AUTHOR=Dasari Prasad , Shopova Iordana A. , Stroe Maria , Wartenberg Dirk , Martin-Dahse Hans , Beyersdorf Niklas , Hortschansky Peter , Dietrich Stefanie , Cseresnyés Zoltán , Figge Marc Thilo , Westermann Martin , Skerka Christine , Brakhage Axel A. , Zipfel Peter F. 

TITLE=Aspf2 From Aspergillus fumigatus Recruits Human Immune Regulators for Immune Evasion and Cell Damage

JOURNAL=Frontiers in Immunology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2018.01635

DOI=10.3389/fimmu.2018.01635

ISSN=1664-3224

ABSTRACT=<p>The opportunistic fungal pathogen <italic>Aspergillus fumigatus</italic> can cause life-threatening infections, particularly in immunocompromised patients. Most pathogenic microbes control host innate immune responses at the earliest time, already before infiltrating host immune cells arrive at the site of infection. Here, we identify Aspf2 as the first <italic>A. fumigatus</italic> Factor H-binding protein. Aspf2 recruits several human plasma regulators, Factor H, factor-H-like protein 1 (FHL-1), FHR1, and plasminogen. Factor H contacts Aspf2 <italic>via</italic> two regions located in SCRs6–7 and SCR20. FHL-1 binds <italic>via</italic> SCRs6–7, and FHR1 <italic>via</italic> SCRs3–5. Factor H and FHL-1 attached to Aspf2-maintained cofactor activity and assisted in C3b inactivation. A Δ<italic>aspf2</italic> knockout strain was generated which bound Factor H with 28% and FHL-1 with 42% lower intensity. In agreement with less immune regulator acquisition, when challenged with complement-active normal human serum, Δ<italic>aspf2</italic> conidia had substantially more C3b (&gt;57%) deposited on their surface. Consequently, Δ<italic>aspf2</italic> conidia were more efficiently phagocytosed (&gt;20%) and killed (44%) by human neutrophils as wild-type conidia. Furthermore, Aspf2 recruited human plasminogen and, when activated by tissue-type plasminogen activator, newly generated plasmin cleaved the chromogenic substrate S2251 and degraded fibrinogen. Furthermore, plasmin attached to conidia damaged human lung epithelial cells, induced cell retraction, and caused matrix exposure. Thus, Aspf2 is a central immune evasion protein and plasminogen ligand of <italic>A. fumigatus</italic>. By blocking host innate immune attack and by disrupting human lung epithelial cell layers, Aspf2 assists in early steps of fungal infection and likely allows tissue penetration.</p>