Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies have shown that cytokine-dependent eosinophils undergo apoptosis, yet the mechanisms governing this phenomenon remain obscure. Fas antigen is a transmembrane glycoprotein belonging to the tumor necrosis factor receptor family. Cross-linking of Fas antigen in numerous cell types leads to apoptosis. In the present study, we examined the potential role of Fas antigen in the apoptosis of purified blood eosinophils from healthy donors. Cytokine-deprived eosinophils exhibited a time-dependent loss in viability, accompanied by an increase in the number of apoptotic nuclei and in the expression of Fas antigen and its mRNA, as shown by flow cytometry and reverse transcriptase-polymerase chain reaction, respectively. Cross-linking of Fas antigen with an agonistic anti-Fas monoclonal antibody (MoAb) induced a dose- and time-dependent increase in the number of apoptotic nuclei. Furthermore, using an in vitro coculture system, we showed engulfment of anti-Fas MoAb-treated eosinophils by monocyte-derived macrophages. Finally, incubation of eosinophils with the corticosteroid, dexamethasone, induced apoptosis and augmented that triggered by anti-Fas MoAb. Together, these observations suggest that Fas antigen expression and activation is involved in the apoptosis of human eosinophils and may contribute to the resolution of inflammatory allergic reactions in which eosinophil accumulation is a prominent feature.
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PMID:Fas-mediated apoptosis in cultured human eosinophils. 863

Stromal cell lines were established by irradiating adherent layers of bone marrow and spleen cells in Dexter-type long-term culture with X-rays. Some of these cell lines support myelopoiesis and/or B lymphopoiesis in vitro. Furthermore, the characteristics of these stromal cell lines were studied. Cytokine activity was detected in the conditioned media from all hematopoietic-supportive and non-supportive stromal cells. Quantitative reverse transcriptase-polymerase chain reaction analysis revealed that the mRNAs of macrophage colony-stimulating factor and stem cell factor, but not that of Interleukin-3, were detectable in all the hematopoietic-supportive and non-supportive stromal cell lines. The transcripts of granulocyte colony-stimulating factor, interleukin-6, interleukin-7, and leukemia inhibitory factor were expressed in a wide variety of cell lines. Most stromal cell lines synthesized mRNA of c-mpl, the ligand of which stimulates megakaryopoiesis and thrombopoiesis. These observations indicate that the pattern of mRNA expression of cytokines is not correlated with the hematopoietic-supportive ability of stromal cell lines. There was a significant difference in the efficiency of adhesion of lineage marker-negative bone marrow cells to fibroblasts and stromal cell lines. This appears to be correlated with the hematopoietic-supportive ability of the stromal cell lines.
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PMID:Characterization of murine stromal cell clones established from bone marrow and spleen. 865 75

In this work, we present evidence that enriched human peripheral blood T lymphocytes, depleted of contaminating monocytes, rapidly express tumor necrosis factor alpha (TNF-alpha) mRNA when exposed to low doses of gamma-irradiation. In total PBL, TNF-alpha mRNA accumulation increased threefold as early as 30 minutes following exposure to 4 Gy and then declined to the baseline level by 3-5 h, as measured by the reverse transcriptase-polymerase chain reaction (RT-PCR). The increase in TNF-alpha mRNA was also observed in populations of enriched T cells and decreased when the dose of irradiation was increased to 10 Gy, strongly suggesting that T lymphocytes, the most radiosensitive cells of the body, contributed directly to the increase of TNF-alpha mRNA. A good correlation was found between mRNA expression and TNF-alpha protein secretion. Interestingly, a eightfold increase in glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA accumulation was also detected in both PBL and enriched T cells irradiated at 4 Gy for 3 h compared with unirradiated cells. This irradiation effect was almost completely abolished, however, following exposure to 10 Gy. Together these data suggest that T cells are responsible for the irradiation-induced expression of TNF-alpha and GAPDH.
J Interferon Cytokine Res 1996 May
PMID:Induction of tumor necrosis factor alpha expression in human T lymphocytes following ionizing gamma irradiation. 872 80

The functional properties of intraepithelial lymphocytes (IEL) in normal human jejunum, ileum, and colon were investigated. Cytokine mRNA expression in IEL and enterocytes was determined by reverse transcriptase-PCR and IFN-gamma+ IEL by immunohistochemistry. Polyclonal activators were used to study proliferation and IFN-gamma secretion of IEL, and an anti-CD3-mediated redirected cytotoxicity assay was used to determine the lytic potential of IEL. Freshly isolated IEL at all three gut levels expressed mRNA for IL-1 beta, IL-2, IL-8, IFN-gamma, and TNF-alpha. Approximately 10% of IEL produced IFN-gamma, suggesting that IEL are immunologically active in vivo, performing similar functions along the intestine. IEL could be stimulated further in vitro to express IL-10, TNF-beta, and TGF-beta 1, while no Th2-type cytokines were induced, suggesting suppressive and cytolytic functions for IEL. All three jejunal IEL subpopulations (CD4-CD8-TCR-gamma delta+, CD4+TCR-alpha beta+, CD8+TCR-alpha beta+) expressed the same four cytokines, IL-2, IL-8, IFN-gamma, and TNF-alpha, indicating that CD4+TCR-alpha beta+ IEL are Th1 cells and that TCR-gamma delta+ IEL and CD8+TCR-alpha beta+ IEL include cytotoxic effector cells. Indeed, freshly isolated jejunal IEL displayed cytolytic activity. IEL were induced to proliferation by anti-CD3/TCR complex mAbs and leukoagglutinin, but not by Con A. There was no correlation between the magnitude of the proliferative response and the amounts of secreted IFN-gamma. Enterocytes expressed IL-1 beta and IL-8, and sometimes TNF-alpha. Although jejunal enterocytes express HLA-DR and hsp60, Ag presentation by these cells may induce anergy since their cytokine profile is different from that of classical APCs.
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PMID:Intraepithelial lymphocytes in human gut have lytic potential and a cytokine profile that suggest T helper 1 and cytotoxic functions. 875 11

The mechanisms of wound healing in the gut are poorly understood but are mediated by cytokines in other tissues. In this study we wanted to determine which cytokines were expressed after nonspecific colonic injury, the kinetics of that expression, and how cytokine expression correlated with tissue histology. At 0, 4, 8, 12, 24, 48, and 72 h after intrarectal administration of 3% acetic acid to C3H/HeJ mice, their colons were removed for histology, organ culture, and RNA extraction. Cytokine mRNA expression for various cytokines was assessed by reverse transcriptase-polymerase chain reaction with primers specific for each cytokine. Cytokine production in organ cultures was measured with bioassays. Shortly after colonic injury and during colonic regeneration, proinflammatory cytokines such as interleukin-1 beta (IL-1 beta), IL-6, tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein (MIP), and transforming growth factor-beta (TGF-beta) were expressed. In contrast, expression of T cell-derived cytokines was not detected at any time point. Cytokines such as IL-1 beta, IL-6, IL-10, TNF-alpha, and MIP-1 are important mediators of tissue repair and restitution after nonspecific colonic injury and may subserve a similar role in human colitis.
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PMID:Kinetics of cytokine expression during healing of acute colitis in mice. 876 Jan 16

The purpose of this study was to describe cytokine profiles of human neonatal pulmonary cells isolated by tracheal aspiration (TA) and by deep pulmonary lavage (DPL). We hypothesized that mRNA phenotyping, using the technique of reverse transcriptase polymerase chain reaction (RT-PCR), would reveal differences in cytokine expression patterns between cells from proximal and distal airway compartments. We reasoned that cells derived by DPL may reflect pathogenic pathways indicative for the development of bronchopulmonary dysplasia in the premature infant. Here we have described the detection of mRNA for IL-1 alpha, IL-1 beta, IL-6, IL-8, and tumor necrosis factor-alpha. Fourteen paired TA and DPL samples from six premature infants were collected at 1, 7, or 28 d of age. Two of 14 samples were negative for beta-actin (a ubiquitous mRNA) by RT-PCR and were excluded from further analysis. Each of the remaining 12 samples expressed IL-8. Furthermore, each cytokine could be expressed by TA or DPL cells. Cytokine mRNA phenotype profiles were found to differ between TA and DPL cells in four of five paired samples. Our results show that cells retrieved from these two pulmonary compartments are sources for these cytokines and suggest that RT-PCR of TA/DPL cells can be used to test hypothetical predictive markers for the development of bronchopulmonary dysplasia.
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PMID:Differential cytokine mRNA expression by neonatal pulmonary cells. 882 95

The expression of transforming growth factor beta 1 and beta 2 (TGF-beta 1 and beta 2) in aortic and venous tissue from male New Zealand White rabbits, at selected time intervals after birth, was examined by the reverse transcriptase polymerase chain reaction. Stable levels of TGF-beta 1 were found in all segments derived from the aortic arch and descending aorta at each time interval. However, increasing amounts of TGF-beta 2 transcripts were observed for the aortic arch from day 4, with peaks occurring between 1 and 6 months of age, followed by progressively decreasing levels thereafter. TGF-beta 2 transcripts in the descending aorta generally did not change significantly over time. TGF-beta transcripts manifested a significantly lower expression in the vena cava than in aortic segments. Histological analysis of the vascular tissue showed cellular hyperplasia (2.5-fold greater prevalence of nuclei per field) in the aortic arch media at 1 month of age as compared with nuclei per field at 12 months and increasing thickness of the aortic arch media with time. No significant differences in relative collagen concentrations were observed among the aortic and vena cava segments. These results suggest that these TGF-beta isoforms may participate in the physiological induction and differentiation of arterial and venous tissue during early normal vascular maturation.
Cytokine 1996 Sep
PMID:Different temporal and spatial distribution of TGF-beta 1 and TGF-beta 2 in rabbit vascular tissue: potential role in normal vessel growth and maturation. 893 78

This study analysed the effects of immunoregulatory cytokines on uroepithelial cell cytokine responses. The A-498 human kidney cell line was treated with the interleukins IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, interferon gamma (IFN-alpha) and transforming growth factor beta (TGF-beta 1). Secreted IL-6 and IL-8 were quantitated by enzyme-linked immunoabsorbent assay (ELISA) and bioassay; IL-6 and IL-8 mRNA species were quantitated by reverse transcriptase polymerase chain reaction (RT-PCR). IL-4, IL-13, IFN-gamma, and TGF-beta 1, but not IL-2, IL-5, IL-10 or IL-12, stimulated IL-6 secretion. At high concentrations, IL-4 and IL-13 stimulated low levels of IL-8 secretion. Immunoregulatory cytokines were analysed for their ability to modify the A-498 cells' IL-6 and IL-8 secretion in response to Escherichia coli. IL-5, IL-12, IL-13 and TGF-beta 1 additively enhanced the bacterially induced IL-6 secretion, but they did not affect IL-8 secretion. The strongest affects on uroepithelial cell IL-6 and IL-8 responses in the presence of bacteria were observed in conjunction with IL-4 and IFN-alpha. IL-4 induced IL-6 production in synergy with E. coli. IFN-alpha both enhanced and inhibited IL-6 and IL-8 responses in combination with E. coli, depending on the order of stimulant addition. The results demonstrate that immunoregulatory cytokines can modify the uroepithelial cell responses to bacteria in vitro. In this way, T cells may regulate the cytokine responses of uroepithelial and possibly other mucosal epithelial cells in vivo.
Cytokine 1996 Sep
PMID:Immunoregulatory cytokines modify Escherichia coli induced uroepithelial cell IL-6 and IL-8 responses. 893 79

Whole blood cultures are used to study cytokine stimulation and release ex vivo. In the present study this method was compared with a more direct approach and a quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was used to assess mRNA expression for IL-1 beta and tumour necrosis factor alpha (TNF-alpha) and mRNA in whole blood. Stimulation of whole blood from normal donors with lipopolysaccharide (LPS) at various time intervals showed a parallel rise of immunogenic IL-1 beta and TNF-alpha as well as a rise of mRNA expression for IL-1 beta and TNF-alpha with peak levels for IL-1 beta after 4-6 h stimulation and for mRNA TNF-alpha expression after 2 h stimulation. These methods were used to explore cytokine production during the course of typhoid fever and after a 5 km run. In both conditions circulating cytokine concentrations were not influenced, but the TNF-alpha and IL-1 beta mRNA gene expression in circulating whole blood cells was increased in patients with typhoid fever. The LPS-stimulated production of TNF-alpha and IL-1 beta was decreased in both but there was no change for the mRNA content in whole blood for these cytokines. These findings demonstrate that RT-PCR is an attractive method to study the gene expression of cytokines in whole blood, an increased TNF-alpha and IL-1 beta gene expression is present in typhoid fever, and that the LPS stimulated downregulation of cytokines in exercise and typhoid fever may be mediated by post-transcriptional processes.
Cytokine 1996 Sep
PMID:A semi-quantitative reverse transcriptase polymerase chain reaction method for measurement of MRNA for TNF-alpha and IL-1 beta in whole blood cultures: its application in typhoid fever and exentric exercise. 893 86

In this study, we provide the first report on the production of granulocyte-macrophage colony-stimulating factor (GM-CSF) by human thyroid epithelial cells. Primary cultures of highly purified thyrocytes and thyroid-derived fibroblasts (n = 3) and three thyroid anaplastic and one largely papillary carcinoma cell lines were exposed to different potent GM-CSF stimulators, employing interleukin 1 alpha (Il-1 alpha) and tumour necrosis factor-alpha (TNF-alpha). Cytokine mRNA levels were monitored by semi-quantitative reverse transcriptase-PCR including an internal heterologous competitor fragment after 3, 6 and 18 h of culture. Culture supernatants were assayed for GM-CSF using a highly sensitive ELISA (detection limit < or = 0.5 pg/ml) after 24 h. Basal GM-CSF mRNA expression was higher in fibroblasts and SW 1736 cells compared with thyrocytes, C 634, 8505 C and HTh 74 cells. GM-CSF was spontaneously secreted by fibroblasts (means +/- S.E.M.; 43 +/- 15 pg/ml), SW 1736 (59 +/- 4 pg/ml), HTh 74 (34 +/- 4 pg/ml) and C 643 cells (12 +/- 1 pg/ml) but not by thyrocytes and 8505 C cells. Treatment with Il-1 alpha (10 U/ml) resulted in a marked increase of GM-CSF mRNA within 3 h and an increase or induction of protein expression in thyrocyte (2350 +/- 214 pg/ml), fibroblast (5242 +/- 1400 pg/ml), SW 1736 (20016 +/- 280 pg/ml) and C 643 cultures (1285 +/- 79 pg/ml). Stimulation with TNF-alpha (10 U/ml) yielded divergent results. No significant increase of GM-CSF mRNA or protein expression was found in thyrocytes although TNF-alpha receptor expression in these cells is well documented. Stimulation with TNF-alpha resulted in an increased GM-CSF production in fibroblasts (361 +/- 14 pg/ml), HTh 74 (148 +/- 51 pg/ml) and SW 1736 cultures (235 +/- 43 pg/ml). TSH (10 mU/ ml) did not stimulate GM-CSF secretion in thyrocytes and HTh 74 cells, both expressing the TSH receptor. Phorbol 12-myristate 13-acetate (10 ng/ml) enhanced GM-CSF mRNA and protein levels in all cell types investigated. Our data suggest that both thyrocytes and fibroblasts synthesize GM-CSF in response to Il-1 alpha, but only fibroblasts respond to TNF-alpha with a significant increase in GM-CSF. Anaplastic thyroid carcinomas are potential GM-CSF producers.
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PMID:Differential regulation of granulocyte-macrophage colony-stimulating factor mRNA and protein expression in human thyrocytes and thyroid-derived fibroblasts by interleukin-1 alpha and tumor necrosis factor-alpha. 895 88


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