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This Article Full Text (PDF) Data Supplement All Versions of this Article: jimmunol.0901220v1 183/10/6708    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Google Scholar Articles by Matsuwaki, Y. Articles by Kita, H. PubMed PubMed Citation Articles by Matsuwaki, Y. Articles by Kita, H.

Recognition of Fungal Protease Activities Induces Cellular Activation and Eosinophil-Derived Neurotoxin Release in Human Eosinophils¹

Yoshinori Matsuwaki,^2* Kota Wada,^2* Thomas A. White,^* Linda M. Benson, M. Cristine Charlesworth, James L. Checkel,^* Yoshinari Inoue,^* Kyoko Hotta,^3* Jens U. Ponikau, Christopher B. Lawrence, and Hirohito Kita^4*

*Department of Medicine and Immunology and Mayo Proteomics Research Center, Mayo Clinic, Rochester, MN 55905; Department of Clinical Otolaryngology, University at Buffalo, State University of New York, Buffalo, NY 14209; and Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060

Eosinophils are multifunctional leukocytes implicated in the pathogenesis of asthma and in immunity to certain organisms. Associations between exposure to an environmental fungus, such as Alternaria, and asthma have been recognized clinically. Protease-activated receptors (PARs) are G protein-coupled receptors that are cleaved and activated by serine proteases, but their roles in innate immunity remain unknown. We previously found that human eosinophils respond vigorously to Alternaria organisms and to the secretory product(s) of Alternaria with eosinophils releasing their proinflammatory mediators. In this study, we investigated the roles of protease(s) produced by Alternaria and of PARs expressed on eosinophils in their immune responses against fungal organisms. We found that Alternaria alternata produces aspartate protease(s) and that human peripheral blood eosinophils degranulate in response to the cell-free extract of A. alternata. Eosinophils showed an increased intracellular calcium concentration in response to Alternaria that was desensitized by peptide and protease ligands for PAR-2 and inhibited by a PAR-2 antagonistic peptide. Alternaria-derived aspartate protease(s) cleaved PAR-2 to expose neo-ligands; these neo-ligands activated eosinophil degranulation in the absence of proteases. Finally, treatment of Alternaria extract with aspartate protease inhibitors, which are conventionally used for HIV-1 and other microbes, attenuated the eosinophils' responses to Alternaria. Thus, fungal aspartate protease and eosinophil PAR-2 appear critical for the eosinophils' innate immune response to certain fungi, suggesting a novel mechanism for pathologic inflammation in asthma and for host-pathogen interaction.

⁴ Address correspondence and reprint requests to Dr. Hirohito Kita, Departments of Medicine and Immunology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905. E-mail address: kita.hirohito{at}mayo.edu

¹ This work was supported in part by Grants AI34486 and AI49235 from the National Institutes of Health and by the Mayo Foundation.

² Current address: Department of Otolaryngology, Jikei University School of Medicine, Tokyo, Japan 105-8461.

³ Current address: Kariya Toyota General Hospital, Aichi, Japan.