Response of bovine endometrium to interferon tau in the presence of lipopolysaccharide

We recently demonstrated that conceptus-derived interferon tau (IFNT), responsible for maternal recognition in cattle, acts on the uterus in a dose- and time-dependent manner by upregulating key interferon-stimulated genes (ISGs) in the endometrium. In high producing dairy cows, postpartum uterine infection is a major factor influencing fertility and pregnancy outcome. Lipopolysaccharide (LPS), an endotoxin of Gram-negative bacteria such as Escherichia coli, generates an altered uterine environment by inducing excessive inflammation at the maternal-conceptus interface. Thus, we aimed to investigate whether the endometrial response to IFNT is altered in the presence of LPS. Endometrial explants were isolated from uteri collected at a local abattoir from Holstein Friesian cows (n = 8) during the mid-luteal stage of the estrous cycle, and cultured in RPMI medium for 24 h in 5 % CO₂ in humidified air without (control), or with IFNT (100 ng/mL), a single Day 15 conceptus, LPS (1 μg/mL), both IFNT and LPS, or both a Day 15 conceptus and LPS. Incubation with IFNT and a Day 15 conceptus up-regulated (P < 0.05) well-known classical ISGs (ISG15, OAS1, MX1 and MX2) as well as other candidate ISGs (CMPK2, IFI35, TRIM38 and TNFSF10) and down-regulated expression of IL1B in endometrial explants. Incubation with LPS increased (P < 0.05) abundance of NFKB1 (a key transcription factor involved in inflammatory and immune response), TNFA, IL1B and IL6 (pro-inflammatory cytokines), IL10 (anti-inflammatory cytokine), IL8, CXCL1, CXCL3 and CCL2 (chemokines), and, to a lesser extent, classical ISGs in endometrial explants. However, LPS did not alter endometrial response to IFNT, irrespective of IFNT concentration (1, 10 or 100 ng/mL). Results suggest that the expression of ISGs, up-regulated by conceptus-derived IFNT, is not altered in the endometrium in the presence of LPS; however, the increased expression of inflammation-related genes induced by LPS indicate an altered endometrial immune response that may be associated with compromised pregnancy establishment or pregnancy failure.