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Dose-dependent effects of hydatid fluid toxins from Echinococcus granulosus on mouse peritoneal macrophages
D Janssen1, P H De Rycke, A Osuna
1Laboratorium voor Zoöfysiologie, Universiteit Gent, Belgium.
Abstract:
Hydatid fluid (HF) from hydatid cysts of the cestode Echinococcus granulosus inhibited the phagocytosis of bacteria and yeast cells by host macrophages in vitro. Different assays were used to study the dose-dependent effect of partially purified HF toxins on peritoneal macrophages (PM phi) of the mouse. Trypan blue exclusion, as well as measuring the specific release of lactate dehydrogenase activity and 51Cr release of 51Cr-labelled PM phi, showed that incubation with HF toxins lead to the lysis of the target cells. By measuring the effect of the toxins on the reduction of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide by PM phi, and by experimental labelling using [3H]-uridine, a decrease in metabolic activity was seen. However, at non-lytic concentrations, the PM phi showed a peak of metabolic activity. The observations of the effects on macrophages by parasite-derived toxins may be related to a mechanism by which the parasite survives within an immunized host.
Insights
Hydatid fluid from Echinococcus granulosus parasites impairs host macrophage function, inhibiting bacterial and yeast cell phagocytosis. These parasite toxins cause macrophage lysis and alter metabolic activity, potentially aiding parasite survival.
Area of Science:
- Immunology
- Parasitology
- Cell Biology
Background:
- Hydatid fluid (HF) is produced by Echinococcus granulosus, a parasitic cestode.
- Host macrophages are crucial immune cells responsible for phagocytosis.
- Parasitic infections often involve complex interactions to evade host immunity.
Purpose of the Study:
- To investigate the effects of Echinococcus granulosus hydatid fluid toxins on mouse peritoneal macrophages (PM phi).
- To determine the impact of these toxins on macrophage phagocytic activity, viability, and metabolic function.
Main Methods:
- Dose-dependent assays were performed using partially purified HF toxins.
- Macrophage viability was assessed using Trypan blue exclusion and lactate dehydrogenase (LDH) release.
- Cell lysis was measured by 51Cr release from labeled PM phi.
- Metabolic activity was evaluated using MTT assays and [3H]-uridine incorporation.
Main Results:
- HF toxins inhibited the phagocytosis of bacteria and yeast cells by PM phi.
- Incubation with HF toxins led to significant lysis of PM phi, confirmed by LDH and 51Cr release.
- A decrease in PM phi metabolic activity was observed at higher toxin concentrations.
- Non-lytic concentrations of HF toxins paradoxically increased PM phi metabolic activity.
Conclusions:
- Parasite-derived toxins in hydatid fluid directly impair host macrophage functions, including phagocytosis and viability.
- These toxins may represent a mechanism by which Echinococcus granulosus evades the host immune system, particularly in immunized hosts.
- Understanding these interactions is crucial for developing strategies against echinococcosis.