Biology of<i>Giardia lamblia</i>

Adam, Rodney D.

doi:10.1128/cmr.14.3.447-475.2001

Cited by 1,117 publications

(1,144 citation statements)

References 362 publications

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“…These molecules are also present in extracellular vesicles (EVs: mainly exosomes and microvesicles), which are released from different cell types and are able to bind to receptors on target cells, triggering intracellular signalling that modifies the physiological state of the target cells (Ratajczak et al, 2006). stand evolution, organelle function, and antigenic variation (Adam, 2001).…”

Section: Introductionmentioning

confidence: 99%

Microvesicles released from Giardia intestinalis disturb host-pathogen response in vitro

Evans-Osses

Mojoli

Monguió‐Tortajada

et al. 2017

European Journal of Cell Biology

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a b s t r a c tGiardia intestinalis (G.I), is an anaerobic protozoan and the aetiological agent of giardiasis, a diarrhoea present worldwide and associated with poverty. G.I has a simple life cycle alternating between cyst and trophozoite. Cysts are transmitted orally to the stomach and transform to trophozoites in the intestine by a multifactorial process. Recently, microvesicles (MVs) have been found to be released from a wide range of eukaryotic cells. We have observed a release of MVs during the life cycle of G.I., identifying MVs from active trophozoites and from trophozoites differentiating to the cyst form. The aim of the current work was to investigate the role of MVs from G.I in the pathogenesis of giardiasis. MVs from log phase were able to increase the attachment of G. intestinalis trophozoites to Caco-2 cells. Moreover, MVs from G. intestinalis could be captured by human immature dendritic cells, resulting in increased activation and allostimulation of human dendritic cells. Lipid rafts participate in the MV biogenesis and in the attachment to Caco-2 cells. Nevertheless, proteomic analysis from two types of MVs has shown slight differences at the protein levels. An understanding of biogenesis and content of MVs derived from trophozoites might have important implications in the pathogenesis of the disease.

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Section: Introductionmentioning

confidence: 99%

Microvesicles released from Giardia intestinalis disturb host-pathogen response in vitro

Evans-Osses

Mojoli

Monguió‐Tortajada

et al. 2017

European Journal of Cell Biology

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“…The parasite has two stages in the life cycle: infective cyst and trophozoite. The major sources and routes of cyst transmission are contaminated water and food or direct fecal-oral contact [3]. Non-specific symptoms, such as diarrhea, greasy stools, flatulence and abdominal cramps, might be noticed during the course of infection.…”

Section: Introductionmentioning

confidence: 99%

Epidemiological survey in Łęczyńsko-Włodawskie Lake District of eastern Poland reveals new evidence of zoonotic potential of <i>Giardia intestinalis</i>

Stojecki¹,

Sroka²,

Cencek³

et al. 2015

Ann Agric Environ Med.

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Faecal samples from 297 farm animals were collected from 18 households in distinct sites of the Łęczyńsko-Włodawskie Lake District of eastern Poland. They included samples from 86 cattle (Bos taurus), 84 pigs (Sus scrofa f. domestica), 81 sheep (Ovis aries), 10 horses (Equus caballus), and 36 dogs (Canis lupus familiaris). The samples were examined for the presence of Giardia intestinalis by the Direct Fluorescence Assay (DFA) and semi-nested PCR. All amplicons were sequenced on both strands. By DFA, cysts of Giardia spp. were detected in 66 of 297 faecal samples (22.2%). Positive specimens for Giardia spp. were derived from 29.8% of examined pigs, 21.0% of sheep, 18.6% of cattle, 10% of horses, and 19.4% of dogs. Based on the detection of the β-giardin gene by PCR, 39 (13.1%) of the 297 examined samples were recognized as positive. Detection of the presence of Giardia cysts by DFA test was overall significantly higher compared to PCR (p=0.0045). By PCR, Giardia was found in 28.1% of sheep, 11.6% of cattle, 10% of horses, 9.5% of pigs and 5.6% of dogs. Partial β-giardin gene sequences were obtained for 73.7% of the PCR positive samples. From sequenced samples derived from the studied animals, Giardia were identified as assemblage A (8 samples), B (1 sample) and E (18 samples). As assemblages A and B may be zoonotic, the farm animals living in eastern Poland could be regarded as a potential source of Giardia infection for humans.

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“…Infection usually starts by ingestion of cysts, which differentiate into trophozoites that colonize the upper small intestine [2]. Clinical manifestations of giardiasis vary from asymptomatic carriage to chronic diarrhea and severe malabsorption [3].…”

Section: Introductionmentioning

confidence: 99%

Release of metabolic enzymes by Giardia in response to interaction with intestinal epithelial cells

Ringqvist

Palm

Skarin

et al. 2008

Molecular and Biochemical Parasitology

154

139

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Giardia lamblia, an important cause of diarrheal disease, resides in the small intestinal lumen in close apposition to epithelial cells. Since the disease mechanisms underlying giardiasis are poorly understood, elucidating the specific interactions of the parasite with the host epithelium is likely to provide clues to understanding the pathogenesis. Here we tested the hypothesis that contact of Giardia lamblia with intestinal epithelial cells might lead to release of specific proteins. Using established co-culture models, intestinal ligated loops and a proteomics approach, we identified three G. lamblia proteins (arginine deiminase, ornithine carbamoyl transferase and enolase), previously recognized as immunodominant antigens during acute giardiasis. Release was stimulated by cell-cell interactions, since only small amounts of arginine deiminase and enolase were detected in the medium after culturing of G. lamblia alone. The secreted G. lamblia proteins were localized to the cytoplasm and the inside of the plasma membrane of trophozoites. Furthermore, in vitro studies with recombinant arginine deiminase showed that the secreted Giardia proteins can disable host innate immune factors such as nitric oxide production. These results indicate that contact of Giardia with epithelial cells triggers metabolic enzyme release, which might facilitate effective colonization of the human small intestine. a b s t r a c tGiardia lamblia, an important cause of diarrheal disease, resides in the small intestinal lumen in close apposition to epithelial cells. Since the disease mechanisms underlying giardiasis are poorly understood, elucidating the specific interactions of the parasite with the host epithelium is likely to provide clues to understanding the pathogenesis. Here we tested the hypothesis that contact of Giardia lamblia with intestinal epithelial cells might lead to release of specific proteins. Using established co-culture models, intestinal ligated loops and a proteomics approach, we identified three G. lamblia proteins (arginine deiminase, ornithine carbamoyl transferase and enolase), previously recognized as immunodominant antigens during acute giardiasis. Release was stimulated by cell-cell interactions, since only small amounts of arginine deiminase and enolase were detected in the medium after culturing of G. lamblia alone. The secreted G. lamblia proteins were localized to the cytoplasm and the inside of the plasma membrane of trophozoites. Furthermore, in vitro studies with recombinant arginine deiminase showed that the secreted Giardia proteins can disable host innate immune factors such as nitric oxide production. These results indicate that contact of Giardia with epithelial cells triggers metabolic enzyme release, which might facilitate effective colonization of the human small intestine.

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Biology ofGiardia lamblia

Cited by 1,117 publications

References 362 publications

Microvesicles released from Giardia intestinalis disturb host-pathogen response in vitro

Microvesicles released from Giardia intestinalis disturb host-pathogen response in vitro

Epidemiological survey in Łęczyńsko-Włodawskie Lake District of eastern Poland reveals new evidence of zoonotic potential of <i>Giardia intestinalis</i>

Release of metabolic enzymes by Giardia in response to interaction with intestinal epithelial cells

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