Specialized pro-resolving mediators (SPM) as markers of postpartum uterine health in dairy cows

Catarina Anastácio^1,2; Gonçalo Pereira^1,2; Elisabete Silva^1,2; Vincent Baillif³, Laurie Saias³, Marc Dubourdeau³, Joëlle Dupont⁴, Patrice Humblot⁵, Luís Lopes da Costa ^1,2*

1. CIISA- Centro de Investigação Interdisciplinar em Sanidade Animal, Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisbon, Portugal
2. Associate Laboratory for Animal and Veterinary Science (AL4AnimalS), Lisbon, Portugal
3. Ambiotis, Toulouse, France
4. Physiologie de la Reproduction et des Comportements, INRA-CNRS-Université Tours-Haras Nationaux UMR6175, Nouzilly, France
5. Department of Clinical Sciences, Swedish University of Agricultural Sciences, SLU, Uppsala, Sweden

Abstract Text:

Specialized pro-resolving molecules (SPM) emerged as mediators of chronic inflammatory resolution in Humans and lab species, but their role in the bovine remains unknown. Postpartum endometritis frequently evolve to a subclinical persistent form, for which current diagnosis is invasive and no therapy is effective. This study characterized the profiles of plasma and uterine fluid SPM in post-partum dairy cows, and evaluated their role as markers of subclinical endometritis (SCE).

Based on uterine cytology at 21 and 42 days post-partum (DPP), cows (n=31) were allocated to groups Healthy (H, n=19, PMN < 18% at 21 DPP and PMN < 5% at 42 DPP), Recovered SCE (SCE-R, n=7; PMN≥18% at 21 DPP and PMN < 5% at 42 DPP), and Persistent SCE (SCE-P, n=5; PMN≥18% at 21 DPP and PMN≥5% at 42 DPP). Blood samples were collected at 2, 10, 21, 30 and 42 DPP and a low volume uterine flush of the previously pregnant uterine horn was taken at 21 DPP for SPM analysis by LC-MS/MS. The panel of SPM included omega-6 ARA (C20:4) derived lipoxin A4 (LXA4) and LXB4 and its precursors (15-HETE, 12-HETE and 5-HETE), omega-3 DHA (C22:6) derived maresins (7(S)-MaR1, 7(R)-MaR1, MaR2) and its precursor 14-HDHA, protectins (PD1, PDX) and resolvins D series (RvD1, RvD2, RvD3, RvD4, RvD5) and its precursor 17-HDHA, and omega-3 EPA (C20:5) derived resolvins E series (RvE1, RvE2, RvE4) and its precursor 18-HEPE. Concentrations of SPM were compared between groups by one-way ANOVA.    

At 2 DPP, SCE-R cows had higher (P < 0.05) plasma concentrations of LXA4, 14-HDHA and 18-HEPE than H and SCE-P cows. At 10 DPP, SCE-P cows had higher concentrations of 5-HETE (P < 0.01), LXA4 (P < 0.05), LXB4 (P < 0.05) and 18-HEPE (P < 0.05) than H and SCE-R cows. At 21 DPP, SCE-P cows had higher concentrations of LXB4 (P < 0.05) and 14-HDHA (P < 0.01) than H and SCE-R cows. In uterine fluid at 21 DPP, SCE-R cows had higher concentrations of 14-HDHA (P < 0.05), MaR2 (P < 0.05) and RvE2 (P < 0.01) than H cows, and higher concentrations of RvE1 (P < 0.05) than SCE-P cows. Plasma concentrations of 12-HETE at 2 DPP were correlated (Spearman Correlation Coefficient) with uterine fluid concentrations at 21 DPP of LXA4 (r=0.552; P< 0.01), LXB4 (r=0.595; P< 0.001), MaR2 (r=0.508; P< 0.01), RvE2 (r=0.740; P< 0.0001) and RvE4 (r=0.881; P< 0.0001). 

This study firstly characterized the SPM plasma profiles of healthy postpartum dairy cows and their deviations in SCE cows. Results evidenced that plasma concentrations as early as 2 DPP and concentrations in uterine fluid at 21 DPP reflect the resolution or persistence of SCE thereafter. Thus, SPM emerge as potential early postpartum non-invasive diagnostic markers of SCE, and of the recover/persistence nature of inflammation.

Funded by Fundação para a Ciência e a Tecnologia (FCT) through projects PTDC/CVTCVT/6932/2020, UIDB/00276/2020 (CIISA) and LA/P/0059/2020 (AL4AnimalS). FCT funded CA (UI/BD/153069/2022).