Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 30, 2005
Publication Date: June 20, 2006
Citation: Lippolis, J.D., Peterson-Burch, B.D., Reinhardt, T.A. 2006. Differential expression analysis of proteins from neutrophils in the periparturient period and neutrophils from dexamethasone-treated dairy cows. Veterinary Immunology and Immunopathology. 111(3-4):149-164. Interpretive Summary: Infection of the udder (mastitis) is a major economic problem for the dairy industry. White blood cells are what fight infections. The time around the birth of a calf causes white blood cells to have a reduced ability to fight infection. To better understand what causes the reduced function of the white blood cells we are using a new technology called proteomics. Proteomics is the identification of proteins made in a cell. Previous protein identification techniques did so one at a time where proteomics can identify hundreds of proteins in a sample. We have identified nearly 300 proteins isolated from bovine white blood cells isolated prior to calving and at the time of calving. The relative abundance of each protein was determined to find those proteins whose expression changed during calving. We found nearly 75 proteins levels changed significantly at the time of calving. Many of the proteins identified help give the cell the energy needed to fight infections. Also, proteins for the white blood cell were identified that kill bacteria. In addition, white blood cell proteins were found that cause the cell to move from the blood to the udder when there is an infection. The next stage of this research will focus on the proteins that changed in abundance and they will be further studied to determine if they play a role in the white blood cell’s inability to fight and kill bacteria. This information will help us better understand and fight mastitis in the dairy industry.
Technical Abstract: Neutrophils play an important role in the host immune system’s defense against pathogens. It has been established that neutrophil functionality is suppressed in dairy cows at parturition. The periparturient immunosuppression seen in dairy cattle is associated with an increase in the incidence of mastitis. Using amine-reactive isobaric tagging reagents we have measured relative protein expression from normal prepartum neutrophils and neutrophils isolated during immunosuppression at parturition. We found over 40 proteins that are differentially expressed at parturition compared to prepartum. In addition, we measured relative protein expression from normal neutrophils and neutrophils obtained from cows treated with an immunosuppressive dose of dexamethasone. We found over 70 proteins are differentially expressed during dexamethasone treatment. We then compared protein expression changes in dexamethasone-induced immunosuppression to periparturient immunosuppression. A number of proteins underwent similar expression changes in both dexamethasone and periparturient immunosuppressed neutrophils. Most significantly, we found a significant number of proteins whose relative expression was not the same for these two different conditions that cause neutrophil immunosuppression. Dexamethasone and periparturient immunosuppression resulted in either opposite expression changes for some proteins or only one of the groups induced a change in expression for a specific protein while the other had no effect. The data demonstrates that there are both similarities and significant differences in neutrophil protein expression in the naturally occurring immunosuppression observed at parturition compared to dexamethasone-induced immunosuppression in the bovine neutrophil. These data also demonstrate that glucocorticoids are not the sole regulators of periparturient immunosuppression in the transition dairy cow.