Journal
SPINE
Volume 25, Issue 1, Pages 17-23Publisher
LIPPINCOTT WILLIAMS & WILKINS
DOI: 10.1097/00007632-200001010-00005
Keywords
anulus fibrosus; cell culture; chondrocyte; intervertebral disc; phospholipase A2; prostaglandin; proteoglycans; stromelysin
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Study Design, Anulus fibrosus cells from rabbits were grown in primary culture 1) to study their ability to produce prostaglandin E2 and Type II phospholipase A2, and to express stromelysin-1 messenger ribonucleic acid; and 2) to study the effect of interleukin 1 beta on this production and on proteoglycan aggregation. Objectives. To investigate the potency of anulus fibrosus cells to respond to interleukin 1 beta by producing degradative and inflammatory agents as compared with the potency of articular chondrocytes in the same animal. Summary of Background Data. Interleukin 1 beta has been implicated in the degradation of intervertebral discs. The way anulus fibrosus cells differ from articular chondrocytes in their responses to interleukin 1 beta remains to be established. Methods. Anulus fibrosus cells and articular chondrocytes were obtained from young rabbits, grown in primary culture, and incubated with interleukin 1 beta. The newly synthesized proteoglycan was measured by labeling with [S-35]-sulfate. Proteoglycan aggregation was analyzed by the elution profile on Sepharose 2B columns. The contents of collagen Type II and stromelysin-1 messenger ribonucleic acid were assessed by Northern blot analysis. The Type II phospholipase A2 activity was measured using a fluorometric substrate. Prostaglandin E2 production was evaluated by radioimmunoassay. Results. Anulus fibrosus cells had 2.5-fold less Type II collagen messenger ribonucleic acid than articular chondrocytes, and interleukin 1 beta had no significant effect on this. Anulus fibrosus cells synthesized and secreted fourfold less proteoglycan than articular chondrocytes. Interleukin 1 beta reduced the anulus fibrosus content of total [S-3S]-sulfated proteoglycan by 35% (P< 0.01), and that of articular cells by 41% and decreased proteoglycan aggregation. Interleukin 1 beta induced the production of stromelysin-1 messenger ribonucleic acid in both cell types. The stromelysin-1 messenger ribonucleic acid content of anulus fibrosus cells was one half that of articular cells. Interleukin 1 beta increased the production of prostaglandin 52 and caused a dose-dependent secretion of Type II phospholipase A2 activity in both cell types. Its effect was 2.5-fold lower in anulus fibrosus cells than in articular chondrocytes. Conclusion. Anulus fibrosus cells can be stimulated by interleukin 1 beta to produce factors implicated in local degradative and inflammatory processes. This production is associated with decreased proteoglycan aggregation. Anulus fibrosus cells respond slightly less well to interleukin 1 beta in vitro than do articular cells.
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