The extrinsic caspase pathway modulates endotoxin-induced diaphragm contractile dysfunction.

Area of Science:

• Physiology
• Molecular Biology
• Immunology

Background:

• Infections can lead to diaphragm dysfunction, impacting respiratory function.
• The specific molecular mechanisms, particularly the role of caspases, in infection-induced diaphragm weakness are not fully understood.

Purpose of the Study:

• To investigate the role of caspase-8 and caspase-9 pathways in endotoxin-induced diaphragm contractile dysfunction.
• To determine if inhibiting these caspase pathways can prevent diaphragm weakness.

Main Methods:

• Administered endotoxin to mice and measured diaphragm force generation and caspase activity.
• Utilized caspase-8 and caspase-9 inhibitors to assess their effects on endotoxin-induced dysfunction.
• Examined TNF receptor 1-deficient mice and cytokine-stimulated myotubes to explore upstream signaling.

Main Results:

• Endotoxin significantly reduced diaphragm force and increased caspase-3 and caspase-8 activity, but not caspase-9.
• Caspase-8 inhibition, but not caspase-9 inhibition, prevented endotoxin-induced diaphragm weakness and caspase-3 activation.
• TNF receptor 1 deficiency and cytokine exposure (TNF-alpha, cytomix) led to increased caspase-8 activation.

Conclusions:

• The caspase-8 pathway is critically involved in endotoxin-induced diaphragm weakness.
• Targeting the caspase-8 pathway may offer a therapeutic strategy for managing infection-related diaphragm dysfunction.