Cytokine gene expression at the materno-foetal interface after experimental Neospora caninum infection of heifers at 110 days of gestation.

Neospora caninum is a major cause of abortion in cattle, but the reasons why only some animals abort remain unclear. The immunological control of the parasite in the placenta or by the foetus could be the key to determining the mechanism of abortion and/or transplacental transmission to the foetus. In this study, cytokine gene expression, analysed by real-time RT-PCR, at the maternal (caruncle) and foetal placenta (cotyledon) of heifers infected at 110 days of gestation by intravenous inoculation of N. caninum tachyzoites was compared with the responses in uninfected heifers. Animals were euthanized 3 weeks after infection. Upregulated Th1, Th2 and T-regulatory (Treg) cytokine gene expression was observed in both the maternal and the foetal placenta in the infected group. In the caruncle of infected animals, the main changes included upregulation of IFN-γ, IL-12p40, IL-6 and IL-10. In the cotyledon, the main changes included upregulation of IFN-γ and downregulation of TGF-β, being the later the only cytokine downregulated in the infected group. The observed cytokine expression pattern was associated with alive but transplacentally infected foetuses, suggesting that such cytokine pattern is beneficial to foetal survival, but could have a role in the transplacental transmission of the parasite.