Refined single-cell profiling captures a CCR5^high CD4⁺ cytotoxic T-cell precursor in multiple sclerosis

Area of Science:

• Immunology
• Neuroscience
• Cell Biology

Background:

• CD4+ T cells are implicated in multiple sclerosis (MS) central nervous system (CNS) pathology.
• A specific CD4+ T cell subset, T helper 17.1 (Th17.1), is hypothesized to play a key role in MS onset.
• Limited understanding exists regarding Th17.1 functional heterogeneity and mechanisms in MS.

Purpose of the Study:

• To investigate the functional heterogeneity and brain-homing properties of Th17.1 cells in MS.
• To identify distinct Th17.1 cell signatures associated with MS pathology.
• To explore potential therapeutic targets for MS based on Th17.1 cell characteristics.

Main Methods:

• Spectral flow cytometry was used to distinguish Th17.1 cells from Th17 and Th1 cells.
• Paired blood and cerebrospinal fluid (CSF) samples, along with pre- and post-natalizumab treatment blood, were analyzed to assess brain-homing properties.
• Single-cell transcriptomics and in vitro stimulation assays were performed on purified Th17.1 subsets to analyze effector signatures.

Main Results:

• A CCR5high Th17.1 cluster was identified, enriched in CSF and reduced in blood after natalizumab treatment in MS patients.
• This Th17.1 cluster exhibited a phenotype and transcriptional signature indicative of a receptive and pre-cytotoxic state.
• CCR5high Th17.1 cells upregulated cytolytic proteins in response to IL-12 and IL-18 stimulation in vitro.

Conclusions:

• Low-frequency circulating Th17.1 cells possess a unique MS-associated CCR5high cluster with increased cytotoxic and CNS-infiltrating potential.
• This CD4+ cytotoxic T-cell precursor represents a potential target for monitoring immune perturbations in MS.
• These findings may inform the development of precision medicine strategies for multiple sclerosis.