FleA Expression in Aspergillus fumigatus Is Recognized by Fucosylated Structures on Mucins and Macrophages to Prevent Lung Infection
Fig 6
Inhibition of FleA by 2EHex or fucose results in a loss of mucin binding and greatly reduced phagocytosis by macrophages.
(A) Structures of fucopyranoside compounds. (B) Amount of compound required to inhibit binding of labeled FleA to mucin by 50% (IC50 [μM]). Addition of a methyl or allyl group to the anomeric position of fucose (methyl α-L-fucopyranoside, allyl α-L-fucopyranoside) improves inhibition by 2–4 fold but inclusion of a longer (6-carbon) unsaturated chain improves inhibition by 3 orders of magnitude. Removing the double bond or extending the carbon chain beyond 6 carbons (hexyl α-L-fucopyranoside, (2E)-octenyl α-L-fucopyranoside) markedly decreases inhibition. (2E)-hexenyl α-D-galactopyranoside has no effect on FleA binding to mucin. (C) Amount of compound required to inhibit PAIIL binding to mucin by 50% (IC50 [μM]). 2EHex does not have a strong inhibitory effect on PAIIL-mucin interactions. (D) Inhibiting WT conidia with 10mM 2EHex or 100mM fucose significantly reduced binding of conidia to mucin. WT conidia were poorly phagocytosed in the presence of 2EHex or fucose by RAW264.7 cells (E) or primary human macrophages (F). The data shown in D and E (6 replicates) reflects the mean ± SD of three independent experiments whereas the data in panel F (6 replicates) reflects the mean ± SD of three independent donors. *Denotes significantly different from control, p = <0.05.