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Combining regulatory T cell depletion and inhibitory receptor blockade improves reactivation of exhausted virus-specific CD8+ T cells and efficiently reduces chronic retroviral loads.

ABSTRACT: 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.

SUBMITTER: Dietze KK

PROVIDER: S-EPMC3855586 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Combining regulatory T cell depletion and inhibitory receptor blockade improves reactivation of exhausted virus-specific CD8+ T cells and efficiently reduces chronic retroviral loads.

Dietze Kirsten K KK Zelinskyy Gennadiy G Liu Jia J Kretzmer Freya F Schimmer Simone S Dittmer Ulf U

PLoS pathogens 20131205 12

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 chro ...[more]

PMID: 24339778

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Project description:Background. The blood-brain barrier (BBB) regulates immune cell entry into the CNS, and various strategies have been developed to target this barrier in efforts to alleviate neuroinflammation in neurodegenerative diseases. α4β1 is crucial for T cell influx into the CNS. In the context of HIV, CD4 T cells drive viral infiltration, while CD8 T cells are essential for viral clearance. This dual role complicates strategies aimed at targeting T cell entry during HIV infection, yet it remains an area that has not been thoroughly explored. Methods. We investigated the impact of disrupting α4-mediated T cell entry into the CNS in SIVmac251-infected rhesus macaques treated with an α4-blocking antibody (n=4) versus an isotype control (n=4). Our comprehensive approach included single-cell analysis of CD45+ cells in the brain and spleen, spatial transcriptomics of the hippocampus, viral load measurements, and flow cytometry on brain tissue. Results. Single-cell analysis revealed a marked reduction in the brain CD8 TEM cluster, particularly in cells expressing Granulysin, CCL5, and STAT4, while CD4 T cell clusters remained unchanged, and two monocyte clusters were enriched. This shift was accompanied by an increase in brain SIV RNA+ CD45+ CD4+ T cells in the α4-treated group (vRNA+ cells = 60) compared to controls (n=11). Spatial transcriptomics of SIV vRNA+ versus SIV vRNA- regions in the hippocampus of α4-treated macaques showed enrichment of CD4 TCM and monocyte gene signatures. Correspondingly, quantitative PCR revealed higher vRNA levels in the gray matter of the PFC, STS, and Hp. These findings suggest that α4 blockade selectively disrupts CD8 TEM populations while sparing CD4 T cells, leading to elevated viral loads and heightened neuroinflammation. The increase in SIV RNA+ CD4+ T cells and viral loads in the gray matter furthermore underscores the compartmentalized effect of α4-mediated immune modulation on viral dynamics across distinct brain regions Conclusion. These results underscore the critical need to evaluate immune-targeting therapies, with implications for strategies aimed at controlling T cell influx in the context of viral infections in the brain.

Dataset Information

Combining regulatory T cell depletion and inhibitory receptor blockade improves reactivation of exhausted virus-specific CD8+ T cells and efficiently reduces chronic retroviral loads.

Publications

Combining regulatory T cell depletion and inhibitory receptor blockade improves reactivation of exhausted virus-specific CD8+ T cells and efficiently reduces chronic retroviral loads.

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