State Of Target Cells Research Articles

The evolving role of interferons in viral eradication strategies

Interferons (IFNs) are a family of pleiotropic cytokines that are released when viral infection is sensed by pattern recognition receptors. They induce an antiviral state in target cells through influencing the expression of hundreds of genes termed IFN-stimulated genes (ISGs), which interfere with the replication of viruses in wide-ranging ways, and they have stimulatory effects on antiviral cell-mediated immunity. Although the role of therapeutic IFNs in the management of infectious diseases has predominantly been restricted to the treatment of chronic hepatotropic viruses, IFNs have effects on the replication of diverse families of viruses in cell culture models, and the potential to harness our endogenous defence system through therapeutic modulation of IFN pathways remains a tantalising prospect for both the broad-spectrum and tailored treatment of viral infections. Additionally, the study of the IFN system has become crucial to our understanding of host/pathogen molecular interactions, which provides plentiful targets for small molecule inhibitors of infection. Although the emergence of directly acting antivirals (DAAs) has resulted in the displacement of pegylated IFNα (pegIFNα) for the treatment of HCV, recent findings have suggested potential roles for IFNs and IFN-related therapies in HIV and HBV eradication strategies, opening up a new avenue of research for this important family of cytokines.

WISH cell line: From the antiviral system to a novel reporter gene assay to test the potency of human IFN-α and IFN-β

Interferons (IFNs) are potent biologically active proteins that are widely used as biopharmaceuticals, so their potency must be correctly identified. Usually, the biological activity is quantified by a bioassay based on its capacity to induce an antiviral state in target cells, but this type of assays is subject to virus manipulation-related issues and they show considerable intra- and inter-assay variability.In this work, we generated a reporter gene assay (RGA) supported on the WISH-Mx/eGFP reporter cell line to determine human type I IFN activity. WISH cells were stably transfected with the enhanced green fluorescent protein (eGFP) gene under the control of type I IFN-inducible Mx2 promoter.This system implies the use of a standardized cell line for human IFN-potency analysis such as WISH cells and the simultaneous use of the sensitive reporter gene eGFP, having also several advantages when compared to antiviral activity assays and other RGAs: it can determine the potency of hIFN-α and hIFN-β using only one cell line showing the highest expression of eGFP after 28h and being only observed in cells treated with type I IFNs due to the specificity of the Mx promoter. It is a sensitive assay and it represents a safe alternative when compared with the conventional antiviral tests. The cell line showed the same sensitivity along 57 generations, allowing its use during two months of successive culture. The inter- and intra-assay coefficients of variation were lower than 20%, demonstrating its reproducibility. In addition, this reporter cell line can be used for the conventional antiviral assay, either for hIFN-α or hIFN-β.In conclusion, we have developed an alternative reporter system for the analysis of type I IFNs, in which its performance make it a suitable candidate to replace or complement conventional bioassays that are currently employed to measure IFN potency.

MiRNA Lentiviral Vector Integration and Gene Targeting Efficacy in Cardiac Progenitors

Stem and progenitor cardiac cells are challenging for possible cell therapy application. Several research laboratories are exploiting the feasibility of autologous cell therapy approach to get rid of immunosuppressive treatments responsible for undesirable side effects. Recently, we showed that cardiac progenitors isolated from Sgcb null mice, animal model of limb-girdle muscular dystrophy type 2E, undergo an aberrant differentiation in vitro and in vivo due to the dysregulation of miR669. This miRNA family is able to inhibit the skeletal myogenic program directly targeting MyoD 3’ UTR. Using lentiviral technology we provided evidence that it is possible to rescue the dystrophic aberrant phenotype by miRNA669overexpression without gene correction. However, how the viruses carrying the miRNAs were positioned in the genome upon transduction and how their localization site could influence the rescue potential was not analysed. Here we investigate the integration profile of lentiviral vector carrying the pre-miR669 in infected polyclonal and clonal populations derived from Sgcb cardiac progenitors. Our study reveals that the retroviral insertion sites (RIS) are largely restricted to coding genes (65%). Although with the limitation of our analysis, we found no hits for cancer-related genes and several sequenced RIS brought to light genes mainly involved in muscle function. Thus our data show that lentiviral vector insertional profile is cell-specific, however, the chromatin state of target cells positively influences the viral integrations.

New reporter cell clones to determine the biological activity of human type I interferons

Background Interferons (IFNs) are potent biologically active proteins synthesized and secreted by somatic cells of all mammalian species. They play an important role in the immune response and defence against viruses because they have antiproliferative, antiviral and immunomodulatory activities [1]. They are widely used as biopharmaceuticals, so their potency must be correctly identified. Usually, the biological activity is quantified by a bioassay based on its capacity to induce an antiviral state in target cells. Antiviral assays may be subject to high interand intraassay variations having the drawbacks of using viruses [2]. Therefore, a set a new human cell lines derived from different tissues were developed using the enhanced green fluorescent protein (eGFP) gene under the control of type I IFN-inducible Mx2 promoter. In addition, having reporter gene assays derived from cells of different tissue origins would allow us to design studies aiming to evaluate how IFNs induce their actions through the human body.

Interferon Gamma: Activity and ELISA Detection Comparisons

Interferon-gamma (IFN-γ) is a pleiotropic cytokine secreted by Natural Killer (NK) cells and many T cells. It is the sole representative of Type II IFN. IFN-γ has pleiotropic activities including: inducing an antiviral state in cells, upregulating cell surface markers such as Class I and II MHC, and regulating the activity of macrophages, NK cells, neutrophils, B-cells, and T-cells. As such, IFN-γ is one of the most widely studied proteins [Scroder et al (2004) J. Leuk. Biol. 75:163; Young and Bream (2007) Curr. Top. Microbiol. Immunol. 316:97].

How does interferon inhibit HCV cell entry?

Hepatitis C virus (HCV), the sole member of the Hepacivirus genus of the Flaviviridae family, is an enveloped virus with a positive-sense single-stranded RNA genome of 9600 nucleotides. HCV virions...

The dependence of the antibacterial effect of the polycationic peptide warnerin on the energy state of target cells

The bactericidal effect of the polycationic peptide warnerin, produced by Staphylococcus warneri IEGM KL-1, was found to depend on the energy state of susceptible Staphylococcus epidermidis cells. The pre-treatment of these cells with compounds that diminish the proton-motive force of plasma membranes enhanced cell tolerance to warnerin. The components deltapsi and deltapH of the membrane proton potential influenced the antibacterial activity of warnerin in different ways. In particular, the antibacterial activity of warnerin decreased when the electric component of the proton-motive force of target membranes declined.

The transcription factor B-Myb is maintained in an inhibited state in target cells through its interaction with the nuclear corepressors N-CoR and SMRT.

The B-Myb transcription factor has been implicated in coordinating the expression of genes involved in cell cycle regulation. Although it is expressed in a ubiquitous manner, its transcriptional activity is repressed until the G(1)-S phase of the cell cycle by an unknown mechanism. In this study we used biochemical and cell-based assays to demonstrate that the nuclear receptor corepressors N-CoR and SMRT interact with B-Myb. The significance of these B-Myb-corepressor interactions was confirmed by the finding that B-Myb mutants, which were unable to bind N-CoR, exhibited constitutive transcriptional activity. It has been shown previously that phosphorylation of B-Myb by cdk2/cyclin A enhances its transcriptional activity. We have now determined that phosphorylation by cdk2/cyclin A blocks the interaction between B-Myb and N-CoR and that mutation of the corepressor binding site within B-Myb bypasses the requirement for this phosphorylation event. Cumulatively, these findings suggest that the nuclear corepressors N-CoR and SMRT serve a previously unappreciated role as regulators of B-Myb transcriptional activity.

Type I Interferon Is a Powerful Inhibitor of in Vivo HIV-1 Infection and Preserves Human CD4+ T Cells from Virus-Induced Depletion in SCID Mice Transplanted with Human Cells

Although several studies are available on the in vitro inhibitory activities of type I interferon (IFN) on HIV-1 replication, the role of these cytokines in the pathogenesis of AIDS is still matter of conjecture. Both beneficial and adverse effects have been envisaged and considered as a possible rationale for the development of either IFN or anti-IFN therapies in HIV-1-infected patients. In the present study, we have evaluated the efficacy of human type I IFN on HIV-1 infection and virus-induced depletion of human CD4 T cells in two models established in SCID mice. In SCID mice transplanted with human U937 cells (U937-SCID mouse model), continuous treatment with type I consensus IFN (CIFN) resulted in a total suppression of HIV-1 infection. This inhibitory effect was superior to that obtained after AZT treatments. Results from an ensemble of experiments in SCID mice transplanted with either control or genetically modified human U937 cells transduced with a Tat-inducible IFN-α gene (LTR-IFN-A2 U937) indicated that low levels of IFN-α, produced locally as a result of virus infection, were extremely effective in inhibiting acute HIV infection and virus replication. Of interest, LTR-IFN-A2 U937 cells conferred a strong anti-HIV-1 protection to coinjected bystander U937 cells. Notably, experiments with SCID mice reconstituted with human PBL (hu-PBL-SCID mouse model) showed that treatment with CIFN inhibited HIV-1 replication more effectively than AZT treatment. Remarkably, treatment with CIFN resulted in a clear-cut protection from the virus-induced depletion of human CD4 T cells, which was also associated with the generation of an antibody response toward HIV-1 antigens in 50% of the virus-injected xenografts. These results suggest that type I IFN efficiently preserves human CD4+ cells from virus-induced damage in hu-PBL-SCID mice, not only by inducing an antiviral state in target cells but also by stimulating anti-HIV-1 human immune responses in vivo.