A comparative immunohistochemical study of inflammatory cells in acute-stage and chronic-stage disc herniations

The association between inflammatory biomarkers and low back disorder: a systematic review and meta-analysis

INTRODUCTION

Low back disorder (LBD) is a major cause of disability worldwide. Inflammation results in proliferation of cytokines or consequent degradation products (collectively known as inflammatory biomarkers) that activate pain pathways which can result in non-specific LBD. This systematic review and meta-analysis aim to evaluate the relationship between inflammatory biomarkers and clinical outcomes in patients with LBD.

METHODS

The PRISMA guideline was followed for the systematic reivew. Three online databases were searched. Four RCTs and sixteen observational studies with 1142 LBD patients were analysed. The primary outcomes were back and leg pain scores, back-specific disability scores and expression of inflammatory biomarkers. Standardized mean difference (SMD) and their 95% confidence intervals (CI) were evaluated. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to summarize the strength of evidence.

RESULTS

Four RCTs and sixteen observational studies were included in the analysis of 1142 patients with LBD. There was a statistically significant reduction in back pain score and IL-1 beta and increase in the expression of CTX-1 and IL-10 levels post treatment. There was a significant relationship between increase in the expression of MCP- and reduction in the expression of hsCRP with increase in back pain. Significant relationship was also observed between increase in the expression of MCP-1 and reduction in the expression of IL-6 with increase in leg pain. Increase in the expression of IL-8 and reduction in the expression of hsCRP was also associated with increased disability score.

CONCLUSION

Inflammatory biomarkers play a significant role in the pathogenesis of LBD. CTX-1, IL-10 and IL-1 beta may be responsible for the decrease in back pain scores post treatment. There is a relationship between MCP-1, IL-6, IL-8 and hsCRP with clinical and functional assessments for LBD. Further studies will improve understanding of the pathogenesis of LBD and aid in targeted management strategies.

Contribution of immune cells to intervertebral disc degeneration and the potential of immunotherapy

Substantial evidence supports that chronic low back pain is associated with intervertebral disc degeneration (IDD), which is accompanied by decreased cell activity and matrix degradation. The role of immune cells, especially macrophages, in a variety of diseases has been extensively studied; therefore, their role in IDD has naturally attracted widespread scholarly interest. The IVD is considered to be an immunologically-privileged site given the presence of physical and biological barriers that include an avascular microenvironment, a high proteoglycan concentration, high physical pressure, the presence of apoptosis inducers such as Fas ligand, and the presence of notochordal cells. However, during IDD, immune cells with distinct characteristics appear in the IVD. Some of these immune cells release factors that promote the inflammatory response and angiogenesis in the disc and are, therefore, important drivers of IDD. Although some studies have elucidated the role of immune cells, no specific strategies related to systemic immunotherapy have been proposed. Herein, we summarize current knowledge of the presence and role of immune cells in IDD and consider that immunotherapy targeting immune cells may be a novel strategy for alleviating IDD symptoms.

Correlations of Disc Tissue Pathological Changes With Pfirrmann Grade in Patients With Disc Herniation Treated With Microdiscectomy

BACKGROUND

To reveal whether pathological disc changes (vascularization, inflammation, disc aging and senescence as assessed with immunohistopathological CD34, CD68, brachyury and P53 staining densities respectively) are associated with the extent of disease (Pfirrmann grade) and lumbar radicular pain in patients with lumbar disc herniation. We selectively included a homogenous group of 32 patients (16 males and 16 females) with single-level sequestered discs who had disease stages between Pfirrmann grades I to IV and excluded patients with the complete collapse of the disc space to determine histopathological correlations of the disease more precisely.

MATERIALS AND METHODS

Pathological assessments were performed on surgically excised disc specimens stored in a -80°C refrigerator. Preoperative and postoperative pain intensities were determined with visual analog scales (VASs). Pfirrmann disc degeneration grades were determined on routine T2-weighted magnetic resonance imaging (MRI).

RESULTS

Stainings were especially observed with CD34 and CD68, which positively correlated with each other and Pfirrmann grading but not with VAS scores or patients' age. Weak nuclear staining with brachyury was observed in 50% of patients and did not correlate with disease features. Focal weak staining with P53 was only seen in the disc specimen of two patients.

CONCLUSIONS

In the pathogenesis of disc disease, inflammation may trigger angiogenesis. The subsequent aberrant increase of oxygen perfusion in the disc cartilage may cause further damage, as the disc tissue is adapted to hypoxia. This vicious cycle of inflammation and angiogenesis may be a future innovative therapeutic target for chronic degenerative disc disease.

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.

Clinical features as predictors of histologically confirmed inflammation in patients with lumbar disc herniation with associated radiculopathy

Background

An understanding of the clinical features of inflammation in low back pain with or without leg symptoms may allow targeted evaluations of anti-inflammatory treatment in randomised-controlled-trials and clinical practice.

Purpose

This study evaluated the diagnostic accuracy of clinical features to predict the presence/absence of histologically confirmed inflammation in herniated disc specimens removed at surgery in patients with lumbar disc herniation and associated radiculopathy (DHR).

Study design

Cohort Study.

Methods

Disc material from patients with DHR undergoing lumbar discectomy was sampled and underwent histological/immunohistochemistry analyses. Control discs were sampled from patients undergoing surgical correction for scoliosis. Baseline assessment comprising sociodemographic factors, subjective examination, physical examination and psychosocial screening was conducted and a range of potential clinical predictors of inflammation developed based on the existing literature. Multi-variate analysis was undertaken to determine diagnostic accuracy.

Results

Forty patients with DHR and three control patients were recruited. None of the control discs had evidence of inflammation compared to 28% of patients with DHR. Predictors of the presence of histologically confirmed inflammation included back pain < 5/10, symptoms worse the next day after injury, lumbar flexion range between 0 and 30° and a positive clinical inflammation score (at least 3 of: constant symptoms, morning pain/stiffness greater than 60-min, short walking not easing symptoms and significant night symptoms). The model achieved a sensitivity of 90.9%, a specificity of 92.9%, and a predictive accuracy of 92.3%.

Conclusion

In a sample of patients with lumbar DHR a combination of clinical features predicted the presence or absence of histologically confirmed inflammation.

Clinical relevance

These clinical features may enable targeted anti-inflammatory treatment in future RCTs and in clinical practice.

Polarization of Macrophages in Epidural Inflammation Induced by Canine Intervertebral Disc Herniation

Introduction: Canine interverterbral disc (IVD), although physiologically acellular, displays an inflammatory cell population consisting almost exclusively of macrophages (Mϕ) when acutely herniated. Mϕ encompass a heterogenous cell population, roughly divided into classically (M1) or alternatively activated (M2)Mϕ. Polarization into M1 Mϕ leads to strong antimicrobial activity and pro-inflammatory response. In contrast, M2Mϕ exibit anti-inflammatory function and regulate wound healing. The purpose of this study was to characterize the phenotype of the Mϕ population present in naturally occurring IVD herniation.

Materials and Methods: IVD material of dogs with IVD disease was collected during standard decompressive surgery. A negative control consisting of IVD material of dogs without IVD degeneration and a positive control consisting of canine liver and lymph node samples were also included. All samples were embedded in OCT and shock frozen. Eight micrometer cryostat sections were prepared, air dried and immunostained without prefixation or permeabilization. CD14 was used as marker Mϕ, MHCII for M1Mϕ and CD206 for M2Mϕ.

Results: Fifteen samples of dogs with IVD herniation, 10 negative, and 5 positive control samples were obtained. No positive cell was found in the negative control group. The positive control group displayed several MHCII and CD206 positive cells, all of them being simultaneously positive to CD14. All herniated samples displayed a mixed population of M1Mϕ and M2Mϕ, and some sparse Mϕ displaying markers for both M1 and M2Mϕ simultaneously.

Conclusion: The mixed phenotype encountered shows the plasticity and dynamism of Mϕ and evidences the chronic component of IVD disease despite its acute clinical presentation.

Lumbar disc extrusions reduce faster than bulging discs due to an active role of macrophages in sciatica

OBJECTIVE

This retrospective observational histological study aims to associate the size and type of disc herniation with the degree of macrophage infiltration in disc material retrieved during disc surgery in patients with sciatica.

METHODS

Disc tissue of 119 sciatica patients was embedded in paraffin and stained with hematoxylin and CD68. Tissue samples were categorized as mild (0-10/cm2), moderate (10-100/cm2), and considerable (> 100/cm2) macrophage infiltration. All 119 patients received an MRI at baseline, and 108 received a follow-up MRI at 1-year. MRIs were reviewed for the size and type of the disc herniations, and for Modic changes in the vertebral endplates.

RESULTS

Baseline characteristics and duration of symptoms before surgery were comparable in all macrophage infiltration groups. The degree of macrophage infiltration was not associated with herniation size at baseline, but significantly associated with reduction of size of the herniated disc at 1-year post surgery. Moreover, the degree of macrophage infiltration was higher in extrusion in comparison with bulging (protrusion) of the disc. Results were comparable in patients with and without Modic changes.

CONCLUSION

Macrophage infiltration was positively associated with an extruded type of disc herniation as well as the extent of reduction of the herniated disc during 1-year follow-up in patients with sciatica. This is an indication that the macrophages play an active role in reducing herniated discs. An extruded disc herniation has a larger surface for the macrophages to adhere to, which leads to more size reduction.

The Evolving Case Supporting Individualised Physiotherapy for Low Back Pain

Low-back pain (LBP) is one of the most burdensome health problems in the world. Guidelines recommend simple treatments such as advice that may result in suboptimal outcomes, particularly when applied to people with complex biopsychosocial barriers to recovery. Individualised physiotherapy has the potential of being more effective for people with LBP; however, there is limited evidence supporting this approach. A series of studies supporting the mechanisms underpinning and effectiveness of the Specific Treatment of Problems of the Spine (STOPS) approach to individualised physiotherapy have been published. The clinical and research implications of these findings are presented and discussed. Treatment based on the STOPS approach should also be considered as an approach to individualised physiotherapy in people with LBP.

Disc inflammation and Modic changes show an interaction effect on recovery after surgery for lumbar disc herniation

Purpose

To study the interaction between Modic changes (MC) and inflammation by macrophages in the disc, in relation to clinical symptoms before and after discectomy for lumbar disc herniation.

Methods

Disc tissue was embedded in paraffin and stained with haematoxylin and CD68. Subsequently, tissue samples were categorized for degree of inflammation. Type of MC was scored on MRI at baseline. Roland Disability Questionnaire (RDQ) score and visual analogue scale for back pain and leg pain separately were considered at baseline and 1-year follow-up post-surgery. Main and interaction effects of MC and inflammation were tested against clinical outcome questionnaires. In addition, this analysis was repeated in bulging and extruded discs separately.

Results

Disc material and MRI’s of 119 patients were retrieved and analysed. Forty-eight patients demonstrated mild inflammation, 45 showed moderate inflammation, and 26 showed considerable inflammation. In total, 49 out of 119 patients demonstrated MC. Grade of disc inflammation did not associate with the presence of MC. At baseline, no main or interaction effects of MC and inflammation were found on the clinical scores. However, during follow-up after discectomy, significant interaction effects were found for RDQ score: Only in patients with MC at baseline, patients remained significantly more disabled (3.2 points p = 0.006) if they showed considerable disc inflammation compared to patients with mild inflammation. The additional analysis showed similar results in extruded discs, but no significant effects in bulging discs.

Conclusions

An interaction effect of MC and disc inflammation by macrophages is present. Only in patients with MC, those with considerable inflammation recover less satisfactory during follow-up after surgery.

Graphic abstract

These slides can be retrieved under Electronic Supplementary Material.

Gadolinium Enhancement Is Not Associated With Disc Inflammation in Patients With Sciatica

STUDY DESIGN

Retrospective observational histological study.

OBJECTIVE

To evaluate the reliability of gadolinium enhancement as a marker for inflammation by associating gadolinium enhancement findings with the degree of inflammation as measured by macrophage infiltration in disc material retrieved during disc surgery in patients with sciatica.

SUMMARY OF BACKGROUND DATA

Disc inflammation often occurs in sciatica patients, a noninvasive tool that is used to assess disc inflammation is Gadolinium enhanced MR imaging.

METHODS

Disc tissue was retrieved from patients in the Sciatica trial (N = 119), a multicenter randomized controlled trial in patients with sciatica. Disc tissue was embedded in paraffin and stained with hematoxylin and CD68. Tissue samples were categorized as mild (0-10 macrophages/cm), moderate (10-100 macrophages/cm), and considerable (>100 macrophages/cm) inflammation. Of the 119 MRIs, 96 were additionally performed with contrast-enhanced gadolinium.

RESULTS

Seventy-four patients showed gadolinium enhancement of the disc herniation and 26 of the nerve root. Degree of inflammation by macrophages was not associated with gadolinium enhancement of nerve roots or herniated discs. These results did not change if the patient groups with and without Modic type 2 changes were evaluated separately. Furthermore, no associations were observed between gadolinium enhancement and presence of Modic type 2 changes.

CONCLUSION

This study found gadolinium enhanced MRI findings to be unreliable as an indicator for inflammation of disc herniation or nerve root in patients with sciatica.

LEVEL OF EVIDENCE

2.

Nerves and blood vessels in degenerated intervertebral discs are confined to physically disrupted tissue

Nerves and blood vessels are found in the peripheral annulus and endplates of healthy adult intervertebral discs. Degenerative changes can allow these vessels to grow inwards and become associated with discogenic pain, but it is not yet clear how far, and why, they grow in. Previously we have shown that physical disruption of the disc matrix, which is a defining feature of disc degeneration, creates free surfaces which lose proteoglycans and water, and so become physically and chemically conducive to cell migration. We now hypothesise that blood vessels and nerves in degenerated discs are confined to such disrupted tissue. Whole lumbar discs were obtained from 40 patients (aged 37-75 years) undergoing surgery for disc herniation, disc degeneration with spondylolisthesis or adolescent scoliosis ('non-degenerated' controls). Thin (5-μm) sections were stained with H&E and toluidine blue for semi-quantitative assessment of blood vessels, fissures and proteoglycan loss. Ten thick (30-μm) frozen sections from each disc were immunostained for CD31 (an endothelial cell marker), PGP 9.5 and Substance P (general and nociceptive nerve markers, respectively) and examined by confocal microscopy. Volocity image analysis software was used to calculate the cross-sectional area of each labelled structure, and its distance from the nearest free surface (disc periphery or internal fissure). Results showed that nerves and blood vessels were confined to proteoglycan-depleted regions of disrupted annulus. The maximum distance of any blood vessel or nerve from the nearest free surface was 888 and 247 μm, respectively. Blood vessels were greater in number, grew deeper, and occupied more area than nerves. The density of labelled blood vessels and nerves increased significantly with Pfirrmann grade of disc degeneration and with local proteoglycan loss. Analysing multiple thick sections with fluorescent markers on a confocal microscope allows reliable detection of thin filamentous structures, even within a dense matrix. We conclude that, in degenerated and herniated discs, blood vessels and nerves are confined to proteoglycan-depleted regions of disrupted tissue, especially within annulus fissures.

The surgery and early postoperative radicular pain in cases with multifocal lumbar disc herniation

Persistence of postoperative radicular pain after surgery for multifocal disc herniation (MFDH) is a clinical problem. This study aims to evaluate the effects of a combined treatment approach compared with unilateral stabilization on early postoperative radicular pain in patients with MFDH.Age, sex, level of operation, clinical findings, and radicular pain visual analogue scale (VAS) scores before surgery in the early postoperative period and at 3 months after surgery were retrospectively reviewed for 20 cases of multifocal lumbar disc herniation. The combined approach (translaminar and far lateral) was used for 13 cases. Seven cases underwent transforaminal lumbar interbody fusion (TLIF) and unilateral transpedicular stabilization following total facetectomy.The mean age of the sample was 49.4 ± 10.1 years and the female-to-male ratio was 8:12. The mean VAS scores for radicular pain in cases treated with the combined approach were 8.2, 4.07, and 2.3 in the preoperative and early postoperative periods and 3 months after surgery, respectively. The mean score for radicular pain improved by 50.4% in the early postoperative period and by 72% in the late postoperative period. The mean VAS scores for radicular pain in cases who underwent TLIF and unilateral stabilization after facetectomy were 8.4, 2.1, and 1.4 in the preoperative and early postoperative periods and 3 months after surgery, respectively. The mean VAS score for radicular pain improved by 75% in the early postoperative period and by 83.3% in the late postoperative period.The combined approach is an effective alternative in cases with MFDH. TLIF and unilateral segmental stabilization provide substantial decompression and eliminate mechanical compression by conserving the height of the intervertebral foramen in the event that sufficient decompression is unable to obtain. We suggest that elimination of chemical mediators, particularly those causing pain in the dorsal ganglion, contributes to the absence of early radicular pain.

Evaluation of ceruloplasmin levels in patients with lumbar disc herniation

BACKGROUND

Chronic inflammation is believed to have a role in the development of lumbar disc herniation (LDH). Ceruloplasmin (CP), an acute phase protein, is known to limit inflammation.

OBJECTIVE

To evaluate CP levels in patients with LDH.

METHODS

Thirty-five patients with LDH and 35 healthy individuals were enrolled in the study. Participants were divided into two groups; group 1 (n = 35) consisted of patients with LDH, and group 2 (n = 35) consisted of healthy subjects. Surgery specimens were taken from all patients who underwent LDH-related surgery. CP levels were measured in both blood and tissue samples. Pain intensity was evaluated using a visual analog scale (VAS).

RESULTS

There were no significant differences in gender, age, or body mass index between the control and LDH patients (p > 0.05 for all). Compared with the control patients, LDH patients had significantly higher serum CP levels (p < 0.001). In LDH patients, tissue CP levels were significantly higher than serum levels (p < 0.001). According to bivariate analysis, the serum CP levels were significantly correlated with the VAS score in group 1 (r = 0.491, p = 0.003).

CONCLUSIONS

The present study showed that CP levels increased in both the serum and the tissues of patients with LDH compared to patients without LDH, possibly as a consequence of LDH-associated inflammation.

Potential roles of cytokines and chemokines in human intervertebral disc degeneration: interleukin-1 is a master regulator of catabolic processes

OBJECTIVE

These studies investigated cytokine and chemokine receptor profiles in nucleus pulposus (NP) cells, and the effects of receptor stimulation on mRNA levels of extracellular matrix (ECM) components, degrading enzymes and cytokine and chemokine expression.

METHOD

Immunohistochemistry (IHC) was performed to localise expression of CD4, CCR1, CXCR1 and CXCR2 in human NP tissue samples. Effects of cytokine and chemokine stimulation was performed to investigate effects related to ECM remodelling and modulation of cytokine and chemokine mRNA expression.

RESULTS

IHC identified CD4, CCR1, CXCR1 and CXCR2 expression by NP cells. Differential expression profiles were observed for CD4 and CXCR2 in tissue samples from degenerate and infiltrated IVDs. In vitro stimulations of primary human NP cultures with IL-16, CCL2, CCL3, CCL7 or CXCL8 did not identify any modulatory effects on parameters associated with ECM remodelling or expression of other cytokines and chemokines. Conversely, IL-1 was seen to modulate ECM remodelling and expression of all other cytokines and chemokines investigated.

CONCLUSION

This study demonstrates for the first time that NP cells express a number of cytokine and chemokine receptors and thus could respond in an autocrine or paracrine manner to cytokines and chemokines produced by NP cells, particularly during tissue degeneration. However, this study failed to demonstrate regulatory effects on ECM genes and degradative enzymes or other cytokines and chemokines for any target investigated, with the exception of IL-1. This suggests that IL-1 is a master regulator within the IVD and may exert regulatory potential over a plethora of other cytokines and chemokines.

Dominance of chemokine ligand 2 and matrix metalloproteinase-2 and -9 and suppression of pro-inflammatory cytokines in the epidural compartment after intervertebral disc extrusion in a canine model

BACKGROUND CONTEXT

In canine intervertebral disc (IVD) disease, a useful animal model, only little is known about the inflammatory response in the epidural space.

PURPOSE

To determine messenger RNA (mRNA) expressions of selected cytokines, chemokines, and matrix metalloproteinases (MMPs) qualitatively and semiquantitatively over the course of the disease and to correlate results to neurologic status and outcome.

STUDY DESIGN/SETTING

Prospective study using extruded IVD material of dogs with thoracolumbar IVD extrusion.

PATIENT SAMPLE

Seventy affected and 13 control (24 samples) dogs.

OUTCOME MEASURES

Duration of neurologic signs, pretreatment, neurologic grade, severity of pain, and outcome were recorded. After diagnostic imaging, decompressive surgery was performed.

METHODS

Messenger RNA expressions of interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor (TNF), interferon (IFN)γ, MMP-2, MMP-9, chemokine ligand (CCL)2, CCL3, and three housekeeping genes was determined in the collected epidural material by Panomics 2.0 QuantiGene Plex technology. Relative mRNA expression and fold changes were calculated. Relative mRNA expression was correlated statistically to clinical parameters.

RESULTS

Fold changes of TNF, IL-1β, IL-2, IL-4, IL-6, IL-10, IFNγ, and CCL3 were clearly downregulated in all stages of the disease. MMP-9 was downregulated in the acute stage and upregulated in the subacute and chronic phase. Interleukin-8 was upregulated in acute cases. MMP-2 showed mild and CCL2 strong upregulation over the whole course of the disease. In dogs with severe pain, CCL3 and IFNγ were significantly higher compared with dogs without pain (p=.017/.020). Dogs pretreated with nonsteroidal anti-inflammatory drugs revealed significantly lower mRNA expression of IL-8 (p=.017).

CONCLUSIONS

The high CCL2 levels and upregulated MMPs combined with downregulated T-cell cytokines and suppressed pro-inflammatory genes in extruded canine disc material indicate that the epidural reaction is dominated by infiltrating monocytes differentiating into macrophages with tissue remodeling functions. These results will help to understand the pathogenic processes representing the basis for novel therapeutic approaches. The canine IVD disease model will be rewarding in this process.

Do intervertebral discs degenerate before they herniate, or after?

The belief that an intervertebral disc must degenerate before it can herniate has clinical and medicolegal significance, but lacks scientific validity. We hypothesised that tissue changes in herniated discs differ from those in discs that degenerate without herniation. Tissues were obtained at surgery from 21 herniated discs and 11 non-herniated discs of similar degeneration as assessed by the Pfirrmann grade. Thin sections were graded histologically, and certain features were quantified using immunofluorescence combined with confocal microscopy and image analysis. Herniated and degenerated tissues were compared separately for each tissue type: nucleus, inner annulus and outer annulus.

Herniated tissues showed significantly greater proteoglycan loss (outer annulus), neovascularisation (annulus), innervation (annulus), cellularity/inflammation (annulus) and expression of matrix-degrading enzymes (inner annulus) than degenerated discs. No significant differences were seen in the nucleus tissue from herniated and degenerated discs. Degenerative changes start in the nucleus, so it seems unlikely that advanced degeneration caused herniation in 21 of these 32 discs. On the contrary, specific changes in the annulus can be interpreted as the consequences of herniation, when disruption allows local swelling, proteoglycan loss, and the ingrowth of blood vessels, nerves and inflammatory cells.

In conclusion, it should not be assumed that degenerative changes always precede disc herniation.

Cite this article: Bone Joint J 2013;95-B:1127–33.

Clinical and pathological analysis of epidural inflammation in intervertebral disk extrusion in dogs

BACKGROUND

Little is known about the pathologic changes in the epidural space after intervertebral disk (IVD) extrusion in the dog.

OBJECTIVES

To analyze the pathology of the epidural inflammatory response, and to search for correlations between this process and clinical findings.

METHODS

Clinical data from 105 chondrodystrophic (CD) and nonchondrodystrophic (NCD) dogs with IVD extrusion were recorded. Epidural material from these dogs was examined histopathologically and immunohistochemically. Using statistical analysis, we searched for correlations between severity of epidural inflammation and various clinical and pathologic variables.

RESULTS

Most dogs exhibited an epidural inflammatory response, ranging from acute invasion of neutrophils to formation of chronic granulation tissue. The mononuclear inflammatory infiltrates consisted mostly of monocytes and macrophages and only few T and B cells. Surprisingly, chronic inflammatory patterns also were found in animals with an acute clinical history. Severity of the epidural inflammation correlated with degree of the epidural hemorrhage and nucleus pulposus calcification (P = .003 and .040), but not with age, chondrodystrophic phenotype, neurologic grade, back pain, pretreatment, or duration. The degree of inflammation was statistically (P = .021) inversely correlated with the ability to regain ambulation.

CONCLUSION AND CLINICAL IMPORTANCE

Epidural inflammation occurs in the majority of dogs with IVD extrusion and may develop long before the onset of clinical signs. Presence of calcified IVD material and hemorrhage in the epidural space may be the triggers of this lesion rather than an adaptive immune response to the nucleus pulposus as suggested in previous studies. Because epidural inflammation may affect outcome, further research is warranted.

The cytokine and chemokine expression profile of nucleus pulposus cells: implications for degeneration and regeneration of the intervertebral disc

INTRODUCTION

The aims of these studies were to identify the cytokine and chemokine expression profile of nucleus pulposus (NP) cells and to determine the relationships between NP cell cytokine and chemokine production and the characteristic tissue changes seen during intervertebral disc (IVD) degeneration.

METHODS

Real-time q-PCR cDNA Low Density Array (LDA) was used to investigate the expression of 91 cytokine and chemokine associated genes in NP cells from degenerate human IVDs. Further real-time q-PCR was used to investigate 30 selected cytokine and chemokine associated genes in NP cells from non-degenerate and degenerate IVDs and those from IVDs with immune cell infiltrates (‘infiltrated’). Immunohistochemistry (IHC) was performed for four selected cytokines and chemokines to confirm and localize protein expression in human NP tissue samples.

RESULTS

LDA identified the expression of numerous cytokine and chemokine associated genes including 15 novel cytokines and chemokines. Further q-PCR gene expression studies identified differential expression patterns in NP cells derived from non-degenerate, degenerate and infiltrated IVDs. IHC confirmed NP cells as a source of IL-16, CCL2, CCL7 and CXCL8 and that protein expression of CCL2, CCL7 and CXCL8 increases concordant with histological degenerative tissue changes.

CONCLUSIONS

Our data indicates that NP cells are a source of cytokines and chemokines within the IVD and that these expression patterns are altered in IVD pathology. These findings may be important for the correct assessment of the ‘degenerate niche’ prior to autologous or allogeneic cell transplantation for biological therapy of the degenerate IVD.

Simvastatin ameliorates cauda equina compression injury in a rat model of lumbar spinal stenosis

Lumbar spinal stenosis (LSS) is the leading cause of morbidity and mortality worldwide. LSS pathology is associated with secondary injury caused by inflammation, oxidative damage and cell death. Apart from laminectomy, pharmacological therapy targeting secondary injury is limited. Statins are FDA-approved cholesterol-lowering drug. They also show pleiotropic anti-inflammatory, antioxidant and neuroprotective effects. To investigate the therapeutic efficacy of simvastatin in restoring normal locomotor function after cauda equina compression (CEC) in a rat model of LSS, CEC injury was induced in rats by implanting silicone gels into the epidural spaces of L4 and L6. Experimental group was treated with simvastatin (5 mg/kg body weight), while the injured (vehicle) and sham operated (sham) groups received vehicle solution. Locomotor function in terms of latency on rotarod was measured for 49 days and the threshold of pain was determined for 14 days. Rats were sacrificed on day 3 and 14 and the spinal cord and cauda equina fibers were extracted and studied by histology, immunofluorescence, electron microscopy (EM) and TUNEL assay. Simvastatin aided locomotor functional recovery and enhanced the threshold of pain after the CEC. Cellular Infiltration and demyelination decreased in the spinal cord from the simvastatin group. EM revealed enhanced myelination of cauda equina in the simvastatin group. TUNEL assay showed significantly decreased number of apoptotic neurons in spinal cord from the simvastatin group compared to the vehicle group. Simvastatin hastens the locomotor functional recovery and reduces pain after CEC. These outcomes are mediated through the neuroprotective and anti-inflammatory properties of simvastatin. The data indicate that simvastatin may be a promising drug candidate for LSS treatment in humans.

Proinflammatory cytokine expression profile in degenerated and herniated human intervertebral disc tissues

OBJECTIVE

Prior reports document macrophage and lymphocyte infiltration with proinflammatory cytokine expression in pathologic intervertebral disc (IVD) tissues. Nevertheless, the role of the Th17 lymphocyte lineage in mediating disc disease remains uninvestigated. We undertook this study to evaluate the immunophenotype of pathologic IVD specimens, including interleukin-17 (IL-17) expression, from surgically obtained IVD tissue and from nondegenerated autopsy control tissue.

METHODS

Surgical IVD tissues were procured from patients with degenerative disc disease (n = 25) or herniated IVDs (n = 12); nondegenerated autopsy control tissue was also obtained (n = 8) from the anulus fibrosus and nucleus pulposus regions. Immunohistochemistry was performed for cell surface antigens (CD68 for macrophages, CD4 for lymphocytes) and various cytokines, with differences in cellularity and target immunoreactivity scores analyzed between surgical tissue groups and between autopsy control tissue regions.

RESULTS

Immunoreactivity for IL-4, IL-6, IL-12, and interferon-gamma (IFNgamma) was modest in surgical IVD tissue, although expression was higher in herniated IVD samples and virtually nonexistent in control samples. The Th17 lymphocyte product IL-17 was present in >70% of surgical tissue fields, and among control samples was detected rarely in anulus fibrosus regions and modestly in nucleus pulposus regions. Macrophages were prevalent in surgical tissues, particularly herniated IVD samples, and lymphocytes were expectedly scarce. Control tissue revealed lesser infiltration by macrophages and a near absence of lymphocytes.

CONCLUSION

Greater IFNgamma positivity, macrophage presence, and cellularity in herniated IVDs suggests a pattern of Th1 lymphocyte activation in this pathology. Remarkable pathologic IVD tissue expression of IL-17 is a novel finding that contrasts markedly with low levels of IL-17 in autopsy control tissue. These findings suggest involvement of Th17 lymphocytes in the pathomechanism of disc degeneration.

Late results of surgery for herniated lumbar disk as related to duration of preoperative symptoms and type of herniation

BACKGROUND

Ten to 40% of patients who have undergone state-of-the-art surgery for HLD do not obtain relief of pain. The relationship among timing of surgery for HLD, type of herniation, and clinical outcome, questioned in the present study, has rarely been referred to as an individual medical factor.

METHODS

Sixty-three patients belonging to a single ethnic group were called in 2 to 5 years after surgery and scored for change in severity of HLD-related pain (VAS) and current disability as scored by a functional rating system (Spangfort).

RESULTS

Patients with noncontained herniation (group 1), as compared with those with contained herniation (group 2), had had more intense radicular pain preoperatively (mean VAS, 8.3 vs 6.5), had a shorter history of pain (mean, 7.4 vs 15.8 weeks), and enjoyed a better functional outcome (good or fair in 96.4% vs 74.3%). Those in group 1 with a preoperative pain history of 6 weeks or less showed a greater decrease in pain intensity than those with a pain history of 6 to 12 weeks. Group 2 patients had had a longer preoperative history of symptoms than any in group 1 (>12 weeks in all) and showed an intermediate decrease in pain intensity.

CONCLUSIONS

Patients with noncontained herniation who do not show signs of improvement should be offered elective surgery after 6 to 8 weeks of observation; those having contained herniation should be advised that a certain degree of benefit can be expected from surgery, however late.

The association of the activation-inducible tumor necrosis factor receptor and ligand with lumbar disc herniation

PURPOSE

Herniated nucleus pulposus fragments are recognized by the immune system as a foreign-body, which results in an autoimmune reaction. Human activation-inducible tumor necrosis factor receptor (AITR) and its ligand, AITRL, are important costimulatory molecules in the pathogenesis of autoimmune diseases. Despite the importance of these costimulatory molecules in autoimmune disease, their role in the autoimmune reaction to herniated disc fragments has yet to be explored. The purpose of the present study is to investigate whether the overexpression of AITR and AITRL might be associated with lumbar disc herniation.

MATERIALS AND METHODS

The study population consisted of 20 symptomatic lumbar disc herniation patients. Ten macroscopically normal control discs were obtained from patients with spinal fractures managed with anterior procedures that involved a discectomy. Peripheral blood samples from both the study patients and controls were collected. The expression levels of AITR and AITRL were investigated by flow cytometric analysis, confocal laser scanning microscopy, immunohistochemistry and by reverse transcriptase-polymerase chain reaction (RT-PCR). The soluble AITR and AITRL serum levels were measured by an enzyme-linked immunosorbent assay.

RESULTS

Flow cytometric analysis revealed significantly higher levels of both AITR and AITRL in the lumbar disc herniation patients than in the controls. The AITRL expression levels were also increased in patients with lumbar disc herniation, shown by using confocal laser scanning microscopy, immunohisto-chemistry, and RT-PCR. Finally, soluble AITR and AITRL were elevated in the patients with lumbar disc herniations.

CONCLUSION

The AITR and AITRL are increased in both the herniated disc tissue and the peripheral blood of patients with lumbar disc herniation.

Autoimmune properties of nucleus pulposus: an experimental study in pigs

STUDY DESIGN

Assessment of activated T and B cells in a subcutaneous chamber filled with autologous nucleus pulposus using flow cytometry and immunohistochemistry.

OBJECTIVES

To examine if subcutaneously placed autologous nucleus pulposus may attract activated T and B cells in an animal model.

SUMMARY OF BACKGROUND DATA

Nucleus pulposus has been suggested to trigger an autoimmune response if exposed to the immune system, for example, in association with disc herniation. T-cell activation represents a hallmark in the generation of an autoimmune response, subsequently leading to the differentiation of B cells, but a causal association between the exposure of nucleus pulposus to the systemic circulation and T and B cell activation is still lacking.

METHODS

Autologous nucleus pulposus was harvested from the intervertebral disc of 9 pigs and placed subcutaneously in perforated titanium chambers. In order to control for the effect of the titanium chamber, an additional empty chamber was placed subcutaneously in each pig. After 7 days, the pigs were killed and the chambers were harvested. Flow cytometry and immunohistochemistry were used for analysis of T-helper cells (CD4+), cytotoxic T cells (CD8+), and B cells (Igkappa) in the chamber exudates and T cells (CD45RC) in the remaining blood clot tissue of the chamber.

RESULTS

As compared with the empty chambers, the proportion of activated T cells (CD4+ and CD8+) was significantly higher in the exudate of the nucleus pulposus filled chamber. The proportion of activated B cells expressing immunoglobulin kappa (Igkappa) was also significantly elevated in the exudate of the nucleus pulposus chambers. The analysis of the remaining chamber tissue revealed a significantly higher amount of T cells (CD45RC) in the nucleus pulposus chambers than in the empty chambers.

CONCLUSIONS

The present findings indicate that nucleus pulposus attracts activated T and B cells. However, since the cell population in the nucleus pulposus of young pigs may differ from that of adult humans, the obtained data may not be directly transferred to the human situation of a disc herniation. The observations in the present study may nevertheless explain some of the local tissue reactions occurring in association with disc herniation and nerve root involvement, thereby providing further insight into the pathophysiology of sciatica.

An experimental animal model of spinal root compression syndrome: an analysis of morphological changes of myelinated axons during compression radiculopathy and after decompression

The treatment of radicular pain is mainly empirical because there are only few experimental studies dealing with morphological changes during compression radiculopathy. The goal of the study was to investigate changes in the morphology of myelinated axons during spinal root compression and the influence of decompression in a new rat model. The number of myelinated axons and their diameter were measured at 1, 2, 5, and 8 weeks during compression of the dorsal spinal root. The same approach was applied for 1-week compression followed by decompression for 1 or 2 weeks and compression for 5 weeks followed by 3-week decompression. A decrease in the number of myelinated axons (particularly those of large diameters) occurred after compression for 1 week. Continued compression for up to 8 weeks resulted in centripetal increase in the number of myelinated axons and the persistence of a small fraction of large myelinated axons at the site of compression. After that time, a decreased number of axons and a reduced fraction of large myelinated axons occurred again. Decompression after 1-week compression caused a rapid increase in the number of both small and large myelinated axons within the spinal root including the site of compression. A small fraction of regenerated axons was found after 5-week compression followed by 3-week decompression. Finally, we investigated the time course of the temporary increase in the number of regenerated myelinated axons during dorsal root compression for up to 8 weeks. The efficacy of decompression was superior when applied one week after compression or after regress of the acute phase of aseptic inflammation associated with fragility of spinal root. The results of the study verify the need for early surgical decompression to prevent irreversible damage of the spinal roots.

Expression of ADAMTS-4 (aggrecanase-1) and possible involvement in regression of lumbar disc herniation

STUDY DESIGN

Examination of ADAMTS-4 expression, and cellular lineages, distribution, and numbers of ADAMTS-4 (aggrecanase-1) expressing cells in herniated lumbar intervertebral discs.

OBJECTIVE

To determine the expression of ADAMTS-4, a metalloproteinase capable of digesting aggrecan, and its role in herniated lumbar intervertebral disc degradation.

SUMMARY OF BACKGROUND DATA

Matrix metalloproteinases degrade extracellular matrix of herniated discs, but the mechanism of aggrecan degradation, the major component of intervertebral discs, is poorly understood.

METHODS

Surgically resected herniated lumbar intervertebral discs from 22 patients were subclassified into protrusion, subligamentous extrusion, transligamentous extrusion, and sequestration types. Reverse transcriptase polymerase chain reaction, Western blot, and immunohistochemistry were used to evaluate ADAMTS-4 messenger ribonucleic acid and protein expression.

RESULTS

Expression of ADAMTS-4 messenger ribonucleic acid and protein was shown in the samples of herniated lumbar intervertebral discs. Immunohistochemical staining showed that ADAMTS-4 was mainly localized in CD68-positive mononuclear cells in granulation and adjacent disc tissues. ADAMTS-4 positive cell counts were significantly higher in transligamentous extrusion and sequestration than protrusion and subligamentous extrusion types. Alcian blue staining showed a decrease of proteoglycan in transligamentous extrusion and sequestration cases.

CONCLUSIONS

Macrophages infiltrating granulation and adjacent disc tissues express ADAMTS-4, suggesting its involvement in herniated disc regression.

Effects of interleukin-1 beta, interleukin-6, and tumor necrosis factor on sensitivity of dorsal root ganglion and peripheral receptive fields in rats

This study was designed to characterize the effects of low doses (0.5-5 ng) of pro-inflammatory cytokines, interleukin-1 beta (IL-1beta), interleukin-6 (IL-6), and tumor necrosis factor (TNF), on the neural activity of dorsal root ganglion (DRG) in rats. The purpose of this study was to examine the effects of cytokines (IL-1beta, IL-6, and TNF) on the somatosensory neural response of DRG. The release of inflammatory cytokines by an injured disc may play a critical role in pain production at nerve endings, axons, and nerve cell bodies. Herniated disc tissue has been shown to release IL-1beta, IL-6, TNF, and other algesic chemicals. Their effects on nerve endings in disc and adjacent tissue may lead to low back pain and their effects on dorsal root axons and ganglia may lead to sciatica. Exposed lumbar DRGs were investigated by electrophysiologic techniques. Sham (mineral oil), control (carrier solution), or IL-1beta, IL-6, or TNF at doses of 0.5, 1, and 5 ng were applied over the DRG. Baseline discharge rates as well as mechanosensitivity of the DRG and peripheral receptive fields were evaluated over 30 min. Applications of IL-1beta at 1 ng resulted in an increase in the discharge rate, 5 ng resulted in an increased mechanosensitivity of the DRG in group II units. Similarly, after 1 ng TNF applications, group II units also showed an increase in mechanosensitivity of DRG and peripheral receptive fields. At low doses IL-1beta and TNF sensitization of receptive fields were observed. The responses observed in the group II units indicate that a sub-population of afferent units might have long-term effects modifying the sensory input to the central nervous system. This study provides added evidence to the role of cytokines in modulating afferent activity following inflammation.

Is there a clinical correlate to the histological and radiological evidence of inflammation in trans-ligamentous extruded and sequestered lumbar disc herniaton?

The pain of lumbar disc herniation is related to direct compression of the nerve root and to the foreign-body inflammatory response to the herniated disc material. In this study, we attempted to identify disc-related inflammation in trans-ligamentous extruded and sequestered lumbar disc herniation using gadolinium-DPTA-enhanced T1-weighted and short-time inversion recovery (STIR) magnetic resonance imaging. We assessed how these results related to each other, and to patients' clinical status, and to immunohistochemistry findings in disc specimens removed at surgery. Forty-one patients with trans-ligamentous extruded or sequestered disc herniation were investigated clinically and radiologically. Twenty-five patients who did not respond to initial medical treatment or who had progressive neurological deficits underwent discectomy. Specimens of disc material removed during surgery were studied immunohistochemically and inflammatory cell types were identified. The other 16 patients showed good response to treatment, and were given further medical therapy and monitored for a mean of 6.3 months of follow-up. All radiological diagnoses in the operated cases were confirmed at surgery. There were no significant differences among the rates of detection of inflammation by contrast MRI, STIR technique, and immunohistochemistry in the surgical treated cases. In the medically treated cases, the frequency of radiological evidence of inflammation on the initial contrast enhanced T1-weighted and STIR images was similar to the frequency observed on the most recent scans done during follow-up. The study showed that the radiological and immunohistochemical evidence of inflammation in these cases does not correspond with patients' clinical pain profiles over time. It also revealed that STIR and contrast T1W are equally reliable for detecting inflammation in trans-ligamentous extruded or sequestered lumbar disc herniation. In future, studies that focus on physical and chemical mechanisms of pain in lumbar disc herniation in larger series of conservatively and surgically treated patients may clarify the link between inflammation and radicular pain in these types of disc herniation.

A fibronectin fragment alters the metabolism by rabbit intervertebral disc cells in vitro

STUDY DESIGN

A biochemical and gene expression study was conducted to determine the effects of the 30-kDa N-terminal fibronectin fragment (Fn-f) on the glycosaminoglycan content of nucleus pulposus (NP) explant cultures, and on the gene expression profile of NP cells in alginate culture.

OBJECTIVE

To determine the effects of Fn-f on NP cells in alginate culture and disc explant cultures.

SUMMARY OF BACKGROUND DATA

The macroscopic and histologic features of disc degeneration have been well described, but the molecular biology of disc degeneration remains poorly understood. Although fibronectin and fibronectin fragments are known to accumulate in degenerative discs, the role of fibronectin fragments on the degenerative process has not been elucidated. This study sought to define the effects of Fn-f on the expression of key matrix and degradative genes and on disc matrix proteins.

METHODS

New Zealand white rabbits discs were harvested. NP cells were either isolated and grown in alginate culture or cultured as explanted tissue. The cultured cells were exposed to 10 nmol/L, 100 nmol/L, and 1 micromol/L concentrations of 30-kDa N-terminal Fn-f or a control substance and then analyzed histologically, biochemically, and with gene expression studies.

RESULTS

Alginate-cultured NP cells maintained a histologic appearance and phenotypic expression pattern similar to disc cells in vivo. Exposure of these cells to Fn-f led to the up-regulation of the MMP-9, MMP-13, and Fas genes and the down-regulation of the Type II collagen and aggrecan genes. In explant culture, Fn-f exposure led to a 60% reduction in glycosaminoglycan content compared with controls.

CONCLUSION

Treatment of NP cells in vitro with Fn-f led to changes in matrix proteins and gene expression similar to those seen during disc degeneration in vivo. This supports a possible detrimental role of the N-terminal fibronectin fragment in degenerative disc disease.

The pattern of interleukin-12 and T-helper types 1 and 2 cytokine expression in herniated lumbar disc tissue

STUDY DESIGN

A study was conducted to investigate the expression of cytokines related to the immune reaction in herniated lumbar disc tissues.

OBJECTIVE

To investigate the immunologic status of lumbar disc tissue and the type of immune reaction that occurs in response to lumbar disc herniation.

SUMMARY OF BACKGROUND DATA

It has been proposed that herniated lumbar disc tissue causes an immune reaction. Various inflammatory cells, proinflammatory cytokines, antibodies, and immunoglobulins have been identified in and around herniated lumbar disc tissue. Recently, it has been reported that lumbar disc tissue may be another potential immune-privileged site in the human body.

METHODS

This study included 40 herniated lumbar disc tissues: 20 contained and 20 noncontained discs. The concentrations of interleukin-12, T-helper Type 1, interferon-gamma (IFN-gamma), and Th2 (IL-4) cytokines were determined by enzyme-linked immunosorbent assay, respectively. The results were compared between the two groups.

RESULTS

The concentrations of interleukin-12 and interferon-gamma were higher in the noncontained discs than in the contained discs: 28.3 +/- 10.7 pg/mL vs 9.2 +/- 4.2 pg/mL (P = 0.001) and 4.7 +/- 5.0 pg/mL vs 2.3 +/- 3.8 pg/mL (P = 0.029), respectively. On the contrary, the concentration of IL-4 was higher in the contained discs than in the noncontained discs: 24.3 +/- 20.1 pg/mL vs 1.9 +/- 4.5 pg/mL; P= 0.001. The degrees of interleukin-12 and interferon-gamma expression were negatively correlated with that of IL-4 (n = 40): correlation coefficient, -0.671 (P = 0.001) and correlation coefficient, -0.344 (P = 0.03), respectively.

CONCLUSIONS

The findings suggest that preferential expression of Th2 cytokines by disc cells, as shown in contained discs, is another factor contributing to the immune privileged status of lumbar disc tissue. The exposure of lumbar disc tissue to the epidural space may increase the concentration of interleukin-12 in herniated lumbar disc tissue, changing the pattern of T-helper Types 1 and 2 cytokine expression.

Pathophysiology of lumbar disc degeneration: a review of the literature

Lumbar disc degeneration occurs because of a variety of factors and results in a multitude of conditions. Alterations in the vertebral endplate cause loss of disc nutrition and disc degeneration. Aging, apoptosis, abnormalities in collagen, vascular ingrowth, loads placed on the disc, and abnormal proteoglycan all contribute to disc degeneration. Some forms of disc degeneration lead to loss of height of the motion segment with concomitant changes in biomechanics of the segment. Disc herniation with radiculopathy and chronic discogenic pain are the result of this degenerative process.

Chemokine profile of herniated intervertebral discs infiltrated with monocytes and macrophages

STUDY DESIGN

Herniated lumbar disc specimens were analyzed using reverse transcriptase-polymerase chain reaction to determine the profile of chemokine expression.

OBJECTIVE

To investigate the mechanism underlying the recruitment of inflammatory cells into herniated discs during the process of spontaneous regression.

SUMMARY OF BACKGROUND DATA

Spontaneous regression of herniated intervertebral discs has been increasingly reported. Although macrophages are suggested to play a central role in this process, it remains unclear how these macrophages accumulate in the herniated discs.

METHODS

RNA was extracted from 36 surgical specimens of the herniated lumbar disc, a disc specimen of idiopathic scoliosis and pyogenic spondylitis, and activated peripheral blood mononuclear cells of a normal donor. The RNA was reverse transcribed, and the resultant cDNA was amplified by PCR using primer pairs specific to the CXC chemokines (IL-8, MGSA-alpha, IP-10, MIG), the CC chemokines (MCP-1, MCP-2, MCP-3, MCP-4, MIP-1alpha, MIP-3alpha, RANTES, STCP-1), the C chemokine (lymphotactin), and the glyceraldehyde phosphate housekeeping gene. Thin cryostat sections also were made from the disc specimens and stained with hematoxylin and eosin.

RESULTS

All the chemokines examined except MCP-4 were expressed by activated peripheral blood mononuclear cells. Glyceraldehyde phosphate was detected in 8 of 36 herniated discs and in 1 disc specimen each of idiopathic scoliosis and pyogenic spondylitis. Chemokine expression was examined for these 10 disc specimens. From among the 13 chemokines examined, MCP-3, MCP-4, RANTES, and IP-10 were detected in the disc from the idiopathic scoliosis, and MCP-3, MCP-4, RANTES, IP-10, MIG, and MGSA-alpha were detected in the infected or herniated discs. Histologic analysis showed infiltration of inflammatory cells in the infected disc and all 8 herniated discs.

CONCLUSIONS

The findings suggest that chemoattractive properties exist in a selected population of human intervertebral discs, and that unique sets of chemokinesplay a role in spontaneous regression of these herniated disc tissues.

Cell cluster formation in degenerate lumbar intervertebral discs is associated with increased disc cell proliferation

Healthy human intervertebral discs contain relatively few cells and these are sparsely distributed. A characteristic feature of disc degeneration, however, is the appearance of cell clusters, particularly in damaged areas. How these clusters form is currently unknown. We have examined excised pathological human discs for evidence of cell proliferation. Disc sections were immunostained for the proliferating cell nuclear antigen (PCNA) and the proliferation-associated Ki-67 antigen. PCNA immunopositive cells were observed within degenerate discs, commonly though not exclusively, in cell clusters. Cells immunopositive for the Ki-67 antigen were less prevalent than those for PCNA, but similarly were observed frequently within clusters in degenerate discs. In contrast, immunopositivity for these markers was not common in less degenerate discs or in areas of the disc where cell clusters were not observed. These observations suggest that disc cell proliferation is associated with disc degeneration and is the likely cause of cell cluster formation.

Cost effectiveness of periradicular infiltration for sciatica: subgroup analysis of a randomized controlled trial

STUDY DESIGN

A subgroup analysis of a prospective, randomized controlled trial was performed.

OBJECTIVE

To describe the cost effectiveness of periradicular infiltration with steroid in subgroups of patients with sciatica.

SUMMARY OF BACKGROUND DATA

A recent trial on periradicular infiltration indicated that a methylprednisolone-bupivacaine combination had a short-term effect, as compared with that of saline. This report describes the efficacy and cost effectiveness of steroid in subgroups of patients with sciatic.

METHODS

This study involved 160 patients with unilateral sciatica. Outcome assessments were leg pain (100-mm visual analog scale), disability on the Oswestry Low Back Disability Questionnaire, and the Nottingham Health Profile. Data on medical costs and sick leaves also were gathered. Patients were randomized for periradicular infiltration with either methylprednisolone-bupivacaine or saline. The adjusted between-group treatment differences at each follow-up assessment, the number of patients free of leg pain (responders, cutoff 75%), and efficacy by the area-under-the-curve method were calculated. For the cost-effectiveness estimate, the total costs were divided by the number of responders. The rate of operations in different subgroups was evaluated by Kaplan-Meier analysis.

RESULTS

In the case of contained herniations, the steroid injection produced significant treatment effects and short-term efficacy in leg pain and in Nottingham Health Profile emotional reactions. For symptomatic lesions at L3-L4-L5, steroid was superior to saline for leg pain, disability, and straight leg raising in the short term. By 1 year, steroid seemed to have prevented operations for contained herniations, costing $12,666 less per responder in the steroid group (P < 0.01). For extrusions, steroid seemed to increase the operation rate, and the steroid infiltration was more expensive, costing $4445 per responder (P < 0.01).

CONCLUSIONS

In addition to short-term effectiveness for contained herniations and lesions at L3-L4-L5, steroid treatment also prevented surgery for contained herniations. However, steroid was countereffective for extrusions. The results of the subgroup analyses call for a verification study.

Comparison of the prevalence of inflammatory cells in subtypes of disc herniations and associations with straight leg raising

STUDY DESIGN

The prevalence of inflammatory cells in 205 disc herniations (DHs) and nine macroscopically normal discs for comparison was studied immunohistochemically. Inflammatory cells were separately analyzed in subtypes of DH. Immunohistochemical data were related to clinical parameters, the straight leg raising test (SLR) in particular.

OBJECTIVES

The objectives of the study were to compare the occurrence of inflammatory cells in various subtypes of DH and to determine the association between clinical data and inflammatory cell occurrence in a more extensive sample of DH, with separate analysis of DH subtypes.

SUMMARY OF BACKGROUND DATA

Previous studies have suggested a common occurrence of inflammation and inflammatory cells, particularly macrophages, in DHs. No studies on any larger material comprising different subtypes of DH have been done.

METHODS

For immunohistochemistry the alkaline phosphatase antialkaline phosphatase method was used. Monoclonal antibodies to T cells in general (CD2), activated T cells (CD25), B cells (CD22), and macrophages (CD68) were used. Obtained immunostaining results were then compared with clinical data, e.g., duration of pain, SLR, and type of DH (sequesters 86, extrusions 103, protrusions 16). Associations were studied by the chi2 test or Fisher's exact test, as applicable (level of significance P < 0.05).

RESULTS

Abundant T cells were seen in 17% of the 205 DHs, activated T cells in 17%, B cells in 16%, and macrophages in 37%. All cell types were 2-3 times more prevalent in sequestrated discs than in extrusions. In protrusions macrophages were abundantly seen in 25% (4 of 16) and no other inflammatory cells. In patients with positive SLR and a sequestrated disc abundant lymphocytes were seen three times more often than in extrusions. When patients with bilaterally negative SLR were compared with those with tight SLR (< or =30 degrees ) with respect to inflammatory cell occurrence, some significant differences were noted (CD68, P < 0.025; CD25, P = 0.04). A comparison between SLR bilaterally positive and bilaterally negative also showed associations for all four inflammatory cell types (P = 0.016 to P = 0.029). There was no correlation between inflammatory cells and duration of pain. Abundant inflammatory cells were never seen in control discs.

CONCLUSIONS

When SLR was positive and the DH type was sequestered, inflammatory cells were most commonly seen. Our results showed some statistically significant associations between inflammatory cells and SLR, most clearly when comparing bilaterally positive and negative SLR. Interestingly, a bilaterally positive SLR showed an association with all four inflammatory cell types analyzed. Tight SLR also showed an association, particularly with macrophages. In addition to tissue resorption, they may participate in sciatic pain. Even though lymphocytes were less prevalent, they may have some role in sequestered discs and bilaterally positive SLR.

Immunophenotypic analysis of the inflammatory infiltrates in herniated intervertebral discs

STUDY DESIGN

The herniated portion of the lumbar disc was analyzed immunohistochemically for inflammatory infiltrates to determine their immunophenotype.

OBJECTIVE

To investigate the pathomechanism behind spontaneous regression of herniated discs.

SUMMARY OF BACKGROUND DATA

Spontaneous regression of herniated intervertebral discs has been increasingly reported. The inflammatory response of the host has been suggested as a factor in this phenomenon. However, whether the inflammation is induced from direct chemical irritation of the nucleus pulposus material or whether it is secondary to an autoimmune response to the nucleus pulposus remains controversial.

METHODS

The herniated portion of the disc was collected from 38 patients who underwent surgery for lumbar disc herniation. Thin cryostat sections were made, and the extent to which inflammatory cells had infiltrated the disc specimen was defined. Then the immunophenotype of cellular infiltrates in the herniated disc specimens was assessed by immunostaining using a series of antibodies for lymphocyte, monocyte, macrophage, and dendritic cell markers.

RESULTS

The inflammatory infiltrates in 14 of the 38 herniated discs were subjected to immunohistochemical analysis. None of them expressed the immunophenotypic markers of the lymphocyte (CD20, CD45RO, CD4, CD8, TCRgammadelta), mature monocyte (CD33), or dendritic cell (CD1a, CD80, CD86, S100). Abundant infiltration of CD68-positive cells that lacked CD33 but had a variable amount of CD11b, CD11c, and CD40 likely represents a process of differentiation from monocytes to macrophages.

CONCLUSIONS

These findings are consistent with an immunophenotype of inflammatory responses to tissue injury or chemical irritation rather than antigen-specific immune responses. Therefore, understanding the mechanism of tissue repair is fundamentally important in the management of patients with disc herniations.

Periradicular infiltration for sciatica: a randomized controlled trial

STUDY DESIGN

A randomized, double-blind trial was conducted.

OBJECTIVES

To test the efficacy of periradicular corticosteroid injection for sciatica.

SUMMARY OF BACKGROUND DATA

The efficacy of epidural corticosteroids for sciatica is controversial. Periradicular infiltration is a targeted technique, but there are no randomized controlled trials of its efficacy.

METHODS

In this study 160 consecutive, eligible patients with sciatica who had unilateral symptoms of 1 to 6 months duration, and who never underwent surgery were randomized for double-blind injection with methylprednisolone bupivacaine combination or saline. Objective and self-reported outcome parameters and costs were recorded at baseline, at 2 and 4 weeks, at 3 and 6 months, and at 1 year.

RESULTS

Recovery was better in the steroid group at 2 weeks for leg pain (P = 0.02), straight leg raising (P = 0.03), lumbar flexion (P = 0.05), and patient satisfaction (P = 0.03). Back pain was significantly lower in the saline group at 3 and 6 months (P = 0.03 and 0.002, respectively), and leg pain at 6 months (13.5, P = 0.02). Sick leaves and medical costs were similar for both treatments, except for cost of therapy visits and drugs at 4 weeks, which were in favor of the steroid injection (P = 0.05 and 0.005, respectively). By 1 year, 18 patients in the steroid group and 15 in the saline group underwent surgery.

CONCLUSIONS

Improvement during the follow-up period was found in both the methylprednisolone and saline groups. The combination of methylprednisolone and bupivacaine seems to have a short-term effect, but at 3 and 6 months, the steroid group seems to experience a "rebound" phenomenon.

Expression of Fas receptor on disc cells in herniated lumbar disc tissue

STUDY DESIGN

The expression of Fas receptor, an apoptosis-related protein, on disc cells was examined in surgically obtained disc specimens.

OBJECTIVE

To assess the fate of disc cells in herniated disc tissue and the difference in the degree of expression of the Fas receptor between contained and noncontained discs.

SUMMARY OF BACKGROUND DATA

Little is known about the fate of disc cells after herniation.

METHODS

Twenty-three herniated lumbar disc specimens were classified into contained discs (protrusion or subligamentous extrusion; n = 9) and noncontained discs (transligamentous extrusion or sequestration; n = 14). All specimens were stained using the avidin-biotin-peroxidase complex method. The percentage of disc cells positive for Fas receptor was calculated and compared with clinical and radiologic data.

RESULTS

There was a significant difference in the percentage of Fas-positive disc cells between the contained and noncontained discs (8.44 vs.- 14.29;P = 0.044). The percentage of Fas-positive disc cells correlated significantly with the patient's age (r = 0.455, P = 0.029), but not with the degree of disc degeneration on magnetic resonance imaging (r = 0.252, P = 0.214).

CONCLUSION

This is the first study to identify the expression of Fas receptor on disc cells in herniated disc tissue. The results show that the disc cells after herniation may undergo Fas-mediated apoptosis and that the degree of expression of Fas receptor differs depending on the type of herniation.

Inflammatory cells, motor weakness, and straight leg raising in transligamentous disc herniations

STUDY DESIGN

Possible statistically significant relationships between inflammatory cells and either motor weakness or straight leg raising were determined.

OBJECTIVES

To look for any clinically relevant links between inflammatory cells in disc herniations and signs of radiculopathy.

SUMMARY OF BACKGROUND DATA

Many studies have during recent years shown a presence of various types of inflammatory cells in disc herniations, but their clinical relevance has been questioned. To be clinically relevant, a presence of inflammatory cells should show a clear relationship to clinical evidence of nerve root involvement. Macrophages repeatedly demonstrated in a high proportion of disc herniations studied are of particular interest. Their major role may be in disc herniations tissue resorption and not in sciatica.

METHODS

A total of 96 disc herniations, all transligamentous, were analyzed by immunohistochemistry for presence of macrophages, T or B lymphocytes, and activated T lymphocytes separately. From recorded patient data, motor weakness and straight leg raising data were compared with a presence or absence of abundant (+ = at least 20 cells in a group) inflammatory cells. When not abundant, inflammatory cells were classified as "only few cells" (+) and grouped together with "no cells" (-). Patients with or without motor weakness were compared. Straight leg raising was compared for a positive (at <70 degrees ) or a negative test, and separately using the median as cut-off value. Groups were compared by chi-square analysis with the level of statistical significance set at P<0.05.

RESULTS

None of the four inflammatory cell types showed any significant association with motor weakness. Nor was any association observed when comparing positive and negative straight leg raising. With the median (straight leg raising = 47.5 degrees ) as cut-off, only activated T cells showed a weak (chi2 = 4.40, P<0.05) relationship with tighter straight leg raising, but none of the other cell types did. Even when straight leg raising was < 47.5 degrees, three times more disc herniations lacked (n = 34) inflammatory cells than showed (n = 13) inflammation. In a subgroup of only sequestrated discs, the findings were similar. However, in the patients with a bilaterally positive straight leg raising (n = 25), the prevalence of at least one inflammatory cell type was much higher in sequestrated discs (80%) than in extrusions (33%). This may suggest more subtle interrelationships between type of disc herniation, straight leg raising, and inflammatory cells.

CONCLUSIONS

The results of this study do not support a clinically relevant role for disc herniation inflammatory cells in sciatica. For the cells to be clinically relevant, a strong relationship between a presence of inflammatory cells and either or both of motor weakness and a tight straight leg raising should have been observed. The authors conclude that macrophages, which have been demonstrated in a high proportion of disc herniations in previous studies, are probably more important for disc tissue resorption processes than for producing sciatica. Other types of inflammatory cells are more rarely observed and may have no clinical meaning at all. However, more subtle interrelationships, considering the various types of disc herniations, should be further explored.

Human intervertebral disc cells are genetically modifiable by adenovirus-mediated gene transfer: implications for the clinical management of intervertebral disc disorders

STUDY DESIGN

Human intervertebral disc cells were cultured in monolayer and treated with adenovirus-containing marker genes to determine the susceptibility of the cells to adenovirus-mediated gene transfer.

OBJECTIVES

To test the efficacy of the adenovirus-mediated gene transfer technique for transferring exogenous genes to human intervertebral disc cells in vitro.

SUMMARY OF BACKGROUND DATA

Upregulated proteoglycan synthesis after direct in vivo adenovirus-mediated transfer of growth factor genes to the rabbit intervertebral disc has previously been reported. Before contemplating extending this approach to the treatment of human disc disease, it is necessary to demonstrate that human intervertebral disc cells are indeed susceptible to adenovirus-mediated gene transduction.

METHODS

Human intervertebral disc cells were isolated from disc tissue obtained from 15 patients during surgical disc procedures. The cells were cultured in monolayer and treated with saline containing five different doses of adenovirus carrying the lacZ gene (Ad/CMV-lacZ), saline containing adenovirus carrying the luciferase gene (Ad/CMV-luciferase), or saline alone. Transgene expression was analyzed by 5-bromo-4-chloro-3-indolyl-beta-galactosidase (X-Gal) staining and luciferase assay.

RESULTS

Adenovirus efficiently transferred lacZ and luciferase marker genes to cells from degenerated discs as well as to cells from nondegenerated discs. A minimum dose of 150 MOI Ad/CMV-lacZ was found to be sufficient to achieve transduction of approximately 100% of disc cells-regardless of patient age, sex, surgical indication, disc level, and degeneration grade. No statistically significant difference in the luciferase activities could be detected in disc cell cultures from degenerated and nondegenerated discs treated with Ad/CMV-luciferase.

CONCLUSIONS

In vitro transducibility of human intervertebral disc cells by adenovirus is relatively insensitive to disc degeneration grade. Because the rate-limiting step for successful gene therapy is the ability to transfer genes efficiently to the target tissue, the achievement of efficient gene transfer to human intervertebral disc cells(using a direct, adenovirus-mediated approach) is an important and necessary step in the development of gene therapy strategies for the management of human intervertebral disc disorders.

Role of leukocytes in radicular pain secondary to herniated nucleus pulposus

Some studies have assessed inflammatory cells such as macrophages, lymphocytes, and neutrophils in herniated lumbar disc tissues using histologic analysis. However, there is no consensus regarding the relationships between clinical symptoms, including radicular pain and the presence of inflammatory cells. It has been shown that autologous nucleus pulposus relocated on the lumbar nerve root in rats produces time dependent and reversible mechanical hyperalgesia, which is thought to be a pain related behavior in peripheral neuropathic pain models. The purpose of this study was to determine whether leukocytes play a role in the mechanical hyperalgesia induced by the nucleus pulposus and to characterize the role of leukocytes in radicular pain attributable to lumbar disc herniation. Nitrogen mustard was used to induce and evaluate leukocytopenia in rats. Sensitivity to mechanical noxious stimuli was measured quantitatively, and inflammatory cells in granulation tissue around the nerve root were examined histologically. The nucleus pulposus produced neither mechanical hyperalgesia nor abundant inflammatory cells in rats with nitrogen mustard induced leukocytopenia. Neuropathic pain produced by the nucleus pulposus, when placed on the nerve root, may be related to inflammatory cell infiltration induced by relocation of the nucleus pulposus, rather than the nucleus pulposus itself.