AMD3100 treatment attenuates pulmonary angiogenesis by reducing the c-kit (+) cells and its pro-angiogenic activity in CBDL rat lungs

Endothelial glycocalyx in hepatopulmonary syndrome: An indispensable player mediating vascular changes

Hepatopulmonary syndrome (HPS) is a serious pulmonary vascular complication that causes respiratory insufficiency in patients with chronic liver diseases. HPS is characterized by two central pathogenic features-intrapulmonary vascular dilatation (IPVD) and angiogenesis. Endothelial glycocalyx (eGCX) is a gel-like layer covering the luminal surface of blood vessels which is involved in a variety of physiological and pathophysiological processes including controlling vascular tone and angiogenesis. In terms of lung disorders, it has been well established that eGCX contributes to dysregulated vascular contraction and impaired blood-gas barrier and fluid clearance, and thus might underlie the pathogenesis of HPS. Additionally, pharmacological interventions targeting eGCX are dramatically on the rise. In this review, we aim to elucidate the potential role of eGCX in IPVD and angiogenesis and describe the possible degradation-reconstitution equilibrium of eGCX during HPS through a highlight of recent literature. These studies strongly underscore the therapeutic rationale in targeting eGCX for the treatment of HPS.

Endothelial‐immune crosstalk contributes to vasculopathy in nonalcoholic fatty liver disease

The top cause of mortality in patients with nonalcoholic fatty liver disease (NAFLD) is cardiovascular complications. However, mechanisms of NAFLD‐associated vasculopathy remain understudied. Here, we show that blood outgrowth endothelial cells (BOECs) from NAFLD subjects exhibit global transcriptional upregulation of chemokines and human leukocyte antigens. In mouse models of diet‐induced NAFLD, we confirm heightened endothelial expressions of CXCL12 in the aortas and the liver vasculatures, and increased retention of infiltrated leukocytes within the vessel walls. To elucidate endothelial‐immune crosstalk, we performed immunoprofiling by single‐cell analysis, uncovering T cell intensification in NAFLD patients. Functionally, treatment with a CXCL12‐neutralizing antibody is effective at moderating the enhanced chemotactic effect of NAFLD BOECs in recruiting CD8⁺ T lymphocytes. Interference with the CXCL12‐CXCR4 axis using a CXCR4 antagonist also averts the impact of immune cell transendothelial migration and restores endothelial barrier integrity. Clinically, we detect threefold more circulating damaged endothelial cells in NAFLD patients than in healthy controls. Our work provides insight into the modulation of interactions with effector immune cells to mitigate endothelial injury in NAFLD.

Effect of Peptidylarginine Deiminase 4 on Endothelial Progenitor Cell Function in Peripheral Arterial Disease

At present, the global prevalence of peripheral arterial disease is increasing year by year, and it has become a worldwide disease. Studies have shown that transplanting endothelial progenitor cells (EPCs) into ischemic tissues can improve the tissue ischemia, thereby having a therapeutic effect on peripheral arterial diseases. This indicates that EPCs play a therapeutic effect in peripheral arterial disease. Recent studies have shown that peptidylarginine deiminase (PAD) is involved in the regulation of epigenetics and its inhibitor Cl-amidine can improve endothelium-dependent vasodilation and significantly reduce the formation of arterial thrombosis. It can also play a role in hematopoietic stem cells that share the same origin with EPCs. Therefore, we speculate that PAD4 may also have an effect on EPCs through a similar mechanism, thereby participating in the damage and repair of peripheral arterial disease. Therefore, we first detected the expression of PAD4 in EPCs of peripheral arterial disease and detected changes in the number and function of endothelial progenitor cells in peripheral blood after injecting the PAD4 inhibitor Cl-amidine into mice. A mouse model of lower limb ischemia was established to explore the effect of PAD4 on the function of EPCs in peripheral arterial disease. The results show that PAD4 is highly expressed in peripheral arterial diseases and the PAD4 inhibitor Cl-amidine can increase the number of EPCs and can treat peripheral arterial diseases by improving the proliferation, migration, and vascularization of EPCs.

Beta-Arrestins and Receptor Signaling in the Vascular Endothelium

The vascular endothelium is the innermost layer of blood vessels and is a key regulator of vascular tone. Endothelial function is controlled by receptor signaling through G protein-coupled receptors, receptor tyrosine kinases and receptor serine-threonine kinases. The β-arrestins, multifunctional adapter proteins, have the potential to regulate all of these receptor families, although it is unclear as to whether they serve to integrate signaling across all of these different axes. Notably, the β-arrestins have been shown to regulate signaling by a number of receptors important in endothelial function, such as chemokine receptors and receptors for vasoactive substances such as angiotensin II, endothelin-1 and prostaglandins. β-arrestin-mediated signaling pathways have been shown to play central roles in pathways that control vasodilation, cell proliferation, migration, and immune function. At this time, the physiological impact of this signaling has not been studied in detail, but a deeper understanding of it could lead to the development of novel therapies for the treatment of vascular disease.

EPO enhances the protective effects of MSCs in experimental hyperoxia-induced neonatal mice by promoting angiogenesis

Bronchopulmonary dysplasia (BPD) is the most common type of chronic lung disease in infancy; however, there is no effective treatment for it. In the present study, a neonatal mouse BPD model was established by continuous exposure to high oxygen (HO) levels. Mice were divided randomly into 5 groups: control, BPD, EPO, MSCs, and MSCs+EPO. At 2 weeks post-treatment, vessel density and the expression levels of endothelial growth factor (VEGF), stromal cell-derived factor-1 (SDF-1), and its receptor C-X-C chemokine receptor type 4 (CXCR4) were significantly increased in the MSC+EPO group compared with the EPO or MSCs group alone; moreover, EPO significantly enhanced MSCs proliferation, migration, and anti-apoptosis ability in vitro. Furthermore, the MSCs could differentiate into cells that were positive for the type II alveolar epithelial cell (AECII)-specific marker surfactant protein-C, but not positive for the AECI-specific marker aquaporin 5. Our present results suggested that MSCs in combination with EPO could significantly attenuate lung injury in a neonatal mouse model of BPD. The mechanism may be by the indirect promotion of angiogenesis, which may involve the SDF-1/CXCR4 axis.

The role of chemokines and chemokine receptors in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by progressive pulmonary artery remodelling leading to increased right ventricular pressure overload, which results in right heart failure and premature death. Inflammation plays a central role in the development of PAH, and the recruitment and function of immune cells are tightly regulated by chemotactic cytokines called chemokines. A number of studies have shown that the development and progression of PAH are associated with the dysregulated expression of several chemokines and chemokine receptors in the pulmonary vasculature. Moreover, some chemokines are differentially regulated in the pressure-overloaded right ventricle. Recent studies have tested the efficacy of pharmacological agents targeting several chemokines and chemokine receptors for their effects on the development of PAH, suggesting that these receptors could serve as useful therapeutic targets. In this review, we provide recent insights into the role of chemokines and chemokine receptors in PAH and RV remodelling and the opportunities and roadblocks in targeting them. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.1/issuetoc.

The Effects of the CXCR4 Antagonist, AMD3465, on Human Retinal Vascular Endothelial Cells (hRVECs) in a High Glucose Model of Diabetic Retinopathy

BACKGROUND High blood glucose levels in diabetes result in retinal angiogenesis, which is the key feature of diabetic retinopathy. This study aimed to investigate the effects of the CXCR4 antagonist, AMD3465, on human retinal vascular endothelial cells (hRVECs) [i]in vitro[/i]. MATERIAL AND METHODS Cell viability and the protein expression levels of CXCR4 and stromal cell-derived factor 1 (SDF-1) were evaluated in high glucose (HG)-treated human retinal vascular endothelial cells (hRVECs). The cell counting kit 8 (CCK-8) assay, the colony formation assay, immunofluorescence, and Western blot were used to investigate the effects of AMD3465 on hRVEC cell viability, colony formation, cell proliferation, and expression of CXCR4 and SDF-1. Cell apoptosis and angiogenesis were assessed by flow cytometry and Western blot. RESULTS Treatment with high glucose reduced the viability of hRVECs and increased the protein expression levels of CXCR4 and SDF-1. Following treatment with AMD3465, the colony formation capacity and cell proliferation in hRVECs increased, and there was a significant reduction in apoptosis rate compared with the untreated cells. AMD3465 significantly reduced the expression of angiogenesis-associated proteins, including ICAM1, VCAM1, VEGF, and AngII. AMD3465 significantly reduced the protein expression levels of TNF-α, IL-1β, NF-κB, and p-p65. CONCLUSIONS The CXCR4 antagonist, AMD3465, reduced apoptosis of HG-treated hRVECs in an [i]in vitro[/i] model of diabetic retinopathy.

Krüppel-like factor 6 mediates pulmonary angiogenesis in rat experimental hepatopulmonary syndrome and is aggravated by bone morphogenetic protein 9

Hepatopulmonary syndrome (HPS) is a serious pulmonary vascular disease derived from chronic liver disease, and its key pathogenesis is angiogenesis. Krüppel-like factor 6 (KLF6) mediates physiological repair and remodeling during vascular injury. However, the role of KLF6 in pulmonary microvascular endothelial cells (PMVECs) during angiogenesis of HPS and its underlying mechanism in HPS have not been investigated. Common bile duct ligation (CBDL) in rats can replicate pulmonary vascular abnormalities of human HPS. Here, we found that advanced pulmonary angiogenesis and pulmonary injury score coincided with the increase of KLF6 level in PMVECs of CBDL rat; KLF6 in PMVECs was also induced while cultured with CBDL rat serum in vitro. Inhibition of KLF6 dramatically suppressed PMVEC-mediated proliferation, migration and tube formation in vivo; this may be related to the downregulation of activin receptor-like kinase-1 (ALK1) and endoglin (ENG), which are transacted by KLF6. Bone morphogenetic protein 9 (BMP9) enhanced the expression of KLF6 in PMVECs and was involved in the angiogenesis of HPS. These results suggest that KLF6 triggers PMVEC-mediated angiogenesis of HPS and is aggravated by BMP9, and the inhibition of the BMP9/KLF6 axis may be an effective strategy for HPS treatment.

Summary: Krüppel-like factor 6, which is triggered by pulmonary injury and promoted by bone morphogenetic protein 9, mediates pulmonary angiogenesis in rat experimental hepatopulmonary syndrome and then aggravates lung dysfunction.

Mozobil® (Plerixafor, AMD3100), 10 years after its approval by the US Food and Drug Administration

AMD3100 (plerixafor, Mozobil®) was first identified as an anti-HIV agent specifically active against the T4-lymphotropic HIV strains, as it selectively blocked the CXCR4 receptor. Through interference with the interaction of CXCR4 with its natural ligand, SDF-1 (also named CXCL12), it also mobilized the CD34⁺stem cells from the bone marrow into the peripheral blood stream. In December 2008, AMD3100 was formally approved by the US FDA for autologous transplantation in patients with Non-Hodgkin’s Lymphoma or multiple myeloma. It may be beneficially used in various other malignant diseases as well as hereditary immunological disorders such as WHIM syndrome, and physiopathological processes such as hepatopulmonary syndrome.

Silibinin efficacy in a rat model of pulmonary arterial hypertension using monocrotaline and chronic hypoxia

Background

C-X-C chemokine receptor type 4 (CXCR4) may be involved in the development of pulmonary arterial hypertension (PAH). CXCR4 inhibitor AMD3100 was described to have a positive effect on the prevention of pulmonary arterial muscularization in PAH models. Silibinin is a traditional medicine that has an antagonistic effect on CXCR4. We investigated the effect of silibinin using rat models of PAH.

Methods

PAH was induced by a single subcutaneous injection of monocrotaline. The rats were maintained in a chronic hypoxic condition (10% O₂) with or without silibinin. To evaluate the efficacy of silibinin on PAH, right ventricular systolic pressure (RVSP), Fulton index (weight ratio of right ventricle to the left ventricle and septum), percent medial wall thickness (% MT), and vascular occlusion score (VOS) were measured and calculated. Immunohistochemical analysis was performed targeting CXCR4 and c-Kit. Reverse transcription-quantitative polymerase chain reaction was performed for the stem cell markers CXCR4, stromal cell derived factor-1 (SDF-1), c-Kit, and stem cell factor (SCF), and the inflammatory markers monocyte chemoattractant protein 1 (MCP1), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNFα). Statistical analyses were performed using t-test and one-way analysis of variance with Bonferroni’s post hoc test.

Results

Silibinin treatment for 1 week reduced RVSP and Fulton index. Treatment for 2 weeks reduced RVSP, Fulton index, % MT, and VOS, as well as downregulating the expression of CXCR4, SDF-1, and TNFα in pulmonary arteries. In contrast, treatment for 3 weeks failed to ameliorate PAH. The time-course study demonstrated that RVSP, Fulton index, % MT, and VOS gradually increased over time, with a decrease in the expression of CXCR4 and TNFα occurring after 2 weeks of PAH development. After 3 weeks, SDF-1, c-Kit, and SCF began to decrease and, after 5 weeks, MCP1 and IL-6 gradually accumulated.

Conclusions

The CXCR4 inhibitor silibinin can ameliorate PAH, possibly through the suppression of the CXCR4/SDF-1 axis, until the point where PAH becomes a severe and irreversible condition. Silibinin results in reduced pulmonary arterial pressure and delays pulmonary arteriolar occlusion and pulmonary vascular remodeling.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1041-y) contains supplementary material, which is available to authorized users.