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

Abstract

Uterine infection and endometritis cause infertility and economic losses in the cattle industry. The innate immune response of the endometrium is critical in the elimination of pathogenic organisms that invade the uterus in postpartum cows. This study investigated the response of bovine endometrium to synthetic intracellular ligands which activate innate immunity by stimulating similar receptors to those used to recognise the presence of some viruses. Mixed primary epithelial and stromal cell cultures were treated with 5 μg/ml of CL097 (a TLR7/8 ligand) or 2 μg/ml of poly(dA:dT) (a DNA analogue) for either 6 h or 24 h. Cellular responses were assessed by the mRNA expression of 18 immune-related genes and 3 endogenous reference genes by conventional PCR followed by qRT-PCR from four replicate experiments. Bovine endometrial cells expressed the cytosolic pattern recognition receptors (PRRs) DDX58 (RIG-I), IFIH1 (MDA5) and LRRFIP1 which act as intracellular nucleic acid sensors. Neither ligand altered the expression of the extra-cytosolic pattern recognition receptors (PRRs) TLR3, TLR4, TLR7 or TLR8 whereas poly(dA:dT) treatment increased the expression of IFIH1 and DDX58.

Mechanisms linking bovine viral diarrhea virus (BVDV) infection with infertility in cattle

“…During early pregnancy, genes of the innate immune response may function to protect the uterus against infection (Walker et al ., 2010). Endometrial epithelial cells and stromal cells express the extra-cytosolic receptors, TLRs 1–10 (Davies et al ., 2008; Swangchan-Uthai et al ., 2012; Oguejiofor et al ., 2015 b , 2017 a ), as well as the cytosolic receptors: IFN-induced with helicase C domain 1 ( IFIH1 also known as MDA5), DExD/H-box helicase 58 ( DDX58 , also known as RIG-I), and leucine-rich repeat (in FLII) interacting protein 1, LRRFIP1 (Cheng et al ., 2017; Oguejiofor et al ., 2015 b , 2017 a ). These receptors are known to detect extracellular and intracellular pathogen-associated molecular patterns (PAMPs) during innate immunity (Kumar et al ., 2011).…”