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Sarathy JP, Xie M, Jones RM, Chang A, Osiecki P, Weiner D, Tsao WS, Dougher M, Blanc L, Fotouhi N, Via LE, Barry CE, De Vlaminck I, Sherman DR, Dartois VA. A Novel Tool to Identify Bactericidal Compounds against Vulnerable Targets in Drug-Tolerant M. tuberculosis found in Caseum. mBio 2023; 14:e0059823. [PMID: 37017524 PMCID: PMC10127596 DOI: 10.1128/mbio.00598-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2023] Open
Abstract
Caseous necrosis is a hallmark of tuberculosis (TB) pathology and creates a niche for drug-tolerant persisters within the host. Cavitary TB and high bacterial burden in caseum require longer treatment duration. An in vitro model that recapitulates the major features of Mycobacterium tuberculosis (Mtb) in caseum would accelerate the identification of compounds with treatment-shortening potential. We have developed a caseum surrogate model consisting of lysed and denatured foamy macrophages. Upon inoculation of Mtb from replicating cultures, the pathogen adapts to the lipid-rich matrix and gradually adopts a nonreplicating state. We determined that the lipid composition of ex vivo caseum and the surrogate matrix are similar. We also observed that Mtb in caseum surrogate accumulates intracellular lipophilic inclusions (ILI), a distinctive characteristic of quiescent and drug-tolerant Mtb. Expression profiling of a representative gene subset revealed common signatures between the models. Comparison of Mtb drug susceptibility in caseum and caseum surrogate revealed that both populations are similarly tolerant to a panel of TB drugs. By screening drug candidates in the surrogate model, we determined that the bedaquiline analogs TBAJ876 and TBAJ587, currently in clinical development, exhibit superior bactericidal against caseum-resident Mtb, both alone and as substitutions for bedaquiline in the bedaquiline-pretomanid-linezolid regimen approved for the treatment of multidrug-resistant TB. In summary, we have developed a physiologically relevant nonreplicating persistence model that reflects the distinct metabolic and drug-tolerant state of Mtb in caseum. IMPORTANCE M. tuberculosis (Mtb) within the caseous core of necrotic granulomas and cavities is extremely drug tolerant and presents a significant hurdle to treatment success and relapse prevention. Many in vitro models of nonreplicating persistence have been developed to characterize the physiologic and metabolic adaptations of Mtb and identify compounds active against this treatment-recalcitrant population. However, there is little consensus on their relevance to in vivo infection. Using lipid-laden macrophage lysates, we have designed and validated a surrogate matrix that closely mimics caseum and in which Mtb develops a phenotype similar to that of nonreplicating bacilli in vivo. The assay is well suited to screen for bactericidal compounds against caseum-resident Mtb in a medium-throughput format, allowing for reduced reliance on resource intensive animal models that present large necrotic lesions and cavities. Importantly, this approach will aid the identification of vulnerable targets in caseum Mtb and can accelerate the development of novel TB drugs with treatment-shortening potential.
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Affiliation(s)
- Jansy P Sarathy
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | - Min Xie
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | - Richard M Jones
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Adrienne Chang
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA
| | - Paulina Osiecki
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | - Danielle Weiner
- Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, NIAID, NIH, Bethesda, Maryland, USA
- Tuberculosis Imaging Program, Division of Intramural Research, NIAID, NIH, Bethesda, Maryland, USA
| | - Wen-Shan Tsao
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | - Maureen Dougher
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | - Landry Blanc
- University of Bordeaux, CNRS, CBMN, UMR 5248, Pessac, France
| | - Nader Fotouhi
- Global Alliance for TB Drug Development, New York, New York, USA
| | - Laura E Via
- Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, NIAID, NIH, Bethesda, Maryland, USA
- Tuberculosis Imaging Program, Division of Intramural Research, NIAID, NIH, Bethesda, Maryland, USA
| | - Clifton E Barry
- Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, NIAID, NIH, Bethesda, Maryland, USA
- Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Iwijn De Vlaminck
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA
| | - David R Sherman
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Véronique A Dartois
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
- Hackensack Meridian School of Medicine, Department of Medical Sciences, Nutley, New Jersey, USA
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