SNOR and wheeze: the asthma enzyme?

Conventionally, asthma is defined as involving both airway inflammation and airway smooth muscle hyper-responsiveness. However, Que and coworkers have recently uncoupled these concepts, showing that mice lacking an S-nitrosothiol reductase have allergen-induced airway inflammation but do not have airway hyper-responsiveness. These data are consistent with recent clinical evidence that: (i) S-nitrosothiol signaling is abnormal in human asthma, (ii) nitric oxide in exhaled air might be only a biomarker for the metabolism of more physiologically relevant nitrogen oxides and (iii) the biochemical response to airway inflammation is central to asthma pathophysiology.