Recruitment of galectin-3 during cell invasion and intracellular trafficking of Trypanosoma cruzi extracellular amastigotes.

The invasion of host cells by the intracellular protozoan Trypanosoma cruzi requires interactions with host cell molecules, and the replication of the parasite requires escape from a parasitophorous vacuole into the host cell cytosol. Galectin-3, a member of ß-galactosidase-binding lectin family, has numerous extracellular and intracellular functions. In this study, we investigated the role of galectin-3 during the invasion and intracellular trafficking of T. cruzi extracellular amastigotes (EAs). Endogenous galectin-3 from mouse peritoneal macrophages accumulated around the pathogen during cell invasion by EAs. In addition, galectin-3 accumulated around parasites after their escape from the parasitophorous vacuole. Thus, galectin-3 behaved as a novel marker of phagolysosome lysis during the infection of host cells by T. cruzi.

[Effect of Toxoplasma gondii infection on the embryonic neural stem cells in rats].

OBJECTIVE: To investigate the effect of Toxoplasma gondii infection on the proliferation, differentiation and migration of the embryonic neural stem cells (NSCs) in early pregnancy of rat. METHODS: Twelve pregnant Sprague-Dawley rats were randomly divided into control and infection groups. Rats in the infection group were each inoculated intraperitoneally with 1 x 10(5) T. gondii RH strain tachyzoites at day 1 (E1 day). Same amount of physiological saline was intraperitoneally injected for rats in control group. At E5 day, blood samples were taken from caudal vein and Giemsa staining of blood cells was performed to find T. gondii. At E9, E10 and E11 day, two rats in each group per time point were sacrificed and reverse transcription PCR (RT-PCR) was performed to detect B1 gene expression of T. gondii in amniotic fluid to confirm T. gondii infection. NSCs were cultured in vitro. The proliferation level was detected by methyl thiazolyl tetrazolium (MTT) assay. After differentiation culture of NSCs, the immunofluorescence assay was conducted to detect the expression of nestin, microtubule-associated protein 2 (MAP2) and glial fibrillary acidic protein (GFAP) to calculate the ratio of NSCs which differentiated to neurons and astrocytes. The embryonic nerve tissues at E9, E10 and E11 day in each group were taken to make frozen sections. The immunofluorescence assay was carried out to detect the expression of neuronal cell adhesion molecule (NCAM) in the nerve tissues at different developmental stages. RESULTS: Both the results of blood smears and RT-PCR confirmed that the pregnant rats and embryos were all infected by T. gondii in infection group. The morphology of the cultured NSCs under microscope was consistent with the characteristics of the normal NSCs. In addition, the NSC biomarker nestin protein was stained positive. The MTT assay showed that the proliferation level was lower in infection group than that of the control, and statistical differences were found between the two groups at day 3 and 4 after passages (P < 0.05). The immunofluorescence staining of MAP2 and GFAP showed that the percentage of neuron differentiation was 15.15% (55/363) in control group and 8.73% (31/355) in infection group, respectively, with a statistical difference (P < 0.05), and the percentage of astrocyte differentiation was 53.35% (199/374) and 67.48% 249/369), respectively (P > 0.05). In both groups, NCAM protein was found expressed at E9, E10 and E11 day in embryo nerve tissues. The fluorescence became stronger with time. The expression level in control group was significantly higher than that in infection group (P < 0.01). CONCLUSION: T. gondii infection at early gestation may inhibit the proliferation, differentiation and migration of neural stem cells in rats.