β-Hydroxybutyrate Effects on Bovine Caruncular Epithelial Cells: A Model for Investigating the Peri-Implantation Period Disruption in Ketotic Dairy Cows

SIMPLE SUMMARY: In high-yielding dairy cows, the successful establishment of pregnancy is of great economic importance. If a new pregnancy does not occur shortly after parturition, this can mean early culling for the animal. Due to today’s breeding, cattle show higher milk yields, but pregnancy rates continue to decline. In addition to genetic dispositions, metabolic diseases, such as ketosis, are particularly relevant here. In this in vitro study, bovine uterine cells were stimulated with the main ketone body β-Hydroxybutyrate. The influence of β-Hydroxybutyrate on uterine cell function, inflammatory state and important genes for successful implantation was investigated. These genes include cell adhesion molecules and prostaglandins. High concentrations of β-Hydroxybutyrate negatively affected cell function and induced an inflammatory response in the cells. These results provide a possible explanation for the poor reproductive performance of ketotic dairy cows. Due to the reduced cell function as well as inflammatory response, the finely regulated feto-maternal communication during early pregnancy might be disturbed. ABSTRACT: Ketosis is a metabolic disorder arising from a negative energy balance (NEB). It is characterized by high β-Hydroxybutyrate (BHBA) blood levels and associated with reduced fertility in dairy cows. To investigate the impact of BHBA on bovine caruncular epithelial cells (BCEC) in vitro, these cells were stimulated with different concentrations of BHBA. Cell metabolism and motility were examined using an MTT assay and Live-cell imaging. RT-qPCR was used to examine mRNA expressions of TNF, IL6, RELA, prostaglandin E2 synthase (PTGES2) and receptor (PTGER2) as well as integrin subunits ITGAV, ITGA6, ITGB1 and ITGB3. Stimulation with 1.8 and 2.4 mM of BHBA negatively affected cell metabolism and motility. TNF showed increased mRNA expression related to rising BHBA concentrations. IL6, RELA, ITGAV, ITGA6, ITGB1 and ITGB3 as well as PTGER2 showed no changes in mRNA expression. Stimulation with 0.6 and 1.2 mM of BHBA significantly increased the mRNA expression of PTGES2. This does not indicate a negative effect on reproductive performance because low BHBA concentrations are found in steady-state conditions. However, the results of the study show negative effects of high BHBA concentrations on the function of BCECs as well as an inflammatory response. This could negatively affect the feto-maternal communication during the peri-implantation period in ketotic dairy cows.