Polymorphonuclear leukocyte cytoplasts mediate acute lung injury

Area of Science:

• Pulmonary Medicine
• Cell Biology
• Toxicology

Background:

• Polymorphonuclear leukocytes (PMNs) play a role in inflammatory lung injury.
• PMN cytoplasts are anucleated cytoplasmic fragments capable of releasing reactive oxygen species (ROS).
• The specific contribution of PMN cytoplasts to acute lung injury (ALI) is not fully understood.

Purpose of the Study:

• To investigate the role of PMN cytoplasts in the development of ALI.
• To determine if PMN cytoplasts can mediate increased endothelial permeability.
• To assess the potential protective effect of dimethylthiourea (DMTU) against PMN cytoplast-induced ALI.

Main Methods:

• Acute lung injury was induced in PMN-depleted rabbits by injecting phorbol 12-myristate 13-acetate (PMA) to activate PMN cytoplasts.
• Measurements included lung weight-to-body weight ratios, circulating cytoplast counts, and levels of angiotensin-converting enzyme and albumin in lung lavage.
• In vitro experiments assessed the effect of activated PMN cytoplasts on endothelial monolayer permeability.

Main Results:

• PMA injection into PMN cytoplast-repleted rabbits caused ALI, evidenced by increased lung weight and elevated albumin in lung lavage.
• Activated PMN cytoplasts significantly increased endothelial monolayer permeability in vitro.
• Pretreatment with DMTU attenuated the ALI and vascular permeability changes.

Conclusions:

• PMN cytoplasts, when activated, can induce acute lung injury.
• PMN cytoplasts mediate increased endothelial permeability, likely through the release of toxic O2 radicals.
• DMTU demonstrates a protective effect, suggesting that ROS contribute to PMN cytoplast-induced lung injury.