Studying On Potential Biomarkers Of Acute Early Ischemia Myocardium And Its Significance

BackgroundWorld health organization reported that, ischemia heart disease will be the second threat ofcivil health in 2030.Among all the causes of ischemia heart disease, ischemia myocardiuminduced by coronary artery infarction must be the most important one. The increasing prevalenceof coronary artery disease (CAD) with high mortality and morbidity in our nation has been oneof the most fatal causes of sudden cardiac death (SCD). During the past decade, the developmentin mechanics and therapy of cardiovascular diseases has been explored. Although the diagnosisand treat of acute myocardial infarction (AMI) has been improved rapidly, AMI remains a severedisease in the world with high mortality, and more and more forensic medical cases results fromSCD were identified. Forensic pathologist found that when the important area is ischemia, suchas ischemia of ventricular septal, could lead to sudden cardiac death. About 1/4 CAD patientshave not pectoral syndrome and half of them do not show electrocardiogram changes. Whereas,SCD cases caused by early myocardial ischemia are often deficient of typical pathological andmorphological changes, and this condition makes difficulty in identifying this kind of cases inforensic medicine. Some of biomarkers of early myocardial ischemia, such as CK-MB, CTn,MHb and H-FABP, etc. are considered as sensitive indicators. Especially CK-MB and CTn arepresumed as golden standard in diagnosing of AMI in clinical, but it not fit for identifying casesof AMI in forensic medicine for they are dramatically increased 3-4hours later since AMI, eventhough, MHb and H-FABP are reported appearing poor specificity in identifying AMI. Accountof that, finding more sensitive early myocardial ischemia biomarkers seems to have moreimportant significance.Understanding the molecular changes after the cardiac ischemia is pivotal for the diagnosisof reliable biomarkers of ischemia cardiac diseases. Our research group had identified somespecific molecular related to myocardial ischemia in our prophase study by SSH, that iscathepsin-L(CTSL), Sjogren syndrome antigen B(SSB)、basigin(BSG) and unc-45 homologA(Unc45a), but their altering tendency according with time in ischemia myocardium and themechanism are still unknown and needed profound research. There, the experiments are designedas follow: firstly, find out the molecular have time tendency in ischemia myocardium throughreal-time PCR; and then, their proteidic expression in ischemia myocardium are observed andverified by immunohistochemistry to explore their contribution in identifying ischemia heartdisease as biomarkers preliminarily. Objectives1. To observe the expression of four selected molecular in early ischemic myocardium and findout the tendency with time.2. To evaluate their contribution in ischemia heart disease occurred in forensic medicine.MethodsReal-time polymerase chain reaction (RT-PCR) technique was applied for detecting theexpression of the four selected molecular mRNA in EIM and NIM of rats at 15min, 30min, 1hand 2h post myocardial ischemia, and in sham operation(SO) group. Thirty six heart samples ofadult human fixed by formalin were collected for detecting the expression of proteins byimmunohistochemical(IHC) staining.Results1. Expression of all of the four molecular mRNA have changed in ischemia myocardium. CTSLmRNA gradually increased since myocardial ischemic, however, BSG mRNA decreasedwithin 1h since myocardial ischemia and then rebounded to the incipient. Other twomolecular appeared no tendency.2. Compared with NIM, SO and control group, no significant differences of CTSL mRNAexpression were observed in EIM within 15min. CTSL mRNA expression increased to 1.4folds at 30min, 3.1 folds at 1h,and 4.5 folds at 2h(p<0.05). No difference was observedamong other three groups(p>0.05). Expression of BSG mRNA decreased after 15min whenmyocardium ischemia occurred; compared with SO, it was of 0.5 folds when 1h(p<0.05), andrebounded to SO level when 2h.3. CTSL augmented expression was detected with IHC in 20 ischemia hearts withⅢ~Ⅳcoronary stenosis after autopsies of SCD cases, while no positive staining was observed in 16normal hearts from corpse of mechanical injury death.ConclusionOur investigation firstly indicated that CTSL mRNA increased expression could be detectedin early ischemia myocardium of rat, and exhibited positive correlation with time. Theexpression of CTSL protein increased in fixed human ischemia myocardium from cases of SCD,and displayed obvious specificity. CTSL could be detected at early ischemic myocardium of rats,and CTSL was intensely expressed in human ischemia hearts from SCD than mechanical injurydeath and may serves as a biomarker of heart ischemia and SCD.