ABSTRACT TGFβ1 plays a key role in placental development, but its regulation of trophoblast function isn't fully known. Meanwhile, the TLR4/NF‐κB pathway is linked to trophoblast dysfunction, yet the mediator linking TGFβ1 to this pathway is unclear. Thus, this study examines if tTG mediates TGFβ1's regulation of trophoblast functions via TLR4/NF‐κB and its relevance in preeclampsia (PE). To address this, HTR‐8/Svneo cells were treated with TGFβ1, cell migration, invasion, and proliferation were assessed via Transwell and CCK‐8 assays. The expression of tTG, TLR4/NF‐κB pathway components, and pro‐inflammatory cytokines was evaluated by qPCR and Western blot. Gain‐ and loss‐of‐function approaches for tTG and TLR4 were employed, alongside transcriptome sequencing. The role of tTG's enzymatic activity was tested using the inhibitor Z‐DON. Placental tissues from normal and preeclamptic pregnancies were analyzed for clinical validation. The results showed that TGFβ1 dose‐dependently inhibited trophoblast migration, invasion, and proliferation while upregulating tTG expression. tTG overexpression activated the TLR4/NF‐κB pathway and altered the transcriptome. TLR4 inhibition blocked tTG‐mediated NF‐κB activation. Furthermore, tTG knockdown and inhibiting tTG's enzymatic activity reversed the suppressive effects of TGFβ1 on cell functions and downstream TLR4/NF‐κB signaling. Clinically, the protein levels of tTG and activated TLR4/NF‐κB pathway components were significantly elevated in preeclamptic placentas. In conclusion, this study first reveals a TGFβ1/tTG/TLR4/NF‐κB axis in trophoblasts, showing TGFβ1 inhibits trophoblast function via upregulation of tTG, which functionally leads to activation of the TLR4/NF‐κB pathway in an enzyme activity‐dependent manner, providing new insights into PE pathogenesis and potential therapeutic targets.
Cheng et al. (Mon,) studied this question.