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Yang H, Kruh-Garcia NA, Dobos KM. Purified protein derivatives of tuberculin--past, present, and future. ACTA ACUST UNITED AC 2012; 66:273-80. [PMID: 22762692 DOI: 10.1111/j.1574-695x.2012.01002.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 06/20/2012] [Accepted: 06/21/2012] [Indexed: 11/30/2022]
Abstract
The tuberculin skin test, which involves monitoring the immune reaction to an injection of purified protein derivative (PPD), has been the most widely used method for detecting infection with Mycobacterium tuberculosis since its development in 1930s. Until recently, the molecular composition of PPD was unknown. This thwarted the discovery of improved skin testing reagents and drastically hindered efforts to define the mechanism of action. Proteomic evaluation of PPD combined with a detailed analysis in the guinea pig model of tuberculosis led to further definition of the molecular composition of PPD. This communication reviews the history and current status of PPD, in addition to describing candidate next-generation PPD reagents, based on the use of an individual protein or protein cocktails.
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Review |
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Diaz G, Wolfe LM, Kruh-Garcia NA, Dobos KM. Changes in the Membrane-Associated Proteins of Exosomes Released from Human Macrophages after Mycobacterium tuberculosis Infection. Sci Rep 2016; 6:37975. [PMID: 27897233 PMCID: PMC5126699 DOI: 10.1038/srep37975] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/31/2016] [Indexed: 12/16/2022] Open
Abstract
Tuberculosis (TB) is the deadliest infectious disease worldwide. One obstacle hindering the elimination of TB is our lack of understanding of host-pathogen interactions. Exosomes, naturally loaded with microbial molecules, are circulating markers of TB. Changes in the host protein composition of exosomes from Mycobacterium tuberculosis (Mtb)-infected cells have not been described, can contribute to our understanding of the disease process, and serve as a direct source of biomarkers or as capture targets to enrich for exosomes containing microbial molecules. Here, the protein composition of exosomes from Mtb-infected and uninfected THP-1-derived macrophages was evaluated by tandem-mass-spectrometry and differences in protein abundances were assessed. Our results show that infection with Mtb leads to significant changes in the protein composition of exosomes. Specifically, 41 proteins were significantly more abundant in exosomes from Mtb-infected cells; 63% of these were predicted to be membrane associated. Thus, we used a novel biotinylation strategy to verify protein localization, and confirmed the localization of some of these proteins in the exosomal membrane. Our findings reveal another important scenario where Mtb could be influencing changes in host cells that unveil new features of the host-pathogen interaction and may also be exploited as a source of biomarkers for TB.
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Estrada AL, Valenti ZJ, Hehn G, Amorese AJ, Williams NS, Balestrieri NP, Deighan C, Allen CP, Spangenburg EE, Kruh-Garcia NA, Lark DS. Extracellular vesicle secretion is tissue-dependent ex vivo and skeletal muscle myofiber extracellular vesicles reach the circulation in vivo. Am J Physiol Cell Physiol 2022; 322:C246-C259. [PMID: 34910603 PMCID: PMC8816621 DOI: 10.1152/ajpcell.00580.2020] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Extracellular vesicles (EVs) are biomarkers and modifiers of human disease. EVs secreted by insulin-responsive tissues like skeletal muscle (SkM) and white adipose tissue (WAT) contribute to metabolic health and disease but the relative abundance of EVs from these tissues has not been directly examined. Human Protein Atlas data and directly measuring EV secretion in mouse SkM and WAT using an ex vivo tissue explant model confirmed that SkM tissue secretes more EVs than WAT. Differences in EV secretion between SkM and WAT were not due to SkM contraction but may be explained by differences in tissue metabolic capacity. We next examined how many EVs secreted from SkM tissue ex vivo and in vivo are myofiber-derived. To do this, a SkM myofiber-specific dual fluorescent reporter mouse was created. Spectral flow cytometry revealed that SkM myofibers are a major source of SkM tissue-derived EVs ex vivo and EV immunocapture indicates that ∼5% of circulating tetraspanin-positive EVs are derived from SkM myofibers in vivo. Our findings demonstrate that 1) SkM secretes more EVs than WAT, 2) many SkM tissue EVs are derived from SkM myofibers, and 3) SkM myofiber-derived EVs reach the circulation in vivo. These findings advance our understanding of EV secretion between metabolically active tissues and provide direct evidence that SkM myofibers secrete EVs that can reach the circulation in vivo.
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Mehaffy C, Dobos KM, Nahid P, Kruh-Garcia NA. Second generation multiple reaction monitoring assays for enhanced detection of ultra-low abundance Mycobacterium tuberculosis peptides in human serum. Clin Proteomics 2017; 14:21. [PMID: 28592925 PMCID: PMC5460347 DOI: 10.1186/s12014-017-9156-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 05/24/2017] [Indexed: 12/11/2022] Open
Abstract
Background Mycobacterium tuberculosis (Mtb) is the causative agent of Tuberculosis (TB), the number one cause of death due to an infectious disease. TB diagnosis is performed by microscopy, culture or PCR amplification of bacterial DNA, all of which require patient sputum or the biopsy of infected tissue. Detection of mycobacterial products in serum, as biomarkers of diagnosis or disease status would provide an improvement over current methods. Due to the low-abundance of mycobacterial products in serum, we have explored exosome enrichment to improve sensitivity. Mtb resides intracellularly where its secreted proteins have been shown to be packaged into host exosomes and released into the bloodstream. Exosomes can be readily purified assuring an enrichment of mycobacterial analytes from the complex mix of host serum proteins. Methods Multiple reaction monitoring assays were optimized for the enhanced detection of 41 Mtb peptides in exosomes purified from the serum of individuals with TB. Exosomes isolated from the serum of healthy individuals was used to create and validate a unique data analysis algorithm and identify filters to reduce the rate of false positives, attributed to host m/z interference. The final optimized method was tested in 40 exosome samples from TB positive patients. Results Our enhanced methods provide limit of detection and quantification averaging in the low femtomolar range for detection of mycobacterial products in serum. At least one mycobacterial peptide was identified in 92.5% of the TB positive patients. Four peptides from the Mtb proteins, Cfp2, Mpt32, Mpt64 and BfrB, show normalized total peak areas significantly higher in individuals with active TB as compared to healthy controls; three of the peptides from these proteins have not previously been associated with serum exosomes from individuals with active TB disease. Some of the detected peptides were significantly associated with specific geographical locations, highlighting potential markers that can be linked to the Mtb strains circulating within each given region. Conclusions An enhanced MRM method to detect ultra-low abundance Mtb peptides in human serum exosomes is demonstrated, highlighting the potential of this methodology for TB diagnostic biomarker development. Electronic supplementary material The online version of this article (doi:10.1186/s12014-017-9156-y) contains supplementary material, which is available to authorized users.
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Diaz G, Bridges C, Lucas M, Cheng Y, Schorey JS, Dobos KM, Kruh-Garcia NA. Protein Digestion, Ultrafiltration, and Size Exclusion Chromatography to Optimize the Isolation of Exosomes from Human Blood Plasma and Serum. J Vis Exp 2018. [PMID: 29708539 DOI: 10.3791/57467] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Exosomes, a type of nanovesicle released from all cell types, can be isolated from any bodily fluid. The contents of exosomes, including proteins and RNAs, are unique to the cells from which they are derived and can be used as indicators of disease. Several common enrichment protocols, including ultracentrifugation, yield exosomes laden with soluble protein contaminants. Specifically, we have found that the most abundant proteins within blood often co-purify with exosomes and can confound downstream proteomic studies, thwarting the identification of low abundance biomarker candidates. Of additional concern is irreproducibility of exosome protein quantification due to inconsistent representation of non-exosomal protein levels. The protocol detailed here was developed to remove non-exosomal proteins that co-purify along with exosomes, adding rigor to the exosome purification process. Five methods were compared using paired blood plasma and serum from five donors. Analysis using nanoparticle tracking analysis and micro bicinchoninic acid protein assay revealed that a combined protocol utilizing ultrafiltration and size exclusion chromatography yielded the optimal vesicle enrichment and soluble protein removal. Western blotting was used to verify that the expected abundant blood proteins, including albumin and apolipoproteins, were depleted.
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Kruh-Garcia NA, Wolfe LM, Dobos KM. Deciphering the role of exosomes in tuberculosis. Tuberculosis (Edinb) 2014; 95:26-30. [PMID: 25496995 DOI: 10.1016/j.tube.2014.10.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 10/27/2014] [Indexed: 12/21/2022]
Abstract
Exosomes were originally described as small vesicles released from reticulocytes during the maturation process. These 40-200 nm microvesicles were hypothesized to be a mechanism for the removal of membrane proteins in lieu of intracellular degradation by Harding et al. (1984) and Johnstone et al. (1987) [1,2]. Exosomes can be distinguished from other extracellular vesicles (ectosomes, apoptotic blebs) based on their size and the protein indicators intercalated in their membrane (also, linking their derivation from the endocytic pathway) by Simpson (2012) [3]. The exact role which exosomes play in cell-to-cell communication and immune modulation is a topic of intense study. However, the focus of most reports has been directed towards discovering aberrations in exosomal protein and RNA content linked to disease onset and progression, and also primarily related to cancer. Nonetheless, exosomes are now documented to be released from a wide variety of cell types by Mathivanan et al. (2012), Simpson et al. (2012) and Kalra et al. (2012) [4-6] and have been isolated from all bodily fluids; thus, exosomes are an excellent source of biomarkers. Here we describe the discoveries related to the role exosomes play in tuberculosis disease, as well as translational work in vaccine development and how circulation of these dynamic vesicles can be harnessed for diagnostic purposes.
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Review |
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Kruh-Garcia NA, Murray M, Prucha JG, Dobos KM. Antigen 85 variation across lineages of Mycobacterium tuberculosis-implications for vaccine and biomarker success. J Proteomics 2013; 97:141-50. [PMID: 23891556 DOI: 10.1016/j.jprot.2013.07.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Revised: 06/26/2013] [Accepted: 07/01/2013] [Indexed: 11/19/2022]
Abstract
UNLABELLED Mycobacterium tuberculosis secretes several hundred proteins; many of which elicit immune responses. As a result, many of these proteins have been explored for their potential as diagnostic and vaccine candidates. Of these, the Antigen 85 complex proteins, represented by Antigen85 A, B, and C, are the most studied from the mycobacterial secretome. However, vaccine constructs exploiting Antigen 85 as the sole antigen repertoire have not experienced the pre-clinical and clinical trials success originally anticipated. Anecdotal and biochemical evidence suggests that differences in protein abundance may explain this phenomenon. Here, biochemical, molecular, and mass spectrometry approaches were used to quantify Antigen 85 among six M. tuberculosis strains from four phylogenetically distinct clades. Our data demonstrates that the greatest variation in Antigen 85 is ascribed to protein quantities, whereas few transcriptional differences were found. In addition, the ratio of Antigen 85 A, to B, to C is conserved within clades and phylogenetic neighbors. In contrast, no such relationship between individual protein quantities was observed, and in the case of Antigen85 B, this variation even extends within biological replicates of individual isolates. The relevance of Antigen 85 protein quantities and vaccine efficacy remains to be defined. BIOLOGICAL SIGNIFICANCE Absolute quantitation via multiple reaction monitoring mass spectrometry was used to determine the exact molar concentrations of Antigen 85A, B, and C; three key immunodominant proteins present in M. tuberculosis. Further, the concentration of these three proteins was compared among various clades of M. tuberculosis, and demonstrated differences in abundance of two of the three proteins. These proteins have been identified as key antigens in multiple vaccine and diagnostic platforms, thus the potential relevance of their abundance in various M. tuberculosis clades to the successful outcome of these interventions is discussed. This article is part of a Special Issue entitled: Trends in Microbial Proteomics.
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Research Support, N.I.H., Extramural |
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Nurul Islam M, Hitchings R, Kumar S, Fontes FL, Lott JS, Kruh-Garcia NA, Crick DC. Mechanism of Fluorinated Anthranilate-Induced Growth Inhibition in Mycobacterium tuberculosis. ACS Infect Dis 2019; 5:55-62. [PMID: 30406991 DOI: 10.1021/acsinfecdis.8b00092] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The biosynthesis of tryptophan in Mycobacterium tuberculosis is initiated by the transformation of chorismate to anthranilate, catalyzed by anthranilate synthase (TrpE/TrpG). Five additional enzymes are required to complete tryptophan biosynthesis. M. tuberculosis strains auxotrophic for tryptophan, an essential amino acid in the human diet, are avirulent. Thus, tryptophan synthesis in M. tuberculosis has been suggested as a potential drug target, and it has been reported that fluorinated anthranilate is lethal to the bacillus. Two mechanisms that could explain the cellular toxicity were tested: (1) the inhibition of tryptophan biosynthesis by a fluorinated intermediate or (2) formation of fluorotryptophan and its subsequent effects. Here, M. tuberculosis mc2 6230 cultures were treated with anthranilates fluorinated at positions 4, 5, and 6. These compounds inhibited bacterial growth on tryptophan-free media with 4-fluoroanthranilate being more potent than 5-fluoroanthranilate or 6-fluoroanthranilate. LC-MS based analysis of extracts from bacteria treated with these compounds did not reveal accumulation of any of the expected fluorinated intermediates in tryptophan synthesis. However, in all cases, significant levels of fluorotryptophan were readily observed, suggesting that the enzymes involved in the conversion of fluoro-anthranilate to fluorotryptophan were not being inhibited. Inclusion of tryptophan in cultures treated with the fluoro-anthranilates obviated the cellular toxicity. Bacterial growth was also inhibited in a dose-dependent manner by exposure to tryptophan substituted with fluorine at positions 5 or 6. Thus, the data suggest that fluorotryptophan rather than fluoro-anthranilate or intermediates in the synthesis of fluorotryptophan causes the inhibition of M. tuberculosis growth.
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Research Support, N.I.H., Extramural |
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Mehaffy C, Ryan JM, Kruh-Garcia NA, Dobos KM. Extracellular Vesicles in Mycobacteria and Tuberculosis. Front Cell Infect Microbiol 2022; 12:912831. [PMID: 35719351 PMCID: PMC9204639 DOI: 10.3389/fcimb.2022.912831] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 04/27/2022] [Indexed: 11/13/2022] Open
Abstract
Tuberculosis (TB) remains a public health issue causing millions of infections every year. Of these, about 15% ultimately result in death. Efforts to control TB include development of new and more effective vaccines, novel and more effective drug treatments, and new diagnostics that test for both latent TB Infection and TB disease. All of these areas of research benefit from a good understanding of the physiology of Mycobacterium tuberculosis (Mtb), the primary causative agent of TB. Mtb secreted protein antigens have been the focus of vaccine and diagnosis research for the past century. Recently, the discovery of extracellular vesicles (EVs) as an important source of secreted antigens in Mtb has gained attention. Similarly, the discovery that host EVs can carry Mtb products during in vitro and in vivo infection has spiked interest because of its potential use in blood-based diagnostics. Despite advances in understanding the content of Mtb and Mtb-infected host extracellular vesicles, our understanding on the biogenesis and role of Mtb and host extracellular vesicles during Mtb infection is still nascent. Here, we explore the current literature on extracellular vesicles regarding Mtb, discuss the host and Mtb extracellular vesicles as distinct entities, and discuss current gaps in the field.
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Mehaffy MC, Kruh-Garcia NA, Dobos KM. Prospective on Mycobacterium tuberculosis proteomics. J Proteome Res 2011; 11:17-25. [PMID: 21988637 DOI: 10.1021/pr2008658] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Mycobacterium tuberculosis, the causative agent of tuberculosis, remains one of the most prevalent human pathogens in the world. Knowledge regarding the bacilli's physiology as well as its mechanisms of virulence, immunogenicity, and pathogenesis has increased greatly in the last three decades. However, the function of about one-quarter of the Mtb coding genome and the precise activity and protein networks of most of the Mtb proteins are still unknown. Protein mass spectrometry and a new interest in research toward the field of functional proteomics have given a new light to the study of this bacillus and will be the focus of this review. We will also discuss new perspectives in the proteomics field, in particular targeted mass spectrometry methods and their potential applications in TB research and discovery.
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Review |
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Hinkle DM, Kruh-Garcia NA, Kruh JN, Broccardo C, Doctor P, Foster CS. Moxifloxacin Concentration and Proteomic Analysis of Aqueous Humor in Human Uveitis Associated with Oral Moxifloxacin Therapy. Open Ophthalmol J 2017; 11:107-116. [PMID: 28694894 PMCID: PMC5481612 DOI: 10.2174/1874364101711010107] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 12/08/2016] [Accepted: 04/02/2017] [Indexed: 11/22/2022] Open
Abstract
PURPOSE The aim was to report the aqueous humor moxifloxacin concentration and proteome profile of an individual with bilateral uveitis-like syndrome with pigment dispersion. METHODS Multiple reactions monitoring mass spectrometry quantified the aqueous concentration of moxifloxacin in the affected individual. Shotgun proteomic analysis performed via liquid chromatography tandem mass spectrometry (LC-MS/MS) defined the protein profile in the affected individual and unaffected control samples. RESULTS Moxifloxacin was present at higher than expected levels in aqueous humor 18 days following oral administration. One-third of the proteins were identified by significantly lower spectral counts in the aqueous of the individual with moxifloxacin associated uveitis compared to the unaffected control. CONCLUSION Moxifloxacin was detected in aqueous humor 18 days following the completion of oral administration. These results suggest that moxifloxacin toxicity may be responsible for the uveitis-like syndrome with pigment dispersion syndrome induced by moxifloxacin therapy.
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Kruh JN, Kruh-Garcia NA, Foster CS. Evaluation of the Effect ofN-Acetylcysteine on Protein Deposition on Contact Lenses in Patients with the Boston Keratoprosthesis Type I. J Ocul Pharmacol Ther 2015; 31:314-22. [DOI: 10.1089/jop.2015.0010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Ryan JM, Dobos KM, Kruh-Garcia NA. <em>Mycobacterium tuberculosis</em> Extracellular Vesicle Enrichment through Size Exclusion Chromatography. J Vis Exp 2022. [DOI: 10.3791/63895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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Mathias AB, Palmer EP, Kruh-Garcia N, Regan DP. The role of osteosarcoma cell-derived exosomes in the promotion of lung metastasis. THE JOURNAL OF IMMUNOLOGY 2020. [DOI: 10.4049/jimmunol.204.supp.242.44] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Osteosarcoma (OS) is the most common primary tumor of bone and typically occurs in children and young adults. 30–40% of OS patients develop lung metastases after initial diagnosis, with only 20% of these patients surviving 4 years post-relapse. For over 30 years, there have been no improvements in the treatment of OS, and more importantly, no diagnostic tools that help identify those patients at high risk for lung metastases. Recent data has shown that in other tumor types, tumor-secreted extracellular vesicles (EVs) deliver biological cargo to distant sites, resulting in priming of non-malignant host cells for promotion of metastasis. The aim of this project is to understand how OS EVs influence the response of lung fibroblasts (LFs) and alveolar macrophages (AMs), and if their uptake of EVs results in pre-metastatic priming that can be detected via AM transcriptomic changes.
Hypothesis
LFs are primary targets of OS EVs, which will increase LF IL-6 production and cause paracrine STAT3 activation of AM’s into an M2 tumor-promoting phenotype.
Results
Flow cytometry and confocal microscopy demonstrated in vitro uptake of OS EVs by LF cells. In vitro ‘education’ of LFs with OS EVs induced significant production of IL-6, IL-8, and CCL2, with the greatest mean difference between EV-educated and naïve LFs observed with IL-6 secretion.
Conclusion
This data suggest that OS EVs efficiently prime LFs to induce IL-6 secretion, and this response may be associated with promotion of OS lung metastasis. Further data is being collected to determine the role of IL-6 in OS cell survival and lung metastatic colonization. RNA sequencing of AMs will be used to characterize phenotype which could serve as an effective cellular biomarker to predict lung metastasis.
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Ryan JM, Shelton K, Dzieciatkowska M, Kruh-Garcia N, Dobos KM. Establishment of minimum protein standards for Mycobacterium tuberculosis-derived extracellular vesicles through comparison of EV enrichment methods. MYCOBACTERIA (LONDON, ENGLAND) 2025; 1:3. [PMID: 40256639 PMCID: PMC12007408 DOI: 10.1186/s44350-025-00003-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2024] [Accepted: 03/30/2025] [Indexed: 04/22/2025]
Abstract
Mycobacterium tuberculosis extracellular vesicles (MEV) have been described as having potent immunological activities that are both beneficial and harmful to the host. Key to understanding this conflicting information is the proteomic characterization of MEVs. However, there is neither a standard for a purification method nor markers to assess relative purity and quality of MEVs. In this study, we purified MEVs by four different methods (simple ultracentrifugation, differential density gradient-based ultracentrifugation, qEV size exclusion chromatography, and Capto™Core size exclusion chromatography) and assessed the variability of MEV characteristics (size, concentration, appearance, purity, and protein content) amongst isolation methods. The vesicle appearance and size were consistent across all methods; however variability was found between and within all methods, with simple ultracentrifugation demonstrating the most variability both in reproducibility and purity. Protein concentration and content, and particle yield and purity, varied amongst all methods. The two size exclusion chromatography-based methods were more technically reproducible than either ultracentrifugation-based method, while qEV size exclusion chromatography and differential density gradient ultracentrifugation afforded MEV samples of the highest purity. Nonetheless, all methods had 7 proteins in common, the Sec-independent membrane bound twin-arginine translocase TatA (Rv2094c), the periplasmic phosphate-binding lipoprotein PstS3 (Rv0928), the heparin binding hemagglutinin HBHA (Rv0475), lipoprotein antigens LprG (Rv1411c) and LpqH (Rv3763), a member of the conserved 13E12 repeat protein family P95201 (Rv0393), and the tuberculin related peptide Rv0431 (P96277), suggesting the use of these proteins as qualitative markers of MEVs versus contaminants, in addition to size and appearance criteria, to benefit reproducibility and consensus for ongoing MEV studies. Supplementary Information The online version contains supplementary material available at 10.1186/s44350-025-00003-8.
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