Medial Smooth Muscle Cells Research Articles

Eosinophilic Coronary Periarteritis: A New Type of Coronary Arteritis as a Cause of Vasospastic Angina and Sudden Death

Eosinophilic coronary periarteritis (ECPA) has been recently established as a new pathological entity and clinically showed a vasospastic angina and sudden cardiac death (SCD). The patients were relatively young (mainly 30 to 50 years old) and predominantly male. The characteristic clinical findings of this disease include a) vasospastic angina (Prinzmetal’s variant angina) appearing usually from evening to early in the morning, b) all patients experienced SCD early in the morning, and c) allergy or history of allergy was hard to identify in the patients with this disease. Histological findings include a) eosinophilic inflammatory infiltration limited to the adventitia and periadventitial soft issue is recognized in the epicardial large coronary arteries, b) all 3 main coronary artery branches are affected, with the left anterior descending artery most frequently affected, c) medial smooth muscle cells of the affected coronary artery and both internal and elastic laminae are well preserved, d) fibrinoid necrosis or granuloma as seen in polyarteritis nodosa or allergic granulomatous angina are not found in or around the inflammatory area, and e) no findings of any type of vasculitis in any other tissues or organs (i.e., localized or non-systemic periarteritis). Spontaneous coronary artery dissection (SCAD) is frequently accompanied by eosinophilic inflammatory infiltration limited to the adventitia and periadventitial soft issue in the dissected portion of the epicardial coronary arteries, i.e., same as the findings of ECPA, and the patients usually die suddenly. A considerable number of patients with this disease will be included among patients suffering from vasospastic angina. Therefore, it is very important for cardiologists to make a precise diagnosis of and provide adequate treatment for this disease.

Lipid-lowering and antiatherosclerotic effect of NK-104, a potent 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, in Watanabe heritable hyperlipidemic rabbits.

NK-104 ((+)-monocalcium bis(3R,5S,6E)-7-[2-cyclopropyl-4-(4-fluorophenyl)-3-quinolyl]-3,5-dihydroxy- 6-heptenoate), CAS 147526-32-7) an inhibitor of 3-hydroxy-3-metylglutaryl coenzyme A reductase, was administered in drinking water (0.5 mg/kg equivalent) to Watanabe heritable hyperlipidemic (WHHL) rabbits for 26 weeks. It lowered plasma total cholesterol (TC, 7-20%) and triglyceride (TG, 16-39%) levels throughout the experimental period due to a significant reduction of very low density lipoprotein cholesterol (VLDL-C, 61-62%, p < 0.05), intermediate density lipoprotein cholesterol (IDL-C, 49-60%, p < 0.05), VLDL-TG (40-53%, p = 0.06-0.08) and IDL-TG (29-59%, p = 0.06-0.14); low density lipoprotein cholesterol (LDL-C) was not affected. The pattern of the lipoprotein reduction along with a decrease in liver cholesteryl ester (CE, 33.1%, p < 0.01) suggests an intense reduction of VLDL secretion and a marginal induction of LDL-receptor. Enhanced expression of LDL receptor-related protein (LRP) in the liver was observed at mRNA levels (49.5% increase, P = 0.13), which might play a role in the lipoprotein reduction. Histological analyses of aorta revealed that aortic arch showed the most advanced lesions with larger lesion area (70.0 vs 41.3%) and much greater CE content (more than 2 fold) with less macrophages than thoracic aorta. NK-104 decreased the surface lesion area at the arch (23.1%, p = 0.054) and reduced the degeneration of media in the thoracic aorta (69.9% increase in medial smooth muscle cells, p < 0.01). Thus NK-104 preferentially reduced TG-rich lipoproteins (VLDL and IDL) without affecting LDL-C levels and prevented progression of atherosclerosis in WHHL rabbits.

Matrix Metalloproteinase-2 Proteolysis of Calponin-1 Contributes to Vascular Hypocontractility in Endotoxemic Rats

Matrix metalloproteinase (MMP)-2 is activated in aorta during endotoxemia and plays a role in the hypocontractility to vasoconstrictors. Calponin-1 is a regulator of vascular smooth muscle tone with similarities to troponin, a cardiac myocyte protein that is cleaved by MMP-2 in myocardial oxidative stress injuries. We hypothesized that calponin-1 may be proteolyzed by MMP-2 in endotoxemia-induced vascular hypocontractility. Rats were given a nonlethal dose of bacterial lipopolysaccharide (LPS) or vehicle. Some rats were given the MMP inhibitors ONO-4817 or doxycycline. Six hours later, plasma nitrate+nitrite increased >15-fold in LPS-treated rats, an effect unchanged by doxycycline. Both ONO-4817 and doxycycline prevented LPS-induced aortic hypocontractility to phenylephrine. LPS activated MMP-2 in the aorta by S-glutathiolation. Calponin-1 levels decreased by 25% in endotoxemic aortae, which was prevented by doxycycline. Calponin-1 and MMP-2 coimmunoprecipitated and both exhibited uniform cytosolic staining in medial vascular smooth muscle cells. In vitro incubation of calponin-1 with MMP-2 led to calponin-1 degradation and appearance of its cleavage product. Calponin-1 is a target of MMP-2, which contributes to endotoxemia-induced vascular hypocontractility.

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.

Increased oxidative stress and severe arterial remodeling induced by permanent high-flow challenge in experimental pulmonary hypertension

BackgroundInvolvement of inflammation in pulmonary hypertension (PH) has previously been demonstrated and recently, immune-modulating dendritic cells (DCs) infiltrating arterial lesions in patients suffering from idiopathic pulmonary arterial hypertension (IPAH) and in experimental monocrotaline-induced PH have been reported. Occurrence of perivascular inflammatory cells could be linked to local increase of oxidative stress (OS), as it has been shown for systemic atherosclerosis. The impact of OS on vascular remodeling in PH is still to be determined. We hypothesized, that augmented blood-flow could increase OS and might thereby contribute to DC/inflammatory cell-recruitment and smooth-muscle-cell-proliferation.MethodsWe applied a monocrotaline-induced PH-model and combined it with permanent flow-challenge. Thirty Sprague-Dawley rats were assigned to following groups: control, monocrotaline-exposure (MCT), monocrotaline-exposure/pneumonectomy (MCT/PE).ResultsHemodynamic exploration demonstrated most severe effects in MCT/PE, corresponding in histology to exuberant medial and adventitial remodeling of pulmonary muscular arteries, and intimal remodeling of smaller arterioles; lung-tissue PCR evidenced increased expression of DCs-specific fascin, CD68, proinflammatory cytokines (IL-6, RANTES, fractalkine) in MCT/PE and to a lesser extent in MCT. Major OS enzyme NOX-4 was maximal in MCT/PE. Antioxidative stress enzymes Mn-SOD and glutathion-peroxidase-1 were significantly elevated, while HO-1 showed maximal expression in MCT with significant decrease in MCT/PE. Catalase was decreased in MCT and MCT/PE. Expression of NOX-4, but also of MN-SOD in MCT/PE was mainly attributed to a highly increased number of interstitial and perivascular CXCR4/SDF1 pathway-recruited mast-cells. Stress markers malonedialdehyde and nitrotyrosine were produced in endothelial cells, medial smooth muscle and perivascular leucocytes of hypertensive vasculature. Immunolabeling for OX62, CD68 and actin revealed adventitial and medial DC- and monocyte-infiltration; in MCT/PE, medial smooth muscle cells were admixed with CD68+/vimentin+ cells.ConclusionOur experimental findings support a new concept of immunologic responses to increased OS in MCT/PE-induced PAH, possibly linking recruitment of dendritic cells and OS-producing mast-cells to characteristic vasculopathy.

Transforming Growth Factor Beta Expression by Human Vascular Cells Inhibits Interferon Gamma Production and Arterial Media Injury by Alloreactive Memory T Cells

Arteriosclerosis is characterized by the local activation of effector T cells leading to production of proinflammatory cytokines, such as IFN (interferon)-γ and IL-17, within the vessel wall. Conversely, the production of antiinflammatory cytokines, for example, TGF-β, by regulatory lymphocytes is known to inhibit both the differentiation of naïve T cells into effector T cells and the development of arteriosclerosis in murine models. We investigated the role of TGF-β on the alloreactivity of human effector memory T cells (Tem). Quiescent vascular cells, but not Tem, expressed TGF-β. Blockade of TGF-β activity in cocultures of CD4(+) Tem with allogeneic endothelial cells significantly increased IFN-γ, but not IL-17, secretion. Additionally, serologic neutralization of TGF-β in immunodeficient mouse hosts of human coronary artery grafts into which allogeneic human T cells were adoptively transferred resulted in heavier medial infiltration by Tem, greater loss of medial smooth muscle cells and increased IFN-γ production within the grafts without significantly reducing either intimal injury or IL-17 production. Protective effects of TGF-β may be limited by fewer TGF-β-expressing vascular cells within the intimal compartment, by a reduction in the expression of TGF-β by vascular cells in rejecting grafts, or possibly to less effective suppression of Tem than naïve T cells.

Crucial role of CD40 signaling in vascular wall cells in neointimal formation and vascular remodeling after vascular interventions.

It has been shown that CD40-TRAF6 axis in leukocytes plays a significant role in neointimal formation after carotid ligation. Because CD40 and TRAF6 are expressed not only in leukocytes but also in vascular cells, we examined the role of CD40 contributed by vascular wall cells in neointimal formation after carotid ligation in an atherogenic environment. Both CD40 and TRAF6 in medial smooth muscle cells (SMCs) was upregulated significantly at 3 days and more prominently at 7 days after injury in wildtype mice, but the TRAF6 upregulation was abolished in CD40(-/-) mice. In vitro, TRAF6 expression was induced by cytokines (tumor necrosis factor -α, interleukin-1β) via a NF-κB-dependent manner in wildtype SMCs, but this induction was blocked in CD40-deficient SMCs. Bone marrow chimeras revealed a comparable reduction in neointimal formation and lumen stenosis in mice lacking either vascular wall- or bone marrow-associated CD40. Lacking vascular wall-associated CD40 resulted in a significant reduction in monocyte/macrophage accumulation, NF-κB activation, and multiple proinflammatory mediators (ICAM-1, VCAM-1, MCP-1, MMP-9, tissue factor). In vitro data confirmed that CD40 deficiency or TRAF6 knockdown suppressed CD40L-induced proinflammatory phenotype of SMCs by inhibition of NF-κB activation. Moreover, both in vivo and in vitro data showed that CD40 deficiency prevented injury-induced SMC apoptosis but did not affect SMC proliferation and migration. CD40 signaling through TRAF6 in vascular SMCs seems to be centrally involved in neointimal formation in a NF-κB-dependent manner. Modulating CD40 signaling on local vascular wall may become a new therapeutic target against vascular restenosis.

060 Primary cultures of rat medial smooth muscle cells spontaneously develop invadopodia

060 Primary cultures of rat medial smooth muscle cells spontaneously develop invadopodia

127 Innate immune effectors are necessary and sufficient to cause early post transplant failure of medial smooth muscle cell recovery in murine aortic allografts

127 Innate immune effectors are necessary and sufficient to cause early post transplant failure of medial smooth muscle cell recovery in murine aortic allografts

Early Atheroma-Derived Agonists of Peroxisome Proliferator–Activated Receptor-γ Trigger Intramedial Angiogenesis in a Smooth Muscle Cell–Dependent Manner

Neovascularization favors intraplaque hemorrhage and plaque rupture. Development of therapeutic strategies against atheromatous angiogenesis requires elucidation of its initiating factors. We investigated the contribution of smooth muscle cells (SMCs) and atheroma-derived lipids to the initiation of atheroma-associated neoangiogenesis. Forty human aortic segments, each harvested from a different donor, were classified as healthy or as bearing early atheromatous lesions, including fatty streaks and fibrolipidic atheroma, according to their histological features. Immunostaining for blood vessels and vascular endothelial growth factor-A (VEGF-A), as well as measurement of VEGF-A protein and mRNA levels by ELISA and real-time PCR, revealed that angiogenesis and VEGF-A production were enhanced in the medial layer of atheromatous aortas. The intramedial vessel density and invasiveness and the production of VEGF-A by medial SMCs were indeed increased in atheromatous aortas compared with healthy aortas. Furthermore, intimal layers of atheromatous aortas were enriched in soluble lipid mediators capable of inducing a sustained increase in VEGF-A production by medial SMCs, turning these cells into potent inducers of angiogenesis when incorporated into mouse Matrigel implants. Both effects were inhibited by the peroxisome proliferator-activated receptor-γ inhibitor GW9662 and mimicked by its agonist, rosiglitazone. We show that VEGF-A production is upregulated in medial SMCs of human atheromatous aortas and that peroxisome proliferator-activated receptor-γ agonists derived from early intimal lesions are likely to contribute to this phenotypic change. Our findings suggest that medial SMCs are central organizers of an angiogenic response initiated by the subendothelial accumulation of atherogenic lipids.

656 Altered microcalcification pattern in aorta from pigs and rats exposed for 30-days to environmental tobacco smoke

Endothelial dysfunction and arterial stiffening are associated with environmental tobacco smoke (ETS) exposure and atherogenesis in humans. Early atherogenic events have recently been proposed to resemble osteogenesis, with microcalcification deposits in the form of calcium hydroxyapatite (Ca10(PO4)6(OH)2) reported in large artery tissue. Thus, we hypothesized that increased microcalcium deposits would be detectable using the high resolution imaging afforded by synchrotron techniques in aorta from male pigs and rats exposed 1-hr/day for 30-days to ETS compared to sham controls. Furthermore, it was hypothesized that calcium deposition would be co-localized with phosphorus. Images of formalin-fixed, paraffin-embedded aortic cross-sections (5 micron) were collected using X-ray fluorescence imaging on beamline 2-3 at Stanford Synchrotron Radiation Lightsource (SSRL, Menlo Park, CA). A striking pattern was evident when aortic calcium was viewed, with high intensity levels within the medial layer smooth muscle cells and a relative absence in the elastic laminae. Paradoxically, the average calcium level was lower in aorta after 30-days of ETS compared to sham-exposure in both pigs and rats. However, the major area where calcium co-localized with phosphorus appeared to be in the elastic laminae, not the medial layer smooth muscle cells. In the same ETS-exposed animals prior to sacrifice, impaired endothelial function (lower flow-mediated dilation) was observed in pigs and increased arterial stiffness (increased arterial pulsewave dP/dt) was evident in rats compared to respective sham controls. Therefore, the key finding of this study is that microcalcification may proceed through deposition of calcium and phosphorus in the elastic laminae. In contrast, decreased bound calcium within aortic smooth muscle cells from ETS- compared to sham-exposed rats and pigs needs to be confirmed, but could have large functional implications.

Mechanism of arterial remodeling in chronic allograft vasculopathy

Chronic allograft vasculopathy (CAV) remains a major obstacle for long-term survival of grafts even though therapeutic strategies have improved considerably in recent years. CAV is characterized by concentric and diffuse neointimal formation, medial apoptosis, infiltration of lymphocyte or inflammatory cells, and deposition of extracellular matrix both in arteries and veins. Recent studies have shown that stem cells derived from the recipient contribute to neointimal formation under the regulation of chemokines and cytokines. Arterial remodeling in allografts eventually causes ischemic graft failure. The pathogenesis is multi-factorial with both immunologic and non-immunological factors being involved. The immunological factors have been discussed extensively in other articles. This review focuses mainly on the arterial remodeling that occurs in 3 layers of vessel walls including intimal injury, accumulation of smooth muscle-like cells in the neointimal, medial smooth muscle cell apoptosis, adventitial fibrosis, and deposition of extracellular matrix.

Cathepsin L Activity Is Essential to Elastase Perfusion–Induced Abdominal Aortic Aneurysms in Mice

The development of abdominal aortic aneurysms (AAA) requires extensive aortic wall matrix degradation. Human AAA lesions express high levels of cathepsin L (CatL), one of the most potent mammalian elastases. Whether this protease participates directly in AAA pathogenesis, however, is unknown. We generated experimental AAA with aortic elastase perfusion in mice and established an essential role of CatL in AAA formation. After 14 days postperfusion, most wild-type (Ctsl(+/+)) mice developed AAA, but none of the CatL-deficient (Ctsl(-/-)) mice did. AAA lesion macrophage contents, CD4(+) T cell numbers, CD31(+) and laminin-5 angiogenic fragment γ2(+) microvessel numbers, and elastin fragmentation were all significantly lower in Ctsl(-/-) mice than in Ctsl(+/+) mice. While lesions from Ctsl(-/-) mice contained fewer Ki67(+) proliferating cells than did Ctsl(+/+) mice, the absence of CatL did not affect lesion apoptotic cell contents or medial smooth-muscle cell loss significantly. Mechanistic studies indicated that the absence of CatL reduced lesion chemokine monocyte chemotactic protein-1 content, macrophage and T-cell in vitro transmigration, and angiogenesis, and altered the expression and activities of matrix metalloproteinases and other cysteinyl cathepsins in inflammatory cells, vascular cells, and AAA lesions. CatL contributes to AAA formation by promoting lesion inflammatory cell accumulation, angiogenesis, and protease expression.

Cathepsin K Deficiency Reduces Elastase Perfusion–Induced Abdominal Aortic Aneurysms in Mice

Cathepsin K (CatK) is one of the most potent mammalian elastases. We have previously shown increased expression of CatK in human abdominal aortic aneurysm (AAA) lesions. Whether this protease participates directly in AAA formation, however, remains unknown. Mouse experimental AAA was induced with aortic perfusion of a porcine pancreatic elastase. Using this experimental model, we demonstrated that absence of CatK prevented AAA formation in mice 14 days postperfusion. CatK deficiency significantly reduced lesion CD4(+) T-cell content, total lesion and medial cell proliferation and apoptosis, medial smooth muscle cell (SMC) loss, elastinolytic CatL and CatS expression, and elastin fragmentation, but it did not affect AAA lesion Mac-3(+) macrophage accumulation or CD31(+) microvessel numbers. In vitro studies revealed that CatK contributed importantly to CD4(+) T-cell proliferation, SMC apoptosis, and other cysteinyl cathepsin and matrix metalloproteinase expression and activities in SMCs and endothelial cells but played negligible roles in microvessel growth and monocyte migration. AAA lesions from CatK-deficient mice showed reduced elastinolytic cathepsin activities compared with those from wild-type control mice. This study demonstrates that CatK plays an essential role in AAA formation by promoting T-cell proliferation, vascular SMC apoptosis, and elastin degradation and by affecting vascular cell protease expression and activities.

Adventitial gene transfer of VEGFR-2 specific VEGF-E chimera induces MCP-1 expression in vascular smooth muscle cells and enhances neointimal formation

BackgroundThe role of vascular endothelial growth factors (VEGFs) in neointimal formation has been controversial. VEGF receptor (R)-2 signaling pathway is crucial in bringing about the effects of VEGFs including vasodilatation, endothelial cell migration and proliferation. In this study we have used an established adventitial gene transfer technique, in vitro studies and a novel VEGF-E/PlGF chimera that binds specifically to VEGFR-2, to investigate the role of VEGFR-2 in neointimal formation. MethodsIntimal hyperplasia was induced in the carotid arteries of cholesterol fed male New Zealand White rabbits using a silastic collar. Adenoviral vectors encoding VEGF-E chimera (1×109pfu/ml) were transferred to the adventitia of the carotid arteries either alone or together with adenoviruses encoding soluble VEGFR-2 (sVEGFR-2). Adenoviruses encoding LacZ were used as controls. All animals were sacrificed 7 days after the gene transfer. ResultsSignificant increases in neointimal formation, proliferating cells, inflammatory responses and adventitial angiogenesis were observed in the VEGF-E chimera transduced arteries. The number of medial smooth muscle cells expressing VEGFR-2 was significantly (p<0.001) higher. MCP-1 mRNA levels were significantly (p<0.01) increased in the VEGF-E chimera transduced arteries and transduced rabbit aortic smooth muscle cells (p<0.05). Soluble VEGFR-2 (sVEGFR-2) significantly inhibited VEGF-E chimera induced neointimal formation (p<0.01), cellular proliferation (p<0.01), inflammatory responses (p<0.01) and adventitial angiogenesis (p<0.01). ConclusionsThe results indicate that VEGFR-2 mediated signaling could aggravate neointimal formation and suggest a potential therapeutic role of sVEGFR-2 in inhibiting neointimal formation and adventitial angiogenesis.

Reduction of reactive oxygen species prevents hypoxia-induced CREB depletion in pulmonary artery smooth muscle cells.

Hypoxia-induced pulmonary arterial hypertension (PAH) is a deadly disease characterized by progressive remodeling and persistent vasoconstriction of the pulmonary arterial system. Remodeling of the pulmonary artery (PA) involves smooth muscle cell (SMC) proliferation, hypertrophy, migration, and elevated extracellular matrix (ECM) production elicited by mitogens and oxidants produced in response to hypoxic insult. We previously reported that the transcription factor cAMP response element binding protein (CREB) is depleted in medial PA SMCs in remodeled, hypertensive vessels in rats or calves exposed to chronic hypoxia. In culture, CREB loss can be induced in PA SMCs by exogenous oxidants or platelet-derived growth factor. Forced depletion of CREB with small interfering RNA (siRNA) in PA SMCs is sufficient to induce their proliferation, hypertrophy, migration, dedifferentiation, and ECM production. This suggests that oxidant and/or mitogen-induced loss of CREB in medial SMCs is, in part, responsible for PA thickening. Here, we tested whether oxidant scavengers could prevent the loss of CREB in PA SMCs and inhibit SMC proliferation, migration, and ECM production using in vitro and in vivo models. Exposure of PA SMCs to hypoxia induced hydrogen peroxide (H2O2) production and loss of CREB. Treatment of SMCs with exogenous H2O2 or a second oxidant, Sin-1, elicited CREB depletion under normoxic conditions. Exogenous H2O2 also induced SMC proliferation, migration, and increased elastin levels as did forced depletion of CREB. In vivo, hypoxia-induced thickening of the PA wall was suppressed by the superoxide dismutase mimetic, Tempol, which also prevented the loss of CREB in medial SMCs. Tempol also reduced hypoxia-induced SMC proliferation and elastin deposition in the PA. The data indicate that CREB levels in the arterial wall are regulated in part by oxidants produced in response to hypoxia and that CREB plays a crucial role in regulating SMC phenotype and PA remodeling.

Varicella zoster virus vasculopathy

Varicella zoster virus (VZV) is an under-recognized yet treatable cause of stroke. No animal model exists for stroke caused by VZV infection of cerebral arteries. Thus, we analyzed cerebral and temporal arteries from 3 patients with VZV vasculopathy to identify features that will help in diagnosis and lead to a better understanding of VZV-induced vascular remodeling. Normal and VZV-infected cerebral and temporal arteries were examined histologically and by immunohistochemistry using antibodies directed against VZV, endothelium, and smooth muscle actin and myosin. All VZV-infected arteries contained 1) a disrupted internal elastic lamina; 2) a hyperplastic intima composed of cells expressing α-smooth muscle actin (α-SMA) and smooth muscle myosin heavy chain (SM-myosin) but not endothelial cells expressing CD31; and 3) decreased medial smooth muscle cells. The location of VZV antigen, degree of neointimal thickening, and disruption of the media were related to the duration of disease. The presence of VZV primarily in the adventitia early in infection and in the media and intima later supports the notion that after reactivation from ganglia, VZV spreads transaxonally to the arterial adventitia followed by transmural spread of virus. Disruption of the internal elastic lamina, progressive intimal thickening with cells expressing α-SMA and SM-MHC, and decreased smooth muscle cells in the media are characteristic features of VZV vasculopathy. Stroke in VZV vasculopathy may result from changes in arterial caliber and contractility produced in part by abnormal accumulation of smooth muscle cells and myofibroblasts in thickened neointima and disruption of the media.

Sirtuin 1 Retards Hyperphosphatemia-Induced Calcification of Vascular Smooth Muscle Cells

Arterial calcification is associated with cardiovascular disease as a complication of advanced atherosclerosis. Aged vascular cells manifest some morphological features of a senescent phenotype. Recent studies have demonstrated that mammalian sirtuin 1 (SIRT1), a histone deacetylase, is an exciting target for cardiovascular disease management. Here, we investigated the role of SIRT1 in a calcification model of vascular smooth muscle cells (SMCs). In adenine-induced renal failure rats with hyperphosphatemia, massive calcification was induced in the aortic media. Senescence-associated β-galactosidase (SAβ-gal) activity, a marker of cellular senescence, in medial SMCs was significantly increased, and its induction was positively associated with the degree of calcification. In cultured SMCs, inorganic phosphate (Pi) stimulation dose-dependently increased SAβ-gal-positive cells, and Pi-induced senescence was associated with downregulation of SIRT1 expression, leading to p21 activation. The activation via SIRT1 downregulation was blunted by inhibition of Pi cotransporter. Activation of SIRT1 by resveratrol significantly reduced the senescence-associated calcification. Conversely, SIRT1 knockdown by small interfering RNA accelerated the Pi-induced SMC senescence and subsequent calcification. In addition, SIRT1 knockdown induced phenotypic change from a differentiated state to osteoblast-like cells. The senescence-related SMC calcification was completely prevented by p21 knockdown. In addition to Pi-induced premature senescence, SMCs with replicative senescence were also more sensitive to Pi-induced calcification compared with young SMCs, and this finding was attributable to augmented p21 expression. SIRT1 plays an essential role in preventing hyperphosphatemia-induced arterial calcification via inhibition of osteoblastic transdifferentiation. In addition, Pi-induced SMC calcification may be associated with both premature and replicative cellular senescence.

The effects of the expression of NF - kB, MCP - 1 and MMP - 9 on experimental cerebral aneurysm rabbit model

Objective To study the effects of nuclear factor Kappa B (NF - κB),MCP - 1 and MMP -9 at the early phase of cerebral aneurysm (CA).Methods 24 healthy New Zealand rabbits,half female and half male,were randomly divided into 4 groups:group A ( control group),group B ( 1 week),group C(2 weeks),group D (3 weeks),6 rabbits per-group.The morphologic change of the right common carotid artery and formation of the aneurysm were detected by CT angiography and HE dyeing.Aneurysm samples were collected,and immunohistochemistry and real - time rolymerase chain reaction ( Real - time PCR)used to detect the expression of the proteinum and mRNA of NF - κB,MCP - 1 and MMP -9.Results ( 1 ) After a week,using CT angiography to detect all the 18 experimental rabbits,all of them have found visible fusiform or cystiform aneurysms where the elastase was dropped,and also found that some vessels were obstructed.Aneurysms have not found in all the control group rabbits.The pathological examination of the experimental aneurysms showed that the wall of aneurysm becoming thinner,the internal elastic layers were disrupted or disappeared and the reduced medial vascular smooth muscle cell becoming atrophy or degradation obviously.Inflammatory cell infiltrate were also observed in the control group,but the internal elastic layers degradation and vascular smooth muscle degeneration were not found.(2)The result of immunohistochemistry and Real - time PCR indicate that NF - κB and MCP - 1 reached the peak at 1 week,and decreased at 3 weeks.MMP - 9 was increased gradually.The expression of NF - κB and MCP - 1 were not found in control group.Conclusion NF - κB activation may be one of the initiating agents in the development of the cerebral aneurysm.MCP - 1 and MMP - 9 significantly increased in CA that play an important role in the pathogenesis of cerebral aneurysm(CA). Key words: Aneurysm; Nuclear factor - κB; Monocyte chemotactic protein - 1; MMP -9

The effect of L‐arginine or L‐citrulline supplementation on biochemical parameters and the vascular aortic wall in high‐fat and high‐cholesterol‐fed rats

The aim of the present study is to investigate the potential role of L-arginine or L-citrulline in rats fed high-fat and high-cholesterol (HFC) diet. HFC feeding increased significantly serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, urea and all lipid profiles and decreased significantly serum high-density lipoprotein-cholesterol (HDL-c) and non significantly serum nitric oxide levels. L-arginine or L-citrulline administration reversed the increase in serum AST and ALT activities, urea and all lipid profiles. These effects were associated with a concomitant increase in HDL-c and nitric oxide levels. In general, rats fed HFC diet and orally treated with L-arginine or L-citrulline had higher relative percentage of 18:0, 20:0 and 22:6 and lower 16:0 fatty acids than rats fed HFC diet. Light and transmission electron microscopic findings of the thoracic aorta confirmed the biochemical results and demonstrated structural changes in the endothelial cells of the intimal layer, medial smooth muscle cells as well as in the adventitial layer in HFC fed-animals. However, these findings indicate little structural alterations in animals supplemented with L-arginine or L-citrulline along with HFC feeding. In the present study, L-arginine or L-citrulline was effective hypocholesterolemic and hypolipidemic agents in rats.