Recombinant protein TprK promotes M1 macrophage polarization and phagocytosis by inducing Indoleamine 2,3-dioxygenase protein production.

Syphilis, caused by Treponema pallidum (T. pallidum), remains a significant global health concern, with its pathogenesis closely linked to immune system interactions. Macrophages play a critical role in host defense, with polarization towards the M1 phenotype contributing to pro-inflammatory responses and pathogen clearance. However, the specific mechanisms through which T. pallidum modulates macrophage activity remain unclear. In this study, we investigated the role of recombinant TprK (rTprK), an outer membrane protein of T. pallidum, in macrophage polarization and phagocytic function. Our findings reveal that rTprK significantly enhances M1 polarization and promotes the production of pro-inflammatory cytokines (P < 0.05). Additionally, we demonstrate that rTprK induces indoleamine 2,3-dioxygenase (IDO) production through the TLR2/JAK1/STAT1 pathway, which is crucial for modulating macrophage function (P < 0.05). Inhibition of TLR2, JAK1, or STAT1 effectively reduces IDO expression and attenuates macrophage activation (P < 0.05). These findings provide novel insights into the immunoregulatory role of rTprK in T. pallidum infection.