AQP5 and asthma: In addition to mucous hyper-secretion, another potential mechanism by which AQP5 may lead to lung function loss in subjects with COPD includes a predisposition to airway reactivity as aqp5 −/− mice have been shown to be hyperresponsive to bronchoconstriction by cholinergic stimulation.[30] Increased airway reactivity characterizes both asthma and COPD and has been previously associated with longitudinal changes in lung function in the LHS cohort.[14]