Comparative studies of macrophage-biased responses in mice to infection with Toxoplasma gondii ToxoDB #9 strains of different virulence isolated from ChinaReportar como inadecuado

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Parasites and Vectors

, 6:308

First Online: 26 October 2013Received: 24 September 2013Accepted: 22 October 2013


BackgroundDifferent from three clonal lineages of Toxoplasma gondii in North America and Europe, the genotype China 1 is predominantly prevalent in China. However, there are different virulent isolates within China 1, such as virulent TgCtwh3 and avirulent TgCtwh6, and little is known about differences in macrophage activation between them. The objective of this study focused on cytokine production, phenotype and markers of activated macrophages, and correlated signaling pathway induced by the two isolates.

MethodsAdherent peritoneal macrophages termed Wh3-Mφ and Wh6-Mφ, respectively harvested from infected mice were cultured for detection of Nitric Oxide and arginase activity, and activated markers on Wh3-Mφ-Wh6-Mφ were determined by flow cytometry. In in vitro experiments, the levels of IL-12p40 and TNF-α were measured using ELISA kits, and mRNA expressions of IL-12p40, TNF-α, iNOS, Arg-1 and Ym1 were assayed by real-time PCR. To confirm the activation state of NF-kB p65 in infected cells stained by IF, protein levels of iNOS, Arg-1, Ym1, nuclear NF-κB p65, and phosphorylation of STAT6-STAT3-IκBα were evaluated by Western Blotting. A one-way ANOVA test was used to compare differences among multiple groups.

ResultsThe result revealed that contrary to the virulent TgCtwh3, the less virulent TgCtwh6 isolate induced a significant increase in IL-12p40 and TNF-α. Although both isolates down-regulated CD80, CD86 and MHCII molecule expression on macrophages, TgCtwh3 promoted up-regulation of PD-L2 and CD206. Wh6-Mφ generated a high level of NO whereas Wh3-Mφ up-regulated Ym1 and arginase expression at transcriptional and protein levels. In terms of signaling pathway, TgCtwh3 induced phospho-STAT6, conversely, TgCtWh6 led to NF-κB p65 activation.

ConclusionsThe virulent TgCtwh3 isolate induced macrophages to polarize toward alternatively activated cells with STAT6 phosphorylation, whereas the less virulent TgCtwh6 elicited the development of classically activated macrophages with nuclear translocation of NF-κB p65. This discrepancy suggests that it is necessary to thoroughly analyze the genotype of TgCtwh3 and TgCtwh6, and to further study other effector molecules that contribute to the macrophage polarization in T. gondii.

KeywordsToxoplasma gondii Genotyping Macrophages Macrophage activation Signaling pathway AbbreviationsMφMacrophage

M1Classically activated macrophage

M2Alternatively activated macrophage

BMMφBone marrow-derived macrophage

PECsPeritoneal exudate cells

iNOSInducible nitric oxide synthase

PD-LProgrammed death ligand

GRADense granule antigen

NONitric oxide

MFIMean fluorescence intensity

ROPRhoptry protein

STATSignal transducer and activator of transcription.

Electronic supplementary materialThe online version of this article doi:10.1186-1756-3305-6-308 contains supplementary material, which is available to authorized users.

Ai-Mei Zhang, Qian Shen contributed equally to this work.

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Autor: Ai-Mei Zhang - Qian Shen - Min Li - Xiu-Cai Xu - He Chen - Yi-Hong Cai - Qing-Li Luo - De-Yong Chu - Li Yu - Jian Du - Z


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