Tumor necrosis factor-alpha induces emphysema-like pulmonary tissue rebuilding. Changes in type II alveolar epithelial cells.

The effect of repeated doses of TNF-alpha on the histological picture of the pulmonary tissue was analyzed in the present study. Special attention was paid to the lung rebuilding processes. TNF-alpha was applied intraperitoneally for two weeks in a dose of 10 micrograms/0.5 ml PBS/24h. Morphological analysis of the pulmonary tissue was performed after 1 and 28 days following the last TNF-alpha dose. The study revealed focal pulmonary tissue rebuilding with emphysema-like changes twenty eight days following termination of TNF-alpha administration. The rebuilding processes included interalveolar septal atrophy, collagen accumulation and damage-repair changes in type II alveolar epithelial cells. It has been demonstrated that apart from the protease-antiprotease hypothesis of the lung emphysema, the inflammatory-repair hypothesis should be considered. Both hypotheses are complementary to each other and interpret the emphysema-like changes as complications of various pathological conditions of the pulmonary tissue.