Changes in endometrial transcription of TLR2, TLR4, and CD14 during the first-week postpartum in dairy cows with retained placenta Telma M. Martins a , Clarice S. Muniz a , Virgílio B. Andrade a , Tatiane A. Paixão b , Renato L. Santos a , Álan M. Borges a, * a Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil b Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil article info Article history: Received 6 March 2015 Received in revised form 16 December 2015 Accepted 17 December 2015 Keywords: Postpartum cows Uterine infection Innate immunity Toll-like receptors NOD-like receptors abstract Changes in the endometrial transcription of pattern recognition receptors may increase the susceptibility to postpartum uterine infections in Holstein cows with retained placenta. To test this hypothesis, nine cows with retained placenta and ten cows without retained placenta were submitted to endometrial biopsies at the first and seventh days postpartum. Cows were monitored weekly with clinical and gynecological examinations until 42 days postpartum. Samples of the uterine contents were collected weekly for aerobic bacteria isolation. All cows had endometrial transcription of Toll-like receptors (TLRs) 1/6, 2, 4, 5, and 9; nucleotide-binding oligomerization domain (NOD)-like receptors 1 and 2; and the coreceptors cluster of differentiation 14 (CD14) and myeloid differentiation protein-2 (MD- 2), as measured on the first and seventh days postpartum. Escherichia coli was the most common bacterium isolated from the uterine contents of cows with or without retained placenta until 21 days postpartum. Transcription levels of TLR2, TLR4, and CD14 in Holstein cows with retained placenta significantly decreased (P < 0.05) between the first and the seventh day postpartum. Conversely, cows without retained placenta did not have any significant changes in transcription levels between these time points. Ó 2016 Elsevier Inc. All rights reserved. 1. Introduction Postpartum uterine infections and inflammation are important causes of reproductive failure in dairy cows. Nearly all cows acquire ascending bacterial contamination of the uterus after parturition because of the opening of anatomic barriers including the vulva, vagina, and cervix [1,2]. Endometrial cells express receptors that recog- nize microbe-associated molecular patterns (MAMPs), previously known as pathogen-associated molecular patterns [3]. Once activated, these receptors trigger an inflammatory response aimed at eliminating the invading bacteria [4–6]. Innate immune responses, including inflam- mation, are modulated, along with other mechanisms through the expression and activation of Toll-like receptors (TLRs) or nucleotide-binding oligomerization domain (NOD)-like receptors, which sense MAMPs. These receptors are known as pattern recognition receptors (PRRs). Failure of the innate immune response favors the multipli- cation of potentially pathogenic bacteria in the uterus, which may lead to persistent infection and impaired fertility [7–9]. Acute and chronic postpartum uterine infections occur frequently in dairy cows, and retained placenta is a major risk factor for these diseases [10–12]. Retained placenta * Corresponding author. Tel.: þ55-31-34092259; fax: þ55-31- 34092230. E-mail address: alanmborges@ufmg.br (Á.M. Borges). Contents lists available at ScienceDirect Theriogenology journal homepage: www.theriojournal.com 0093-691X/$ – see front matter Ó 2016 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.theriogenology.2015.12.013 Theriogenology 85 (2016) 1282–1288