% vs. 65.3%; P=0.032). The mortality rate was high in HF patients with severe and moderate TR (27.1% and 17.0%, respectively). During follow-up, 33.1% of HF patients with moderate TR progressed to severe TR, and showed unfavorable all-cause mortality compared with those with unchanged TR. Atrial functional TR was a more common etiology in HF patients with moderate TR and worsened TR than in those with unchanged TR (84.6% vs. 59.5%; P=0.004). Right atrial enlargement was independently correlated with worsened TR. CONCLUSIONS: Moderate or greater TR was prevalent in 22.4% of the real-world super-aged HF population. Even HF patients with moderate TR had poor outcomes, with right atrial remodeling a key factor for worsened TR.2025年04月, Circulation journal : official journal of the Japanese Circulation Society, 英語, 国内誌研究論文（学術雑誌）
- AIM: Cholesterol uptake capacity (CUC) is a functional assessment of high-density lipoprotein (HDL) and has drawn attention for the risk stratification of atherosclerotic cardiovascular disease (ASCVD). This study evaluated the usefulness of HDL-CUC as a predictive marker for long-term ASCVD events in patients with coronary artery disease (CAD). METHODS: This retrospective observational study included 503 patients with CAD who underwent coronary revascularization. Blood was sampled from the participants within three months before or after index revascularization. The CUC was assayed using a previously reported automated system. The study population was divided into three groups according to the tertiles of CUC levels. The primary outcome was ASCVD events, which were defined as a composite of all-cause death, acute myocardial infarction, stroke, and peripheral artery disease. RESULTS: A total of 29 events were observed during the follow-up (median 2.8 years). The risk of the primary outcome in the low-CUC group was significantly higher than that in the high-CUC group (3-year incidence: low CUC 8.8% vs. high CUC 4.0%; log-rank p = 0.046). After adjusting for age and sex, the risk in the low-CUC group relative to that in the high-CUC group remained significantly high (hazard ratio 3.17, 95% confidence interval 1.05-9.54, p = 0.040). CONCLUSION: Low CUC in patients with CAD were associated with a higher risk of ASCVD events after coronary revascularization than high CUC levels. The assessment of HDL functionality measured by CUC would be useful for the risk prediction of ASCVD after coronary revascularization.2025年03月, Journal of atherosclerosis and thrombosis, 英語, 国内誌研究論文（学術雑誌）
- BACKGROUND: ATP citrate lyase (ACLY) is a key enzyme in de novo lipogenesis that generates acetyl-CoA from citrate. Although fatty acids are required for energy production and biomass synthesis in the heart, the regulatory mechanisms of ACLY-mediated de novo lipogenesis in pathological cardiac fibroblasts remain unknown. The aim of this study was to investigate the biological role of ACLY in cardiac remodeling. METHODS: Adeno-associated virus serotype 9-mediated shRNA targeting Acly was intravenously injected into C57BL/6J male mice. The mice were subsequently continuously infused with a mixture of angiotensin II and phenylephrine. Cardiac phenotypes were evaluated via histological staining. Cell proliferation assays, stable isotope tracing with 13C-labeled glucose, and chromatin immunoprecipitation assays were performed using human cardiac fibroblasts. RESULTS: ACLY expression was upregulated in the heart sections of mice treated with angiotensin II/phenylephrine, in particular in fibrotic areas. Masson trichrome staining revealed that Acly gene silencing significantly reduced cardiac fibrosis in these mice. Both siRNA-mediated ACLY knockdown and pharmacological ACLY inhibition suppressed the proliferation and expression of fibrous proteins in cultured human cardiac fibroblasts stimulated with transforming growth factor-β. Mechanistically, ACLY inhibition reduced de novo lipogenesis, limiting the fatty acid supply essential for cellular growth and proliferation. It also decreased H3K9 and H3K27 acetylation, in addition to the presence of acetylated H3K9 and H3K27 at the promoter regions of fibrotic genes. CONCLUSIONS: Our findings demonstrate that ACLY plays an important role in maladaptive cardiac fibrosis. ACLY could be a novel therapeutic target to prevent the development of heart failure.Ovid Technologies (Wolters Kluwer Health), 2025年03月, Hypertension[査読有り]研究論文（学術雑誌）
- Atrial fibrillation (AF) is strongly associated with strokes, heart failure, and increased mortality. This study aims to identify the monocyte-macrophage heterogeneity and interactions of these cells with non-immune cells, and to identify functional biomarkers in patients with AF. Therefore, we assess the single cell landscape of left atria (LA), using a combination of single cell and nucleus RNA-seq. Myeloid cells in LA tissue are categorized into five macrophage clusters, three monocyte clusters, and others. Cell-Chat analysis revealed that monocytes and IL1B+ macrophages send epidermal growth factor (EGF) signals to fibroblasts. Amphiregulin (AREG) is the most upregulated gene in monocytes and IL1B+ macrophages in the AF group, compared with healthy controls from other groups. Serum AREG levels are higher in patients with persistent AF. These data suggested that EGF signaling pathway could be a therapeutic target for AF and serum AREG levels provide an effective biomarker for predicting persistent AF.2024年12月, Communications biology, 7(1) (1), 1601 - 1601, 英語, 国際誌研究論文（学術雑誌）
- BACKGROUND: Stage B heart failure (HF) refers to structural heart disease without signs or symptoms of HF, so that early intervention may delay or prevent the onset of overt HF. However, stage B HF is a very broad concept, and risk stratification of such patients can be challenging. METHODS AND RESULTS: We conducted a prospective study of data for 1646 consecutive patients with HF from the KUNIUMI (Kobe University Heart Failure Registry in Awaji Medical Center) registry chronic cohort. The definition of HF stages was based on current guidelines for classification of 29 patients as stage A HF, 761 as stage B HF, 827 as stage C HF, and 29 patients as stage D HF. The primary end point was the time-to-first-event defined as cardiovascular death or HF hospitalization within 2.0 years of follow-up. A maximum of 6 adjustment factor points was assigned based on Cox proportional hazards analysis findings for the hazard ratio (HR) of independent risk factors for the primary end point: 1 point for anemia, estimated glomerular filtration rate <45 mL/min per 1.73 m2, brain natriuretic peptide ≥150 pg/mL, and average ratio of early transmitral flow velocity to early diastolic mitral annular velocity >14, and 2 points for clinical frailty scale >3. Patients with stage B HF were stratified into 3 groups, low risk (0-1 points), moderate risk (2-3 points), and high risk (4-6 points). Based on this scoring system (BEEAF2 [brain natriuretic peptide, estimated glomerular filtration rate, ratio of early transmitral flow velocity to early diastolic mitral annular velocity, anemia, and frailty]), the outcome was found to become worse in accordance with risk level. High-risk patients with stage B HF and patients with stage C HF showed similar outcomes. CONCLUSIONS: Our scoring system offers an easy-to-use evaluation of risk stratification for patients with stage B HF.2024年10月, Journal of the American Heart Association, 13(19) (19), e034793, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- The pathophysiology of variant transthyretin (TTR) amyloidosis (ATTRv) is associated with destabilizing mutations in the TTR tetramer. However, why TTR with a wild-type genetic sequence misfolds and aggregates in wild-type transthyretin amyloidosis (ATTRwt) is unknown. Here, we evaluate kinetic TTR stability with a newly developed ELISA system in combination with urea-induced protein denaturation. Compared with that in control patients, endogenous TTR in patients with wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) exhibited thermodynamic instability, indicating that circulating TTR instability may be associated with the pathogenesis of ATTRwt as well as ATTRv. Our findings provide new insight into the underlying mechanisms of ATTRwt.2024年09月, Scientific reports, 14(1) (1), 20508 - 20508, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- 2024年09月, CIRCULATION JOURNAL, 88(9) (9), 1502 - 1508, 英語研究論文（学術雑誌）
- BACKGROUND: Although low high-density lipoprotein cholesterol (HDL-C) levels are a common metabolic abnormality associated with insulin resistance, their role in cardiovascular risk stratification remains controversial. Recently, we developed a simple, high-throughput, cell-free assay system to evaluate the "cholesterol uptake capacity (CUC)" as a novel concept for HDL functionality. In this study, we assessed the CUC in patients with hypertriglyceridemia and diabetes mellitus. METHODS: The CUC was measured using cryopreserved serum samples from 285 patients who underwent coronary angiography or percutaneous coronary intervention between December 2014 and May 2019 at Kobe University Hospital. RESULTS: The CUC was significantly lower in diabetic patients (n = 125) than in nondiabetic patients (93.0 vs 100.7 arbitrary units (A.U.), P = 0.002). Patients with serum triglyceride (TG) levels >150 mg/dL (n = 94) also had a significantly lower CUC (91.8 vs 100.0 A.U., P = 0.004). Furthermore, the CUC showed a significant inverse correlation with TG, hemoglobin A1c (Hb A1c), homeostasis model assessment of insulin resistance (HOMA-IR), and body mass index (BMI). Finally, the HDL-C/Apolipoprotein A1 (ApoA1) ratio, calculated as a surrogate index of HDL particle size, was significantly positively correlated with the CUC (r2 = 0.49, P < 0.001), but inversely correlated with TG levels (r2 = -0.30, P < 0.001). CONCLUSIONS: The CUC decreased in patients with hypertriglyceridemia and diabetes mellitus, and HDL particle size was a factor defining the CUC and inversely correlated with TG levels, suggesting that impaired CUC in insulin-resistant states was partially due to the shift in HDL towards smaller particles. These findings provide a better understanding of the mechanisms underlying impaired HDL functionality.2024年04月, The journal of applied laboratory medicine, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- Stress has garnered significant attention as a prominent risk factor for inflammation-related diseases, particularly cardiovascular diseases (CVDs). However, the precise mechanisms underlying stress-driven CVDs remain elusive, thereby impeding the development of preventive and therapeutic strategies. To explore the correlation between plasma lipid metabolites and human depressive states, liquid chromatography-mass spectrometry (LC/MS) based analysis of plasma and the self-rating depression (SDS) scale questionnaire were employed. We also used a mouse model with restraint stress to study its effects on plasma lipid metabolites and stenotic vascular remodeling following carotid ligation. In vitro functional and mechanistic studies were performed using macrophages, endothelial cells, and neutrophil cells. We revealed a significant association between depressive state and reduced plasma levels of 4-oxoDHA, a specific omega-3 fatty acid metabolite biosynthesized by 5-lipoxygenase (LO), mainly in neutrophils. In mice, restraint stress decreased plasma 4-oxoDHA levels and exacerbated stenotic vascular remodeling, ameliorated by 4-oxoDHA supplementation. 4-oxoDHA enhanced Nrf2-HO-1 pathways, exerting anti-inflammatory effects on endothelial cells and macrophages. One of the stress hormones, noradrenaline, reduced 4-oxoDHA and the degraded 5-LO in neutrophils through the proteasome system, facilitated by dopamine D2-like receptor activation. Our study proposed circulating 4-oxoDHA levels as a stress biomarker and supplementation of 4-oxoDHA as a novel therapeutic approach for controlling stress-related vascular inflammation.2024年02月, Scientific reports, 14(1) (1), 4178 - 4178, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- BACKGROUND: Early detection and intervention for preclinical heart failure (HF) are crucial for restraining the potential increase in patients with HF. Thus, we designed and conducted a single-center retrospective cohort study to confirm the efficacy of B-type natriuretic peptide (BNP) for the early detection of preclinical HF in a primary care setting.Methods and Results: We investigated 477 patients with no prior diagnosis of HF who were under the care of general practitioners. These patients were categorized into 4 groups based on BNP concentrations: Category 1, 0 pg/mL≤BNP≤35 pg/mL; Category 2, 35 pg/mL2024年02月, Circulation journal : official journal of the Japanese Circulation Society, 英語, 国内誌[査読有り]研究論文（学術雑誌）
- BACKGROUND: Diabetes increases the risk of heart failure (HF). 3-Hydroxyisobutyric acid (3-HIB) is a muscle-derived metabolite reflecting systemic insulin resistance. In this study, we investigated the prognostic impact of 3-HIB in patients with chronic HF.Methods and Results: The KUNIUMI Registry chronic cohort is a community-based cohort study of chronic HF in Awaji Island, Japan. We analyzed the association between serum 3-HIB concentrations and adverse cardiovascular (CV) events in 784 patients from this cohort. Serum 3-HIB concentrations were significantly higher in patients with than without diabetes (P=0.0229) and were positively correlated with several metabolic parameters. According to Kaplan-Meier analysis, rates of CV death and HF hospitalization at 2 years were significantly higher among HF patients without diabetes in the high 3-HIB group (3-HIB concentrations above the median; i.e., >11.30 μmol/L) than in the low 3-HIB group (log-rank P=0.0151 and P=0.0344, respectively). Multivariable Cox proportional hazard models adjusted for established risk factors for HF revealed high 3-HIB as an independent predictor of CV death (hazard ratio [HR] 1.82; 95% confidence interval [CI] 1.16-2.85; P=0.009) and HF hospitalization (HR 1.72; 95% CI 1.17-2.53, P=0.006) in HF patients without diabetes, whereas no such trend was seen in subjects with diabetes. CONCLUSIONS: In a community cohort, circulating 3-HIB concentrations were associated with prognosis in chronic HF patients without diabetes.2023年12月, Circulation journal : official journal of the Japanese Circulation Society, 88(1) (1), 110 - 116, 英語, 国内誌[査読有り]研究論文（学術雑誌）
- Elevated circulating homocysteine (Hcy) is a well-known risk factor for cardiovascular diseases (CVDs), including coronary artery disease (CAD) and heart failure (HF). It remains unclear how Hcy and its derivatives relate to left ventricular (LV) diastolic function. The aim of the present study was to investigate the relationship between plasma Hcy-related metabolites and diastolic dysfunction (DD) in patients with heart disease (HD). A total of 62 HD patients with preserved LV ejection fraction (LVEF ≥ 50%) were enrolled. Plasma Hcy and its derivatives were measured by liquid chromatography‒mass spectrometry (LC-MS/MS). Spearman's correlation test and multiple linear regression models were used to analyze the associations between metabolite levels and LV diastolic function. The cystine/methionine (CySS/Met) ratio was positively correlated with LV diastolic function, which was defined from the ratio of mitral inflow E and mitral e' annular velocities (E/e') (Spearman's r = 0.43, p < 0.001). When the subjects were categorized into two groups by E/e', the high-E/e' group had a significantly higher CySS/Met ratio than the low-E/e' group (p = 0.002). Multiple linear regression models revealed that the CySS/Met ratio was independently associated with E/e' after adjustment for age, sex, body mass index (BMI), diabetes mellitus, hypertension, chronic kidney disease (CKD), hemoglobin, and lipid peroxide (LPO) {standardized β (95% CI); 0.14 (0.04-0.23); p = 0.005}. Hcy, CySS, and Met did not show a significant association with E/e' in the same models. A high plasma CySS/Met ratio reflected DD in patients with HD.2023年08月, Heart and vessels, 英語, 国内誌[査読有り]研究論文（学術雑誌）
- BACKGROUND: Recently, the function of high-density lipoprotein (HDL), rather than the HDL cholesterol (HDL-C) level, has been attracting more attention in risk prediction for coronary artery disease (CAD).Methods and Results: Patients with clinically diagnosed familial hypercholesterolemia (FH; n=108; male/female, 51/57) were assessed cross-sectionally. Serum cholesterol uptake capacity (CUC) levels were determined using our original cell-free assay. Linear regression was used to determine associations between CUC and clinical variables, including low-density lipoprotein cholesterol and the carotid plaque score. Multivariable logistic regression analysis was used to test factors associated with the presence of CAD. Among the 108 FH patients, 30 had CAD. CUC levels were significantly lower among patients with than without CAD (median [interquartile range] 119 [92-139] vs. 142 [121-165] arbitrary units [AU]; P=0.0004). In addition, CUC was significantly lower in patients with Achilles tendon thickness ≥9.0 mm than in those without Achilles tendon thickening (133 [110-157] vs. 142 [123-174] AU; P=0.047). Serum CUC levels were negatively correlated with the carotid plaque score (Spearman's r=0.37; P=0.00018). Serum CUC levels were significantly associated with CAD, after adjusting for other clinical variables (odds ratio=0.86, 95% CI=0.76-0.96, P=0.033), whereas HDL-C was not. CONCLUSIONS: HDL function, assessed by serum CUC level, rather than HDL-C level, adds risk stratification information among FH patients.2023年05月, Circulation journal : official journal of the Japanese Circulation Society, 87(6) (6), 806 - 812, 英語, 国内誌[査読有り]研究論文（学術雑誌）
- High-density lipoprotein (HDL) cholesterol efflux capacity (CEC), which is a conventional metric of HDL function, has been associated with coronary heart disease risk. However, the CEC assay requires cultured cells and takes several days to perform. We previously established a cell-free assay to evaluate cholesterol uptake capacity (CUC) as a novel measure of HDL functionality and demonstrated its utility in coronary risk stratification. To apply this concept clinically, we developed a rapid and sensitive assay system based on a chemiluminescent magnetic particle immunoassay. The system is fully automated, providing high reproducibility. Measurement of CUC in serum is completed within 20 min per sample without HDL isolation, a notably higher throughput than that of the conventional CEC assay. CUC decreased with myeloperoxidase-mediated oxidation of HDL or in the presence of N-ethylmaleimide, an inhibitor of lecithin: cholesterol acyltransferase (LCAT), whereas CUC was enhanced by the addition of recombinant LCAT. Furthermore, CUC correlated with CEC even after being normalized by ApoA1 concentration and was significantly associated with the requirement for revascularization due to the recurrence of coronary lesions. Therefore, our new assay system shows potential for the accurate measurement of CUC in serum and permits assessing cardiovascular health.2023年02月, Scientific reports, 13(1) (1), 1899 - 1899, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- AIMS: With the rapidly increasing ageing population, heart failure is an urgent challenge, particularly in developed countries. The study aimed to investigate the main aetiologies of chronic heart failure in a super-aged society. METHODS AND RESULTS: The KUNIUMI registry chronic cohort is a community-based, prospective, observational study of chronic heart failure in Awaji Island, Japan. Inhabitants of this island aged ≥65 years accounted for 36.3% of the population. In the present study, data from patients with symptomatic heart failure were extracted from the registry. A total of 1646 patients were enrolled from March 2019 to March 2021, accounting for ~1.3% of the inhabitants of Awaji Island. We analysed 852 patients with symptomatic heart failure. The mean age was high (78.7 ± 11.1 years), with 357 patients (41.9%) being female. The proportion of women increased significantly with advancing age and constituted more than half of the patients aged 85 years and older (P < 0.01). The prevalence of atrial fibrillation, and in particular long-standing persistent atrial fibrillation, increased at 70 years of age (P < 0.01). The proportion of patients with heart failure with preserved ejection fraction increased to ~60% when age was over 75 years. Although ischaemic heart disease accounted for 35.0% of chronic heart failure aetiologies, valvular heart disease was the most common cause of chronic heart failure (49.8%). The major types of valvular heart disease were mitral regurgitation and tricuspid regurgitation (27.2% and 21.7%, respectively), both of which increased significantly with age (P < 0.01). The incidence of aortic valve stenosis increased markedly over the age of 85 years (P < 0.01). Atrial functional mitral regurgitation increased with age and was the major cause of mitral regurgitation in patients aged >75 years. Patients with atrial functional mitral regurgitation had a higher prevalence of atrial fibrillation (especially long-standing persistent atrial fibrillation) and a larger left atrial volume index when compared with patients with other types of mitral regurgitation (P < 0.001, respectively). CONCLUSIONS: The KUNIUMI registry chronic cohort showed a change in heart failure aetiology to valvular heart disease in a super-aged society. Effective and comprehensive countermeasures are required to prepare for the rapid rise in heart failure incidence in a super-aged society.2022年09月, ESC heart failure, 10(1) (1), 100 - 110, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- Alterations in cardiac metabolism are strongly associated with the pathogenesis of heart failure (HF). We recently reported that glutamine-dependent anaplerosis, termed glutaminolysis, was activated by H2O2 stimulation in rat cardiomyocytes, which seemed to be an adaptive response by which cardiomyocytes survive acute stress. However, the molecular mechanisms and fundamental roles of glutaminolysis in the pathophysiology of the failing heart are still unknown. Here, we treated wild-type mice (C57BL/6J) and rat neonatal cardiomyocytes (RNCMs) and fibroblasts (RNCFs) with angiotensin II (ANG II) to induce pathological cardiac remodeling. Glutaminase 1 (GLS1), a rate-limiting glutaminolysis enzyme, was significantly increased in ANG II-induced mouse hearts, RNCMs and RNCFs. Unexpectedly, a GLS1 inhibitor attenuated ANG II-induced left ventricular hypertrophy and fibrosis in the mice, and gene knockdown and pharmacological perturbation of GLS1 suppressed hypertrophy and the proliferation of RNCMs and RNCFs, respectively. Using mass spectrometry (MS)-based stable isotope tracing with 13C-labeled glutamine, we observed glutamine metabolic flux in ANG II-treated RNCMs and RNCFs. The incorporation of 13C atoms into tricarboxylic acid (TCA) cycle intermediates and their derivatives was markedly enhanced in both cell types, indicating the activation of glutaminolysis in hypertrophied hearts. Notably, GLS1 inhibition reduced the production of glutamine-derived aspartate and citrate, which are required for the biosynthesis of nucleic acids and lipids, possibly contributing to the suppression of cardiac hypertrophy and fibrosis. The findings of the present study reveal that GLS1-mediated upregulation of glutaminolysis leads to maladaptive cardiac remodeling. Inhibition of this anaplerotic pathway could be a novel therapeutic approach for HF.NEW & NOTEWORTHY To our knowledge, this study is the first to demonstrate that increased GLS1 expression and subsequent activation of glutaminolysis are associated with exacerbation of cardiac hypertrophy and fibrosis. Inhibiting GLS1 antagonized the adverse cardiac remodeling in vitro and in vivo, partly due to reduction of glutamine-derived metabolites, which are necessary for cellular growth and proliferation. Increased glutamine utilization for anabolic reactions in cardiac cells may be related to the pathogenesis and development of HF.2022年05月, American journal of physiology. Heart and circulatory physiology, 322(5) (5), H749-H761, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- Springer Science and Business Media LLC, 2022年04月, Nature Cardiovascular Research, 1(4) (4), 322 - 333[査読有り]研究論文（学術雑誌）
- Recently we established a cell-free assay to evaluate "cholesterol uptake capacity (CUC)" as a novel concept for high-density lipoprotein (HDL) functionality and demonstrated the feasibility of CUC for coronary risk stratification, although its regulatory mechanism remains unclear. HDL fluidity affects cholesterol efflux, and trans fatty acids (TFA) reduce lipid membrane fluidity when incorporated into phospholipids (PL). This study aimed to clarify the effect of TFA in HDL-PL on CUC. Serum was collected from 264 patients after coronary angiography or percutaneous coronary intervention to measure CUC and elaidic acid levels in HDL-PL, and in vitro analysis using reconstituted HDL (rHDL) was used to determine the HDL-PL mechanism affecting CUC. CUC was positively associated with HDL-PL levels but negatively associated with the proportion of elaidic acid in HDL-PL (elaidic acid in HDL-PL/HDL-PL ratio). Increased elaidic acid-phosphatidylcholine (PC) content in rHDL exhibited no change in particle size or CUC compared to rHDL containing oleic acid in PC. Recombinant human lecithin-cholesterol acyltransferase (LCAT) enhanced CUC, and LCAT-dependent enhancement of CUC and LCAT-dependent cholesterol esterification were suppressed in rHDL containing elaidic acid in PC. Therefore, CUC is affected by HDL-PL concentration, HDL-PL acyl group composition, and LCAT-dependent cholesterol esterification. Elaidic acid precipitated an inhibition of cholesterol uptake and maturation of HDL; therefore, modulation of HDL-PL acyl groups could improve CUC.2021年09月, Nutrients, 13(9) (9), 英語, 国際誌[査読有り]研究論文（学術雑誌）
- BACKGROUND: Metabolic remodeling in cardiomyocytes is deeply associated with the pathogenesis of heart failure (HF). Glutaminolysis is an anaplerotic pathway that incorporates α-ketoglutarate (αKG) derived from glutamine into the tricarboxylic acid (TCA) cycle. It is well known that cancer cells depend on glutamine for their increased energy demand and proliferation; however, the physiological roles of glutamine metabolism in failing hearts remain unclear. OBJECTIVE: To investigate the regulatory mechanisms and biological effects of glutamine metabolism in oxidative stress-induced failing myocardium. METHODS AND RESULTS: The intracellular levels of glutamine, glutamate, and αKG were significantly decreased by H2O2 stimulation in rat neonatal cardiomyocytes (RNCMs). To better understand the metabolic flux in failing myocardium, we performed a stable isotope tracing study and found that glutaminolysis was upregulated in RNCMs under oxidative stress. Consistent with this, the enzymatic activity of glutaminase (Gls), which converts glutamine to glutamate, was augmented in RNCMs treated with H2O2. These findings suggest that glutamine anaplerosis is enhanced in cardiomyocytes under oxidative stress to compensate for the reduction of αKG. Furthermore, the inhibition of Gls reduced cardiac cell viability, ATP production, and glutathione (GSH) synthesis in RNCMs with H2O2 stimulation. Finally, we evaluated the effects of αKG on failing myocardium and observed that dimethyl α-ketoglutarate (DMKG) suppressed oxidative stress-induced cell death likely due to the enhancement of intracellular ATP and GSH levels. CONCLUSION: Our study demonstrates that under oxidative stress, glutaminolysis is upregulated to compensate for the loss of αKG and its replenishment into the TCA cycle, thereby exerting cardioprotective effects by maintaining ATP and GSH levels. Modulation of glutamine metabolism in failing hearts might provide a new therapeutic strategy for HF.2020年11月, Biochemical and biophysical research communications, 534, 687 - 693, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- Fibronectin-containing High-Density Lipoprotein is Associated with Cancer Cell Adhesion and Proliferation.A large amount of evidence suggests that high-density lipoprotein (HDL) has anti-atherosclerotic properties. HDL-cholesterol (HDL-C) has also been widely used as a marker of cardiovascular disease. Recently, it was reported that plasma HDL-C levels are inversely correlated with cancer risk. However, the relationship between HDL and cancer pathophysiology remains unknown. Here, we sought to investigate the effect of HDL on cancer progression. First, we focused on fibronectin-an essential extracellular matrix glycoprotein-as an HDL-associated protein and found that only 7.4% of subjects in this study had fibronectin in HDL isolated from their plasma. The fibronectin-containing HDL (FN-HDL) increased the phosphorylation of focal adhesion kinase (FAK) in HeLa cells compared to HDL without fibronectin, further inducing the phosphorylation in a dose-dependent manner. Second, we found that fibronectin-treated HDL activated the phosphorylation of FAK, and its upstream effector blocked the phosphorylation induced by FN-HDL. Finally, we demonstrated that FN-HDL promoted cancer cell proliferation and adhesion compared to HDL without fibronectin. Our study showed the possible mechanism by which FN-HDL enhanced cancer cell proliferation and adhesion via the FAK signaling pathway. Further investigation of the roles of HDL components in tumorigenesis might provide novel insight into cancer pathophysiology.2020年08月, The Kobe journal of medical sciences, 66(1) (1), E40-E48, 英語, 国内誌[査読有り]研究論文（学術雑誌）
- BACKGROUND: Smooth muscle cells (SMC) play a critical role in atherosclerosis. The Aryl hydrocarbon receptor (AHR) is an environment-sensing transcription factor that contributes to vascular development, and has been implicated in coronary artery disease risk. We hypothesized that AHR can affect atherosclerosis by regulating phenotypic modulation of SMC. METHODS: We combined RNA-sequencing, chromatin immunoprecipitation followed by sequencing, assay for transposase-accessible chromatin using sequencing, and in vitro assays in human coronary artery SMCs, with single-cell RNA-sequencing, histology, and RNAscope in an SMC-specific lineage-tracing Ahr knockout mouse model of atherosclerosis to better understand the role of AHR in vascular disease. RESULTS: Genomic studies coupled with functional assays in cultured human coronary artery SMCs revealed that AHR modulates the human coronary artery SMC phenotype and suppresses ossification in these cells. Lineage-tracing and activity-tracing studies in the mouse aortic sinus showed that the Ahr pathway is active in modulated SMCs in the atherosclerotic lesion cap. Furthermore, single-cell RNA-sequencing studies of the SMC-specific Ahr knockout mice showed a significant increase in the proportion of modulated SMCs expressing chondrocyte markers such as Col2a1 and Alpl, which localized to the lesion neointima. These cells, which we term "chondromyocytes," were also identified in the neointima of human coronary arteries. In histological analyses, these changes manifested as larger lesion size, increased lineage-traced SMC participation in the lesion, decreased lineage-traced SMCs in the lesion cap, and increased alkaline phosphatase activity in lesions in the Ahr knockout in comparison with wild-type mice. We propose that AHR is likely protective based on these data and inference from human genetic analyses. CONCLUSIONS: Overall, we conclude that AHR promotes the maintenance of lesion cap integrity and diminishes the disease-related SMC-to-chondromyocyte transition in atherosclerotic tissues.2020年08月, Circulation, 142(6) (6), 575 - 590, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- BACKGROUND: Cholesterol efflux from atherosclerotic lesion is a key function of high-density lipoprotein (HDL). Recently, we established a simple, high-throughput, cell-free assay to evaluate the capacity of HDL to accept additional cholesterol, which is herein referred to as "cholesterol uptake capacity (CUC)". OBJECTIVE: To clarify the cross-sectional relationship between CUC and coronary plaque properties. METHODS: We enrolled 135 patients to measure CUC and assess the morphological features of angiographic stenosis by optical coherence tomography (OCT). We estimated the extent of the lipid-rich plaque by multiplying the mean lipid arc by lipid length (lipid index). The extent of the OCT-detected macrophage accumulation in the target plaque was semi-quantitatively estimated using a grading system. RESULTS: Lipid-rich plaque lesions were identified in 125 patients (92.6%). CUC was inversely associated with the lipid index (R = -0.348, P < 0.0001). In addition, CUC was also inversely associated with macrophage score (R = -0.327, P < 0.0001). Conversely, neither circulating levels of HDL cholesterol nor apoA1 showed a similar relationship. CONCLUSIONS: We demonstrated that CUC was inversely related to lipid-rich plaque burden and the extent of macrophage accumulation, suggesting that CUC could be useful for cardiovascular risk stratification.2020年04月, Clinica chimica acta; international journal of clinical chemistry, 503, 136 - 144, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- RATIONALE: The gene encoding TCF21 (transcription factor 21) has been linked to coronary artery disease risk by human genome-wide association studies in multiple racial ethnic groups. In murine models, Tcf21 is required for phenotypic modulation of smooth muscle cells (SMCs) in atherosclerotic tissues and promotes a fibroblast phenotype in these cells. In humans, TCF21 expression inhibits risk for coronary artery disease. The molecular mechanism by which TCF21 regulates SMC phenotype is not known. OBJECTIVE: To better understand how TCF21 affects the SMC phenotype, we sought to investigate the possible mechanisms by which it regulates the lineage determining MYOCD (myocardin)-SRF (serum response factor) pathway. METHODS AND RESULTS: Modulation of TCF21 expression in human coronary artery SMC revealed that TCF21 suppresses a broad range of SMC markers, as well as key SMC transcription factors MYOCD and SRF, at the RNA and protein level. We conducted chromatin immunoprecipitation-sequencing to map SRF-binding sites in human coronary artery SMC, showing that binding is colocalized in the genome with TCF21, including at a novel enhancer in the SRF gene, and at the MYOCD gene promoter. In vitro genome editing indicated that the SRF enhancer CArG box regulates transcription of the SRF gene, and mutation of this conserved motif in the orthologous mouse SRF enhancer revealed decreased SRF expression in aorta and heart tissues. Direct TCF21 binding and transcriptional inhibition at colocalized sites were established by reporter gene transfection assays. Chromatin immunoprecipitation and protein coimmunoprecipitation studies provided evidence that TCF21 blocks MYOCD and SRF association by direct TCF21-MYOCD interaction. CONCLUSIONS: These data indicate that TCF21 antagonizes the MYOCD-SRF pathway through multiple mechanisms, further establishing a role for this coronary artery disease-associated gene in fundamental SMC processes and indicating the importance of smooth muscle response to vascular stress and phenotypic modulation of this cell type in coronary artery disease risk.2020年02月, Circulation research, 126(4) (4), 517 - 529, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- 2019年10月, Journal of clinical lipidology, 13(5) (5), 839 - 846, 英語Serum concentration of full-length- and carboxy-terminal fragments of endothelial lipase predicts future cardiovascular risks in patients with coronary artery disease[査読有り]研究論文（学術雑誌）
- In response to various stimuli, vascular smooth muscle cells (SMCs) can de-differentiate, proliferate and migrate in a process known as phenotypic modulation. However, the phenotype of modulated SMCs in vivo during atherosclerosis and the influence of this process on coronary artery disease (CAD) risk have not been clearly established. Using single-cell RNA sequencing, we comprehensively characterized the transcriptomic phenotype of modulated SMCs in vivo in atherosclerotic lesions of both mouse and human arteries and found that these cells transform into unique fibroblast-like cells, termed 'fibromyocytes', rather than into a classical macrophage phenotype. SMC-specific knockout of TCF21-a causal CAD gene-markedly inhibited SMC phenotypic modulation in mice, leading to the presence of fewer fibromyocytes within lesions as well as within the protective fibrous cap of the lesions. Moreover, TCF21 expression was strongly associated with SMC phenotypic modulation in diseased human coronary arteries, and higher levels of TCF21 expression were associated with decreased CAD risk in human CAD-relevant tissues. These results establish a protective role for both TCF21 and SMC phenotypic modulation in this disease.2019年08月, Nature medicine, 25(8) (8), 1280 - 1289, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- BACKGROUND: Genome-wide association studies have identified over 160 loci that are associated with coronary artery disease. As with other complex human diseases, risk in coronary disease loci is determined primarily by altered expression of the causal gene, due to variation in binding of transcription factors and chromatin-modifying proteins that directly regulate the transcriptional apparatus. We have previously identified a coronary disease network downstream of the disease-associated transcription factor TCF21, and in work reported here extends these studies to investigate the mechanisms by which it interacts with the AP-1 transcription complex to regulate local epigenetic effects in these downstream coronary disease loci. METHODS: Genomic studies, including chromatin immunoprecipitation sequencing, RNA sequencing, and protein-protein interaction studies, were performed in human coronary artery smooth muscle cells. RESULTS: We show here that TCF21 and JUN regulate expression of two presumptive causal coronary disease genes, SMAD3 and CDKN2B-AS1, in part by interactions with histone deacetylases and acetyltransferases. Genome-wide TCF21 and JUN binding is jointly localized and particularly enriched in coronary disease loci where they broadly modulate H3K27Ac and chromatin state changes linked to disease-related processes in vascular cells. Heterozygosity at coronary disease causal variation, or genome editing of these variants, is associated with decreased binding of both JUN and TCF21 and loss of expression in cis, supporting a transcriptional mechanism for disease risk. CONCLUSIONS: These data show that the known chromatin remodeling and pioneer functions of AP-1 are a pervasive aspect of epigenetic control of transcription, and thus, the risk in coronary disease-associated loci, and that interaction of AP-1 with TCF21 to control epigenetic features, contributes to the genetic risk in loci where they co-localize.2019年05月, Genome medicine, 11(1) (1), 23 - 23, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- BACKGROUND: Trans-fatty acid (TFA) intake increases the risk of coronary artery disease (CAD). Our previous cross-sectional survey showed that middle-aged patients with CAD in Japan have elevated serum TFA. In this study, we longitudinally investigated whether elevated TFA is a risk factor in the secondary prevention of CAD for the same-age patients. Methods and Results: A total of 112 patients (age, 21-66 years) who underwent percutaneous coronary intervention were followed up for up to 2 years. Serum elaidic acid was measured using gas chromatography/mass spectrometry as a marker of TFA intake and divided into quartiles. The primary endpoint was ischemia-driven target lesion revascularization (TLR). The hazard ratio (HR) for TLR increased significantly with higher serum elaidic acid (P<0.01). The significant positive trend remained unchanged after adjusting for conventional lipid profile and bare-metal stent usage. In contrast, although triglycerides and low-density lipoprotein cholesterol were positively correlated with elaidic acid, they were not associated with TLR. On multivariable Cox proportional hazard analysis, elevated elaidic acid was independently associated with TLR risk after adjusting for conventional coronary risks (HR, 10.7, P<0.01). CONCLUSIONS: Elevated elaidic acid is associated with higher TLR rate in middle-aged patients with CAD, suggesting that excessive TFA intake is becoming a serious health problem in Japan.2019年04月, Circulation journal : official journal of the Japanese Circulation Society, 83(5) (5), 1032 - 1038, 英語, 国内誌[査読有り]研究論文（学術雑誌）
- High-density lipoprotein cholesterol (HDL-C) has been identified as a powerful independent negative predictor of cardiovascular disease. The beneficial effect of HDL is largely attributable to its key role in reverse cholesterol transport, whereby excess cholesterol in the peripheral tissues is transported to the liver, reducing the atherosclerotic burden. However, mounting evidence indicates that HDL also has pleiotropic properties, such as anti-inflammatory, anti-oxidative, and vasodilatory properties, which may contribute in reducing the incidence of heart failure. Actually, previous data from clinical and experimental studies have suggested that HDL exerts cardioprotective effects irrespective of the presence/absence of coronary artery disease. This review summarizes the currently available evidence regarding beneficial effects of HDL on the heart beyond its anti-atherogenic property. Understanding the mechanisms of cardiac protection by HDL will provide new insight into the underlying mechanism and therapeutic strategy for heart failure.2018年10月, Journal of atherosclerosis and thrombosis, 25(10) (10), 985 - 993, 英語, 国内誌[査読有り]研究論文（学術雑誌）
- Although numerous genetic loci have been associated with coronary artery disease (CAD) with genome wide association studies, efforts are needed to identify the causal genes in these loci and link them into fundamental signaling pathways. Recent studies have investigated the disease mechanism of CAD associated gene SMAD3, a central transcription factor (TF) in the TGFβ pathway, investigating its role in smooth muscle biology. In vitro studies in human coronary artery smooth muscle cells (HCASMC) revealed that SMAD3 modulates cellular phenotype, promoting expression of differentiation marker genes while inhibiting proliferation. RNA sequencing and chromatin immunoprecipitation sequencing studies in HCASMC identified downstream genes that reside in pathways which mediate vascular development and atherosclerosis processes in this cell type. HCASMC phenotype, and gene expression patterns promoted by SMAD3 were noted to have opposing direction of effect compared to another CAD associated TF, TCF21. At sites of SMAD3 and TCF21 colocalization on DNA, SMAD3 binding was inversely correlated with TCF21 binding, due in part to TCF21 locally blocking chromatin accessibility at the SMAD3 binding site. Further, TCF21 was able to directly inhibit SMAD3 activation of gene expression in transfection reporter gene studies. In contrast to TCF21 which is protective toward CAD, SMAD3 expression in HCASMC was shown to be directly correlated with disease risk. We propose that the pro-differentiation action of SMAD3 inhibits dedifferentiation that is required for HCASMC to expand and stabilize disease plaque as they respond to vascular stresses, counteracting the protective dedifferentiating activity of TCF21 and promoting disease risk.2018年10月, PLoS genetics, 14(10) (10), e1007681, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- BACKGROUND: Glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1), a glycosylphosphatidylinositol (GPI)-anchored protein of capillary endothelial cells, transports lipoprotein lipase to the capillary lumen and is essential for the lipolytic processing of triglyceride-rich lipoproteins. OBJECTIVE: Because some GPI-anchored proteins have been detected in plasma, we tested whether GPIHBP1 is present in human blood and whether GPIHBP1 deficiency or a history of cardiovascular disease affected GPIHBP1 circulating levels. METHODS: We developed 2 monoclonal antibodies against GPIHBP1 and used the antibodies to establish a sandwich enzyme-linked immunosorbent assay (ELISA) to measure GPIHBP1 levels in human blood. RESULTS: The GPIHBP1 ELISA was linear in the 8 to 500 pg/mL range and allowed the quantification of GPIHBP1 in serum and in pre- and post-heparin plasma (including lipemic samples). GPIHBP1 was undetectable in the plasma of subjects with null mutations in GPIHBP1. Serum GPIHBP1 median levels were 849 pg/mL (range: 740-1014) in healthy volunteers (n = 28) and 1087 pg/mL (range: 877-1371) in patients with a history of cardiovascular or metabolic disease (n = 415). There was an extremely small inverse correlation between GPIHBP1 and triglyceride levels (r = 0.109; P < .0275). GPIHBP1 levels tended to be slightly higher in patients who had a major cardiovascular event after revascularization. CONCLUSION: We developed an ELISA for quantifying GPIHBP1 in human blood. This assay will be useful to identify patients with GPIHBP1 deficiency and patients with GPIHBP1 autoantibodies. The potential of plasma GPIHBP1 as a biomarker for metabolic or cardiovascular disease is yet questionable but needs additional testing.2018年02月, Journal of clinical lipidology, 12(1) (1), 203 - 210, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- BACKGROUND: It has previously been reported that oral administration of purified eicosapentaenoic acid (EPA) generates EPA-rich high-density lipoprotein (HDL) particles with a variety of anti-inflammatory properties. In this study, the mechanism underlying the anti-atherogenic effects of EPA-rich HDL using reconstituted HDL (rHDL) was investigated.Methods and Results:rHDL was generated by the sodium cholate dialysis method, using apolipoprotein A-1 protein, cholesterol, and various concentrations of EPA-phosphatidylcholine (PC) or egg-PC. Increased EPA-PC contents in rHDL resulted in decreased particle size. Next, the effects of rHDL containing various amounts (0-100% of total PC) of EPA-PC on vascular cell adhesion molecule-1 (VCAM-1) expression in human umbilical vein endothelial cells (HUVECs) was examined. Cytokine-stimulated VCAM-1 expression was inhibited in a dose-dependent manner based on the amount of EPA-PC in rHDL. Surprisingly, the incubation of HUVECs with EPA-rich rHDL resulted in the production of resolvin E3 (RvE3), an anti-inflammatory metabolite derived from EPA. Incubation with EPA-PC alone did not adequately induce RvE3 production, suggesting that RvE3 production requires an endothelial cell-HDL interaction. The increased anti-inflammatory effects of EPA-rich HDL may be explained by EPA itself and RvE3 production. Furthermore, the increase in EPA-PC content enhanced cholesterol efflux. CONCLUSIONS: The EPA-enriched HDL particles exhibit cardioprotective properties via the production of anti-inflammatory lipid metabolites and the increase in cholesterol efflux.2018年01月, Circulation journal : official journal of the Japanese Circulation Society, 82(2) (2), 596 - 601, 英語, 国内誌[査読有り]研究論文（学術雑誌）
- High-density lipoprotein (HDL) interacts with various cells, particularly macrophages, in functional cell-HDL interactions. Here, we found that HDL protein quality and lipid quality play critical roles in HDL functions. HDL fractions from healthy volunteers (HDLHealthy) and patients with recurrent coronary atherosclerotic disease (HDLCAD) were prepared. To analyse functional HDL-macrophage interactions, macrophages were co-incubated with each HDL, and lipid mediator production was assessed by liquid chromatography/mass spectrometry-based metabololipidomics. HDLHealthy treatment attenuated the pro-inflammatory lipid mediator production, particularly that of leukotriene (LT) B4, and this treatment enhanced lipoxin (LX) B4 and resolvin (Rv) E2 production. HDLHealthy treatment enhanced the proteasome-mediated degradation of the LTB4-producing enzyme 5-lipoxygenase (LO) in activated macrophages; however, HDLCAD did not show these anti-inflammatory effects. HDLHealthy was engulfed by macrophages via clathrin-mediated endocytosis, which was a critical step in 5-LO/LTB4 regulation. We also found that HDLCAD showed higher levels of the LTB4-producing enzymes and thus promoted LTB4 production from HDLCAD. In addition, LTB4 attenuated HDL endocytosis, HDL-mediated 5-LO degradation in macrophages, and HDL-derived augmentation of macrophage phagocytosis. These results indicated that local LTB4 produced de novo from HDLCAD regulates HDL-macrophage functional interactions and plays critical roles in dysfunctional, inflammatory HDL characteristics.2017年10月, Scientific reports, 7(1) (1), 12989 - 12989, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- Low levels of plasma high-density lipoprotein (HDL) cholesterol are associated with an increased risk of heart failure, regardless of the presence or absence of coronary artery disease. However, the direct effects of HDL on failing myocardium have not been fully elucidated. We found that HDL treatment resulted in improved cell viability in H9c2 cardiomyocytes under oxidative stress. This cardioprotective effect of HDL was regulated via the phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway. mTOR signaling promotes cell survival through the inactivation of the BCL2-associated agonist of cell death via phosphorylation of ribosomal protein S6 kinase. Modulation of cardiac PI3K/mTOR signaling by HDL could represent a novel therapeutic strategy for heart failure.2017年09月, FEBS open bio, 7(9) (9), 1402 - 1409, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- A previous report showed that the consumption of glutathione through oxidative stress activates the glutathione synthetic pathway, which is accompanied by production of ophthalmic acid from 2-aminobutyric acid (2-AB). We conducted a comprehensive quantification of serum metabolites using gas chromatography-mass spectrometry in patients with atrial septal defect to find clues for understanding myocardial metabolic regulation, and demonstrated that circulating 2-AB levels reflect hemodynamic changes. However, the metabolism and pathophysiological role of 2-AB remains unclear. We revealed that 2-AB is generated by an amino group transfer reaction to 2-oxobutyric acid, a byproduct of cysteine biosynthesis from cystathionine. Because cysteine is a rate-limiting substrate for glutathione synthesis, we hypothesized that 2-AB reflects glutathione compensation against oxidative stress. A murine cardiomyopathy model induced by doxorubicin supported our hypothesis, i.e., increased reactive oxygen species are accompanied by 2-AB accumulation and compensatory maintenance of myocardial glutathione levels. Intriguingly, we also found that 2-AB increases intracellular glutathione levels by activating AMPK and exerts protective effects against oxidative stress. Finally, we demonstrated that oral administration of 2-AB efficiently raises both circulating and myocardial glutathione levels and protects against doxorubicin-induced cardiomyopathy in mice. This is the first study to demonstrate that 2-AB modulates glutathione homeostasis in the myocardium.2016年11月, Scientific reports, 6, 36749 - 36749, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- Recent studies have shown that the ketone body β-hydroxybutyrate (βOHB) acts not only as a carrier of energy but also as a signaling molecule that has a role in diverse cellular functions. Circulating levels of ketone bodies have been previously reported to be increased in patients with congestive heart failure (HF). In this study, we investigated regulatory mechanism and pathophysiological role of βOHB in HF. First, we revealed that βOHB level was elevated in failing hearts, but not in blood, using pressure-overloaded mice. We also measured cellular βOHB levels in both cardiomyocytes and non-cardiomyocytes stimulated with or without H2O2 and revealed that increased myocardial βOHB was derived from cardiomyocytes but not non-cardiomyocytes under pathological states. Next, we sought to elucidate the mechanisms of myocardial βOHB elevation and its implication under pathological states. The gene and protein expression levels of CoA transferase (SCOT), a key enzyme involved in ketone body oxidation, was decreased in failing hearts. In cardiomyocytes, H2O2 stimulation caused βOHB accumulation concomitantly with SCOT downregulation, implying that the accumulation of myocardial βOHB occurs because of the decline in its utilization. Finally, we checked the effects of βOHB on cardiomyocytes under oxidative stress. We found that βOHB induced FOXO3a, an oxidative stress resistance gene, and its target enzyme, SOD2 and catalase. Consequently, βOHB attenuated reactive oxygen species production and alleviated apoptosis induced by oxidative stress. It has been reported that hyperadrenergic state in HF boost lipolysis and result in elevation of circulating free fatty acids, which can lead hepatic ketogenesis for energy metabolism alteration. The present findings suggest that the accumulation of βOHB also occurs as a compensatory response against oxidative stress in failing hearts.2016年07月, Biochemical and biophysical research communications, 475(4) (4), 322 - 8, 英語, 国際誌[査読有り]研究論文（学術雑誌）
- OBJECTIVE: It has been reported that high-density lipoprotein (HDL) loses anti-inflammatory function and promotes atherosclerosis under pathological conditions. However, no pharmacological therapy to improve HDL function is currently available. We aimed to evaluate the effect of oral administration of eicosapentaenoic acid (EPA) on HDL function. METHODS: Japanese patients with dyslipidemia were treated with EPA (1800 mg/day, 4 weeks), and anti-inflammatory functions of HDL were assessed utilizing in vitro cell-based assays. RESULTS: The EPA treatment did not change serum cholesterol and triglyceride levels, but it significantly increased EPA concentrations in the serum and HDL fraction. The EPA/arachidonic acid ratio in the HDL was in proportion to that in the serum, suggesting that the orally administered EPA was efficiently incorporated into the HDL particles. The HDL after EPA treatment showed significantly increased activity of anti-oxidative enzyme, paraoxonase-1. In addition, the EPA-rich HDL significantly improved endothelial cell migration, and markedly inhibited cytokine-induced expression of vascular cell adhesion molecule-1, in human umbilical vein endothelial cells, compared to HDL before the EPA treatment. Moreover, the EPA-rich HDL augmented cholesterol efflux capacity from macrophages. CONCLUSION: Oral administration of EPA regenerated anti-oxidative and anti-inflammatory functions of HDL, and promoted cholesterol efflux from macrophages. Therefore, EPA may transform "dysfunctional HDL" to "functional", in patients with coronary risk factors.2014年12月, Atherosclerosis, 237(2) (2), 577 - 83, 英語, 国際誌[査読有り]研究論文（学術雑誌）
■ 共同研究・競争的資金等の研究課題
- 日本学術振興会, 科学研究費助成事業, 基盤研究(C), 神戸大学, 2025年04月01日 - 2028年03月31日時計遺伝子を標的とした心不全の新規検査法、治療法の開拓
- 日本学術振興会, 科学研究費助成事業, 基盤研究(C), 神戸大学, 2024年04月01日 - 2027年03月31日de novo 脂肪酸合成経路に着目した心臓線維化の分子機序解明と治療法の確立
- 日本学術振興会, 科学研究費助成事業, 基盤研究(C), 神戸大学, 2024年04月01日 - 2027年03月31日超高齢社会における健康寿命延伸に寄与する脂質代謝物の探索的研究
- 日本学術振興会, 科学研究費助成事業, 若手研究, 神戸大学, 2023年04月01日 - 2026年03月31日野生型トランスサイレチン型心アミロイドーシスの簡易診断法の確立
- 日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 神戸大学, 2022年04月 - 2025年03月, 研究分担者分岐鎖アミノ酸代謝に注目した糖尿病性心筋症の病態解明と治療応用
- 日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 神戸大学, 2021年04月 - 2024年03月, 研究分担者心不全におけるグルタミン代謝制御機構の解明と新規治療戦略の構築1) 不全心筋におけるグルタミン代謝制御機構を解明する 当初予定していた大動脈縮窄術による心不全モデルの実験系の結果にバラつきが大きく、動物モデルとしての安定した結果が得られなかったため、代替的にAngiotensinⅡの持続皮下投与による心肥大モデルを用いた検討を行った。AngiotensinⅡを投与したマウスの心臓組織ではグルタミン分解において、グルタミンからグルタミン酸への変換を触媒する酵素であるグルタミナーゼ１（GLS1）の発現がAngiotensinⅡ群で有意に増加していた。また、心肥大を心重量/体重比(mg/g)および心重量/脛骨長比(mg/mm)で評価したところ、いずれもAngiotensinⅡで有意に増加し、GLS1阻害薬（BPTES）投与によって抑制された。さらに、心臓切片における線維化面積はAngiotensinⅡ投与群で顕著に増加し、AngiotensinⅡ＋BPTES投与群では抑制された。同様に、線維化マーカーであるCol1a1の遺伝子発現も、AngiotensinⅡ投与群で増加し、AngiotensinⅡ＋BPTES投与群では、有意に抑制された。 不全心筋におけるグルタミン代謝の役割を解明するため、 [U-13C5]-グルタミンを用いて、ラット初代培養心筋細胞の細胞内の標識代謝物の追跡を行った（stable isotope tracing）。AngiotensinⅡによる刺激でグルタミン由来の代謝物は増加し、阻害薬・siRNAによるGLS1の阻害によってその増加は抑制された。 以上の実験より心臓リモデリングを来した心臓ではグルタミン分解が亢進し、その阻害がリモデリングの抑制に繋がることを証明した。
- 日本学術振興会, 科学研究費助成事業 若手研究, 若手研究, 神戸大学, 2020年04月 - 2023年03月, 研究代表者糖尿病性心筋症における早期診断バイオマーカーと治療法の確立1) 糖尿病性心筋症におけるグルタミノリシスの制御機構の解明 インスリン抵抗性を有する心臓におけるグルタミン代謝を評価するにあたり、グルタミンをグルタミン酸へ変換する酵素であるグルタミナーゼに注目した。グルタミナーゼの発現・酵素活性については2型糖尿病モデル動物として用いているAdipo-PDK1 KOマウスと野生型の間に有意な差は無かった。また、実際のグルタミン代謝を評価するため、安定同位体ラベルされたグルタミンをマウスに投与し、心臓組織におけるグルタミン由来の代謝物の定量を行った（stable isotope tracing）。外因性に投与されたグルタミンは心臓組織中のグルタミン総量の10％にも満たないという結果であり、KO群の心臓組織におけるグルタミン、グルタミン酸の増加のメカニズムは解明できていない。一方、Adipo-PDK1KOマウスに離乳後より6週間、グルタミナーゼ阻害薬（BPTES）を腹腔内投与したところ、統計上の有意差は認めないものの、心重量/脛骨長比はBPTES投与群で低下する傾向を示した。糖尿病性心筋症における心肥大にグルタミン代謝が何らかの影響を及ぼすことを示唆する結果であると考えられ、さらなる研究が必要である。