Direct application of the TNF-alpha inhibitor, etanercept, does not affect CGRP expression and phenotypic change of DRG neurons following application of nucleus pulposus onto injured sciatic nerves in rats

Intradiscal inflammatory stimulation induces spinal pain behavior and intervertebral disc degeneration in vivo

Degeneration of the intervertebral disc (IVD) results in a range of symptomatic (i.e., painful) and asymptomatic experiences. Components of the degenerative environment, including structural disruption and inflammatory cytokine production, often correlate with pain severity. However, the role of inflammation in the activation of pain and degenerative changes has been complex to delineate. The most common IVD injury model is puncture; however, it initiates structural damage that is not representative of the natural degenerative cascade. In this study, we utilized in vivo injection of lipopolysaccharide (LPS), a pro-inflammatory stimulus, into rat caudal IVDs using 33G needles to induce inflammatory activation without the physical tissue disruption caused by puncture using larger needles. LPS injection increased gene expression of pro-inflammatory cytokines (Tnfa, Il1b) and macrophage markers (Inos, Arg1), supported by immunostaining of macrophages (CD68, CCR7, Arg1) and systemic changes in blood cytokine and chemokine levels. Disruption of the IVD structural integrity after LPS injection was also evident through changes in histological grading, disc height, and ECM biochemistry. Ultimately, intradiscal inflammatory stimulation led to local mechanical hyperalgesia, demonstrating that pain can be initiated by inflammatory stimulation of the IVD. Gene expression of nociceptive markers (Ngf, Bdnf, Cgrp) and immunostaining for neuron ingrowth (PGP9.5) and sensitization (CGRP) in the IVD were also shown, suggesting a mechanism for the pain exhibited. To our knowledge, this rat IVD injury model is the first to demonstrate local pain behavior resulting from inflammatory stimulation of caudal IVDs. Future studies will examine the mechanistic contributions of inflammation in mediating pain.

Intradiscal Therapies for Lumbar Degenerative Disk Disease

Discogenic low back pain is a common musculoskeletal complaint in patients presenting to orthopaedic surgeons. In addition to surgical options, there are several nonsurgical intradiscal treatments that have gained interest, ranging from biologic, nonbiologic, cell-based, and molecular therapies. However, there is limited evidence for many of these techniques, and some are still in the clinical trial stage. We describe a broad overview of these intradiscal therapies, the mechanism of action, and the evidence behind them.

The Elevated Serum Level of IFN-γ in Patients with Failed Back Surgery Syndrome Remains Unchanged after Spinal Cord Stimulation

Objectives

We investigated the influence of spinal cord stimulation (SCS) on IFN-γ, IL-1β, IL-6, TNF-α, IL-10, and TGF-β serum levels in failed back surgery syndrome (FBSS) patients. The study will try to give new insights into the mechanism of SCS action and the role of IFN-γ and other cytokines in neuropathic pain (NP) development.

Materials and Methods

Clinical and biochemical assessment was conducted in four groups of patients: group 0 consisted of 24 FBSS patients qualified to SCS therapy, group 1 included 17 patients who were one month after implantation, group 2 featured 12 patients who were 3 months after the implantation, and group C (the control group) with no NP. Clinical status was assessed with the use of Numeric Rating Scale (NRS), the Pain Rating Index of McGill Pain Questionnaire (SF-MPQ), the Oswestry Disability Index (ODI), and Beck Depression Inventory (BDI). The plasma concentrations of IFN-γ were ascertained by an immunoenzymatic method.

Results

We found a significant difference between the patients before SCS and controls' serum level of IFN-γ. Similarly, a significantly higher level of TNF-α and significantly lower level of IL-10 in FBSS patients than controls were observed. The significant differences were not observed between SCS patients 3 months after the procedure and controls' serum level of IFN-γ and other cytokines. We noticed a positive correlation between IFN-γ concentration with NRS back value before SCS and positive correlation between IFN-γ concentration after SCS with NRS leg value before SCS. Higher IFN-γ concentrations accompanied higher NRS values. Levels of TGF-β and IL-10 may correlate with physical ability and depressive behavior.

Conclusions

SCS did not influence serum cytokine levels significantly. Serum concentration of IFN-γ may be recognized as an occasional pain factor because of its significantly higher level in FBSS patients versus controls and higher IFN-γ value accompanying higher pain intensity.

Comparison of effectiveness for fluoroscopic cervical interlaminar epidural injections with or without steroid in cervical post-surgery syndrome

Background

Neck and back pain are leading sources of disability placing substantial burden on health care systems. Surgical interventions in managing chronic neck pain secondary to various disorders continue to increase. Even though surgical interventions are effective, a significant proportion of patients continue to have symptomatology and develop cervical post-surgery syndrome. This study was performed to know the effectiveness of cervical interlaminar epidural injections with or without steroids.

Methods

The effectiveness of fluoroscopic cervical interlaminar epidural injections in post-surgery syndrome was evaluated in a randomized, active controlled trial. The study population included 116 patients assigned to 2 groups. Group 1 received cervical interlaminar epidural injections with local anesthetic alone and Group 2 received injection with local anesthetic and steroids. The main outcomes were defined as significant improvement (greater than 50%) of pain relief using the numeric rating scale and/or functional status improvement using the Neck Disability Index (NDI).

Results

Both groups had similar results with significant improvement (≥ 50% pain relief and functional status improvement) in 69% of the patients in Group I, whereas, in Group II, 71% of the patients showed significant improvement at the end of 2 years. During a 2-year period, the average number of procedures was 5 to 6, with an average of approximately 12 weeks of significant improvement per procedure.

Conclusions

Fluoroscopic cervical interlaminar epidural injections administered in cervical post-surgery syndrome using local anesthetic, regardless of the use of steroids, may be effective in approximately 70% of the patients at 2-year follow-up.

Targeting cytokines for treatment of neuropathic pain

BACKGROUND

Neuropathic pain is a challenging condition often refractory to existing therapies. An increasing number of studies have indicated that the immune system plays a crucial role in the mediation of neuropathic pain. Exploration of the various functions of individual cytokines in neuropathic pain will provide greater insight into the mechanisms of neuropathic pain and suggest potential opportunities to expand the repertoire of treatment options.

METHODS

A literature review was performed to assess the role of pro-inflammatory and anti-inflammatory cytokines in the development of neuropathic pain. Both direct and indirect therapeutic approaches that target various cytokines for pain were reviewed. The current understanding based on preclinical and clinical studies is summarized.

RESULTS AND CONCLUSIONS

In both human and animal studies, neuropathic pain has been associated with a pro-inflammatory state. Analgesic therapies involving direct manipulation of various cytokines and indirect methods to alter the balance of the immune system have been explored, although there have been few large-scale clinical trials evaluating the efficacy of immune modulators in the treatment of neuropathic pain. TNF-α is perhaps the widely studied pro-inflammatory cytokine in the context of neuropathic pain, but other pro-inflammatory (IL-1β, IL-6, and IL-17) and anti-inflammatory (IL-4, IL-10, TGF-β) signaling molecules are garnering increased interest. With better appreciation and understanding of the interaction between the immune system and neuropathic pain, novel therapies may be developed to target this condition.

Single-Shot Epidural Injections in the Management of Radicular Pain

Epidural injections are commonly used in the treatment of chronic low back pain due to symptomatic lumbar spinal disorders. The aim of the present investigation was to study their therapeutic value for different age subgroups. A consecutive series of 356 patients were treated with at least one injection, and assessed before and after injection. Significant pain reduction was observed in all age groups following a series of injections with the greatest reduction after the first one. Especially in patients younger than 50 years, pain medication could be reduced substantially. Surgery was performed in 19.4% of patients (n=69) following a series of SSPDA injections. In the current study, interlaminar steroid injections for treatment of chronic low back and radicular pain caused sufficient improvement and significant reduction of medication especially in younger patients.

Up-Regulation of Pain Behavior and Glial Activity in the Spinal Cord after Compression and Application of Nucleus Pulposus onto the Sciatic Nerve in Rats

Study Design

Experimental animal study.

Purpose

To evaluate pain-related behavior and changes in glial activity in the spinal dorsal horn after combined sciatic nerve compression and nucleus pulposus (NP) application in rats.

Overview of Literature

Mechanical compression and inflammation caused by prostaglandins and cytokines at disc herniation sites induce pain. Structural changes and pain-associated cytokines in the dorsal root ganglia and spinal dorsal horn contribute to prolonged pain. Glial cells in the spinal dorsal horn may also function in pain transmission.

Methods

The sciatic nerve was compressed with NP for 2 seconds using forceps in the NP+nerve compression group; the sham-operated group received neither compression nor NP; and the control group received no operation. Mechanical hyperalgesia was measured for 3 weeks using von Frey filaments. Glial activity in the spinal dorsal horn was examined 7 days and 14 days postsurgery using anti-glial fibrillary acidic protein and anti-Ionized calcium binding adaptor molecule-1 antibodies to detect astrocytes and microglia, respectively.

Results

Mechanical hyperalgesia was detected throughout the 14-day observation in the NP+nerve compression group, but not in control or sham-operated groups (p<0.05). Both astrocytes and microglia were significantly increased in the spinal dorsal horn of the NP+nerve compression group compared to control and sham groups on days 7 and 14 (p<0.05).

Conclusions

Nerve compression with NP application produces pain-related behavior, and up-regulates astrocytes and microglia in the spinal dorsal horn, suggesting that these glia may be related to pain transmission.

Evaluation of behavior and expression of receptor activator of nuclear factor-kappa B ligand in dorsal root Ganglia after sciatic nerve compression and application of nucleus pulposus in rats

Study Design

Experimental animal study.

Purpose

To evaluate pain-related behavior and changes in nuclear factor-kappa B (NF-kB), receptor activator of NF-kB (RANK), and ligand (RANKL) in dorsal root ganglia (DRG) after combined sciatic nerve compression and nucleus pulposus (NP) application in rats.

Overview of Literature

The pathological mechanisms underlying pain from lumbar-disc herniation have not been fully elucidated. RANKL are transcriptional regulators of inflammatory cytokines. Our aim was to evaluate pain-related behavior and RANKL expression in DRG after sciatic-nerve compression and application of NP in rats.

Methods

Mechanical hyperalgesia and RANKL expression were assessed in three groups of rats: NP+sciatic nerve compression (2 seconds), sham-operated, and controls (n=20 each). Mechanical hyperalgesia was measured every other day for 3 weeks using von Frey filaments. RANKL expression in L5 DRGs was examined at five and ten days after surgery using immunohistochemistry.

Results

Mechanical hyperalgesia was observed over the 12-day observation period in the NP+nerve compression group, but not in the control and sham-operated animal groups (p<0.05). RANKL immunoreactivity was seen in the nuclei of L5 DRG neurons, and its expression was significantly upregulated in NP+nerve compression rats compared with control and sham-operated rats (p<0.01).

Conclusions

The exposure of sciatic nerves to mechanical compression and NP produces pain-related behavior and up-regulation of RANKL in DRG neurons. RANKL may play an important role in mediating pain after sciatic nerve injury with exposure to NP.

Is there any relation between cervical cord plaques and discopathy in patients with multiple sclerosis?

INTRODUCTION

Multiple sclerosis (MS) is the most common chronic autoimmune demyelinating disease of the central nervous system. The purpose of this study is to determine the relationship between the site of the cervical discopathy and cervical spinal cord plaque in MS patients.

METHODS

This retrospective study included all patients with a definite diagnosis of MS who were treated at an outpatient clinic between September 2004 and September 2011. All patients underwent cervical magnetic resonance imaging (MRI) for primary investigation of the disease. Cervical MRI scans were evaluated for detection of any evidence of cervical discopathy and cervical MS plaques. Any correlation between the site of the MS lesions and discopathy was recorded.

RESULTS

From 536 patients who were involved in the study, 214 patients had both cervical discopathy and cervical cord plaques. In this group 148 (69.1% of patients) had cervical plaque at the same site of cervical discopathy. The number of patients with cervical cord plaque and discopathy at same site was significantly higher than those with plaque and discopathy at different sites (P<0.05).

CONCLUSION

The study data suggests a possible correlation between cervical discopathy and cervical MS plaque.

Evaluation of pain behavior and calcitonin gene-related peptide immunoreactive sensory nerve fibers in the spinal dorsal horn after sciatic nerve compression and application of nucleus pulposus in rats

STUDY DESIGN

Animal study.

OBJECTIVE

To evaluate pain behavior and neuropeptide changes in the spinal dorsal horn after sciatic nerve compression and application of nucleus pulposus (NP) in rats.

SUMMARY OF BACKGROUND DATA

The pathomechanisms of lumbar disc herniation pain have not been fully elucidated. Pain-associated neuropeptides, including substance P and calcitonin gene-related peptide (CGRP), are produced in dorsal root ganglion neurons and transported to spinal dorsal horn nerve terminals where they function in pain transmission. However, changes in CGRP-immunoreactive (IR) sensory nerve terminals have not been reported in models of disc herniation. This study evaluated pain-related behavior and changes in CGRP-IR terminals in the spinal dorsal horn after combined sciatic nerve compression and NP application.

METHODS

Five groups of rats underwent either sciatic nerve compression with NP (n = 20), application of NP only (n = 20), nerve compression only (n = 20), and sham operation with neither compression nor NP (n = 20) or no operation (controls, n = 20). Mechanical hyperalgesia was measured every second day for 3 weeks. CGRP-IR terminals in each spinal dorsal horn lamina were examined 7 and 14 days postsurgery. Pain behavior and CGRP immunoreactivity were compared among the 5 groups.

RESULTS

Mechanical hyperalgesia was found in the NP only, nerve compression only, and the NP with nerve compression groups (P ≤ 0.05). CGRP-IR nerve terminals in the superficial laminae (I and II) and the deep laminae (III-VI) significantly increased in the NP only, nerve compression only, and NP with nerve compression groups compared with control and sham groups (P ≤ 0.05). Significant mechanical hyperalgesia and increased CGRP-IR nerve terminals were found in the NP with nerve compression group compared with the NP only and nerve compression only groups (P ≤ 0.05).

CONCLUSION

Our results indicate that nerve compression plus NP application produces the most pain-related behavior. CGRP-IR nerve terminals increased in laminae I and II that transmit pain and in laminae III to VI that transmit proprioception. Findings suggest that nerve compression plus NP application induces changes in CGRP expression in the superficial and deep laminae, and these changes are partly responsible for disc herniation pain.

Evaluation of behavior and expression of NaV1.7 in dorsal root ganglia after sciatic nerve compression and application of nucleus pulposus in rats

PURPOSE

The pathomechanisms of pain resulting from lumbar disc herniation have not been fully elucidated. Prostaglandins and cytokines generated at the inflammatory site produce associated pain; however, non-steroidal anti-inflammatory drugs and steroids are sometimes ineffective in patients. Tetrodotoxin-sensitive voltage-gated sodium (NaV) channels are related to sensory transmission in primary sensory nerves. The sodium channel NaV1.7 has emerged as an attractive analgesic target. The purpose of this study was to evaluate pain-related behavior and expression of NaV1.7 in dorsal root ganglia (DRG) after combined sciatic nerve compression and nucleus pulposus (NP) application in rats.

METHODS

Rats were divided into three groups and underwent either sciatic nerve compression with NP for 2 s using forceps (n = 20), sham operation with neither compression nor NP (n = 20), or no operation (controls, n = 20). Mechanical hyperalgesia was measured every second day for three weeks using von Frey filaments. NaV1.7 expression in L5 DRG was examined 7 and 14 days after surgery using immunohistochemistry. The number of neurons immunoreactive for NaV1.7 was compared among the three groups.

RESULTS

Mechanical hyperalgesia was found over the 14-day observation in the nerve compression plus NP application group, but not in the sham-operated or control groups (P < 0.05). NaV1.7 expression in L5 DRG was up-regulated in the nerve compression plus NP application group, compared with sham-operated and control rats (P < 0.01).

CONCLUSIONS

Our results indicate that nerve compression plus NP application produces pain-related behavior. We conclude that NaV1.7 expression in DRG neurons may play an important role in mediating pain from sciatic nerves after compression injury and exposure to NP.

[Biotechnological therapies for the treatment of back pain: alternatives to corticosteroids]

In recent years, it is increasingly clear that back pain is not only caused by biomechanical problems. Currently, biologically-based local therapy concepts for the treatment of affected spinal regions as an alternative to the standard treatment with steroids are in development or in early stages of clinical application. The common features of these new therapies are to intervene in the regulation of homeostasis at various key points at the affected region and specifically to suppress or block catabolic influences as well as to provide with anti-inflammatory substances and growth factors. These include on one hand the genetically produced Biologicals such as TNF-α inhibitors and cytokine antagonists and on the other hand therapies with autologous blood preparations (Autologous Conditioned Serum [ACS], and Platelet Rich Plasma formulations [PRP]). This article presents the individual methods, gives an overview of developments and results of various studies and discusses current recommendations.

Comparison of CatWalk analysis and von Frey testing for pain assessment in a rat model of nerve crush plus inflammation

STUDY DESIGN

Assessment of pain-related behavior and immunohistology of the dorsal root ganglion in a rat model.

OBJECTIVE

To investigate pain-related behavior in a rat model of nerve crush plus inflammation using the CatWalk system.

SUMMARY OF BACKGROUND DATA

A definitive method for evaluating animal models of lumbar disease has not been established. Von Frey testing has often been used in this type of study, but the reliability remains in question. The CatWalk system is a computer-assisted apparatus for analyzing gait that provides an automated way to assess gait function during pain. However, there have been few reports using this system for models of lumbar disease.

METHODS

Fourteen rats were divided into 2 groups: a treatment group and a sham group. For the treatment group, nucleus pulposus was applied to the sciatic nerve and the sciatic nerve was pinched. Two different methods for assessment of pain-related behavior, von Frey testing and CatWalk analysis, were used before surgery and at 4 and 7 days after surgery. Immunohistochemistry was used to examine calcitonin gene-related peptide expression in L4 to L6 dorsal root ganglia.

RESULTS

No significant differences were found between the treatment and sham control groups using von Frey testing. However, significant differences in 4 parameters were found between the 2 groups using the CatWalk system (P < 0.05). The proportion of calcitonin gene-related peptide-immunoreactive neurons was higher in the treatment group than in the control group (P < 0.05).

CONCLUSION

Our results demonstrate that the CatWalk system is useful for the measurement of pain-related behavioral change in our rat model in which nociception was indicated at a cellular level. Although further studies are needed, we think that this system is a valid alternative method for the evaluation of models of lumbar disease in rodents.

Epidural administration of spinal nerves with the tumor necrosis factor-alpha inhibitor, etanercept, compared with dexamethasone for treatment of sciatica in patients with lumbar spinal stenosis: a prospective randomized study

STUDY DESIGN

Prospective randomized trial.

OBJECTIVE

To examine the effect of the tumor necrosis factor alpha (TNF-α) inhibitor, etanercept, on radicular pain by its epidural administration onto spinal nerves in patients with lumbar spinal stenosis.

SUMMARY OF BACKGROUND DATA

TNF-α is thought to play a crucial role in the radicular pain caused by lumbar disc herniation and spinal stenosis. Intravenous infusion of infliximab for sciatica has been examined in 2 studies; however, the results were equivocal.

METHODS

Eighty patients with low back and radicular leg pain were investigated. We diagnosed the patients by physical examination, and X-ray and magnetic resonance imaging. In 40 patients, we epidurally administered 2.0 mL of lidocaine and 10 mg of etanercept onto the affected spinal nerve, and 2.0 mL of lidocaine and 3.3 mg of dexamethasone was used in 40 patients. Low back pain, leg pain, and leg numbness were evaluated using a visual analogue scale (VAS) and Oswestry Disability Index (ODI) score before and for 1 month after epidural administration.

RESULTS

Low back pain, leg pain, and leg numbness in the 2 groups were not significantly different before epidural administration. Epidural administration of etanercept was more effective than dexamethasone for leg pain (3 days, and 1, 2, and 4 weeks: P < 0.05), low back pain (3 days, and 1 and 2 weeks: P < 0.05), and leg numbness (3 days, and 1 and 2 weeks: P < 0.05). No adverse event was observed in either group.

CONCLUSION

Our results indicate that epidural administration of a TNF-α inhibitor onto the spinal nerve produced pain relief, but no adverse event. TNF-α inhibitors may be useful tools for the treatment of radicular pain caused by spinal stenosis.

Update on the pathophysiology of degenerative disc disease and new developments in treatment strategies

Degenerative disc disease (DDD) continues to be a prevalent condition that afflicts populations on a global scale. The economic impact and decreased quality of life primarily stem from back pain and neurological deficits associated with intervertebral disc degeneration. Although much effort has been invested into understanding the etiology of DDD and its relationship to the onset of back pain, this endeavor is a work in progress. The purpose of this review is to provide focused discussion on several areas in which recent advances have been made. Specifically, we have categorized these advances into early, middle, and late phases of age-related or degenerative changes in the disc and into promising minimally invasive treatments, which aim to restore mechanical and biological functions to the disc.

New challenges for intervertebral disc treatment using regenerative medicine

The development of tissue engineering therapies for the intervertebral disc is challenging due to ambiguities of disease and pain mechanisms in patients, and lack of consensus on preclinical models for safety and efficacy testing. Although the issues associated with model selection for studying orthopedic diseases or treatments have been discussed often, the multifaceted challenges associated with developing intervertebral disc tissue engineering therapies require special discussion. This review covers topics relevant to the clinical translation of tissue-engineered technologies: (1) the unmet clinical need, (2) appropriate models for safety and efficacy testing, (3) the need for standardized model systems, and (4) the translational pathways leading to a clinical trial. For preclinical evaluation of new therapies, we recommend establishing biologic plausibility of efficacy and safety using models of increasing complexity, starting with cell culture, small animals (rats and rabbits), and then large animals (goat and minipig) that more closely mimic nutritional, biomechanical, and surgical realities of human application. The use of standardized and reproducible experimental procedures and outcome measures is critical for judging relative efficacy. Finally, success will hinge on carefully designed clinical trials with well-defined patient selection criteria, gold-standard controls, and objective outcome metrics to assess performance in the early postoperative period.