Impaired remyelination in late-onset multiple sclerosis.

Area of Science:

• Neuroscience
• Pathology
• Immunology

Background:

• Reduced regenerative capacity may accelerate disease progression in late-onset multiple sclerosis (LOMS).
• LOMS patients (onset >50 years) may experience poorer relapse recovery compared to normal-onset MS (NOMS) patients.
• Histopathological differences in LOMS lesions, including axonal damage and remyelination, were investigated.

Purpose of the Study:

• To compare histopathological features of early-stage LOMS and NOMS.
• To assess inflammatory infiltrate, axonal damage, and oligodendrocyte populations in MS lesions.
• To investigate the relationship between oligodendrocyte differentiation, remyelination, and clinical outcomes in LOMS.

Main Methods:

• Detailed histopathological analysis of MS biopsies from 31 LOMS and 30 NOMS patients.
• Assessment of T cells, B cells, plasma cells, microglia/macrophages, and oligodendrocyte populations.
• Evaluation of axonal density, acute axonal damage, and correlation with clinical scores (EDSS).

Main Results:

• No significant differences in inflammatory infiltrate or axonal damage between LOMS and NOMS.
• Significantly lower numbers of early myelinating (BCAS1-positive) and mature oligodendrocytes in LOMS normal-appearing white matter.
• Impaired remyelination in LOMS lesions, with reduced BCAS1-positive cells and correlation with lesion age and higher EDSS scores.

Conclusions:

• LOMS is characterized by impaired oligodendrocyte differentiation and reduced remyelination capacity.
• Reduced remyelination in LOMS contributes to poorer clinical outcomes, evidenced by higher EDSS scores.
• Therapeutic strategies for LOMS should focus on fostering oligodendrocyte precursor cell differentiation into myelinating oligodendrocytes.