title: Real-time detection of the chemokine CXCL12 in urine samples by surface plasmon resonance.
abstract: Surface plasmon resonance (SPR)-based biosensors are established tools for measuring biomolecular interactions between unlabeled analytes in real time, and are thus an ideal method to evaluate G protein-coupled receptor (GPCR) binding interactions. Using as a vehicle lentiviral particles bearing the chemokine receptor CXCR4 in its native plasma membrane context, SPR analysis can be performed using the particles as specific receptors to monitor the CXCR4 interaction with its ligand, CXCL12. The method shows linear correlation in the 5-40 nM range, with low intra- and inter-assay variation, a relative standard deviation <10%, chip-to-chip variation <12%, with stability of the sensor response for more than 150 measurements in the same chip over a four-week period. Our objective was to develop a method for rapid detection and quantification of analytes such as CXCL12 in biological samples, with no need for pretreatment. As a proof of concept, we tested for CXCL12 in urine samples from rheumatoid arthritis patients, who have elevated levels of this chemokine in plasma and synovial fluid. The biosensor method allowed sensitive, reproducible CXCL12 detection in the physiological range, suggesting its value for the diagnosis of autoimmune disorders.
authors.affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB/CSIC), Campus de Cantoblanco, Madrid, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Vega
authors.forename: Ana
authors.initials: A
authors.lastname: Calle
authors.forename: Alejandra
authors.initials: A
authors.lastname: Sánchez
authors.forename: Laura M
authors.initials: LM
authors.lastname: Lechuga
authors.forename: Ana M
authors.initials: AM
authors.lastname: Ortiz
authors.forename: Gaspar
authors.initials: G
authors.lastname: Armelles
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Rodríguez-Frade
authors.forename: Mario
authors.initials: M
authors.lastname: Mellado
mesh_terms: D001172:Arthritis, Rheumatoid / Q000097:blood / Q000652:urine; D015415:Biomarkers / Q000652:urine; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D054377:Chemokine CXCL12 / Q000737:chemistry / Q000652:urine*; D005434:Flow Cytometry; D057809:HEK293 Cells; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D008024:Ligands; D011485:Protein Binding; D019718:Receptors, CXCR4 / Q000737:chemistry / Q000235:genetics; D020349:Surface Plasmon Resonance / Q000295:instrumentation / Q000379:methods*; D013582:Synovial Fluid / Q000737:chemistry; D014162:Transfection; D014771:Virion / Q000235:genetics
chemical_list: D015415:Biomarkers; C515255:CXCL12 protein, human; C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; D008024:Ligands; D019718:Receptors, CXCR4