PADIS

Pubblicazioni Aperte DIgitali Sapienza > Biotecnologie cellulari ed ematologia > SCIENZE PASTEURIANE >

Please use this identifier to cite or link to this item: http://hdl.handle.net/10805/2235

Title: T cell exhaustion and microRNAs
Authors: PROIA, ALESSANDRA
Tutor: Barnaba, Vincenzo
Keywords: T cell exhaustion
cytokines
effector functions
inhibitory receptors
PD-1
TIM-3
microRNAs
miR-21
Issue Date: 29-Feb-2012
Abstract: Functional exhaustion of antigen-specific T cells is a feature of many chronic viral infections and the role of miRNAs in this process are not well understood. A typical exhausted T cell is characterized by dysfunctional responses such as low proliferative potential and decreased ability of cytokine production such IL-2, TNF-α and IFN-γ. These defects have been associated with upregulation of inhibitory receptors such as programmed death-1 ( PD-1), a member of the B7:CD28 family, capable to induce T cell exhaustion following the interaction with its own ligands (PD-L1 expressed on all cells and/or PD-L2 particularly expressed on dendritic cells). In this project we studied the early phases of PD-1-dependent T cell exhaustion in healthy individuals and we correlated this phenomenon with the microRNAs profile in these cells. PD-1 positive and PD-1 negative PBL populations from six healthy donors were FACS-sorted and the functional features of CD4+ and CD8+ T cells/ expressing or not PD-1 were analyzed for the intracellular cytokine production in response to polyclonal stimuli. The exhaustion is a gradual process in which IL-2 production is the first function to be lost: our data demonstrated that two samples analyzed were characterized by PBLs/PD-1+ in terminal exhaustion because they produced less IL-2 and IFN-γ after antiCD3/CD28 stimulation than PD-1- T cells; the other four samples analyzed instead were characterized by T lymphocytes in early exhaustion, because PD-1+ T cells produced only less IL-2 when stimulated with antiCD3-CD28. This result demonstrates that PD-1 expression correlates with different degree of exhaustion. To validate both PD-1 and TIM-3 as exhaustion markers, we stimulated T cell clones with mitogenic stimuli in vitro and we analyzed the expression level of both PD-1 and TIM-3, as well as the cytokine production upon the appropriate stimuli. In these conditions, T cell clones upregulated both PD-1 and TIM-3 in relation with impaired cytokine production. Interestingly, upon repeated rounds of stimulation in vitro, T cell clones rescued the capacity of performing their functions in relation with a dramatic downregulation of both PD-1 and TIM-3, suggesting that the exhaustion phenomenon is reversible. This was confirmed by experiments showing rescued cytokine production by PD-1+ T cell clones that had been stimulated in the presence of a blocking anti-PD-L1 antibody. To identify candidate microRNAs in early phases of the exhaustion process, we analyzed the microRNAs expression profile by Taqman Low density array on PD-1+ T cells producing low amounts of IL-2, but normal IFN- The analyses showed that only 23 microRNAs are deregulated in PD-1+ PBLs compared to PD-1- PBLs and that miR-21 resulted the most upregulated. The upregulation of miR-21 were also validated by RT-PCR in functionally-exhausted CD4+ T cell clones coexpressing PD-1 and TIM-3. This dimostrated that miR-21 could be a candidate microRNA in the early phases of T cell exhaustion.
URI: http://hdl.handle.net/10805/2235
Research interests: Immunology
Appears in PhD:SCIENZE PASTEURIANE

Files in This Item:

File Description SizeFormat
Alessandra_Proia_XXIVciclo_TESI_DOTTORATO.pdf1.42 MBAdobe PDF


This item is protected by original copyright

Recommend this item

Items in PADIS are protected by copyright, with all rights reserved, unless otherwise indicated.

 

Valid XHTML 1.0! DSpace Software Copyright © 2002-2010  Duraspace - Feedback Sviluppo e manutenzione a cura del CINECA