Impact of uterine macrophage phenotype on placental retention in dairy cows

Reproductive diseases affect 25% of dairy cows in the US and often develop from retention of the placenta. It is well established that expulsion of the placenta is a highly regulated inflammatory process, but the mechanisms by which dysregulation of uterine immune responses impair this process are poorly understood. In healthy non-ruminants, pro-inflammatory M1 macrophages are predominant in uterine tissue after parturition. However, macrophage phenotype in the postpartum bovine uterus is unknown. Our study compared macrophage phenotypes in the uterine caruncles of multiparous dairy cows that during the first day postpartum either retained (RET, n = 5) or had normal expulsion (NOR, n = 5) of placenta. Immune cells were sorted magnetically from the caruncular endometrial cell fraction using the CD172a marker and monocyte/macrophage population was characterized using flow cytometry. Transcriptional and protein expression studies were performed on uterine caruncles. Compared to NOR, RET samples showed a lower CD14+/CD16+ expression (P