The role of endothelial cell adhesion molecules in the development of atherosclerosis

Prunus yedoensis Bark Downregulates the Expression of Cell Adhesion Molecules in Human Endothelial Cell Lines and Relaxes Blood Vessels in Rat Aortic Rings

The incidence of cardiovascular diseases, such as high blood pressure, is increasing worldwide, owing to population aging and irregular lifestyle habits. Previous studies have reported the vasorelaxant effects of Prunus yedoensis bark methanol extract. However, various solvent extracts of P. yedoensis bark and their vascular relaxation mechanisms have not been sufficiently studied. We prepared extracts of P. yedoensis bark using various solvents (water, 30% ethanol, and 70% ethanol). P. yedoensis bark 30% ethanol extract (PYB-30E) decreased the expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin in human umbilical vein endothelial cells (HUVECs) activated with 200 ng/mL TNF-α. Additionally, PYB-30E showed vasodilatory effects on isolated rat aortic rings. This was confirmed to be the result of the activation of the NO/cGMP pathway, regulation of non-selective calcium-activated K+ channels, and calcium channel blockade. Additionally, PYB-30E significantly reduced systolic and diastolic blood pressure in spontaneously hypertensive rats (SHR). Taken together, our results indicated that PYB-30E is a candidate functional material with preventive and therapeutic effects against hypertension.

Investigating the therapeutic effects and mechanisms of Carthamus tinctorius L.-derived nanovesicles in atherosclerosis treatment

BACKGROUND

Carthamus tinctorius L., a traditional herbal medicine used for atherosclerosis (AS), lacks a clear understanding of its therapeutic mechanisms. This study aimed to investigate the therapeutic effects and mechanisms of Carthamus tinctorius L.-derived nanovesicles (CDNVs) in AS treatment.

METHODS

CDNVs were isolated and characterized using improved isolation methods. Transmission electron microscopy, nanoparticle tracking analysis, and protein analysis confirmed their morphology, size, and protein composition. Small RNA sequencing was performed to identify the miRNA profile of CDNVs, and bioinformatics analysis was used to determine their potential biological roles. In vivo biodistribution and toxicity studies were conducted in mice to assess the stability and safety of orally administered CDNVs. The anti-atherosclerotic effects of CDNVs were evaluated in ApoE-/- mice through plaque burden analysis. The protective effects of CDNVs on ox-LDL-treated endothelial cells were assessed through proliferation, apoptosis, reactive oxygen species activation, and monocyte adhesion assays. miRNA and mRNA sequencing of CDNV-treated endothelial cells were performed to explore their regulatory effects and potential target genes.

RESULTS

CDNVs were successfully isolated and purified from Carthamus tinctorius L. tissue lysates. They exhibited a saucer-shaped or cup-shaped morphology, with an average particle size of 142.6 ± 0.7 nm, and expressed EV markers CD63 and TSG101. CDNVs contained proteins, small RNAs, and metabolites, including the therapeutic compound HSYA. Small RNA sequencing identified 95 miRNAs, with 10 common miRNAs accounting for 72.63% of the total miRNAs. These miRNAs targeted genes involved in cell adhesion, apoptosis, and cell proliferation, suggesting their relevance in cardiovascular disease. Orally administered CDNVs were stable in the gastrointestinal tract, absorbed into the bloodstream, and accumulated in the liver, lungs, heart, and aorta. They significantly reduced the burden of atherosclerotic plaques in ApoE-/- mice and exhibited superior effects compared to HSYA. In vitro studies demonstrated that CDNVs were taken up by HUVECs, promoted proliferation, attenuated ox-LDL-induced apoptosis and ROS activation, and reduced monocyte adhesion. CDNV treatment resulted in significant changes in miRNA and mRNA expression profiles of HUVECs, with enrichment in inflammation-related genes. CXCL12 was identified as a potential direct target of miR166a-3p.

CONCLUSION

CDNVs isolated from Carthamus tinctorius L. tissue lysates represent a promising oral therapeutic option for cardiovascular diseases. The delivery of miRNAs by CDNVs regulates inflammation-related genes, including CXCL12, in HUVECs, suggesting their potential role in modulating endothelial inflammation. These findings provide valuable insights into the therapeutic potential of CDNVs and their miRNAs in cardiovascular disease.

Long non‑coding RNA MALAT1 regulates cholesterol accumulation in ox‑LDL‑induced macrophages via the microRNA‑17‑5p/ABCA1 axis

Atherosclerosis (AS), a major cause of cardiovascular disease, has developed into a serious challenge to the health system. The long non-coding RNA (lncRNA) metastasis associated lung adenocarcinoma transcript 1 (MALAT1) is associated with the pathogenesis of AS. However, whether MALAT1 can affect cholesterol accumulation in macrophages during AS progression, and the potential molecular mechanism involved in this progression have not been elucidated. In the present study, the mRNA expression level of MALAT1 was measured using reverse transcription-quantitative PCR (RT-qPCR) and the protein expression level was detected via western blot analysis. Oil Red O staining was used for detecting lipid accumulation in macrophages. Bioinformatics, dual-luciferase reporter and RT-qPCR assays were used to investigate the relationship between MALAT1 and the microRNA (miR)-17-5p/ATP-binding cassette transporter A1 (ABCA1) axis. The present results suggested that the MALAT1 expression level was significantly decreased in patients with AS and in oxidized low-density lipoprotein (ox-LDL)-stimulated macrophages. Knockdown of MALAT1 increased ox-LDL uptake, lipid accumulation and the total cholesterol (T-CHO) level in ox-LDL-induced macrophages. In addition, MALAT1 inhibition significantly decreased the mRNA and protein expression levels of scavenger receptor (SR) class B member 1, apolipoprotein E (ApoE) and ABCA1. However, MALAT1 increased the expression level of SR class A. Subsequently, the present study investigated whether MALAT1 could target miR-17-5p to regulate the expression level of ABCA1, which is involved in cholesterol efflux from macrophages. The present results suggested that inhibition of miR-17-5p reversed the effects of MALAT1 knockdown on T-CHO content, and protein expression levels of ApoE and ABCA1 in ox-LDL-stimulated macrophages. In summary, knockdown of MALAT1 may promote cholesterol accumulation by regulating the miR-17-5p/ABCA1 axis in ox-LDL-induced THP-1 macrophages.

The role of T-lymphocyte subpopulations in acute myocardial infarction

T lymphocytes have the potential to affect atherosclerosis at different stages of the process. They play an active role in acute myocardial infarction (AMI) and myocardial damage, and may affect the clinical outcome of patients with coronary artery disease. CD40 ligand expression on T lymphocytes promotes the expression of matrix-degrading enzymes in vascular smooth muscle cells and may thus establish a new pathway of immune-mediated destabilization of the human atheroma. The major class of T lymphocytes present in atherosclerotic lesions is CD4+. CD4+ cells differentiate into Th1 and Th2 lineage in response to the local milieu of cytokines. Much of the emphasis in atherosclerosis research is focused on the role of Th1 type responses.

Inflammatory and thrombotic mechanisms in coronary atherosclerosis

Many molecular and cellular mechanisms link inflammation and haemostatic mechanisms. Inflammation, and perhaps chronic infection, may play important roles in the initiation and progression of atherosclerosis. Atherosclerotic lesions are heavily infiltrated by cellular components associated with inflammation (macrophages and T lymphocytes), and acute plaque rupture is also associated with inflammatory components. Several markers of systemic inflammation may predict future cardiovascular events in apparently healthy subjects as well as in patients with chronic and acute syndromes. There may thus be therapeutic potential in modifying the atherosclerotic, vasomotor, and thrombotic components of ischaemic heart disease.

Sustained long-term improvement of arterial endothelial function in heterozygous familial hypercholesterolemia patients treated with simvastatin

Patients with heterozygous familial hypercholesterolemia (hFH) are at very high risk for premature coronary heart disease. In the last decade, treatment with statins has reduced cardiovascular mortality in these patients. The aim of this study was to analyze arterial endothelial function assessed as flow-mediated dilatation (FMD) and soluble E-selectin (sE-selectin) levels in patients with hFH under a long-term lipid-lowering treatment. Twenty-five patients who completed the study received a dose of simvastatin to achieve a treatment goal of at least 30% reduction in serum low-density lipoprotein (LDL)-cholesterol (LDL-C) for 52 weeks. Functional and biochemical measurements were taken at entry, and at week 12 and 52 of treatment. FMD was measured by vascular ultrasound of the brachial artery. sE-selectin, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 were determined by enzyme linked immunosorbent assay (ELISA). LDL-C levels were significantly reduced by treatment at week 12 and maintained at week 52 (reduction vs. baseline, 44+/-12 and 43+/-11%, respectively, P<0.0001). A significant improvement in endothelial function, measured as FMD (baseline, 4.7+/-6.2%; 12 weeks, 12.3+/-5.9%; 52 weeks, 9.7+/-4.7%; P<0.005) and a reduction in sE-selectin levels (baseline, 16.2+/-3.4 ng/ml; 12 weeks, 11.0+/-3.2 ng/ml; 52 weeks, 12.3+/-4.2 ng/ml; P<0.01) were observed. Endothelial-independent relaxation induced by nitroglycerin was not modified during the study. Our results indicate that a long-term treatment with simvastatin produced a sustained beneficial effect in endothelial function in hFH patients.

T lymphocyte activation and restenosis after percutaneous transluminal coronary angioplasty

We investigated the relation between the activation of T lymphocytes and the occurrence of restenosis after percutaneous transluminal coronary angioplasty (PTCA) in 10 stable angina patients. Recent studies have suggested that PTCA causes an inflammatory response, which may affect restenosis after angioplasty. Soluble interleukin-2 receptor (sIL-2R) is a useful marker to evaluate the activation of T lymphocytes. sIL-2R was measured before and 2 h after successful PTCA, and 3-month follow-up coronary angiography was done to observe restenosis. Four of 10 patients showed restenosis. The restenosis group of 4 patients had a higher level of sIL-2R after PTCA than the no-restenosis group of 6 patients (495 vs. 274 U/ml, p < 0.01). This study suggests that sIL-2R may offer prognostic information after elective PTCA and identify a subgroup of patients at high risk for clinical restenosis in a few months.

Development of atherosclerotic plaque with endothelial disruption in Watanabe heritable hyperlipidemic rabbit aortas

To better understand the morphogenesis of atherosclerotic plaque, we evaluated temporal distribution of leukocytes, macrophages, foam cells, vascular smooth muscle cells, and subendothelial lipid in Watanabe heritable hyperlipedimic (WHHL) rabbit aortas. Aortas of WHHL (n=20) and New Zealand White (NZW, controls; n=8) rabbits were perfusion fixed at 1, 3, 6, and 12 months of age. At initial gross evaluation of lipid distribution, we identified aortic areas at high risk for lesion development. In WHHL rabbits, the lipid-positive portion of high-risk areas increased from 3% at 1 month to 50% at 12 months; during the same period, adherent cell count increased from <1 leukocyte and monocyte/mm(2) to 25 leukocytes, 44 monocytes, and 10 foam cells/mm(2). Controls showed no increase over time in lipid-positive areas or cellular adherence to the endothelium. One-month-old WHHL rabbit aortas had scattered lipid-positive cells in the intima (primarily branch points). Immunostaining of these areas did not show rabbit macrophages (RAM antibody) but were actin positive. Occasionally, platelets and monocytes adhered to the endothelial surface. By age 3 months, well-defined fatty streaks/atherosclerotic plaques had RAM-positive cells within foam cell core, along core margins, and in focal clusters in the fibrous cap and subendothelium. By age 12 months, isolated RAM-positive cells were on the endothelial surface, and surface morphology showed endothelial cell disruption foci containing clusters of macrophages and foam cells. Our results indicate that lipid accumulation (extra- and intracellular) is important in the early development of atherosclerotic lesions; a corresponding, slower accumulation of adherent cells on the lesion surface promotes lipid conversion from fatty streak to plaque.

L-selectin and ICAM-1 mediate reperfusion injury and neutrophil adhesion in the warm ischemic mouse liver

Leukocytes recruited during ischemia-reperfusion to the liver are important mediators of injury. However, the mechanisms of leukocyte adhesion and the role of adhesion receptors in hepatic vasculature remain elusive. L-selectin may critically contribute to injury, priming adhesion for later action of intercellular adhesion molecule-1 (ICAM-1). Paired experiments were performed using mutant mice (L-selectin -/-, ICAM-1 -/-, and L-selectin/ICAM-1 -/-) and wild-type mice (C57BL/6) to investigate leukocyte adhesion in the ischemic liver. Leukocyte adhesion and infiltration were assessed histologically. Aspartate aminotransferase levels were significantly reduced (2- to 3-fold) in mutant vs. wild-type mice in most groups but most significantly after 90 min of partial hepatic ischemia. Leukocyte adhesion was significantly reduced in all mutant mice. Areas of microcirculatory failure, visualized by intravital microscopy, were prevalent in wild-type but virtually absent in L-selectin-deficient mice. After total hepatic ischemia for 75 or 90 min, survival was better in mutant L-selectin and L-selectin/ICAM-1 mice vs. wild-type mice and ICAM-1 mutants. In conclusion, L-selectin is critical in the pathogenesis of hepatic ischemia-reperfusion injury. Poor sinusoidal perfusion due to leukocyte adhesion and clot formation is a factor of injury and appears to involve L-selectin and ICAM-1 receptors.

T lymphocyte activation in stable angina pectoris and after percutaneous transluminal coronary angioplasty

BACKGROUND

Inflammatory reactions have an important part in atherosclerosis. Smooth muscle cells, endothelial cells, monocytes, and T lymphocytes are actively involved. The purpose of this study was to assess whether T lymphocytes are activated in patients with stable angina pectoris who are candidates for a percutaneous transluminal coronary angioplasty (PTCA) and the influence of PTCA on this process.

METHODS AND RESULTS

Twenty-four patients participated in the study. All were 40- to 60-year-old men, and all but one underwent successful PTCA. Blood samples were taken 1 day before PTCA and 1 week, 1 month, and 2 months after. Two groups of patients were detected: group A, 11 patients who had high levels of soluble interleukin-2 receptor (sIL-2R) before PTCA that decreased toward normal during the follow-up period in most of them; and group B, 13 patients who did not have elevated sIL-2R levels before PTCA and in whom sIL-2R levels did not change after the procedure. Group C consisted of 15 healthy men whose sIL-2R levels were in the normal range (control subjects).

CONCLUSIONS

(1) T lymphocytes are activated in stable angina patients. (2) The level of sIL-2R can be a reliable laboratory marker for follow-up of patients after PTCA, especially those with high sIL-2R levels before the procedure.

Endothelial injury during extracorporeal circulation: neutrophil-endothelium interaction induced by complement activation

This study was designed to understand the physiologic intravascular and intradevice events at the cellular level following complement system activation during extracorporeal circulation. The addition of anaphylatoxin C5a or complement-activated serum into neutrophil- or endothelial cell-suspensions resulted in a dose-dependent transmembrane stimulation that was assessed by an intracellular free calcium ion mobilization technique using a calcium-sensitive photoprotein, aequorin. The adhesion and ruffle formation of neutrophils on endothelial cell monolayers were markedly enhanced when both cell types were treated with C5a or activated serum. The significance of complement activation on intravascular events during extracorporeal circulation is emphasized and discussed from the viewpoint of surface-expressed adhesion molecules.

The distribution of adhesion molecules in chronic periaortitis

Chronic periaortitis is a local complication of human atherosclerosis. It is defined as the triad of advanced atherosclerosis, medical thinning and aortic adventitial chronic inflammation. It is present to a variable degree in association with atherosclerotic abdominal aortic aneurysms. These aortic adventitial infiltrates differ from those described solely within the atheroma itself, in that they consist predominantly of B lymphocytes. Many of the lymphocytes are activated and proliferating, and germinal centres are common. In this study, an immunohistochemical analysis was carried out on fresh surgical aortic aneurysm tissue in order to investigate the presence and distribution of activation-inducible adhesion molecules, and to correlate this with the degree of inflammation. A consistent finding was the presence of E-selectin on endothelial cells in up to 50% of the vessels throughout the aortic wall and at the base of the atheroma, independent of the severity of inflammation. ICAM-1 expression was abundant on many cell types and increased with the severity of chronic inflammation, being strongest in the germinal centres. VCAM-1 expression was predominant on follicular dendritic cells and also increased with severity of inflammation. VCAM-1 expression was also detected on vessels within lymphoid follicles. The pattern of expression of the adhesion molecules suggests a role in the initiation and progression of chronic inflammation associated with advanced atherosclerosis.

Perforin expression localizing cytotoxic lymphocytes in the intimas of coronary arteries with transplant-related accelerated arteriosclerosis

Accelerated arteriosclerosis is the major long-term complication of cardiac transplantation. It has been demonstrated recently that accelerated arteriosclerosis is caused, in part, by rejection-related, cell-mediated immunity. However, the role of cytotoxic T lymphocytes in this process is a subject of controversy. Perforin is a specific marker of functionally active cytotoxic lymphocytes because it is a functional component of the cytotoxic granules of these cells. We examined 11 coronary arteries from seven autopsied and four retransplanted heart transplant recipients for the presence of perforin-containing lymphocytes. Immunohistochemical stains for perforin were performed using a monoclonal antibody against human perforin. Eight of the 11 coronary arteries examined were found to contain perforin-positive cells. These perforin-positive cells were present in subendothelial spaces of the coronary arteries, and the staining seen was cytoplasmic and granular. The granules often were polarized to the endothelial surface. Furthermore, the cells identified were usually in close proximity to, or in direct contact with, coronary artery endothelial cells. These results suggest that cell-mediated endothelial injury by perforin-positive cytotoxic lymphocytes may contribute to the development of accelerated arteriosclerosis in heart transplant recipients.