Protective and detrimental roles for regulatory T cells in a viral model for multiple sclerosis

Area of Science:

• Neuroimmunology
• Virology

Background:

• Multiple sclerosis (MS) is an immune-mediated central nervous system (CNS) disease potentially triggered by viral infections.
• Theiler's murine encephalomyelitis virus (TMEV) infection in mice serves as a model for MS, exhibiting acute polioencephalomyelitis and chronic immune-mediated demyelination.
• Regulatory T cells (Tregs) are known to suppress inflammation but may also impair antiviral responses, complicating their role in viral-induced demyelination.

Purpose of the Study:

• To investigate the role and translational potential of induced Tregs (iTregs) in a viral model of MS.
• To evaluate the effects of early versus therapeutic iTreg administration on disease progression and CNS pathology.

Main Methods:

• TMEV-infected mice were treated with ex vivo generated iTregs at different time points: early (day 0) or during the chronic stage.
• Clinical signs, viral titers, immune cell infiltration in the CNS, and cytokine production were assessed.

Main Results:

• Early iTreg treatment exacerbated acute disease, correlating with increased viral titers and reduced CNS immune cell recruitment.
• Therapeutic iTreg treatment during the chronic stage significantly reduced inflammatory demyelination.
• iTreg treatment enhanced interleukin-10 production from B cells, CD4(+) T cells, and dendritic cells, potentially mediating reduced CNS inflammation.

Conclusions:

• The timing of Treg-based interventions is critical in viral-induced demyelinating diseases.
• Therapeutic application of iTregs shows promise for reducing chronic inflammation and demyelination in MS models.
• Tregs modulate immune responses in the CNS, influencing both viral control and inflammatory pathology.