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CONTEXTE : Bien que l’évaluation de l’inflammation bronchique, par expectoration induite, permette d’identifier différents phénotypes, chez les patients asthmatiques, il n’y a que peu d’informations sur le déterminant du pattern d’inflammation bronchique chez les patients présentant un asthme professionnel par sensibilisation. OBJECTIF : Déterminer si le pattern d’inflammation bronchique, déterminé par expectoration induite, permet de définir des phénotypes cliniques distincts. MÉTHODE : Cette étude multicentrique rétrospective a été réalisée auprès de 372 patients, présentant un asthme professionnel diagnostiqué par test d’exposition spécifique, qui étaient recrutés par le biais de la cohorte du groupe European network for Phenotypique of Ocupational Asthma. Chaque patient a bénéficié d’une expectoration induite avant et après test d’exposition spécifique. L’éosinophilie bronchique était définie par un pourcentage d’éosinophiles supérieur ou égal à 3 % dans l’expectoration induite, après test d’exposition spécifique, alors que la neutrophilie bronchique était définie par un pourcentage de neutrophiles supérieur ou égal à 76 %. RÉSULTATS : Au total, 268 (72 %) et 42 patients (11 %) présentaient respectivement une éosinophilie et une neutrophilie bronchique. Les analyses de régression logistique ont mis en évidence une association entre l’éosinophilie bronchique et l’exposition aux agents de haut poids moléculaire (odds ratio [OR], 1,89 ; IC 95 % 1,18–3,04), l’asthme persistant modéré (OR, 3,17 ; IC 95 %, 1,43–7,0) et l’asthme persistant sévère (OR, 2,39 ; IC 95 %, 1,06–5,43). La neutrophilie bronchique était associée à l’âge (OR pour chaque année supplémentaire, 1,04 ; IC 95 % 1,01–1,08), au genre masculin (OR, 2,83 : IC 95 %, 1,14–6,87), à l’asthme persistant léger (OR, 3,26 ; IC 95 %, 1,24–8,88), et à la dysphonie (OR, 2,83 ; IC95 %, 1,14–6,87). CONCLUSIONS : La majorité des patients avec un asthme professionnel par sensibilisation présentait une éosinophilie bron, [Phenotypes of occupational asthma defined with induced sputum after specific inhalation challenge] RATIONALE : Although the non-invasive assessment of airway inflammation through the induced sputum (IS) technique identified distinct asthma phenotypes, there is few information on the determinants of airway inflammatory pattern in sensitizer-induced occupational asthma (OA). AIM : To investigate whether the pattern of airway inflammation in IS is associated with distinct clinical phenotypes of OA. METHODS : This retrospective multicentric study was conducted among 372 patients with OA confirmed by a positive specific inhalation challenge (SIC) who were recruited in the European network for the Phenotyping of OCupational Asthma cohort (2006–2018). Each patient underwent an analysis of IS before and 24 hours after the SIC. Sputum eosinophilia and neutrophilia were defined by the presence of ≥ 3% eosinophils and ≥ 76% neutrophils in sputum samples collected after the SIC. RESULTS : In total, 268 (72%) and 42 patients (11%) exhibited sputum eosinophilia and neutrophilia, respectively. Multivariate logistic regression analysis revealed that eosinophilia was associated with exposure to a high molecular weight agent (odds ratio [OR], 1.89; 95% CI, 1.18–3.04), moderate asthma (OR, 3.17; 95% CI, 1,43–7.0) and severe asthma (OR, 2.39; 95% CI, 1.06–5.43). Sputum neutrophilia was associated with age (OR for each additional year, 1.04; 95% CI, 1.01–1.08), male gender (OR, 2.74; 95% CI, 1,21–6.8), mild asthma (OR, 3.26; 95% CI, 1.24–8.88), and dysphonia (OR, 2.83; 95% CI, 1.14–6.87). CONCLUSIONS : Sputum eosinophilia post-SIC was predominant in OA patients. Sputum eosinophilia and neutrophilia were associated with distinct clinical phenotypes of OA, especially in terms of causal agents and asthma severity.

High-molecular-weight (HMW) proteins and low-molecular-weight (LMW) chemicals can cause occupational asthma (OA) although few studies have thoroughly compared the clinical, physiological, and inflammatory patterns associated with these different types of agents. The aim of this study was to determine whether OA induced by HMW and LMW agents show distinct phenotypic profiles. Clinical and functional characteristics, and markers of airway inflammation were analyzed in an international, multicenter, retrospective cohort of subjects with OA ascertained by a positive inhalation challenge response to HMW (n=544) and LMW (n=635) agents. Multivariate logistic regression analysis showed significant associations between OA caused by HMW agents and work-related rhinitis (OR [95% CI]: 4.79 [3.28-7.12]), conjunctivitis (2.13 [1.52-2.98]), atopy (1.49 [1.09-2.05]), and early asthmatic reactions (2.86 [1.98-4.16]). By contrast, OA due to LMW agents was associated with chest tightness at work (2.22 [1.59-3.03]), daily sputum (1.69 [1.19-2.38]), and late asthmatic reactions (1.52 [1.09-2.08]). Furthermore, OA caused by HMW agents showed a higher risk of airflow limitation (1.76 [1.07-2.91]) whereas OA due to LMW agents exhibited a higher risk of severe exacerbations (1.32 [1.01-1.69]). There were no differences between the two types of agents in the baseline sputum inflammatory profiles, but OA caused by HMW agents showed higher baseline blood eosinophilia and a greater post-challenge increase in fractional nitric oxide. This large cohort study describes distinct phenotypic profiles in OA caused by HMW and LMW agents, There is a need to further explore differences in underlying pathophysiological pathways and outcome after environmental interventions. This article is protected by copyright. All rights reserved.