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https://www.readbyqxmd.com/read/28448028/system-for-efficacy-and-cytotoxicity-screening-of-inhibitors-targeting-intracellular-mycobacterium-tuberculosis
#1
Xingji Zheng, Yossef Av-Gay
Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a leading cause of morbidity and mortality worldwide. With the increased spread of multi drug-resistant TB (MDR-TB), there is a real urgency to develop new therapeutic strategies against M. tuberculosis infections. Traditionally, compounds are evaluated based on their antibacterial activity under in vitro growth conditions in broth; however, results are often misleading for intracellular pathogens like M. tuberculosis since in-broth phenotypic screening conditions are significantly different from the actual disease conditions within the human body...
April 5, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28446902/modulation-of-macrophage-responses-by-cmx-a-fusion-protein-composed-of-ag85c-mpt51-and-hspx-from-mycobacterium-tuberculosis
#2
Adeliane C da Costa, Danilo P de Resende, Bruno de P O Santos, Karina F Zoccal, Lúcia H Faccioli, André Kipnis, Ana P Junqueira-Kipnis
Mycobacterium bovis Bacillus Calmette-Guérin (BCG) is a vaccine used to prevent tuberculosis (TB). Due to the poor protection conferred by BCG in adults, new, more effective formulations have been developed. A recombinant BCG vaccine expressing the CMX fusion protein Ag85c_MPT51_HspX (rBCG-CMX) induced Th1 and Th17 responses and provided better protection than BCG. It has been shown that Mycobacterium smegmatis expressing CMX also induces better protection than BCG and is a strong macrophage activator. The aim of the present study was to evaluate macrophage activation by the recombinant CMX fusion protein and by rBCG-CMX and to evaluate their ability to generate vaccine-specific immune responses...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28442574/the-r753q-polymorphism-in-toll-like-receptor-2-tlr2-attenuates-innate-immune-responses-to-mycobacteria-and-impairs-myd88-adapter-recruitment-to-tlr2
#3
Goutham Pattabiraman, Rahul Panchal, Andrei E Medvedev
Toll-like receptor (TLR) 2 plays a critical role in host defenses against mycobacterial infections. The Arg753Gln (R753Q) TLR2 polymorphism has been associated with increased incidence of tuberculosis and infections with non-tuberculous mycobacteria in human populations, but the mechanisms by which this polymorphism affects TLR2 signaling are unclear. In this study, we determined the impact of the R753Q TLR2 polymorphism on macrophage sensing of Mycobacterium smegmatis. Upon infection with M. smegmatis, macrophages from knock-in (KI) mice harboring R753Q TLR2 expressed lower levels of TNF-α, IL-1β, IL-6 and IL-10 compared to cells from wild-type (WT) mice but both R753Q TLR2 and WT mice exhibited comparable bacterial burdens...
April 25, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28440335/mycobacterium-tuberculosis-pe_pgrs41-enhances-the-intracellular-survival-of-m-smegmatis-within-macrophages-via-blocking-innate-immunity-and-inhibition-of-host-defense
#4
Wanyan Deng, Quanxin Long, Jie Zeng, Ping Li, Wenmin Yang, Xinchun Chen, Jianping Xie
The success of Mycobacterium tuberculosis (M. tuberculosis) as a pathogen is largely contributes to its ability to manipulate the host immune responses. The genome of M. tuberculosis encodes multiple immune-modulatory proteins, including several members of the multi-genic PE_PPE family. Despite of intense research, the roles of PE_PGRS proteins in mycobacterial pathogenesis remain elusive. The function of M. tuberculosis PE_PGRS41, characterized by an extended and unique C-terminal domain, was studied. Expression of PE_PGRS41 in Mycobacterium smegmatis, a non-pathogenic species intrinsically deficient of PE_PGRS, severely impaired the resistance of the recombinant to multiple stresses via altering the cell wall integrity...
April 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28436453/functional-thermodynamics-structural-and-biological-studies-of-in-silico-identified-inhibitors-of-mycobacterium-tuberculosis-enoyl-acp-coa-reductase-enzyme
#5
Leonardo K B Martinelli, Mariane Rotta, Anne D Villela, Valnês S Rodrigues-Junior, Bruno L Abbadi, Rogério V Trindade, Guilherme O Petersen, Giuliano M Danesi, Laura R Nery, Ivani Pauli, Maria M Campos, Carla D Bonan, Osmar Norberto de Souza, Luiz A Basso, Diogenes S Santos
Novel chemotherapeutics agents are needed to kill Mycobacterium tuberculosis, the main causative agent of tuberculosis (TB). The M. tuberculosis 2-trans-enoyl-ACP(CoA) reductase enzyme (MtInhA) is the druggable bona fide target of isoniazid. New chemotypes were previously identified by two in silico approaches as potential ligands to MtInhA. The inhibition mode was determined by steady-state kinetics for seven compounds that inhibited MtInhA activity. Dissociation constant values at different temperatures were determined by protein fluorescence spectroscopy...
April 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28436433/pathways-and-genes-associated-with-immune-dysfunction-in-sheep-paratuberculosis
#6
Anton Gossner, Craig Watkins, Francesca Chianini, John Hopkins
Multibacillary and paucibacillary paratuberculosis are both caused by Mycobacterium avium subspecies paratuberculosis. Multibacillary lesions are composed largely of infected epithelioid macrophages and paucibacillary lesions contain T cells but few bacteria. Multibacillary disease is similar to human lepromatous leprosy, with variable/high levels of antibody and a dysfunctional immune response. Animals with paucibacillary disease have high cell-mediated immunity and variable levels of antibody. This study aims to characterize the immunological dysfunction using TruSeq analysis of the ileocaecal lymph node that drains disease lesions...
April 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28435012/il-10-down-regulates-the-expression-of-survival-associated-gene-hspx-of-mycobacterium-tuberculosis-in-murine-macrophage
#7
Babban Jee, Pawan Sharma, Kiran Katoch, Beenu Joshi, Sudhir Kumar Awasthi
Mycobacterium tuberculosis (MTB) adopts a special survival strategy to overcome the killing mechanism(s) of host immune system. Amongst the many known factors, small heat shock protein 16.3 (sHSP16.3) of MTB encoded by gene hspX has been reported to be critical for the survival of MTB. In the present study, the effect of recombinant murine interferon-gamma (rmIFN-γ) and recombinant murine interleukin-10 (rmIL-10) on the expression of gene hspX of MTB in murine macrophage RAW264.7 has been investigated. By real-time RT-PCR, it was observed that three increasing concentrations (5, 25 and 50ng/ml) of rmIFN-γ significantly up-regulated the expression of hspX whereas similar concentrations of rmIL-10 (5, 25 and 50ng/ml) significantly down-regulated the hspX expression...
April 20, 2017: Brazilian Journal of Infectious Diseases
https://www.readbyqxmd.com/read/28428950/endogenous-and-exogenous-kdpf-peptide-increases-susceptibility-of-mycobacterium-bovis-bcg-to-nitrosative-stress-and-reduces-intramacrophage-replication
#8
Mariana Rosas Olvera, Eric Vivès, Virginie Molle, Anne-Béatrice Blanc-Potard, Laila Gannoun-Zaki
Emerging antibiotic resistance in pathogenic bacteria like Mycobacterium sp., poses a threat to human health and therefore calls for the development of novel antibacterial strategies. We have recently discovered that bacterial membrane peptides, such as KdpF, possess anti-virulence properties when overproduced in pathogenic bacterial species. Overproduction of the KdpF peptide in Mycobacterium bovis BCG decreased bacterial replication within macrophages, without presenting antibacterial activity. We propose that KdpF functions as a regulatory molecule and interferes with bacterial virulence, potentially through interaction with the PDIM transporter MmpL7...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28424703/immune-responses-to-bacillus-calmette-gu%C3%A3-rin-vaccination-why-do-they-fail-to-protect-against-mycobacterium-tuberculosis
#9
REVIEW
Juan I Moliva, Joanne Turner, Jordi B Torrelles
Mycobacterium tuberculosis (M.tb), the causative agent of tuberculosis (TB), is the current leading cause of death due to a single infectious organism. Although curable, the broad emergence of multi-, extensive-, extreme-, and total-drug resistant strains of M.tb has hindered eradication efforts of this pathogen. Furthermore, computational models predict a quarter of the world's population is infected with M.tb in a latent state, effectively serving as the largest reservoir for any human pathogen with the ability to cause significant morbidity and mortality...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28422754/mpeg1-perforin-2-mutations-in-human-pulmonary-nontuberculous-mycobacterial-infections
#10
Ryan M McCormack, Eva P Szymanski, Amy P Hsu, Elena Perez, Kenneth N Olivier, Eva Fisher, E Brook Goodhew, Eckhard R Podack, Steven M Holland
Perforin-2 is a highly conserved pore-forming protein encoded by macrophage expressed gene 1 (MPEG1). A number of studies have shown that Perforin-2-deficient mice are unable to survive following a bacterial challenge that is nonlethal in WT mice. There is also recent evidence that Mpeg1+/- heterozygous mice display an intermediate killing ability compared with Mpeg1 WT and Mpeg1-/- mice. Despite these in vivo findings, to date, no perforin-2 deficiencies have been associated with human disease. Here, we report four patients with persistent nontuberculous mycobacterial infection who had heterozygous MPEG1 mutations...
April 20, 2017: JCI Insight
https://www.readbyqxmd.com/read/28422568/cgas-sting-tbk1-irf3-7-induced-interferon-%C3%AE-contributes-to-the-clearing-of-non-tuberculous-mycobacterial-infection-in-mice
#11
Nanthapon Ruangkiattikul, Andreas Nerlich, Ketema Abdissa, Stefan Lienenklaus, Abdulhadi Suwandi, Nina Janze, Kristin Laarmann, Julia Spanier, Ulrich Kalinke, Siegfried Weiss, Ralph Goethe
Type I interferons (IFN-I), such as IFN-α and IFN-β are important messengers in the host response against bacterial infections. Knowledge about the role of IFN-I in infections by nontuberculous mycobacteria (NTM) is limited. Here we show that macrophages infected with pathogens of the Mycobacterium avium complex produced significantly lower amounts of IFN-β than macrophages infected with the opportunistic pathogen M. smegmatis. To dissect the molecular mechanisms of this phenomenon, we focussed on the obligate pathogen Mycobacterium avium ssp...
April 19, 2017: Virulence
https://www.readbyqxmd.com/read/28421165/the-diverse-cellular-and-animal-models-to-decipher-the-physiopathological-traits-of-mycobacterium-abscessus-infection
#12
REVIEW
Audrey Bernut, Jean-Louis Herrmann, Diane Ordway, Laurent Kremer
Mycobacterium abscessus represents an important respiratory pathogen among the rapidly-growing non-tuberculous mycobacteria. Infections caused by M. abscessus are increasingly found in cystic fibrosis (CF) patients and are often refractory to antibiotic therapy. The underlying immunopathological mechanisms of pathogenesis remain largely unknown. A major reason for the poor advances in M. abscessus research has been a lack of adequate models to study the acute and chronic stages of the disease leading to delayed progress of evaluation of therapeutic efficacy of potentially active antibiotics...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28419514/activition-of-tlr7-inhibition-of-mycobacterium-tuberculosis-survival-by-autophagy-in-raw-264-7-macrophages
#13
Meng Bao, Zhengjun Yi, Yurong Fu
The aim of the study was to evaluate the effect of regulation of TLR7 on Mycobacterium tuberculosis (Mtb) survival in macrophages. TLR7 expression in macrophages infected by Mtb was detected by RT-PCR and western blotting. Regulation of TLR7 was achieved by single strand RNA (ssRNA) or siRNA. The effects of TLR7 on Mtb survival and cell viability were detected by acid fast staining and cell counting kit-8, respectively. Cell ultrastructure was observed via transmission electron microscopy (TEM), and autophagy related protein LC3 was analyzed by western blotting...
April 17, 2017: Journal of Cellular Biochemistry
https://www.readbyqxmd.com/read/28416555/mycobacterium-tuberculosis-proteome-response-to-anti-tuberculosis-compounds-reveals-metabolic-escape-pathways-that-prolong-bacterial-survival
#14
Lia Danelishvili, Natalia Shulzhenko, Jessica J J Chinison, Lmar Babrak, Jialu Hu, Andriy Morgun, Gregory Burrows, Luiz E Bermudez
Tuberculosis (TB) continues to be one of the most common bacterial infectious diseases and the leading cause of death in many parts of the world. A major limitation of TB therapy is slow killing of infecting organism, increasing the risk for the development of tolerance phenotype and drug-resistance. Studies indicate that M. tuberculosis (Mtb) takes several days to be killed upon treatment with lethal concentrations of antibiotics both in vitro and in vivo To investigate how metabolic remodeling can enable transient bacterial survival during exposure with bactericidal concentrations of compounds, Mtb H37Rv strain was exposed to twice of the minimal inhibitory concentration of isoniazid, rifampicin, moxifloxacin, mefloquine or bedaquiline for 24h, 48h, 4 days, and 6 days, and the bacterial proteomic response was analyzed using the quantitative shotgun mass spectrometry...
April 17, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28412202/the-immunosuppressive-effects-of-a-novel-recombinant-lipq-rv2485c-protein-of-mycobacterium-tuberculosis-on-human-macrophage-cell-lines
#15
Anjani Kumar, Manisha, Gurkamaljit Kaur Sangha, Anju Shrivastava, Jagdeep Kaur
Mycobacterium tuberculosis (MTB), an intracellular pathogen, still represents a major global health challenge. A number of mycobacterial macromolecules have been shown to target biological processes within host macrophages; however, the exact mechanism for the majority of these host pathogen interactions is still poorly understood. Moreover, the lipid metabolic pathway is one of the most important physiologic pathways that plays a vital role in the survival and infection of Mycobacterium tuberculosis. In present study, we investigated the effect of rLipQ from Mycobacterium tuberculosis H37Rv on macrophage functions in vitro...
April 12, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28401933/bcl-xl-mediates-ripk3-dependent-necrosis-in-m-tuberculosis-infected-macrophages
#16
X Zhao, N Khan, H Gan, F Tzelepis, T Nishimura, S-Y Park, M Divangahi, H G Remold
Virulent Mycobacterium tuberculosis (Mtb) triggers necrosis in host Mϕ, which is essential for successful pathogenesis in tuberculosis. Here we demonstrate that necrosis of Mtb-infected Mϕ is dependent on the action of the cytosolic Receptor Interacting Protein Kinase 3 (RIPK3) and the mitochondrial Bcl-2 family member protein B-cell lymphoma-extra large (Bcl-xL). RIPK3-deficient Mϕ are able to better control bacterial growth in vitro and in vivo. Mechanistically, cytosolic RIPK3 translocates to the mitochondria where it promotes necrosis and blocks caspase 8-activation and apoptosis via Bcl-xL...
April 12, 2017: Mucosal Immunology
https://www.readbyqxmd.com/read/28400772/sphingolipids-are-dual-specific-drug-targets-for-the-management-of-pulmonary-infections-perspective
#17
REVIEW
Lalita Sharma, Hridayesh Prakash
Sphingolipids are the major constituent of the mucus secreted by the cells of epithelial linings of lungs where they maintain the barrier functions and prevent microbial invasion. Sphingolipids are interconvertible, and their primary and secondary metabolites have both structural and functional roles. Out of several sphingolipid metabolites, sphingosine-1 phosphate (S1P) and ceramide are central molecules and decisive for sphingolipid signaling. These are produced by enzymatic activity of sphingosine kinase-1 (SK-1) upon the challenge with either biological or physiological stresses...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28398760/nicotine-impairs-macrophage-control-of-mycobacterium-tuberculosis
#18
Xiyuan Bai, Jerry A Stitzel, An Bai, Cristian A Zambrano, Matthew Phillips, Philippa Marrack, Edward D Chan
Pure nicotine impairs macrophage killing of Mycobacterium tuberculosis (MTB) but it is not known whether the nicotine component in cigarette smoke (CS) plays a role. Moreover, the mechanisms by which nicotine impairs macrophage immunity against MTB have not been explored. To neutralize the effects of nicotine in CS extract, we utilized a competitive inhibitor to the nicotinic acetylcholine receptor (nAChR) - mecamylamine - as well as macrophages derived from mice with genetic disruption of specific subunits of nAChR...
April 11, 2017: American Journal of Respiratory Cell and Molecular Biology
https://www.readbyqxmd.com/read/28396657/the-activity-of-a-hexameric-m17-metallo-aminopeptidase-is-associated-with-survival-of-mycobacterium-tuberculosis
#19
Andre F Correa, Izabela M D Bastos, David Neves, Andre Kipnis, Ana P Junqueira-Kipnis, Jaime M de Santana
Mycobacterium tuberculosis is one of the most prevalent human pathogens causing millions of deaths in the last years. Moreover, tuberculosis (TB) treatment has become increasingly challenging owing to the emergence of multidrug resistant M. tuberculosis strains. Thus, there is an immediate need for the development of new anti-TB drugs. Proteases appear to be a promising approach and may lead to shortened and effective treatments for drug-resistant TB. Although the M. tuberculosis genome predicts more than 100 genes encoding proteases, only a few of them have been studied...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28396391/enhanced-respiration-prevents-drug-tolerance-and-drug-resistance-in-mycobacterium-tuberculosis
#20
Catherine Vilchèze, Travis Hartman, Brian Weinrick, Paras Jain, Torin R Weisbrod, Lawrence W Leung, Joel S Freundlich, William R Jacobs
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...
April 10, 2017: Proceedings of the National Academy of Sciences of the United States of America
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