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1.
Undernutrition and Tuberculosis: Public Health Implications.
Sinha, P, Davis, J, Saag, L, Wanke, C, Salgame, P, Mesick, J, Horsburgh, CR, Hochberg, NS
The Journal of infectious diseases. 2019;(9):1356-1363
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Abstract
Almost 800 million people are chronically undernourished worldwide, of whom 98% are in low- and middle-income countries where tuberculosis is endemic. In many tuberculosis-endemic countries, undernutrition is a driver of tuberculosis incidence and associated with a high population attributable fraction of tuberculosis and poor treatment outcomes. Data suggest that undernutrition impairs innate and adaptive immune responses needed to control Mycobacterium tuberculosis infection and may affect responses to live vaccines, such as BCG. Given its impact on tuberculosis, addressing undernutrition will be a vital component of the World Health Organization End TB strategy. This narrative review describes the effect of undernutrition on the immune response, vaccine response, and tuberculosis incidence, severity, and treatment outcomes.
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2.
A review on anti-tuberculosis peptides: Impact of peptide structure on anti-tuberculosis activity.
Yathursan, S, Wiles, S, Read, H, Sarojini, V
Journal of peptide science : an official publication of the European Peptide Society. 2019;(11):e3213
Abstract
Antibiotic resistance is a major public health problem globally. Particularly concerning amongst drug-resistant human pathogens is Mycobacterium tuberculosis that causes the deadly infectious tuberculosis (TB) disease. Significant issues associated with current treatment options for drug-resistant TB and the high rate of mortality from the disease makes the development of novel treatment options against this pathogen an urgent need. Antimicrobial peptides are part of innate immunity in all forms of life and could provide a potential solution against drug-resistant TB. This review is a critical analysis of antimicrobial peptides that are reported to be active against the M tuberculosis complex exclusively. However, activity on non-TB strains such as Mycobacterium avium and Mycobacterium intracellulare, whenever available, have been included at appropriate sections for these anti-TB peptides. Natural and synthetic antimicrobial peptides of diverse sequences, along with their chemical structures, are presented, discussed, and correlated to their observed antimycobacterial activities. Critical analyses of the structure allied to the anti-mycobacterial activity have allowed us to draw important conclusions and ideas for research and development on these promising molecules to realise their full potential. Even though the review is focussed on peptides, we have briefly summarised the structures and potency of the various small molecule drugs that are available and under development, for TB treatment.
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3.
Cationic Antimicrobial Peptides for Tuberculosis: A Mini-Review.
Silva, S, Vale, N
Current protein & peptide science. 2019;(9):885-892
Abstract
Cationic antimicrobial peptides (CAMPs) can be considered as new potential therapeutic agents for Tuberculosis treatment with a specific amino acid sequence. New studies can be developed in the future to improve the pharmacological properties of CAMPs and also understand possible resistance mechanisms. This review discusses the principal properties of natural and/or synthetic CAMPs, and how these new peptides have a significant specificity for Mycobacterium tuberculosis. Also, we propose some alternative strategies to enhance the therapeutic activity of these CAMPs that include coadministration with nanoparticles and/or classic drugs.
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4.
Targeting DNA Gyrase to Combat Mycobacterium tuberculosis: An Update.
Das, S, Garg, T, Srinivas, N, Dasgupta, A, Chopra, S
Current topics in medicinal chemistry. 2019;(8):579-593
Abstract
DNA gyrase is a clinically validated drug target, currently targeted only by fluoroquinolone class of antibacterials. However, owing to increasing drug resistance as well as a concomitant reduction in the availability of newer classes of antibiotics, fluoroquinolones are increasingly being over-utilized in order to treat serious infections, including multi-drug resistant tuberculosis. This, in turn, increases the probability of resistance to fluoroquinolones, which is mediated by a single amino acid change in gyrA, leading to class-wide resistance. In this review, we provide an overview of the recent progress in identifying novel scaffolds which target DNA gyrase and provide an update on their discovery and development status.
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5.
The lung microbiome, vitamin D, and the tuberculous granuloma: A balance triangle.
Balcells, ME, Yokobori, N, Hong, BY, Corbett, J, Cervantes, J
Microbial pathogenesis. 2019;:158-163
Abstract
Mycobacterium tuberculosis (Mtb) has the extraordinary ability to persist for decades within granulomas in the human host. These histopathological structures involved in both protection and pathogenesis, are subject to various influences from the host systemically and through micro-niche environments. Despite the fact that vitamin D (VD) has a key role in macrophage activation and mycobacterial clearance in the early stages of Mtb infection, the overall role of VD in granuloma maintenance or functionality has been scarcely studied. VD deficiency has long time been known to influence on gut microbiota composition, and recent studies have shown that it can also impact on respiratory microbiome. The human microbiota plays an important role in pathogen colonization resistance, and it has been proposed to play a potential role in TB pathogenesis. In this article, we have reviewed current knowledge on the interaction between VD, the lung microbiome and TB, and propose mechanisms by which the tuberculous granuloma's outcome could be modulated by these two factors. The determinants of the final fate of lung granulomas are still unclear, and deciphering the underlying drivers of Mtb infection outcome within those structures is of critical importance.
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6.
Severe disseminated tuberculosis in HIV-negative refugees.
Suárez, I, Maria Fünger, S, Jung, N, Lehmann, C, Reimer, RP, Mehrkens, D, Bunte, A, Plum, G, Jaspers, N, Schmidt, M, et al
The Lancet. Infectious diseases. 2019;(10):e352-e359
Abstract
In high-income countries, the presentation of tuberculosis is changing, primarily because of migration, and understanding the specific health needs of susceptible populations is becoming increasingly important. Although disseminated tuberculosis is well documented in HIV-positive patients, the disease is poorly described and less expected in HIV-negative individuals. In this Grand Round, we report eight HIV-negative refugees, who presented with extensively disseminated tuberculosis. We discuss the multifactorial causes, such as deprivations during long journeys, precarious living conditions, and the experience of violence, which might add to nutritional factors and chronic disorders, eventually resulting in a state of predisposition to immune deficiency. We also show that disseminated tuberculosis is often difficult to diagnose when pulmonary symptoms are absent. Communication difficulties between refugees and health-care workers are another major hurdle, and every effort should be made to get a valid patient history. This medical history is crucial to guide imaging and other diagnostic procedures to establish a definite diagnosis, which should be confirmed by a positive tuberculosis culture. Because many of these patients are at risk for multidrug-resistant tuberculosis, drug susceptibility testing is imperative to guide therapy. In the absence of treatment guidelines for this entity, clinicians can determine treatment duration according to recommendations provided for extrapulmonary tuberculosis and affected organs. Paradoxical expansion of tuberculous lesions during therapy should be treated with corticosteroids. In many cases, treatment duration must be individualised and might even exceed 12 months.
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7.
Conventional polymerase chain reaction and amplification refractory mutation system-multi-gene/ multi-primer PCR in the diagnosis of female genital tuberculosis.
Bhanothu, V, Venkatesan, V
Archives of microbiology. 2019;(3):267-281
Abstract
This review mainly summarizes disease, immune-pathology and the clinical usefulness, advances, potential applications and limitations of new, cutting-edge technology (MG/MP-PCR and/or ARMS-MG/MP-PCR) in the detection of female genital tuberculosis (FGTB) disease and gene polymorphism among infertile patients. The investigation was set in the Department of Zoology, Osmania University and National Institute of Nutrition, Hyderabad, India. Desired articles were critically reviewed and analysed. Keywords and NET searches were conducted in all electronic databases starting from September, 2006. Full-text English-language reviews and research articles describing FGTB, infertility, gene polymorphism, conventional polymerase chain reaction (PCR) and multigene (MG)/multiprimer (MP)-PCR were included. The current review provides a comprehensive overview on the PCR and types (multiplex, nested, RT etc.) including the reagents, cycling conditions and pitfalls in the detection of FGTB disease and gene polymorphism among infertile patients. It provides limited information on MG/MP-PCR. At present, conventional PCR, MG/MP-PCR and/or amplification refractory mutation system (ARMS)-MG/MP-PCR have emerged as scientific innovations and perform significant function in medical research, mutational analysis and clinical investigations. This review admits that MG/MP-PCR and/or ARMS-MG/MP-PCR has the capacity to diagnose disease rapidly and to genotype a large number of samples. MG/MP-PCR and/or ARMS-MG/MP-PCR are considered as simple, reliable, non-isotopic, low-cost, fast, accurate and relatively easy-to-perform procedure. This review suggests that this method needs to be critically evaluated using huge number of clinical samples occurring across the world and then can be accredited for clinical utilization.
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8.
Changes in Host Response to Mycobacterium tuberculosis Infection Associated With Type 2 Diabetes: Beyond Hyperglycemia.
Segura-Cerda, CA, López-Romero, W, Flores-Valdez, MA
Frontiers in cellular and infection microbiology. 2019;:342
Abstract
Tuberculosis (TB) remains as the first cause of death among infectious diseases worldwide. Global incidence of tuberculosis is in part coincident with incidence of type 2 diabetes (T2D). Incidence of T2D is recognized as a high-risk factor that may contribute to tuberculosis dissemination. However, mechanisms which favor infection under T2D are just starting to emerge. Here, we first discuss the evidences that are available to support a metabolic connection between TB and T2D. Then, we analyze the evidences of metabolic changes which occur during T2D gathered thus far for its influence on susceptibility to M. tuberculosis infection and TB progression, such as hyperglycemia, increase of 1AC levels, increase of triglycerides levels, reduction of HDL-cholesterol levels, increased concentration of lipoproteins, and modification of the activity of some hormones related to the control of metabolic homeostasis. Finally, we recognize possible advantages of metabolic management of immunity to develop new strategies for treatment, diagnosis, and prevention of tuberculosis.
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9.
Vitamin C: A Natural Inhibitor of Cell Wall Functions and Stress Response in Mycobacteria.
Syal, K, Chatterji, D
Advances in experimental medicine and biology. 2018;:321-332
Abstract
Tuberculosis, caused by Mycobacterium tuberculosis, has re-emerged as a threat to human race. Conventional antibiotic treatments are failing due to different stress response strategies adopted by bacterial pathogens. Since time immemorial, Vitamin C is known to protect against pathogens by boosting immunity in humans. Recently, Vitamin C has been shown to directly kill M. tuberculosis including multiple drug-resistant strains by generation of oxidative radicals through Fenton's reaction. Concurrently, it inhibits (p)ppGpp-mediated stringent response thus effectively shutting down long-term survival and persistence in mycobacteria. Here, we have discussed historical perspective and recent evidences on Vitamin C-mediated inhibition of several key pathways of M. tuberculosis such as (p)ppGpp synthesis and mycobacterial cell wall function. Several cell wall components including mycolic acids are critical for mycobacterial virulence. We observed downregulation of various mycolic acids in M. smegmatis upon treatment with Vitamin C, and data have been presented here. Vitamin C has been shown to inhibit the biofilm growth as well as disrupt the formed biofilm in mycobacteria. Additionally, Vitamin C role in cell-mediated and humoral immunity has been elucidated. Vitamin C is toxic at high concentration; therefore we have proposed the idea of derivatizing Vitamin C in order to lower the minimal inhibition concentration (MIC) necessary to target M. tuberculosis.
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10.
Macrophage-microbe interaction: lessons learned from the pathogen Mycobacterium tuberculosis.
BoseDasgupta, S, Pieters, J
Seminars in immunopathology. 2018;(6):577-591
Abstract
Macrophages, being the cornerstone of the immune system, have adapted the ancient nutrient acquisition mechanism of phagocytosis to engulf various infectious organisms thereby helping to orchestrate an appropriate host response. Phagocytosis refers to the process of internalization and degradation of particulate material, damaged and senescent cells and microorganisms by specialized cells, after which the vesicle containing the ingested particle, the phagosome, matures into acidic phagolysosomes upon fusion with hydrolytic enzyme-containing lysosomes. The destructive power of the macrophage is further exacerbated through the induction of macrophage activation upon a variety of inflammatory stimuli. Despite being the end-point for many phagocytosed microbes, the macrophage can also serve as an intracellular survival niche for a number of intracellular microorganisms. One microbe that is particularly successful at surviving within macrophages is the pathogen Mycobacterium tuberculosis, which can efficiently manipulate the macrophage at several levels, including modulation of the phagocytic pathway as well as interfering with a number of immune activation pathways that normally would lead to eradication of the internalized bacilli. M. tuberculosis excels at circumventing destruction within macrophages, thus establishing itself successfully for prolonged times within the macrophage. In this contribution, we describe a number of general features of macrophages in the context of their function to clear an infection, and highlight the strategies employed by M. tuberculosis to counter macrophage attack. Interestingly, research on the evasion tactics employed by M. tuberculosis within macrophages not only helps to design strategies to curb tuberculosis, but also allows a better understanding of host cell biology.