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Generation of anaphylatoxins through proteolytic processing of C3 and C5 by house dust mite protease
1Department of Microbiology, Kumamoto University School of Medicine, Japan.
Background:
The group 3 allergen of Dermatophagoides species (Der p 3 and Der f 3) has been identified as a 30 kd trypsin-like protease of the house dust mite. We previously showed that the 30 kd protease from Dermatophagoides farinae (Df-protease) could activate the bradykinin-generating cascade and exacerbate inflammatory reactions.
Objective:
The purpose of this study was to determine whether Df-protease could enzymatically generate anaphylatoxins from complement components C3 and C5.
Methods:
Df-protease was incubated with human serum C3 or C5 in a purified system, and the anaphylatoxin activity produced was assayed by measuring enhancement of vascular permeability and release of histamine from mast cells triggered by C3a and by assessing chemotaxis of polymorphonuclear cells caused by C5a. We also attempted to determine whether protease isolated from house dust could cause release of C5a from C5.
Results:
Df-protease showed strong activation of C3 and C5, producing C3a and C5a by proteolytic cleavage of the complements. An appreciable amount of Df-protease was recovered in the house dust extract, and the house dust protease caused C5a release from C5.
Conclusion:
Df-protease activated the complement system to produce anaphylatoxins. Thus it is suggested that house dust mite proteases may contribute to the pathogenesis of allergic and inflammatory diseases caused by house dust allergens.
Insights
House dust mite proteases, like Der f 3, activate the complement system to produce anaphylatoxins (C3a and C5a). This suggests a role for these proteases in allergic and inflammatory diseases.
Area of Science:
- Immunology
- Allergy Research
- Protease Biochemistry
Background:
- Group 3 allergens from Dermatophagoides species, Der p 3 and Der f 3, are trypsin-like proteases.
- Previous research demonstrated that Dermatophagoides farinae protease (Df-protease) activates the bradykinin cascade and exacerbates inflammation.
Purpose of the Study:
- To investigate if Df-protease can enzymatically generate anaphylatoxins from complement components C3 and C5.
- To determine the role of house dust mite proteases in activating the complement system.
Main Methods:
- Incubation of purified Df-protease with human serum C3 or C5.
- Assay of anaphylatoxin activity by measuring vascular permeability and histamine release (for C3a).
- Assessment of polymorphonuclear cell chemotaxis (for C5a) and C5a release from C5 by house dust protease.
Main Results:
- Df-protease demonstrated potent activation of C3 and C5 through proteolytic cleavage, generating C3a and C5a.
- House dust extracts contained Df-protease, which induced C5a release from C5.
- Anaphylatoxin activity was confirmed through biological assays.
Conclusions:
- Df-protease activates the complement system, producing anaphylatoxins C3a and C5a.
- House dust mite proteases are implicated in the pathogenesis of allergic and inflammatory conditions.
- These findings highlight a mechanism by which house dust mite allergens contribute to disease.
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