scholarly journals Functionally Competent, PD-1+ CD8+ Trm Cells Populate the Brain Following Local Antigen Encounter

2021 ◽  
Vol 11 ◽  
Author(s):  
Amalie Skak Schøller ◽  
Loulieta Nazerai ◽  
Jan Pravsgaard Christensen ◽  
Allan Randrup Thomsen
Keyword(s):  
T Cells ◽  
T Cell ◽  
Viral Vector ◽  
T Cell Memory ◽  
T Cell Exhaustion ◽  
Chronic Infections ◽  
Cell Memory ◽  
Cell Exhaustion ◽  
Monocytes And Macrophages ◽  
T Cell Survival

Expression of programmed cell death-1 receptor (PD-1) has traditionally been linked to T-cell exhaustion, as signaling via PD-1 dampens the functionality of T-cells upon repetitive antigen exposures during chronic infections. However, resent findings pointing to the involvement of PD-1 both in T-cell survival and in restraining immunopathology, challenge the concept of PD-1 solely as marker for T-cell exhaustion. Tissue resident memory T cells (Trms) hold unique effector qualities, but within a delicate organ like the CNS, these protective abilities could potentially be harmful. In contrast to their counterparts in many other tissues, brain derived CD8+ Trms have been found to uniformly and chronically express PD-1. In this study we utilized a recently established model system for generating CNS Trms in order to improve our understanding regarding the role of PD-1 expression by Trms inside the CNS. By intracerebral (i.c.) inoculation with a non-replicating adeno-viral vector, we induced a PD-1hi CD8+ T cell memory population within the CNS. We found that PD-1 expression lowered the severity of clinical disease associated with the i.c. inoculation. Furthermore, high levels of PD-L1 expression were found on the infiltrating monocytes and macrophages as well as on the resident microglia, oligodendrocytes and astrocytes during the acute phase of the response. Additionally, we showed that the intensity of PD-1 expression correlates with local antigen encounter and found that PD-1 expression was associated with decreased CD8+ T cell memory formation in the CNS despite an increased number of infiltrating CD8+ T cells. Most importantly, our experiments revealed that despite expression of PD-1 and several additional markers linked to T-cell exhaustion, Tim-3, Lag-3 and CD39, the cells did not show signs of limited effector capacity. Collectively, these results endorse the increasing amount of evidence pointing to an immune-modifying role for PD-1 expression within the CNS, a mechanism we found to correlate with local antigen exposure.

scholarly journals Differentiation of exhausted CD8 T cells after termination of chronic antigen stimulation stops short of achieving functional T cell memory

2021 ◽  
Author(s):  
Pierre Tonnerre ◽  
David Wolski ◽  
Sonu Subudhi ◽  
Jihad Al-Jabban ◽  
Ruben C. Hoogeveen ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Hcv Infection ◽  
Viral Escape ◽  
T Cell Memory ◽  
T Cell Exhaustion ◽  
Cell Memory ◽  
Cell Exhaustion ◽  
Antigen Removal

T cell exhaustion is associated with failure to clear chronic infections and malignant cells. Defining the molecular mechanisms of T cell exhaustion and reinvigoration is essential to improving immunotherapeutic modalities. Analysis of antigen-specific CD8+ T cells before and after antigen removal in human hepatitis C virus (HCV) infection confirmed pervasive phenotypic, functional, and transcriptional differences between exhausted and memory CD8+ T cells. After viral cure, we observed broad phenotypic and transcriptional changes in clonally stable exhausted T-cell populations suggesting differentiation towards a memory-like profile. However, functionally, the cells showed little improvement and critical transcriptional regulators remained in the exhaustion state. Notably, T cells from chronic HCV infection that were exposed to antigen for shorter periods of time because of viral escape mutations were functionally and transcriptionally more similar to memory T cells from spontaneously resolved acute HCV infection. Thus, duration of T cell stimulation impacts the ability to recover from exhaustion, as antigen removal after long-term T cell exhaustion is insufficient for the development of key T cell memory characteristics.

Abstract A86: PI3Kγ inhibition activates T cell memory and relieves T cell exhaustion

2020 ◽  
Author(s):  
Hideyuki Takahashi ◽  
Paulina Pathria ◽  
Ryan Shepard ◽  
Ann Shih ◽  
Tiani L. Louis ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Memory ◽  
T Cell Exhaustion ◽  
Cell Memory ◽  
Cell Exhaustion

scholarly journals Immune Exhaustion: Past Lessons and New Insights from Lymphocytic Choriomeningitis Virus

Viruses ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 156 ◽  
Author(s):  
Shannon Kahan ◽  
Allan Zajac
Keyword(s):  
T Cells ◽  
T Cell ◽  
Experimental System ◽  
Lymphocytic Choriomeningitis ◽  
Lymphocytic Choriomeningitis Virus ◽  
T Cell Exhaustion ◽  
Chronic Infections ◽  
Cell Exhaustion ◽  
Adult Mice ◽  
Track Record

Lymphocytic choriomeningitis virus (LCMV) is a paradigm-forming experimental system with a remarkable track record of contributing to the discovery of many of the fundamental concepts of modern immunology. The ability of LCMV to establish a chronic infection in immunocompetent adult mice was instrumental for identifying T cell exhaustion and this system has been invaluable for uncovering the complexity, regulators, and consequences of this state. These findings have been directly relevant for understanding why ineffective T cell responses commonly arise during many chronic infections including HIV and HCV, as well as during tumor outgrowth. The principal feature of exhausted T cells is the inability to elaborate the array of effector functions necessary to contain the underlying infection or tumor. Using LCMV to determine how to prevent and reverse T cell exhaustion has highlighted the potential of checkpoint blockade therapies, most notably PD-1 inhibition strategies, for improving cellular immunity under conditions of antigen persistence. Here, we discuss the discovery, properties, and regulators of exhausted T cells and highlight how LCMV has been at the forefront of advancing our understanding of these ineffective responses.

scholarly journals Skeletal muscle antagonizes antiviral CD8+ T cell exhaustion

2020 ◽  
Vol 6 (24) ◽  
pp. eaba3458 ◽  
Author(s):  
Jingxia Wu ◽  
Nina Weisshaar ◽  
Agnes Hotz-Wagenblatt ◽  
Alaa Madi ◽  
Sicong Ma ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
T Cells ◽  
T Cell ◽  
Muscle Mass ◽  
Lymphoid Tissues ◽  
Proliferative Potential ◽  
T Cell Exhaustion ◽  
Chronic Infections ◽  
Cell Exhaustion ◽  
Body Weight Reduction

CD8+ T cells become functionally impaired or “exhausted” in chronic infections, accompanied by unwanted body weight reduction and muscle mass loss. Whether muscle regulates T cell exhaustion remains incompletely understood. We report that mouse skeletal muscle increased interleukin (IL)–15 production during LCMV clone 13 chronic infection. Muscle-specific ablation of Il15 enhanced the CD8+ T cell exhaustion phenotype. Muscle-derived IL-15 was required to maintain a population of CD8+CD103+ muscle-infiltrating lymphocytes (MILs). MILs resided in a less inflamed microenvironment, expressed more T cell factor 1 (Tcf1), and had higher proliferative potential than splenic T cells. MILs differentiated into functional effector T cells after reentering lymphoid tissues. Increasing muscle mass via muscle-specific inhibition of TGFβ signaling enhanced IL-15 production and antiviral CD8+ T cell responses. We conclude that skeletal muscle antagonizes T cell exhaustion by protecting T cell proliferative potential from inflammation and replenishing the effector T cell progeny pool in lymphoid organs.

scholarly journals Genetic absence of PD-1 promotes accumulation of terminally differentiated exhausted CD8+ T cells

2015 ◽  
Vol 212 (7) ◽  
pp. 1125-1137 ◽  
Author(s):  
Pamela M. Odorizzi ◽  
Kristen E. Pauken ◽  
Michael A. Paley ◽  
Arlene Sharpe ◽  
E. John Wherry
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Cd8 T Cell ◽  
Lymphocytic Choriomeningitis ◽  
T Cell Exhaustion ◽  
Cell Exhaustion ◽  
Cell Dysfunction ◽  
T Cell Dysfunction ◽  
T Cell Survival

Programmed Death-1 (PD-1) has received considerable attention as a key regulator of CD8+ T cell exhaustion during chronic infection and cancer because blockade of this pathway partially reverses T cell dysfunction. Although the PD-1 pathway is critical in regulating established “exhausted” CD8+ T cells (TEX cells), it is unclear whether PD-1 directly causes T cell exhaustion. We show that PD-1 is not required for the induction of exhaustion in mice with chronic lymphocytic choriomeningitis virus (LCMV) infection. In fact, some aspects of exhaustion are more severe with genetic deletion of PD-1 from the onset of infection. Increased proliferation between days 8 and 14 postinfection is associated with subsequent decreased CD8+ T cell survival and disruption of a critical proliferative hierarchy necessary to maintain exhausted populations long term. Ultimately, the absence of PD-1 leads to the accumulation of more cytotoxic, but terminally differentiated, CD8+ TEX cells. These results demonstrate that CD8+ T cell exhaustion can occur in the absence of PD-1. They also highlight a novel role for PD-1 in preserving TEX cell populations from overstimulation, excessive proliferation, and terminal differentiation.

Molecular Basis of T-Cell Exhaustion

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. SCI-38-SCI-38
Author(s):  
E. John Wherry
Keyword(s):  
T Cells ◽  
Transcription Factors ◽  
T Cell ◽  
Terminal Differentiation ◽  
Cell Populations ◽  
T Cell Exhaustion ◽  
Inhibitory Receptors ◽  
Chronic Infections ◽  
Cell Exhaustion

Abstract T-cell exhaustion is common during chronic infections, cancer, exposure to persisting antigens, and can prevent optimal immunity. Exhausted T cells are defined by the loss of ability to perform effector functions efficiently, low proliferative capacity, and poor survival following antigen stimulation. In addition, it has become clear that exhausted T cells co-express multiple inhibitory receptors that negatively regulate their function. Indeed, receptors such as PD-1 have become major targets of clinical immunotherapies in cancer and infectious disease aimed at re-invigorating exhausted T cells. Our work has recently defined transcriptional networks of T-cell exhaustion and has focused on the role of key transcription factors, including T-bet and Eomesodermin (Eomes), in controlling the sustainability and terminal differentiation of exhausted T cell populations. Chronic infections and persisting antigen exposure often strains the sustainability or regenerative capacity of exhausted T cell populations resulting in an eventual collapse in immunity. We have found a key role for T-bet in sustaining a progenitor pool of exhausted CD8 T cells during chronic infection, while the related transcription factor Eomes governs terminal differentiation. These represent unique functions for T-bet and Eomes since these transcription factors are associated with different roles in functional memory T cells, highlighting the contextual dependence of transcriptional regulation guiding T-cell exhaustion. Additional studies are focusing on the role of other transcription factors such as BATF in T-cell activation and exhaustion, and on the role of inhibitory receptors including PD-1 in shaping the differentiation of exhausted CD8 T-cell subsets. Ultimately, a more precise molecular understanding of T-cell exhaustion should lead to novel and more robust clinical interventions to reverse exhaustion in settings of persisting infections and cancer. Disclosures: Wherry: Genentech: Patents & Royalties.

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