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Innate function of house dust mite allergens: robust enzymatic degradation of extracellular matrix at elevated pH
Kumiko Oida1,2, Lukas Einhorn1, Ina Herrmann1,3
1The interuniversity Messerli Research Institute of the University of Veterinary Medicine Vienna, Medical University Vienna and University Vienna, Veterinaerplatz 1, 1210 Vienna, Austria.
Background:
Exposure to the house dust mite Dermatophagoides pteronyssinus (D.p.) increases the risk for developing allergic diseases in humans and their best friends, the dogs. Here, we explored whether this allergenic mite via its enzymes may impact the cutaneous extracellular matrix (ECM), which critically determines epithelial barrier integrity both structurally and functionally.
Methods:
Two extracts obtained from either dust-purified or cultured D.p. bodies were used in the present study. To assess the potential impact of D.p. on protein components of the ECM, proteolytic activity of the D.p. extracts were determined by casein and gelatin gel zymography, and their N-acetyl-β-hexosaminidase activity determined colorimetrically. In addition, IgE-dependent and innate degranulation potential of D.p. was examined in canine MPT-1 mast cells and neurite outgrowth assay using rat pheochromocytoma PC-12 cells.
Results:
In gel zymography, both extracts digested the substrates casein and gelatin in a dose-dependent manner, especially at alkaline pH, and effective in a wide range of temperatures (30 °C-42 °C). In particular, a 25-kDa band corresponding to Der p 1, the major D.p. allergen for humans, was found enzymatically active in both casein and gelatin gels regardless of the presence of metal ions and of alkaline conditions. Besides protease activity, N-acetyl-β-hexosaminidase activity was detected in both extracts, suggesting that D.p. affects the cutaneous ECM through deteriorating both proteins and glycosaminoglycans. While both D.p. extracts induced IgE-dependent mast cell degranulation, much less innate effects on mast- and neuronal cells were observed.
Conclusions:
Our data highlight that D.p. is a robust source of several distinct enzymes with protease- and N-acetyl-β-hexosaminidase activities. In alkaline milieu they can degrade components of the ECM. Therefore, D.p. may contribute to epithelial barrier disruption especially when the skin surface pH is elevated.
Insights
House dust mite (Dermatophagoides pteronyssinus) enzymes degrade skin extracellular matrix proteins and glycosaminoglycans. This protease and N-acetyl-β-hexosaminidase activity can disrupt the epithelial barrier, particularly at alkaline pH.
Area of Science:
- Dermatology
- Allergology
- Biochemistry
Background:
- House dust mite (Dermatophagoides pteronyssinus) exposure is linked to allergic diseases in humans and dogs.
- The house dust mite's enzymes may impact the skin's extracellular matrix (ECM), crucial for epithelial barrier integrity.
Purpose of the Study:
- To investigate the enzymatic impact of Dermatophagoides pteronyssinus (D.p.) on the cutaneous extracellular matrix (ECM).
- To assess D.p. enzymes' role in epithelial barrier function and potential contribution to allergic skin conditions.
Main Methods:
- Proteolytic activity of D.p. extracts was assessed using casein and gelatin zymography.
- N-acetyl-β-hexosaminidase activity was measured colorimetrically.
- IgE-dependent and innate degranulation of mast and neuronal cells by D.p. extracts were examined.
Main Results:
- D.p. extracts demonstrated dose-dependent protease activity against casein and gelatin, especially at alkaline pH and moderate temperatures.
- The major allergen Der p 1 showed enzymatic activity, degrading ECM components.
- Both protease and N-acetyl-β-hexosaminidase activities were detected, indicating degradation of proteins and glycosaminoglycans.
- D.p. induced IgE-dependent mast cell degranulation but had minimal innate effects on mast and neuronal cells.
Conclusions:
- Dermatophagoides pteronyssinus possesses potent protease and N-acetyl-β-hexosaminidase enzymes.
- These enzymes degrade ECM components, particularly in alkaline conditions.
- D.p. can contribute to epithelial barrier disruption when skin surface pH is elevated.
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