Beyond EOsinophils: proteoMICS to Identify Potential Biomarker of Organ Damage and Response to MEPOLIZUMAB in EGPA

Aim of the study is to identify potential biomarkers, through a proteomic approach, which could be used to evaluate organ damage and predict the response to mepolizumab in a cohort of patients affected by EGPA. Proteomic analyses will be performed using a proteomic platform, based on a nano-HPLC- couplet to an high resolution ESI-MS device, on three types of biological matrices: blood, saliva and sputum samples in both EGPA and severe asthmatic patients (as controls) at baseline and at different time points after starting treatment with mepolizumab, an anti-IL-5 drug, in order to cluster patients and to analyze the effect of the therapy during treatment, assessing the disease progression on three key aspects: lung function and symptoms control, vasculitis and neuropathy. Plasma analysis will provide an overview of quantitative/qualitative proteomic variations at systemic level after drug administration; however, a less invasive procedure is often sufficient and would improve trial recruitment. On this regard, saliva is a biological fluid well suitable to be used in proteomic investigations for suggestion of potential disease biomarkers and includes various potential advantages compared with blood sample collection such as lower overall cost, lower infection risk, increased patient convenience, acceptability, compliance and uptake. Moreover, the protein composition of the human saliva includes both specific proteins of the oral cavity and proteins common to other tissues and bodily fluids, so saliva prognostic and diagnostic role is particularly interesting. Consequently, the plan is to compare the proteomic results of the non-invasive saliva testing to that of blood examination. These data may be a further step to untangle the mechanisms of the disease and to characterize treatment's response, in the contest of a phenotype/endotype asthma management.