Purpose:
Epidemiological studies have demonstrated adverse health effects of environmental air pollution. Diesel exhaust (DE) is known to be the major contributor to the total amount of particulate matter. Previously, our group found a correlation between air pollution exposure and conjunctival goblet cells hyperplasia. The aim of the present investigation was to elucidate the involvement of the epidermal growth factor receptor (EGFR) in the conjunctival epithelium response to DE in-vitro.
Methods:
DE was collected in polycarbonate filters and were extracted from the filters using sonication in distilled water. A suspension with 50 µg/ml concentration of DE was prepared. Cells of a normal human conjunctival epithelium cell line (IOBA-NHC) were grown on multiwell plates and switched to a maintenance medium for 24 hours before treatment. Cells were exposed to 1 ml of DE suspension (50µg/ml) for 18 hours and a control group was cultured under the same conditions. Cells were trypsin harversted and a single cell suspension, was 0.2% PFA fixed, PBS washed and incubated with rabbit anti-EGFR antibody. After that, cells were PBS washed and incubated with an anti-rabbit Alexa488. Flow cytometric analysis was carried out (FACSCalibur, BD). Mean fluorescence intensity of lineal distribution was calculated and results were expressed as increments relative to the controls using FCS Express V3.
Results:
FACS analysis of IOBA-NHC cells incubated for 18 hours with 50 µg/ml DE showed that its fluorescence intensity (35.23 median; 228 peak value) increased when compared with control IOBA-NHC at same condition without DE incubation (22.67median; 170 peak value)
Conclusions:
IOBA-NHC cells exposed to DE (50 µg/ml) showed enhanced EGFR expression. The present finding suggest a key role of EGFR pathways in the epithelial conjunctival response to diesel exhaust and could be related with conjunctival mucin production and goblet cell hyperplasia.
Keywords: conjunctivitis • ocular irritants • cornea: tears/tear film/dry eye