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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: METHODS, OBJECTIVE, BACKGROUND, METHODS, RESULTS. Meshes: Animals, Coccyx, Coculture Techniques, Discitis, Enzyme-Linked Immunosorbent Assay, Gene Expression Regulation, Interleukin-6, Intervertebral Disc, Macrophages, Male, Organ Culture Techniques, Rats, Rats, Sprague-Dawley, Reverse Transcriptase Polymerase Chain Reaction, Sciatica.
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Is interleukin-6 production upregulated by interaction between disc tissue and macrophages? Context: Interleukin (IL)-6 production was investigated using a coculture system of disc tissue and macrophages. The purpose of this study was to investigate the interaction between intervertebral disc tissue and macrophages in terms of IL-6 production. IL-6 production is observed in human herniated disc specimens, and there is a correlation between IL-6 production and neurologic symptoms. However, the mechanism of IL-6 production in the herniated disc is not clear. Coccygeal intervertebral discs and exudated peritoneal macrophages were obtained from male Sprague-Dawley rats. Macrophages and intervertebral disc without endplates were cocultured in a serum-free medium. Fat tissue culture with or without macrophages, intervertebral disc alone, and macrophages alone were used for controls. The supernatant fluid of the culture was utilized for the enzyme-linked immunosorbent assay. The precipitations of macrophages and disc coculture were used for semiquantitative RT-PCR for IL-6. Immunohistochemical staining for IL-6 and the macrophages marker (ED2) were also carried out using disc tissue cultured with macrophages. IL-6 production level was significantly increased in the coculture of intervertebral disc and macrophages (P < 0.01). However, there was no significant production of IL-6 in the control groups. The precipitations from coculture of macrophages and disc expressed IL-6 mRNA in semiquantitative RT-PCR. Immunohistochemical staining revealed most IL-6 producing cells were also positive for ED2, which adheres to or infiltrates the peripheral area of the nucleus pulposus.
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Our results demonstrated that interaction between disc tissue and macrophage is necessary for upregulation of IL-6 production. Immunohistochemical staining also indicated that infiltrated macrophages played a major role in production of IL-6, suggesting that infiltration of macrophages into herniated disc material may be a trigger for IL-6 production and associated neurologic symptoms. Final Decision: yes