Cytokine gene expression in ileal tissues of cattle infected with Mycobacterium paratuberculosis

Cytokine gene expression in ileal tissues of cattle infected with Mycobacte rium paratuberculosis was evaluated. The effects of infection with M. parat uberculosis on cytokine production may influence immune regulation at the s ite of colonization, resulting in the chronic inflammatory state associated with the latter stages of this disease. Ileal samples were obtained at nec ropsy from noninfected control cows (n = 8) and clinically infected cows (n = 7) and processed for immunohistochemistry and in situ hybridization. Cow s infected with M. paratuberculosis were in the latter stages of disease wi th clinical signs such as weight loss, watery diarrhea, and inappetence. Am ong cytokines we studied, interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-6 , and interferon-gamma (IFN-gamma) were expressed significantly more in inf ected animals than in noninfected control animals. The expression of tumor necrosis factor-alpha (TNF-alpha), however, was not different between the t wo groups of cattle. In addition, immunohistochemical staining demonstrated that the number of resident macrophages in the ileum of infected animals w as three times greater than that of noninfected cows. In contrast to this, ileal tissues from noninfected control animals contained 1.5 times more neu trophils than the ileal tissues from cows infected with M. paratuberculosis . These data demonstrate that localized Heal cytokine production is differe nt between cows chronically infected with M. paratuberculosis and noninfect ed control cows. Published by Elsevier Science B.V.