THE PRESENCE OF ANTI-PHOSPHATIDYLETHANOLAMINE ANTIBODIES IN ACUTE MYOCARDIAL INFARCTION

Acute Myocardial Infarction (AMI) is a clinical man ifestation of coronary atherothrombosis and is the important causes of death. Many factors play a role in AMI. Anti-Phospholipid (aPL) antibodies may act in the induction of immunological response lead ing to the development of AMI. AntiPhosphatidylethanolamine (aPEA) antibody has been d etected in various autoimmune diseases and anti-phospholipid antibody syndrome. The study of a PEA antibody in AMI might shed light on etiologic mechanisms in the pathogenesis of coronar y atherothrombosis and AMI. This study was aimed to evaluate whether prevalence of aPEA antibo dies, in patients with AMI and to analyze their relationship with traditional cardiovascular risk f actors. The prevalence of aPEA IgG and IgM in a well characterized group of patients with AMI as a c se group and in age and sex matched healthy subjects as a control group. Sera from two groups w ere tested to evaluate the presence of aPEA IgG and IgM isotypes by ELISA method. The frequencies o f p sitive test for aPEA IgG were 12.22 and 2.22% among patients and controls respectively with significant difference (p = 0.007). The aPEA IgM frequencies were 3.33 and 0.00% in patients and the controls, with significant difference (p = 0.005). According to the results of this study, aPEA antibo dies have a role in AMI, independent risk factors for AMI, which may represent a link between autoimm unity and coronary atherothrombosis. Further studies with larger sample size of patients and hea lt y people are needed to explore the role of aPEA antibodies in coronary atherothrombosis.


INTRODUCTION
Acute Myocardial Infarction (AMI) is a clinical manifestation of coronary atherothrombosis and among Cardiovascular Diseases (CVD) is the important causes of morbidity and mortality (Upaganlawar et al., 2011).
Arterial thrombosis (myocardial infarction, cerobrovascular accident, angina) is the collective result of environmental factors and personal Science Publications

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predispositions. Factors such as low serum adiponectin (Shojaie et al., 2009a) and low annexin V levels (Shojaie et al., 2009b) and infectious diseases such as Mycoplasma pneumonia (Pourahmad et al., 2009) are a part of involving factors in AMI. It has been demonstrated that the immunopathological such as anti-beta2 glycoprotein-I antibody (Shojaie et al., 2011), Anti-Phosphatidylserine antibodies (Jahromi et al., 2013) and Inflammatory processes (Jahromi et al., 2010a) have important roles in the initiation and development of AMI.
It seems that several subspecificities of antiphospholipid antibodies may occur in the patients with MI and some evidence suggest that these antibodies may contribute to the development of MI (Vaarala, 1998). However their pathogenic mechanisms in AMI are still matter of research.
Venous thrombosis is the most common vascular event; however, one third patients with Antiphospholipid Syndrome (APS) presents arterial thrombosis (myocardial infarction, cerobrovascular accident, angina) during the progression of the disease (Matsuura and Lopez, 2008).
Elevated serum levels of antiphospholipid antibodies along with thromboembolic complications involving arterial blood vessels (Shojaie et al., 2011;Jafarzadeh et al., 2011) or with pregnancy morbidity (miscarriages and fetal loss) represent the major features of APS (Jahromi et al., 2010b).
It is notable that genetic factors as well as other traditional risk factors such as smoking, hypercholesterolemia, diabetes mellitus and hypertension may contribute to IHD development and these parameters differ among various population. Even though there are a few studies on the association of some autoantibodies with AMI, more epidemiological data are needed to confirm their significance as independent risk factors in CVD. Furthermore, the data on the correlation of autoantibodies with traditional risk factors of AMI is scarce.
Henceforth, present case control study was undertaken to evaluate the serum levels of anti-Phosphatidylethanolamine (aPEA) antibodies (IgG and IgM) in Iranian patients with AMI and also to illuminate their association with traditional risk factors of this disease.

Subjects
A total of 90 consecutive patients (aged 41-67 years) with AMI including 67 men and 23 women who were admitted to Peymanieh Hospital of Jahrom (a southwest city of Iran), were enrolled to this casecontrol study.
AMI was diagnosed by the presence of two of the following criteria: (i) prolonged chest pain compatible with AMI, (ii) typical ECG changes, (iii) rising of cardiac enzymes such as creatine kinase and lactate dehydrogenase (Antman et al., 2008).
Exclusion criteria were valvular heart disease, surgery, trauma during the prior month, cardiomyopathy, liver disease, renal failure, arthritis, malignant diseases, other inflammatory diseases (such as SLE and RA) and oral anticoagulant therapy. In patients with AMI, the serum concentration of Anti-PC antibodies was measured during 3-5 days after admission.
An age, sex and other CAD risk factors such as Hypertension (HTN), Diabetes Mellitus (DM) and Hyper Lipidemia (HLP) matched group (n = 90) with similar geographic and socioeconomic backgrounds without any ischemic heart disease were used as a control group. All control subjects were basically healthy, with no acute or chronic illnesses and did not use any drugs. The healthy control group was recruited from blood donors attending Jahrom Blood Transfusion Center.
The study protocol was approved by research ethics committee of Jahrom University of Medical Sciences and informed consents were obtained from all participants before enrollment. The patient or his/her legal representative provided written informed consent.
Historical, demographic and clinical data were obtained through a review of medical records and Science Publications OJBS interviews with patients and their families. The risk factors for myocardial infarction were as following: (a) age, sex; (b) history of hypertension (diagnosis confirmed when the systolic or diastolic pressures were >160 or 95 mmHg, respectively, or when the patient was using antihypertensive medication) 12; (c) smoking, according to the criteria of the British Council for Medical Research; (d) history of heart disease (atrial fibrillation or coronary heart disease, defined as previous myocardial infarction, angina, or revascularization procedure); (e) history of diabetes mellitus, according to the medical history or the use of insulin or an oral anti-diabetes drug; (f) hypercholesterolemia, based on total cholesterol >200 mg/dL, LDL-cholesterol >130 mg/dL, or total cholesterol/HDL-cholesterol ratio >5 (Donahue et al., 1988).
Blood samples (5 cc) were obtained by venipuncture from the patients immediately after admission before starting any IV medications by skilled personnel. Blood samples were centrifuged and frozen within, at most, 2 h after collection and stored at -20°C until laboratory testing.
Enzyme-immunoassay kits (BINDAZYME Human Anti-phosphatidylethanolamine IgG/IgM Combi EIA Kit, MK077, manufactured by: The Binding Site Ltd., Birmingham, U.K.) were used for the detection of IgG or IgM aPEA by indirect solid phase enzyme immunoassay (ELISA) as suggested by the ELISA kit manufacturer.
Statistical analyses were performed by SPSS (version 17; SPSS, Inc., Chicago, IL). Data were expressed as mean ± SD. Continuous variables with little-to-mild skewness were summarized as mean ± SD and compared using Student's t-test.

RESULTS
The demographic and clinical characteristics of the study groups, as well as laboratory variables are shown in Table 1.
There was no significant difference between the two groups regarding the following variables: age, sex, HTN, DM, LDL, HDL, total cholesterol and TG.
The association between positive aPEA IgG and IgM tests and selected cardiovascular risk factors were examined in this study.
There was a significant association between positive aPEA IgG and IgM tests with hypertension. But there was not found any significant association between positive aPEA IgG and IgM tests with Type-I DM, Type-II DM, age, sex, LDL, HDL, TG, total cholesterol and adjusted smoking.
There was not found significant difference between positive aPEA IgG test in patients with STEMI and those with NSTEMI (74.40% Vs 24.80%), (p = 0.154) and also there was not found significant difference between positive aPEA IgM test in patients with STEMI and those with NSTEMI (67.10% Vs 23.70%), (p = 0.434).

DISCUSSION
The results of the present study showed that the prevalence of positive aPEA IgG and also IgM in patients with AMI were significantly higher than that detected in healthy control group. These associations were independent of traditional risk factors. Other aPLs antibodies have been reported to have association with CAD and AMI (Shojaie et al., 2011;Jafarzadeh et al., 2011;Greco et al., 2010). The result of present study and other researches (Shojaie et al., 2011;Jafarzadeh et al., 2011;Urbanus et al., 2009;Jahromi et al., 2013;Sanmarco et al., 2007) are consistent with current concepts on the immune pathogenesis of atherosclerosis. However, the precise mechanisms of involvement of aPEA antibodies in the pathogenesis of AMI remain to be determined.
The presence of increased titers of aPEA antibodies in our patients were independent factors for AMI and were not associated with any of the conventional cardiovascular risk factors (smoking, hypertension, mellitus and hypercholesterolemia). These results are in accordance with the results of previous studies (Shojaie et al., 2011;Jahromi et al., 2010c;2013).
In this study there was a significant association between aPEA IgG with HTN in the case and the control groups. These results suggest that aPEA IgG are independent of these variables.
As there were not significant differences between positive aPEA antibodies test in patients with STEMI and those with NSTEMI, it can be concluded that aPEA IgG and IgM do not participate in kind of AMI (STEMI Vs NSTEMI). But, unfortunately, there were not found any data indicating association of aPEA IgG and IgM with these parameters to compare the results.

CONCLUSION
These results show an association between AMI and high prevalence of positive tests for aPEA IgG and IgM. The results of this study in parallel with the data from other studies about oyher anti-phospholipid antibodies (Shojaie et al., 2011;Jafarzadeh et al., 2011;Urbanus et al., 2009;Jahromi et al., 2013;Sanmarco et al., 2007) support the potential important role of aPL antibodies in AMI.
According to the result of this study, it seems that aPEA antibodies are associated with AMI and may involve in the development of AMI.
Clinical trials for the prevention of myocardial infarction and atherosclerosis in patients with antiphospholipid antibodies are recommended. Further studies with larger sample size of patients and healthy people are needed to explore the exact role of aPEA IgG and IgM in AMI. To achieve this, these kinds of studies should be planned as international multicenter researches.

ACKNOWLEDGEMENT
This study was completely financed by Jahrom University of Medical Sciences. The authors are grateful to the patients and the control individuals who accepted to enter this study.