MS CD49d⁺CD154⁺ Lymphocytes Reprogram Oligodendrocytes into Immune Reactive Cells Affecting CNS Regeneration

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• Multiple sclerosis (MS) progression is linked to insufficient central nervous system (CNS) regeneration due to poor myelin synthesis by oligodendrocytes (OLs).
• While T-cell mediated inflammation is studied, the challenge of inadequate remyelination and disease progression persists.

Purpose of the Study:

• To investigate the impact of myelin-specific lymphocytes on oligodendrocyte (OL) function in MS patients and a mouse model of MS.
• To identify molecular mechanisms underlying lymphocyte-induced OL dysfunction and explore therapeutic targets.

Main Methods:

• Co-culture of myelin-specific CD49d+CD154+ lymphocytes from MS patients and Experimental Autoimmune Encephalomyelitis (EAE) mouse T and B cells with oligodendrocyte precursor cells (OPCs).
• Analysis of OPC maturation, myelin protein (MBP, PLP) synthesis, and inflammatory mediator production.
• Investigation of microRNA (miRNA) synthesis and polymerase II activity in OLs.

Main Results:

• Myelin-specific CD49d+CD154+ lymphocytes induced immune-reactive OLs with imbalanced MBP/PLP production and pro-inflammatory cytokine synthesis.
• Lymphocytes dysregulated miRNA synthesis in OLs, primarily targeting miR-665 and ELL3.
• Neutralizing elevated intracellular miR-665 restored normal miRNA and MBP/PLP synthesis.

Conclusions:

• MS-associated myelin-specific lymphocytes impair oligodendrocyte maturation and myelin synthesis.
• Dysregulation of miR-665 by lymphocytes is a key mechanism driving impaired remyelination.
• Targeting miR-665 presents a potential therapeutic strategy to promote CNS remyelination in MS.