Comparative responses of chicken macrophages to infection with Salmonella enterica serovars

Poultry products such as meat and eggs are known reservoirs for Salmonella serovars. Macrophages play an important role by limiting bacterial replication using several defense mechanisms including immune and inflammatory mediators, antibacterial proteins, reactive nitrogen and oxygen species. In this study, we evaluate transcriptional changes in Toll-like receptors, immune/inflammatory cytokines, chemokines, antibacterial factors, and nitric oxide (NO) production in HD11 chicken macrophages in response to intracellular persistence of poultry-derived Salmonella enterica Enteritidis (SE), Typhimurium (ST), and Heidelberg (SH) that were associated with human salmonellosis. Invasion of ST was higher than SE or SH; however, SH persistence in HD11 cells at 18 h post infection (hpi) was more pronounced than the other 2 serovars. In comparison to the uninfected control HD11 cells, expression of TLR5 was >2 fold higher for SE and SH which was followed by up-regulation of downstream signal transduction molecules. Significant up-regulation of antibacterial peptides, proinflammatory chemokines, cytokines, and NO production were observed in response to SE, SH, and ST at 18 hpi. These results indicate that although antibacterial factors contribute to the clearance of invading Salmonella, some of the differences in response could also be due to the different virulence properties of these serovars.