Improved In Vitro Anti-Mucorales Activity and Cytotoxicity of Amphotericin B with a Pegylated Surfactant.

Kévin Brunet,Sandrine Marchand,Cheikh A. B. Diop,Blandine Rammaert,Noémie Prébonnaud,Alexia Chauzy,Frédéric Tewes

doi:10.3390/jof8020121

Abstract

The aim of this study was to evaluate the effect of the combination of amphotericin B (AmB) and various non-ionic surfactants on the anti-Mucorales activity of AmB, the toxicity of the combination on eukaryotic cells and the modification of AmB aggregation states. Checkerboards were performed on five genera of Mucorales (12 strains) using several combinations of different surfactants and AmB. These data were analyzed by an Emax model. The effect of surfactants on the cytotoxic activity of AmB was then evaluated for red blood cells and two eukaryotic cell lines by absorbance and propidium iodide internalization. Finally, the effect of polyethylene glycol (15)-hydroxystearate (PEG15HS) on the aggregation states of AmB was evaluated by UV-visible spectrometry. PEG15HS increased the efficacy of AmB on four of the five Mucorales genera, and MICs of AmB were decreased up to 68-fold for L. ramosa. PEG15HS was the only surfactant to not increase the cytotoxic activity of AmB. Finally, the analysis of AmB aggregation states showed that the increased efficacy of AmB and the absence of toxicity are related to an increase in monomeric and polyaggregated forms of AmB at the detriment of the dimeric form. In conclusion, PEG15HS increases the in vitro efficacy of AmB against Mucorales at low concentration, without increasing its toxicity; this combination could therefore be evaluated in the treatment of mucormycosis.

Highlights

Mucormycosis is a life-threatening invasive fungal disease caused by a species belonging to Mucorales order [1]
The first step of the study was to evaluate the ability of polyethylene glycol (15)-hydroxystearate (PEG15HS) to improve the efficacy of amphotericin B (AmB) against several genera and strains of Mucorales involved in mucormycosis (Figure 2)
For a high concentration of AmB (15 mg/L), AmB was found in the dimeric form, as indicated by a high absorbance at 330–350 nm (Figure 7c)

Summary

Introduction

Mucormycosis is a life-threatening invasive fungal disease caused by a species belonging to Mucorales order [1]. They are difficult-to-treat infections in immunocompromised patients, being resistant to most antifungal drugs [2]. Mortality remains inacceptable, varying from 30 to 90%, according to the disease forms [2]. In this context, combinations of antifungal agents have been tested in vitro and in vivo to improve their efficacy against Mucorales. Several authors have studied combinations of antifungal agents and non-antifungal molecules [12]. Some of these combinations increased antifungal efficiency in vitro or in vivo in animal models, and presented issues such as improving

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Conclusion