An approach for studying the mediators of pathogenesis inMycobacterium tuberculosis (original) (raw)
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Transcriptional landscape of Mycobacterium tuberculosis infection in macrophages
Scientific reports, 2018
Mycobacterium tuberculosis (Mtb) infection reveals complex and dynamic host-pathogen interactions, leading to host protection or pathogenesis. Using a unique transcriptome technology (CAGE), we investigated the promoter-based transcriptional landscape of IFNγ (M1) or IL-4/IL-13 (M2) stimulated macrophages during Mtb infection in a time-kinetic manner. Mtb infection widely and drastically altered macrophage-specific gene expression, which is far larger than that of M1 or M2 activations. Gene Ontology enrichment analysis for Mtb-induced differentially expressed genes revealed various terms, related to host-protection and inflammation, enriched in up-regulated genes. On the other hand, terms related to dis-regulation of cellular functions were enriched in down-regulated genes. Differential expression analysis revealed known as well as novel transcription factor genes in Mtb infection, many of them significantly down-regulated. IFNγ or IL-4/IL-13 pre-stimulation induce additional differ...
European Journal of Immunology, 2009
Progression and outcome of tuberculosis is governed by extensive crosstalk between pathogen and host. Analyses of global changes in gene expression during immune response to infection with Mycobacterium tuberculosis (M.tb) can help identify molecular markers of disease state and progression. Global distribution of M.tb strains with different degrees of virulence and drug resistance, especially for the immunocompromised host, make closer analyses of host responses more pressing than ever. Here, we describe global transcriptional responses of inducible nitric oxide synthase-deficient (iNOS -/-) and WT mice infected with two related M.tb strains of markedly different virulence, namely the M.tb laboratory strains H37Rv and H37Ra. Both hosts exhibited highly similar resistance to infection with H37Ra. In contrast, iNOS -/mice rapidly succumbed to H37Rv, whereas WT mice developed chronic course of disease. By differential analyses, virulence-specific changes in global host gene expression were analyzed to identify molecular markers characteristic for chronic versus acute infection. We identified several markers unique for different stages of disease progression and not previously associated with virulencespecific host responses in tuberculosis.
GENE REGULATION IN MYCOBACTERIUM TUBERCULOSIS
As one of the world's best intracellular pathogens, Mycobacterium tuberculosis, the causative specialists of human tuberculosis, is in charge of a few million passings every year. The pathogenicity of M. tuberculosis depends on its capacity to survive and hold on inside host macro phage cells amid contamination. It is of focal significance, accordingly, to recognize qualities and pathways that are included in the survival and determination of M. tuberculosis inside these cells. Phagocytos is of tubercle bacilli by antigen-exhibiting cells in human lung alveoli starts a perplexing disease process by Mycobacterium tuberculosis and a possibly defensive safe reaction by the host. M. tuberculosis has committed an extensive piece of its genome towards capacities that permit it to effectively build up idle or dynamic contamination in the dominant part of tainted people.
The infectious diseases caused by intracellular bacterial pathogens, such as M. tuberculosis, are among the most important problems in public health worldwide. The development of an infectious process depends on intricate interactions between the host defence systems and the specific systems regulating mycobacterial gene expression. Changes in expression in response to host defence are a necessary condition for the M. tuberculosis survival and functioning.
Immunoinformatics study on highly expressed Mycobacterium tuberculosis genes during infection
Tuberculosis, 2014
The most important targets for vaccine development are the proteins that are highly expressed by the microorganisms during infection in-vivo. A number of Mycobacterium tuberculosis (Mtb) proteins are also reported to be expressed in-vivo at different phases of infection. In the present study, we analyzed multiple published databases of gene expression profiles of Mtb in-vivo at different phases of infection in animals and humans and selected 38 proteins that are highly expressed in the active, latent and reactivation phases. We predicted T-and B-cell epitopes from the selected proteins using HLAPred for T-cell epitope prediction and BCEPred combined with ABCPred for B-cell epitope prediction. For each selected proteins, regions containing both T-and B-cell epitopes were identified which might be considered as important candidates for vaccine design against tuberculosis.
Transcriptional profiling of Mycobacterium tuberculosis during infection: lessons learned
2010
Infection with Mycobacterium tuberculosis, the causative agent of tuberculosis, is considered one of the biggest infectious disease killers worldwide. A significant amount of attention has been directed toward revealing genes involved in the virulence and pathogenesis of this airborn pathogen. With the advances in technologies for transcriptional profiling, several groups, including ours, took advantage of DNA microarrays to identify transcriptional units differentially regulated by M. tuberculosis within a host. The main idea behind this approach is that pathogens tend to regulate their gene expression levels depending on the host microenvironment, and preferentially express those needed for survival. Identifying this class of genes will improve our understanding of pathogenesis. In our case, we identified an in vivo expressed genomic island that was preferentially active in murine lungs during early infection, as well as groups of genes active during chronic tuberculosis. Other studies have identified additional gene groups that are active during macrophage infection and even in human lungs. Despite all of these findings, one of the lingering questions remaining was whether in vivo expressed transcripts are relevant to the virulence, pathogenesis, and persistence of the organism. The work of our group and others addressed this question by examining the contribution of in vivo expressed genes using a strategy based on gene deletions followed by animal infections. Overall, the analysis of most of the in vivo expressed genes supported a role of these genes in M. tuberculosis pathogenesis. Further, these data suggest that in vivo transcriptional profiling is a valid approach to identify genes required for bacterial pathogenesis.
Unique Characteristic Features of Mycobacterium Tuberculosis in Relation to Immune System
American Journal of Immunology, 2011
Problem statement: Tuberculosis is a leading global mortality factor which has not been effectively controlled, with 1.7 million deaths per year and 8.9 million new cases. Aerobic microbe Mycobacterium Tuberculosis H37Rv (MTB) is the causative agent of tuberculosis. Approach: It is unique among prokaryotes due to its exceptional features contributing to its survival within the hostile environment of macrophages. Results: It modifies both its intracellular and local tissue environment and proliferates within macrophages resulting in caseous granulomas, the characteristic lesions of TB. MTB derived cAMP intoxicates host cells and thus enable MTB for long term persistence within macrophages by modifying its intracellular environment. Apart from these, there are several unique structural components of MTB which interfere in the pathways of immune system and thus eluding it from destruction. Conclusion: The dormant state of MTB is the major factor which provides this pathogen ability to survive host inflammatory mediators and antibiotic treatment. It is indispensable to delineate the unusual features of MTB that enable its escape from the host immune system, in order to design an efficacious drug against the unpardonable form of tuberculosis.