The Immunology of Early Pregnancy in Farm Animals

Abstract

Contents The mammalian conceptus undergoes development in the face of a functional immune system. This characteristic of viviparity creates opportunities and perils for the conceptus. In the period up to hatching from the zona pellucida, the conceptus appears immunologically inert with low expression of major histocompatibility complex (MHC) genes and little evidence for alterations in the function of maternal immune cells. The conceptus may benefit from cytokines produced by leucocytes resident in the reproductive tract or by other cells of the reproductive tract. One cytokine in particular, colony‐stimulating factor 2, can promote preimplantation development and cause changes in conceptus function that increase the likelihood that the conceptus develops to term. It is not clear whether activation of specific types of immune responses in early pregnancy can enhance the likelihood of pregnancy success. Semen deposition causes inflammation in the reproductive tract, but there is little evidence that this process is beneficial to pregnancy unless the uterus was exposed to a prior inflammatory event. Around the time of placentation, the period of immunological inertness of the conceptus is replaced by a period of immune activation caused by the expression of interferon genes in ruminants and pigs and MHC class I genes in invasive trophoblast of the horse. The large‐scale changes in the endometrium that occur as a result are likely to play an important role to ensure continued development of the conceptus. In contrast, other immune responses generated as a result of disease in the reproductive tract or other tissues (mastitis) can lead to death of the conceptus. Because of this hazard, as well as the possibility that cell‐mediated immune responses against the conceptus could occur, the immune system is regulated by both the mother and conceptus to reduce immune responsiveness during pregnancy.

Prostasomes: extracellular vesicles from the prostate

“…On the one hand, it has to protect the carrier and a potential embryo or fetus against invading pathogens, but on the other hand, it must tolerate potentially highly immunogenic paternal alloantigens in order to be able to establish and maintain pregnancy (reviewed in Wira et al (2005) and Hansen (2011)). Macrophages and neutrophil granulocytes form a first line of defence against pathogens but also phagocytose sperm cells (Matthijs et al 2003, Wira et al 2005.…”

Current and Future Assisted Reproductive Technologies for Mammalian Farm Animals

“…Addition of the heterodimer of porcine seminal protein I (PSP1) and PSPII to sex-sorted boar sperm improved fertilization rate when sperm were placed in the oviduct laparoscopically (García et al 2007 ). There have also been inconsistent reports in pigs and cattle that addition of transforming growth factor-β to semen improves fertility following AI (Hansen 2011c ).…”

Bovine Endometrial Cells Mount Innate Immune Response to the Intracellular Ligands CL097 and Poly(dA:dT) Indicating Roles against Uterine Viruses

“…In females, TLRs have been implicated in the regulation of ovulation, fertilization, gestation and parturition, as well as in pathological conditions such as endometritis and mastitis [37]. In fact, immune responses generated towards other cells and molecules could have adverse consequences for reproduction [38] [39] [40]. Inappropriate activation of TLRs and other innate immune mediators such as cytokines and eicosanoids may also disrupt reproductive functions in the endometrium or the development of the conceptus thereby decreasing fertility.…”