Analysis of chondrex (YKL-40, HC gp-39) in the cerebrospinal fluid of patients with spine disease

Study Design. The expression of chondrex (YKL-40, HC gp-39) was measured in the cerebrospinal fluid of from patients with spine diseases. Objectives. To quantify the levels of chondrex in human cerebrospinal fluid, and to clarify the nature of its expression. Summary of Background Data. Chondrex is a newly discovered 40-kDa glycoprotein identified originally in the whey secretions of nonlactating cows. It is secreted by a human osteosarcoma cell line, human articular cartilage chondrocytes, and human fibroblasts. However, the function of chondrex in chondrogenesis is unknown, and the expression of chondrex in human cerebrospinal fluid has never been reported. Methods. The concentration of chondrex in human cerebrospinal fluid was measured by sandwich immunoassay with antihuman chondrex antibodies. Cerebrospinal fluid samples were collected from two groups of patients. Group 1, the control group, consisted of 34 trauma patients. Group 2 consisted of 130 patients with spine diseases: 29 with cervical spondylotic myelopathy, 30 with lumbar disc herniation, 35 with lumbar canal stenosis, and 36 with scoliosis. All values are expressed as the mean +/- standard deviation. Results. The concentration of chondrex in Group 1 (control group) was 113.8 +/- 48.3 ng/mL. The concentrations of chondrex in Group 2 were 245.3 +/- 107.2 ng/mL in cervical myelopathy, 143.2 +/- 53.6 ng/mL in lumbar disc herniation, 241.5 +/- 77.2 ng/mL in lumbar canal stenosis, and 71.4 +/- 33.9 ng/mL in scoliosis. The concentrations of chondrex in cervical myelopathy, lumbar canal stenosis, and lumbar disc herniation were significantly higher than in the control group (P < 0.05). Conclusions. In this study, the chondrex concentration was high in spine diseases causing spinal stenosis. The authors believe that chondrex is expressed in cerebrospinal fluid as a result of damage or stress to the neural structure, and that it could be a new marker for spine diseases.