Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Increasing evidence suggests the existence of polarized human T cell responses described as Th1-type (promoting cell-mediated immunity) and Th2-type (promoting humoral immunity), characterized by a dominant production of either interferon-gamma (IFN-gamma) or IL-4, respectively. Little is known about the intratumoural activation of infiltrating lymphocytes (TIL) in human gliomas. Therefore, we assessed fresh TIL at cellular and molecular levels to find out if they were activated and polarized into a type 1 or 2 immune response. Flow cytometry analysis of TIL revealed that the major subset was made of T lymphocytes. Double labelling with alpha-CD3 and adhesion/ activation markers revealed T cell subsets expressing CD49a, CD49b, CD54, and CD15, some of which were almost absent in autologous T peripheral blood lymphocytes (T-PBL). Furthermore, the proportions of T-TIL expressing CD56, CD65, or CD25 were several-fold higher than in T-PBL. Intratumoural functional activation of TIL was tested by semiquantitative assessment in relative units (RU) of lymphokine gene activation with mRNA reverse transcriptase-polymerase chain reaction (RT-PCR). All TIL populations except one significantly expressed IL-4 1 to 2 logs of RU above healthy PBL baseline. Similarly, all patients expressed granulocyte-macrophage colony-stimulating factor (GM-CSF) in a range comparable to IL-4. However, most TIL populations did not express IFN-gamma, IL-2, and tumour necrosis factor-beta (TNF-beta) at higher levels than healthy normal PBL. The increase proportion of T cells expressing activation markers and the consistent detection of significant IL-4 and GM-CSF lymphokine gene activation in TIL populations suggested a predominant type 2 intratumoural immune response that does not promote cell-mediated tumouricidal activity and may contribute to the inefficiency of the antiglioma immune response.
...
PMID:Predominance of a type 2 intratumoural immune response in fresh tumour-infiltrating lymphocytes from human gliomas. 870 44

Modulation of intercellular adhesion molecule-1 (ICAM-1) expression may be a basic mechanism by which alveolar macrophages (AMs) regulate the inflammatory process in the lung in response to local stimuli. As a model for studying the anti-inflammatory activity of drugs on human AMs, we investigated the effects of fusafungine, an antibiotic for local use by aerosol with anti-inflammatory properties, and that of the glucocorticoid dexamethasone, on ICAM-1 expression induced in vitro by recombinant interferon-gamma (rIFN-gamma). ICAM-1 protein expression was studied on AMs by means of flow cytometry with an anti-CD54 monoclonal antibody; messenger ribonucleic acid (mRNA) levels were determined by reverse transcriptase-polymerase chain reaction (RT-PCR). ICAM-1 was expressed before culture on 21% of bronchoalveolar lavage (BAL) cells, with low intensity. Culture for 24 h with rIFN-gamma resulted in a significant increase in ICAM-1 protein expression (82% of cells were strongly positive). Fusafungine significantly inhibited rIFN-gamma-induced ICAM-1-protein expression on AMs in a concentration-dependent fashion. The mechanism of ICAM-1 downregulation was mainly post-transcriptional, but also partly transcriptional. By contrast, dexamethasone did not influence rIFN-gamma-induced ICAM-1 expression. This in vitro model using human AMs should prove useful for investigating the cellular and molecular targets of anti-inflammatory drugs.
...
PMID:Modulation of ICAM-1 expression in human alveolar macrophages in vitro. 873 5

Calcium-dependent signal transduction is essential to the induction of cytokine expression by stimuli acting through the T cell receptor. In vitro, the immunosuppressant cyclosporine (CyA) blocks this pathway by inhibition of calcineurin (CN) phosphatase activity. But in vivo, patients on CyA have only 50% inhibition of CN and can mount cytokine responses. To simulate this state of partial inhibition, we studied the responses of human peripheral blood mononuclear leucocytes (PBL) in vitro at low CyA concentrations. PBL were challenged in vitro with calcium ionophores or anti-CD3 monoclonal antibody. The induction of IFN-gamma (interferon-gamma) and IL-2 (interleukin 2) steady-state mRNA was studied by Northern blotting and reverse transcriptase-polymerase chain reaction. IFN-gamma was assessed in a radiolabelled antibody binding assay or by ELISA (enzyme-linked immunosorbent assay). CN was assessed by dephosphorylation of a 32P-serine labelled 19 amino acid substrate. CyA inhibited CN with an IC50 (concentration giving 50% inhibition) of 10 ng/ml (95% confidence interval, CI = 8-13 ng/ml). Likewise, the induction of IFN-gamma and IL-2 mRNA by calcium ionophore A23187 was inhibited with IC50 of 14 ng/ml (95% CI = 8-27 ng/ml) and 32 ng/ml (95% CI = 5-178 ng/ml), respectively, while the IC50 for inhibition of IFN-gamma protein secretion was 8 ng/ml (95% CI = 9-18 ng/ml). Partial inhibition of CN also altered the threshold for IFN-gamma induction. CyA 10 ng/ml inhibited IFN-gamma induction by anti-CD3 monoclonal antibody OKT3 significantly more at low OKT3 concentrations (10 ng/ml, mean +/- SEM = 72 +/- 9% inhibition) compared to high OKT3 concentrations (1000 ng/ml, 47 +/- 6%, p < 0.01). Similar results were seen using high and low concentrations of A23187. Finally, cells pretreated with CyA recovered the ability to respond to high concentrations of A23187 (5 microM) faster than low concentrations (0.5 microM). We conclude that the principal defect in lymphocytes with partial CN inhibition is a reduction in maximum cytokine output which is closely related to the degree of CN inhibition. In addition, there is significantly greater inhibition of weak stimuli compared to maximal stimuli. These defects may explain why patients on CyA can have a reduction in immune responsiveness but still retain protection from infection.
...
PMID:The functional consequences of partial calcineurin inhibition in human peripheral blood mononuclear leucocytes. 876 5

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease that is characterized by selective destruction of insulin-secreting beta-cells. Cytokines have been implicated as effector molecules that participate in both islet inflammation and beta-cell destruction during the development of IDDM. In this study, the effects of cytokines on the expression of inducible nitric oxide synthase (iNOS) and inducible cyclooxygenase (COX-2) by human islets were examined. In combination, the cytokines, human recombinant interleukin-1 beta (IL-1 beta), human recombinant tumor necrosis factor-alpha (TNF-alpha), and human recombinant interferon-gamma (IFN-gamma), induce the time-dependent formation of nitrite and prostaglandin E2 (PGE2) by human islets. The nitric oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) completely inhibits cytokine-induced nitrite formation and attenuates PGE2 production by human islets. L-NMMA does not inhibit cytokine-induced expression of COX-2 by human islets, suggesting that nitric oxide may directly activate cyclooxygenase, an effect that has been previously demonstrated for isolated rat islets. This combination of cytokines (IL-1 beta, TNF-alpha, and IFN-gamma) also induces the expression of iNOS mRNA by human islets as demonstrated by both reverse transcriptase-polymerase chain reaction and Northern blot analysis. We further show that the tyrosine kinase inhibitors genistein and herbimycin A prevent IL-1 beta plus IFN-gamma-induced expression of COX-2 and iNOS and the production of PGE2 and nitric oxide by human islets. These results demonstrate that cytokines induce the expression of iNOS and COX-2 by human islets and that cytokine-induced expression of both COX-2 and iNOS by human islets appears to require the activation of a tyrosine kinase(s).
...
PMID:Tyrosine kinase inhibitors prevent cytokine-induced expression of iNOS and COX-2 by human islets. 876 39

T-helper subset 2 (Th2) lymphocytes produce interleukin 4 (IL-4) and IL-10, which exert anti-inflammatory actions on monocytes and macrophages. Th1 lymphocytes, on the other hand, secrete interferon-gamma (IFN gamma) which promotes tissue inflammation. The functional dichotomy between TH1 and Th2 lymphocyte subsets suggests that these cells play a regulatory role in inflammatory disease. The participation of Th subpopulations and their lymphokine products in experimental glomerulonephritis (GN) has not been previously evaluated. In this study, we examined renal expression of Th1 and Th2-type lymphokines in the first 48 hours of passive anti-glomerular basement membrane (anti-GBM) GN in the rate. Using the reverse transcriptase-polymerase chain reaction (RT-PCR) method, apparent increase in expression of both TH1-type (IL-2 and IFN gamma) and Th2-type (IL-4 and IL-10) lymphokine mRNA was observed in glomerular-enriched renal tissue obtained from nephritic rats. Induction of monocyte-derived IL-1 alpha and IL-1 receptor antagonist (IL-1RA) mRNA expression was also detected shorted after initiation of GN. Evidence for influx of mononuclear cells including T lymphocytes into the kidney was noted during the same time period as cytokine mRNA expression. Utilizing a monoclonal anti-rat IL-4 antibody, we also detected interleukin 4-producing cells in the renal cortex 24 hours following induction of GN. these experiments demonstrate for the first time anti-inflammatory lymphokine (IL-4 and IL-10) mRNA expression and IL-4 protein production in the kidney during antibody-mediated GN. WE hypothesize that Th lymphocyte subsets modulate glomerular inflammation by producing lymphokines with opposing actions.
...
PMID:Anti-inflammatory lymphokine mRNA expression in antibody-induced glomerulonephritis. 877 Sep 57

In the pathogenesis of allergic reactions, T cells and cytokines play a major role. However, characterizations of food allergen-specific T cells are very limited. In this study, we screened the peripheral blood mononuclear cells (PBMC) of 14 patients for reactivity to ovomucoid (Gal d I), the major hen's egg allergen, and ovalbumin (Gal d II). Cell lines and clones specific to ovomucoid were generated from PBMC of four egg-allergic subjects, in order to study antigen domain specificity and cell cytokine production profiles. The results demonstrated, firstly, that egg-allergic patients respond to ovomucoid rather than to ovalbumin, and, secondly, that antigen specificity is predominantly directed toward the second and third domains of ovomucoid. The T-cell cytokine message was characterized by reverse transcriptase polymerase chain reaction (RT-PCR). Cell lines and clones from all four patients consistently expressed interleukin (IL)-5. IL-4, IL-13, and interferon-gamma were found to be expressed only by certain lines or clones. This observation suggests a central pathogenic role for IL-5 in food allergy-related symptoms.
...
PMID:Characterization of ovomucoid-specific T-cell lines and clones from egg-allergic subjects. 879 79

Pulmonary inflammation is characterized by the accumulation of eosinophils and other leukocytes in the lungs of individuals challenged with antigen. Cytokines released by the Th2 lymphocyte subset, especially interleukin-4 (IL-4) and interleukin-5 (IL-5), are also present and thought to play an important role in this process. Previously, we used a model of aerosolized antigen challenge of sensitized mice to show that T cells were necessary for the accumulation of eosinophils and the production of cytokine steady-state messenger ribonucleic acid (mRNA). T cells were isolated from lung tissue at a time (4 h) when high levels of IL-4 and IL-5 mRNAs had accumulated, and from bronchoalveolar lavage fluid (BALF) and lung tissue at a later time (24 h), when inflammation could be detected by lavage. Lung-derived lymphocytes from sensitized challenged mice consisted of approximately 40% Thyl+ T cells (20% CD4+, 13% CD8+, and 6% CD4+/CD8+) and 30% B220+ B cells. Both BALF- and lung-derived T lymphocytes exhibited a similar activated/memory phenotype (CD44+ CD45RBlo), although lung tissue also contained less differentiated cells (CD44+ CD45RBhi). Thyl+ BALF cells isolated by magnetic bead-mediated separation accounted for approximately 88% of the IL-5 mRNA, 21% of the interferon-gamma (IFN-gamma) mRNA, and < 2% of the IL-4 mRNA detected in unseparated samples by reverse transcriptase-polymerase chain reaction (RT-PCR). Thyl+ T cells from lung tissue accounted for approximately 98% and 89% of IL-5 mRNA, 56% and 80% of IFN-gamma mRNA, and 23% and 40% of IL-4 mRNA at 4 h and 24 h after challenge, respectively. These experiments demonstrate that isolated T cells from BALF and lung are responsible for most of the IL-5 mRNA, but not all of the IFN-gamma or IL-4 mRNAs, detected in this model. These results are consistent with human studies indicating T cells as the major source of IL-5 mRNA in the lungs of asthmatic patients.
...
PMID:T cells are the predominant source of interleukin-5 but not interleukin-4 mRNA expression in the lungs of antigen-challenged allergic mice. 881 Jun 48

Recent animal studies suggest that indirect T-cell recognition of alloantigen plays an important role in allograft rejection and tolerance. In this study, we generated T cell clones from Lewis (LEW, RT1(l)) rat lymph node cells that had been primed in vivo by immunization with immunogenic class II MHC allopeptide RT1.D(u)beta2, representing residues 20-44 of the polymorphic beta chain of RT1.Dbeta(u) (Wistar Furth [WF]). Using reverse transcriptase polymerase chain reaction transcript analysis with specific rat T cell receptor Vbeta primers, we show that six out of nine T cell clones specifically proliferated to RT1.D(u)beta2 and expressed Vbeta 9. One of these clones, clone 2F4, which specifically proliferated to RT1.D(u)beta2 in a dose-response fashion and produced interferon-gamma in response to restimulation by RT1.D(u)beta2, was selected for further studies. The beta-chains of RT1.D(l) and RT1.D(u) residues 20-44 differ by two amino acids at positions 30 and 38. We synthesized two peptides, each containing a single polymorphic site: RT1.D(u)beta 20-33 and RT1.D(u)beta 31-44. Both these peptides were immunogenic by LEW responders, since lymph node cells primed by immunization proliferated equally to the peptides in vitro. Interestingly, in vitro dose-response studies with clone 2F4 showed better proliferative response to peptide RT1.D(u)beta 20-33 than to peptide RT1.D(u)beta 31-44, indicating that this T cell clone preferentially recognizes a single amino acid difference on residue 30. Finally, it has been suggested that indirect allorecognition by CD4+ T cells mediate graft rejection by delayed-type hypersensitivity responses, although definitive studies are lacking. Systemic injection of the 2F4 clone to naive LEW rats elicited an antigen-specific delayed-type hypersensitivity response against RT1.D(u)beta2 peptide and WF splenocytes, confirming indirect presentation in vivo. These data demonstrate that Th1 cell clones generated by in vivo priming via the indirect pathway utilize specific T cell receptor Vbeta and recognize single amino acid differences in the allopeptide. More importantly,these Th1 clones are capable of mediating a specific immune response in vivo. These studies with MHC allopeptide-specific T cell clones further delineate the cellular mechanisms of indirect allorecognition and provide a potential strategy to study its role in acute and chronic rejection, and tolerance.
...
PMID:Mechanisms of indirect allorecognition in graft rejection: class II MHC allopeptide-specific T cell clones transfer delayed-type hypersensitivity responses in vivo. 882 64

Tumor necrosis factor-alpha (TNF-alpha) has attracted the greatest attention as a major factor in experimental autoimmune encephalomyelitis (EAE) pathogenesis. We compared rats undergoing EAE with manipulated but healthy animals by examining TNF-alpha gene expression in cells recovered from the brain. We used reverse transcriptase-polymerase chain reaction (RT-PCR) as a sensitive assay for detection and Northern blot hybridization as a reliable quantitative assay of TNF-alpha mRNA. TNF-alpha gene expression was consistently detected in rats immunized with myelin basic protein (MBP) emulsified in complete Freund adjuvant (CFA), but not in rats immunized with MBP emulsified in incomplete Freund adjuvant (IFA), which does not induce EAE. Similarly, brain-derived cells from rats injected with cloned encephalitogenic T cells contained increased amounts of TNF-alpha mRNA compared with rats injected with nonencephalitogenic T cell clones similar in antigen specificity and in vitro lymphokine-producing capacity. Considering that the differing pathogenic capacity of MBP-reactive T cells might result from differing patterns of interaction with glia, we examined the impact of T-cell-glia interaction in vitro on cytokine gene expression in both cell types. Glial components were efficient in inducing TNF-alpha expression in T cells; T cells and T-cell-derived cytokines could elicit expression of several lymphokine genes in glial cells. Comparison of RT-PCR and blot hybridization assays, however, suggested that cytokine expression was much more efficient, on a per cell basis, in T cells than in glia. TNF-alpha was shown to have direct cytotoxic effect on glial cells, which was greatly enhanced by small amounts of interferon-gamma (IFN-gamma).
...
PMID:Production of tumor necrosis factor-alpha as a result of glia-T-cell interaction correlates with the pathogenic activity of myelin basic protein-reactive T cells in experimental autoimmune encephalomyelitis. 887

The mechanisms underlying the chronic hepatic inflammatory process in hepatitis C virus (HCV) infection are not well understood. Some models of experimentally induced hepatitis point to a role of interferon-gamma (IFN-gamma) secreted by liver-infiltrating peripheral blood lymphocytes (PBMC) in mediating hepatocellular injury. In the present study, IFN-gamma gene expression was analysed in PBMC and in liver biopsy specimens from patients with chronic HCV infection using a quantitative reverse transcriptase polymerase chain reaction technique. IFN-gamma gene expression by PBMC from HCV-infected patients exhibiting elevated serum transaminase activities was found to be increased up to ninefold when compared with (1) healthy individuals, (2) HCV-infected patients exhibiting normal or only slightly elevated serum enzyme activities, or (3) patients with drug-induced elevated serum transaminase activity. A histo-pathological evaluation of liver biopsy sections revealed further that high IFN-gamma gene expression by PBMC was associated with a more pronounced degree of inflammatory activity. In individual patients, the expression of IFN-gamma by PBMC was shown to parallel closely serum transaminase activities during IFN-alpha 2a therapy. Moreover, liver biopsy material from patients chronically infected with HCV contained higher amounts of IFN-gamma transcripts than liver tissue from patients with liver disorders unrelated to HCV infection or without any liver disease. These data thus demonstrate a close association between the amount of IFN-gamma transcripts in PBMC and in liver tissue and the inflammatory activity in chronic HCV infection in man.
...
PMID:High inflammatory activity is associated with an increased amount of IFN-gamma transcripts in peripheral blood cells of patients with chronic hepatitis C virus infection. 888 41


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---