Investigations into the influence and role of tissue factor in the pathogenesis of myocardial hypertrophy

Recently it has been demonstrated that tissue factor (TF) plays an important role in the induction and/or progression of cardiac hypertrophy. The aim of this thesis was to examine the relationship between TF and the onset of cardiac hypertrophy. Cardiac hypertrophy was achieved by aortic constriction in male Sprague-Dawely rats. TF levels increased in cardiac tissue but not in isolated cardiomyocytes suggesting another cellular site of TF expression. In contrast, tissue factor pathway inhibitor, (TFPI), was transiently up-regulated in cardiomyocytes potentially to counteract the effects of TF.Stimulation of H9c2 cardiomyocytes with exogenous TF resulted in the up-regulation of mechano growth factor. Incubation of the cells with TF alone up-regulated atrial natriuretic factor (ANF) expression, whilst the presence of the TF-associated proteases, factor VIla and factor Xa, suppressed this effect, suggesting that contact between TF and blood within the heart can exacerbates the hypertrophic response.Moderate concentrations of TF were found to induce proliferation In H9c2 cardiomyocytes, while high concentrations of TF resulted in increased cellular apoptosis as detected by caspase-3 activation but via a p53-independent mechanism. In addition, supplementation of TF with proteolytically active factors, VIla and Xa, partially abrogated this apoptotic effect. These data suggest that the expression of moderate concentrations of TF, induced by pressure overload observed during early hypertrophy, result in an enhanced rate of cellular turnover, and combined with hypertrophic growth, leads to alterations in heart structure. In contrast, higher concentrations of TF at later stages of disease can deplete the cardiomyocytes. In conclusion, TF appears to function as a pro-inflammatory mediator which is upregulated at the onset of hypertrophy and is capable of influencing the progression of the disease through altering the function of cardiomyocytes

European Language Social Science Thesaurus (ELSST): issues in designing a multilingual tool for social science researchers

Proceedings of the Workshop CHAT 2011: Creation, Harmonization and Application of Terminology Resources. Editors: Tatiana Gornostay and Andrejs Vasiļjevs. NEALT Proceedings Series, Vol. 12 (2011), 11-15. © 2011 The editors and contributors. Published by Northern European Association for Language Technology (NEALT) http://omilia.uio.no/nealt . Electronically published at Tartu University Library (Estonia) http://hdl.handle.net/10062/16956

Cardiomyocyte specific expression of the nuclear matrix protein, CIZ1, stimulates production of mononucleated cells with an extended window of proliferation in the postnatal mouse heart.

Myocardial injury in mammals leads to heart failure through pathological cardiac remodelling that includes hypertrophy, fibrosis and ventricular dilatation. Central to this is inability of the mammalian cardiomyocyte to self-renew due to entering a quiescent state after birth. Modulation of the cardiomyocyte cell-cycle after injury is therefore a target mechanism to limit damage and potentiate repair and regeneration. Here we show that cardiomyocyte specific over-expression of the nuclear-matrix associated DNA replication protein, CIZ1, extends their window of proliferation during cardiac development, delaying onset of terminal differentiation without compromising function. CIZ1 expressing hearts are enlarged, but the cardiomyocytes are smaller with an overall increase in number, correlating with increased DNA replication after birth and retention of an increased proportion of mono-nucleated cardiomyocytes into adulthood. Furthermore, these CIZ1 induced changes in the heart reduce the impact of myocardial injury, identifying CIZ1 as a putative therapeutic target for cardiac repair

Investigations into the influence and role of tissue factor in the pathogenesis of myocardial hypertrophy

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Identification and characterization of glial and neuronal cells in vitro and in bone marrow

This study attempts to identify and characterize glial cells and neuronal cells in avian brain and mammalian bone marrow, respectively. The project has four major objectives: (a) to culture and maintain avian glial and neuronal cells up to 20 days, (b) to examine cell cultures using selective cytological markers for gliaj and nerve cells, (c) to investigate the effects of the steroid hormone oestrogen on the growth of glial cells and (d) to investigate the presence of neuronal cell bodies in mammalian bone marrow using alternative approaches. Glial cells were grown for 20 days, supplemented with oestrogen after the 10th day. Control cultures were grown for 20 days without oestrogen supplement. Consequently, the cultures were subjected in GFAP, Gal C, NSE and PR antibodies. The results have shown that oestrogen had no significant effect on the development of the cells. Staining of glial cells with Haematoxylin and Eosin and taking measurements for cell diameter, nucleus diameter and number of projections, the results demonstrated significant differences in the nucleus diameter and the number of projections in the cells treated with estrogen compared to non-treated cells. The neuronal cells were cultured for 10-15 days. Comparing to the glial cell cultures, it was found that neuronal cells were more difficult to grow and more vulnerable to contamination even when a modified medium was used to grow the cells. However, the results show that they can express immunoreactivity for NSE but not for either GFAP or Gal C. The expression of NSE was crucial since it positively showed that the cells grown were neuronal cells in nature. The final aim of this study was to identify and localize the innervation pattern within the bone marrow and the possible existence of neuronal cells bodies. Using either male or female young mice as animal model, perfused femurs were decalcified, sectioned with a cryostat and subsequently, stained using immunocytochemistry for different markers, including Gal C, GFAP, NSE and antityrosine hydroxylase. Furthermore, sections were subjected to silver stain, which is capable in recognising neuronal cells bodies. In addition, Dii neuronal tracer was applied to post-fixed tissue for the same reason. The results showed that the tissue had NSE immunoreactivity revealing an extensive network of neuronal fibers running among the bone marrow. However, there was no expression of Gal C, GFAP or antityrosine hydroxylase. The results also revealed the presence of neuronal fibers within the bone marrow, running alongside with blood vessels. Unfortunately, no neuronal cell bodies were found in this present investigation. In conclusion, the results of this study have shown that (1) oestrogen can have marked effects on the morphology of glial cells and (2) neuronal fibers are present in bone marrow and they seem to be located near blood vessels

Investigation of the mechanisms of tissue factor-mediated evasion of tumour cells from cellular cytotoxicity

Aims We previously reported that overexpression of tissue factor (TF) protected HT29 tumour cells from cellular cytotoxicity through a mechanism requiring the presence of the cytoplasmic domain of TF. In this investigation the mechanism of TF-mediated immune evasion has been examined. Methods The influence of alanine-substitution at Ser253 and Ser258 of TF (TFAla253 and TF (Ala258)) on the induction of cytotoxic evasion, as well as expression of vascular cell adhesion molecule-1 and intra-cellular adhesion molecule-1 (VCAM-1 and ICAM-1) was investigated. Moreover, we examined the effect of transfection of four 20-mer peptides, corresponding to the C-terminal residues of TF, with different phosphorylation states, on promotion of evasion from cell cytotoxicity. Results Cells overexpressing TFAla258 and to a lesser extent overexpressing TFAla253, exhibited a reduced ability to evade cellular cytotoxicity compared to cells overexpressing the wild-type TF. Furthermore, the increase in protection acquired was greatest on transfection of Ser258-phosphsorylated form of the cytoplasmic peptide, lower in double-phosphorylated and Ser253-phosphorylated peptides respectively, and lowest in the unphosphorylated form. Finally, the expression of VCAM-1 mRNA as well as surface antigen was reduced on overexpression of TFwt but was partially reverted in the cells transfected to overexpress TFAla253 or TFAla258. Conclusions These data show that the phosphorylation of TF at Ser258 and to a lesser extent Ser253, plays an essential role in the protective influence of TF on immune evasion by tumour cells, and that the mechanism could involve the downregulation of key surface antigens, such as adhesion proteins, involved in cell:cell interaction

IL-1β Down-Regulates ADAMTS-13 mRNA Expression in Cells of the Central Nervous System.

ADAMTS-13 is the Von Willebrand factor (vWF) cleaving protease, responsible for the cleavage and down-regulation of the pro-thrombotic properties of ultra large VWF multimers. It is expressed predominantly by the hepatic stellate cells of the liver, but is also found to be expressed in other tissues, including brain. Reduced ADAMTS-13 is associated with a variety of thrombotic microangiopathies. Since the cellular origin and regulation of ADAMTS-13 expression in the brain is unknown, we aimed to investigate this in four different central nervous system (CNS)-derived cell lines, SHSY-5Y (human neuroblastoma), U373 (human astroglioma), CHME-3 (human foetal microglia) and hCMEC/D3 (adult human brain endothelial cells). All cell lines expressed ADAMTS-13 mRNA constitutively with neuroblastoma cells showing the highest expression. Interleukin (IL)-1β down-regulated ADAMTS-13 mRNA expression in astroglioma cells and microglial cells whereas TNF and IL-6 treatment showed no significant differences in ADAMTS-13 mRNA expression in any cell line tested. ADAMTS-13 protein expression was reduced in a dose-dependent manner only in astroglioma cells following stimulation by IL-1β. The ability of IL-1β to significantly reduce ADAMTS-13 mRNA expression in human microglia and astroglioma cells suggests a role in the haemostasis of the local microenvironment under inflammatory conditions. This is the first report of ADAMTS-13 expression in cells of the CNS; however, its function remains to be determined

Differential induction of cellular proliferation, hypertrophy and apoptosis in H9c2 cardiomyocytes by exogenous tissue factor

Recent evidence has shown that prolonged exposure to exogenous tissue factor (TF) can alter the cellular functions of cardiomyocytes resulting in cardiac dysfunction. The effect of TF may arise from local inflammation within or in the vicinity of the heart. The aim of this study was to investigate the effect of TF on cardiomyocyte proliferation and growth. H9c2 rat cardiomyocytes were exposed to a range of concentrations of recombinant TF (rTF) (1.3-52 ng/ml) for up to 10 days and the outcome on cell proliferation and induction of apoptosis measured. At lower concentrations examined (1.3 ng/ml), rTF had a proliferative influence on the H9c2 cells. In contrast, elevated concentrations of rTF (52 ng/ml) induced cellular apoptosis as indicated by increased caspase-3 activity and nuclear localisation of p53. Moreover, incubation with intermediate concentrations of rTF (13 ng/ml) resulted in an initial increase in proliferation but subsequently, led to cellular apoptosis by day 7 of the incubation. In order to determine if these effects induced hypertrophic cell growth, expression of mechano-growth factor (MGF) was analysed. Incubation of cells with rTF resulted in enhanced expression of MGF particularly at the intermediate concentrations of rTF (13 ng/ml) as well as mean cellular transverse diameter. In addition, there was a rapid increase in the expression of atrial natriuretic factor (ANF) in the cells, on incubation with rTF but diminished rapidly when exposed to higher concentrations of rTF. These data indicate that exposure to increasing concentrations of rTF can accelerate the rate of cardiomyocyte turnover which may ultimately lead to depletion of viable cells within the heart. Moreover, at lower concentrations of rTF, the induction of cell proliferation together with hypertrophic markers indicates that rTF may contribute to the induction and progression of cardiac hypertrophy

Differential functions of tissue factor in the trans-activation of cellular signalling pathways

In this study we examined the ability of tissue factor (TF) alone, or in conjunction with factor VIIa, factor Xa and TFPI in activating a number of key signalling pathways associated with cellular growth, stress and differentiation responses in human endothelial cells. We used luciferase reporter systems to demonstrate the activation of p42/44 MAPK by the TF-FVIIa complex, mediated via the PAR1 receptor. TF alone was capable of interacting with the cell surface and was sufficient to activate the JNK-SAPK pathway and subsequently AP-1, but the level of activation was enhanced by the activity of FXa on PAR1 and 2. Furthermore, the phosphorylated form of the transmembrane-cytoplasmic domain of TF was directly responsible for activation of these pathways. CREB activation occurred in response to TF-FVIIa in a non-protease dependent manner but was lowered on addition of FXa. Finally, NFκB activation occurred in response to FVIIa or FXa, with the latter exhibiting higher levels of activation. In conclusion, we have shown that TF is capable of activating differing signalling pathways, via more than one mechanism. The differential influence of TF is modified depending on the presence of other coagulation factors and ultimately acts as a deciding factor in the determination of cellular fate. © 2006 Elsevier Ireland Ltd. All rights reserved