Mycobacterium avium is a major opportunistic pathogen in AIDS patients as well as a major cause of pulmonary infection in individuals with underlying lung disease. However, our understanding of M. avium pathogenesis is lacking due in part to limited information on M. avium components involved in modulating the host response. Nevertheless, previous studies suggest that glycopeptidolipids (GPLs), which are major surface components expressed on many non-tuberculosis mycobacteria, may function in directing the host response to an M. avium infection. We have found that GPLs can engage the pattern recognition receptor Toll-like receptor 2 (TLR2) leading to macrophage activation. Interestingly, we found that GPLs varied in their ability to interact with TLR2 and that slight changes in the GPL acetylation and methylation patterns determine whether this glycolipid can signal through TLR2. GPLs can also engage the mannose receptor and that this interaction is required for the delayed accusation of lysosomal markers observed for phagosomes containing GPL-coated beads. Based on these observations we hypothesize that M. avium can modify its GPL structure during the course of an infection and that this is an important virulence mechanism. Further, we predict that increased expression of certain GPL variants by M. avium will correlate with a strain's pathogenicity. To test these predictions we will: 1) Define the GPL structural components necessary for its binding to the MR and for its ability to delay phagosome maturation and the mechanism by which GPLs mediate this delay. 2) Characterize the GPL composition of M. avium strains following macrophage and mouse infections and define how the GPL composition correlates with strain virulence. 3) Generate M. avium knockout mutants for genes involved in GPL biosynthesis and evaluate the mutants for GPL-mediated activities including signaling through TLR2 and MR, biofilm formation and sliding motility and for virulence in a mouse infection model. Upon completion of these studies we will have a better understanding of M. avium pathogenesis and the role that GPLs play in this process and the information garnered may lead to the development of new diagnostic tools to evaluate M. avium virulence.

Public Health Relevance

Mycobacterium avium is a major opportunistic pathogen in AIDS patients and a significant cause of morbidity and mortality in HIV infected individuals. It is also a common cause of pulmonary infections in individuals with underlying lung disease. The goal of this proposal is to better understand M. avium pathogenesis so as to develop new methods to limit M. avium infections and to treat those infected.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Special Emphasis Panel (ZRG1-AARR-E (02))
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Jacobs, Gail G
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University of Notre Dame
Schools of Arts and Sciences
Notre Dame
United States
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Cheng, Yong; Schorey, Jeffrey S (2018) Mycobacterium tuberculosis-induced IFN-? production requires cytosolic DNA and RNA sensing pathways. J Exp Med 215:2919-2935
D'Souza-Schorey, Crislyn; Schorey, Jeffrey S (2018) Regulation and mechanisms of extracellular vesicle biogenesis and secretion. Essays Biochem 62:125-133
Smith, Victoria L; Cheng, Yong; Bryant, Barry R et al. (2017) Exosomes function in antigen presentation during an in vivo Mycobacterium tuberculosis infection. Sci Rep 7:43578
Singh, Prachi Pratap; Li, Li; Schorey, Jeffrey Scott (2015) Exosomal RNA from Mycobacterium tuberculosis-Infected Cells Is Functional in Recipient Macrophages. Traffic 16:555-71
Schorey, Jeffrey S; Cheng, Yong; Singh, Prachi P et al. (2015) Exosomes and other extracellular vesicles in host-pathogen interactions. EMBO Rep 16:24-43
Smith, Victoria L; Jackson, Liam; Schorey, Jeffrey S (2015) Ubiquitination as a Mechanism To Transport Soluble Mycobacterial and Eukaryotic Proteins to Exosomes. J Immunol 195:2722-30
Kruh-Garcia, Nicole A; Wolfe, Lisa M; Chaisson, Lelia H et al. (2014) Detection of Mycobacterium tuberculosis peptides in the exosomes of patients with active and latent M. tuberculosis infection using MRM-MS. PLoS One 9:e103811
Cheng, Yong; Schorey, Jeffery S (2013) Exosomes carrying mycobacterial antigens can protect mice against Mycobacterium tuberculosis infection. Eur J Immunol 43:3279-90
Singh, Prachi P; Smith, Victoria L; Karakousis, Petros C et al. (2012) Exosomes isolated from mycobacteria-infected mice or cultured macrophages can recruit and activate immune cells in vitro and in vivo. J Immunol 189:777-85
Singh, Prachi P; LeMaire, Christopher; Tan, John C et al. (2011) Exosomes released from M. tuberculosis infected cells can suppress IFN-ýý mediated activation of naive macrophages. PLoS One 6:e18564

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