Abstract
Objective: The objective of this study was to investigate the effects of rituximab (RTX) intrathecal injection on antibody levels in serum and cerebrospinal fluid (CSF), hippocampal tissue and neuronal injury and the behaviour of central neuropsychological lupus erythematosus (cNPSLE) model mice and to further explore the effects of RTX on microglia (MG) polarisation and related signalling pathways. Methods: Female MRL/lpr mice received intrathecal RTX, with C57BL/6 and MRL/mpj mice as controls. Behavioural performance was evaluated using the open field test, novel object recognition and Porsolt swim task. Autoantibody levels in serum and CSF were measured by ELISA. Hippocampal pathology was assessed by H&E and Nissl staining. M1-type MG activation (Iba-1+/CD32+), CD20+ B-cell infiltration and immunoglobulin G (IgG) deposition were examined via immunohistochemistry and immunofluorescence. Immune transcriptome sequencing and in vitro polarisation assays were used to identify regulatory pathways. Results: Intrathecal injection of RTX reduced the levels of antibodies in the serum and CSF of MRL/lpr mice and alleviated brain tissue injury and neuronal injury. Moreover, hippocampal MG M1 polarisation was inhibited, and the number of CD20+ B cells and expression of IgG were reduced. Transcriptome sequencing revealed that the cAMP-dependent protein kinase A (cAMP/PKA) pathway may be involved in the activation of M1-type MG in the hippocampus. In vitro cell experiments demonstrated that RTX could reduce the expression of kinase cAMP-activated catalytic subunit alpha and phosphorylated-cAMP response element-binding protein/cAMP response element-binding protein through the suppression of the cAMP/PKA pathway, thus inhibiting M1-type MG activation. Conclusion: The data in this study revealed that the intrathecal injection of RTX can attenuate M1-type MG activation-mediated inflammatory neuronal injury in cNPSLE model mice.