Project description:Differentiation of proliferative acute stages into semi-quiescent chronic stages is key for Toxoplasma gondii persistence within an infected host. During natural infection, chronic stages are almost exclusively found in neurons, and it is well appreciated that neurons support high rates of spontaneous differentiation in cell culture. Recently, we found that parasites lacking the RNA-binding protein BFD2 are unable to produce chronic forms, consistent with a block in this develomental program. To compare the effects of BFD1 and BFD2 on chronic-stage transcriptional reprogramming in T. gondii, we profiled the transcriptomes of both 'wildtype' and BFD1- and BFD2-knockout parasites during infection of murine primary neurons.
Project description:In the DSS-induced colitis model, the epithelial damage and resulting inflammation is restricted to the colon, with a potential influence on the microbial composition in the adjacent cecum. Several studies have reported changes of the gut microbiota in the DSS-induced colitis model and other mouse models of IBD. Furthermore, metaproteomics analysis of the gut microbiome in a mouse model of Crohn’s disease demonstrated that disease severity and location are microbiota-dependent, with clear evidence for the causal role of bacterial dysbiosis in the development of chronic ileal inflammation. We have developed a refined model of chronic DSS-induced colitis that reflects typical symptoms of human IBD without a risky body weight loss usually observed in DSS models [Hoffmann et al., submitted]. In this study, we used metaproteomics to characterize the disease-related changes in bacterial protein abundance and function in the refined model of DSS-induced colitis. To assess the structural and functional changes, we applied 16S rRNA gene sequencing and metaproteomics analysis of the intestinal microbiota in three different entities of the intestinal environment, i.e. colon mucus, colon content and cecum content.
Project description:Toxoplasma gondii persists in humans by converting from actively replicating acute stage tachyzoites to slow-growing chronic stage bradyzoites. The molecular mechanisms that mediate T. gondii differentiation remain poorly understood. Through a chemical mutagenesis screen, we identified translation initiation factor eIF1.2 as being critical for T. gondii differentiation. The presence of an F97L mutation in eIF1.2 identified in the screen or the complete lack eIF1.2 (∆eIF1.2) markedly impeded bradyzoite cyst formation in culture and in the brains of infected mice. ∆eIF1.2 parasites were defective in the upregulation of bradyzoite differentiation regulators BFD1 and BFD2 during stress-induced differentiation. Conditional overexpression of BFD1 or BFD2 rescued differentiation in ∆eIF1.2 parasites. We further show that eiF1.2 interacted with the yeast 40S ribosome and directed the scanning of a model 5’ untranslated region. Together, our findings imply that eIF1.2 functions by regulating the translation of key differentiation factors necessary to establish T. gondii chronic infection.
Project description:Expression profile microarray of human foreskin fibroblast cell comparing control untreated HFF cell with HFF cell infected with ME49 strain.Study on Toxoplasma gondii infection of HFF cell LncRNAs expression, for further studies on the differential exprssion of LncRNAs in HFF cell against the infection of Toxoplasma gondii research provide the basic function.
Project description:Toxoplasma gondii (T. gondii) is an obligate intracellular parasite that can infect almost all warm-blooded animals, causing serious public health problems. Lysine crotonylation (Kcr) is a newly discovered posttranslational modification (PTM), which has been proved that is relevant to procreation regulation, active transcription and cell signaling pathway. However, the biological functions of crotonylation have not yet been reported in macrophages infected with T. gondii. In our study, we performed a ChIP-seq analysis of porcine alveolar macrophages infected with T. gondii RH to explore the relationship of histone Kcr with T. gondii infection.
Project description:During chronic infection memory T cells acquire a unique phenotype and become dependent on different survival signals than those needed for memory T cells generated during an acute infection. The distinction between the role of effector and memory T cells in an environment of persistent antigen remains unclear. Here, in the context of chronic Toxoplasma gondii infection we demonstrate that a population of CD8 T cells exhibiting a tissue resident memory (TRM) phenotype persists in the brain. We show that this population is distributed throughout the brain in both parenchymal and extraparenchymal spaces. Furthermore, this population is transcriptionally distinct and exhibits a transcriptional signature consistent with the TRM observed in acute viral infections.
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-κB 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 zoonotic pathogen for which felids serve as definitive hosts. In cats, the parasite undergoes several rounds of asexual replication before entering the sexual cycle which gives rise to oocysts that are shed into the environment. These then sporulate and become infective to humans and live stock. To understand the genes involved in the parasite development in the felid host and identify potential intervention targets, we designed a transcriptomic approach to compare the cat intestinal stages with the well characterised tachyzoites that mediate acute infection and tissue cysts that are responsible for chronic infection. Cats were infected with T. gondii tissue cysts from mouse brain and sampled the intestinal stages at day 3, 5 and 7 post infection. As an input sample, we also collected tissue cysts from mouse brain as well as in vitro cultivated tachyzoites. Total RNA was extracted, enriched for mRNA and used for cDNA synthesis. RNA-Seq was then performed to describe the transcriptomic repertoire of each time point/life cycle stage.
Project description:Cyst formation is a key feature of the T. gondii life cycle but the genetic networks that drive this process are not yet fully characterized. To identify new components of this network, we compared T. gondii to its nearest extant relative Hammondia hammondi given the critical differences between these species in the timing and efficiency of cyst formation. Using transcriptional data from critical developmental and pH exposure time points from both species, we identified the gene TGVEG_311100, which we named Regulator of Cystogenesis 1 (ROCY1), as being both necessary and sufficient for cyst formation in T. gondii. Compared to WT parasites, TGVEG?ROCY1 parasites formed significantly fewer tissue cysts in response to alkaline pH stress in vitro and cysts were nearly undetectable in mouse brains for up to 9 weeks post-infection. Overexpression of tagged ROCY1 in WT parasites was sufficient to induce cyst formation in vitro in both WT and ROCY1-deficient parasites, demonstrating that ROCY1 is both necessary and sufficient for cyst formation. Moreover this induction of cyst formation required at least 1 of 3 predicted CCCH Zinc finger domains. Mice chronically infected with ?ROCY1 parasites had detectable tachyzoites in the brain for up to 37 days post-infection (while mice infected with WT parasites did not), and CNS transcriptional analyses at day 30 post-infection throughout the chronic phase of infection revealed inflammatory signatures consistent with acute infection in ?ROCY1 parasites compared to WT. Despite our inability to detect brain cysts in infected mice, both WT and ?ROCY1 knockout parasites reactivated after dexamethasone treatment with similar timing and magnitude for up to 5 months post infection, challenging the paradigm that long term parasite persistence in the CNS requires cyst formation. These data identify a new regulator of cyst formation in T. gondii that is both necessary and sufficient for cyst formation, and whose function relies on its conserved nucleic acid binding motif.
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-κB 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.