The role of interleukin-17 in murine cytomegalovirus interstitial pneumonia in mice with skin transplants.

ABSTRACT

We hypothesized that the T helper (Th)17 response plays an important role in murine cytomegalovirus (MCMV) interstitial pneumonia. BALB/c mice with skin grafts from C57/BJ6 mice were intranasally inoculated with 1.0 × 10(5) PFU MCMV. Lung tissues and skin grafts were histologically evaluated and expression of interleukins (IL)-17, -6 and -8, monocyte chemotactic protein (MCP)-1 and interferon (IFN)-γ in serum and bronchoalveolar lavage (BAL) fluid, intracellular IL-4, -17, and IFN-γ, in spleen lymphocytes were analysed. The levels of IL-17 in the serum and BAL fluid were significantly higher in MCMV-infected mice versus not-infected mice (P = 0.0286 and P = 0.007, respectively) and the BAL levels of IL-17 peaked in 9 days (P = 0.001). The IL-17 level in the BAL was correlated with the grade of lung interstitial inflammation (r = 0.554, P = 0.0144). Serum IFN-γ levels were also higher after infection than that in the not-infected mice (P = 0.0286). IL-17 production increases locally and systemically during MCMV interstitial pneumonia. Neutralization of IL-17 significantly suppressed lung inflammation at day14 as assessed by histology. These findings suggest that IL-17 is important in the pathology of MCMV interstitial pneumonia.