Targeting eosinophils in chronic respiratory diseases using nanotechnology-based drug delivery.

Asthma, COPD, COVID-19, EGPA, Lung cancer, and Pneumonia are major chronic respiratory diseases (or CRDs) affecting millions worldwide and account for substantial morbidity and mortality. These CRDs are irreversible diseases that affect different parts of the respiratory system, imposing a considerable burden on different socio-economic classes. All these CRDs have been linked to increased eosinophils in the lungs. Eosinophils are essential immune mediators that contribute to tissue homeostasis and the pathophysiology of various diseases. Interestingly, elevated eosinophil level is associated with cellular processes that regulate airway hyperresponsiveness, airway remodeling, mucus hypersecretion, and inflammation in the lung. Therefore, eosinophil is considered the therapeutic target in eosinophil-mediated lung diseases. Although, conventional medicines like antibiotics, anti-inflammatory drugs, and bronchodilators are available to prevent CRDs. But the development of resistance to these therapeutic agents after long-term usage remains a challenge. However, progressive development in nanotechnology has unveiled the targeted nanocarrier approach that can significantly improve the pharmacokinetics of a therapeutic drug. The potential of the nanocarrier system can be specifically targeted on eosinophils and their associated components to obtain promising results in the pharmacotherapy of CRDs. This review intends to provide knowledge about eosinophils and their role in CRDs. Moreover, it also discusses nanocarrier drug delivery systems for the targeted treatment of CRDs.