Enhanced bacterial clearance and sepsis resistance in caspase-12-deficient mice

Area of Science:

• Immunology
• Molecular Biology
• Cell Death Research

Background:

• Caspases are key regulators of apoptosis and inflammation, influencing sepsis outcomes.
• A novel role for caspase-12 in modulating host responses to bacterial infection is investigated.

Purpose of the Study:

• To elucidate the function of caspase-12 in bacterial infection and sepsis.
• To determine the mechanism by which caspase-12 influences inflammatory responses and survival.

Main Methods:

• Gene-targeted deletion of caspase-12 in mice to create knockout models.
• Assessment of survival rates, bacterial clearance, and cytokine production (IL-1beta, IL-18, IFN-gamma) in response to bacterial components.
• Investigation of caspase-12 interaction with caspase-1 and the role of caspase-12's protease activity using a catalytically inactive mutant.

Main Results:

• Caspase-12 deficient mice exhibited resistance to peritonitis and septic shock, demonstrating enhanced survival.
• These mice showed more efficient bacterial clearance compared to wild-type littermates.
• Caspase-12 deficiency led to reduced production of IL-1beta, IL-18, and IFN-gamma, while TNF-alpha and IL-6 remained unaffected.
• The protective effect was dependent on the interferon-gamma (IFN-gamma) pathway.
• Caspase-12 associated with and inhibited caspase-1 activity, even in its catalytically inactive form, suggesting a dominant-negative role.

Conclusions:

• Caspase-12 deficiency confers resistance to sepsis by enhancing bacterial clearance and modulating inflammatory cytokine production.
• Caspase-12 acts as a negative regulator of caspase-1 and the inflammatory response, with its absence conferring a survival advantage.
• The findings identify caspase-12 as a potential therapeutic target for sepsis treatment.