Screening Repurposed Antiviral Small Molecules as Antimycobacterial Compounds by a Lux-Based phoP Promoter-Reporter Platform

Li Zhu,Kelvin Ka-Lok Wu,Wing Cheong Yam,Hiu Yin Lao,Peng Gao,Richard Yi-Tsun Kao,Gilman Kit Hang Siu,Galata Chala Chaburte,Kingsley King-Gee Tam,Timothy Ting-Leung Ng,Chloe Toi-Mei Chan,Rahim Rajwani,Annie Wing-Tung Lee

doi:10.3390/antibiotics11030369

Li Zhu, Kelvin Ka-Lok Wu + Show 11 more

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https://doi.org/10.3390/antibiotics11030369

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Abstract

The emergence of multidrug-resistant strains and hyper-virulent strains of Mycobacterium tuberculosis are big therapeutic challenges for tuberculosis (TB) control. Repurposing bioactive small-molecule compounds has recently become a new therapeutic approach against TB. This study aimed to identify novel anti-TB agents from a library of small-molecule compounds via a rapid screening system. A total of 320 small-molecule compounds were used to screen for their ability to suppress the expression of a key virulence gene, phop, of the M. tuberculosis complex using luminescence (lux)-based promoter-reporter platforms. The minimum inhibitory and bactericidal concentrations on drug-resistant M. tuberculosis and cytotoxicity to human macrophages were determined. RNA sequencing (RNA-seq) was conducted to determine the drug mechanisms of the selected compounds as novel antibiotics or anti-virulent agents against the M. tuberculosis complex. The results showed that six compounds displayed bactericidal activity against M. bovis BCG, of which Ebselen demonstrated the lowest cytotoxicity to macrophages and was considered as a potential antibiotic for TB. Another ten compounds did not inhibit the in vitro growth of the M. tuberculosis complex and six of them downregulated the expression of phoP/R significantly. Of these, ST-193 and ST-193 (hydrochloride) showed low cytotoxicity and were suggested to be potential anti-virulence agents for M. tuberculosis.

Highlights

TB infections associated with multidrug-resistant (MDR), extensively drug-resistant (XDR), and totally drug-resistant (TDR) Mycobacterium tuberculosis strains have been increasing in recent years [1–4]
According to the global new TB drug development pipeline built by the Stop TB Partnership Working Group on New Drugs in 2021, only a few anti-TB drugs were in phase III clinical trials [5], and some of them could not penetrate through complex lung lesions and the MTB cell wall, thereby failing to eliminate M. tuberculosis [6,7]
We firstly showed that there was no significant difference (p > 0.05) in optical density via absorbance at 600 nm (OD600) between M. bovis bacille Calmette-Guérin (BCG) with and without ETZ treatment (Figure 1(Ci))

Summary

Introduction

Tuberculosis (TB) remains a significant global health problem today. TB infections associated with multidrug-resistant (MDR), extensively drug-resistant (XDR), and totally drug-resistant (TDR) Mycobacterium tuberculosis strains have been increasing in recent years [1–4]. This situation poses a significant threat to global TB control, in resource-poor countries with a high prevalence of AIDS. According to the global new TB drug development pipeline built by the Stop TB Partnership Working Group on New Drugs in 2021, only a few anti-TB drugs were in phase III clinical trials [5], and some of them could not penetrate through complex lung lesions and the MTB cell wall, thereby failing to eliminate M. tuberculosis [6,7]. There is an urgent need to develop new anti-TB treatments against M. tuberculosis strains with various patterns of drug resistance

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