Identification of a single nucleotide polymorphism indicative of high risk in acute myocardial infarction.

Background & objectives: Acute myocardial infarction (AMI) is a major health concern in India. The aim of the study was to identify single nucleotide polymorphisms (SNPs) associated with AMI in patients using dedicated chip and validating the identified SNPs on custom-designed chips using high-throughput microarray analysis. Methods: In pilot phase, 48 AMI patients and 48 healthy controls were screened for SNPs using human CVD55K BeadChip with 48,472 SNP probes on Illumina high-throughput microarray platform. The identified SNPs were validated by genotyping additional 160 patients and 179 controls using custom-made Illumina VeraCode GoldenGate Genotyping Assay. Analysis was carried out using PLINK software. Results: From the pilot phase, 98 SNPs present on 94 genes were identified with increased risk of AMI (odds ratio of 1.84-8.85, P=0.04861-0.003337). Five of these SNPs demonstrated association with AMI in the validation phase (P=0.05). Among these, one SNP rs9978223 on interferon gamma receptor 2 [IFNGR2, interferon (IFN)-gamma transducer 1] gene showed a significant association (P=0.00021) with AMI below Bonferroni corrected P value (P=0.00061). IFNGR2 is the second subunit of the receptor for IFN-gamma, an important cytokine in inflammatory reactions. Interpretation & conclusions: The study identified an SNP rs9978223 on IFNGR2 gene, associated with increased risk in AMI patient from India.

Peripheral Blood Mononuclear Cell ABCA1 Transcripts and Protein Expression in Acute Myocardial Infarction.

BACKGROUND: ATP binding cassette transporter-A1 (ABCA1) facilitates the formation of high density lipoprotein (HDL). HDL due to its anti-atherosclerotic, anti-inflammatory and anti-thrombotic activities provides protection against atherothrombosis or myocardial infarction (MI). The aim was to investigate the role of peripheral blood mononuclear cell (PBMNC) ABCA1 expression in MI. METHODS: The participants comprised 29 males with acute MI (AMI) and 20 healthy controls. AMI patients were normotensive, not on statins, with triglycerides < 200mg/dl and categorized into AMI with type 2 diabetes (T2DM) (N = 12) and without T2DM (N = 17). The PBMNC ABCA1 mRNA transcripts were analysed by quantitative real-time polymerase chain reaction (qRTPCR) and protein by enzyme linked immunosorbent assay (ELISA). RESULTS: PBMNC ABCA1 mRNA transcript and protein levels were not significantly different in AMI patients or when sub-grouped into with/without T2DM, as compared to controls. ABCA1 protein correlated positively with HDL-cholesterol (r = 0.655, p = 0.021) in AMI patients with T2DM and negatively with age (r = - 0.525, p = 0.031) in AMI patients without T2DM and it was more strongly associated in latter group with smoking and alcohol habit. CONCLUSION: In the present study, the effects of metabolites of diabetes and ischemia were observed on PBMNC ABCA1 protein and thus on HDL-C in AMI patients. Further influence of risk factors such as smoking and alcohol consumption observed in the present study can be evaluated in larger sample size. The control of these cardiovascular associated risk factors may increase stability of PBMNC ABCA1 protein and thus HDL-C levels.

Polymorphisms of MDR1, CYP2C19 and P2Y12 genes in Indian population: effects on clopidogrel response.

AIMS/OBJECTIVE: Influence of genetic variations on the response of clopidogrel, an antiplatelet drug is implicated. In the present study, the prevalence of single nucleotide polymorphisms of MDR1 (C3435T), CYP2C19 [CYP2C19*2 CYP2C19*3, CYP2C19*17] and P2Y12 (i-T744C) in Indian population and their effects on clopidogrel response was analyzed. METHODS AND RESULTS: To analyze the prevalence of polymorphisms, 102 healthy individuals were recruited. Clopidogrel response was assessed by ADP induced platelet aggregation in clopidogrel naïve acute myocardial infarction (AMI) patients (n = 26) screened from 100 AMI cases, before loading dose of 300 mg, at 24 h before next dose and 6 days after on 75 mg per day and platelet aggregation inhibition (PAI) was calculated between these time intervals. Genotyping was carried out by PCR-based restriction enzyme digestion method for C3435T of MDR1 and i-T744C of P2Y12, by multiplex PCR for CYP2C19*2 (G681A) and CYP2C19*3 (G636A) and by nested PCR for CYP2C19*17 (C806T). The effect of the above mentioned genetic variations on PAI was analyzed. Variant allele of CYP2C19*3 was not observed while the prevalence of 3435T of MDR1 (0.524), CYP2C19*2 (681A, 0.352); i-744C of P2Y12 (0.088), as well as wild type allele CYP2C19*17 (C806, 0.897) associated with decrease clopidogrel response were observed. Trend toward poor response to clopidogrel was observed at 24 h with the variant genotypes of CYP2C19*2 and i-T744C of P2Y12 as compared to wild type. CONCLUSION: The present study did show a trend toward impaired response of clopidogrel to inhibit platelet aggregation with variant genotypes of CYP2C19*2 and iT744C of P2Y12 compared to respective wild type genotype at 24 h.

Levels of cathepsins in acute myocardial infarction.

AIMS/OBJECTIVE: Over expression of matrix degrading enzymes have been implicated in plaque destabilisation and rupture. Cathepsins associated with extracellular matrix breakdown make them intriguing suspects. The aim of the study was to analyse peripheral levels of cathepsin B and cathepsin K and their inhibitor cystatin C during acute myocardial infarction (AMI). MATERIALS AND METHODS: Study population included AMI patients at acute event (AMI group, n=48), stable angina patients (stable angina group n = 17), and healthy individuals (Control group, n=31). Cathepsin B, cathepsin K, cystatin C, and matrix metalloproteinases (MMP)-9 were analysed by enzyme-linked immunosorbent assay (ELISA) method. RESULTS: Cathepsin B (45.9%) and cathepsin K (92.31%) at acute event of myocardial infarction (AMI group) increased (P=0.001) while cystatin C decreased marginally (12.5%) as compared to controls. Stable angina group, demonstrated only marginal reduction in all the parameters studied as compared to controls. CONCLUSION: Cathepsin B and cathepsin K can be further evaluated as biomarkers in identifying high-risk individuals for AMI.

Prevalence of VKORC1 and CYP2C9 gene polymorphisms in Indian population and its effect on warfarin response.

OBJECTIVES: The clinical effectiveness of Warfarin is established. Patients require different warfarin dosages to achieve the target therapeutic anticoagulation. The variability of Warfarin dosage is largely genetically determined, and it can be partly explained by the C1173T and G-1639A polymorphisms of vitamin K epoxide reductase complex subunit 1 (VKORC1) which is its target and *2 and *3 allele of Cytochrome P-450 (CYP) 2C9 [CYP2C9] enzyme which metabolizes to its inactive form. Aim of the present study was to determine the prevalence of these variant alleles known to influence the warfarin dose and correlate genotypes with the average INR as well as mean dose of Warfarin required to maintain INR, in the Indian population. METHODS: Study population included 100 healthy individuals and 83 patients operated for Aortic or Mitral Valve replacement and prescribed warfarin thereafter. Of these 83 patients records of INR for the period of six months and mean maintenance dose (stable therapeutic dose) of warfarin required to maintain INR were available for 26 patients. For the remaining patients, apart from their demographic data only maintenance dose was available. Genotyping of above mentioned polymorphisms was carried out by using PCR-based restriction digestion method. RESULTS: Although less as compared to wild type alleles, the variant alleles of CYP2C9*2 and *3 as well as of VKORC1 polymorphisms (C1173T and G-1639A) were observed in our study population. Mean maintenance dose (mg/day) of Warfarin was in the decreasing order of patients as compared to the wild type genotypes for all above mentioned polymorphisms. The decrease in the dose was in the order of heterozygotes for CYP2C9*2 to CYP2C9*3 to C1173T and G-1639A of VKORC1 (P<0.001). There was significant correlation (r=0.51, P<0.001) observed between the dose estimated by pharmacogenetic algorithm of Sconce et al (2005) and actual stable therapeutic dose. INR was high for mutant variants (3.8 to 4) after first dose suggesting that they require decreased mean daily dose of Warfarin. CONCLUSION: In the present study the effect of CYP2C9*2, *3, and VKORC1 (C1173T and G-1639A) genotypes on warfarin dose was observed. However, the genotyping has not been incorporated into daily practice. Perhaps more practical approach would be for clinicians to take genotype information into consideration along with other factors when dosing warfarin.

In search for novel biomarkers of acute coronary syndrome.

Prerequisites for a biomarker to enter clinical routine in acute coronary syndrome (ACS) are several folds. The most important features are that the biomarker can be offered on a routine platform to diagnose and identify high-risk individuals of ACS, provide higher sensitivity and specificity than the ECG in predicting outcome, and should have impact on therapeutic decision making. In recent years, a deeper understanding of the pathobiology of the atherothrombosis as the underlying mechanism of ACS has directed scientific studies towards the evaluation of certain pathogenic components involved in the process as potential biomarkers for the clinical settings of ACS. Under investigations are markers to identify early injury/ischemia, markers for detection of vulnerable plaque, its disruption, of thrombosis and markers for inflammation. The aim of this paper is to review the current contribution of biochemical markers to clinical cardiology and also to discuss some important developments in this field.

Soluble levels of cell adhesion molecules (CAMs) in coronary artery disease.

AIMS: To analyze soluble levels ofcell adhesion molecules (CAM) such as Intercellular CAM (ICAM), vascular CAM (VCAM-1), platelet endothelial CAM (PECAM-1), Endothelial (E)-selectin, and Platelet (P)-selectin in coronary artery disease patients and correlate with degree of severity of the disease. METHODS: Study population included patients who suffered myocardial infarction at presentation (N=49) and those with unstable angina (N=79) and stable angina (N=14). Soluble levels of CAMs were measured by ELISA. RESULTS: At acute event in AMI patients, there was significant rise of soluble (s) E-selectin (4.5 fold, P = 0.001), sVCAM-1 (65.6%, p = 0.001), sPECAM-1 (46.2%, p = 0.02), sP-selectin (42.7%, p = 0.001) and sICAM-1 (20.1%, p = 0.003) as compared to controls. In unstable angina group as compared to AMI there was significant decrease in the levels observed in, sE-selectin (62.7%, p = 0.001), sPECAM-1 (47.5%, p = 0.001) as well as sVCAM-1 (17.9%, p = 0.04) and insignificant decrease with respect to sICAM-1 and no change with respect to sP-selectin levels. Stable angina group as compared to unstable angina group demonstrated no significant difference in sCAMs and the trend with AMI group was similar to that seen between unstable angina and AMI group. Significantly elevated levels of sE-selectin, sVCAM-1 and sPECAM-1 at acute event suggest them to be causal molecules as well as markers of plaque destabilization. Levels of sP-selectin in stable angina were similar to that observed in AMI and unstable angina groups suggesting elevated platelet activation in stable angina as well.

Leucine125Valine (Leu125Val) Gene Polymorphism of Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1) and Myocardial Infarction in Indian Population.

Platelet-endothelial cell adhesion molecule-1 (PECAM-1) has role in atherosclerotic plaque development as well as in thrombosis leading to myocardial infarction (MI). Present study was aimed to analyse the association of PECAM-1 Leu125Val gene polymorphism with MI in Indian population. Subjects included healthy individuals as control (N = 116) and MI patients (N = 100) divided into two groups; MI patients at presentation of the acute event (MI-Group-1, N = 46) and patients with recent event of MI stabilized with treatment 4.5 days from their symptoms (MI-Group-2, N = 54). The difference in the distribution of Leu125Val genotype frequencies of controls and patients did not reach statistical significance. However Leu allele frequency (0.57) was more associated with MI patients as compared to control (0.504). sPECAM-1 levels were significantly elevated in patients at acute event of MI (MI-Group-1) by 44.1% (P = 0.009) as compared to controls and by 95.2% (P = 0.001) as compared to stabilized MI patients (MI-Group-2).

Role of matrix metalloproteinases in coronary artery disease.

AIM: Matrix metalloproteinases (MMPs) contribute both in the formation as well as in the destabilization of atherosclerotic plaque. In the present study we analyzed circulating levels of MMP-7 that acts on chondroitin sulphate a proteoglycan that is particularly abundant in atherosclerotic plaque and MMP-8 which acts on Type I collagen, the synthesis and degradation of which is important for stability of the plaque and correlate with the degree of severity of coronary artery disease (CAD). METHODS: Circulating levels of MMP-7 and MMP-8 and tissue inhibitors of MMP (TIMP) -1 and TIMP-2 were analysed by Enzyme Linked ImmunoSorbent Assay (ELISA7rpar;, in patients with acute myocardial infarction (AMI) at presentation (N=48), acute coronary syndrome (ACS) group (N=227rpar; (on treatment) and stable angina group (N=17) (on treatment). RESULTS: There was significant rise in MMP-8 (88.23%, P=0.001), in AMI group which decreased in ACS treated group 7lpar;15.9%, non-significant) as compared to controls. There was increasing trend of MMP-7 in AMI and ACS group and strong correlation with hsCRP. MMP-7 predominated in stable angina group. There was significant decrease in TIMP-2 in AMI group and TIMP-1 and TIMP-2 in ACS and stable angina group as compared to controls. CONCLUSION: Significant increase in MMP-8 and decrease in TIMP-2 during acute stage of AMI suggests MMP-8 and TIMP-2 are markers for vulnerable plaque independent of hsCRP for AMI. MMP-7 was found to be elevated in stable angina patients and was correlated with hsCRP at acute phase of AMI suggesting persistent at all stages of CAD.

Regeneration of myocardium--dawn of a new era!

The notion of repairing or regenerating lost myocardium via cell based therapies is highly appealing. The identification of adult bone marrow stem cells and their supportive pre-clinical data fueled the interest in utilizing these cells for physiological relevant cardiomyogenesis. Enthusiasm for cardiac regeneration via cell therapy has further increased by many encouraging reports in both animal and human studies. Further intensive research in basic science paralleled with clinical trials may make cardiovascular regenerative medicine a reality in fighting against congestive heart failure, the leading cause of morbidity and mortality associated with loss of functional cardiomyocytes. Here we review the preclinical phase to clinical phase of stem cell therapy for myocardium and provide a brief overview on unresolved issue and mechanistic insight of the repair.

Bone marrow cells for myocardial repair-a new therapeutic concept.

AIM: To assess the safety and feasibility of transfusing autologous bone marrow stem cells (ABMSC) into the culprit coronary artery after an acute anterior wall myocardial infarction (MI) and further to see the ability of ABMSC to promote improvement in Left Ventricular lsqb;LV] function at follow-up. METHODS: In an ongoing phase I clinical trial, twenty-seven patients of uncomplicated acute anterior wall MI treated as per the current practicing guidelines have been included. Among these, seventeen patients received intra-coronary unfractionated ABMSCs from 77ndash;15 days after acute MI (ABMSC group) and ten patients acted as controls. RESULTS: All the procedures carried out were without any complications. After 6 months, cardiac function analysis of ten patients from the ABMSC group by LV angiography and Cardiac Magnetic Resonance Imaging (MRI) demonstrated a significant rise of 12.74% (p = 0.001) and 7.1% (p = 0.001), respectively in the LV ejection fraction [LVEF]. There was an improvement in the LV systolic function wherein LV end systolic volume (LVESV) decreased significanty to 28.75% (p = 0.010) and 16.49% (p = 0.022) by LV angiography and cardiac MRI, respectively. LV end diastolic volume (LVEDV) decreased marginally by LV angiography (p = 0.548) and by cardiac MRI (p = 0.514). Five patients of the control group by LV angiography demonstrated non-significant rise of 1.0% (p = 0.706) in LVEF, 12.79% (p = 0.332) in LVEDV and 22.56% (p = 0.308) in LVESV. By cardiac MRI controls demonstrated significant rise in EF of 3.2% (p = 0.0367rpar; but non-significant fall of only 2.32% (p = 0.812) in LVEDV and 6.47% (p 7equals; 0.508) in LVESV. CONCLUSION: This study shows that intracoronary infusion of ABMSC is safe and feasible after acute MI and shows a favourable trend towards the improvement of LV function and prevention of ventricular remodeling which determines long-term survival.