scholarly journals Pathogenesis of atherosclerosis in the tunica intima, media, and adventitia of coronary arteries: An updated review

Author(s):  
Aleksandra Milutinović ◽  
Dušan Šuput ◽  
Ruda Zorc-Pleskovič

Atherosclerosis is a chronic inflammatory disease of arteries and it affects the structure and function of all three layers of the coronary artery wall. Current theories suggest that the dysfunction of endothelial cells is one of the initial steps in the development of atherosclerosis. The view that the tunica intima normally consists of a single layer of endothelial cells attached to the subendothelial layer and internal elastic membrane has been questioned in recent years. The structure of intima changes with age and it becomes multilayered due to migration of smooth muscle cells from the media to intima. At this stage, the migration and proliferation of smooth muscle cells do not cause pathological changes in the intima. The multilayering of intima is classically considered to be an important stage in the development of atherosclerosis, but in fact atherosclerotic plaques develop only focally due to the interplay of various processes that involve the resident and invading inflammatory cells. The tunica media consists of multiple layers of smooth muscle cells that produce the extracellular matrix, and this layer normally does not contain microvessels. During the development of atherosclerosis, the microvessels from the tunica adventitia or from the lumen may penetrate thickened media to provide nutrition and oxygenation. According to some theories, the endothelial dysfunction of these nutritive vessels may significantly contribute to the atherosclerosis of coronary arteries. The adventitia contains fibroblasts, progenitor cells, immune cells, microvessels, and adrenergic nerves. The degree of inflammatory cell infiltration into the adventitia, which can lead to the formation of tertiary lymphoid organs, correlates with the severity of atherosclerotic plaques. Coronary arteries are surrounded by perivascular adipose tissue that also participates in the atherosclerotic process.

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1485
Author(s):  
Adrian Sowka ◽  
Pawel Dobrzyn

Studies of adipose tissue biology have demonstrated that adipose tissue should be considered as both passive, energy-storing tissue and an endocrine organ because of the secretion of adipose-specific factors, called adipokines. Adiponectin is a well-described homeostatic adipokine with metabolic properties. It regulates whole-body energy status through the induction of fatty acid oxidation and glucose uptake. Adiponectin also has anti-inflammatory and antidiabetic properties, making it an interesting subject of biomedical studies. Perivascular adipose tissue (PVAT) is a fat depot that is conterminous to the vascular wall and acts on it in a paracrine manner through adipokine secretion. PVAT-derived adiponectin can act on the vascular wall through endothelial cells and vascular smooth muscle cells. The present review describes adiponectin’s structure, receptors, and main signaling pathways. We further discuss recent studies of the extent and nature of crosstalk between PVAT-derived adiponectin and endothelial cells, vascular smooth muscle cells, and atherosclerotic plaques. Furthermore, we argue whether adiponectin and its receptors may be considered putative therapeutic targets.


2002 ◽  
Vol 282 (5) ◽  
pp. H1656-H1664 ◽  
Author(s):  
William B. Campbell ◽  
Christine Deeter ◽  
Kathryn M. Gauthier ◽  
Richard H. Ingraham ◽  
J. R. Falck ◽  
...  

Epoxyeicosatrienoic acids (EETs) cause vascular relaxation by activating smooth muscle large conductance Ca2+-activated K+ (KCa) channels. EETs are metabolized to dihydroxyeicosatrienoic acids (DHETs) by epoxide hydrolase. We examined the contribution of 14,15-DHET to 14,15-EET-induced relaxations and characterized its mechanism of action. 14,15-DHET relaxed U-46619-precontracted bovine coronary artery rings but was approximately fivefold less potent than 14,15-EET. The relaxations were inhibited by charybdotoxin, iberiotoxin, and increasing extracellular K+ to 20 mM. In isolated smooth muscle cells, 14,15-DHET increased an iberiotoxin-sensitive, outward K+ current and increased KCa channel activity in cell-attached patches and inside-out patches only when GTP was present. 14,15-[14C]EET methyl ester (Me) was converted to 14,15-[14C]DHET-Me, 14,15-[14C]DHET, and 14,15-[14C]EET by coronary arterial rings and endothelial cells but not by smooth muscle cells. The metabolism to 14,15-DHET was inhibited by the epoxide hydrolase inhibitors 4-phenylchalcone oxide (4-PCO) and BIRD-0826. Neither inhibitor altered relaxations to acetylcholine, whereas relaxations to 14,15-EET-Me were increased slightly by BIRD-0826 but not by 4-PCO. 14,15-DHET relaxes coronary arteries through activation of KCa channels. Endothelial cells, but not smooth muscle cells, convert EETs to DHETs, and this conversion results in a loss of vasodilator activity.


2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Irina Grechowa ◽  
Bernhard Dorweiler ◽  
Anja Wallrath ◽  
Sven Horke

Introduction: Rupture of atherosclerotic plaques is the most abundant cause for stroke. The serine protease elastase plays an important role as it induces death of endothelial cells (ECs) and smooth muscle cells (SMCs), and breaks down the fibrous cap of atherosclerotic plaques. Increased elastase concentrations were found in patients with symptomatic stenosis. We previously showed that elastase activates the endoplasmic reticulum (ER) stress signaling pathway unfolded protein response (UPR) in rupture-prone plaques of human carotid artery. However, signaling pathways elicited by elastase in vascular cells were largely unknown. We hypothesized that elastase induces cell-type dependent responses in ECs, SMCs and macrophages (M[[Unable to Display Character: &#1060;]]). Methods and Results: Different forms of cell death and UPR activation were analyzed in primary and immortalized endothelial cells, coronary artery smooth muscle cells (HCASMCs) and M[[Unable to Display Character: &#1060;]] after treatment with human neutrophil elastase. To discriminate between the involved cell death types, three independent assays were performed. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-assay by confocal microscopy (p < .01), caspase3/7 activity by chemiluminescence-assays (p < .01) and cell-cycle analysis by flow cytometry revealed that an autophagic/apoptotic cell death was induced upon elastase treatment. This appeared specific for ECs, as it was absent in M[[Unable to Display Character: &#1060;]]. Necrosis (as determined by chemiluminescent lactate dehydrogenase-release assay) and necroptosis (assessed by flow cytometry) played only minor roles. The involvement of the UPR was investigated on protein and / or gene expression level. The high levels of GRP78, phospho-PERK, phospho-eIF2α, spliced XBP1 and CHOP indicate a strongly activated UPR that may give rise to the subsequent induced autophagic/apoptotic cell death. Conclusion: Elastase plays a significant role in plaque stability and cell survival likely through activation of a UPR/autophagic type of endothelial cell death. This may explain underlying molecular links how elastase destabilizes atherosclerotic plaques.


2013 ◽  
Vol 68 (9) ◽  
pp. 22-26
Author(s):  
T. E. Vladimirskaya ◽  
I. A. Shved ◽  
S. G. Krivorot

Objective: to study apoptosis of individual cellular components of the vascular wall of coronary arteries at different morphological stages of atherosclerosis. Material and methods. The study was performed on coronary arteries taken from 52 deceased patients with atherosclerosis and coronary heart disease at different stages of atherogenesis. For morphological study prepared paraffin sections, which were stained for morphological studies were prepared paraffin sections, which were stained with hematoxylin and eosin, by Van Gieson, Masson, on lipids with Sudan black B, according to Van Cossu. .To determine apoptosis, TUNEL method used in paraffin sections. Apoptotic index (AI) was calculated by TUNEL-positive cells and the average inner shell coronary artery around the perimeter each with increasing microscopic 1000. Results. Investigation showed significant apoptosis (p 0.05) increase in AI smooth muscle, endothelial cells, macrophages in the coronary arteries affected by atherosclerosis compared to intact control group vascular segments significant reduction AI endothelial, smooth muscle cells and macrophages (p  0,05) traced from the early stages of atherogenic disorders to atheromatosis. Conclusions. It is established that apoptosis of smooth muscle cells, macrophages and endothelial cells is the most intensive on early stages of atherosclerotic process. In process of progressing of atherosclerosis intensity and prevalence of apoptosis of coronary artery wall cells decreases, and processes of necrosis becomes predominant. Apoptosis of coronary artery wall cells is valuable in increasing the zones of atheromatosis, plaque destabilizations, and also increases the risk of thrombosis and ulcerations. 


2001 ◽  
Vol 281 (3) ◽  
pp. H1156-H1162 ◽  
Author(s):  
Stéphane Budel ◽  
Alexander Schuster ◽  
Nikos Stergiopoulos ◽  
Jean-Jacques Meister ◽  
Jean-Louis Bény

We tested the hypothesis that the cytosolic free calcium concentration in endothelial cells is under the influence of the smooth muscle cells in the coronary circulation. In the left descending branch of porcine coronary arteries, cytosolic free calcium concentration ([Ca2+]i) was estimated by determining the fluorescence ratio of two calcium probes, fluo 4 and fura red, in smooth muscle and endothelial cells using confocal microscopy. Acetylcholine and potassium, which act directly on smooth muscle cells to increase [Ca2+]i, were found to indirectly elevate [Ca2+]i in endothelial cells; in primary cultures of endothelial cells, neither stimulus affected [Ca2+]i, yet substance P increased the fluorescence ratio twofold. In response to acetylcholine and potassium, isometric tension developed by arterial strips with intact endothelium was attenuated by up to 22% ( P < 0.05) compared with strips without endothelium. These findings suggest that stimuli that increase smooth muscle [Ca2+]i can indirectly influence endothelial cell function in porcine coronary arteries. Such a pathway for negative feedback can moderate vasoconstriction and diminish the potential for vasospasm in the coronary circulation.


2016 ◽  
Vol 94 (9) ◽  
pp. 672-677
Author(s):  
Tatyana E. Vladimirskaya ◽  
I. A. Shved

Aim. To study apoptosis of endothelial cells (EC), macrophages (MF) and smooth muscle cells (SMC) in the early atherosclerotic process (prior to plaque formation), elucidate mechanisms of its realization and evaluate effect on progression of atherosclerosis. Materials and methods. Histopathological studies were performed on coronary arteries affected by atherosclerosis takenat autopsy of patients with coronary heart disease (n = 63). To detect apoptosis, the TUNEL method was used for calculating the apoptotic index (AI) in paraffin sections. Phenotyping the cells and test for expression of active caspase 3 (AC-3) and apoptosis-inducing factor (AIF) were performed using sections of coronary arteries stained by immunohistochemistry. Results. The study of apoptosis showed a significant (p <0.0001) increase in AI of SMC, EC, MF coronary arteries affected by atherosclerosis compared with unaffected vessels. Progression of the atherosclerotic process led to a decrease of AI of SMC and EC. Statistical analysis revealed moderate feedback between AI of SMC and neointimal thickness in the development of atherosclerotic lesions (r = -0,44, p <0.0001). The amount of the AC-positive SMC and EC at the stage of lipoidosis significantly (p <0.0001) exceeded the number of AC -positive SMC at the liposclerosis stage. Expression of AIF was observed in the nuclei of EC in the newly formed vessels of hyperplastic intima. Conclusions. Early atherosclerotic lesions of the coronary arteries are accompanied by intense apoptosis of SMC, EC and MF. The intensity of apoptosis of SMC and EC decreases with the development of atherosclerosis. Progression of intimal hyperplasia at the early stages of atherosclerosis is associated with reduced apoptosis of smooth muscle cells and enhanced macrophage apoptosis. Apoptosis of SMC and MF is caspase-dependent. Apoptosis of endothelial cells can occur both with the participation of caspases and independently of them (with AIF).


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