Taro Kikuchi

Intervertebral disc cells produce tumor necrosis factor α, interleukin-1β, and monocyte chemoattractant protein-1 immediately after herniation: An experimental study using a new hernia model

Study Design. A new hernia model that simulates human disc herniations was developed in rabbits. The herniated discs were examined by gross appearance and histology and production of tumor necrosis factor &agr;, interleukin-1&bgr;, and monocyte chemoattractant protein-1 was investigated. Objectives. To clarify the early mechanism of spontaneous herniated disc resorption. Summary of Background Data. Macrophage infiltration in herniated discs is essential for disc resorption. However, surgically removed human herniated disc tissues and existing animal hernia models are not suitable for analyzing the mechanism of macrophage infiltration. Recently, we have demonstrated that intervertebral disc cells are capable of producing monocyte chemoattractant protein-1, a potent macrophage chemoattractant, after stimulation with tumor necrosis factor &agr; and interleukin-1&bgr;. Methods. Intervertebral disc herniations were surgically developed in rabbits using a new technique. The herniated discs were excised at appropriate time intervals after the surgery, and the size and histologic findings were examined. Expressions of tumor necrosis factor &agr;, interleukin-1&bgr;, and monocyte chemoattractant protein-1 in herniated discs were investigated immunohistochemically. Results. A new rabbit model of disc herniation was established. The herniated discs spontaneously reduced in size by 12 weeks postsurgery. Infiltrating cells, mainly composed of macrophages, were observed from day 3. Immunohistochemically, intervertebral disc cells in the herniated discs produced tumor necrosis factor &agr; and interleukin-1&bgr; on day 1, followed by monocyte chemoattractant protein-1 on day 3. Conclusions. The new hernia model appears to be very useful for studying herniated disc resorption. Intervertebral disc cells may produce inflammatory cytokines/chemokine immediately after the onset of disc herniation, possibly triggering subsequent macrophage infiltration that leads to disc resorption.

Monocyte chemoattractant protein-1 in the intervertebral disc. A histologic experimental model.

Study Design. Monocyte chemoattractant protein‐1 was investigated in an experimental rat model using immunohistochemistry. Objective. To ascertain the precise mechanism of macrophage recruitment in the early phase of disc resorption. Summary of Background Data. In previous studies, many investigators reported that disc herniation was resorbed by monocytic phagocytosis. However, how the recruitment of monocytes was triggered is still unknown. Methods. The autologous intervertebral discs from tails of Wistar rats were subcutaneously implanted into the abdomen. These discs were obtained on days 2, 3, 7, and 14 after implantation and were used for immunohistochemical study and for quantitative analysis of monocyte chemoattractant protein‐1 by sandwich enzyme‐linked immunosorbent assay. Results. Monocyte chemoattractant protein‐1‐positive granulocytes and macrophages were observed surrounding the intervertebral disc, and monocyte chemoattractant protein‐1‐positive disc chondrocytes were observed in the nucleus pulposus and the inner anulus fibrosus on day 3. By day 7, monocyte chemoattractant protein‐1‐positive and TRPM‐3‐positive macrophages appeared in the granulation tissue, and some of these cells invaded the nucleus pulposus and inner anulus fibrosus. The concentration of monocyte chemoattractant protein‐1 was highest on day 3. Conclusion. Intervertebral disc chondrocytes have chemotactic properties and play an active role in the recruitment of monocytes involved in disc resorption.

Expression of monocyte chemoattractant protein-1 in primary cultures of rabbit intervertebral disc cells.

Macrophages are considered essential for herniated disc resorption, and chemokines may play a role in their recruitment. Here we demonstrate that intervertebral disc cells are capable of producing monocyte chemoattractant protein‐1 (MCP‐1), a CC chemokine that is chemotactic for macrophages. Nucleus pulposus cells and anulus fibrosus cells were harvested from intervertebral discs of healthy rabbits, and the cells were stimulated with either interleukin (IL)‐1β or tumor necrosis factor (TNF)α. Reverse transcriptase polymerase chain reaction demonstrated that IL‐1β and TNFα induced mRNA expression for MCP‐1 in nucleus pulposus and anulus fibrosus cells. Protein concentrations of MCP‐1 in the culture supernatants were quantitated by fluoroim‐munoassay, which showed that nucleus pulposus and anulus fibrosus cells dose‐ and time‐dependently produced MCP‐1 after IL‐1β‐and TNFα‐stimulation, an event that was completely abrogated by IL‐1 receptor antagonist and anti‐TNFα monoclonal antibody, respectively. Nucleus pulposus cells produced significantly higher levels of MCP‐1 than did anulus fibrosus cells. Immunohisto‐chemically, the intensity of MCP‐1 positive cells in nucleus pulposus cells was stronger than that in anulus fibrosus cells. Altogether, our data clearly demonstrated the production of MCP‐1 in intervertebral disc cells, suggesting the possible involvement of disc cells in an early stage of macrophage infiltration.

Bacteriological Study of Fresh Open and Festering Wounds Following Trauma

To establish a basis for the treatment of open injuries, a bacteriological study of fresh open and festering wounds following trauma was performed. Clinical specimens were directly collected from the wounds by inserting TranswabR into the wounds, followed by bacteriological examinations. Of 213 fresh open wounds, 131 cases were polluted by bacteria and compared to the control group of 57 cases of festering wounds. All 4 of the fresh open wounds that became festered were bacteriologically polluted on their first examination. Of these 4 cases, three were open fractures. On the other hand, no case festered when the wound was proven to be aseptic on the first examination. Bacteria were detected from the wounds more frequently in summer than winter. Coagulase-negative Staphylococcus was most frequently detected and Bacillus cereus, the next. Other species with clinical importance were S. aureus, S. epidermidis, S. milleri, E. faecalis, Aeromonas species, and Clostridium species. Compared with fresh wounds, S. aureus and GNR were detected more frequently in festering wounds.