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Dectin‐2‐mediated signaling triggered by the cell wall polysaccharides of Cryptococcus neoformans
Author(s) -
Tanno Daiki,
Yokoyama Rin,
Kawamura Kotone,
Kitai Yuki,
Yuan Xiaoliang,
Ishii Keiko,
De Jesus Magdia,
Yamamoto Hideki,
Sato Ko,
Miyasaka Tomomitsu,
Shimura Hiroki,
Shibata Nobuyuki,
Adachi Yoshiyuki,
Ohno Naohito,
Yamasaki Sho,
Kawakami Kazuyoshi
Publication year - 2019
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/1348-0421.12746
Subject(s) - cryptococcus neoformans , mannose , biology , polysaccharide , microbiology and biotechnology , immune system , galactose , concanavalin a , tumor necrosis factor alpha , cell wall , biochemistry , in vitro , immunology
Cryptococcus neoformans is rich in polysaccharides of the cell wall and capsule. Dectin‐2 recognizes high‐mannose polysaccharides and plays a central role in the immune response to fungal pathogens. Previously, we demonstrated Dectin‐2 was involved in the activation of dendritic cells upon stimulation with C. neoformans , suggesting the existence of a ligand recognized by Dectin‐2. In the present study, we examined the cell wall structures of C. neoformans contributing to the Dectin‐2‐mediated activation of immune cells. In a NFAT‐GFP reporter assay of the reported cells expressing Dectin‐2, the lysates, but not the whole yeast cells, of an acapsular strain of C. neoformans (Cap67) delivered Dectin‐2‐mediated signaling. This activity was detected in the supernatant of β‐glucanase‐treated Cap67 and more strongly in the semi‐purified polysaccharides of this supernatant using ConA‐affinity chromatography (ConA‐bound fraction), in which a large amount of saccharides, but not protein, were detected. Treatment of this supernatant with periodic acid and the addition of excessive mannose, but not glucose or galactose, strongly inhibited this activity. The ConA‐bound fraction of the β‐glucanase‐treated Cap67 supernatant was bound to Dectin‐2‐Fc fusion protein in a dose‐dependent manner and strongly induced the production of interleukin‐12p40 and tumour necrosis factor‐α by dendritic cells; this was abrogated under the Dectin‐2‐deficient condition. Finally, 98 kDa mannoprotein (MP98) derived from C. neoformans showed activation of the reporter cells expressing Dectin‐2. These results suggested that a ligand with mannose moieties may exist in the cell walls and play a critical role in the activation of dendritic cells during infection with C. neoformans .