Montelukast Reduces Serum Levels of Eosinophil-Derived Neurotoxin in Preschool Asthma

Kim, Chang-Keun; Callaway, Zak; Park, Jin-Sung; Nishimori, Hisashi; Ogino, Tikatoshi; Nagao, Mizuho; Fujisawa, Takao

Asthma is a heterogeneous disease with many phenotypes. The recognition of a high EDN/ HDM-sensitive phenotype that exhibits a favorable response to standard asthma treatments is important. Of the 100 patients screened for eligibility, nearly half (43%) were found to be of this phenotype, which is considerable. The elevated levels of EDN and other eosinophil degranulation products found in symptomatic asthma would suggest airway inflammation is characterized not only by an increase in the number of eosinophils, but also an increase in airway eosinophil degranulation. 16 Therefore, it has been suggested that the secretory activity of eosinophils -a combination of concentration of eosinophils and their propensity to release degranulation products -may be a key marker for disease activity and is more accurately assessed by eosinophil degranulation products such as EDN. 17 EDN is released almost exclusively by eosinophils 18 ; therefore, any change in EDN levels would be a direct reflection of changes in eosinophilic inflammation. Significant changes in EDN levels between disease phases have been noted in previous studies. 12, 19 EDN may therefore be useful in predicting therapeutic outcomes and is a welcome addition to a clinician's ability to effectively treat and monitor asthma. This was further demonstrated in our study as montelukast treatment significantly reduced elevated EDN levels in the MONT group, which has also been shown in other asthma studies 12 and even in patients with post-RSV bronchiolitis recurrent wheeze. 20 Among the subjects excluded from the main study group (OBS group), the subgroup with no HDM sensitivity but elevated EDN experienced a reduction in their EDN levels as well.