A peripheral blood gene expression score is associated with plaque volume and phenotype by intravascular ultrasound with radiofrequency backscatter analysis: results from the ATLANTA study

Gene expression profiling of coronary artery disease and its relation with different severities

Global gene expression profiling is a powerful tool enabling the understanding of pathophysiology and subsequent management of diseases. This study aims to explore functionally annotated differentially expressed genes (DEGs); their biological processes for coronary artery disease (CAD) and its different severities of atherosclerotic lesions. This study also aims to identify the change in expression patterns of DEGs in atherosclerotic lesions of single-vessel disease (SVD) and triple-vessel disease (TVD). The weight of different severities of lesion was estimated using a modified Gensini score. The gene expression profiling was performed using the Affymetrix microarray platform. The functional annotation for CAD was performed using DAVID v6.8. The biological network gene ontology tool (BiNGO) and ClueGO were used to explore the biological processes of functionally annotated genes of CAD. The changes in gene expression from SVD to TVD were determined by evaluating the fold change. Functionally annotated genes were found in an unique set and could be distinguishing two distinct severities of CAD. The biological processes such as cellular migration, locomotion, cell adhesion, cytokine production, positive regulation of cell death etc. enriched the functionally annotated genes in SVD, whereas, wound healing, negative regulation of cell death, blood coagulation, angiogenesis and fibrinolysis were enriched significantly in TVD patients. The genes THBS1 and CAPN10 were functionally annotated for CAD in both SVD and TVD. The 61 DEGs were identified, those have changes their expression with different severities of atherosclerotic lesions, in which 13 genes had more than two-fold change in expression between SVD and TVD. The consistent findings were obtained on validation of microarray gene expression of selected 10 genes in a separate cohort using real-time PCR. This study identified putative candidate genes and their biological processes predisposing toward and affecting the severity of CAD.

An integrated approach to coronary heart disease diagnosis and clinical management

The major issue in coronary heart disease (CHD) diagnosis and management is that symptoms onset in an advanced state of disease. Despite the availability of several clinical risk scores, the prediction of cardiovascular events is lacking, and many patients at risk are not well stratified according to the canonical risk factors alone. Therefore, adequate risk assessment remains the most challenging issue. Recently, the integration of imaging data with biochemical markers in a radiogenomic framework has been proposed in many fields of medicine as well as in cardiology. Multimodal imaging and advanced processing techniques can provide both direct (e.g., remodeling index, calcium score, total plaque volume, plaque burden) and indirect (e.g., myocardial perfusion index, coronary flow reserve) imaging features of CHD. Furthermore, the identification of novel non-invasive biochemical markers, mainly focused on plasma and/or serum samples, has increased the specificity of findings, reflecting several pathophysiological pathways of atherosclerosis, the principal actor in CHD. In this context, a multifaced approach, derived from the strengths of all these modalities, appears promising for finer risk stratification and treatment strategies, facilitating the decision-making and clinical management of patients. This review underlines the role of different imaging modalities in the quantification of coronary atherosclerosis and describes novel blood-based markers that could improve diagnosis and have a better predictive value in CHD.

In Vivo and In Vitro Analysis in Coronary Artery Disease Related to Type 2 Diabetes

AIM

The leading cause of morbidity and mortality in patients with type 2 diabetes mellitus (DM) is coronary artery disease (CAD), a condition often asymptomatic but severe in these patients. Although glucose metabolism impairment and oxidative stress are known actors in the endothelial dysfunction/remodeling that occurs in diabetic patients, the relationship between cardiovascular disorders and DM is not fully understood. We have performed both an in vivo imaging and in vitro molecular analysis to investigate diabetic-specific CAD alterations.

METHODS

Computed tomography coronary angiography (CTCA) was performed in a group of 20 diabetic patients with CAD (DM⁺CAD⁺), 20 non-diabetic with CAD (DM^-CAD⁺), 10 diabetic non-CAD patients (DM⁺CAD^-), and 20 non-diabetic healthy subjects (HS). Imaging quantitative parameters such as calcium score (Cascore), calcified plaque volume (CPV), non-calcified plaque volume (NCPV), total plaque volume (TPV), remodeling index (RI), and plaque burden were extracted for each CAD subject. Moreover, the expression levels of superoxide dismutase 2 (SOD2) and liver X receptor alpha (LXRα) genes were analyzed in the peripheral blood mononuclear cells, whereas hyaluronan (HA) concentrations were evaluated in the plasma of each subject.

RESULTS

Imaging parameters, such as Cascore, CPV, RI, and plaque burden, were significantly higher in DM⁺CAD⁺ group, compared to DM^-CAD⁺ (P = 0.019; P = 0.014; P < 0.001, P < 0.001, respectively). SOD2 mRNA was downregulated, while LXRα gene expression was upregulated in DM⁺CAD^-, DM⁺CAD⁺, and DM^-CAD⁺ groups compared to HS (P = 0.001, P = 0.03, and P = 0.001 for SOD2 and P = 0.006, P = 0.008, and P < 0.001 for LXRα, respectively). Plasmatic levels of HA were higher in DM^-CAD⁺, DM⁺CAD^-, and DM⁺CAD⁺ groups, compared to HS (P = 0.001 for the three groups). When compared to DM^-CAD⁺, HA concentration was higher in DM⁺CAD^- (P = 0.008) and DM⁺CAD⁺ (P < 0.001) with a significant difference between the two diabetic groups (P = 0.003). Moreover, HA showed a significant association with diabetes (P = 0.01) in the study population, and the correlation between HA levels and glycemia was statistically significant (ρ = 0.73, P < 0.001).

CONCLUSION

In our population, imaging parameters highlight a greater severity of CAD in diabetic patients. Among molecular parameters, HA is modulated by diabetic CAD-related alterations while SOD2 and LXRα are found to be more associated with CAD but do not discriminate between diabetic and non-diabetic subgroups.

Comprehensive plaque assessment by coronary CT angiography

Most acute coronary syndromes are caused by sudden luminal thrombosis due to atherosclerotic plaque rupture or erosion. Preventing such an event seems to be the only effective strategy to reduce mortality and morbidity of coronary heart disease. Coronary lesions prone to rupture have a distinct morphology compared with stable plaques, and provide a unique opportunity for noninvasive imaging to identify vulnerable plaques before they lead to clinical events. The submillimeter spatial resolution and excellent image quality of modern computed tomography (CT) scanners allow coronary atherosclerotic lesions to be detected, characterized, and quantified. Large plaque volume, low CT attenuation, napkin-ring sign, positive remodelling, and spotty calcification are all associated with a high risk of acute cardiovascular events in patients. Computation fluid dynamics allow the calculation of lesion-specific endothelial shear stress and fractional flow reserve, which add functional information to plaque assessment using CT. The combination of morphologic and functional characteristics of coronary plaques might enable noninvasive detection of vulnerable plaques in the future.