Cytokines’ profile of the low-volume uterine lavage in mares with normal postpartum and septic metritis

Abstract

Even though metritis is one of the most common puerperal diseases in mares, there is a lack of information with regard to the condition. The aim of this study was to evaluate cytokines’ profile in uterine fluid collected with low volume lavage (LVL) from mares with normal postpartum period (PPP) (group 1; N=11) and from mares with septic metritis (group 2; N=12). Septic metritis was defined as the presence of hyperthermia (>38.5°C), depression, an enlarged and an excessive amount of variably echogenic uterine fluid. Mares were treated with oxytetracycline IV q12 h for 5 days, high volume uterine lavage with saline q12 h until necessary. In group 1, LVL was performed 36-48 hours after parturition (T1) and then after 2 days (T2). In group 2, LVL was performed when evidence of septic metritis appeared and then after 2 days of treatment. The samples were centrifuged, the supernatant was removed and stored at -80°C until analysis. Cytokines were measured simultaneously, using Equine Cytokine/Chemokine Panel (Merck-Millipore), based on xMAP technology. Analyzed cytokines were monocyte chemoattractant protein-1 (MCP-1), fibroblast growth factor-2 (FGF-2), granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (INF)-γ, tumor necrosis factor (TNF)-α, interleukins (IL)-1β, 1α, 2, 4, 5, 6, 8, 10, 13, 18. Data are given as median in pg/mL. Differences between groups were analyzed by Mann-Whitney test and between sample times by Wilcoxontest. In group 2, the concentration of most cytokines was larger than in group 1: IL-6 (2256.3 vs 188.2; p<0.01), IL-8 (94.8 vs 72.1; p<0.05), IL-1β (13738.7 vs 16.5; p<0.01), TNF-α (393.2 vs 0.4; p<0.05), INF-γ (224.5 vs 31.6; p<0.05), IL-10 (39.5 vs 7.9; p<0.05). The concentrations of IL-18, IL-13, and FGF-2 did not differ between groups, while IL-1α, 2, 4, 5, MCP-1 and GM-CSF were not detectable. In group 1 there was an increase (p<0.05) in IL-10, IL-5 and IL-18, while in group 2 there was no difference between T1 and T2. All mares with septic metritis recovered well and without any complications. Results suggest that, although an inflammatory response is already present in mares with normal PPP to ensure a proper endometrial regeneration and uterine involution, it is stronger in mares with septic metritis. In both groups, a high percentage (>60%) of neutrophils was detected, suggesting that in physiologic uterine involution, an inflammatory response is required. In agreement with findings from cattle, more neutrophils than monocytes and macrophages are recruited. An intense inflammatory response persists for at least 4 days. It should be noted that metritis was treated without any empirical use of intrauterine antibiotics as suggested by the WHO.