The immune landscape of MOG antibody-associated disease identifies Tfh–Th17 cells as potential early drivers of neuroinflammation

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is an inflammatory disorder of the central nervous system (CNS) characterized by a propensity for relapse, incompletely understood pathogenesis, and a lack of approved therapies. We performed single-cell RNA sequencing of paired peripheral blood mononuclear cell (PBMC) and cerebrospinal fluid (CSF) samples from patients with MOGAD. Key findings were validated by flow cytometry and in vitro stimulation assays in an independent clinical cohort, as well as by examining lesion tissues from patients and an MOG-IgG-augmented experimental autoimmune encephalomyelitis (MOG-EAE) model. Our findings support a data-informed working model of MOGAD involving peripheral immune activation, CNS amplification, and metabolic adaptation. During peripheral immune system activation, ITGA4 + Tfh–Th17 and Tfh, CXCR6 + ex-Th17, CX3CR1 + CD8 + TEM, and CXCR4 + memory B cells exhibited transcriptional features associated with migration and chemotaxis. Among them, ITGA4 + Tfh–Th17 cells exhibited hyperexpanded TCR clones in both CSF and PBMCs and were inferred to be the predominant signal senders in the CD40 and MIF signaling pathways. Consistently, the marker-defined Tfh–Th17-like cells (CD4 + CD161 + CD40L + ) showed an MOG-responsive increase in frequency in vitro and were observed in perivascular regions of the examined lesions, supporting a possible role in early disease-related immune activation. Transcriptomic analysis revealed features of Th1 plasticity in CXCR6 + ex-Th17 cells, while immunofluorescence analysis showed prominent parenchymal infiltration by Th17.1 cells (CD4 + CCR6 + CXCR3 + ) in lesion tissues of patients and MOG-EAE mice. CellChat predicted CD40-pathway interactions between Tfh-like cells (including Tfh–Th17 and Tfh cells) and IGHG1 + B cells; these interactions were also predicted during remission. In the MOG-EAE model, anti-CD40L mAb treatment significantly reduced clinical scores, attenuated inflammation and demyelination, and markedly reduced infiltration by Tfh–Th17-like cells (CD4 + CD161 + CD40L + ) and Th17.1 cells (CD4 + CCR6 + CXCR3 + ). This study identifies a transcriptomically defined Tfh–Th17 cell state associated with early disease-related immune activation in MOGAD and implicates Th17.1 cells and memory B cells as potential contributors to CNS inflammation.