Showing papers on "Interferon published in 1992"

Early molecular events in the induction phase of contact sensitivity

Abstract: To assess changes in epidermis-derived cytokine mRNA levels early in the afferent phase of allergic contact sensitivity, total epidermal mRNA was analyzed at various times after painting skin with haptens. We used a sensitive reverse transcriptase-polymerase chain reaction technique to quantitatively compare the regulation patterns of the following mRNAs: class II major histocompatibility complex I-A alpha, tumor necrosis factor alpha (TNF-alpha), interleukin (IL) 1 alpha, IL-1 beta, interferon (IFN) gamma, granulocyte/macrophage colony-stimulating factor, IFN-induced protein 10, and macrophage inflammatory protein 2. Enhanced Langerhans cell-derived IL-1 beta mRNA signals were detected as early as 15 min after skin painting with allergens. TNF-alpha, IFN-gamma, and granulocyte/macrophage colony-stimulating factor mRNAs were found to be upregulated after application of allergens, irritant, and tolerogens, but class II major histocompatibility complex I-A alpha, IL-1 alpha, IL-1 beta, IFN-induced protein 10, and macrophage inflammatory protein 2 mRNAs were upregulated only after allergen painting. Depletion of specific cell populations demonstrated that Langerhans cells were the primary source of the IL-1 beta and class II major histocompatibility complex I-A alpha mRNAs, keratinocytes were the primary source of TNF-alpha, IL-1 alpha, IFN-induced protein 10, and macrophage inflammatory protein 2, and infiltrating T lymphocytes were the source of IFN-gamma. Relevance of the molecular findings was demonstrated by the identification of biologically active IL-1 alpha and immunoreactive TNF-alpha in culture supernatants. These studies demonstrate that Langerhans cell-derived and certain keratinocyte-derived cytokine mRNAs are selectively upregulated by allergens in the very early afferent phase of contact sensitivity.

Cytokine expression in the brain during the acquired immunodeficiency syndrome.

Abstract: The pathogenesis of central nervous system (CNS) disease in acquired immunodeficiency syndrome (AIDS) is poorly understood but may be related to specific effects of the immune system. Cytokines such as tumor necrosis factor and interleukin-1 may have toxic effects on CNS cells and have been postulated to contribute to the pathogenesis of the neurological complications of human immunodeficiency virus (HIV) infection. To characterize viral and immunological activity in the CNS, frozen specimens taken at autopsy from the cerebral cortex and white matter of HIV-seropositive and -seronegative individuals were stained immunocytochemically for mononuclear cells, major histocompatibility complex (MHC) antigens, HIV, astrocytes, and the cytokines interleukin-1 and -6, tumor necrosis factor-α and -β, and interferon γ. Levels of soluble CD4, CD8, and interleukin-2 receptor, as well as interferon γ, tumor necrosis factor-α, β2-microglobulin, neopterin, and interleukin-6 and -1 β were assayed in the cerbrospinal fluid and plasma of many of these individuals during life. The HIV-seropositive group included individuals without neurological disease, those with CNS oppotunistic infections, and those with HIV encephalopathy. Perivascular cells, consisting primarily of macrophages with some CD4+ and CD8+ T cells and rare B cells, were consistently MHC class II positive. MHC class II antigen was also present, on microglial cells, which were frequently positive for tumor necrosis factor-α. HIV p24 antigen, when present, was found on macrophages and microglia. Endothelial cells were frequently positive for interleukin-1 and interferon γ and less frequently for tumor necrosis factor and interleukin-6. There were gliosis and significant increases in MHC class II antigen, interleukin-1, and tumor necrosis factor-α in HIV-positive patients compared to HIV-negative brains. Cerebrospinal fluid from most of the patients tested had increased levels of tumor necrosis factor, β2-microglobulin, and neopterin. There was no correlationin HIV-positive individuals between levels of cytokines and the presence or absence of CNS disease. These data indicate that there is a relative state of “immune activation” in the brains of HIV-positive compared to HIV-negative individuals, and suggest a potential role for the immune system in the pathogenesis of HIV encephalopathy.

Pathogenesis and molecular biology of progressive multifocal leukoencephalopathy, the JC virus-induced demyelinating disease of the human brain.

Abstract: Studies of the pathogenesis and molecular biology of JC virus infection over the last two decades have significantly changed our understanding of progressive multifocal leukoencephalopathy, which can be described as a subacute viral infection of neuroglial cells that probably follows reactivation of latent infection rather than being the consequence of prolonged JC virus replication in the brain. There is now sufficient evidence to suggest that JC virus latency occurs in kidney and B cells. However, JC virus isolates from brain or kidney differ in the regulatory regions of their viral genomes which are controlled by host cell factors for viral gene expression and replication. DNA sequences of noncoding regions of the viral genome display a certain heterogeneity among isolates from brain and kidney. These data suggest that an archetypal strain of JC virus exists whose sequence is altered during replication in different cell types. The JC virus regulatory region likely plays a significant role in establishing viral latency and must be acted upon for reactivation of the virus. A developing hypothesis is that reactivation takes place from latently infected B lymphocytes that are activated as a result of immune suppression. JC virus enters the brain in the activated B cell. Evidence for this mechanism is the detection of JC virus DNA in peripheral blood lymphocytes and infected B cells in the brains of patients with progressive multifocal leukoencephalopathy. Once virus enters the brain, astrocytes as well as oligodendrocytes support JC virus multiplication. Therefore, JC virus infection of neuroglial cells may impair other neuroglial functions besides the production and maintenance of myelin. Consequently our increased understanding of the pathogenesis of progressive multifocal leukoencephalopathy suggests new ways to intervene in JC virus infection with immunomodulation therapies. Perhaps along with trials of nucleoside analogs or interferon administration, this fatal disease, for which no consensus of antiviral therapy exists, may yield to innovative treatment protocols.

DNA from bacteria, but not from vertebrates, induces interferons, activates natural killer cells and inhibits tumor growth.

Abstract: The nucleic acid fraction from cells of 6 species of bacterium and 2 kinds of vertebrate, calf and salmon, was extracted and purified by the same procedures as described previously. When the spleen cells from BALB/c mice were incubated with the nucleic acid fraction from either of the bacteria, natural killer (NK) activity of the cells was remarkably elevated and the cells produced factors to activate macrophages and to inhibit viral growth. It was shown that the factor to activate macrophages was interferon (IFN)-gamma and that to inhibit viral growth was IFN-alpha/beta. On the other hand, the nucleic acid fraction from either of the vertebrate cells did not show such activities. Pretreatment of the bacterial nucleic acid fraction with DNase, but not with RNase, abrogated completely the biological activities. The activities of the bacterial nucleic acid were not influenced by the presence of polymyxin B, an inhibitor of lipopolysaccharide (LPS), and the spleen cells from not only BALB/c mice but also LPS-insensitive C3H/HeJ mice were activated, indicating that the activities of the fraction were not ascribed to LPS contaminated possibly into the fraction, but to DNA itself. Intralesional injection with the bacterial DNA fraction caused regression of mouse IMC tumors, but the injection with the vertebrate DNA fraction did not. These findings prompted us to examine the biological activities of DNA samples from a variety of animals and plants, which were provided from other laboratories or purchased from manufacturers. All of the DNA samples from cells of 5 kinds of bacterium, 2 of virus and 4 of invertebrate augmented NK activity and induced IFN, more or less, in mouse spleen calls, while the DNA from 10 kinds of vertebrate, including 3 of fish and 5 of mammal, showed no such activities. The DNA from 2 species of plants, were also inactive. Possible mechanisms to explain the different biological activities of DNA from different cell sources were discussed based on our previous finding that the particular palindromic sequences with a G-C motif(s) are required for induction of IFNs and activation of NK cells with synthetic 30-mer oligonucleotides.

Interleukin 10 inhibits macrophage microbicidal activity by blocking the endogenous production of tumor necrosis factor alpha required as a costimulatory factor for interferon gamma-induced activation.

Abstract: Interleukin 10 (IL-10) inhibits interferon gamma-induced macrophage activation for cytotoxicity against larvae of the human parasite Schistosoma mansoni by suppressing production of the toxic effector molecule nitric oxide (NO). In this study, the mechanism of IL-10 action was identified as inhibition of endogenous tumor necrosis factor alpha (TNF-alpha) production by interferon gamma-activated macrophages. TNF-alpha appears to serve as a cofactor for interferon gamma-mediated activation, since both schistosomulum killing and NO production were inhibited by anti-TNF-alpha antibody, whereas TNF-alpha alone was unable to stimulate these macrophage functions. IL-10 blocked TNF-alpha production by interferon gamma-treated macrophages at the levels of both protein and mRNA synthesis. Addition of exogenous TNF-alpha reversed IL-10-mediated suppression of macrophage cytotoxic activity as well as NO production. Likewise, addition of a macrophage-triggering agent (bacterial lipopolysaccharide or muramyl dipeptide), which induced the production of TNF-alpha, also reversed the suppressive effect of IL-10 on cytotoxic function. In contrast to IL-10, two other cytokines, IL-4 and transforming growth factor beta, which also inhibit macrophage activation for schistosomulum killing and NO production, did not substantially suppress endogenous TNF-alpha production. These results, therefore, describe a separate pathway by which macrophage microbicidal function is inhibited by the down-regulatory cytokine IL-10.

Role of gamma interferon and tumor necrosis factor alpha in resistance to Salmonella typhimurium infection.

Abstract: In mice infected with a sublethal dose of Salmonella typhimurium, the injection of an anti-gamma interferon (IFN-gamma) monoclonal antibody increased bacterial proliferation in the spleen and led to death on day 7 or 8. Depletion of both CD4+ and CD8+ T cells with monoclonal antibodies in vivo had a much less marked effect during the first week of infection than the administration of anti-IFN-gamma antibodies, suggesting that cells other than T lymphocytes participate in the production of IFN-gamma at this time. Administration of anti-tumor necrosis factor alpha (TNF-alpha) antibodies to mice infected with a sublethal dose of S. typhimurium induced the same effect as anti-IFN-gamma antibodies, while the administration of both antibodies resulted in a synergistic interaction. When mice were infected with an avirulent strain of S. typhimurium and challenged on day 7 either with a virulent strain of S. typhimurium or with Listeria monocytogenes, their resistance to reinfection was slightly depressed by anti-IFN-gamma or anti-TNF-alpha antibodies given 1 day before challenge and much more strongly depressed by the simultaneous administration of both antibodies. Taken together, these results indicate that IFN-gamma and TNF-alpha play an essential role in acquired resistance during the early phase of S. typhimurium infection.

Synergism between tumor necrosis factor-alpha and interferon-gamma on macrophage activation for the killing of intracellular Trypanosoma cruzi through a nitric oxide-dependent mechanism.

Abstract: Intracellular replication of the protozoan parasite Trypanosoma cruzi inside macrophages is essential for the production of the disease and the development of the parasite. Two CD4+ T cell lines, A10 and A28, were established from T. cruzi-infected BALB/c mice which specifically proliferated to parasite antigens. The trypanocidal activity of BALB/c macrophages was induced upon culture with the A10, but not with the A28 T cell line. The cell-free supernatant from this A10 line, as well as from immune spleen cells stimulated with specific antigen or concanavalin A, but not from the A28 T cell line also activated the trypanocidal activity of peritoneal macrophages or of the J774 macrophage-like cell line. when the lymphokine content of the supernatants from both cell lines was analyzed, it was found that the A10 T cell line secreted interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha and interleukin 2, whereas the A28 line did not secrete IFN-gamma upon stimulation. Furthermore, the trypanocidal-inducing ability of A10 supernatant was completely abrogated by neutralizing anti-IFN-gamma antibodies and partially abrogated by neutralizing anti-TNF-alpha antibodies. When recombinant cytokines were added to J774 cells, IFN-gamma was able to induce significant trypanocidal activity whereas TNF-alpha was almost ineffective. However, TNF-alpha or lipopolysaccharide (LPS) showed a synergistic effect with IFN-gamma on macrophage activation. IFN-gamma triggered nitric oxide (NO) synthesis by J774 cells whereas TNF-alpha was almost ineffective. TNF-alpha and LPS were also synergistic with IFN-gamma in the NO production. Both the NO production and the trypanocidal activity in J774 cells induced by T cell supernatants or lymphokine combinations were inhibited by N-monomethyl-L-arginine, a competitive inhibitor of NO synthase activity. A good correlation between the levels of NO production and trypanocidal activity induced by different lymphokine preparations was found. Those results suggest that IFN-gamma and TNF-alpha, secreted by T. cruzi-immune T cells, are involved in the activation of the trypanocidal activity of mouse macrophages through an NO-dependent mechanism.

Critical role of a common transcription factor, IRF-1, in the regulation of IFN-beta and IFN-inducible genes.

Abstract: Interferon regulatory factor 1 (IRF-1) is a protein that binds to cis-elements within the promoter of interferon (IFN)-beta and some IFN-inducible genes. We used a human fibroblast line, GM-637, to generate stable transfectants constitutively expressing IRF-1 mRNA in either the sense or antisense orientation. Upon induction with poly-(I).poly(C) or Newcastle disease virus, cells expressing sense IRF-1 mRNA produced significantly higher levels of IFN-beta mRNA and protein than control cells, whereas cells expressing antisense IRF-1 mRNA produced little or no IFN-beta mRNA and protein. Furthermore, clear differences were seen among the transfectants in the level of expression of two IFN-induced genes (2'-5'-oligoadenylate synthetase and class I HLA). Our data show that IRF-1 is essential for the induced expression of the IFN-beta gene. The results also indicate an important role of IRF-1 in the expression of IFN-inducible genes and suggest a role for IRF-1 in many other cytokine actions.

Spontaneous Transformation of Rat Ovarian Surface Epithelial Cells: Association With Cytogenetic Changes and Implications of Repeated Ovulation in the Etiology of Ovarian Cancer

Abstract: BACKGROUND Ovarian surface epithelial cells undergo several rounds of division to repair the wound created by follicular rupture at the time of ovulation. This cyclical requirement for cell division, when not interrupted by the long anovulatory rest periods that occur during pregnancy and lactation, may contribute to the development of ovarian cancer. PURPOSE AND METHODS To test this hypothesis, we isolated rat ovarian surface epithelial cells from 10 adult female Fisher rats, initiated two mixed-population and seven clonal cell lines, and repeatedly subcultured these cells in vitro for more than 20 passages. We then tested them for the acquisition of the following four features associated with transformation: 1) the loss of contact inhibition, 2) the capacity for substrate-independent growth, 3) the ability to form tumors when injected subcutaneously and/or intraperitoneally into athymic mice, and 4) cytogenetic abnormalities. RESULTS Loss of contact inhibition was observed in all nine late-passage cell lines. Six of the nine late-passage, but none of the early-passage, cell lines tested exhibited a capacity for substrate-independent growth that was augmented in a dose-dependent manner by epidermal growth factor. Two late-passage cell lines (clone 2 and mixed-population 2) generated tumors in athymic BALB/c mice within 3 weeks following subcutaneous injection of 5 x 10(6) cells, whereas similar numbers of early-passage cells from the same cell lines failed to generate palpable tumors. Late-passage clone 7 cells were tumorigenic when 5 x 10(7) cells were injected intraperitoneally. Two of the cell lines analyzed exhibited alterations involving losses of part or all of one member of the chromosome 5 pair. Clone 2 possessed an interstitial deletion, del(5)(q21.3q24), consistent with the loss of an uncloned putative tumor suppressor gene at 5q22q23 previously reported to reside near the loci for the interferon alpha, interferon beta, and c-jun genes. Early-passage clone 7 cells exhibited chromosome 5 monosomy, while late-passage cells contained one normal chromosome 5 and a derivative (5q12q). Southern analysis of the three cell lines revealed no consistent loss of loci for the interferon and c-jun genes, although early-passage clone 7 cells had one half the gene copy number for the interferon beta and c-jun genes and both early- and late-passage clone 7 cells lacked DNA sequences hybridizing with the probe for interferon alpha. CONCLUSION This pattern of passage-dependent spontaneous transformation of rat ovarian surface epithelial cells in vitro supports the hypothesis that repetitious ovulation contributes to the etiology of human ovarian cancer.

Proteasomes are regulated by interferon gamma: implications for antigen processing

Abstract: Class I major histocompatibility complex (MHC) molecules present antigenic peptides of cytoplasmic origin to T cells. As the lengths of these peptides seem restricted to eight or nine amino acids, an unusual proteolytic system must play a role in antigen processing. Proteasomes, a major extralysosomal proteolytic system, are responsible for the degradation of cytoplasmic proteins. We demonstrate that several proteasomal subunits, including MHC-encoded subunits, are regulated by interferon gamma. These data and the finding that MHC-encoded and other interferon gamma-regulated proteasomal subunits are uniquely associated with proteasomes strongly suggest that the immune system has recruited proteasomes for antigen processing.

Downregulation of interleukin 8 gene expression in human fibroblasts: unique mechanism of transcriptional inhibition by interferon.

Abstract: The chemotactic cytokine interleukin 8 (IL-8) is produced upon stimulation by various agents in many cell types, including connective-tissue fibroblasts. Tumor necrosis factor (TNF) and IL-1 are potent inducers of IL-8 expression. Earlier we showed that TNF-induced stimulation of IL-8 mRNA accumulation in human FS-4 fibroblasts was inhibited by interferon beta (IFN-beta) or IFN-gamma. Here we show that this inhibition is not specific for TNF, since IFN-beta also reduced IL-8 mRNA accumulation induced by IL-1 or the double-stranded RNA poly (I-C). Treatment with IFN-beta also decreased TNF-induced IL-8 protein accumulation. Interestingly, the inhibitory effect was much less pronounced when IFN-beta was added greater than or equal to 1 hr before TNF. The inhibitory action of IFN-beta on IL-8 mRNA accumulation was undiminished in the presence of inhibitors of protein synthesis. Nuclear run-on assays demonstrated that IFN-beta caused a marked inhibition of TNF-induced IL-8 gene transcription; the transcriptional activation of several other TNF-induced genes was not inhibited by IFN-beta. The results suggest that the specific inhibition of the transcriptional activation of IL-8 by IFN is due either to a transient inactivation of a factor required for IL-8 transcription or to the activation of a selective inhibitory factor.

Hantaan virus infection of human endothelial cells.

Abstract: The primary pathophysiologic finding of the viral disease known as Korean hemorrhagic fever, the etiological agent of which is Hantaan virus (HTV), is vascular instability. To investigate whether HTV was able to infect cells derived from human vascular tissue and alter their behavior, we infected in vitro primary adult human endothelial cells from saphenous veins (HSVEC). We were able to detect the presence of viral antigens in infected cells both by immunofluorescence and by Western blot (immunoblot) analysis as early as day 1 postinfection. HSVEC infected with HTV produce infectious virus during the first 3 days of infection but, at later times (days 4 to 8), show decreasing yields of virus. This contrasts with the HTV growth pattern observed for the permissive simian CV-7 cell line, which generates infectious virus up to day 12 after infection. Further investigation showed that the late decrease in viral production in HSVEC is the result of the induction of beta interferon and can be reversed by the addition of anti-beta interferon serum to the culture medium. At no time during the course of infection of HSVEC with HTV was any obvious cytopathic effect observed. When tests for changes in mRNA levels of other cytokines and endothelial cell gene products following HTV infection of HSVEC were done by reverse transcription and polymerase chain reaction methods, no significant changes were observed in the levels of interleukin 1, interleukin 6, or von Willebrand factor mRNA. We hypothesize that, while HTV can replicate in human vascular endothelial cells, the mechanism of microvascular damage seen with Korean hemorrhagic fever is not likely to be a direct effect of virus replication but may conceivably be the consequence of an immune-mediated endothelial injury triggered by viral infection.

Inhibition of human erythroid colony‐forming units by interleukin‐1 is mediated by gamma interferon

Abstract: IL-1 inhibits erythropoiesis in vivo and in vitro. This inhibition was studied by comparing the effect of recombinant human IL-1 (rhIL-1) on highly purified CFU-erythroid (E) generated from peripheral blood burst-forming units-erythroid (BFU-E) (mean purity 44.4%) with its effect on unpurified marrow CFU-E (mean purity 0.36%). Colony formation by marrow CFU-E was significantly inhibited by rhIL-1, while colony formation by highly purified CFU-E was not inhibited. However, purified CFU-E colonies were inhibited by rhIL-1 in the presence of autologous T-lymphocytes, and also by cell-free conditioned medium prepared from T-lymphocytes stimulated by rhIL-1. This inhibitory effect was ablated by neutralizing antibodies to gamma interferon (IFN), but not by antibodies to human IL-1, tumor necrosis factor, or beta IFN. Colony formation by highly purified CFU-E was also inhibited by recombinant human gamma IFN (rh gamma IFN). IL-1 and gamma IFN play significant roles in the pathogenesis of the anemia of chronic disease. These studies indicate that rhIL-1 inhibits CFU-E colony formation by an indirect mechanism involving T-lymphocytes and requiring gamma IFN and that gamma IFN itself is most probably the direct mediator of this effect.

Autoimmune chronic hepatitis exacerbated by alpha-interferon.

Abstract: Excerpt Alpha-interferon is known to reduce viral replication, to normalize aminotransferase levels, and to reduce hepatic lesions in 40% of patients with chronic hepatitis caused by hepatitis C vi...

Constitutive expression of an ISGF2/IRF1 transgene leads to interferon-independent activation of interferon-inducible genes and resistance to virus infection.

Abstract: Interferon (IFN)-stimulated gene factor 2 (ISGF2) plays a role in transcription of the beta IFN (IFN-beta) gene and IFN-stimulated genes (ISGs) and may function as a central mediator of cytokine responses. Constitutive ISGF2 transgene expression resulted in substantial resistance to three RNA virus families. This phenotype was not a consequence of IFN production and may have arisen directly through ISG expression. ISGF2 acted generally as a positive transcription factor through binding sites from several genes, in the context of transient cotransfection. Constitutive transcription of the endogenous IFN-beta gene, and several genes that are normally induced by either IFN-alpha or IFN-gamma, or only by IFN-alpha, was elevated in cells that constitutively express an ISGF2 transgene. However, constitutive and virus-induced levels of IFN-beta mRNA were unaffected in such cell lines.

A comparison of interferon-Con1 with natural recombinant interferons-α : antiviral, antiproliferative, and natural killer-inducing activities

Abstract: The antiviral, antiproliferative, and natural killer (NK) cell activation by recombinant human interferon-consensus (IFN-Con1) has been compared with that of two other type I IFNs: IFN-alpha 2a (Roferon) and IFN-alpha 2b (Intron A). The specific activity (antiviral units/mg) of IFN-Con1 was 10-fold higher than that of the other two IFNs in the vesicular stomatitis virus (VSV)-HeLa antiviral assay. The antiproliferative activity on a molar basis of IFN-Con1 on Daudi cells and Eskol (a human leukemic hairy cell-like cell line) was significantly greater than that of IFN-alpha 2a and IFN-alpha 2b. IFN-Con1 also enhanced or induced NK cell killing of target cells to a greater extent than that of IFN-alpha 2a and IFN-alpha 2b. However, on antiviral unit basis, the activities were similar. These results would suggest that IFN-Con1 may be more effective at lower protein concentrations in clinical applications than other available IFNs.