Perspective - Journal of Cholesterol and Heart Disease (2022) Volume 6, Issue 5
Intraplaque Hemorrhage and Coronary Atheroma Development.
Department of Cardiovascular Pathology, Armed Forces Institute of Pathology, Washington
- *Corresponding Author:
- Allen David
Department of Cardiovascular Pathology,
Armed Forces Institute of Pathology,
Received:27-Sep-2022, Manuscript No. AACHD-22-80635; Editor assigned: 29-Sep-2022, PreQC No. AACHD-22-80635(PQ); Reviewed:13-Oct-2022, QC No. AACHD-22-80635; Revised:18-Oct-2022, Manuscript No. AACHD-22-80635(R); Published:25-Oct-2022, DOI:10.35841/aachd-6.5.124
Citation: David A. Intraplaque hemorrhage and coronary atheroma development. J Cholest Heart Dis. 2022; 6(5):124
The study received approval from an institutional review board. As previously mentioned, the hearts of patients who had passed away suddenly from cardiac reasons were taken. 8 Out of 270 of these patients, 100 were chosen at random for further research to find out the frequency of haemorrhage in non-culprit plaques with luminal constriction of greater than 50%. In patients with coronary thrombosis brought on by acute plaque rupture, the average number of Intraplaque haemorrhages per heart was 5.00.4, compared to 0.60.3 in patients with thrombosis brought on by plaque erosion and 2.80.8 in patients with stenosis of at least 75% of the lesion in the absence of acute thrombi. In this study, erythrocyte membranes were found inside the necrotic cores of human atherosclerotic plaques, even those without recent haemorrhages and their relationship to the development and instability of the lesions was examined. In order to create a model of the course of lesions caused by haemorrhage, we also looked at what happened to the erythrocytes in existing plaques in atherosclerotic rabbits. Another potential mechanism of plaque progression and vulnerability would be provided by the identification of a relationship between Intraplaque haemorrhage and the growth of the lesions.
Atherosclerotic plaques, Intraplaque haemorrhage, Thrombosis, Haemorrhage.
An antibody against glycophorin A was incubated with paraffin slices to detect the locations of past plaque bleeding. Endothelial cells and macrophages were distinguished by staining with antibodies against CD68 and von Willebrand factor, respectively. Using a peroxidase-based kit, primary antibodies were tagged with a biotinylated link antibody directed against mouse antigen and observed using a 3-amino-9-ethylcarbazole substrate. Two independent observers semi-quantitatively rated the proportion of the necrotic core or lipid pool that was composed of glycophorin A and iron on a scale from 0 to 4, with higher scores denoting larger percentages. The analysis was limited to those that had erythrocyte fragments stained.
Intramural Hemorrhage Rabbit Model
The rabbits had a left-sided lateral laparotomy under general anaesthesia and a 4-cm piece of the abdominal aorta was exposed after eight weeks on the non-atherogenic diet. At the locations of the lesions, a 30-gauge needle was inserted into the artery lumen and progressively withdrawn until the bevelled tip was inside the arterial wall. Using a portable 1-ml syringe, washed autologous erythrocytes were slowly injected into developed atherosclerotic plaques. Visual proof that erythrocytes were trapped within the plaque came in the form of a modestly elevated hematoma. Per animal, two to three lesions were injected; the controls were the lesions that weren't injected. For an additional six weeks, the animals were fed a regular chow diet .
Aortic Lesions' Histologic Appearance with Intramural Hemorrhage
Despite identical plaque diameters in the two groups, erythrocyte-injected rabbit atheromas displayed more widespread macrophage infiltration than control lesions. The plaques with injected erythrocytes had considerably more lipid content when stained with oil red O than the control lesions did. Histological examination of the injected erythrocyte plaques revealed distinct dissection planes and a circumferential infiltration of macrophages within the arterial wall. Both the superficial and deep layers of the arterial wall contained a significant number of lipid-rich RAM11-positive foam cells. In plaques that had received an injection of erythrocytes, there was a significant amount of fat present. Erythrocyte fragments and iron-depositing macrophage foam cells were frequently identified with cholesterol crystals .
Tissue Preparation and Staining
The abdominal aorta was removed and divided into 3-mm pieces before the rabbits were put to death. The arterial tree was also perfused and fastened. Cryosections were stained with movat pentachrome and hematoxylin and eosin on prepared frozen blocks. For the immunohistochemistry analysis, additional slices were employed to evaluate the lipid and iron contents. A particular monoclonal antibody directed against rabbit alveolar macrophages was used to identify the macrophages. We dyed the slices with isolectin B4 from Bandeiraea simplicifolia coupled with biotin to detect erythrocyte membranes .
Studies in histopathology
An antibody against glycophorin A was incubated with paraffin slices to detect the locations of past plaque bleeding. Endothelial cells and macrophages were distinguished by staining with antibodies against CD68 and von Willebrand factor, respectively. Using a peroxidase-based kit, primary antibodies were tagged with a biotinylated link antibody directed against mouse antigen and observed using a 3-amino-9-ethylcarbazole substrate. Two independent observers semi-quantitatively rated the proportion of the necrotic core or lipid pool that was composed of glycophorin A and iron on a scale from 0 to 4, with higher scores denoting larger percentages. The analysis was limited to those that had erythrocyte fragments stained. As previously mentioned, the size of the lipid core, plaque area, and macrophage content were all measured using computer-based morphometric .
Association among Intraplaque hemorrhage
According to our research, Intraplaque bleeding, a growth in the size of the necrotic core, and lesion instability in coronary plaques are all related. In lesions with late cores and those that are prone to rupture, immunostaining with an anti-glycophorin a antibody indicated prior haemorrhages. The size of the necrotic core was correlated with the level of iron build up and glycophorin A reactivity, and an increase in both factors was accompanied by an increase in macrophage density, supporting the hypothesis that the bleeding itself acts as an inflammatory trigger. We created an experimental model of intramural bleeding in the rabbit to investigate the idea that erythrocytes actively contribute to the development of atheromas .
Given that the level of free cholesterol is much higher in disturbed lesions, it is thought that lipid composition affects the stability of atherosclerotic plaques. Additionally, compared to fibrocalcific plaques, lesions that have ruptured exhibit a higher percentage of cholesterol clefts. Although apoptotic macrophages might be a source of free cholesterol, since most of the cholesterol in foam cells is esterified, it is improbable that the total amount of free cholesterol in plaques could have come from foam cells alone. Similar to the discovery of cholesterol clefts, macrophages, and iron in significant regions of extravagated erythrocytes outside the coronary circulation, we also discovered cholesterol crystals and glycophorin A in the necrotic cores of advanced coronary plaques. Although the origin of the cholesterol crystals in these nonvascular lesions from foam cells is plausible, cholesterol clefts frequently only exist in regions of erythrocytes devoid of macrophages. When this happens, the amount of cholesterol derived from erythrocyte membranes may go above a certain point, resulting in the formation of an immiscible cholesterol phase and eventually crystallisation
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