Amphotericin B mediates killing in Cryptococcus neoformans through the induction of a strong oxidative burst

作者：Sangalli Leite Fernanda; Scorzoni Liliana; Cecilia Mesa Arango Ana; Casas Celia; Herrero Enrique; Mendes Gianinni Maria Jose Soares; Luis Rodriguez Tudela Juan; Cuenca Estrella Manuel; Zaragoza Oscar^*

来源：Microbes and Infection, 2011, 13(5): 457-467.

DOI：10.1016/j.micinf.2011.01.015

• Cryptococcus neoformans
• Amphotericin B
• Oxidative burst
• XTT
• Propidium iodide

We studied the effects of Amphotericin B (AmB) on Cryptococcus neoformans using different viability methods (CFUs enumeration, XTT assay and propidium iodide permeability). After 1 h of incubation, there were no viable colonies when the cells were exposed to AmB concentrations >= 1 mg/L. In the same conditions, the cells did not become permeable to propidium iodide, a phenomenon that was not observed until 3 h of incubation. When viability was measured in parallel using XTT assay, a result consistent with the CFUs was obtained, although we also observed a paradoxical effect in which at high AmB concentrations, a higher XTT reduction was measured than at intermediate AmB concentrations. This paradoxical effect was not observed after 3 h of incubation with AmB, and lack of XTT reduction was observed at AmB concentrations higher than 1 mg/L. When stained with dihydrofluorescein, AmB induced a strong intracellular oxidative burst. Consistent with oxidative damage, AmB induced protein carbonylation. Our results indicate that in C. neoformans, Amphotericin B causes intracellular damage mediated through the production of free radicals before damage on the cell membrane, measured by propidium iodide uptake.

• 出版日期2011-5