miR-320a Regulates Placenta Endothelial Function After Fetal Cardiopulmonary Bypass via the ATG7-SIRT1/FOXO1 Pathway.

Objective: Placental dysfunction induced by fetal cardiopulmonary bypass (CPB) imposes limitations on the clinical application of this procedure. The potential impact of microRNA-mediated autophagy in placental endothelial cells on overall placental function remains elusive, necessitating a comprehensive exploration of the underlying mechanisms involved.

Methods: We established fetal sheep CPB models and employed immunohistochemistry to assess the placental expression of ATG7. Bioinformatic analysis, coupled with dual-luciferase reporter assays, was used to elucidate the intricate relationship between miR-320a and ATG7. Changes in ATG7 expression were further investigated through Western blotting and quantitative polymerase chain reaction (qPCR). Human umbilical vein endothelial cells (HUVECs) were cultured, and in vitro experiments were conducted to evaluate their regulatory effects on endothelial function. Immunoblotting was used to measure the expression levels of ATG7, endothelin-1 (ET-1), SIRT1, and FOXO1, whereas enzyme-linked immunosorbent assay (ELISA) was used to quantify nitric oxide (NO) production.

Results: Sixty minutes after CPB, a substantial decrease in ATG7 expression in placental tissue was observed. The downregulation of ATG7 expression led to increased ET-1 production in HUVECs, concomitant with decreased NO production. miR-320a was identified as a specific regulator of ATG7 expression, with subsequent experiments demonstrating a significant reduction in placental ATG7 levels upon injection of the miR-320a agomir compared with the miR-320a antagomir during fetal sheep CPB. In HUVECs, miR-320a downregulated ATG7, resulting in increased ET-1 production and diminished NO production. Treatment with the miR-320a mimic/miR-320a inhibitor revealed that miR-320a inhibited the SIRT1/FOXO1 pathway in HUVECs by downregulating ATG7 expression, culminating in increased ET-1 production and reduced NO levels.

Conclusion: The observed downregulation of placental ATG7 expression subsequent to fetal CPB is intricately associated with endothelial dysfunction. Furthermore, our findings underscore the specific regulatory role of miR-320a in modulating ATG7 expression within the placenta. At the cellular level, increasing the level of miR-320a has emerged as a potential strategy for modulating endothelial function through the inhibition of ATG7 and the SIRT1/FOXO1 pathway.