Manipulated plasma insulin, glucose, and BHBA affect immune factors in somatic cells in milk with and without intramammary LPS challenge in dairy cows

Wednesday, July 23, 2014
Exhibit Hall AB (Kansas City Convention Center)
Mousa Zarrin , Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
Rupert M. Bruckmaier , Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
Olga Wellnitz , Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
Abstract Text:

Changes of plasma hormones and metabolites affect mammary immunity during onset of lactation. Somatic cells are important for the initial udder defense and they are additionally recruited into milk during the immune response. This study aimed to investigate effects of long term (56 h) elevated insulin at simultaneous hypoglycemia or euglycemia, and elevated beta-hydroxybutyrate (BHBA) concentrations, and additional intramammary LPS challenge on mRNA abundance of immune factors in somatic cells in milk. Animals were subjected to four intravenous treatment groups: an insulin infusion (HypoG, n=5) to decrease plasma glucose concentration to 2.5 ± 0.1 mmol/L, a hyperinsulinemic euglycemic clamp to maintain plasma glucose concentration at pre-infusion level (EuG, n=6), a BHBA infusion (HyperB, n= 5), and a 0.9 % NaCl infusion (Control, n=8). Two udder quarters were challenged with 200 µg E.coli LPS at 48 h of infusions. Cells were extracted from milk of control and treated quarters obtained before, after 48 h, and at the end of infusion with a quarter milking device. The mRNA abundances of immune factors were measured by RT-qPCR. Changes of mRNA abundance between before and after 48 h of infusions, and before and after LPS challenge were evaluated by analysis of variance with treatments as fixed effect. In HypoG mRNA abundance of interleukin (IL)-1beta and RANTES (regulated on activation, normal T cell expressed and secreted) decreased (P<0.05) during 48 h. In HyperB the mRNA abundance of IL-1beta, IL-8, and RANTES tended to increase (P<0.1) during 48 h. Intramammary LPS challenge up-regulated mRNA abundance of IL-1b, IL-8, and nuclear factor kappa-light-chain-enhancer of activated B cells after 8 h in all treatment groups (P<0.05), and tumor necrosis factor-alpha in HypoG (P<0.05). The mRNA abundance of IL-1beta and IL-8 was up-regulated in HypoG (P<0.05), and IL-1beta, IL-8, and RANTES was down-regulated in control quarters of HyperB (P<0.05) 8 h after LPS challenge. Results demonstrate that intravenous insulin infusion down-regulates the expression of immune factors in somatic cells in milk during hypoglycemia, whereas induced hyperketonemia seems to up-regulate some of these factors during 48 h. It can be speculated that the down-regulation of immune factors in HypoG is related to a lack of energy (glucose) for the immune system, while BHBA is an alternative energy source for the immune system during immune response. Up-regulation of immune factors after LPS challenge was predictable, whereas mechanisms of down-regulation in control quarters after LPS challenge are unclear.

Keywords: immunity, metabolite,LPS