Immunohistochemical Analysis of Placental Tissue of Women Infected with SARS-CoV-2 During Pregnancy-A Prospective Clinical Study.

SARS-CoV-2 has an affinity for binding to the human Angiotensin-converting enzyme 2 (ACE2) receptor through cleavage and conformational changes at the S1-S2 boundary and the receptor binding domain of the spike protein, which is also the most variable part of SARS-CoV-2. This study aimed to investigate the expression of Angiotensin-converting enzyme 2 (ACE2), spike protein, and CD68+ markers in placental tissue to demonstrate a possible correlation with the level of systemic oxidative stress biomarkers in patients who were infected with SARS-CoV-2 during pregnancy. A prospective clinical cohort study was designed to investigate the presence of CD68+ macrophages, ACE2, and spike proteins in placental tissue using immunohistochemical methods and to compare these results with oxidative stress from our previous study. Spike and CD68+ macrophages' immunoreactivity were more pronounced in the placental tissue of patients from the SARS-CoV-2 group. Placental tissue spike protein and CD68+ immunoreactivity correlate with maternal and fetal Thiobarbituric Acid Reactive (TBARS) levels. This study has confirmed that spike protein expression in placental tissue is associated with the newborn's stay in intensive neonatal care. Therefore, immunoreactivity analysis for the Spike antigen is important in detecting newborns at risk of early neonatal complications.