Poster Presentation ESA-SRB-APEG-NZSE 2022

MULTIOMICS APPROACH TO DIFFERENTIATE PREGNANT AND NON-PREGNANT MARES: IDENTIFICATION OF EARLY PREGNANCY PLASMA BIOMARKERS (#403)

Tharangani RW Perera 1 2 , Brett Nixon 1 2 , Zamira Gibb 1 2 , Alecia R Sheridan 1 , Russell Pickford 3 , Thusi Rupasinghe 4 , Jennifer Clulow 5 , David A Skerrett-Byrne 1 2 , Aleona Swegen 1 2
  1. Priority Research Centre for Reproductive Science, School of Environmental and Life Sciences, College of Engineering, Science, and Environment, University of Newcastle, Callaghan, New South Wales, Australia
  2. Pregnancy and Reproduction Program, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia
  3. Bioanalytical Mass Spectrometry Facility, University of New South Wales, Sydney, NSW, Australia
  4. School of Bio Sciences, University of Melbourne, Parkville, Victoria, Australia
  5. School of Agriculture, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia

Diagnosis of early pregnancy in mares is an important component of equine breeding practice, as early embryo loss is relatively common and incurs substantial economic loss. This is compounded by a short breeding season, placing pressure to achieve pregnancies early. Furthermore, a precise signal or mechanism for maternal recognition of pregnancy has not yet been elucidated in horses with current detection only being possible at day 14. We have undertaken multiomic analyses to compare the blood plasma profiles of pregnant (7P) and non-pregnant (7NP) mares at day 7 post-ovulation to identify pregnancy-induced biomarkers. We conducted a proteomics study (n=264) in parallel with lipidomics and metabolomics (n=72). Using a batch mode approach, our established bioinformatical pipelines led us to identify a plasma protein profile of 234 proteins and a lipidome composed of ~700 lipid ions. Amongst these profiles we identified 14 proteins and 24 lipids that were significantly up or down-regulated between 7P and 7NP. Proteomics revealed serpinA6, immunoglobulin lambda light chain variable region, alpha 2 macroglobulin and complement C8 gamma chain to be significantly increased in 7P plasma. Immunoglobulin lambda light chain variable region is important in the immunological recognition of pregnancy and in humans altered Free Light Chains (FLC) or FLC ratios during pregnancy has been identified. Further, lipidomic analysis revealed several ceramides to be significantly increased in 7P plasma, suggesting a role for lipid-mediated signaling in early pregnancy. Moreover, pathway analysis implicated ceramides in many reproductive hormone signaling pathways, including progesterone synthesis. These novel findings support the utility of mass spectrometry driven omics platforms for pregnancy biomarker discovery and indicate that systemic physiological changes occur as early as day 7 following fertilisation in the pregnant mare. Overall, this study represents significant progress toward establishing a panel of biomarkers for the accurate detection of early pregnancy in mare.