Exosomes and inflammatory biomarkers: potential tools for the study of heterogeneity in asthmatic inflammation

Asthma is a chronic inflammatory airway disease, with a global prevalence of 5-10%, that affects about 339 million people worldwide. The severity of asthma is variable, and the most severe cases are often further complicated by various comorbidities, such as chronic rhinosinusitis with nasal polyps (CRSwNP). Severe asthma is characterized by persistent symptoms and/or frequent exacerbations, despite treatment with high dosage therapies or continuous or frequent use of corticosteroids. Approximately 50% of people with severe asthma are uncontrolled: the majority of these patients have evidence of type 2 (T2) inflammation and are eligible for biologic therapies directed against specific T2 inflammatory mediators (e.g. interleukin [IL]‐5, IL‐4/IL‐13, and immunoglobulin [Ig]E). Given that there is a specific phenotype and an underlying endotype for each asthma patient, the use of clustering methods (phenotypes and endotypes) and the emergence of targeted molecular-based therapies have rapidly advanced both the concept of, and the approach to, asthma. The present project is aimed at analyzing inflammation molecular profiles in patients with severe asthma, by identifying specific features in terms of proteomic expression, in particular in terms of exosomes, which can be considered as part of an intercellular cross-talking like a “shuttle system” for biological communication. Analyzing the molecular and inflammatory profile of patients with severe asthma and observing that 8 out of 13 patients were affected by CRSwNP, we decided to investigate what happens from a molecular and inflammatory point of view in patients who present this phenotype in non-severe asthma. Therefore, we enrolled a total of 22 asthmatic patients, 13 of whom were affected by severe asthma, and 9 who were affected by non-severe asthma + polyps. Moreover, considering that the inflammatory process underlying asthma is coordinated by a cytokine network, we conducted an analysis of the cytokines expressed in the enrolled patients, identifying possible inflammatory and molecular differences. Our data on cytokine analysis were very interesting and reported much information that was in concordance with data reported in literature. Characterization of circulating extracellular vesicles (EVs) in enrolled patients and tracking of their cellular origin through a standardized flow cytometric assay, allowed the simultaneous evaluation of 37 antigens expressed on EV surfaces. Analysis of the various surface clusters of differentiation presented by the exosomes reported that the main origin cells of exosomes in the enrolled patients, are represented by platelets, eosinophils and endothelial cells. The results we obtained in the enrolled patients allowed us to understand how every phenotype is associated with a variety of underlying distinct molecular characteristics and how "individual variability" is the key to a clinical, diagnostic and therapeutic approach aimed at precision medicine in chronic inflammatory diseases, such as severe asthma.