Inflammatory endotype before and after specific inhalation challenge in patients with work-related asthma

Abstract

Work-related asthma comprises occupational asthma (OA) and work-exacerbated asthma (WEA). It is unknown whether the inflammatory pathways activated in OA and WEA are different. The aim of the study was to determine the inflammatory endotype in OA and WEA at diagnosis, based on Fractional Exhaled Nitric Oxide (FeNO) and type 2 (T2) or non-type 2 (non-T2) circulating biomarkers, monitored before and after Specific Inhalation Challenge (SIC). We collected data of 40 asthmatics with a diagnosis of OA (n=25) or WEA (n=15) due to various agents, confirmed by a positive or negative, respectively, SIC. All the patients had been free from corticosteroid therapy for the last 2 weeks. FeNO was measured before and 24 h after SIC. Blood samples were collected before and 7 h after SIC and sera were stored at -80°C until used. Eotaxin, IL-2, IL-3, IL-5, IL-8, IL-9, IL12p70, IL-17, IL-33, IFNγ, GM-CSF levels were assessed by Luminex xMAP Technologies. At diagnosis, OA and WEA patients did not differ in terms of age, gender, atopy, eosinophil and neutrophil count in blood, total IgE, lung function, latency and months of symptomatic exposure. FeNO levels significantly increased in OA patients after SIC (pre:62 ppb <i>vs</i> post:103 ppb) compared to WEA patients (pre:46 ppb <i>vs</i> post:52 ppb), (p=0.0098). No differences between the serum levels of cytokines in OA and WEA patients were detected neither before nor after SIC. OA and WEA subjects did not exhibit a different serum inflammatory profile before and 7 h after SIC. FeNO levels increased 24 h after SIC in OA subjects, but not in WEA subjects. However, T2 airway inflammation in OA was not associated with changes in T2 serum cytokines after SIC.