Smoke inhalation with a concurrent systemic stress results in lung alveolar injury

Smoke inhalation causes injuries to lung airways, and, at times, alveolar inflammation also develops over approximately 24 h. The pathophysiology of parenchymal lung injuries is unknown, and it is often fatal. We hypothesized that an inflammatory stress remote from the smoke-related lung insult was required for development of alveolar injuries. Spontaneously breathing rats were exposed, head only, to smoke generated by nonflaming pyrolysis (smoldering) of Douglas fir wood (DF), polyvinylchloride (PVC), or the combination of DF+PVC. Intraperitoneal injection of sterile oyster shell glycogen 4 h before smoke inhalation was used as an extra inflammatory stimulus. Histologic examinations revealed extensive airway inflammation in all smoke-exposed groups. Glycogen peritonitis alone caused no lung injuries, and in the absence of glycogen, smoke inhalation caused neither parenchymal lung injuries, assessed by [125I]bovine serum albumin (BSA) leakage, nor neutrophil infiltration, quantified by myeloperoxidase (MPO) activity. However, in rats pretreated with glycogen and studied 24 h after exposure to smoke from burning DF+PVC, [125I]BSA permeability was increased by 232 +/- 41% (SE; n = 13), MPO activity was increased 5-fold, from 2.6 +/- 0.4 (n = 7) to 13.9 +/- 1.4 (n = 19) A460/min/g lung, and histopathologic findings included extensive pulmonary inflammation. We conclude that inhalation of certain types of smoke will trigger pulmonary injury when an inflammatory process remote from the lungs is present.