Abstract
Background: Pregnant women are at increased risk for severe outcomes from coronavirus disease 2019 (COVID-19), but the pathophysiology underlying this increased morbidity and its potential effect on the developing fetus is not well understood.
Methods: We assessed placental histology, ACE2 expression, and viral and immune dynamics at the term placenta in pregnant women with and without respiratory severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
Findings: The majority (13 of 15) of placentas analyzed had no detectable viral RNA. ACE2 was detected by immunohistochemistry in syncytiotrophoblast cells of the normal placenta during early pregnancy but was rarely seen in healthy placentas at full term, suggesting that low ACE2 expression may protect the term placenta from viral infection. Using immortalized cell lines and primary isolated placental cells, we found that cytotrophoblasts, the trophoblast stem cells and precursors to syncytiotrophoblasts, rather than syncytiotrophoblasts or Hofbauer cells, are most vulnerable to SARS-CoV-2 infection in vitro . To better understand potential immune mechanisms shielding placental cells from infection in vivo , we performed bulk and single-cell transcriptomics analyses and found that the maternal-fetal interface of SARS-CoV-2-infected women exhibited robust immune responses, including increased activation of natural killer (NK) and T cells, increased expression of interferon-related genes, as well as markers associated with pregnancy complications such as preeclampsia.
Conclusions: SARS-CoV-2 infection in late pregnancy is associated with immune activation at the maternal-fetal interface even in the absence of detectable local viral invasion.
Funding: NIH (T32GM007205, F30HD093350, K23MH118999, R01AI157488, U01DA040588) and Fast Grant funding support from Emergent Ventures at the Mercatus Center.
Keywords: COVID-19; SARS-CoV-2; placenta; pregnancy.
【저자키워드】 COVID-19, SARS-CoV-2, Placenta, Pregnancy, 【초록키워드】 coronavirus disease, stem cells, immunohistochemistry, viral infection, Coronavirus disease 2019, ACE2, coronavirus, T cells, SARS-COV-2 infection, transcriptomics, Infection, Local, in vitro, outcome, immune, preeclampsia, pregnant women, Pregnancy, Viral, pathophysiology, cells, immune activation, immune responses, morbidity, Complication, placental, Viral RNA, women, pregnancy complications, respiratory, in vivo, histology, ACE2 expression, single-cell, immune mechanism, marker, Analysis, stem cell, early pregnancy, Support, shielding, natural killer, acute respiratory syndrome, Activation, full term, increased expression, acute respiratory syndrome coronavirus, increased risk, center, precursors, precursor, viral invasion, Placentas, immortalized cell lines, Genes, Cell, Hofbauer cells, robust, PROTECT, analyzed, performed, healthy, detectable, exhibited, majority, absence, had no, NIH, immortalized cell line, 【제목키워드】 Maternal, Inflammatory response, robust,