Autophagy facilitates secretion and protects against degeneration of the Harderian gland.

The epithelial derived Harderian gland consists of 2 types of secretory cells. The more numerous type A cells are responsible for the secretion of lipid droplets, while type B cells produce dark granules of multilamellar bodies. The process of autophagy is constitutively active in the Harderian gland, as confirmed by our analysis of LC3 processing in GFP-LC3 transgenic mice.

Vascular injury response in mice is dependent on genetic background.

Mouse models are employed to unravel the pathophysiology of vascular restenosis. Although much effort has been spent on how to apply an adequate arterial injury, the influence of the genetic background of mice has not yet received sufficient consideration. The study presented herein was designed to demonstrate the influence of the mouse strain on vascular injury response.

Upregulation of connexin43 gap junctions between neointimal smooth muscle cells.

Increased expression of connexin43 gap junctions in smooth muscle cells (SMC) is implicated in the response to primary arterial injury and in the early stages of human coronary atherosclerosis, but the relevance of these findings to restenosis is unknown. Here we investigated the expression of connexin43 gap junctions in restenotic aortas of cholesterol-fed double injured rabbits. Immunofluorescence confocal microscopy was used to evaluate temporal and spatial expression patterns and to characterize the major expressing cell type.

Phytanic acid accumulation is associated with conduction delay and sudden cardiac death in sterol carrier protein-2/sterol carrier protein-x deficient mice.

Introduction: The sterol carrier protein-2 gene encodes two functionally distinct proteins: sterol carrier protein-2 (SCP2, a peroxisomal lipid carrier) and sterol carrier protein-x (SCPx, a peroxisomal thiolase known as peroxisomal thiolase-2), which is involved in peroxisomal metabolism of bile acids and branched-chain fatty acids. We show in this study that mice deficient in SCP2 and SCPx (SCP2null) develop a cardiac phenotype leading to a high sudden cardiac death rate if mice are maintained on diets enriched for phytol (a metabolic precursor of branched-chain fatty acids).

Methods And Results: In 210 surface and 305 telemetric ECGs recorded in wild-type (C57BL/6; wt; n = 40) and SCP2 null mice (n = 40), no difference was observed at baseline.

[Mechanisms of transplant vasculopathy].

Cardiac allograft vasculopathy is a diffuse, obliterative form of arteriosclerosis that is characterized by the production of a neointima rich in vascular smooth muscle cells that progressively obstructs the lumen. Pathophysiologically, after heart transplantation, alloantigens (e. g.

Proinflammatory cytokines regulate LOX-1 expression in vascular smooth muscle cells.

Objective: Atherogenesis represents a type of chronic inflammation and involves elements of the immune response, eg, the expression of proinflammatory cytokines. In advanced atherosclerotic lesions, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is expressed in endothelial cells, macrophages, and smooth muscle cells (SMCs). In vitro, the expression of LOX-1 is induced by inflammatory cytokines like TNF-alpha and transforming growth factor (TGF)-beta.

Lipids partition caveolin-1 from ER membranes into lipid droplets: updating the model of lipid droplet biogenesis.

Caveolin-1, a putative mediator of intracellular cholesterol transport, is generally assumed to be integrated into the cytoplasmic leaflets of all cellular membranes. Lipid droplets form by budding at the endoplasmic reticulum (ER), and caveolin-1 is thought to be transferred to the droplet surface along with the cytoplasmic leaflet of ER membranes and not to enter the droplet core. We explored how caveolin-1 accesses lipid droplets from the ER by localizing caveolin-1 in ER membranes and in lipid droplets in cultured smooth muscle cells using freeze-fracture immunocytochemistry.

Tropomyosin 4 expression is enhanced in dedifferentiating smooth muscle cells in vitro and during atherogenesis.

Dedifferentiation of smooth muscle cells (SMC) from the contractile to the synthetic phenotype is a key event in atherosclerosis. A comparable phenotypic change from the contractile to the synthetic state is rapidly incurred when SMC are grown in culture. To identify genes that characterize the contractile and synthetic phenotypes, we performed differential display reverse transcription polymerase chain reactions on RNA from porcine arterial contractile SMC obtained directly from medial tissues and from SMC made synthetic by cell culturing.

Cholesterol transporter caveolin-1 transits the lipid bilayer during intracellular cycling.

Caveolin-1, a major protein of cell surface invaginations called caveolae, is currently believed to cycle between the plasma membrane and intracellular compartments via the endocytotic pathway, at least for part of its itinerary. We studied the distribution of caveolin-1 in cell membranes, using ultrathin cryosections and freeze-fracture immunolabeling and found this protein not only in the cytoplasmic leaflet of the plasma membrane, but also in the exoplasmic leaflet of all intracellular membranes. This sidedness implies that caveolin-1 switches from one membrane leaflet to the other somewhere on its way through the cell and rules out the classic mechanism of endocytotic membrane budding and fusion for caveolin-1 intracellular trafficking.

Alterations in the vascular extracellular matrix of granulocyte macrophage colony-stimulating factor (GM-CSF) -deficient mice.

GM-CSF takes part in the cytokine network regulating the metabolism of extracellular matrix (ECM) during atherogenesis. Since data also point to an effect of GM-CSF on the vascular ECM in general, the vascular collagenous matrix was studied in wild-type and GM-CSF-deficient mice. Histological examination revealed a disorganized vascular ECM in GM-CSF-deficient mice involving the collagenous matrix and elastic fiber system.

Vascular ligation response is independent of p107: stressing the role of the related p130.

Recent studies have revealed the role of the pRb family members pRb and p130 in the response to vascular injury. We evaluated the arterial injury response in the absence of p107, a protein that shares a high degree of homology with the injury-controlling p130. Carotid artery ligation and perivascular electric injury of the femoral artery were applied to p107 knockout (p107 -/-) mice, and morphometric analysis was performed 3 wk after ligation and electric injury.

Expanding expression of the 5-lipoxygenase pathway within the arterial wall during human atherogenesis.

Oxidation products of low-density lipoproteins have been suggested to promote inflammation during atherogenesis, and reticulocyte-type 15-lipoxygenase has been implicated to mediate this oxidation. In addition, the 5-lipoxygenase cascade leads to formation of leukotrienes, which exhibit strong proinflammatory activities in cardiovascular tissues. Here, we studied both lipoxygenase pathways in human atherosclerosis.

Vascular collagens: spotlight on the role of type VIII collagen in atherogenesis.

Collagens play a central role in maintaining the integrity and stability of the undiseased as well as of the atherosclerotic vessel wall. An imbalanced metabolism may lead to uncontrolled collagen accumulation reducing vessel wall velocity, frequently resulting in arterial occlusion or thrombosis. A reduced production of collagen and its uncontrolled degradation may affect the stability of the vessel wall and especially of the atherosclerotic plaques by making them prone to rupture and aneurysm.

Smooth muscle-specific expression of SV40 large TAg induces SMC proliferation causing adaptive arterial remodeling.

To study the effects of enhanced smooth muscle cell (SMC) proliferation on arterial vessel geometry in the absence of vessel trauma, we developed a transgenic mouse model expressing SV40 large T antigen under control of the 2.3-kb smooth muscle-myosin heavy chain promoter. Transgenic mice studied at ages from 3 to 13 wk showed a 3.

Direct evidence for the importance of p130 in injury response and arterial remodeling following carotid artery ligation.

Objective: Remodeling of arterial morphology in atherosclerosis, hypertension, and restenosis following angioplasty involves controlled alterations in total vascular circumference which critically modulate sequelae of changes in vessel wall mass. Despite the clinical relevance of this process little is known about the pathophysiology, especially the correlation between smooth muscle cell proliferation and remodeling.

Methods: Carotid artery ligation was applied to mice with targeted disruption of the p130 gene (p130 -/-).

Paclitaxel and cyclosporine A show supra-additive antiproliferative effects on smooth muscle cells by activation of protein kinase C.

We intended to establish a pharmacologic concept of synergistic antiproliferative effects on smooth muscle cells (SMC) by using paclitaxel and cyclosporine A at clinically applicable doses. Coronary SMC were incubated with paclitaxel and cyclosporine A at concentrations of 10-20 nmol/L and 83-415 nmol/L, respectively. Antiproliferative effects were assessed by cell counts, [3H]thymidine incorporation and cell cycle analysis.

The interleukin-6/interleukin-6-receptor system is activated in donor hearts.

Objectives: To assess the potential of the donor heart to respond to interleukin-6 (IL6), the present study investigated the expression of IL6 receptor components in the myocardium of donor hearts before transplantation.

Background: Donor heart dysfunction early after transplantation has been associated with the cytokine storm after donor brain death. Proinflammatory cytokines are thought to play a central role in this process.

Alteration of fracture stability influences chondrogenesis, osteogenesis and immigration of macrophages.

Mechanical conditions at the fracture line determine the mode of fracture healing (osteonal versus non-osteonal bone union). The aim of this study was to investigate the influence of differing degrees of fracture stability on the time course of chondrogenesis, enchondral ossification and immigration of macrophages into the fracture callus. Using a fracture model of the rat's tibia, histological (Azan staining), immunohistological (antibodies directed against the macrophage-specific surface antigen ED2), and molecular biological techniques (expression of the mRNA of the cartilage-specific collagen IX, osteocalcin - a marker for mature osteoblasts - and the macrophage-specific macrosialin) were employed.

Activation of the cardiac interleukin-6 system in advanced heart failure.

Objectives: The study objective was to assess the cardiac expression of interleukin-6 (IL6) and its receptor (IL6R) in advanced heart failure.

Background: While IL6 plasma levels are elevated and associated with an impaired prognosis in advanced heart failure, little is known about the intracardiac expression of the IL6 system.

Methods: Heart tissue was obtained from 20 patients (n=10, idiopathic dilated cardiomyopathy, age 44+/-15 years; n=10, ischemic cardiomyopathy, age 55+/-8 years) at the time of transplantation.