Key result
Nonresponders to dimethyl fumarate had a 2.9-fold higher proportion of a specific CXCR3+ memory T helper cell population at 12 months compared to responders, predicting disease activity with an AUC of 0.85.
Why the study?
Despite the wide clinical use of dimethyl fumarate in multiple sclerosis, the mechanisms underlying clinical response are not understood.
Cohort (n=44)
No
Depletion of GM-CSF-, IFNγ-, and CXCR3-expressing T helper cells is a key mechanism of action of dimethyl fumarate and serves as a biomarker for treatment response in multiple sclerosis.
Answers are grounded in this paper and cite their sources.
May flag DMF nonresponders in MS via CXCR3+ monitoring; hypothesis-generating for biomarker-guided decisions pending validation.
Dimethyl fumarate (DMF) is an immunomodulatory treatment for multiple sclerosis (MS). Despite its wide clinical use, the mechanisms underlying clinical response are not understood. This study aimed to reveal immune markers of therapeutic response to DMF treatment in MS. For this purpose, we prospectively collected peripheral blood mononuclear cells (PBMCs) from a highly characterized cohort of 44 individuals with MS before and at 12 and 48 wk of DMF treatment. Single cells were profiled using high-dimensional mass cytometry. To capture the heterogeneity of different immune subsets, we adopted a bioinformatic multipanel approach that allowed cell population-cluster assignment of more than 50 different parameters, including lineage and activation markers as well as chemokine receptors and cytokines. Data were further analyzed in a semiunbiased fashion implementing a supervised representation learning approach to capture subtle longitudinal immune changes characteristic for therapy response. With this approach, we identified a population of memory T helper cells expressing high levels of neuroinflammatory cytokines (granulocyte-macrophage colony-stimulating factor [GM-CSF], interferon γ [IFNγ]) as well as CXCR3, whose abundance correlated with treatment response. Using spectral flow cytometry, we confirmed these findings in a second cohort of patients. Serum neurofilament light-chain levels confirmed the correlation of this immune cell signature with axonal damage. The identified cell population is expanded in peripheral blood under natalizumab treatment, substantiating a specific role in treatment response. We propose that depletion of GM-CSF-, IFNγ-, and CXCR3-expressing T helper cells is the main mechanism of action of DMF and allows monitoring of treatment response.
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Diebold et al. (2022) conducted a cohort in Relapsing-remitting multiple sclerosis (n=44). Dimethyl fumarate vs. Responders was evaluated on Proportion of CXCR3+ effector-memory T cells at 12 months (2.9-fold higher, p=0.0004). Nonresponders to dimethyl fumarate had a 2.9-fold higher proportion of a specific CXCR3+ memory T helper cell population at 12 months compared to responders, predicting disease activity with an AUC of 0.85.
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