[PM2.5 inhibits the expression of occludin in human nasal mucosal epithelial cells]

Objective To investigate the effect of PM2.5 on the distribution and expression of occludin in nasal mucosal epithelial cells. Methods The normal human nasal epithelial cell line HNEpCs were stimulated with PM2.5 in vitro. The incubated cells were treated with 0, 50, 100, 200, 400, 500, 800, 1000 μg/mL of PM2.5. The suitable concentration of PM2.5 was determined according to the cell viability measured by CCK-8 assay. Then the incubated cells were treated with 200, 400, 500 μg/mL of PM2.5. The occludin expression and distribution on the levels of protein and mRNA were detected by immunofluorescence assay, Western blot analysis and real-time fluorescence quantitative PCR. Results Compared with the control group, the cell viability of HNEpCs treated with different concentrations of PM2.5 decreased after 24 and 48 hours. The cell viability was negatively correlated with PM2.5 concentrations. Compared with the control group, there was no obvious change in the cell morphology and occluding expression of the 200 μg/mL PM2.5 group. The cell morphology changed into the spindle shape in the 400 μg/mL group, and a small number of vacuoles appeared in the cell connection. After treated with 500 μg/mL PM2.5, the cell density decreased, normal cell morphology changed into irregular long spindle shape and the intercellular space was enlarged. Occludin mRNA and protein levels were down-regulated in all the groups except for the cells treated with 200 g/mL PM2.5 for 24 hours, and occludin protein expression levels were time-dependent. Conclusion PM2.5 can reduce the viability of HNEpCs in normal human nasal epithelial cell line, and reduce the mRNA and protein expression of the intercellular occludin.