Excreted/secreted glycoproteins of G. intestinalis play an essential role in the antibody response

Hyung

et al. 2012

Parasite Immunology

Giardia lamblia, a pathogen causing diarrhoeal outbreaks, is interesting how it triggers immune response in the human epithelial cells. This study defined the crucial roles of signalling components involved in G. lamblia-induced cytokine production in human epithelial cells. Incubation of the gastrointestinal cell line HT-29 with G. lamblia GS trophozoites triggered production of interleukin (IL)-1β, IL-8 and tumour necrosis factor (TNF)-α. IL-8 production was not significantly decreased by physically separating the HT-29 cells and G. lamblia GS trophozoites. Indeed, treatment of HT-29 with G. lamblia excretory-secretory products (ESP) induced IL-8 production. Electrophoretic mobility gel shift and transfection assays using mutagenized IL-8 promoter reporter plasmids indicated that IL-8 production by G. lamblia ESP occurs through activation of two transcriptional factors, nuclear factor kappaB (NF-κB) and activator protein 1 (AP-1) in HT-29 cells. In addition, activation of two mitogen-activated protein kinases (MAPKs), p38 and ERK1/2, was also detected in the HT-29 cells stimulated with G. lamblia ESP. Selective inhibition of these MAPKs resulted in decreased production of ESP-induced IL-8. These results indicate that activation of p38, ERK1/2 MAPK, NF-κB and AP-1 comprises the signalling pathway responsible for IL-8 production by G. lamblia ESP.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Excretory–secretory products of Giardia lamblia induce interleukin‐8 production in human colonic cells via activation of p38, ERK1/2, NF‐κB and AP‐1

Hyung

et al. 2012

Parasite Immunology

European Journal of Cell Biology

“…Oral administration of G. lamblia ESPs into BALB/c mice stimulated a Th2 response, which led to intestinal histological changes characterized by eosinophilic infiltration, and can induce host cell apoptosis, hypercellularity, and enterocytic desquamation (Jiménez et al, 2004). Glycoproteins in G. lamblia ESP were found to induce antibody production during giardiasis (Jiménez et al, 2007). Cysteine proteases present in G. lamblia ESP were essential for the induction of antibody and cytokine production in BALB/c mice infected with ESP (Jiménez et al, 2009).…”

Section: Exosome and Microvesicles Content Can Alter Neighbouring Cellsmentioning

confidence: 99%

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

Evans-Osses

Mojoli

Monguió‐Tortajada

et al. 2017

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.

“…However, recent studies have shed light on trophozoites excreted/secreted proteases and their involvement in immunological and pathophysiological processes (Jiménez et al 2000;Kaur et al 2001;Shant et al 2002, Jiménez et al 2004. A series of studies have reported that trophozoite proteins are excreted and secreted during in vitro growth (Nash and Keister 1985;Jiménez et al 2000;Shant et al 2002) and some of them have provided considerable evidences that these molecules seem to be important in processes such adhesion, nutrition, pathogenesis, and evasion of the host immune response (Kaur et al 2001;Shant et al 2002;Jiménez et al 2004;Rodríguez-Fuentes et al 2006;Jiménez et al 2007).…”

Section: Introductionmentioning

confidence: 98%

Protease activity in extracellular products secreted in vitro by trophozoites of Giardia duodenalis

et al. 2008

There are evidences that Giardia trophozoites contain and/or release proteolytic enzymes that may be implicated in pathogenesis of giardiasis. This report describes a preliminary characterization of the proteolytic activity in excretory/secretory (E/S) products of Giardia duodenalis trophozoites of an axenic Brazilian strain (BTU-11) and the reference strain Portland 1 (P1). The protease activity of E/S products in conditioned medium by trophozoites of each strain was analyzed using substrate (gelatin and collagen) impregnated SDS-PAGE and hemoglobin assay. The protease characterization was based on inhibition assays including synthetic inhibitors. Proteolytic products were detected in the conditioned medium by trophozoites of both assayed strains. In the gels containing copolymerized gelatin and collagen, E/S products promoted degradation of the substrates and the most evident proteolysis zones were distributed in the migration regions of 77 to 18 kDa and 145 to 18 kDa, respectively, in the patterns of gelatinolytic and collagenolytic activities. Degradation of hemoglobin was also observed, and the pattern of hydrolysis was similar in both E/S products assayed. Inhibition assays showed that the main proteolytic activity in both E/S products is due to cysteine proteases although the presence of serine proteases was also indicated, mainly in the hydrolysis of hemoglobin.