Mechanistic Insights of Sulfur Mustard-Induced Acute Tracheal Injury in Rats

Sulfur mustard (SM) is believed to be a major threat to civilian populations because of the persistent asymmetric threat by nonstate actors, such as terrorist groups, the ease of synthesis and handling, and the risk of theft from stockpiles. The purpose of this study was to establish mechanisms of acute tracheal injury in rats induced by SM using histopathologic, immunohistochemical, and biochemical parameters. Male rats (Sprague-Dawley) were anesthetized, intratracheally intubated, and exposed to 2 mg/kg of SM. Animals were euthanized 6-, 24-, 48-, and 72-hour postexposure, and intracavitary blood samples from the heart and tracheal tissues were collected. Exposure of rats to SM resulted in rapid tracheal injury, including tracheal epithelial cell shedding, focal ulceration, and abundant lymphocyte invasion of the submucosa. There was also evidence of a large number of apoptotic cells in the epithelium and submucosa, the serum levels of tumor necrosis factor , interleukin 1 (IL) 1, IL-6, and -glutamyl transferase peaked at 24 hours, and the serum levels of lactate dehydrogenase, glutathione peroxidase, and thiobarbituric acid reactive substance peaked at 6 hours. The SM exposure also resulted in a loss of the cellular membrane, leakage of cytoplasm, fuzzy mitochondrial cristae, medullary changes in ciliated and goblet cells, and the nuclear chromatin appeared marginated in basal cells and fibroblasts. The results in the propylene glycol group were the same as the control group. These data demonstrated the histologic changes, inflammatory reactions, apoptosis, oxidative stress, and DNA damage following SM (2 mg/kg)-induced acute tracheal injury; the severity of changes was time dependent.