Treponema pallidum membrane protein Tp47 induced autophagy and inhibited cell migration in HMC3 cells via the PI3K/AKT/FOXO1 pathway

Abstract

The migratory ability of microglia facilitates their rapid transport to a site of injury to kill and remove pathogens. However, the effect of Treponema pallidum membrane proteins on microglia migration remains unclear. The effect of Tp47 on the migration ability and autophagy and related mechanisms were investigated using the human microglial clone 3 cell line. Tp47 inhibited microglia migration, the expression of autophagy‐associated protein P62 decreased, the expression of Beclin‐1 and LC3‐II/LC3‐I increased, and the autophagic flux increased in this process. Furthermore, autophagy was significantly inhibited, and microglial cell migration was significantly increased after neutralisation with an anti‐Tp47 antibody. In addition, Tp47 significantly inhibited the expression of p‐PI3K, p‐AKT, and p‐mTOR proteins, and the sequential activation of steps in the PI3K/AKT/mTOR pathways effectively prevented Tp47‐induced autophagy. Moreover, Tp47 significantly inhibited the expression of p‐FOXO1 protein and promoted FOXO1 nuclear translocation. Inhibition of FOXO1 effectively suppressed Tp47‐induced activation of autophagy and inhibition of migration. Treponema pallidum membrane protein Tp47‐induced autophagy and inhibited cell migration in HMC3 Cells via the PI3K/AKT/FOXO1 pathway. These data will contribute to understanding the mechanism by which T. pallidum escapes immune killing and clearance after invasion into the central nervous system.

Neurosyphilis: insights into its pathogenesis, susceptibility, diagnosis, treatment, and prevention

“…CSF sTREM2 (a biomarker of microglial activation) was observed to be at significantly higher levels in neurosyphilis patients ( 26 ). Further study revealed that T. pallidum promotes microglial apoptosis and inhibits microglial migration as a means of evading clearance ( 27 , 28 ). The balance between phagocytic uptake and T. pallidum evasion is influenced by production of opsonic antibodies, with TP0326 (BamA) and TP0751 (pallilysin) being identified as opsonic targets ( 29 , 30 ).…”