RESUMO
The objectives of the current experiment were to investigate the effects of intrauterine treatment of cows with purulent vaginal discharge (PVD) using lipopolysaccharide (LPS) from Escherichia coli on uterine mRNA expression of genes related to inflammatory responses, peripheral polymorphonuclear leukocyte (PMN) function, hematological parameters, and blood concentrations of cortisol, haptoglobin, and progesterone (P4). Jersey cows (n = 3,084) were examined for PVD at 35 ± 6 d postpartum using the Metricheck device (Simcro, Hamilton, New Zealand). At examination, 310 cows had PVD (10.1%), but to ensure proper collection and processing of samples, 267 cows were used in this experiment. Cows were balanced for lactation number, body condition score, and milk yield, and randomly assigned to the control treatment [intrauterine infusion of 20 mL of phosphate-buffered saline (PBS); n = 87] or to receive intrauterine infusion of 20 mL of PBS containing 150 µg (LPS150; n = 91) or 300 µg (LPS300; n = 89) of E. coli LPS. Uteri were biopsied in a subgroup of cows at 6 h after infusion and in another subgroup of cows at 24 h after infusion. Peripheral PMN expression of adhesion molecules (L-selectin and MAC-1) and phagocytosis and oxidative burst were evaluated at 0, 2, and 6 h after infusion. Blood sampled 0, 2, 6, 24, 48, and 168 h after infusion was used for complete hemogram and to determine concentrations of cortisol, haptoglobin, and P4. Treatment did not affect uterine mRNA expression of adhesion molecules [endothelial leukocyte adhesion molecule (E-selectin), intracellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1)], cytokines (tumor necrosis factor-α, IL-1ß, IL-6, IL-8, and IL-10), and toll-like receptor-4. Treatment did not affect PMN expression of L-selectin, but intensity of expression of MAC-1 was higher for LPS150 cows than PBS cows, and tended to be higher in LPS150 than LPS300 cows. Furthermore, a greater percentage of PMN from LPS300 cows were positive for phagocytosis and oxidative burst compared with PBS and LPS150 cows. No effects were observed of treatment on hematological parameters and concentrations of cortisol, haptoglobin, and P4. These observations suggest that intrauterine infusion of E. coli LPS moderately stimulates peripheral PMN function, but further research is needed to better understand the immunomodulatory effects of LPS in the uterus of cows with PVD.