Keita Odashiro

Functional variation in LGALS2 confers risk of myocardial infarction and regulates lymphotoxin-|[alpha]| secretion in vitro

Myocardial infarction (MI) has become one of the leading causes of death in the world. Its pathogenesis includes chronic formation of plaque inside the vessel wall of the coronary artery and acute rupture of the artery, implicating a number of inflammation-mediating molecules, such as the cytokine lymphotoxin-α (LTA). Functional variations in LTA are associated with susceptibility to MI. Here we show that LTA protein binds to galectin-2, a member of the galactose-binding lectin family. Our case–control association study in a Japanese population showed that a single nucleotide polymorphism in LGALS2 encoding galectin-2 is significantly associated with susceptibility to MI. This genetic substitution affects the transcriptional level of galectin-2 in vitro, potentially leading to altered secretion of LTA, which would then affect the degree of inflammation; however, its relevance to other populations remains to be clarified. Smooth muscle cells and macrophages in the human atherosclerotic lesions expressed both galectin-2 and LTA. Our findings thus suggest a link between the LTA cascade and the pathogenesis of MI.

Long-Term Clinical and Angiographic Follow-Up After Coronary Stent Placement in Native Coronary Arteries

Background—Although coronary stents have been proved effective in reducing clinical cardiac events for up to 3 to 5 years, longer term clinical and angiographic outcomes have not yet been fully clarified. Methods and Results—To evaluate longer term (7 to 11 years) outcome, clinical and angiographic follow-up information was analyzed in 405 patients with successful stenting in native coronary arteries. Primary or secondary stabilization, which was defined as freedom from death, coronary artery bypass grafting, and target lesion-percutaneous coronary intervention (TL-PCI) during the 14 months after the initial procedure or after the last TL-PCI, was achieved in 373 patients (92%) overall. Only 7 patients (1.7%) underwent TL-PCI more than twice. After the initial 14-month period, freedom from TL-PCI reached a plateau at 84.9% to 80.7% over 1 to 8 years. However, quantitative angiographic analysis in 179 lesions revealed a triphasic luminal response characterized by an early restenosis phase until 6 months, an intermediate-term regression phase from 6 months to 3 years, and a late renarrowing phase beyond 4 years. Minimal luminal diameter in 131 patients with complete serial data were 2.62±0.4 mm immediately after stenting, 2.0±0.49 mm at 6 months, 2.19±0.49 mm at 3 years, and 1.85±0.56 mm beyond 4 years (P <0.0001). Conclusions—The efficacy and safety of coronary stenting seemed to be clinically sustained at 7 to 11 years of follow-up. However, late luminal renarrowing beyond 4 years was common, which demonstrates the need for further follow-up.

SNPs in BRAP associated with risk of myocardial infarction in Asian populations

Myocardial infarction is a common disease and among the leading causes of death in the world. We previously reported association of variants in LGALS2, encoding galectin-2, with myocardial infarction susceptibility in a case-control association study in a Japanese population. Here we identify BRAP (BRCA1-associated protein) as a galectin-2–binding protein. We report an association of SNPs in BRAP with myocardial infarction risk in a large Japanese cohort (P = 3.0 × 10−18, OR = 1.48, 2,475 cases and 2,778 controls), with replication in additional Japanese and Taiwanese cohorts (P = 4.4 × 10−6, 862 cases and 1,113 controls and P = 4.7 × 10−3, 349 cases and 994 controls, respectively). BRAP expression was observed in smooth muscle cells (SMCs) and macrophages in human atherosclerotic lesions. BRAP knockdown by siRNA using cultured coronary endothelial cells suppressed activation of NF-κB, a central mediator of inflammation.

Contribution of bone marrow-derived hematopoietic stem/progenitor cells to the generation of donor-marker⁺ cardiomyocytes in vivo.

Background Definite identification of the cell types and the mechanism relevant to cardiomyogenesis is essential for effective cardiac regenerative medicine. We aimed to identify the cell populations that can generate cardiomyocytes and to clarify whether generation of donor-marker+ cardiomyocytes requires cell fusion between BM-derived cells and recipient cardiomyocytes. Methodology/Principal Findings Purified BM stem/progenitor cells from green fluorescence protein (GFP) mice were transplanted into C57BL/6 mice or cyan fluorescence protein (CFP)-transgenic mice. Purified human hematopoietic stem cells (HSCs) from cord blood were transplanted into immune-compromised NOD/SCID/IL2rγnull mice. GFP+ cells in the cardiac tissue were analyzed for the antigenecity of a cardiomyocyte by confocal microscopy following immunofluorescence staining. GFP+ donor-derived cells, GFP+CFP+ fused cells, and CFP+ recipient-derived cells were distinguished by linear unmixing analysis. Hearts of xenogeneic recipients were evaluated for the expression of human cardiomyocyte genes by real-time quantitative polymerase chain reaction. In C57BL/6 recipients, Lin−/lowCD45+ hematopoietic cells generated greater number of GFP+ cardiomyocytes than Lin−/lowCD45− mesenchymal cells (37.0+/−23.9 vs 0.00+/−0.00 GFP+ cardiomyocytes per a recipient, P = 0.0095). The number of transplanted purified HSCs (Lin−/lowSca-1+ or Lin−Sca-1+c-Kit+ or CD34−Lin−Sca-1+c-Kit+) showed correlation to the number of GFP+ cardiomyocytes (P<0.05 in each cell fraction), and the incidence of GFP+ cardiomyocytes per injected cell dose was greatest in CD34−Lin−Sca-1+c-Kit+ recipients. Of the hematopoietic progenitors, total myeloid progenitors generated greater number of GFP+ cardiomyocytes than common lymphoid progenitors (12.8+/−10.7 vs 0.67+/−1.00 GFP+ cardiomyocytes per a recipient, P = 0.0021). In CFP recipients, all GFP+ cardiomyocytes examined coexpressed CFP. Human troponin C and myosin heavy chain 6 transcripts were detected in the cardiac tissue of some of the xenogeneic recipients. Conclusions/Significance Our results indicate that HSCs resulted in the generation of cardiomyocytes via myeloid intermediates by fusion-dependent mechanism. The use of myeloid derivatives as donor cells could potentially allow more effective cell-based therapy for cardiac repair.

A functional SNP in ITIH3 is associated with susceptibility to myocardial infarction

AbstractMyocardial infarction (MI) results from complex interactions of multiple genetic and environmental factors. To disclose genetic backgrounds of MI, we performed a large-scale, case-control association study using 52,608 gene-based single-nucleotide polymorphism (SNP) markers, and identified a candidate SNP located on chromosome 3p21.2-p21.1. Subsequent linkage-disequilibrium mapping indicated very significant association between MI and a SNP in exon 2 of the inter-alpha (globulin) inhibitor 3 gene (ITIH3; χ2= 24.88, P= 6.1 × 10−7, 3,353 affected individuals versus 3,807 controls). In vitro functional analyses showed that this SNP enhanced the transcriptional level of the ITIH3 gene. Furthermore, we found expression of the ITIH3 protein in the vascular smooth muscle cells and macrophages in the human atherosclerotic lesions, suggesting ITIH3 SNP to be a novel genetic risk factor of MI.

Relationship between atrial fibrillation and gastroesophageal reflux disease: a multicenter questionnaire survey.

Objectives: The relationship between atrial fibrillation (AF) and gastroesophageal reflux disease (GERD) remains controversial, and investigations into this relationship have been based on small series. This multicenter survey evaluated the relationship between these diseases. Methods: The study enrolled 188 consecutive subjects (110 males and 78 females, mean age 60.4 ± 0.9 years) treated as outpatients. Patients were classified by the frequency scale for symptoms of GERD (F-scale) after obtaining informed consent for screening for GERD. Scores on this questionnaire were correlated to baseline characteristics obtained from medical records. The cutoff value for a diagnosis of GERD was set at 8.0 points. Results: Total scores on the F-scale were significantly greater in female subjects (p = 0.004) and in patients with AF (p = 0.019) compared to the other subjects. Univariate and multivariate analysis of the prevalence of GERD demonstrated that GERD was not related to gender, hypertension, dyslipidemia or coronary artery disease and that AF alone showed a significant (p < 0.001) correlation with GERD. Conclusions: This multicenter questionnaire survey demonstrated that among traditional cardiovascular risk factors, AF was an independent risk factor for GERD. A large cohort study to assess the potential relationship between GERD and AF is warranted.

Case of paroxysmal atrial fibrillation improved after the administration of proton pump inhibitor for associated reflux esophagitis.

A 64-year-old man had demonstrated palpitations caused by paroxysmal atrial fibrillation (AF) documented by ambulatory electrocardiographic monitoring. Effectiveness of antiarrhythmic agent (disopyramide: 300 mg/day) was limited. Based on the gastrointestinal endoscopic findings, proton pump inhibitor (PPI: rabeprazole, 10 mg/day) was administered to eliminate heart burn due to reflux esophagitis. Symptoms of paroxysmal AF and reflux esophagitis were confusing due to the anatomical proximity of the diseased organs and concomitant occurrence in the evening and when in a supine position. After the additional PPI therapy, not only was reflux esophagitis improved subjectively and endoscopically but also paroxysms of AF markedly reduced. Because esophagus is attached to left atrial posterior wall and the role of inflammatory process on the development of AF is highlighted, amelioration of reflux esophagitis by PPI may have been followed by the remarkable reduction of paroxysms of AF.

Relationship between amiodarone-induced subclinical lung toxicity and Th1/Th2 balance

BACKGROUND Although amiodarone is a potent antiarrhythmic agent, its clinical use is limited by serious lung toxicity. This study investigated the mechanisms of amiodarone-induced lung toxicity from an immunological perspective. Because interferon gamma (IFN-gamma: Th1 cytokine) inhibits pulmonary fibroblast proliferation whereas interleukin-4 (IL-4: Th2 cytokine) augments fibroblast growth and collagen production, we hypothesized that amiodarone lung toxicity is related to Th1/Th2 balance. METHODS Twenty-six consecutive Japanese patients with ventricular arrhythmias treated with amiodarone were enrolled in this study and were divided into two groups. Group A contained patients demonstrating amiodarone lung toxicity diagnosed by chest X-ray, KL-6 or D(LCO) (n=6), whereas group B included patients treated without any adverse effects (n=20). Th1/Th2 balance was investigated by the ratio of IFN-gamma and IL-4 produced by activated peripheral CD4(+) T cells. RESULTS Clinical baseline characteristics prior to oral amiodarone did not show any differences between group A and group B except for D(LCO) (82.0+/-5.2% vs. 90.8+/-9.0%, p=0.032) and Th1/Th2 balance (7.98+/-1.68 vs. 13.34+/-5.10, p=0.020). This balance was not altered three months after withdrawal of amiodarone in group A and under continued treatment in group B, suggesting patient-specific rather than amiodarone-induced. After starting amiodarone, serum concentration of desethylamiodarone was greater in group A than in group B (p=0.009) and was inversely proportional to Th1/Th2 ratio (p=0.013). Multilogistic regression analysis indicated that Th1/Th2 balance was the most powerful indicator of amiodarone lung toxicity (p=0.046, odds ratio of 0.424). CONCLUSIONS Although large cohort is required, the present study indicates that Th1/Th2 balance may influence amiodarone metabolism and may be a powerful indicator of amiodarone-induced subclinical lung toxicity at least in Japanese.

Reduced Plasma Eicosapentaenoic Acid–Arachidonic Acid Ratio in Peripheral Artery Disease

A reduced ratio of plasma eicosapentaenoic acid–arachidonic acid (EPA-AA) is a newly recognized atherosclerotic risk factor. This ratio has not been fully investigated in peripheral artery disease (PAD). Seventy Japanese patients with atherosclerotic risk factors were enrolled and divided into 2 groups, those with PAD (group A: n = 38) and those without PAD (group B: n = 32). The EPA-AA ratio (P = .001) and ankle–brachial index (ABI: P < .001) in group A were significantly lower than those in group B. Univariate and multivariate analyses demonstrated that EPA-AA, ABI, and prescription of clopidogrel had significant correlation with PAD. Given the appropriate cutoff values, EPA-AA (odds ratio [OR] = 11.7, 95% confidence interval [CI] = 3.0-45.8; P < .001) and ABI (OR = 44.0, 95% CI = 5.4-358.5; P < .001) are factors independently associated with PAD. In conclusion, this study demonstrated that reduced plasma EPA/AA may underlie PAD at least in Japanese.

Influence of common cardiac drugs on gastroesophageal reflux disease: Multicenter questionnaire survey

BACKGROUND Although gastroesophageal reflux disease (GERD) causes noncardiac chest pain mimicking angina pectoris, systemic studies surveying the effects of common cardiac drugs on symptomatic GERD are rare. METHODS To investigate the drugrelated GERD, this multicenter trial enrolled 201 consecutive cardiac outpatients (69.7 ± 10.5 y) after obtaining written informed consent. They were assessed using the Frequency Scale for Symptoms of GERD (F-scale) to screen for GERD with a cut-off value of 8.0. Clinical background was obtained from medical records. Gastric medicine was empirically administered at the discretion of the attending physician. F-scale score and incidence of GERD were analyzed individually in relation to background and prescription. RESULTS The average F-scale score did not correlate with gender, age or underlying diseases. F-scale score was elevated significantly (p = 0.006) by administration of calcium channel blockers to the patients treated with gastric medicine, suggesting that calcium channel blockers exacerbate the possibly preexisting GERD. Incidence of GERD within 2 months after starting warfarin tended to be greater than that at other durations (p = 0.087). Patients showing a high score (≥ 8.0) suggestive of GERD showed a correlation with the combined administration of calcium channel blockers (OR = 3.19; 95% CI of 1.01 - 10.11; p = 0.049) and warfarin (OR = 3.05; 95% CI of 1.00 - 9.27; p = 0.049) in the best logistic model. CONCLUSION Although larger cohort is required, this survey demonstrates that the combination of calcium channel blockers and warfarin is an independent risk factor for GERD.