Oral Concurrent Session 2 - Prematurity
Oral Concurrent Sessions
Expedited Sessions
The placenta exists as a maternal-fetal barrier and displays remarkable immunoactivity. This barrier is effective against multiple pathogens, yet, the underlying mechanisms of immune regulation are not well understood. The inner layer of the fetal membrane, the amnion, has been proposed to be a significant barrier to infection. The amnion is made up of an epithelial layer and a mesenchymal layer. The amnion has been reported to contain CD14+ cells, but the immune activity and localization of these cells are poorly characterized. As a monocyte marker, these CD14+ cells may be endemic to the amnion and involved in antimicrobial defenses.
Study Design:
Fetal membranes were collected from cesarean sections in the absence of labor or inflammation. The amnion and chorion were separated mechanically and cultured to generate conditioned media. mCherry labeled L. monocytogenes (LM) or CFSE labeled S. agalactiae (GBS) were used to infect explants and infectivity was quantified by colony forming units. Immunofluorescence staining was used to localize CD14. Bacteria colonization with CD14 was visualized in infected tissue explants. CD86 and CD163 were used as M1 and M2 markers respectively. Imaging was performed using the STELLARIS confocal microscope.
Results:
CD14+ cells exist in healthy amniotic tissue explants and appear to localize in the mesenchymal layer. Amnion CD14+ cells also co-localize with CD86 and without CD163 suggesting a distinct phenotype from other placental macrophages (Hoffbauer cells and PAMM subsets). Amnion explants have decreased growth of LM and GBS in comparison to chorion and chorionic villi. LM co-localized with CD14+ cells in the amnion.
Conclusion:
We present the novel finding of resident macrophages in the amnion and demonstrate the presence of amnion macrophages in the absence of infection. Amnion macrophages express CD86 and contain bacteria that can be vertically transmitted. Further characterization of the regulation of these cells may provide insight into the immunomodulatory function of the fetal membrane.
Eva Fandozzi, BA (she/her/hers)
University of Pittsburgh School of Medicine
Pittsburgh, Pennsylvania, United States
Caroline Smith, BA (she/her/hers)
University of Pittsburgh School of Medicine
Pittsburgh, Pennsylvania, United States
Christina J. Megli, MD, PhD
Research Assistant Professor
Magee- Womens Hospital UPMC
Pittsburgh, Pennsylvania, United States