High levels of IsoDGR-modified fibronectin are associated with higher levels of macrophages and other rupture-prone plaque characteristics in patients undergoing carotid endarterectomy

Objective: Deamidation of the NGR (Asn-Gly-Arg) motif to the isoDGR (isoAsp-Gly-Arg) motif in fibronectin (IsoDGR-fibronectin) enhances in vitro monocyte and endothelial cell activation. Blocking isoDGR reduces macrophage influx in murine tissues. Although macrophage influx is an important feature of human plaque destabilization, the role for plasma and plaque isoDGR-fibronectin in macrophage influx in the atherosclerotic plaque and thereby increasing plaque vulnerability has not been investigated in large human cohorts. Design: IsoDGR-fibronectin levels in plasma and plaques were measured in carotid endarterectomy (CEA) patients from the Athero Express biobank cohort and associated with macrophage and other vulnerable plaque characteristics in the carotid plaque of the same patient. Methods: Levels of isoDGR-fibronectin were measured using an ELISA. Carotid plaque characteristics were visualized with immunohistochemistry staining and scored semi-quantitatively. Baseline characteristics were analysed with Pearson`s Chi-squared test and Mann-Whitney U-test when applicable. Univariate and multivariate logistics regression analyses were used to identify associations with adverse plaque characteristics. Results: Plasma isoDGR-fibronectin was measured in 730 CEA patients. Patients with moderate/heavy plaque macrophage staining had higher levels of isoDGR-fibronectin than patients with no/minor macrophage staining (multivariate OR 1.40 (95%CI 1.04-1.90, p=0.028)). Of the 730 CEA patients, 348 had plaque samples available for isoDGR-fibronectin measurements. In the multivariate analysis, higher plaque levels of isoDGR-fibronectin were associated with moderate/high plaque macrophage staining (OR 1.22 (95%CI 1.00-1.56, p=0.049)), >40% fat in plaque (OR 1.1.44 (95% CI 1.14-1.86, p=0.004)) and intraplaque haemorrhage (OR 1.38 (95% 1.12-1.72, p=0.003)). Conclusion: In this large human cohort study high plasma and plaque levels of isoDGR-fibronectin were associated with more plaque macrophages and other adverse plaque characteristics. This suggests the involvement of isoDGR-fibronectin in human plaque destabilization that may lead to new potential treatment modalities.