Summary: A comprehensive analysis of immune cells from human blood, cerebrospinal fluid (CSF), and intestinal mucosal tissue in control individuals and multiple sclerosis (MS) patients treated with B-cell depletion reveals a previously unrecognized mechanism. Rather than working solely by removing disease-driving B cells, anti-B-cell therapy appears to alter systemic regulatory signals and actively mobilize protective, gut-derived regulatory B cells into the circulation and central nervous system, where they can help reduce neuroinflammation.
Key Facts
- Gut-to-CNS migration: B-cell depletion shifts levels of systemic regulatory factors, encouraging the movement of protective B cells from intestinal mucosa into the bloodstream and the central nervous system.
- Dual mechanism of action: Anti-B-cell immunotherapies do not simply deplete harmful, autoreactive B cells; they also support recruitment of beneficial B-cell subsets that regulate inflammation.
- Biomarker association: Increased concentrations of B-cell–regulating factors after depletion therapy correlate with improved clinical outcomes and reduced disease progression in MS patients.
- Cross-tissue human profiling: Researchers validated these migratory pathways through parallel cellular analyses of blood, CSF, and gut mucosal biopsies in human participants.
- Therapeutic potential: Revealing this gut–brain immune circuit suggests new strategies to directly harness or enhance gut-derived regulatory lymphocytes to suppress central nervous system inflammation in MS and other autoimmune diseases.
Source: University of Bonn
B-cell depletion therapies — treatments that transiently remove B cells, which can contribute to disease activity in multiple sclerosis — have substantially improved outcomes for many patients. New work from an international research team provides insight into how these therapies produce their beneficial effects.
Investigators from the University Hospital Bonn, the Universities of Bonn, Basel, Toronto, and Yale, together with other collaborators, studied how B-cell depletion affects protective B-cell populations that naturally reside in the gut mucosa. Their results indicate that part of the therapy’s benefit derives from mobilizing these regulatory immune cells and redirecting them to systemic and central compartments.
These findings are published in the peer-reviewed journal Science Translational Medicine.
Multiple sclerosis is a chronic inflammatory disease of the central nervous system in which immune cells, including certain B cells, contribute to damage of the myelin sheath that insulates nerve fibers. While some B-cell subsets promote disease, others have anti-inflammatory roles and help regulate immune responses. Distinguishing between harmful and beneficial B cells is critical for designing safer, more effective treatments.
Led by Prof. Anne-Katrin Pröbstel and colleagues, the study investigated how anti-CD20 B-cell depletion affects regulatory B-cell populations. First authors Dr. Tradite Neziraj and Dr. Elisabeth Pössnecker collected and analyzed immune cells from blood, CSF, and intestinal mucosal tissue of control subjects and MS patients undergoing B-cell depletion. Using single-cell transcriptomics, flow cytometry, and immune receptor repertoire analysis, they tracked cell types and their likely tissue origins.
Therapy promotes migration of gut-derived regulatory B cells
The researchers found that anti-CD20 treatment is associated with increased frequencies of mucosal-origin IgA-producing regulatory B cells in the periphery and CSF. Evidence of greater clonal overlap between gut mucosal and systemic B-cell receptors suggested enhanced trafficking of these IgA B cells from the intestinal mucosa to the blood and central nervous system. Concurrent changes in circulating B-cell–activating factor and proliferation-inducing ligand were linked to better clinical outcomes in treated patients.
In short, B-cell depletion appears to reprogram systemic signals that both reduce harmful B cells and mobilize protective, gut-derived regulatory B cells. This dual action helps explain the strong clinical efficacy of anti-CD20 therapies in MS and points to new therapeutic avenues that deliberately leverage mucosal immune regulation.
Collaborations and funding
The study involved collaboration with teams at Université de Lausanne and UMC Amsterdam. Funding sources included the Swiss Multiple Sclerosis Society, Propatient Stiftung of the University Hospital of Basel, Fondation Pierre Mercier pour la Science, the National Multiple Sclerosis Society, the Swiss National Science Foundation, the State Secretariat for Education, Research and Innovation (SERI) under an EU Horizon 2020 grant, and the German Research Foundation (DFG) as part of Germany’s Excellence Strategy. Additional individual awards supported early-career investigators involved in the project.
Key questions answered
A: In MS, autoreactive B cells can mistakenly target the myelin sheath, driving demyelination and neuroinflammation. Simultaneously, non-pathogenic B-cell subsets produce anti-inflammatory cytokines that help restrain autoimmune activity.
A: Anti-CD20 therapy alters levels of circulating regulatory signals and cytokines. This biochemical environment can prompt protective regulatory B cells in the gut mucosa to enter the circulation and migrate into the central nervous system, where they contribute to immune balance.
A: Recognizing the gut as a reservoir of protective immune cells suggests new strategies to enhance or recruit intestinal regulatory B cells. Targeting this gut–brain immune circuit could improve efficacy while reducing broad immunosuppression.
Editorial Notes
- This article was edited by a Neuroscience News editor.
- The original journal paper was reviewed in full for accuracy.
- Additional explanatory context was provided by the editorial staff.
About this multiple sclerosis research news
Author: Inka Väth
Source: Universitätsklinikum Bonn
Contact: Inka Väth – Universitätsklinikum Bonn
Image credit: Neuroscience News
Original research: Open access. “Anti-CD20 B cell depletion is associated with elevated mucosal-originating circulating regulatory IgA B cells in multiple sclerosis” by Tradite Neziraj et al., Science Translational Medicine. DOI: 10.1126/scitranslmed.aee1580
Abstract
Anti-CD20 B cell depletion is associated with elevated mucosal-originating circulating regulatory IgA B cells in multiple sclerosis
Anti-CD20 monoclonal antibody therapy is highly effective across several autoimmune diseases, including multiple sclerosis. Yet which B-cell subsets and altered regulatory factors drive this clinical benefit has been unclear. To address this, the authors performed longitudinal, high-dimensional single-cell transcriptomic and proteomic profiling of blood, CSF, and intestinal samples from people with MS, complemented by immune profiling in a preclinical autoimmune encephalomyelitis model and analysis of published CSF datasets.
Multisite intestinal profiling in a treated patient and a control volunteer, together with algorithm-guided integration of flow cytometry, single-cell transcriptomic data, and immune receptor repertoires, revealed that anti-CD20 therapy is associated with increased peripheral and CSF frequencies of regulatory IgA-producing B cells of mucosal origin. Enhanced clonal overlap between mucosal and systemic compartments indicated greater trafficking of IgA B cells from gut mucosal tissue to the circulation and CNS. Higher concentrations of B-cell–activating factor and related ligands were associated with favorable clinical outcomes during treatment. These results suggest that anti-CD20 therapy engages mucosal immune regulatory mechanisms and point to new therapeutic opportunities for harnessing gut-derived regulation in MS.