Rutao Wang

Advanced Glycation End Products Accelerate Ischemia/Reperfusion Injury Through Receptor of Advanced End Product/Nitrative Thioredoxin Inactivation in Cardiac Microvascular Endothelial Cells

The advanced glycation end products (AGEs) are associated with increased cardiac endothelial injury. However, no causative link has been established between increased AGEs and enhanced endothelial injury after ischemia/reperfusion. More importantly, the molecular mechanisms by which AGEs may increase endothelial injury remain unknown. Adult rat cardiac microvascular endothelial cells (CMECs) were isolated and incubated with AGE-modified bovine serum albumin (BSA) or BSA. After AGE-BSA or BSA preculture, CMECs were subjected to simulated ischemia (SI)/reperfusion (R). AGE-BSA increased SI/R injury as evidenced by enhanced lactate dehydrogenase release and caspase-3 activity. Moreover, AGE-BSA significantly increased SI/R-induced oxidative/nitrative stress in CMECs (as measured by increased inducible nitric oxide synthase expression, total nitric oxide production, superoxide generation, and peroxynitrite formation) and increased SI/R-induced nitrative inactivation of thioredoxin-1 (Trx-1), an essential cytoprotective molecule. Supplementation of EUK134 (peroxynitrite decomposition catalyst), human Trx-1, or soluble receptor of advanced end product (sRAGE) (a RAGE decoy) in AGE-BSA precultured cells attenuated SI/R-induced oxidative/nitrative stress, reduced SI/R-induced Trx-1 nitration, preserved Trx-1 activity, and reduced SI/R injury. Our results demonstrated that AGEs may increase SI/R-induced endothelial injury by increasing oxidative/nitrative injury and subsequent nitrative inactivation of Trx-1. Interventions blocking RAGE signaling or restoring Trx activity may be novel therapies to mitigate endothelial ischemia/reperfusion injury in the diabetic population.

Downregulation of adiponectin induced by tumor necrosis factor α is involved in the aggravation of posttraumatic myocardial ischemia/reperfusion injury*

Objective:Recent clinical observations have indicated that nonlethal mechanical trauma significantly increases myocardial infarction risk even in the presence of completely normal coronary arteries. We investigated the molecular mechanisms responsible for exacerbation of ischemic myocardial injury after nonlethal mechanical trauma with a special focus on the role of tumor necrosis factor &agr; and its potential downstream effector adiponectin, a novel adipokine with anti-inflammatory and cardioprotective properties. Design:Laboratory study. Setting:University research unit. Subjects:Male adult adiponectin knockout mice and wild-type mice. Interventions:The animals were subjected to nonlethal mechanical trauma using the Noble-Collip drum (40 rpm ± 5 mins) followed by myocardial ischemia/reperfusion injury 7 days posttrauma. We also investigated the effects of neutralizing tumor necrosis factor &agr; with etanercept and exogenous adiponectin supplementation on ischemic myocardial injury after trauma. Measurements and Main Results:Trauma significantly sensitized myocardium to ischemia/reperfusion injury as evidenced by increased apoptosis, enlarged infarct size, and decreased cardiac function. Plasma adiponectin concentrations were reduced after traumatic injury (the nadir occurring 3 days posttrauma), an effect abrogated by etanercept-mediated tumor necrosis factor &agr; blockade. The downregulation of adiponectin was accompanied by increased myocardial superoxide and nitric oxide generation and peroxynitrite formation. Both etanercept and exogenous adiponectin supplementation (on day 3 posttrauma or 10 mins before reperfusion on day 7 posttrauma) markedly inhibited oxidative/nitrative stress and ischemia/reperfusion injury in posttraumatic ischemic/reperfused hearts of wild-type mice, whereas only adiponectin supplementation (but not tumor necrosis factor &agr; inhibition) substantially attenuated posttraumatic ischemia/reperfusion injury in adiponectin knockout mice. Conclusions:Tumor necrosis factor &agr;-induced downregulation of adiponectin and the resultant enhanced oxidative/nitrative stress are involved in exacerbated posttraumatic ischemic myocardial injury. Therapeutic approaches blocking tumor necrosis factor &agr; production or restoring adiponectin might have prophylactic value against secondary myocardial ischemic injury after a primary nonlethal mechanical trauma.

Dynamic alteration of adiponectin/adiponectin receptor expression and its impact on myocardial ischemia/reperfusion in type 1 diabetic mice

The present study determined the dynamic change of adiponectin (APN, a cardioprotective adipokine), its receptor expression, and their impact upon myocardial ischemia/reperfusion (MI/R) injury during type 1 diabetes mellitus (T1DM) progression, and involved underlying mechanisms. Diabetic state was induced in mice via multiple intraperitoneal injections of low-dose streptozotocin. The dynamic change of plasma APN concentration and cardiac APN receptor-1 and -2 (AdipoR1/2) expression were assessed immediately after diabetes onset (0 wk) and 1, 3, 5, and 7 wk thereafter. Indicators of MI/R injury (infarct size, apoptosis, and LDH release) were determined at 0, 1, and 7 wk of DM duration. The effect of APN on MI/R injury was determined in mice subjected to different diabetic durations. Plasma APN levels (total and HMW form) increased, whereas cardiac AdipoR1 expression decreased early after T1DM onset. With T1DM progression, APN levels were reduced and cardiac AdipoR1 expression increased. MI/R injury was exacerbated with T1DM progression in a time-dependent manner. Administration of globular APN (gAD) failed to attenuate MI/R injury in 1-wk T1DM mice, while an AMP-activated protein kinase (AMPK) activator (AICAR) reduced MI/R injury. However, administration of gAD (and AICAR) reduced infarct size and cardiomyocyte apoptosis in 7-wk T1DM mice. In conclusion, our results demonstrate a dynamic dysfunction of APN/AdipoR1 during T1DM progression. Reduced cardiac AdipoR1 expression and APN concentration may be responsible for increased I/R injury susceptibility at early and late T1DM stages, respectively. Interventions bolstering AdipoR1 expression during early T1DM stages and APN supplementation during advanced T1DM stages may potentially reduce the myocardial ischemic injury in diabetic patients.

The alternative crosstalk between RAGE and nitrative thioredoxin inactivation during diabetic myocardial ischemia-reperfusion injury

The receptor for advanced glycation end products (RAGE) and thioredoxin (Trx) play opposing roles in diabetic myocardial ischemia-reperfusion (MI/R) injury. We recently demonstrated nitrative modification of Trx leads to its inactivation and loss of cardioprotection. The present study is to determine the relationship between augmented RAGE expression and diminished Trx activity pertaining to exacerbated MI/R injury in the diabetic heart. The diabetic state was induced in mice by multiple intraperitoneal low-dose streptozotocin injections. RAGE small-interfering RNA (siRNA) or soluble RAGE (sRAGE, a RAGE decoy) was via intramyocardial and intraperitoneal injection before MI/R, respectively. Mice were subjected to 30 min of myocardial infarction followed by 3 or 24 h of reperfusion. At 10 min before reperfusion, diabetic mice were randomized to receive EUK134 (peroxynitrite scavenger), recombinant hTrx-1, nitrated Trx-1, apocynin (a NADPH oxidase inhibitor), or 1400W [an inducible nitric oxide synthase (iNOS) inhibitor] administration. The diabetic heart manifested increased RAGE expression and N(ε)-(carboxymethyl)lysine (CML, major advanced glycation end product subtype) content, reduced Trx-1 activity, and increased Trx nitration after MI/R. RAGE siRNA or administration of sRAGE in diabetic mice decreased MI/R-induced iNOS and gp91(phox) expression, reduced Trx nitration, preserved Trx activity, and decreased infarct size. Apocynin or 1400W significantly decreased nitrotyrosine production and restored Trx activity. Conversely, administration of either EUK134 or reduced hTrx, but not nitrated hTrx, attenuated MI/R-induced superoxide production, RAGE expression, and CML content and decreased cardiomyocyte apoptosis in diabetic mice. Collectively, we demonstrate that RAGE modulates the MI/R injury in a Trx nitrative inactivation fashion. Conversely, nitrative modification of Trx blocked its inhibitory effect upon RAGE expression in the diabetic heart. This is the first direct evidence demonstrating the alternative cross talk between RAGE overexpression and nitrative Trx inactivation, suggesting that interventions interfering with their interaction may be novel means of mitigating diabetic MI/R injury.

Low-Dose Versus Standard-Dose Tissue Plasminogen Activator in Acute Ischemic Stroke in Asian Populations: A Meta-Analysis.

AbstractRecent studies have investigated the most efficacious dose of intravenous tissue plasminogen activator (IV-tPA) for acute ischemic stroke (AIS) patients. There remains no definitive consensus concerning the superior efficacious IV-tPA dose (standard- vs. low-dose), prompting us to perform a meta-analysis comparing the efficacy and safety profile of standard- versus low-dose IV-tPA.We identified relevant studies pertaining to the specific aim of our meta-analysis by searching PubMed and EMBASE (January 1990–September 2015) Either a fixed- or random-effects model was employed (dependent upon data heterogeneity) to analyze the efficacy and safety outcome.Ten cohort studies involving 4389 sum patients were included in the meta-analysis. By using the random-effects model, the meta-analysis indicated no statistically significant difference in favorable functional outcome (modified Rankin scale 0–1) at 3 months (heterogeneity: &khgr;2 = 17.45, P = 0.04, I2 = 48%; OR: 0.88 [95% CI: 0.71–1.11]; P = 0.28) and incidence of symptomatic intracranial hemorrhage (SICH) (heterogeneity: &khgr;2 = 14.41, P = 0.11, I2 = 38%; OR: 1.19 [95% CI: 0.76 to 1.87]; P = 0.45) between the standard- and low-dose groups. The fixed-effects model demonstrated no significant difference in mortality within 3 months (heterogeneity: &khgr;2 = 6.73, P = 0.57, I2 = 0%; OR: 0.91 [95% CI: 0.73–1.12]; P = 0.37) between the standard- and low-dose groups.Low-dose IV-tPA is comparable to standard-dose IV-tPA in both efficacy (favorable functional outcome) and safety (SICH and mortality). Confirmation of these findings through randomized trials is warranted.

Effect of chronic pretreatment of angiotensin-converting receptor blocker on no-reflow phenomenon in patients with acute myocardial infarction undergoing percutaneous coronary intervention.

AIMS Angiotensin receptor blockers (ARBs) exert favorable effects on the vascular system, which are not directly related to hypertension lowering function. The no-reflow phenomenon determines the prognosis in patients after acute myocardial infarction (AMI). Early ARB treatment has many beneficial effects on the prognosis after AMI. In this study, we tested the hypothesis that ARB treatment before admission would have beneficial effects on the development of the no-reflow phenomenon after infarction. METHODS We investigated 276 consecutive patients with AMI undergoing successful primary percutaneous coronary intervention (PCI). No-reflow was defined as thrombolysis in myocardial infarction (TIMI) flow grade <3, which was determined by the TIMI frame count method using angiographic images obtained just after PCI and stenting. RESULTS Compared with patients without ARB treatment, patients with ARB had more frequently hypertension and ST resolution (P < 0.05), but no significant difference was found in the other clinical characteristics (age, sex, Hyperlipidaemia, Diabetes mellitus, etc) between the two groups. A total of 51 patients receiving chronic ARB treatment before admission have lower incidence of the no-reflow phenomenon than those without chronic ARB treatment (8.7% and 26.7%, P= 0.003). However, the incidence of the no-reflow phenomenon between the patients with and without hypertension had no significant difference. Multivariable logistic regression analysis revealed that ARB pretreatment was a significant predictor of the no-reflow phenomenon, whereas blood pressure was found to be insignificant. CONCLUSION Chronic pretreatment of ARB is associated with the reduction of the no-reflow phenomenon in patients with reperfused AMI and could preserve microvascular integrity after AMI independent of blood pressure lowering, which may contribute to better functional recovery.

The opposite effects of nitric oxide donor, S-nitrosoglutathione, on myocardial ischemia/reperfusion injury in diabetic and non-diabetic mice

Nitric oxide is a potent anti‐apoptotic and cardioprotective molecule in healthy animals. However, recent study demonstrates that overexpression of eNOS exacerbates the liver injury in diabetic animals. whether diabetes may also alter NOs biologic activity in ischaemic/reperfused heart remains unknown. The present experiment was designed to determine whether the nitric oxide donor, S‐nitrosoglutathione, may exert different effects on diabetic and non‐diabetic myocardial ischaemia/reperfusion (MI/R) injury. Diabetic state was induced in mice by multiple intraperitoneal injections of low‐dose streptozotocin (STZ). The control or diabetic mice were subjected to 30 minutes ischaemia and 3 or 24 hours reperfusion. At 10 minutes before reperfusion, diabetic and non‐diabetic mice were received an intraperitoneal injection of S‐nitrosoglutathione (GSNO, a nitric oxide donor, 1 μmol/kg). GSNO attenuated MI/R injury in non‐diabetic mice, as measured by improved cardiac function, reduced infarct size and decreased cardiomyocyte apoptosis. In contrast, GSNO failed to attenuate but, rather, aggravated the MI/R injury in diabetic mice. Mechanically, the diabetic heart exhibited an increased nitrative/oxidative stress level, as measured by peroxynitrite formation, compared with non‐diabetic mice. Co‐administration of GSNO with EUK134 (a peroxynitrite scavenger) or MnTE‐2‐PyP5 (a superoxide dismutase mimetic) or Apocynin (a NADPH oxidase inhibitor) 10 minutes before reperfusion significantly decreased the MI/R‐induced peroxynitrite formation and the MI/R injury. Collectively, the present study for the first time demonstrated that diabetes may cause superoxide overproduction, increase NO inactivation and peroxynitrite formation, and thus convert GSNO from a cardioprotective molecule to a cardiotoxic molecule.

Adiponectin multimers and their bioactivities were down-regulated in newly diagnosed Chinese type 2 diabetes patients

Objective Adiponectin, circulates as trimer, hexamer and high molecular weight form (HMW) in blood. Both adiponectin complexes concentration and their bioactivities are decreased in pathological state. Moreover, DsbA-L, a key regulator for adiponectin biosynthesis, is down-regulated in obese humans. However, the alterations of adiponectin multimers distribution, bioactivities and DsbA-L level in newly diagnosed Chinese type 2 diabetes (T2DM) patients are unknown. The objective of present study was to compare plasma adiponectin isoform status along with their bioactivities and DsbA-L concentration in T2DM with control subjects. Methods Plasma total adiponectin was measured by ELISA. Adiponectin multimers were analysed by western blot followed SDS-PAGE under nonheating nonreducing conditions. Plasma adiponectin multimers were isolated by chromotography techniques from plasma in ten T2DM and ten healthy control subjects respectively. Adiponectin bioactivity was detected by incubating HUVEC with isolated adiponectin isoforms and determining the phosphorylation level of AMPK and eNOS. DsbA-L protein expression level was determined by western blot. Results 189 T2DM (48.7±9.4 y) and 123 healthy people (42.8±8.0 y) were enrolled. In comparison with healthy control group, total adiponectin (p<0.0001) and HMW adiponectin (p<0.05) were significantly lower in T2DM patients. Furthermore, HMW adiponectin bioactivity (p-AMPK and p-eNOS level, p<0.01 and p<0.01, respectively) and DsbA-L level (p<0.01) were decreased in diabetes patients. Conclusion This study directly demonstrated for the first time that human HMW adiponectin bioactivity was decreased in type 2 diabetes. We also provide a target for regulating HMW adiponectin concentration in diabetic patients.

ASSA14-03-04 Circulating hematopoietic progenitor cells in patients undergoing coronary artery bypass graft surgery

Objective To evaluate the change of circulating hematopoietic progenitor cells (cHPCs) in patients undergoing coronary artery bypass graft surgery. Methods 51 patients who were scheduled to undergo elective coronary artery bypass graft surgery were prospectively enrolled in this study. Blood samples were collected at baseline, on postoperative day 1, postoperative day 3 and postoperative day 5. The CD34+CD45dim, CD133+CD45dim, CD34+CD133+ CD45dim cell were measured by flow cytometry. Circulating progenitor cell functions were studied in vitro by clonogenic and migration assays. Results All elective patients showed a significant post-operative increase of CD34+CD45dim (1.51 ± 1.26 vs 2.02 ± 1.16, p = 0.036) and CD133+CD45dim cells (1.16 ± 0.85 vs 1.65 ± 0.99, p = 0.008), irrespective of on-pump CABG or off-pump CABG. The periopoerative change of cHPCs level in patients undergoing on-pump surgery was more significant than that in patients with off-pump surgery. Conclusion Patients undergoing elective cardiac surgery demonstrated an increase in cHPC level postoperaively.

INCREASED URINARY ADIPONECTIN LEVEL IS ASSOCIATED WITH CONTRAST-INDUCED NEPHROPATHY IN PATIENTS UNDERGOING PCI

Contrast-induced nephropathy (CIN) is one of major complications in patients undergoing PCI. We prospectively examined the association of urinary adiponectin (UAPN), a sensitive marker for early renal function impairment, with CIN. We enrolled 208 patients without severe hepatic and renal function