Possible pathogenesis of painful intervertebral disc degeneration

A One-Stone-Two-Birds Strategy for Intervertebral Disc Repair: Constructing a Reductive Chelation Hydrogel to Mitigate Oxidative Stress and Promote Disc Matrix Reconstruction

Intervertebral disc degeneration (IVDD) is characterized by fibrosis of nucleus pulposus (NP) cells and accelerated surrounding extracellular matrix catabolism. Bioactive hydrogels have shown significant potential in regulating cellular functions and tissue homeostasis. In this work, a dynamic hydrogel (HA-NCSN/Cu) is designed via the reductive chelation of hyaluronic acid grafted with thiourea (HA-NCSN) and Cu2+. The reductivity of the grafted thiourea groups of HA-NCSN can quickly reduce part of the chelated Cu2+ to Cu+. Therefore, during the gelation process, the color of hydrogel become dark immediately, which endowed hydrogel with remarkable photothermal effect. The abundant thiourea groups inside hydrogel can effectively scavenge reactive oxygen species to mitigate the inflammatory stress of NP cells. RNA sequencing analysis further reveals that glutathione signaling pathway is significantly altered. Meanwhile, mild photothermal therapy could activate the TGF-β/Smad pathway in NP cells, promoting the expression and secretion of Aggrecan and Collagen II. Ultimately, the combined modulation of inflammation alleviation and matrix regeneration achieves the restoration of the structure and function of the damaged intervertebral disc, which is also strongly demonstrated by the in vivo animal experiments. All of these results demonstrate the great potential of the dynamic HA-NCSN/Cu hydrogel in IVDD treatment.

Role of macrophage in intervertebral disc degeneration

Intervertebral disc degeneration is a degenerative disease where inflammation and immune responses play significant roles. Macrophages, as key immune cells, critically regulate inflammation through polarization into different phenotypes. In recent years, the role of macrophages in inflammation-related degenerative diseases, such as intervertebral disc degeneration, has been increasingly recognized. Macrophages construct the inflammatory microenvironment of the intervertebral disc and are involved in regulating intervertebral disc cell activities, extracellular matrix metabolism, intervertebral disc vascularization, and innervation, profoundly influencing the progression of disc degeneration. To gain a deeper understanding of the inflammatory microenvironment of intervertebral disc degeneration, this review will summarize the role of macrophages in the pathological process of intervertebral disc degeneration, analyze the regulatory mechanisms involving macrophages, and review therapeutic strategies targeting macrophage modulation for the treatment of intervertebral disc degeneration. These insights will be valuable for the treatment and research directions of intervertebral disc degeneration.

Fundamentals of intervertebral disc degeneration and related discogenic pain

Lumbar intervertebral disc degeneration is thought to be the main cause of low back pain, although the mechanisms by which it occurs and leads to pain remain unclear. In healthy adult discs, vessels and nerves are present only in the outer layer of the annulus fibrosus and in the bony endplate. Animal models, and histological and biomechanical studies have shown that annulus tear or endplate injury is the initiating factor for painful disc degeneration. Injury to the disc triggers a local inflammatory repair response that activates nociceptors and promotes the synthesis of neuropeptides such as substance P and calcitonin gene-related peptide, by dorsal root ganglion neurons. These neuropeptides are transported to injured discs and act as pro-inflammatory molecules, promoting the production of an "inflammatory soup" by inducing vasodilatation and plasma extravasation as well as by promoting the release of chemical mediators from disc cells and infiltrating immune cells, causing neurogenic inflammation that leads to progressive disc degeneration and discogenic pain.

Role of neurogenic inflammation in intervertebral disc degeneration

In healthy intervertebral discs (IVDs), nerves and blood vessels are present only in the outer annulus fibrosus, while in degenerative IVDs, a large amount of nerve and blood vessel tissue grows inward. Evidence supports that neurogenic inflammation produced by neuropeptides such as substance P and calcitonin gene related peptide released by the nociceptive nerve fibers innervating the IVDs plays a crucial role in the process of IVD degeneration. Recently, non-neuronal cells, including IVD cells and infiltrating immune cells, have emerged as important players in neurogenic inflammation. IVD cells and infiltrating immune cells express functional receptors for neuropeptides through which they receive signals from the nervous system. In return, IVD cells and immune cells produce neuropeptides and nerve growth factor, which stimulate nerve fibers. This communication generates a positive bidirectional feedback loop that can enhance the inflammatory response of the IVD. Recently emerging transient receptor potential channels have been recognized as contributors to neurogenic inflammation in the degenerative IVDs. These findings suggest that neurogenic inflammation involves complex pathophysiological interactions between sensory nerves and multiple cell types in the degenerative IVDs. Clarifying the mechanism of neurogenic inflammation in IVD degeneration may provide in-depth understanding of the pathology of discogenic low back pain.

Depression predicts decreased lumbar bone mineral density: A scoping review of chronic psychological stress and spinal tissue pathology

Objective

Chronic low back pain (cLBP) is a complex disease with biological, psychological, and social components and the complex interactions of these components are poorly understood. Chronic psychological stress (CPS) (anxiety, depression, etc.) and pathological changes in spinal tissue (osteoporosis, disc degeneration, etc.) are frequently and independently associated with cLBP, yet their explicit relationship has not been collectively reviewed. The objective of this scoping review is to investigate the current state of research on how CPS may impact spinal tissue pathology.

Design

Five steps were utilized to conduct this scoping review: 1) identify a research objective and establish a search strategy, 2) identify research articles, 3) select research articles that meet search criteria, 4) extract data, 5) summarize and report results.

Results

We identified N ​= ​56 articles relating CPS to spinal pathology. Of those that identified a relationship between CPS and spine pathology (N ​= ​39), most (N ​= ​24) described decreased lumbar vertebral bone mineral density (BMD) between depression and control groups. Animal studies (N ​= ​8) were limited to mice and confirmed a causal relationship between CPS and lower vertebral BMD. Only a few additional human studies (N ​= ​9) documented relationships between other various forms of CPS and spinal tissue pathologies.

Conclusion

This scoping review documents evidence of a relationship between CPS and decreased spine health in humans as well as a causal relationship between the initiation of CPS and decreased BMD in animals. As few studies evaluated disease in other spinal anatomy in relationship to CPS, future work in this area is warranted. Further exploration of CPS beyond depression is warranted as well.

The Role of Immunocyte Infiltration Regulatory Network Based on hdWGCNA and Single-Cell Bioinformatics Analysis in Intervertebral Disc Degeneration

Immune infiltration plays a crucial role in intervertebral disc degeneration (IDD). In this study, we explored the immune microenvironment of IDD through single-cell bioinformatics analysis. Three single-cell datasets were integrated into this study. Nucleus pulposus cells (NPCs) were divided into subgroups based on characteristic genes, and the role of each subgroup in the IDD process was analyzed through pseudo-time trajectory analysis. The hub genes were obtained using hdWGCNA, further identified by bulk datasets and pseudo-time sequence. The expression of the hub genes defined the NPCs related to immune infiltration, and the interaction between these NPCs and immunocytes was explored. The NPCs were divided into four subgroups: reserve NPCs, HCL-NPCs, response NPCs, and support NPCs, which, respectively, dominate the four processes of IDD: non, mild, moderate, and severe degeneration. SPP1 and ICAM1 were identified as the nucleus pulposus immune infiltration hub genes. Macrophages and myelocytes played pro-inflammatory roles in the SPP1-ICAM both-up NPC group through the SPP1-CD44 pathway and ICAM1-ITGB2 ligand-receptor pathway, respectively. At the same time, both-up NPCs sought self-help inflammation remission from neutrophils through the ANXA1-FPR1 pathway. The systematic analysis of the differentiation and immune infiltration landscapes helps to understand IDD's overall development process. Our data suggest that SPP1 and ICAM1 may be new targets for the treatment of inflammatory infiltration in IDD.

The efficacy of 3D gait analysis to evaluate surgical (and rehabilitation) outcome after degenerative lumbar surgery

BACKGROUND

Lumbar degenerative conditions are a major cause of back pain and disability in individuals aged 45 and above. Gait analysis utilizes sensor technology to collect movement data, aiding in the evaluation of various gait aspects like spatiotemporal parameters, joint angles, neuromuscular activity, and joint forces. It is widely used in conditions such as cerebral palsy and knee osteoarthritis. This research aims to assess the effectiveness of 3D gait analysis in evaluating surgical outcomes and postoperative rehabilitation for lumbar degenerative disorders.

METHODS

A prospective self-controlled before-after study (n = 85) carried out at our Hospital (Sep 2018 - Dec 2021) utilized a 3D motion analysis system to analyze gait in patients with lumbar degenerative diseases. The study focused on the multifidus muscle, a crucial spinal muscle, during a minimally invasive lumbar interbody fusion surgery conducted by Shandong Weigao Pharmaceutical Co., Ltd. Pre- and postoperative assessments included time-distance parameters (gait speed, stride frequency, stride length, stance phase), hip flexion angle, and stride angle. Changes in 3D gait parameters post-surgery and during rehabilitation were examined. Pearson correlation coefficient was employed to assess relationships with the visual analog pain scale (VAS), Oswestry Disability Index (ODI), and Japanese Orthopedic Association (JOA) scores. Patient sagittal alignment was evaluated using "Surgimap" software from two types of lateral radiographs to obtain parameters like pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), intervertebral space height (DH), posterior height of the intervertebral space (PDH) at the operative segment, and anterior height of the intervertebral space (ADH).

RESULTS

By the 6th week post-operation, significant improvements were observed in the VAS score, JOA score, and ODI score of the patients compared to preoperative values (P < 0.05), along with notable enhancements in 3D gait quantification parameters (P < 0.05). Pearson correlation analysis revealed a significant positive correlation between improvements in 3D gait quantification parameters and VAS score, JOA score, and ODI value (all P < 0.001).

CONCLUSION

3D gait analysis is a valuable tool for evaluating the efficacy of surgery and rehabilitation training in patients.

Characterization and modulation of the pro-inflammatory effects of immune cells in the canine intervertebral disk

Background

Intervertebral disk (IVD) degeneration affects both humans and canines and is a major cause of low back pain (LBP). Mast cell (MC) and macrophage (MØ) infiltration has been identified in the pathogenesis of IVD degeneration (IVDD) in the human and rodent model but remains understudied in the canine. MC degranulation in the IVD leads to a pro-inflammatory cascade and activates protease activated receptor 2 (PAR2) on IVD cells. The objectives of the present study are to: (1) highlight the pathophysiological changes observed in the degenerate canine IVD, (2) further characterize the inflammatory effect of MCs co-cultured with canine nucleus pulposus (NP) cells, (3) evaluate the effect of construct stiffness on NP and MCs, and (4) identify potential therapeutics to mitigate pathologic changes in the IVD microenvironment.

Methods

Canine IVD tissue was isolated from healthy autopsy research dogs (beagle) and pet dogs undergoing laminectomy for IVD herniation. Morphology, protein content, and inflammatory markers were assessed. NP cells isolated from healthy autopsy (Mongrel hounds) tissue were co-cultured with canine MCs within agarose constructs and treated with cromolyn sodium (CS) and PAR2 antagonist (PAR2A). Gene expression, sulfated glycosaminoglycan content, and stiffness of constructs were assessed.

Results

CD 31+ blood vessels, mast cell tryptase, and macrophage CD 163+ were increased in the degenerate surgical canine tissue compared to healthy autopsy. Pro-inflammatory genes were upregulated when canine NP cells were co-cultured with MCs and the stiffer microenvironment enhanced these effects. Treatment with CS and PAR2 inhibitors mediated key pro-inflammatory markers in canine NP cells.

Conclusion

There is increased MC, MØs, and vascular ingrowth in the degenerate canine IVD tissue, similar to observations in the clinical population with IVDD and LBP. MCs co-cultured with canine NP cells drive inflammation, and CS and PAR2A are potential therapeutics that may mitigate the pathophysiology of IVDD in vitro.

Lumbar instability remodels cartilage endplate to induce intervertebral disc degeneration by recruiting osteoclasts via Hippo-CCL3 signaling

Degenerated endplate appears with cheese-like morphology and sensory innervation, contributing to low back pain and subsequently inducing intervertebral disc degeneration in the aged population.1 However, the origin and development mechanism of the cheese-like morphology remain unclear. Here in this study, we report lumbar instability induced cartilage endplate remodeling is responsible for this pathological change. Transcriptome sequencing of the endplate chondrocytes under abnormal stress revealed that the Hippo signaling was key for this process. Activation of Hippo signaling or knockout of the key gene Yap1 in the cartilage endplate severed the cheese-like morphological change and disc degeneration after lumbar spine instability (LSI) surgery, while blocking the Hippo signaling reversed this process. Meanwhile, transcriptome sequencing data also showed osteoclast differentiation related gene set expression was up regulated in the endplate chondrocytes under abnormal mechanical stress, which was activated after the Hippo signaling. Among the discovered osteoclast differentiation gene set, CCL3 was found to be largely released from the chondrocytes under abnormal stress, which functioned to recruit and promote osteoclasts formation for cartilage endplate remodeling. Over-expression of Yap1 inhibited CCL3 transcription by blocking its promoter, which then reversed the endplate from remodeling to the cheese-like morphology. Finally, LSI-induced cartilage endplate remodeling was successfully rescued by local injection of an AAV5 wrapped Yap1 over-expression plasmid at the site. These findings suggest that the Hippo signaling induced osteoclast gene set activation in the cartilage endplate is a potential new target for the management of instability induced low back pain and lumbar degeneration.

Mrgprb2-mediated mast cell activation exacerbates Modic changes by regulating immune niches

Modic changes are radiographic features associated with microfracture, low-virulence organism infection and chronic inflammation with inflammatory cell infiltration in the vertebral endplate region. Mast cells, as innate immune cells similar to macrophages, are present in painful degenerated intervertebral discs. However, the involvement and mechanisms of mast cells in the development of Modic changes remain unclear. Herein, we found increased mast cell infiltration in samples from patients with Modic changes and in mouse models of Modic changes. To clarify the role of mast cells in the progression of Modic changes, we used mast cell-deficient (KITW-SH/W-SH) mice to construct a model of Modic changes and found that the severity of Modic changes in KITW-SH/W-SH mice was significantly lower than that in WT mice. These findings were further supported by the use of a mast cell-specific activator (compound 48/80) and a stabilizer (cromolyn). Furthermore, we found that mast cells were not activated via the classic IgE pathway in the Modic change models and that Mrgprb2 is the specific receptor for mast cell activation reported in recent studies. Then, we utilized Mrgprb2 knockout mice to demonstrate that Mrgprb2 knockout inhibited mast cell activation and thus reduced the degree of Modic changes. Transcriptomic sequencing revealed aberrant PI3K-AKT and MAPK pathway activation in the Mrgprb2-deficient mast cells. Additionally, Mrgpbrb2-activated mast cells regulate immune niches by recruiting macrophages, promoting M1 polarization and reducing M2 polarization, thereby promoting the progression of Modic changes. These findings suggest that mast cells may serve as a novel therapeutic target for addressing Modic changes.

Altered serum cytokines in patients with symptomatic disk herniation and depressive symptoms

Purpose

An increasing number of studies have indicated the important role of cytokines in the development of depressive disturbances (DD). In medically ill patients, cytokines can provoked sickness behavior, the signs of which resemble DD. This results in alterations in behavior to limit energy expenditure and redirect it to cope with particular diseases. The aim of our study was to investigate the role of pro-inflammatory IL-6, TNF-α, and IL-1β and anti-inflammatory IL-10 and TGF-β in DD observed in patients suffering from pain caused by disk herniation (DH) qualified for surgery.

Patients and methods

The intensity of DD assessed by using Beck Depression Inventory, pain intensity, and functional impairment were evaluated in 70 patients with DH who were qualified for surgery. Pro-inflammatory serum levels of TNF-α, IL-1, IL-6, anti-inflammatory TGF-β, and IL-10 were measured.

Results

Elevated serum levels of TGF-β, IL-10, and IL-6 were found in the group with moderate and severe depressive symptoms (SD) compared with the groups with mild (MD) or no depressive symptoms (ND). TGF-β levels were negatively correlated with pain intensity, as assessed using the Present Pain Intensity scale in SD. Functional impairment measured using the Oswestry Disability Index was the most advanced in SD group.

Conclusion

Results of our study can suggest association between depressive disturbances and anti-inflammatory cytokines TGF-β and IL-10. Functional impairment of SD group is more severe but serum levels of TGF-β and IL-10, which are involved in the healing processes, are increased.

Engineering Sensory Ganglion Multicellular System to Model Tissue Nerve Ingrowth

Discogenic pain is associated with deep nerve ingrowth in annulus fibrosus tissue (AF) of intervertebral disc (IVD). To model AF nerve ingrowth, primary bovine dorsal root ganglion (DRG) micro-scale tissue units are spatially organised around an AF explant by mild hydrodynamic forces within a collagen matrix. This results in a densely packed multicellular system mimicking the native DRG tissue morphology and a controlled AF-neuron distance. Such a multicellular organisation is essential to evolve populational-level cellular functions and in vivo-like morphologies. Pro-inflammatory cytokine-primed AF demonstrates its neurotrophic and neurotropic effects on nociceptor axons. Both effects are dependent on the AF-neuron distance underpinning the role of recapitulating inter-tissue/organ anatomical proximity when investigating their crosstalk. This is the first in vitro model studying AF nerve ingrowth by engineering mature and large animal tissues in a morphologically and physiologically relevant environment. The new approach can be used to biofabricate multi-tissue/organ models for untangling pathophysiological conditions and develop novel therapies.

Effect of Glycemic Disorders and Habits on the Concentration of Selected Neurotrophic Factors in Patients with Lumbosacral Intervertebral Disc Degeneration

BACKGROUND

Unhealthy habits, such as overeating processed and high-calorie foods, alcohol abuse, and smoking, negatively impact human health. It has been suggested that the inflammatory process and the resulting growth of nerve fibers within the intervertebral disc (IVD) fissures is the main reason for the pain accompanying IVD degeneration (IVDD).

OBJECTIVES

The aim of this study was to determine whether smoking, alcohol consumption, overweight/obesity, or diabetes comorbidity contribute to the development of IVDD and how the aforementioned factors affect the levels of brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), and growth associated protein 43 (GAP-43) in the study and control groups (intervertebral discs, IVDs from cadavers, and serum samples from voluntary blood donors).

METHODS

The study group comprised 113 patients diagnosed with IVDD who qualified for microdiscectomy. Two control groups (I and II) were used in this study. The first included 81 IVDs obtained from Caucasian human cadavers. Control group II, on the other hand, included serum samples obtained from 113 voluntary blood donors. The expression profiles of BDNF, GDNF, and GAP-43 were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Our statistical analysis confirmed that patients who were overweight/obese, smoked tobacco, consumed alcohol, or had diabetes had a higher risk of IVDD (OR > 1). Statistical analysis showed that BDNF, GAP-43, and GDNF concentrations were significantly higher in the IVDs and serum samples obtained from the study group compared to the control group (p < 0.05). In addition, higher levels of BDNF, GDNF, and GAP-43 were noted in IVDD patients who consumed alcohol, smoked tobacco, were overweight/obese, or had comorbid diabetes compared to patients without these risk factors (p < 0.05).

CONCLUSION

We showed that changes in energy metabolism, habits, and lifestyle, as well as the degenerative process of IVD in the lumbosacral spine contribute to changing the concentration profile of the analyzed neurotrophic factors.

Intervertebral disc human nucleus pulposus cells associated with back pain trigger neurite outgrowth in vitro and pain behaviors in rats

Low back pain (LBP) is often associated with the degeneration of human intervertebral discs (IVDs). However, the pain-inducing mechanism in degenerating discs remains to be elucidated. Here, we identified a subtype of locally residing human nucleus pulposus cells (NPCs), generated by certain conditions in degenerating discs, that was associated with the onset of discogenic back pain. Single-cell transcriptomic analysis of human tissues showed a strong correlation between a specific cell subtype and the pain condition associated with the human degenerated disc, suggesting that they are pain-triggering. The application of IVD degeneration-associated exogenous stimuli to healthy NPCs in vitro recreated a pain-associated phenotype. These stimulated NPCs activated functional human iPSC-derived sensory neuron responses in an in vitro organ-chip model. Injection of stimulated NPCs into the healthy rat IVD induced local inflammatory responses and increased cold sensitivity and mechanical hypersensitivity. Our findings reveal a previously uncharacterized pain-inducing mechanism mediated by NPCs in degenerating IVDs. These findings could aid in the development of NPC-targeted therapeutic strategies for the clinically unmet need to attenuate discogenic LBP.

Spatially multicellular variability of intervertebral disc degeneration by comparative single-cell analysis

Previous studies have revealed cellular heterogeneity in intervertebral discs (IVDs). However, the cellular and molecular alteration patterns of cell populations during degenerative progression remain to be fully elucidated. To illustrate the cellular and molecular alteration of cell populations in intervertebral disc degeneration (IDD), we perform single cell RNA sequencing on cells from four anatomic sites of healthy and degenerative goat IVDs. EGLN3+ StressCs, TGFBR3+ HomCs and GPRC5A+ RegCs exhibit the characteristics associated with resistance to stress, maintaining homeostasis and repairing, respectively. The frequencies and signatures of these cell clusters fluctuate with IDD. Notably, the chondrogenic differentiation programme of PROCR+ progenitor cells is altered by IDD, while notochord cells turn to stemness exhaustion. In addition, we characterise CAV1+ endothelial cells that communicate with chondrocytes through multiple signalling pathways in degenerative IVDs. Our comprehensive analysis identifies the variability of key cell clusters and critical regulatory networks responding to IDD, which will facilitate in-depth investigation of therapeutic strategies for IDD.

Systematic Review of Platelet-Rich Plasma for Low Back Pain

BACKGROUND

Low back pain (LBP) has a high economic burden and is strongly related to the degenerative process of the spine, especially in the intervertebral disc and of the facet joints. Numerous treatment modalities have been proposed for the management of LBP, and the use of platelet-rich plasma (PRP) has emerged as an innovative therapeutic option for degenerative disease of the spine. The present study aims to evaluate the efficacy of PRP injections in managing low back pain.

METHODS

We conducted a systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations, a registered at PROSPERO Systematic Reviews Platform, under number CRD42021268491. The PubMed, Web of Science, and Scopus databases were searched to identify relevant articles, along with hand searching to identify gray literature articles, with no language restrictions. Randomized clinical trials (RCTs), nonrandomized trials (NRTs), and case series (CSs) with more than 10 patients were considered eligible. The quality assessment and the risk of bias of the randomized clinical trials were evaluated using the RoB II tool. An evaluation of the description of the preparation methods was performed using an adapted version of the MIBO checklist.

RESULTS

An electronic database search resulted in 2324 articles, and after the exclusion of noneligible articles, 13 RCTs and 27 NRTs or CSs were analyzed. Of the 13 RCTs, 11 found favorable results in comparison to the control group in pain and disability, one showed no superiority to the control group, and one was discontinued because of the lack of therapeutic effect at eight-week evaluation. Description of the PRP preparation techniques were found in almost all papers. The overall risk of bias was considered high in 2 papers and low in 11. An adapted MIBO checklist showed a 72.7% compliance rate in the selected areas.

CONCLUSIONS

In this systematic review, we analyzed articles from English, Spanish and Russian language, from large databases and grey literature. PRP was in general an effective and safe treatment for degenerative LPB. Positive results were found in almost studies, a small number of adverse events were related, the risk of bias of the RCTs was low. Based on the evaluation of the included studies, we graded as level II the quality of the evidence supporting the use of PRP in LBP. Large-scale, multicenter RCTs are still needed to confirm these findings.

The Clinical Efficacy of Autologous Platelet-Rich Plasma Interventional Circulatory Perfusion Combined with Radiofrequency Ablation and Thermocoagulation in the Treatment of Discogenic Low Back Pain

Objective

In this study, we aimed to explore the efficacy of the autologous platelet-rich plasma (PRP) interventional circulatory perfusion combined with radiofrequency ablation and thermocoagulation (RFAT) in the treatment of discogenic low back pain (DLBP).

Methods

From January 2020 to November 2022, 158 patients of the Second Affiliated Hospital of Nanchang University were selected as the study subjects, and 24 patients met the exclusion criteria. The 134 patients who met the inclusion criteria were divided into 65 patients in the control group (3 patients lost to follow-up) and 69 patients in the observation group (5 patients lost to follow-up), so 126 patients were actually completed the study, including 62 patients in the control group and 64 patients in the observation group. The control group responsible disc received RFAT, and an interventional circulatory perfusion was performed; the observation group received RFAT, and an interventional circulatory perfusion was performed, and then autologous PRP 2 ml was injected. Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) were performed before and 4 and 8 weeks after treatment, and the efficacy was evaluated at 4 and 8 weeks after treatment. The changes of lumbar disc MRI before and after treatment were observed.

Results

The differences in the Visual Analog Scale (VAS) scores and the Oswestry Disability Index (ODI) between the observation group and the control group before the treatment were not statistically significant (P > 0.05 in both). However, four weeks and eight weeks after the treatment, the VAS scores and the ODIs were significantly lower in both groups than those before the treatment (P < 0.05 in both). In terms of the therapeutic efficacy, eight weeks after the treatment, the total effective rates in the control group and the observation group were 67.7% and 87.5%, respectively, with the observation group being superior to the control group (P < 0.05).

Conclusion

After RFAT, interventional circulatory perfusion combined with autologous PRP intramedullary injection in the lumbar disc is a safe and effective treatment for DLBP, and it had superior long-term effects in improving the clinical symptoms and patient dysfunction than the RFAT and interventional circulatory perfusion.

CX3CL1/CX3CR1 axis alleviates inflammation and apoptosis in human nucleus pulpous cells via M2 macrophage polarization

CX3C chemokine ligand 1 (CX3CL1) belongs to the CX3C chemokine family and is involved in various disease processes. However, its role in intervertebral disc degeneration (IDD) remains to be elucidated. In the present study, western blotting, reverse transcription-quantitative PCR and ELISA assays were used to assess target gene expression. In addition, immunofluorescence and TUNEL staining were used to assess macrophage infiltration, monocyte migration and apoptosis. The present study aimed to reveal if and how CX3CL1 regulates IDD progression by exploring its effect on macrophage polarization and apoptosis of human nucleus pulposus cells (HNPCs). The data showed that CX3CL1 bound to CX3C motif chemokine receptor 1 (CX3CR1) promoted the M2 phenotype polarization via JAK2/STAT3 signaling, followed by increasing the secretion of anti-inflammatory cytokines from HNPCs. In addition, HNPC-derived CX3CL1 promoted M2 macrophage-derived C-C motif chemokine ligand 17 release thereby reducing the apoptosis of HNPCs. In clinic, the reduction of mRNA and protein levels CX3CL1 in degenerative nucleus pulposus tissues (NPs) was measured. Increased M1 macrophages and pro-inflammatory cytokines were found in NPs of IDD patients with low CX3CL1 expression. Collectively, these findings suggested that the CX3CL1/CX3CR1 axis alleviates IDD by reducing inflammation and apoptosis of HNPCs via macrophages. Therefore, targeting CX3CL1/CX3CR1 axis is expected to produce a new therapeutic approach for IDD.

Defining the Patient with Lumbar Discogenic Pain: Real-World Implications for Diagnosis and Effective Clinical Management

There is an enormous body of literature that has identified the intervertebral disc as a potent pain generator. However, with regard to lumbar degenerative disc disease, the specific diagnostic criteria lack clarity and fail to capture the primary components which include axial midline low back pain with or without non-radicular/non-sciatic referred leg pain in a sclerotomal distribution. In fact, there is no specific ICD-10-CM diagnostic code to classify and define discogenic pain as a unique source of pain distinct from other recognized sources of chronic low back pain including facetogenic, neurocompressive including herniation and/or stenosis, sacroiliac, vertebrogenic, and psychogenic. All of these other sources have well-defined ICD-10-CM codes. Corresponding codes for discogenic pain remain absent from the diagnostic coding vernacular. The International Society for the Advancement of Spine Surgery (ISASS) has proposed a modernization of ICD-10-CM codes to specifically define pain associated with lumbar and lumbosacral degenerative disc disease. The proposed codes would also allow the pain to be characterized by location: lumbar region only, leg only, or both. Successful implementation of these codes would benefit both physicians and payers in distinguishing, tracking, and improving algorithms and treatments for discogenic pain associated with intervertebral disc degeneration.

ISSLS PRIZE in basic science 2023: Lactate in lumbar discs-metabolic waste or energy biofuel? Insights from in vivo MRS and T2r analysis following exercise and nimodipine in healthy volunteers

PURPOSE

To quantitatively assess the dynamic changes of Lactate in lumbar discs under different physiological conditions using MRS and T2r.

METHODS

In step1, MRS and T2r sequences were standardized in 10 volunteers. Step2, analysed effects of high cellular demand. 66 discs of 20 volunteers with no back pain were evaluated pre-exercise (EX-0), immediately after targeted short-time low back exercises (EX-1) and 60 min after (EX-2). In Step 3, to study effects of high glucose and oxygen concentration, 50 lumbar discs in 10 volunteers were analysed before (D0) and after 10 days intake of the calcium channel blocker, nimodipine (D1).

RESULTS

Lactate showed a distinctly different response to exercise in that Grade 1 discs with a significant decrease in EX-1 and a trend for normalization in Ex-2. In contrast, Pfirrmann grade 2 and 3 and discs above 40 years showed a higher lactate relative to proteoglycan in EX-0, an increase in lactate EX-1 and mild dip in Ex-2. Similarly, following nimodipine, grade 1 discs showed an increase in lactate which was absent in grade 2 and 3 discs. In contrast, exercise and Nimodipine had no significant change in T2r values and MRS spectrum of proteoglycan, N-acetyl aspartate, carbohydrate, choline, creatine, and glutathione across age groups and Pfirrmann grades.

CONCLUSION

MRS documented changes in lactate response to cellular demand which suggested a 'Lactate Symbiotic metabolic Pathway'. The differences in lactate response preceded changes in Proteoglycan/hydration and thus could be a dynamic radiological biomarker of early degeneration.

Intervertebral disc degeneration and how it leads to low back pain

The purpose of this review was to evaluate data generated by animal models of intervertebral disc (IVD) degeneration published in the last decade and show how this has made invaluable contributions to the identification of molecular events occurring in and contributing to pain generation. IVD degeneration and associated spinal pain is a complex multifactorial process, its complexity poses difficulties in the selection of the most appropriate therapeutic target to focus on of many potential candidates in the formulation of strategies to alleviate pain perception and to effect disc repair and regeneration and the prevention of associated neuropathic and nociceptive pain. Nerve ingrowth and increased numbers of nociceptors and mechanoreceptors in the degenerate IVD are mechanically stimulated in the biomechanically incompetent abnormally loaded degenerate IVD leading to increased generation of low back pain. Maintenance of a healthy IVD is, thus, an important preventative measure that warrants further investigation to preclude the generation of low back pain. Recent studies with growth and differentiation factor 6 in IVD puncture and multi-level IVD degeneration models and a rat xenograft radiculopathy pain model have shown it has considerable potential in the prevention of further deterioration in degenerate IVDs, has regenerative properties that promote recovery of normal IVD architectural functional organization and inhibits the generation of inflammatory mediators that lead to disc degeneration and the generation of low back pain. Human clinical trials are warranted and eagerly anticipated with this compound to assess its efficacy in the treatment of IVD degeneration and the prevention of the generation of low back pain.

Development of a Nanohybrid Peptide Hydrogel for Enhanced Intervertebral Disc Repair and Regeneration

Effective therapeutic approaches to overcome the heterogeneous pro-inflammatory and inhibitory extracellular matrix (ECM) microenvironment are urgently needed to achieve robust structural and functional repair of severely wounded fibrocartilaginous tissues. Herein we developed a dynamic and multifunctional nanohybrid peptide hydrogel (NHPH) through hierarchical self-assembly of peptide amphiphile modified with biodegradable two-dimensional nanomaterials with enzyme-like functions. NHPH is not only injectable, biocompatible, and biodegradable but also therapeutic by catalyzing the scavenging of pro-inflammatory reactive oxygen species and promoting ECM remodeling. In addition, our NHPH method facilitated the structural and functional recovery of the intervertebral disc (IVD) after severe injuries by delivering pro-regenerative cytokines in a sustained manner, effectively suppressing immune responses and eventually restoring the regenerative microenvironment of the ECM. In parallel, the NHPH-enhanced nucleus pulposus cell differentiation and pain reduction in a rat nucleotomy model further validated the therapeutic potential of NHPH. Collectively, our advanced nanoscaffold technology will provide an alternative approach for the effective treatment of IVD degeneration as well as other fibrocartilaginous tissue injuries.

Macrophages and Intervertebral Disc Degeneration

The intervertebral disc (IVD) aids in motion and acts to absorb energy transmitted to the spine. With little inherent regenerative capacity, degeneration of the intervertebral disc results in intervertebral disc disease, which contributes to low back pain and significant disability in many individuals. Increasing evidence suggests that IVD degeneration is a disease of the whole joint that is associated with significant inflammation. Moreover, studies show elevated macrophage accumulation within the IVD with increasing levels of disease severity; however, we still need to understand the roles, be they causative or consequential, of macrophages during the degenerative process. In this narrative review, we discuss hallmarks of IVD degeneration, showcase evidence of macrophage involvement during disc degeneration, and explore burgeoning research aimed at understanding the molecular pathways regulating macrophage functions during intervertebral disc degeneration.

Immune exposure: how macrophages interact with the nucleus pulposus

Intervertebral disc degeneration (IDD) is a primary contributor to low back pain. Immune cells play an extremely important role in modulating the progression of IDD by interacting with disc nucleus pulposus (NP) cells and extracellular matrix (ECM). Encased within the annulus fibrosus, healthy NP is an avascular and immune-privileged tissue that does not normally interact with macrophages. However, under pathological conditions in which neovascularization is established in the damaged disc, NP establishes extensive crosstalk with macrophages, leading to different outcomes depending on the different microenvironmental stimuli. M1 macrophages are a class of immune cells that are predominantly pro-inflammatory and promote inflammation and ECM degradation in the NP, creating a vicious cycle of matrix catabolism that drives IDD. In contrast, NP cells interacting with M2 macrophages promote disc tissue ECM remodeling and repair as M2 macrophages are primarily involved in anti-inflammatory cellular responses. Hence, depending on the crosstalk between NP and the type of immune cells (M1 vs. M2), the overall effects on IDD could be detrimental or regenerative. Drug or surgical treatment of IDD can modulate this crosstalk and hence the different treatment outcomes. This review comprehensively summarizes the interaction between macrophages and NP, aiming to highlight the important role of immunology in disc degeneration.

Whole-transcriptome sequencing identifies key differentially expressed circRNAs/lncRNAs/miRNAs/mRNAs and linked ceRNA networks in adult degenerative scoliosis

Background

Adult degenerative scoliosis (ADS) is forecast to be a prevalent disabling condition in an aging society. Universally, its pathogenesis is perceived as intervertebral disc degeneration (IDD), however, a thought-provoking issue is why precisely a subset of patients with disc degeneration develop ADS. Exploring the diversities between common IDD and ADS would contribute to unraveling the etiological mechanisms of ADS. Therefore, we aimed to integrate the circRNA, lncRNA, miRNA, and mRNA expression profiles from normal adults (Normal), patients with lumbar disc herniation (LDH), and ADS by whole transcriptome sequencing, which identifies critical functional ncRNA and ceRNA networks and crosstalk between the various transcripts.

Methods

The fresh whole blood samples (n = 3/group) were collected from ADS patients, LDH patients, and healthy volunteers (Normal group), which were examined for mRNA, miRNA, lncRNA, and circRNA expression and screened for differentially expressed (DE) ncRNAs. Then, Gene Ontology (GO) and KEGG analyses were performed for gene annotation and enrichment pathways on the DE RNAs, which were constructed as a lncRNA-miRNA-mRNA network. Eventually, DE RNAs were validated by qRT-PCR targeting disc nucleus pulposus (NP) tissue in ADS and LDH group (n = 10/group).

Results

Compared to the LDH group, we identified 3322 DE mRNAs, 221 DE lncRNAs, 20 DE miRNAs, and 15 DE circRNAs in the ADS. In contrast to Normal, 21 miRNAs and 19 circRNAs were differentially expressed in the ADS. The expression of multiple differentially expressed ncRNAs was confirmed by qRT-PCR analysis to be consistent with the sequencing results. In addition, GO, and KEGG analysis demonstrated that most DE mRNAs and ncRNAs target genes are involved in various biological processes, including Endocytosis, Apoptosis, Rap1 signaling pathway, Notch signaling pathway, and others. The constructed lncRNA-miRNA-mRNA co-expression network was primarily related to angiogenesis and regulation.

Conclusion

By focusing on comparing asymmetric and symmetric disc degeneration, whole-transcriptome sequencing and bioinformatics analysis systematically screened for key ncRNAs in the development of ADS, which provided an abundance of valuable candidates for the elucidation of regulatory mechanisms. The DE ncRNAs and the lncRNA-miRNA-mRNA network are intrinsically involved in the regulation of mediator and angiogenesis, which may contribute to the insight into the pathogenesis of ADS.

Barriers to mesenchymal stromal cells for low back pain

Intervertebral disc degeneration is the main cause of low back pain. In the past 20 years, the injection of mesenchymal stromal cells (MSCs) into the nucleus pulposus of the degenerative disc has become the main approach for the treatment of low back pain. Despite the progress made in this field, there are still many barriers to overcome. First, intervertebral disc is a highly complex load-bearing composite tissue composed of annulus fibrosus, nucleus pulposus and cartilaginous endplates. Any structural damage will change its overall biomechanical function, thereby causing progressive degeneration of the entire intervertebral disc. Therefore, MSC-based treatment strategies should not only target the degenerated nucleus pulposus but also include degenerated annulus fibrosus or cartilaginous endplates. Second, to date, there has been relatively little research on the basic biology of annulus fibrosus and cartilaginous endplates, although their pathological changes such as annular tears or fissures, Modic changes, or Schmorl's nodes are more commonly associated with low back pain. Given the high complexity of the structure and composition of the annulus fibrosus and cartilaginous endplates, it remains an open question whether any regeneration techniques are available to achieve their restorative regeneration. Finally, due to the harsh microenvironment of the degenerated intervertebral disc, the delivered MSCs die quickly. Taken together, current MSC-based regenerative medicine therapies to regenerate the entire disc complex by targeting the degenerated nucleus pulposus alone are unlikely to be successful.

Complex Regional Pain Syndrome after Spine Surgery: A Rare Complication in Mini-Invasive Lumbar Spine Surgery: An Updated Comprehensive Review

BACKGROUND

Complex regional pain syndrome (CRPS) is a postoperative, misdiagnosed condition highlighted only by pain therapists after numerous failed attempts at pain control by the treating surgeon in the case of prolonged pain after surgery. It only occurs rarely after spine surgery, causing the neurosurgeon's inappropriate decision to resort to a second surgical treatment.

METHODS

We performed a systematic review of the literature reporting and analyzing all recognized and reported cases of CRPS in patients undergoing spinal surgery to identify the best diagnostic and therapeutic strategies for this unusual condition. We compare our experience with the cases reported through a review of the literature.

RESULTS

We retrieve 20 articles. Most of the papers are clinical cases showing the disorder's rarity after spine surgery. Most of the time, the syndrome followed uncomplicated lumbar spine surgery involving one segment. The most proposed therapy was chemical sympathectomy and spinal cord stimulation.

CONCLUSION

CRPS is a rare pathology and is rarer after spine surgery. However, it is quite an invalidating disorder. Early therapy and resolution, however, require a rapid diagnosis of the syndrome. In our opinion, since CRPS occurs relatively rarely following spinal surgery, it should not have a substantial impact on the indications for and timing of these operations. Therefore, it is essential to diagnose this rare occurrence and treat it promptly and appropriately.

Controversies in spine research: Organ culture versus in vivo models for studies of the intervertebral disc

Intervertebral disc degeneration is a common cause of low back pain, the leading cause of disability worldwide. Appropriate preclinical models for intervertebral disc research are essential to achieving a better understanding of underlying pathophysiology and for the development, evaluation, and translation of more effective treatments. To this end, in vivo animal and ex vivo organ culture models are both widely used by spine researchers; however, the relative strengths and weaknesses of these two approaches are a source of ongoing controversy. In this article, members from the Spine and Preclinical Models Sections of the Orthopedic Research Society, including experts in both basic and translational spine research, present contrasting arguments in support of in vivo animal models versus ex vivo organ culture models for studies of the disc, supported by a comprehensive review of the relevant literature. The objective is to provide a deeper understanding of the respective advantages and limitations of these approaches, and advance the field toward a consensus with respect to appropriate model selection and implementation. We conclude that complementary use of several model types and leveraging the unique advantages of each is likely to result in the highest impact research in most instances.

Effect of regulating macrophage polarization phenotype on intervertebral disc degeneration

Background

Macrophages are the only inflammatory cells that can penetrate the closed nucleus pulposus and their polarization plays an important role in intervertebral disc degeneration (IVDD). This paper attempted to investigate the pathogenesis of IVDD by altering the polarization state of macrophages.

Methods

Macrophage RAW264.7 cells were induced by interferonγ (IFN‐γ) and lipopolysaccharide (LPS). The polarization of RAW264.7 cells was estimated by western blot and immunofluorescence. The expressions of inflammatory factors were detected by ELISA. Subsequently, RAW264.7 cells were treated with different concentrations of minocycline (Mino) and sinomenine (Sino), followed by the assessment of cell viability with cell counting kit‐8 kit. Then, RAW264.7 cell culture medium was collected for the culture of human nucleus pulposus cells (NPCs). Toluidine blue staining and type II collagen staining were applied to assay the level of type II collagen. The cell apoptosis, oxidative stress, and nitric oxide (NO) level were appraised by TUNEL, oxidative stress kits and NO kit, respectively. Western blot was employed to test the levels of apoptosis‐ and oxidative stress‐related proteins.

Results

IFN‐γ and LPS could induce M1 polarization of RAW264.7 cells. Mino and Sino could reduce the polarization of RAW264.7 cells toward M1. M1‐polarized medium inhibited LPS‐induced activity, inflammation, and damage of NPCs, which were enhanced by Mino and Sino in medium.

Conclusion

M1 polarization of macrophages promoted LPS‐induced inflammation and damage of NPCs.

Integrative Bioinformatics Analysis Revealed Mitochondrial Dysfunction-Related Genes Underlying Intervertebral Disc Degeneration

Objective

Mitochondrial dysfunction plays an important role in intervertebral disc degeneration (IDD). We aim to explore the pathways and key genes that cause mitochondrial dysfunction during IDD and to further reveal the pathogenesis of IDD based on bioinformatic analyses.

Methods

Datasets GSE70362 and GSE124272 were downloaded from the Gene Expression Omnibus. Differentially expressed genes (DEGs) of mitochondrial dysfunction between IDD patients and healthy controls were screened by package limma package. Critical genes were identified by adopting gene ontology (GO), Kyoto encyclopedia of genes and genomes (KEGG) pathways, and protein-protein interaction (PPI) networks. We collected both degenerated and normal disc tissues obtained surgically, and we performed western blot and qPCR to verify the key DEGs identified in intervertebral disc tissues.

Results

In total, 40 cases of IDD and 24 healthy controls were included. We identified 152 DEGs, including 67 upregulated genes and 85 downregulated genes. Four genes related to mitochondrial dysfunction (SOX9, FLVCR1, NR5A1 and UCHL1) were screened out. Of them, SOX9, FLVCR1, and UCHL1 were down-regulated in peripheral blood and intervertebral disc tissues of IDD patients, while NR5A1 was up-regulated. The analysis of immune infiltration showed the concentrations of mast cells activated were significantly the highest in IDD patients. Compared with the control group, the level of T cells CD4 memory resting was the lowest in the patients. In addition, 24 cases of IDD tissues and 12 cases of normal disc tissues were obtained to verify the results of bioinformatics analysis. Both western blot and qPCR results were consistent with the results of bioinformatics analysis.

Conclusion

We identified four genes (SOX9, FLVCR1, NR5A1 and UCHL1) associated with mitochondrial dysfunction that play an important role in the progress of disc degeneration. The identification of these differential genes may provide new insights for the diagnosis and treatment of IDD.

Microfluidic Electroceuticals Platform for Therapeutic Strategies of Intervertebral Disc Degeneration: Effects of Electrical Stimulation on Human Nucleus Pulposus Cells under Inflammatory Conditions

The degeneration of an intervertebral disc (IVD) is a major cause of lower back pain. IVD degeneration is characterized by the abnormal expression of inflammatory cytokines and matrix degradation enzymes secreted by IVD cells. In addition, macrophage-mediated inflammation is strongly associated with IVD degeneration. However, the precise pathomechanisms of macrophage-mediated inflammation in IVD are still unknown. In this study, we developed a microfluidic platform integrated with an electrical stimulation (ES) array to investigate macrophage-mediated inflammation in human nucleus pulposus (NP). This platform provides multiple cocultures of different cell types with ES. We observed macrophage-mediated inflammation and considerable migration properties via upregulated expression of interleukin (IL)-6 (p < 0.001), IL-8 (p < 0.05), matrix metalloproteinase (MMP)-1 (p < 0.05), and MMP-3 (p < 0.05) in human NP cells cocultured with macrophages. We also confirmed the inhibitory effects of ES at 10 μA due to the production of IL-6 (p < 0.05) and IL-8 (p < 0.01) under these conditions. Our findings indicate that ES positively affects degenerative inflammation in diverse diseases. Accordingly, the microfluidic electroceutical platform can serve as a degenerative IVD inflammation in vitro model and provide a therapeutic strategy for electroceuticals.

Axial hypersensitivity is associated with aberrant nerve sprouting in a novel model of disc degeneration in female Sprague Dawley rats

Chronic low back pain is a global socioeconomic crisis and treatments are lacking in part due to inadequate models. Etiological research suggests that the predominant pathology associated with chronic low back pain is intervertebral disc degeneration. Various research teams have created rat models of disc degeneration, but the clinical translatability of these models has been limited by an absence of robust chronic pain-like behavior. To address this deficit, disc degeneration was induced via an artificial annular tear in female Sprague Dawley rats. The subsequent degeneration, which was allowed to progress for 18-weeks, caused a drastic reduction in disc volume. Furthermore, from week 10 till study conclusion, injured animals exhibited significant axial hypersensitivity. At study end, intervertebral discs were assessed for important characteristics of human degenerated discs: extracellular matrix breakdown, hypocellularity, inflammation, and nerve sprouting. All these aspects were significantly increased in injured animals compared to sham controls. Also of note, 20 significant correlations were detected between selected outcomes including a moderate and highly significant correlation (R = 0.59, p < 0.0004) between axial hypersensitivity and disc nerve sprouting. These data support this model as a rigorous platform to explore the pathobiology of disc-associated low back pain and to screen treatments.

Platelet-rich plasma-derived exosomes attenuate intervertebral disc degeneration by promoting NLRP3 autophagic degradation in macrophages

Intervertebral disc degeneration (IDD) is a common orthopedic multifactorial disease associated with spine-related disorders, such as low back pain. Recent studies have shown that both platelet-rich plasma (PRP) and exosomes could be used to treat IDD, but the effects and mechanism of PRP-derived exosomes in the treatment of IDD are still unclear. This study showed that PRP-derived exosomes inhibited the polarization of M1 macrophages by regulating the NF-κB and MAPK pathways and affected the polarization of M2 macrophages by regulating STAT6 phosphorylation. Additionally, PRP-derived exosomes promoted the autophagic degradation of NLRP3 by increasing NLRP3 ubiquitination and reducing IL-1β and Caspase-1 production. Moreover, PRP-derived exosomes could reduce IL-1β-induced apoptosis of nucleus pulposus cells. Lastly, in vivo experiments confirmed that PRP-derived exosomes reduced the expression of inflammatory mediators and apoptotic factors, which could thereby alleviate the progression of IDD. Taken together, these data showed that PRP-derived exosomes could alleviate the IDD-associated inflammation by regulating the ubiquitination and autophagic degradation of NLRP3 inflammasome, providing new insights into the treatment of IDD.

Computational Analysis of the Immune Infiltration Pattern and Candidate Diagnostic Biomarkers in Lumbar Disc Herniation

Objectives

Lumbar disc herniation (LDH) is a musculoskeletal disease that contributes to low back pain, sciatica, and movement disorder. Existing studies have suggested that the immune environment factors are the primary contributions to LDH. However, its etiology remains unknown. We sought to identify the potential diagnostic biomarkers and analyze the immune infiltration pattern in LDH.

Methods

The whole-blood gene expression level profiles of GSE124272 and GSE150408 were downloaded from the Gene Expression Omnibus (GEO) database, including that of 25 patients with LDH and 25 healthy volunteers. After merging the two microarray datasets, Differentially Expressed Genes (DEGs) were screened, and a functional correlation analysis was performed. The Least Absolute Shrinkage and Selection Operator (LASSO) logistic regression algorithm and support vector machine recursive feature elimination (SVM-RFE) were applied to identify diagnostic biomarkers by a cross-validation method. Then, the GSE42611 dataset was used as a validation dataset to detect the expression level of these diagnostic biomarkers in the nucleus pulposus and evaluate their accuracy. The hub genes in the network were identified by the CIBERSORT tool and the Weighted Gene Coexpression Network Analysis (WGCNA). A Spearman correlation analysis between diagnostic markers and infiltrating immune cells was conducted to further illustrate the molecular immune mechanism of LDH.

Results

The azurophil granule and the systemic lupus erythematosus pathway were significantly different between the healthy group and the LDH group after gene enrichment analysis. The XLOC_l2_012836, lnc-FGD3-1, and scavenger receptor class A member 5 were correlated with the immune cell infiltration in various degrees. In addition, five hub genes that correlated with LDH were identified, including AQP9, SIRPB2, SLC16A3, LILRB3, and HSPA6.

Conclusion

The XLOC_l2_012836, lnc-FGD3-1, and SCARA5 might be adopted for the early diagnosis of LDH. The five identified hub genes might have similar pathological mechanisms that contribute to the degeneration of the lumbar disc. The identified hub genes and immune infiltrating pattern extend the knowledge on the potential functioning mechanisms, which offer guidance for the development of therapeutic targets of LDH.

Does the Intradiscal Injection of Platelet Rich Plasma Have Any Beneficial Role in the Management of Lumbar Disc Disease?

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVES

We performed this meta-analysis to evaluate whether intradiscal Platelet Rich Plasma(PRP) injection has any beneficial role in the management of lumbar disc disease.

METHODS

We conducted independent and duplicate electronic database searches including PubMed, Embase, and Cochrane Library till September 2020 for studies investigating the role of intradiscal PRP in the management of lumbar disc disease. The analysis was performed in the R platform using OpenMeta[Analyst] software.

RESULTS

13 studies including 2 RCTs, 5 prospective, and 6 retrospective studies involving 319 patients were included in the meta-analysis. A single-arm meta-analysis of the included studies showed a beneficial effect of the intervention in terms of pain relief outcomes like VAS score (p < 0.001), pain component of SF-36 (p = 0.003) while such improvement was not seen in functional outcome measures like ODI score (p = 0.071), the physical component of SF-36 (p = 0.130) with significant heterogeneity noted among the included studies. No structural improvement in magnetic resonance imaging was observed (p = 0.106). No additional procedure-related adverse events were noted in the included studies (p = 0.662).

CONCLUSION

There is a paucity of high-quality studies to give conclusive evidence on the benefits of intradiscal PRP for lumbar disc disease. Although intradiscal PRP injection has shown some beneficial effect in controlling pain for lumbar disc disease, we could not find structural or functional improvement from the included studies. Hence, we recommend large double-blind double-arm randomized controlled studies to analyze the benefits of the intervention being analyzed.

Current Knowledge and Future Therapeutic Prospects in Symptomatic Intervertebral Disc Degeneration

Intervertebral disc (IVD) degeneration is the main source of intractable lower back pain, and symptomatic IVD degeneration could be due to different degeneration mechanisms. In this article, we describe the molecular basis of symptomatic IVD degenerative disc diseases (DDDs), emphasizing the role of degeneration, inflammation, angiogenesis, and extracellular matrix (ECM) regulation during this process. In symptomatic DDD, pro-inflammatory mediators modulate catabolic reactions, resulting in changes in ECM homeostasis and, finally, neural/vascular ingrowth-related chronic intractable discogenic pain. In ECM homeostasis, anabolic protein-regulating genes show reduced expression and changes in ECM production, while matrix metalloproteinase gene expression increases and results in aggressive ECM degradation. The resultant loss of normal IVD viscoelasticity and a concomitant change in ECM composition are key mechanisms in DDDs. During inflammation, a macrophage-related cascade is represented by the secretion of high levels of pro-inflammatory cytokines, which induce inflammation. Aberrant angiogenesis is considered a key initiative pathologic step in symptomatic DDD. In reflection of angiogenesis, vascular endothelial growth factor expression is regulated by hypoxia-inducible factor-1 in the hypoxic conditions of IVDs. Furthermore, IVD cells undergoing degeneration potentially enhance neovascularization by secreting large amounts of angiogenic cytokines, which penetrate the IVD from the outer annulus fibrosus, extending deep into the outer part of the nucleus pulposus. Based on current knowledge, a multi-disciplinary approach is needed in all aspects of spinal research, starting from basic research to clinical applications, as this will provide information regarding treatments for DDDs and discogenic pain.

Effectiveness of intradiscal platelet rich plasma for discogenic low back pain without Modic changes: A randomized controlled trial

Objective

To determine if autologous platelet-rich plasma (PRP) injection into a degenerative intervertebral disc, without Modic changes on magnetic resonance imaging (MRI), improve pain and function.

Design

Prospective, randomized controlled study.

Setting

Outpatient spine practice (Stichting Rugpoli, Netherlands).

Participants

Adults with chronic low back pain referred to Stichting Rugpoli, according to the Dutch General Practitioners Guidelines, unresponsive to conservative treatment, without Modic changes on MRI.

Methods

Provocation discography was performed to confirm the suspected disc was the source of pain. Participants were randomized to receive 1.0 ​cc intradiscal PRP (intervention) or 1.0 ​cc Saline with 0.2g Kefzol (control). Data on pain (Numeric Rating Scale), physical function (Roland Morris Disabilty Questionnaire, RMDQ), and participants' general perceived health (SF-12) were collected at 1 week, 4 weeks, 2 months, 6 months, 9 months and 1 year. A repeated-measures analysis (mixed model) was used for comparing the outcomes of the groups.

Results

Of the initial 98 (49 intervention, 49 control) patients randomized, 89 (91%) (44 intervention, 45 control) with complete outcome data were analyzed. Groups were balanced at baseline. After twelve months no differences between groups were found in the average pain (improved 21/44 in intervention vs 16/45 in control, p ​= ​0.244), the disability scores (RMDQ minimal 3 points improvement 22/44 in intervention vs 24/45 in control, p ​= ​0.753) and the SF-12 (mean difference physical health -1.19, 95% CI -5.39 to 2.99, p ​= ​0.721, and mental health -0.34, 95% CI -3.99 to 3.29, p ​= ​0.834). One serious adverse event occurred (spondylodiscitis) after intervention.

Conclusion

Participants who received intradiscal PRP showed no significant improvement in pain or functionality compared to the control group at 1 year follow up.

Rebalance of the Polyamine Metabolism Suppresses Oxidative Stress and Delays Senescence in Nucleus Pulposus Cells

Intervertebral disk degeneration (IDD) is a major cause of low back pain that becomes a prevalent age-related disease. However, the pathophysiological processes behind IDD are rarely known. Here, we used bioinformatics analysis based on the microarray datasets (GSE34095) to identify the differentially expressed genes (DEGs) as biomarkers and therapeutic targets in degenerated discs. From the previous studies, oxidative stress has been notified as a positive inducement of IDD, which causes DNA damage and accelerates cell senescence. Polyamine oxidase (PAOX), a member of the observed 1057 DEGs, is involved in polyamine metabolism and influences the oxidative balance in cells. However, it is uncertain if the IDD is implicated in the dysregulation of PAOX and polyamine metabolism. This study firstly verified the PAOX upregulation in human degenerated disc samples and applied an IL-1β-induced nucleus pulposus (NP) cell degeneration model to demonstrate that spermidine supplementation balanced polyamine metabolism and delayed NP cell senescence. Moreover, we confirmed that spermidine/N-acetylcysteine supplementation or Cdkn2a gene deletion stabilized the polyamine metabolism, suppressed oxidative stress, and therefore delayed the progress of IDD in older mice. Collectively, our study highlights the role of polyamine metabolism in IDD and foresees spermidine would be the advanced therapeutical drug for IDD.

Fibroblasts: the neglected cell type in peripheral sensitisation and chronic pain? A review based on a systematic search of the literature

Chronic pain and its underlying biological mechanisms have been studied for many decades, with a myriad of molecules, receptors and cell types known to contribute to abnormal pain sensations. Besides an obvious role for neurons, immune cells like microglia, macrophages and T cells are also important drivers of persistent pain. While neuroinflammation has therefore been widely studied in pain research, there is one cell type that appears to be rather neglected in this context: the humble fibroblast. Fibroblasts may seem unassuming but actually play a major part in regulating immune cell function and driving chronic inflammation. Here, our aim was to determine the breadth and quality of research that implicates fibroblasts in chronic pain conditions and models.

OBJECTIVES

We set out to analyse the current literature on this topic-using systematic screening and data extraction methods to obtain a balanced view on what has been published.

METHODS

We categorised the articles we included-stratifying them according to what was investigated, the estimated quality of results and any common conclusions.

RESULTS

We found that there has been surprisingly little research in this area: 134 articles met our inclusion criteria, only a tiny minority of which directly investigated interactions between fibroblasts and peripheral neurons.

CONCLUSIONS

Fibroblasts are a ubiquitous cell type and a prominent source of many proalgesic mediators in a wide variety of tissues. We think that they deserve a more central role in pain research and propose a new, testable model of how fibroblasts might drive peripheral neuron sensitisation.

Microfluidic Chip with Low Constant-Current Stimulation (LCCS) Platform: Human Nucleus Pulposus Degeneration In Vitro Model for Symptomatic Intervertebral Disc

Intervertebral disc (IVD) degeneration is a major cause of low back pain (LBP) in the lumbar spine. This phenomenon is caused by several processes, including matrix degradation in IVD tissues, which is mediated by matrix metalloproteinases (MMPs) and inflammatory responses, which can be mediated by interactions among immune cells, such as macrophages and IVD cells. In particular, interleukin (IL)-1 beta (β), which is a master regulator secreted by macrophages, mediates the inflammatory response in nucleus pulposus cells (NP) and plays a significant role in the development or progression of diseases. In this study, we developed a custom electrical stimulation (ES) platform that can apply low-constant-current stimulation (LCCS) signals to microfluidic chips. Using this platform, we examined the effects of LCCS on IL-1β-mediated inflammatory NP cells, administered at various currents (5, 10, 20, 50, and 100 μA at 200 Hz). Our results showed that the inflammatory response, induced by IL-1β in human NP cells, was successfully established. Furthermore, 5, 10, 20, and 100 μA LCCS positively modulated inflamed human NP cells' morphological phenotype and kinetic properties. LCCS could affect the treatment of degenerative diseases, revealing the applicability of the LCCS platform for basic research of electroceuticals.

Effects of cyclic compression on intervertebral disc metabolism using a whole-organ rat tail model

Many factors contribute to the development and progression of intervertebral disc (IVD) degeneration. This study was designed to assess the effects of compressive load magnitude on IVD metabolism. It was hypothesized that as load magnitude increased, there would be a significant increase in release of proinflammatory and degradative biomarkers, and a significant decrease in tissue proteoglycan (GAG) and collagen contents compared with unloaded controls. IVD whole organ functional spinal units (FSU) consisting of cranial and caudal body halves, cartilage endplates, and IVD (n = 36) were harvested from the tails of six Sprague Dawley rats, and FSUs were cultured at 0.0 MPa, 0.5 MPa, or 1.0 MPa at 0.5 Hz for 3 days. After culture, media were collected for biomarker analysis and FSUs were analyzed for extracellular matrix composition. Significant differences were determined using a one-way analysis of variance or Kruskal-Wallis test and post hoc analyses. Media concentrations of IFN-γ, IL-6, IL-1β, and MMP-8 were significantly higher in the 0.5 MPa compared with the 0.0 MPa group. Media concentrations of PGE2 and TIMP-1 were significantly higher in the 1.0 MPa group compared with the 0.0 MPa group, and media PGE2 was significantly higher in the 1.0 MPa group compared with the 0.5 MPa group. Media GAG content was significantly higher in the 1.0 MPa group compared with the 0.0 MPa group, and percent GAG in the tissue was significantly lower in 0.5 MPa and 1.0 MPa groups compared with the 0.0 MPa group. Clinical Significance: These data suggest that there are magnitude-dependent inflammatory and degradative IVD responses to cyclic loading, which may contribute to IVD degeneration.

Cervical spine MRI phenotypes and prediction of pain, disability and adjacent segment degeneration/disease after ACDF

Degenerative spine imaging findings have been extensively studied in the lumbar region and are associated with pain and adverse clinical outcomes after surgery. However, few studies have investigated the significance of these imaging "phenotypes" in the cervical spine. Patients with degenerative cervical spine pathology undergoing anterior cervical discectomy and fusion (ACDF) from 2008 to 2015 were retrospectively and prospectively assessed using preoperative MRI for disc degeneration, narrowing, and displacement, high-intensity zones, endplate abnormalities, Modic changes, and osteophyte formation from C2-T1. Points were assigned for these phenotypes to generate a novel Cervical Phenotype Index (CPI). Demographics were evaluated for association with phenotypes and the CPI using forward stepwise regression. Bootstrap sampling and multiple imputations assessed phenotypes and the CPI in association with patient-reported outcomes (Neck Disability Index [NDI], Visual Analog Scale [VAS]-neck, VAS-arm) and adjacent segment degeneration (ASDeg) and disease (ASDz). Of 861 patients, disc displacement was the most common (99.7%), followed by osteophytes (92.0%) and endplate abnormalities (57.3%). Most findings were associated with age and were identified at similar cervical vertebral levels; at C5-C7. Imaging phenotypes demonstrated both increased and decreased associations with adverse patient-reported outcomes and ASDeg/Dz. However, the CPI consistently predicted worse NDI (P = .012), VAS-neck (P = .007), and VAS-arm (P = .013) scores, in addition to higher odds of ASDeg (P = .002) and ASDz (P = .004). The CPI was significantly predictive of postoperative symptoms of pain/disability and ASDeg/Dz after ACDF, suggesting that the totality of degenerative findings may be more clinically relevant than individual phenotypes and that this tool may help prognosticate outcomes after surgery.

Painful intervertebral disc degeneration and inflammation: from laboratory evidence to clinical interventions

Low back pain (LBP), as a leading cause of disability, is a common musculoskeletal disorder that results in major social and economic burdens. Recent research has identified inflammation and related signaling pathways as important factors in the onset and progression of disc degeneration, a significant contributor to LBP. Inflammatory mediators also play an indispensable role in discogenic LBP. The suppression of LBP is a primary goal of clinical practice but has not received enough attention in disc research studies. Here, an overview of the advances in inflammation-related pain in disc degeneration is provided, with a discussion on the role of inflammation in IVD degeneration and pain induction. Puncture models, mechanical models, and spontaneous models as the main animal models to study painful disc degeneration are discussed, and the underlying signaling pathways are summarized. Furthermore, potential drug candidates, either under laboratory investigation or undergoing clinical trials, to suppress discogenic LBP by eliminating inflammation are explored. We hope to attract more research interest to address inflammation and pain in IDD and contribute to promoting more translational research.

FK506 Induces the TGF-β1/Smad 3 Pathway Independently of Calcineurin Inhibition to Prevent Intervertebral Disk Degeneration

Background

Intervertebral disk (IVD) degeneration is the most common cause of lower back pain. Inhibiting inflammation is a key strategy for delaying IVD degeneration. Tacrolimus (FK506) is a potent immunosuppressive agent that is also beneficial to chondrocytes via alleviating inflammation. However, the potential function of FK506 in IVD and the underlying mechanisms remain unknown. The current study is aim at exploring the underlying mechanism of FK506 in preventing IVD degeneration.

Methods

Cell morphology was imaged using an optical microscope. mRNA levels of nucleus pulposus (NP) matrix components were determined by qRT-PCR, and protein expression NP matrix components was assessed by western blotting. A rat caudal IVD degeneration model was established to test for FK506 in vivo.

Results

FK506 improved the morphology of NP cells and the cell function at both the mRNA and protein level. FK506 could attenuate NP degeneration induced by IL-1β. Furthermore, FK506 exerted its function via TGFβ/Smad3 activation instead of through calcineurin inhibition. Inhibition of the TGF-β pathway prevented the protective effect of FK506 on IVD degeneration. In an in vivo study, FK506 injection reversed the development of rat caudal IVD degeneration influenced by Smad3.

Conclusion

Our current study demonstrates the positive effect of FK506 on delaying the degeneration of IVD via the TGFβ/Smad3 pathway.

Small molecule antagonist of C-C chemokine receptor 1 (CCR1) reduces disc inflammation in the rabbit model

BACKGROUND CONTEXT

Targeting chemokines or chemokine receptors is a promising treatment strategy for diseases with chronic inflammation such as rheumatoid arthritis and discogenic pain. Identifying specific molecules and determining their effectiveness in animal models are the first steps in developing these treatments. Macrophage markers have been detected in the intervertebral disc tissues of patients with disc degenerative disease and discogenic pain and in different animal models. Macrophage recruitment into the disc may play a role in initiation of inflammation and if unresolved may lead to chronic inflammation and subsequent back pain.

PURPOSE

The objectives of these studies are to (1) identify chemokine receptor antagonists that can block macrophage migration induced by disc cells in vitro and (2) determine if intradiscal treatment with these antagonists can reduce disc inflammation and degeneration in vivo.

STUDY DESIGN

In vitro migration assays were used to test effectiveness of chemokine receptor antagonists to block macrophage migration induced by disc cells. The rabbit annular puncture model was used to test for anti-inflammatory and regenerative effects of chemokine receptor antagonist treatment in vivo.

METHODS

In vitro - THP-1 human monocytic cell line and freshly isolated rabbit primary splenocytes were assayed for migration using 3 µm Corning Transwell inserts with conditioned media of interleukin (IL)-1β treated human or rabbit disc cells. Inhibition of macrophage migration was evaluated using different concentrations of small molecule antagonists of C-C chemokine receptor (CCR)1 and CCR2. In vivo - New Zealand White rabbits (n=40) underwent disc puncture and intradiscal treatment with saline, CCR1 or CCR2 antagonists within the same procedure. X-ray and magnetic resonance (MR) images and serum samples were taken for disc height, MRI grade and IL-8 serum level analyses. Intervertebral discs were isolated for RNA analysis of inflammatory and disc phenotypic markers and for immunohistochemical analysis of macrophage marker, RAM11. The outcome measures were compared between the three treatment groups. These studies were funded by a research grant from AO Foundation, Switzerland (Project no S-14-86A; 120000 CHF). CCR1 and CCR2 antagonists were kindly provided by ChemoCentryx (Mountain View, CA).

RESULTS

In vitro migration assays showed that THP-1 migration induced by disc cells was blocked by CCR2 antagonist more effectively than CCR1 antagonist, while rabbit splenocyte migration was inhibited by CCR1 antagonist and not the other. In the rabbit annular puncture model, rabbit discs treated with CCR1 antagonist had significantly better MRI grades than those treated with CCR2 antagonist at 6 weeks post-treatment. Gene expression studies demonstrate that discs treated with CCR1 or CCR2 antagonists expressed less inflammatory markers than saline-treated discs at 3 weeks post-treatment. Although CCR2 antagonist treatment did not reduce inflammatory marker expression at 6 weeks, discs treated with CCR1 antagonist expressed less inflammatory markers and also a higher ratio of collagen type 2 to collagen type 1 genes indicating favorable disc matrix production. There were no significant differences between all three treatment groups in regards to disc height indexes, IL-8 serum levels or macrophage marker detection.

CONCLUSIONS

These studies have identified that small molecule antagonists against CCR2 and CCR1 were respectively effective in blocking THP-1 and rabbit splenocyte migration induced by disc cells in vitro. Further, both CCR2 and CCR1 antagonist intradiscal treatments were effective in reducing disc inflammation at an early time point of 3 weeks. Lastly, only CCR1 antagonist demonstrated anti-inflammatory effects and better MRI grades at 6 weeks.

CLINICAL SIGNIFICANCE

Our preclinical studies demonstrate that CCR1 and CCR2 antagonist delivery through intradiscal injection is sufficient to reduce disc inflammation at early time points, whereas CCR1 antagonists had longer term anti-inflammatory effects. Clinical studies have found that CCR1 antagonist was safe, tolerable and clinically active in reducing inflammation in rheumatoid arthritis patients. These studies suggest that CCR1 antagonist may be a promising biological treatment to reduce disc inflammation that translates to back pain relief.

Cervical spinal instability causes vertebral microarchitecture change and vertebral endplate lesion in rats

Background

The vertebral endplate (VEP) was damaged after spinal instability induced by cervical muscle section (CMS). Whether CMS induces bone formation and mechanical loading change in the vertebra is still obscure. This study was aimed to explore mechanical loading change and endplate damage after CMS.

Methods

Forty-eight rats were randomly divided into the CMS group and the sham group. The C6/7 segments were harvested at 4, 8, and 12 weeks after surgery. The microarchitectures of the C6 vertebra ​and the vertebral endplate lesions and intervertebral disc height of C6/7 were measured by micro-computed tomography. Micro-finite element analysis was used to evaluate biomechanical properties of the C6 vertebra. Bone remodelling of the C6 vertebra ​and the endplate ​sclerosis and intervertebral disc degeneration of C6/7 were evaluated by histological and immunohistochemical analyses.

Results

CMS significantly induced bone formation of the C6 ventral vertebra ​and increased the biomechanical properties of mainly the ventral side at 4 weeks, which was gradually rebalanced throughout the rest of the study. CMS also significantly increased protein expression of transforming growth factor-β1 (TGF-β1) and phosphorylated small mothers against decapentaplegic (pSmad)2/3 ​at 4 weeks. Moreover, tartrate-resistant acid phosphatase staining showed that osteoclast-positive cells were slightly in number decreased at 4 weeks, but were obviously increased at 8 weeks. The VEP of the ventral side was abraded earlier followed by calcification in situ later after CMS, consistent with the biomechanical enhancements observed. The degree of endplate degeneration was aggravated with time. Finally, CMS decreased intervertebral disc height and increased disc degeneration scores with time.

Conclusions

Spinal instability induced by CMS increases bone mass and biomechanical loading of the ventral side of vertebra in the early stage, which might initiate VEP damage and cause intervertebral disc degeneration.

The translational potential of this article

Our study indicates that vertebral trabecular changes may involve in intervertebral disc degeneration induced by spinal instability. This may help to elucidate the mechanisms by which disc degeneration occur.

Senotherapeutic drugs for human intervertebral disc degeneration and low back pain

Cellular senescence is a contributor to intervertebral disc (IVD) degeneration and low back pain. Here, we found that RG-7112, a potent mouse double-minute two protein inhibitor, selectively kills senescent IVD cells through apoptosis. Gene expression pathway analysis was used to compare the functional networks of genes affected by RG-7112, a pure synthetic senolytic with o-Vanillin a natural and anti-inflammatory senolytic. Both affected a functional gene network related to cell death and survival. O-Vanillin also affected networks related to cell cycle progression as well as connective tissue development and function. Both senolytics effectively decreased the senescence-associated secretory phenotype (SASP) of IVD cells. Furthermore, bioavailability and efficacy were verified ex vivo in the physiological environment of degenerating intact human discs where a single dose improved disc matrix homeostasis. Matrix improvement correlated with a reduction in senescent cells and SASP, supporting a translational potential of targeting senescent cells as a therapeutic intervention.

Pain in the lower back affects about four in five people during their lifetime. Over time, the discs that provide cushioning between the vertebrae of the spine can degenerate, which can be one of the major causes of lower back pain.

It has been shown that when the cells of these discs are exposed to different stress factors, they stop growing and become irreversibly dormant. Such ‘senescent’ cells release a range of proteins and small molecules that lead to painful inflammation and further degeneration of the discs. Moreover, it is thought that a high number of senescent cells may be linked to other degenerative diseases such as arthritis.

Current treatments can only reduce the severity of the symptoms, but they cannot prevent the degeneration from progressing. Now, Cherif et al. set out to test the effects of two different compounds on human disc cells grown in the laboratory. One of the molecules studied, RG-7112, is a synthetic drug that has been approved for safety by the US Food and Drug Administration and has been shown to remove senescent cells. The other, o-Vanillin, is a natural compound that has anti-inflammatory and anti-senescence properties.

The results showed that both compounds were able to trigger changes to that helped new, healthy cells to grow and at the same time kill senescent cells. They also reduced the production of molecules linked to inflammation and pain.

Further analyses revealed that the compounds were able to strengthen the fibrous matrix that surrounds and supports the discs. Cherif et al. hope that this could form the basis for a new family of drugs for back pain to slow the degeneration of the discs and reduce pain. This may also have benefits for other similar degenerative diseases caused by cell senescence, such as arthritis.

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.