Abnormal effector and regulatory T cell subsets in paediatric-onset multiple sclerosis.

Area of Science:

• Immunology
• Neuroimmunology
• Pediatric Neurology

Background:

• Multiple sclerosis (MS) pathogenesis involves complex T-cell immune responses.
• Understanding T-cell subsets, including effector (Teff) and regulatory (Treg) cells, is crucial for targeted therapies.
• Paediatric-onset MS offers insights into early disease mechanisms, distinct from adult-onset MS.

Purpose of the Study:

• To comprehensively assess both phenotype and function of Teff and Treg cells simultaneously in children with MS.
• To evaluate the balance between Teff and Treg cells in early paediatric MS.
• To identify distinct T-cell abnormalities contributing to paediatric MS development.

Main Methods:

• Integrated analysis of T-cell phenotype and function using multi-parametric flow cytometry and functional assays.
• Simultaneous assessment of effector (Teff) and regulatory (Treg) T cells in the same pediatric patients.
• Utilized cryopreserved peripheral blood cells from children with MS, controls, and inflammatory CNS disorders.

Main Results:

• Increased frequencies and pro-inflammatory responses of MAIT and CD4+CCR2+CCR5+ Teffs observed in paediatric MS.
• Reduced suppressive capacity of CD4+CD25hiCD127lowFOXP3+ Tregs in children with MS.
• Implicated Teffs showed resistance to normal Treg suppression, and an abnormal Teff/Treg ratio distinguished MS patients.

Conclusions:

• Paediatric MS involves distinct abnormalities in both pro-inflammatory CD4/CD8 T-cell subsets and Treg function.
• Early MS development may stem from individual-specific mechanisms involving Teff excess, Treg deficiency, or a combination.
• These findings highlight the importance of assessing Teff/Treg balance in paediatric MS for understanding disease heterogeneity.