Increased expression of aquaporin 5 in bronchial glands of smokers with or without COPD

RATIONALE: Previous studies suggest that smoking causes a decreased expression of aquaporin 5 (AQP5) in bronchial submucosal glands of chronic obstructive pulmonary disease (COPD) patients and this is associated with an increased expression of the mucin MUC5AC (Acta Pharmacol Sin 2007;28:1166-74). We have previously demonstrated increased MUC5AC expression in COPD bronchial mucous glands (Histopathology 2009;55:321-31). AIM and METHODS: The aim of our study was to investigate by immunohistochemistry the expression of AQP5 in formalin-fixed paraffin-embedded bronchial rings, obtained during lung resection surgery, from 10 age-matched non-smokers subjects, 29 smokers with normal lung function and 27 smokers with COPD. RESULTS: The percentage (%) of AQP5+ve mucous gland cells area on total mucous gland cells area was significantly decreased in non-smokers compared to smokers with or without COPD [median (range) 28.0 (9.0-47.0) vs 47.0 (8.0-64.0) vs 45.5 (14.0-65.0)% p<0.05]. CONCLUSION: These data suggest that AQP5 is not critical for the increased expession of MUC5AC seen in the bronchial mucous glands of COPD patients.