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Treponema pallidum Protein TpF1 Inhibits Migration by Impairing Actin Polymerization via Toll-Like Receptor

Yuan-Yi Zhao1, Lin Xie1, Ruo-Ying Wang1

  • 1Center of Clinical Laboratory, Zhongshan Hospital Xiamen University, School of Medicine, Xiamen University, Xiamen 361004, China.

ACS Infectious Diseases
|April 24, 2025
PubMed

Insights

The Treponema pallidum protein TpF1 inhibits microglial migration by disrupting actin polymerization via the Toll-like receptor 4 (TLR4) pathway. This finding reveals a novel immune evasion mechanism in central nervous system (CNS) infections.

Area of Science:

  • Neuroimmunology
  • Infectious Diseases
  • Cell Biology

Background:

  • Treponema pallidum invades the central nervous system (CNS), triggering microglial responses.
  • Impaired microglial migration's role in T. pallidum pathogenesis is poorly understood.
  • Microglia are crucial immune cells in the CNS, involved in pathogen clearance and injury response.

Purpose of the Study:

  • To investigate the molecular mechanisms by which the T. pallidum protein TpF1 inhibits microglial migration.
  • To elucidate TpF1's impact on actin polymerization and related signaling pathways.
  • To understand T. pallidum's immune evasion strategies in the CNS.

Main Methods:

  • Utilized microglial HMC3 cells to assess TpF1's effects on migration and actin polymerization.
  • Quantified changes in filamentous actin (F-actin) and globular actin (G-actin) ratio using immunofluorescence.
  • Analyzed the expression of Toll-like receptor 4 (TLR4), PI3K/AKT pathway components, and Rac1.

Main Results:

  • TpF1 significantly reduced microglial migration in horizontal and vertical directions.
  • TpF1 decreased the F-actin/G-actin ratio, indicating impaired actin polymerization.
  • TpF1 suppressed TLR4, phosphorylated PI3K (P-PI3K)/PI3K, phosphorylated AKT (P-AKT)/AKT, and Rac1 expression.

Conclusions:

  • TpF1 disrupts microglial migration by inhibiting actin polymerization through the TLR4/PI3K/AKT signaling pathway.
  • This study identifies a novel mechanism of immune evasion by T. pallidum in the CNS.
  • Findings provide insights into the pathogenesis of T. pallidum-induced CNS infections.
Keywords:
Treponema pallidumTreponema pallidum protein TpF1actinmigration

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