Hypoxia accelerates intraplaque neovascularization derived from endothelial progenitor cells in carotid stenosis

Impact of distribution of carotid intraplaque neovessels on plaque vulnerability

BACKGROUND AND PURPOSE

Intraplaque neovessels (INVs) are considered important contributors to carotid plaque vulnerability. The purpose of this study was to examine whether differences in INV distribution affect plaque vulnerability.

METHODS

The study cohort comprised 110 patients with significant stenosis of the carotid artery who had undergone carotid endarterectomy. The distribution of INVs within carotid plaques was assessed by immunohistochemical studies using anti-CD-34 antibody as a marker for endothelial cells. First, we divided the patients into M group and S group depending on the numbers of INVs in middle and shoulder region. Next, we categorized carotid plaques into four categories according to the distributions of INVs: Shoulder, Middle, Mixed, and Scarce. We then compared total area of intraplaque hemorrhage, cholesterol, and calcification, width of thinnest fibrous cap, and number of INVs between the four categories of plaque.

RESULTS

The area of intraplaque hemorrhage was significantly larger in the M group than in the S group (P = 0.011). Meanwhile, symptomatic carotid stenosis was significantly more frequently associated with the Middle and Mixed than the Shoulder and Scarce categories (P < 0.01). The area of intraplaque hemorrhage was significantly different between the four groups (P = 0.022). Rupture of the fibrous cap was more frequently detected in the Middle and Mixed than the other categories (P = 0.002).

CONCLUSIONS

INVs in the middle region of carotid plaques are strongly associated with symptomatic carotid stenosis, intraplaque hemorrhage, and rupture of the fibrous cap. Our findings indicate that the distribution of INVs may affect plaque vulnerability.

Added Clinical Value of Intraplaque Neovascularization Detection to Color Doppler Ultrasound for Assessing Ischemic Stroke Risk

Purpose

Intraplaque neovascularization, assessed using contrast-enhanced ultrasound (CEUS), is associated with ischemic stroke. It remains unclear whether detection of intraplaque neovascularization combined with color Doppler ultrasound (CDUS) provides additional value compared with CDUS alone in assessing ischemic stroke risk. Therefore, we investigated the clinical value of combined CEUS, CDUS, and clinical features for ischemic stroke risk stratification.

Patients and Methods

We recruited 360 patients with ≥50% carotid stenosis between January 2019 and September 2022. Patients were examined using CDUS and CEUS. Covariates associated with ischemic stroke were identified using multivariate logistic regression analysis. The discrimination and calibration were verified using the C-statistic and Hosmer-Lemeshow test. The incremental value of intraplaque neovascularization in the assessment of ischemic stroke was analyzed using the Delong test.

Results

We analyzed the data of 162 symptomatic and 159 asymptomatic patients who satisfied the inclusion and exclusion criteria, respectively. Based on multivariate logistic regression analysis, we constructed a nomogram using intraplaque neovascularization, degree of carotid stenosis, plaque hypoechoicity, and smoking status, with a C-statistic of 0.719 (95% confidence interval [CI]: 0.666-0.768) and a Hosmer-Lemeshow test p value of 0.261. The net reclassification index of the nomogram was 0.249 (95% CI: 0.138-0.359), and the integrated discrimination improvement was 0.053 (95% CI: 0.029-0.079). Adding intraplaque neovascularization to the combination of CDUS and clinical features (0.672; 95% CI: 0.617-0.723) increased the C-statistics (p=0.028).

Conclusion

Further assessment of intraplaque neovascularization after CDUS may help more accurately identify patients at risk of ischemic stroke. Combining multiparametric carotid ultrasound and clinical features may help improve the risk stratification of patients with ischemic stroke with ≥50% carotid stenosis.

A Review Into the Insights of the Role of Endothelial Progenitor Cells on Bone Biology

In addition to its important transport functions, the skeletal system is involved in complex biological activities for the regulation of blood vessels. Endothelial progenitor cells (EPCs), as stem cells of endothelial cells (ECs), possess an effective proliferative capacity and a powerful angiogenic capacity prior to their differentiation. They demonstrate synergistic effects to promote bone regeneration and vascularization more effectively by co-culturing with multiple cells. EPCs demonstrate a significant therapeutic potential for the treatment of various bone diseases by secreting a combination of growth factors, regulating cellular functions, and promoting bone regeneration. In this review, we retrospect the definition and properties of EPCs, their interaction with mesenchymal stem cells, ECs, smooth muscle cells, and immune cells in bone regeneration, vascularization, and immunity, summarizing their mechanism of action and contribution to bone biology. Additionally, we generalized their role and potential mechanisms in the treatment of various bone diseases, possibly indicating their clinical application.

Associations between Circulating VEGFR2hi-Neutrophils and Carotid Plaque Burden in Patients Aged 40-64 without Established Atherosclerotic Cardiovascular Disease

Background

Neutrophils expressing vascular endothelial growth factor receptor (VEGFR) represent a distinct subtype of neutrophils with proangiogenic properties. The purpose of this study was to identify the interrelations between circulating CD16^hiCD11b^hiCD62L^loCXCR2^hiVEGFR2^hi-neutrophils and indicators of carotid plaque burden in patients without atherosclerotic cardiovascular diseases (ASCVD).

Methods

The study included 145 patients, 51.7% men and 48.3% women, median age—49.0 years. All patients underwent carotid duplex ultrasound scanning. The maximal carotid plaque thickness was used as an indicator of carotid plaque burden. Also, carotid intima-media thickness (cIMT) and femoral IMT were measured. The phenotyping of neutrophil subpopulations was executed by the flow cytometry via the Navios 6/2. Results. The subpopulation of VEGFR2^hi-neutrophils accounted for about 5% of the total pool of circulating neutrophils. A decrease in VEGFR2^hi-neutrophils with an increase in carotid plaque burden was statistically significant (p = 0.036). A decrease in VEGFR2^hi-neutrophils < 4.52% allowed to predict the presence of plaque with a maximum height > 2.1 mm (Q4), with sensitivity of 78.9% and specificity of 61.5% (AUC 0.693; 95% CI 0.575-0.811; p = 0.007). Inverse correlations were established between the carotid and femoral IMT and the absolute and relative number of VEGFR2^hi-neutrophils (p < 0.01).

Conclusion

In patients aged 40-64 years without established ASCVD, with an increase in indicators of the carotid plaque burden, a significant decrease in the proportion of circulating VEGFR2^hi-neutrophils was noticed. A decrease in the relative number of VEGFR2^hi-neutrophils of less than 4.52% made it possible to predict the presence of extent carotid atherosclerosis with sensitivity of 78.9% and specificity of 61.5%.

Neutrophil-to-lymphocyte ratio is associated with carotid intraplaque neovascularization in asymptomatic carotid stenosis patients

BACKGROUND AND PURPOSE

Neutrophil-to-lymphocyte ratio (NLR) has been suggested as an available systemic inflammatory biomarker. This study aims to evaluate whether intraplaque neovascularization assessed by contrast-enhanced ultrasound (CEUS) is associated with NLR in asymptomatic carotid stenosis patients.

MATERIALS AND METHODS

One hundred and forty-four asymptomatic patients with carotid luminal stenosis >30% were assessed using contrast-enhanced ultrasound imaging. The contrast enhancement within the plaque was classified on a visual semiquantitative grading scale. The data collected included the patient's risk factors, laboratory results, cardiovascular disease history, and drug use history. Univariate and multivariate analyses were assessed to identify independent factors related to intraplaque neovascularization with adjustment for potential confounders.

RESULTS

Patients with CEUS grade 2 plaques had a higher level of LDL-C (p < .001), neutrophil count (p < .001), and blood glucose (p = .005), but lower level of lymphocyte count (p = .021). The presence of grade 2 plaques was significantly associated with high NLR values (OR 1.21, 95% CI 1.03-1.43, p = .017). Patients were divided into four groups according to the quartile of NLR values. Compared to the patients in the first quartile of NLR (<1.73), the patients in the fourth NLR quartile (≥3.38) were characterized by the most prevalence of CEUS grade 2 plaques (OR 4.55, 95% CI 1.69-12.25, p = .003). Multivariate logistic regression analysis after adjusting various variables demonstrated NLR remained an independent risk factor for the presence of CEUS grade 2 plaques.

CONCLUSION

Intraplaque neovascularization is significantly associated with NLR in asymptomatic carotid stenosis patients.

Macrophage-Hypoxia-Inducible Factor-1α Signaling in Carotid Artery Stenosis

Macrophages play crucial and diverse roles in the pathogenesis of inflammatory vascular diseases. Macrophages are the principal innate immune cells recruited to arterial walls to govern vascular homeostasis by modulating the proliferation of vascular smooth muscle cells, the reorganization of extracellular matrix components, the elimination of dead cells, and the restoration of normal blood flow. However, chronic sterile inflammation within the arterial walls draws inflammatory macrophages into intimal/neointimal regions that may contribute to disease pathogenesis. In this context, the accumulation and aberrant activation of macrophages in the neointimal regions govern the progression of inflammatory arterial wall diseases. Herein, we report that myeloid-hypoxia-inducible factor-1α (HIF1α) deficiency attenuates vascular smooth muscle cells and macrophage abundance in stenotic arteries and abrogates carotid neointima formation in vivo. The integrated transcriptomics, Gene Set Enrichment Analysis, metabolomics, and target gene evaluation showed that HIF1α represses oxidative phosphorylation, tricarboxylic acid cycle, fatty acid metabolism, and c-MYC signaling pathways while promoting inflammatory, glycolytic, hypoxia response gene expression in stenotic artery macrophages. At the molecular level, proinflammatory agents utilized STAT3 signaling pathways to elevate HIF1α expression in macrophages. Collectively, this study uncovers that macrophage-HIF1α deficiency restrains the pathogenesis of carotid artery stenosis by rewiring inflammatory and metabolic signaling pathways in macrophages.

Dilated microvessel with endothelial cell proliferation involves intraplaque hemorrhage in unstable carotid plaque

BACKGROUND

The purpose of the present study was to clarify the characteristics of endothelial cell (EC) proliferation in intraplaque microvessels in vulnerable plaques and impact on clinical results.

METHODS

The present study included 76 patients who underwent carotid endarterectomy. Patients were classified into three groups based on their symptoms: asymptomatic, symptomatic without recurrent ischemic event, and symptomatic with recurrent ischemic event. MR plaque imaging was performed and surgical specimens underwent immunohistochemical analysis. The number of CD31⁺ microvessels, and Ki67⁺ and CD105⁺ ECs in the carotid plaques was quantified, as measurements of maximum CD31⁺ microvessel diameter.

RESULTS

MR plaque imaging yielded 41 subjects (54.0%) diagnosed with plaque with intraplaque hemorrhage (IPH), 14 subjects (18.4%) diagnosed with fibrous plaques, and 21 (27.6%) subjects diagnosed with lipid-rich plaques. The average largest diameter of microvessel in fibrous plaques, lipid-rich plaques, and plaque with IPH was 12.7 ± 4.1 μm, 31.3 ± 9.3 μm, and 56.4 ± 10.0 μm, respectively (p < 0.01). Dilated microvessels (>40 μm) were observed in 9.6% of plaques with IPH but only in 2.8% of lipid-rich plaques and 0% of fibrous plaques (p < 0.01). Ki67⁺/CD31⁺ ECs were identified in 2.8 ± 1.2% of fibrous plaques, 9.6 ± 6.9% of lipid-rich plaques, and in 19.5 ± 5.9% of plaques with IPH (p < 0.01). The average largest diameter of microvessels in the asymptomatic group was 17.1 ± 8.7 μm, 32.3 ± 10.8 μm in the symptomatic without recurrence group, and 55.2 ± 13.2 μm in the symptomatic with recurrence group (p < 0.01).

CONCLUSION

Dilated microvessels with proliferative ECs may play a key role in IPH pathogenesis. Furthermore, dilated microvessels are likely related to clinical onset and the recurrence of ischemic events. The purpose of the present study was to clarify the characteristics of EC proliferation in intraplaque microvessels in vulnerable plaques and their impact on clinical results, focusing on dilated intraplaque microvessels.