Combining Regulatory T Cell Depletion and Inhibitory Receptor Blockade Improves Reactivation of Exhausted Virus-Specific CD8+ T Cells and Efficiently Reduces …

KK Dietze, G Zelinskyy, J Liu, F Kretzmer… - PLoS …, 2013 - journals.plos.org
KK Dietze, G Zelinskyy, J Liu, F Kretzmer, S Schimmer, U Dittmer
PLoS pathogens, 2013journals.plos.org
Chronic infections with human viruses, such as HIV and HCV, or mouse viruses, such as
LCMV or Friend Virus (FV), result in functional exhaustion of CD8+ T cells. Two main
mechanisms have been described that mediate this exhaustion: expression of inhibitory
receptors on CD8+ T cells and expansion of regulatory T cells (Tregs) that suppress CD8+ T
cell activity. Several studies show that blockage of one of these pathways results in
reactivation of CD8+ T cells and partial reduction in chronic viral loads. Using blocking …
Chronic infections with human viruses, such as HIV and HCV, or mouse viruses, such as LCMV or Friend Virus (FV), result in functional exhaustion of CD8+ T cells. Two main mechanisms have been described that mediate this exhaustion: expression of inhibitory receptors on CD8+ T cells and expansion of regulatory T cells (Tregs) that suppress CD8+ T cell activity. Several studies show that blockage of one of these pathways results in reactivation of CD8+ T cells and partial reduction in chronic viral loads. Using blocking antibodies against PD-1 ligand and Tim-3 and transgenic mice in which Tregs can be selectively ablated, we compared these two treatment strategies and combined them for the first time in a model of chronic retrovirus infection. Blocking inhibitory receptors was more efficient than transient depletion of Tregs in reactivating exhausted CD8+ T cells and reducing viral set points. However, a combination therapy was superior to any single treatment and further augmented CD8+ T cell responses and resulted in a sustained reduction in chronic viral loads. These results demonstrate that Tregs and inhibitory receptors are non-overlapping factors in the maintenance of chronic viral infections and that immunotherapies targeting both pathways may be a promising strategy to treat chronic infectious diseases.
PLOS