Hyun Jai Cho

Adipokine resistin is a key player to modulate monocytes, endothelial cells, and smooth muscle cells, leading to progression of atherosclerosis in rabbit carotid artery.

OBJECTIVESnWe investigated the effects of human resistin on atherosclerotic progression and clarified its underlying mechanisms.nnnBACKGROUNDnResistin is an adipokine first identified as a mediator of insulin resistance in murine obesity models. But, its role in human pathology is under debate. Although a few recent studies suggested the relationship between resistin and atherosclerosis in humans, the causal relationship and underlying mechanism have not been clarified.nnnMETHODSnWe cloned rabbit resistin, which showed 78% identity to human resistin at the complementary deoxyribonucleic acid level, and its expression was examined in 3 different atherosclerotic rabbit models. To evaluate direct role of resistin on atherosclerosis, collared rabbit carotid arteries were used. Histological and cell biologic analyses were performed.nnnRESULTSnRabbit resistin was expressed by macrophages of the plaque in the 3 different atherosclerotic models. Peri-adventitial resistin gene transfer induced macrophage infiltration and expression of various inflammatory cytokines, resulting in the acceleration of plaque growth and destabilization. In vitro experiments elucidated that resistin increased monocyte-endothelial cell adhesion by upregulating very late antigen-4 on monocytes and their counterpart vascular cell adhesion molecule-1 on endothelial cells. Resistin augmented monocyte infiltration in collagen by direct chemoattractive effect as well as by enhancing migration toward monocyte chemotactic protein-1. Administration of connecting segment-1 peptide, which blocks very late antigen-4 × vascular cell adhesion molecule-1 interaction, ameliorated neointimal growth induced by resistin in vivo.nnnCONCLUSIONSnOur results indicate that resistin aggravates atherosclerosis by stimulating monocytes, endothelial cells, and vascular smooth muscle cells to induce vascular inflammation. These findings provide the first insight on the causal relationship between resistin and atherosclerosis.

A multicentre cohort study of acute heart failure syndromes in Korea: Rationale, design, and interim observations of the Korean Acute Heart Failure (KorAHF) registry

The Korean Acute Heart Failure registry (KorAHF) aims to evaluate the clinical characteristics, management, hospital course, and long‐term outcomes of patients hospitalized for acute heart failure syndrome (AHFS) in Korea.

Angiopoietin-1 promotes endothelial differentiation from embryonic stem cells and induced pluripotent stem cells.

Angiopoietin-1 (Ang1) plays a crucial role in vascular and hematopoietic development, mainly through its cognate receptor Tie2. However, little is known about the precise role of Ang1 in embryonic stem cell (ESC) differentiation. In the present study, we used COMP-Ang1 (a soluble and potent variant of Ang1) to explore the effect of Ang1 on endothelial and hematopoietic differentiation of mouse ESCs in an OP9 coculture system and found that Ang1 promoted endothelial cell (EC) differentiation from Flk-1(+) mesodermal precursors. This effect mainly occurred through Tie2 signaling and was altered in the presence of soluble Tie2-Fc. We accounted for this Ang1-induced expansion of ECs as enhanced proliferation and survival. Ang1 also had an effect on CD41(+) cells, transient precursors that can differentiate into both endothelial and hematopoietic lineages. Intriguingly, Ang1 induced the preferential differentiation of CD41(+) cells toward ECs instead of hematopoietic cells. This EC expansion promoted by Ang1 was also recapitulated in induced pluripotent stem cells (iPSCs) and human ESCs. We successfully achieved in vivo neovascularization in mice by transplantation of ECs obtained from Ang1-stimulated ESCs. We conclude that Ang1/Tie2 signaling has a pivotal role in ESC-EC differentiation and that this effect can be exploited to expand EC populations.

Angiopoietin-1 protects heart against ischemia/reperfusion injury through VE-cadherin dephosphorylation and myocardiac integrin-β1/ERK/caspase-9 phosphorylation cascade.

Early reperfusion after myocardial ischemia that is essential for tissue salvage also causes myocardial and vascular injury. Cardioprotection during reperfusion therapy is an essential aspect of treating myocardial infarction. Angiopoietin-1 is an endothelialspecific angiogenic factor. The potential effects of angiopoietin-1 on cardiomyocytes and vascular cells undergoing reperfusion have not been investigated. We propose a protective mechanism whereby angiopoietin-1 increases the integrity of the endothelial lining and exerts a direct survival effect on cardiomyocytes under myocardial ischemia followed by reperfusion. First, we found that angiopoietin-1 prevents vascular leakage through regulating vascular endothelial (VE)-cadherin phosphorylation. The membrane expression of VE-cadherin was markedly decreased on hypoxia/reoxygenation but was restored by angiopoietin-1 treatment. Interestingly, these effects were mediated by the facilitated binding between SH2 domain-containing tyrosine phosphatase (SHP2) or receptor protein tyrosine phosphatase μ (PTPμ) and VE-cadherin, leading to dephosphorylation of VE-cadherin. siRNA against SHP2 or PTPμ abolished the effect of angiopoietin-1 on VE-cadherin dephosphorylation and thereby decreased levels of membrane-localized VE-cadherin. Second, we found that angiopoietin-1 prevented cardiomyocyte death, although cardiomyocytes lack the angiopoietin-1 receptor Tie2. Angiopoietin-1 increased cardiomyocyte survival through integrin-β1-mediated extracellular signal-regulated kinase (ERK) phosphorylation, which inhibited caspase-9 through phosphorylation at Thr125 and subsequently reduced active caspase-3. Neutralizing antibody against integrin-β1 blocked these protective effects. In a mouse myocardial ischemia/reperfusion model, angiopoietin-1 enhanced cardiac function and reduction in left ventricular-end systolic dimension (LV-ESD) and left ventricular-end diastolic dimension (LV-EDD) with an increase in ejection fraction (EF) and fractional shortening (FS). Our findings suggest the novel cardioprotective mechanisms of angiopoietin-1 that are achieved by reducing both vascular leakage and cardiomyocyte death after ischemia/reperfusion injury.

G-CSF exerts dual effects on endothelial cells—Opposing actions of direct eNOS induction versus indirect CRP elevation

Granulocyte-colony stimulating factor (G-CSF) has been shown to have protective effects in the heart and brain. However, it may also be involved in the acute inflammatory response which may be harmful. The effects of G-CSF on endothelial cells (ECs) and the vasculature are mostly unknown. To study the possible dual effects of G-CSF on ECs, we investigated whether G-CSF induces release of C-reactive protein (CRP) by hepatocytes and whether the direct beneficial effects of G-CSF could protect ECs from the detrimental effects of CRP. G-CSF treatment significantly induced monocytes to produce IL-6, and culture supernatants of G-CSF-stimulated monocytes induced CRP production in hepatocytes. On the other hand, G-CSF directly promoted EC proliferation and migration and reversed the deleterious effects of CRP. In mechanistic analyses, G-CSF increased not only the protein expression of endothelial nitric oxide synthase (eNOS), but also its transcription. Furthermore, it enhanced eNOS phosphorylation and activation, leading to increased production of NO. Thus, G-CSF reversed the attenuated production of NO by CRP. These effects of G-CSF on eNOS transcription, translation, and activation were blunted by the PI3K inhibitor, suggesting that EC protective effects of G-CSF were associated with the activation of the Akt/eNOS pathway. In conclusion, although G-CSF induces an inflammatory reaction leading to CRP production, it has direct beneficial effects protecting ECs from the deleterious effects of CRP through activation of Akt/eNOS pathway, leading to an increase in NO production. Our data suggests that G-CSF may exert dual opposing effects on endothelial cells.

Clinical Characteristics and Outcome of Acute Heart Failure in Korea: Results from the Korean Acute Heart Failure Registry (KorAHF)

Background and Objectives The burden of heart failure has increased in Korea. This registry aims to evaluate demographics, clinical characteristics, management, and long-term outcomes in patients hospitalized for acute heart failure (AHF). Subjects and Methods We prospectively enrolled a total of 5625 consecutive subjects hospitalized for AHF in one of 10 tertiary university hospitals from March 2011 to February 2014. Descriptive statistics were used to determine the baseline characteristics of the study population and to compare them with those from other registries. Results The mean age was 68.5±14.5 years, 53.2% were male, and 52.2% had de novo heart failure. The mean systolic and diastolic blood pressures were 131.2±30.3 mmHg and 78.6±18.8 mmHg at admission, respectively. The left ventricular ejection fraction was ≤40% in 60.5% of patients. Ischemia was the most frequent etiology (37.6%) and aggravating factor (26.3%). Angiotensin converting enzyme inhibitors/angiotensin receptor blockers, beta-blockers, and aldosterone antagonists were prescribed in 68.8%, 52.2%, and 46.6% of the patients at discharge, respectively. Compared with the previous registry performed in Korea a decade ago, extracorporeal membrane oxygenation (ECMO) and heart transplantation have been performed more frequently (ECMO 0.8% vs. 2.8%, heart transplantation 0.3% vs. 1.2%), and in-hospital mortality decreased from 7.6% to 4.8%. However, the total cost of hospital care increased by 40%, and one-year follow-up mortality remained high. Conclusion While the quality of acute clinical care and AHF-related outcomes have improved over the last decade, the long-term prognosis of heart failure is still poor in Korea. Therefore, additional research is needed to improve long-term outcomes and implement cost-effective care.

Combination Therapy of Rosuvastatin and Ezetimibe in Patients with High Cardiovascular Risk

PURPOSEnThe aim of this study was to evaluate the efficacy and tolerability of rosuvastatin/ezetimibe combination therapy in Korean patients with high cardiovascular risk.nnnMETHODSnThis was a 12-week, randomized, double-blind, placebo-controlled, multicenter study. A total of 337 patients were screened. After a 4-week run-in period, 245 of these patients with high or moderately high risk as defined by the National Cholesterol Education Program Adult Treatment Panel III guidelines were randomly assigned. Patients received 1 of 6 regimens for 8 weeks as follows: (1) rosuvastatin 5 mg, (2) rosuvastatin 5 mg/ezetimibe 10 mg, (3) rosuvastatin 10 mg, (4) rosuvastatin 10 mg/ezetimibe 10 mg, (5) rosuvastatin 20 mg, or (6) rosuvastatin 20 mg/ezetimibe 10 mg. The primary outcome variable was percentage change in the level of LDL-C at week 8 of drug treatment. Secondary outcome variables included percentage changes of other lipid variables and achievement rates of LDL-C targets. Tolerability analyses were also performed.nnnFINDINGSnThe percentage change of LDL-C ranged from -45% to -56% (mean, -51%) in the monotherapy groups and from -58% to -63% (mean, -60%) in the combination therapy groups. The percentage change was greater in the pooled combination therapy group than in the counterpart (P < 0.001 for the pooled groups); this difference was more obvious for regimens with a lower statin dose. The percentage reductions of total cholesterol and triglycerides were greater in the combination groups than in the monotherapy groups. The LDL-C target achievement rates were 64% to 87% (mean, 73%) in the monotherapy groups and 87% to 95% (mean, 91%) in the combination groups (P = 0.01 for the pooled groups). The rates were significantly greater in patients receiving the combination therapy than in the monotherapy at lower doses of rosuvastatin. The proportions of patients with various adverse events were not significantly different between the groups.nnnIMPLICATIONSnRosuvastatin/ezetimibe combination therapy has better efficacy and target achievement rates than rosuvastatin monotherapy in patients with high cardiovascular risk.

Effects of intensive versus mild lipid lowering by statins in patients with ischemic congestive heart failure: Korean Pitavastatin Heart Failure (SAPHIRE) study

Background/Aims This study was designed to evaluate the dose-effect relationship of statins in patients with ischemic congestive heart failure (CHF), since the role of statins in CHF remains unclear. Methods The South koreAn Pitavastatin Heart FaIluRE (SAPHIRE) study was designed to randomize patients with ischemic CHF into daily treatments of 10 mg pravastatin or 4 mg pitavastatin. Results The low density lipoprotein cholesterol level decreased by 30% in the pitavastatin group compared with 12% in the pravastatin (p < 0.05) group. Left ventricular systolic dimensions decreased significantly by 9% in the pitavastatin group and by 5% in the pravastatin group. Left ventricular ejection fraction (EF) improved significantly from 37% to 42% in the pitavastatin group and from 35% to 39% in the pravastatin group. Although the extent of the EF change was greater in the pitavastatin group (16% vs. 11%) than that in the pravastatin group, no significant difference was observed between the groups (p = 0.386). Exercise capacity, evaluated by the 6-min walking test, improved significantly in the pravastatin group (p < 0.001), but no change was observed in the pitavastatin group (p = 0.371). Conclusions Very low dose/low potency pravastatin and high dose/high potency pitavastatin had a beneficial effect on cardiac reverse remodeling and improved systolic function in patients with ischemic CHF. However, only pravastatin significantly improved exercise capacity. These findings suggest that lowering cholesterol too much may not be beneficial for patients with CHF.

Early parasympathetic reinnervation is not related to reconnection of major branches of the vagus nerve after heart transplantation

Background and Objectives Bicaval heart transplantation (HTx) may promote parasympathetic reinnervation. However, the prevalence and timing of reinnervation have not been fully investigated. Heart rate variability (HRV) and direct vagal stimulation were used to evaluate the presence of parasympathetic reinnervation after bicaval HTx. Subjects and Methods A total of 21 patients (time after HTx 0.52-4.41 years, mean 1.8±1.2 years) who received a bicaval HTx was enrolled. Reinnervation was evaluated using HRV values from 24-hour Holter recordings. A cross-sectional analysis of the HRV at 0.5-1, 1-2, and >2 years after HTx was performed. We also applied high-frequency electrical stimulation (16.7 Hz, 1 msec pulse width, ≤10 V) to the cardiac branches of the vagus nerve at the level of the superior vena cava in eight patients at 6 and 12 months after HTx. Results The degree of parasympathetic reinnervation corresponded to the time after HTx. The HRV analysis revealed that the root mean square of the successive differences between consecutive RR-intervals (RMSSD) and high-frequency power were significantly higher during the late period (>2 years) compared with the early period (0.5-1 year) after HTx. None of the eight patients who underwent direct vagal stimulation responded during the stimulation at 6 and 12 months, whereas incremental trends in HRV parameters were observed, which indicated that parasympathetic reinnervation began within 1 year after HTx. Conclusion Parasympathetic reinnervation seemed to begin in the early period (<1 year) after bicaval HTx. Reconnection of major branches of the vagus nerve may not be related to early reinnervation.

Prevalence and socio-economic burden of heart failure in an aging society of South Korea

BackgroundHeart failure (HF) is one of the leading causes of morbidity and mortality in South Korea. With the rapidly aging population in the country, the prevalence of HF and its associated costs are expected to rise continuously. This study was carried out to estimate the prevalence and economic burden of HF in order to understand its impact on our society.MethodsA prevalence-based, cost-of-illness study was conducted using the 2014 Health Insurance Review and Assessment Service-National Patients Sample (HIRA-NPS) data. Adult HF patients were defined as those aged ≥19xa0years who had at least one insurance claim record with a primary or secondary diagnosis of HF (ICD-10 codes of I11.0, I13.0, I13.2, and I50.x). The costs consist of direct costs (i.e., medical and non-medical costs) and indirect costs (i.e., productivity loss cost due to morbidity and premature death). Subgroup analyses were conducted by age group, history of HF hospitalization, and type of universal health security program enrolled in.ResultsA total of 475,019 adults were identified to have HF in 2014. The estimated prevalence rate of HF was 12.4 persons per 1,000 adults. According to the base cases and the extended definition of the cases, the annual economic burden of HF from a societal perspective ranges from USD 1,414.0 to 1,560.5 for individual patients, and from USD 752.8 million to 1,085.6 million for the country. A high percentage (68.5xa0%) of this socioeconomic burden consist of medical costs, followed by caregiver’s cost (13.2xa0%), productivity loss costs due to premature death (10.8xa0%) and morbidity (4.2xa0%), and transportation costs (3.4xa0%). The HF patients with prior hospitalization due to HF annually spent 9.7 times more for National-Health-Insurance-covered medical costs compared to HF patients who were not previously hospitalized.ConclusionsIn the present study, HF patients who were older and had a history of prior hospitalization for HF as well as an indigent status were shown at high risk of spending more for healthcare to treat their HF. An effective disease management protocol should be employed to target this patient group.