Trichomonas vaginalis Induces SiHa Cell Apoptosis by NF-κB Inactivation via Reactive Oxygen Species.

Trichomonas vaginalis induces apoptosis in host cells through various mechanisms; however, little is known about the relationship between apoptosis, reactive oxygen species (ROS), and NF-κB signaling pathways in the cervical mucosal epithelium. Here, we evaluated apoptotic events, ROS production, and NF-κB activity in T. vaginalis-treated cervical mucosal epithelial SiHa cells, with or without specific inhibitors, using fluorescence microscopy, DNA fragmentation assays, subcellular fractionation, western blotting, and luciferase reporter assay. SiHa cells treated with live T. vaginalis at a multiplicity of infection of 5 (MOI 5) for 4 h produced intracellular and mitochondrial ROS in a parasite-load-dependent manner. Incubation with T. vaginalis caused DNA fragmentation, cleavage of caspase 3 and PARP, and release of cytochrome c into the cytoplasm. T. vaginalis-treated SiHa cells showed transient early NF-κB p65 nuclear translocation, which dramatically dropped at 4 h after treatment. Suppression of NF-κB activity was dependent on parasite burden. However, treatment with the ROS scavenger, N-acetyl-C-cysteine (NAC), reversed the effect of T. vaginalis on apoptosis and NF-κB inactivation in SiHa cells. Taken together, T. vaginalis induces apoptosis in human cervical mucosal epithelial cells by parasite-dose-dependent ROS production through an NF-κB-regulated, mitochondria-mediated pathway.

Involvement of PI3K/AKT and MAPK Pathways for TNF-α Production in SiHa Cervical Mucosal Epithelial Cells Infected with Trichomonas vaginalis.

Trichomonas vaginalis; induces proinflammation in cervicovaginal mucosal epithelium. To investigate the signaling pathways in TNF-α production in cervical mucosal epithelium after T. vaginalis infection, the phosphorylation of PI3K/AKT and MAPK pathways were evaluated in T. vaginalis-infected SiHa cells in the presence and absence of specific inhibitors. T. vaginalis increased TNF-α production in SiHa cells, in a parasite burden-dependent and incubation time-dependent manner. In T. vaginalis-infected SiHa cells, AKT, ERK1/2, p38 MAPK, and JNK were phosphorylated from 1 hr after infection; however, the phosphorylation patterns were different from each other. After pretreatment with inhibitors of the PI3K/AKT and MAPK pathways, TNF-α production was significantly decreased compared to the control; however, TNF-α reduction patterns were different depending on the type of PI3K/MAPK inhibitors. TNF-α production was reduced in a dose-dependent manner by treatment with wortmannin and PD98059, whereas it was increased by SP600125. These data suggested that PI3K/AKT and MAPK signaling pathways are important in regulation of TNF-α production in cervical mucosal epithelial SiHa cells. However, activation patterns of each pathway were different from the types of PI3K/MAPK pathways.

Analysis of monocyte subsets and toll-like receptor 4 expression in peripheral blood monocytes of women in preterm labor.

Preterm labor is associated with both localized inflammation of the uterus and elevated proinflammatory cytokines. Recently, specific roles have been suggested for distinct monocyte subsets and toll-like receptor 4 (TLR4) expression in inflammation. The aim of this study was to determine whether specific monocyte subsets and increased TLR4 expression in monocyte subsets contribute to preterm labor. The study included 30 preterm labor, 40 full-term labor and 20 pregnant women (not in labor). Four-color flow cytometry was used to examine the distribution of three monocyte subsets (CD14(+)CD16(-), CD14(high)CD16(+), and CD14(low)CD16(+)) and the TLR4 expression in each monocyte subset in each group of women. A larger percentage of CD14(high)CD16(+) cells was found in the preterm labor group than in the other groups (P=0.08, P=0.06). Women in preterm labor also showed significantly higher TLR4 expression in all monocyte subsets and increased fluorescence intensity in the CD14(+)CD16(-) and CD14(high)CD16(+) cells. Expression of TLR4 and mean fluorescence intensity on each monocyte subset were also significantly correlated. We conclude that women with preterm labor have higher CD16 monocytes, with high concomitant expression of CD14 and enhanced TLR4 expression in monocytes, and that monocyte TLR4 levels could be used as a marker to predict preterm delivery.