Asian Sand Dust Enhances the Inflammatory Response and Mucin Gene Expression in the Middle Ear

OBJECTIVES: Asia sand dust (ASD) is known to cause various human diseases including respiratory infection. The aim of this study was to examine the effect of ASD on inflammatory response in human middle ear epithelial cells (HMEECs) in vitro and in vivo. METHODS: Cell viability was assessed using the cell counting kit-8 assay. The mRNA levels of various genes including COX-2, TNF-a, MUC 5AC, MUC 5B, TP53, BAX, BCL-2, NOX4, and SOD1 were analyzed using semiquantitative realtime polymerase chain reaction. COX-2 protein levels were determined by western blot analysis. Sprague Dawley rats were used for in vivo investigations of inflammatory reactions in the middle ear epithelium as a result of ASD injection. RESULTS: We observed dose-dependent decrease in HMEEC viability. ASD exposure significantly increased COX-2, TNF-a, MUC5AC, and MUC5B mRNA expression. Also, ASD affected the mRNA levels of apoptosis- and oxidative stress-related genes. Western blot analysis revealed a dose-dependent increase in COX-2 production. Animal studies also demonstrated an ASD-induced inflammatory response in the middle ear epithelium. CONCLUSION: Environmental ASD exposure can result in the development of otitis media.

Microarray Analysis of Gene Expression Alteration in Human Middle Ear Epithelial Cells Induced by Asian Sand Dust

OBJECTIVES: The primary aim of this study is to evaluate the gene expression profile of Asian sand dust (ASD)-treated human middle ear epithelial cell (HMEEC) using microarray analysis. METHODS: The HMEEC was treated with ASD (400 microg/mL) and total RNA was extracted for microarray analysis. Molecular pathways among differentially expressed genes were further analyzed. For selected genes, the changes in gene expression were confirmed by real-time polymerase chain reaction. RESULTS: A total of 1,274 genes were differentially expressed by ASD. Among them, 1,138 genes were 2 folds up-regulated, whereas 136 genes were 2 folds down-regulated. Up-regulated genes were mainly involved in cellular processes, including apoptosis, cell differentiation, and cell proliferation. Down-regulated genes affected cellular processes, including apoptosis, cell cycle, cell differentiation, and cell proliferation. The 10 genes including ADM, CCL5, EDN1, EGR1, FOS, GHRL, JUN, SOCS3, TNF, and TNFSF10 were identified as main modulators in up-regulated genes. A total of 11 genes including CSF3, DKK1, FOSL1, FST, TERT, MMP13, PTHLH, SPRY2, TGFBR2, THBS1, and TIMP1 acted as main components of pathway associated with 2-fold down regulated genes. CONCLUSION: We identified the differentially expressed genes in ASD-treated HMEEC. Our work indicates that air pollutant like ASD, may play an important role in the pathogenesis of otitis media.