PD-1 coinhibitory signals: the link between pathogenesis and protection

DA Kulpa, M Lawani, A Cooper, Y Peretz, J Ahlers… - Seminars in …, 2013 - Elsevier
DA Kulpa, M Lawani, A Cooper, Y Peretz, J Ahlers, RP Sékaly
Seminars in immunology, 2013Elsevier
In the majority of HIV-1 infected individuals, the adaptive immune response drives virus
escape resulting in persistent viremia and a lack of immune-mediated control. The
expression of negative regulatory molecules such as PD-1 during chronic HIV infection
provides a useful marker to differentiate functional memory T cell subsets and the frequency
of T cells with an exhausted phenotype. In addition, cell-based measurements of virus
persistence equate with activation markers and the frequency of CD4 T cells expressing PD …
Abstract
In the majority of HIV-1 infected individuals, the adaptive immune response drives virus escape resulting in persistent viremia and a lack of immune-mediated control. The expression of negative regulatory molecules such as PD-1 during chronic HIV infection provides a useful marker to differentiate functional memory T cell subsets and the frequency of T cells with an exhausted phenotype. In addition, cell-based measurements of virus persistence equate with activation markers and the frequency of CD4 T cells expressing PD-1. High-level expression of PD-1 and its ligands PD-L1 and PD-L2 are found on hematopoietic and non-hematopoietic cells, and are upregulated by chronic antigen stimulation, Type 1 and Type II interferons (IFNs), and homeostatic cytokines. In HIV infected subjects, PD-1 levels on CD4 and CD8 T cells continue to remain high following combination anti-retroviral therapy (cART). System biology approaches have begun to elucidate signal transduction pathways regulated by PD-1 expression in CD4 and CD8 T cell subsets that become dysfunctional through chronic TCR activation and PD-1 signaling. In this review, we summarize our current understanding of transcriptional signatures and signal transduction pathways associated with immune exhaustion with a focus on recent work in our laboratory characterizing the role of PD-1 in T cell dysfunction and HIV pathogenesis. We also highlight the therapeutic potential of blocking PD-1–PD-L1 and other immune checkpoints for activating potent cellular immune responses against chronic viral infections and cancer.
Elsevier