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

Area of Science:

• Immunology
• Virology
• Molecular Biology

Background:

• Adaptive immune responses in HIV-1 infection often fail to control the virus, leading to persistent viremia.
• Programmed cell death protein 1 (PD-1) expression serves as a marker for T cell exhaustion and functional memory T cell subsets in chronic HIV.
• PD-1 and its ligands (PD-L1, PD-L2) are upregulated by chronic antigen stimulation, interferons, and cytokines, and remain elevated even after combination anti-retroviral therapy (cART).

Purpose of the Study:

• To review the current understanding of transcriptional signatures and signaling pathways in immune exhaustion.
• To highlight the role of PD-1 in T cell dysfunction and HIV pathogenesis.
• To explore the therapeutic potential of targeting PD-1 and other immune checkpoints.

Main Methods:

• Review of existing literature on PD-1 expression and signaling in HIV infection.
• Analysis of transcriptional signatures and signal transduction pathways associated with T cell exhaustion.
• Focus on laboratory's recent work characterizing PD-1's role in T cell dysfunction and HIV pathogenesis.

Main Results:

• PD-1 expression is a significant marker for T cell exhaustion in HIV infection.
• Chronic antigen stimulation and inflammatory signals upregulate PD-1 expression.
• PD-1 levels remain high in T cells even after cART treatment, indicating persistent immune dysfunction.

Conclusions:

• PD-1 signaling contributes to T cell dysfunction in chronic HIV infection.
• Targeting the PD-1/PD-L1 pathway offers therapeutic potential for enhancing anti-viral and anti-cancer immune responses.
• Understanding PD-1's role is crucial for developing effective immunotherapies for chronic viral infections.