Submitted to: Developmental and Comparative Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 13, 2006
Publication Date: April 20, 2007
Citation: Genovese, K.J., He, H., Lowry, V.K., Kogut, M.H. 2007. Comparison of MAP and tyrosine kinase signaling in heterophils from commercial and wild-type turkeys. Developmental and Comparative Immunology. 31:927-933. Interpretive Summary: We have previously described differences in the immune systems between commercial turkeys and wild-type turkeys. The current study describes some of the factors that result in the commercial line’s decreased immune functions as compared to wild-type turkeys. Specifically, the current study describes the signals that go on inside the cell when a white blood cell encounters a foreign invader, such as a bacteria. We show that cells from commercial turkey lines have deficiencies in their cell signaling response to foreign invaders as compared to cells from wild-type turkeys. These deficiencies aid in explaining why commercial turkeys are more susceptible to diseases and colonization with food borne pathogens as compared to their wild-type counterparts.
Technical Abstract: Protein tyrosine and mitogen activated kinases are crucial mediators of the host innate immune response, conferring signals from surface receptors on the host cell to the nucleus of the cell where gene expression occurs. Heterophils were isolated from wild-type Rio Grande turkeys and a commercial line of turkeys (Line A) on days 4 and 7 post-hatch. Heterophils were stimulated for 1 hr with Salmonella enteritidis (SE) or opsonized SE (OPSE). After stimulation, cells were lysed and cell lysates were tested for mitogen-activated protein kinase (MAPK) activity. Specifically, phosphorylation of extracellular signal-regulated protein kinase (ERK1/2) and p38 MAPK phosphorylation were assayed using commercially available ELISA kits. In addition, total protein tyrosine kinase (PTK) activity was assayed. On both day 4 and day 7 post-hatch, heterophils from Rio Grande turkeys had significantly higher levels of ERK 1/2 and p38 MAPK kinase activity upon stimulation with either SE or OPSE (p< 0.001). Likewise, PTK values on day 4 and 7 in Rio Grande turkey heterophils was significantly higher upon stimulation with SE than with OPSE and was significantly (p<0.001) higher than the PTK levels in Line A upon SE and OPSE stimulation. The data presented here supports previous heterophil functional comparison studies wherein heterophils from Rio Grande turkeys had higher levels of oxidative burst and degranulation activities as compared to the activity observed in commercial Line A heterophils, suggesting that the regulation and control of these functions are mediated by protein tyrosine and mitogen activated kinases. Furthermore, the data suggest that selection of commercial lines of turkeys for larger, heavier bodies, and faster growth may be associated with subsequent selection for decreased innate immune functions related to intracellular signaling mechanisms and possibly a subsequent increase in susceptibility to disease.