Cytokines in vertebrate reproduction

Mechanisms determining survival and growth of the semi-allogeneic fetus in the maternal uterus are still not completely defined. Studies in mammals have shown that soluble substances with autocrine/paracrine action (cytokines) have a central role in the maternal-fetal immunotolerance thus, contributing to the expansion of fetal tissues in the maternal uterus. We report here about a methodological approach based on analysis of cytokines in reproductive tissues of vertebrates using different reproductive strategies i.e., placental and aplacental viviparity and oviparity. Most of the studies focused on Interleukin-1 (IL-1), an evolutionarily conserved cytokine with many roles in mammalian reproduction, particularly in uterine receptivity and blastocyst implantation. The presence of IL-1, mainly IL-1β and of its functional membrane receptor IL-1 receptor type I (IL-1R tI) in reproductive tissues of oviparous and viviparous species suggests that this cytokine is a fundamental mediator of maternal-fetal immunotolerance.