Reprod Domest Anim. 2021 Jun 26. doi: 10.1111/rda.13983. Online ahead of print.
ABSTRACT
Retention of fetal membranes (RFM) is a major reproductive disorder in dairy cows. An appropriate immune response is important for a physiological expulsion of the fetal membranes at parturition. Our study aims to provide a deeper insight into characteristics of fetal and maternal macrophages in bovine term placenta. We used transmission electron microscopy (TEM), immunohistochemistry and semi-quantitative RT-PCR to provide a deeper insight into characteristics of fetal and maternal macrophages in bovine term placenta. Semi-quantitative RT-PCR was used to define macrophage polarization in fetal and maternal compartments of normal term placenta. Gene expression of factors involved in M1-polarization [interferon regulatory factor-5 (IRF5), interleukin (IL)-12A, IL12B] and in M2-polarization (IL10) were studied. Ultrastructurally, fetal macrophages showed an irregular shape and large vacuoles, whereas the maternal macrophages were spindle shaped. By immunohistochemistry macrophages were identified by a strong staining with the lysosomal marker Lysosome-associated membrane glycoprotein 1 (LAMP-1), while myofibroblast in the maternal stroma were positive for alpha-smooth muscle actin. We used the LAMP-1 marker to compare the density of fetal stromal macrophages in placentas of cows with RFM and in controls, but no statistically significant difference was observed. RT-PCR showed a higher expression of all studied genes in the maternal compartment of the placenta and generally a higher expression of M1-, compared to M2-associated genes. Our results indicated that at parturition placental macrophages predominantly show the pro-inflammatory M1-polarization. The higher expression of all the target genes in the maternal compartment may denote that maternal macrophages in bovine term placenta are more frequent than fetal macrophages.
PMID:34174122 | DOI:10.1111/rda.13983
