Inhibition of The Auto-inflammation Suppressor Protein ISG15 Triggers Preeclampsia by Blocking Trophoblast Migration and Invasion
Materials and Methods: Immunohistochemistry was performed on term decidua basalis specimens to determine cell specific ISG15 expression (n=4). Migration and invasion assays were performed on normal and ISG15-siRNA silenced HTR8/SVneo cells (human first-trimester chorionic villi explant-derived immortalized cytotrophoblasts) using non-coated and matrigel coated trans-wells and 24-h wound healing assays in 12-well culture plates. Statistical analysis used student’s t-test.
Results: Among decidua basalis cells, immunostaining revealed the highest in situ ISG15 expression in interstitial CTBs. Immunoblotting and qRT-PCR of HTR8 cultures confirmed significantly reduced ISG15 protein and mRNA levels following ISG15 siRNA vs. control siRNA treatment. Phase-contrast microscopy observed flattened and larger cells in HTR8 cultures following ISG15 siRNA vs. control siRNA treatment. Moreover, ISG15 siRNA silencing reduced HRT8 migration (Mean ± SEM 0.410±0.05 vs. 0.679± 0.080; p = 0.026; n=6), invasion (0.373±0.02 vs. 0.573±0.06; p= 0.024; n=5) and delayed in vitro wound healing compared to control siRNA treatment at 4 to12 h.
Conclusion: These results indicate that ISG15 expression levels are crucial for trophoblast morphology and function (migration/invasion). By blocking trophoblast invasion, reduced ISG15 levels could contribute to impaired spiral artery transformation that reduces utero-placental blood flow in PE. Thus, induction of ISG15 expression is likely to be therapeutic in preeclampsia.
Supported by U01HD087213 by NICHD.