Effects of intrauterine infusion of Trueperella pyogenes on endometrial mRNA expression of proinflammatory cytokines and luteolytic cascade genes and their association with luteal life span in dairy cows

Objectives were to determine the effects of intrauterine infusion (IUI) of Trueperella pyogenes on endometrial expression of proinflammatory cytokines and luteal life span. Holstein cows (n = 32) were allocated randomly, in two replicates (15 then 17 cows), to receive one of three treatments on Day 5 of the estrous cycle: TP (n = 13), IUI containing 10⁹ colony-forming units/mL of T pyogenes; tumor necrosis factor (TNF; n = 9), IUI containing 1 μg of TNFα; and control (n = 10), IUI of saline solution. Five cows per treatment had uterine biopsies collected at 6, 12, and 24 hours after treatment to evaluate the endometrial messenger RNA expression of TNFα (TNF), interleukin-1β (IL1B), IL6, IL8, prostaglandin E synthase (PGES), prostaglandin F synthase (PGFS), and oxytocin receptor (OXR), and histologic evidence of inflammation. Messenger RNA expression was measured using quantitative reverse transcription polymerase chain reaction. The remaining cows had ovaries scanned and blood collected for progesterone evaluation; however, only seven, four, and three cows in the TP, TNF, and control groups were used for comparison in replicate 2. The GLIMMIX procedure of SAS was used for statistical analysis. All TP and TNF cows had moderate to severe endometrial inflammation, whereas only one control had mild inflammation. Premature luteolysis occurred in three, one, and zero cows in the TP, TNF and control groups, respectively. Delayed luteolysis occurred in one TP and one TNF cow. Interleukin-1β expression was greater in the TP cows than in the TNF cows at 24 hours after IUI. Moreover, IL6 expression tended to be greater for the TP cows than for the control cows at 12 hours after IUI. Interleukin 8 expression was greater in the TP cows than in the control and TNF cows at 24 hours after IUI. Oxytocin receptor expression tended to be greater for the TP cows and was greater for the TNF cows than for the control cows at 12 hours. The messenger RNA expressions of TNF, PGES, and PGFS were not affected by treatment, time, or their interaction. In conclusion, IUI of T pyogenes or TNFα led to histologic evidence of inflammation and early luteolysis in some cows, which may have been caused by increased endometrial expression of proinflammatory cytokines (i.e., IL1B, IL6), chemokines (i.e., IL8), and luteolytic cascade factors (i.e., OXR).