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1
Mishra, Richa, Sakshi Kohli, Nitish Malhotra, Parijat Bandyopadhyay, Mansi Mehta, MohamedHusen Munshi, Vasista Adiga, et al. "Targeting redox heterogeneity to counteract drug tolerance in replicating Mycobacterium tuberculosis." Science Translational Medicine 11, no. 518 (November 13, 2019): eaaw6635. http://dx.doi.org/10.1126/scitranslmed.aaw6635.
Full textAbstract:
The capacity of Mycobacterium tuberculosis (Mtb) to tolerate multiple antibiotics represents a major problem in tuberculosis (TB) management. Heterogeneity in Mtb populations is one of the factors that drives antibiotic tolerance during infection. However, the mechanisms underpinning this variation in bacterial population remain poorly understood. Here, we show that phagosomal acidification alters the redox physiology of Mtb to generate a population of replicating bacteria that display drug tolerance during infection. RNA sequencing of this redox-altered population revealed the involvement of iron-sulfur (Fe-S) cluster biogenesis, hydrogen sulfide (H2S) gas, and drug efflux pumps in antibiotic tolerance. The fraction of the pH- and redox-dependent tolerant population increased when Mtb infected macrophages with actively replicating HIV-1, suggesting that redox heterogeneity could contribute to high rates of TB therapy failure during HIV-TB coinfection. Pharmacological inhibition of phagosomal acidification by the antimalarial drug chloroquine (CQ) eradicated drug-tolerant Mtb, ameliorated lung pathology, and reduced postchemotherapeutic relapse in in vivo models. The pharmacological profile of CQ (Cmax and AUClast) exhibited no major drug-drug interaction when coadministered with first line anti-TB drugs in mice. Our data establish a link between phagosomal pH, redox metabolism, and drug tolerance in replicating Mtb and suggest repositioning of CQ to shorten TB therapy and achieve a relapse-free cure.
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Vilchèze, Catherine, Travis Hartman, Brian Weinrick, Paras Jain, Torin R. Weisbrod, Lawrence W. Leung, Joel S. Freundlich, and William R. Jacobs. "Enhanced respiration prevents drug tolerance and drug resistance in Mycobacterium tuberculosis." Proceedings of the National Academy of Sciences 114, no. 17 (April 10, 2017): 4495–500. http://dx.doi.org/10.1073/pnas.1704376114.
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Persistence, manifested as drug tolerance, represents a significant obstacle to global tuberculosis control. The bactericidal drugs isoniazid and rifampicin kill greater than 99% of exponentially growing Mycobacterium tuberculosis (Mtb) cells, but the remaining cells are persisters, cells with decreased metabolic rate, refractory to killing by these drugs, and able to generate drug-resistant mutants. We discovered that the combination of cysteine or other small thiols with either isoniazid or rifampicin prevents the formation of drug-tolerant and drug-resistant cells in Mtb cultures. This effect was concentration- and time-dependent, relying on increased oxygen consumption that triggered enhanced production of reactive oxygen species. In infected murine macrophages, the addition of N-acetylcysteine to isoniazid treatment potentiated the killing of Mtb. Furthermore, we demonstrate that the addition of small thiols to Mtb drug treatment shifted the menaquinol/menaquinone balance toward a reduced state that stimulates Mtb respiration and converts persister cells to metabolically active cells. This prevention of both persister cell formation and drug resistance leads ultimately to mycobacterial cell death. Strategies to enhance respiration and initiate oxidative damage should improve tuberculosis chemotherapies.
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Lim, Juhyeon, Jae Jin Lee, Sun-Kyung Lee, Seoyong Kim, Seok-Yong Eum, and Hyungjin Eoh. "Phosphoenolpyruvate depletion mediates both growth arrest and drug tolerance of Mycobacterium tuberculosis in hypoxia." Proceedings of the National Academy of Sciences 118, no. 35 (August 23, 2021): e2105800118. http://dx.doi.org/10.1073/pnas.2105800118.
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Mycobacterium tuberculosis (Mtb) infection is difficult to treat because Mtb spends the majority of its life cycle in a nonreplicating (NR) state. Since NR Mtb is highly tolerant to antibiotic effects and can mutate to become drug resistant (DR), our conventional tuberculosis (TB) treatment is not effective. Thus, a novel strategy to kill NR Mtb is required. Accumulating evidence has shown that repetitive exposure to sublethal doses of antibiotics enhances the level of drug tolerance, implying that NR Mtb is formed by adaptive metabolic remodeling. As such, metabolic modulation strategies to block the metabolic remodeling needed to form NR Mtb have emerged as new therapeutic options. Here, we modeled in vitro NR Mtb using hypoxia, applied isotope metabolomics, and revealed that phosphoenolpyruvate (PEP) is nearly completely depleted in NR Mtb. This near loss of PEP reduces PEP-carbon flux toward multiple pathways essential for replication and drug sensitivity. Inversely, supplementing with PEP restored the carbon flux and the activities of the foregoing pathways, resulting in growth and heightened drug susceptibility of NR Mtb, which ultimately prevented the development of DR. Taken together, PEP depletion in NR Mtb is associated with the acquisition of drug tolerance and subsequent emergence of DR, demonstrating that PEP treatment is a possible metabolic modulation strategy to resensitize NR Mtb to conventional TB treatment and prevent the emergence of DR.
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Liu, Yancheng, Shumin Tan, Lu Huang, Robert B. Abramovitch, Kyle H. Rohde, Matthew D. Zimmerman, Chao Chen, Véronique Dartois, Brian C. VanderVen, and David G. Russell. "Immune activation of the host cell induces drug tolerance in Mycobacterium tuberculosis both in vitro and in vivo." Journal of Experimental Medicine 213, no. 5 (April 25, 2016): 809–25. http://dx.doi.org/10.1084/jem.20151248.
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Successful chemotherapy against Mycobacterium tuberculosis (Mtb) must eradicate the bacterium within the context of its host cell. However, our understanding of the impact of this environment on antimycobacterial drug action remains incomplete. Intriguingly, we find that Mtb in myeloid cells isolated from the lungs of experimentally infected mice exhibit tolerance to both isoniazid and rifampin to a degree proportional to the activation status of the host cells. These data are confirmed by in vitro infections of resting versus activated macrophages where cytokine-mediated activation renders Mtb tolerant to four frontline drugs. Transcriptional analysis of intracellular Mtb exposed to drugs identified a set of genes common to all four drugs. The data imply a causal linkage between a loss of fitness caused by drug action and Mtb’s sensitivity to host-derived stresses. Interestingly, the environmental context exerts a more dominant impact on Mtb gene expression than the pressure on the drugs’ primary targets. Mtb’s stress responses to drugs resemble those mobilized after cytokine activation of the host cell. Although host-derived stresses are antimicrobial in nature, they negatively affect drug efficacy. Together, our findings demonstrate that the macrophage environment dominates Mtb’s response to drug pressure and suggest novel routes for future drug discovery programs.
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Fattorini, Lanfranco, Giovanni Piccaro, Alessandro Mustazzolu, and Federico Giannoni. "TARGETING DORMANT BACILLI TO FIGHT TUBERCULOSIS." Mediterranean Journal of Hematology and Infectious Diseases 5, no. 1 (November 19, 2013): e2013072. http://dx.doi.org/10.4084/mjhid.2013.072.
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Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb), which kills about 2 million people annually. Furthermore, 2 billion people worldwide are latently infected with this organism, with 10% of them reactivating to active TB due to re-growth of nonreplicating (dormant) Mtb residing in their tissues. Because of the huge reservoir of latent TB it is important to find novel drugs/drug combinations killing dormant bacilli (microaerophiles, anaerobes and drug-tolerant persisters) surviving for decades in a wide spectrum of granulomatous lesions in the lungs of TB patients. Antibiotic treatment of drug-susceptible TB requires administration of isoniazid, rifampin, pyrazinamide, ethambutol for 2 months, followed by isoniazid and rifampin for 4 months. To avoid reactivation of dormant Mtb to active pulmonary TB, up to 9 months of treatment with isoniazid is required. Therefore, a strategy to eliminate dormant bacilli needs to be developed to shorten therapy of active and latent TB and reduce the reservoir of people with latent TB. Finding drugs with high rate of penetration into the caseous granulomas and understanding the biology of dormant bacilli and in particular of persister cells, phenotypically resistant to antibiotics, will be essential to eradicate Mtb from humans. In recent years unprecedented efforts have been done in TB drug discovery, aimed at identifying novel drugs and drug combinations killing both actively replicating and nonreplicating Mtb in vitro, in animal models and in clinical trials in humans.
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Saito, Kohta, Thulasi Warrier, Selin Somersan-Karakaya, Lina Kaminski, Jianjie Mi, Xiuju Jiang, Suna Park, et al. "Rifamycin action on RNA polymerase in antibiotic-tolerant Mycobacterium tuberculosis results in differentially detectable populations." Proceedings of the National Academy of Sciences 114, no. 24 (May 30, 2017): E4832—E4840. http://dx.doi.org/10.1073/pnas.1705385114.
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Mycobacterium tuberculosis (Mtb) encounters stresses during the pathogenesis and treatment of tuberculosis (TB) that can suppress replication of the bacteria and render them phenotypically tolerant to most available drugs. Where studied, the majority of Mtb in the sputum of most untreated subjects with active TB have been found to be nonreplicating by the criterion that they do not grow as colony-forming units (cfus) when plated on agar. However, these cells are viable because they grow when diluted in liquid media. A method for generating such “differentially detectable” (DD) Mtb in vitro would aid studies of the biology and drug susceptibility of this population, but lack of independent confirmation of reported methods has contributed to skepticism about their existence. Here, we identified confounding artifacts that, when avoided, allowed development of a reliable method of producing cultures of ≥90% DD Mtb in starved cells. We then characterized several drugs according to whether they contribute to the generation of DD Mtb or kill them. Of the agents tested, rifamycins led to DD Mtb generation, an effect lacking in a rifampin-resistant strain with a mutation in rpoB, which encodes the canonical rifampin target, the β subunit of RNA polymerase. In contrast, thioridazine did not generate DD Mtb from starved cells but killed those generated by rifampin.
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Genestet, Charlotte, Elisabeth Hodille, Alexia Barbry, Jean-Luc Berland, Jonathan Hoffmann, Emilie Westeel, Fabiola Bastian, et al. "Rifampicin exposure reveals within-host Mycobacterium tuberculosis diversity in patients with delayed culture conversion." PLOS Pathogens 17, no. 6 (June 24, 2021): e1009643. http://dx.doi.org/10.1371/journal.ppat.1009643.
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Mycobacterium tuberculosis (Mtb) genetic micro-diversity in clinical isolates may underline mycobacterial adaptation to tuberculosis (TB) infection and provide insights to anti-TB treatment response and emergence of resistance. Herein we followed within-host evolution of Mtb clinical isolates in two cohorts of TB patients, either with delayed Mtb culture conversion (> 2 months), or with fast culture conversion (< 2 months). We captured the genetic diversity of Mtb isolates obtained in each patient, by focusing on minor variants detected as unfixed single nucleotide polymorphisms (SNPs). To unmask antibiotic tolerant sub-populations, we exposed these isolates to rifampicin (RIF) prior to whole genome sequencing (WGS) analysis. Thanks to WGS, we detected at least 1 unfixed SNP within the Mtb isolates for 9/15 patients with delayed culture conversion, and non-synonymous (ns) SNPs for 8/15 patients. Furthermore, RIF exposure revealed 9 additional unfixed nsSNP from 6/15 isolates unlinked to drug resistance. By contrast, in the fast culture conversion cohort, RIF exposure only revealed 2 unfixed nsSNP from 2/20 patients. To better understand the dynamics of Mtb micro-diversity, we investigated the variant composition of a persistent Mtb clinical isolate before and after controlled stress experiments mimicking the course of TB disease. A minor variant, featuring a particular mycocerosates profile, became enriched during both RIF exposure and macrophage infection. The variant was associated with drug tolerance and intracellular persistence, consistent with the pharmacological modeling predicting increased risk of treatment failure. A thorough study of such variants not necessarily linked to canonical drug-resistance, but which are prone to promote anti-TB drug tolerance, may be crucial to prevent the subsequent emergence of resistance. Taken together, the present findings support the further exploration of Mtb micro-diversity as a promising tool to detect patients at risk of poorly responding to anti-TB treatment, ultimately allowing improved and personalized TB management.
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Iacobino, Angelo, Lanfranco Fattorini, and Federico Giannoni. "Drug-Resistant Tuberculosis 2020: Where We Stand." Applied Sciences 10, no. 6 (March 22, 2020): 2153. http://dx.doi.org/10.3390/app10062153.
Full textAbstract:
The control of tuberculosis (TB) is hampered by the emergence of multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) strains, defined as resistant to at least isoniazid and rifampin, the two bactericidal drugs essential for the treatment of the disease. Due to the worldwide estimate of almost half a million incident cases of MDR/rifampin-resistant TB, it is important to continuously update the knowledge on the mechanisms involved in the development of this phenomenon. Clinical, biological and microbiological reasons account for the generation of resistance, including: (i) nonadherence of patients to their therapy, and/or errors of physicians in therapy management, (ii) complexity and poor vascularization of granulomatous lesions, which obstruct drug distribution to some sites, resulting in resistance development, (iii) intrinsic drug resistance of tubercle bacilli, (iv) formation of non-replicating, drug-tolerant bacilli inside the granulomas, (v) development of mutations in Mtb genes, which are the most important molecular mechanisms of resistance. This review provides a comprehensive overview of these issues, and releases up-dated information on the therapeutic strategies recently endorsed and recommended by the World Health Organization to facilitate the clinical and microbiological management of drug-resistant TB at the global level, with attention also to the most recent diagnostic methods.
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Yadav, Pramod. "Challenges & Solutions for Recent Advancements in Multi-Drugs Resistance Tuberculosis: A Review." Microbiology Insights 16 (January 2023): 117863612311524. http://dx.doi.org/10.1177/11786361231152438.
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In MDR-TB, mycobacterium is resistant to battlefront drugs like rifampicin and isoniazid. Now it’s an urgent global challenge for treatment & diagnosis because more than 50% of drugs are resistant. Till today's information, 5 reasons are liable for MDR: (1) Errors of physicians/patients in therapy management, (2) Complexity and poor vascularization of granulomatous lesions, which obstruct drug distribution to some sites, leading to resistance development, (3) Intrinsic drug resistance of tubercle bacilli, (4) Formation of non-replicating, drug-tolerant bacilli inside the granulomas, (5) Development of mutations in Mtb genes, which are the foremost important molecular mechanisms of resistance. the most contribution of this work is a brief & clear explanation of things chargeable for resistant development, and recent diagnostic & treatment methods for MDR-TB. This study shall help researchers & scientists to develop replacement rapid diagnostic tools, drugs, and treatment protocols.
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Choudhury, Sreetama, Ajay Suresh Akhade, and Naeha Subramanian. "Dual RNA-seq as an effective tool to simultaneously identify transcriptional changes in host macrophages and invading intracellular pathogens." Journal of Immunology 204, no. 1_Supplement (May 1, 2020): 227.27. http://dx.doi.org/10.4049/jimmunol.204.supp.227.27.
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Abstract Intracellular pathogens have evolved strategies to subvert the host immune response and establish infection leading to disease. For example, Mycobacterium tuberculosis (MTB) has been recently reported to effectively counteract immunological and anti-tubercular challenges by activating resistance mechanisms that enable the pathogen to attain an immune tolerant state. A systems scale approach using dual RNA Sequencing revealed key transcriptional factors that enabled researchers to discover a drug combination that delivers more effective killing of MTB. On the basis of our preliminary findings we hypothesize that similar to MTB, Salmonella spp. have evolved to escape host macrophage responses by down-regulating the expression of flagellin, a potent activator of the NLRC4 inflammasome, by taking advantage of a natural host negative feedback mechanism that allows the pathogen to reside intracellularly within macrophages. However, how Salmonella and host transcriptional networks rewire over the course of infection to permit development of an immune-evasive phenotype in the pathogen remains unknown. Using dual RNA-Seq and regulatory network analysis, we propose to simultaneously identify the molecular changes that occur in both the host and the pathogen during infection. We aim to conduct a temporal study to find transcriptional changes at different time points post infection that lead to development of a permissive host environment and allow Salmonella to undergo immune escape within macrophages. Our study will help identify the key regulators that shape host-pathogen crosstalk over the course of Salmonella infection with potentially important implications for bacterial pathogenesis and immunity.
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Ivanenko, N. "BIOFILM AND TUMOR: INTERPRETATION OF INTERACTION AND TREATMENT STRATEGIES. Review." Medical Science of Ukraine (MSU) 17, no. 1 (March 30, 2021): 104–20. http://dx.doi.org/10.32345/2664-4738.1.2021.13.
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Relevance. Treatment of solid tumors and biofilm-derived infections face a common problem: drugs often fail to reach and kill cancer cells and microbial pathogens because of local microenvironment heterogeneities. There are remarkable challenges for current and prospective anticancer and antibiofilm agents to target and maintain activity in the microenvironments where cancer cells and microbial pathogens survive and cause the onset of disease. Bacterial infections in cancer formation will increase in the coming years. Collection of approaches such as ROS modulation in cells, the tumor is promoted by microbe’s inflammation can be a strategy to target cancer and bacteria. Besides that, bacteria may take the advantage of oxygen tension and permissive carbon sources, therefore the tumor microenvironment (TM) becomes a potential refuge for bacteria. It is noteworthy that the relationship between cancer and bacteria is intertwined.
Objective: To analyze similarities between biofilm and tumor milieu that is produced against stress conditions and heterogeneous microenvironment for a combination of approaches the bacteriotherapy with chemotherapy which can help in defeating the tumor heterogeneity accompanied with malignancy, drug-resistance, and metastasis.
Method: An analytical review of the literature on keywords from the scientometric databases PubMed, Wiley.
Results: Bacteria evade antimicrobial treatment is mainly due to persistence that has become dormant during the stationary phase and tolerance. Drug-tolerant persisters and cellular dormancy are crucial in the development of cancer, especially in understanding the development of metastases as a late relapse. Biofilms are formed by groups of cells in different states, growing or non-growing and metabolically active or inactive in variable fractions, depending on maturity and on chemical gradients (O2 and nutrients) of the biofilms producing physiological heterogeneity. Heterogeneity in the microenvironment of cancer can be described as a non-cell autonomous driver of cancer cell diversity; in a highly diverse microenvironment, different cellular phenotypes may be selected for or against in different regions of the tumor. Hypoxia, oxidative stress, and inflammation have been identified as positive regulators of metastatic potential, drug resistance, and tumorigenic properties in cancer. It is proven that, Escherichia coli (E. coli) and life-threatening infectious pathogens such as Staphylococcus aureus (SA) and Mycobacterium tuberculosis (Mtb) are noticeably sensitive to alterations in the intracellular oxidative environment. An alternative emerging paradigm is that many cancers may be promoted by commensal microbiota, either by translocation and adherence of microbes to cancer cells or by the distant release of inflammation-activating microbial metabolites. Microbial factors such as F. nucleatum, B. fragilis, and Enterobacteriaceae members may contribute to disease onset in patients with a hereditary form of colorectal cancer (CRC); familial adenomatous polyposis (FAP). These findings are linked with the creation of new biomarkers and therapy for identifying and treating biofilm-associated cancers. Currently, about 20% of neoplasms globally can be caused by infections, with approximately 1.2 million cases annually. Several antineoplastic drugs that exhibited activity against S. mutans, including tamoxifen, doxorubicin, and ponatinib, also possessed activity against other Gram-positive bacteria. Drug repurposing, also known as repositioning, has gained momentum, mostly due to its advantages over de novo drug discovery, including reduced risk to patients due to previously documented clinical trials, lower drug development costs, and faster benchtop-to-clinic transition. Although many bacteria are carcinogens and tumor promoters, some have shown great potential towards cancer therapy. Several species of bacteria have shown an impressive power to penetrate and colonize solid tumors, which has mainly led to neoplasm slower growth and tumor clearance. Different strains of Clostridia, Lactococcus, Bifidobacteria, Shigella, Vibrio, Listeria, Escherichia, and Salmonella have been evaluated against cancer in animal models.
Conclusion. Cancer is a multifactorial disease and the use of bacteria for cancer therapy as an immunostimulatory agent or as a vector for carrying the therapeutic cargo is a promising treatment method. Therefore, the world has turned to an alternative solution, which is the use of genetically engineered microorganisms; thus, the use of living bacteria targeting cancerous cells is the unique option to overcome these challenges. Bacterial therapies, whether used alone or combination with chemotherapy, give a positive effect to treat multiple conditions of cancer.
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Lin, Haifeng, Jie Ma, Manyun Zhuo, Chengsheng Zhang, Jingru Luo, Xiaohong Zhuang, Zhiming Zeng, and Lihua Yang. "Preliminary results of the phase II ALTER-H003 trial: Anlotinib plus toripalimab as a first-line treatment for patients with unresectable hepatocellular carcinoma." Journal of Clinical Oncology 39, no. 3_suppl (January 20, 2021): 314. http://dx.doi.org/10.1200/jco.2021.39.3_suppl.314.
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314 Background: Hepatocellular carcinoma (HCC) is particularly prevalent in China because of the high prevalence of chronic hepatitis B infection. In the last decade, sorafenib was the first molecular target drug approved for the treatment of advanced liver cancer. Until recently, the combination of angiogenic inhibitor with anti-PD-1 /L1 monoclonal antibody has represented significant efficacy over sorafenib monotherapy in the first-line regimen of unresectable HCC. Nevertheless, there are still unmet needs in clinical practice due to limited choice of drugs. Anlotinib is a novel oral multi-targeted tyrosine kinase inhibitor that targets VEGF receptors 1/2/3, FGF receptors 1-4, PDGF receptors α and β, and c-kit, and has been approved for standard treatment of non-small cell lung cancer, small cell lung cancer and soft tissue sarcoma in China. Toripalimab, a humanized IgG4 mAb against PD-1, is the first Chinese-produced PD-1 inhibitor marketed, which has been approved as a second-line treatment for metastasis melanoma. This study aims to evaluate the efficacy and safety of anlotinib plus toripalimab as the first-line treatment for unresectable HCC. Methods: This was a single-arm, multicenter, phase II trial. 30 patients with unresectable HCC, Child-Pugh ≤7 and ECOG PS <2 will be enrolled if they had not been treated with prior treatment. Pts received anlotinib (12 mg, p.o., qd, d1-14, q3w) and toripalimab (240 mg, iv, d1, q3w) until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR) assessed by investigator according to mRECIST and irRECIST. Secondary endpoints included progression-free survival (PFS), overall survival (OS), disease control rate (DCR), duration of response (DoR) and safety. Results: By the cutoff date of September 21, 2020, 11 pts were enrolled and of those 8 pts were evaluable. 9 pts (81.8%) experienced treatment related adverse events (TRAEs) and grade 3 TRAEs occurred in 5 pts (45.5%). No grade 4 or above TRAEs occurred. The most common TRAEs were decreased appetite (n =6, 54.5%) and fatigue (n =5, 45.5%).Among 8 evaluable pts, unconfirmed ORR was 25% (95% CI 0.032-0.651) with 1 unconfirmed CR and 1 unconfirmed PR, and DCR was 87.5% (95% CI 0.473-0.997) according to mRECIST. Conclusions: Anlotinib in combination with toripalimab showed tolerant toxicity and preliminary anti-tumor efficacy in first-line regimen for uHCC patients. Furthermore, it is needed to be proved in update results and large scale studies. Clinical trial information: ChiCTR1900028295.
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Samuels, Amanda N., Erin R. Wang, Gregory A. Harrison, Joy C. Valenta, and Christina L. Stallings. "Understanding the contribution of metabolism to Mycobacterium tuberculosis drug tolerance." Frontiers in Cellular and Infection Microbiology 12 (August 22, 2022). http://dx.doi.org/10.3389/fcimb.2022.958555.
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Treatment of Mycobacterium tuberculosis (Mtb) infections is particularly arduous. One challenge to effectively treating tuberculosis is that drug efficacy in vivo often fails to match drug efficacy in vitro. This is due to multiple reasons, including inadequate drug concentrations reaching Mtb at the site of infection and physiological changes of Mtb in response to host derived stresses that render the bacteria more tolerant to antibiotics. To more effectively and efficiently treat tuberculosis, it is necessary to better understand the physiologic state of Mtb that promotes drug tolerance in the host. Towards this end, multiple studies have converged on bacterial central carbon metabolism as a critical contributor to Mtb drug tolerance. In this review, we present the evidence that changes in central carbon metabolism can promote drug tolerance, depending on the environment surrounding Mtb. We posit that these metabolic pathways could be potential drug targets to stymie the development of drug tolerance and enhance the efficacy of current antimicrobial therapy.
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Kreutzfeldt, Kaj M., Robert S. Jansen, Travis E. Hartman, Alexandre Gouzy, Ruojun Wang, Inna V. Krieger, Matthew D. Zimmerman, et al. "CinA mediates multidrug tolerance in Mycobacterium tuberculosis." Nature Communications 13, no. 1 (April 22, 2022). http://dx.doi.org/10.1038/s41467-022-29832-1.
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AbstractThe ability of Mycobacterium tuberculosis (Mtb) to resist and tolerate antibiotics complicates the development of improved tuberculosis (TB) chemotherapies. Here we define the Mtb protein CinA as a major determinant of drug tolerance and as a potential target to shorten TB chemotherapy. By reducing the fraction of drug-tolerant persisters, genetic inactivation of cinA accelerated killing of Mtb by four antibiotics in clinical use: isoniazid, ethionamide, delamanid and pretomanid. Mtb ΔcinA was killed rapidly in conditions known to impede the efficacy of isoniazid, such as during nutrient starvation, during persistence in a caseum mimetic, in activated macrophages and during chronic mouse infection. Deletion of CinA also increased in vivo killing of Mtb by BPaL, a combination of pretomanid, bedaquiline and linezolid that is used to treat highly drug-resistant TB. Genetic and drug metabolism studies suggest that CinA mediates drug tolerance via cleavage of NAD-drug adducts.
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Eoh, Hyungjin, Rachel Liu, Juhyeon Lim, Jae Jin Lee, and Philip Sell. "Central carbon metabolism remodeling as a mechanism to develop drug tolerance and drug resistance in Mycobacterium tuberculosis." Frontiers in Cellular and Infection Microbiology 12 (August 22, 2022). http://dx.doi.org/10.3389/fcimb.2022.958240.
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Suboptimal efficacy of the current antibiotic regimens and frequent emergence of antibiotic-resistant Mycobacterium tuberculosis (Mtb), an etiological agent of tuberculosis (TB), render TB the world’s deadliest infectious disease before the COVID-19 outbreak. Our outdated TB treatment method is designed to eradicate actively replicating populations of Mtb. Unfortunately, accumulating evidence suggests that a small population of Mtb can survive antimycobacterial pressure of antibiotics by entering a “persister” state (slowly replicating or non-replicating and lacking a stably heritable antibiotic resistance, termed drug tolerance). The formation of drug-tolerant Mtb persisters is associated with TB treatment failure and is thought to be an adaptive strategy for eventual development of permanent genetic mutation-mediated drug resistance. Thus, the molecular mechanisms behind persister formation and drug tolerance acquisition are a source of new antibiotic targets to eradicate both Mtb persisters and drug-resistant Mtb. As Mtb persisters are genetically identical to antibiotic susceptible populations, metabolomics has emerged as a vital biochemical tool to differentiate these populations by determining phenotypic shifts and metabolic reprogramming. Metabolomics, which provides detailed insights into the molecular basis of drug tolerance and resistance in Mtb, has unique advantages over other techniques by its ability to identify specific metabolic differences between the two genetically identical populations. This review summarizes the recent advances in our understanding of the metabolic adaptations used by Mtb persisters to achieve intrinsic drug tolerance and facilitate the emergence of drug resistance. These findings present metabolomics as a powerful tool to identify previously unexplored antibiotic targets and improved combinations of drug regimens against drug-resistant TB infection.
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Sarathy, Jansy P., Min Xie, Richard M. Jones, Adrienne Chang, Paulina Osiecki, Danielle Weiner, Wen-Shan Tsao, et al. "A Novel Tool to Identify Bactericidal Compounds against Vulnerable Targets in Drug-Tolerant M. tuberculosis found in Caseum." mBio, April 5, 2023. http://dx.doi.org/10.1128/mbio.00598-23.
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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.
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Shankaran, Deepthi, Anjali Singh, Stanzin Dawa, Prabhakar Arumugam, Sheetal Gandotra, and Vivek Rao. "The antidepressant sertraline provides a novel host directed therapy module for augmenting TB therapy." eLife 12 (January 11, 2023). http://dx.doi.org/10.7554/elife.64834.
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A prolonged therapy, primarily responsible for development of drug resistance by Mycobacterium tuberculosis (Mtb), obligates any new TB regimen to not only reduce treatment duration but also escape pathogen resistance mechanisms. With the aim of harnessing the host response in providing support to existing regimens, we used sertraline (SRT) to stunt the pro-pathogenic type I IFN response of macrophages to infection. While SRT alone could only arrest bacterial growth, it effectively escalated the bactericidal activities of Isoniazid (H) and Rifampicin (R) in macrophages. This strengthening of antibiotic potencies by SRT was more evident in conditions of ineffective control by these frontline TB drug, against tolerant strains or dormant Mtb. SRT, could significantly combine with standard TB drugs to enhance early pathogen clearance from tissues of mice infected with either drug sensitive/ tolerant strains of Mtb. Further, we demonstrate an enhanced protection in acute TB infection of the highly susceptible C3HeB/FeJ mice with the combination therapy signifying the use of SRT as a potent adjunct to standard TB therapeutic regimens against bacterial populations of diverse physiology. This study advocates a novel host directed adjunct therapy regimen for TB with a clinically approved anti-depressant to achieve quicker and greater control of infection.
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Khan, Mehak Zahoor, and Vinay Kumar Nandicoori. "Deletion of pknG Abates Reactivation of Latent Mycobacterium tuberculosis in Mice." Antimicrobial Agents and Chemotherapy 65, no. 4 (March 18, 2021). http://dx.doi.org/10.1128/aac.02095-20.
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Eradication of tuberculosis (TB), caused by Mycobacterium tuberculosis ( Mtb ), has been a challenge due to its uncanny ability to survive in a dormant state inside host granulomas for decades. Mtb rewires its metabolic and redox regulatory networks to survive in the hostile hypoxic and nutrient-limiting environment, facilitating the formation of drug-tolerant persisters. Previously, we showed that protein kinase G (PknG), a virulence factor required for lysosomal escape, aids in metabolic adaptation, thereby promoting the survival of nonreplicating mycobacteria.
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Immanuel, Selva Rupa Christinal, Mario L. Arrieta-Ortiz, Rene A. Ruiz, Min Pan, Adrian Lopez Garcia de Lomana, Eliza J. R. Peterson, and Nitin S. Baliga. "Quantitative prediction of conditional vulnerabilities in regulatory and metabolic networks using PRIME." npj Systems Biology and Applications 7, no. 1 (December 2021). http://dx.doi.org/10.1038/s41540-021-00205-6.
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AbstractThe ability of Mycobacterium tuberculosis (Mtb) to adopt heterogeneous physiological states underlies its success in evading the immune system and tolerating antibiotic killing. Drug tolerant phenotypes are a major reason why the tuberculosis (TB) mortality rate is so high, with over 1.8 million deaths annually. To develop new TB therapeutics that better treat the infection (faster and more completely), a systems-level approach is needed to reveal the complexity of network-based adaptations of Mtb. Here, we report a new predictive model called PRIME (Phenotype of Regulatory influences Integrated with Metabolism and Environment) to uncover environment-specific vulnerabilities within the regulatory and metabolic networks of Mtb. Through extensive performance evaluations using genome-wide fitness screens, we demonstrate that PRIME makes mechanistically accurate predictions of context-specific vulnerabilities within the integrated regulatory and metabolic networks of Mtb, accurately rank-ordering targets for potentiating treatment with frontline drugs.
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Tükenmez, Hasan, Souvik Sarkar, Saber Anoosheh, Anastasiia Kruchanova, Isabel Edström, Gregory A. Harrison, Christina L. Stallings, Fredrik Almqvist, and Christer Larsson. "Mycobacterium tuberculosis Rv3160c is a TetR-like transcriptional repressor that regulates expression of the putative oxygenase Rv3161c." Scientific Reports 11, no. 1 (January 15, 2021). http://dx.doi.org/10.1038/s41598-021-81104-y.
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AbstractTuberculosis, caused by Mycobacterium tuberculosis (Mtb), is a major health threat listed among the top 10 causes of death worldwide. Treatment of multidrug-resistant Mtb requires use of additional second-line drugs that prolong the treatment process and result in higher death rates. Our team previously identified a 2-pyridone molecule (C10) that blocks tolerance to the first-line drug isoniazid at C10 concentrations that do not inhibit bacterial growth. Here, we discovered that the genes rv3160c and rv3161c are highly induced by C10, which led us to investigate them as potential targets. We show that Rv3160c acts as a TetR-like transcriptional repressor binding to a palindromic sequence located in the rv3161c promoter. We also demonstrate that C10 interacts with Rv3160c, inhibiting its binding to DNA. We deleted the rv3161c gene, coding for a putative oxygenase, to investigate its role in drug and stress sensitivity as well as C10 activity. This Δrv3161c strain was more tolerant to isoniazid and lysozyme than wild type Mtb. However, this tolerance could still be blocked by C10, suggesting that C10 functions independently of Rv3161c to influence isoniazid and lysozyme sensitivity.
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De Siena, Barbara, Nicoletta Campolattano, Gianluca D’Abrosca, Luigi Russo, Daire Cantillon, Rosangela Marasco, Lidia Muscariello, Simon J. Waddell, and Margherita Sacco. "Characterization of the Mycobacterial MSMEG-3762/63 Efflux Pump in Mycobacterium smegmatis Drug Efflux." Frontiers in Microbiology 11 (December 3, 2020). http://dx.doi.org/10.3389/fmicb.2020.575828.
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Multi-drug resistant tuberculosis (MDR-TB) represents a major health problem worldwide. Drug efflux and the activity of efflux transporters likely play important roles in the development of drug-tolerant and drug-resistant mycobacterial phenotypes. This study is focused on the action of a mycobacterial efflux pump as a mechanism of drug resistance. Previous studies demonstrated up-regulation of the TetR-like transcriptional regulator MSMEG_3765 in Mycobacterium smegmatis and its ortholog Rv1685c in Mycobacterium tuberculosis (Mtb) in acid-nitrosative stress conditions. MSMEG-3765 regulates the expression of the MSMEG_3762/63/65 operon, and of the orthologous region in Mtb (Rv1687c/86c/85c). MSMEG-3762 and Rv1687c are annotated as ATP-binding proteins, while MSMEG-3763 and Rv1686c are annotated as trans-membrane polypeptides, defining an ABC efflux pump in both M. smegmatis and Mtb. The two putative efflux systems share a high percentage of identity. To examine the role of the putative efflux system MSMEG-3762/63, we constructed and characterized a MSMEG-3763 deletion mutant in M. smegmatis (∆MSMEG_3763). By comparative analysis of wild type, knockout, and complemented strains, together with structural modeling and molecular docking bioinformatics analyses of the MSMEG-3763 trans-membrane protein, we define the protein complex MSMEG-3762/63 as an efflux pump. Moreover, we demonstrate involvement of this pump in biofilm development and in the extrusion of rifampicin and ciprofloxacin (CIP), antimicrobial drugs used in first- and second-line anti-TB therapies.
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Srinivas, Vivek, Mario L. Arrieta-Ortiz, Amardeep Kaur, Eliza J. R. Peterson, and Nitin S. Baliga. "PerSort Facilitates Characterization and Elimination of Persister Subpopulation in Mycobacteria." mSystems 5, no. 6 (December 1, 2020). http://dx.doi.org/10.1128/msystems.01127-20.
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ABSTRACT Mycobacterium tuberculosis (MTB) generates phenotypic diversity to persist and survive the harsh conditions encountered during infection. MTB avoids immune effectors and antibacterial killing by entering into distinct physiological states. The surviving cells, persisters, are a major barrier to the timely and relapse-free treatment of tuberculosis (TB). We present for the first time, PerSort, a method to isolate and characterize persisters in the absence of antibiotic or other pressure. We demonstrate the value of PerSort to isolate translationally dormant cells that preexisted in small numbers within Mycobacterium species cultures growing under optimal conditions but that dramatically increased in proportion under stress conditions. The translationally dormant subpopulation exhibited multidrug tolerance and regrowth properties consistent with those of persister cells. Furthermore, PerSort enabled single-cell transcriptional profiling that provided evidence that the translationally dormant persisters were generated through a variety of mechanisms, including vapC30, mazF, and relA/spoT overexpression. Finally, we demonstrate that notwithstanding the varied mechanisms by which the persister cells were generated, they converge on a similar low-oxygen metabolic state that was reversed through activation of respiration to rapidly eliminate persisters fostered under host-relevant stress conditions. We conclude that PerSort provides a new tool to study MTB persisters, enabling targeted strategies to improve and shorten the treatment of TB. IMPORTANCE Mycobacterium tuberculosis (MTB) persists and survives antibiotic treatments by generating phenotypically heterogeneous drug-tolerant subpopulations. The surviving cells, persisters, are a major barrier to the relapse-free treatment of tuberculosis (TB), which is already killing >1.8 million people every year and becoming deadlier with the emergence of multidrug-resistant strains. This study describes PerSort, a cell sorting method to isolate and characterize, without antibiotic treatment, translationally dormant persisters that preexist in small numbers within Mycobacterium cultures. Characterization of this subpopulation has discovered multiple mechanisms by which mycobacterial persisters emerge and unveiled the physiological basis for their dormant and multidrug-tolerant physiological state. This analysis has discovered that activating oxygen respiratory physiology using l-cysteine eliminates preexisting persister subpopulations, potentiating rapid antibiotic killing of mycobacteria under host-relevant stress. PerSort serves as a new tool to study MTB persisters for enabling targeted strategies to improve and shorten the treatment of TB.
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Mitini-Nkhoma, Steven C., Elizabeth T. Chimbayo, David T. Mzinza, David V. Mhango, Aaron P. Chirambo, Christine Mandalasi, Agness E. Lakudzala, Dumizulu L. Tembo, Kondwani C. Jambo, and Henry C. Mwandumba. "Something Old, Something New: Ion Channel Blockers as Potential Anti-Tuberculosis Agents." Frontiers in Immunology 12 (June 24, 2021). http://dx.doi.org/10.3389/fimmu.2021.665785.
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Tuberculosis (TB) remains a challenging global health concern and claims more than a million lives every year. We lack an effective vaccine and understanding of what constitutes protective immunity against TB to inform rational vaccine design. Moreover, treatment of TB requires prolonged use of multi-drug regimens and is complicated by problems of compliance and drug resistance. While most Mycobacterium tuberculosis (Mtb) bacilli are quickly killed by the drugs, the prolonged course of treatment is required to clear persistent drug-tolerant subpopulations. Mtb’s differential sensitivity to drugs is, at least in part, determined by the interaction between the bacilli and different host macrophage populations. Therefore, to design better treatment regimens for TB, we need to understand and modulate the heterogeneity and divergent responses that Mtb bacilli exhibit within macrophages. However, developing drugs de-novo is a long and expensive process. An alternative approach to expedite the development of new TB treatments is to repurpose existing drugs that were developed for other therapeutic purposes if they also possess anti-tuberculosis activity. There is growing interest in the use of immune modulators to supplement current anti-TB drugs by enhancing the host’s antimycobacterial responses. Ion channel blocking agents are among the most promising of the host-directed therapeutics. Some ion channel blockers also interfere with the activity of mycobacterial efflux pumps. In this review, we discuss some of the ion channel blockers that have shown promise as potential anti-TB agents.
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Mavi, Parminder Singh, Shweta Singh, and Ashwani Kumar. "Media component bovine serum albumin facilitates the formation of mycobacterial biofilms in response to reductive stress." BMC Microbiology 23, no. 1 (April 20, 2023). http://dx.doi.org/10.1186/s12866-023-02853-6.
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Abstract Background Mycobacterium tuberculosis (Mtb) forms physiologically relevant biofilms harboring drug-tolerant bacteria. This observation has brought the study of mycobacterial biofilms to the forefront of tuberculosis research. We established earlier that dithiothreitol (DTT) mediated reductive stress induces cellulose-rich biofilm formation in Mtb cultures. The molecular events associated with the DTT-induced biofilm formation are not known. Furthermore, there are only limited tools for monitoring the presence of cellulose in biofilms. Results To decipher the molecular events associated with DTT-induced biofilm formation, we used Mtb and non-pathogenic, fast-growing Mycobacterium smegmatis (Msm). We observed that DTT induces biofilm formation in Msm cultures. We explored whether media components facilitate biofilm formation in mycobacteria upon exposure to DTT. We observed that media component bovine serum albumin promotes mycobacterial biofilm formation in response to DTT. Furthermore, we analyzed the composition of extracellular polymeric substances of Msm biofilms. We found that, like Mtb biofilms, Msm biofilms are also rich in polysaccharides and proteins. We also developed a novel protein-based molecular probe for imaging cellulose by utilizing the cellulose-binding domain of cellulase CenA from Cellulomonas fimi and fusing it to fluorescent reporter mCherry. Characterization of this new probe revealed that it has a high affinity for cellulose and could be used for visualizing cellulose biosynthesis during the development of Agrobacterium biofilms. Furthermore, we have demonstrated that biological macromolecule cellulose is present in the extracellular polymeric substances of Msm biofilms using this novel probe. Conclusions This study indicates that DTT-mediated reduction of media component BSA leads to the formation of nucleating foci. These nucleating foci are critical for subsequent attachment of bacterial cells and induction of EPS production. Furthermore, this new tool, IMT-CBD-mC, could be used for monitoring cellulose incorporation in plant cells, understanding cellulose biosynthesis dynamics during biofilm formation, etc.
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Yamamoto, Kentaro, Noboru Nakata, Tetsu Mukai, Ikuro Kawagishi, and Manabu Ato. "Coexpression of MmpS5 and MmpL5 Contributes to Both Efflux Transporter MmpL5 Trimerization and Drug Resistance in Mycobacterium tuberculosis." mSphere 6, no. 1 (January 6, 2021). http://dx.doi.org/10.1128/msphere.00518-20.
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ABSTRACT The increasing occurrence of multidrug-resistant Mycobacterium tuberculosis (Mtb) is a serious threat to global public health. Among the many mechanisms of drug resistance, only resistance-nodulation-division (RND)-type multidrug efflux systems can simultaneously render bacteria tolerant to numerous toxic compounds, including antibiotics. The elevated expression of RND-type xenobiotic efflux transporter complexes, which consist of an inner membrane transporter, membrane fusion protein, and outer membrane channel, plays a major role in multidrug resistance. Among the 14 mycobacterial membrane protein large (MmpL) proteins identified as inner membrane transporters of Mtb, MmpL5 is known to participate in the acquisition of resistance to bedaquiline and clofazimine. MmpL5 exports these drugs by forming a complex with the membrane fusion protein mycobacterial membrane protein small 5 (MmpS5). However, the role of MmpS5 in the efflux of antituberculous drugs by MmpL5 remains unclear. In this study, we focused on the in vivo dynamics of MmpL5 using green fluorescent protein (GFP). Single-molecule observations of MmpL5 showed substantial lateral displacements of MmpL5-GFP without the expression of MmpS5. Nondiffusing MmpL5-GFP foci typically showed three-step photobleaching, suggesting that MmpL5 formed a homotrimeric functional complex on the inner membrane in the presence of MmpS5. These results suggest that the expression of MmpS5 facilitates the assembly of monomeric MmpL5 into a homotrimer that is anchored to the inner membrane to transport various antimycobacterial drugs. IMPORTANCE It has been reported that mycobacterial membrane protein large 5 (MmpL5), a resistance-nodulation-division (RND)-type inner membrane transporter in Mycobacterium tuberculosis (Mtb), is involved in the transport of antimycobacterial drugs. However, the functional roles of the membrane fusion protein mycobacterial membrane protein small 5 (MmpS5), organized as an operon with MmpL5, are unclear. Via the single-molecule imaging of MmpL5, we uncovered the maintenance of the functional trimeric complex structure of MmpL5 in the presence of MmpS5. These findings demonstrate that the assembly mechanisms of mycobacterial RND efflux systems are the dynamically regulated process through interactions among the components. This represents the first report of the single-molecule observation of Mtb efflux transporters, which may enhance our understanding of innate antibiotic resistance.
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Hasenoehrl, Erik J., Thomas J. Wiggins, and Michael Berney. "Bioenergetic Inhibitors: Antibiotic Efficacy and Mechanisms of Action in Mycobacterium tuberculosis." Frontiers in Cellular and Infection Microbiology 10 (January 11, 2021). http://dx.doi.org/10.3389/fcimb.2020.611683.
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Development of novel anti-tuberculosis combination regimens that increase efficacy and reduce treatment timelines will improve patient compliance, limit side-effects, reduce costs, and enhance cure rates. Such advancements would significantly improve the global TB burden and reduce drug resistance acquisition. Bioenergetics has received considerable attention in recent years as a fertile area for anti-tuberculosis drug discovery. Targeting the electron transport chain (ETC) and oxidative phosphorylation machinery promises not only to kill growing cells but also metabolically dormant bacilli that are inherently more drug tolerant. Over the last two decades, a broad array of drugs targeting various ETC components have been developed. Here, we provide a focused review of the current state of art of bioenergetic inhibitors of Mtb with an in-depth analysis of the metabolic and bioenergetic disruptions caused by specific target inhibition as well as their synergistic and antagonistic interactions with other drugs. This foundation is then used to explore the reigning theories on the mechanisms of antibiotic-induced cell death and we discuss how bioenergetic inhibitors in particular fail to be adequately described by these models. These discussions lead us to develop a clear roadmap for new lines of investigation to better understand the mechanisms of action of these drugs with complex mechanisms as well as how to leverage that knowledge for the development of novel, rationally-designed combination therapies to cure TB.
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Goyal, Akanksha, Maria Hauswald, Helen McCallum, Gerald Hoebarth, and Annette Feussner. "Fit-for-purpose validation of a drug-tolerant immunogenicity assay for a human mAb drug in animal safety studies." Journal of Immunological Methods, December 2022, 113406. http://dx.doi.org/10.1016/j.jim.2022.113406.
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Kilany, Lobna Abdel Aziz, Ayman Abdel Samie Gaber, Mohammad Mabrouk Aboulwafa, and Hamdallah Hafez Zedan. "Trastuzumab immunogenicity development in patients’ sera and in laboratory animals." BMC Immunology 22, no. 1 (February 19, 2021). http://dx.doi.org/10.1186/s12865-021-00405-z.
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Abstract Background Immunogenicity is a major challenge in drug development and patient care. Clinicians and regulators are familiar with immunogenicity concerns of monoclonal antibody (mAb) therapeutics, growth factors and enzyme replacements. Although most small therapeutic molecules are unlikely to trigger undesirable immunogenic responses against themselves upon their administration, the biological therapeutic agents are likely to induce such kind of immunogenicity. This imparts a problem that has to be considered upon judging their risk–benefit ratio. In this article, we tested the immunogenicity developed in patients’ sera due to the use of trastuzumab and that developed in laboratory animals injected with this recombinant humanized IgG1 monoclonal antibody. Methods We studied trastuzumab immunogenicity by: I in vitro detection of anti-trastuzumab antibody (Ab) levels in patient’s serum samples withdrawn at different points during trastuzumab treatment course; I.1 using an Affinity Capture Elution (ACE) assay, the assay is both sensitive and highly tolerant to free drug; I.2 using MTT cytotoxicity method against MCF-7 cell line as confirmatory method used in sample showed high level of anti-trastuzumab Ab and to determine neutralizing activity of the anti-trastuzumab Ab. II in vivo immunogenicity testing of trastuzumab in lab animals. Results In vitro analysis of patients’ sera for antibodies developed against trastuzumab revealed that this monoclonal antibody has low immunogenicity since most samples showed low levels of anti-trastuzumab antibodies that decreased progressively along the treatment course. Only 1% of samples showed high levels of anti-trastuzumab antibodies which might affect treatment course. In vivo immunogenicity testing in mice showed also low immunogenicity of trastuzumab that could support the in vitro clinical assessment applied in our study. Conclusions The study gives an evidence for the low trastuzumab immunogenicity when assessed in Egyptian patients under treatment with this biological therapeutic agent. This supports its prescription and continuous use across the approved indications as biological therapeutic agent.