Soluble Lectin-Like Oxidized LDL Receptor-1 and High-Sensitivity Troponin T as Diagnostic Biomarkers for Acute Coronary Syndrome
Soluble Lectin-Like Oxidized LDL Receptor-1and High-Sensitivity Troponin T as Diagnostic Biomarkers for Acute Coronary Syndrome Prepared by Nagi Abdalla Supervisors Prof. Kim Dong Hyun Prof. Jea Gook Shin
Project objectives (what, why and how) • About Cardiovascular disease and Acute Coronary Syndromes.. • Importance and clinical impact.. • The road to biomarker discovery..
Acute Coronary Syndromes• Definition..• The triad: – STEMI – NSTEMI – Unstable angina• Prognosis in Acute coronary syndromes..
Method overview• Biomarker type approach: – Screening: • study of risk factors – Diagnostic: • Mechanism of vascular endothelial dysfunction and injury • Mechanism of ischemia in cardiac cells – Prognostic: • Cell injury (reversible/irreversible) • Long term observation and prolonged exposure to ischemia• Methodological approach: – Analysis: (global and target based approach) • Use of proteomics • Use of metabolomics – Clinical: • Study of patients at risk • Study of patients during the event • Study of patients after injury
Introduction• Problems with current cardiac biomarkers – CK-MB – Cardiac Troponins and high sensitivity Troponins• Other conditions mimicking ACS: – coronary spastic angina pectoris (CSA), – pulmonary thromboembolism, – perimyocarditis – (pericarditis and/or myocarditis) – takotsubo cardiomyopathy.
About Lectin-like oxidized LDL receptor-1 (LOX-1)• LOX-1 receptor is present in: – Surface of intimal smooth muscle cells (VSMC) – Lipid-laden macrophages (in advanced human atherosclerotic plaques)• The expression of this receptor is induced by factors related to atherogenesis and plaque vulnerability such as: – Proinflammatory cytokines – Angiotensin II – Hyperglycemia – Oxidized LDL• In the vulnerable plaque stage; sLOX-1 is released into the circulation after being cleaved by protease enzymes (disintegrin/metalloproteinase)• These evidence points out that sLOX-1 is a biomarker for plaque rupture or plaque instability
About Lectin-like oxidized LDL receptor-1 (LOX-1) (cont.)• a receptor for atherogenic oxidized LDL• abundantly expressed in advanced human atherosclerotic plaques• soluble LOX-1 (sLOX-1) is regarded as a marker of plaque rupture or instability..• previous studies revealed the diagnostic value of sLOX-1 for early-stage ACS in which conventional troponin T (TnT) was unable to provide a diagnosis
Aim of this study• evaluate the diagnostic value of sLOX-1 and hs-TnT for patients in the ER with chest symptoms & ECG abnormalities suggestive of ACS.
Study Population• Time line April2008/Dec.2009• Number of patients: 200 (160 males-40 females)• Mean age: 65±12 years• Presentation: ER within 48hrs with chest symptoms and ECG abnormalities suggestive of ACS (diagnosis within first 3 hours of onset of symptoms were defined as early)• ACS parameters: – prolonged chest pain >20mins – Coronary lesion seen on coronary angiography – Diagnosis of NSTEACS and STEACS was according to ECG findings• Exclusions: – Patients with acute/chronic renal disease under going renal replacement therapy. – Patients with cardiogenic shock on percutaneous cardio-pulmonary support system.
Measurement of sLOX-1 & hs-TnT sampling methods and biomarker measurement• Collection and treatment of samples: – Blood samples obtained in ER. – Plasma separated by centrifugation. – Stored in -80ºC.• Measurement tools: • For plasma sLOX-1: – measured by Chemiluminescent enzyme immunoassay (CLEIA) using anti-human LOX-1 monoclonal antibodies (modified ELISA). – Intra-and inter-assay coefficients of variation (CV) where 4.4-6.5% and 4.0-6.1% respectively – Lower limit of detection was 8.0pg/ml • For serum hs-TnT: – Measured by Electrochemoluminescence immunoassay – Intra- and inter-assay CV were 0.5-5.7% and 1.4-3.0% respectively – Lower limit of detection was 0.003ng/ml
Statistical Analysis• Variable groups of data obtained for sLOX-1, hs- TnT, CK-MB at different time intervals• Analytical tools used for comparison are: – Student’s T-test for 2 groups comparison – 1-way ANOVA for 3groups comparison – Mann Whitney U test 2 groups with unequal distribution of time intervals – Kruskal-Wallis test 3 groups with unequal distribution of time intervals – Spearman’s rank correlation test comparing both sensitivity and specificity of sLOX-1 & hs-TnT for diagnosing ACS – Receiver-operating characteristics (ROC curve) using non-ACS subjects as negative controls..• Software used: SPSS software package• Ethically approved and consents collected
Comparison of sLOX-1 & hs-TnT levels (cont.) sLOX-1 hs-TnT
II. Diagnostic overall Value of sLOX-1 & hsTnT for ACS
III.Comparing the diagnostic value of sLOX- 1 & hs-TnT for early stage of ACS (within 3h of the onset of symptoms)
IV. Evaluating the Diagnostic Value of sLOX-1 for ACS in patients with hs-TnT negative ACS• 2 subgroups: I. hs-TnT negative ACS (<0.0205ng/ml) II. hs-TnT postive ACS (>0.0205ng/ml)• Findings: – Gender and the prevalence of risk factors were comparable in the 2 groups except that patients were younger in the 1st subgroup – Plasma sLOX-1 levels were significantly higher in the 1st subgroup – Peak CK-MB levels were also comparable between these subgroups & Serum creatinine levels were significantly higher in the 1st subgroup – Time intervals from the onset of chest symptoms to ER arrival were significantly shorter in the 1st subgroup
Evaluating the Diagnostic Value of sLOX-1 for ACS in patients with hs-TnT negative ACS (cont.) Negative reference: hs-TnT-negative non-ACS subgroup
V. Evaluating the Diagnostic Value of hs-TnT for ACS in Patients with sLOX-1 negative ACS• 2 subgroups: I. sLOX-1 negative ACS (<131.7pg/ml) II. sLOX-1 positive ACS (>131.7pg/ml)• Findings: – Gender and the prevalence of risk factors were comparable in the 2 groups except that smokers were more prevalent in the 2nd subgroup. – patients with STEACS were more prevalent in the 2nd subgroup. – Serum hs-TnT and creatinine levels were comparable between these subgroups & Peak serum CK-MB levels were higher in the 2nd subgroup – Time intervals from the onset of chest symptoms to ER arrival were significantly shorter in the 2nd group.
Evaluating the Diagnostic Value of hs-TnT for ACS in Patients with sLOX-1 negative ACS (cont.) Negative reference: sLOX-1-negative non-ACS subgroup
• About AMI..• Troponin as a specific cardiac biomarker..• Recent studies revealed insufficiency of tropnin as a biomarker in early stage ACS (within 3 h of onset) the cause is mainly related to the kinetics of cardiac troponins during the acute stage of ACS• sLOX-1 is regarded as a biomarker for plaque rupture or plaque instability and expected to precede the release of myocardial damage markers, including cardiac troponins superior in diagnosis in early stage• The development of high sensitivity assay for early detection of Troponins was associated with decreased specificity other non-ACS conditions shared the same clinical presentation and elevated troponins with or without cardiac ischemia
• Other markers of cardiac damage include: – Myoglobin – Heart-type fatty acid-binding protein (H-FABP)These markers are also present in early stage AMI but their diagnostic specificity is of the same as troponins since they share the same mechanism.• Therefore, sLOX-1 may be a better candidate since it has a different mechanism involving plaque instability and rupture• By using non-ACS patients as negative reference; this study showed for the first time the ability of sLOX-1 to detect ACS during the acute stage in cases with no increased hs-TnT levels• Although the combination of sLOX-1 & hs-TnT are useful in diagnosis of ACS; their diagnostic specificity remains insufficient both markers were found elevated in non-ACS conditions: – Some types of coronary vasospasm – Thrombus formation in the pulmonary artery – Synovial fluid rheumatoid arthritis (Arthritis & Rheumatism art.33452)
• sLOX-1 levels were found higher in STEACS than NSTEACS – Short arrival interval in STEACS – Different plaque characteristics (rupure/erosion)• Peak CK-MB values were higher in patients with sLOX-1>131.7pg/ml indication of severity• sLOX-1 can be an alternative to detect vulnerable plaques (less invasive) current methods are considered invasive: – Multidetector row CT – IV U/S• sLOX-1 is found reduced in patients on statins, Angiotensin II receptor blockers, body weight reduction it can be used as a tool to monitor therapeutic effects
• sLOX-1 is a biomarker of plaque rupture or vulnerability• hs-TnT is a biomarker of myocardial damage using either one of them alone appears to be insufficient for diagnosing ACS in the real clinical setting therfore, the diagnostic accuracy would improve by using the combination of both..• sLOX-1 has its limitations: since it is also elevated in other atherosclerotic conditions like: – Ischemic stroke – Aortic athersclerosis – Peripheral arteriosclerosis obliterance• Further studies are need to clarify the mechanisms of sLOX-1 elevation