Dendritic Cell-Derived Exosomes Stimulated by Treponema pallidum Induce Endothelial Cell Inflammatory Response through the TLR4/MyD88/NF-κB Signaling Pathway

Exosomes have been implicated in vascular damage in recent research. The influence of dendritic cell-derived exosomes generated by Treponema pallidum ( T. pallidum ) on the inflammatory process of vascular cells was examined in this study. Human umbilical vein endothelial cells (HUVECs) were cocultured with exosomes isolated from dendritic cells induced by T. pallidum . Western blot and reverse transcription-quantitative real-time polymerase chain reaction were used to assess toll-like receptor 4 (TLR4) expression and the quantity of proinflammatory cytokines. The findings showed that the expression of TLR4 was considerably upregulated, and TLR4 knockdown dramatically reduced interleukin-1β ( IL-1β ), interleukin-6 ( IL-6 ), and tumor necrosis factor- α ( TNF-α ) production in exosome-treated HUVECs. Furthermore, TLR4 silencing reduced myeloid differentiation primary response protein 88 (MyD88) and nuclear factor kappa light chain enhancer of activated B cells (NF-κB) levels in exosome-treated HUVECs. Additionally, suppression of the activity of NF-κB with BAY11-7082, an NF-κB inhibitor, also reduced the exosome-treated inflammatory response. Our results suggested that dendritic cell-derived exosomes stimulated by T. pallidum induced endothelial cell inflammation, and the TLR4/MyD88/NF-κB signal axis was activated, significantly increasing IL-1β, IL-6, and TNF-α expression. This may have a significant role in the vascular inflammatory response in syphilis, which would contribute to the understanding of the pathogenesis of syphilis and the host immunological response to T. pallidum .