Tuberculosis in CBA/J mice.

Area of Science:

• Immunology
• Pathology
• Microbiology

Background:

• Tuberculosis (TB) affects 5-10% of Mycobacterium tuberculosis (M.tb) infected individuals, but disease development mechanisms remain poorly understood.
• CBA/J mice exhibit TB-like symptoms including weight loss, M.tb growth, granulomatous infiltrates, neutrophils, necrosis, and fibrosis, potentially modeling human TB.
• Understanding TB pathogenesis is crucial for developing effective treatments and interventions.

Purpose of the Study:

• To investigate the association between clinical status (weight loss) and lung pathology in M.tb-infected CBA/J mice.
• To determine if CBA/J mice can serve as a relevant model for studying TB disease progression.
• To explore the role of neutrophils in the development of TB lesions.

Main Methods:

• Mice infected with M.tb were clinically assessed and categorized based on weight loss (none vs. 10%).
• Lung tissues were examined for the type, distribution, and extent of inflammatory infiltrates, necrosis, and fibrosis.
• Histopathological analysis was performed to compare lesions between clinically distinct groups of mice.

Main Results:

• Lung infiltrates (granulomatous with lymphoid aggregates and neutrophils) were similar in type and distribution between mice with and without weight loss.
• Mice experiencing 10% weight loss showed significantly higher infiltration and neutrophil foci compared to asymptomatic mice.
• Necrosis and fibrosis were exclusively observed in M.tb-infected CBA/J mice that exhibited weight loss.

Conclusions:

• CBA/J mice with M.tb infection develop distinct lung pathologies correlating with clinical signs of disease.
• The presence of weight loss in M.tb-infected CBA/J mice is associated with increased inflammation, necrosis, and fibrosis.
• These findings support the utility of CBA/J mice as a model to investigate the contribution of neutrophils to TB disease progression.