Editor's Highlight: Pulmonary Vascular Thrombosis in Rats Exposed to Inhaled Sulfur Mustard

Area of Science:

• Toxicology
• Pulmonary Medicine
• Hematology

Background:

• Sulfur mustard (SM) is a chemical warfare agent known to cause severe respiratory tract injury upon inhalation.
• The precise mechanisms by which SM induces distal lung vascular injury remain incompletely understood.
• Previous research has focused on acute airway injury, leaving a knowledge gap in SM's effects on pulmonary vasculature.

Purpose of the Study:

• To investigate the hypothesis that acute SM inhalation leads to activated systemic coagulation and subsequent pulmonary vascular thrombi formation.
• To elucidate the role of SM exposure in distal lung vascular injury.
• To assess the impact of SM on coagulation markers and platelet function in vivo.

Main Methods:

• Sprague Dawley rats were exposed to vaporized SM (3.8 mg/kg).
• Pulmonary vascular thrombi burden was assessed using barium/gelatin CT pulmonary angiography.
• Lung immunohistochemistry was performed for fibrin(ogen), von Willebrand factor, and CD42d.
• Systemic d-dimer levels and platelet aggregometry were measured post-exposure.

Main Results:

• CT angiography revealed significantly decreased distal pulmonary vessel density at 6 hours post-SM exposure.
• Immunohistochemistry showed increased intravascular fibrin(ogen), von Willebrand factor, and CD42d in distal pulmonary vessels (<200 µm).
• Circulating d-dimer levels and platelet aggregation (ADP and thrombin-stimulated) were significantly increased post-SM inhalation.

Conclusions:

• Acute SM inhalation in rats causes significant pulmonary vascular thrombi formation in distal pulmonary arterioles.
• Enhanced systemic platelet aggregation and activated systemic coagulation are key contributors to SM-induced pulmonary vessel occlusion.
• These findings highlight a critical mechanism of SM-induced lung injury beyond acute airway damage.