Role of chemokines in regulating luteal and uterine functions in pregnant cows

Abstract

Pregnancy is intricately regulated by the interactions between various bioactive substances secreted by the conceptus, uterus, and corpus luteum (CL). Interferon-τ, synthesized and secreted by the conceptus, plays a central role in the interaction mechanism of maternal recognition in cows. Chemokines, chemotaxis mediators that are primarily secreted by immune cells, regulate various reproductive responses in various species. Although there are scattered reports on the potential roles of chemokines in the bovine CL and the uterus during the estrous cycle, there is little information on chemokines in these organs during pregnancy. Therefore, in this review, we discuss the possible physiological roles of chemokines in the CL and uterus of pregnant cows, focusing on our recent findings on chemokines and changes in their receptor expression in the CL and endometrium of cows at some stages of pregnancy.

Keywords: Chemokines; Corpus luteum; Cow; Pregnancy; Uterus.

Fig. 1.

Hypothetical model of the inhibition of luteolysis and maternal recognition of pregnancy by IFNT and chemokines in cows. Although this model does not consider the effects of steroids or growth factors, IFNT, CCL2, CCL8, CCL14, and CXCL10 may block COX2 or OT receptor expression in bovine endometrial cells, leading to a reduction in OT-induced PGF2α output from the cells. Furthermore, IFNT and CCL16 may stimulate antiviral activity by upregulating ISG15 and MX1 expression in the endometrium as well as immune cells at the time of maternal recognition. IFNT may stimulate both CCL8 and CXCL10 production from immune cells and the endometrium and inhibit CCL14 production from the endometrium. The effects of CCL3, CCL5, and CCL11 on bovine endometrial function are still unclear, although their receptors (CCR1 and CCR3) are expressed in endometrial epithelial cells. The CCL19 actions via its receptor (CCR7) in the endometrium and immune cells still need to be clarified. Red and blue arrows show the stimulatory and inhibitory actions of each substance, respectively. This schematic figure was modified and adapted from the original figure in [48].