Peroral Infectivity ofToxoplasma gondiiin Bile and Feces of Interferon-γ Knockout Mice

Motile invaded neutrophils in the small intestine of Toxoplasma gondii-infected mice reveal a potential mechanism for parasite spread

Toxoplasma gondii infection occurs through the oral route, but we lack important information about how the parasite interacts with the host immune system in the intestine. We used two-photon laser-scanning microscopy in conjunction with a mouse model of oral T. gondii infection to address this issue. T. gondii established discrete foci of infection in the small intestine, eliciting the recruitment and transepithelial migration of neutrophils and inflammatory monocytes. Neutrophils accounted for a high proportion of actively invaded cells, and we provide evidence for a role for transmigrating neutrophils and other immune cells in the spread of T. gondii infection through the lumen of the intestine. Our data identify neutrophils as motile reservoirs of T. gondii infection and suggest a surprising retrograde pathway for parasite spread in the intestine.

Azithromycin and spiramycin induce anti-inflammatory response in human trophoblastic (BeWo) cells infected by Toxoplasma gondii but are able to control infection

Toxoplasma gondii is an important pathogen which may cause fetal infection if primary infection. Our previous studies have used human choriocarcinoma trophoblastic cells (BeWo cell line) as experimental model of T. gondii infection involving placental microenvironment. This study aimed to examine the effects of azithromycin and spiramycin against T. gondii infection in BeWo cells. Cells were treated with different concentrations of the macrolide antibiotics and analyzed first for cell viability using thiazolyl blue tetrazole (MTT) assay. As cell viability was significantly decreased with drug concentrations higher than 400 μg/mL, the concentration range used in further experiments was from 50 to 400 μg/mL. The number of infected cells and intracellular replication of T. gondii decreased after treatment with each drug. The infection induced up-regulation of the macrophage migration inhibitory factor (MIF), which was also enhanced in infected cells after treatment with azithromycin, but not with spiramycin. Analysis of the cytokine profile showed increase TNF-α, IL-10 and IL-4 production, but decreased IFN-γ levels, were detected in infected cells and treated with each drug. In conclusion, treatment of human trophoblastic BeWo cells with with azithromycin or spiramycin is able to control the infection and replication of T. gondii. In addition, treatment with these macrolides, especially with azityromycin induces an anti-inflammatory response and high MIF production, which can be important for the establishment and maintenance of a viable pregnancy during T. gondii infection.

Maternal–fetal transmission of Toxoplasma gondii in interferon-γ deficient pregnant mice

Toxoplasma gondii infection is generally asymptomatic in immunocompetent persons but can be life-threatening in immunocompromised persons and for fetuses in the case of maternal-fetal transmission. The effect of interferon (IFN)-gamma, which plays a crucial role in the protective immunity against T. gondii infection, on maternal-fetal transmission of T. gondii was analyzed by quantitative competitive polymerase chain reaction targeting T. gondii-specific SAG1 gene. T. gondii loads were obvious in uterus and placenta of wild type (WT) C57BL/6 (B6, susceptible strain) but not BALB/c (resistant strain) pregnant mice. Higher levels of T. gondii were detected in uterus and placenta of IFN-gamma knock-out (GKO) B6 and BALB/c than in those of WT mice. Furthermore, T. gondii was detected in fetus of GKO B6 but not GKO BALB/c, WT B6, or WT BALB/c mice. Thus, not only IFN-gamma but also genetic susceptibility to T. gondii infection was important for the protective immunity of maternal-fetal transmission of T. gondii to fetus via placenta. T. gondii-infected WT mice displayed a low delivery rate with high IFN-gamma production, whereas infected GKO mice did not. Additionally, mean body weight of neonates from T. gondii-infected GKO BALB/c pregnant mice was significantly lower than that of unaborted neonates from WT BALB/c pregnant mice, suggesting the effects of T. gondii infection on intrauterine growth retardation of fetus in pregnant GKO mice.