Abstract
Purpose: :
Abnormalities in corneal reepithelization caused by air pollution are not studied yet. Diesel exhaust (DE) is a mayor contributor to particular matter air pollution. The aim of the present investigation was elucidated the effect of DE on conjunctiva and corneal epithelium migration in-vitro and air pollution effects on corneal wound healing reepithelization in-vivo.
Methods: :
DE was collected in polycarbonate filters. Particles were extracted from the filters and suspension of 10, 50, 100 and 500 µg/ml of DE in maintenance medium (MM) were prepared. Cells of IOBA-NHC and HCLE cell lines were grown on multiwell plates. We performed two conditions over each monolayer: (1). 24 hs MM- wound (W)- culture with DE or (2). 24 hs DE-W-culture again DE. We measured the wound area at 0, 18 and 44 hs and calculated the percentage of migration, using Image ProPlus software. Twenty male Balb/c mice were maintained in two exposure chambers 24 h/day, 7 days/week, during 1 month. One of the chambers received ambient air at a flow rate of 50 L/min (polluted group, n:10), whereas the other (control) received filtered air (clean group, n:10). On day 21, mice were anesthetized and a 1.5-mm diameter portion of the central cornea epithelium was removed with a trephine and a scalpel. At 0, 8, 24, 32, 44 and 48 hs after wounding, the wounded areas were stained with sodium fluorescein, photographed and each epithelial defect area was quantified and analyzed.
Results: :
IOBA-NHC: In the MM-W-DE condition at 18-44 hs cell migration was decreased in a dose dependent: 0 µg/ml (24.6%-42.4%), 10 µg/ml (14%-20%), 50 µg/ml (7.3%-13.6%), 100 µg/ml (5.6%-12.6%) and 500 µg/ml (2.6%-9.7%). Instead, in the DE-W-DE condition cell migration decreased but not in a dose dependent: 0 µg/ml (24.6%-42.4%), 10 µg/ml (7.3%-13.6%), 50 µg/ml (6.3%-20.5%), 100 µg/ml (6.6%-13.5%) and 500 µg/ml (0.5%-2%). Similar results were found to HCLE. After a single manual 1.5 mm debridement wound to the cornea, wounds are completely reepithelialised at 32 hs for clean group and at 44 hs for polluted group.
Conclusions: :
IOBA-NHC and HCLE cultured in basal conditions, scraped and exposed to DE showed a decreased dose dependent migration. Despite this, the cells preincubated with DE showed a decreased migration compare to the cells in the MM-W-DE condition only at 10 and 500 µg/ml. The percentages obtained for 50 and 100 µg/ml of DE might be a combination of migration and proliferation activated at those concentration of contaminate. In vivo, air pollution delay corneal wound healing reepithelization.
Keywords: cornea: epithelium • keratitis • inflammation