Imaging of vulnerable plaques using near-infrared spectroscopy for risk stratification of atherosclerosis

miR-223-3p inhibits the progression of atherosclerosis via down-regulating the activation of MEK1/ERK1/2 in macrophages

BACKGROUND

microRNAs (miRNAs) have drawn more attention to the progression of atherosclerosis (AS), due to their noticeable inflammation function in cardiovascular disease. Macrophages play a crucial role in disrupting atherosclerotic plaque, thereby we explored the involvement of miR-223-3p in the inflammatory response in macrophages.

METHODS

RT-qPCR was used to analyze the miR-223-3p levels in carotid arteries and serum of AS patients. ROC curve was used to assess the diagnostic value of miR-223-3p. Movat staining was applied to evaluate the morphological differences. FISH was used to identify the expression of miR-223-3p in macrophages of atherosclerotic lesions. Bioinformatic analysis was performed. Double-immunofluorescence and western blot were performed to assess the inflammatory cytokine secretion and p-ERK1/2. C16-PAF was injected into the culture medium of the miR-223-3p mimic/NC-transfected macrophages with ox-LDL.

RESULTS

MiR-223-3p was up-regulated in AS patients and was associated with a higher overall survival rate. MiR-223-3p was co-localized with CD68+ macrophages in vulnerable atherosclerotic lesions. MiR-223-3p mimics decreased atherosclerotic lesions, macrophages numbers whereas increased SMCs numbers in the lesions. The TNF-a immune-positive areas were reduced by miR-223-3p mimics. MAP2K1 was negatively associated with miR-223-3p. MiR-223-3p mimics reduced the inflammation and the MEK1/ERK1/2 signaling pathway in vivo and in vitro. C16-PAF reversed the effects of miR-223-3p mimics on inflammation and ERK1/2 signaling pathway.

CONCLUSIONS

MiR-223-3p negatively regulates inflammatory responses by the MEK1/ERK1/2 signaling pathway. Our study provides new insight into how miR-223-3p protects against atherosclerosis, representing a broader therapeutic prospect for treating atherosclerosis by miR-223-3p.

Significant decrease in lipid core burden index following balloon dilation was associated with the leakage of cholesterol crystals in a patient: a case report

BACKGROUND

Near-infrared spectroscopy (NIRS) has been used for analysis the composition of the atherosclerotic plaque in coronary arteries. However, meaning of significant decrease in max lipid core burden index at 4 mm (max LCBI_4mm) during percutaneous coronary intervention (PCI) is poorly understood.

CASE SUMMARY

A 64-year-old male with unstable angina underwent coronary angiography, which demonstrated a hazy tight culprit lesion in the mid-right coronary artery. Pre-intervention NIRS-intravascular ultrasound (NIRS-IVUS) and chemogram showed plaque with high lipid burden at the culprit lesion. Then, we used a distal protection device before PCI because of high max LCBI_4mm in the lesion. After pre-dilation with a scoring balloon, repeat NIRS-IVUS interrogation revealed an almost complete disappearance of the yellow signal and decrease in max LCBI_4mm (from 537 to 44) significantly, suggesting decrease in the lipid content of the plaque. Finally, a drug-eluting stent deployment followed by inflation of a non-compliant balloon led to an excellent result. After PCI, we detected trapped large amounts of debris on retrieval of the filter. Pathological diagnosis confirmed that trapped material was lipid-rich plaque including cholesterol crystals.

DISCUSSION

This is the first report directly demonstrated that significant decrease in max LCBI_4mm at culprit lesion should be associated with the leakage of cholesterol crystals from lipid-rich plaque during PCI in the clinical patient.

Plaque imaging to refine indications for emerging lipid-lowering drugs

Statins have been effective in reducing adverse cardiovascular events. Their benefits have been proportional to the level of plasma LDL-cholesterol reduction and seem to extend to patients with 'normal' levels of cholesterol at outset. Statins are also inexpensive and have a favourable side-effect profile. As a result, they are used widely (almost indiscriminately) in patients with atherosclerotic vascular disease, and in those at risk of disease. Next generation lipid-modifying drugs seem unlikely to offer the same simplicity of application. The recent trials of new classes of lipid modifying drugs underline the need for a risk stratification tool which is not based on patients' category of diagnosis (for example, post-myocardial infarction) but based on the characterization of disease in that individual patient. Mechanistic staging, a process that matches the target of the drug action with an identifiable disease characteristic, may offer an opportunity to achieve more precise intervention. The upshots of this targeted approach will be greater efficacy, requiring smaller clinical trials to demonstrate effectiveness; a reduced number needed to treat to yield benefits and more cost-effective prescribing. This will be important, as purchasers require ever more rigorous demonstration of both efficacy and cost-effectiveness. In this context, we will discuss available pharmacological strategies of lipid reduction in anti-atherosclerotic treatment and how plaque imaging techniques may provide an ideal method in stratifying patients for new lipid-modifying drugs.

The role of near-infrared spectroscopy in the detection of vulnerable atherosclerotic plaques

Coronary artery disease is the leading cause of mortality worldwide. Most acute coronary syndromes are caused by a rupture of a vulnerable atherosclerotic plaque which can be characterized by a lipid-rich necrotic core with an overlying thin fibrous cap. Many vulnerable plaques can cause angiographically mild stenoses due to positive remodelling, which is why the extent of coronary artery disease may be seriously underestimated. In recent years, we have witnessed a paradigm shift in interventional cardiology. We no longer focus solely on the degree of stenosis; rather, we seek to determine the true extent of atherosclerotic disease. We seek to identify high-risk plaques for improvement in risk stratification of patients and prevention. Several imaging methods have been developed for this purpose. Intracoronary near-infrared spectroscopy is one of the most promising. Here, we discuss the possible applications of this diagnostic method and provide a comprehensive overview of the current knowledge.

Quantification of Lipid-Rich Core in Carotid Atherosclerosis Using Magnetic Resonance T2 Mapping: Relation to Clinical Presentation

Objectives

The aim of this study was to: 1) provide tissue validation of quantitative T₂ mapping to measure plaque lipid content; and 2) investigate whether this technique could discern differences in plaque characteristics between symptom-related and non–symptom-related carotid plaques.

Background

Noninvasive plaque lipid quantification is appealing both for stratification in treatment selection and as a possible predictor of future plaque rupture. However, current cardiovascular magnetic resonance (CMR) methods are insensitive, require a coalesced mass of lipid core, and rely on multicontrast acquisition with contrast media and extensive post-processing.

Methods

Patients scheduled for carotid endarterectomy were recruited for 3-T carotid CMR before surgery. Lipid area was derived from segmented T₂ maps and compared directly to plaque lipid defined by histology.

Results

Lipid area (%) on T₂ mapping and histology showed excellent correlation, both by individual slices (R = 0.85, p < 0.001) and plaque average (R = 0.83, p < 0.001). Lipid area (%) on T₂ maps was significantly higher in symptomatic compared with asymptomatic plaques (31.5 ± 3.7% vs. 15.8 ± 3.1%; p = 0.005) despite similar degrees of carotid stenosis and only modest difference in plaque volume (128.0 ± 6.0 mm³ symptomatic vs. 105.6 ± 9.4 mm³ asymptomatic; p = 0.04). Receiver-operating characteristic analysis showed that T₂ mapping has a good ability to discriminate between symptomatic and asymptomatic plaques with 67% sensitivity and 91% specificity (area under the curve: 0.79; p = 0.012).

Conclusions

CMR T₂ mapping distinguishes different plaque components and accurately quantifies plaque lipid content noninvasively. Compared with asymptomatic plaques, greater lipid content was found in symptomatic plaques despite similar degree of luminal stenosis and only modest difference in plaque volumes. This new technique may find a role in determining optimum treatment (e.g., providing an indication for intensive lipid lowering or by informing decisions of stents vs. surgery).