Inhibition of asthma by mutant fungal protease allergen

Abstract

Asthma is a chronic inflammatory disease of the lower airways characterized by recurrent airway obstruction and wheezing. There are several causes of asthma. In immunological aspect, the main cause of asthma is an allergen such as secretions from house dust mite, fungal protease, pollen. One of the most important allergen is proteases from fungi. The activity of protease is thought to be important to induce the Th2-mediated immune response. Generally, protease activity of Aspergillus oryzae is high enough to develop allergic asthma. I secured the cDNA of wild type A. oryzae protease, then mutated active sites of A. oryzae protease and optimized codon for bacterial expression. The mutant A. oryzae protease could be induced the expression of 46.7 kDa sized protein in $16$T_H2$ for 16h under 0.2-0.4 mM of IPTG. The A. oryzae protease was purified by using the $Ni^{2+}$ His binding bead column. Purified mutant A. oryzae protease was being lost protease activity and used to induce allergic asthma in mouse model. In the group of mice administrated by mutant protease, lung inflammation and bronchoalveolar lavage (BAL) eosinophilia were significantly lowered com-pared to a group of mice which was administrated with wild type Aspergillus protease (AP). Furthermore, airway hyper-responsiveness (AHR), total BAL cell counts and BAL glycoprotein secretion were significantly lowered with administration of mutant protease. Immune tolerance rather than immune stimulation was detected in mutant protease administered group. Inactivated A. oryzae protease can control the differentiation and function of helper T cell and eventually reduce allergic asthma. In the future, I expect to develop asthma vaccine by manipulating protease activity.