Analysis of Chicken Mucosal Immune Response toEimeria tenellaandEimeria maximaInfection by Quantitative Reverse Transcription-PCR

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Abstract
The recent cloning of chicken genes coding for interleukins, chemokines, and other proteins involved in immune regulation and inflammation allowed us to analyze their expression during infection withEimeria. The expression levels of different genes in jejunal and cecal RNA extracts isolated from uninfected chickens and chickens infected withEimeria maximaorE. tenellawere measured using a precise quantitative reverse transcription-PCR technique. Seven days afterE. tenellainfection, expression of the proinflammatory cytokine interleukin-1β (IL-1β) mRNA was increased 80-fold. Among the chemokines analyzed, the CC chemokines K203 (200-fold) and macrophage inflammatory factor 1β (MIP-1β) (80-fold) were strongly upregulated in the infected ceca, but the CXC chemokines IL-8 and K60 were not. However, the CXC chemokines were expressed at very high levels in uninfected cecal extracts. The levels of gamma interferon (IFN-γ) (300-fold), inducible nitric oxide synthase (iNOS) (200-fold), and myelomonocytic growth factor (MGF) (50-fold) were also highly upregulated during infection withE. tenella, whereas cyclooxygenase 2 showed a more modest (13-fold) increase. The genes upregulated duringE. tenellainfection were generally also upregulated duringE. maximainfection but at a lower magnitude except for those encoding MIP-1β and MGF. For these two cytokines, no significant change in expression levels was observed afterE. maximainfection. CD3+intraepithelial lymphocytes may participate in the IFN-γ upregulation observed after infection, since both recruitment and upregulation of the IFN-γ mRNA level were observed in the infected jejunal mucosa. Moreover, in the chicken macrophage cell line HD-11, CC chemokines, MGF, IL-1β, and iNOS were inducible by IFN-γ, suggesting that macrophages may be one of the cell populations involved in the upregulation of these cytokines observed in vivo during infection withEimeria.