Expression of matrix metalloproteinases-12 in ST-segment elevation myocardial infarction: A case-control study

Matrix metalloproteinases in coronary artery disease and myocardial infarction

Cardiovascular diseases (CVDs) remain the leading cause of death worldwide. Most cardiovascular deaths are caused by ischaemic heart diseases such as myocardial infarction (MI). Hereby atherosclerosis in the coronary arteries often precedes disease manifestation. Since tissue remodelling plays an important role in the development and progression of atherosclerosis as well as in outcome after MI, regulation of matrix metalloproteinases (MMPs) as the major ECM-degrading enzymes with diverse other functions is crucial. Here, we provide an overview of the expression profiles of MMPs in coronary artery and left ventricular tissue using publicly available data from whole tissue to single-cell resolution. To approach an association between MMP expression and the development and outcome of CVDs, we further review studies investigating polymorphisms in MMP genes since polymorphisms are known to have an impact on gene expression. This review therefore aims to shed light on the role of MMPs in atherosclerosis and MI by summarizing current knowledge from publically available datasets, human studies, and analyses of polymorphisms up to preclinical and clinical trials of pharmacological MMP inhibition.

Immunohistochemical characteristics of coronary thrombi in ST-elevation myocardial infarction

Background and aims

The dynamics and implications of intracoronary thrombus constituency in patients with ST-segment elevation myocardial infarction (STEMI) are not fully understood. We evaluated the expression of CD34, CD61and factor VIII surface markers in thrombi of patients with STEMI and its association with clinical and angiographic characteristics and major adverse cardiovascular events (MACE).

Methods

Patients presenting with STEMI undergoing aspiration thrombectomy during primary percutaneous coronary intervention (pPCI) were included. Morphological, histopathological and immunohistochemical aspects of thrombi were assessed by two pathologists blinded to clinical variables and outcomes.

Results

The mean age of the 245 patients included was 58 ± 12 years old, and 70 % were men. Regarding the thrombi microscopic patterns, 61 % were classified as recent, 20 % as lytic and 19 % as organized. There were higher levels of the CD61 index in patients with a history of heart failure. Smokers presented lower CD61 positive cells and CD61 index, but this association did not remain significant after multivariable analysis. There was an inverse correlation between CD61 positive cells and CD61 index with the time from onset of pain to the first medical contact, but no other significant association amongst clinical characteristics and antigenic expression. There was higher expression of the CD61 antigen in patients with in-hospital MACE, but statistical significance was borderline (p = 0.06).

Conclusions

In this cohort of patients with STEMI, immunohistochemistry of coronary thrombus showed a significantly higher platelet content in patients with previous heart failure and a trend in those with in-hospital MACE. Thrombus' platelet content was inversely related to ischemic time.

Matrix Metalloproteinases as Biomarkers of Atherosclerotic Plaque Instability

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases responsible for tissue remodeling and degradation of extracellular matrix (ECM) proteins. MMPs may modulate various cellular and signaling pathways in atherosclerosis responsible for progression and rupture of atherosclerotic plaques. The effect of MMPs polymorphisms and the expression of MMPs in both the atherosclerotic plaque and plasma was shown. They are independent predictors of atherosclerotic plaque instability in stable coronary heart disease (CHD) patients. Increased levels of MMPs in patients with advanced cardiovascular disease (CAD) and acute coronary syndrome (ACS) was associated with future risk of cardiovascular events. These data confirm that MMPs may be biomarkers in plaque instability as they target in potential drug therapies for atherosclerosis. They provide important prognostic information, independent of traditional risk factors, and may turn out to be useful in improving risk stratification.

Immune-Mediated Inflammation in Vulnerable Atherosclerotic Plaques

Atherosclerosis is a chronic long-lasting vascular disease leading to myocardial infarction and stroke. Vulnerable atherosclerotic (AS) plaques are responsible for these life-threatening clinical endpoints. To more successfully work against atherosclerosis, improvements in early diagnosis and treatment of AS plaque lesions are required. Vulnerable AS plaques are frequently undetectable by conventional imaging because they are non-stenotic. Although blood biomarkers like lipids, C-reactive protein, interleukin-6, troponins, and natriuretic peptides are in pathological ranges, these markers are insufficient in detecting the critical perpetuation of AS anteceding endpoints. Thus, chances to treat the patient in a preventive way are wasted. It is now time to solve this dilemma because clear results indicate a benefit of anti-inflammatory therapy per se without modification of blood lipids (CANTOS Trial, NCT01327846). This fact identifies modulation of immune-mediated inflammation as a new promising point of action for the eradication of fatal atherosclerotic endpoints.

Matrix metalloproteinase-12 as an endogenous resolution promoting factor following myocardial infarction

Following myocardial infarction (MI), timely resolution of inflammation promotes wound healing and scar formation while limiting excessive tissue damage. Resolution promoting factors (RPFs) are agents that blunt leukocyte trafficking and inflammation, promote necrotic and apoptotic cell clearance, and stimulate scar formation. Previously identified RPFs include mediators derived from lipids (resolvins, lipoxins, protectins, and maresins), proteins (glucocorticoids, annexin A1, galectin 1, and melanocortins), or gases (CO, H₂S, and NO). Matrix metalloproteinase-12 (MMP-12; macrophage elastase) has shown promising RPF qualities in a variety of disease states. We review here the evidence that MMP-12 may serve as a novel RPF with potential therapeutic efficacy in the setting of MI.