Airway smooth muscle dynamics: a common pathway of airway obstruction in asthma.
An SS., Bai TR., Bates JHT., Black JL., Brown RH., Brusasco V., Chitano P., Deng L., Dowell M., Eidelman DH., Fabry B., Fairbank NJ., Ford LE., Fredberg JJ., Gerthoffer WT., Gilbert SH., Gosens R., Gunst SJ., Halayko AJ., Ingram RH., Irvin CG., James AL., Janssen LJ., King GG., Knight DA., Lauzon AM., Lakser OJ., Ludwig MS., Lutchen KR., Maksym GN., Martin JG., Mauad T., McParland BE., Mijailovich SM., Mitchell HW., Mitchell RW., Mitzner W., Murphy TM., Paré PD., Pellegrino R., Sanderson MJ., Schellenberg RR., Seow CY., Silveira PSP., Smith PG., Solway J., Stephens NL., Sterk PJ., Stewart AG., Tang DD., Tepper RS., Tran T., Wang L.
Excessive airway obstruction is the cause of symptoms and abnormal lung function in asthma. As airway smooth muscle (ASM) is the effecter controlling airway calibre, it is suspected that dysfunction of ASM contributes to the pathophysiology of asthma. However, the precise role of ASM in the series of events leading to asthmatic symptoms is not clear. It is not certain whether, in asthma, there is a change in the intrinsic properties of ASM, a change in the structure and mechanical properties of the noncontractile components of the airway wall, or a change in the interdependence of the airway wall with the surrounding lung parenchyma. All these potential changes could result from acute or chronic airway inflammation and associated tissue repair and remodelling. Anti-inflammatory therapy, however, does not "cure" asthma, and airway hyperresponsiveness can persist in asthmatics, even in the absence of airway inflammation. This is perhaps because the therapy does not directly address a fundamental abnormality of asthma, that of exaggerated airway narrowing due to excessive shortening of ASM. In the present study, a central role for airway smooth muscle in the pathogenesis of airway hyperresponsiveness in asthma is explored.