HMGB1 Mediates Microglia-Astrocyte/Neuron Crosstalk and Pyroptosis by the TLR4/NF-κB Pathway in Multiple Sclerosis

Background: Multiple sclerosis (MS) is characterized as a chronic inflammatory autoimmune disorder affecting the central nervous system (CNS). Prior research has explored the involvement of Pyroptosis and high mobility group box 1 (HMGB1) in the pathophysiology of MS. Nevertheless, the underlying pathogenic mechanisms and their interactions have yet to be fully elucidated.

Methods: Myelin oligodendrocyte glycoprotein (MOG)35-55-treated mice and BV-2 microglial cells were utilized as a model for MS. Subsequently, these subjects were transfected with lentiviral vectors that express short hairpin RNA targeting HMGB1. HT-22 cells and Ma-c cells were exposed to conditioned medium (CM) derived from BV-2 cells following treatment. The levels of HMGB1, tumor necrosis factor (TNF)-α, and interleukin-1β (IL-1β) were quantified using enzyme-linked immunosorbent assay (ELISA). Additionally, western blot (WB) analysis was performed to further elucidate the mechanisms involved.

Results: Mice treated with MOG35-55 (experimental autoimmune encephalomyelitis, EAE) exhibited reduced body weights and significant nerve function impairment (p < 0.001), accompanied by increased activation of microglia within the CNS (p < 0.05). Additionally, the secretion of HMGB1 was found to be upregulated in the MS cell model (p < 0.05), and CM from these cells induced the release of pro-inflammatory cytokines in HT-22 and Ma-c cell lines (p < 0.001). Notably, the modulation of HMGB1 and NOD-like Receptor family pyrin domain containing 3 (NLRP3) expression was shown to mitigate the release of pro-inflammatory cytokines (p < 0.01), TUNEL-positive cells (p < 0.01) in both HT-22 cells and Ma-c cells, which were induced by CM from BV-2 cells treated with MOG35-55. Furthermore, WB analysis indicated that the suppression of HMGB1 expression can inhibit the activation of the Toll-like Receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway, as well as Pyroptosis in EAE mice and HT-22/ Ma-c cells exposed to CM from BV-2 cells (p < 0.05).

Conclusion: HMGB1 has the potential to act as a promoter of MS through the activation of TLR4/NF-κB signaling pathway and the induction of Pyroptosis in microglial and Other cells. Consequently, the modulation of HMGB1 may represent a novel therapeutic strategy for the management of MS.

HMGB1; inflammation; multiple sclerosis; neuroimmune interaction; pyroptosis.