Macrophage-Mediated Efferocytosis in Rat Uterine Remodeling



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Macrophages are professional phagocytes that survey the body for pathogens and secrete biomolecules relevant to many cellular processes. Our lab identified the presence of macrophages around the rat uterine lumen and within the metrial gland during mid-pregnancy and postpartum. We hypothesized that macrophages might be involved in the clearance of apoptotic cells, i.e., efferocytosis. The aim of this study was to test this further. Using quantitative real-time PCR during pregnancy and postpartum timepoints, we found that the pan-macrophage marker CD68, phosphatidylserine receptor MerTK, and anti-inflammatory marker TGFβ1 were expressed at higher levels compared to pro-inflammatory marker TNFα in the rat’s metrial gland and decidua. We hypothesized that if macrophages were efferocytosing, they must be expressing MerTK. Hence, we performed double immunofluorescence across pregnancy and postpartum in the rat using frozen tissue sections containing metrial gland and decidua. Macrophages (CD68-positive) appeared spatially proximal to apoptotic cells (Annexin V-positive) and scattered in the tissue amongst perforin-positive natural killer cells. Lastly, only a few macrophages were MerTK-positive and other unknown cell types also expressed MerTK. This suggests that macrophages involved in uterine remodeling may be functionally heterogeneous. Future studies will focus on understanding how macrophages affect pregnancy in rats and whether this may have relevant implications to humans.



Macrophages, Efferocytosis, Reproductive Immunology, Innate Immunity