YKL-40 in human lumbar herniated disc and its relationships with nitric oxide and cyclooxygenase-2

The basic pathophysiology of intervertebral disc degeneration and low back pain remains unclear. It has been hypo-thesized a role of biochemical mediators of inflammation and tissue degradation in intervertebral disc degeneration and herniation. Chitinase 3-like protein 1 (YKL-40) is a glycoprotein mainly secreted by chondrocytes which has been proposed as a possible marker of inflammation and/or cartilage alterations. To investigate the YKL-40 presence in human lumbar disc tissue culture and its possible relationships with some substances relevant in inflammation such as cyclooxygenase-2 (COX-2) and nitric oxide (NO). We analyzed lumbar discs from 19 patients who underwent surgery for lumbar disc herniation at L4-L5 or L5-S1 levels. The specimens were cultured and incubated for 72 hours. At the end of incubation, the supernatants were assayed for presence and concentration of YKL-40, COX-2 and NO. YKL-40 was detectable in all the samples analyzed. Mean (+/-SD) concentration was 1.54+/-1.29 ng/ml/mg compared to dry weight. COX-2 and NO levels were 25.25+/-11.42 pg/ml/mg and 1.3+/-1.8 microM/mgx10(-2), respectively. A correlation was found between YKL-40 and COX-2 (r=0.579, p