Atorvastatin pleiotropically decreases intraplaque angiogenesis and intraplaque haemorrhage by inhibiting ANGPT2 release and VE-Cadherin internalization

Pathological angiogenesis: mechanisms and therapeutic strategies

In multicellular organisms, angiogenesis, the formation of new blood vessels from pre-existing ones, is an essential process for growth and development. Different mechanisms such as vasculogenesis, sprouting, intussusceptive, and coalescent angiogenesis, as well as vessel co-option, vasculogenic mimicry and lymphangiogenesis, underlie the formation of new vasculature. In many pathological conditions, such as cancer, atherosclerosis, arthritis, psoriasis, endometriosis, obesity and SARS-CoV-2(COVID-19), developmental angiogenic processes are recapitulated, but are often done so without the normal feedback mechanisms that regulate the ordinary spatial and temporal patterns of blood vessel formation. Thus, pathological angiogenesis presents new challenges yet new opportunities for the design of vascular-directed therapies. Here, we provide an overview of recent insights into blood vessel development and highlight novel therapeutic strategies that promote or inhibit the process of angiogenesis to stabilize, reverse, or even halt disease progression. In our review, we will also explore several additional aspects (the angiogenic switch, hypoxia, angiocrine signals, endothelial plasticity, vessel normalization, and endothelial cell anergy) that operate in parallel to canonical angiogenesis mechanisms and speculate how these processes may also be targeted with anti-angiogenic or vascular-directed therapies.

Comparison the therapeutic effects of bone marrow CD144+ endothelial cells and CD146+ mesenchymal stem cells in POF rats

Introduction

Premature ovarian insufficiency (POI) is a challenging issue in terms of reproduction biology. In this study, therapeutic properties of bone marrow CD146+ mesenchymal stem cells (MSCs) and CD144+ endothelial cells (ECs) were separately investigated in rats with POI.

Methods

POI rats were classified into control POI, POI + CD146+ MSCs, and POI + CD144+ ECs groups. Enriched CD146+ MSCs and CD144+ ECs were directly injected into ovarian tissue (15 × 104 cells/10 μL) in relevant groups. After 4 weeks, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol (E2) levels were measured in blood samples. Ovarian tissues were collected and subjected to Hematoxylin-Eosin and Masson's trichrome staining. The expression of angp-2, vegfr-2, smad-2, -4, -6, and tgf-β1 was studied using qRT-PCR analysis. Histopathological examination indicated an increased pattern of atretic follicles in the POI group related to the control rats (P<0.0001).

Results

Data indicated that injection of POI + CD146+ MSCs and CD144+ ECs in POI rats reduced atretic follicles and increased the number of normal follicles (P<0.01). Along with these changes, the content of blue-colored collagen fibers was diminished after cell transplantation. Besides, cell transplantation in POI rats had the potential to reduce increased FSH, and LH levels (P<0.05). In contrast, E2 content was increased in POI + CD146+ MSCs and POI + CD144+ ECs groups compared to control POI rats, indicating restoration of follicular function. CD144+ (smad-2, and -4) and CD146+ (smad-6) cells altered the activity of genes belonging TGF-β signaling pathway. Unlike POI + CD146+ MSCs, aberrant angiogenesis properties were significantly down-regulated in POI + CD144+ ECs related to the control POI group (P<0.05).

Conclusion

The transplantation of bone marrow CD146+ and CD144+ cells can lead to the restoration of ovarian tissue function in POI rats via modulating different mechanisms associated with angiogenesis and fibrosis.

Biliverdin Reductase B Is a Plasma Biomarker for Intraplaque Hemorrhage and a Predictor of Ischemic Stroke in Patients with Symptomatic Carotid Atherosclerosis

BACKGROUND

Intraplaque hemorrhage (IPH) is a hallmark of atherosclerotic plaque instability. Biliverdin reductase B (BLVRB) is enriched in plasma and plaques from patients with symptomatic carotid atherosclerosis and functionally associated with IPH.

OBJECTIVE

We explored the biomarker potential of plasma BLVRB through (1) its correlation with IPH in carotid plaques assessed by magnetic resonance imaging (MRI), and with recurrent ischemic stroke, and (2) its use for monitoring pharmacotherapy targeting IPH in a preclinical setting.

METHODS

Plasma BLVRB levels were measured in patients with symptomatic carotid atherosclerosis from the PARISK study (n = 177, 5 year follow-up) with and without IPH as indicated by MRI. Plasma BLVRB levels were also measured in a mouse vein graft model of IPH at baseline and following antiangiogenic therapy targeting vascular endothelial growth factor receptor 2 (VEGFR-2).

RESULTS

Plasma BLVRB levels were significantly higher in patients with IPH (737.32 ± 693.21 vs. 520.94 ± 499.43 mean fluorescent intensity (MFI), p = 0.033), but had no association with baseline clinical and biological parameters. Plasma BLVRB levels were also significantly higher in patients who developed recurrent ischemic stroke (1099.34 ± 928.49 vs. 582.07 ± 545.34 MFI, HR = 1.600, CI [1.092-2.344]; p = 0.016). Plasma BLVRB levels were significantly reduced following prevention of IPH by anti-VEGFR-2 therapy in mouse vein grafts (1189 ± 258.73 vs. 1752 ± 366.84 MFI; p = 0.004).

CONCLUSIONS

Plasma BLVRB was associated with IPH and increased risk of recurrent ischemic stroke in patients with symptomatic low- to moderate-grade carotid stenosis, indicating the capacity to monitor the efficacy of IPH-preventive pharmacotherapy in an animal model. Together, these results suggest the utility of plasma BLVRB as a biomarker for atherosclerotic plaque instability.

Identification of a Novel Angiogenesis Signalling circSCRG1/miR-1268b/NR4A1 Pathway in Atherosclerosis and the Regulatory Effects of TMP-PF In Vitro

Angiogenesis contributes to plaque instability in atherosclerosis and further increases cardio-cerebrovascular risk. Circular RNAs (circRNAs) are promising biomarkers and potential therapeutic targets for atherosclerosis. Previous studies have demonstrated that tetramethylpyrazine (TMP) and paeoniflorin (PF) combination treatment (TMP-PF) inhibited oxidized low-density lipoprotein (ox-LDL)-induced angiogenesis in vitro. However, whether circRNAs regulate angiogenesis in atherosclerosis and whether TMP-PF can regulate angiogenesis-related target circRNAs in atherosclerosis are unknown. In this study, human RNA sequencing (RNA-seq) data were analysed to identify differentially expressed (DE) circRNAs in atherosclerosis and to obtain angiogenesis-associated circRNA-microRNA (miRNA)-messenger RNA (mRNA) networks. Target circRNA-related mechanisms in angiogenesis in atherosclerosis and the regulatory effects of TMP-PF on target circRNA signalling were studied in ox-LDL-induced human umbilical vein endothelial cells (HUVECs) by cell proliferation, migration, tube formation, and luciferase reporter assays, real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting. A novel circRNA (circular stimulator of chondrogenesis 1, circSCRG1) was initially identified associated with angiogenesis in atherosclerosis, and circSCRG1 silencing up-regulated miR-1268b expression, increased nuclear receptor subfamily 4 group A member 1 (NR4A1) expression and then promoted ox-LDL-induced angiogenesis. TMP-PF (1 μmol/L TMP combined with 10 μmol/L PF) up-regulated circSCRG1 expression, mediated miR-1268b to suppress NR4A1 expression and then inhibited ox-LDL-induced angiogenesis. However, circSCRG1 silencing abolished the inhibitory effects of TMP-PF on ox-LDL-induced angiogenesis, which were rescued by the miR-1268b inhibitor. In conclusion, circSCRG1 might serve as a new target regulating angiogenesis in atherosclerosis via the circSCRG1/miR-1268b/NR4A1 axis and TMP-PF could regulate the circSCRG1/miR-1268b/NR4A1 axis to inhibit angiogenesis in atherosclerosis in vitro, indicating a novel angiogenesis signalling circSCRG1/miR-1268b/NR4A1 pathway in atherosclerosis and the regulatory effects of TMP-PF, which might provide a new pharmaceutical strategy to combat atherosclerotic plaque instability.

Molecular Mechanisms Underlying Pathological and Therapeutic Roles of Pericytes in Atherosclerosis

Pericytes are multipotent mesenchymal stromal cells playing an active role in angiogenesis, vessel stabilisation, maturation, remodelling, blood flow regulation and are able to trans-differentiate into other cells of the mesenchymal lineage. In this review, we summarised recent data demonstrating that pericytes play a key role in the pathogenesis and development of atherosclerosis (AS). Pericytes are involved in lipid accumulation, inflammation, growth, and vascularization of the atherosclerotic plaque. Decreased pericyte coverage, endothelial and pericyte dysfunction is associated with intraplaque angiogenesis and haemorrhage, calcification and cholesterol clefts deposition. At the same time, pericytes can be used as a novel therapeutic target to promote vessel maturity and stability, thus reducing plaque vulnerability. Finally, we discuss recent studies exploring effective AS treatments with pericyte-mediated anti-atherosclerotic, anti-inflammatory and anti-apoptotic effects.

Genetic landscape of FOXC2 mutations in lymphedema-distichiasis syndrome: Different mechanism of pathogenicity for mutations in different domains

Lymphedema-dissociated syndrome (LDS), of which the pathogenesis is not fully understood, afflicts many patients. In this study, we investigated the effect of FOXC2 gene loss-of-function on the development of LDS disease.Two Han Chinese families with LDS were recruited in this study, pathogenic mutations were identified by Sanger sequencing. Reverse-transcription PCR, subcellular localization, dual fluorescein enzymes, and other in vitro experiments were used to study the functional effects of eight FOXC2 mutations. Two pathogenic FOXC2 duplication mutations (c.930_936dup and c.931-937dup) were identified in the two families. Both mutations caused uneven distribution in the nucleus and a chromatin contraction phenotype, weakening the DNA binding activity and transcription activity. We then performed functional analysis on six additional mutations in different domains of FOXC2 that were reported to cause LDS. We found mutations located in the forkhead domain and central region dramatically reduced the transactivation ability, while mutations in activation domain-2 enhanced this ability. All 8 mutations down-regulated the transcription of ANGPT2 and affected the activity of the ERK-RAS pathway, which may cause abnormal formation of lymphatic vessels. Our findings also showed that all 8 mutations decreased the ability of interaction between FOXC2 and the Wnt4 promoter, suggesting mutations in FOXC2 may also affect the Wnt4-Frizzled-RYK signaling pathway, leading the abnormal differentiation of the meibomian glands into hair follicle cells during the embryonic period and causing distichiasis. This study expanded and revealed the potential pathogenesis mechanism.

Incident Rheumatoid Arthritis Following Statin Use: From the View of a National Cohort Study in Korea

Safety issues regarding the potential risk of statins and incident rheumatoid arthritis (RA) have been raised, but the existing data are largely based on Caucasian populations, and continue to have biases and require further validation in Asian populations. Here, we aimed to verify the risk of RA depending on the duration of previous statin use and statin types using a large-scale, nationwide database. This study enrolled 3149 patients with RA and 12,596 matched non-RA participants from the national health insurance database (2002−2015), and investigated their statin prescription histories for two years before the index date. Propensity score overlap-weighted logistic regression was applied after adjusting for multiple covariates. The prior use of any statins and, specifically, the long-term use of lipophilic statins (>365 days) were related to a lower likelihood of developing RA ((odds ratio (OR) = 0.73; 95% confidence intervals (CI) = 0.63−0.85, p < 0.001) and (OR = 0.71; 95% CI = 0.61−0.84, p < 0.001), respectively). Subgroup analyses supported these preventive effects on RA in those with dyslipidemia, independent of sex, age, smoking, alcohol use, hypertension, and hyperglycemia. Hydrophilic statin use or short-term use showed no such associations. Our study suggests that prior statin use, especially long-term lipophilic statin use, appears to confer preventive benefits against RA.

Interfering in the ALK1 Pathway Results in Macrophage-Driven Outward Remodeling of Murine Vein Grafts

Aims

Vein grafts are frequently used to bypass coronary artery occlusions. Unfortunately, vein graft disease (VGD) causes impaired patency rates. ALK1 mediates signaling by TGF-β via TGFβR2 or BMP9/10 via BMPR2, which is an important pathway in fibrotic, inflammatory, and angiogenic processes in vascular diseases. The role of the TGF-β pathway in VGD is previously reported, however, the contribution of ALK1 signaling is not known. Therefore, we investigated ALK1 signaling in VGD in a mouse model for vein graft disease using either genetic or pharmacological inhibition of the Alk1 signaling.

Methods and Results

Male ALK1 heterozygous (ALK1^+/−), control C57BL/6, as well as hypercholesterolemic ApoE3^*Leiden mice, underwent vein graft surgery. Histologic analyses of ALK1^+/− vein grafts demonstrated increased outward remodeling and macrophage accumulation after 28 days. In hypercholesterolemic ApoE3^*Leiden mice receiving weekly ALK1-Fc injections, ultrasound imaging showed 3-fold increased outward remodeling compared to controls treated with control-Fc, which was confirmed histologically. Moreover, ALK1-Fc treatment reduced collagen and smooth muscle cell accumulation, increased macrophages by 1.5-fold, and resulted in more plaque dissections. No difference was observed in intraplaque neovessel density. Flow cytometric analysis showed increased systemic levels of Ly6C^High monocytes in ALK1-Fc treated mice, supported by in vitro increased MCP-1 and IL-6 production of LPS-stimulated and ALK1-Fc-treated murine monocytes and macrophages.

Conclusion

Reduced ALK1 signaling in VGD promotes outward remodeling, increases macrophage influx, and promotes an unstable plaque phenotype.

Translational Perspective

Vein graft disease (VGD) severely hampers patency rates of vein grafts, necessitating research of key disease-driving pathways like TGF-β. The three-dimensional nature of VGD together with the multitude of disease driving factors ask for a comprehensive approach. Here, we combined in vivo ultrasound imaging, histological analyses, and conventional in vitro analyses, identifying the ambiguous role of reduced ALK1 signaling in vein graft disease. Reduced ALK1 signaling promotes outward remodeling, increases macrophage influx, and promotes an unstable plaque phenotype in murine vein grafts. Characterization of in vivo vascular remodeling over time is imperative to monitor VGD development and identify new therapies.

Where the Action Is-Leukocyte Recruitment in Atherosclerosis

Atherosclerosis is the leading cause of death worldwide and leukocyte recruitment is a key element of this phenomenon, thus allowing immune cells to enter the arterial wall. There, in concert with accumulating lipids, the invading leukocytes trigger a plethora of inflammatory responses which promote the influx of additional leukocytes and lead to the continued growth of atherosclerotic plaques. The recruitment process follows a precise scheme of tethering, rolling, firm arrest, crawling and transmigration and involves multiple cellular and subcellular players. This review aims to provide a comprehensive up-to-date insight into the process of leukocyte recruitment relevant to atherosclerosis, each from the perspective of endothelial cells, monocytes and macrophages, neutrophils, T lymphocytes and platelets. In addition, therapeutic options targeting leukocyte recruitment into atherosclerotic lesions-or potentially arising from the growing body of insights into its precise mechanisms-are highlighted.

PFKFB3 gene deletion in endothelial cells inhibits intraplaque angiogenesis and lesion formation in a murine model of venous bypass grafting

Vein grafting is a frequently used surgical intervention for cardiac revascularization. However, vein grafts display regions with intraplaque (IP) angiogenesis, which promotes atherogenesis and formation of unstable plaques. Graft neovessels are mainly composed of endothelial cells (ECs) that largely depend on glycolysis for migration and proliferation. In the present study, we aimed to investigate whether loss of the glycolytic flux enzyme phosphofructokinase-2/fructose-2,6-bisphosphatase 3 (PFKFB3) in ECs inhibits IP angiogenesis and as such prevents unstable plaque formation. To this end, apolipoprotein E deficient (ApoE^−/−) mice were backcrossed to a previously generated PFKFB3^fl/fl Cdh5^iCre mouse strain. Animals were injected with either corn oil (ApoE^−/−PFKFB3^fl/fl) or tamoxifen (ApoE^−/−PFKFB3^ECKO), and were fed a western-type diet for 4 weeks prior to vein grafting. Hereafter, mice received a western diet for an additional 28 days and were then sacrificed for graft assessment. Size and thickness of vein graft lesions decreased by 35 and 32%, respectively, in ApoE^−/−PFKFB3^ECKO mice compared to controls, while stenosis diminished by 23%. Moreover, vein graft lesions in ApoE^−/−PFKFB3^ECKO mice showed a significant reduction in macrophage infiltration (29%), number of neovessels (62%), and hemorrhages (86%). EC-specific PFKFB3 deletion did not show obvious adverse effects or changes in general metabolism. Interestingly, RT-PCR showed an increased M2 macrophage signature in vein grafts from ApoE^−/−PFKFB3^ECKO mice. Altogether, EC-specific PFKFB3 gene deletion leads to a significant reduction in lesion size, IP angiogenesis, and hemorrhagic complications in vein grafts. This study demonstrates that inhibition of endothelial glycolysis is a promising therapeutic strategy to slow down plaque progression.

Endothelial Barrier Function and Leukocyte Transmigration in Atherosclerosis

The vascular endothelium is a highly specialized barrier that controls passage of fluids and migration of cells from the lumen into the vessel wall. Endothelial cells assist leukocytes to extravasate and despite the variety in the specific mechanisms utilized by different leukocytes to cross different vascular beds, there is a general principle of capture, rolling, slow rolling, arrest, crawling, and ultimately diapedesis via a paracellular or transcellular route. In atherosclerosis, the barrier function of the endothelium is impaired leading to uncontrolled leukocyte extravasation and vascular leakage. This is also observed in the neovessels that grow into the atherosclerotic plaque leading to intraplaque hemorrhage and plaque destabilization. This review focuses on the vascular endothelial barrier function and the interaction between endothelial cells and leukocytes during transmigration. We will discuss the role of endothelial dysfunction, transendothelial migration of leukocytes and plaque angiogenesis in atherosclerosis.