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EBV stimulates TLR- and autophagy-dependent pathways and impairs maturation

Discussion in 'Other Health News and Research' started by Ecoclimber, Aug 26, 2014.

  1. Ecoclimber

    Ecoclimber Senior Member

    Eur J Immunol. 2013 Jan;43(1):147-58. doi: 10.1002/eji.201242552. Epub 2012 Oct 30.
    EBV stimulates TLR- and autophagy-dependent pathways and impairs maturation in plasmacytoid dendritic cells: implications for viral immune escape.
    Severa M1, Giacomini E, Gafa V, Anastasiadou E, Rizzo F, Corazzari M, Romagnoli A, Trivedi P, Fimia GM, Coccia EM.
    Author information


    Plasmacytoid DCs (pDCs) are crucial mediators in the establishment of immunity against most viruses, given their extraordinary capacity to produce a massive quantity of type I IFN.

    In this study we investigate the response of pDCs to infection with EBV, a γ-herpes virus that persists with an asymptomatic infection in immunocompetent hosts, although in certain conditions it can promote development of cancers or autoimmune diseases. We show that high amounts of type I IFNs were released from isolated pDCs after exposure to EBV by a mechanism requiring TLRs and a functional autophagic machinery. We next demonstrate that EBV can infect pDCs via viral binding to MHC class II molecule HLA-DR and that pDCs express EBV-induced latency genes.

    Furthermore, we observe that EBV is able to induce activation but not maturation of pDCs, which correlates with an impaired TNF-α release. Accordingly, EBV-infected pDCs are unable to mount a full T-cell response, suggesting that impaired pDC maturation, combined with a concomitant EBV-mediated upregulation of the T-cell inhibitory molecules B7-H1 and ICOS-L, could represent an immune-evasion strategy promoted by the virus. These mechanisms might lead to persistence in immunocompetent hosts or to dysregulated immune responses linked to EBV-associated diseases.

    © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

    Hum Immunol. 2014 Apr;75(4):306-16. doi: 10.1016/j.humimm.2014.02.002. Epub 2014 Feb 12.
    Epstein-Barr virus induces the differentiation of semi-mature dendritic cells from cord blood monocytes.
    Jin YY1, Wang X2, Du J2, Cao RM2, Law HK3, Wang JJ2, Chen TX4.
    Author information

    Epstein-Barr virus (EBV) is a tumorigenic virus which has effectively infected nearly all human beings with over 95% adult being seropositive. The persistence of latent EBV infection is not fully understood. Recent studies point towards a hypothesis of immune suppression and immune evasion involving regulatory T cells (Tregs) and dendritic cells (DCs). We sought to explore the mechanism of EBV suppression and immune evasion.

    We compared the effects of EBV on cord blood (CB) and adult DCs differentiation and maturation including phenotype by flow cytometry, cytokine by ELISA and RT-PCR. And we evaluated the function of DC by co-culture DC and Treg by detection the expression of Foxp3, the phenotype and the cytokine profile of Tregs by flow cytometry.

    CB DCs derived from EBV-infected CB monocytes or from EBV-infected CB immature DCs (iDCs) displayed distinct phenotypes of "semi-mature" DCs with high expression of co-stimulatory molecules, such as CD40, CD80 and CD86 but low cytokine production, related to immune tolerance and homeostasis. While the EBV-infected adult iDCs resemble that of "pathogen-driven regulatory mature DCs" with high expression of co-stimulatory molecules, down-regulation of IL-12 secretion and up-regulation of IL-10 secretion, related to protection of host and immune evasion of pathogens. EBV infected cord blood monocytes-derived DCs drived Tregs development by driving the expression of Foxp3, increasing the expression of CTLA-4, decreasing the expression of GITR and promoted the generation of intracellular IL-2 and IL-10 by Tregs.

    Epstein-Barr virus induces the differentiation of semi-mature dendritic cells from cord blood monocytes. The differences between CB and adult DCs suggested that the developmental maturity of the cells may affect their immune responses to EBV infection.

    Copyright © 2014 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.
    NK17 and heapsreal like this.

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