Coronary Smooth Muscle Cells Research Articles

PRMT1-p53 Pathway Controls Epicardial EMT and Invasion

Epicardial cells are cardiac progenitors that give rise to the majority of cardiac fibroblasts, coronary smooth muscle cells, and pericytes during development. An integral phase of epicardial fate transition is epithelial-to-mesenchymal transition (EMT) that confers motility. We uncover an essential role for the protein arginine methyltransferase 1 (PRMT1) in epicardial invasion and differentiation. Using scRNA-seq, we show that epicardial-specific deletion of Prmt1 reduced matrix and ribosomal gene expression in epicardial-derived cell lineages. PRMT1 regulates splicing of Mdm4, which is a key controller of p53 stability. Loss of PRMT1 leads to accumulation of p53 that enhances Slug degradation and blocks EMT. During heart development, the PRMT1-p53 pathway is required for epicardial invasion and formation of epicardial-derived lineages: cardiac fibroblasts, coronary smooth muscle cells, and pericytes. Consequently, this pathway modulates ventricular morphogenesis and coronary vessel formation. Altogether, our study reveals molecular mechanisms involving the PRMT1-p53 pathway and establish its roles in heart development.

Inflammatory Drivers of Cardiovascular Disease: Molecular Characterization of Senescent Coronary Vascular Smooth Muscle Cells.

The senescence of vascular smooth muscle cells (VSMCs) has been implicated as a causal pro-inflammatory mechanism for cardiovascular disease development and progression of atherosclerosis, the instigator of ischemic heart disease. Contemporary limitations related to studying this cellular population and senescence-related therapeutics are caused by a lack of specific markers enabling their detection. Therefore, we aimed to profile a phenotypical and molecular signature of senescent VSMCs to allow reliable identification. To achieve this goal, we have compared non-senescent and senescent VSMCs from two in vitro models of senescence, replicative senescence (RS) and DNA-damage induced senescence (DS), by analyzing the expressions of established senescence markers: cell cycle inhibitors- p16 INK4a, p14 ARF, p21 and p53; pro-inflammatory factors-Interleukin 1β (IL-1β), IL-6 and high mobility group box-1 (HMGB-1); contractile proteins-smooth muscle heavy chain- (MYH11), smoothelin and transgelin (TAGLN), as well as structural features (nuclear morphology and LMNB1 (Lamin B1) expression). The different senescence-inducing modalities resulted in a lack of the proliferative activity. Nucleomegaly was seen in senescent VSMC as compared to freshly isolated VSMC Phenotypically, senescent VSMC appeared with a significantly larger cell size and polygonal, non-spindle-shaped cell morphology. In line with the supposed switch to a pro-inflammatory phenotype known as the senescence associated secretory phenotype (SASP), we found that both RS and DS upregulated IL-1β and released HMGB-1 from the nucleus, while RS also showed IL-6 upregulation. In regard to cell cycle-regulating molecules, we detected modestly increased p16 levels in both RS and DS, but largely inconsistent p21, p14ARF, and p53 expressions in senescent VSMCs. Since these classical markers of senescence showed insufficient deregulation to warrant senescent VSMC detection, we have conducted a non-biased proteomics and in silico analysis of RS VSMC demonstrating altered RNA biology as the central molecular feature of senescence in this cell type. Therefore, key proteins involved with RNA functionality, HMGB-1 release, LMNB-1 downregulation, in junction with nuclear enlargement, can be used as markers of VSMC senescence, enabling the detection of these pathogenic pro-inflammatory cells in future therapeutic studies in ischemic heart disease and atherosclerosis.

The adipokine vaspin is associated with decreased coronary in-stent restenosis in vivo and inhibits migration of human coronary smooth muscle cells in vitro.

BackgroundPercutaneous coronary intervention represents the most important treatment modality of coronary artery stenosis. In-stent restenosis (ISR) is still a limitation for the long-term outcome despite the introduction of drug eluting stents. It has been shown that adipokines directly influence vessel wall homeostasis by influencing the function of endothelial cells and arterial smooth muscle cells. Visceral adipose tissue-derived serpin vaspin was recently identified as a member of serine protease inhibitor family and serveral studies could demonstrate a relation to metabolic diseases. The aim of this study was to investigate a role of vaspin in the development of in-stent restenosis in vivo and on migration of smooth muscle cells and endothelial cells in vitro.MethodsWe studied 85 patients with stable coronary artery disease who underwent elective and successful PCI with implatation of drug eluting stents. Blood samples were taken directly before PCI. Vaspin plasma levels were measured by specific ELISA. ISR was evaluated eight months later by coronary angiography. Human coronary artery smooth muscle cells (HCASMC) and human umbilical vein endothelial cells (HUVEC) migration was analyzed by an in-vitro migration assay with different concentrations (0.004ng/mL up to 40ng/mL) of vaspin as well as by an scratch assay. For proliferation an impedance measurement with specialiced E-Plates was performed.ResultsDuring the follow up period, 14 patients developed ISR. Patients with ISR had significantly lower vaspin plasma levels compared to patients without ISR (0.213 ng/ml vs 0.382 ng/ml; p = 0.001). In patients with plasma vaspin levels above 1.35 ng/ml we could not observe any restenosis. There was also a significant correlation of plasma vaspin levels and late lumen loss in the stented coronary segments. Further we could demonstrate that vaspin nearly abolishes serum induced migration of HCASMC (100% vs. 9%; p<0.001) in a biphasic manner but not migration of HUVEC. Proliferation of HCASMC and HUVEC was not modulated by vaspin treatment.ConclusionWe were able to show that the adipokine vaspin selectively inhibits human coronary SMC migration in vitro and has no effect on HUVEC migration. Vaspin had no effect on proliferation of HUVEC which is an important process of the healing of the stented vessel. In addition, the occurrence of ISR after PCI with implantation of drug eluting stents was significantly associated with low vaspin plasma levels before intervention. Determination of vaspin plasma levels before PCI might be helpful in the identification of patients with high risk for development of ISR after stent implantation. In addition, the selective effects of vaspin on smooth muscle cell migration could potentially be used to reduce ISR without inhibition of re-endothelialization of the stented segment.

Reduced stiffness and augmented traction force in type 2 diabetic coronary microvascular smooth muscle.

Type 2 diabetic (T2DM) coronary resistance microvessels (CRMs) undergo inward hypertrophic remodeling associated with reduced stiffness and reduced coronary blood flow in both mice and pig models. Since reduced stiffness does not appear to be due to functional changes in the extracellular matrix, this study tested the hypothesis that decreased CRM stiffness in T2DM is due to reduced vascular smooth muscle cell (VSMC) stiffness, which impacts the traction force generated by VSMCs. Atomic force microscopy (AFM) and traction force microscopy (TFM) were conducted on primary low-passage CRM VSMCs from normal Db/db and T2DM db/db mice in addition to low-passage normal and T2DM deidentified human coronary VSMCs. Elastic modulus was reduced in T2DM mouse and human coronary VSMCs compared with normal (mouse: Db/db 6.84 ± 0.34 kPa vs. db/db 4.70 ± 0.19 kPa, P < 0.0001; human: normal 3.59 ± 0.38 kPa vs. T2DM 2.61 ± 0.35 kPa, P = 0.05). Both mouse and human T2DM coronary microvascular VSMCs were less adhesive to fibronectin compared with normal. T2DM db/db coronary VSMCs generated enhanced traction force by TFM (control 692 ± 67 Pa vs. db/db 1,507 ± 207 Pa; P < 0.01). Immunoblot analysis showed that T2DM human coronary VSMCs expressed reduced β1-integrin and elevated β3-integrin (control 1.00 ± 0.06 vs. T2DM 0.62 ± 0.14, P < 0.05 and control 1.00 ± 0.49 vs. T2DM 3.39 ± 1.05, P = 0.06, respectively). These data show that T2DM coronary VSMCs are less stiff and less adhesive to fibronectin but are able to generate enhanced force, corroborating previously published computational findings that decreasing cellular stiffness increases the cells' ability to generate higher traction force.NEW & NOTEWORTHY We show here that a potential causative factor for reduced diabetic coronary microvascular stiffness is the direct reduction in coronary vascular smooth muscle cell stiffness. These cells were also able to generate enhanced traction force, validating previously published computational models. Collectively, these data show that smooth muscle cell stiffness can be a contributor to overall tissue stiffness in the coronary microcirculation, and this may be a novel area of interest for therapeutic targets.

Protein Kinase C Activity is Increased in Human Coronary Smooth Muscle Cells following Exposure to 5‐FU Chemotherapy

Background5‐Fluorouracil (5‐FU) is the third most commonly used chemotherapeutic agent used to treat cancer but is strongly associated with a dose‐limiting cardiotoxicity. Cancer patients treated with 5‐FU chemotherapy are at risk of cardiotoxicity that manifests as alterations in the myocardial circulation such as resting or exertional angina, arrhythmias, myocardial infarction, and coronary vasospasm. However, little is known about the primary signaling mechanisms that contribute to cardiotoxicity with 5‐FU. Recent work has suggested that the Protein Kinase C (PKC) family of kinases plays a role in altered vasoconstrictive responses in vascular smooth muscle following exposure to 5‐FU. Further, PKC signaling in other pathologies is known to be influenced by reactive oxygen species (ROS) and 5‐FU chemotherapy is known to promote the production of ROS. Therefore, we hypothesized that 5‐FU administration would increase PKC activity in human coronary smooth muscle cells (HCSMCs).MethodsIn vitro, HCSMCs were incubated with 5‐FU (7×10−3M) for 3h, 1h, and 10 minutes. Following the respective incubation periods, media was aspirated in control and 5‐FU groups and the HCSMCs were scraped, homogenized in lysis buffer, and analyzed for protein content. The activity of PKC was assessed by a PKC activity assay kit.ResultsAnalysis revealed relative PKC activity was significantly increased in HCSMCs following 10 minutes of exposure to 5‐FU chemotherapy (6.52±0.36 versus 4.84±0.36; p=0.02) and was not different at 1 hour versus control and 3 hours versus control (1h 5.28±0.356 versus 4.84±0.36; p=0.82, 3h 5.67±0.36 versus 4.84±0.36; p=0.37).ConclusionsOur findings suggest 5‐FU exposure acutely upregulates PKC activity in coronary smooth muscle cells immediately following drug administration and the PKC pathway may have a mechanistic role in the altered vasoconstrictive response to 5‐FU as previously shown. These findings are imperative given the limited knowledge of mechanistic pathways that lead to vascular damage following 5‐FU exposure. Future studies will focus on reactive oxygen species as a regulator of PKC activity and specific isoforms involved in this pathway.

Coronary Vascular Cell Stiffness Influences Coronary Blood Flow

Our laboratory has previously shown that type 2 diabetic (T2DM) coronary resistance microvessels (CRMs) undergo inward hypertrophic remodeling associated with reduced stiffness. Reduced T2DM CRM tissue stiffness is associated with decreased elastic modulus of coronary vascular smooth muscle cells (VSMCs). The goal of this study was to test the hypothesis that reducing or augmenting coronary vascular cell stiffness will increase or decrease coronary blood flow, respectively. Coronary blood flow was measured from hearts isolated from 16‐week‐old control Db/db and diabetic db/db mice and perfused on a Langendorff system at a constant pressure of 80 mmHg. Latrunculin B (1 μM final concentration; n=2 per group) was infused to depolymerize actin and reduce vascular cell stiffness and jasplakinolide (0.2 μM final concentration; n=4 per group) was infused to increase actin polymerization and increase vascular cell stiffness. After drug infusions, hearts were immediately transferred to an adjacent Langendorff apparatus and were perfusion fixed with 4% paraformaldehyde for 2 mins at 1 mL/min. Hearts were then placed in 4% PFA for 24–48 hours and were stored in 70% EtOH until embedding in paraffin and sectioning. Sections were evaluated for F‐ and G‐actin by immunofluorescence. In pooled Db/db and db/db analyses, Latrunculin B caused an increase in coronary blood flow over baseline (34.1 ± 15.0% above baseline, n=7), and jasplakinolide caused a 26.5 ± 4.1% reduction in coronary blood flow from baseline (n=8). Immunohistochemical analysis confirmed a decreased trend in F/G actin in the coronary microvessels of latrunculin B‐perfused hearts (1.00 vs. 0.82 ± 0.08, n=1–4 per group), while F/G actin tended to be increased in the CRMs of jasplakinolide‐perfused hearts (1.00 ± 0.00 vs. 1.50 ± 0.16, p=0.12, n=2–6 per group). Importantly, the F/G actin ratio in jasplakinolide‐treated hearts was not different measured in the myocardium 50–100 μm away from a CRM (1.00 ± 0.06 in vehicle‐perfused hearts vs. 1.01 ± 0.10 in jasplakinolide‐perfused hearts, p=0.96, n=2–6 per group), demonstrating that the drug was efficacious only in the peri‐vascular region. These data support the hypothesis that coronary blood flow increases as vascular cell stiffness is decreased and coronary blood flow decreases as vascular cell stiffness is increased. Collectively, these data suggest that coronary vascular cell stiffness can modulate coronary blood flow.Support or Funding InformationKRM was supported by an American Heart Association Summer Undergraduate Research Fellowship (17UFEL33420025). NIH R00HL116769, R21EB026518, and S10OD023438 to AJT.

Vasospastic angina: pathophysiology and clinical significance

The review discusses an analysis of the literature on various aspects of the pathogenesis, diagnosis and treatment of vasospastic angina (VA). Data on the prevalence of coronary artery spasm (CAS) in various populations, as well as risk factors and triggers, are presented. We considered pathophysiological mechanisms of CAS, including hyperreactivity of coronary smooth muscle cells, endothelial dysfunction, nonspecific inflammation, oxidative stress, magnesium deficiency, autonomic imbalance, etc. The relationship of CAS with coronary atherosclerosis and thrombosis is emphasized. Modern recommendations for the diagnosis and treatment of VA are presented. Invasive verification of CAS is performed by pharmacological provocation tests with certain contraindications. Calcium antagonists and their combination with long-acting nitrates play a key role in the treatment of VA. Medications with a prospect for use in VA are Rho-kinase inhibitors, ATP-sensitive potassium channel activators, alpha-1 blockers. The management of patients with refractory VA and the prospects for endovascular treatment are discussed. It was noted that patients with multi-vessel VA are more likely to develop life-threatening arrhythmias and sudden death.

Vasospastic angina: pathophysiology and clinical significance

The review discusses an analysis of the literature on various aspects of the pathogenesis, diagnosis and treatment of vasospastic angina (VA). Data on the prevalence of coronary artery spasm (CAS) in various populations, as well as risk factors and triggers, are presented. We considered pathophysiological mechanisms of CAS, including hyperreactivity of coronary smooth muscle cells, endothelial dysfunction, nonspecific inflammation, oxidative stress, magnesium deficiency, autonomic imbalance, etc. The relationship of CAS with coronary atherosclerosis and thrombosis is emphasized. Modern recommendations for the diagnosis and treatment of VA are presented. Invasive verification of CAS is performed by pharmacological provocation tests with certain contraindications. Calcium antagonists and their combination with long-acting nitrates play a key role in the treatment of VA. Medications with a prospect for use in VA are Rho-kinase inhibitors, ATP-sensitive potassium channel activators, alpha-1 blockers. The management of patients with refractory VA and the prospects for endovascular treatment are discussed. It was noted that patients with multi-vessel VA are more likely to develop life-threatening arrhythmias and sudden death.

Vasospastic angina: pathophysiology and clinical significance

The review discusses an analysis of the literature on various aspects of the pathogenesis, diagnosis and treatment of vasospastic angina (VA). Data on the prevalence of coronary artery spasm (CAS) in various populations, as well as risk factors and triggers, are presented. We considered pathophysiological mechanisms of CAS, including hyperreactivity of coronary smooth muscle cells, endothelial dysfunction, nonspecific inflammation, oxidative stress, magnesium deficiency, autonomic imbalance, etc. The relationship of CAS with coronary atherosclerosis and thrombosis is emphasized. Modern recommendations for the diagnosis and treatment of VA are presented. Invasive verification of CAS is performed by pharmacological provocation tests with certain contraindications. Calcium antagonists and their combination with long-acting nitrates play a key role in the treatment of VA. Medications with a prospect for use in VA are Rho-kinase inhibitors, ATP-sensitive potassium channel activators, alpha-1 blockers. The management of patients with refractory VA and the prospects for endovascular treatment are discussed. It was noted that patients with multi-vessel VA are more likely to develop life-threatening arrhythmias and sudden death.

BNC1: A master regulator of human epicardial heterogeneity and function

The epicardium is a heterogeneous cell layer covering the heart. During cardiogenesis, epicardium-derived cells migrate into developing myocardium, yielding cardiac fibroblasts and coronary smooth muscle cells (CoSMC). Mammalian epicardium is quiescent in adulthood but reactivates post-injury with limited functionality. Of note, in zebrafish post-myocardial injury, effective epicardial signaling enables cardiac regeneration. We hypothesize that manipulating human epicardial composition and function could benefit therapeutic heart regeneration, via reactivating epicardial embryonic processes that enable cardiac development.

Functional Heterogeneity within the Developing Zebrafish Epicardium

SummaryThe epicardium is essential during cardiac development, homeostasis, and repair, and yet fundamental insights into its underlying cell biology, notably epicardium formation, lineage heterogeneity, and functional cross-talk with other cell types in the heart, are currently lacking. In this study, we investigated epicardial heterogeneity and the functional diversity of discrete epicardial subpopulations in the developing zebrafish heart. Single-cell RNA sequencing uncovered three epicardial subpopulations with specific genetic programs and distinctive spatial distribution. Perturbation of unique gene signatures uncovered specific functions associated with each subpopulation and established epicardial roles in cell adhesion, migration, and chemotaxis as a mechanism for recruitment of leukocytes into the heart. Understanding which mechanisms epicardial cells employ to establish a functional epicardium and how they communicate with other cardiovascular cell types during development will bring us closer to repairing cellular relationships that are disrupted during cardiovascular disease.

Plasma circular RNA hsa_circ_0001445 and coronary artery disease: Performance as a biomarker.

The role of circular RNAs (circRNAs) as biomarkers remains poorly characterized. Here, we investigated the performance of the circRNA hsa_circ_0001445 as a biomarker of coronary artery disease (CAD) in a real-world clinical practice setting. Plasma hsa_circ_0001445 was measured in a study population of 200 consecutive patients with suspected stable CAD who had undergone coronary computed tomographic angiography (CTA). Multivariable logistic models were constructed combining conventional risk factors with established biomarkers and hsa_circ_0001445. Model robustness was internally validated by the bootstrap technique. Biomarker accuracy was evaluated using the C-index. The integrated discrimination improvement (IDI) and net reclassification improvement (NRI) were also calculated. Risk groups were developed via classification tree models. The stability of plasma hsa_circ_0001445 was evaluated under different clinical conditions. hsa_circ_0001445 levels were associated with higher coronary atherosclerosis extent and severity with a 2-fold increase across tertiles (28.4%-50.0%). Levels of hsa_circ_0001445 were proportional to coronary atherosclerotic burden, even after comprehensive adjustment for cardiovascular risk factors, medications, and established biomarkers (fully adjusted OR=0.432 for hsa_circ_0001445 as a continuous variable and fully adjusted OR=0.277 for hsa_circ_0001445 as a binary variable). The classification of patients was improved with the incorporation of hsa_circ_0001445 into a base clinical model (CM) composed of conventional cardiovascular risk factors, showing an IDI of 0.047 and NRI of 0.482 for hsa_circ_0001445 as a continuous variable and an IDI of 0.056 and NRI of 0.373 for hsa_circ_0001445 as a binary variable. A trend toward higher discrimination capacity was also observed (C-indexCM =0.833, C-indexCM+continuous hsa_circ_0001445 =0.856 and C-indexCM+binary hsa_circ_0001445 =0.855). Detailed analysis of stability showed that hsa_circ_0001445 was present in plasma in a remarkably stable form. In vitro, hsa_circ_0001445 was downregulated in extracellular vesicles secreted by human coronary smooth muscle cells upon exposure to atherogenic conditions. In patients with suspected stable CAD referred for coronary CTA, plasma hsa_circ_0001445 improves the identification of coronary artery atherosclerosis.

Binding of myeloperoxidase to the extracellular matrix of smooth muscle cells and subsequent matrix modification

The extracellular matrix (ECM) of tissues is susceptible to modification by inflammation-associated oxidants. Considerable data support a role for hypochlorous acid (HOCl), generated by the leukocyte-derived heme-protein myeloperoxidase (MPO) in these changes. HOCl can modify isolated ECM proteins and cell-derived matrix, with this resulting in decreased cell adhesion, modulated proliferation and gene expression, and phenotypic changes. Whether this arises from free HOCl, or via site-specific reactions is unresolved. Here we examine the mechanisms of MPO-mediated changes to human coronary smooth muscle cell ECM. MPO is shown to co-localize with matrix fibronectin as detected by confocal microscopy, and bound active MPO can initiate ECM modification, as detected by decreased antibody recognition of fibronectin, versican and type IV collagen, and formation of protein carbonyls and HOCl-mediated damage. These changes are recapitulated by a glucose/glucose oxidase/MPO system where low continuous fluxes of H2O2 are generated. HOCl-induced modifications enhance MPO binding to ECM proteins as detected by ELISA and MPO activity measurements. These data demonstrate that MPO-generated HOCl induces ECM modification by interacting with ECM proteins in a site-specific manner, and generates alterations that increase MPO adhesion. This is proposed to give rise to an increasing cycle of alterations that contribute to tissue damage.

Role of Orai1 and L-type CaV1.2 channels in Endothelin-1 mediated coronary contraction under ischemia and reperfusion

Ischemia and Reperfusion (I/R) injuries are associated with coronary artery hypercontracture. They are mainly originated by an exacerbated response to agonists released by endothelium such as Endothelin (ET-1), involving the alteration in intracellular calcium handling. Recent evidences have highlighted the implication of Store-Operated Calcium Channels (SOCC) in intracellular calcium homeostasis in coronary artery. However, little is known about the role of SOCC in the regulation of coronary vascular tone under I/R.The aim of this study was to evaluate the role of SOCC and l-type Ca2+ channels (LTCC) in coronary artery vasoconstriction originated by ET-1 in I/R. We used Left Anterior Descendent coronary artery (LAD) rings, isolated from Wistar rats, to study the contractility and intracellular Ca2+ concentration ([Ca2+]i) under a simulated I/R protocol. We observed that responses to high-KCL induced depolarization and caffeine-induced Ca2+ release are attenuated in coronary artery under I/R. Furthermore, ET-1 addition in ischemia promotes transient and small rise of [Ca2+]i and coronary vascular tone. Meanwhile, these effects are significantly potentiated during reperfusion. The resulting ET-1-induced vasoconstrictions and [Ca2+]i increase were abolished by; GSK-7975A and gadolinium, inhibitors of SOCC; and nifedipine a widely used inhibitor of LTCC. Interestingly, using in situ Proximity Ligation Assay (PLA) in isolated coronary smooth muscle cells we found significant colocalization of LTCC CaV1.2 isoform with Orai1, the pore forming subunit of SOCC, and TRPC1 under I/R.Our data suggest that hypercontraction of coronary artery induced by ET-1 after I/R involves the co-activation of LTCC and SOCC, which colocalize significantly in the sarcolemma of coronary smooth muscle cells.

The Diagnostic Criteria 2020 for Triglyceride Deposit Cardiomyovasculopathy.

Triglyceride deposit cardiomyovasculopathy (TGCV) is a newly identified disease that was discovered in individuals who required cardiac transplantation in Japan in 2008. Defective intracellular lipolysis causes triglyceride (TG) accumulation in the myocardium and coronary artery vascular smooth muscle cells, which results in severe heart failure and coronary artery disease with poor prognosis. A known cause of TGCV is a genetic deficiency of adipose triglyceride lipase (ATGL), a rate-limiting enzyme in the intracellular hydrolysis of TG. TGCV is classified into primary TGCV with ATGL mutations and idiopathic TGCV without ATGL mutations. Since its discovery, the Japan TGCV Study Group has attempted to elucidate its pathophysiology, develop diagnostic procedures, and specific treatment. Myocardial scintigraphy with iodine-123-β-methyl iodophenyl-pentadecanoic acid (123I-BMIPP) is a unique imaging modality for evaluating myocardial lipolysis in vivo. The washout rate of 123I-BMIPP is an essential indicator for the diagnosis of TGCV. Along with our efforts to provide awareness of and insights into this disease concept, we found that the cumulative number of clinically diagnosed patients has reached >200 and the cases are distributed throughout Japan. In addition, we successfully completed three investigator-initiated clinical trials of a potential therapeutic agent (CNT-01) for TGCV, which was assigned by the Ministry of Health, Labour, and Welfare, Japan, under the SAKIGAKE Designation System in June 2020. Here, we provide the Diagnostic Criteria 2020 for TGCV in order to further promote this "rare and intractable disease" project.

Immunization with the Gly1127-Cys1140 amino acid sequence of the LRP1 receptor reduces atherosclerosis in rabbits. Molecular, immunohistochemical and nuclear imaging studies.

Background: The LRP1 (CR9) domain and, in particular, the sequence Gly1127-Cys1140 (P3) plays a critical role in the binding and internalization of aggregated LDL (agLDL). We aimed to evaluate whether immunization with P3 reduces high-fat diet (HFD)-induced atherosclerosis.Methods: Female New Zealand White (NZW) rabbits were immunized with a primary injection and four reminder doses (R1-R4) of IrP (irrelevant peptide) or P3 conjugated to the carrier. IrP and P3-immunized rabbits were randomly divided into a normal diet group and a HFD-fed group. Anti-P3 antibody levels were determined by ELISA. Lipoprotein profile, circulating and tissue lipids, and vascular pro-inflammatory mediators were determined using standardized methods while atherosclerosis was determined by confocal microscopy studies and non-invasive imaging (PET/CT and Doppler ultrasonography). Studies treating human macrophages (hMΦ) and coronary vascular smooth muscle cells (hcVSMC) with rabbit serums were performed to ascertain the potential impact of anti-P3 Abs on the functionality of these crucial cells.Results: P3 immunization specifically induced the production of anti-P3 antibodies (Abs) and did not alter the lipoprotein profile. HFD strongly induced cholesteryl ester (CE) accumulation in the aorta of both the control and IrP groups, and their serum dose-dependently raised the intracellular CE of hMΦ and hcVSMC, promoting TNFR1 and phospho-NF-kB (p65) overexpression. These HFD pro-inflammatory effects were dramatically decreased in the aorta of P3-immunized rabbits and in hMΦ and hcVSMC exposed to the P3 rabbit serums. Microscopy studies revealed that P3 immunization reduced the percentage of lipids, macrophages, and SMCs in the arterial intima, as well as the atherosclerotic extent and lesion area in the aorta. PET/CT and Doppler ultrasonography studies showed that the average standardized uptake value (SUVmean) of the aorta and the arterial resistance index (ARI) of the carotids were more upregulated by HFD in the control and IrP groups than the P3 group.Conclusions: P3 immunization counteracts HFD-induced fatty streak formation in rabbits. The specific blockade of the LRP1 (CR9) domain with Anti-P3 Abs dramatically reduces HFD-induced intracellular CE loading and harmful coupling to pro-inflammatory signaling in the vasculature.

Decreased inward rectifier and voltage-gated K+ currents of the right septal coronary artery smooth muscle cells in pulmonary arterial hypertensive rats.

In vascular smooth muscle, K+ channels, such as voltage-gated K+ channels (Kv), inward-rectifier K+ channels (Kir), and big-conductance Ca2+-activated K+ channels (BKCa), establish a hyperpolarized membrane potential and counterbalance the depolarizing vasoactive stimuli. Additionally, Kir mediates endothelium-dependent hyperpolarization and the active hyperemia response in various vessels, including the coronary artery. Pulmonary arterial hypertension (PAH) induces right ventricular hypertrophy (RVH), thereby elevating the risk of ischemia and right heart failure. Here, using the whole-cell patch-clamp technique, we compared Kv and Kir current densities (IKv and IKir) in the left (LCSMCs), right (RCSMCs), and septal branches of coronary smooth muscle cells (SCSMCs) from control and monocrotaline (MCT)-induced PAH rats exhibiting RVH. In control rats, (1) IKv was larger in RCSMCs than that in SCSMCs and LCSMCs, (2) IKv inactivation occurred at more negative voltages in SCSMCs than those in RCSMCs and LCSMCs, (3) IKir was smaller in SCSMCs than that in RCSMCs and LCSMCs, and (4) IBKCa did not differ between branches. Moreover, in PAH rats, IKir and IKv decreased in SCSMCs, but not in RCSMCs or LCSMCs, and IBKCa did not change in any of the branches. These results demonstrated that SCSMC-specific decreases in IKv and IKir occur in an MCT-induced PAH model, thereby offering insights into the potential pathophysiological implications of coronary blood flow regulation in right heart disease. Furthermore, the relatively smaller IKir in SCSMCs suggested a less effective vasodilatory response in the septal region to the moderate increase in extracellular K+ concentration under increased activity of the myocardium.

Matrine pre-treatment suppresses AGEs- induced HCSMCs fibrotic responses by regulating Poldip2/mTOR pathway

The fibrotic response of vascular smooth muscle cells (VSMCs) takes responsibilities in atherosclerosis. Advanced glycation end products (AGEs) induce and promote the fibrotic responses of VSMCs. Matrine shows potent anti-fibrotic and cardio-protective effects. This study was aimed to investigate the underlying mechanisms of matrine's inhibitory effects on AGEs-induced VSMCs fibrotic responses. Cultured human coronary smooth muscle cells (HCSMCs) were pre-treated with matrine and exposed to AGEs. Specific siRNA was used to silence polymerase delta interacting protein 2 (Poldip2) expression. Sircol collagen assay was used to assess collagen content. Protein expression and phosphorylation levels were determined by Western blotting. Matrine pre-treatment significantly reduced collagen content, increased smooth muscle myosin heavy chain 11 (MYH11) and Poldip2 expression, decreased expressions of collagen I, β1-integrin, phsphoinositide-3-kinase (PI3K) and nuclear phosphorylated p70S6k, and reduced phosphorylation levels of protein kinase B (Akt) and mechanistic target of rapamycin (mTOR) in HCSMCs exposed to AGEs in a concentration dependent manner. Specific siRNA effectively silenced Poldip2 expression and impaired matrine's effect on collagen content, expressions of MYH11, collagen I, β1-integrin, PI3K, nuclear p-p70S6k and phosphorylation levels of Akt and mTOR in HCSMCs exposed to AGEs. Matrine suppresses AGEs- induced fibrotic responses in HCSMCs via regulating Poldip2/mTOR signaling pathway.

Activation of adenosine A2A but not A2B receptors is involved in uridine adenosine tetraphosphate-induced porcine coronary smooth muscle relaxation

Activation of both adenosine A2A and A2B receptors (A2BR) contributes to coronary vasodilation. We previously demonstrated that uridine adenosine tetraphosphate (Up4A) is a novel vasodilator in the porcine coronary microcirculation, acting mainly on A2AR in smooth muscle cells (SMC). We further investigated whether activation of A2BR is involved in Up4A-mediated coronary SMC relaxation. Both A2AR and A2BR may stimulate H2O2 production leading to activation of KATP channels in SMCs, we also studied the involvement of H2O2 and KATP channels in Up4A-mediated effect. Coronary small arteries dissected from the apex of porcine hearts were mounted on wire myograph for Up4A concentration responses. Up4A-induced coronary SMC relaxation was attenuated by A2AR but not A2BR antagonism or non-selective P2R antagonism, despite greater endogenous A2BR expression vs. A2AR in both coronary small arteries and primary cultured coronary SMCs. Moreover, Up4A-induced coronary SMC relaxation was blunted by H2O2 catabolism. This effect was not altered by KATP channel blockade. Combination of H2O2 catabolism and A2AR antagonism attenuated Up4A-induced coronary SMC relaxation to the similar extent as A2AR antagonism alone. Collectively, Up4A-induced porcine coronary SMC relaxation is mediated by activation of A2AR-H2O2 pathway. This process does not involve A2BR, P2R or KATP channels.

Effects of n-3 polyunsaturated fatty acid on store-operated calcium channels in coronary artery smooth muscle cells derived from diabetic rat

Objective: To investigate the impact of n-3 polyunsaturated fatty acid (n-3 PUFA) on function and expression of store-operated calcium channels (SOCC) in coronary artery smooth muscle cells (SMC) derived from diabetic rat. Methods: A total of 180 healthy male Sprague-Dawley (SD) rats were randomly divided into normal group (N, n=45), placebo-treated diabetic group (D, n=45), lose dose n-3 PUFA treated diabetic group (DL, n=45) and high dose n-3 PUFAs treated diabetic group (DH, n=45). Streptozotocin-induced diabetic rat animal model was established by two consecutive intraperitoneal injections. After modeling, rats in group DL and DH were treated with 10 mg·kg(-1)·d(-1) and 50 mg·kg(-1)·d(-1) n-3 PUFAs respectively per gavage for eight weeks. After eight weeks, rat coronary artery SMC was isolated by enzyme digestion. Changes of cytosolic calcium concentration in coronary artery SMC were examined by calcium fluorescence imaging technique, coronary artery tension was detected by myograph system, and protein expressions of SOCC on coronary artery SMC were measured by Western blot. Results: SOCC induced ΔF340/F380 of group N, D, DL and DH were 0.425±0.023, 0.838±0.037, 0.342±0.052 and 0.364±0.045 respectively, which was significantly lower in group N, DL, DH than in group D (P<0.05). SOCC induced changes of tensions were 0.94±0.09, 1.95±0.18, 1.35±0.24 and 1.01±0.18 in the group N, D, DL and DH, respectively, which was significantly lower in group N and DH than in group D (P<0.05). Protein expressions of STIM1, Orai1 and TRPC1 were significantly higher in diabetic rat coronary SMC than in group N (P<0.05). STIM1 protein expressions were significantly lower in group DL and DH than in group D, and Orai1 and TRPC1 protein expressions were similar among group. Conclusions: Coronary artery tension, cytosolic calcium concentration and protein expressions of SOCC are higher in diabetic rat coronary artery SMC when compared with normal rats. n-3 PUFA intervention could downregulate the protein expression of SOCC, reduce cytosolic calcium concentration and coronary artery tension, and is protective to the diabetic injury in coronary artery.