TY - JOUR T1 - Is it really time to look at distal airways to improve asthma phenotyping and treatment? JF - European Respiratory Journal JO - Eur Respir J SP - 1252 LP - 1254 DO - 10.1183/09031936.00067711 VL - 38 IS - 6 AU - T. Perez Y1 - 2011/12/01 UR - http://erj.ersjournals.com/content/38/6/1252.abstract N2 - In 2011, severe asthma and/or insufficient control of disease remain major challenges for the pulmonologist [1]. Small airway involvement has been demonstrated by a number of studies, particularly in fatal, severe or poorly controlled asthma, and may be a potential target to improve treatment and asthma outcomes [2–5]. Although inhaled corticosteroids (ICSs) remain the cornerstone of asthma treatment, there is a continuing debate on the potential benefit of small-particle formulations. In this context, the recent study by Cohen et al. [6] clearly adds new data to this controversial topic.It is the first to compare airway hyperresponsiveness (AHR) to small-particle adenosine monophosphate (AMP) with large and standard particles in a reasonable sample of mild-to-moderate asthmatics. In addition, the impact of small- (ciclesonide) versus large-particle (fluticasone) ICS formulations was compared at 4 weeks using the same original AMP challenges, exhaled NO and spirometry. Unfortunately, asthma control was not assessed. The results clearly indicate that small-particle ICSs may improve corresponding AHR, but other functional outcomes were surprisingly not correlated with this benefit. Such an approach targeting evaluation and treatment of small airways raises a series of questions.AHR is a complex phenomenon in asthma and the contribution of small airways to this hyperresponsiveness is poorly characterised, particularly regarding its variable inflammatory component. Distal airway inflammation has been demonstrated by a number of histopathological studies using lung resection specimens or transbronchial biopsies [2]. Taken together, these data suggest an important role for distal airway inflammation in severe asthma.Consistent with these histopathological findings, direct measurement of distal airway resistance showed that they accounted for up to 50–90% of total airflow resistance in asthma [7], implying that distal airways were the main site of airflow obstruction. Early experimental and theoretical models … ER -