Chemical Synthesis and Application of Biotinylated Oligo-α-(1 → 3)-d-Glucosides To Study the Antibody and Cytokine Response against the Cell Wall α-(1 → 3)-d-Glucan of Aspergillus fumigatus

Abstract

Biotinylated hepta-, nona- and undeca-α-(1 → 3)-d-glucosides representing long oligosaccharides of α-(1 → 3)-d-glucan, one of the major components of the cell walls of the fungal pathogen Aspergillus fumigatus, were synthesized for the first time via a blockwise strategy. Convergent assembly of the α-(1 → 3)-d-glucan chains was achieved by glycosylation with oligoglucoside derivatives bearing 6-O-benzoyl groups. Those groups are capable of remote α-stereocontrolling participation, making them efficient α-directing tools even in the case of large glycosyl donors. Synthetic biotinylated oligoglucosides (and biotinylated derivatives of previously synthesized tri- and penta-α-(1 → 3)-d-glucosides) loaded on streptavidin microtiter plates were shown to be better recognized by anti-α-(1 → 3)-glucan human polyclonal antibodies and to induce higher cytokine responses upon stimulation of human peripheral blood mononuclear cells than their natural counterpart, α-(1 → 3)-d-glucan, immobilized on a conventional microtiter plate. Attachment of the synthetic oligosaccharides equipped with a hydrophilic spacer via the streptavidin–biotin pair allows better spatial presentation and control of the loading compared to the random sorption of natural α-(1 → 3)-glucan. Increase of oligoglucoside length results in their better recognition and enhancement of cytokine production. Thus, using synthetic α-(1 → 3)-glucan oligosaccharides, we developed an assay for the host immune response that is more sensitive than the assay based on native α-(1 → 3)-glucan.

Importance of Candida Antigenic Factors: Structure-Driven Immunomodulation Properties of Synthetically Prepared Mannooligosaccharides in RAW264.7 Macrophages

“…Next, a novel tetrasaccharide construct consisting of β-1,2-mannopyranosyl trisaccharide and α-mannopyranoside was designed and suggested as a model of the C. albicans phosphodiester epitope (Dang et al, 2012). Glycoarrays formed by biotinylated oligosaccharides loaded on streptavidin-coated surfaces were previously shown to be indispensable instruments for the investigation of carbohydrate antigen recognition by immune cells (Komarova et al, 2015, 2018; Akhmatova et al, 2016; Paulovicova et al, 2016, 2017; Kurbatova et al, 2017; Argunov et al, 2019; Schubert et al, 2019).…”

Novel mouse monoclonal antibodies specifically recognizing β-(1→3)-D-glucan antigen

“…The wells of 96-well Pierce streptavidin-coated plates were coated with 20 pmol/well of appropriate linear ( G1 - G13 ) and branched ( brG3 , brG6-I, brG6-II, brG8 ) biotin-tagged oligosaccharides (Fig 2) in 100 μL of wash buffer and then incubated for 2 h at 37°C as previously described [20,23,24]. After washing three times with wash buffer, the plates were incubated with mAbs 5H5 and 3G11 diluted in wash buffer (concentration 63, 8.0 ng/mL) for 1 h at 37°C.…”

Mannan detecting C-type lectin receptor probes recognise immune epitopes with diverse chemical, spatial and phylogenetic heterogeneity in fungal cell walls

“…In Candida species the outer wall is dominated by a fibrillar layer of highly glycosylated cell wall proteins that are extensively decorated with N-and O-linked mannans and phosphomannans [17,18]. The chemical fingerprint of the fungal cell wall mannans are used to identify medically relevant species in diagnostic tests [19][20][21]. However, within a species the composition of the cell wall is highly variable and changes according to morphology, growth stage, nutrient availability, the presence of antibiotics and other environmental stressors [15,[22][23][24][25].…”