Related Experiment Videos
Resistance of nematode secretory products to cleavage by mast cell proteinases
Abstract:
Mast cell proteinases are known to be released in response to helminth infection, and are, in particular, characteristic of the immune rejection of intestinal nematode parasites. In intestinal mucosal tissue the relevant enzyme is rat mast cell proteinase II (RMCP II) and that of other tissues, including the lung, is rat mast cell proteinase I (RMCP I). The function of these enzymes is unknown, and we have examined the possibility that they directly attack the parasites. This was done by examining the cleavage patterns produced by both proteinases on 125I-labelled excretory/secretory (ES) products of two intestinal nematodes (the infective larva of Ascaris suum, and adult Nippostrongylus brasiliensis) and one which has a pulmonary migration route (the third/fourth stage larva of A. suum). It was first established that all the labelled molecules were proteinaceous, by their susceptibility to broad spectrum proteinases, and that none were host components carried over into culture, by their antigenicity to infected hosts. All the nematode ES products were found to be remarkably resistant to RMCP I and II, only one major component of the infective larva of A. suum being cleaved by both enzymes. This was not found to reflect a resistance to serine proteinases in general, since selected ES components were cleaved by chymotrypsin and trypsin. This would, therefore, argue that, if the enzymes play any direct role in the immune expulsion of nematodes, it is unlikely to be successfully directed at their secretions.
Insights
Rat mast cell proteinases (RMCP I and II) do not effectively degrade helminth parasite secretions. This suggests these enzymes may not directly attack parasite excretory/secretory products during immune responses.
Area of Science:
- Immunology
- Parasitology
- Biochemistry
Background:
- Mast cell proteinases, specifically rat mast cell proteinase I (RMCP I) and rat mast cell proteinase II (RMCP II), are released during helminth infections.
- These enzymes are particularly associated with the immune rejection of intestinal nematode parasites.
Purpose of the Study:
- To investigate the functional role of RMCP I and RMCP II in combating helminth infections.
- To determine if these mast cell proteinases directly attack nematode parasites by degrading their excretory/secretory (ES) products.
Main Methods:
- The study utilized 125I-labelled ES products from three nematode species: Ascaris suum (intestinal and lung-stage larvae) and Nippostrongylus brasiliensis (adult).
- Proteinase cleavage patterns were analyzed using RMCP I and RMCP II.
- The proteinaceous nature and non-host origin of ES products were confirmed using broad-spectrum proteinases and host antigenicity tests, respectively.
- Susceptibility to other serine proteinases (chymotrypsin, trypsin) was also assessed.
Main Results:
- Nematode ES products demonstrated significant resistance to degradation by both RMCP I and RMCP II.
- A single major component from Ascaris suum infective larvae was found to be cleaved by both RMCP I and RMCP II.
- This resistance was not general to serine proteinases, as other ES components were susceptible to chymotrypsin and trypsin.
Conclusions:
- The findings suggest that RMCP I and RMCP II are unlikely to play a direct role in the immune expulsion of nematodes by targeting their secreted products.
- The observed resistance of ES products implies alternative mechanisms of immune defense against these parasites may be more significant.