Our goal is to determine the biochemical and structural basis for binding of Mycobacterium tuberculosis (MTB) lipoproteins to Toll-like receptor (TLR)-2 and resulting agonist activity. TLR2 recognition of MTB lipoproteins initiates innate immunity and influences adaptive immunity to MTB. Despite this critical role for TLR2 in tuberculosis, the structural basis for TLR2 recognition of MTB lipoproteins remains poorly understood. In addition, TLR2 functions in recognition of other pathogenic species, yet the structural determinants of TLR2 agonist activity are largely unexplored. It is known that acyl structures of lipoproteins influence their recognition by TLR2, but the influence of protein structures on TLR2 binding is essentially unknown. We have characterized three distinct MTB lipoproteins that signal through TLR2: LpqH (19-kDa lipoprotein), LprG and LprA. These lipoproteins are all TLR2 agonists but differ in potency and apparent structural determinants of their activity. Our data indicate that both lipid and protein components of MTB lipoproteins can influence TLR2 agonist activity. We are constructing recombinant tagged lipoproteins and soluble TLR2 fusion proteins to dissect structure-function relationships in TLR2-ligand interactions relevant to these pathophysiologically important TLR2 agonists from MTB.
Aim 1 will use cellular cytokine secretion readouts to study the activity of His-tagged recombinant MTB lipoproteins and their receptor dependence (use of TLR1 or TLR6 as co-receptors in heterodimers with TLR2, as well as use of accessory receptors, CD14 and CD36).
Aim 2 will determine structural features of MTB lipoproteins that affect interations with TLR2, TLR1, TLR6 and accessory receptors (CD14 and CD36) by use of macrophages and dendritic cells from mice that are genetically deficient in there receptors and analyses of MTB lipoprotein variantswithout acylation and/or with deletions, truncations or mutations in the protein sequence (or use of minimal active constructs expressed as recombinant proteins or made as synthetic peptides).
Aim 3 will use direct biochemical binding assays to study binding of tagged recombinant soluble TLR and lipoprotein molecules. We will measure the affinities of different MTB lipoproteins and structural variants thereof for TLR2 to further understand the structural determinants of agonist binding to TLR2. Overall we will determine the structural basis for binding of MTB lipoproteins to TLR2, including contributions of lipid and protein components.

Public Health Relevance

These studies will provide unique and novel insights into the mechanisms by which TLR2 recognizes MTB. TLR2 is a key immune system receptor involved in recognition of MTB. Greater understanding of its function will help reveal important mechanisms in immunity that lead to host resistance and/or evasion of immunity during chronic infection by MTB. This may help develop better treatments for tuberculosis. It may also aid in design of better immune adjuvants for a wide array of therapeutic uses.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Special Emphasis Panel (ZRG1-IDM-A (02))
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Parker, Tina M
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Case Western Reserve University
Schools of Medicine
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Athman, Jaffre J; Sande, Obondo J; Groft, Sarah G et al. (2017) Mycobacterium tuberculosis Membrane Vesicles Inhibit T Cell Activation. J Immunol 198:2028-2037
Karim, Ahmad F; Sande, Obondo J; Tomechko, Sara E et al. (2017) Proteomics and Network Analyses Reveal Inhibition of Akt-mTOR Signaling in CD4+ T Cells by Mycobacterium tuberculosis Mannose-Capped Lipoarabinomannan. Proteomics 17:
Sande, Obondo J; Karim, Ahmad F; Li, Qing et al. (2016) Mannose-Capped Lipoarabinomannan from Mycobacterium tuberculosis Induces CD4+ T Cell Anergy via GRAIL. J Immunol 196:691-702
Nguyen, Thao P; Bazdar, Doug A; Mudd, Joseph C et al. (2015) Interferon-? inhibits CD4 T cell responses to interleukin-7 and interleukin-2 and selectively interferes with Akt signaling. J Leukoc Biol 97:1139-46
Athman, Jaffre J; Wang, Ying; McDonald, David J et al. (2015) Bacterial Membrane Vesicles Mediate the Release of Mycobacterium tuberculosis Lipoglycans and Lipoproteins from Infected Macrophages. J Immunol 195:1044-53
Richardson, Edward T; Shukla, Supriya; Sweet, David R et al. (2015) Toll-like receptor 2-dependent extracellular signal-regulated kinase signaling in Mycobacterium tuberculosis-infected macrophages drives anti-inflammatory responses and inhibits Th1 polarization of responding T cells. Infect Immun 83:2242-54
Shukla, Supriya; Richardson, Edward T; Athman, Jaffre J et al. (2014) Mycobacterium tuberculosis lipoprotein LprG binds lipoarabinomannan and determines its cell envelope localization to control phagolysosomal fusion. PLoS Pathog 10:e1004471
Yu, Minjia; Zhou, Hao; Zhao, Junjie et al. (2014) MyD88-dependent interplay between myeloid and endothelial cells in the initiation and progression of obesity-associated inflammatory diseases. J Exp Med 211:887-907
Gabrilovich, M I; Walrath, J; van Lunteren, J et al. (2013) Disordered Toll-like receptor 2 responses in the pathogenesis of pulmonary sarcoidosis. Clin Exp Immunol 173:512-22
Hardy, Gareth A D; Sieg, Scott; Rodriguez, Benigno et al. (2013) Interferon-? is the primary plasma type-I IFN in HIV-1 infection and correlates with immune activation and disease markers. PLoS One 8:e56527

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