Protease-activated receptor-2 signaling through β-arrestin-2 mediates Alternaria alkaline serine protease-induced airway inflammation

• Published in: American journal of physiology. Lung cellular and molecular physiology 2018-12, Vol.315 (6), p.L1042-L1057
• Main Authors: Yee, Michael C, Nichols, Heddie L, Polley, Danny, Saifeddine, Mahmoud, Pal, Kasturi, Lee, Kyu, Wilson, Emma H, Daines, Michael O, Hollenberg, Morley D, Boitano, Scott, DeFea, Kathryn A
• Format: Article
• Language: English
• Subjects: Airway management; Allergens; Allergens - metabolism; Animal models; Animals; Arrestin; Asthma; Asthma - metabolism; Bacterial Proteins - metabolism; beta-Arrestin 2 - metabolism; Endopeptidases - metabolism; Hyperplasia; Inflammation; Inflammation - metabolism; Intranasal administration; Leukocytes (eosinophilic); Lung - metabolism; Mice; Mice, Inbred C57BL; Mucin; Par-2 protein; Phenotypes; Proteases; Receptor, PAR-2 - metabolism; Respiratory tract; Respiratory tract diseases; Serine; Serine - metabolism; Serine Endopeptidases - metabolism; Serine Proteases - metabolism; Serine proteinase; Signal Transduction - physiology; Therapeutic applications; Trypsin
• ISSN: 1040-0605; 1931-857X; 1522-1504; 1522-1466
• DOI: 10.1152/ajplung.00196.2018

Alternaria alternata is a fungal allergen associated with severe asthma and asthma exacerbations. Similarly to other asthma-associated allergens, Alternaria secretes a serine-like trypsin protease(s) that is thought to act through the G protein-coupled receptor protease-activated receptor-2 (PAR ) to induce asthma symptoms. However, specific mechanisms underlying Alternaria-induced PAR activation and signaling remain ill-defined. We sought to determine whether Alternaria-induced PAR signaling contributed to asthma symptoms via a PAR /β-arrestin signaling axis, identify the protease activity responsible for PAR signaling, and determine whether protease activity was sufficient for Alternaria-induced asthma symptoms in animal models. We initially used in vitro models to demonstrate Alternaria-induced PAR /β-arrestin-2 signaling. Alternaria filtrates were then used to sensitize and challenge wild-type, PAR and β-arrestin-2 mice in vivo. Intranasal administration of Alternaria filtrate resulted in a protease-dependent increase of airway inflammation and mucin production in wild-type but not PAR or β-arrestin-2 mice. Protease was isolated from Alternaria preparations, and select in vitro and in vivo experiments were repeated to evaluate sufficiency of the isolated Alternaria protease to induce asthma phenotype. Administration of a single isolated serine protease from Alternaria, Alternaria alkaline serine protease (AASP), was sufficient to fully activate PAR signaling and induce β-arrestin-2 -dependent eosinophil and lymphocyte recruitment in vivo. In conclusion, Alternaria filtrates induce airway inflammation and mucus hyperplasia largely via AASP using the PAR /β-arrestin signaling axis. Thus, β-arrestin-biased PAR antagonists represent novel therapeutic targets for treating aeroallergen-induced asthma.