Intratracheal fiber glass instillation in rats: IL8 and lymphocytes levels in bronchoalveolar lavage, correlation with the histopathological findings

INTRODUCTION Fiberglass (FG) is the largest category of man -made mineral fibers. Many types of FG are manufactured for specific uses building insulation, air handling, and sound absorption. Because of increasing use and potential for widespread human exposure, a chronic toxicity instillation study was conducted in Wistar rats, which were found to be sensitive to the induction of mesotheliomas with another MMVF. AIM The present study is focused on the effect of fiber glass on lung through intratracheal exposure, the analysis of bronchoalveolar lavage and measurement of IL 8 levels, lymphocytes number and histopathological finding after the exposure period. MATERIAL AND METHOD Four groups of 8 female Wistar rats were included in the study. The animals were divided into three groups of 8 each, exposed to different doses of FG and one control group. The first group (1-8) was exposed to 6 mg dose/0.2 ml saline 5 days/week for 10 weeks, the second (9-16) group was exposed to 10 mg/0.2 ml saline 5 days/week 10 weeks, the third group (17-24) was exposed to 12 mg FG/0.2 ml saline solution 5 days/week 10 weeks and the control group (25-32) was exposed to the same volume of saline. The fibers had been size selected to be rat respirable. At the end of the exposure period of 10 weeks the rats were killed one week after the last exposure. Following preparation of the lungs, they were lavaged with 2x5 ml saline without massage. The lavage fluid was collected in calibrated tubes and harvested volume was recorded. Supernatant was obtained after centrifugation at 1,500 r.p.m for 5 minutes and IL8 levels and lymphocytes number were measured. RESULTS The IL8 levels were found to be dose related; the first group had values ranging from 10 to 19.8 pg/ml and the total lymphocytes number in the bronchoalveolar lavage fluid ranging from 1,500-1,900 and minimal/slight inflammatory lesions. The second group had the IL8 levels ranging between 60.4-80.4 pg/ml, lymphocytes number between 680-881 and moderate to marked inflammatory lesions. For the third group the IL8 values ranged between 88.3-113.2, the lymphocytes number ranged between 241-342 and the histopathological findings were marked and severe including emphysema, lung and pleural fibrosis. The control group had IL8 values between 10-19.4, there were no lymphocytes in the bronchoalveolar lavage and no histopathological findings. CONCLUSION These findings indicate that IL8 levels were dose related and IL8 levels have an inverse correlation with lymphocytes count in BAL, also correlated with the histopathological findings for the studied groups.