Salmonella Enteritidis-induced alteration of inflammatory CXCL chemokine messenger-RNA expression and histologic changes in the ceca of infected chicks.

To understand better the events in early avian host immune responses to Salmonella Enteritidis (SE), we examined messenger-RNA (mRNA) expression for eight genes: CXCLi1[K60], CXCLi2 [IL-8/CAF], interferon (IFN)-gamma, interleukin (IL)-1beta, IL-6, IL-12alpha, IL-12beta, and gallinacin (Gal)-2 in the ceca of young chicks 1 wk postinoculation with SE. Cecum tissue sections were stained and evaluated for the presence of macrophages, lymphocytes, heterophils, and apoptotic cells following SE infection. With the use of quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), SE infection was associated with a significant (P < 0.01) upregulation of cecal CXCLi1 and CXCLi2 mRNA expression. Infection with SE was also associated (P < 0.05) with increased staining for macrophages and decreased apoptosis (single-stranded DNA [ssDNA]) in cecal tissue sections when these sections were compared with those of uninfected animals. Changes in chemokine expression and cell population dynamics are a direct result of SE infection, as uninfected animals do not show these alterations. Thus, these SE-induced changes reflect the host immune response to SE in young chickens.