Objective To explore the effects of prolonged inhalation of Aspergillus fumigatus ( Af)spores on epithelial cell injury and expression of epidermal growth factor receptor( EGFR) in airways of asthmatic rats. Methods 64 male Wistar rats were randomly divided into 8 groups, ie. chronic asthma group ( group A) , chronic asthma plus Af spores inhalation for 1 week ( group B) , 3 weeks ( group C) and 5 weeks ( group D) , chronic asthma plus saline inhalation for 5 weeks ( group E) , OVA-sensitized and salinechallenged group ( group F) , and OVA-sensitized and saline-challenged plus Af spores inhalation for 5 weeks ( group G) ( each n =8) . The airway resistance ( Raw) and change of Raw after acetylcholine provocation were detected using a computerized system. The concentrations of epidermal growth factor ( EGF) andtransforming growth factor alpha( TGF-α) in BALF were measured by ELISA. The extents of epithelial cell injury and goblet cell hyperplasia were evaluated on hematoxylin and eosin-stained( HE) and periodic acidschiff ( PAS) stained lung sections. The expression of EGFR in airway epithelia was demonstrated byimmunohistochemistry, and the level of EGFR protein in the rat lung tissues was measured by western blot.Results The concentration of EGF( pg/mL) ( 51. 72 ±8. 54, 68. 12 ±7. 85, 86. 24 ±9. 12, respectively)and TGF-α( pg/mL) ( 55. 26 ±9. 30, 75. 58 ±11. 56, 96. 75 ±14. 66, respectively) , detached/ inner perimeter of epithelium( % ) ( 11. 25 ±3. 12, 26. 45 ±5. 56, 28. 50 ±7. 50, respectively) , the ratio of goblet cell area to epithelial cell area ( % ) ( 16. 42 ±5. 24, 22. 64 ±6. 82, 36. 38 ±9. 21, respectively) , the integrated optical density ( IOD) of EGFR positive stain in airway epithelial cells ( 82 ±15,120 ±19, 165 ±21, respectively) , and the EGFR protein levels in lung tissues ( 0. 91 ±0. 26, 1. 61 ±0. 52, 2. 52 ±0. 78,respectively) in group B, C, and D were higher than those in group A, E, F and G( P lt; 0. 05 or P lt;0. 01) .The change rates of Raw( % ) ( 61. 91 ±5. 26, 84. 69 ±6. 38) in group C and D were higher than those in group A, E, F and G ( P lt; 0. 05 or P lt;0. 01) . The IOD of EGFR was positively correlated with detached/inner perimeter of epithelium( % ) and the ratio of goblet cell area to epithelial cell area( % ) ( r = 0. 692,P lt;0. 01; r = 0. 657, P lt; 0. 01, respectively) . Conclusion Prolonged inhalation of Aspergillus fumigatus spores can aggravate airway epithelial cell injury, up-regulate the expression of EGFR in airway epithelial cell and induce goblet cell hyperplasia, thus increase the airway responsiveness in rats with chronic asthma.
Objective Respiratory syncytial virus ( RSV) is a primary cause of lower respiratory tract infections in children, and is also the cause for the development of asthma primarily in infants. However,the immunological mechanisms by which RSV enhances allergic sensitization and asthma remain unclear. The aimof this study was to examine the influence of RSV-infected airway epithelial cells on the activation and functions of rat myeloid dendritic cells ( mDCs) . Methods Rat airway epithelial cells ( RAECs) were infected by RSV. Then RSV-infected RAECs were co-cultured with rat mDCs, and the expression of cytokine and maturation markers on mDCs were examined by real time PCR and flow cytometry. To confirm this functional mDC maturation, allergenic mixed lymphocyte reaction ( MLR) were performed. Results Wefound that functional maturation of mDCs was induced by RSV-treated RAECs, as shown by their enhanced levels of OX40L and thymus- and activation-regulated chemokine ( TARC) mRNAs, which increased the expressions of major histocompatibility complex II ( MHCII) and CD86 costimulatorymolecules and promotedT-cell proliferation in mixed lymphocyte reactions. Conclusion Our results suggest that RSV-infected epithelial cells promote the maturation of mDCs that might support Th2 cell polarization and contribute to the pathogenesis of asthma.