Eosinophil granule proteins as a biomarker in managing asthma and allergies

In the past few decades, biomarkers have been successfully used for the diagnosis, treatment, and monitoring of disease. Taking together clinical, genetic, lifestyle, and information on relevant biomarkers, the therapy of diseases can be personalized to an individual. Several novel biomarkers have been recently reported for allergic diseases. However, to interpret the validity of biomarker data, the validation of their reliability, precision, and reproducibility is imperative. Once validated, they can be used in therapeutic product development and in clinical practice. Eosinophils are multifunctional leukocytes and major effector cells that play a crucial role in the immunological mechanisms of allergic disease. Measuring eosinophils has been the gold standard for treating and monitoring eosinophil-related diseases such as asthma, atopic dermatitis, and allergic rhinitis. However, eosinophil numbers/percentages yield little information about eosinophil activity. Eosinophil activation leads to the extracellular release of 4 granule proteins, with the most promising biomarker of the 4 being eosinophil-derived neurotoxin (EDN). EDN is more easily recovered from measuring instruments and cell surfaces than other eosinophil biomarkers because of its weaker electrical charge. EDN is known to be released from eosinophils at a greater efficiency, adding to its recoverability. It also has antiviral activity in respiratory infections associated with allergic disease development in early life (eg, respiratory syncytial virus and human rhinovirus infections in early childhood). EDN can be measured in several body fluids, including blood, urine, sputum, nasal secretions, and bronchoalveolar lavage. EDN is a stable biomarker utilized to precisely diagnose, treat, and monitor many eosinophil-related allergic diseases. This eosinophil granule protein may prove useful in precision medicine approaches and should always be considered as a useful tool for the clinician to give the best patient care possible.