Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MEDIATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
PubMed2004

Mediators of diabetic renal disease: the case for tgf-Beta as the major mediator.

The critical role of hyperglycemia in the genesis of diabetic nephropathy has been established by cell culture studies, experimental animal models, and clinical trials. Certain cytokines and growth factors have been identified as likely mediators of the effects of high ambient glucose on the kidney, but prominent among these is TGF-beta, a prototypical hypertrophic and fibrogenic cytokine. Overexpression of TGF-beta has been demonstrated in the glomerular and tubulointerstitial compartments of experimental diabetic animals. The TGF-beta receptor signaling system is also triggered, as evidenced by upregulation of the TGF-beta type II receptor and activation of the downstream Smad signaling pathway. Treatment of diabetic mice with neutralizing anti-TGF-beta antibodies prevents the development of renal hypertrophy, mesangial matrix expansion, and the decline in renal function. Antibody therapy also reverses the established lesions of diabetic glomerulopathy. These studies argue strongly in support of the hypothesis that overactivity of the TGF-beta system in the kidney is a crucial mediator of diabetic renal hypertrophy and mesangial matrix expansion.

Diabetic Nephropathies↗
PubMed2025

EP300-mediated lactylation leads to ulcerative colitis via CD86-positive plasmacytoid dendritic cells: A Mendelian randomization and mediation analysis.

This study explores the potential mechanism between lactylation and ulcerative colitis (UC) using two-sample Mendelian randomization and multi-omics analysis. This study employed expression quantitative trait loci and protein quantitative trait loci as exposures, with UC from the Finnish database as the outcome, to conduct Mendelian randomization analysis on lactylation-related target genes, aiming to investigate the causal relationships between these exposures and the outcome. Sensitivity and pleiotropy tests, combined with colocalization analysis, are performed to identify the best target genes and ensure the robustness of the results. Finally, immune cells are included for mediation analysis between lactylation and UC to explore potential mechanisms of action. Through Mendelian randomization analysis combined with sensitivity and pleiotropy tests, 2 lactylation target genes were found to have a significant causal relationship with UC. Subsequent colocalization analysis confirmed EP300 as a potential gene target. After including immune cells in the mediation analysis, it was discovered that there is a potential mechanism involving EP300, CD86+ plasmacytoid dendritic cells (pDCs), and UC. There is a significant causal relationship between lactylation and UC. Furthermore, the lactylation-modified gene EP300 may lead to UC occurrence by regulating CD86+ pDCs.

Humans↗
PubMed2002

IRE1-mediated unconventional mRNA splicing and S2P-mediated ATF6 cleavage merge to regulate XBP1 in signaling the unfolded protein response.

All eukaryotic cells respond to the accumulation of unfolded proteins in the endoplasmic reticulum (ER) by signaling an adaptive pathway termed the unfolded protein response (UPR). In yeast, a type-I ER transmembrane protein kinase, Ire1p, is the proximal sensor of unfolded proteins in the ER lumen that initiates an unconventional splicing reaction on HAC1 mRNA. Hac1p is a transcription factor required for induction of UPR genes. In higher eukaryotic cells, the UPR also induces site-2 protease (S2P)-mediated cleavage of ER-localized ATF6 to generate an N-terminal fragment that activates transcription of UPR genes. To elucidate the requirements for IRE1alpha and ATF6 for signaling the mammalian UPR, we identified a UPR reporter gene that was defective for induction in IRE1alpha-null mouse embryonic fibroblasts and S2P-deficient Chinese hamster ovary (CHO) cells. We show that the endoribonuclease activity of IRE1alpha is required to splice XBP1 (X-box binding protein) mRNA to generate a new C terminus, thereby converting it into a potent UPR transcriptional activator. IRE1alpha was not required for ATF6 cleavage, nuclear translocation, or transcriptional activation. However, ATF6 cleavage was required for IRE1alpha-dependent induction of UPR transcription. We propose that nuclear-localized IRE1alpha and cytoplasmic-localized ATF6 signaling pathways merge through regulation of XBP1 activity to induce downstream gene expression. Whereas ATF6 increases the amount of XBP1 mRNA, IRE1alpha removes an unconventional 26-nucleotide intron that increases XBP1 transactivation potential. Both processing of ATF6 and IRE1alpha-mediated splicing of XBP1 mRNA are required for full activation of the UPR.

Activating Transcription Factor 6↗
PubMedDate not supplied

Enhancement by cysteinyl thiols of acetyltransferase-mediated, but not of sulfotransferase-mediated, binding of a pyrolysate-derived N-hydroxyarylamine, 2-hydroxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole, to DNA.

The effect of thiols on the activation of a pyrolysate-derived N-hydroxyarylamine, 2-hydroxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (N-hydroxy-Glu-P-1), was studied in vitro. In hepatic cytosol of rats, [3H]-N-hydroxy-Glu-P-1 bound covalently to calf thymus DNA in the presence of acetyl CoA or 3'-phosphoadenosine-5'-phosphosulfate (PAPS). The extent of the binding of N-hydroxy-Glu-P-1 in a PAPS-dependent system was decreased by the addition of 10 mM glutathione, N-acetyl-L-cysteine, 2-mercaptoethanol or dithiothreitol. However, acetyl CoA-dependent binding of N-hydroxy-Glu-P-1 was stimulated by the addition of 10 mM N-acetyl-L-cysteine (3 fold), L-cysteine (2 fold) or glutathione (1.2 fold), but not 10 mM 2-mercaptoethanol or L-methionine. After hydrolysis of the modified DNA, no difference was detected in the physicochemical properties of the nucleoside adduct formed in the acetyl CoA-supported system with and without thiols. These results indicate that thiols with a cysteine residue are able to affect the activation of carcinogenic heterocyclic arylamines selectively by the modulation of the acetyltransferase-mediated, but not the sulfotransferase-mediated, pathway.

Acetyl Coenzyme A↗
PubMed1996

The relationship between IgE-mediated and cell-mediated hypersensitivities in an unselected Danish population: the Glostrup Allergy Study, Denmark.

In this study, we have assessed the relationship between IgE-mediated and cell-mediated hypersensitivities in an unselected population living in western Copenhagen, Denmark. A total of 793 subjects, aged 15-69 years, were studied. Measurements of total serum IgE, prick tests with aero-allergens and patch tests with environmental haptens were performed in 561 (70.7% of 793) subjects. One or more positive prick tests were present in 28.4%, and contact sensitization occurred in 15.2%. When adjusted for the effects of sex and age, the probability of contact sensitization to one or more hapten was independent of serum IgE level (the odds ratio value (OR) = 1.0; 95% confidence interval (CI) = 0.7-1.4), and the probability of contact sensitization was independent of the number of positive prick tests (OR = 1.0; CI = 0.8-1.2). Contact sensitization appeared to be independent of enhanced IgE responsiveness in an unselected adult population.

Adolescent↗
PubMed1975

A comparison of the effector cells involved in cell-mediated lympholysis and antibody-dependent cell-mediated cytotoxicity in man.

Some physical and mechanistic properties of cytotoxic lymphocytes and antibody-dependent killer cells were compared. Cytotoxic lymphocytes were measured by the cell-mediated lympholysis (CML) technique after sensitization of human peripheral blood leukocytes (PBL) in unidirectional mixed leukocyte culture (MLC). Killer cells were measured before and after MLC in an antibody-dependent cell-mediated cytotoxicity (ADCMC) assay using 51-Cr-labeled mouse mastocytoma cells as targets. Quantitative analysis of the cytotoxic activity of populations separated by velocity sedimentation at 1 g indicated that cytotoxic lymphocytes in MLC were a relatively heterogeneous population of rapidly sedimenting cells that corresponded morphologically to lymphoblasts. Further studies in which PBL were separated before MLC suggested that such cytotoxic lymphocytes were derived from small lymphocyte progenitors. Analysis of ADCMC in separated populations showed that most killer cells in PBL had the sedimentation properties of small lymphocytes. After stimulation of PBL in MLC, increased ADCMC activity was detected, and the increased activity was associated with a population of rapidly sedimenting cells, Comparison of the sensitivity of cytotoxic lymphocytes and killer cells to inhibition by EDTA, cytochalasin B, and dimethyl sulfoxide showed no significant differences between the two types of effector cells.

Cell Separation↗
PubMed1996

Different apoptotic pathways mediated by Fas and the tumor-necrosis-factor receptor. Cytosolic phospholipase A2 is not involved in Fas-mediated apoptosis.

Fas is a cell-surface receptor that belongs to the tumor-necrosis factor (TNF)/nerve growth factor receptor family. Fas can transduce an apoptotic signal through the death domain in the cytoplasmic region, which has similarity with the corresponding region of the TNF type-I receptor. Here, we expressed human Fas in mouse L929 cells or its subline (C12), which express extremely low levels of cytosolic phospholipase A2 (cPLA2). L929 cells were sensitive to the cytotoxic activity of TNF, while C12 cells were resistant. Cross-linking of human Fas with anti-(human Fas antibody) Ig killed both L929 transformants and C12 transformants expressing human Fas. Various inhibitors of the arachidonate metabolism significantly inhibited the TNF-induced cytotoxicity in L929 cells, but they did not have any effect on Fas-mediated apoptosis. These results indicated that cPLA2 is required for TNF-induced apoptosis, whereas it is dispensable for Fas-mediated apoptosis, and suggested that the TNF receptor and Fas use different signaling pathways for apoptosis.

Animals↗
PubMed1997

Pathway of detergent-mediated and peptide ligand-mediated refolding of heterodimeric class II major histocompatibility complex (MHC) molecules.

We investigated the mechanism of refolding and reassembly of recombinant alpha and beta chains of the class II major histocompatibility molecules (MHC-II) HLA-DRB5*0101. Both chains were expressed in the cytosol of Escherichia coli, purified in urea and SDS, and reassembled to functional heterodimers by replacement of SDS by mild detergents, incubation in a redox-shuffling buffer and finally by oxidation and removal of detergent. Refolding was mediated by mild detergents and by peptide ligands. Early stages of structure formation were characterized by circular dichroism, fluorescence, and time-resolved fluorescence anisotropy decay (FAD) spectroscopies. We found that formation of secondary structure was detectable after replacement of SDS by mild detergents. At that stage the alpha and beta chains were still monomeric, the buffer was strongly reducing, and the folding intermediates did not yet interact with peptide ligands. Formation of folding intermediates capable of interacting with peptide ligands was detected after adjusting the redox potential with oxidized glutathione and incubation in mild detergents. We conclude that at that stage a tertiary structure close to the native structure is formed at least locally. The nature and concentration of detergent critically determined the refolding efficiency. We compared detergents with different carbohydrate headgroups, and with aliphatic chains ranging from C6 to C14 in length. For each of the detergents we observed a narrow concentration range for mediating refolding. Surprisingly, detergents with long aliphatic chains had to be used at higher concentrations than short-chain detergents, indicating that increasing the solubility of folding intermediates is not the only function of detergents during a refolding reaction. We discuss structure formation and interactions of detergents with stable folding intermediates. Understanding such interactions will help to develop rational strategies for refolding hydrophobic or oligomeric proteins.

Circular Dichroism↗
PubMed1996

Decrease in [Ca2+]c but not in cAMP Mediates L-AP4 inhibition of glutamate release: PKC-mediated suppression of this inhibitory pathway.

We investigated the mechanism of the inhibition of glutamate release by (L)-2-amino-4-phosphonobutyrate ((L)-AP4) in cerebrocortical nerve terminals from young rats (3 weeks of age). The Ca(2+)-dependent release of glutamate was reduced by (L)-AP4 in a concentration-dependent manner. This inhibitory effect was prevented by pertussis toxin, insensitive to staurosporine and associated with a reduction both in the depolarization-evoked increase in the cytoplasmic free Ca(2+) concentration ([Ca(2+)](c)) and in forskolin-stimulated cAMP formation. However, the reduction in [Ca(2+)](c) but not in cAMP seemed to be responsible for the decrease in release, since inhibition by (L)-AP4 can also be observed in the absence of detectable changes in cAMP The inhibitory modulation by (L)-AP4 was suppressed by the activation of protein kinase C with phorbol esters. The nerve terminals from young rats also exhibited a facilitatory pathway of glutamate release which was mediated by protein kinase C. Interestingly, stimulation of this pathway with the glutamate agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylate in the presence of arachidonic acid also abolished the inhibitory action of (L)-AP4. The dominance of the facilitatory pathway in its interaction with the (L)-AP4-mediated inhibitory control may provide some clues to understand the presynaptic changes during synaptic plasticity.

Aminobutyrates↗
PubMedDate not supplied

Pentylenetetrazol-induced seizures decrease gamma-aminobutyric acid-mediated recurrent inhibition and enhance adenosine-mediated depression.

To elucidate the consequences of convulsions, we examined biochemically and electrophysiologically the brains of mice that had sustained two complete tonic-clonic convulsions after administration of pentylenetetrazol (PTZ 50 mg/kg intraperitoneally, i.p.), 48 and 24 h before decapitation. Control mice were injected with saline. Input/output curves of the extracellular synaptic responses in the CA1 area of hippocampal slices showed that PTZ-induced seizures do not establish the persistent change in hippocampal excitability itself that can be detected in vitro. However, use of the paired-pulse stimulation paradigm showed that gamma-aminobutyric acid A (GABAA)-mediated recurrent inhibition was significantly weaker (by 19-25%) in the CA1 area of slices from PTZ-treated mice (PTZ slices) as compared with slices from control mice (control slices). The density of GABAA receptors (high-affinity component) was also lower in hippocampus (by 19%) and cortex (by 14%) of PTZ-treated mice. A GABA-related disinhibitory mechanism underlying PTZ seizures may thus persist for 1 day after the seizure, predisposing the brain to subsequent seizures. On the other hand, the depressant effect of a single dose of adenosine 10 microM on the CA1 synaptic response was stronger (by 35% on population spikes) and longer lasting in PTZ slices as compared with controls. This could be attributed to significantly higher adenosine A1 receptor density in hippocampus (Bmax of [3H]CHA was higher by 34%) as well as cortex and cerebellum of these animals. The phenomenon may reflect an adenosine A1-mediated adaptive mechanism that offers protection from subsequent seizures.

Action Potentials↗
PubMed1986

In vitro cell-mediated and complement-mediated cytotoxicity to murine testicular cells.

Male BALB/c mice at 8 to 14 weeks of age were divided into three groups: group 1 was immunized with an emulsion of testicular cells (TCs) (10(7)/mouse), complete Freund's adjuvant (CFA), and extract of Bordetella pertussis (BP); group 2 was given CFA and BP injections; and group 3 was given sterile saline injections. Suspensions of TCs and spleen cells (SCs) from each mouse were prepared 4 weeks after the first immunization for a cytotoxic T lymphocyte (CTL) assay. For the antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent complement-mediated cytotoxicity (ACC) assays, TCs and SCs were prepared from normal male and female mice, respectively. Targets were labeled with Na251 Cr0(4). The interactions of targets (TCs) and effectors (SCs) were conducted at 32.5 degrees C (for CTL, ADCC, and ACC assays) or 37 degrees C (for ACC assay). In the CTL assay, SCs from group 1 and group 2 caused significantly more killing than those from group 3. Specific cytotoxicity in the ADCC assay was only detected in the serum (maximum specific lysis 47.65%) of one mouse. No other cytotoxicity was detectable in 61 serum samples from group 1 (n = 25), group 2 (n = 17), and group 3 (n = 19). In the ACC assay, no significant specific cytolysis was found at different incubation temperatures (32.5 and 37.0 degrees C) in 44 serum samples from the three groups. These results suggest that CTLs are important in the pathogenesis of experimental allergic orchitis (EAO). Adjuvant alone, probably because of breakdown of the blood-testis barrier, causes significant T lymphocyte cytotoxicity to TCs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed2003

Thrombin inhibits NMDA-mediated nociceptive activity in the mouse: possible mediation by endothelin.

The CNS expresses many components of an extracellular protease signalling system, including the protease-activated receptor-1 (PAR-1) whose tethered ligand is generated by thrombin. Activation of PAR-1 potentiates NMDA receptor activity in hippocampal neurons. Because NMDA activity mediates hyperalgesia, we tested the hypothesis that PAR-1 receptors also regulate pain processing. In contrast to the potentiating effect of thrombin in the hippocampus, NMDA-induced behaviours and the transient mechanical hyperalgesia (von Frey fibres) induced by intrathecally injected NMDA in mice were inhibited by thrombin in a dose-related fashion. This anti-hyperalgesic effect was mimicked by SFLLRN, the natural ligand at PAR-1 binding sites, but not SLIGRL-amide, a PAR-2 agonist. The effects of SFLLRN were less potent and shorter in duration than that of thrombin, consistent with its more transient effect on PAR-1 sites. Both thrombin and SFLLRN inhibited acetic acid-induced abdominal stretch (writhing) behaviours, which were also sensitive to NMDA antagonism, but not hot plate or tail flick latencies, which were insensitive to NMDA antagonists. TFLLR-amide, a selective ligand for PAR-1 sites, mimicked the effects of thrombin while RLLFT-amide, an inactive, reverse peptide sequence, did not. In addition, the effect of TFLLR-amide was prevented by RWJ-56110, a PAR-1 antagonist. Thrombin and TFLLR-amide produced no oedema (Evans Blue extravasation) in the spinal cord that would account for these effects. Based on the reported ability of thrombin to mobilize endothelin-1 from astrocytes, we tested the role of this compound in thrombin's activity. BQ123, an endothelin A receptor antagonist, prevented thrombin's inhibition of writhing and NMDA-induced behaviours while BQ788, an endothelin B receptor antagonist, did not. Thus, activation of PAR-1 sites by thrombin in the CNS appears to inhibit NMDA-mediated nociception by a pathway involving endothelin type A receptors.

Acetic Acid↗
PubMed1999

Selective regulation of G protein-coupled receptor-mediated signaling by G protein-coupled receptor kinase 2 in FRTL-5 cells: analysis of thyrotropin, alpha(1B)-adrenergic, and A(1) adenosine receptor-mediated responses.

G protein-coupled receptor kinases (GRKs) play a key role in the process of receptor homologous desensitization. In the present study, we address the question of whether a variety of receptors coupled to different G protein subtypes and naturally expressed on the same cell are selectively regulated by GRK2. The signaling stimulated by thyrotropin (TSH), alpha(1B)-adrenergic, and A(1) adenosine receptors was studied in FRTL-5 cells permanently transfected to overexpress GRK2 and GRK2-K220R, a kinase dead GRK dominant negative mutant. In FRTL-5 overexpressing GRK2, TSH-induced cyclic AMP response was attenuated, indicating that TSH receptor is desensitized by this kinase. Consistently, FRTL-5 cells overexpressing GRK2-K220R show increased TSH-induced cyclic AMP response, demonstrating that this receptor is under tonic control by GRK. Unlike TSH receptor, alpha(1B)-adrenergic receptor response was unaffected in FRTL-5 overexpressing GRK2 and GRK2-K220R. When A(1) adenosine receptors were stimulated, G(ialpha)-mediated cyclic AMP inhibition was totally unaffected by overexpression of either GRK2 or GRK2-K220R. By contrast, G(betagamma)-mediated response (activation of mitogen-activated protein kinases) was efficiently desensitized by GRK2 but was unaffected by GRK2-K220R overexpression. The present study documents that overexpression of GRK2 results in a selective regulation of different G protein-coupled receptors expressed on the same cell and that this kinase can regulate preferentially only one of the different pathways activated by the same receptor. The preferential regulation of the A(1) adenosine receptor-stimulated mitogen-activated protein kinases by GRK2 indicates that this kinase can have additional regulatory effects on G(betagamma)-stimulated pathways, possibly through direct binding and regulation of the receptor-G(betagamma) complex.

Animals↗
PubMed1996

CD4-mediated and CD8-mediated cytotoxic and proliferative immune responses to Toxoplasma gondii in seropositive humans.

Both CD4+ and CD8+ cytotoxic T lymphocytes (CTL) are part of the human immune response to Toxoplasma gondii infection. To further our understanding of Toxoplasma immunity, we investigated factors influencing stimulation of CD4+ or CD8+ human T. gondii-specific immune cells. Both antigen-pulsed and Toxoplasma-infected antigen-presenting cells (APC) induced cell proliferation. Toxoplasma-infected APC elicited strong proliferation of CD4+ cells, but little or no proliferation of CD8+ cells, unless high antigen loads were used. Toxoplasma-infected APC stimulated specific cytotoxicity poorly or not at all, owing to death of stimulated cultures, whereas antigen-pulsed APC strongly elicited specific cytotoxicity. Cytotoxicity elicited by either type of APC resided exclusively in CD4+ T cells in polyclonal cultures. Thus, Toxoplasma-infected APC elicited stronger CD4-mediated than CD8-mediated cell proliferation and generated CD4+ CTL more readily than CD8+ CTL. Nonetheless, specific CD8+ memory cells were demonstrated, and rare CD8+ Toxoplasma-specific CTL were subcloned. Fixed Toxoplasma-infected APC (which induce CD8+ CTL) also elicited cell proliferation, but polyclonal cultures stimulated with these infected APC did not die. Unfixed Toxoplasma-infected APC strongly inhibited phytohemagglutinin-induced cell proliferation, whereas fixed APC did not. These data suggested that infected APC were inhibitory or lethal to some immune cells. Further investigations into interactions between immune cells and Toxoplasma-infected cells likely will help elucidate factors involved in the immunopathogenesis of Toxoplasma infection. As other intracellular parasites, including Plasmodium spp. and Leishmania spp., also elicit CD4+ CTL, such work may help establish paradigms governing immunity to intracellular parasites.

Animals↗
PubMed1993

Mutations in the tyrR gene of Escherichia coli which affect TyrR-mediated activation but not TyrR-mediated repression.

Site-directed mutagenesis has been used to further characterize amino acid residues necessary for the activation of gene expression by the TyrR protein. Amino acid substitutions have been made at positions 2, 4, 5, 6, 7, 8, 9, 10, and 16. TyrR mutants with amino acid substitutions V-5-->P (VP5), VF5, CS7, CR7, DR9, RI10, RS10, and ER16 show no or very little activation of expression of either mtr or tyrP. In each case, however, the ability to repress aroF is unaltered. Amino acid substitutions at positions 4, 6, and 8 have no effect on activation. Small internal deletions of residues 10 to 19, 20 to 29, or 30 to 39 also destroy phenylalanine- or tyrosine-mediated activation of mtr and tyrP. In these mutants repression of aroF is also unaltered. In activation-defective tyrR mutants, expression of mtr is repressed in the presence of tyrosine. This tyrosine-mediated repression is trpR dependent and implies an interaction between TrpR and TyrR proteins in the presence of tyrosine.

Alleles↗
PubMed1994

Chromosome-mediated 2,3-dihydroxybenzoic acid is a precursor in the biosynthesis of the plasmid-mediated siderophore anguibactin in Vibrio anguillarum.

We have isolated a recombinant clone harboring the chromosomal aroC gene, encoding chorismate synthase, from Vibrio anguillarum 775 by complementation of the Escherichia coli aroC mutant AB2849 which was transfected with a cosmid gene bank of the plasmidless V. anguillarum H775-3. The nucleotide sequence was determined, and an open reading frame that corresponds to a protein of 372 amino acids was found. The calculated mass of 40,417 Da was correlated with the size of the V. anguillarum aroC product detected in vitro. The homology of the V. anguillarum aroC gene to the aroC genes of E. coli and Salmonella typhi is 68% at the nucleotide level and 78% at the protein level. The expression of the aroC transcript is not regulated by iron, as determined by Northern (RNA) blot hybridization analysis. After insertion of an antibiotic resistance gene cassette within the cloned aroC gene, an aroC mutant of V. anguillarum was generated by allelic exchange. This mutant is deficient in the production of 2,3-dihydroxybenzoic acid (2,3-DHBA). Our bioassay and complementation experiments with this mutant demonstrate that the chromosome-mediated 2,3-DHBA is a precursor of the pJM1 plasmid-mediated siderophore anguibactin.

Amino Acid Sequence↗
PubMed1984

Lysis of dengue virus-infected cells by natural cell-mediated cytotoxicity and antibody-dependent cell-mediated cytotoxicity.

Peripheral blood mononuclear cells (PBMC) from humans without antibodies to dengue 2 virus lysed dengue 2 virus-infected Raji cells to a significantly greater degree than uninfected Raji cells. The addition of mouse anti-dengue antibody increased the lysis of dengue-infected Raji cells by PBMC. Dengue 2 immune human sera also increased lysis of dengue-infected Raji cells by PBMC. These results indicate that both PBMC-mediated cytotoxicity and antibody-dependent cell-mediated cytotoxicity (ADCC) can cause significant lysis of dengue-infected Raji cells. The lysis of infected Raji cells in the ADCC assay correlated with the dilution of dengue-specific antibody which was added, indicating the dengue virus specificity of the lysis of dengue virus-infected Raji cells. Alpha interferon (IFN alpha) was detected in the culture supernatant of PBMC and dengue-infected Raji cells. However, enhanced lysis of dengue-infected Raji cells by PBMC may not be due to the IFN produced, because neutralization of all IFN activity with anti-IFN alpha antibody did not decrease the lysis of dengue-infected cells, and effector cells pretreated with exogenous IFN alpha also lysed dengue-infected cells to a greater degree than uninfected cells. The effector cells responsible for lysis of dengue virus-infected Raji cells in the natural killer and ADCC assays were analyzed. Nonadherent PBMC caused more lysis than did adherent cells. Characterization of nonadherent cells with monoclonal antibodies showed that the predominant responsible effector cells were contained in OKM1+ and OKT3- fraction in the natural killer and ADCC assays.

Animals↗
PubMed1998

Herpesvirus entry mediator HVEM mediates cell-cell spread in BHK(TK-) cell clones.

95-19 and U(S)11c119.3 are BHK(TK-)-derived cell lines that are highly resistant to postattachment entry of herpes simplex virus type 1 (HSV-1) and HSV-2 but not to later steps in single-step replication. The resistance properties of these two cell types are not identical. U(S)11c119.3 cells are fully susceptible to pseudorabies virus (PRV), as shown by single-step growth experiments, whereas 95-19 cells are resistant to entry of free PRV but not to entry by cell-cell spread. We have tested the ability of HVEM to overcome the block to infection in both cell lines following transient and stable transfection. HVEM was able to mediate entry of free HSV-1 into both cell lines, as shown by an increase in the number of beta-galactosidase-expressing cells in cultures transiently transfected with an HVEM expression plasmid and infected with lacZ-expressing HSV-1. In stably transfected 95-19 cells, HVEM enhanced infection by free HSV-1, as shown by an increase in the number of infectious centers obtained following infection. In both cell types, HVEM strongly enhanced entry of HSV-1 and HSV-2 by cell-cell spread, suggesting that HVEM can function as an entry mediator both in entry of free virus and in entry by cell-cell spread.

Cell Line↗