Abstract
This study was aimed at investigating the effects of placenta-derived mesenchymal stem cells (PL-MSCs) on particulate matter- (PM-) exposed human middle ear epithelial cells (HMEECs). HMEECs were treated with 300 μg/ml PM for 24 hours. The PL-MSCs were cocultured with PM-treated HMEECs. Cells were harvested on days 0, 1, and 4, and the expression of the inflammatory genes TNFα, COX2, IL1β, IL6, and MUC5B in HMEECs and anti-inflammatory genes PTGES, TGFβ, and VEGF in PL-MSCs was examined by qRT-PCR. The culture media were collected to measure the secreted PGE2 level using an enzyme-linked immunosorbent assay. The mRNA expression of TNFα, COX2, IL1β, IL6, and MUC5B in HMEECs increased following PM treatment. PM-treated HMEECs cocultured with PL-MSCs showed alleviated inflammatory reactions represented by lower mRNA expression levels of MUC5B, TNFα, IL1β, and IL6 compared to monocultured PM-treated HMEECs. The mRNA expression levels of PGE2, TGFβ, and VEGF were elevated in cocultured PL-MSCs compared to those of control PL-MSCs. The medium of PM-treated HMEECs cocultured with PL-MSCs exhibited increased PGE2 levels. The increased inflammatory response in PM-treated HMEECs was reversed using PL-MSCs. The PGE2, TGFβ, and VEGF were the mediators of the anti-inflammatory effects of PL-MSCs.
Highlights
Particulate matter (PM) is a major airway pollutant that has increased in recent years
The mRNA expression of TNFα, interleukin 6 (IL6), mucin 5B (MUC5B), IL1β, and cyclooxygenase 2 (COX2) was differently increased in human middle ear epithelial cells (HMEECs) following incubation with 300 μg/ml PM at different time points (Figure 3)
PM exposure decreased the proliferation of HMEECs
Summary
Particulate matter (PM) is a major airway pollutant that has increased in recent years. The middle ear is connected to the upper airway via the Eustachian tube. PM could enter directly into middle ear epithelial cells and cause injury. The blood supply of the middle ear epithelium could be a route for PM-induced effects. Prior studies have demonstrated inflammation in human middle ear epithelial cells (HMEECs) following PM exposure [5, 6]. The 24 hours of diesel exhaust particle (DEP) increased the mucinproducing gene of MUC5AC in HMEECs [7]. Few studies have explored the temporal changes in PM effects on the middle ear. The anti-inflammatory response of stem cells following PM exposure in the middle ear has not been well-described
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