Abstract
In the swine industry, Lawsonia intracellularis is one of the main enteric pathogens; it causes acute intestinal hemorrhage (proliferative hemorrhagic enteropathy) in naïve adult pigs and a wasting disease (proliferative enteropathy) in growing pigs. Among many kinds of cytokines, interferon-γ (IFN-γ) has previously been reported to play a significant role in limiting intracellular infection and increasing cellular proliferation associated with L. intracellularis. However, the levels of various circulating inflammatory cytokines, including IFN-γ, in animals infected with L. intracellularisis is still an area of considerable interest for understanding immunity against this bacterium. In addition, there has been no information on cytokine response in animals infected with any L. intracellularis isolate of South Korean origin or Asian origin. To determine the relationship between the changes in the systemic inflammatory cytokine response in the peripheral blood of the host after L. intracellularis infection, we measured the levels of some pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IFN-γ), anti-inflammatory cytokines (IL-4, IL-10, and transforming growth factor-β (TGF-β)), and a chemokine (IL-8) in pigs infected with L. intracellularis isolated from South Korea. This study demonstrated that a L. intracellularis isolate of South Korean origin induced cytokine (TNF-α, IL-6, and IFN-γ) responses in infected animals within 15 days post-infection although the circulating levels of IL-4, IL-10, IL-8 and TGF-β were induced relatively late.