Intimal Smooth Muscle Cells Research Articles

Abstract 13838: Smooth Muscle Cells Are the Origin of the Majority of Foam Cells in Atherosclerotic Lesions of Apolipoprotein E-deficient Mice

Background: Apolipoprotein E-deficient (ApoE -/- ) mice are the most frequently used model of human atherosclerosis. Foam cells in mouse lesions have been believed to be primarily macrophage-derived using traditional staining with macrophage markers. Recent studies indicated that smooth muscle cells (SMCs) comprise at least 50% of foam cells in human coronary atherosclerosis, and express reduced levels of ATP-binding cassette transporter A1 (ABCA1) when compared to intimal leucocytes. Identification of SMC-derived foam cells is challenging due to the absence of classic SMC markers and expression of macrophage markers by a high percentage of intimal SMCs in mouse and human lesions. Hypothesis: Unlike human atherosclerosis, foam cells in ApoE -/- mice are primarily macrophage- rather than SMC-derived. Methods: 8-week-old male and female ApoE -/- mice were fed a Western diet for 6 weeks to promote lesion development. Flow cytometry was used to estimate the proportion of leukocyte- and SMC-derived foam cells in cell suspensions from digested ascending aortas. Foam cells were identified by the neutral lipid dye BODIPY, and leukocyte-derived were distinguished from SMC-derived foam cells by expression of CD45 (a pan-leukocyte marker), and I-A/I-E (antigen presenting cell markers), which have not been reported to be expressed by SMCs. SMC origin was confirmed using a SMC-specific epigenetic lineage marker. ABCA1 level was also measured in the two foam cell populations. Results: 69.47±3.20 % (male) and 73.33±2.35 % (female) (mean ± SEM, n=9 each) of foam cells in ApoE -/- mouse lesions were CD45 and I-A/I-E negative, and were confirmed by SMC lineage marker to be predominantly SMC-derived. SMC-derived foam cells were thus significantly greater than leukocyte-derived foam cells in ApoE -/- mice ( P <0.01), and exhibited three times lower ABCA1 protein than leukocyte-derived foam cells in both sexes. Conclusions: Contrary to our hypothesis, SMCs contribute the majority of foam cells in ApoE -/- mouse atherosclerosis. Impaired ABCA1 expression in SMC foam cells, as seen in human intimal SMC foam cells, suggests a likely mechanism for preferential SMC foam cell development in both species, and a potential target for atherosclerosis treatment and prevention.

A20 Haploinsufficiency Aggravates Transplant Arteriosclerosis in Mouse Vascular Allografts: Implications for Clinical Transplantation.

Inflammation is central to the pathogenesis of transplant arteriosclerosis (TA). We questioned whether physiologic levels of anti-inflammatory A20 influence TA severity. We performed major histocompatibility complex mismatched aorta to carotid artery interposition grafts, using wild type (WT) or A20 heterozygote (HET) C57BL/6 (H-2) donors and BALB/c (H-2) recipients, and conversely BALB/c donors and WT/HET recipients. We analyzed aortic allografts by histology, immunohistochemistry, immunofluorescence, and gene profiling (quantitative real-time reverse-transcriptase polymerase chain reaction). We validated select in vivo A20 targets in human and mouse smooth muscle cell (SMC) cultures. We noted significantly greater intimal hyperplasia in HET versus WT allografts, indicating aggravated TA. Inadequate upregulation of A20 in HET allografts after transplantation was associated with excessive NF-кB activation, gauged by higher levels of IkBα, p65, VCAM-1, ICAM-1, CXCL10, CCL2, TNF, and IL-6 (mostly localized to SMC). Correspondingly, cytokine-induced upregulation of TNF and IL-6 in human and mouse SMC cultures inversely correlated with A20 expression. Aggravated TA in HET versus WT allografts correlated with increased intimal SMC proliferation, and a higher number of infiltrating IFNγ and Granzyme B CD4 T cells and natural killer cells, and lower number of FoxP3 regulatory T cells. A20 haploinsufficiency in allograft recipients did not influence TA. A20 haploinsufficiency in vascular allografts aggravates lesions of TA by exacerbating inflammation, SMC proliferation, and infiltration of pathogenic T cells. A20 single nucleotide polymorphisms associating with lower A20 expression or function in donors of vascularized allografts may inform risk and severity of TA, highlighting the clinical implications of our findings.

Amendment of the cytokine profile in macrophages subsequent to their interaction with smooth muscle cells: Differential modulation by fractalkine and resistin

In atherosclerotic plaques, macrophages (MAC) and smooth muscle cells (SMC) frequently reside in close proximity and resistin (Rs) and fractalkine (Fk) are present at increased levels, resistin being associated with CD68 macrophages and fractalkine predominantly associated with intimal SMC; however, their role in this location is not clear, yet. The objective of this study was to determine whether the cross-talk between MAC-SMC induces changes in MAC cytokine phenotype and if Fk and Rs have a role in the process. To this purpose, macrophages (THP-1 monocytes differentiated with phorbol myristate acetate) were interacted with SMC cultured on the membrane inserts in the presence or absence of Rs or Fk. After 24h, MAC were removed from the co-culture and the gene and protein expression of 57 cytokines was assessed by QPCR and Proteome Profiler™ Array. Fk secreted in the culture medium following MAC-SMC interaction was determined (ELISA assay) and the role of Fk in MAC cytokine gene expression was assessed by silencing the Fk receptor in both cell types. The results showed that subsequent to the interaction with SMC, MAC exhibit: (1) a general increased expression of chemokines (the highest fold increase: VCC-1 and GRO-α) and of some interleukins, such as interleukins IL-5 (∼8-fold) and IL-6; (2) an increased Fk expression that in turn induces expression of: CXCL17, CCL19, CCL2, CXCL10, CXCL12, CXCL4, CXCL7, CCL4, CCL18, CXCL16, CXCL1 and IL-27; (3) in the presence of Rs, a predominant increased expression of interleukins (the highest fold increase: IL-6, IL-27, IL-23 and IL-5) and an augmented expression of some chemokines such as MIP-1β, GRO-α and CCL1. In addition, the secretome collected from the SMC-MAC co-culture increased human monocytes chemotaxis. DAVID analysis of the data revealed that the switch of MAC to a pro-inflammatory phenotype, prime the cells to intervene in the immune response, chemotaxis and inflammatory response. In conclusion, MAC cytokines expression is considerable augmented upon their interaction with SMC and Fk and Rs have distinct immunomodulatory roles: Fk predominantly increases the pro-angiogenic and inflammatory chemokines expression and Rs mostly the pro-inflammatory interleukins with consequences on monocyte chemotaxis. The novel data could help to develop targeted nanotherapies to reduce leukocyte chemotaxis and the ensuing inflammatory process associated with atherosclerosis.

Abstract 573: Vibrational Spectroscopy Discriminates Differentiated Vascular Smooth Muscle Cells From Mesenchymal Stem Cells and Their Vascular Progeny

Background: The source of intimal vascular smooth muscle cells (SMCs) following vascular remodelling has been controversial, with either de-differentiated SMCs and/or stem cell-derived SMCs playing a putative role. Fourier transform Infrared (FTIR) and Raman spectroscopy are complementary forms of vibrational spectroscopy which provide an excellent platform for extracting important biochemical data in a label-free manner to discriminate cell types. Aim: Determine whether native differentiated SMCs can be distinguished from mesenchymal stem cells (MSCs) and MSC-derived SMCs using vibrational spectroscopy. Methods: Freshly isolated rat aortic differentiated SMCs (up to passage 4), CD44+ bone marrow derived mesenchymal stem cells (MSCs), MSC-derived smooth muscle cells (mdSMCs - after TGF-β1 treatment for 14 d) and osteoblasts (mdOSTs - after osteogenic inductive stimulation for 21 d) were grown and fixed on calcium fluoride slides before their respective spectra were recorded by Raman and FTIR Spectroscopy. Multivariate statistical algorithms, including Principal Components Analysis (PCA) and Linear Discriminant Analysis (LDA), were applied to the spectra in order to classify the cell types based on their biochemical variation. Results: The recorded spectra for each cell type revealed significant visible differences between the cells across all recordings. The PCA score plot discriminated the cells based on their unique characteristics. A combination of PCA-LDA were applied for classification, and a leave one out cross validation resulted in sensitivities and specificities that were >95%. Conclusion: Vibrational spectroscopy discriminates differentiated SMCs from MSC and their vascular progeny and may be useful for identifying these cells as early biomarkers of disease.

Nuclear PTEN functions as an essential regulator of SRF-dependent transcription to control smooth muscle differentiation.

Vascular disease progression is associated with marked changes in vascular smooth muscle cell (SMC) phenotype and function. SMC contractile gene expression and, thus differentiation, is under direct transcriptional control by the transcription factor, serum response factor (SRF); however, the mechanisms dynamically regulating SMC phenotype are not fully defined. Here we report that the lipid and protein phosphatase, PTEN, has a novel role in the nucleus by functioning as an indispensible regulator with SRF to maintain the differentiated SM phenotype. PTEN interacts with the N-terminal domain of SRF and PTEN–SRF interaction promotes SRF binding to essential promoter elements in SM-specific genes. Factors inducing phenotypic switching promote loss of nuclear PTEN through nucleo-cytoplasmic translocation resulting in reduced myogenically active SRF, but enhanced SRF activity on target genes involved in proliferation. Overall decreased expression of PTEN was observed in intimal SMCs of human atherosclerotic lesions underlying the potential clinical importance of these findings.

Periodontitis as a risk factor of atherosclerosis

Aim and objective: to do a review on periodontitis which is a risk factor of atherosclerosis. Background : periodontitis is the loss of gum attachment with the alveolar bone and resulting in the tooth loss. Pathogenesis of periodontal diseases is thought to be due to he accumulation of dental plaque along with the mucosal infection and inflammation. Atherosclerosis is a vascular diseases in which the artery thickens due to the accumulation of white blood cells and proliferation of intimal smooth muscle cells creating a fibro fatty plaque. Reason : to know about the several mechanisms by which the dental plaque associated periodontitis initiate or worsen the atherosclerosis .

Soluble LR11 is a novel biomarker for vascular lesions late after Kawasaki disease

ObjectiveCoronary artery lesions (CALs) and a risk for early onset of atherosclerosis are major concerns following Kawasaki disease (KD). Intimal smooth muscle cells (SMCs) have an important role in vascular lesions in KD. It is known that soluble LR11 (sLR11) is a novel biomarker for vascular lesions and LR11 is markedly expressed in intimal SMCs in atherosclerotic lesions. In this study, we hypothesized that sLR11 reflects the presence of vascular lesions late after KD. MethodsTwenty-three age-matched controls (group 1) and 59 patients with a history of KD were enrolled; 36 with KD had normal coronary arteries or regressed aneurysms (group 2), and 23 had CALs (group 3). ResultsSerum sLR11 levels in group 3 (median, interquartile range (IQR): 11.1 ng/mL, 9.3–13.9 ng/mL) were significantly higher than those in groups 1 (8.4 ng/mL, 7.1–10.2 ng/mL, p < 0.001) and 2 (9.0 ng/mL, 7.7–10.1 ng/mL, p < 0.01). Levels of sLR11 were positively correlated with levels of high-sensitivity C-reactive protein (r = 0.480, p < 0.01) and lipoprotein (a) (r = 0.486, p < 0.01). ConclusionThese findings suggest that sLR11 reflects the development of vascular lesions in patients with serious CALs.

Prognostic impact of circulating soluble LR11 on long-term clinical outcomes in patients with coronary artery disease

BackgroundLR11, a member of LDL receptor family, is a novel marker of the proliferation of intimal smooth muscle cells (SMCs). LR11 is released in soluble form (sLR11) by proteolytic shedding and has biological activity toward SMC migration. We previously showed that circulating sLR11 positively correlates with carotid intima-medial thickness (IMT) independently of classical atherosclerotic risk factors and that it significantly associates with the severity of CAD. However, the association between sLR11 and long-term clinical outcomes remain uncertain. Methods and resultsThis study included 438 consecutive patients (mean age, 65.8 ± 9.6 y; male, 82.4%) who underwent coronary intervention between March 2003 and December 2004 at our institution. The patients were assigned to quartiles according to pre-procedural sLR11 values. The primary endpoints were composite cardiovascular disease (CVD) endpoints including cardiovascular death, non-fatal acute coronary syndrome and non-fatal stroke. During median follow-up of 2876 days, composite CVD endpoints occurred 97 (22.1%) patients including 41 (9.4%) with cardiovascular disease (CVD)-related death, 36 (8.2%) non-fatal ACS and 20 (4.6%) non-fatal strokes. The hazard ratio (HR) for composite CVD endpoints significantly and dose-dependently increased with sLR11 levels (p for trend = 0.0077). A higher logarithm-transformed sLR11 value was associated with a greater risk of composite CVD endpoints, and the increased number of adverse long-term clinical outcomes persisted even after adjustment for other independent variables (HR 1.87 95%CI 1.02–3.31, p = 0.0435). ConclusionsElevated sLR11 levels were significantly associated with higher long-term adverse cardiac events in patients with CAD. Further extensive studies are expected to elucidate the mechanistic role of sLR11 and its clinical value as a prognostic marker in the development of atherosclerosis.

Intimal smooth muscle cells are a source but not a sensor of anti-inflammatory CYP450 derived oxylipins

Vascular pathologies are associated with changes in the presence and expression of morphologically distinct vascular smooth muscle cells. In particular, in complex human vascular lesions and models of disease in pigs and rodents, an intimal smooth muscle cell (iSMC) which exhibits a stable epithelioid or rhomboid phenotype in culture is often found to be present in high numbers, and may represent the reemergence of a distinct developmental vascular smooth muscle cell phenotype. The CYP450-oxylipin - soluble epoxide hydrolase (sEH) pathway is currently of great interest in targeting for cardiovascular disease. sEH inhibitors limit the development of hypertension, diabetes, atherosclerosis and aneurysm formation in animal models. We have investigated the expression of CYP450-oxylipin-sEH pathway enzymes and their metabolites in paired intimal (iSMC) and medial (mSMC) cells isolated from rat aorta. iSMC basally released significantly larger amounts of epoxy-oxylipin CYP450 products from eicosapentaenoic acid > docosahexaenoic acid > arachidonic acid > linoleic acid, and expressed higher levels of CYP2C12, CYP2B1, but not CYP2J mRNA compared to mSMC. When stimulated with the pro-inflammatory TLR4 ligand LPS, epoxy-oxylipin production did not change greatly in iSMC. In contrast, LPS induced epoxy-oxylipin products in mSMC and induced CYP2J4. iSMC and mSMC express sEH which metabolizes primary epoxy-oxylipins to their dihydroxy-counterparts. The sEH inhibitors TPPU or AUDA inhibited LPS-induced NFκB activation and iNOS induction in mSMC, but had no effect on NFκB nuclear localization or inducible nitric oxide synthase in iSMC; effects which were recapitulated in part by addition of authentic epoxy-oxylipins. iSMCs are a rich source but not a sensor of anti-inflammatory epoxy-oxylipins. Complex lesions that contain high levels of iSMCs may be more resistant to the protective effects of sEH inhibitors.

Identification and characterization of intimal smooth muscle cell with innate immune capacity in atherosclerosis

Smooth muscle cells (SMC) contribute to the development and stability of atherosclerotic lesions. The phenotype transition and modulation of SMC is involved in many atherosclerotic pathological process. To date, more and more evidences indicated that innate immune response play important roles in atherosclerosis. As the first line of host defense and innate immunity, pathogen recognition receptors (PPR) have been shown to be involved in many mechanistic pathways in atherosclerosis. To investigate the role of innate immunity in SMC phenotype modulation in atherosclerosis, we analyzed PPR expression profile between different phenotypes of SMC and immune cells. Our data at the first time identified the high level of PPR expression in intimal SMC and characterized the comprehensive innate immune signatures. With comparison to other phenotypes of SMC and immune cells, we found intimal SMC possess a pro-inflammatory macrophage-like phenotype. To investigate the functional features and regulatory mechanism underlying the distinct phenotype, we used specific ligands for PRRs activation and showed that the innate immune capacity acquired by intimal SMC contribute to chemokine and cytokine secretion, migration promotion and extracellular matrix remodelling. Last but not least, we found the macrophage-like phenotype in intimal SMC and the pro-inflammatory capacity is associated with the elevated level of key transcription factors STAT1a, IRF8, IRF9, KLF4 and HIF2a. In conclusion, we propose a critical role of intimal SMC with innate immune capacity in the development of atherosclerosis. Targeting the phenotypic modulation of intimal SMC might be a new strategy for further clinical treatment.

Syndecan-1 is overexpressed during atherogenesis

During atherogenesis, smooth muscle cells (SMCs) undergo phenotypic modulation and migration into the intima. Like macrophages, intimal SMCs accumulate excess lipids and contribute to the foam cell population. Syndecan-1 is a transmembrane proteoglycan which can interact with lipoproteins and acts as a major receptor in triglyceride-rich lipoprotein clearance. Additionally, it has been shown to modulate SMCs phenotype and to affect the response to arterial injury, but its function in atherosclerosis is unknown. Our studies therefore aim to analyse syndecan-1 expression in human atheromatous tissue and its role in atherosclerosis development.

Abstract 357: Intimal Smooth Muscle Cells Are Vascular Tissue Specific Innate Immune Effector Cell

Intimal smooth muscle cells (SMC) represent the largest cell population in atherosclerotic plaques and restenotic lesions. These cells have multiple functions that differ from those of SMC of tunica media. Compared with medial SMC, intimal SMC are hyperresponsive to a large array of endogenous and exogenous inflammatory stimuli. However, the underlying molecular basis is elusive. Analyzing the phenotype of smooth muscle cells (SMC) isolated from balloon injury induced neointima of rat carotid artery, we found that unlike SMC of tunica media, the SMC of the intima exhibit an innate immune phenotype, characterized by constitutively expressing a broad panel of pathogen pattern recognition receptors (PRR) seen typically in macrophages. These PRR confer on intimal SMC an ability to react to an extensive list of microbial components by producing inflammatory mediators including nitric oxide, cytokines and chemokines. Additionally, intimal SMC produce the leukocyte chemokine CCL-5 (or RANTES) in the absence of exogenous stimuli, implying an intrinsic innate immune activity. The master program that determines the phenotype of intimal SMC remains to be defined but may involve a number of transcription pathways. These observations suggest that intimal SMC are vascular tissue specific innate immune effector cells with functions similar to those of macrophages.

Abstract 360: Reduction of Atherosclerotic Lesions by the Chemotherapeutic Agent Carmustine Associated to a Lipid Nanoemulsion

After injection in bloodstream, a lipid nanoemulsion (LDE) resembling low-density lipoprotein (LDL) concentrate in atherosclerotic lesions of cholesterol-fed rabbits. Here, rabbits with atherosclerosis were treated with carmustine, an antiproliferative agent used in cancer chemotherapy, associated to LDE to investigate the effects on the lesions. Eighteen male New Zealand rabbits were fed a 1% cholesterol diet for 8 weeks. After 4 weeks nine animals were treated intravenous saline solution and nine with intravenous LDE-carmustine (4 mg/kg, weekly for 4 weeks). LDE-carmustine inhibited atherosclerotic lesions by 90%, compared to controls. LDE-carmustine reduced presence of macrophages, smooth muscle cells, and regulatory T-cells in the arterial intima as well as the expression of matrix metallopeptidase-9, interleukin-1β and TNF-α and lipoprotein receptors (LDL receptor, LDL-related protein-1 and scavenger receptor class B member 1). In conclusion, LDE-carmustine treatment resulted in marked reduction of lesion area, invasion by macrophages and intimal smooth muscle cells and pro-inflammatory factors. Therefore, this new formulation shows great potential for therapy of atherosclerotic cardiovascular disease.

Abstract 140: Nuclear Targeting Apelin Induces Phenotypic Transition of Vascular Smooth Muscle Cells

Apelin, and its receptor APJ, are a peptidic system playing a crucial role in vascular diseases. However, the role of apelin in atherogenesis and smooth muscle cell (SMC) proliferation remains unclear. We isolated 2 distinct SMC phenotypes from porcine coronary artery: spindle-shaped (S) and rhomboid (R). Biological features of R-SMCs (i.e. enhanced proliferative and migratory activities as well as poor level of differentiation) explain their capacity to accumulate into the intima. We identified S100A4 as being a marker of the R-SMCs in vitro and of intimal SMCs, both in pig and human. The aim of our study was to investigate the effects of apelin on SMC phenotypic transition and S100A4 expression. Apelin was highly expressed in R-SMCs including in their nucleus. P-SORT software analysis of preproapelin sequence suggested that N-terminal truncated apelin may target the nucleus, and we confirmed this in SMCs by overexpression of mutated preproapelin-His-tag. Transfection of mutated preproapelin-His-tag encoding plasmid in differentiated S-SMCs induced a transition towards a R-phenotype associated with increased proliferative activity, downregulation of SMC differentiation markers, and increased nuclear expression and release of S100A4. In contrast, transfection of S-SMCs with wild type preproapelin-His-tag encoding plasmid did not induce nuclear targeting of apelin or S100A4, and did not change the S-phenotype. Stimulation of S-SMCs with PDGF-BB, known to induce a transition to the R-phenotype, yielded nuclear targeting of both apelin and S100A4. In vivo, Apelin was expressed in SMC nuclei of stent-induced intimal thickening while its expression in the media was mainly cytoplasmic. Our results suggest that nuclear targeting of apelin in SMCs acts on S100A4 expression and release, cell proliferation and differentiation. The pathophysiological consequences of this retargeting could be instrumental in the understanding of artherosclerosis.

Ultrasound microbubble-carried PNA targeting to c-myc mRNA inhibits the proliferation of rabbit iliac arterious smooth muscle cells and intimal hyperplasia

Objective: To elucidate the transfected effect of albumin ultrasound microbubbles carrying peptide nucleic acids (PNAs) against c-myc gene to the vascular walls and their effect on the intimal proliferation induced by vascular denudation.Methods: A rabbit iliac artery intimal proliferation model was constructed and PNA against c-myc mRNA was designed and synthesized and was added to albumin solution before ultrasound microbubbles were prepared and encapsulated in matrix of albumin. The ultrasound microbubbles carrying PNA were transfected to intima under ultrasound exposure. The transfected effect was identified by a histochemical method and the expression of c-myc was detected by in situ hybridization. The proliferation of intimal smooth muscle cells was estimated by the expression of proliferative cell nuclear antigen (PCNA) of them. The intimal area and thickness were judged morphologically for intimal hyperplasia.Results: The ultrasound microbubbles with PNA were successfully prepared and c-myc PNA was transfected to vascular intimal cells. The expression of c-myc and PCNA by intimal vascular smooth muscle cells (vSMCs) was inhibited significantly and the intimal thickness and area were reduced remarkably.Conclusion: Transfection of c-myc PNA could inhibit proliferartion of vSMCs and intima in the rabbit iliac artery intimal proliferation model and the targeted transfection of albumin ultrasound microbubbles carrying PNA offers a feasible way to facilitate its access to specific cells in vivo and produce bioavailability.

LR11 PLAYS A PIVOTAL ROLE IN PULMONARY A ARTERIAL HYPERTENSION

This study examined low-density lipoprotein receptor relative with 11 binding repeats (sLR11) plays a pivotal role in pulmonary arterial hypertension (PAH). LR11 (also called SorLA or SORL1), is a low-density lipoprotein (LDL)-receptor that is expressed in intimal smooth muscle cells during the

Connexins and intercellular communication in arterial growth and remodeling

Gap junction functionality and intercellular exchange of chemical messengers and other biologically important cellular signals makes communication between adjacent cells possible and is essential for multicellular living systems. This intercellular communication is carried out through gap junction channels that are comprised of multimeric connexin (Cx) proteins and that provide physical linkages between neighboring cells. This Cx-specific gap junction intercellular communication (GJIC) helps perform numerous essential physiological functions in different organ systems. In vascular tissues, reciprocal GJIC between intimal vascular endothelial cells (VECs) and medial vascular smooth muscle cells (VSMCs) helps to control blood flow and arterial pressures by signaling contraction or relaxation events. In the vascular system appropriate GJIC also regulates responses to circulating hormones and other vasoactive factors as well as growth during episodes of stimulated angiogenesis and/or vasculogenesis. Deleterious GJIC, however, serves as a contributing element in vascular pathologies and plays key roles in abnormal vascular cell proliferation, migration, and inflammation, foundational mechanisms of arterial remodeling and neointima development. In this review we discuss the critical roles of vascular gap junction Cx proteins and GJIC in regulating pathologic arterial remodeling.

Circulating soluble LR11, a novel marker of smooth muscle cell proliferation, is enhanced after coronary stenting in response to vascular injury

ObjectiveRestenosis after vascular intervention remains a major clinical problem. Circulating LR11 has been shown a novel marker of intimal smooth muscle cell (SMC) proliferation in human and animal studies. The present study was performed to clarify the clinical significance of circulating LR11 in patients with stable angina pectoris after coronary stenting. Methods and resultsWe firstly investigated the circulating sLR11 levels for 28 days after arterial injury in mice, and then assessed time-dependent change in circulating sLR11 level after coronary stenting in a clinical study. Mouse sLR11 levels rapidly increased to 4.0-fold of the control value without cuff placement at postoperative day (POD) 14, and the levels gradually declined to 3.1-fold of the control value until POD 28 in mice. The circulating soluble LR11 levels were measured (before and at 14, 60 and 240 days after coronary stenting in a clinical study of 102 consecutive patients with stable angina pectoris who were treated with percutaneous coronary intervention. Circulating sLR11 levels were significantly increased on days 14 and 60 after the procedure and positively associated with the angiographic late loss index. ConclusionsOur study suggested that circulating sLR11 levels may be a potential marker for angiographic late loss in patients after coronary stenting. Further mechanistic studies are expected to know the clinical significance of sLR11 as a novel marker for intimal SMC.

Inverse expression of estrogen receptor alpha and apolipoprotein B in coronary intimal hyperplasia of surgically repaired congenital heart disease: A pre-atherosclerotic condition?

Congenital heart diseases (CHD) or the process of their repair leads to an increased risk for adult cardiovascular disease compared with the general population [1]. The proliferation of intimal smooth muscle cells (SMCs), which causes intimal thickenings prior to any evidence of visible lipid deposition, was proposed to be the initial lesion of coronary atherosclerosis [2]. The increasing trend to consider intimal thickenings as possible pre-atherosclerotic lesions is based on the distribution of intimal hyperplasia in children and the localization of characteristic atherosclerotic lesions observed in adult humans [3].

Serum and glucocorticoid-regulated kinase 1 promotes vascular smooth muscle cell proliferation via regulation of β-catenin dynamics

In response to arterial intimal injury vascular smooth muscle cells (VSMCs) within the vessel wall proliferate upon exposure to growth factors, accumulate, and form a neointima that can occlude the vessel lumen. Serum and glucocorticoid inducible kinase 1 (SGK1) is a growth factor-responsive kinase; however its role in VSMC proliferation is not fully understood. Here, we examined growth factor-dependent regulation of SGK1 and defined a molecular role for SGK1 in stimulation of VSMC proliferation. We found that stimulation of VSMCs with the pro-proliferative growth factor, platelet-derived growth factor BB (PDGF) significantly increased SGK1 mRNA, protein, and kinase activity in aortic VSMCs in vitro. To test the hypothesis that activation of SGK1 activity promotes VSMC proliferation, we examined the effects of stable expression of constitutively active (S422D) and kinase-defective (S422A) mutants of SGK1 on VSMC growth. We found that activation of SGK1 increased, whereas interference of SGK1 signaling inhibited VSMC growth in vitro. Consistent with these findings, expression of the S422D mutant augmented both basal and PDGF-induced BrdU uptake in VSMCs. Conversely, PDGF-induced BrdU uptake was attenuated in VSMCs expressing S422A. Furthermore, we determined that activated SGK1 enhanced basal and PDGF-dependent G1→S cell cycle transition, whereas dominant-negative SGK1 abrogated G1→S cell cycle transition under similar conditions. Downstream signaling by active SGK1 induced basal and PDGF-induced phosphorylation of glycogen synthase kinase 3β, an effect which was attenuated when SGK1 activity was blocked by expression of the kinase-defective mutant, S422A. We also found that transfection of S422D enhanced β-catenin-nuclear localization and activation of the TOP/Flash and cyclin D1 transcriptional reporters. These effects were significantly blunted in VSMCs transfected with the S422A mutant. Our results provide compelling evidence of a role for SGK1 in stimulation of arterial VSMC growth via regulation of β-catenin dynamics and implicate SGK1 in the progression of intimal narrowing following arterial injury. Hence, the findings presented here point to inhibition of SGK1 activity as a novel therapeutic approach for the treatment of occlusive vascular diseases.