Takana Koshi

Tumor necrosis factor-immunoreactive cells and PGP 9.5-immunoreactive nerve fibers in vertebral endplates of patients with discogenic low back Pain and Modic Type 1 or Type 2 changes on MRI.

Study Design. Immunohistochemistry for tumor necrosis factor (TNF) and protein gene product (PGP) 9.5 in vertebral endplates of patients with discogenic low back pain and Modic Type 1 or Type 2 endplate changes on MRI. Objectives. To examine whether inflammatory cytokines and nerve in-growth into the vertebral endplate are associated with discogenic low back pain. Summary and Background Data. Degenerated discs and endplate abnormalities can be a cause of discogenic low back pain. However, the presence of TNF-immunoreactive cells and PGP 9.5-immunoreactive nerve fibers has not been studied in patients with discogenic low back pain and endplate changes on MRI. Methods. Eighteen endplates showing either normal intensity signals on MRI (endplate change −), Modic Type 1 signals (low intensity on T1-weighted spin-echo images), or Modic Type 2 signals (high intensity) from patients with discogenic low back pain (n = 14) or controls requiring surgery for other back problems (n = 4; scoliosis and traumatic injury of vertebra) were harvested during surgery. Endplates were immunostained using antibodies to TNF and PGP 9.5 and immunostained cells and nerve fibers in the endplates were counted. Results. Vertebral endplates from patients with Modic Type 1 or Type 2 endplate changes on MRI had significantly more PGP 9.5-immunoreactive nerve fibers and TNF-immunoreactive cells in comparison with patients with normal endplates on MRI (P < 0.01). The number of TNF-immunoreactive cells in endplates exhibiting Modic Type 1 changes was significantly higher than in endplates exhibiting Modic Type 2 changes (P < 0.05). Conclusions. The results suggest that endplate abnormalities are related to inflammation and axon growth induced by TNF. TNF expression and PGP 9.5-positive nerve in-growth in abnormal endplates may be a cause of low back pain.

Associations between proinflammatory cytokines in the synovial fluid and radiographic grading and pain-related scores in 47 consecutive patients with osteoarthritis of the knee

BackgroundOne of the sources of knee pain in osteoarthritis (OA) is believed to be related to local chronic inflammation of the knee joints, which involves the production of inflammatory cytokines such as tumor necrosis factor alpha (TNFα), interleukin (IL)-6, and nerve growth factor (NGF) in the synovial membrane, and these cytokines are believed to promote pathological OA. In the present study, correlations between proinflammatory cytokines in knee synovial fluid and radiographic changes and functional scores and pain scores among OA patients were examined.MethodsSynovial fluid was harvested from the knees of 47 consecutive OA patients, and the levels of TNFα, IL-6, and NGF were measured using enzyme-linked immunosorbent assays. Osteoarthritic knees were classified using Kellgren-Lawrence (KL) grading (1-4). The Western Ontario and McMaster University Osteoarthritis Index (WOMAC) was used to assess self-reported physical function, pain, and stiffness.ResultsTNFα and IL-6 were detectable in knee synovial, whereas NGF was not. TNFα was not correlated with the KL grade, whereas IL-6 had a significantly negative correlation. We observed differences in the correlations between TNFα and IL-6 with WOMAC scores and their subscales (pain, stiffness, and physical function). TNFα exhibited a significant correlation with the total score and its 3 subscales, whereas IL-6 exhibited a moderately significant negative correlation only with the subscale of stiffness.ConclusionsThe present study demonstrated that the concentrations of proinflammatory cytokines are correlated with KL grades and WOMAC scores in patients with knee OA. Although TNFα did not have a significant correlation with the radiographic grading, it was significantly associated with the WOMAC score. IL-6 had a significant negative correlation with the KL grading, whereas it had only a weakly significant correlation with the subscore of stiffness. The results suggest that these cytokines play a role in the pathogenesis of synovitis in osteoarthritic knees in different ways: TNFα is correlated with pain, whereas IL-6 is correlated with joint function.

Results of surgery for discogenic low back pain: a randomized study using discography versus discoblock for diagnosis.

Study Design. Randomized, controlled study. Objective. To evaluate the diagnosis of discogenic low back pain (LBP) with discography and discoblock. Summary of Background Data. Discogenic LBP is usually diagnosed by magnetic resonance imaging and discography. However, the reliability of discography is controversial. Previously, we reported the usefulness of discoblock with bupivacaine for diagnosis, and discoblock improved the results of anterior interbody fusion surgery. However, that study was not a randomized, controlled study. Therefore, the purpose of the current study was to compare the results of surgery after diagnosis of LBP by discography and discoblock. Methods. Patients (n = 42) with severe LBP showing L4–L5 or L5–S1 disc degeneration on magnetic resonance imaging were evaluated by discography (1.5 mL of contrast medium) or discoblock (intradisc injection of 0.75 mL of 0.5% bupivacaine). We randomized the patients in turn. Anterior discectomy and interbody fusion were performed in patients who responded to the diagnostic procedures. The visual analogue scale score (0, no pain; 100, worst pain), Japanese Orthopedic Association Score (0, worst pain; 3, no pain), Oswestry Disability Index, and patient satisfaction before and 3 years after surgery were recorded and compared between groups. Results. Twelve patients did not show pain provocation by discography or pain relief by discoblock and were excluded. Fifteen patients who showed pain provocation by discography and 15 patients who experienced pain relief with discoblock were evaluated. Rates of improvement in the visual analogue scale score, Japanese Orthopedic Association Score, and Oswestry Disability Index score in the discoblock group were significantly higher than those in the discography group (P < 0.05) from baseline to 3 years after surgery. Three patients were dissatisfied with surgery after discography compared with one patient after discoblock. Conclusion. Pain relief after injection of a small amount of bupivacaine into the painful disc was a useful tool for the diagnosis of discogenic LBP compared with discography.

Glial phosphorylated p38 MAP kinase mediates pain in a rat model of lumbar disc herniation and induces motor dysfunction in a rat model of lumbar spinal canal stenosis.

Study Design. Immunohistochemical and behavioral study using rat models of lumbar disc herniation and cauda equina syndrome. Objective. To investigate the expression of activated p38 mitogen-activated protein kinases (p38 MAP kinase; p38) in the spinal cord and to determine the effect of intrathecal administration of a specific p38 inhibitor on pain in a lumbar disc herniation model and on motor function and hypoalgesia in a spinal canal stenosis (SCS) model. Summary of Background Data. In pathologic lumbar disc herniation-induced neuropathic pain and compression of cauda equina-induced motor dysfunction and hypoalgesia caused by SCS, glia are activated and produce certain cytokines, including tumor necrosis factor-alpha (TNF-&agr;) and interleukins, which play a crucial role in the pathogenesis of nerve degeneration. p38 is phosphorylated by these cytokines, suggesting that it may play an important role in pain transmission and nerve degeneration. Here we have examined the role of p38 in rat models of lumbar disc herniation and SCS. Methods. Six-week-old male Sprague-Dawley rats were used. For the disc herniation model, autologous nucleus pulposus was applied to L5 nerve roots, which were then crushed. For the SCS model, a piece of silicon was placed under the lamina of the fourth lumbar vertebra. We assessed mechanical allodynia, hypoalgesia, and motor function using von Frey hairs, treadmill tests, and immunohistochemical localization of phosphorylated p38 (P-p38) in the cauda equina, dorsal root ganglion (DRG), and spinal cord, which were also double-stained with NeuN (neuronal marker), GFAP (astrocyte/Schwann cell marker), or isolectin B4 (IB4; microglia marker). We also examined the effects of intrathecal administration of a specific p38 inhibitor, FR167653, on nucleus pulposus-induced pain, hypoalgesia, and motor dysfunction following SCS. Results. We demonstrated that activated P-p38-immunoreactive cells in the spinal cord and cauda equina were not observed before nerve injury but appeared in the cauda equina, DRG, and spinal dorsal horn in the disc herniation and SCS models. Double-labeling revealed that most P-p38-immunoreactive cells were isolectin B4-labeled microglia and GFAP-immunoreactive Schwann cells. Intrathecal administration of the p38 inhibitor FR167653 decreased mechanical allodynia in the disc herniation model and improved hypoalgesia and intermittent motor dysfunction in the SCS model. Conclusions. Our findings suggest that activated p38 may play an important role in the involvement of microglia in the pathophysiology of pain following lumbar disc herniation and mechanical hypoalgesia, and motor nerve dysfunction of cauda equina following SCS.

Up-regulation of acid-sensing ion channel 3 in dorsal root ganglion neurons following application of nucleus pulposus on nerve root in rats.

Study Design. Immunocytochemistry for acid-sensing ion channel 3 (ASIC3) in neurons of rat dorsal root ganglions (DRGs) from animals exposed to a model of lumbar disc herniation. Objective. To examine expression of ASIC3 in DRGs and the effect of a sodium channel blocker applied to the nerve root in a rat model of lumbar disc herniation. Summary of Background Data. Radicular pain is a common symptom of lumbar disc herniation in human beings. A depolarizing sodium channel gated by protons during tissue acidosis, ASIC3, is specifically expressed in sensory neurons. It has been associated with cardiac ischemic and inflammatory pain. We often perform spinal nerve root block for radicular pain using a sodium channel blocker, such as lidocaine; however, it has been unclear whether the effective period of this treatment is usually longer than the expected duration of efficacy. Methods. For the lumbar disc herniation model, nucleus pulposus was harvested from the tail and applied to the L5 nerve root, and the nerve roots were pinched. We evaluated mechanical allodynia in sham-operated animals and a disc herniation model. Immunohistochemistry was used to examine ASIC3 expression in L5 DRGs. Finally, the effect of lidocaine on pain and ASIC3 expression in the disc herniation model was examined. Results. Animals exposed to the lumbar disc herniation model showed allodynia for 8 days, and ASIC3 immunoreactivity was up-regulated in DRG neurons. After administration of lidocaine to spinal nerve roots affected by disc herniation, ASIC3 immunoreactivity was down-regulated in DRG neurons, and the level of mechanical allodynia was significantly decreased for 8 days. Conclusions. Our results suggest that ASIC3 in DRG neurons may play an important role in nerve root pain caused by lumbar disc herniation. Lidocaine decreased ASIC3 expression in DRG neurons and pain associated with the disc herniation model.

Tumor Necrosis Factor-alpha in the Nucleus Pulposus Mediates Radicular Pain, but Not Increase of Inflammatory Peptide, Associated With Nerve Damage in Mice

Study Design. Changes in behavior and the immunohistochemistry of dorsal root ganglion (DRG) neurons were examined using a mouse model of radicular pain. Objective. To examine the effects of TNF-α in the nucleus pulposus (NP) on nerve roots. Summary of Background Data. Radicular pain is induced by mechanical compression and inflammation of nerve roots. Many authors have reported that following disc herniation, producing TNF-α plays a major role in neuropathic pain. Their findings suggest that TNF-α contained in the NP is significant in the development of pain and nerve root degeneration, but it has not been clearly demonstrated. Methods. Wild-type NPs or TNF-KO NPs, which were harvested from C57BL/6 mice (wild-type NP) or TNF-knock-out mice (TNF-KO NP), were applied to the left sciatic nerves of 30 wild-type mice, and the nerves were pinched. Production of hind paw mechanical allodynia, activating transcription factor 3, and calcitonin gene- related peptide (CGRP) were assessed. Results. Animals receiving a NP application demonstrated significant mechanical allodynia compared to the pinch-only and the control groups. The degree of mechanical allodynia was greater in the wild-type than in the TNF-KO group. The number of activating transcription factor 3 immunoreactive neurons was significantly higher in the wild-type than in the TNF-KO group. The number of CGRP-immunoreactive neurons was higher in the wild-type and TNF-KO than in the control groups. However, no significant difference in activity was observed between both CGRP positive groups. Conclusion. In this study TNF-α contained in the NP was important for the production of radicular pain accompanied by long-lasting degeneration of DRG neurons. However, other cytokines in the NP and nerve compression may also play important roles in pain transmission. In this model system, TNF-α in the NP appears to mediate pain, but not cause an increase in CGRP in the DRG neurons.

TNF-alpha in nucleus pulposus induces sensory nerve growth: a study of the mechanism of discogenic low back pain using TNF-alpha-deficient mice.

Study Design. We used retrograde neurotracing with fluoro-gold to investigate the relationship between tumor necrosis factor (TNF-á) and nerve growth into the nucleus pulposus (NP) of wild-type and TNF-&agr;-deficient mice. Objective. To clarify mechanisms underlying nerve growth into the NP and the role of TNF-á in this process. Summary of Background Data. Degeneration of lumbar intervertebral discs is a cause of low back pain. Pathogenesis may involve sensory nerve ingrowth into the inner layers and NP of degenerating discs. We hypothesized that TNF-á in the NP is a major inducer of nerve ingrowth and investigated this hypothesis in vivo using wild-type and TNF-á-deficient mice. Methods. NP was harvested at the L4/5 level from 10 wild-type and 10 TNF-deficient mice. These 20 samples of wild-type NP or TNF-deficient NP were mixed with fluoro-gold and injected into the left quadriceps muscle of 20 other wild-type mice (1 sample per mouse). Five control mice underwent sham operations in which they received similar injections of NP-free fluoro-gold into their left quadriceps muscles to detect whether neurons innervating the muscle establish contact with injected NP. Seven and 14 days after surgery, left L4 dorsal root ganglions were removed and incubated with antibodies against growth-associated protein 43 (GAP43), a marker of axonal growth. We evaluated fluoro-gold-labeled and GAP43-immunoreactive dorsal root ganglions neurons. Results. Within the set of fluoro-gold-labeled neurons, 10% were positive for GAP43 in sham-operated animals, 22% positive in the TNF-deficient NP group, and 38% positive in the wild-type NP group. These intergroup differences in the percentage of GAP43-positive neurons were statistically significant (sham vs. TNF-deficient NP group: P = 0.009; TNF-deficient NP group vs wild-type NP group: P = 0.026). Conclusion. The percentage of fluoro-gold–labeled GAP43-immunoreactive neurons significantly increased after injections of NP harvested from both mouse types. Furthermore, the percentage of GAP43-immunoreactive neurons was significantly higher in mice receiving wild-type NP compared with mice receiving TNF-deficient NP. These findings suggest that TNF-&agr; acts as an inducer of axonal growth into degenerated discs, as evidenced by decreased GAP-43 immunoreactivity in mice receiving TNF-deficient NP injections and even lower GAP-43 immunoreactivity in control mice receiving NP-free fluoro-gold injections.

Nerve growth factor of cultured medium extracted from human degenerative nucleus pulposus promotes sensory nerve growth and induces substance p in vitro.

Study Design. We investigated the mechanism of discogenic low back pain using an in vitro model. Objective. To evaluate the axonal growth and induction of a painful neuropeptide, substance P (SP), using rat dorsal root ganglion (DRG) neurons and degenerated human disc cells in vitro. Summary of Background Data. Degeneration of the lumbar intervertebral disc is a cause of low back pain. The pathologic mechanism is thought to be sensory nerve ingrowth into the inner layers of the degenerated intervertebral disc; however, the precise patho-mechanism has not been clarified. Methods. The nucleus pulposus (NP) and annulus fibrosus (AF) of human intervertebral discs were harvested from patients with discogenic low back pain. Extracted medium from human degenerative intervertebral discs was cultured with neurons of rat DRGs. We evaluated the promotion of axonal growth and SP induction of DRG neurons in extracted medium from the NP and AF using immunocytochemistry. Results. The average length of growing axons in the NP and AF was significantly longer than that in the control (P < 0.005). That in the NP was significantly longer than that in the AF. The average length of growing axons in the NP was significantly shortened after anti-nerve growth factor (NGF)&bgr; treatment (P < 0.005); however, that in the AF was not (P > 0.05). The percentage of SP-immunoreactive cells with growing axons was significantly higher only in the NP group compared with the control and AF groups (P < 0.005), and anti-NGF&bgr; treatment decreased the expression of SP in the NP group (P < 0.05). Conclusion. Extracted medium from the NP and AF promoted axonal growth. Furthermore, NGF from the NP promoted axonal growth and induced SP. These in vitro results may suggest that NGF from the NP promotes the growth of sensory nerve fibers innervating the degenerated intervertebral disc and may induce SP related with pain transmission.

Existence of nerve growth factor receptors, tyrosine kinase a and p75 neurotrophin receptors in intervertebral discs and on dorsal root ganglion neurons innervating intervertebral discs in rats.

Study Design. We evaluated 2 types of nerve growth factor (NGF) receptors on dorsal root ganglion (DRG) cells and nerve fibers innervating rat lumbar intervertebral discs. Objective. To examine the NGF receptors, tyrosine kinase A (TrkA) and p75 neurotrophin receptor (p75NTR) on DRG cells and nerve fibers innervating rat lumbar intervertebral discs using immunohistochemistry and a retrograde neurotracing method. Summary of Background Data. Nerve innervation of intervertebral discs is thought to be a pathology of discogenic low back pain. NGF is also important for mediating inflammatory pain from intervertebral discs via the high affinity receptor, TrkA. Recent research has also revealed that the low affinity NGF receptor, p75NTR plays an important role in inflammatory pain. However, the presence of TrkA and p75NTR-immunoreactive (NTR-IR) DRG neurons innervating the rat L5/6 intervertebral disc, and p75NTR-IR nerve fibers in rat intervertebral discs, has not been explored. Methods. The Fluoro-gold neurotracer was applied to rat L5/6 intervertebral discs to determine the DRG neurons innervating the discs (n = 20). Fourteen days after surgery, bilateral DRG from the L1–L6 levels were harvested, sectioned, and immunostained for TrkA and p75NTR. The percentages of TrkA and p75NTR-IR DRG neurons were counted, and p75NTR-IR nerve fibers in L5/6 discs evaluated. Results. p75NTR-IR nerve fibers were found in superficial layers in the annulus fibrosus in L5/6 intervertebral discs. Fluoro-gold-labeled neurons innervating the L5/6 discs were distributed throughout DRG from the L1–L6 levels. The percentage of TrkA-immunoreactive (TrkA-IR) neurons was 75.1% ± 3.9% (mean ± SE) and that of p75NTR-IR neurons was 75.8% ± 5.1%. These percentages were similar for each level. Conclusion. Rat L5/6 intervertebral discs were innervated by multisegmental levels of DRG. Most DRG neurons innervating the discs were positive for 2 types of NGF receptors.

Surgical versus nonsurgical treatment of selected patients with discogenic low back pain: a small-sized randomized trial.

Low back pain (LBP) is a common clinical problem and is of major socioeconomic importance. Although any of the spinal structures (intervertebral discs, facet joints, vertebral bodies, ligaments, and muscles) may be a source of LBP, the most likely cause is a lumbar intervertebral disc.1–3 Many autho