Effect of Mepolizumab on Severe Eosinophilic Asthma

Two parts: A:Case-control study including 15 healthy adult donors and 15 severe adult eosinophilic asthmatics selected for treatment with mepolizumab. B: A longitudinal cohort study,where the same patients once on mepolizumab treatment are followed over time (0, 4, 16 and 32 weeks). SCOPE: response to mepolizumab in severe adult eosinophilic asthma. INCLUSION CRITERIA: Male or female, 18-75 years-old, with severe eosinophilic asthma. EXCLUSION CRITERIA: Smoking history, recent exacerbations, other pulmonary or systemic disease with eosinophilia, malignancy, pregnancy, obesity (BMI \>35). OBJECTIVES: General objective: Discovery of predictive/prognostic biomarkers of response to mepolizumab using flow cytometry, transcriptomic, and proteomic technologies. OTHER OBJECTIVES: 1.-To identify changes in surface markers of eosinophils and eosinophil subpopulations in response to treatment with mepolizumab using flow cytometry techniques. 2.-Transcriptomic analysis to identify mRNAs within the eosinophil transcriptome displaying enhanced or reduced levels in response to treatment with mepolizumab.3.-Proteomic profiling to identify proteins with differential abundance within the eosinophils in response to treatment with mepolizumab.4.-Check whether late-onset severe eosinophilic asthmatics display elevated levels of IGF-1, IGF-BP3, IGF-ALS in serum samples, if the response of mepolizumab depends on the levels of this markers, and if treatment with this biological reduces the concentration in serum of these IGF-family members. 5.-Identify proteins with differential abundance within the deep serum proteome of patients with SEA in response to treatment with mepolizumab by means of non-targeted proteomic analysis. MEASUREMENTS: Flow cytometry assays with multimarker panels 1 (regulatory), 2 (activation), and 3 eosinophil subsets. Clinical, hematological, biochemical and flow cytometry data generated at times T4, T16 and T32. Total RNA extraction from eosinophil lysates, assay of quality and quantity of RNA, and storage at -80ºC. Evaluation of the levels of 770 human protein-coding mRNAs linked to the recruitment, activation, and effector functions of myeloid cells by means of a direct multiplexed molecular measurement platform named nCounter® NanoString) in combination with a pre-made "nCounter® Human Myeloid Innate Immunity Panel (v2)". Perform retrotranscription and qPCR analyses of those mRNAs in eosinophils displaying the greatest abundance changes in response to mepolizumab treatment according to the nCounter® study. In addition, some additional mRNAs not included in the "nanoString Myeloid Innate Immunity" panel, such as FOXP3 (regulatory function), CRLF2, ST2, or IL-7R (cytokine receptors; activation), will be analysed. HPRT1 gene will be used as a house-keeping gene in this set of RTqPCR experiments. Perform SWATH-MS analysis in samples from 15 healthy donors and 15 patients (T0, T4, T16, T32) ("information-dependent acquisition" method or IDA; "Targeted label-free proteomics") in eosinophil homogenates. High abundant serum protein depletion using two protocols (P1: affinity chromatography, and P2: DTT precipitation) and SWATH-MS analysis of medium-low abundant serum proteome in samples from 15 healthy donors and 15 patients (T0, T4, T16, T32) ("information-dependent acquisition" method or IDA; "Targeted label-free proteomics").