A comparison of the uterine proteome of mares in oestrus and dioestrus

Abstract

Contents Proteomic analysis of mare uterine flush fluid provides a minimally invasive technique for studying protein changes associated with the oestrous cycle. The aim of this study was to identify differentially abundant proteins in the uterine flush fluid of mares in oestrus and dioestrus. In this study, uterine flush fluid samples were collected from eight reproductively healthy mares in either oestrus (n = 5) or dioestrus (n = 3). Proteomic analysis was performed using liquid chromatography‐tandem mass spectrometry. Of 172 proteins identified, six proteins (immunoglobulin lambda‐like polypeptide 1, haemoglobin subunit alpha, alpha‐1B‐glycoprotein, serotransferrin, apolipoprotein A‐1, and haemoglobin subunit beta) were significantly more abundant in oestrus. These proteins may contribute to the endometrial defence system through roles in inflammation, immunity or antimicrobial activity. In other species, some of these proteins have been described as immunoglobulins, negative acute phase proteins or defence agents against micro‐organisms. During dioestrus, immunoglobulin alpha‐1 chain C region‐related, complement factor I, CD 109 antigen and uterocalin, were significantly more abundant. Research in other species suggests that these four proteins contribute to the immune response through proposed immunoregulatory characteristics, complement system involvement or roles in B cell–T cell interactions. In conclusion, ten differentially abundant proteins were identified in the uterine flush fluid of mares in oestrus and dioestrus. Targeted studies on these proteins could elucidate their role in uterine defence mechanisms during the oestrous cycle in the mare.

Qualitative analysis and functional classification of the uterine proteome of mares in oestrus and dioestrus

“…Quantitative differences in the uterine flush fluid proteome of mares between oestrus and dioestrus have been reported recently (Maloney et al, 2019). Ten proteins were identified to be significantly different in abundance between the two stages.…”

“…To date, there is very little information on changes in the uterine proteome across different stages of the oestrous cycle in mares. Quantitative differences in the uterine flush fluid proteome of mares between oestrus and dioestrus have been reported recently (Maloney et al., 2019). Ten proteins were identified to be significantly different in abundance between the two stages.…”

“…All procedures were approved by the Animal Care Committee, University of Guelph. The selection of healthy mares, their classification into oestrus and dioestrus, and the collection and processing of uterine flush fluid samples for proteomic analysis have been described previously in detail (Maloney et al., 2019). Briefly, eight healthy light breed mares (age range: 3–8 years) from the research herd at the University of Guelph were enrolled in the study.…”

“…Dioestrus was defined as a lack of uterine oedema, the presence of uterine tone and a corpus luteum (CL) visually identified by ultrasound or a serum progesterone concentration ≥ 6 nmol/L (≥2 ng/ml). Software Inc., Portland, OR) using the criteria described previously (Maloney et al, 2019). Proteins that were exclusively detected in oestrus or dioestrus or those common to both stages were identified using the Venn diagram feature available in the Scaffold software.…”

Sperm Proteome after Interaction with Reproductive Fluids in Porcine: From the Ejaculation to the Fertilization Site

“…Within the female reproductive tract, sperm flow through the uterine and oviductal environments, which themselves are key elements to the selection of the best spermatozoon for fertilization [ 29 , 30 , 31 ]. During the estrus cycle, changes in the proteome of the uterine and oviductal environment occur [ 32 , 33 , 34 ] and it is known that, within the uterus, some proteins, such as spermadhesin AWN, mucins, and complement cascade proteins, interact with gametes [ 32 ]. Once in the uterus, spermatozoa are in contact with the uterine fluid (UF), a fluid that contains ions, nutrients, hormones, growth factors, and proteins, as previously described in humans [ 29 , 35 ] and pigs [ 36 , 37 ].…”