| Part 1The Early Development of Cardiac Remodeling after Coronary Microembolization and Its Relations to TGF-β1/Smad3 in PigsBackground:Coronary microembolization (CME) is one of significant and frequent complications of atherosclerosis plaque rupture in acute coronary syndromes and coronary interventions. However, it has not been evidenced whether the progressive contractive dysfunction after CME is associated with the early initiation of cardiac remodeling. At the same time, as a critical cytokine involved in a wide scope of physiological and pathological processes, the influence of transforming growth factor-betal (TGF-β1) to the early initiation and progression of cardiac remodeling after CME is still unknown.Objective:This study was designed to describe the early development of cardiac remodeling after CME, and elucidate its relations to TGF-β1 and Smad3.Methods:A total of eighteen mini-pigs were enrolled in this study. Fifteen pigs were subjected to CME with infusion of 42μm-microspheres into left anterior descending artery; three pigs were underwent sham-operation. MRI was performed at baseline,6th hour and one week after CME. Detection included the evaluation of left ventricular ejection fraction (LVEF), Left ventricular end-systolic volume (LVESV), left ventricular end-diastolic volume (LVEDV). The serum levels of TGF-β1, IL-6 and TNF-αwere detected by ELISA, while Troponin T was analyzed by immunoturbidimetry. Myocardial expression of TGF-β1 and Smad3 was detected by western blot and immunohistochemistry. In addition, the mRNA expression of TGF-β1 and Smad3 were analyzed by Realtime-PCR. Masson Trichrome stain was also performed to distinguish areas of collagen.Results:As detected by the 3.0T MRI, the values of LVESV (20.2ml vs.15.3ml, P<0.05) and LVEDV (45.4ml vs.38.8ml, P<0.05) were increased progressively 6 hours after CME, while LVEF was decreased oppositely (55.5% vs.60.6%,.P<0.05). One week later, the value of LVEF in CME group was still higher than that in sham-group (56.4% vs. 62.1%, P<0.05).The serum levels of TGF-β1 and troponin T began to increase at 2nd hour after CME. TGF-β1 maintained one week at least, while troponin T was decreased significantly one week after CME. The serum levels of TNF-a and IL-6 were increased at 2nd and 6th hour, respectively. Both of them returned to the base level after one week.It was also demonstrated that there were positive correlation between serum level of TGF-β1 and LVESV (r=0.409) and LVEDV (r=0.532), while negative correlation between TGF-β1 and LVEF (r=-0.438). As a biomarker of cardiac injury, troponin T also had the similar correlation with cardiac function after CME. However, there were no relationship between TNF-a and cardiac remodeling.The mRNA and protein expression of TGF-β1 and Smad3 were enhanced in anterior myocardium one week after CME, which were corresponded to the expression of collagen.Conclusions:Cardiac remodeling could be initiated and progress early after CME, especially, the decrease of cardiac syotolic function. This remodeling could be associated with the expressions of TGF-β1 and Smad3. Part 2Mechanism of myocardial apoptosis induced by TNF-αon the progress of cardiac systolic dysfunction after CMEBackground:It had been demonstrated that TNF-αplayed an important role in the cardiac dysfunction after coronary microembolization (CME). However, it was unclear about the presence of apoptosis after CME and whether TNF-αinduced apoptosis involved in cardiac dysfunction after CME.Objective:This study was designed to demonstrate myocardial apoptosis after CME, and clarify the effect of adalimumab (monoclonal anti-human TNF-αantibody) in protecting the cardiac function through decreased the progress of myocardial apoptosis induced by TNF-α.Methods:Sixteen mini-pigs divided by three groups were studied in this research. CME was performed by intra-coronary infusion of 42μm-microspheres into left anterior descending artery. CME group (n=8), intracoronary received 10ml saline before CME; Therapy group (n=5), intracoronary received 2mg/kg adalimumab 20 minutes before CME; Sham-operation group (n=3), received 10ml saline without CME.Tissue Doppler Imaging (TDI) was performed at baseline,6th hour and one week after CME or sham-operation. This detection included the systolic peak velocity (S wave). The serum level of TNF-αwas detected by ELISA, while myocardial expression of TNF-αwas detected by western blot and immunohistochemistry. Myocardial apoptosis was detected by using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining. In addition, the caspase3 mRNA was analyzed by Realtime-PCR.Results:Compared with the results of TDI in the sham-operation group, systolic peak velocity was significantly decreased in the CME group (1.20cm/s vs.1.50cm/s, P<0.01) at lweek after operation, although there was no significant difference between sham-group and CME group at 6th hour after operation (1.51cm/s,1.45cm/s, P>0.05). In adalimumab-treated group, systolic peak velocity at 1 week after CME was ameliorated greatly (1.39cm/s vs.1.42cm/s, P>0.05).The serum level of TNF-αin CME group was increasd at 2nd hour after operation, and returned to basic level one week later. Intra-coronary injection of Adalimumab could not change this trend. The expression of TNF-αmRNA and protein level in anterior wall was significantly higher than those in sham-operation group. In addition, the total number of apoptosis nucleus was increased significantly (22.0±3.0 vs.3.0±2.0, P<0.01). Intra-coronary injection of adalimumab could reduce the total number of apoptosis nucleus (12.0±4.0 vs.22.0±3.0, P<0.01), although the expression of TNF-αmRNA and protein level were similar between CME group and TNF-αantibody-treated group.Conclusions:Myocardial apoptosis induced by TNF-αwas involved in the progress of cardiac dysfunction after CME. Intracoronary injection of TNF-αantibody before CME could alleviate the impairment of cardiac dysfunction.Part 3Risk factors for elevated troponin T after elective percutaneous coronary intervention and its relations to serum level of TNF-α Background:Elevation of troponin following routine percutaneous coronary intervention (PCI) has been found to be predictive of both short- and long-term major adverse cardiovascular events. Troponin elevation might be associated with thrombosis in stents, occlusion of side vessels, coronary artery spasm, non-reflow, reduced TIMI tissue myocardial perfusion grade and coronary microembolization. However, there was little evidence about the risk factors of elevated troponin T after elective PCI.Obejective:We designed this study to clarify the clinical risk factors of elevated troponin T after elective PCI. In order to seek a novel clinical biomarker of coronary microembolization, the relation between troponin T and TNF-a was also analysed at the the same.Methods:From April to December in 2010, a total of 167 patients with chest pain or chest distress were admitted for coronary angiography and intervention. Clinical factors (such as gender, age, hypertension, diabetes and so on), laboratory tests (such as serum creatinine, cholesterol and so on) and procedural factors (such as age, hypertension, cholesterol, number of stenosed vessels, number of stents implanted this time and Gensini score) were analysed between patients with elevated troponin T and normal troponin T after stents implantation.Results:A total of 167 patients with an average of 64.2±9.8 years were enrolled in our study, including 123 males and 44 females. Preprocedural serum level of troponin T, creatine kinase and CK-MB were normal. We did not find the phenonmenon of thrombosis in stents, occlusion of side vessels, coronary artery spasm, non-reflow after stent implantation by coronary angiography. Patients were divided into two groups:one with elevated troponin T after PCI (n=59), and the other with normal troponin T (n=108).After analyzed by the Student’s t and Chi-squre test, we found that age, hypertension, cholesterol, number of stenosed vessels, number of stents implanted this time and Gensini score were risk factors of elevated troponin T after elective PCI. After multivariable analysis of logistic test, we found that age, hypertension, cholesterol, number of stenosed vessels and number of stents implanted this time were the independent risk factors of elevated troponin T. We also found that there was a positive relation between serum level of troponin T and TNF-a (r=0.493, P<0.01).Conclusions:Age, hypertension, cholesterol, number of stenosed vessels and number of stents implanted this time were the independent risk factors of elevated troponin T after elective PCI. There was a positive relation between serum level of troponin T and TNF-a, which could be another biomarker of coronary microembolization. |
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