The Role of the FCRL5 Protein in the Pathophysiology of Multiple Sclerosis and Response to Treatment

The Role of the FCRL5 Protein in the Pathophysiology of Multiple Sclerosis and Response to Treatment

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease of the central nervous system (CNS) and the leading non-traumatic cause of neurological disability in young adults. Historically considered a T-cell-mediated disease, the paradigm for MS has shifted thanks to the efficacy of therapies targeting B cells. The investigators recently identified FCRL5 as a B-cell-specific biomarker that is significantly elevated in the cerebrospinal fluid (CSF) of patients with relapsing-remitting MS and is independently associated with an increased risk of developing new MRI lesions within two years of diagnosis (ref. Deltombe et al., PMID: 41004694). This project aims to further explore FCRL5 as a prognostic biomarker, study the role of FCRL5-expressing B cells in MS pathogenesis and the effects of disease-modifying therapies on these subsets.

Inclusion Criteria:

• For MS patients:
• Male or female
• Between 18 and 80 years of age
• Diagnosed with MS according to the most recent McDonald criteria (2025)
• Patients who are about to start a new MS treatment or switch treatments

For healthy volunteers:

• Men or women
• Ages 18 to 80
• Healthy volunteers with no neurological conditions or autoimmune diseases

For participants with Sjögren's syndrome:

• Men or women
• Ages 18 to 80

Exclusion Criteria:

• For MS patients:
• No recent relapse (during the 3 months prior to study enrollment)
• Patients treated with corticosteroids (during the 3 months prior to study enrollment)
• Patients receiving another immunosuppressive therapy unrelated to MS
• Inability to sign the informed consent form

For healthy volunteers:

Subjects not receiving immunosuppressive therapy

For subjects with Sjögren's syndrome:

Subjects not receiving immunosuppressive therapy