Dataset Information

Genome-wide gene expression analysis of human foreskin fibroblast cells infected with Toxoplasma gondii over time

ABSTRACT: Analysis of host cell gene expression patterns following infection of the parasite Toxoplasma gondii over a time course of 2 hours, 6 hours and 24 hours. Parasites were washed off after 2 hours to ensure that gene expression changes are truly reflective of an on-going infection, and not on-going parasite invasion.

ORGANISM(S): Homo sapiens

PROVIDER: GSE98677 | GEO | 2017/07/05

SECONDARY ACCESSION(S): PRJNA385865

REPOSITORIES: GEO

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Project description:The innate immune response of mucosal epithelial cells during pathogen invasion plays a central role in immune regulation in the gut. Toxoplasma gondii (T. gondii) is a protozoan intracellular parasite that is usually transmitted through oral infection. Although much of the information on immunity to T. gondii has come from intra-peritoneal infection models, more recent studies have revealed the importance of studying immunity following infection through the natural per-oral route. Oral infection studies have identified many of the key players in the intestinal response; however, they have relied on responses detected days to weeks following infection. Much less is known about how the gut epithelial layer senses and reacts during initial contact with the pathogen. Given the importance of epithelial cells during pathogen invasion, this study uses an in vitro approach to isolate the key players and examine the early response of intestinal epithelial cells during infection by T. gondii. We show that human intestinal epithelial cells infected with T. gondii elicit rapid MAPK phosphorylation, NF-ÎºB nuclear translocation, and secretion of interleukin (IL)-8. Both ERK1/2 activation and IL-8 secretion responses were shown to be MyD88 dependent and TLR2 was identified to be involved in the recognition of the parasite regardless of the parasite genotype. Furthermore, we were able to identify additional T. gondii-regulated genes in the infected cells using a pathway-focused array. Together, our findings suggest that intestinal epithelial cells were able to recognize T. gondii during infection, and the outcome is important for modulating intestinal immune responses. Oral infection studies have demonstrated an increase in several cytokines and chemokines in response to T.gondii infection; however, the mixed population of the intestinal mucosa did not allow for the determination of the relative role that specific cell populations play in the production of these mediators. To address the role of intestinal epithelial cells to modulate the cytokine environment early following infection, we used specific pathway arrays to identify cytokines and chemokines induced 4 hours after exposure to T. gondii. At this time point most cells have become infected, but the parasites have not replicated.

Project description:Toxoplasma gondii is a globally distributed obligate intracellular parasite which can cause zoonotic toxoplasmosis with great harms. The average death time of mice that infected with Toxoplasma gondii RH strain tachyzoites recovered from the liquid nitrogen was shortened after multiple generations. It has been reported that the parasite is in a state of static virulence during cryopreservation and the virulence of the protozoan parasite can be enhanced after continuous passages in hosts under laboratory conditions. However, no research has been conducted to elucidate its biological mechanism. Herein, we sequenced the T. gondii transcriptome using RNA-Seq technology and performed de novo assembly to investigated the virulence factors expression changes by comparing gene expression profiles between incipiently recovered and completely resuscitated tachyzoites. Transcriptome analysis identified 1,951 differentially expressed transcripts in infected liver, of which 1,752 were significantly downregulated and 199 upregulated. We identified many differentially expressed proteins and genes, including serine/threonine kinase, calnexin, myosin and microtubule-associated protein which have previously been reported to be either involved in cell adhesion, parasite gliding or participate in cell invasion. The great majority of the virulence factors including microneme proteins, rhoptry proteins and dense granule proteins were upregulated in fully recovered tachyzoites. The enhanced virulence of recovered Toxoplasma gondii RH strain from the liquid nitrogen is associated with the up-regulated expression of MICs, ROPs and GRAs. Our data will facilitate future genomic research and in-depth annotation of Toxoplasma gondii RH strain genomes. This study provides a profile of the candidate genes that are suspected to be involved with virulence enhancement of recovered Toxoplasma gondii RH strain tachyzoites. Many further studies should be carried out to confirm the function of the candidate genes. Moreover, the preliminary identification of genes and pathways exhibiting differential expression in complete resuscitation stage may further our general understanding of virulence enhancement in this parasite.

Dataset Information

Genome-wide gene expression analysis of human foreskin fibroblast cells infected with Toxoplasma gondii over time

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