Trichomonas vaginalis triggers the release of THP-1 extracellular traps.

Trichomonas vaginalis is responsible for the prevalence of trichomoniasis, which may be one of the most epidemic nonviral sexually transmitted pathogens. Extracellular traps (ET) are a unique form of innate immunity against infection; they bind to and kill microorganisms. However, the effect of T. vaginalis on ET release in the human monocytic cell line THP-1 remains unclear. In the present study, the morphology of ET derived from THP-1 in response to T. vaginalis was observed by scanning electron microscopy (SEM). The results demonstrated ET entangling T. vaginalis. Then, the colocalization of histone (H3) and myeloperoxidase (MPO) with DNA was observed via fluorescence confocal microscopy. Colocalization revealed the classic characteristics of DNA decorated with H3 and MPO. T. vaginalis significantly increased reactive oxygen species (ROS) and THP-1-derived ET. In addition, we measured the levels of lactic dehydrogenase (LDH) and the phosphorylation of the P38 and ERK1/2 MAPK signaling pathways. The results indicated that the formation of ET induced by T. vaginalis was related to phosphorylation of the P38 and ERK1/2 MAPK signaling pathways but not to LDH levels. These data confirmed the phenomenon of THP-1-derived ET being triggered by T. vaginalis in vitro; this process may play a pivotal role in innate immunity during defense against T. vaginalis infection.