Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Currently available anti-human immunodeficiency virus type 1 (HIV-1) agents such as azidothymidine can prevent de novo virus infection in vitro but lack significant activity against chronically infected cells. Our laboratory has recently described glycoprotein (gp)120-specific cell mediated cytotoxicity (CMC) present in HIV-1-seropositive individuals that is capable of destroying virally infected cells. As a means of potentially eliminating persistent reservoirs of HIV-1, we examined the ability of various cytokines to augment preexisting gp120-specific CMC activity of peripheral blood mononuclear cells obtained from early disease patients. We found that interferon-gamma alone had no effect on gp120 cellular reactivity; however, the combination of interferon-gamma plus IL-2 produced enhancement beyond that of IL-2 alone.
 ...
PMID:Cytokine augmentation of human immunodeficiency virus type 1 (HIV-1) gp120-specific cellular cytotoxicity. 255 26

Neutrophils from 10 homosexual men with evidence of HIV infection and 10 healthy controls were tested for their capacity to generate leukotriene B4. Neutrophils from patients with AIDS produced less leukotriene immunoreactivity when appropriately stimulated than neutrophils from healthy controls, whereas no significant difference could be detected between HIV-antibody-positive individuals without AIDS and healthy controls. This observation may be pertinent to the recurrence of some of the opportunistic infections associated with AIDS but more importantly, if reflecting a general defect in leukotriene production, it may provide further understanding of the mechanism which leads to reduced natural killer-cell activity, interleukin-2 and interferon-gamma production in AIDS.
 ...
PMID:Reduced neutrophil production of leukotriene B4 associated with AIDS. 255 54

We studied the effect of human immunodeficiency virus (HIV) infection on the surface-marker expression of the human promonocytic cell line U937. U937 cells persistently produced HIV as detected by reverse transcriptase activity in culture supernatant. Expression of HLA class II antigens on U937/HIV cells was decreased 2- to 10-fold, depending on the Mab used. Class II expression of U937/HIV cells increased approximately two-fold by treatment with r-interferon-gamma. Whereas noninfected U937 cells expressed moderate amounts of lymphocyte function-associated antigen-1 (LFA-1) (CD11a) and minimal amounts of the C3bi receptor (CD11b) and p150/95 (CD11c), U937/HIV cells expressed moderate amounts of C3bi receptor and p150/95 and showed elevated expression of LFA-1 alpha (CD11a) and -beta (CD18) chains. Expression of these adhesion molecules resulted in strongly enhanced phorbolester-induced aggregation of U937/HIV cells compared with the noninfected U937 cells. In addition, almost all U937/HIV cells, but not noninfected U937 cells, intensely stained for cytoplasmic nonspecific esterase activity. The effects of HIV infection on U937 cells strikingly resemble the effects of differentiation-inducing agents, such as PMA and DMSO, on the U937 phenotype. Our finding suggests that HIV infection, apart from down regulating class II expression, induces differentiation of U937 cells.
 ...
PMID:Human immunodeficiency virus infection down-regulates HLA class II expression and induces differentiation in promonocytic U937 cells. 310 23

Tryptophan and kynurenine were measured retrospectively in sera of 11 male patients with advanced human immunodeficiency virus (HIV) infection (Walter Reed stages 4 and 6). Tryptophan levels are significantly reduced to less than 50% in patients with HIV infection and kynurenine levels significantly elevated when compared to sex and age matched controls. The decrease of tryptophan levels might contribute to neurologic symptoms often associated with HIV infection. Since interferon-gamma induces degradation of tryptophan via the kynurenine pathway, the present results may be consistent with enhanced endogenous production of interferon-gamma in advanced HIV infection.
 ...
PMID:Tryptophan degradation in patients infected by human immunodeficiency virus. 316 37

A model system for cytokine-induced up-regulation of human immunodeficiency virus type 1 (HIV-1) expression in chronically infected promonocyte clones was established. The parent promonocyte cell line U937 was chronically infected with HIV-1 and from this line a clone, U1, was derived. U1 showed minimal constitutive expression of HIV-1, but virus expression was markedly up-regulated by a phytohemagglutinin-induced supernatant containing multiple cytokines and by recombinant granulocyte/macrophage colony-stimulating factor alone. Recombinant interleukin-1 (IL-1), IL-2, interferon-gamma, and tumor necrosis factor-alpha did not up-regulate virus expression. Concomitant with the cytokine-induced up-regulation of HIV-1, expression of membrane-bound IL-1 beta was selectively induced in U1 in the absence of induction of other surface membrane proteins. This cytokine up-regulation of IL-1 beta was not seen in the uninfected parent U937 cell line. These studies have implications for the understanding of the mechanism of progression from a latent or low-level HIV-1 infection to a productive infection with resulting immunosuppression. In addition, this model can be used to delineate the potential mechanisms whereby HIV-1 infection regulates cellular gene expression.
 ...
PMID:Cytokine-induced expression of HIV-1 in a chronically infected promonocyte cell line. 331 29

AIDS dementia complex (ADC) is a complex, progressive neuropsychiatric syndrome seen in 60-70% of the patients with AIDS. The structural and functional changes associated with ADC may be the result of a variety of indirect mechanisms mediated via activated brain cells or/and virus that produce neurotoxins including N-methyl-D-aspartate receptor agonist (eg, quinolinic acid, glutamate), cytokines, gp 120 and nitric oxide. The level of the neurotoxin and kynurenine pathway metabolite, quinolinic acid, is increased in the brain and CSF of HIV-1-infected patients, and is correlated with quantitative measures of neurologic impairment. Importantly, increased CSF and brain levels of QUIN also occur in other inflammatory neurologic diseases (bacterial, viral, fungal and parasitic infections, meningitis, autoimmune diseases and septicemia), independent of HIV-1 infection. Therefore, QUIN and other neuroactive kynurenine pathway metabolites may be final common mediators of neurologic dysfunction in a broad spectrum of inflammatory neurologic diseases. Conversion of L-tryptophan to QUIN has also been demonstrated in vitro in both brain tissue following macrophage infiltration, and in macrophages stimulated by interferon-gamma or HIV infection. Macrophages in vitro have a high capacity to synthesize QUIN following exposure to interferon-gamma, tumor necrosis factor-alpha, IL-1 beta and IL-6, compared to cells derived from other tissues. Notably, the concentrations achieved in the macrophage incubates exceeded the levels found in the CNS of HIV-1-infected patients, and exceeded the concentrations shown to be neurotoxic in vitro. We hypothesize that increased kynurenine pathway metabolism following inflammation reflects the presence of macrophages and other reactive cell populations at the site of brain infection. Strategies to attenuate the neurotoxic effects of kynurenines, such as inhibitors of kynurenine pathway metabolism and cytokine antibodies may offer new approaches to therapy.
 ...
PMID:[Biochemical studies on AIDS dementia complex--possible contribution of quinolinic acid during brain damage]. 747 52

HIV-infected monocytes form highly invasive network on basement membrane matrix and secrete high levels of 92-kd metalloproteinase (MMP-9), an enzyme that degrades basement membrane proteins. In the present study, using matrigel as a model basement membrane system, we demonstrate that treatment of human immunodeficiency virus (HIV)-infected monocytes with interferon-gamma at 50 U/ml inhibited the ability of infected monocytes to form an invasive network on matrigel and their invasion through the matrigel matrix. These effects were associated with a significant reduction in the levels of MMP-9 produced by HIV-infected monocytes treated with interferon-gamma 1 day prior to infection with HIV as compared with that of untreated HIV-infected monocytes. Monocytes treated with interferon-gamma 1 day after HIV infection showed the presence of integrated HIV sequences; however, the levels of MMP-9 were substantially lower than those produced by monocytes inoculated with live HIV, heat-inactivated HIV, or even the control uninfected monocytes. Exposure of monocytes to heat-inactivated HIV did not result in increased invasiveness or high MMP-9 production, suggesting that regulation of metalloproteinase by monocytes was independent of CD4-gp120 interactions and required active virus infection. Furthermore, addition of interferon-gamma to monocytes on day 10 after infection inhibited MMP-9 production by more than threefold with no significant reduction of virus replication. These results indicate that the mechanism of interferon-gamma-induced down-regulation of MMP-9 levels and reduced monocyte invasiveness may be mediated by a mechanism independent of antiviral activity of IFN-gamma in monocytes. Down-regulation of MMP-9 in HIV-infected monocytes by interferon-gamma may play an important role in the control of HIV pathogenesis.
 ...
PMID:Interferon-gamma inhibits HIV-induced invasiveness of monocytes. 749 70

We have recently shown that, in unfractioned peripheral blood mononuclear cells (PBMCs), the cross-linking of CD4 molecules (CD4XL) is sufficient to induce T-cell apoptosis. However, the underlying mechanism for the CD4XL-mediated T-cell apoptosis is largely unknown. Several recent studies have shown that Fas antigen (Ag), a cell-surface molecule, mediates apoptosis-triggering signals. We show here that cross-linking of CD4 molecules, induced either by anti-CD4 monoclonal antibody (MoAb) Leu3a or by human immunodeficiency virus-1 (HIV-1) envelope protein gp160, upregulates Fas Ag expression as well as Fas mRNA in normal lymphocytes. Addition of the tyrosine protein kinase inhibitor genistein or of the immunosuppressive agent cyclosporin A abrogated these effects. The upregulation of Fas Ag closely correlated with apoptotic cell death, as determined by flow cytometry. In addition, CD4XL resulted in the induction of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) in the absence of interleukin-2 (IL-2) and IL-4 secretion in PBMCs. Both INF-gamma and TNF-alpha were found to contribute to Fas Ag upregulation and both anti-IFN-gamma and anti-TNF-alpha antibodies blocked CD4XL-induced Fas Ag upregulation and lymphocyte apoptosis. These findings strongly suggest that aberrant cytokine secretion induced by CD4XL and consequent upregulation of Fas Ag expression might play a critical role in triggering peripheral T-cell apoptosis and thereby contribute to HIV disease pathogenesis.
 ...
PMID:Cross-linking of CD4 molecules upregulates Fas antigen expression in lymphocytes by inducing interferon-gamma and tumor necrosis factor-alpha secretion. 752 37

Since early growth response-1 (Egr-1) is required for macrophage differentiation and nitric oxide (NO) is immunosuppressive, we hypothesized that NO would reduce Egr-1 expression in rat lung macrophages. The inflammatory stimuli interferon-gamma and lipopolysaccharide induced an early, transient increase in Egr-1 mRNA (> 5-fold at 2 h) and a sustained, high level of inducible NO synthase mRNA (> 100-fold from 4 to 24 h). The NO metabolites nitrite and nitrate rose > 10-fold in medium from stimulated versus unstimulated cells over 24 h. Concomitant with elevated nitrogen oxides, Egr-1 mRNA levels declined to 80% below unstimulated cells at 24 h. This decline was blocked by an inhibitor of NO production, NG-monomethyl-L-arginine. Further, the NO donor S-nitroso-N-acetylpenicillamine inhibited Egr-1 expression in a dose-dependent manner, producing complete inhibition at 0.5 mM. The effect of S-nitroso-N-acetylpenicillamine was not due to reduced macrophage viability. We conclude that Egr-1 induction precedes inducible NO synthase induction in stimulated rat macrophages and that subsequent NO production reduces macrophage expression of Egr-1. We propose that this mechanism is used to regulate macrophage differentiation in human immunodeficiency virus infection and other inflammatory states.
 ...
PMID:Nitric oxide reduces early growth response-1 gene expression in rat lung macrophages treated with interferon-gamma and lipopolysaccharide. 752 82

The Gal beta(1-3)GalNAc-binding lectin jacalin is known to specifically induce the proliferation of human CD4+ T lymphocytes in the presence of autologous monocytes and to interact with the CD4 molecule and block HIV-1 infection of CD4+ cells. We further show that jacalin-induced proliferation is characterized by an unusual pattern of T cell activation and cytokine production by human peripheral blood mononuclear cells (PBMC). A cognate interaction between T cells and monocytes was critical for jacalin-induced proliferation, and human recombinant interleukin (IL)-1 and IL-6 did not replace the co-stimulatory activity of monocytes. Blocking studies using monoclonal antibodies (mAb) point out the possible importance of two molecular pathways of interaction, the CD2/LFA-3 and LFA-1/ICAM-1 pathways. One out of two anti-CD4 mAb abolished jacalin responsiveness. Jacalin induced interferon-gamma and high IL-6 secretion, mostly by monocytes, and no detectable IL-2 synthesis or secretion by PBMC. In contrast, jacalin-stimulated Jurkat T cells secreted IL-2. CD3- Jurkat cell variants failed to secrete IL-2, suggesting the involvement of the T cell receptor/CD3 complex pathway in jacalin signaling. IL-2 secretion by CD4- Jurkat variant cells was delayed and lowered. In addition to CD4, jacalin interacts with the CD5 molecule. Jacalin-CD4 interaction and the proliferation of PBMC, as well as IL-2 secretion by Jurkat cells were inhibited by specific jacalin-competitive sugars.
 ...
PMID:Proliferative response of human CD4+ T lymphocytes stimulated by the lectin jacalin. 754 1


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