Joji Nitobe

Toll-Like Receptor-2 Modulates Ventricular Remodeling After Myocardial Infarction

Background—Toll-like receptors (TLRs) are members of the interleukin-1 receptor family and transduce similar signals as interleukin-1 receptor in response to exogenous pathogens. Recent studies have demonstrated that TLRs are activated by endogenous signals, such as heat shock proteins and oxidative stress, that may contribute to ventricular remodeling after myocardial infarction. In this study, we determined whether TLR-2 was involved in cardiac remodeling after myocardial infarction. Methods and Results—Myocardial infarction was induced by surgical left anterior descending coronary artery ligation on wild-type (WT) mice and TLR-2–knockout (KO) mice. The survival rate was significantly higher in KO mice than in WT mice 4 weeks after myocardial infarction (65% versus 43%, P <0.03). Infarct size and degree of inflammatory cell infiltration in infarct area were similar between WT and KO mice. However, myocardial fibrosis in the noninfarct area of KO mice was much less than in WT mice (P <0.01) and was accompanied by reduced transforming growth factor-&bgr;1 and collagen type 1 mRNA expressions (P <0.01 and P <0.05, respectively). Left ventricular dimensions at end diastole were smaller in KO mice than in WT mice at 1 week (P <0.05) and 4 weeks (P <0.01) after surgery. Furthermore, fractional shortening was higher (27.7±2.5% versus 21.2±2.6%, P <0.05, at 1 week, and 24.3±2.0% versus 16.6±2.5%, P <0.01, at 4 weeks) in KO mice compared with WT mice. Conclusions—These data suggest that TLR-2 plays an important role in ventricular remodeling after myocardial infarction.

Reactive oxygen species regulate FLICE inhibitory protein (FLIP) and susceptibility to Fas-mediated apoptosis in cardiac myocytes

OBJECTIVE Fas ligand (FasL) is a key cytokine which initiates apoptosis when FasL binds to its receptor, Fas. Cardiac myocytes are generally resistant to Fas-induced apoptosis. However, sublethal dose of doxorubicin (Dox) can sensitize cardiac myocytes to Fas-induced apoptosis. We investigated the molecular mechanism by which Dox sensitizes cardiac myocytes to Fas-induced apoptosis. FLICE inhibitory protein (FLIP) is a key molecule for blocking Fas-induced apoptosis by functioning as a caspase-8 dominant negative. METHODS AND RESULTS FLIP was constitutively expressed in cultured neonatal rat cardiac myocytes. FLIP protein levels were markedly down-regulated by Dox in a time-dependent and dose-dependent manner. Next, we examined the relation of reactive oxygen species (ROS) by Dox to the expression of FLIP. Both of N-acetylcysteine (NAC) and the combination of superoxide dismutase and catalase restored the decreased FLIP in Dox-treated cardiac myocytes to the basal level. NAC also restored the increased formation of thiobarbituric acid-reactive substance after Dox-treatment. Concurrently, the susceptibility to Fas-mediated apoptosis disappeared with the treatments of the antioxidant agents. Hydrogen peroxide down-regulated FLIP in a dose-dependent fashion and also sensitized cardiac myocytes to Fas-induced apoptosis. CONCLUSIONS FLIP, an inhibitor of apoptosis induced by cytokines of TNF family, contributes at least partly to Dox-induced sensitization to Fas-mediated apoptosis in cardiac myocytes. The expression of FLIP in cardiac myocytes is regulated by ROS.

Relation of Serum Heat Shock Protein 60 Level to Severity and Prognosis in Chronic Heart Failure Secondary to Ischemic or Idiopathic Dilated Cardiomyopathy

Heat shock protein (HSP) 60 is induced by a variety of stressors, including oxidative stress and inflammation, and it plays a protective role against stress-induced cardiomyocyte injury. Recently, it has been reported that HSP 60 exists in the circulation. Chronic heart failure (CHF) is characterized by systemic abnormalities, and the myocardium is exposed to various stressors. However, the clinical significance of serum HSP 60 has not been examined in CHF. Therefore, the purpose of this study was to examine whether HSP 60 is correlated with the severity of CHF and whether HSP 60 can predict clinical outcomes in patients with CHF. Serum HSP 60 levels were measured in 112 patients with CHF and 62 control subjects. Serum HSP 60 levels were higher in patients with CHF than in control subjects and increased with advancing New York Heart Association functional class. There were 37 cardiac events during a mean follow-up period of 569 +/- 476 days (range 17 to 1,986). Serum HSP 60 levels were higher in patients with cardiac events than in event-free patients. Patients were divided into 4 groups on the basis of HSP 60 level. Cox proportional-hazards regression analysis and Kaplan-Meier analysis revealed that the fourth quartile was associated with the greatest risk for cardiac events. In conclusion, serum HSP 60 level was related to the severity of CHF and associated with a high risk for adverse cardiac events in patients CHF.

8-Hydroxy-2'-deoxyguanosine is a prognostic mediator for cardiac event.

Eur J Clin Invest 2011; 41 (7): 759–766

Hemodialysis improves myocardial interstitial edema and left ventricular diastolic function in patients with end-stage renal disease: noninvasive assessment by ultrasonic tissue characterization.

Abstract. Congestive heart failure is the most common cause of mortality in patients with end-stage renal disease (ESRD). Ultrasonic tissue characterization with integrated backscatter offers a promising method for the noninvasive assessment of regional myocardial contractile performance and fibrosis. The aim of this study was to investigate the effect of hemodialysis (HD) on myocardial tissue characterization and left ventricular function in ESRD patients. We examined 26 patients with ESRD undergoing routine HD (age 63 ± 12 years, duration of HD 9.2 ± 3.2 years) and 30 patients with essential hypertension (HT; 60 ± 10 years). Routine echocardiographic parameters and the cyclic variation of ultrasonic integrated backscatter of the ventricular septum (CV-IBS) were measured. Left ventricular mass index was significantly larger in patients with ESRD than in those with HT (217 ± 56 vs 146 ± 45 g/m2, P < 0.05). The indices for left ventricular diastolic function (E/A, the ratio of left ventricular peak early to late diastolic filling velocity; DT, the deceleration time of the early diastolic filling) and CV-IBS had deteriorated significantly in patients with ESRD before HD compared with those with HT (E/A, 0.6 ± 0.2 vs 0.9 ± 0.3, P < 0.05; DT, 228 ± 23 vs 184 ± 19 ms, P < 0.05; CV-IBS, 9.0 ± 1.3 vs 12.4 ± 0.9 dB, P < 0.05), possibly reflecting interstitial fibrosis. In patients with ESRD, HD reduced calculated left ventricular mass index by 19% (before HD, 217 ± 56 vs immediately after HD, 176 ± 45 g/m2, P < 0.05) and CV-IBS by 19% (9.0 ± 1.3 vs 7.3 ± 1.1 dB, P < 0.05), that possibly reflected improvement of interstitial edema. HD also significantly improved indices for left ventricular diastolic function (E/A, 0.6 ± 0.2 vs 0.9 ± 0.2, P < 0.05; DT, 228 ± 23 vs 188 ± 21 ms, P < 0.05). HD improves myocardial interstitial edema and left ventricular diastolic function in patients with ESRD. Noninvasive assessment of ultrasonic tissue characterization is useful in defining the pathophysiological changes of ventricular myocardium in patients with ESRD.

The role of epicardial adipose tissue in coronary artery disease in non-obese patients

BACKGROUND Epicardial adipose tissue (EAT) surrounding the heart may contribute to the development of coronary artery disease (CAD) through its local secretion of adipocytokines. Although the quantity of EAT is associated with obesity and metabolic syndrome, the role of EAT in the development of CAD in non-obese patients remains to be determined. METHODS This study included 41 patients with CAD who underwent coronary artery bypass graft surgery and 28 patients without CAD who underwent other cardiac surgery. EAT volume was measured by 64-slice multi-detector computed tomography before the surgery. We obtained pericardial fluid and epicardial and subcutaneous adipose tissue samples at the surgery. We investigated the relationship between EAT volume and adiponectin levels in pericardial fluid and incident CAD in patients with and without obesity (body mass index>25 kg/m(2)). RESULTS There was no significant difference in EAT volume between obese patients with and without CAD (55.5 ± 40.2 mL vs. 40.1 ± 19.7 mL, p=0.323). However, EAT volume was significantly greater in non-obese patients with CAD compared to those without CAD (35.0 ± 18.8 mL vs. 15.7 ± 11.0 mL, p<0.001). Adiponectin concentrations in pericardial fluid were significantly lower in non-obese patients with CAD compared to those without CAD (2.7 ± 2.0 μg/mL vs. 4.3 ± 3.7 μg/mL, p=0.049), whereas the adiponectin levels were decreased in obese patients regardless of the presence of CAD. Non-obese patients with CAD had significantly larger size adipocytes in EAT but not subcutaneous adipose tissue compared to those without CAD. Multiple logistic regression analysis showed that increased EAT volume was independently associated with incident CAD in non-obese patients. CONCLUSION Increased EAT may play a crucial role in development of CAD through impairment of adiponectin secretion in non-obese patients.

Serum Midkine as a Predictor of Cardiac Events in Patients With Chronic Heart Failure

BACKGROUND Midkine, a heparin-binding growth factor, has various functions such as migration of inflammatory cell and anti-apoptotic effect. Invasion of inflammatory cell and cardiomyocyte apoptosis are involved in development and progression of heart failure (HF). However, the relationship between midkine and HF has not been previously examined. Therefore, we examined clinical significance of serum midkine levels to determine the prognosis of HF patients. METHODS AND RESULTS Serum levels of midkine were measured at admission in 216 consecutive patients hospitalized for HF and 60 control subjects. Patients were prospectively followed during a mean follow-up period of 653 +/- 375 days with the end points of cardiac death and progressive HF requiring rehospitalization. Serum concentrations of midkine were significantly higher in patients with HF than in controls. Patients with cardiac events had significantly higher concentrations of midkine than those without cardiac events. Kaplan-Meier analysis revealed that cardiac event rates increased markedly as midkine levels rose. Furthermore in the multivariate analysis, after adjustment for age, gender ,and complications, midkine was the independent predictor of cardiac events. CONCLUSION Serum midkine levels are increased in HF patients, and midkine is a novel marker for risk stratifying HF patients.

Nitric Oxide Enhances Expression and Shedding of Tumor Necrosis Factor Receptor I (p55) in Endothelial Cells

The biological actions of tumor necrosis factor-alpha (TNF-alpha) are mediated by 2 distinct receptors, TNF-RI (p55) and TNF-RII (p75). The extracellular domains of both receptors are shed in soluble form (sTNF-RI and sTNF-RII). The soluble receptors are involved in regulating TNF-alpha activities and may have therapeutic potential as TNF-neutralizing agents. However, it remains unclear as to what kind of physiological molecule can regulate TNF receptors. Nitric oxide (NO) mediates a variety of biological and pathophysiological functions. We hypothesized that NO may modulate the expression and shedding of TNF-RI. An NO donor, diethylamine/NO complex (NOC 5), increased sTNF-RI in the supernatants of ECV304, a human umbilical vein cell line, in a dose-dependent manner. TNF-RI mRNA in these cells was upregulated by NOC 5. 8-Br-cGMP and peroxynitrate had no effect on sTNF-RI release. Genistein and herbimycin A, inhibitors of tyrosine kinase, inhibited sTNF-RI release. Herbimycin A inhibited the levels of TNF-RI mRNA enhanced by NOC 5, which downregulated the surface expression of TNF-RI, indicating that NO is also involved in the shedding process of TNF-RI. The shedding of TNF-RI was abolished by a synthetic inhibitor of matrix metalloproteinase, KB-R8301. In conclusion, NO enhanced the release of sTNF-RI from endothelial cells by a cGMP-independent mechanism. Dual pathways suggested for NO-induced sTNF-RI release include (1) enhanced expression of TNF-RI, at least partially, by a tyrosine kinase-dependent mechanism and (2) increased shedding of TNF-RI by a type of metalloproteinase.

Low Wall Velocity of Left Atrial Appendage Measured by Trans-Thoracic Echocardiography Predicts Thrombus Formation Caused by Atrial Appendage Dysfunction

BACKGROUND Atrial fibrillation is associated with ischemic stroke because of thrombi that form within the left atrial appendage (LAA). The aim of this study was to develop a new parameter for LAA function that is easily performed using transthoracic echocardiography (TTE). METHODS TTE and transesophageal echocardiography were performed in 106 patients with stroke. LAA wall motion velocity (TTE-LAWV) was measured using Doppler tissue imaging at the LAA tip. RESULTS TTE-LAWV was significantly lower in patients with atrial fibrillation and LAA thrombus than in those with atrial fibrillation and no LAA thrombus and in sinus rhythm (7.5 +/- 1.9 vs 10.0 +/- 3.4 and 13.8 +/- 5.7 cm/s, respectively, P < .05). TTE-LAWV was significantly correlated with LAA emptying flow velocity (R = 0.462, P < .05). The multivariate logistic regression analysis showed that TTE-LAWV < 8.7 cm/s was an independent predictor of LAA thrombus formation (odds ratio, 9.473; 95% confidence interval, 1.172-76.55; P < .05). CONCLUSION TTE-LAWV can noninvasively evaluate LAA dysfunction and assist in the detection of LAA thrombus.

Suppressive Effects of Valsartan on Microalbuminuria and CRP in Patients with Metabolic Syndrome (Val-Mets)

The presence of metabolic syndrome (Mets) increases the risk for cardiovascular disease. There is a significant correlation between the levels of urinary albumin to creatinine ratio (UACR) and high-sensitive C-reactive peptide (hs-CRP), and accumulation of each Mets component. Increasing evidence has shown the importance of blockade of renin-angiotensin-systems (RAS) for reducing urinary albumin excretion and hs-CRP levels in Mets patients. However, the impact of RAS blockade on these effects in hypertensive (HT) Mets patients without diabetes mellitus (DM) has not been evaluated. We prospectively measured the levels of UACR and hs-CRP in 153 HT patients with and without Mets. Body weight; waist circumference; presence of dyslipidemia and DM, and levels of HOMA-R, UACR, and hs-CRP were significantly higher in HT patients with Mets than in those without Mets. After we treated these Mets patients with valsartan for 6 months, blood pressure (BP), UACR, and hs-CRP were decreased, whereas body weight, HOMR-R, and the lipid profile were not changed. In HT Mets patients without DM, 6 months after valsartan administration, levels of UACR and hs-CRP were also significantly decreased by 37.8% (–9.0–56.5%, p < 0.05) and 23.6% (–28.7–73.4%, p < 0.05), respectively. However, the percentage change of UACR and hs-CRP was not correlated with the reduction in BP. Valsartan administration lowered increased levels of chronic inflammation in both HT Mets patients with DM and in those without DM. These results indicate that the anti-inflammatory properties of valsartan might also have beneficial effects in Mets patients without DM.