Exploring eNOS-Caveolin-1 interaction in placentas of SARS-Cov-2 positive pregnancies

The placenta serves as a vital interface between mother and fetus, facilitating nutrient exchange and immune regulation. Although generally effective in preventing pathogen transmission, some viruses such as CMV and Zika can cross this barrier. The mechanism of vertical transmission of SARS-CoV-2 remains unclear.

To investigate the expression and interaction of caveolin-1 (Cav-1) and endothelial nitric oxide synthase (eNOS) in placental tissues from SARS-CoV-2-positive pregnancies and their potential role in limiting vertical transmission.

Placental samples were obtained from RT-PCR-confirmed COVID-19-positive and healthy pregnancies. Histological, immunohistochemical, and immunofluorescence techniques were used to evaluate tissue morphology and Cav-1/eNOS expression.

Control placentas exhibited intact villous structures, normal erythrocyte morphology, and strong Cav-1 and eNOS expression in endothelial cells. SARS-CoV-2-positive placentas showed villous damage, swollen erythrocytes, decreased collagen, and reduced endothelial expression of Cav-1 and eNOS. Cav-1 was absent in syncytiotrophoblasts in all samples.

Reduced expression of Cav-1 and eNOS in endothelial cells, combined with the absence of Cav-1 in syncytiotrophoblasts, may contribute to the placental resistance against SARS-CoV-2. These findings support the hypothesis that molecular features of the placenta, particularly involving Cav-1/eNOS pathways, play a protective role in preventing vertical transmission.