Phospholipidosis is a shared mechanism underlying thein vitroantiviral activity of many repurposed drugs against SARS-CoV-2

Abstract

Repurposing drugs as treatments for COVID-19 has drawn much attention. A common strategy has been to screen for established drugs, typically developed for other indications, that are antiviral in cells or organisms. Intriguingly, most of the drugs that have emerged from these campaigns, though diverse in structure, share a common physical property: cationic amphiphilicity. Provoked by the similarity of these repurposed drugs to those inducing phospholipidosis, a well-known drug side effect, we investigated phospholipidosis as a mechanism for antiviral activity. We tested 23 cationic amphiphilic drugs-including those from phenotypic screens and others that we ourselves had found-for induction of phospholipidosis in cell culture. We found that most of the repurposed drugs, which included hydroxychloroquine, azithromycin, amiodarone, and four others that have already progressed to clinical trials, induced phospholipidosis in the same concentration range as their antiviral activity; indeed, there was a strong monotonic correlation between antiviral efficacy and the magnitude of the phospholipidosis. Conversely, drugs active against the same targets that did not induce phospholipidosis were not antiviral. Phospholipidosis depends on the gross physical properties of drugs, and does not reflect specific target-based activities, rather it may be considered a confound in early drug discovery. Understanding its role in infection, and detecting its effects rapidly, will allow the community to better distinguish between drugs and lead compounds that more directly impact COVID-19 from the large proportion of molecules that manifest this confounding effect, saving much time, effort and cost.

The roles of lipids in SARS-CoV-2 viral replication and the host immune response

“…Sigma-1 and sigma-2 receptors, both of which appear to play roles in cholesterol transport ( 66 , 67 ), were identified as potential targets in SARS-CoV-2-human protein-protein interaction screens ( 68 , 69 ). In screens of repurposed drugs, it has been observed that there was a strong correlation between antiviral efficacy against SARS-CoV-2 and the magnitude of phospholipidosis in vitro ( 70 ). However, none of the lead compounds tested exhibited significant antiviral activity in vivo , underscoring the need for additional research to translate these in vitro observations into a useful therapeutic approach in humans.…”

Molecular Networking for Drug Toxicities Studies: The Case of Hydroxychloroquine in COVID-19 Patients

“…In this study, 100 µM HCQ induced neutral lipid accumulation in HepaRG cells incubated without fatty acid accumulation. However, to the best of our knowledge, HCQ-induced accumulation of hepatic triglycerides (i.e., steatosis) does not seem to occur in treated patients, contrary to phospholipid accumulation (i.e., phospholipidosis), which is common with this cationic amphiphilic drug [ 16 , 41 ]. Hence, our data suggest that only a few susceptible patients might be at risk for HCQ-induced steatosis.…”

Cellular toxicity of iHAP1 and DT-061 does not occur through PP2A-B56 targeting

“…This would be consistent with the hydrophobic nature of DT-061 and the fact that we see DT-061 forming small structures in cells attracting the Golgi marker. Tricyclic heterocyclic compounds can have a profound impact on lipids and indeed methylene blue, which belongs to this class of molecules, has been used to stain the Golgi in cells [37–41]. We acknowledge the extensive studies conducted by Leonard et al (2020) to analyse the interaction between DT-061 and PP2A-B56α complexes.…”