Mast Cell Distribution in Human Carotid Atherosclerotic Plaque Differs Significantly by Histological Segment

Cellular and Molecular Mechanisms of Mast Cells in Atherosclerotic Plaque Progression and Destabilization

Mast cells (MCs) are commonly recognized for their crucial involvement in the pathogenesis of allergic diseases, but over time, it has come to light that they also play a role in the pathophysiology of non-allergic disorders including atherosclerosis. The involvement of MCs in the pathology of atherosclerosis is supported by their accumulation in atherosclerotic plaques upon their progression and the association of intraplaque MC numbers with acute cardiovascular events. MCs that accumulate within the atherosclerotic plaque release a cocktail of mediators through which they contribute to neovascularization, plaque progression, instability, erosion, rupture, and thrombosis. At a molecular level, MC-released proteases, especially cathepsin G, degrade low-density lipoproteins (LDL) and mediate LDL fusion and binding of LDL to proteoglycans (PGs). Through a complicated network of chemokines including CXCL1, MCs promote the recruitment of among others CXCR2+ neutrophils, therefore, aggravating the inflammation of the plaque environment. Additionally, MCs produce extracellular traps which worsen inflammation and contribute to atherothrombosis. Altogether, evidence suggests that MCs actively, via several underlying mechanisms, contribute to atherosclerotic plaque destabilization and acute cardiovascular syndromes, thus, making the study of interventions to modulate MC activation an interesting target for cardiovascular medicine.

Contrast-Enhanced Ultrasound Combined With 2D Strain Imaging and Histopathological Multimodal Assessment of Carotid Plaque Vulnerability

OBJECTIVE

The aim of this study was to explore the value of contrast-enhanced ultrasound (CEUS) combined with 2-D strain imaging in evaluating carotid plaque vulnerability and the correlations among CEUS perfusion parameters, strain parameters and histopathological findings in different plaque segments.

METHODS

Patients with carotid artery stenosis who underwent carotid endarterectomy (CEA) at the First Affiliated Hospital of Xinjiang Medical University from September 2020 to June 2021 underwent preoperative carotid artery 2-D ultrasonography and CEUS. The plaques were divided into three segments: the proximal end of the shoulder, central cap and distal end of the shoulder. The peak intensity (PI) value and strain rate parameters of the regions of interest were analyzed. Plaques were divided into a stable group (8 cases) and an unstable group (19 cases). The microvascular density (MVD) and vascular endothelial growth factor (VEGF) expression of each patch in the unstable group were analyzed.

RESULTS

The peak strain during the systolic period in each plaque segment in both groups showed the following pattern: proximal end shoulder > distal end shoulder > top (p < 0.05). The PI value for CEUS is also represented. In the unstable group, the PI values of each segment of the plaque were positively correlated with the MVD, near-center PI value and VEGF average optical density value. The average optical density of each segment was positively correlated with the MVD (p < 0.05). There were positive correlations between the PI values of the proximal and distal shoulder and the strain values (p < 0.05), and the MVD value of each segment, VEGF value and strain value were positively correlated (p < 0.05).

CONCLUSION

PI and the pathological tissue components represented by CEUS were positively correlated with the mechanical parameters of the plaque along the long axis. There may be overlap between the high shear stress area of the plaque and the neovascular aggregation area, and the combination of the two has certain significance for assessing the vulnerability of the plaque.

The Relationship between Intracarotid Plaque Neovascularization and Lp (a) and Lp-PLA2 in Elderly Patients with Carotid Plaque Stenosis

The aim of this study was to investigate the relationship between carotid plaque neovascularization and lipoprotein (a) [Lp (a)], lipoprotein-associated phospholipase A2 (Lp-PLA2) in elderly patients with carotid plaque stenosis. One hundred elderly patients with carotid plaque stenosis diagnosed in our hospital from January 2020 to January 2022 were retrospectively analyzed and divided into stable (n = 62) and unstable (n = 38) groups according to whether the plaque was stable or not. Plasma Lp (a), Lp-PLA2, apoA, and apoB levels were measured; intraplaque angiogenesis (IPN) scores were examined by contrast-enhanced ultrasound (CEUS) to assess IPN grade in patients; and Pearson correlation was used to analyze the relationship between plasma Lp (a) and Lp-PLA2 levels and plaque characteristics and angiogenesis. The maximum thickness and total thickness of carotid plaque in the unstable group were significantly greater than those in the stable group (P < 0.05); the IPN grade was mainly grade III and IV in the unstable group and grade II in the stable group, and the IPN score was significantly higher in the unstable group than in the stable group (P < 0.05); there was no significant difference in the plasma apoA and apoB levels between the two groups (P > 0.05), and the plasma Lp (a) and Lp-PLA2 levels were significantly higher in the unstable group than in the stable group (P < 0.05); the neovascular grade, plasma Lp-PLA2, and Lp (a) levels were significantly increased (P < 0.05); the plasma Lp (a) and Lp-PLA2 levels were positively correlated with the maximum plaque thickness, total plaque thickness, degree of stenosis, and angiogenesis (P < 0.05). The plasma levels of Lp (a) and Lp-PLA2 are positively correlated with intraplaque angiogenesis, and their levels can reflect the stability of carotid plaques.