Peroxisome proliferator-activated receptor-γ-mediated polarization of macrophages in Neospora caninum infection

- The expressions of CD206, IL-10 and Arg-1 were significantly increased at 2, 4 and 8 weeks of Neospora caninum infection in mouse peritoneal macrophages.
- The expressions of CD206, IL-10 and Arg-1 (P < 0.01) of the M2 marks were increased by activating PPAR-γ in RGZ and Neospora caninum groups.
- Macrophages differentiated into M2 at the late stage of N. caninum infection through mediating PPARγ/NF-κB signaling pathway.

BackgroundNeospora caninum is an apicomplexan parasite closely related Toxoplasma gondii, which causes neurological disease and abortion in multiple animal species. Macrophage polarization plays an important role in host immune responses to parasites infection, such as Toxoplasma gondii, Leishmania, Trypanosoma cruzi. However, the dynamics of macrophage polarization, as well as the possible mechanism that regulate macrophage polarization, during N. caninum infection remains unclear.MethodsThe M1 and M2-phenotypic markers of peritoneal macrophages from mice infected with tachyzoites of Nc-1 were analyzed by flow cytometry (FCM) analysis. Then J774A.1 cells were respectively treated with GW9662 and RGZ, and stimulated by tachyzoites of Nc-1. M1 and M2-phenotypic markers were determined by FCM and ELISA. And the activations of PPAR-γ and NF-κB were determined by Western blotting.ResultsIn this study, our data showed that macrophages were preferentially differentiated into the M1 type during the acute stage of N. caninum infection, while the level of M2 macrophages significantly increased during the chronic stage of infection. In vitro study, compared with the GW9662 group and RGZ group, N. caninum can promote M2-polarized phenotype through up-regulate the activity of PPAR-γ and inhibting NF-κB activation.ConclusionIn conclusion, this study demonstrated that macrophages are plastic since M1 differentiated macrophages can express M2 markers with N. caninum infection through up-regulating the activity of PPAR-γ and inhibting NF-κB activation and may be providing new insights for the prevention and treatment of N. caninum infection.

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