Host-microbe interactions and defense mechanisms in the development of amoebic liver abscesses.

Amoebiasis by Entamoeba histolytica is a major public health problem in developing countries and leads to several thousand deaths per year. The parasite invades the intestine (provoking diarrhea and dysentery) and the liver, where it forms abscesses (amoebic liver abscesses [ALAs]). The liver is the organ responsible for filtering blood coming from the intestinal tract, a task that implies a particular structure and immune features.

Bioinformatics and functional analysis of an Entamoeba histolytica mannosyltransferase necessary for parasite complement resistance and hepatical infection.

The glycosylphosphatidylinositol (GPI) moiety is one of the ways by which many cell surface proteins, such as Gal/GalNAc lectin and proteophosphoglycans (PPGs) attach to the surface of Entamoeba histolytica, the agent of human amoebiasis. It is believed that these GPI-anchored molecules are involved in parasite adhesion to cells, mucus and the extracellular matrix. We identified an E.

Initiation of inflammation and cell death during liver abscess formation by Entamoeba histolytica depends on activity of the galactose/N-acetyl-D-galactosamine lectin.

The parasite Entamoeba histolytica colonizes the human intestine causing amoebic colitis and disseminates through the vascular route to form liver abscesses. The Gal/GalNAc lectin is an adhesion protein complex which sustains tissue invasion by E. histolytica.

Roles of cell adhesion and cytoskeleton activity in Entamoeba histolytica pathogenesis: a delicate balance.

The protozoan parasite Entamoeba histolytica colonizes the human large bowel. Invasion of the intestinal epithelium causes amoebic colitis and opens the route for amoebic liver abscesses. The parasite relies on its dynamic actomyosin cytoskeleton and on surface adhesion molecules for dissemination in the human tissues.

Myosin II and the Gal-GalNAc lectin play a crucial role in tissue invasion by Entamoeba histolytica.

Entamoeba histolytica is the human parasite responsible of amoebiasis, during which highly motile trophozoites invade the intestinal epithelium leading to amoebic colitis, and disseminate via the blood circulation causing liver abscesses. The invasive process, central to the pathogenesis, is known to be driven by parasites motility. To investigate molecules responsible for in vivo motion, we performed a high resolution dynamic imaging analysis using two-photon laser scanning microscopy.

Fate of Entamoeba histolytica during establishment of amoebic liver abscess analyzed by quantitative radioimaging and histology.

The protozoan parasite Entamoeba histolytica is the causative agent of amoebiasis, a human disease characterized by dysentery and liver abscess. The physiopathology of hepatic lesions can be satisfactorily reproduced in the hamster animal model by the administration of trophozoites through the portal vein route. Hamsters were infected with radioactively labeled amoebas for analysis of liver abscess establishment and progression.

Purification and biochemical characterization of a novel cysteine protease of Entamoeba histolytica.

Cysteine proteases are important virulence factors of Entamoeba histolytica, the causative agent of amoebiasis. A novel cysteine protease from parasite extracts was purified 15-fold by a procedure including concanavalin A-Sepharose, hydroxylapatite and DEAE-Sepharose chromatography. The purification resulted in the obtainment of an homogeneous protein with a molecular mass of 66 kDa on native PAGE.

Inhibitory activity of saccharomyces yeasts on the adhesion of Entamoeba histolytica trophozoites to human erythrocytes in vitro.

Adhesion to target cells represents the first step in infection by Entamoeba histolytica. Binding of axenic amoeba (HMI strain) to human red cells in vitro was employed as a model of the adhesion process. The influence of precontact of trophozoites with suspensions of live Saccharomyces boulardii yeasts, their fractions (membranes and yeast-content supernatant before and after filtration to eliminate the membrane) or yeast culture medium before and after fermentation was investigated.

Purification and functional characterization of the 112 kDa adhesin of Entamoeba histolytica.

The 112 kDa adhesin of E. histolytica is directly involved in the cytopathogenic activity of the parasite. We describe here the purification of the 112 kDa protein by electroelution and immunoaffinity chromatography using a monoclonal antibody against the adhesin.

A new in vitro model of Entamoeba histolytica adhesion, using the human colon carcinoma cell line Caco-2: scanning electron microscopic study.

The human colon carcinoma cell line Caco-2, which is widely used to study the adhesion and cytotoxicity of enterobacteria, was used to investigate the adhesion of the trophozoites of Entamoeba histolytica. We observed a high percentage of adhesion of amoebae to Caco-2 cells. Scanning electron microscopy showed that amoebial membrane structures were involved in adhesion and the cytolytic action.

[Effects of Saccharomyces boulardii yeast on trophozoites of Entamoeba histolytica in vitro and in cecal amebiasis in young rats].

Lyophilized and rehydrated Saccharomyces boulardii yeasts were administered to young rats previously inoculated into the cecum with Entamoeba histolytica. The numbers of diseased young rats and the severity of the infection, assessed from the appearance of the cecum and its content of mucus and amebae, were significantly reduced by the treatment. The lesions observed resembled those seen in the untreated controls, although healing was faster in the treated animals.

[A new experimental model of cecal amebiasis in rats].

The young rat was used as an experimental model of caecal amebiasis by implanting, without injury of the caecum, a suspension of E. histolytica trophozoites gnotoxenic strain Rahman of high virulence. The degree of pathogenicity is demonstrated by the macroscopic aspect of caecum, by the density of trophozoites and by an anatomopathologic examination.