Levels of alpha-elastin and of desmosine as indexes of elastase-induced lung injury in rats

Two markers of elastin degradation, alpha-elastin and desmosine levels, were measured in sera from rats after single tracheal instillations of porcine pancreatic elastase (PPE). Biochemical and pathophysiological changes in the lung were also studied. Male Wistar rats were divided into three groups. The control group received one intratracheal dose of saline (0.3 ml). The PPE 60 group received one intratracheal dose of 60 U of PPE. The PPE 120 group received one intratracheal dose of 120 of PPE. Blood samples were collected 0, 1, 3, 5, 7, 14, 28, and 56 days after the intervention, and levels of alpha-elastin and desmosine were measured by enzyme-linked immunosorbent assay. At the end of the study (day 56), lung volumes and static pressure-volume curves were measured by body pletysmography. Then the rats were killed and the mean linear intercept was measured as defined by Thurlbeck. The serum alpha-elastin level in the PPE 120 group on day 7 was significantly higher (p < 0.05) than those in other groups. Desmosine values on day 1 in the PPE 60 group and on days 1 and 7 in the PPE 120 group were significantly higher (p < 0.05) than those in the control group. Functional and morphometric analyses revealed that the PPE 120 group had more emphysematous changes than the control group (p < 0.01) and more than the PPE 60 group (p < 0.05). These results suggest that levels of alpha-elastin and of desmosine reflect changes that occur in the early stages of lung injury, and that these changes are related to abnormalities found in rat lungs on day 56.