engleski

Antifungal activity of galectin-3 against black Aspergilli

Objectives. The Aspergillus section Nigri comprises several species widely distributed in the environment. Apart from their use in food production and biotechnology, many species are plant pathogens, mycotoxin (ochratoxin A and fumonisins) producers, and causative agents of respiratory infections in immunocompromised patients as well as otomycosis and keratomycosis in tropical and subtropical regions. Galectin-3 (Gal-3), an animal lectin, is a pleiotropic protein that primarily binds to lactose and it is involved in a variety of cellular processes including interaction with pathogens, immune response and cell death. Several studies indicated possible antimicrobial action of Gal-3 against bacteria and yeasts but antifungal activity against filamentous fungi such as Aspergilli is not known. The aim of this study was to test antifungal activity of Gal-3 in comparison to amphotericin B (AMB) against A. brasiliensis ATCC 16404 and 5 airborne species of black Aspergilli (A. piperis, A. tubingensis, A. welwitchiae, A. niger, A. luchuensis). Methods. A modified broth dilution method for susceptibility testing against Aspergillus (EUCAST-AST-ASPERGILLUS) was employed in this study. Dilutions of AMB (0.015-16 g/mL) and Gal-3 (8-520 g/mL) in RPMI 1640 with 2% glucose inoculated with conidial suspension of black Aspergilli (1-2, 5x105 CFU/mL) were incubated for 48 h at 35°C. Upon incubation MTS reagent was added and plates were incubated for 3 h at at 35°C. The absorbance was measured using a microplate reader (Labsystem iEMS, type 1404) at a wavelength of 492 nm. All tests were performed in triplicate and viability of Aspergilli was expressed as percentage of control (untreated Aspergilli). Results. According to minimum inhibitory concentration (MIC) of AMB, A. brasiliensis ATCC 16404 (1 g/mL) followed by A. piperis (0.5 g/mL) were the most resistant black Aspergilli. MIC of AMB for the rest of tested strains was 0.25 g/mL. Opposite to AMB, Gal-3 was efficient only against A. brasiliensis strain (520 g/mL). All applied concentrations of Gal-3 decreased viability of A. piperis by 30%, while other black Aspergilli were resistant to Gal-3. Conclusion. Our preliminary results shows that Gal-3 may have antifungal activity against black Aspergilli that is species related and does not involve binding to ergosterol.

black Aspergilli, galectin-3, amphotericin, EUCAST method

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