pa-824 and Hypoxia

The activities of rifampin, nitazoxanide, PA-824, and sutezolid were tested against dormant

Topics: Antitubercular Agents; Drug Combinations; Drug Therapy, Combination; Ethambutol; Humans; Hydrogen-Ion Concentration; Hypoxia; Isoniazid; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Nitroimidazoles; Oxazolidinones; Pyrazinamide; Rifampin; Tuberculosis

Preclinical evaluation of tuberculosis drugs is generally limited to mice. However, necrosis and hypoxia, key features of human tuberculosis lesions, are lacking in conventional mouse strains.. We used C3HeB/FeJ mice, which develop necrotic lesions in response to Mycobacterium tuberculosis infection. Positron emission tomography in live infected animals, postmortem pimonidazole immunohistochemistry, and bacterial gene expression analyses were used to assess whether tuberculosis lesions in C3HeB/FeJ are hypoxic. Efficacy of combination drug treatment, including PA-824, active against M. tuberculosis under hypoxic conditions, was also evaluated.. Tuberculosis lesions in C3HeB/FeJ (but not BALB/c) were found to be hypoxic and associated with up-regulation of known hypoxia-associated bacterial genes (P < .001). Contrary to sustained activity reported elsewhere in BALB/c mice, moxifloxacin and pyrazinamide (MZ) combination was not bactericidal beyond 3 weeks in C3HeB/FeJ. Although PA-824 added significant activity, the novel combination of PA-824 and MZ was less effective than the standard first-line regimen in C3HeB/FeJ.. We demonstrate that tuberculosis lesions in C3HeB/FeJ are hypoxic. Activities of some key tuberculosis drug regimens in development are represented differently in C3HeB/FeJ versus BALB/c mice. Because C3HeB/FeJ display key features of human tuberculosis, this strain warrants evaluation as a more pathologically relevant model for preclinical studies.

Topics: Animals; Antitubercular Agents; Aza Compounds; Disease Models, Animal; Fluoroquinolones; Gene Expression Profiling; Genes, Bacterial; Granuloma; Hypoxia; Immunohistochemistry; Male; Mice; Mice, Inbred C3H; Moxifloxacin; Mycobacterium tuberculosis; Nitroimidazoles; Positron-Emission Tomography; Pyrazinamide; Quinolines; Treatment Outcome; Tuberculosis

The one-electron reduction chemistry of the antituberculosis drug PA-824, together with a series of closely related compounds, has been investigated in irradiated anaerobic propan-2-ol solution. The protic solvent, of low dielectric constant, was chosen to mimic the environment of a water-restricting active site of a model protein, which is capable of reducing the compounds. Radiolytic reduction of the compounds containing electron donating substituents in the 2-position of the imidazole ring released nitrite, with compounds that are highly active against Mycobacterium tuberculosis exhibiting high yields of nitrite. The release of cytotoxic reactive nitrogen species through a one-electron pathway, by as yet unidentified proteins, may play a role in the activity of this class of compounds against TB. The described radiolytic quantification of nitrite release may have utility as a preliminary screening test for nitroaromatic candidate drugs against the disease.

Topics: Aerobiosis; Antitubercular Agents; Electron Transport; Hypoxia; Mass Spectrometry; Mycobacterium tuberculosis; Nitriles; Nitrites; Nitrobenzenes; Nitroimidazoles; Pulse Radiolysis; Reactive Nitrogen Species; Solvents; Spectrophotometry, Ultraviolet; Water