Chronic human immunodeficiency virus type 1 infection of myeloid cells disrupts the autoregulatory control of the NF-kappaB/Rel pathway via enhanced IkappaBalpha degradation.

Productive human immunodeficiency virus type 1 (HIV-1) infection causes sustained NF-kappaB DNA-binding activity in chronically infected monocytic cells. A direct temporal correlation exists between HIV infection and the appearance of NF-kappaB DNA-binding activity in myelomonoblastic PLB-985 cells. To examine the molecular basis of constitutive NF-kappaB DNA-binding activity in HIV1 -infected cells, we analyzed the phosphorylation and turnover of IkappaBalpha protein, the activity of the double-stranded RNA-dependent protein kinase (PKR) and the intracellular levels of NF-kappaB subunits in the PLB-985 and U937 myeloid cell models. HIV-1 infection resulted in constitutive, low-level expression of type 1 interferon (IFN) at the mRNA level. Constitutive PKR activity was also detected in HIV-1-infected cells as a result of low-level IFN production, since the addition of anti-IFN-alpha/beta antibody to the cells decreased PKR expression. Furthermore, the analysis of IkappaBalpha turnover demonstrated an increased degradation of IkappaBalpha in HIV-1-infected cells that may account for the constitutive DNA binding activity. A dramatic increase in the intracellular levels of NF-kappaB subunits c-Rel and NF-kappaB2 p100 and a moderate increase in NF-kappaB2 p52 and RelA(p65) were detected in HIV-1-infected cells, whereas NF-kappaB1 p105/p50 levels were not altered relative to the levels in uninfected cells. We suggest that HIV-1 infection of myeloid cells induces IFN production and PKR activity, which in turn contribute to enhanced IkappaBalpha phosphorylation and subsequent degradation. Nuclear translocation of NF-kappaB subunits may ultimately increase the intracellular pool of NF-kappaB/IkappaBalpha by an autoregulatory mechanism. Enhanced turnover of IkappaBalpha and the accumulation of NF-kappaB/Rel proteins may contribute to the chronically activated state of HIV-1-infected cells.     

Human immunodeficiency virus does not induce interleukin-1, interleukin-6, or tumor necrosis factor in mononuclear cells.

The production of interleukin-1 beta (IL-1 beta), IL-6, and tumor necrosis factor alpha (TNF-alpha) by fresh peripheral blood mononuclear cells was evaluated after exposure to human immunodeficiency virus (HIV) or purified recombinant HIV-1 envelope glycoprotein (rgp120). To exclude the role of contaminating endotoxin in this study, all media were subjected to ultrafiltration and reagents contained less than 25 pg of endotoxin per ml by Limulus assay. Under endotoxin-free conditions, no increases in IL-1 beta, IL-6, or TNF-alpha mRNA or protein were detectable in cell cultures exposed to HIV-1, HIV-2, or rgp120 (0.1 to 10 micrograms/ml), as compared with cytokine levels in mock-exposed cultures. However, concentrations of endotoxin (lipopolysaccharide) as low as 0.5 ng/ml induced significant production of mRNA and protein for these three cytokines. Preincubation of mononuclear cells with "shake" HIV-1 preparations and also mock-infected shake preparations prior to lipopolysaccharide stimulation resulted in a two- to threefold increase in IL-1 beta and TNF-alpha production. This priming effect was not observed with rgp120 (0.1 to 10 micrograms/ml) or standard HIV-1 or mock-infected supernatants, suggesting the presence of biologically active material independent of virus in the shake preparations. Our studies indicate that, in the absence of endotoxin, HIV-1, HIV-2, and HIV gp120 do not induce production of IL-1 beta, IL-6, or TNF-alpha by peripheral blood mononuclear cells.     

Increased human immunodeficiency virus (HIV) expression in chronically infected U937 cells upon in vitro differentiation by hydroxyvitamin D3: roles of interferon and tumor necrosis factor in regulation of HIV production.

We have investigated the roles of cytokines in the modulation of human immunodeficiency virus (HIV) production in chronically infected U937 cells upon in vitro differentiation by hydroxyvitamin D3. HIV-infected U937 cells exhibited markedly lower levels of CD4 and HLA-DR antigens than uninfected cells did. Vitamin D3 induced a time-dependent macrophagelike differentiation, as determined by monitoring the expression of some surface antigens by means of the monoclonal antibodies OKM1, OKM5, OKM13, OKM14, OKT4, anti-HLA-DR, TecMG2, TecMG3, LeuM3, LeuM1, anti-HLA-DP, and anti-HLA-DQ. Treatment with hydroxyvitamin D3 resulted in a marked increase in HIV production compared with control cultures. Interleukin 1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha) were detected in the culture media, whereas interferon (IFN) was not generally found. Using the polymerase chain reaction technique, we found HIV-infected U937 cells to express detectable levels of mRNAs for alpha interferon (IFN-alpha), IFN-beta, TNF-alpha, and IL-1 beta. The addition of TNF resulted in a marked increase of HIV production, whereas IL-1 beta was ineffective. In contrast, both IFN-alpha and IFN-beta exerted some inhibitory effect on HIV production, which was more marked in vitamin D3-treated cultures than in untreated cultures. HIV production was significantly increased by antibodies to IFN-alpha in both untreated and vitamin D3-treated cultures. Anti-IFN-beta antibody increased HIV production only in vitamin D3-treated cells. In contrast, anti-TNF-alpha antibodies markedly decreased HIV production in both control and differentiating U937 cells. Vitamin D3 treatment resulted in a higher expression of TNF receptors in differentiating cells than in control HIV-infected cells. These data demonstrate a strong correlation between HIV production and macrophagelike differentiation in chronically infected U937 cells and suggest that endogenous IFN and TNF exert opposite effects in the regulation of virus production in both undifferentiated and vitamin D3-treated cell cultures.     

Interleukin 1 induces HIV-1 expression in chronically infected U1 cells: blockade by interleukin 1 receptor antagonist and tumor necrosis factor binding protein type 1.

BACKGROUND: Cytokines and cytokine antagonists modulate human immunodeficiency virus (HIV) replication in vitro and may be involved in HIV disease pathogenesis. An understanding of these cytokine networks may suggest novel treatment strategies for HIV-seropositive persons. MATERIALS AND METHODS: U1 cells, a chronically infected promonocytic cell line, were stimulated with interleukin 1 alpha (IL-1 alpha), IL-1 beta or tumor necrosis factor (TNF) for 24 hr. The effects of these cytokines, and of anti-IL-1 receptor type 1 and type 2 (IL-1RI and II) antibody, IL-1 receptor antagonist (IL-1Ra), and recombinant human TNF binding protein type 1 (rhTBP-1, a form of TNF receptor p55), on HIV-1 replication, as measured by ELISA for HIV-1 p24 antigen, were determined. The effects of IL-1 and IL-1Ra on nuclear factor-kappa B (NF-kappa B) DNA binding activity, as measured by electrophoretic mobility shift assays, were also determined. RESULTS: IL-1 alpha and IL-1 beta increased p24 antigen production in a concentration-dependent manner. IL-1Ra completely, and rhTBP-1 partially, suppressed IL-1-induced p24 antigen production. IL-1 increased NF-kappa B DNA binding activity and IL-1Ra blocked this effect. Since IL-1Ra blocks IL-1 from binding to both the IL-1RI and Il-1RII, monoclonal antibodies directed against each receptor were used to ascertain which IL-1R mediates IL-1-induced HIV-1 expression. Antibody to the IL-1RI reduced IL-1-induced p24 antigen production. Although anti-IL-1RII antibody blocked the binding of 125IL-1-1 alpha to U1 cells by 99%, this antibody did not affect IL-1-induced p24 antigen production. IL-1 beta enhanced TNF alpha-induced HIV expression when added before or simultaneously with TNF alpha. CONCLUSIONS: IL-1 induces HIV-1 expression (via the IL-1RI) and NF-kappa B activity in U1 cells. These effects are blocked by IL-1Ra and partially mediated by TNF. IL-1 enhances TNF alpha-induced HIV replication in U1 cells.     

Synergistic stimulation of amnion cell prostaglandin E2 synthesis by interleukin-1, tumor necrosis factor and products from activated human granulocytes

We examined the interactions between supernatant from FMLP-activated human granulocytes, recombinant interleukin-1 (IL-1) and recombinant tumor necrosis factor (TNF) in the stimulation of prostaglandin E2 (PGE2) production by human amnion cells. Amnion cells from elective term cesarian sections were cultured in monolayer culture. Human granulocytes were activated with FMLP and centrifuged to obtained cell-free supernatant. Amnion cells were treated with granulocyte supernatant, IL-1 alpha, IL-1 beta, TNF-alpha, TNF-beta, or different combinations of these. Each of the stimulators alone enhanced the PGE2 production 5- to 27-fold. Granulocyte supernatant was synergistic with each of the cytokines. The combinations of IL-1 alpha or IL-1 beta with either TNF-alpha or TNF-beta caused a synergistic stimulation of amnion cell PGE2 production as well, whereas the combinations of IL-1 alpha with IL-1 beta or of TNF-alpha with TNF-beta were not synergistic. Furthermore, granulocyte supernatant was synergistic with the combination of IL-1 and TNF, resulting in a more than 150-fold stimulation of PGE2 production. Indomethacin completely suppressed these effects. We propose that granulocyte products acting together with IL-1 and TNF enhance PGE2 synthesis during inflammation, and serve as signals for the initiation of preterm labor in the setting of intra-amniotic infection.     

Endotoxin and Staphylococcus aureus enterotoxin A induce different patterns of cytokines.

The effects of Staphylococcus aureus enterotoxin A (SEA) and lipopolysaccharide (LPS) in cytokine production were assessed at the single cell level in cells obtained from healthy blood donors. Cytokine production was studied with UV-microscopy of fixed and permeabilized cells stained with cytokine specific monoclonal antibodies. The cytokines evaluated included tumour necrosis factor (TNF)-alpha, interleukin (IL)-1 alpha, IL-1 beta, IL-6, IL-8, IL-10, IL-2, IL-4, interferon (IFN)-gamma and TNF-beta. LPS exhibited marked production of IL-1 alpha, IL-1 beta, TNF-alpha, IL-6 and IL-8. After LPS stimulation IL-1 alpha, IL-1 beta, TNF-alpha and IL-8 were the dominating products, all peaking at or before 4 hours after cell stimulation. In addition, IL-10 production was evident after 12 hours of cell stimulation. The T-lymphocyte-derived cytokines TNF-beta, IL-2, IFN-gamma and IL-4 were never detected in the cultures. All cytokine production, except IL-8, was downregulated at 96 hours. In contrast, peak production of IL-1 alpha, IL-1 beta and IL-8, which were the dominant products, occurred after 12 hours in the SEA-stimulated cultures. Further, a significant T-lymphocyte production of TNF-beta, TNF-alpha, IFN-gamma and IL-2 was found with peak production 12-48 hours after initiation. Only low amounts of IL-6 were evident. The two types of cytokine pattern and kinetics found may correspond to the different clinical conditions after invasive Gram-negative Escherichia coli vs Gram-positive Staphylococcus aureus infections in humans, with a much more rapid onset of disease after E. coli infections.(ABSTRACT TRUNCATED AT 250 WORDS)     

Induction of interleukin 2 receptor (TAC) by tumor necrosis factor in YT cells

The effect of human recombinant tumor necrosis factor alpha (TNF-alpha) and interleukin 1 beta (IL-1 beta) on interleukin 2 receptor (IL-2R) expression on YT cells was examined. IL-2R expression was assessed by flow cytometric analysis with a monoclonal antibody to IL-2R (anti-TAC). TNF-alpha, like IL-1 beta, induced increased levels of IL-2R expression on YT cells with similar kinetics of induction. Maximum induction occurred at 20 to 30 hr. On a molar basis. TNF was less active than IL-1 beta. RNA isolated from TNF-alpha- or IL-1 beta-treated YT cells contained increased levels of IL-2R-specific mRNA as indicated by slot blot analysis by using an IL-2R-specific mRNA probe. Kinetic and IL-1 beta mRNA expression studies indicated that the TNF effect was a direct one. Because IL-2R expression is known to be associated with lymphocyte activation, the present results suggest that TNF-alpha may play a role in the regulation of immune responses.     

Antiretroviral treatment induces a shift to type-2 cytokine responses in HIV-1 infected pregnant women

We report on a cross-sectional study on proliferation and cytokine production (IFN-gamma, IL-12, IL-5 and TNF-alpha) by peripheral blood mononuclear cells (PBMC), activated or not with phytohemagglutinin (PHA) in HIV-1-infected pregnant women, untreated or treated with zidovudine. We compared the results with healthy women, either pregnant or not, and with HIV-1-infected, non-pregnant women. The most significant results indicate that basal IL-5 production in HIV-1-infected pregnant women was higher than in the rest of the groups, being even higher in the zidovudine-treated than in the untreated group. IL-5 and TNF-alpha production by PHA-activated PBMC was also higher in HIV-1 pregnant women than in controls and infected non-pregnant women. IFN-gamma production was much higher in healthy women than in the other groups. Finally, the IFN-gamma/IL-5 (Th1-type/Th2-type-cytokine) ratio was lower in HIV-infected than in uninfected groups. Zidovudine treatment reduced basal IL-12 and increased PHA-stimulated IL-5 production. Our results indicate that both HIV-1 infection and pregnancy favored a Th2-type response by T cells. Interestingly, zidovudine-treated pregnant women had a significantly higher Th2-type response than untreated ones.     

Human cytokines, tumor necrosis factor, and interferons: gene cloning, animal studies, and clinical trials

Presented is a comprehensive program designed to isolate human cytokine genes and investigate their relative induction, and to analyze cytokine activities in cell culture, animal tumor models, and human clinical trials. Human cytokine cDNAs have been isolated from a cDNA library made from normal human peripheral blood leukocytes (PBLs) treated with Sendai virus and the relative induction of tumor necrosis factor (TNF), alpha and gamma interferons (IFN-alpha, IFN-gamma), and interleukin-1 beta IL-1 beta) genes has been analyzed. In the Sendai virus-induced PBL system, IL-1 beta mRNA was shown to be approximately twofold higher than TNF or IFN-alpha mRNA whereas IFN-gamma mRNA was 50-100-fold lower than TNF or IFN-alpha mRNA. The cytotoxic activity of TNF was analyzed on several cell lines and IFN-alpha and IFN-gamma were shown to potentiate TNF cytotoxicity about 2-200-fold depending on cell lines. The LD50 for recombinant TNF in BALB/c mice was determined to be 6 X 10(7) U/kg and the therapeutic dose of recombinant TNF in sarcoma 180 bearing BALB/c mice was 3 X 10(5) U/kg, indicating a wide therapetic index. Phase I clinical trials of recombinant TNF given I.V. indicated a tolerated dose of 150,000 U/kg with biphasic half-life (T-1/2) of 2 and 31 min following TNF injection. Phase II trials of TNF and trials of TNF combined with IFN-alpha are in progress. These studies indicate that cytokines such as TNF and IFN-alpha are subject to similar induction systems, potentiate each other's activities, and can be tolerated at specific doses for potential therapeutic use.     

Effects of eleven cytokines and of IL-1 and tumor necrosis factor inhibitors in a human B cell assay.

The effects of different recombinant human cytokines and cytokine inhibitors were compared in a culture system in which cell contact with mutant EL-4 thymoma cells of murine origin efficiently stimulates human B cell proliferation and Ig secretion in conjunction with human T cell supernatant. IL-1 alpha, IL-1 beta, TNF-alpha, and IL-2 co-stimulated B cell proliferation and IgM, IgG, and IgA secretion, whereas IL-3, IL-4, IL-5, IL-6, IFN-gamma, or GM-CSF had weak or no activity in this regard. In contrast, TGF-beta 1 was strongly inhibitory. A very strict hierarchy of cytokine interactions was found in that IL-1 was necessary to induce TNF-alpha responsiveness, and TNF-alpha the IL-2 responsiveness, of the B cells. Most likely the small number of starting B cells in the present assay (300 FACS-separated B cells/200 microliters) minimized the effects of autocrine B cell factors. IL-4 together with IL-1 induced IgE secretion, and the IgE secretion was further increased by TNF-alpha. IFN-gamma had no modulatory effect on the IL-4 dependent IgE response in this system. Pretreatment of B cells with IL-1R antagonist (IL-1ra, which binds to IL-1R) or addition of soluble TNF receptor type 1 (sTNF-R55, which binds to TNF) completely inhibited the IL-1 or TNF-alpha effects, respectively. This occurred in a specific manner; the inhibition was reversed by a large excess of cytokine. IL-1ra also inhibited a B cell response induced by PMA-preactivated EL-4 cells alone. Because B cells responding to such preactivated EL-4 cells did not acquire TNF-alpha responsiveness, no IL-1 was apparently involved under this assay condition. It appears, therefore, 1) that IL-1ra can act on B cells and 2) that this antagonist may not only block IL-1R, but may provide a direct or indirect inhibitory signal interfering even with IL-1-independent B cell activation.