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

Abstract

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.

Keywords: atherosclerosis; biomarkers; computed tomography coronary angiography; coronary artery disease; type 2 diabetes.

Figure 1

(A,D) Non-contrast enhanced images showing calcium deposits (yellow) on the left descending coronary artery (LAD) in a non-diabetic CAD patient (DM⁻CAD⁺) and in a diabetic CAD patient (DM⁺CAD⁺), respectively. (B,E) cMPR of LAD is provided for DM⁻CAD⁺ and DM⁺CAD⁺. (C,F) Plaque characterization: the calcific (yellow) and non-calcific (pink) components of the plaque are highlighted; the vessel lumen is represented in green. DM⁺CAD⁺ displayed significantly higher coronary calcium values compared to DM⁻CAD⁺.

Figure 2

(A,B) Cross-sectional view and cMPR of the left descending coronary artery (LAD) in a non-diabetic CAD patient (DM⁻CAD⁺) and in a diabetic CAD patient (DM⁺CAD⁺). In cross-sectional images, the vessel lumen is represented in green whereas the calcific component of the plaque is red.

Figure 3

(A) Superoxide dismutase 2 (SOD2) mRNA relative expression in PBMNCs of healthy subjects (HS), diabetic non-CAD patients (DM⁺CAD⁻), non-diabetic CAD patients (DM⁻CAD⁺), and diabetic CAD patients (DM⁺CAD⁺). (B) Liver X receptor alpha (LXRα) gene expression in PBMNCs of HS, DM⁺CAD⁻, DM⁻CAD⁺, and DM⁺CAD⁺. (C) Median plasma hyaluronan (HA) concentrations (ng/mL) in HS, DM⁺CAD⁻, DM⁻CAD⁺, and DM⁺CAD⁺ (*P < 0.05; **P < 0.01; ***P < 0.001). When not specified, significance is referred to the comparison vs HS. (D) Correlation between HA levels and glycemia in HS, DM⁺CAD⁻, DM⁻CAD⁺, and DM⁺CAD⁺ patients (ρ = 0.73, P < 0.001).