Activation of ERK Signaling via TLR11 Induces IL-12p40 Production in Peritoneal Macrophages Challenged by Neospora caninum .

Neospora caninum , an obligate intracellular protozoan parasite, can infect a large variety of vertebrate hosts including the most economically important cattle. Infection with N . caninum is a main cause of abortion in both dairy and beef cattle, which causes great economic losses worldwide. However, the mechanism of host cell infection by N . caninum has not been fully elucidated, especially in terms of inflammatory responses. In this study, the effect of TLR-ERK signaling pathway on the synthesis of pro-inflammatory interleukin-12p40 in mouse peritoneal macrophages (PMϕ) challenged by N . caninum was investigated. Our results suggested that N . caninum infection quickly activated MEK-ERK signaling via TLR11 in PMϕ. In addition, N . caninum infection also caused upregulated production of IL-12p40 by PMϕ, which was significantly reduced with the blockade of TLR11/MEK/ERK pathway, suggesting that this upregulation of IL-12 p40 was TLR11 and MEK-ERK-activation dependent.