Telitacicept Inhibits the Maturation and Differentiation of B Lymphocytes in NMOSD

Telitacicept, a novel recombinant fusion protein comprising the ligand-binding domain of the TACI receptor and the Fc component of human IgG, has rarely been studied for the treatment of neuromyelitis optica spectrum disorders (NMOSD). This study aimed to explore the effects of telitacicept in NMOSD mice. An NMOSD mouse model was constructed. Fifty microliters of 0.8 mg/mL telitacicept was injected intravenously on Days 4, 8, 12 and 16 postimmunization (p.i.). Behavioral scoring, magnetic resonance imaging and histopathological evaluation were conducted on Day 19. B lymphocytes and their subgroups were analyzed by flow cytometry. Concentration of serum IgM was measured using an ELISA kit. Concentrations of B lymphocyte stimulator (BLyS) and IL-6 were measured via LEGENDplex. Differentially expressed genes of B lymphocytes were screened via mRNA sequencing and verified by qPCR. Behavioral score of telitacicept-treated NMOSD mice significantly decreased (p < 0.0001). Inflammation, demyelination, loss of AQP4 and GFAP in the spinal cord were markedly alleviated (p < 0.05). B lymphocytes and their subsets were reduced to varying degrees (p < 0.05). Telitacicept treatment significantly reduced serum IgM levels (p < 0.01), as well as BLyS and IL-6 concentrations (p < 0.05). Telitacicept induced differential gene expression in B lymphocytes, inhibiting the expression of transcription factors related to B lymphocyte maturation, such as IRF8, BLIMP1, and Pou2af1, as well as cell surface receptors such as CD19 and CD21. Telitacicept has a therapeutic effect on NMOSD mice by regulating the differentiation of B lymphocyte subsets and inhibiting the production of pathogenic antibodies.