BMC Immunology (Sep 2018)

Treponema pallidum promotes macrophage polarization and activates the NLRP3 inflammasome pathway to induce interleukin-1β production

  • Li-Rong Lin,
  • Wei Liu,
  • Xiao-Zhen Zhu,
  • Yu-Yan Chen,
  • Zheng-Xiang Gao,
  • Kun Gao,
  • Man-Li Tong,
  • Hui-Lin Zhang,
  • Yao Xiao,
  • Wen-Dong Li,
  • Shu-Lian Li,
  • Hui-Ling Lin,
  • Li-Li Liu,
  • Zan-Xi Fang,
  • Jian-Jun Niu,
  • Yong Lin,
  • Tian-Ci Yang

DOI
https://doi.org/10.1186/s12865-018-0265-9
Journal volume & issue
Vol. 19, no. 1
pp. 1 – 9

Abstract

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Abstract Background The involvement of inflammasome activation and macrophage polarization during the process of syphilis infection remains unknown. In this study, A series of experiments were performed using human macrophages to research the role of NLRP3 inflammasome regulation in interleukin (IL)-1β production and its influence on macrophage polarization triggered by T. pallidum. Results The results showed that in M0 macrophages treated with T. pallidum, the M1-associated markers inducible nitric oxide synthase (iNOS), IL-1β and TNF-α were upregulated, and the M2-associated markers CD206 and IL-10 were downregulated. In addition, we observed NLRP3 inflammasome activation and IL-1β secretion in T. pallidum-treated macrophages, and the observed production of IL-1β occurred in a dose- and time-dependent manner. Moreover, the secretion of IL-1β by macrophages after T. pallidum treatment was notably reduced by anti-NLRP3 siRNA and caspase-1 inhibitor treatment. NAC, KCl, and CA074-ME treatment also suppressed IL-1β release from T. pallidum-treated macrophages. Conclusions These findings showed that T. pallidum induces M0 macrophages to undergo M1 macrophage polarization and elevate IL-1β secretion through NLRP3. Moreover, the process of NLRP3 inflammasome activation and IL-1β production in macrophages in response to T. pallidum infection involves K+ efflux, mitochondrial ROS production and cathepsin release. This study provides a new insight into the innate immune response to T. pallidum infection.

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