Phagocytosis of<i>Giardia lamblia</i>trophozoites by cytokine-activated macrophages

Belosevic, Miodrag; Cw, Daniels

doi:10.1111/j.1365-2249.1992.tb02992.x

Cited by 27 publications

(13 citation statements)

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“…The increase of trophozoite levels in relation to cells (3:1) did not significantly influence trophozoite adherence and ingestion, in agreement with other research 24 in which a 10‐fold increase in the number of available trophozoites for interaction with macrophages did not alter the level of phagocytic activity. The percentage of dead intracellular trophozoites reached almost 50%, indicating that these phagocytes may have a double functional role as effector cells and also as antigen‐presenting cells.…”

Section: Discussionsupporting

confidence: 91%

Phagocytosis of Giardia lamblia trophozoites by human colostral leukocytes

et al. 2006

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Aim: To determine the phagocytic activity of the polymorphonuclear and mononuclear cells present in human colostrum, and to verify the influence of opsonins in the adherence, ingestion and killing of Giardia lamblia trophozoites. Methods: Polymorphonuclear and mononuclear phagocytes were incubated with G. lamblia trophozoites, in the presence as well as the absence of supernatant of human colostrum (the source of opsonins) for 30, 60 and 120 min. The trophozoites/phagocytes ratio was 1:1, and the percentage of phagocytosed trophozoites was determined by microscopic examination of acridine orange‐stained cells. Results: The mononuclear phagocytes presented more functional activity than the polymorphonuclear. The highest indexes of adherence (77.6±5.1), ingestion (68.9±5.5) and killing (48.5±4.9) were obtained through the incubation of mononuclear cells in the presence of colostrum supernatant for 120 min. Conclusion: The phagocytes of human colostrum were able to ingest G. lamblia trophozoites and presented microbicidal activity in vitro, suggesting that these phagocytes may act as an additional mechanism of protection against infant giardiasis through breastfeeding.

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Section: Discussionsupporting

confidence: 91%

Phagocytosis of Giardia lamblia trophozoites by human colostral leukocytes

et al. 2006

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“…The activation of immune factors, such as T cells, neutrophils, mast cells, secretory IgA, proinflammatory cytokines, and nitric oxide, have been reported in Giardia -infected humans and mice [14,15,22,23,37-39]. A recent report described long-term CD4 + T cell proliferative responses in patients 5 years after acute giardiasis [40], suggesting unresolved immune activation during the post-clearance phase.…”

Section: Discussionmentioning

confidence: 99%

Persistent gut barrier damage and commensal bacterial influx following eradication of Giardia infection in mice

Chen

et al. 2013

Gut Pathog

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BackgroundRecent studies of Giardia lamblia outbreaks have indicated that 40–80% of infected patients experience long-lasting functional gastrointestinal disorders after parasitic clearance. Our aim was to assess changes in the intestinal barrier and spatial distribution of commensal bacteria in the post-clearance phase of Giardia infection.MethodsMice were orogastrically inoculated with G. lamblia trophozoites (strain GS/M) or pair-fed with saline and were sacrificed on post-infective (PI) days 7 (colonization phase) and 35 (post-clearance phase). Gut epithelial barrier function was assessed by Western blotting for occludin cleavage and luminal-to-serosal macromolecular permeability. Gut-associated, superficial adherent, and mucosal endocytosed bacteria were measured by agar culturing and were examined by fluorescence in situ hybridization. Intracellular bacteria cultured from isolated mucosal cells were characterized by 16S rDNA sequencing. Neutrophil-specific esterase staining, a myeloperoxidase activity assay, and enzyme-linked immunosorbent assays for cytokine concentrations were used to verify intestinal tissue inflammation.ResultsTight junctional damage was detected in the intestinal mucosa of Giardia-infected mice on PI days 7 and 35. Although intestinal bacterial overgrowth was evident only during parasite colonization (PI day 7), enhanced mucosal adherence and endocytosis of bacteria were observed on PI days 7 and 35. Multiple bacterial strains, including Bacillus, Lactobacillus, Staphylococcus, and Phenylobacterium, penetrated the gut mucosa in the post-infective phase. The mucosal influx of bacteria coincided with increases in neutrophil infiltration and myeloperoxidase activity on PI days 7 and 35. Elevated intestinal IFNγ, TNFα, and IL-1β levels also were detected on PI day 35.ConclusionsGiardia-infected mice showed persistent tight junctional damage and bacterial penetration, accompanied by mucosal inflammation, after parasite clearance. These novel findings suggest that the host’s unresolved immune reactions toward its own microbiota, due to an impaired epithelial barrier, may partly contribute to the development of post-infective gut disorders.

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“…However, the uptake of opsonised or unopsonised E. coli is the same in IL-4-treated and untreated macrophages, whereas Raveh et al (1998) showed an increase of the phagocytosis of Saccharomyces cerevisiae by thioglycollate elicited peritoneal macrophages after IL-4 treatment. Likewise, IL-4 stimulation of murine macrophages increased phagocytosis and killing of the parasite Trypanosoma cruzi (Wirth et al, 1989), but did not modify trophozoite uptake (Belosevic and Daniels, 1992). A recent paper indicated that the IL-4/STAT6 pathway limited the phagocytosis of small particles by the macrophages (Moreno et al, 2007).…”

Section: Effect On Endocytic and Phagocytic Pathway Referencesmentioning

confidence: 97%