Investigating the role of CNS-expanded innate-like b-cells in a mouse model of progressive multiple sclerosis

The National Institute of Neurological Disorders and Stroke awarded The Ohio State University $135,066 on September 1, 2026, under the Extramural Research Programs in the Neurosciences and Neurological Disorders program (CFDA 93.853) to investigate the role of central nervous system–expanded innate-like B-cells in a mouse model of progressive multiple sclerosis.

The research employs an age-dependent experimental autoimmune encephalomyelitis (EAE) model in which young adult mice injected with encephalitogenic T helper 17 cells develop remitting disease, while middle-aged mice injected with the same cell pool develop severe, chronic disease. The work characterizes a subset of innate-like B-cells that are enriched and clonally expanded in the central nervous system of middle-aged EAE mice but are less frequent and lack clonal expansion in younger mice. These cells exhibit transcriptomic similarities to age-associated B-cell with clonal expansions (ACE B-cells), previously associated with lupus and chronic infections. One dominant clone expresses immunoglobulin sequences reactive against phosphatidylcholine, a major myelin component also found on apoptotic cell membranes. The research addresses the poorly understood mechanism by which B-cells contribute to disease progression in multiple sclerosis, complementing the known therapeutic efficacy of B-cell targeting therapies such as anti-CD20 monoclonal antibodies.

Work is performed in Columbus, Ohio. The period of performance extends from September 1, 2026, through April 30, 2028.

Abstract

Multiple sclerosis (MS) is a multifocal inflammatory demyelinating disease of the central nervous system (CNS), presenting in two major clinical forms. Younger adults typically develop relapsing-remitting MS (rrms), characterized by episodic neurological dysfunction followed by partial or full recovery, whereas older patients are more likely to experience progressive MS (PMS), marked by a gradual accumulation of disability. MS is widely believed to be an autoimmune disease mediated by lymphocytes reactive against CNS autoantigens. The therapeutic efficacy of b-cell targeting therapies, such as anti-CD20 monoclonal antibodies, in both forms of disease underscores the role of b-cells in MS pathogenesis across disease stages. However, the precise mechanism by which b-cells contribute to disease progression is poorly understood. To better simulate MS across disease stages, we developed an age-dependent experimental autoimmune encephalomyelitis (EAE) model. Young adult mice injected with encephalitogenic TH17 cells develop remitting EAE, while middle-aged mice injected with the same pool of TH17 cells develop severe, chronic disease. Our preliminary studies reveal that a subset of innate-like b-cells, enriched and clonally expanded in the CNS of middle aged EAE mice, is less frequent and lacks clonal expansion in younger mice. These cells exhibit transcriptomic similarities to age- associated B1-cells with clonal expansions (ACE b-cells), previously associated with lupus and chronic infections. Notably, one of the dominant clones in our model expresses immunoglobulin sequences reactive against phosphatidylcholine (PTC), a major myelin component also found on the outer cell membrane of apoptotic cells. While most MS research has focused on class switched B2-cells, emerging evidence suggests a role of innate like B1-cells. Anti-PTC IGM antibodies have been detected in the cerebrospinal fluid (CSF) of MS patients, correlating with greater white matter lesion burden, more severe disability, and increased brain atrophy. However, the contribution of specific b-cell subsets to MS and how they evolve with aging remain unclear. This proposal aims to elucidate the mechanisms underlying ACE b-cell accumulation in the CNS of middle-aged EAE mice and to determine their role in disease progression. In aim 1, i will test my hypothesis that ACE b-cell recruitment is mediated by enhanced production of the chemokines CXCL13 and CCL19, using in vitro chemotaxis assays and in vivo neutralization strategies. Aim 2 will pinpoint the spatial location of ACE b-cells relative to encephalitogenic t cells and CNS damage, assess their ability to reactivate encephalitogenic TH17 cells EX vivo, and determine whether PTC-specific ACE b-cell antibodies exacerbate EAE in young adult or middle-aged mice. Understanding how age influences b-cell recruitment to the CNS and elucidating the pathogenic properties of ACE b-cells could open new therapeutic approaches in PMS, an area of significant unmet need, and provide novel insights into the function of B1-cells in neuroinflammation.