With 8.9 million new cases and 1.7 million deaths per year tuberculosis is a leading AIDS-related global killer which has not been effectively controlled. The causative agent, Mycobacterium tuberculosis, proliferates within host macrophages where it modifies both its intracellular and local tissue environment resulting in caseous granulomas with incomplete bacterial sterilization. We recently reported that M. tuberculosis uses at least one of its adenylate cyclases (Rv0386) to secrete cAMP into the host cell cytoplasm. By this cAMP intoxication mechanism, M. tuberculosis subverts host cell signal transduction by induction of protein kinase A (PKA), upregulation of cAMP-response element binding protein (CREB) phosphorylation, and a cascade of additional responses including excess TNF-1 secretion. Recently we have begun to probe other consequences of cAMP intoxication using novel recombinant M. tuberculosis strains with altered ability to deliver cAMP, through microarray and multiplex cytokine profiling, and through pharmacologic inhibition of key cAMP signaling pathways. We have found that cAMP intoxication may block induction of the key host cell anti- microbial peptides (AMPs) cathelicidin and human 2-defensin-1. Also, we found that pharmacologic inhibitors of phosphodiesterases modulate the outcome of murine tuberculosis possibly by interfering with the cAMP intoxication pathway.
In Aim 1 of this study we will systematically address the consequences of cAMP intoxication at the cellular level in vitro, in whole lung tissue using the mouse model in vivo, and at the granuloma level using laser-capture microdissection in specialized animal models including the rabbit which display caseation necrosis.
In Aim 2 we will investigate the ability of clinically available signal transduction inhibitors (PDE inhibitors, JAK inhibitors) to modulate the cAMP intoxication pathways identified in Aim 1, and we will test some of these drugs for their ability to accelerate cure when used as adjuvant immunomodulatory drugs in the TB mouse model.
In Aim 3 we will investigate whether bacterial mechanisms to elevate intramacrophage cAMP levels may inhibit the expression of host AMPs (cathelicidin and human 2-defensin-1) and determine the extent to which vitamin D induction of AMPs may override this mycobacterial virulence mechanism.

Public Health Relevance

The bacteria causing TB enter human cells and subvert normal human cell signaling by secreting excess levels of the second-messenger, cyclic-AMP;we have observed that this process enables the microbe to block host cell secretion of key defense molecules known as anti-microbial peptides. This study will identify the specific mechanisms and inflammatory processes that are subverted by bacterial cyclic-AMP secretion and will test clinically available drugs which may interfere with the microbial cAMP-mediated subversion.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI036973-20
Application #
8702071
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Lacourciere, Karen A
Project Start
1994-09-30
Project End
2015-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
20
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Johns Hopkins University
Department
Type
Schools of Medicine
DUNS #
City
Baltimore
State
MD
Country
United States
Zip Code
21218
Rogers, Zoe; Hiruy, Hiwot; Pasipanodya, Jotam G et al. (2016) The Non-Linear Child: Ontogeny, Isoniazid Concentration, and NAT2 Genotype Modulate Enzyme Reaction Kinetics and Metabolism. EBioMedicine 11:118-126
Winglee, Kathryn; Manson McGuire, Abigail; Maiga, Mamoudou et al. (2016) Whole Genome Sequencing of Mycobacterium africanum Strains from Mali Provides Insights into the Mechanisms of Geographic Restriction. PLoS Negl Trop Dis 10:e0004332
Ahidjo, Bintou A; Maiga, Mariama C; Ihms, Elizabeth A et al. (2016) The antifibrotic drug pirfenidone promotes pulmonary cavitation and drug resistance in a mouse model of chronic tuberculosis. JCI Insight 1:e86017
Kubler, Andre; Larsson, Christer; Luna, Brian et al. (2016) Cathepsin K Contributes to Cavitation and Collagen Turnover in Pulmonary Tuberculosis. J Infect Dis 213:618-27
Maiga, Mamoudou; Cohen, Keira; Baya, Bocar et al. (2016) Stool microbiome reveals diverse bacterial ureases as confounders of oral urea breath testing for Helicobacter pylori and Mycobacterium tuberculosis in Bamako, Mali. J Breath Res 10:036012
Dey, Bappaditya; Dey, Ruchi Jain; Cheung, Laurene S et al. (2015) A bacterial cyclic dinucleotide activates the cytosolic surveillance pathway and mediates innate resistance to tuberculosis. Nat Med 21:401-6
Maiga, Mariama C; Ahidjo, Bintou Ahmadou; Maiga, Mamoudou et al. (2015) Roflumilast, a Type 4 Phosphodiesterase Inhibitor, Shows Promising Adjunctive, Host-Directed Therapeutic Activity in a Mouse Model of Tuberculosis. Antimicrob Agents Chemother 59:7888-90
Winglee, Kathryn; Lun, Shichun; Pieroni, Marco et al. (2015) Mutation of Rv2887, a marR-like gene, confers Mycobacterium tuberculosis resistance to an imidazopyridine-based agent. Antimicrob Agents Chemother 59:6873-81
Kübler, André; Luna, Brian; Larsson, Christer et al. (2015) Mycobacterium tuberculosis dysregulates MMP/TIMP balance to drive rapid cavitation and unrestrained bacterial proliferation. J Pathol 235:431-44
Sullivan, Zuri A; Wong, Emily B; Ndung'u, Thumbi et al. (2015) Latent and Active Tuberculosis Infection Increase Immune Activation in Individuals Co-Infected with HIV. EBioMedicine 2:334-340

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