Comparative analysis of serum proteomes to discover biomarkers for ossification of the posterior longitudinal ligament

STUDY DESIGN. Serum proteomes from normal subjects and the patients with ossification of the posterior longitudinal ligament (OPLL) were analyzed by using proteomics. OBJECTIVES. To identify novel serologic biomarkers for diagnosing OPLL. SUMMARY OF BACKGROUND DATA. OPLL can compress the spinal cord, and special planning is required for surgeries that are done from the front of the cervical spine. However, the definitive serologic biomarkers for OPLL are still unclear. METHODS. The 2-dimensional electrophoresis patterns of sera from OPLL patients and normal subjects were compared. The differentially expressed spots were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and electrospray ionization quadruple time-of-flight mass spectrometry. RESULTS. Nine spots that were differentially expressed in the sera of OPLL patients were found and were identified. PRO2675, human serum albumin in a complex with myristic acid and tri-iodobenzoic acid, an unknown protein, chain B of the crystal structure of deoxy-human hemoglobin beta6, pro-apolipoprotein, ALB protein, retinol binding protein and chain A of human serum albumin mutant R218h complexed with thyroxine (3,3′,5, 5′, tetraiodo-L-thyronine), were up-regulated in the sera of OPLL patients, whereas α1-microglobulin/bikunin precursor was down-regulated. CONCLUSIONS. These proteins could be used as diagnostic biomarkers of OPLL.