Simultaneous Increases in Proliferation and Apoptosis of Vascular Smooth Muscle Cells Accelerate Diabetic Mouse Venous Atherosclerosis

Gene expression modulation in human aortic smooth muscle cells under induced physiological mechanical stretch

In this study, we investigated gene expression in vitro of human primary Aortic smooth muscle cells (AoSMCs) in response to 9% physiological dynamic stretch over a 4 to 72-h timeframe using RT-qPCR. AoSMC were derived from primary culture and were exposed to continuous cycles of stretch and relaxation at 1 Hz by a computer-controlled Flex Jr.™ Tension System. Unstretched control AoSMCs were simultaneously cultured in the same dishes. Our results revealed a rapid and significant upregulation of specific genes (COL1A1, FBN1, LAMA5, TGFBR1 and TGFBR2) within the initial 4 h for AoSMCs subjected to dynamic stretching, whilst control cells did not respond within the same 4 h. The upregulated genes were the ones associated with extracellular matrix (ECM) fibrillogenesis and regulation of traction forces. Interestingly, stretched cells maintained stable gene expression between 4 and 72 h, whilst control cells exhibited variations over time in the absence of mechanical cues. These findings shed light on the essential role played by pulsatile stretches in the regulation of gene expressions by AoSMCs and the intricate processes governing their mechanobiological function, paving the way for further investigations in cardiovascular health.

A Comprehensive Retrospective Study on the Mechanisms of Cyclic Mechanical Stretch-Induced Vascular Smooth Muscle Cell Death Underlying Aortic Dissection and Potential Therapeutics for Preventing Acute Aortic Aneurysm and Associated Ruptures

Acute aortic dissection (AAD) and associated ruptures are the leading causes of death in cardiovascular diseases (CVDs). Hypertension is a prime risk factor for AAD. However, the molecular mechanisms underlying AAD remain poorly understood. We previously reported that cyclic mechanical stretch (CMS) leads to the death of rat aortic smooth muscle cells (RASMCs). This review focuses on the mechanisms of CMS-induced vascular smooth muscle cell (VSMC) death. Moreover, we have also discussed the potential therapeutics for preventing AAD and aneurysm ruptures.

Release of Pro-Inflammatory/Angiogenic Factors by Retinal Microvascular Cells Is Mediated by Extracellular Vesicles Derived from M1-Activated Microglia

The interactions between the neuronal and vascular sides of the retina during diabetic retinopathy (DR) have gained increasing attention. Microglia is responsible for the immune response to inflammation inside the retina, which could be mediated by paracrine signals carried by extracellular vesicles (EVs). We aimed to characterize EVs released from immortalized human microglial cells in inflammation and investigate their effects on the retinal microvasculature and the anti-inflammatory potential of thiamine in this context. M1 pro-inflammatory polarization in microglia was induced through a cytokine cocktail. EVs were isolated from the supernatants, characterized, and used to stimulate human retinal endothelial cells (HRECs) and pericytes (HRPs). Microvascular cell functions and their release of pro-inflammatory/angiogenic factors were assessed. M1-derived EVs showed increased content of miR-21, miR-155, CCL2, MMP2, and MMP9, and enhanced apoptosis, proliferation, migration, and ROS production in HRPs and HRECs. IL-1β, IL-6, MMP9, CCL2, and VEGF release increased in HRPs exposed to M1-derived EVs, while HRECs showed augmented IL-6, Ang2, VEGF, and PDFG-B. Addition of thiamine to M1-microglial cultures reverted most of these effects. In conclusion, M1-derived EVs stimulate functional changes and secretion of pro-inflammatory/angiogenic molecules in microvascular cells, exacerbating inflammatory damage and retinopathy features. Thiamine added to microglia exerts anti-inflammatory effects.

Selenium Deficiency Induces Apoptosis and Necroptosis Through ROS/MAPK Signal in Human Uterine Smooth Muscle Cells

Selenium (Se) is one of the essential trace elements; its deficiency induces ROS production and cell death in cardiomyocytes, skeletal muscle cells, and vascular smooth muscle cells, but it is still not clear the impact of Se deficiency on human uterine smooth muscle cells (HUSMCs). To investigate the effect of low Se on the mRNA expression of selenoproteins, the mRNA and protein expression of apoptosis and necroptosis of HUSMCs and their mechanism, Se deficient HUSMCs mode was established through culturing with 1% FBS containing 0 ng/mL, 0.7 ng/mL, and 7 ng/mL Se, and 10% FBS was as the control group. Then, the apoptosis and necroptosis rates, intracellular ROS content and the expression levels of selenoproteins, apoptosis, necroptosis, MAPK pathway-related genes were examined under different Se concentrations. The results showed that Se deficiency led to the augment of cell apoptosis and necroptosis in HUSMCs (p < 0.05), downregulated (p < 0.05) 19 selenoproteins (GPX1, GPX2, GPX3, GPX4, GPX6, Dio3, Txnrd2, Txnrd3, SEPHS2, SEL15, SELH, SELI, SELM, SELN, SELO, SELS, SELT, SELV, and SELW), while Dio2, SELK, Txnrd1, and MSRB1 were not affected by Se deficiency (p ≥ 0.05). In addition, Se deficiency led to increased intracellular ROS content, p-P38 and p-JNK gene expression levels (p < 0.05), the mitochondrial apoptosis pathway Bax, Casp9 and Cle-Casp3 protein expression levels (p < 0.05), and decreased Bcl2 protein expression level (p < 0.05), simultaneously, increased necroptosis marker genes RIP1, RIP3, and MLKL protein expression levels (p < 0.05) with a dose-dependent pattern. The above results indicate that Se deficiency induces HUSMCs apoptosis and necroptosis through the ROS/MAPK pathway and is closely related to selenoproteins.

Characterization of an Immortalized Human Microglial Cell Line as a Tool for the Study of Diabetic Retinopathy

The complexity of the retinal structure reflects on the difficulty to describe its composite cell interactions. Microglia is responsible for the immune reaction to inflammatory stimuli during diabetic retinopathy (DR), but most studies still use rodent cells. We characterized a commercially available immortalized human microglial line and tested its susceptibility to inflammation, to study the interactions between the neuro-vascular retinal portions in species-specific models. After checking the expression of microglial markers, we tried lipopolysaccharide (LPS) stimulation and several pro-inflammatory cocktails to select the best combination able to induce a significant M1 (inflammatory) response. We measured M1 induction through the expression of pro- and anti-inflammatory molecules and performed morphologic and functional assays. Marker expression confirmed the human microglial derivation of these cells. Differently from rodents, LPS did not induce a M1 profile. The best pro-inflammatory stimulus was an interleukin-1β + tumor necrosis factor-α + interferon-γ cocktail, which induced morphology changes and increased proliferation, apoptosis, migration, reactive oxygen species, and the expression of inflammatory cytokines and miRNAs. In conclusion, this microglial line proved potentially useful to investigate the cascade of events leading to DR. In perspective, co-culture models involving microvascular cells will help in the understanding of multifaceted interactions of the neurovascular unit.

Evening Primrose Extracts Inhibit PDGF-BB-Induced Vascular Smooth Muscle Cell Proliferation and Migration by Regulating Cell-Cycle-Related Proteins

The proliferation and migration of vascular smooth muscle cells (VSMCs) are important factors in the occurrence of cardiovascular diseases, such as blood flow abnormalities, stroke and atherosclerosis. Evening primrose, known as Oenothera biennis, is a plant native to Korea that exerts physiological activities, such as antioxidant effects, the inhibition of lipid accumulation and the prevention of muscle atrophy. However, the function of evening primrose stem (EVP) in the regulation of VSMC proliferation and migration and the underlying mechanisms have not been identified. In this study, the effect of EVP on the platelet-derived growth factor (PDGF)-induced proliferation and migration of VSMCs was investigated. The results show that PDGF-BB-induced proliferation of VSMCs was inhibited by EVP at concentrations of 25, 50 or 100 μg/mL in a concentration-dependent manner, and a migration assay showed that EVP inhibited cell migration. Cell cycle analysis was performed to confirm the mechanism by which cell proliferation and migration was inhibited. The results indicate that proteins involved in the cell cycle, such as cyclin, CDK and phosphorylated Rb, were downregulated by EVP at concentrations of 100 μg/mL, thereby increasing the proportion of cells in the G0/G1 phase and inhibiting cell cycle progression. In the PDGF receptor (PDGFR) signaling pathway, phosphorylation of the PDGFR was inhibited by EVP at concentrations of 100 μg/mL, and PLCγ phosphorylation was also decreased. The PDGF-BB-induced effect of EVP on the proliferation of VSMCs involved the inhibition of Akt phosphorylation and the reduction in the phosphorylation of MAPK proteins such as ERK, P38 and JNK. In conclusion, the results demonstrate that EVP inhibited PDGF-BB-induced VSMC proliferation and migration by regulating cell-cycle-related proteins.

Circular RNAs in atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory lesion of the arterial vessel wall caused by a variety of complex factors. Furthermore, it is a major cause of cardiovascular disease and a leading cause of death. Circular RNAs (circRNAs) are a new family of endogenous non-coding RNAs with unique covalently closed loops that have sparked interest due to their unique characteristics and potential diagnostic and therapeutic applications in various diseases. A growing number of studies have shown that circRNAs can be used as biomarkers for the diagnosis and treatment of AS. In this article, we review the biogenesis, classification as well as functions of circRNA and summarize the research on circRNA as a diagnostic biomarker for AS. Finally, we describe the regulatory capacity of circRNA in AS pathogenesis through its pathogenesis and demonstrate the potential therapeutic role of circRNA for AS.

Immuno-regenerative biomaterials for in situ cardiovascular tissue engineering - Do patient characteristics warrant precision engineering?

In situ tissue engineering using bioresorbable material implants - or scaffolds - that harness the patient's immune response while guiding neotissue formation at the site of implantation is emerging as a novel therapy to regenerate human tissues. For the cardiovascular system, the use of such implants, like blood vessels and heart valves, is gradually entering the stage of clinical translation. This opens up the question if and to what extent patient characteristics influence tissue outcomes, necessitating the precision engineering of scaffolds to guide patient-specific neo-tissue formation. Because of the current scarcity of human in vivo data, herein we review and evaluate in vitro and preclinical investigations to predict the potential role of patient-specific parameters like sex, age, ethnicity, hemodynamics, and a multifactorial disease profile, with special emphasis on their contribution to the inflammation-driven processes of in situ tissue engineering. We conclude that patient-specific conditions have a strong impact on key aspects of in situ cardiovascular tissue engineering, including inflammation, hemodynamic conditions, scaffold resorption, and tissue remodeling capacity, suggesting that a tailored approach may be required to engineer immuno-regenerative biomaterials for safe and predictive clinical applicability.

Phenotypic and Functional Transformation in Smooth Muscle Cells Derived from a Superficial Thrombophlebitis-affected Vein Wall

BACKGROUND

Superficial thrombophlebitis (ST) is a frequent pathology, but its exact incidence remains to be determined. This study tested the hypothesis whether relationships exist among smooth muscle cells (SMCs) derived from ST, varicose great saphenous veins (VGSVs), and normal great saphenous veins (GSVs).

METHODS

Forty-one samples of ST, VGSVs, and GSVs were collected. SMCs were isolated and cultured. Proliferation, migration, adhesion, and senescence in SMCs from the three vein walls were compared by various methods. Bax, Bcl-2, caspase-3, matrix metalloproteinase-2 (MMP-2), MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), and TIMP-2 messenger RNA (mRNA) and protein expressions were detected by fluorescence quantitative PCR and Western blot.

RESULTS

An obvious decrease in cytoskeletal filaments was observed in thrombophlebitic vascular smooth muscle cells (TVSMCs). The quantity of proliferation, migration, adhesion, and senescence in TVSMCs was significantly higher than in varicose vascular smooth muscle cells and normal vascular smooth muscle cells (NVSMCs) (all P < 0.05). Bax and caspase-3 mRNA and protein expression were decreased, while Bcl-2 mRNA and protein expression were increased in the TVSMCs compared with the varicose vascular smooth muscle cells and the NVSMCs (all P < 0.05). MMP-2, MMP-9, TIMP-1, and TIMP-2 mRNA and protein expression were significantly increased in the TVSMCs compared with the VVGSVs and the NVSMCs (all P < 0.05).

CONCLUSION

SMCs derived from ST are more dedifferentiated and demonstrate increased cell proliferation, migration, adhesion, and senescence, as well as obviously decreased cytoskeletal filaments. These results suggest that the phenotypic and functional differences could be related to the presence of atrophic and hypertrophic vein segments during the disease course among SMCs derived from ST, VGSVs, and GSVs.

The Phenotypic Responses of Vascular Smooth Muscle Cells Exposed to Mechanical Cues

During the development of atherosclerosis and other vascular diseases, vascular smooth muscle cells (SMCs) located in the intima and media of blood vessels shift from a contractile state towards other phenotypes that differ substantially from differentiated SMCs. In addition, these cells acquire new functions, such as the production of alternative extracellular matrix (ECM) proteins and signal molecules. A similar shift in cell phenotype is observed when SMCs are removed from their native environment and placed in a culture, presumably due to the absence of the physiological signals that maintain and regulate the SMC phenotype in the vasculature. The far majority of studies describing SMC functions have been performed under standard culture conditions in which cells adhere to a rigid and static plastic plate. While these studies have contributed to discovering key molecular pathways regulating SMCs, they have a significant limitation: the ECM microenvironment and the mechanical forces transmitted through the matrix to SMCs are generally not considered. Here, we review and discuss the recent literature on how the mechanical forces and derived biochemical signals have been shown to modulate the vascular SMC phenotype and provide new perspectives about their importance.

Exploring the regulatory roles of circular RNAs in the pathogenesis of atherosclerosis

Circular RNAs (circRNAs) are a class of noncoding RNAs with a covalently closed loop structure. Recent evidence has shown that circRNAs can regulate gene transcription, alternative splicing, microRNA (miRNA) "molecular sponges", RNA-binding proteins and protein translation. Atherosclerosis is one of the leading causes of death worldwide, and more studies have indicated that circRNAs are related to atherosclerosis pathogenesis, including vascular endothelial cells, vascular smooth muscle cells, inflammation and lipid metabolism. In this review, we systematically summarize the biogenesis, characteristics and functions of circRNAs with a focus on their roles in the pathogenesis of atherosclerosis.

Uric acid can enhance MAPK pathway-mediated proliferation in rat primary vascular smooth muscle cells via controlling of mitochondria and caspase-dependent cell death

Hyperuricemia may be a risk factor for cardiovascular diseases such as hypertension and atherosclerosis, but the mechanisms underlying uric acid-induced pathological conditions remain unknown. In this study, we investigated the effect of short time and long-term administration of increasing uric acid concentrations on cell viability, proliferative and apoptotic pathways in vascular smooth muscle cells (VSMCs). Cell viability/proliferation was determined with WST-1 assay. Expression levels of mitogen-activated protein kinases (MAPKs) (phosphorylated (p)-p38 and p-p44/42 MAPK), extrinsic (caspase 3, caspase 8), and intrinsic (B-cell lymphoma-extra-large (Bcl-xL)) apoptotic pathway proteins were measured by Western blotting. In order to assess the proliferative effects of uric acid incubations on VSMCs, we monitored the proliferative/apoptosis signaling pathways for up to 24 h. Our results indicated that uric acid increases cell viability at time and dose-dependently in VSMCs. Immunoblotting results showed that uric acid treatment elevated the expression level of p-p38 MAPK but did markedly reduce the protein levels of p-p44/42, compared with all the uric acid doses-treated VSMCs, especially at 1 h. Uric acid stimulation increased caspase-3 protein levels and decreased Bcl-xL, but did not alter caspase-8 protein expression at the same dose and time. Furthermore, low uric acid incubations (0-7.5 mg/dL) did not affect any signaling pathways for long time points (6-24 h). In conclusion, our study demonstrates for the first time that VSMCs induced with uric acid can affect cell viability, proliferative, and apoptosis pathways at the widest time and dose range. These findings provide a better understanding of the uric acid effects related to vascular impairments.

Circular RNA PPP1CC promotes Porphyromonas gingivalis-lipopolysaccharide-induced pyroptosis of vascular smooth muscle cells by activating the HMGB1/TLR9/AIM2 pathway

Objective

Porphyromonas gingivalis (Pg) plays a critical role in the occurrence and development of atherosclerosis. Lipopolysaccharide from Pg (Pg-LPS) could lead to pyroptosis of vascular smooth muscle cells (VSMCs) and induce instability of atherosclerotic plaque. Therefore, pyroptosis of VSMCs could promote the process of atherosclerosis. However, the exact mechanism of Pg-LPS-induced pyroptosis of VSMCs is unclear.

Methods

We determined pyroptosis and expression of interleukin (IL)-1β and IL-18 in VSMCs using 4′,6-diamidino-2-phenylindole staining and ELISA after stimulation by Pg-LPS. We established a knockdown plasmid containing the circular (circ)RNA PPP1CC and transfected it into VSMCs. Luciferase assays were performed to reveal the association between microRNAs miR-103a-3p and miR-107 and circRNA PPP1CC.

Results

Stimulation of Pg-LPS led to pyroptosis of VSMCs. Knockdown of circRNA PPP1CC relieved the Pg-LPS-induced pyroptosis of VSMCs and suppressed the expression of HMGB1, TLR9, AIM2, and cleaved caspase-1. Luciferase assays showed that PPP1CC directly targeted and competitively adsorbed miR-103a-3p and miR-107, weakening the inhibitory effect of these microRNAs on the expression of HMGB1.

Conclusion

Knockdown of circRNA PPP1CC relieved Pg-LPS-induced pyroptosis of VSMCs. Pyroptosis of VSMCs appears to promote atherosclerosis and may represent a novel therapeutic target for its treatment.

miR-140-5p regulates vascular smooth muscle cell viability, migration and apoptosis by targeting ROBO4 gene expression in atherosclerosis

MicroRNAs (miRs) are essential regulators of atherosclerosis (AS) development; however, the pathogenic roles of miR-140-5p during AS development are not completely understood. The present study investigated the effects of miR‑140-5p on human vascular smooth muscle cells (VSMCs) and its target gene. miR-140-5p and roundabout guidance receptor 4 (ROBO4) mRNA expression levels were determined by performing reverse transcription-quantitative PCR. ROBO4 protein expression levels were analyzed via western blotting. Cell viability, migration, invasion and apoptosis were evaluated by conducting Cell Counting Kit-8, Transwell and flow cytometry assays, respectively. The binding of miR-140-5p to ROBO4 mRNA was verified using the dual-luciferase reporter assay. miR-140-5p was highly expressed in the plaque-containing artery tissues of patients with AS compared with healthy control tissues. Oxidized-low density lipoprotein (ox-LDL) treatment increased miR-140-5p expression and decreased ROBO4 expression in human VSMCs, which promoted VSMC viability, migration and invasion, but suppressed apoptosis compared with the control group. The effects of ox-LDL treatment on VSMCs were attenuated by miR-140-5p inhibitor. miR-140-5p directly bound to the 3'-untranslated region of ROBO4 mRNA. ROBO4 overexpression mitigated the effects of ox-LDL treatment on VSMC viability, migration, invasion and apoptosis. Therefore, the present study suggested that high level miR-140-5p expression promoted VSMC viability, migration, and invasion, and suppressed VSMC apoptosis by reducing ROBO4 gene expression. The present study provided novel insights into AS pathogenesis that may aid the development of new strategies for the treatment and prevention of AS.

Increased serum calcium levels are associated with carotid atherosclerotic plaque in normocalcaemic individuals with type 2 diabetes

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) have an elevated risk of atherosclerotic cardiovascular disease. Although previous data have suggested that serum calcium levels could be involved in T2DM and cardiovascular disease, whether this applies in T2DM patients with atherosclerosis remains unclear. This study therefore aimed to investigate the relationship between serum calcium levels within the physiological ranges and carotid atherosclerotic plaque in T2DM patients.

METHODS

A total of 594 normocalcaemic in-patients with T2DM were recruited, of whom 231 had carotid atherosclerotic plaque. Serum calcium levels were measured and carotid ultrasonography was performed.

RESULTS

Patients with plaque had significantly higher serum albumin-corrected calcium than those without plaque [9.02 (8.78-9.34) mg/dL versus 8.86 (8.66-9.06) mg/dL, p < 0.001]. As serum albumin-corrected calcium levels increased across tertiles, the percentage of plaque increased (27.6%, 35.5%, and 55.7%; p < 0.001). Logistic regression showed that serum albumin-corrected calcium levels were independently and positively correlated with the presence of plaque, but not parathyroid hormone levels. Compared with patients in the lowest serum calcium tertiles, the odds ratio for plaque in patients in the upper quartile was 2.47 (95% confidence interval 1.51-4.03, p < 0.001) after adjustment for potential confounders.

CONCLUSION

Serum albumin-corrected calcium levels are elevated in patients with T2DM and carotid atherosclerotic plaques.

Cytokine regulation of apoptosis-induced apoptosis and apoptosis-induced cell proliferation in vascular smooth muscle cells

Vascular smooth muscle cells (VSMCs) are the main structural cell of blood vessels, and VSMC apoptosis occurs in vascular disease, after injury, and in vessel remodeling during development. Although VSMC apoptosis is viewed as silent, recent studies show that apoptotic cells can promote apoptosis-induced compensatory proliferation (AICP), apoptosis-induced apoptosis (AIA), and migration of both local somatic and infiltrating inflammatory cells. However, the effects of VSMC apoptosis on adjacent VSMCs, and their underlying signaling and mechanisms are unknown. We examined the consequences of VSMC apoptosis after activating extrinsic and intrinsic death pathways. VSMCs undergoing apoptosis through Fas/CD95 or the protein kinase inhibitor staurosporine transcriptionally activated interleukin 6 (IL-6) and granulocyte-macrophage colony stimulating factor (GM-CSF), leading to their secretion. Apoptosis induced activation of p38MAPK, JNK, and Akt, but neither p38 and JNK activation nor IL-6 or GM-CSF induction required caspase cleavage. IL-6 induction depended upon p38 activity, while Fas-induced GM-CSF expression required p38 and JNK. Conditioned media from apoptotic VSMCs induced VSMC apoptosis in vitro, and IL-6 and GM-CSF acted as pro-survival factors for AIA. VSMC apoptosis was studied in vivo using SM22α-DTR mice that express the diphtheria toxin receptor in VSMCs only. DT administration induced VSMC apoptosis and VSMC proliferation, and also signficantly induced IL-6 and GM-CSF. We conclude that VSMC apoptosis activates multiple caspase-independent intracellular signaling cascades, leading to release of soluble cytokines involved in regulation of both cell proliferation and apoptosis. VSMC AICP may ameliorate while AIA may amplify the effects of pro-apoptotic stimuli in vessel remodeling and disease.

Berberine inhibits proliferation and apoptosis of vascular smooth muscle cells induced by mechanical stretch via the PDI/ERS and MAPK pathways

AIMS

We recently demonstrated that mechanical stretch increases the proliferation and apoptosis of vascular smooth muscle cells (VSMCs) by activating the protein disulfide isomerase (PDI) redox system, thus accelerating atherosclerotic lesion formation in the transplanted vein. At present, there are no efficient intervention measures to prevent this phenomenon. Berberine inhibits pathological vascular remodeling caused by hypertension, but the underlying mechanism is controversial. Herein, we investigate the role of berberine and the underlying mechanism of its effects on mechanical stretch-induced VSMC proliferation and apoptosis.

MAIN METHODS

Mouse VSMCs cultivated on flexible membranes were pretreated for 1 h with one of the following substances: berberine, PDI inhibitor bacitracin, MAPK inhibitors, or ERS inhibitor 4-PBA. VSMCs were then subjected to mechanical stretch. Immunofluorescence and western blot were used to detect proliferation and apoptosis, as well as to analyze signaling pathways in VSMCs.

KEY FINDINGS

Our results showed that berberine inhibits the PDI-endoplasmic reticulum stress system, thereby attenuating the simultaneous increase of VSMC proliferation and apoptosis in response to mechanical stretch. Interestingly, MAPK inhibitors PD98059, SP600125, and SB202190 significantly reduced the activation of ERS signaling cascades, and their combination with berberine had additive effects. The ERS inhibitor 4-PBA reduced PDI activation and ERS signaling, but not MAPK phosphorylation. Moreover, caspase-3 and caspase-12 were downregulated by berberine.

SIGNIFICANCE

These results illustrate a novel mechanism of action of berberine that has practical implications. Our data provide important insights for the prevention and treatment of vascular remodeling and diseases caused by mechanical stretching during hypertension.

Biomechanical signal communication in vascular smooth muscle cells

Biomechanical stresses are closely associated with cardiovascular development and diseases. In vivo, vascular smooth muscle cells are constantly stimulated by biomechanical factors caused by increased blood pressure leading to the non-specific activation of cell transmembrane proteins. Thus, various intracellular signal molecules are simultaneously activated via signaling cascades, which are closely related to alterations in the differentiation, phenotype, inflammation, migration, pyroptosis, calcification, proliferation, and apoptosis of vascular smooth muscle cells. Meanwhile, mechanical stress-induced miRNAs and epigenetics modification on vascular smooth muscle cells play critical roles as well. Eventually, the overall pathophysiology of the cells is altered, resulting in the development of many major clinical diseases, including hypertension, atherosclerosis, grafted venous atherosclerosis, and aneurysm, among others. In this paper, important advances in mechanical signal communication in vascular smooth muscle cells are reviewed.

Protein disulfide isomerase in cardiovascular disease

Protein disulfide isomerase (PDI) participates in the pathogenesis of numerous diseases. Increasing evidence indicates that intravascular cell-derived PDI plays an important role in the initiation and progression of cardiovascular diseases, including thrombosis and vascular inflammation. Recent studies with PDI conditional knockout mice have advanced our understanding of the function of cell-specific PDI in disease processes. Furthermore, the identification and development of novel small-molecule PDI inhibitors has led into a new era of PDI research that transitioned from the bench to bedside. In this review, we will discuss recent findings on the regulatory role of PDI in cardiovascular disease.

Efforts to untangle the functions of a large family of enzymes could lead researchers to new therapies for diverse cardiovascular diseases. Members of the protein disulfide isomerase (PDI) family chemically modify other proteins in ways that can alter both their structure and biological activity. Jaehyung Cho of the University of Illinois at Chicago, USA and coworkers have reviewed numerous studies linking PDI with cardiovascular diseases, including thrombosis, heart attack, vascular inflammation, and stroke. The authors also report progress in developing small-molecule PDI inhibitors that could yield the treatment for these conditions.

LncRNA MEG3-derived miR-361-5p regulate vascular smooth muscle cells proliferation and apoptosis by targeting ABCA1

BACKGROUND

Atherosclerosis remains a leading cause of cardiology disease worldwide, which vascular smooth muscle cells (VSMCs) proliferation and apoptosis are involved. Increasing evidences have revealed that long non-coding RNAs (lncRNAs) considered to be critical regulatory factors of VSMCs function. However, the molecular mechanism is not fully understood.

METHODS

First, we establish the ox-LDL induced VSMC model. We conducted RT-PCR to measure MEG3 expression and miR-361-5p expression in this model. The proliferation and apoptosis of VSMCs were measured via CCK-8 proliferative assay and flow cytometry respectively. We used knockdown and overexpression system to identify the molecular mechanism. In addition, luciferase report assay and bioinformatics analysis were used to confirm the bio-target of different factors.

RESULTS

LncRNA MEG3 was down-regulated and related with miR-361-5p expression in ox-LDL injured VSMCs. Inhibition of lncRNA MEG3 promotes the proliferation and decelerates apoptosis of VSMCs. Moreover, MEG3 acts as a competing endogenous RNA (ceRNA) for miR-361-5p and further regulate ABCA1 expression regulate proliferation and apoptosis in ox-LDL injured VSMCs.

CONCLUSION

These results suggest that LncRNA MEG3 regulate proliferation and apoptosis in ox-LDL injured VSMCs and function as a ceRNA for miR-361-5p to modulate ABCA1 expression.

Angiotensin II inhibits apoptosis of mouse aortic smooth muscle cells through regulating the circNRG-1/miR-193b-5p/NRG-1 axis

Angiotensin II (Ang II) is known to promote proliferation of vascular smooth muscle cells (VSMCs) in vascular remodeling, but whether it has an anti-apoptotic effect needs to be explored. Neuregulin-1 (NRG-1) as a member of the epidermal growth factor family was reported to suppress the proliferation of VSMCs by activating ErbB receptors, and therefore we hypothesized that there might be a cross talk between the anti-apoptotic effect of Ang II and the anti-proliferative effect of NRG-1 in VSMCs. The aim of the present study was to observe the expression and role of NRG-1 underlying the inhibitory effect of Ang II on apoptosis of mouse aortic smooth muscle cells (MASMCs). It was found that NRG-1 expression was down-regulated via the circNRG-1/miR-193b-5p-mediated post-transcriptional mechanism in response to Ang II. In addition, NRG-1 overexpression reversed the inhibitory effect of Ang II on apoptosis in MASMCs. Our data may provide a molecular basis for further understanding the mechanism of Ang II in suppressing the apoptosis of MASMCs by decreasing NRG-1 expression at circular RNA and micro RNA levels. The circNRG-1/miR-193b-5p/NRG-1 axis may prove to be a potential target for Ang II to inhibit the apoptosis of VSMCs and lead to vascular remodeling.

Modulation of the Proliferation/Apoptosis Balance of Vascular Smooth Muscle Cells in Atherosclerosis by lncRNA-MEG3 via Regulation of miR-26a/Smad1 Axis

The balance between proliferation and apoptosis of vascular smooth muscle cells (VSMCs) plays a critical role in the initiation of atherosclerosis. LncRNA-MEG3 is involved in the pathophysiology of atherosclerosis through regulation of endothelial cell proliferation and migration. Its effect on the dysfunction of VSMCs and the corresponding mechanisms are actively researched. In this study, we observed that downregulated lncRNA-MEG3 expression was inversely correlated with the microRNA-26a level in coronary artery disease tissues. The overexpression of lncRNA-MEG3 could inhibit VSMCs proliferation while facilitating apoptosis. Moreover, alteration in the miR-26a/Smad1 axis could antagonize this effect. Bioinformatic analysis indicated that lncRNA-MEG3 could interact with miR-26a via complementary binding sites. The enforced expression of lncRNA-MEG3 could reduce the level of miR-26a in VSMCs, while the expression of Smad1 increases. Further, the direct binding between lncRNA-MEG3 and miR-26a was confirmed via dual-luciferase reporter assay, which indicated that lnc-MEG3 could sponge miR-26a as a competing endogenous RNA. In summary, we propose that lncRNA-MEG3 modulates the proliferation/apoptosis balance of VSMCs in atherosclerosis by regulating the miR-26a/Smad1 axis.

Long non-coding RNAs in coronary atherosclerosis

Coronary atherosclerosis (CAS), a leading cause of cardiovascular disease, is a major cause of death worldwide. CAS is a chronic disease in the aorta that can be caused by dyslipidemia, abnormal glucose metabolism, endothelial cell dysfunction, vascular smooth muscle cell (VSMC) or fibrous connective tissue hyperplasia, immune inflammatory reactions, and many other factors. The pathogenesis of CAS is not fully understood, as it is a complex lesion complicated by multiple factors. Damage-response theories have put forward endothelial cell (EC) injury as the initiating factor for CAS; the addition of lipid metabolism disorders may enhance monocyte adhesion, increase the proliferation and migration of fibroblasts and VSMCs, and accelerate the development of CAS. Furthermore, inflammatory and immune responses can create a vicious cycle of endothelial injury, which also plays key roles in the formation of CAS. Therefore, in order to elucidate the mechanisms controlling CAS, it is important to study the etiology of vascular cell dysfunction, abnormal energy and metabolism disorders, and immune and inflammatory reactions. Non-coding RNAs play regulatory roles in the pathogenesis of CAS, especially long non-coding RNAs (lncRNAs); lncRNAs have recently become a major focus for cardiovascular disease mechanisms, as they play numerous roles in the progression of CAS. Therefore, in this review, we discuss the role of lncRNAs in the pathogenesis of coronary CAS, and their role in the prevention and treatment of coronary CAS.

Mathematical model of hypertension-induced arterial remodeling: A chemo-mechanical approach

The development of chronic hypertension is a poorly described process involving many chemical and structural changes to the artery. Typically, mathematical models of this disease focus primarily on the mechanical aspects such as arterial geometry, elasticity, and tissue content, or alternatively on the chemical drivers of vasoactivity such as nitric oxide and reactive oxygen species. This paper presents a model that considers the powerful interaction between mechanical and biochemical drivers of hypertension and arterial remodeling. Based on biological processes thought to be involved in the development of hypertension, we have built a system of algebraic, differential, and integral equations. Endothelial dysfunction, which is known to limit vasodilation, is explicitly considered in the model and plays a vital role in the development of chronic hypertension. Numerical solutions to the system are consistent with available experimental data for normal and spontaneously-hypertensive rats.

ICAM-1-Targeted Liposomes Loaded with Liver X Receptor Agonists Suppress PDGF-Induced Proliferation of Vascular Smooth Muscle Cells

The proliferation of vascular smooth muscle cells (VSMCs) is one of the key events during the progress of atherosclerosis. The activated liver X receptor (LXR) signalling pathway is demonstrated to inhibit platelet-derived growth factor BB (PDGF-BB)-induced VSMC proliferation. Notably, following PDGF-BB stimulation, the expression of intercellular adhesion molecule-1 (ICAM-1) by VSMCs increases significantly. In this study, anti-ICAM-1 antibody-conjugated liposomes were fabricated for targeted delivery of a water-insoluble LXR agonist (T0901317) to inhibit VSMC proliferation. The liposomes were prepared by filming-rehydration method with uniform size distribution and considerable drug entrapment efficiency. The targeting effect of the anti-ICAM-T0901317 liposomes was evaluated by confocal laser scanning microscope (CLSM) and flow cytometry. Anti-ICAM-T0901317 liposomes showed significantly higher inhibition effect of VSMC proliferation than free T0901317 by CCk8 proliferation assays and BrdU staining. Western blot assay further confirmed that anti-ICAM-T0901317 liposomes inhibited retinoblastoma (Rb) phosphorylation and MCM6 expression. In conclusion, this study identified anti-ICAM-T0901317 liposomes as a promising nanotherapeutic approach to overcome VSMC proliferation during atherosclerosis progression.

[Effects of simvastatin on aortic vascular endothelial cell apoptosis and Bcl-2 protein expression in a rat model of atherosclerosis]

OBJECTIVE

To explore the effects of simvastatin on vascular endothelial cell apoptosis and Bcl-2 protein expression in the aorta in a rat model of atherosclerosis.

METHODS

Thirty-six rats were randomized into control group (n=10), atherosclerosis model group (n=13) and simvastatin intervention group (n=13). In the latter two groups, rat models of atherosclerosis were established by intraperitoneal injection of vitamin D3 combined with high-fat feeding for 6 weeks, and the control rats were fed with regular diet. In the intervention group, the rats were further fed with high-fat diet with daily simvastatin treatment for 4 weeks. After the treatments, the pathological changes and plaque in the thoracic aorta were observed, and the expression of Bcl-2 protein was detected with immunohistochemistry. TUNEL assay was used to determine the apoptosis index (AI) of the vascular endothelial cells.

RESULTS

Compared with that in the control group, Bcl-2 protein expression in the aorta of atherosclerotic rats was significantly decreased (P<0.05); simvastatin treatment obviously increased the expression of Bcl-2 protein in atherosclerotic rats (P<0.05) to a level similar to that in the control group. The AI was the highest in the model group (P<0.05) and comparable between the control and simvastatin treatment group.

CONCLUSION

The therapeutic effect of simvastatin against atherosclerosis is probably mediated by up-regulation of Bcl-2 protein, which inhibits vascular endothelial cell apoptosis in rats with aortic atherosclerosis.

Effect of crocetin on vascular smooth muscle cells migration induced by advanced glycosylation end products

Crocetin is a major active constituent of Gardenia jasminoides J. Ellis, and can aid in the prevention of cardiovascular disease. The effect and possible mechanism of crocetin on the migration of vascular smooth muscle cells (VSMCs) induced by advanced glycosylation end products (AGEs) were investigated. VSMCs were pre-incubated with or without crocetin and exposed to AGEs subsequently. The invasion of the cells was investigated using a 24-well Cell Invasion Chamber. The anti-proliferative activity of crocetin was evaluated by MTT assay and VSMCs cell-cycle distribution was examined by flow cytometry. Cytokine TNF-α and IL-6 secreted by VSMCs and the amount of matrix metalloproteinase MMP-2 and MMP-9 in the culture supernatant were detected by ELISA. The expression level of RAGE (AGEs receptor), in cells was analyzed by western blot. The results demonstrated that AGEs increased about two-fold migration of VSMCs compared with control (OD=0.778±0.191 vs OD=0.413±0.214, P<0.01), and the proliferation increased by about 20% (OD=0.335±0.043 vs OD=0.281±0.037, P<0.01). Pre-treatment with crocetin (1.0μM) or RAGE antibody (10μg/ml) could inhibit the AGEs triggered migration of VSMCs obviously. Furthermore, both crocetin and RAGE antibody inhibited the increase of RAGE protein in VSMCs stimulated by AGEs. The levels of TNF-α and IL-6 decreased in the crocetin (1.0μM) pre-treated group compared to the AGEs (without pre-treated) group (37.60±3.08pg/ml vs 46.59±1.92pg/ml, 32.11±4.69pg/ml vs 49.99±8.84pg/ml, respectively). Crocetin (1.0μM) also reduced the value of MMP-2 and MMP-9 compared with the AGEs group (2.81±0.35ng/ml vs 6.40±0.85ng/ml, 2.69±0.25ng/ml vs 4.32±0.57ng/ml, respectively). In summary, crocetin inhibits the migration of VSMCs induced by AGEs through RAGE-dependent signaling pathway. And it is meaningful to diabetic vascular complications.

Phenotypic and functional transformation in smooth muscle cells derived from varicose veins

OBJECTIVE

Varicose veins (VVs) are a common disorder of venous dilation and tortuosity, but the underlying mechanism is unclear. The functional integrity and phenotypic differences of VVs are also unclear. This study tested the hypothesis that phenotypic and functional differences exist between smooth muscle cells (SMCs) derived from VVs and normal veins.

METHODS

SMCs were isolated from 28 samples of varicose great saphenous veins (VGSVs) and normal great saphenous (NGSVs) and cultured. Proliferation, migration, adhesion, and aging capacity in SMCs were compared in the two veins. Bas, Bcl-2, caspase-3, matrix metalloproteinase (MMP)-2 MMP-9, tissue inhibitor of metalloproteinases (TIMP)-1, and TIMP-2 messenger (m)RNA expression and protein content were detected by fluorescence quantitative polymerase chain reaction and immunoblotting.

RESULTS

The microfilament structure of the framework was increased in SMCs in the VGSV group. Proliferation, migration, adhesion, and the aging cell count in SMCs in the VGSV group were significantly higher than the corresponding regions in the NGSV group (P < .05). Bas and caspase-3 mRNA expression and protein content were decreased, whereas Bcl-2 mRNA expression and protein content were increased in the VGSV group compared with the NGSV group (P < .05). MMP-2, MMP-9, TIMP-1, and TIMP-2 mRNA expression and protein content in the VGSV group were increased compared with the NGSV group (P < .05).

CONCLUSIONS

SMCs derived from VGSVs are more dedifferentiated and demonstrate increased proliferative and synthetic capacity. These results suggest the presence of phenotypic and functional differences between SMCs derived from VGSVs and NGSVs. The phenotypic and functional abnormalities in SMCs may be associated with the pathogenesis in VGSVs.

Protein disulfide isomerase-mediated apoptosis and proliferation of vascular smooth muscle cells induced by mechanical stress and advanced glycosylation end products result in diabetic mouse vein graft atherosclerosis

Protein disulfide isomerase (PDI) involves cell survival and death. Whether PDI mediates mechanical stretch stress (SS) and/or advanced glycosylation end products (AGEs) -triggered simultaneous increases in proliferation and apoptosis of vascular smooth muscle cells (VSMCs) is unknown. Here, we hypothesized that different expression levels of PDI trigger completely opposite cell fates among the different VSMC subtypes. Mouse veins were grafted into carotid arteries of non-diabetic and diabetic mice for 8 weeks; the grafted veins underwent simultaneous increases in proliferation and apoptosis, which triggered vein graft arterializations in non-diabetic or atherosclerosis in diabetic mice. A higher rate of proliferation and apoptosis was seen in the diabetic group. SS and/or AGEs stimulated the quiescent cultured VSMCs, resulting in simultaneous increases in proliferation and apoptosis; they could induce increased PDI activation and expression. Both in vivo and in vitro, the proliferating VSMCs indicated weak co-expression of PDI and SM-α-actin while apoptotic or dead cells showed strong co-expression of both. Either SS or AGEs rapidly upregulated the expression of PDI, NOX1 and ROS, and their combination had synergistic effects. Inhibiting PDI simultaneously suppressed the proliferation and apoptosis of VSMCs, while inhibition of SM-α-actin with cytochalasin D led to increased apoptosis and cleaved caspases-3 but had no effect on proliferation. In conclusion, different expression levels of PDI in VSMCs induced by SS and/or AGEs triggered a simultaneous increase in proliferation and apoptosis, accelerated vein graft arterializations or atherosclerosis, leading us to propose PDI as a novel target for the treatment of vascular remodeling and diseases.

Functional and Proteomic Investigations Reveal Major Royal Jelly Protein 1 Associated with Anti-hypertension Activity in Mouse Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) are a major cell type of the arterial wall and their functionality is associated with blood pressure regulation. Although royal jelly (RJ) has reported effects on anti-hypertension, the mechanism of blood pressure regulation by major royal jelly protein 1 (MRJP1), the most abundant RJ protein, is still unknown. The mrjp1 gene was inserted into mouse VSMCs to investigate how MRJP1 influences VSMC functionality by functional and proteomic analysis. The expression of MRJP1 in VSMCs significantly reduced cell contraction, migration, and proliferation, suggesting a potential role in decreasing hypertension via action on VSMCs. These anti-hypertension activities were further observed in the changes of the proteome setting of mouse VSMCs. Among 675 different proteins after MRJP1 expression, 646 were down-regulated and significantly enriched in pathways implicated in VSMC contraction and migration, which suggest MRJP1 lowers VSMC contraction and migration by inhibiting muscle filament movement. The down-regulated proteins also enriched pathways in proliferation, indicating that MRJP1 hinders VSMC proliferation by reducing the supply of energy and genetic material. This is the first report integrating MRJP1 into VSMC, revealing the function and mechanism correlated with anti-hypertensive activity. This offers a therapeutic potential to control hypertension by gene-therapy using bee-products.