A systematic review and meta-analysis of biological treatments targeting tumour necrosis factor α for sciatica

Efficacy of Individualized Homeopathic Medicines in the Treatment of Sciatica Pain: Double-Blind, Randomized, Placebo-Controlled Trial

Objectives: Sciatica is a debilitating condition that causes pain in its distribution or in the lumbosacral nerve root that is connected to it. Although there are claims that homeopathy can reduce sciatica pain, systematic scientific proof is currently lacking. The objective of the trial was to determine whether individualized homeopathic medicines (IHMs) were as effective as identical-looking placebos in treating sciatica pain. Design: This is a double-blind, randomized (1:1), two parallel arms, placebo-controlled trial. Setting: The study was conducted at Mahesh Bhattacharyya Homoeopathic Medical College and Hospital, Howrah, West Bengal, India. Subjects: Sixty participants with sciatica pain were included in this study. Interventions: Verum (n = 30; IHMs plus concomitant care) versus control (n = 30; placebos plus concomitant care). Outcome measures: Primary-Sciatica Bothersome Index (SBI) and Sciatica Frequency Index (SFI) scores and secondary-Roland Morris Pain and Disability Questionnaire (RMPDQ), Short Form McGill Pain Questionnaire (SF-MPQ), and Oswestry Low Back Pain Questionnaire (OLBPQ) scores: all of them were measured at baseline, and every month, up to 3 months. Results: Intention-to-treat sample (n = 60) was analyzed. Group differences were examined by two-way (split-half) repeated measure analysis of variance, primarily accounting for between groups and time interactions, and additionally, by unpaired t tests comparing the estimates obtained individually every month. The level of significance was set at p < 0.025 and <0.05 two tailed for the primary and secondary outcomes, respectively. Group differences could not achieve significance in SBI (p = 0.044), SFI (p = 0.080), and RMPDQ scores (p = 0.134), but were significant for SF-MPQ (p = 0.007) and OLBPQ (p = 0.036). Gnaphalium polycephalum (n = 6; 10%) was the most frequently prescribed medicine. No harm, serious adverse events, or intercurrent illnesses were recorded in either of the groups. Conclusions: The primary outcome failed to demonstrate evidently that homeopathy was effective beyond placebo, and the trial remained inconclusive. Independent replications are warranted to confirm the findings. Clinical Trial Registration Number: CTRI/2020/10/028617.

Pain-resolving immune mechanisms in neuropathic pain

Interactions between the immune and nervous systems are of central importance in neuropathic pain, a common and debilitating form of chronic pain caused by a lesion or disease affecting the somatosensory system. Our understanding of neuroimmune interactions in pain research has advanced considerably. Initially considered as passive bystanders, then as culprits in the pathogenesis of neuropathic pain, immune responses in the nervous system are now established to underpin not only the initiation and progression of pain but also its resolution. Indeed, immune cells and their mediators are well-established promoters of neuroinflammation at each level of the neural pain pathway that contributes to pain hypersensitivity. However, emerging evidence indicates that specific subtypes of immune cells (including antinociceptive macrophages, pain-resolving microglia and T regulatory cells) as well as immunoresolvent molecules and modulators of the gut microbiota-immune system axis can reduce the pain experience and contribute to the resolution of neuropathic pain. This Review provides an overview of the immune mechanisms responsible for the resolution of neuropathic pain, including those involved in innate, adaptive and meningeal immunity as well as interactions with the gut microbiome. Specialized pro-resolving mediators and therapeutic approaches that target these neuroimmune mechanisms are also discussed.

Study protocol: effect of infection, Modic and inflammation on clinical outcomes in surgery for radiculopathy (EIMICOR)

BACKGROUND

Evidence indicates that inflammatory processes are involved in radicular pain as well as in resorption of herniated disc tissue. Furthermore there are indications that the presence of vertebral end plate pathology (Modic changes; MC) is associated with a negative effect on inflammation. It is hypothesized that in patients with MC, the (possibly bacterial induced) inflammation will be accompanied by pro inflammatory cytokines that worsen the outcome, and that in patients without MC, the inflammation is accompanied by cytokines that induce a resorption process to accelerate recovery.

METHODS

This prospective cohort study will include 160 lumbar and 160 cervical patients (total of 320), which are scheduled for surgery for either a lumbar or cervical herniated disc with ages between 18 and 75. The main and interaction effects of local bacterial infection (culture), inflammatory cells in disc material (immunohistology), MC (MRI), and blood biomarkers indicating inflammation or infection (blood sample evaluation) will be evaluated. Clinical parameters to be evaluated are leg pain on the 11 point NRS pain scale, Oswestry (lumbar spine) or Neck (cervical spine) Disability Index, Global Perceived Recovery, Womac Questionnaire, and medication status, at baseline, and after 6, 16, 26 and 52 weeks.

DISCUSSION

Gaining insight in the aetiology of pain and discomfort in radiculopathy caused by a herniated disc could lead to more effective management of patients. If the type of inflammatory cells shows to be of major influence on the rate of recovery, new immunomodulating treatment strategies can be developed to decrease the duration and intensity of symptoms. Moreover, identifying a beneficial inflammatory response in the disc through a biomarker in blood could lead to early identification of patients whose herniations will resorb spontaneously versus those that require surgery.

TRIAL REGISTRATION

prospectively enrolled at trialregister.nl, ID: NL8464 .

Monoclonal Antibodies for Chronic Pain Treatment: Present and Future

Chronic pain remains a major problem worldwide, despite the availability of various non-pharmacological and pharmacological treatment options. Therefore, new analgesics with novel mechanisms of action are needed. Monoclonal antibodies (mAbs) are directed against specific, targeted molecules involved in pain signaling and processing pathways that look to be very effective and promising as a novel therapy in pain management. Thus, there are mAbs against tumor necrosis factor (TNF), nerve growth factor (NGF), calcitonin gene-related peptide (CGRP), or interleukin-6 (IL-6), among others, which are already recommended in the treatment of chronic pain conditions such as osteoarthritis, chronic lower back pain, migraine, or rheumatoid arthritis that are under preclinical research. This narrative review summarizes the preclinical and clinical evidence supporting the use of these agents in the treatment of chronic pain.

Inflammation in the intervertebral disc herniation

Up until fairly recently, it was thought that sciatic pain in the lumbar herniated disc was caused by compression on the nerve root. However, the lumbar herniated disc shows mixed pictures which are difficult to explain by simple mechanical compromise. In recent years various immunology, immunohistochemistry and molecular biology studies have shown that the herniated tissue is not an inert material, but rather it Is biologically very active with the capability of expressing a series of inflammatory mediators: cytokines such as interleukin-1, interleukin-6, interleuquin-8 and tumor necrosis factor being the ones which stand out. The inflammation is not only induced by the chemical irritation of the bioactive substances released by the nucleus pulposus but also by an autoimmune response against itself. Thus, in addition to the mechanical factor, the biomechanical mediation plays an important role in the pathophysiology of sciatic pain and of radiculopathy. Through a review of a wide range of literature, we researched the cellular molecular mediators involved in this inflammatory process around the lumbar herniated disc and its involvement in sciatic pain.

Preclinical ex-vivo Testing of Anti-inflammatory Drugs in a Bovine Intervertebral Degenerative Disc Model

Discogenic low back pain (LBP) is a main cause of disability and inflammation is presumed to be a major driver of symptomatic intervertebral disc degeneration (IDD). Anti-inflammatory agents are currently under investigation as they demonstrated to alleviate symptoms in patients having IDD. However, their underlying anti-inflammatory and regenerative activity is poorly explored. The present study sought to investigate the potential of Etanercept and Tofacitinib for maintaining disc homeostasis in a preclinical intervertebral disc (IVD) organ culture model within IVD bioreactors allowing for dynamic loading and nutrient exchange. Bovine caudal IVDs were cultured in a bioreactor system for 4 days to simulate physiological or degenerative conditions: (1) Phy—physiological loading (0.02–0.2 MPa; 0.2 Hz; 2 h/day) and high glucose DMEM medium (4.5 g/L); (2) Deg+Tumor necrosis factor α (TNF-α)—degenerative loading (0.32–0.5 MPa; 5 Hz; 2 h/day) and low glucose DMEM medium (2 g/L), with TNF-α injection. Etanercept was injected intradiscally while Tofacitinib was supplemented into the culture medium. Gene expression in the IVD tissue was measured by RT-qPCR. Release of nitric oxide (NO), interleukin 8 (IL-8) and glycosaminoglycan (GAG) into the IVD conditioned medium were analyzed. Cell viability in the IVD was assessed using lactate dehydrogenase and ethidium homodimer-1 staining. Immunohistochemistry was performed to assess protein expression of IL-1β, IL-6, IL-8, and collagen type II in the IVD tissue. Etanercept and Tofacitinib downregulated the expression of IL-1β, IL-6, IL-8, Matrix metalloproteinase 1 (MMP1), and MMP3 in the nucleus pulposus (NP) tissue and IL-1β, MMP3, Cyclooxygenase-2 (COX2), and Nerve growth factor (NGF) in the annulus fibrosus (AF) tissue. Furthermore, Etanercept significantly reduced the IL-1β positively stained cells in the outer AF and NP regions. Tofacitinib significantly reduced IL-1β and IL-8 positively stained cells in the inner AF region. Both, Etanercept and Tofacitinib reduced the GAG loss to the level under physiological culture condition. Etanercept and Tofacitinib are able to neutralize the proinflammatory and catabolic environment in the IDD organ culture model. However, combined anti-inflammatory and anabolic treatment may be required to constrain accelerated IDD and relieving inflammation-induced back pain.

The contradictory effect of macrophage-related cytokine expression in lumbar disc herniations: a systematic review

PURPOSE

Sciatic symptoms due to lumbar disc herniation are likely to be caused not solely by mechanical compression of the nerve root, but also by pain-inducing elements from inflammatory processes. Key components in the inflammatory reaction are M1 and M2 macrophages, with the M1 type being associated with pro-inflammatory processes and M2 with anti-inflammatory-processes.

METHOD

The present systematic review summarizes all studies on associations between M1 and M2 macrophages and their related inflammation factors and pain symptoms in lumbar disc herniations. Literature search was performed using an optimally sensitive search string. Studies were selected for inclusion by means of predefined inclusion and exclusion criteria and subsequently graded for risk of bias. A total of 14 studies were included. Overall risk of bias was moderate (8/14), and three studies had high risk of bias and three has low risk of bias.

RESULTS

Regarding M1-related cytokines, high levels of TNF-α, TNFR1, IL-6, IL-8, and IFN-γ were all associated high VAS scores. In contrast, high levels of TNFR2 were associated with lower VAS scores. Moreover, no associations were found for IL-1a and IL-1β. Results regarding M2-related cytokines revealed the opposite: high levels of both IL-4 and IL-10 were associated with lower VAS scores. No associations were established for TGF-β. Moreover, the presence of macrophages (CD68) was negatively associated with VAS scores.

CONCLUSION

While M1-related pro-inflammatory cytokines worsen pain symptoms, M2-related anti-inflammatory cytokines alleviate pain symptoms. Nevertheless, the present evidence is limited, and further research on the underlying pathophysiological mechanism in sciatica is required. These slides can be retrieved under Electronic Supplementary Material.

Inflammatory biomarkers do not distinguish between patients with sciatica and referred leg pain within a primary care population: results from a nested study within the ATLAS cohort

Background

There is increasing interest in the role of pro-inflammatory cytokines in the pathogenesis of sciatica and whether these could be potential targets for treatment. We sought to investigate serum biomarker levels in patients with low back-related leg pain, including sciatica.

Methods

Primary care consulters aged > 18 with low back-related leg pain were recruited to a cohort study (ATLAS). Participants underwent a standardised clinical assessment, lumbar spine MRI and a subsample (n = 119) had samples taken for biomarker analysis. Participants were classified having: a) clinically confirmed sciatica or referred leg pain, and then subdivided into those with (or without) MRI confirmed nerve root compression due to disc prolapse. Seventeen key cytokines, chemokines and matrix metalloproteinases (MMPs) implicated in sciatica pathogenesis including TNFα and IL-6, were assayed in duplicate using commercial multiplex detection kits and measured using a Luminex suspension array system. Median biomarker levels were compared between the groups using a Mann Whitney U test. Multivariate logistic regression analysis was used to investigate the association between clinical measures and biomarker levels adjusted for possible confounders such as age, sex, and symptom duration.

Results

No difference was found in the serum level of any of the 17 biomarkers tested in patients with (n = 93) or without (n = 26) clinically confirmed sciatica, nor between those with (n = 44) or without (n = 49) sciatica and MRI confirmed nerve root compression.

Conclusion

In this cohort, no significant differences in serum levels of TNFα, IL-6 or any other biomarkers were seen between patients with sciatica and those with back pain with referred leg pain. These results suggest that in patients with low back-related leg pain, serum markers associated with inflammation do not discriminate between patients with or without clinically confirmed sciatica or between those with or without evidence of nerve root compression on MRI.

Biologic Drugs as Analgesics for the Management of Low Back Pain and Sciatica

Objective

To discuss the current knowledge on the impact of commonly used biologic agents (i.e., anti–tumor necrosis factor–alpha [anti-TNF-α] and anti–nerve growth factor [anti-NGF]) in the management of low back pain with or without sciatica.

Methods

A narrative literature review of studies investigating the use of biologic agents for the management of low back pain and sciatica was conducted. We searched MEDLINE and EMBASE for English language publications. A hand-search of reference lists of relevant studies was also performed.

Results

Although some observational studies showed that inhibition of TNF-α reduced pain and improved function, randomized controlled trials and a meta-analysis failed to demonstrate the superiority of anti-TNF-α over placebo in this regard. Anti-TNF-α, however, reduced the risk of having invasive procedures such as discectomy and radicular block in cases of sciatica. Conversely, controlled studies showed moderate pain reduction and mild functional improvement with anti-NGF administration, but the side effect profile of anti-NGF was unfavorable compared with placebo.

Conclusions

Overall, anticytokine treatments have limited efficacy in patients with chronic low back pain with or without sciatica. However, larger and better-designed studies may need to be performed in specific patient subpopulations. Low back pain is particularly disabling in younger patients. This group therefore represents a potential target population for investigating the effectiveness of anticytokine therapies, especially where other pharmacological and nonpharmacological management strategies have failed.

Targeting toll-like receptor-4 (TLR4)-an emerging therapeutic target for persistent pain states

Toll-like receptors (TLRs) are a family of pattern recognition receptors that initiate signaling in innate and adaptive immune pathways. The highly conserved family of transmembrane proteins comprises an extracellular domain that recognizes exogenous and endogenous danger molecules and an ectodomain that activates downstream pathways in response. Recent studies suggest that continuous activation or dysregulation of TLR signaling may contribute to chronic disease states. The receptor is located not only on inflammatory cells (meningeal and peripheral macrophages) but on neuraxial glia (microglia and astrocytes), Schwann cells, fibroblasts, dorsal root ganglia, and dorsal horn neurons. Procedures blocking TLR functionality have shown pronounced effects on pain behavior otherwise observed in models of chronic inflammation and nerve injury. This review addresses the role of TLR4 as an emerging therapeutic target for the evolution of persistent pain and its role in noncanonical signaling, mediating anomalous pro-algesic actions of opiates. Accordingly, molecules targeting inhibition of this receptor have promise as disease-modifying and opioid-sparing alternatives for persistent pain states.

Lessons learnt from a discontinued randomised controlled trial: adalimumab injection compared with placebo for patients receiving physiotherapy treatment for sciatica (Subcutaneous Injection of Adalimumab Trial compared with Control: SCIATiC)

BACKGROUND

Adalimumab, a biological treatment targeting tumour necrosis factor α, might be useful in sciatica. This paper describes the challenges faced when developing a new treatment pathway for a randomised controlled trial of adalimumab for people with sciatica, as well as the reasons why the trial discussed was stopped early.

METHODS

A pragmatic, parallel group, randomised controlled trial with blinded (masked) participants, clinicians, outcome assessment and statistical analysis was conducted in six UK sites. Participants were identified and recruited from general practices, musculoskeletal services and outpatient physiotherapy clinics. They were adults with persistent symptoms of sciatica of 1 to 6 months' duration with moderate to high level of disability. Eligibility was assessed by research physiotherapists according to clinical criteria, and participants were randomised to receive two doses of adalimumab (80 mg then 40 mg 2 weeks later) or saline placebo subcutaneous injections in the posterior lateral thigh. Both groups were referred for a course of physiotherapy. Outcomes were measured at baseline, 6-week, 6-month and 12-month follow-up. The main outcome measure was disability measured using the Oswestry Disability Index. The planned sample size was 332, with the first 50 in an internal pilot phase.

RESULTS

The internal pilot phase was discontinued after 10 months from opening owing to low recruitment (two of the six sites active, eight participants recruited). There were several challenges: contractual delays; one site did not complete contract negotiations, and two sites signed contracts shortly before trial closure; site withdrawal owing to patient safety concerns; difficulties obtaining excess treatment costs; and in the two sites that did recruit, recruitment was slower than planned because of operational issues and low uptake by potential participants.

CONCLUSIONS

Improved patient care requires robust clinical research within contexts in which treatments can realistically be provided. Step changes in treatment, such as the introduction of biologic treatments for severe sciatica, raise complex issues that can delay trial initiation and retard recruitment. Additional preparatory work might be required before testing novel treatments. A randomised controlled trial of tumour necrosis factor-α blockade is still needed to determine its cost-effectiveness in severe sciatica.

TRIAL REGISTRATION

Current Controlled Trials, ISRCTN14569274 . Registered on 15 December 2014.

Bed Rest for Sciatica: A Closer Look at the Evidence

When managing acute nonspecific low back pain (LBP), bed rest is commonly discouraged as a form of therapy. However, when the picture includes radiating leg pain arising from the lumbar spine, the evidence is less robust. In this Viewpoint, the authors explore evidence pertaining to sciatica, defined as "low back pain with verified neurological deficits," and bed rest as part of the management of radiating leg pain. J Orthop Sports Phys Ther 2018;48(6):436-438. doi:10.2519/jospt.2018.0609.

Subcutaneous Injection of Adalimumab Trial compared with Control (SCIATiC): a randomised controlled trial of adalimumab injection compared with placebo for patients receiving physiotherapy treatment for sciatica

BACKGROUND

Biological treatments such as adalimumab (Humira^®; AbbVie Ltd, Maidenhead, UK) are antibodies targeting tumour necrosis factor alpha, released from ruptured intervertebral discs, which might be useful in sciatica. Recent systematic reviews concluded that they might be effective, but that a definitive randomised controlled trial was needed. Usual care in the NHS typically includes a physiotherapy intervention.

OBJECTIVES

To test whether or not injections of adalimumab plus physiotherapy are more clinically effective and cost-effective than injections of saline plus physiotherapy for patients with sciatica.

DESIGN

Pragmatic, parallel-group, randomised controlled trial with blinded participants and clinicians, and an outcome assessment and statistical analysis with concurrent economic evaluation and internal pilot.

SETTING

Participants were referred from primary care and musculoskeletal services to outpatient physiotherapy clinics.

PARTICIPANTS

Adults with persistent symptoms of sciatica of 1-6 months' duration and with moderate to high levels of disability. Eligibility was assessed by research physiotherapists according to clinical criteria for diagnosing sciatica.

INTERVENTIONS

After a second eligibility check, trial participants were randomised to receive two doses of adalimumab (80 mg and then 40 mg 2 weeks later) or saline injections. Both groups were referred for a course of physiotherapy.

MAIN OUTCOME MEASURES

Outcomes were measured at the start, and after 6 weeks' and 6 months' follow-up. The main outcome measure was the Oswestry Disability Index (ODI). Other outcomes: leg pain version of the Roland-Morris Disability Questionnaire, Sciatica Bothersomeness Index, EuroQol-5 Dimensions, 5-level version, Hospital Anxiety and Depression Scale, resource use, risk of persistent disabling pain, pain trajectory based on a single question, Pain Self-Efficacy Questionnaire, Tampa Scale of Kinesiophobia and adverse effects.

SAMPLE SIZE

To detect an effect size of 0.4 with 90% power, a 5% significance level for a two-tailed t-test and 80% retention rate, 332 participants would have needed to be recruited.

ANALYSIS PLAN

The primary effectiveness analysis would have been linear mixed models for repeated measures to measure the effects of time and group allocation. An internal pilot study would have involved the first 50 participants recruited across all centres. The primary economic analysis would have been a cost-utility analysis.

RESULTS

The internal pilot study was discontinued as a result of low recruitment after eight participants were recruited from two out of six sites. One site withdrew from the study before recruitment started, one site did not complete contract negotiations and two sites signed contracts shortly before trial closure. In the two sites that did recruit participants, recruitment was slow. This was partly because of operational issues, but also because of a low rate of uptake from potential participants.

LIMITATIONS

Although large numbers of invitations were sent to potential participants, identified by retrospective searches of general practitioner (GP) records, there was a low rate of uptake. Two sites planned to recruit participants during GP consultations but opened too late to recruit any participants.

CONCLUSION

The main failure was attributable to problems with contracts. Because of this we were not able to complete the internal pilot or to test all of the different methods for primary care recruitment we had planned. A trial of biological therapy in patients with sciatica still needs to be done, but would require a clearer contracting process, qualitative research to ensure that patients would be willing to participate, and simpler recruitment methods.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN14569274.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 60. See the NIHR Journals Library website for further project information.

A Phase II Randomized, Double-Blind, Placebo-Controlled Safety and Efficacy Study of Lenalidomide in Lumbar Radicular Pain with a Long-Term Open-Label Extension Phase

Objective

This phase II study assessed lenalidomide efficacy and safety.

Design

Three-phase core study: 14-day prerandomization, 12-week treatment, and 52-week open-label extension.

Setting

Fourteen US centers from July 2005 to July 2007.

Subjects

Chronic lumbar radicular pain patients without history of nerve injury or deficit.

Methods

Subjects were randomized (1:1) to double-blind treatment with lenalidomide 10 mg or placebo once daily for 12 weeks, followed by a 52-week open-label extension. A 12-week, single-center, randomized-withdrawal (1:2, lenalidomide:placebo), exploratory study with open-label extension was undertaken in 12 subjects from the core extension who were naïve to neuropathic medications and with at least a two-point decrease from baseline average daily Pain Intensity-Numerical Rating Scale score.

Results

Of 180 subjects enrolled, 176 had at least one postbaseline measure; 132 completed the 12-week treatment phase. In the core study, no statistically significant difference in Pain Intensity-Numerical Rating Scale mean change (-0.02, P  =   0.958) was observed at week 12 between lenalidomide and placebo; proportions achieving pain reduction at week 12 and other secondary measures were comparable between lenalidomide and placebo. In the exploratory study, week 12 mean changes in Pain Intensity-Numerical Rating Scale scores were -0.05 (lenalidomide: N = 3) and 2.11 (placebo: N = 8). Mean changes in Brief Pain Inventory-short form interference scores were -3.33 and 8.38, respectively; scores at six months were maintained or decreased in 10 of 12 subjects.

Conclusions

While this study does not support lenalidomide use in an unselected lumbar radicular pain population, an immunomodulating agent may relieve pain in select subjects naïve to neuropathic pain medications.

ClinicalTrials.gov identifier: NCT00120120.

Increased local expressions of CX3CL1 and CCL2 are related to clinical severity in lumbar disk herniation patients with sciatic pain

Background

Chemokines have been identified to be involved in the modulation of pain through both peripheral and central mechanisms. However, the role of chemokines in lumbar disk herniation (LDH) with sciatic pain remains unknown.

Objective

The current study was performed to explore the expression of two most commonly studied chemokines CX3CL1 and CCL2 and assess their associations with clinical severity in LDH patients with sciatic pain.

Methods

The soft tissues around nerve root (STANR), annulus fibrosus (AF), and nucleus pulposus (NP) biopsies were obtained from 36 LDH patients with chronic sciatic pain and 10 scoliosis patients (painless controls). The serum and local expressions of CX3CL1 and CCL2 were determined using enzyme-linked immunosorbent assay and Western blot analysis, respectively. The visual analog scale (VAS) scores for low back pain and lower extremity pain and Japanese Orthopaedic Association (JOA) scores were recorded on the day of hospital admission to evaluate the clinical severity. LDH patients with sciatic pain were divided into severe pain (SP) group (VAS ≥7; n=18) and mild-to-moderate pain (M-MP) group (VAS <7; n=18) for lower extremity pain.

Results

Local expressions instead of CX3CL1 and CCL2 in STANR, AF, and NP were significantly higher in the SP group than in M-MP compared with scoliosis painless group. Expressions of both CX3CL1 and CCL2 in STANR and AF were positively correlated with VAS scores for lower extremity and for low back pain, respectively. In addition, CX3CL1 and CCL2 expressions in STANR were negatively associated with JOA scores. There were no significant differences of serum CX3CL1 and CCL2 levels among SP group, M-MP group, and scoliosis painless group.

Conclusion

Both CX3CL1 and CCL2 may play important roles in maintaining pain in LDH patients. Local blockade of CX3CL1 and CCL2 in LDH patients with persistent pain deserves further intensive study.

Monoclonal antibodies for chronic pain: a practical review of mechanisms and clinical applications

Context

Monoclonal antibodies are being investigated for chronic pain to overcome the shortcomings of current treatment options.

Objective

To provide a practical overview of monoclonal antibodies in clinical development for use in chronic pain conditions, with a focus on mechanisms of action and relevance to specific classes.

Methods

Qualitative review using a systematic strategy to search for randomized controlled trials, systematic and nonsystematic (narrative) reviews, observational studies, nonclinical studies, and case reports for inclusion. Studies were identified via relevant search terms using an electronic search of MEDLINE via PubMed (1990 to June 2017) in addition to hand-searching reference lists of retrieved systematic and nonsystematic reviews.

Results

Monoclonal antibodies targeting nerve growth factor, calcitonin gene-related peptide pathways, various ion channels, tumor necrosis factor-α, and epidermal growth factor receptor are in different stages of development. Mechanisms of action are dependent on specific signaling pathways, which commonly involve those related to peripheral neurogenic inflammation. In clinical studies, there has been a mixed response to different monoclonal antibodies in several chronic pain conditions, including migraine, neuropathic pain conditions (e.g., diabetic peripheral neuropathy), osteoarthritis, chronic back pain, ankylosing spondylitis, and cancer. Adverse events observed to date have generally been mild, although further studies are needed to ensure safety of monoclonal antibodies in early stages of development, especially where there is an overlap with non-pain-related pathways. High acquisition cost remains another treatment limitation.

Conclusion

Monoclonal antibodies for chronic pain have the potential to overcome the limitations of current treatment options, but strategies to ensure their appropriate use need to be determined.

Developments in intervertebral disc disease research: pathophysiology, mechanobiology, and therapeutics

Low back pain is a leading cause of disability worldwide and the second most common cause of physician visits. There are many causes of back pain, and among them, disc herniation and intervertebral disc degeneration are the most common diagnoses and targets for intervention. Currently, clinical treatment outcomes are not strongly correlated with diagnoses, emphasizing the importance for characterizing more completely the mechanisms of degeneration and their relationships with symptoms. This review covers recent studies elucidating cellular and molecular changes associated with disc mechanobiology, as it relates to degeneration and regeneration. Specifically, we review findings on the biochemical changes in disc diseases, including cytokines, chemokines, and proteases; advancements in disc disease diagnostics using imaging modalities; updates on studies examining the response of the intervertebral disc to injury; and recent developments in repair strategies, including cell-based repair, biomaterials, and tissue engineering. Findings on the effects of the omega-6 fatty acid, linoleic acid, on nucleus pulposus tissue engineering are presented. Studies described in this review provide greater insights into the pathogenesis of disc degeneration and may define new paradigms for early or differential diagnostics of degeneration using new techniques such as systemic biomarkers. In addition, research on the mechanobiology of disease enriches the development of therapeutics for disc repair, with potential to diminish pain and disability associated with disc degeneration.

Cerebrospinal Fluid Cytokines and Neurotrophic Factors in Human Chronic Pain Populations: A Comprehensive Review

Chronic pain is a prevalent and debilitating condition, conveying immense human burden. Suffering is caused not only by painful symptoms, but also through psychopathological and detrimental physical consequences, generating enormous societal costs. The current treatment armamentarium often fails to achieve satisfying pain relief; thus, research directed toward elucidating the complex pathophysiological mechanisms underlying chronic pain syndromes is imperative. Central neuroimmune activation and neuroinflammation have emerged as driving forces in the transition from acute to chronic pain, leading to central sensitization and decreased opioid efficacy, through processes in which glia have been highlighted as key contributors. Under normal conditions, glia exert a protective role, but in different pathological states, a deleterious role is evident--directly and indirectly modulating and enhancing pain transmission properties of neurons, and shaping synaptic plasticity in a dysfunctional manner. Cytokines and neurotrophic factors have been identified as pivotal mediators involved in neuroimmune activation pathways and cascades in various preclinical chronic pain models. Research confirming these findings in humans has so far been scarce, but this comprehensive review provides coherent data supporting the clear association of a mechanistic role of altered central cytokines and neurotrophic factors in a number of chronic pain states despite varying etiologies. Given the importance of these factors in neuropathic and inflammatory chronic pain states, prospective therapeutic strategies, and directions for future research in this emerging field, are outlined.

Clinical significance of tumor necrosis factor-α inhibitors in the treatment of sciatica: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Currently, no satisfactory treatment is available for sciatica caused by herniated discs and/or spinal stenosis. The objective of this study is to assess the value of tumor necrosis factor (TNF)-α inhibitors in the treatment of sciatica.

METHODS

Without language restrictions, we searched PubMed, OVID, EMBASE, the Web of Science, the Clinical Trials Registers, the Cochrane Central Register of Controlled Trials and the China Academic Library and Information System. We then performed a systematic review and meta-analysis on the enrolled trials that met the inclusion criteria.

RESULTS

Nine prospective randomized controlled trials (RCTs) and two before-after controlled trials involving 531 patients met our inclusion criteria and were included in this study. Our systematic assessment and meta-analysis demonstrated that in terms of the natural course of the disease, compared with the control condition, TNF-α inhibitors neither significantly relieved lower back and leg pain (both p > 0.05) nor enhanced the proportion of patients who felt overall satisfaction (global perceived effect (satisfaction)) or were able to return to work (return to work) (combined endpoint; p > 0.05) at the short-term, medium-term and long-term follow-ups. In addition, compared with the control condition, TNF-α inhibitors could reduce the risk ratio (RR) of discectomy or radicular block (combined endpoint; RR = 0.51, 95% CI 0.26 to 1.00, p = 0.049) at medium-term follow-up, but did not decrease RR at the short-term (RR = 0.64, 95% CI 0.17 to 2.40, p = 0.508) and long-term follow-ups (RR = 0.64, 95% CI 0.40 to 1.03, p = 0.065).

CONCLUSION

The currently available evidence demonstrated that other than reducing the RR of discectomy or radicular block (combined endpoint) at medium-term follow-up, TNF-α inhibitors showed limited clinical value in the treatment of sciatica caused by herniated discs and/or spinal stenosis.