Effect of aluminum inhalation on alveolar phospholipid profiles in experimental silicosis

In the sheep tracheal lobe model of silicosis, we have recently reported that total phospholipid, lecithin, and phosphatidylglycerol levels were elevated in lung lavage. To investigate further this observation, we obtained complete phospholipid profiles of lung lavage in 10 sheep exposed to saline only (Sa group), 10 sheep exposed to aluminum lactate inhalation only (Al group), 10 sheep exposed to 100 mg Minusil-5 in saline followed by monthly saline inhalation (Si group), and 10 sheep exposed to 100 mg Minusil-5 in saline followed by monthly aluminum lactate inhalation (Si-Al group). The following phospholipid components were measured: total phospholipids, phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylcholine, disaturated phosphatidylcholine, sphingomyelin, and lyso-phosphatidylcholine. All values were comparable in the Sa group, Al group, and Si-Al group. In the Si group, there was a significant increase in total phospholipid to approximately 200% of the control values. The phospholipid profile of this group demonstrated an increase in all of the phospholipid components with some enrichment of the fraction of PG, PE, and PI. We concluded that lung exposure to silica dust significantly increases the concentration of phospholipids in the alveoli. This increase is of a large spectrum of alveolar phospholipids and is completely suppressed by aluminum lactate inhalation.