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Latent tuberculosis infection: myths, models, and molecular mechanisms. Microbiol Mol Biol Rev 2015; 78:343-71. [PMID: 25184558 DOI: 10.1128/mmbr.00010-14] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The aim of this review is to present the current state of knowledge on human latent tuberculosis infection (LTBI) based on clinical studies and observations, as well as experimental in vitro and animal models. Several key terms are defined, including "latency," "persistence," "dormancy," and "antibiotic tolerance." Dogmas prevalent in the field are critically examined based on available clinical and experimental data, including the long-held beliefs that infection is either latent or active, that LTBI represents a small population of nonreplicating, "dormant" bacilli, and that caseous granulomas are the haven for LTBI. The role of host factors, such as CD4(+) and CD8(+) T cells, T regulatory cells, tumor necrosis factor alpha (TNF-α), and gamma interferon (IFN-γ), in controlling TB infection is discussed. We also highlight microbial regulatory and metabolic pathways implicated in bacillary growth restriction and antibiotic tolerance under various physiologically relevant conditions. Finally, we pose several clinically important questions, which remain unanswered and will serve to stimulate future research on LTBI.
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Zumla A, Rao M, Parida SK, Keshavjee S, Cassell G, Wallis R, Axelsson-Robertsson R, Doherty M, Andersson J, Maeurer M. Inflammation and tuberculosis: host-directed therapies. J Intern Med 2015; 277:373-87. [PMID: 24717092 DOI: 10.1111/joim.12256] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Tuberculosis (TB) is an airborne infectious disease that kills almost two million individuals every year. Multidrug-resistant (MDR) TB is caused by strains of Mycobacterium tuberculosis (M. tb) resistant to isoniazid and rifampin, the backbone of first-line antitubercular treatment. MDR TB affects an estimated 500,000 new patients annually. Genetic analysis of drug-resistant MDR-TB showed that airborne transmission of undetected and untreated strains played a major role in disease outbreaks. The need for new TB vaccines and faster diagnostics, as well as the development of new drugs, has recently been highlighted. The major problem in terms of current TB research and clinical demands is the increasing number of cases of extensively drug-resistant and 'treatment-refractory' TB. An emerging scenario of adjunct host-directed therapies is intended to target pulmonary TB where inflammatory processes can be deleterious and lead to immune exhaustion. 'Target-organ-saving' strategies may be warranted to prevent damage to infected tissues and achieve focused, clinically relevant and long-lasting anti-M. tb cellular immune responses. Candidates for such interventions may be biological agents or already approved drugs that can be 're-purposed' to interfere with biologically relevant cellular checkpoints. Here, we review current concepts of inflammation in TB disease and discuss candidate pathways for host-directed therapies to achieve better clinical outcomes.
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Affiliation(s)
- A Zumla
- University College London, University College London Hospitals NHS Foundation Trust, London, UK
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103
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Parida SK, Axelsson-Robertson R, Rao MV, Singh N, Master I, Lutckii A, Keshavjee S, Andersson J, Zumla A, Maeurer M. Totally drug-resistant tuberculosis and adjunct therapies. J Intern Med 2015; 277:388-405. [PMID: 24809736 DOI: 10.1111/joim.12264] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The first cases of totally drug-resistant (TDR) tuberculosis (TB) were reported in Italy 10 years ago; more recently, cases have also been reported in Iran, India and South Africa. Although there is no consensus on terminology, it is most commonly described as 'resistance to all first- and second-line drugs used to treat TB'. Mycobacterium tuberculosis (M.tb) acquires drug resistance mutations in a sequential fashion under suboptimal drug pressure due to monotherapy, inadequate dosing, treatment interruptions and drug interactions. The treatment of TDR-TB includes antibiotics with disputed or minimal effectiveness against M.tb, and the fatality rate is high. Comorbidities such as diabetes and infection with human immunodeficiency virus further impact on TB treatment options and survival rates. Several new drug candidates with novel modes of action are under late-stage clinical evaluation (e.g., delamanid, bedaquiline, SQ109 and sutezolid). 'Repurposed' antibiotics have also recently been included in the treatment of extensively drug resistant TB. However, because of mutations in M.tb, drugs will not provide a cure for TB in the long term. Adjunct TB therapies, including therapeutic vaccines, vitamin supplementation and/or repurposing of drugs targeting biologically and clinically relevant molecular pathways, may achieve better clinical outcomes in combination with standard chemotherapy. Here, we review broader perspectives of drug resistance in TB and potential adjunct treatment options.
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Affiliation(s)
- S K Parida
- Therapeutic Immunology Division, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
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104
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Zumla A, Chakaya J, Centis R, D'Ambrosio L, Mwaba P, Bates M, Kapata N, Nyirenda T, Chanda D, Mfinanga S, Hoelscher M, Maeurer M, Migliori GB. Tuberculosis treatment and management—an update on treatment regimens, trials, new drugs, and adjunct therapies. THE LANCET RESPIRATORY MEDICINE 2015; 3:220-34. [DOI: 10.1016/s2213-2600(15)00063-6] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 01/09/2015] [Accepted: 01/12/2015] [Indexed: 01/08/2023]
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Chang HH, Cohen T, Grad YH, Hanage WP, O'Brien TF, Lipsitch M. Origin and proliferation of multiple-drug resistance in bacterial pathogens. Microbiol Mol Biol Rev 2015; 79:101-16. [PMID: 25652543 PMCID: PMC4402963 DOI: 10.1128/mmbr.00039-14] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SUMMARY Many studies report the high prevalence of multiply drug-resistant (MDR) strains. Because MDR infections are often significantly harder and more expensive to treat, they represent a growing public health threat. However, for different pathogens, different underlying mechanisms are traditionally used to explain these observations, and it is unclear whether each bacterial taxon has its own mechanism(s) for multidrug resistance or whether there are common mechanisms between distantly related pathogens. In this review, we provide a systematic overview of the causes of the excess of MDR infections and define testable predictions made by each hypothetical mechanism, including experimental, epidemiological, population genomic, and other tests of these hypotheses. Better understanding the cause(s) of the excess of MDR is the first step to rational design of more effective interventions to prevent the origin and/or proliferation of MDR.
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Affiliation(s)
- Hsiao-Han Chang
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
| | - Ted Cohen
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, USA
| | - Yonatan H Grad
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA Division of Infectious Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - William P Hanage
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
| | - Thomas F O'Brien
- The World Health Organization Collaborating Centre for Surveillance of Antimicrobial Resistance, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Marc Lipsitch
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, USA
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106
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Demitto FDO, do Amaral RCR, Maltempe FG, Siqueira VLD, Scodro RBDL, Lopes MA, Caleffi-Ferracioli KR, Canezin PH, Cardoso RF. In vitro activity of rifampicin and verapamil combination in multidrug-resistant mycobacterium tuberculosis. PLoS One 2015; 10:e0116545. [PMID: 25689777 PMCID: PMC4331551 DOI: 10.1371/journal.pone.0116545] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 12/09/2014] [Indexed: 11/30/2022] Open
Abstract
The aim of the present study was to evaluate the effect of the combination of rifampicin (RIF) and verapamil (VP) against the Mycobacterium tuberculosis H37Rv reference strain and six multidrug-resistant (MDR) M. tuberculosis clinical isolates by determining Time-Kill Curves and the ability to efflux drug by fluorometry. The RIF+VP combination showed synergism in one MDR clinical isolate. For the other five MDR clinical isolates, the drug combination showed no interaction. The MDR clinical isolate had lower ethidium bromide (EtBr) accumulation when exposed to the RIF+VP combination, compared with RIF and VP exposure alone. The other MDR clinical isolates showed no significant difference in EtBr accumulation. These results suggest greater efflux action in one of the MDR clinical isolates compared with the M. tuberculosis H37Rv reference strain. The other five MDR isolates may have additional mechanisms of drug resistance to RIF. The use of the RIF+VP combination made one MDR bacillus more susceptible to RIF probably by inhibiting efflux pumps, and this combination therapy, in some cases, may contribute to a reduction of resistance to RIF in M. tuberculosis.
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Affiliation(s)
- Fernanda de Oliveira Demitto
- Postgraduation in Health Sciences, State University of Maringa, Avenida Colombo, 5790, Maringa, Parana, 87020–900, Brazil
| | - Renata Claro Ribeiro do Amaral
- Postgraduation in Bioscience and Pathophysiology, State University of Maringa, Avenida Colombo, 5790, Maringa, Parana, 87020–900, Brazil
| | - Flaviane Granero Maltempe
- Postgraduation in Bioscience and Pathophysiology, State University of Maringa, Avenida Colombo, 5790, Maringa, Parana, 87020–900, Brazil
| | - Vera Lúcia Dias Siqueira
- Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Avenida Colombo, 5790, Maringa, Parana, 87020–900, Brazil
| | - Regiane Bertin de Lima Scodro
- Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Avenida Colombo, 5790, Maringa, Parana, 87020–900, Brazil
| | - Mariana Aparecida Lopes
- Postgraduation in Bioscience and Pathophysiology, State University of Maringa, Avenida Colombo, 5790, Maringa, Parana, 87020–900, Brazil
| | - Katiany R. Caleffi-Ferracioli
- Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Avenida Colombo, 5790, Maringa, Parana, 87020–900, Brazil
| | - Pedro Henrique Canezin
- Postgraduation in Health Sciences, State University of Maringa, Avenida Colombo, 5790, Maringa, Parana, 87020–900, Brazil
| | - Rosilene Fressatti Cardoso
- Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Avenida Colombo, 5790, Maringa, Parana, 87020–900, Brazil
- * E-mail:
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107
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The efflux pump inhibitor timcodar improves the potency of antimycobacterial agents. Antimicrob Agents Chemother 2014; 59:1534-41. [PMID: 25534740 DOI: 10.1128/aac.04271-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous studies indicated that inhibition of efflux pumps augments tuberculosis therapy. In this study, we used timcodar (formerly VX-853) to determine if this efflux pump inhibitor could increase the potency of antituberculosis (anti-TB) drugs against Mycobacterium tuberculosis in in vitro and in vivo combination studies. When used alone, timcodar weakly inhibited M. tuberculosis growth in broth culture (MIC, 19 μg/ml); however, it demonstrated synergism in drug combination studies with rifampin, bedaquiline, and clofazimine but not with other anti-TB agents. When M. tuberculosis was cultured in host macrophage cells, timcodar had about a 10-fold increase (50% inhibitory concentration, 1.9 μg/ml) in the growth inhibition of M. tuberculosis and demonstrated synergy with rifampin, moxifloxacin, and bedaquiline. In a mouse model of tuberculosis lung infection, timcodar potentiated the efficacies of rifampin and isoniazid, conferring 1.0 and 0.4 log10 reductions in bacterial burden in lung, respectively, compared to the efficacy of each drug alone. Furthermore, timcodar reduced the likelihood of a relapse infection when evaluated in a mouse model of long-term, chronic infection with treatment with a combination of rifampin, isoniazid, and timcodar. Although timcodar had no effect on the pharmacokinetics of rifampin in plasma and lung, it did increase the plasma exposure of bedaquiline. These data suggest that the antimycobacterial drug-potentiating activity of timcodar is complex and drug dependent and involves both bacterial and host-targeted mechanisms. Further study of the improvement of the potency of antimycobacterial drugs and drug candidates when used in combination with timcodar is warranted.
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108
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Host Evasion and Exploitation Schemes of Mycobacterium tuberculosis. Cell 2014; 159:1497-509. [DOI: 10.1016/j.cell.2014.11.024] [Citation(s) in RCA: 269] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Indexed: 12/20/2022]
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109
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Zumla A, Memish ZA, Maeurer M, Bates M, Mwaba P, Al-Tawfiq JA, Denning DW, Hayden FG, Hui DS. Emerging novel and antimicrobial-resistant respiratory tract infections: new drug development and therapeutic options. THE LANCET. INFECTIOUS DISEASES 2014; 14:1136-1149. [PMID: 25189352 PMCID: PMC7106460 DOI: 10.1016/s1473-3099(14)70828-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The emergence and spread of antimicrobial-resistant bacterial, viral, and fungal pathogens for which diminishing treatment options are available is of major global concern. New viral respiratory tract infections with epidemic potential, such as severe acute respiratory syndrome, swine-origin influenza A H1N1, and Middle East respiratory syndrome coronavirus infection, require development of new antiviral agents. The substantial rise in the global numbers of patients with respiratory tract infections caused by pan-antibiotic-resistant Gram-positive and Gram-negative bacteria, multidrug-resistant Mycobacterium tuberculosis, and multiazole-resistant fungi has focused attention on investments into development of new drugs and treatment regimens. Successful treatment outcomes for patients with respiratory tract infections across all health-care settings will necessitate rapid, precise diagnosis and more effective and pathogen-specific therapies. This Series paper describes the development and use of new antimicrobial agents and immune-based and host-directed therapies for a range of conventional and emerging viral, bacterial, and fungal causes of respiratory tract infections.
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Affiliation(s)
- Alimuddin Zumla
- Division of Infection and Immunity, University College London, London, UK; NIHR Biomedical Research Centre, University College London Hospitals, London, UK; University of Zambia-University College London Research and Training Project, University Teaching Hospital, Lusaka, Zambia; Global Center for Mass Gatherings Medicine, Ministry of Health, Riyadh, Saudi Arabia
| | - Ziad A Memish
- Global Center for Mass Gatherings Medicine, Ministry of Health, Riyadh, Saudi Arabia; Al-Faisal University, Riyadh, Saudi Arabia
| | - Markus Maeurer
- Therapeutic Immunology, Departments of Laboratory Medicine and Microbiology, Tumour and Cell Biology, Karolinska Institute, Stockholm, Sweden
| | - Matthew Bates
- Division of Infection and Immunity, University College London, London, UK; University of Zambia-University College London Research and Training Project, University Teaching Hospital, Lusaka, Zambia
| | - Peter Mwaba
- University of Zambia-University College London Research and Training Project, University Teaching Hospital, Lusaka, Zambia
| | - Jaffar A Al-Tawfiq
- Johns Hopkins Aramco Healthcare, Dhahran, Saudi Arabia; Indiana University School of Medicine, Indianapolis, IN, USA
| | - David W Denning
- National Aspergillosis Centre, University Hospital South Manchester, University of South Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Frederick G Hayden
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - David S Hui
- Division of Respiratory Medicine and Stanley Ho Center for Emerging Infectious Diseases, Chinese University of Hong Kong, Prince of Wales Hospital, New Territories, Hong Kong.
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110
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Verapamil increases the bactericidal activity of bedaquiline against Mycobacterium tuberculosis in a mouse model. Antimicrob Agents Chemother 2014; 59:673-6. [PMID: 25331694 DOI: 10.1128/aac.04019-14] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Bedaquiline is a newly approved drug for the treatment of multidrug-resistant tuberculosis, but there are concerns about its safety in humans. We found that the coadministration of verapamil with subinhibitory doses of bedaquiline gave the same bactericidal effect in mice as did the full human bioequivalent bedaquiline dosing. Adding verapamil to bedaquiline monotherapy also protected against the development of resistant mutants in vivo. The adjunctive use of verapamil may permit use of lower doses of bedaquiline to be used and thereby reduce its dose-related toxicities in tuberculosis patients.
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111
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LprG-mediated surface expression of lipoarabinomannan is essential for virulence of Mycobacterium tuberculosis. PLoS Pathog 2014; 10:e1004376. [PMID: 25232742 PMCID: PMC4169494 DOI: 10.1371/journal.ppat.1004376] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Accepted: 07/28/2014] [Indexed: 11/19/2022] Open
Abstract
Mycobacterium tuberculosis employs various virulence strategies to subvert host immune responses in order to persist and cause disease. Interaction of M. tuberculosis with mannose receptor on macrophages via surface-exposed lipoarabinomannan (LAM) is believed to be critical for cell entry, inhibition of phagosome-lysosome fusion, and intracellular survival, but in vivo evidence is lacking. LprG, a cell envelope lipoprotein that is essential for virulence of M. tuberculosis, has been shown to bind to the acyl groups of lipoglycans but the role of LprG in LAM biosynthesis and localization remains unknown. Using an M. tuberculosis lprG mutant, we show that LprG is essential for normal surface expression of LAM and virulence of M. tuberculosis attributed to LAM. The lprG mutant had a normal quantity of LAM in the cell envelope, but its surface was altered and showed reduced expression of surface-exposed LAM. Functionally, the lprG mutant was defective for macrophage entry and inhibition of phagosome-lysosome fusion, was attenuated in macrophages, and was killed in the mouse lung with the onset of adaptive immunity. This study identifies the role of LprG in surface-exposed LAM expression and provides in vivo evidence for the essential role surface LAM plays in M. tuberculosis virulence. Findings have translational implications for therapy and vaccine development. Mycobacterium tuberculosis is among the leading infectious causes of human death. A better understanding of its virulence mechanisms is needed to facilitate development of novel therapeutics and a preventative vaccine. Lipoarabinomannan (LAM), an abundant surface-exposed lipoglycan, is believed to be a critical virulence determinant for intracellular survival and latency of M. tuberculosis. In vitro experiments with purified LAM have led to a model in which surface-exposed LAM binds to macrophage mannose receptor and facilitates bacterium entry, inhibition of phagosome-lysosome fusion, and modulation of innate immune responses. However, confirmation of these findings in vivo has not been possible due to the essentiality of genes involved in the LAM biosynthetic pathway. It was recently shown that LprG, a cell envelope lipoprotein, binds to the acyl groups of lipoglycan, but the role of LprG in LAM biosynthesis and localization remains unknown. Here, using an M. tuberculosis lprG mutant and a novel cell-imprinting assay, we show that LprG is essential for normal surface expression of LAM and virulence of M. tuberculosis attributed to LAM. Our study provides new insights into the mechanism of surface expression of LAM and confirms the essential role surface LAM serves in pathogenesis of M. tuberculosis.
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112
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Andries K, Villellas C, Coeck N, Thys K, Gevers T, Vranckx L, Lounis N, de Jong BC, Koul A. Acquired resistance of Mycobacterium tuberculosis to bedaquiline. PLoS One 2014; 9:e102135. [PMID: 25010492 PMCID: PMC4092087 DOI: 10.1371/journal.pone.0102135] [Citation(s) in RCA: 274] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 06/16/2014] [Indexed: 11/18/2022] Open
Abstract
Bedaquiline (BDQ), an ATP synthase inhibitor, is the first drug to be approved for treatment of multi-drug resistant tuberculosis in decades. In vitro resistance to BDQ was previously shown to be due to target-based mutations. Here we report that non-target based resistance to BDQ, and cross-resistance to clofazimine (CFZ), is due to mutations in Rv0678, a transcriptional repressor of the genes encoding the MmpS5-MmpL5 efflux pump. Efflux-based resistance was identified in paired isolates from patients treated with BDQ, as well as in mice, in which it was confirmed to decrease bactericidal efficacy. The efflux inhibitors verapamil and reserpine decreased the minimum inhibitory concentrations of BDQ and CFZ in vitro, but verapamil failed to increase the bactericidal effect of BDQ in mice and was unable to reverse efflux-based resistance in vivo. Cross-resistance between BDQ and CFZ may have important clinical implications.
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Affiliation(s)
- Koen Andries
- Department of Infectious Diseases, Janssen Pharmaceutica, Beerse, Belgium
- * E-mail:
| | - Cristina Villellas
- Department of Infectious Diseases, Janssen Pharmaceutica, Beerse, Belgium
| | - Nele Coeck
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Kim Thys
- Department of Infectious Diseases, Janssen Pharmaceutica, Beerse, Belgium
| | - Tom Gevers
- Department of Infectious Diseases, Janssen Pharmaceutica, Beerse, Belgium
| | - Luc Vranckx
- Department of Infectious Diseases, Janssen Pharmaceutica, Beerse, Belgium
| | - Nacer Lounis
- Department of Infectious Diseases, Janssen Pharmaceutica, Beerse, Belgium
| | - Bouke C. de Jong
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Anil Koul
- Department of Infectious Diseases, Janssen Pharmaceutica, Beerse, Belgium
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113
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Reves R, Schluger NW. Update in tuberculosis and nontuberculous mycobacterial infections 2013. Am J Respir Crit Care Med 2014; 189:894-8. [PMID: 24735031 DOI: 10.1164/rccm.201402-0210up] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Randall Reves
- 1 Department of Medicine, University of Colorado, Denver, Colorado
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114
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Singh K, Kumar M, Pavadai E, Naran K, Warner DF, Ruminski PG, Chibale K. Synthesis of new verapamil analogues and their evaluation in combination with rifampicin against Mycobacterium tuberculosis and molecular docking studies in the binding site of efflux protein Rv1258c. Bioorg Med Chem Lett 2014; 24:2985-90. [PMID: 24894561 DOI: 10.1016/j.bmcl.2014.05.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 05/08/2014] [Accepted: 05/09/2014] [Indexed: 11/19/2022]
Abstract
New verapamil analogues were synthesized and their inhibitory activities against Mycobacterium tuberculosis H37Rv determined in vitro alone and in combination with rifampicin (RIF). Some analogues showed comparable activity to verapamil and exhibited better synergies with RIF. Molecular docking studies of the binding sites of Rv1258c, a M. tuberculosis efflux protein previously implicated in intrinsic resistance to RIF, suggested a potential rationale for the superior synergistic interactions observed with some analogues.
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Affiliation(s)
- Kawaljit Singh
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa; South African Medical Research Council Drug Discovery and Development Research Unit, University of Cape Town, Rondebosch 7701, South Africa
| | - Malkeet Kumar
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa; South African Medical Research Council Drug Discovery and Development Research Unit, University of Cape Town, Rondebosch 7701, South Africa
| | - Elumalai Pavadai
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa; South African Medical Research Council Drug Discovery and Development Research Unit, University of Cape Town, Rondebosch 7701, South Africa
| | - Krupa Naran
- MRC/NHLS/UCT Molecular Mycobacteriology Research Unit, Division of Medical Microbiology, University of Cape Town, Rondebosch 7701, South Africa
| | - Digby F Warner
- MRC/NHLS/UCT Molecular Mycobacteriology Research Unit, Division of Medical Microbiology, University of Cape Town, Rondebosch 7701, South Africa; Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
| | - Peter G Ruminski
- Centre for World Health and Medicine, Saint Louis University, USA
| | - Kelly Chibale
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa; South African Medical Research Council Drug Discovery and Development Research Unit, University of Cape Town, Rondebosch 7701, South Africa; Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa.
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115
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Selvakumar A, Antony C, Singhal J, Tiwari BK, Singh Y, Natarajan K. Reciprocal regulation of reactive oxygen species and phospho-CREB regulates voltage gated calcium channel expression during Mycobacterium tuberculosis infection. PLoS One 2014; 9:e96427. [PMID: 24797940 PMCID: PMC4010530 DOI: 10.1371/journal.pone.0096427] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 04/04/2014] [Indexed: 11/18/2022] Open
Abstract
Our previous work has demonstrated the roles played by L-type Voltage Gated Calcium Channels (VGCC) in regulating Mycobacterium tuberculosis (M. tb) survival and pathogenesis. Here we decipher mechanisms and pathways engaged by the pathogen to regulate VGCC expression in macrophages. We show that M. tb and its antigen Rv3416 use phospho-CREB (pCREB), Reactive Oxygen Species (ROS), Protein Kinase C (PKC) and Mitogen Activated Protein Kinase (MAPK) to modulate VGCC expression in macrophages. siRNA mediated knockdown of MyD88, IRAK1, IRAK2 or TRAF6 significantly inhibited antigen mediated VGCC expression. Inhibiting Protein Kinase C (PKC) or MEK-ERK1/2 further increased VGCC expression. Interestingly, inhibiting intracellular calcium release upregulated antigen mediated VGCC expression, while inhibiting extracellular calcium influx had no significant effect. siRNA mediated knockdown of transcription factors c-Jun, SOX5 and CREB significantly inhibited Rv3416 mediated VGCC expression. A dynamic reciprocal cross-regulation between ROS and pCREB was observed that in turn governed VGCC expression with ROS playing a limiting role in the process. Further dissection of the mechanisms such as the interplay between ROS and pCREB would improve our understanding of the regulation of VGCC expression during M. tb infection.
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Affiliation(s)
- Arti Selvakumar
- From the Infectious Disease Immunology Lab, Dr. B. R. Ambedkar Centre for Biomedical Research, University of Delhi, Delhi, India
- * E-mail: (AS); (KN)
| | - Cecil Antony
- From the Infectious Disease Immunology Lab, Dr. B. R. Ambedkar Centre for Biomedical Research, University of Delhi, Delhi, India
| | - Jhalak Singhal
- From the Infectious Disease Immunology Lab, Dr. B. R. Ambedkar Centre for Biomedical Research, University of Delhi, Delhi, India
| | | | - Yogendra Singh
- CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Krishnamurthy Natarajan
- From the Infectious Disease Immunology Lab, Dr. B. R. Ambedkar Centre for Biomedical Research, University of Delhi, Delhi, India
- * E-mail: (AS); (KN)
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New antituberculosis drugs, regimens, and adjunct therapies: needs, advances, and future prospects. THE LANCET. INFECTIOUS DISEASES 2014; 14:327-40. [DOI: 10.1016/s1473-3099(13)70328-1] [Citation(s) in RCA: 262] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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117
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Antimicrobial treatment improves mycobacterial survival in nonpermissive growth conditions. Antimicrob Agents Chemother 2014; 58:2798-806. [PMID: 24590482 PMCID: PMC3993263 DOI: 10.1128/aac.02774-13] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Antimicrobials targeting cell wall biosynthesis are generally considered inactive against nonreplicating bacteria. Paradoxically, we found that under nonpermissive growth conditions, exposure of Mycobacterium bovis BCG bacilli to such antimicrobials enhanced their survival. We identified a transcriptional regulator, RaaS (for regulator of antimicrobial-assisted survival), encoded by bcg1279 (rv1219c) as being responsible for the observed phenomenon. Induction of this transcriptional regulator resulted in reduced expression of specific ATP-dependent efflux pumps and promoted long-term survival of mycobacteria, while its deletion accelerated bacterial death under nonpermissive growth conditions in vitro and during macrophage or mouse infection. These findings have implications for the design of antimicrobial drug combination therapies for persistent infectious diseases, such as tuberculosis.
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118
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Stanley SA, Barczak AK, Silvis MR, Luo SS, Sogi K, Vokes M, Bray MA, Carpenter AE, Moore CB, Siddiqi N, Rubin EJ, Hung DT. Identification of host-targeted small molecules that restrict intracellular Mycobacterium tuberculosis growth. PLoS Pathog 2014; 10:e1003946. [PMID: 24586159 PMCID: PMC3930586 DOI: 10.1371/journal.ppat.1003946] [Citation(s) in RCA: 193] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 01/01/2014] [Indexed: 02/05/2023] Open
Abstract
Mycobacterium tuberculosis remains a significant threat to global health. Macrophages are the host cell for M. tuberculosis infection, and although bacteria are able to replicate intracellularly under certain conditions, it is also clear that macrophages are capable of killing M. tuberculosis if appropriately activated. The outcome of infection is determined at least in part by the host-pathogen interaction within the macrophage; however, we lack a complete understanding of which host pathways are critical for bacterial survival and replication. To add to our understanding of the molecular processes involved in intracellular infection, we performed a chemical screen using a high-content microscopic assay to identify small molecules that restrict mycobacterial growth in macrophages by targeting host functions and pathways. The identified host-targeted inhibitors restrict bacterial growth exclusively in the context of macrophage infection and predominantly fall into five categories: G-protein coupled receptor modulators, ion channel inhibitors, membrane transport proteins, anti-inflammatories, and kinase modulators. We found that fluoxetine, a selective serotonin reuptake inhibitor, enhances secretion of pro-inflammatory cytokine TNF-α and induces autophagy in infected macrophages, and gefitinib, an inhibitor of the Epidermal Growth Factor Receptor (EGFR), also activates autophagy and restricts growth. We demonstrate that during infection signaling through EGFR activates a p38 MAPK signaling pathway that prevents macrophages from effectively responding to infection. Inhibition of this pathway using gefitinib during in vivo infection reduces growth of M. tuberculosis in the lungs of infected mice. Our results support the concept that screening for inhibitors using intracellular models results in the identification of tool compounds for probing pathways during in vivo infection and may also result in the identification of new anti-tuberculosis agents that work by modulating host pathways. Given the existing experience with some of our identified compounds for other therapeutic indications, further clinically-directed study of these compounds is merited. Infection with the bacterial pathogen Mycobacterium tuberculosis causes the disease tuberculosis (TB) that imposes significant worldwide morbidity and mortality. Approximately 2 billion people are infected with M. tuberculosis, and almost 1.5 million people die annually from TB. With increasing drug resistance and few novel drug candidates, our inability to effectively treat all infected individuals necessitates a deeper understanding of the host-pathogen interface to facilitate new approaches to treatment. In addition, the current anti-tuberculosis regimen requires months of strict compliance to clear infection; targeting host immune function could play a strategic role in reducing the duration and complexity of treatment while effectively treating drug-resistant strains. Here we use a microscopy-based screen to identify molecules that target host pathways and inhibit the growth of M. tuberculosis in macrophages. We identified several host pathways not previously implicated in tuberculosis. The identified inhibitors prevent growth either by blocking host pathways exploited by M. tuberculosis for virulence, or by activating immune responses that target intracellular bacteria. Fluoxetine, used clinically for treating depression, induces autophagy and enhances production of TNF-α. Similarly, gefitinib, used clinically for treating cancer, inhibits M. tuberculosis growth in macrophages. Importantly, gefitinib treatment reduces bacterial replication in the lungs of M. tuberculosis-infected mice.
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Affiliation(s)
- Sarah A Stanley
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America ; Division of Infectious Disease and Vaccinology, School of Public Health, University of California, Berkeley, Berkeley, California, United States of America
| | - Amy K Barczak
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America ; Division of Infectious Disease, Massachusetts General Hospital, Boston, Massachusetts, United States of America ; Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Melanie R Silvis
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Samantha S Luo
- Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Kimberly Sogi
- Division of Infectious Disease and Vaccinology, School of Public Health, University of California, Berkeley, Berkeley, California, United States of America
| | - Martha Vokes
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Mark-Anthony Bray
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Anne E Carpenter
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Christopher B Moore
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Noman Siddiqi
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Eric J Rubin
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Deborah T Hung
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America ; Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America ; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
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119
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Adams KN, Szumowski JD, Ramakrishnan L. Verapamil, and its metabolite norverapamil, inhibit macrophage-induced, bacterial efflux pump-mediated tolerance to multiple anti-tubercular drugs. J Infect Dis 2014; 210:456-66. [PMID: 24532601 DOI: 10.1093/infdis/jiu095] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Drug tolerance likely represents an important barrier to tuberculosis treatment shortening. We previously implicated the Mycobacterium tuberculosis efflux pump Rv1258c as mediating macrophage-induced tolerance to rifampicin and intracellular growth. In this study, we infected the human macrophage-like cell line THP-1 with drug-sensitive and drug-resistant M. tuberculosis strains and found that tolerance developed to most antituberculosis drugs, including the newer agents moxifloxacin, PA-824, linezolid, and bedaquiline. Multiple efflux pump inhibitors in clinical use for other indications reversed tolerance to isoniazid and rifampicin and slowed intracellular growth. Moreover, verapamil reduced tolerance to bedaquiline and moxifloxacin. Verapamil's R isomer and its metabolite norverapamil have substantially less calcium channel blocking activity yet were similarly active as verapamil at inhibiting macrophage-induced drug tolerance. Our finding that verapamil inhibits intracellular M. tuberculosis growth and tolerance suggests its potential for treatment shortening. Norverapamil, R-verapamil, and potentially other derivatives present attractive alternatives that may have improved tolerability.
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Affiliation(s)
| | | | - Lalita Ramakrishnan
- Department of Microbiology Department of Medicine, Division of Infectious Diseases Department of Immunology, University of Washington, Seattle, Washington
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120
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Efflux inhibition with verapamil potentiates bedaquiline in Mycobacterium tuberculosis. Antimicrob Agents Chemother 2013; 58:574-6. [PMID: 24126586 DOI: 10.1128/aac.01462-13] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Drug efflux is an important resistance mechanism in Mycobacterium tuberculosis. We found that verapamil, an efflux inhibitor, profoundly decreases the MIC of bedaquiline and clofazimine to M. tuberculosis by 8- to 16-fold. This exquisite susceptibility was noted among drug-susceptible and drug-resistant clinical isolates. Thus, efflux inhibition is an important sensitizer of bedaquiline and clofazimine, and efflux may emerge as a resistance mechanism to these drugs.
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