Mouse model of necrotic tuberculosis granulomas develops hypoxic lesions

Area of Science:

• Tuberculosis research
• Infectious disease modeling
• Preclinical drug evaluation

Background:

• Conventional mouse models for tuberculosis (TB) drug evaluation lack key human lesion features like necrosis and hypoxia.
• Developing more accurate preclinical models is crucial for effective TB drug development.

Purpose of the Study:

• To evaluate C3HeB/FeJ mice as a preclinical model for tuberculosis by assessing lesion hypoxia.
• To investigate the efficacy of novel drug combinations against Mycobacterium tuberculosis in a hypoxic lesion environment.

Main Methods:

• C3HeB/FeJ mice were infected with Mycobacterium tuberculosis to induce necrotic lesions.
• Positron emission tomography, pimonidazole immunohistochemistry, and bacterial gene expression analysis were used to confirm hypoxia.
• The efficacy of drug combinations, including PA-824, moxifloxacin, and pyrazinamide, was assessed.

Main Results:

• Tuberculosis lesions in C3HeB/FeJ mice were confirmed to be hypoxic, with up-regulation of hypoxia-associated bacterial genes.
• The standard moxifloxacin and pyrazinamide (MZ) combination showed limited bactericidal activity beyond 3 weeks in C3HeB/FeJ mice.
• While PA-824 demonstrated activity, the novel PA-824 and MZ combination was less effective than the standard first-line regimen.

Conclusions:

• Tuberculosis lesions in C3HeB/FeJ mice are demonstrably hypoxic, mirroring human disease characteristics.
• Drug efficacy in C3HeB/FeJ mice differs from BALB/c mice, highlighting the importance of model selection.
• C3HeB/FeJ mice represent a more pathologically relevant model for preclinical tuberculosis studies.