Advances in host‐based screening for compounds with intracellular anti‐mycobacterial activity

Subhash, N.; Sundaramurthy, Varadharajan

doi:10.1111/cmi.13337

Cited by 8 publications

(3 citation statements)

References 84 publications

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“…Others targeted specific proteins or pathways of mycobacteria [19,21,22]. Only a few HTS campaigns were designed to identify inhibitors of intracellular mycobacteria [22,37,38].…”

Section: Discussionmentioning

confidence: 99%

Identification of Small Molecule Inhibitors against Mycobacteria in Activated Macrophages

et al. 2022

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Mycobacterial pathogens are intrinsically resistant to many available antibiotics, making treatment extremely challenging, especially in immunocompromised individuals and patients with underlying and chronic lung conditions. Even with lengthy therapy and the use of a combination of antibiotics, clinical success for non-tuberculous mycobacteria (NTM) is achieved in fewer than half of the cases. The need for novel antibiotics that are effective against NTM is urgent. To identify such new compounds, a whole cell high-throughput screen (HTS) was performed in this study. Compounds from the Chembridge DIVERSet library were tested for their ability to inhibit intracellular survival of M. avium subsp. hominissuis (MAH) expressing dtTomato protein, using fluorescence as a readout. Fifty-eight compounds were identified to significantly inhibit fluorescent readings of MAH. In subsequent assays, it was found that treatment of MAH-infected THP-1 macrophages with 27 of 58 hit compounds led to a significant reduction in intracellular viable bacteria, while 19 compounds decreased M. abscessus subsp. abscessus (Mab) survival rates within phagocytic cells. In addition, the hit compounds were tested in M. tuberculosis H37Ra (Mtb) and 14 compounds were found to exhibit activity in activated THP-1 cells. While the majority of compounds displayed inhibitory activity against both replicating (extracellular) and non-replicating (intracellular) forms of bacteria, a set of compounds appeared to be effective exclusively against intracellular bacteria. The efficacy of these compounds was examined in combination with current antibiotics and survival of both NTM and Mtb were evaluated within phagocytic cells. In time-kill dynamic studies, it was found that co-treatment promoted increased bacterial clearance when compared with the antibiotic or compound group alone. This study describes promising anti-NTM and anti-Mtb compounds with potential novel mechanisms of action that target intracellular bacteria in activated macrophages.

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“…Others targeted specific proteins or pathways of mycobacteria [19,21,22]. Only a few HTS campaigns were designed to identify inhibitors of intracellular mycobacteria [22,37,38].…”

Section: Discussionmentioning

confidence: 99%

Identification of Small Molecule Inhibitors against Mycobacteria in Activated Macrophages

et al. 2022

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“…Intracellular assays that quantify the bacterial survival inside the host phagocytes are used as host-based screening platforms to describe new, better-acting drugs ( 24 ). These screens were performed with Mtb or its surrogate M. bovis BCG ( 25 ) residing mainly in macrophages.…”

Section: Introductionmentioning

confidence: 99%

Novel Assay Platform to Evaluate Intracellular Killing of Mycobacterium tuberculosis: In Vitro and In Vivo Validation

et al. 2021

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One of the main hallmarks of tuberculosis (TB) is the ability of the causative agent to transform into a stage of dormancy and the capability of long persistence in the host phagocytes. It is believed that approximately one-third of the population of the world is latently infected with Mycobacterium tuberculosis (Mtb), and 5%–10% of these individuals can develop clinical manifestations of active TB even decades after the initial infection. In this latent, intracellular form, the bacillus is shielded by an extremely robust cell wall and becomes phenotypically resistant to most antituberculars. Therefore, there is a clear rationale to develop novel compounds or carrier-conjugated constructs of existing drugs that are effective against the intracellular form of the bacilli. In this paper, we describe an experimental road map to define optimal candidates against intracellular Mtb and potential compounds effective in the therapy of latent TB. To validate our approach, isoniazid, a first-line antitubercular drug was employed, which is active against extracellular Mtb in the submicromolar range, but ineffective against the intracellular form of the bacteria. Cationic peptide conjugates of isoniazid were synthesized and employed to study the host-directed drug delivery. To measure the intracellular killing activity of the compounds, Mtb-infected MonoMac-6 human monocytic cells were utilized. We have assessed the antitubercular activity, cytotoxicity, membrane interactions in combination with internalization efficacy, localization, and penetration ability on interface and tissue-mimicking 3D models. Based on these in vitro data, most active compounds were further evaluated in vivo in a murine model of TB. Intraperitoneal infectious route was employed to induce a course of slowly progressive and systemic disease. The well-being of the animals, monitored by the body weight, allows a prolonged experimental setup and provides a great opportunity to test the long-term activity of the drug candidates. Having shown the great potency of this simple and suitable experimental design for antimicrobial research, the proposed novel assay platform could be used in the future to develop further innovative and highly effective antituberculars.

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“…High throughput screening is an integral part of drug development as well as large scale genomic editing approaches. Subhash and Sundaramurthy describe screening platforms that take the host environment into account (Subhash & Sundaramurthy, 2021). This allows the identification of potential host directed therapeutics which may be used as adjunct therapies against chronic intractable infections like tuberculosis, particularly where the pathogen is intracellular.…”

mentioning

confidence: 99%

Emerging methods in cellular microbiology

Hartland

2021

Cellular Microbiology

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Advances in host‐based screening for compounds with intracellular anti‐mycobacterial activity

Cited by 8 publications

References 84 publications

Identification of Small Molecule Inhibitors against Mycobacteria in Activated Macrophages

Identification of Small Molecule Inhibitors against Mycobacteria in Activated Macrophages

Novel Assay Platform to Evaluate Intracellular Killing of Mycobacterium tuberculosis: In Vitro and In Vivo Validation

Emerging methods in cellular microbiology

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