Mitochondrial dysfunction and lipid accumulation in the human diaphragm during mechanical ventilation

Area of Science:

• Mitochondrial biology
• Respiratory physiology
• Cellular metabolism

Background:

• Mechanical ventilation (MV) can harm the diaphragm, leading to ventilator-induced diaphragmatic dysfunction (VIDD).
• The cellular mechanisms underlying VIDD, particularly mitochondrial involvement, are not fully understood.

Purpose of the Study:

• To investigate mitochondrial function and energy status in human diaphragms following MV.
• To determine the role of mitochondria-derived oxidative stress in VIDD development.

Main Methods:

• Comparison of mitochondrial function, DNA integrity, lipid content, and metabolic gene/protein expression in human diaphragm/biceps from MV organ donors versus controls.
• Evaluation of diaphragmatic force and oxidative stress in mice exposed to MV, with and without hyperlipidemia or antioxidant treatment.

Main Results:

• Human MV diaphragms showed reduced mitochondrial biogenesis and content, with specific defects in cytochrome-c oxidase and mitochondrial DNA deletions, indicating oxidative stress damage.
• Diaphragmatic lipid accumulation and altered metabolic sensor activity suggested energy substrate excess.
• In mice, hyperlipidemia exacerbated MV-induced oxidative stress, while a mitochondrial antioxidant protected against VIDD.

Conclusions:

• Mitochondrial dysfunction and oxidative stress are central to impaired diaphragmatic contractility during MV.
• Diaphragmatic inactivity during MV may lead to energy substrate oversupply, contributing to mitochondrial dysfunction and VIDD.