The Third Signal Cytokine IL-12 Rescues the Anti-Viral Function of Exhausted HBV-Specific CD8 T Cells
Open Access
- 14 March 2013
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLoS Pathogens
- Vol. 9 (3), e1003208
- https://doi.org/10.1371/journal.ppat.1003208
Abstract
Optimal immune activation of naïve CD8 T cells requires signal 1 mediated by the T cell receptor, signal 2 mediated by co-stimulation and signal 3 provided by pro-inflammatory cytokines. However, the potential for signal 3 cytokines to rescue anti-viral responses in functionally exhausted T cells has not been defined. We investigated the effect of using third signal cytokines IL-12 or IFN-α to rescue the exhausted CD8 T cell response characteristic of patients persistently infected with hepatitis B virus (HBV). We found that IL-12, but not IFN-α, potently augmented the capacity of HBV-specific CD8 T cells to produce effector cytokines upon stimulation by cognate antigen. Functional recovery mediated by IL-12 was accompanied by down-modulation of the hallmark inhibitory receptor PD-1 and an increase in the transcription factor T-bet. PD-1 down-regulation was observed in HBV but not CMV-specific T cells, in line with our finding that the highly functional CMV response was not further enhanced by IL-12. IL-12 enhanced a number of characteristics of HBV-specific T cells important for viral control: cytotoxicity, polyfunctionality and multispecificity. Furthermore, IL-12 significantly decreased the pro-apoptotic molecule Bim, which is capable of mediating premature attrition of HBV-specific CD8 T cells. Combining IL-12 with blockade of the PD-1 pathway further increased CD8 functionality in the majority of patients. These data provide new insights into the distinct signalling requirements of exhausted T cells and the potential to recover responses optimised to control persistent viral infections. Persistent viral infections continue to cause major morbidity and mortality; chronic hepatitis B virus infection alone accounts for more than a million deaths annually. Such infections are characterised by a failure of viral control perpetuated by exhaustion of the T cell response. Here we show that the cytokine IL-12 can act as a potent “third signal” to rescue antiviral function in exhausted T cells. IL-12 has previously been shown to enhance naïve T cell responses but this is the first demonstration of its capacity to boost the disabled antiviral response in a persistent viral infection. IL-12 was able to down-regulate PD-1, a key inhibitory receptor driving T cell exhaustion, resulting in the recovery of hepatitis B virus-specific responses able to mediate multiple antiviral functions. Control responses in the same patients directed against the well-controlled cytomegalovirus did not require IL-12 to function efficiently. Our findings therefore elucidate a role for IL-12 in re-programming functionally exhausted T cells in persistent viral infections.Keywords
This publication has 39 references indexed in Scilit:
- IL-12 upregulates TIM-3 expression and induces T cell exhaustion in patients with follicular B cell non-Hodgkin lymphomaJCI Insight, 2012
- Transcription factor T-bet represses expression of the inhibitory receptor PD-1 and sustains virus-specific CD8+ T cell responses during chronic infectionNature Immunology, 2011
- Inflammatory cytokines as a third signal for T cell activationCurrent Opinion in Immunology, 2010
- Semliki Forest Virus Expressing Interleukin-12 Induces Antiviral and Antitumoral Responses in Woodchucks with Chronic Viral Hepatitis and Hepatocellular CarcinomaJournal of Virology, 2009
- Cell-Intrinsic Transforming Growth Factor-β Signaling Mediates Virus-Specific CD8+ T Cell Deletion and Viral Persistence In VivoImmunity, 2009
- Intrahepatic Murine CD8 T-Cell Activation Associates With a Distinct Phenotype Leading to Bim-Dependent DeathGastroenterology, 2008
- Functional skewing of the global CD8 T cell population in chronic hepatitis B virus infectionThe Journal of Experimental Medicine, 2008
- Inflammation Directs Memory Precursor and Short-Lived Effector CD8+ T Cell Fates via the Graded Expression of T-bet Transcription FactorImmunity, 2007
- Characterization of Hepatitis B Virus (HBV)-Specific T-Cell Dysfunction in Chronic HBV InfectionJournal of Virology, 2007
- Interleukin-10 determines viral clearance or persistence in vivoNature Medicine, 2006