Inflammasome Activation Differences Underpin Different Mycobacterium tuberculosis Infection Outcomes

Area of Science:

• Immunology
• Microbiology
• Cellular Biology

Background:

• Tuberculosis (TB) outcomes vary from latent to active disease.
• Cellular mechanisms driving these different TB outcomes are not fully understood.

Purpose of the Study:

• Investigate cellular pathways differentiating progressive from nonprogressive Mycobacterium tuberculosis (Mtb) infection.
• Identify key molecular players influencing TB disease progression.

Main Methods:

• Infection of rabbit lungs and macrophages (rabbit, human, THP-1) with virulent and nonvirulent Mtb strains.
• Analysis of guanylate-binding protein-1 (GBP1), hypoxia-inducible factor-1 alpha (HIF-1α), and NLRP3 inflammasome activation.
• Assessment of mitochondrial stress, apoptosis, and necrosis.
• Gene knockdown studies for HIF-1α and GBP1.

Main Results:

• Progressive Mtb infection correlates with elevated GBP1, HIF-1α, and NLRP3 inflammasome activation.
• HIF-1α and GBP1 drive NLRP3 inflammasome activation, causing mitochondrial stress, apoptosis, and necrosis in progressive infections.
• These pathways are suppressed in nonprogressive TB and in cells with reduced HIF-1α or GBP1.

Conclusions:

• Differential activation of HIF-1α- and GBP1-mediated NLRP3 inflammasome pathways influences Mtb infection outcomes.
• These findings provide insight into the cellular basis of TB disease progression.
• Targeting these pathways could offer new therapeutic strategies for TB.