Enzymatic activity in extracts of allergy-causing astigmatid mites

Many of the previously characterized allergens of house dust mites are known to be proteases, and this enzymatic activity is thought to contribute to their allergenicity. Other astigmatid mites, including stored-product mites and the ectoparasitic itch mite, Sarcoptes scabiei De Geer, are also known to be allergenic, but little or nothing is known about their enzymatic activities. The purpose of this study was to characterize the enzymatic activities present in extracts of the parasitic itch mite and from eight other species of free-living astigmatid mites. Extracts were prepared from one parasitic mite (S. scabiei), five stored-product mites (Chortoglyphus arcuatus (Troupeau), Lepidoglyphus destructor (Schrank), Blomia tropicalis Bronswijk, Cock, Oshima, Tyrophagus putrescentiae (Schrank), and Acarus siro L.), and three house dust mites [Dermatophagoidesfarinae Hughes, Dermatophagoides pteronyssinus (Troussart), and Euroglyphus maynei (Cooreman) ]. ApiZym strips were used to screen for the presence of 19 individual enzyme activities. Digestion of nine other substrates was evaluated by spectrophotometric or electrophoretic methods. All mite extracts exhibited some form of phosphatase, esterase, aminopeptidase, and glycosidase activity, although their substrate specificities varied considerably. Itch mite extract did not possess detectable serine peptidase activity nor was it able to hydrolyze gelatin or casein, whereas all other mite extracts exhibited these activities. Storage mite extracts possessed enzymes capable of degrading the widest range of substrates, whereas itch mite extract had the most limited proteolytic capacity. Extracts of nine species of allergy-causing astigmatid mites contain wide and diverse repertoires of enzymatic activities. These catalytic activities may be important contributors to the induction and manifestation of inflammatory and immune responses to mites in patients.