Study On Aquaporin-5 Expression In The Human Bronchial Epithelium Cells And BALB/c Mice Airways And Its Correlation To Asthma

Bronchial asthma is a kind of common airway inflammatory diseases, and can beclinically divided into immediate asthmatic response (IAR) and late asthmatic response(LAR). Pathological study demonstrated that airway epithelium goblet cells metaplasia, seenin the IAR, could result in mucin hypersecretion to form mucin clogs which caused severeairway obstruction and respiratory failure, which is a major life-threatening factor forasthma patients. IL-4 and TNF-α have been reported to upregulate the mucin geneexpression of airway epithelium cells and promote mucin hypersecretion. Formation ofmucin clogs in airway and hyperventilation may increase airway surface tension and osmoticpressure of surface liquid, both of which can result in the increase of airway responsiveness.Aquaporin (AQP) is a group of membrane proteins specially relating to water moleculestransmission to and fro cells. AQP5 localizes in the apical membrane of the columnepithelium cells in the mammalian upper airway, trachea, main bronchus till bronchioles,and is also abundant in the apical membrane of glandular cells of subepithelium glands andtype I alveolar epithelium. It has been proved that AQP5 gene knockout mice showed higherairway responsiveness, AQP5 expression in the mice infected by viruses decreasedsignificantly, while TNF-α downregulated its expression in the mice alveolar epithelium celllines. There is no report about AQP expression in asthma till now. In order to furtherelucidate the mechanism of asthma, The AQP5 expression were studied on BALB/casthmatic mice and hBECs with a variety of methods including cell culture,immunihistochemistry and molecular biology and treatments with IL-4, TNF-α andglucosteroids to explore the possible mechanism of AQP5 expression changes. It was foundthat the expression of AQP5 mRNA and protein decreased in both airway and lung tissueunder asthmatic conditions, and either IL-4 or TNF-α was able to downregulate theexpression while dexamethasone upregulated its expression. The results suggest that AQP5may be involved in the pathogenic mechanism of asthma, by mediating the role ofinflammatory mediators in asthma and the therapeutic role of dexamethasone, whichdevelops a new area of further study on elucidating the pathogenesis of asthma. - 5 -Part I Expression of AQP5 in human bronchial epithelium cells and BALB/c miceairways Objective: To establish the primary culture methods and observe the biologicalbehaviors of human bronchial epithelium cells (hBECs) by fiberobronchoscopic brushingsand tissue planting. To observe AQP5 location in the hBECs and BALB/c mice airways.Methods: hBECs were collected by fiberobronchoscopic brushings or human surgicalsamples, and then were cultured and passaged in serum-free bronchial epithelium growthmedium (BEGM). The biological features of the cultured cells were observed and identifiedby reverse phase contrast microscopy, trypan blue staining,HE and AB-PAS staining,chromosome analysis and pan-cytokeratin immunohistochemistry. AQP5 expression in themice airways and the cells was detected by immunohistochemistry. Results: 1.The cellsacquired through bronchoscopic brushings consisted of epithelium cells without fibroblastscontamination, the number and viability being 1~2×106 and about 60% respectively. Thecells can live up to 7~8 passages. The mean number of epithelium cells produced by onelobar bronchus specimen with 2cm in length could reach 1.5×107, with >90% viability. Thedoubling time of hBECs was 49.6h according to the growth curve, which was intimatelyrelated to the seeding intensity. The cells displayed an irregular cobblestone shape, andexpressed cytokeratin. The cells with positive AB-PAS staining, indicating goblet cells,occupied about 20.82%±13%. The chromosome variations were not detected in the 1~4passages. 2.AQP5 expressed in the column epithelium cells of airway from trachea toproximate extrapulmonary bronchioles and...