Diagnostic and Prognostic Values of Eosinophil Derived Neurotoxin in Pediatric Patients with Allergic Respiratory Diseases

Abstract Background Asthma is a heterogeneous disease, usually characterized by chronic airway inflammation. It is defined by the history of respiratory symptoms such as wheeze, shortness of breath, chest tightness and cough that vary over time and in intensity, together with variable expiratory airflow limitation. In bronchial asthma (BA), the levels of eosinophils are elevated both in the airways and in the blood and they are correlated to asthma severity and control. Activated eosinophils release eosinophil derived neurotoxin (EDN), eosinophil cationic protein (ECP), major basic protein (MBP), eosinophil peroxidase (EPO), and newly developed major basic protein 2 (MBP2). EDN has RNase with broad anti-viral and anti-bacterial activity that may also promote further leukocyte activation and is implicated in the pathophysiology of asthma. Objective The aim of the work is to assess the diagnostic and prognostic value of serum EDN levels via ELISA in pediatric patients with BA and preschool wheezes in relation to their clinical and laboratory parameters particularly absolute eosinophilic counts. Patients and Methods This is a case control study that had been conducted on a stratified random sample of 90 subjects who were seen in Pediatric Allergy, Immunology and Rheumatology unit, and Clinical Pathology Immunology Laboratory Ain Shams university Hospitals, in the period between June 2022 to November 2022, divided as 30 patients with BA, 30 patients with preschool wheezes and 30 age and sex matched healthy subjects. Results The comparison between the studied groups revealed the presence of statistically significant increase in percent and absolute count of eosinophils among the cases group compared with the controls (P value<0.001). There was a statistically significant increase in serum EDN among the cases group, preschool wheezers and asthmatic patients compared with the controls (17.96 ± 4.95 ng/ml vs. 5.52 ± 1.4 ng/ml), (16.97 ± 4.24 ng/ml vs. 5.14 ± 1.39 ng/ml) and (18.95 ± 5.47 ng/ml vs. 5.89 ± 1.35 ng/ml) (P value<0.001) respectively. Elevated EDN level has been linked to eosinophilia, Th2-mediated inflammation and type 2 airway inflammations as well as increased eosinophil extracellular traps that promoted the degranulation of eosinophils. Conclusion EDN is a good biomarker for eosinophilic inflammation including bronchial asthma and preschool wheezes and may be useful as a screening tool. For prediction of allergic respiratory diseases (asthmatic and school wheezers), the best cutoff value is > 7.8 with sensitivity =100% and specificity =96.67%.