Neutrophil Extracellular Traps Contain Calprotectin, a Cytosolic Protein Complex Involved in Host Defense against Candida albicans

PLoS Pathogens

Wolfgang Nacken¹  Constantin F. Urban¹  David Ermert¹  Ulrike Abu-Abed¹  Peter R. Jungblut²  Arturo Zychlinsky³  Volker Brinkmann⁴  Christian Goosmann⁴  Monika Schmid⁵ 

[1] Department for Cellular Microbiology, Max Planck Institute for Infection Biology, Berlin, Germany;Institute for Immunology, Münster University, Münster, Germany;Institute for Molecular Virology, Center for Molecular Biology of Inflammation, Münster University, Münster, Germany;Microscopy Core Facility, Max Planck Institute for Infection Biology, Berlin, Germany;Protein Analysis Core Facility, Max Planck Institute for Infection Biology, Berlin, Germany

关键词: Neutrophils;    C;    ida albicans;    Histones;    Antifungals;    Immunoblotting;    Abscesses;    DNA-binding proteins;    Cytoplasmic staining;   

DOI  :  10.1371/journal.ppat.1000639

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Neutrophils are the first line of defense at the site of an infection. They encounter and kill microbes intracellularly upon phagocytosis or extracellularly by degranulation of antimicrobial proteins and the release of Neutrophil Extracellular Traps (NETs). NETs were shown to ensnare and kill microbes. However, their complete protein composition and the antimicrobial mechanism are not well understood. Using a proteomic approach, we identified 24 NET-associated proteins. Quantitative analysis of these proteins and high resolution electron microscopy showed that NETs consist of modified nucleosomes and a stringent selection of other proteins. In contrast to previous results, we found several NET proteins that are cytoplasmic in unstimulated neutrophils. We demonstrated that of those proteins, the antimicrobial heterodimer calprotectin is released in NETs as the major antifungal component. Absence of calprotectin in NETs resulted in complete loss of antifungal activity in vitro. Analysis of three different Candida albicans in vivo infection models indicated that NET formation is a hitherto unrecognized route of calprotectin release. By comparing wild-type and calprotectin-deficient animals we found that calprotectin is crucial for the clearance of infection. Taken together, the present investigations confirmed the antifungal activity of calprotectin in vitro and, moreover, demonstrated that it contributes to effective host defense against C. albicans in vivo. We showed for the first time that a proportion of calprotectin is bound to NETs in vitro and in vivo.

【 授权许可】

CC BY