Surface plasmon resonance imaging in arrays coupled with mass spectrometry (SUPRA-MS): proof of concept of on-chip characterization of a potential breast cancer marker in human plasma.

Protein biomarker discovery and validation are crucial for diagnosis, prognosis, and theranostics of human pathologies; "omics" approaches bring new insights in this field. In particular, the combination of immuno-sensors in array format with mass spectrometry efficiently extends the classical immunoassay format and includes molecular characterization. Here, we coupled surface plasmon resonance imaging (SPRi) with MALDI-TOF mass spectrometry in a hyphenated technique which enables multiplexed quantification of binding by SPRi and molecular characterization of interacting partners by subsequent MS analysis. This adds specificity, because MS enables differentiation of molecules that are difficult to distinguish by use of antibodies, for example truncation variants or protein isoforms. Proof of concept was established for detection, identification, and characterization of a potential breast cancer marker, the LAG3 protein, at ~1 µg mL(-1), added to human plasma. The analytical performance of this new method, dubbed "SUPRA-MS", was established, particularly its specificity (S/N > 10) and reliability (100 % LAG3 identification with high significant mascot score >87.9). The adjusted format for rapid, collective, and automated on-chip MALDI-MS analysis is robust at the femtomole level and has numerous potential applications in proteomics.

Characterization of new mutations in the 5'-flanking region of the familial Mediterranean fever gene.

Familial Mediterranean fever (FMF) is a recessive autoinflammatory disease commonly found in the Mediterranean populations. Genetic diagnosis has developed since the discovery of the causative gene MEFV in 1997. As many patients could not be confirmed genetically by routine exon screening, we searched for mutations in the 5'-flanking region of this gene. Using denaturing gradient gel electrophoresis, we screened DNA from 108 patients with clinical FMF and 91 asymptomatic individuals. We found six novel sequence variants in a region extending -825 bp upstream of the first translated codon. To investigate the potential role of these variants in altering MEFV gene expression, we first characterized the MEFV promoter. Promoter mapping assays revealed that the region located between nucleotides -949 and -152 of the initiation codon was important for regulating expression of the gene. We identified a putative enhancer element between -571 and -414. Investigation of the sequence variants found in two patients demonstrated that c.-614C>G resulted in a 70% decrease in promoter activity, whereas c.-382C>T induced a 100% increase in activity, when compared to the wild type. We observed specific DNA-protein binding to both wild-type sites, suggesting that transcription factors may bind to these sequences to modulate MEFV expression.

Human monoclonal antibodies isolated from spontaneous Epstein-Barr virus-transformed tumors of Hu-SPL-SCID mice and specific for fusion protein display broad neutralizing activity toward respiratory syncytial virus.

Two human monoclonal antibodies, RF-1 and RF-2, specifically recognize the fusion protein of the human respiratory syncytial virus (RSV). These were isolated from spontaneous tumors in SCID mice reconstituted with human splenocytes and boosted with fusion protein. The tumors consisted of Epstein-Barr virus-transformed human B cells in animals with antigen-specific antibody titers>105. The binding affinity of RF-1 and RF-2 to the fusion protein is 1010 and 109 M-1, respectively. The antibodies bind specifically to a conformational epitope of the fusion protein on RSV-infected HEp-2 cells. Both antibodies display virus-neutralizing properties in vitro at concentrations varying between 8 and 1000 ng/mL. Virus neutralization applies to a broad variety of wild and laboratory-adapted virus strains belonging to both virus types A and B. These antibodies are potential candidates for passive immunotherapy of severe RSV infections.