HERNIATED LUMBAR INTERVERTEBRAL DISCS SPONTANEOUSLY PRODUCE MATRIX METALLOPROTEINASES, NITRIC-OXIDE, INTERLEUKIN-6, AND PROSTAGLANDIN E(2)

Study Design. Herniated lumbar disc specimens were obtained from patie nts undergoing surgical discectomy for persistent radiculopathy and cu ltured in vitro to determine whether various biochemical agents were b eing produced. Objectives, Our hypothesis is that biochemical mediator s of inflammation and tissue degradation play a role in intervertebral disc degeneration ana in the pathophysiology of radiculopathy. Summar y of Background Data, Low back pain with or without radiculopathy is a significant clinical problem, but the etiology of low back pain and t he exact pathophysiology of radiculopathy remain elusive. The biochemi cal events that occur with intervertebral disc degeneration and, in pa rticular, the role of biochemical mediators of inflammation and tissue degradation have received sparse attention in the literature.-There i s some preliminary evidence that inflammatory mediators may have an im portant role in the pathophysiology of radiculopathy. Methods. Eightee n herniated lumbar discs were obtained from 15 patients undergoing dis c surgery. The specimens were cultured and incubated for 72 hours, and the media were collected subsequently for biochemical analysis. Bioch emical assays for matrix metalloproteinases, nitric oxide,prostaglandi n E(2), and a variety of cytokines were performed. As a control group, eight lumbar disc specimens were obtained from four patients undergoi ng anterior surgery for scoliosis and traumatic burst fractures, and s imilar biochemical analyses were performed. Results. The culture media from the herniated lumbar discs showed increased levels of matrix met alloproteinase activity compared with the control discs. Similarly, th e levels of nitric oxide,,prostaglandin E(2), and interleukin-6 were s ignificantly higher in the herniated discs compared with the control d iscs. Interleukin-1 alpha, interleukin-1 beta, tumor necrosis factor-a lpha, interleukin-1 receptor antagonist protein, and substance P were not detected in the culture media of either the herniated or control d iscs. Conclusions. Herniated lumbar discs were making spontaneously in creased amounts of matrix metalloproteinases, nitric oxide, prostaglan din E(2), and interleukin-6. These products may be involved intimately in the biochemistry of disc degeneration and the pathophysiology of r adiculopathy. Their exact roles certainly need further investigation, but their mere presence implicates biochemical processes in interverte bral disc degeneration.