Chronic thoracic spinal cord injury impairs CD8+ T-cell function by up-regulating programmed cell death-1 expression

Area of Science:

• Immunology
• Neuroscience
• Cell Biology

Background:

• Chronic spinal cord injury (SCI) is linked to immune depression and increased infection risk.
• Humoral immunity defects are known, but T-cell immunity in chronic SCI remains unexplored.

Purpose of the Study:

• To investigate the impact of chronic SCI on peripheral T-cell number and function.
• To explore the role of sympathetic activity and neurogenic mechanisms in SCI-induced T-cell dysfunction.

Main Methods:

• Mouse model of thoracic spinal cord contusion (T9).
• Flow cytometry for T-cell markers and intracellular cytokine staining.
• Measurement of splenic tyrosine hydroxylase (TH) and norepinephrine (NE) levels.
• In vitro NE stimulation of T-cells to assess exhaustion markers.

Main Results:

• Chronic SCI impaired CD4+ and CD8+ T-cell cytokine production.
• Increased expression of the exhaustion marker PD-1 on T-cells correlated with dysfunction.
• Elevated splenic NE levels in chronic SCI mice contributed to T-cell exhaustion.
• In vitro NE exposure upregulated PD-1 expression on T-cells.

Conclusions:

• Altered sympathetic activity in chronic SCI induces T-cell exhaustion, impairing T-cell function and contributing to immune depression.
• Inhibition of the T-cell exhaustion pathway presents a potential therapeutic strategy for SCI-induced immune depression.