Leukocytes mediate acid aspiration-induced multiorgan edema

Area of Science:

• Pulmonary Medicine
• Immunology
• Critical Care

Background:

• Acid aspiration causes lung injury with neutrophil sequestration and edema.
• The role of circulating neutrophils in acid aspiration-induced injury is not fully understood.

Purpose of the Study:

• To investigate if localized acid aspiration activates circulating neutrophils.
• To determine if activated neutrophils cause local and remote organ sequestration.
• To assess neutrophil involvement in pulmonary permeability and systemic organ edema.

Main Methods:

• Rats were pretreated with saline or made neutropenic (nitrogen mustard or antineutrophil serum).
• Tracheostomy and lung segment instillation of 0.1 N HCl or saline were performed.
• Circulating white blood cell counts, neutrophil activation markers, and organ wet-to-dry weights were measured.

Main Results:

• Acid aspiration induced leukopenia and neutrophil activation (H2O2 production).
• Neutrophils sequestered in non-aspirated lungs, heart, and kidneys, correlating with organ edema.
• Neutropenic rats showed reduced inflammatory mediators, lung edema, and systemic organ damage.

Conclusions:

• Localized acid aspiration activates circulating neutrophils.
• Activated neutrophils contribute significantly to lung injury and multisystem organ edema.
• Neutrophils play a critical role in the pathogenesis of acid aspiration-induced injury.