Submitted to: Avian Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2005
Publication Date: 4/20/2006
Citation: Swaggerty, C.L., Kaiser, P., Rothwell, L., Pevzner, I., Kogut, M.H. 2006. Heterophil cytokine mRNA profiles from genetically distinct lines of chickens with differential heterophil-mediated innate immune responses. Avian Pathology. 35:102-108. Interpretive Summary: During the first week of life, baby chickens are likely to get infected with germs, including Salmonella which can make people sick when they eat the infected chickens. Baby chickens have blood cells called heterophils that can help them prevent these infections. Heterophils can produce and release chemicals, called cytokines, which can kill Salmonella and other germs. The objective of this research was (1) to take heterophils from different types of chickens (A and B) when they are 1, 14, and 28 days old and to look for different cytokines and (2) to take heterophils from the different types of baby chickens and treat them with Salmonella to see which type of heterophils make the largest amount of cytokines. We found that heterophils from type A chickens made the most cytokines. These experiments are important to the commercial poultry breeders because we have shown that chickens can be selected for the ability to produce large amounts of cytokines which will allow them to be more resistant to Salmonella and other germs. A resistant chicken is going to be stronger and will fight off infections better; therefore, people are less likely to get sick from eating contaminated poultry.
Technical Abstract: We have demonstrated increased in vitro heterophil functional efficiency translates to increased in vivo resistance to Salmonella enteritidis (SE) (gram-negative) and Enterococcus gallinarum (gram-positive) infections utilizing a pair of parental broiler lines, A and B. Heterophils produce cytokines and modulate acute protection against Salmonella in neonatal poultry. Therefore, we hypothesized heterophils from resistant chickens (line A) have the ability to produce an upregulated pro-inflammatory cytokine response compared to heterophils from susceptible chickens (line B). In this study, heterophils were isolated from chickens 1, 14, and 28 days post-hatch and treated with either RPMI 1640 (control) or phagocytic agonists (SE or SE opsonized with normal chicken serum or immune serum against SE) for 30 min at 39°C. Cytokine mRNA expression levels were then assessed using real-time quantitative RT-PCR. At all time points, heterophils from resistant chickens (line A) had significantly higher levels of pro-inflammatory cytokine (interleukin [IL]-6, IL-8, and IL-18) mRNA expression upon treatment with the phagocytic agonists compared to heterophils from susceptible chickens (line B). Further, heterophils from resistant chickens had significantly decreased mRNA expression levels of transforming growth factor (TGF)-beta4, an anti-inflammatory cytokine, when compared to heterophils from susceptible chickens. These data indicate there is a relationship between the cytokine mRNA expression profiles generated by heterophils in determining the overall immune competence of chickens. Therefore, heterophil functional efficiency, accompanied by evaluating the cytokines produced by heterophils, may be useful biomarkers for poultry breeders to consider when developing new immunocompetent lines of birds.