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PD-L1 partially protects renal tubular epithelial cells from the attack of CD8+cytotoxic T cells

Waeckerle-Men, Ying ; Starke, Astrid ; Wüthrich, Rudolf P.

In: Nephrology Dialysis Transplantation, 2007, vol. 22, no. 6, p. 1527-1536

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    Titel
    • PD-L1 partially protects renal tubular epithelial cells from the attack of CD8+cytotoxic T cells
    Autor
    • Waeckerle-Men, Ying. Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zürich-Irchel and Clinic for Nephrology, University Hospital Zürich, Switzerland
    • Starke, Astrid. Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zürich-Irchel and Clinic for Nephrology, University Hospital Zürich, Switzerland
    • Wüthrich, Rudolf P.. Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zürich-Irchel and Clinic for Nephrology, University Hospital Zürich, Switzerland
    Dokumententyp
    • Postprint
    Sprache
    • Englisch
    Veröffentlicht in
    • Nephrology Dialysis Transplantation, 2007, vol. 22, no. 6, p. 1527-1536. Oxford University Press
    Andere elektronische Ausgabe
    OAI-PMH-ID
    • oai:doc.rero.ch:294945
    Summary
    Background. Activated infiltrating T cells play a crucial role in nephritic inflammation via the direct interaction with proximal tubular epithelial cells (TEC). Under inflammatory conditions, major histocompatibility complex class I and II molecules are upregulated on the surface of renal TEC, enabling them to function as ‘non-professional' antigen-presenting cells (APC) to activate T cells, and, in turn to be targeted by cytotoxic T lymphocytes (CTL) to cause tissue damage. It is known that co-stimulatory (e.g. B7/CD28) and co-inhibitory (e.g. PD-L1/PD-1) signals regulate and determine the magnitude of T cell responses. In this study, we examined the expression of co-stimulatory molecule PD-L1 by renal TEC and the functional role of renal PD-L1/PD-1 pathway in regulating CD8+ T cell responses induced by antigen-presenting renal TEC. Methods. Renal TEC were treated with type I and type II interferons (IFN-α, IFN-β or IFN-γ). PD-L1 expression was then determined with flow cytometry and RT-PCR. To investigate the functional role of renal epithelial PD-L1 on CD8+ CTL responses, H-2Kb-restricted, OVA257-264 peptide-specific CD8+ T cells isolated from OT-1 T cell receptor transgenic mice were co-incubated with IFN-stimulated, OVA257-264 peptide-pulsed congeneic TEC. The activation of OT-1 CD8+ CTL was estimated either by IFN-γ production in the supernatants of co-cultures or by CTL activity. Results. TECs do not constitutively express PD-L1 on their surface. However, a strong and dose-dependent upregulation of PD-L1 was observed on TEC after stimulation with IFN-β or IFN-γ, but not with IFN-α. OVA257-264 peptide pulsed-TEC were able to activate OT-1 CD8+ T cells, indicated by the high amount of IFN-γ production and cytolysis of TEC. Blockade of epithelial PD-L1 with specific mAb significantly increased OT-1 CD8+ T cell activity, indicating that the PD-L1 pathway has a negative effect on CD8+ T cell responses. Moreover, IFN- β- or IFN-γ-stimulated TEC with high surface PD-L1 expression were more resistant to the cytolysis by OT-1 CTL. Conclusion. Together our data reveal that the renal PD-L1/PD-1 pathway has a negative effect on CD8+ CTL activation. PD-L1 might, therefore, act as a protective molecule on TEC, downregulating the cytotoxic renal parenchymal immune response