Purpose: Previous research in our laboratory indicated that prothrombin and other coagulation enzymes required to activate prothrombin to thrombin are synthesized by the cornea and that apoptotic human corneal stromal cells can provide a surface for prothrombin activation through the intrinsic and extrinsic coagulation pathways. The purpose of the work reported here is to study the role of thrombin activity in the regulation of matricellular protein Cyr61 (CCN1) produced by wounded phenotype human corneal stromal fibroblasts and myofibroblasts.
Methods: Stromal cells from human donor corneas were converted to defined wounded phenotype fibroblasts and myofibroblasts with fetal bovine serum, followed by basic fibroblast growth factor (bFGF) and transforming growth factor beta-1 (TGFβ-1), respectively, and stimulated with varying concentrations (0-10.
Purpose: Insulin-like growth factor 2 receptor (IGF2R) associates with ligands that influence wound healing outcomes. However, the expression pattern of IGF2R and its role in the cornea is unknown.
Methods: Human keratocytes were isolated from donor corneas.
Latent TGF-β1 was one of the first non-lysosomal glycoproteins reported to bear mannose 6-phosphate (Man-6-P) residues on its N-glycans. Prior studies have suggested that this sugar modification regulates the activation of latent TGF-β1 by allowing it to bind cell surface-localized Man-6-P receptors. Man-6-P has also been proposed as an anti-scarring therapy based on its ability to directly block the activation of latent TGF-β1.
View Article and Find Full Text PDFMaspin, an inhibitor of cell migration and a stimulator of adhesion of cells to the ECM, is synthesized and released by corneal keratocytes into the extracellular matrix. When the cornea is wounded, the quiescent stromal keratocytes underlying the wound undergo apoptosis and cells adjacent to this apoptotic area convert to fibroblasts or myofibroblasts. This study explores the effect of extracellular maspin on the plasminogen-plasminogen activator system of corneal stromal cells following wounding.
View Article and Find Full Text PDFMaspin is a non-inhibitory serine protease inhibitor (serpin) that influences many cellular functions including adhesion, migration, and invasion. The underlying molecular mechanisms that facilitate these actions are still being elucidated. In this study we determined the mechanism by which maspin mediates increased MCF10A cell adhesion.
View Article and Find Full Text PDFMaspin, a 42 kDa non-classical serpin (serine protease inhibitor) that controls cell migration and invasion, is mainly expressed by epithelial-derived cells but is also expressed in corneal stromal keratocytes. Upon culture of stromal keratocytes in the presence of FBS, maspin is down-regulated to nearly undetectable levels by passage two. DNA methylation is one of several processes that controls gene expression during cell differentiation, development, genetic imprinting, and carcinogenesis but has not been studied in corneal stromal cells.
View Article and Find Full Text PDFFibroblasts migrate into and repopulate connective tissue wounds. At the wound edge, fibroblasts differentiate into myofibroblasts, and they promote wound closure. Regulated fibroblast-to-myofibroblast differentiation is critical for regenerative healing.
View Article and Find Full Text PDFInvest Ophthalmol Vis Sci
January 2007
Purpose: Two major functions of thrombin observed in the cornea are activation of thrombin-sensitive, proteinase-activated receptors and cleavage of fibrinogen to fibrin. The purpose of this study was to determine whether the normal human cornea itself is competent to convert prothrombin to thrombin and synthesizes the mRNA for the proteins required.
Methods: Human corneas were processed for immunolocalization studies or separated into epithelial, stromal, and endothelial layers for proteins and RNA isolation.
Purpose: Maintenance of avascularity of the normal cornea and control of neovascularization during wound healing depend on a balance of angiogenic and antiangiogenic factors. The purpose of this paper is to determine the ability of corneal cells to convert plasminogen to angiostatins and to compare these products with those made by intact corneas.
Methods: RT-PCR was performed using plasminogen specific primers and the generated cDNA was sequenced.
The overall conformation of plasminogen depends upon the presence of anions and molecules such as AHA (6-aminohexanoic acid) and BZ (benzamidine). The purpose of the present study was to determine the effect of conformation on the initial and secondary cleavages of plasminogen to generate active angiostatins. Plasminogen was digested with the physiologically relevant neutrophil elastase in one of the four Tris/acetate buffers: buffer alone or buffer plus NaCl, AHA or BZ.
View Article and Find Full Text PDFMaspin, an ov-serpin, inhibits tumor invasion and induces cell adhesion to extracellular matrix molecules. Here, we use maspin/ovalbumin chimeric proteins and the maspin reactive site loop (RSL) peptide to characterize the role of the RSL in maspin-mediated functions. Replacement of the RSL plus the C-terminal region or the RSL alone of maspin with that of ovalbumin resulted in the loss of the stimulatory effect on adhesion of corneal stromal cells to type I collagen, fibronectin, and laminin and of mammary carcinoma MDA-MB-231 cells to fibronectin.
View Article and Find Full Text PDFAm J Physiol Heart Circ Physiol
August 2001
Because inflammatory processes may promote the development of atherosclerosis, we examined the activation of cytokine genes in rat vascular smooth muscle cells in vitro after treatment with bacterial lipopolysaccharide (LPS). Interleukin-1 (IL-1), IL-6 and tumor necrosis factor-alpha (TNF-alpha) mRNA increased in response to LPS. Activation of nuclear factor-kappaB (NF-kappaB) presumably results in NF-kappaB binding to regulatory regions of target genes and activating transcription.
View Article and Find Full Text PDFRecent evidence suggests that inflammatory cytokines, particularly tumor necrosis factor alpha (TNF-alpha), may play a role in heart disease. Elevated plasma levels of the cytokine have been reported in congestive heart failure and severe angina and after myocardial infarction. The exact role of TNF-alpha in heart disease and how production is stimulated and regulated in the heart are current areas of investigation.
View Article and Find Full Text PDFObjectives: Beta-adrenergic receptor agonists such as isoproterenol inhibit production of tumor necrosis factor (TNF)-alpha in a number of cell types. Because the heart is a source of TNF-alpha, we hypothesized that isoproterenol would inhibit cardiac production of the cytokine.
Design: Analysis of cardiac release of TNF-alpha.
Background: Recently we reported that bacterial lipopolysaccharide (LPS) stimulates release of tumor necrosis factor alpha (TNF-alpha) from porcine coronary arteries and smooth muscle cells cultured from those vessels. It has also been reported that plasma levels of TNF-alpha are elevated after myocardial infarction. Since it is known that the production of reactive oxygen intermediates (ROI) occurs during ischemia and ROI are suggested activators of the nuclear regulatory factor kappaB (NF-kappaB), we tested the hypothesis that release of TNF-alpha from smooth muscle cells could also be stimulated with a ROI-generating system.
View Article and Find Full Text PDFBackground: Evidence suggests that tumor necrosis factor-alpha (TNF-alpha) is involved in heart diseases such as atherosclerosis. We used porcine coronary arteries and smooth muscle cells cultured from these vessels to study the regulation of production of TNF-alpha. The aims were to determine if bacterial lipopolysaccharide (LPS) could stimulate production; if activation of the nuclear regulatory factor, NF-kappaB, was associated with production; and if intracellular cAMP regulates TNF-alpha in coronary vasculature through a mechanism involving NF-kappaB.
View Article and Find Full Text PDFPolypropylene mesh is commonly used in open and laparoscopic hernia repairs. We tested the hypothesis that intra-abdominal adhesion formation secondary to polypropylene mesh is greater when mesh is placed in an intraperitoneal versus an extraperitoneal position. Fifty adult male rats underwent midline laparotomy with or without implantation of a nonabsorbable mesh.
View Article and Find Full Text PDFTransforming growth factor-beta (TGF-beta) is an important factor in regulating the inflammatory response and the production of extracellular matrix by fibroblasts. These two processes are linked in the formation of fibrous adhesions after abdominal surgery. When the mesothelium is injured a fibrin strand is produced which is populated first by inflammatory cells then by fibroblasts which secrete extracellular matrix forming a permanent adhesion.
View Article and Find Full Text PDFA population of stem cells has been isolated from embryonic avian and neonatal rat skeletal muscle. These cells differentiate into several mesodermal phenotypes in culture upon treatment with dexamethasone. This study reports the isolation of a similar population of stem cells from another mesodermal tissue, the heart.
View Article and Find Full Text PDFOne of the common and most serious side effects of abdominal surgery is the formation of adhesions within the peritoneal cavity during healing. Efforts to prevent adhesion formation have concentrated on inhibiting the inflammatory response, inhibiting the formation or encouraging the lysis of fibrin, and protection of the damaged serosal surface. We are interested in regenerating the serosal surface by providing a source of mesothelial progenitor cells.
View Article and Find Full Text PDFWe have previously shown a population of putative mesenchymal stem cells in the connective tissue surrounding embryonic avian skeletal muscle. These cells differentiate into at least five recognizable phenotypes in culture: fibroblasts, chondrocytes, myotubes, osteoblasts, and adipocytes. We have now isolated a similar population of cells from fetal and newborn rat skeletal muscle.
View Article and Find Full Text PDFSpine (Phila Pa 1976)
March 1995
Study Design: An animal model of laminectomy in rats was used to study scar tissue formation around the spinal cord. Dexamethasone, in controlled-release form, was tested in this system for its ability to decrease fibrous tissue formation.
Objectives: The results were evaluated to determine whether dexamethasone in a biodegradable controlled-release vehicle could be used to limit scar tissue formation around the spinal cord after laminectomy.
Streptococci and streptococcal cell wall fragments induce arthritis in rats, with the severity and duration depending on the capacity of the cells or cell fragments to resist degradation by tissue enzymes. Their phlogogenic effects are apparently related to their ability to activate the alternate complement pathway (ACP). The in vitro activation of the ACP by lysozyme-treated cells and cell walls of group A, B, and D streptococci suggests that both rat and human lysozyme can modulate this activity, i.
View Article and Find Full Text PDFSeveral strains of group B Streptococcus agalactiae were found to be lethal for young adult rats. When bacteria were heat killed and then injected intraperitoneally into rats, rapid death (14 to 18 h) of the rats occurred, characterized by labored breathing, hemolyzed serum, hemoglobinuria, and subungual hemorrhages. Sections of tissues from these rats failed to reveal the cause of death.
View Article and Find Full Text PDFHeat-killed streptococci of Groups A, B, and D injected intraperitoneally into Sprague-Dawley rats induced arthritis. The histopathologic features of the arthritis were those of erosive synovitis. Early acute lesions were associated with deposits of streptococcal antigens.
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