Analysis of pulmonary surfactant by Fourier-transform infrared spectroscopy following exposure to Stachybotrys chartarum (atra) spores

Lung cells are among the first tissues of the body to be exposed to air-bor ne environmental contaminants. Consequently the function of these cells may be altered before other cells are affected. As gas exchange takes place in the lungs, changes in cellular function may have serious implications for the processes of oxygen uptake and carbon dioxide elimination. In order for these processes to occur, the lung must maintain a high degree of expandab ility. This latter function is accomplished in part by the pulmonary surfac tant which is synthesized and released by alveolar type II cells. Earlier s tudies have shown that exposure to gas phase materials such as smoke or org anic solvents can alter the composition and function of the surfactant. The present study examines the ability of highly toxigenic mold spores to alte r surfactant composition. Stachybotrys chartarum spores suspended in saline were instilled into mouse trachea as described earlier. After 24 h, the lu ngs were lavaged and the different processing stages of surfactant isolated by repeated centrifugation. Intracellular surfactant was isolated from the homogenized lung tissue by centrifugation on a discontinuous sucrose gradi ent. Samples were extracted into chloroform-methanol, dried and analyzed by Fourier-Transform infrared spectroscopy (FTIR). Exposure to S. chartarum i nduced an overall reduction of phospholipid among the three surfactant subf ractions. The intermediate and spent surfactant fractions in particular wer e reduced to about half of the values observed in the saline-treated group. The relative distribution of phospholipid was also altered by spore exposu re. Within the intracellular surfactant pool, higher levels of phospholipid were detected after spore exposure. In addition, changes were observed in the nature of the phospholipids. In particular strong intramolecular hydrog en bonding, together with other changes, suggested that spore exposure was associated with absence of an acyl chain esterified on the glycerol backbon e, resulting in elevated levels of lysophospholipid in the samples. This st udy shows that mold spores and their products induce changes in regulation of both secretion and synthesis of surfactant, as well as alterations in th e pattern of phospholipid targeting to the pulmonary surfactant pools. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.