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Autophagy induction by Mycobacterium indicus pranii promotes Mycobacterium tuberculosis clearance from RAW 264.7 macrophages.

ABSTRACT: Mycobacterium indicus pranii (MIP) is a potent vaccine candidate against tuberculosis (TB) as it has demonstrated significant protection in animal models of tuberculosis as well as in clinical trials. Higher protective efficacy of MIP against TB as compared to BCG provoked the efforts to gain insight into the molecular mechanisms underlying MIP mediated protection against Mycobacterium tuberculosis (M.tb). Autophagy, initially described as a cell survival mechanism during starvation, also plays a key role in host resistance to M.tb. Virulent mycobacteria like M.tb, suppresses host autophagy response to increase its survival in macrophages. Since mycobacterial species have been shown to vary widely in their autophagy-inducing properties, in the present study, we examined the autophagy inducing efficacy of MIP and its role in MIP-mediated protection against M.tb. MIP was found to be potent inducer of autophagy in macrophages. Induced autophagy was responsible for reversal of the phagosome maturation block and phagolysosome fusion inhibition in M.tb infected macrophages, which ultimately lead to significantly enhanced clearance of M.tb from the macrophages. This is an important study which further delineated the underlying mechanisms for significant immunotherapeutic activity observed in TB patients / animal models of tuberculosis, given MIP therapy along with chemotherapy.

SUBMITTER: Singh B

PROVIDER: S-EPMC5728553 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Autophagy induction by Mycobacterium indicus pranii promotes Mycobacterium tuberculosis clearance from RAW 264.7 macrophages.

Singh Bindu B Saqib Mohd M Gupta Ananya A Kumar Pawan P Bhaskar Sangeeta S

PloS one 20171213 12

Mycobacterium indicus pranii (MIP) is a potent vaccine candidate against tuberculosis (TB) as it has demonstrated significant protection in animal models of tuberculosis as well as in clinical trials. Higher protective efficacy of MIP against TB as compared to BCG provoked the efforts to gain insight into the molecular mechanisms underlying MIP mediated protection against Mycobacterium tuberculosis (M.tb). Autophagy, initially described as a cell survival mechanism during starvation, also plays ...[more]

PMID: 29236768

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Project description:BackgroundTuberculous pericarditis is associated with high morbidity and mortality even if antituberculosis therapy is administered. We evaluated the effects of adjunctive glucocorticoid therapy and Mycobacterium indicus pranii immunotherapy in patients with tuberculous pericarditis.MethodsUsing a 2-by-2 factorial design, we randomly assigned 1400 adults with definite or probable tuberculous pericarditis to either prednisolone or placebo for 6 weeks and to either M. indicus pranii or placebo, administered in five injections over the course of 3 months. Two thirds of the participants had concomitant human immunodeficiency virus (HIV) infection. The primary efficacy outcome was a composite of death, cardiac tamponade requiring pericardiocentesis, or constrictive pericarditis.ResultsThere was no significant difference in the primary outcome between patients who received prednisolone and those who received placebo (23.8% and 24.5%, respectively; hazard ratio, 0.95; 95% confidence interval [CI], 0.77 to 1.18; P=0.66) or between those who received M. indicus pranii immunotherapy and those who received placebo (25.0% and 24.3%, respectively; hazard ratio, 1.03; 95% CI, 0.82 to 1.29; P=0.81). Prednisolone therapy, as compared with placebo, was associated with significant reductions in the incidence of constrictive pericarditis (4.4% vs. 7.8%; hazard ratio, 0.56; 95% CI, 0.36 to 0.87; P=0.009) and hospitalization (20.7% vs. 25.2%; hazard ratio, 0.79; 95% CI, 0.63 to 0.99; P=0.04). Both prednisolone and M. indicus pranii, each as compared with placebo, were associated with a significant increase in the incidence of cancer (1.8% vs. 0.6%; hazard ratio, 3.27; 95% CI, 1.07 to 10.03; P=0.03, and 1.8% vs. 0.5%; hazard ratio, 3.69; 95% CI, 1.03 to 13.24; P=0.03, respectively), owing mainly to an increase in HIV-associated cancer.ConclusionsIn patients with tuberculous pericarditis, neither prednisolone nor M. indicus pranii had a significant effect on the composite of death, cardiac tamponade requiring pericardiocentesis, or constrictive pericarditis. (Funded by the Canadian Institutes of Health Research and others; IMPI ClinicalTrials.gov number, NCT00810849.).

Project description:BACKGROUND:Mycobacterium indicus pranii (MIP), popularly known as Mw, is a cultivable, non-pathogenic organism, which, based on its growth and metabolic properties, is classified in Runyon Group IV along with M. fortuitum, M. smegmatis and M. vaccae. The novelty of this bacterium was accredited to its immunological ability to undergo antigen driven blast transformation of leukocytes and delayed hypersensitivity skin test in leprosy patients, a disease endemic in the Indian sub-continent. Consequently, MIP has been extensively evaluated for its biochemical and immunological properties leading to its usage as an immunomodulator in leprosy and tuberculosis patients. However, owing to advances in sequencing and culture techniques, the citing of new strains with almost 100% similarity in the sequences of marker genes like 16S rRNA, has compromised the identity of MIP as a novel species. Hence, to define its precise taxonomic position, we have carried out polyphasic taxonomic studies on MIP that integrate its phenotypic, chemotaxonomic and molecular phylogenetic attributes. METHODOLOGY/PRINCIPAL FINDINGS:The comparative analysis of 16S rRNA sequence of MIP by using BLAST algorithm at NCBI (nr database) revealed a similarity of > or =99% with M. intracellulare, M. arosiense, M. chimaera, M. seoulense, M. avium subsp. hominissuis, M. avium subsp. paratuberculosis and M. bohemicum. Further analysis with other widely used markers like rpoB and hsp65 could resolve the phylogenetic relationship between MIP and other closely related mycobacteria apart from M. intracellulare and M. chimaera, which shares > or =99% similarity with corresponding MIP orthologues. Molecular phylogenetic analysis, based on the concatenation of candidate orthologues of 16S rRNA, hsp65 and rpoB, also substantiated its distinctiveness from all the related organisms used in the analysis excluding M. intracellulare and M. chimaera with which it exhibited a close proximity. This necessitated further analysis of MIP with more sensitive and segregating parameters to ascertain its precise taxonomic position as a new species. The analysis of MIP and its comparison with other mycobacterial reference strains based on cellular and biochemical features, growth characteristics and chemotaxonomic studies like FAME profiling confirmed that MIP is uniquely endowed with diverse metabolic attributes that effectively distinguishes it from all the closely related mycobacteria including M. intracellulare and M. chimaera. CONCLUSION:The results presented in this study coupled with the non-pathogenic nature and different biochemical and immunomodulatory properties of MIP affirm it as a distinct species belonging to M. avium complex (MAC). It is further proposed to use an earlier suggested name Mycobacterium indicus pranii for this newly established mycobacterial species. This study also exemplifies the growing need for a uniform, consensus based broader polyphasic frame work for the purpose of taxonomy and speciation, particularly in the genus Mycobacterium.

Project description:Mycobacterium ulcerans produces a macrolide exotoxin, mycolactone which suppresses immune cells activity, is toxic to most cells and the key virulence factor in the pathogenesis of Buruli ulcer disease. Mycolactone is reported to mediate the production of reactive oxygen species in keratinocytes; cells that play critical role in wound healing. Increased levels of reactive oxygen species have been shown to disrupt the well-ordered process of wound repair; hence, the function of wound-healing cells such as macrophages, keratinocytes, and fibroblast could be impaired in the presence of the reactive oxygen species mediator, mycolactone. To ensure regeneration of tissues in chronic ulcers, with proper and timely healing of the wounds, natural antioxidants that can combat the effects of induced reactive oxygen species in wound-healing cells ought to be investigated. Reactive oxygen species activity was determined in mycolactone-treated RAW 264.7 macrophages and the scavenging ability of the antioxidants (ascorbic acid, gallic acid, and green tea kombucha) against mycolactone-induced reactive oxygen species (superoxide anions) was assessed using fluorescein probe (DCF-DA) and nitroblue tetrazolium dye. Cytotoxicity of the antioxidants, mycolactone, and the protective effect of the antioxidants on the cells upon treatment with mycolactone were determined using the Alamar blue assay. The expression levels of endogenous antioxidant enzyme genes (superoxide dismutase, catalase, and glutathione peroxidase) in response to mycolactone-mediated reactive oxygen species were determined using RT-qPCR. Mycolactone induced the production of reactive oxygen species in RAW 264.7 macrophages, and the resulting superoxide anions were scavenged by some of the antioxidants. The selected endogenous antioxidant enzyme genes in the macrophages were upregulated in the presence of the antioxidants and mycolactone. The exogenously supplied ascorbic acid and green tea kombucha offered moderate protection to the macrophages against the toxicity of mycolactone. We conclude that the results provide insights into alternate and adjunct therapeutic approaches in Buruli ulcer treatment, which could significantly attenuate the toxicity of the pathogenic factor; mycolactone.

Dataset Information

Autophagy induction by Mycobacterium indicus pranii promotes Mycobacterium tuberculosis clearance from RAW 264.7 macrophages.

Publications

Autophagy induction by Mycobacterium indicus pranii promotes Mycobacterium tuberculosis clearance from RAW 264.7 macrophages.

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