Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: March 21, 2012
Publication Date: July 15, 2012
Citation: Elsasser, T.H., Capuco, A.V., Rinaldi, M., Kahl, S. 2012. Changes in biomarkers of the nitrooxidative stress response and Prolactin (PRL) signal transduction elements (STE) to E. coli infection (INFec) in the mammary gland (MG). Journal of Animal Science. 90(Suppl. 3):9. Technical Abstract: Key features of the MG response to INFec include (a) the cellular generation of reactive oxynitrogen molecules (Roxn) derived from nitric oxide (NO) and superoxide anion (SO) and (b) loss of responsiveness to lactogenic hormone signaling. Of significance to the MG is the damage done to mammary epithelial cells (MEC) by Roxn generated by MEC and neutrophils (PMN). The aim of this study was to determine the time course of production and cellular localization of biomarkers of the Roxn pathway and to quantify changes in PRL receptor (PRLr)-janus kinase-2 (JAK-2) signaling. As applied across the four quarters of the MG, five multiparous lactating Holstein cows received treatments consisting of PBS or 400 cfu E. coli administered 12 or 24 h prior to euthanasia. MG tissues (lobulo-alveolar) were prepared for immunohistochemical (IHC) localization of biomarker antigens. IHC biomarkers for the Roxn pathway elements consisted of 3’-nitrotyrosine (3-NT, cellular protein nitration) as well as inducible (i) and constitutive (e) isoforms of nitric oxide synthase (NOS, NO generation), and xanthine oxidase (XO, SO-generating capacity). PRL STE markers were PRLr, JAK-2, and nitrated JAK-2 (ntJAK, Roxn-inactivated JAK-2). Antigenic markers were quantified by image analysis of digitally-captured micrographs. Mean pixel densities of all antigenic determinants were affected by time and/or cell type (P<0.02). Infiltrating PMN were present only at 24 h. The 3-NT increase peaked in MEC (4.6-fold) at 12h and in PMN (3.7-fold) at 24 h. Both iNOS and eNOS increased in MEC at 12 and 24 h but only iNOS was increased in PMN at 24 h. XO increased 118 % in MEC at 12 h (P<0.04) but normalized by 24h. PRLr was decreased by 29 (P<0.03) and 54 % (P<0.01) in MEC at 12 and 24 h, respectively. JAK-2 was decreased 84 % (P<0.02) at 24 h, respectively. ntJAK was increased 22- (P<0.005) and 4-fold (P<0.05) at 12 and 24 h, respectively. The data indicate that changes in these measured cellular responses to INFec occur in the MG as a function of time and cell type.