PD-1 modulating Mycobacterium tuberculosis-specific polarized effector memory T cells response in tuberculosis...

Area of Science:

• Immunology
• Tuberculosis Research
• Cellular Biology

Background:

• Tuberculosis (TB) pathogenesis involves complex host-pathogen interactions at disease sites.
• T-cell responses are critical for controlling Mycobacterium tuberculosis (M.tb) infection.
• The role of programmed cell death protein 1 (PD-1) in T-cell immunity during tuberculosis pleurisy (TBP) is not well understood.

Purpose of the Study:

• To investigate the phenotype and function of PD-1-expressing T cells in the pleural fluid of TBP patients.
• To elucidate the regulatory role of the PD-1/PD-L1 pathway in T-cell responses during TBP.
• To explore the potential of IL-12 in modulating PD-1 expression and T-cell function.

Main Methods:

• Analysis of pleural fluid mononuclear cells (PFMCs) from TBP patients and peripheral blood mononuclear cells (PBMCs) from healthy donors.
• Characterization of PD-1-expressing CD4+ and CD8+ T cells, including their phenotypes and cytokine production (e.g., IFN-γ).
• Assessment of the impact of PD-1/PD-L1 pathway blockade and IL-12 stimulation on T-cell function.

Main Results:

• PFMCs from TBP patients showed increased numbers of PD-1-expressing CD4+ and CD8+ T cells with effector memory phenotypes.
• M.tb-specific antigen stimulation correlated with increased PD-1+ T cells, IFN-γ production, and PD-L1+ antigen-presenting cells.
• PD-1/PD-L1 pathway blockade enhanced IFN-γ+ T cells, indicating a negative regulatory role. PD-1+ T cells exhibited enhanced effector functions, suggesting they are not exhausted.
• IL-12 enhanced PD-1 expression and restored IFN-γ responses by inducing STAT4 phosphorylation in specific T-cell subsets.

Conclusions:

• PD-1+ T cells in TBP are crucial for maintaining antigen-specific effector functions rather than being exhausted.
• The PD-1/PD-L1 pathway negatively regulates T-cell effector functions in TBP.
• IL-12 can modulate PD-1 expression and enhance anti-mycobacterial T-cell responses, offering potential for immune intervention in TBP.