Monocyte chemotactic protein-1 and-2 messenger ribonucleic acids in the ovine uterus: Regulation by pregnancy, progesterone, and interferon-tau

Endometrial leukocytes may play important roles during pregnancy. Because c hemokines are regulators of immune cell activity and trafficking, this stud y determined if mRNAs for monocyte chemotactic proteins (MCP);were present in the ovine uterus and regulated by progesterone (P) and/or recombinant ov ine interferon tao (roIFN-tau). Uteri of normal cycling and pregnant ewes ( experiment 1) and uteri of ovariectomized ewes receiving intrauterine infus ions of IFN-tau and/or i.m. injections of P (experiment 2) were used to det ect MCP-1 and MCP-2 mRNA. In experiment 1, slot-blot hybridization analysis of endometrial total RNA revealed that MCP-1 and MCP-2 mRNA levels did not change during the estrous cycle but increased between Days 13 and 19 of pr egnancy. Using in situ hybridization, MCP-1 and MCP-2 mRNA were localized t o immune cells in the subepithelial compact stroma. Histomorphological stud ies and in situ hybridization for major basic protein (MBP) indicated that MCP-positive immune cells were eosinophils. In experiment 2, treatment with P and roIFN-tau increased (P < 0.05) the number of MCP-1- and MCP-2-expres sing eosinophils in the endometrium compared to ewes treated with P alone. Injection of the P receptor antagonist (ZK 137,316) inhibited effects of P and/or roIFN-<tau> to recruit eosinophils expressing MCP-1 and MCP-2 mRNAs. Endometrial production of MCPs by eosinophils during early pregnancy may p lay a role(s) in central implantation and/or placentation in ewes that is c rucial for successful establishment of pregnancy.