MicroRNA-155 modulates STAT3 signaling by targeting KPNA1 in chronic chorioamnionitis of human placenta

Chronic chorioamnionitis (CCA) is a placental inflammatory lesion characterized by maternal T cell infiltration and trophoblast apoptosis, resembling allograft rejection. MicroRNA-155 (miR-155) is a central regulator of immune and inflammatory pathways, but its role in CCA remains unclear. This study investigated whether miR-155 contributes to the pathogenesis of CCA by targeting karyopherin α1 (KPNA1) and modulating STAT3 signaling in human trophoblasts. Placental tissues from 28 CCA cases and 16 gestational age-matched controls were analyzed for miR-155 expression using quantitative RT-PCR and in situ hybridization. Functional assays were conducted in Swan 71 trophoblast cells following miR-155 overexpression and siRNA-mediated KPNA1 knockdown. Microarray and qRT-PCR analyses identified gene expression changes, while western blotting and dual-luciferase reporter assays were conducted to evaluate STAT3 activity and direct target binding. miR-155 expression was significantly elevated in CCA fetal membranes. KPNA1 was identified as a direct target of miR-155, and its suppression reduced STAT3 phosphorylation and nuclear translocation. Dual-luciferase assays confirmed that miR-155 binds to the 3' untranslated region of KPNA1 mRNA, thereby inhibiting its translation. These findings suggest that miR-155 downregulates KPNA1, leading to inhibition of STAT3 signaling in trophoblasts, which may contribute to maternal-fetal immune dysregulation and trophoblast apoptosis in CCA. The miR-155-KPNA1-STAT3 axis may represent a potential therapeutic target in pregnancy-related inflammatory disorders.