Dataset Information

Quantitative proteomics of host-parasite interactions in Giardia duodenalis

ABSTRACT: Giardia duodenalis is the protozoan agent responsible for the majority of parasitic gastroenteritis in humans worldwide. Disease pathology includes malabsorption and maldigestion, cell apoptosis and small intestinal barrier dysfunction, which occurs in absence of known toxins, cell invasion and overt inflammation. To understand pathogenesis, host-parasite in vitro interaction models provide global insights into disease induction and virulence. Hence, we performed the first proteomic analysis of G. duodenalis trophozoites interacted with intestinal epithelial cells (IECs, HT-29) for 6 hours, and compared it to trophozoites exposed to cell-free fractions of host-soluble signals. This has allowed us to demonstrate that distinct and independent protein cascades are induced by host attachment compared to host soluble signals. We utilised a tandem mass tag (TMT) approach and evaluated it as quantitative proteomics for the first time in Giardia.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Giardia Intestinalis Assemblage A

TISSUE(S): Trophozoite

SUBMITTER: Samantha Emery

LAB HEAD: Professor Paul Haynes

PROVIDER: PXD002398 | Pride | 2016-02-19

REPOSITORIES: Pride

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Publications

Induction of virulence factors in Giardia duodenalis independent of host attachment.

Emery Samantha J SJ Mirzaei Mehdi M Vuong Daniel D Pascovici Dana D Chick Joel M JM Lacey Ernest E Haynes Paul A PA

Scientific reports 20160212

Giardia duodenalis is responsible for the majority of parasitic gastroenteritis in humans worldwide. Host-parasite interaction models in vitro provide insights into disease and virulence and help us to understand pathogenesis. Using HT-29 intestinal epithelial cells (IEC) as a model we have demonstrated that initial sensitisation by host secretions reduces proclivity for trophozoite attachment, while inducing virulence factors. Host soluble factors triggered up-regulation of membrane and secrete ...[more]

PMID: 26867958

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Project description:Despite of Giardia duodenalis being one of the most commonly found intestinal pathogens in humans and animals, little is known of the host-parasite interactions in natural hosts. Therefore, the objective of this study was to investigate the intestinal response in calves following a G. duodenalis infection, using a bovine high-density oligo microarray to analyze global gene expression in the small intestine. The resulting microarray data suggested a decrease in inflammation, immune response and immune cell migration in infected animals, which was examined in more detail by quantitative real-time PCR on a panel of cytokines combined with histological analyses. The cytokine transcription levels showed a trend of down regulated expression in infected animals compared to the negative controls, best seen in jejunum for IL-6 and IL-8 and statistically significant for IL-17, IL-13 and IFN-?. No increased immune cell recruitment could be seen after infection, as well as no intestinal pathologies, such as villus shortening or increased levels of apoptosis. Key regulators in this intestinal response seem to be the nuclear peroxisome proliferator-activated receptors alpha (PPARA) and gamma (PPARG), for which an up-regulated expression was seen on microarray and qRT-PCR data. The activation of PPARs can exert an anti-inflammatory effect with inhibition of pro-inflammatory cytokines and a decrease in cell recruitment. . How the PPARs are activated during a Giardia infection still needs to be further elucidated. Eight male Holstein calves aged two to four weeks old were used for the trial. Prior to arrival, all animals were screened for the presence of Giardia cysts in their faecal samples. After confirming their negative status for all these pathogens, four of the animals were randomly chosen and placed in a G. duodenalis contaminated environment, whereas the four remaining animals were kept as negative controls in separate G. duodenalis-free stables. All calves in the study received the same commercial milk replacer. After three weeks, the presence or absence of a G. duodenalis infection was confirmed by IFA on faecal samples after which the animals were euthanized. Changes in gene expression profiles induced by Giardia duodenalis infection were compared using a high-density 60mer bovine oligo microarray.

Project description:Giardia causes more episodes of illness worldwide than any other parasite. It is a flagellated cyst-forming enteric pathogen that inhabits the lumen of the small intestine and although it is clear that more and less virulent strains do occur, pathogenesis and virulence of Giardia remains poorly understood. Identification of Giardia virulence factors is highly desirable since their expression would be the best indicator for determining disease outcome. The advent of quantitative proteomics has been timely in investigating which proteins are likely to be secreted virulence factors. Here we successfully apply such analyses to the whole parasite and to the supernatants derived from the parasite, in order to ascertain a repertoire of secreted proteins. In our initial analysis we compared replicates of Giardia cells and culture supernatants from the two major lineages which cause human disease – assemblage A and assemblage B. The genome of Giardia is believed to contain open reading frames which could encode as many as 6000 proteins. In our study we confirm expression of ~1600 proteins from each assemblage, the vast majority of which being common to both lineages. To look for actual enrichment of secreted proteins, we considered the ratio of proteins in the supernatant compared with the pellet. This simple method defines a small group of enriched proteins, putatively secreted at a steady state by cultured growing Giardia trophozoites of both assemblages. This secretome contains a high proportion annotated to have N’ terminus signal peptides, with some showing evidence of having recently evolved under strong positive selective pressure. The most abundant secreted proteins include known virulence factors such as the Cathepsin B cysteine proteases and members of a Giardia superfamily of Cysteine Rich Proteins which comprises VSPs, HCMPs and a new class of virulence factors, the Giardia Tenascins. Since we also find that physiological function of human enteric epithelial cells can be disrupted by soluble factors even in the absence of the trophozoites we are able to propose a straightforward model of Giardia pathogenesis incorporating key roles for the major Giardia derived soluble mediators.

			Action	DRS
	TMTFraction1.raw	Raw
	TMTFraction10.raw	Raw
	TMTFraction11.raw	Raw
	TMTFraction12.raw	Raw
	TMTFraction2.raw	Raw