Pharmacologically induced endolysosomal cholesterol imbalance through clinically licensed drugs itraconazole and fluoxetine impairs Ebola virus infection in vitro

ABSTRACT

Ebola virus disease (EVD) is a severe and frequently lethal disease caused by Ebola virus (EBOV). The latest occasional EVD outbreak (2013–2016) in Western African, which was accompanied by a high fatality rate, showed the great potential of epidemic and pandemic spread. Antiviral therapies against EBOV are very limited, strain-dependent (only antibody therapies are available) and mostly restricted to symptomatic treatment, illustrating the urgent need for novel antiviral strategies. Thus, we evaluated the effect of the clinically widely used antifungal itraconazole and the antidepressant fluoxetine for a repurposing against EBOV infection. While itraconazole, similar to U18666A, directly binds to and inhibits the endosomal membrane protein Niemann-Pick C1 (NPC1), fluoxetine, which belongs to the structurally unrelated group of weakly basic, amphiphile so-called “functional inhibitors of acid sphingomyelinase” (FIASMA) indirectly acts on the lysosome-residing acid sphingomyelinase via enzyme detachment leading to subsequent lysosomal degradation. Both, the drug-induced endolysosomal cholesterol accumulation and the altered endolysosomal pH, might interfere with the fusion of viral and endolysosomal membrane, preventing infection with EBOV. We further provide evidence that cholesterol imbalance is a conserved cross-species mechanism to hamper EBOV infection. Thus, exploring the endolysosomal host–pathogen interface as a suitable antiviral treatment may offer a general strategy to combat EBOV infection.

KEYWORDS:

• Ebola virus
• Niemann-Pick C1
• itraconazole
• FIASMA
• fluoxetine
• viral entry
• endolysosomal interference

Acknowledgments

We are grateful to Andreas Kurth for kindly providing the possibility to perform the BSL 4 experiments using the BSL 4 containment at the Center for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, Germany. We thank Katharina Kimmerl und Uwe Vogel for excellent technical support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded by grants from the German Research Foundation (DFG) [Deutsche Forschungsgemeinschaft], CRC1009 “Breaking Barriers”, Project A06 (to U.R.), CRC 1348 “Dynamic Cellular Interfaces”, Project A11 (to U.R.), the Interdisciplinary Center for Clinical Research (IZKF) of the Münster Medical School, grant number Re2/022/20 (to U.R.) and the Innovative Medizinische Forschung (IMF) of the Münster Medical School, grant number SC121912 (to S.S.). S.S. and U.R. are members of the German FluResearchNet, a nation-wide research network on zoonotic influenza, and of the British Pharmacological Society. S.S., S.K. and U.R. are also members of the German Society for Virology (GfV). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript; Interdisziplinäres Zentrum für Klinische Forschung, Universitätsklinikum Münster.