Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb), is a global health problem. Treatment of drug-susceptible TB involves months of therapy with multiple potentially toxic antibiotics. Treatment of TB has become even more difficult by the emergence and increasing prevalence of multi-drug resistant M.tb. This proposal focuses on the development of a novel therapy that targets M.tb iron (Fe) acquisition, a process that is critical to its ability to cause disease. Ga(NO3)3 is a FDA- approved drug for treating hypercalcemia of malignancy. It interferes with cellular Fe metabolism by competing with Fe for uptake/use. We find that Ga also decreases M.tb Fe acquisition, inhibits growth of both drug-susceptible and drug-resistant M.tb strains growing in vitro extracellularly and within human macrophages. Ga also demonstrated efficacy in murine models of M.tb infection. Intermittent systemic delivery of Ga(NO3)3 for a few days has shown minimal toxicity in humans. However, treatment of TB would likely require more sustained treatment regimens. Ways to improve targeting of Ga to infected macrophages, extend dosing intervals, or avoid systemic administration would improve Ga's therapeutic index. There have been considerable advances in recent years in the aerosol delivery of drugs to the lung, as well as cellular targeting of nanoparticles to accomplish these goals. Therefore, we hypothesize that Ga delivery by aerosol or nanoparticle to the lung could prove to be novel, well-tolerated, and effective therapies for TB that would work via disruption of M.tb Fe metabolism. In order to test the above hypothesis we propose to accomplish the following specific aims: 1. Identify forms of Ga that exhibit maximal in vitro potency against extracellular and intracellular M.tb, including MDR- and XDR-TB, with the goal of arriving at lead compounds. 2. Develop formulations of two lead Ga compounds that will allow them to be administered by inhalation for the treatment of pulmonary TB and determine their biodistribution, pharmacokinetics, toxicity and efficacy in murine models of pulmonary TB. 3. Develop nanoparticle formulations of two lead Ga compounds that will allow them to be administered for the treatment of pulmonary TB and determine their biodistribution, pharmacokinetics, toxicity and efficacy in murine models of pulmonary TB. 4. Determine mechanisms of action of the lead Ga formulations against M.tb, potential for emergence of resistance, and effect of the presence of other TB drugs on Ga anti-mycobacterial activity. RESEARCH DESIGN AND METHODOLOGY: Human monocyte-derived macrophages and murine models of TB will be employed along with fully virulent strains of M.tb. The work will emphasize: Fe and Ga acquisition by M.tb: Ga biodistribution, pharmacokinetics, toxicity; and potential bacterial target for Ga antimicrobial activity. Experimental methods employed include: development of Ga formulations suitable for aerosol or nanoparticle-mediated delivery; bacterial uptake of radiolabeled Fe and Ga, growth of M.tb in vitro and in vivo, murine models of pulmonary TB, quantitation of Ga in tissues. POTENTIAL IMPACT ON VETERAN HEALTH CARE: Veterans are at high risk for pulmonary TB. This work could lead to development of novel treatments for TB that would benefit veterans.

Public Health Relevance

Tuberculosis is a worldwide health problem, with new drugs needed to combat the increasing prevalence of multi-drug-resistant Mycobacterium tuberculosis strains. The proposed studies will provide a novel approach to disruption of M. tuberculosis iron metabolism using gallium. To enhance efficacy and decrease toxicity we will explore unique delivery approaches - aerosolization directly into the lung or nanoparticles. These studies could ultimately lead to the development of a novel anti-TB drug.

Agency
National Institute of Health (NIH)
Institute
Veterans Affairs (VA)
Type
Non-HHS Research Projects (I01)
Project #
1I01BX002504-01
Application #
8731319
Study Section
Infectious Diseases B (INFB)
Project Start
2014-10-01
Project End
2018-09-30
Budget Start
2014-10-01
Budget End
2015-09-30
Support Year
1
Fiscal Year
2015
Total Cost
Indirect Cost
Name
Omaha VA Medical Center
Department
Type
DUNS #
844360367
City
Omaha
State
NE
Country
United States
Zip Code
68105
Choi, Seoung-Ryoung; Britigan, Bradley E; Switzer, Barbara et al. (2018) In Vitro Efficacy of Free and Nanoparticle Formulations of Gallium(III) meso-Tetraphenylporphyrine against Mycobacterium avium and Mycobacterium abscessus and Gallium Biodistribution in Mice. Mol Pharm 15:1215-1225
Choi, Seoung-Ryoung; Britigan, Bradley E; Moran, David M et al. (2017) Gallium nanoparticles facilitate phagosome maturation and inhibit growth of virulent Mycobacterium tuberculosis in macrophages. PLoS One 12:e0177987
Pasula, Rajamouli; Martin 2nd, William J; Kesavalu, Banu Rekha et al. (2017) Passive transfer of interferon-? over-expressing macrophages enhances resistance of SCID mice to Mycobacterium tuberculosis infection. Cytokine 95:70-79
Abdalla, Maher Y; Hoke, Traci; Seravalli, Javier et al. (2017) Pseudomonas Quinolone Signal Induces Oxidative Stress and Inhibits Heme Oxygenase-1 Expression in Lung Epithelial Cells. Infect Immun 85:
Choi, Seoung-Ryoung; Britigan, Bradley E; Narayanasamy, Prabagaran (2017) Ga(III) Nanoparticles Inhibit Growth of both Mycobacterium tuberculosis and HIV and Release of Interleukin-6 (IL-6) and IL-8 in Coinfected Macrophages. Antimicrob Agents Chemother 61:
Narayanasamy, Prabagaran; Switzer, Barbara L; Britigan, Bradley E (2015) Prolonged-acting, multi-targeting gallium nanoparticles potently inhibit growth of both HIV and mycobacteria in co-infected human macrophages. Sci Rep 5:8824
Abdalla, Maher Y; Ahmad, Iman M; Switzer, Barbara et al. (2015) Induction of heme oxygenase-1 contributes to survival of Mycobacterium abscessus in human macrophages-like THP-1 cells. Redox Biol 4:328-39