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

Our plain-English summary of Intratracheal fiber glass instillation in rats: IL8 and lymphocytes levels in bronchoalveolar lavage, correlation with the histopathological findings, by B.D. Hancu, M. Pop (Clujul Medical, 2013).

The study

• Authors: B.D. Hancu, M. Pop
• Journal: Clujul Medical
• Published: 2013;86(1):43-7
• Read it: PubMed · Free full text

Abstract

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.

In plain English

This was an animal experiment on fiber glass, a man-made mineral fiber. Asbestos was not studied. The authors used 32 female Wistar rats in four groups of eight. Three groups had fiber glass placed directly into the windpipe (intratracheal instillation), at 6, 10 or 12 mg in 0.2 ml saline, 5 days a week for 10 weeks. The control group received saline only. The fibers were sized to be breathable by rats (20 µm long, 1 µm diameter). One week after the last dose, the rats were killed, their lungs rinsed (bronchoalveolar lavage) and lung tissue examined. Average IL8 levels, an inflammation signal, were 29.7, 69.5 and 103.8 pg/ml in the low, middle and high dose groups, against 14 pg/ml in controls. Lymphocyte counts in the rinse fluid fell as dose rose; controls had none. Lung damage rose with dose. The lowest dose caused slight inflammation. The highest dose caused lung fibrosis, pleural fibrosis and emphysema. Controls showed no changes. The authors concluded that IL8 levels were dose related, ran opposite to lymphocyte counts, and matched the tissue findings.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: animal experiment (intratracheal instillation in rats)
• Who was studied: 32 female Wistar rats aged 9-10 weeks at the start, in four groups of eight (three fiber glass groups and one saline control group); Iuliu Hațieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
• Exposure: Fiber glass at 6 mg, 10 mg or 12 mg per 0.2 ml saline, 5 days per week for 10 weeks. Controls received the same volume of saline. Fibers were selected to be rat respirable, 20 µm long and 1 µm in diameter.
• Main results:
  • Average IL8 levels in lavage fluid were 29.7 pg/ml in the 6 mg group, 69.5 pg/ml in the 10 mg group and 103.8 pg/ml in the 12 mg group, versus 14 pg/ml in the control group. The means are printed without a unit; the unit comes from the table they were calculated from, which reports IL8 in pg/ml. The authors described this as a direct correlation with dose.
  • Lymphocyte counts in the lavage fluid showed an inverse relationship with dose in the fiber glass groups. The control group had no lymphocytes in the lavage fluid. In the 12 mg group, counts ranged from 241 to 342.
  • Spearman rank correlation showed IL8 values rising while lymphocyte numbers fell across the fiber glass groups.
  • In the 6 mg group, tissue findings were minimal or slight inflammatory lesions (grades 1-2), including tracheitis, proliferative bronchitis and interstitial pneumonia.
  • In the 10 mg group, tissue findings were moderate to marked inflammatory lesions with discrete fibrosis.
  • In the 12 mg group, tissue findings were marked to massive lesions (grades 4, 5) with collagen proliferation, lung fibrosis, pleural fibrosis and emphysema.
  • The control group showed no histopathological changes.
• The authors' conclusion: The authors concluded that IL8 levels were dose related, had an inverse correlation with lymphocyte count in the lavage fluid, and correlated with the histopathological findings.

Topics

Medical terms in this study, explained in our Lexicon: Bronchoalveolar Lavage (BAL), Mineral Fiber, Mesothelioma, Emphysema, Fibrosis.

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