Rewiring cellular metabolism via the AKT/mTOR pathway contributes to host defence against Mycobacterium tuberculosis in human and murine cells (original) (raw)
Related papers
Rewiring of Metabolic Network in Mycobacterium tuberculosis During Adaptation to Different Stresses
Frontiers in Microbiology
Metabolic adaptation of Mycobacterium tuberculosis (M. tuberculosis) to microbicidal intracellular environment of host macrophages is fundamental to its pathogenicity. However, an in-depth understanding of metabolic adjustments through key reaction pathways and networks is limited. To understand how such changes occur, we measured the cellular metabolome of M. tuberculosis subjected to four microbicidal stresses using liquid chromatography-mass spectrometric multiple reactions monitoring (LC-MRM/MS). Overall, 87 metabolites were identified. The metabolites best describing the separation between stresses were identified through multivariate analysis. The coupling of the metabolite measurements with existing genome-scale metabolic model, and using constraint-based simulation led to several new concepts and unreported observations in M. tuberculosis; such as (i) the high levels of released ammonia as an adaptive response to acidic stress was due to increased flux through L-asparaginase rather than urease activity; (ii) nutrient starvation-induced anaplerotic pathway for generation of TCA intermediates from phosphoenolpyruvate using phosphoenolpyruvate kinase; (iii) quenching of protons through GABA shunt pathway or sugar alcohols as possible mechanisms of early adaptation to acidic and oxidative stresses; and (iv) usage of alternate cofactors by the same enzyme as a possible mechanism of rewiring metabolic pathways to overcome stresses. Besides providing new leads and important nodes that can be used for designing intervention strategies, the study advocates the strength of applying flux balance analyses coupled with metabolomics to get a global picture of complex metabolic adjustments.
Metabolism of Mycobacterium tuberculosis
Systems Biology of Tuberculosis, 2012
Despite decades of research many aspects of the biology of Mycobacterium tuberculosis remain unclear and this is re fl ected in the antiquated tools available to treat and prevent tuberculosis. Consequently, this disease remains a serious public health problem responsible for 2-3 million deaths each year. Important discoveries linking M. tuberculosis metabolism and pathogenesis have renewed interest in the metabolic underpinning of the interaction between the pathogen and its host. Whereas, previous experimental studies tended to focus on the role of single genes, antigens or enzymes, the central paradigm of systems biology is that the role of any gene cannot be determined in isolation from its context. Therefore, systems approaches examine the role of genes and proteins embedded within a network of interactions. We here examine the application of this approach to studying metabolism of M. tuberculosis. Recent advances in high-throughput experimental technologies, such as functional genomics and metabolomics, provide datasets that can be analysed with computational tools such as fl ux balance analysis. These new approaches allow metabolism to be studied on a genome scale and have already been applied to gain insights into the metabolic pathways utilised by M. tuberculosis in vitro and identify potential drug targets. The information from these studies will fundamentally change our approach to tuberculosis research and lead to new targets for therapeutic drugs and vaccines.
mTORC2/Akt activation in adipocytes is required for adipose tissue inflammation in tuberculosis
EBioMedicine, 2019
Background: Mycobacterium tuberculosis has co-evolved with the human host, adapting to exploit the immune system for persistence and transmission. While immunity to tuberculosis (TB) has been intensively studied in the lung and lymphoid system, little is known about the participation of adipose tissues and non-immune cells in the host-pathogen interaction during this systemic disease. Methods: C57BL/6J mice were aerosol infected with M. tuberculosis Erdman and presence of the bacteria and the fitness of the white and brown adipose tissues, liver and skeletal muscle were studied compared to uninfected mice. Findings: M. tuberculosis infection in mice stimulated immune cell infiltration in visceral, and brown adipose tissue. Despite the absence of detectable bacterial dissemination to fat tissues, adipocytes produced localized pro-inflammatory signals that disrupted adipocyte lipid metabolism, resulting in adipocyte hypertrophy. Paradoxically, this resulted in increased insulin sensitivity and systemic glucose tolerance. Adipose tissue inflammation and enhanced glucose tolerance also developed in obese mice after aerosol M. tuberculosis infection. We found that infection induced adipose tissue Akt signaling, while inhibition of the Akt activator mTORC2 in adipocytes reversed TB-associated adipose tissue inflammation and cell hypertrophy. Interpretation: Our study reveals a systemic response to aerosol M. tuberculosis infection that regulates adipose tissue lipid homeostasis through mTORC2/Akt signaling in adipocytes. Adipose tissue inflammation in TB is not simply a passive infiltration with leukocytes but requires the mechanistic participation of adipocyte signals.
Microorganisms
The physiological state of the human macrophage may impact the metabolism and the persistence of Mycobacterium tuberculosis. This pathogen senses and counters the levels of O2, CO, reactive oxygen species (ROS), and pH in macrophages. M. tuberculosis responds to oxidative stress through WhiB3. The goal was to determine the effect of NADPH oxidase (NOX) modulation and oxidative agents on the expression of whiB3 and genes involved in lipid metabolism (lip-Y, Icl-1, and tgs-1) in intracellular mycobacteria. Human macrophages were first treated with NOX modulators such as DPI (ROS inhibitor) and PMA (ROS activator), or with oxidative agents (H2O2 and generator system O2•−), and then infected with mycobacteria. We determined ROS production, cell viability, and expression of whiB3, as well as genes involved in lipid metabolism. PMA, H2O2, and O2•− increased ROS production in human macrophages, generating oxidative stress in bacteria and augmented the gene expression of whiB3, lip-Y, Icl-1...
International Immunology, 2019
Macrophages are major components of tuberculosis (TB) granulomas and are responsible for host defenses against the intracellular pathogen, Mycobacterium tuberculosis. We herein showed the strong expression of hypoxia-inducible factor-1α (HIF-1α) in TB granulomas and more rapid death of HIF-1α-conditional knockout mice than wild-type (WT) mice after M. tuberculosis infection. Although interferon-γ (IFN-γ) is a critical host-protective cytokine against intracellular pathogens, HIF-1-deficient macrophages permitted M. tuberculosis growth even after activation with IFN-γ. These results prompted us to investigate the role of HIF-1α in host defenses against infection. We found that the expression of lactate dehydrogenase-A (LDH-A) was controlled by HIF-1α in M. tuberculosis-infected macrophages IFN-γ independently. LDH-A is an enzyme that converts pyruvate to lactate and we found that the intracellular level of pyruvate in HIF-1α-deficient bone marrow-derived macrophages (BMDMs) was signi...
LungMycobacterium tuberculosisinfection perturbs metabolic pathways in non-pulmonary tissues
bioRxiv (Cold Spring Harbor Laboratory), 2024
Mycobacterium tuberculosis (Mtb), through aerosol, reaches the lungs to cause pulmonary tuberculosis (TB); however, it may also affect the metabolism of other tissues in age-specific ways. In this study, female C57BL/6 mice (2 and 5 months old; M) were infected with a low aerosol dose (100-200 cfu) of Mtb H37Rv to monitor tissue mycobacterial load and multitissue metabolite profiling using gas chromatography and mass spectrometry (GC-MS). 5M C57BL/6 mice showed separate tissue metabolic phenotype with significantly higher lung aspartic acid, fecal oxalic acid and tryptophan levels with lower liver lysine and aspartic acid and fecal phenylalanine levels (log2FC: 5M/2M> ±1.0, p<0.1) compared to 2M young controls. Upon Mtb infection, the lung mycobacterial load of 2M and 5M mice were similar till 6 weeks post-infection. However, significantly higher lung phosphoric acid, malonic acid and lower mannose levels (log2FC: Mtb infected/healthy> ±1.0, p<0.1) were observed in Mtbinfected 5M C57BL/6 mice. Meanwhile, Mtb-infected 2M mice showed higher liver xylose and lower lysine levels. The thigh muscles of Mtb-infected 2M and 5M mice showed increased malic acid and oxalic acid and decreased glycine, serine, and glycerol levels. Fecal aspartic acid level was higher in Mtb-infected 5M mice, while a decreased abundance of fecal lysine was observed in Mtb-infected 2M mice. Overall, this study demonstrates a deregulated tissuespecific amino acid metabolism in Mtb-infected mice groups of different age groups, which might be targeted for managing TB infection-related adverse effects.
PLoS Pathogens, 2014
The success of Mycobacterium tuberculosis as a pathogen derives from its facile adaptation to the intracellular milieu of human macrophages. To explore this process, we asked whether adaptation also required interference with the metabolic machinery of the host cell. Temporal profiling of the metabolic flux, in cells infected with differently virulent mycobacterial strains, confirmed that this was indeed the case. Subsequent analysis identified the core subset of host reactions that were targeted. It also elucidated that the goal of regulation was to integrate pathways facilitating macrophage survival, with those promoting mycobacterial sustenance. Intriguingly, this synthesis then provided an axis where both host-and pathogen-derived factors converged to define determinants of pathogenicity. Consequently, whereas the requirement for macrophage survival sensitized TB susceptibility to the glycemic status of the individual, mediation by pathogen ensured that the virulence properties of the infecting strain also contributed towards the resulting pathology.
H2S is a potent gasotransmitter in eukaryotes and bacteria. Host-derived H2S has been shown to profoundly alter M. tuberculosis (Mtb) energy metabolism and growth. However, compelling evidence for endogenous production of H2S and its role in Mtb physiology is lacking. We show that multidrug-resistant and drug-susceptible clinical Mtb strains produce H2S, whereas H2S production in non-pathogenic M. smegmatis is barely detectable. We identified Rv3684 (Cds1) as an H2S-producing enzyme in Mtb and show that cds1 disruption reduces, but does not eliminate, H2S production, suggesting the involvement of multiple genes in H2S production. We identified endogenous H2S to be an effector molecule that maintains bioenergetic homeostasis by stimulating respiration primarily via cytochrome bd. Importantly, H2S plays a key role in central metabolism by modulating the balance between oxidative phosphorylation and glycolysis, and functions as a sink to recycle sulfur atoms back to cysteine to maintai...