Hyaluronan (hyaluronic acid) in lung lavage of asbestos-exposed humans and sheep.

The concentration of hyaluronan was measured in the bronchoalveolar lavage fluid (BALF) of 18 control subjects and 27 workers from the asbestos mills and mines of Quebec, 9 without asbestosis and 18 with asbestosis. Hyaluronan was also measured in the BALF of 9 control sheep exposed to 100 ml phosphate-buffered saline (PBS) at 10 day intervals for 39 months, and 13 sheep exposed at the same intervals to 100 mg chrysotile in 100 ml PBS for 24 months. At month 24, the asbestos-exposed sheep were classified into 3 groups: (A) 4 sheep exposed to PBS alone, (B) 4 sheep exposed to 10 mg chrysotile asbestos every 10 days, and (C) 5 sheep exposed to 100 mg chrysotile asbestos every 10 days for 15 months. The BALF hyaluronan averaged 53.9 ± 7.4 ng/ml in human controls, 67.5 ± 10.3 ng/ml in asbestos-exposed workers without asbestosis, and 206 ± 83 ng/ml in workers with asbestosis (p < 0.05 vs. normal). In the control sheep, BALF hyaluronan was 34.7 ± 6.9 ng/ml, and it was 31.5 ± 17.8 ng/ml in the low-dosage asbestos-exposed group (A), 83.0 ± 27.7 ng/ml in the intermediate-dose group (B), and 248.0 ± 134.7 ng/ml in the high-dosage group (C) (p < 0.05 vs. controls). In contrast, the release of plasminogen activator, a protease that may play a role in limiting the fibrotic process, was increased in group A, but not in groups B and C. In conclusion, BALF hyaluronan constitutes an indicator of lung interstitial tissue changes that may reflect the activity of the fibrosing alveolitis associated with chronic asbestos exposure.