• lab members in Star Wars costumes
  • 2019 Group Picture

What We Do

The Sharpe laboratory investigates T cell costimulatory pathways and their immunoregulatory functions. We focus on the roles of these pathways in regulating pathogenic and protective immune responses needed for the induction and maintenance of T cell tolerance and the prevention of autoimmunity, as well as effective antimicrobial and antitumor immunity.

We are also involved in studies aimed at translating the fundamental understanding of T cell costimulation into new therapies for autoimmune diseases, chronic viral infections, and cancer. Manipulation of T cell costimulatory pathways is of great therapeutic interest as it may provide a means to enhance immune responses to promote anti-microbial and tumor immunity, or to terminate immune responses to control autoimmune diseases and achieve tolerance for organ transplantation.

Recent Publications

The PD-1 Pathway Regulates Development and Function of Memory CD8+ T Cells following Respiratory Viral Infection

Pauken KE, Godec J, Odorizzi PM, Brown KE, Yates KB, Ngiow SF, Burke KP, Freeman GJ, Haining WN, Wherry EJ, et al. The PD-1 Pathway Regulates Development and Function of Memory CD8+ T Cells following Respiratory Viral Infection. Cell Reports. 2020;31 (13) :107827.Abstract

The PD-1 pathway regulates dysfunctional T cells in chronic infection and cancer, but the role of this pathway during acute infection remains less clear. Here, we demonstrate that PD-1 signals are needed for optimal memory. Mice deficient in the PD-1 pathway exhibit impaired CD8+ T cell memory following acute influenza infection, including reduced virus-specific CD8+ T cell numbers and compromised recall responses. PD-1 blockade during priming leads to similar differences early post-infection but without the defect in memory formation, suggesting that timing and/or duration of PD-1 blockade could be tailored to modulate host responses. Our studies reveal a role for PD-1 as an integrator of CD8+ T cell signals that promotes CD8+ T cell memory formation and suggest PD-1 continues to fine-tune CD8+ T cells after they migrate into nonlymphoid tissues. These findings have important implications for PD-1-based immunotherapy, in which PD-1 inhibition may influence memory responses in patients.

PubMed DOI

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Fibroblastic reticular cells enhance T cell metabolism and survival via epigenetic remodeling

Brown FD, Sen DR, LaFleur MW, Godec J, Lukacs-Kornek V, Danial NN, Manning BD, Sharpe AH, Haining WN, Turley SJ. Fibroblastic reticular cells enhance T cell metabolism and survival via epigenetic remodeling. Nature Immunology. 2019;20 (12) :1668-1680.Abstract

Lymph node fibroblastic reticular cells (FRCs) respond to signals from activated T cells by releasing nitric oxide, which inhibits T cell proliferation and restricts the size of the expanding T cell pool. Whether interactions with FRCs also support the function or differentiation of activated CD8+ T cells is not known. Here we report that encounters with FRCs enhanced cytokine production and remodeled chromatin accessibility in newly activated CD8+ T cells via interleukin-6. These epigenetic changes facilitated metabolic reprogramming and amplified the activity of pro-survival pathways through differential transcription factor activity. Accordingly, FRC conditioning significantly enhanced the persistence of virus-specific CD8+ T cells in vivo and augmented their differentiation into tissue-resident memory T cells. Our study demonstrates that FRCs play a role beyond restricting T cell expansion—they can also shape the fate and function of CD8+ T cells.

PubMed DOI

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T Cell Activation Depends on Extracellular Alanine

Ron-Harel N, Ghergurovich JM, Notarangelo G, LaFleur MW, Tsubosaka Y, Sharpe AH, Rabinowitz JD, Haigis MC. T Cell Activation Depends on Extracellular Alanine. Cell Reports. 2019;28 (12) :3011-3021.Abstract

T cell stimulation is metabolically demanding. To exit quiescence, T cells rely on environmental nutrients, including glucose and the amino acids glutamine, leucine, serine, and arginine. The expression of transporters for these nutrients is tightly regulated and required for T cell activation. In contrast to these amino acids, which are essential or require multi-step biosynthesis, alanine can be made from pyruvate by a single transamination. Here, we show that extracellular alanine is nevertheless required for efficient exit from quiescence during naive T cell activation and memory T cell restimulation. Alanine deprivation leads to metabolic and functional impairments. Mechanistically, this vulnerability reflects the low expression of alanine aminotransferase, the enzyme required for interconverting pyruvate and alanine, whereas activated T cells instead induce alanine transporters. Stable isotope tracing reveals that alanine is not catabolized but instead supports protein synthesis. Thus, T cells depend on exogenous alanine for protein synthesis and normal activation.

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Immuno-PET identifies the myeloid compartment as a key contributor to the outcome of the antitumor response under PD-1 blockade

Rashidian M, LaFleur MW, Verschoor VL, Dongre A, Zhang Y, Nguyen TH, Kolifrath S, Aref AR, Lau CJ, Paweletz CP, et al. Immuno-PET identifies the myeloid compartment as a key contributor to the outcome of the antitumor response under PD-1 blockade. PNAS. 2019;116 (34) :16971-16980.Abstract

Immunotherapy, especially blockade of the PD-1/PD-L1 and CTLA-4 axes, has resulted in durable responses in a range of cancers. However, responses remain heterogeneous among patients. Treatment outcome results from changes in the tumor microenvironment imposed by such blockade. Here, we use immuno-PET and single-cell RNA sequencing to increase our understanding of the dynamics of immune cells and their functional status in the tumor microenvironment in response to PD-1 blockade. Our data provide insights into the dynamics of CD8+ T cells and the functional status of the myeloid compartment in response to PD-1 blockade.

PubMed DOI

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