Related Experiment Videos
Control of host complement activation by the Echinococcus granulosus hydatid cyst
A Díaz1, F Irigoín, F Ferreira
1MRC Immunochemistry Unit, Department of Biochemistry, University of Oxford, UK.
Insights
Cystic hydatid disease, caused by Echinococcus granulosus, involves a parasite cyst that surprisingly avoids triggering a strong immune response. This study identifies a heat-stable parasite inhibitor that prevents complement factor B activation, explaining the cyst
Area of Science:
- Immunology
- Parasitology
- Biochemistry
Background:
- Cystic hydatid disease, caused by Echinococcus granulosus, presents a unique immunological challenge.
- Hydatid cysts are large, antigenic structures that typically induce minimal host inflammation, contrary to expectations.
- The host-exposed hydatid cyst wall (HCW) is known to poorly activate the complement system, a key immune pathway.
Purpose of the Study:
- To investigate the mechanisms by which the hydatid cyst wall (HCW) evades robust complement system activation.
- To identify and characterize the specific factors within the HCW responsible for its complement-inhibitory properties.
Main Methods:
- Comprehensive survey of complement inhibitory mechanisms associated with the hydatid cyst wall (HCW).
- Focus on identifying non-protein, heat-stable inhibitors.
- Detailed analysis of inhibitors targeting host complement factor B activation.
Main Results:
- The hydatid cyst wall (HCW) possesses multiple mechanisms for inhibiting complement activation.
- A significant finding is a non-protein, heat-stable molecule that directly inhibits the activation of host complement factor B.
- This inhibitor plays a crucial role in rendering the parasite cyst 'complement-inert'.
Conclusions:
- The Echinococcus granulosus parasite employs sophisticated strategies to evade host immune responses.
- A novel, heat-stable, non-protein inhibitor of complement factor B activation is a key mechanism for immune evasion.
- Understanding these mechanisms offers insights into host-parasite interactions and potential therapeutic targets.
Abstract:
Cystic hydatid disease is caused by the multicellular parasite Echinococcus granulosus. The hydatid cyst, being a long-lived, large, antigenic structure lodged in the host's internal organs, could potentially elicit major inflammatory responses. However, in practice, the cyst causes only minimal local inflammation. The complement system is a major pathway to immune-mediated inflammation. Recent results have shown that the host-exposed structure of the cyst, the hydatid cyst wall (HCW), fails to trigger the complement system strongly. We have carried out a wide survey for the mechanisms making the cyst wall relatively complement-inert. The results of those studies are summarised in this work, with emphasis on the most recently identified of the complement inhibitory mechanisms. This is based on a non-protein heat-stable, parasite inhibitor of the activation of host complement factor B.