Pro-Inflammatory Molecules Implicated in Multiple Sclerosis Divert the Development of Human Oligodendrocyte Lineage...

Area of Science:

• Neuroscience
• Immunology
• Stem Cell Biology

Background:

• Multiple sclerosis (MS) involves the loss of oligodendrocytes and myelin, crucial for nerve function.
• Myelin repair relies on oligodendrocyte progenitor cells (OPCs), but repair often fails in MS.
• The impact of inflammatory molecules like TNFα and IFNγ on human OPC differentiation in MS is not fully understood.

Purpose of the Study:

• To investigate the effect of tumor necrosis factor-alpha (TNFα) and interferon-gamma (IFNγ) on human OPC differentiation.
• To explore the molecular mechanisms underlying impaired remyelination in MS.

Main Methods:

• Generated human OPCs from induced pluripotent stem cells with an SOX10 reporter.
• Treated OPCs in vitro with TNFα or IFNγ, assessing cell viability and lineage marker expression.
• Analyzed human MS brain single-nuclear RNA sequencing datasets to compare with in vitro findings.

Main Results:

• Both TNFα and IFNγ reduced the differentiation of OPCs into the oligodendrocyte lineage.
• TNFα induced aberrant differentiation, with some OPCs coexpressing astrocytic markers (aquaporin-4).
• Transcriptomic analysis revealed an astrocyte-like and reactive phenotype in affected OPCs, with downregulated OL genes.
• MS brain data showed a subset of OPCs with an astrocyte-like signature.

Conclusions:

• In MS, OPCs are present but their differentiation into myelin-producing oligodendrocytes is inhibited by inflammation.
• A subset of OPCs develop a reactive, stem cell-like phenotype, compromising their repair capacity.
• These findings identify a cellular basis for failed myelin repair in MS and suggest potential therapeutic targets.