Maruo K, Akaike T, Ono T, Okamoto T, Maeda H
Department of Microbiology, Kumamoto University School of Medicine, Japan.
J Allergy Clin Immunol. 1997 Aug;100(2):253-60. doi: 10.1016/s0091-6749(97)70233-1.
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.
The purpose of this study was to determine whether Df-protease could enzymatically generate anaphylatoxins from complement components C3 and C5.
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.
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.
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.
粉尘螨属第3组变应原（Der p 3和Der f 3）已被鉴定为屋尘螨的一种30kd胰蛋白酶样蛋白酶。我们之前表明，来自粉尘螨的30kd蛋白酶（Df-蛋白酶）可激活缓激肽生成级联反应并加剧炎症反应。
本研究旨在确定Df-蛋白酶是否能通过酶促作用从补体成分C3和C5产生过敏毒素。
在纯化系统中将Df-蛋白酶与人血清C3或C5孵育，通过测量C3a触发的血管通透性增强和肥大细胞组胺释放来测定产生的过敏毒素活性，并通过评估C5a引起的多形核细胞趋化性来进行测定。我们还试图确定从屋尘中分离的蛋白酶是否能导致C5释放C5a。
Df-蛋白酶对C3和C5有强烈激活作用，通过对补体进行蛋白水解切割产生C3a和C5a。在屋尘提取物中回收了相当数量的Df-蛋白酶，且屋尘蛋白酶可使C5释放C5a。
Df-蛋白酶激活补体系统产生过敏毒素。因此提示屋尘螨蛋白酶可能在屋尘变应原引起的变应性和炎性疾病发病机制中起作用。
