Apoptosis Of Aortic Smooth Muscle Cells Research Articles

Indoxyl Sulfate-induced Vascular Calcification is mediated through Altered Notch Signaling Pathway in Vascular Smooth Muscle Cells.

Introduction: The aim of this study was to determine the role of Notch in indoxyl sulfate (IS)-induced vascular calcification (VC).Materials and methods: VC and expression of Notch-related and osteogenic molecules were examined in Dahl salt-sensitive (DS), DS hypertensive (DH), and DH IS-treated rats (DH+IS). The effects of IS on expression of Notch receptors, apoptotic activity, and calcification were examined in cultured aortic smooth muscle cells (SMCs).Results: Medial calcification was noted only in aortas and coronary arteries of DH+IS rats. Notch1, Notch3, and Hes-1 were expressed in aortic SMCs of all rats, but only weakly in the central areas of the media and around the calcified lesions in DH+IS rats. RT-PCR and western blotting of DH+IS rat aortas showed downregulation of Notch ligands, Notch1 and Notch3, downstream transcriptional factors, and SM22, and conversely, overexpression of osteogenic markers. Expression of Notch1 and Notch3 in aortic SMCs was highest in incubation under 500 μM IS for 24hrs, and then decreased time- and dose-dependently. Coupled with this decrease, IS increased caspase 3/7 activity and TUNEL-positive aortic SMCs. In addition, pharmacological Notch signal inhibition with DAPT induced apoptosis in aortic SMCs. ZVAD, a caspase inhibitor abrogated IS-induced and DAPT-induced in vitro vascular calcification. Knockdown of Notch1 and Notch3 cooperatively increased expression of osteogenic transcriptional factors and decreased expression of SM22.Conclusion: Our results suggested that IS-induced VC is mediated through suppression of Notch activity in aortic SMCs, induction of osteogenic differentiation and apoptosis.

P3779MRTF-A mediates aortic smooth muscle cell apoptosis and inflammatory response to develop aortic dissection

P3779MRTF-A mediates aortic smooth muscle cell apoptosis and inflammatory response to develop aortic dissection

IL-22 modulates inflammatory properties of human primary aortic smooth muscle cells.

IL-22 is expressed at barrier surfaces, which suggests its critical role in the maintenance of normal barrier homeostasis and tissue repair. IL-22 can both promote pathological inflammation and prevent the destruction of tissues. The functional outcomes of IL-22 on vascular smooth muscle cells, which are shown to regulate immune processes within the vascular wall and which are involved in certain pathologies, have not been analyzed. The effect of IL-22 on the expression of novel antiand pro-inflammatory and barrier disrupting cytokines, apoptosis and the expression of adhesive molecules in human primary aortic smooth muscle cells (AoSMC) was investigated. Human AoSMC were induced with IL-22 for 24 h in vitro. The influence of IL-22 on IL-35 subunits EBI3 and p35, IL-33, IFN-γ and VEGF mRNA expression in Ao-SMC were assessed using real-time PCR. Additionally, the surface expression of ICAM-1 and apoptosis of AoSMC were analyzed in the flow cytometer. IL-22 caused a 2- and 3-fold increase of mRNA expression of the EBI3 and p35 IL-35 subunits, and a 40% decrease of IL-33 mRNA expression in AoSMC. Additionally, IL-22 decreased ICAM-1 expression on the surface of AoSMC by 30%. However, IL-22 affected neither IFN-γ and VEGF mRNA expression in AoSMC nor their apoptosis and viability. Our data suggest that IL-22, which is released by Th22 and NK cells, may be an agent affecting the inflammatory response of AoSMC, and thus it may regulate immune homeostasis of the vascular wall.

RhoA deficiency disrupts podocyte cytoskeleton and induces podocyte apoptosis by inhibiting YAP/dendrin signal.

BackgroundPodocyte apoptosis is a major mechanism that leads to proteinuria in many kidney diseases. However, the concert mechanisms that cause podocyte apoptosis in these kidney diseases are not fully understood. RhoA is one of Rho GTPases that has been well studied and plays a key role in regulating cytoskeletal architecture. Previous study showed that insufficient RhoA could result in rat aortic smooth muscle cell apoptosis. However, whether RhoA is involved in podocyte apoptosis remains unknown.MethodsCulture podocytes were treated with LPS, ADR or siRNA for 48 h before harvest. Subcellular immunoblotting, qRT-PCR, immunofluorescence and flow cytometry were used to exam the expression and function of RhoA or YAP in podocytes.ResultsWe found that the expression of RhoA and its activity were significantly decreased in LPS or ADR-injured podocytes, accompanying loss of stress fibers and increased cell apoptosis. Knocking down RhoA or its downstream effector mDia expression by siRNA also caused loss of stress fibers and podocyte apoptosis. Moreover, our results further demonstrated that RhoA deficiency could reduce the mRNA and protein expression of YAP, which had been regarded as an anti-apoptosis protein in podocyte. Silenced dendrin expression significantly abolished RhoA, mDia or YAP deficiency-induced podocyte apoptosis.ConclusionRhoA deficiency could disrupt podocyte cytoskeleton and induce podocyte apoptosis by inhibiting YAP/dendrin signal. RhoA/mDia/YAP/dendrin signal pathway may potentially play an important role in regulating podocyte apoptosis. Maintaining necessary RhoA would be one potent way to prevent proteinuria kidney diseases.

Abstract 119: Nebivolol Suppresses Hypoxic-Induced Rat Thoracic Aortic Smooth Muscle Cell Apoptosis by a Mechanism Involving Nitric Oxide Production, HSP70 Upregulation and Inhibition of P53 Phosphorylation

Aneurysmal degeneration of the ascending aortic artery is a common and frequently lethal disease process. Localized hypoxic-induced aortic smooth muscle cell (SMC) apoptosis, a factor amenable to medical intervention, has been reported to participate in the pathogenesis of ascending aortic aneurysm formation (ASAA. β-adrenergic blockers are the drugs most commonly used in the treatment of ASAA. The aim of this study was to investigate the effects of the new third-generation β-blocker nebivolol (NB) on hypoxic-induced smooth muscle cell apoptosis and to characterize the mechanisms activated in this NB action. Treatment of cultured rat thoracic aortic SMC, with NB (10 μM) compared to diluent (100 μM Ascorbic acid) (AA) for 1 hr attenuated hypoxic (5%C02/95%N2) apoptosis as measured by decreases in TUNEL positive staining (15.3+2.3 (AA) vs 5.6+1.2 (NB) % apoptotic nuclei, p<0.05), caspase-3 activity (91.3+2.4 (AA) vs 72.1+0.8 (NB) μmol/mL, p<0.05), the apoptotic ratio of bax/bcl-2 mRNA expression (1.37+0.14 (AA) vs 0.82+0.11 (NB) fold-change, p<0.05), pro-apoptotic miR1 (2.9+0.35 (AA) vs 1.18+0.22 (NB) fold change, p<0.05), and increased anti-apoptotic miR133A (0.74+0.17 (AA) vs 2.3+0.42 (NB) fold change, p<0.05), n=8-10/group. The NB-induced decrease in hypoxic SMC apoptosis was associated with a 5.5 fold increase in nitric oxide (NO) production as quantified by the ratio of Nitrate/Nitrite, a 2.5-3.2 fold increase in Hsp70 mRNA and protein as measured by RT-PCR and Western analysis respectively, and an attenuation of p53 phosphorylation. Blockade of NO production by L-NAME, or siRNA HSP70 knock down, resulted in an increase in p53 phosphorylation and prevented the NB-induced antiapoptotic response of hypoxic SMC. The beneficial pro-survival response of NB in hypoxic thoracic aortic SMCs makes this novel β-blocker clinically relevant in the treatment of ASAA.

Human HDL containing a novel apoC-I isoform induces smooth muscle cell apoptosis

We discovered that some adults with coronary heart disease (CHD) have a high density lipoprotein (HDL) subclass which induces human aortic smooth muscle cell (ASMC) apoptosis in vitro. The purpose of this investigation was to determine what properties differentiate apoptotic and non-apoptotic HDL subclasses in adults with and without CHD. Density gradient ultracentrifugation was used to measure the particle density distribution and to isolate two HDL subclass fractions, HDL2 and HDL3, from 21 individuals, including 12 without CHD. The HDL fractions were incubated with ASMCs for 24 h; apoptosis was quantitated relative to C2-ceramide and tumour necrosis factor-alpha (TNF-α). The observed effect of some HDL subclasses on apoptosis was ∼6-fold greater than TNF-α and ∼16-fold greater than the cell medium. We observed that apoptotic HDL was (i) predominately associated with the HDL2 subclass; (ii) almost exclusively found in individuals with a higher apoC-I serum level and a novel, higher molecular weight isoform of apoC-I; and (iii) more common in adults with CHD, the majority of whom had high (>60 mg/dL) HDL-C levels. Some HDL subclasses enriched in a novel isoform of apoC-I induce extensive ASMC apoptosis in vitro. Individuals with this apoptotic HDL phenotype generally have higher apoC-I and HDL-C levels consistent with an inhibitory effect of apoC-I on cholesteryl ester transfer protein activity. The association of this phenotype with processes that can promote plaque rupture may explain a source of CHD risk not accounted for by the classical risk factors.

Aldosterone induces aortic smooth muscle cell apoptosis

Objective To determine whether aldosterone induces aortic smooth muscle cell apoptosis in vivo.Methods 24 Sprague-Dawley rats were randomly divided into 3 groups:vehicle as control; aldosterone and aldosterone plus hydralazine.All animals were then implanted with an osmotic mini-pump containing either aldosterone ( 1 μg/h) or vehicle.Hydralazine [ 25 mg/(kg·d) ] was resolved in drinking water and gavaged once daily.After 8 weeks,aortic smooth muscle cell (ASMC) apoptosis was examined by terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) assay.Results TUNEL-positive aortic smooth muscle cells in aldosterone-infused and aldosterone plus hydralazine rats were ( 18.0± 1.5 ) ％ and ( 16.5 ± 2.0) ％ respectively; compared with control rats (4.7 ± 1.0 ) ％,there was signifi-cant difference (P ＜ 0.05 ). In contrast,no significant difference was achieved between the latter twogroups (P ＞ 0.05).Conclusion This study' s findings suggest that aldosterone induces aortic smooth muscle cell apoptosis by its direct effect on the aorta. Key words: Aldosterone; Apoptosis; Smooth muscle cell; Aorta

Mitochondrial Oxidative Stress in Aortic Stiffening With Age

Age-related aortic stiffness is an independent risk factor for cardiovascular diseases. Although oxidative stress is implicated in aortic stiffness, the underlying molecular mechanisms remain unelucidated. Here, we examined the source of oxidative stress in aging and its effect on smooth muscle cell (SMC) function and aortic compliance using mutant mouse models. Pulse wave velocity, determined using Doppler, increased with age in superoxide dismutase 2 (SOD2)+/- but not in wild-type, p47phox-/- and SOD1+/- mice. Echocardiography showed impaired cardiac function in these mice. Increased collagen I expression, impaired elastic lamellae integrity, and increased medial SMC apoptosis were observed in the aortic wall of aged SOD2+/- versus wild-type (16-month-old) mice. Aortic SMCs from aged SOD2+/- mice showed increased collagen I and decreased elastin expression, increased matrix metalloproteinase-2 expression and activity, and increased sensitivity to staurosporine-induced apoptosis versus aged wild-type and young (4-month-old) SOD2+/- mice. Smooth muscle α-actin levels were increased with age in SOD2+/- versus wild-type SMCs. Aged SOD2+/- SMCs had attenuated insulin-like growth factor-1-induced Akt and Forkhead box O3a phosphorylation and prolonged tumor necrosis factor-α-induced Jun N-terminal kinase 1 activation. Aged SOD2+/- SMCs had increased mitochondrial superoxide but decreased hydrogen peroxide levels. Finally, dominant-negative Forkhead box O3a overexpression attenuated staurosporine-induced apoptosis in aged SOD2+/- SMCs. Mitochondrial oxidative stress over a lifetime causes aortic stiffening, in part by inducing vascular wall remodeling, intrinsic changes in SMC stiffness, and aortic SMC apoptosis.

Does atorvastatin induce aortic smooth muscle cell apoptosis in vivo?

It has been reported that HMG-CoA reductase inhibitors such as atorvastatin induce vascular smooth muscle cell (SMC) apoptosis in vitro. However, this effect remains to be demonstrated in vivo. The present studies were designed to test the ability of atorvastatin to induce SMC apoptosis in vivo, using the spontaneously hypertensive rat (SHR) as a well-known reference model of SMC apoptosis induction in vivo by cardiovascular drugs including the calcium channel blocker amlodipine. Atorvastatin was administered to SHR for 3 or 6weeks either alone or together with amlodipine, a drug combination clinically available to patients. Primary endpoints included aortic medial hypertrophy and aortic SMC hyperplasia, internucleosomal DNA fragmentation and expression of the apoptosis regulatory proteins Bax and Bcl-2. The SHR aorta showed no evidence of SMC apoptosis induction by atorvastatin, even at the high dose of 50mgkg−1day−1, although the statin significantly reduced oxidative stress after 3weeks and blood pressure after 6weeks of administration. Amlodipine-induced regression of aortic hypertophy and aortic SMC hyperplasia were dose- and time-dependent, but there was no interaction between atorvastatin and amlodipine in modulating the primary endpoints. These results do not support the notion that atorvastatin induces SMC apoptosis in the aortic media in vivo.

Protein kinase C δ is antiapoptotic in H2O2 induced rats aortic smooth muscle cell apoptosis: Possible role in human atherosclerotic plaque remodeling

Protein kinase C δ is antiapoptotic in H2O2 induced rats aortic smooth muscle cell apoptosis: Possible role in human atherosclerotic plaque remodeling

Pulse Pressure-Induced Transmural Fluid Flux Increases Bovine Aortic Smooth Muscle Cell Apoptosis in a Mitogen Activated Protein Kinase Dependent Manner

Background: Mechanical forces associated with blood flow are critical in the regulation of vascular smooth muscle cell (VSMC) growth, migration, differentiation and apoptosis as fundamental features in the pathogenesis of vascular disease. We investigated the effect of pulse pressure on VSMC apoptosis. Methods: Using a perfused transcapillary co-culture system, bovine thoracic aortic SMC (BASMC) were exposed to increases in pulsatile flow (0.3–17 ml/min) and hence pulse pressure (amplitude of pulse 6–50 mm Hg) in the absence or presence of bovine aortic endothelial cells (BAEC). The extent of apoptosis was determined by measuring caspase-3 activity, the levels of pro- and anti-apoptotic Bcl-2 family proteins, FasL and cellular apoptosis susceptibility (CAS) protein expression and the extent of DNA fragmentation. Results: Changes in pulse pressure resulted in a significant force- and time-dependent increase in caspase-3 activity in BASMC. This effect was maximal after 6 h, independent of BAEC presence, and attenuated following inhibition of mitogen-activated protein kinase (MAPK) activity with PD98059. In parallel cultures, there was a significant increase in Bad and Bax expression, concomitant with an increase in DNA fragmentation, and a significant decrease in Bcl-2 and Bcl-X_L expression. The pro-apoptotic effects of pulse pressure were specific for differentiated cells but independent of p53, inasmuch as FasL and CAS expression were enhanced in differentiated adult cells but decreased in de-differentiated embryonic cells in response to flow. Conclusions: These results suggest that pulse pressure promotes phenotypically distinct VSMC apoptosis in vitro in an endothelial-independent, MAPK-dependent, manner.