Twin study dissects CXCR3+ memory B cells as non-heritable feature in multiple sclerosis.

BACKGROUND: In multiple sclerosis (MS), B cells are considered main triggers of the disease, likely as the result of complex interaction between genetic and environmental risk factors. Studies on monozygotic twins discordant for MS offer a unique way to reduce this complexity and reveal discrepant subsets. METHODS: In this study, we analyzed B cell subsets in blood samples of monozygotic twins with and without MS using publicly available data. We verified functional characteristics by exploring the role of therapy and performed separate analyses in unrelated individuals. FINDINGS: The frequencies of CXCR3+ memory B cells were reduced in the blood of genetically identical twins with MS compared to their unaffected twin siblings. Natalizumab (anti-VLA-4 antibody) was the only treatment regimen under which these frequencies were reversed. The CNS-homing features of CXCR3+ memory B cells were supported by elevated CXCL10 levels in MS cerebrospinal fluid and their in vitro propensity to develop into antibody-secreting cells. CONCLUSIONS: Circulating CXCR3+ memory B cells are affected by non-heritable cues in people who develop MS. This underlines the requirement of environmental risk factors such as Epstein-Barr virus in triggering these B cells. We propose that after CXCL10-mediated entry into the CNS, CXCR3+ memory B cells mature into antibody-secreting cells to drive MS. FUNDING: This work was supported by Nationaal MS Fonds (OZ2021-016), Stichting MS Research (19-1057 MS, 20-490f MS, and 21-1142 MS), the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program grant agreement no. 882424, and the Swiss National Science Foundation (733 310030_170320, 310030_188450, and CRSII5_183478).

Single-cell profiling of myasthenia gravis identifies a pathogenic T cell signature.

Myasthenia gravis (MG) is an autoimmune disease characterized by impaired neuromuscular signaling due to autoantibodies targeting the acetylcholine receptor. Although its auto-antigens and effector mechanisms are well defined, the cellular and molecular drivers underpinning MG remain elusive. Here, we employed high-dimensional single-cell mass and spectral cytometry of blood and thymus samples from MG patients in combination with supervised and unsupervised machine-learning tools to gain insight into the immune dysregulation underlying MG. By creating a comprehensive immune map, we identified two dysregulated subsets of inflammatory circulating memory T helper (Th) cells. These signature ThCD103 and ThGM cells populated the diseased thymus, were reduced in the blood of MG patients, and were inversely correlated with disease severity. Both signature Th subsets rebounded in the blood of MG patients after surgical thymus removal, indicative of their role as cellular markers of disease activity. Together, this in-depth analysis of the immune landscape of MG provides valuable insight into disease pathogenesis, suggests novel biomarkers and identifies new potential therapeutic targets for treatment.