|Rosa, G J M|
|Smith, Timothy - Tim|
Submitted to: Joint Abstracts of the American Dairy Science and Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 2/21/2005
Publication Date: 7/1/2005
Citation: Burton, J.L., Madsen, S.A., Chang, L.C., Weber, P.S., Coussens, P.M., Rosa, G., Matukumalli, L.K., Sonstegard, T.S., Smith, T.P. 2005. Immunogenomics and the transition dairy cow: physiological insights and future possibilities for improving animal health. ADSA/ASAS Joint Meeting, Cincinnati, OH, Abstract 17
Technical Abstract: Neutrophils are sensitive biomarkers of an animal's physiological status and comprise the main source of immune defense against bacteria that cause mastitis in postpartum dairy cows. Neutrophils become defective in some anti-bacterial activities as parturition approaches, but little is known about the genes or proteins responsible for these defects. This lack of knowledge impedes our ability to make improvements in cow health. Development of functional genomics tools for cattle provided the opportunity to rapidly investigate how the expression of thousands of genes in bovine neutrophils were affected by parturition. In our recent immunogenomics studies we used BOTL cDNA microarrays (see http://www.nbfgc.msu.edu) to examine gene expression in neutrophils collected from transition cows. Of 302 genes that we identified as either turned on or shut off in neutrophils around parturition, we showed that genes encoding proteins in 3 key functional categories were responsive to glucocorticoid and G-CSF, two blood factors induced during parturition. Additional phenotyping of cells subjected directly to these blood factors painted a picture of neutrophil physiology not previously recognized, showing that the cells' life span was dramatically extended and potent tissue degrading and phagocytic activities were induced at the expense of anti-bacterial capacity. Biomedical literature points to tissue degrading and phagocytic activities of neutrophils as critical for successful parturition and uterine involution in humans, and our results extend this by showing that parturient steroids and cytokines reprogram neutrophils so they can take part in parturition, perhaps at the expense of mammary defense. Because we now know the actual molecules involved in these important neutrophil phenotypic changes, our next steps are to: (1) identify which molecules are suitable drug targets for mastitis prevention; (2) test hormone/cytokine regimes as strategies for timed parturition; and (3) identify useful gene polymorphisms to aid genetic selection decisions for improved calving behavior and mammary health.