IL-1 receptor antagonist anakinra is usually highly efficient in Schnitzler syndrome (SS), a rare inflammatory condition associating urticaria, fever, and IgM monoclonal gammopathy. In this study, we aimed to assess lipopolysaccharide (LPS)-induced production of inflammatory cytokines by peripheral blood mononuclear cells (PBMCs) before and after 1 month of anakinra in patients with SS. LPS-induced production of IL-1β, IL-6 and TNFα was assessed by enzyme-linked immunosorbent assay with and without anakinra in vitro, and before and after 1 month (in vivo condition) of treatment in 2 patients with SS. Spontaneous production of IL-1β, IL-6 and TNF-α by PBMCs was similar in the patients and the healthy controls and was almost undetectable. Stimulation with LPS caused a higher release of cytokines from the patients than from the healthy controls. Before in vivo anakinra start, in vitro adjunction of anakinra reduced the high LPS-induced production of IL-1β and TNFα in both patients and of IL-6 in one patient. After 1 month of treatment with anakinra, while the patients had dramatically improved, there was also a marked reduction in LPS-induced cytokines production, which was almost normalized in one patient. This study shows an abnormal LPS-induced inflammatory cytokines production in SS, which can be decreased or even normalized by in vitro and in vivo anakinra.

The FIP1L1-PDGFRA (F/P) fusion gene, which was identified as a recurrent molecular finding in hypereosinophilic syndrome (HES), lead to a constitutively increased tyrosine kinase activity of the fusion protein. Despite data obtained in animals or cell lines models, the mechanisms underlying the predominant eosinophil lineage targeting and the cytotoxicity of eosinophils in this leukemia remain unclear. To define more precisely intrinsic molecular events associated with F/P gene, we performed a proteomic analysis comparing F/P+ eosinophils (F/P-Eos) and eosinophils from healthy donors (C-Eos). Using 2D-DIGE and mass spectrometry techniques, we identified 41 proteins significantly overexpressed between F/P-Eos and C-Eos. Among them, 17.8% belonged to the oxidoreductase family. We further observed a down-expression of peroxiredoxin-2 (PRX-2) and an overexpression of src-homology-2 domain containing tyrosine phosphatase (SHP-1), enzymes regulating PDGFR downstream pathways, and especially intracellular reactive oxygen species (ROS) production. This profile, confirmed in immunoblot analysis, appears specific to F/P-Eos compared to controls and patients with idiopathic HES. In this clonal disorder possibly involving a pluripotent hematopoietic stem cell, we postulate that the well documented relationships between PDGFRA downstream signals and intracellular ROS levels might influence the phenotype of this leukemia.

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Serological proteome analysis (SERPA) combines classical proteomic technology with effective separation of cellular protein extracts on two-dimensional gel electrophoresis, western blotting, and identification of the antigenic spot of interest by mass spectrometry. A critical point is related to the antigenic target characterization by mass spectrometry, which depends on the accuracy of the matching of antigenic reactivities on the protein spots during the 2D immunoproteomic procedures. The superimposition, based essentially on visual criteria of antigenic and protein spots, remains the major limitation of SERPA. The introduction of fluorescent dyes in proteomic strategies, commonly known as 2D-DIGE (differential in-gel electrophoresis), has boosted the qualitative capabilities of 2D electrophoresis. Based on this 2D-DIGE strategy, we have improved the conventional SERPA by developing a new and entirely fluorescence-based bi-dimensional immunoproteomic (FBIP) analysis, performed with three fluorescent dyes. To optimize the alignment of the different antigenic maps, we introduced a landmark map composed of a combination of specific antibodies. This methodological development allows simultaneous revelation of the antigenic, landmark and proteomic maps on each immunoblot. A computer-assisted process using commercially available software automatically leads to the superimposition of the different maps, ensuring accurate localization of antigenic spots of interest.