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Victoria A Ploplis

Publications and source records attributed to Victoria A Ploplis.

15 recordsLinked to original sources
PubMed2006

Coagulation factor Xa modulates airway remodeling in a murine model of asthma.

RATIONALE: Previous studies have demonstrated that dysregulated coagulation and fibrinolysis contribute to the pathogenesis of asthma. OBJECTIVE: The role of procoagulant factor X in a murine model of ovalbumin (OVA)-induced asthma was investigated. METHODS: Biochemical, cellular, and physiologic in vivo and in vitro approaches were used to determine effects of factor X on the asthmatic response in mice. MEASUREMENTS AND MAIN RESULTS: Factor X transcript levels and factor Xa activity were increased in lungs of asthmatic mice challenged with OVA, compared with controls treated with phosphate-buffered saline. Factor X was highly expressed in bronchoalveolar lavage fluid macrophages from asthmatic mice. Treatment of mice with the factor Xa inhibitor fondaparinux during the last 4 wk of OVA challenge resulted in the attenuation of airway hyperresponsiveness but did not alter infiltration of inflammatory cells into the lung. There was a significant decrease in the thickness of the mucosal layer and in lung collagen deposition in fondaparinux-treated mice. In vitro investigations using human mucus-producing NCI-H292 cells indicated that exogenous factor Xa enhanced mucin production in a dose-dependent manner. Levels of amphiregulin, a protein that induces mucin production, were also increased in cells stimulated by factor Xa. CONCLUSIONS: The results of this study introduce a novel participant in the asthmatic response and indicate that factor Xa functions in airway remodeling in asthma by stimulating mucin production, through regulation of amphiregulin expression and collagen deposition.

Amphiregulin↗
PubMed2006

A novel function of plasminogen activator inhibitor-1 in modulation of the AKT pathway in wild-type and plasminogen activator inhibitor-1-deficient endothelial cells.

Cell proliferation, an event associated with angiogenesis, involves coordinated activities of a number of proteins. The role of plasminogen activator inhibitor-1 (PAI-1) in angiogenesis remains controversial. Utilizing proliferating PAI-1-/- endothelial cells (EC), the impact of a host PAI-1 deficiency on Akt activation was evaluated. Hyperactivation of Akt(Ser(P)473) was observed in PAI-1-/- EC, and this was probably due to enhanced inactivation of tumor suppressor PTEN, thus rendering the cells resistant to apoptotic signals. Higher levels of inactivated caspase-9 in PAI-1-/- EC led to lower levels of procaspase-3 and cleaved caspase-3, thereby promoting survival. These effects were reversed when recombinant PAI-1 was added to PAI-1-/- EC. Additional studies demonstrated that regulation of proliferation is dependent on its interaction with low density lipoprotein receptor-related protein. Thus, PAI-1 is a negative regulator of cell growth, exerting its effect on the phosphatidylinositol 3-kinase/Akt pathway and allowing controlled cell proliferation.

Animals↗
PubMed2006

A fibrinogen deficiency accelerates the initiation of LDL cholesterol-driven atherosclerosis via thrombin generation and platelet activation in genetically predisposed mice.

Mice with combined deficiencies of the low-density lipoprotein receptor (LDLR(-/-)) and the catalytic component of an apolipoprotein B-edisome complex (APOBEC1(-/-)) that converts apoB-100 to apoB-48 have been characterized, and this model of LDL cholesterol-driven atherosclerosis was applied to an investigation of the role of fibrinogen (Fg) in the genesis and progression of the plaque. LDLR(-/-)/APOBEC1(-/-)/FG(-/-) (L(-/-)/A(-/-)/FG(-/-)) triple-deficient mice presented more advanced plaque in their aortic trees and aortic sinuses at 24, 36, and 48 weeks of age compared to L(-/-)/A(-/-) mice, a feature that may result from enhanced platelet activation in these former mice. This is supported by the presence of hypercoagulability, increased CD61 and CD62P on resting platelets, and higher plasma soluble P-selectin in L(-/-)/A(-/-)/FG(-/-) mice as compared to L(-/-)/A(-/-), FG(-/-), or wild-type mice. The elevated higher molecular weight forms of von Willebrand factor (VWF) in L(-/-)/A(-/-)/FG(-/-) mice, revealed by increased VWF collagen binding activity, perhaps resulting from down-regulation of its cleaving metalloproteinase, ADAMTS13, further indicates enhanced platelet activation. Thus, the earlier arterial plaque deposition in L(-/-)/A(-/-)/FG(-/-) mice appears to contain a contribution from enhanced levels of thrombin and activated platelets, a synergistic consequence of an Fg deficiency combined with a high LDL cholesterol concentration.

APOBEC-1 Deaminase↗
PubMed2006

Plasminogen activator inhibitor-1 potentiates LPS-induced neutrophil activation through a JNK-mediated pathway.

Plasminogen activator inhibitor-1 (PAI-1), a member of the serine protease inhibitor superfamily, modulates fibrinolysis by interacting with proteolytic mediators, including urokinase plasminogen activator (uPA). Although the roles of uPA and PAI-1 in plasmin generation and the degradation of fibrin are well known, recent evidence also suggests that they can participate in acute inflammatory conditions that involve neutrophil activation. In the present experiments, we found that the addition of PAI-1 to LPS- stimulated neutrophils resulted in enhanced nuclear translocation of NF-kappaB and increased production of the proinflammatory cytokines IL-1beta, Tnf-alpha, and Mip-2. uPA and the kringle domain (KD) of uPA potentiated cytokine expression and NF-kappaB activation by neutrophils cultured with LPS, and had additive effects when combined with PAI-1. The c-Jun N-terminal kinase (JNK) was activated after exposure of resting neutrophils to PAI-1 or the uPA KD. Enhanced JNK activation, but not that of other kinases induced by LPS, was present in neutrophils cocultured with PAI-1 or uPA KD. Inhibition of JNK activation prevented the potentiation of expression of proinflammatory cytokines induced by PAI-1 or uPA KD in LPS stimulated neutrophils. These results demonstrate that PAI-1 and uPA KD enhance LPS-induced neutrophil responses through their effects on JNK mediated pathways.

Active Transport, Cell Nucleus↗
PubMed2006

Focal arterial inflammation is augmented in mice with a deficiency of the protein C gene.

Increased risk of thrombosis, with propitious conditions for fibrin deposition, along with upregulation of inflammation, are important factors that enhance plaque formation in atherosclerosis. Evidence supporting the role of anticoagulant protein C (PC) as an inflammatory agent has emerged, supplementing its well-known function as an anticoagulant. Thus, we sought to examine whether a PC deficiency would lead to an enhanced response to an acute arterial hyperplasic challenge. The presentation of early arterial inflammation was studied using a copper/silicone arterial cuff model of accelerated focal neointimal remodeling in mice with a heterozygous total deficiency of PC (PC+/-). Increased inflammation, cell proliferation, cell migration, fibrin elevation, and tissue necrosis were observed in the treated arteries of PC+/- mice, as compared to arteries of equally challenged age- and gender-matched WT mice. These results indicate that PC+/- mice subjected to this challenge displayed enhanced focal arterial inflammation and thrombosis, leading to larger neointimas and subsequent localized occlusion, as compared to their WT counterparts.

Animals↗
PubMed2005

Structure and function of the plasminogen/plasmin system.

Activation of the fibrinolytic system is dependent on the conversion of the plasma zymogen, plasminogen (Pg), to the serine protease plasmin (Pm) by the physiological activators urokinase-type Pg activator (uPA) or tissue-type plasminogen activator (tPA). The primary in vivo function of Pm is to regulate vascular patency by degrading fibrin-containing thrombi. However, the identification of Pg/Pm receptors and the ability of Pm to degrade other matrix proteins have implicated Pm in other functions involving degradation of protein barriers, thereby mediating cell migration, an important event in a number of normal e.g., embryogenesis, wound healing, angiogenesis, and pathological, e.g., tumor growth and dissemination, processes. Prior to the development of Pg-deficient mice, much of the evidence for its role in other biological events was based on indirect studies. With the development and characterization of these mice, and ability to apply challenges utilizing a number of animal models that mimic the human condition, a clearer delineation of Pg/Pm function has evolved and has contributed to an understanding of mechanisms associated with a number of pathophysiological events.

Animals↗
PubMed2004

Conservation of critical functional domains in murine plasminogen activator inhibitor-1.

Plasminogen activator inhibitor-1 is the main physiological regulator of tissue-type plasminogen activator in normal plasma. In addition to its critical function in fibrinolysis, plasminogen activator inhibitor-1 has been implicated in roles in other physiological and pathophysiological processes. To investigate structure-function aspects of mouse plasminogen activator inhibitor-1, the recombinant protein was expressed in Escherichia coli and purified. Five variant recombinant murine proteins (R76E, Q123K, R346A, R101A, and Q123K/R101A) were also generated using site-directed mutagenesis. The variant (R346A) was found to be defective in its inhibitory activity against tissue plasminogen activator relative to its wild-type counterpart. Enzyme-linked immunosorbent assay and surface plasmon resonance experiments demonstrated reduced vitronectin-binding affinity of the (Q123K) variant (K(D) = 1800 nm) relative to the wild-type protein (K(D) = 5.4 nm). Kinetic analyses indicated that the (Q123K) variant had a slower association (k(on) = 2.92 x 10(4) m(-1) s(-1)) to, and a faster dissociation from, vitronectin (k(off) = 5.3 x 10(-2) s(-1)), (wild-type k(on) = 1.03 x 10(6) m(-1) s(-1) and k(off) = 5.27 x 10(-3) s(-1)). The Q123K/R101A variant demonstrated an even lower vitronectin-binding ability. Low density lipoprotein receptor-related protein binding was decreased for the (R76E) variant. It was also demonstrated that the plasminogen activator inhibitor-1/vitronectin complex decreased the interaction of plasminogen activator inhibitor-1 with low density lipoprotein receptor-related protein. These results indicate that the complex interactions traditionally associated with different plasminogen activator inhibitor-1 functions apply to the murine system, thus showing a commonality of subtle functions among different species and evolutionary conservation of this protein. Further, this study provides additional evidence that the human hemostasis system can be studied effectively in the mouse, which is a great asset for investigations with gene-altered mice.

Animals↗
PubMed2003

Enhanced in vitro proliferation of aortic endothelial cells from plasminogen activator inhibitor-1-deficient mice.

A number of studies have identified a role for plasminogen activator inhibitor-1 (PAI-1) in regulating angiogenesis, although results from these investigations have been controversial. Among key cellular components of an angiogenic vessel are endothelial cells (ECs), which are known to express several components of the fibrinolytic system, including PAI-1. Thus, alterations in expression of this protein may have direct effects on cell functions involved in vascular development. In this study, ECs were isolated from sections of murine arterial trees from wild-type and PAI-1-deficient mice, and low passage (passages 3-4) homogeneous subpopulations of these cells were obtained by immunomagnetic absorption to antibodies against CD105/CD106. The homogeneity of these cells was further assessed by immunohistochemistry and quantitative real-time reverse transcription-PCR analysis of a number of EC markers. Comparative analyses of EC proliferation (one event associated with angiogenesis) in wild-type and PAI-1-deficient ECs demonstrated enhanced rates of cell growth for PAI-1-deficient cells relative to wild-type cells. Additional studies demonstrated similar levels of both vascular endothelial growth factor (VEGF) mRNA and protein and enhanced levels of VEGF receptor-1 (Flt-1) mRNA in PAI-1-deficient cells relative to wild-type cells. Immunohistochemical analyses indicated that phosphorylation of Akt was also enhanced in PAI-1-deficient cells, implicating VEGF-induced cell signaling alterations in PAI-1-deficient cells, the result of which may contribute to alterations in cell proliferation.

Animals↗
PubMed2003

Transcriptional profiling of the transition from normal intestinal epithelia to adenomas and carcinomas in the APCMin/+ mouse.

Mutations in the adenomatous polyposis coli (APC) gene that result in excessive beta-catenin-induced cell signaling are implicated in the risk of colon cancer. Although the mechanism of APC-mediated tumorigenesis is known, the pathways that translate beta-catenin signaling into tumor growth in vivo are undefined. To address this, gene expression profiles of normal intestinal epithelial cells were compared with those from adenomas and carcinomas from APC(Min/+) mice, a model of APC-related colorectal cancer. The gene expression profiles of adenomas and carcinomas were very similar, which is consistent with the theory that carcinomas progress from adenomas in this model system. Tumors had altered transcript abundance for members of several pathways that influence cell growth and proliferation including growth factors/receptors, molecules involved in apoptosis, and protein processing and catabolism enzymes. Comparison of gene expression between adenomas and carcinomas revealed nine differentially expressed transcripts. These included members of three growth-regulating pathways, and the results are consistent with the increased growth potential of carcinomas. SRY-box containing gene 17 (Sox 17), a negative regulator of beta-catenin signaling, and calbindin-D9K, a factor that enhances calcium transport, were more highly expressed in adenomas than carcinomas (approximately 4-fold and 15- to 22-fold, respectively). Transcript abundance for insulin-like growth factor binding protein 5, which mediates insulin-like growth factor function, was 2.6-fold greater in carcinomas. Because the changes in gene expression observed in this study are directly associated with a deficiency in APC, the data provide new insights into how loss of this important tumor suppressor translates into benign and malignant tumor growth.

Adenoma↗
PubMed2003

The fibrinolytic system in dissemination and matrix protein deposition during a mycobacterium infection.

The fibrinolytic system is known to play an important role in the inflammatory response to bacterial infections. In the present study, relationships between protein components of the fibrinolytic system and infectivity by Mycobacterium avium were analyzed. Infections were initiated through noninvasive intratracheal administration of M. avium 724 in mice individually deficient for plasminogen, tissue-type plasminogen activator, urokinase-type plasminogen activator, and urokinase-type plasminogen activator receptor, along with wild-type control mice. There were no differences in lung colony counts among all mouse genotypes throughout a 10-week infection. However, in tissue-type plasminogen activator and plasminogen-deficient mice an earlier dissemination of M. avium to other organs was observed. Nevertheless, the M. avium growth rates in the liver, spleen, and lung did not differ between the various mouse populations throughout a 10-week infection. Histochemical and immunohistochemical analyses at 5 and 10 weeks after infection demonstrated that plasminogen-deficient mice, compared to wild-type mice, had enhanced fibrin and fibronectin deposition, as well as increased neutrophil infiltration within liver granulomas. These results suggest that plasmin(ogen) plays a role in the turnover of extracellular matrix proteins within granulomas and has a limited effect in the early dissemination of M. avium from lungs. Thus, plasmin(ogen) functions in limiting progressive fibrosis in the granuloma during a chronic mycobacterial infection.

Animals↗
PubMed2003

Thrombospondin 1--a regulator of adenoma growth and carcinoma progression in the APC(Min/+) mouse model.

Thrombospondin 1 (TSP-1) is a multifunctional extracellular matrix protein that is an endogenous regulator of tumor angiogenesis. The effects of TSP-1 on adenoma formation and development into cancerous lesions has been evaluated in the Min(/+) (multiple intestinal neoplasia) mouse model. These mice develop multiple adenomas in the small intestine due to a mutation in the homologous APC (adenomatous polyposis coli) gene. As in its human counterpart, these adenomas may progress to carcinomas. Intestines of APC(Min/+) mice were dissected and histologic evaluation of adenomas was then conducted. Significant increases in vascularization and proliferation were observed in adenomatous, as compared with normal, mucosa. TSP-1 immunostaining revealed significant decreases in the number and intensity of positive cells in adenomas, as compared with normal mucosa. TSP-1 scores were inversely correlated with vascularity and proliferation rate. Cross breeding of mice homozygous for a deletion of the TSP-1 gene (TSP-1(-/-)) with mice heterozygous for the APC gene mutation (APC(Min/+)), resulted in animals that showed a significant increase in adenoma number and diameter. Also, histopathological examination of these adenomas showed accelerated dysplasic changes, carcinoma in situ and early invasion, compared with their APC(Min/+) littermates. Moreover, a significant decrease of TUNEL-positive cells was observed in intestinal adenomas of TSP-1(-/-)/APC(Min/+) mice. This study reports the first in vivo impact of TSP-1 during early stages of tumor initiation and development in an intestinal carcinogenesis model and demonstrates that TSP-1 affects both angiogenesis and tumor cell apoptosis.

Adenoma↗
PubMed2002

Fibrinogen stabilizes placental-maternal attachment during embryonic development in the mouse.

In humans, maternal fibrinogen (Fg) is required to support pregnancies by maintaining hemostatic balance and stabilizing uteroplacental attachment at the fibrinoid layer found at the fetal-maternal junction. To examine relationships between low Fg levels and early fetal loss, a genetic model of afibrinogenemia was developed. Pregnant mice homozygous for a deletion of the Fg-gamma chain, which results in a total Fg deficiency state (FG(-/-)), aborted the fetuses at the equivalent gestational stage seen in humans. Results obtained from timed matings of FG(-/-) mice showed that vaginal bleeding was initiated as early as embryonic day (E)6 to 7, a critical stage for maternal-fetal vascular development. The condition of afibrinogenemia retarded embryo-placental development, and consistently led to abortion and maternal death at E9.75. Lack of Fg did not alter the extent or distribution pattern of other putative factors of embryo-placental attachment, including laminin, fibronectin, and Factor XIII, indicating that the presence of fibrin(ogen) is required to confer sufficient stability at the placental-decidual interface. The results of these studies demonstrate that maternal Fg plays a critical role in maintenance of pregnancy in mice, both by supporting proper development of fetal-maternal vascular communication and stabilization of embryo implantation.

Abortion, Spontaneous↗
PubMed2002

Gene targeting of components of the fibrinolytic system.

A number of in vitro and in vivo observations have implicated components of the fibrinolytic system in events associated with diverse physiological and pathophysiological processes, ranging from embryo implantation to cancer. Advances in gene targeting technology have led to the generation of mice deficient for components of the fibrinolytic system. Remarkably, these animals survive to adulthood with few spontaneous life threatening events. Thus, these mice are valuable resources for in vivo studies, not only for hemostasis-related research, but also for the relationships of these genes to other disease states associated with cellular growth and mobility, along with angiogenesis, vascular remodeling, inflammation, wound healing, and tumor growth and dissemination.

Animals↗