Cellular Crosstalk in the Vascular Wall Microenvironment: The Role of Exosomes in Vascular Calcification

Alleviating vascular calcification with Bushen Huoxue formula in rats with chronic kidney disease by inhibiting the PTEN/PI3K/AKT signaling pathway through exosomal microRNA-32

BACKGROUND

Vascular calcification (VC) significantly raises cardiovascular mortality in chronic kidney disease (CKD) patients. VC is characterized by the phenotypic transformation of vascular smooth muscle cells (VSMCs) to osteoblast-like cells, mediated by exosomes derived from calcified VSMCs and the exosomal microRNAs (miRNA) which may trigger some signals to recipient VSMCs. Bushen Huoxue (BSHX) formula has demonstrated its clinical efficacy in CKD and its protective role in CKD-VC rats has also been observed. However, little is known about its underlying mechanism.

METHODS

To establish a VC model, aortic VSMCs from rats were induced to osteogenic differentiation by high-level phosphate (HP) in vitro. The expression of exosome and calcification makers were analyzed by western blot, including CD9, CD63, α-SMA, BMP-2, and Runx2, respectively. Differential expression of exosomal miRNAs in normal and HP-induced VSMCs were identified by using whole miRNA microarray technology. GO and KEGG analyses were performed to determine the significant enrichment of functions and signaling pathways in the target genes. In vivo, the CKD-VC rat model was established by administering adenine gavage combined with a high phosphorus diet. The rats were divided into normal control, model, low-dose BSHX, medium-dose BSHX, high-dose BSHX groups, and sevelamer groups. The blood biochemical parameters were measured. Renal histopathology and aortic calcification were observed. Western blot detected the levels of the calcification markers. Quantitative real-time PCR (qPCR) assay detected exosomal microRNA-32 (miR-32) mRNA expression in the aorta, the most differentially expressed exosomal miRNA previously identified. Phosphatase and tensin homolog located on chromosome ten (PTEN)/phosphatidylinositol-3 kinase (PI3K)/protein kinase B (AKT) signaling pathway components were also tested by western blot.

RESULTS

Exosomal miRNA-32 and PI3K/AKT signaling pathways were highly differentially expressed between normal and HP-induced VSMCs. In vivo, BSHX improved blood biochemical parameters, renal histopathology, and aortic calcification in CKD-VC rats. BSHX increased the expression level of α-SMA and decreased the level of BMP-2 and Runx2. BSHX also lowered the expression level of exosomal miR-32 mRNA, enhanced PTEN expression, therefore, reduced p-PI3K and p-AKT levels in the aorta.

CONCLUSION

BSHX alleviated VC in CKD rats by downregulating exosomal miR-32 expression in the aorta, thereby promoting PTEN expression and inhibiting the PI3K/AKT signaling pathway.

Functions and application of circRNAs in vascular aging and aging-related vascular diseases

Circular RNAs (circRNAs), constituting a novel class of endogenous non-coding RNAs generated through the reverse splicing of mRNA precursors, possess the capacity to regulate gene transcription and translation. Recently, the pivotal role of circRNAs in controlling vascular aging, as well as the pathogenesis and progression of aging-related vascular diseases, has garnered substantial attention. Vascular aging plays a crucial role in the increased morbidity and mortality of the elderly. Endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are crucial components of the intima and media layers of the vascular wall, respectively, and are closely involved in the mechanisms underlying vascular aging and aging-related vascular diseases. The review aims to provide a comprehensive exploration of the connection between circRNAs and vascular aging, as well as aging-related vascular diseases. Besides, circRNAs, as potential diagnostic markers or therapeutic targets for vascular aging and aging-related vascular diseases, will be discussed thoroughly, along with the challenges and limitations of their clinical application. Investigating the role and molecular mechanisms of circRNAs in vascular aging and aging-related vascular diseases will provide a novel insight into early diagnosis and therapy, and even effective prognosis assessment of these conditions.

Exosomal ALKBH5 Alleviates Vascular Calcification by Suppressing Cell Apoptosis via m6A-Modified GSDME

This study aimed to explore the function and regulatory mechanism of ALKBH5 in the progression of coronary artery calcification. Human aortic vascular smooth muscle cells (HA-VSMCs) were treated with inorganic phosphate (Pi) and exosomes derived from bone marrow mesenchymal stem cell (BMSC) carrying ALKBH5, a GSDME overexpression vector or si-GSDME. The morphology and size of the exosomes were assessed using nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM). Calcium deposition was measured using Alizarin red staining and cell pyroptosis was evaluated using Hoechst 33342/PI staining. The association between ALKBH5 and m6A modifications was confirmed by methylated-RNA immunoprecipitation assay (MeRIP) and dot blot assays. The expression levels of ALKBH5 and GSDME were quantified by quantitative real-time polymerase chain reaction (qRT-PCR), and protein levels were quantified by western blot. BMSCs-derived exosomes reduced calcium deposition and cell pyroptosis in Pi-treated HA-VSMCs. Exosomes containing ALKBH5 overexpression inhibited high mobility group box 1 (HMGB1) and cell apoptosis, thereby promoting vascular calcification, whereas ALKBH5 knockdown in exosomes exerted the opposite effect on calcification development. Additionally, ALKBH5 was found to regulate the m6A modification of GSDME. Overexpression of GSDME reversed the effects of ALKBH5 in exosomes on HMGB1 expression and cell apoptosis. Exosomal ALKBH5 mitigated HMGB1 expression and cell pyroptosis by modulating the m6A modification of GSDME, thus influencing the progression of coronary artery calcification.

Mechanism of cold exposure delaying wound healing in mice

Cold temperatures have been shown to slow skin wound healing. However, the specific mechanisms underlying cold-induced impairment of wound healing remain unclear. Here, we demonstrate that small extracellular vesicles derived from cold-exposed mouse plasma (CT-sEVs) decelerate re-epithelialization, increase scar width, and weaken angiogenesis. CT-sEVs are enriched with miRNAs involved in the regulation of wound healing-related biological processes. Functional assays revealed that miR-423-3p, enriched in CT-sEVs, acts as a critical mediator in cold-induced impairment of angiogenic responses and poor wound healing by inhibiting phosphatase and poly(A) binding protein cytoplasmic 1 (PABPC1). These findings indicate that cold delays wound healing via miR-423-3p in plasma-derived sEVs through the inhibition of the ERK or AKT phosphorylation pathways. Our results enhance understanding of the molecular mechanisms by which cold exposure delays soft tissue wound healing.

Endothelial cells derived extracellular vesicles promote diabetic arterial calcification via circ_0008362/miR-1251-5p/Runx2 axial

INTRODUCTION

Arterial calcification, an independent predictor of cardiovascular events, increases morbidity and mortality in patients with diabetes mellitus (DM), but its mechanisms remain unclear. Extracellular vesicles (EVs) play an important role in intercellular communication. The study investigates the role and potential mechanisms of EVs derived from endothelial cells (ECs) in regulating vascular smooth muscle cell (VSMC) calcification under high glucose (HG) condition, with a goal of developing effective prevention and treatment strategies for diabetic arterial calcification.

RESULTS

The results showed that EVs derived from HG induced ECs (ECHG-EVs) exhibited a bilayer structure morphology with a mean diameter of 74.08 ± 31.78 nm, expressing EVs markers including CD9, CD63 and TSG101, but not express calnexin. ECHG-EVs was internalized by VSMCs and induced VSMC calcification by increasing Runx2 expression and mineralized nodule formation. The circ_0008362 was enriched in ECHG-EVs, and it can be transmitted to VSMCs to promote VSMC calcification both in vitro and in vivo. Mechanistically, miR-1251-5p might be one of the targets of circ_0008362 and they were co-localization in the cytoplasm of VSMCs. Runx2 was identified as the downstream target of miR-1251-5p, and circ_0008362 acted as a sponge, enhancing Runx2 expression and then promoted VSMC calcification. Besides, circ_0008362 could directly interact with Runx2 to aggravate VSMC calcification. Notably, DiR-labelled ECHG-EVs was detected in the vessels of mice. Meanwhile, the level of circ_0008362 and Runx2 were increased significantly, while the expression of miR-1251-5p was decreased significantly in calcified artery tissues of mice. However, inhibiting the release of EVs by GW4869 attenuated arterial calcification in diabetic mice. Finally, the level of circulation of plasma EVs circ_0008362 was significantly higher in patients with DM compared with normal controls. Elevated levels of plasma EVs circ_0008362 were associated with more severe coronary and aorta artery calcification in patients with DM.

CONCLUSIONS

Our findings suggested that circ_0008362 was enriched in EVs derived from ECs and promoted VSMC calcification under HG conditions, both by sponging miR-1251-5p to upregulate Runx2 expression and through direct interaction with Runx2. Furthermore, elevated levels of plasma EVs circ_0008362 were associated with more severe coronary and aorta artery calcification in patients with DM. These results may serve as a potential prevention and therapeutic target for diabetic arterial calcification.

Current Understanding of Cardiovascular Calcification in Patients with Chronic Kidney Disease

The burden of chronic kidney disease (CKD) is increasing, posing a serious threat to human health. Cardiovascular calcification (CVC) is one of the most common manifestations of CKD, which significantly influences the morbidity and mortality of patients. The manifestation of CVC is an unusual accumulation of mineral substances containing calcium and phosphate. The main component is hydroxyapatite. Many cells are involved in this process, such as smooth muscle cells (SMCs) and endothelial cells. CVC is an osteogenic process initiated by complex mechanisms such as metabolic disorders of calcium and phosphorus minerals, inflammation, extracellular vesicles, autophagy, and micro-RNAs with a variety of signaling pathways like Notch, STAT, and JAK. Although drug therapy and dialysis technology continue to advance, the survival time and quality of life of CVC patients still face challenges. Therefore, early diagnosis and prevention of CKD-related CVC, reducing its mortality rate, and improving patients' quality of life have become urgent issues in the field of public health. In this review, we try to summarize the state-of-the-art understanding of the progression of CVC and hope that it will help in the prevention and treatment of CVC in CKD.

Endothelial Dysfunction in Youth-Onset Type 2 Diabetes: A Clinical Translational Study

BACKGROUND

Youth-onset type 2 diabetes (Y-T2D) is associated with increased risk for coronary atherosclerotic disease, but the timing of the earliest pathological features and evidence of cardiac endothelial dysfunction have not been evaluated in this population. Endothelial function magnetic resonance imaging may detect early and direct endothelial dysfunction in the absence of classical risk factors (severe hyperglycemia, hypertension, and hyperlipidemia). Using endothelial function magnetic resonance imaging, we evaluated peripheral and coronary artery structure and endothelial function in young adults with Y-T2D diagnosed ≤5 years compared with age-matched healthy peers. We isolated and characterized plasma-derived small extracellular vesicles and evaluated their effects on inflammatory and signaling biomarkers in healthy human coronary artery endothelial cells to validate the imaging findings.

METHODS

Right coronary wall thickness, coronary artery flow-mediated dilation, and brachial artery flow-mediated dilation were measured at baseline and during isometric handgrip exercise using a 3.0T magnetic resonance imaging. Human coronary artery endothelial cells were treated with Y-T2D plasma-derived small extracellular vesicles. Protein expression was measured by Western blot analysis, oxidative stress was measured using the redox-sensitive probe dihydroethidium, and nitric oxide levels were measured by 4-amino-5-methylamino-2',7'-difluororescein diacetate.

RESULTS

Y-T2D (n=20) had higher hemoglobin A1c and high-sensitivity C-reactive protein, but similar total and LDL (low-density lipoprotein)-cholesterol compared with healthy peers (n=16). Y-T2D had greater coronary wall thickness (1.33±0.13 versus 1.22±0.13 mm; P=0.04) and impaired endothelial function: lower coronary artery flow-mediated dilation (-3.1±15.5 versus 15.9±17.3%; P<0.01) and brachial artery flow-mediated dilation (6.7±14.7 versus 26.4±15.2%; P=0.001). Y-T2D plasma-derived small extracellular vesicles reduced phosphorylated endothelial nitric oxide synthase expression and nitric oxide levels, increased reactive oxygen species production, and elevated ICAM (intercellular adhesion molecule)-mediated inflammatory pathways in human coronary artery endothelial cells.

CONCLUSIONS

Coronary and brachial endothelial dysfunction was evident in Y-T2D who were within 5 years of diagnosis and did not have severe hyperglycemia or dyslipidemia. Plasma-derived small extracellular vesicles induced markers of endothelial dysfunction, which corroborated accelerated subclinical coronary atherosclerosis as an early feature in Y-T2D.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02830308 and NCT01399385.

Vascular wall microenvironment: exosomes secreted by adventitial fibroblasts induced vascular calcification

Vascular calcification often occurs in patients with chronic renal failure (CRF), which significantly increases the incidence of cardiovascular events in CRF patients. Our previous studies identified the crosstalk between the endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), and the paracrine effect of VSMCs, which regulate the calcification of VSMCs. Herein, we aim to investigate the effects of exosomes secreted by high phosphorus (HPi) -induced adventitial fibroblasts (AFs) on the calcification of VSMCs and the underlying mechanism, which will further elucidate the important role of AFs in high phosphorus vascular wall microenvironment. The conditioned medium of HPi-induced AFs promotes the calcification of VSMCs, which is partially abrogated by GW4869, a blocker of exosomes biogenesis or release. Exosomes secreted by high phosphorus-induced AFs (AFsHPi-Exos) show similar effects on VSMCs. miR-21-5p is enriched in AFsHPi-Exos, and miR-21-5p enhances osteoblast-like differentiation of VSMCs by downregulating cysteine-rich motor neuron 1 (Crim1) expression. AFsHPi-Exos and exosomes secreted by AFs with overexpression of miR-21-5p (AFsmiR21M-Exos) significantly accelerate vascular calcification in CRF mice. In general, AFsHPi-Exos promote the calcification of VSMCs and vascular calcification by delivering miR-21-5p to VSMCs and subsequently inhibiting the expression of Crim1. Combined with our previous studies, the present experiment supports the theory of vascular wall microenvironment.

Cold exposure protects against medial arterial calcification development via autophagy

Medial arterial calcification (MAC), a systemic vascular disease different from atherosclerosis, is associated with an increased incidence of cardiovascular events. Several studies have demonstrated that ambient temperature is one of the most important factors affecting cardiovascular events. However, there has been limited research on the effect of different ambient temperatures on MAC. In the present study, we showed that cold temperature exposure (CT) in mice slowed down the formation of vitamin D (VD)-induced vascular calcification compared with room temperature exposure (RT). To investigate the mechanism involved, we isolated plasma-derived exosomes from mice subjected to CT or RT for 30 days (CT-Exo or RT-Exo, respectively). Compared with RT-Exo, CT-Exo remarkably alleviated the calcification/senescence formation of vascular smooth muscle cells (VSMCs) and promoted autophagy by activating the phosphorylation of AMP-activated protein kinase (p-AMPK) and inhibiting phosphorylation of mammalian target of rapamycin (p-mTOR). At the same time, CT-Exo promoted autophagy in β-glycerophosphate (β-GP)-induced VSMCs. The number of autophagosomes and the expression of autophagy-related proteins ATG5 and LC3B increased, while the expression of p62 decreased. Based on a microRNA chip microarray assay and real-time polymerase chain reaction, miR-320a-3p was highly enriched in CT-Exo as well as thoracic aortic vessels in CT mice. miR-320a-3p downregulation in CT-Exo using AntagomiR-320a-3p inhibited autophagy and blunted its anti-calcification protective effect on VSMCs. Moreover, we identified that programmed cell death 4 (PDCD4) is a target of miR-320a-3p, and silencing PDCD4 increased autophagy and decreased calcification in VSMCs. Treatment with CT-Exo alleviated the formation of MAC in VD-treated mice, while these effects were partially reversed by GW4869. Furthermore, the anti-arterial calcification protective effects of CT-Exo were largely abolished by AntagomiR-320a-3p in VD-induced mice. In summary, we have highlighted that prolonged cold may be a good way to reduce the incidence of MAC. Specifically, miR-320a-3p from CT-Exo could protect against the initiation and progression of MAC via the AMPK/mTOR autophagy pathway.

Differentially Expressed Genes and Molecular Susceptibility to Human Age-Related Diseases

Mainstream transcriptome profiling of susceptibility versus resistance to age-related diseases (ARDs) is focused on differentially expressed genes (DEGs) specific to gender, age, and pathogeneses. This approach fits in well with predictive, preventive, personalized, participatory medicine and helps understand how, why, when, and what ARDs one can develop depending on their genetic background. Within this mainstream paradigm, we wanted to find out whether the known ARD-linked DEGs available in PubMed can reveal a molecular marker that will serve the purpose in anyone's any tissue at any time. We sequenced the periaqueductal gray (PAG) transcriptome of tame versus aggressive rats, identified rat-behavior-related DEGs, and compared them with their known homologous animal ARD-linked DEGs. This analysis yielded statistically significant correlations between behavior-related and ARD-susceptibility-related fold changes (log₂ values) in the expression of these DEG homologs. We found principal components, PC1 and PC2, corresponding to the half-sum and the half-difference of these log₂ values, respectively. With the DEGs linked to ARD susceptibility and ARD resistance in humans used as controls, we verified these principal components. This yielded only one statistically significant common molecular marker for ARDs: an excess of Fcγ receptor IIb suppressing immune cell hyperactivation.

Vascular smooth muscle cells in intimal hyperplasia, an update

Arterial occlusive disease is the leading cause of death in Western countries. Core contemporary therapies for this disease include angioplasties, stents, endarterectomies and bypass surgery. However, these treatments suffer from high failure rates due to re-occlusive vascular wall adaptations and restenosis. Restenosis following vascular surgery is largely due to intimal hyperplasia. Intimal hyperplasia develops in response to vessel injury, leading to inflammation, vascular smooth muscle cells dedifferentiation, migration, proliferation and secretion of extra-cellular matrix into the vessel's innermost layer or intima. In this review, we describe the current state of knowledge on the origin and mechanisms underlying the dysregulated proliferation of vascular smooth muscle cells in intimal hyperplasia, and we present the new avenues of research targeting VSMC phenotype and proliferation.

Vascular homeostasis in atherosclerosis: A holistic overview

Atherosclerosis refers to the deposition of lipids and the co-existence of inflammation and impaired inflammation resolution in pan-vasculature, which causes lumen narrowing, hardening, plaque formation, and the manifestation of acute cardiovascular events. Emerging evidence has suggested that vascular circulation can be viewed as a complex homeostatic system analogous to a mini-ecosystem which consists of the vascular microenvironment (niche) and the crosstalk among phenotypically and functionally diverse vascular cell types. Here, we elucidate how cell components in the vascular wall affect vascular homeostasis, structure, function, and atherosclerosis in a holistic perspective. Finally, we discuss the potential role of vascular-stabilizing strategies including pharmacotherapies, natural substances and lifestyle modifications, in preventing cardiovascular diseases by preserving vascular integrity and homeostasis.