Immuno-Modulatory Effects of Intervertebral Disc Cells

Predicting gene disease associations with knowledge graph embeddings for diseases with curtailed information

Knowledge graph embeddings (KGE) are a powerful technique used in the biomedical domain to represent biological knowledge in a low dimensional space. However, a deep understanding of these methods is still missing, and, in particular, regarding their applications to prioritize genes associated with complex diseases with reduced genetic information. In this contribution, we built a knowledge graph (KG) by integrating heterogeneous biomedical data and generated KGE by implementing state-of-the-art methods, and two novel algorithms: Dlemb and BioKG2vec. Extensive testing of the embeddings with unsupervised clustering and supervised methods showed that KGE can be successfully implemented to predict genes associated with diseases and that our novel approaches outperform most existing algorithms in both scenarios. Our findings underscore the significance of data quality, preprocessing, and integration in achieving accurate predictions. Additionally, we applied KGE to predict genes linked to Intervertebral Disc Degeneration (IDD) and illustrated that functions pertinent to the disease are enriched within the prioritized gene set.

M1 macrophage-derived exosomes promote intervertebral disc degeneration by enhancing nucleus pulposus cell senescence through LCN2/NF-κB signaling axis

Intervertebral disc degeneration (IVDD) is the primary factor contributing to low back pain (LBP). Unlike elderly patients, many young IVDD patients usually have a history of trauma or long-term abnormal stress, which may lead to local inflammatory reaction causing by immune cells, and ultimately accelerates degeneration. Research has shown the significance of M1-type macrophages in IVDD; nevertheless, the precise mechanism and the route by which it influences the function of nucleus pulposus cell (NPC) remain unknown. Utilizing a rat acupuncture IVDD model and an NPC degeneration model induced by lipopolysaccharide (LPS), we investigated the function of M1 macrophage-derived exosomes (M1-Exos) in IVDD both in vivo and in vitro in this study. We found that M1-Exos enhanced LPS-induced NPC senescence, increased the number of SA-β-gal-positive cells, blocked the cell cycle, and promoted the activation of P21 and P53. M1-Exos derived from supernatant pretreated with the exosome inhibitor GW4869 reversed this result in vivo and in vitro. RNA-seq showed that Lipocalin2 (LCN2) was enriched in M1-Exos and targeted the NF-κB pathway. The quantity of SA-β-gal-positive cells was significantly reduced with the inhibition of LCN2, and the expression of P21 and P53 in NPCs was decreased. The same results were obtained in the acupuncture-induced IVDD model. In addition, inhibition of LCN2 promotes the expression of type II collagen (Col-2) and inhibits the expression of matrix metalloproteinase 13 (MMP13), thereby restoring the equilibrium of metabolism inside the extracellular matrix (ECM) in vitro and in vivo. In addition, the NF-κB pathway is crucial for regulating M1-Exo-mediated NPC senescence. After the addition of M1-Exos to LPS-treated NPCs, p-p65 activity was significantly activated, while si-LCN2 treatment significantly inhibited p-p65 activity. Therefore, this paper demonstrates that M1 macrophage-derived exosomes have the ability to deliver LCN2, which activates the NF-κB signaling pathway, and exacerbates IVDD by accelerating NPC senescence. This may shed new light on the mechanism of IVDD and bring a fresh approach to IVDD therapy.

Sulfated Hydrogels as Primary Intervertebral Disc Cell Culture Systems

The negatively charged extracellular matrix plays a vital role in intervertebral disc tissues, providing specific cues for cell maintenance and tissue hydration. Unfortunately, suitable biomimetics for intervertebral disc regeneration are lacking. Here, sulfated alginate was investigated as a 3D culture material due to its similarity to the charged matrix of the intervertebral disc. Precursor solutions of standard alginate, or alginate with 0.1% or 0.2% degrees of sulfation, were mixed with primary human nucleus pulposus cells, cast, and cultured for 14 days. A 0.2% degree of sulfation resulted in significantly decreased cell density and viability after 7 days of culture. Furthermore, a sulfation-dependent decrease in DNA content and metabolic activity was evident after 14 days. Interestingly, no significant differences in cell density and viability were observed between surface and core regions for sulfated alginate, unlike in standard alginate, where the cell number was significantly higher in the core than in the surface region. Due to low cell numbers, phenotypic evaluation was not achieved in sulfated alginate biomaterial. Overall, standard alginate supported human NP cell growth and viability superior to sulfated alginate; however, future research on phenotypic properties is required to decipher the biological properties of sulfated alginate in intervertebral disc cells.

Research on the role and mechanism of IL-17 in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is one of the primary causes of low back pain (LBP), which seriously affects patients' quality of life. In recent years, interleukin (IL)-17 has been shown to be highly expressed in the intervertebral disc (IVD) tissues and serum of patients with IDD, and IL-17A has been shown to promote IDD through multiple pathways. We first searched databases such as PubMed, Cochrane, Embase, and Web of Science using the search terms "IL-17 or interleukin 17″ and "intervertebral discs". The search period ranged from the inception of the databases to December 2023. A total of 24 articles were selected after full-text screening. The main conclusion of the clinical studies was that IL-17A levels are significantly increased in the IVD tissues and serum of IDD patients. The results from the in vitro studies indicated that IL-17A can activate signaling pathways such as the NF-κB and MAPK pathways; promote inflammatory responses, extracellular matrix degradation, and angiogenesis; and inhibit autophagy in nucleus pulposus cells. The main finding of the in vivo experiments was that puncture of animal IVDs resulted in elevated levels of IL-17A within the IVD, thereby inducing IDD. Clinical studies, in vitro experiments, and in vivo experiments confirmed that IL-17A is closely related to IDD. Therefore, drugs that target IL-17A may be novel treatments for IDD, providing a new theoretical basis for IDD therapy.

Exploring the Impact of TLR-2 Signaling on miRNA Dysregulation in Intervertebral Disc Degeneration

Toll-like receptors (TLRs) are key mediators of inflammation in intervertebral disc (IVD) degeneration. TLR-2 activation contributes to the degenerative process by increasing the expression of extracellular matrix-degrading enzymes, pro-inflammatory cytokines, and neurotrophins. As potent post-transcriptional regulators, microRNAs can modulate intracellular mechanisms, and their dysregulation is known to contribute to numerous pathologies. This study aims to investigate the impact of TLR-2 signaling on miRNA dysregulation in the context of IVD degeneration. Small-RNA sequencing of degenerated IVD cells shows the dysregulation of ten miRNAs following TLR-2 activation by PAM2CSK4. The miR-155-5p is most significantly upregulated in degenerated and non-degenerated annulus fibrosus and nucleus pulposus cells. Sequence-based target and pathway prediction shows the involvement of miR-155-5p in inflammation- and cell fate-related pathways and TLR-2-induced miR-155-5p expression leads to the downregulation of its target c-FOS. Furthermore, changes specific to the activation of TLR-2 through fragmented fibronectin are seen in miR-484 and miR-487. Lastly, miR-100-3p, miR-320b, and miR-181a-3p expression exhibit degeneration-dependent changes. These results show that TLR-2 signaling leads to the dysregulation of miRNAs in IVD cells as well as their possible downstream effects on inflammation and degeneration. The identified miRNAs provide important opportunities as potential therapeutic targets for IVD degeneration and low back pain.

Experimental validation and comprehensive analysis of m6A methylation regulators in intervertebral disc degeneration subpopulation classification

Intervertebral disc degeneration (IVDD) is one of the most prevalent causes of chronic low back pain. The role of m6A methylation modification in disc degeneration (IVDD) remains unclear. We investigated immune-related m6A methylation regulators as IVDD biomarkers through comprehensive analysis and experimental validation of m6A methylation regulators in disc degeneration. The training dataset was downloaded from the GEO database and analysed for differentially expressed m6A methylation regulators and immunological features, the differentially regulators were subsequently validated by a rat IVDD model and RT-qPCR. Further screening of key m6A methylation regulators based on machine learning and LASSO regression analysis. Thereafter, a predictive model based on key m6A methylation regulators was constructed for training sets, which was validated by validation set. IVDD patients were then clustered based on the expression of key m6A regulators, and the expression of key m6A regulators and immune infiltrates between clusters was investigated to determine immune markers in IVDD. Finally, we investigated the potential role of the immune marker in IVDD through enrichment analysis, protein-to-protein network analysis, and molecular prediction. By analysising of the training set, we revealed significant differences in gene expression of five methylation regulators including RBM15, YTHDC1, YTHDF3, HNRNPA2B1 and ALKBH5, while finding characteristic immune infiltration of differentially expressed genes, the result was validated by PCR. We then screen the differential m6A regulators in the training set and identified RBM15 and YTHDC1 as key m6A regulators. We then used RBM15 and YTHDC1 to construct a predictive model for IVDD and successfully validated it in the training set. Next, we clustered IVDD patients based on the expression of RBM15 and YTHDC1 and explored the immune infiltration characteristics between clusters as well as the expression of RBM15 and YTHDC1 in the clusters. YTHDC1 was finally identified as an immune biomarker for IVDD. We finally found that YTHDC1 may influence the immune microenvironment of IVDD through ABL1 and TXK. In summary, our results suggest that YTHDC1 is a potential biomarker for the development of IVDD and may provide new insights for the precise prevention and treatment of IVDD.

Evodiamine ameliorates intervertebral disc degeneration through the Nrf2 and MAPK pathways

Degradation of extracellular matrix (ECM), reactive oxygen species (ROS) production, and inflammation are critical players in the pathogenesis of intervertebral disc degeneration (IDD). Evodiamine exerts functions in inhibiting inflammation and maintaining mitochondrial antioxidant functions. However, the biological functions of evodiamine and its related mechanisms in IDD progression remain unknown. The IDD-like conditions in vivo were stimulated via needle puncture. Hematoxylin and eosin staining, Safranin O/Fast Green staining and Alcian staining were performed to determine the degenerative status. The primary nucleus pulposus cells (NPCs) were isolated from Sprague-Dawley rats and then treated with tert-butyl peroxide (TBHP) to induce cellular senescence and oxidative stress. The cell viability was assessed by cell counting kit-8 assays. The mitochondria-derived ROS in NPCs was evaluated by MitoSOX staining. The mitochondrial membrane potential in NPCs was identified by JC-1 staining and flow cytometry. The expression of collagen II in NPCs was measured by immunofluorescence staining. The levels of mRNAs and proteins were measured by RT-qPCR and western blotting. The Nrf2 expression in rat nucleus pulposus tissues was measured by immunohistochemistry staining. Evodiamine alleviated TBHP-induced mitochondrial dysfunctions in NPCs. The enhancing effect of TBHP on the ECM degradation was reversed by evodiamine. The TBHP-stimulated inflammatory response was ameliorated by evodiamine. Evodiamine alleviated the IDD process in the puncture-induced rat model. Evodiamine promoted the activation of Nrf2 pathway and inactivated the MAPK pathway in NPCs. In conclusion, evodiamine ameliorates the progression of IDD by inhibiting mitochondrial dysfunctions, ECM degradation and inflammation via the Nrf2/HO-1 and MAPK pathways.

Evaluating the Efficacy of IL-6 as Predictors of Lateral Lumbar Interbody Fusion Success: Insights From Pain Scores and JOABPEQ Assessments

STUDY DESIGN

A prospective study.

OBJECTIVES

This study aims to explore the correlation between interleukin (IL)- 6 levels in intervertebral disc (IVD) tissue and clinical outcomes in patients undergoing lumbar surgery for lumbar degenerative disease (LDD).

METHODS

This prospective study analyzed 32 patients (22 men and 10 women, average age 69.6 years) who underwent lateral lumbar interbody fusion (LLIF). IL-6 gene expression in IVD tissues collected during surgery was measured and correlated with pre- and postoperative clinical outcomes, including pain intensity assessed via Numeric Rating Scales (NRS) and quality of life (QOL) evaluated through the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ).

RESULTS

IL-6 levels showed statistical correlations with postoperative intensity of low back pain (LBP) and several JOABPEQ domains. Patients with higher expression of IL-6 levels experienced more severe postoperative LBP and lower scores in lumbar function, walking ability, social life function, and mental health. The effectiveness rate of JOABPEQ scores was exceptionally high for low back pain (.548), walking ability (.677), and social functioning (.563), demonstrating the effectiveness of LLIF. The average operation time was 105.6 minutes, and the estimated blood loss was 85.6 mL.

CONCLUSIONS

The study underscores IL-6 as a potential biomarker for predicting surgical outcomes in LDD. High IL-6 levels correlate with worse postoperative LBP and lower QOL scores. Integrating molecular markers like IL-6 with patient-reported outcomes could provide a more comprehensive approach to postoperative care in spinal disorders, aiming to improve the overall QOL for LDD patients undergoing LLIF surgery.

No evidence of association between either Modic change or disc degeneration and five circulating inflammatory proteins

Introduction

Intervertebral disc degeneration and Modic change are the main spinal structural changes associated with chronic low back pain (LBP). Both conditions are thought to manifest local inflammation and if inflammatory proteins translocate to the blood circulation could be detected systemically. The work here assesses whether the presence of disc degeneration is associated with detectable blood level changes of five inflammatory markers and whether chronic LBP is associated with these changes.

Materials and Methods

Two hundred and forty TwinsUK cohort participants with both MRI disc degeneration grade and Modic change extent, and IL-6, IL-8, IL-8 TNF, and CX3CL1 protein blood concentration measurements were included in this work. Linear mixed effects models were used to test the association of blood cytokine concentration with disc degeneration score and Modic change volumetric score. Association of chronic LBP status from questionnaires with disc degeneration, Modic change, and cytokine blood concentration was also tested.

Results

No statistically significant association between disc degeneration or Modic change with cytokine blood concentration was found. Instead, regression analysis pointed strong association between cytokine blood concentration with body mass index for IL-6 and with age for IL-6 and TNF. Mild association was found between IL-8 blood concentration and body mass index. Additionally, LBP status was associated with Modic change volumetric score but not associated with any cytokine concentration.

Conclusions

We found no evidence that Modic change and disc degeneration are able to produce changes in tested blood cytokine concentration. However, age and body mass index have strong influence on cytokine concentration and both are associated with the conditions studied which may confound associations found in the literature. It is then unlikely that cytokines produced in the disc or vertebral bone marrow induce chronic LBP.

SSR1 and CKAP4 as potential biomarkers for intervertebral disc degeneration based on integrated bioinformatics analysis

Background

Intervertebral disc degeneration (IDD) is a significant cause of low back pain and poses a significant public health concern. Genetic factors play a crucial role in IDD, highlighting the need for a better understanding of the underlying mechanisms.

Aim

The aim of this study was to identify potential IDD-related biomarkers using a comprehensive bioinformatics approach and validate them in vitro.

Materials and Methods

In this study, we employed several analytical approaches to identify the key genes involved in IDD. We utilized weighted gene coexpression network analysis (WGCNA), MCODE, LASSO algorithms, and ROC curves to identify the key genes. Additionally, immune infiltrating analysis and a single-cell sequencing dataset were utilized to further explore the characteristics of the key genes. Finally, we conducted in vitro experiments on human disc tissues to validate the significance of these key genes in IDD.

Results

we obtained gene expression profiles from the GEO database (GSE23130 and GSE15227) and identified 1015 DEGs associated with IDD. Using WGCNA, we identified the blue module as significantly related to IDD. Among the DEGs, we identified 47 hub genes that overlapped with the genes in the blue module, based on criteria of |logFC| ≥ 2.0 and p.adj <0.05. Further analysis using both MCODE and LASSO algorithms enabled us to identify five key genes, of which CKAP4 and SSR1 were validated by GSE70362, demonstrating significant diagnostic value for IDD. Additionally, immune infiltrating analysis revealed that monocytes were significantly correlated with the two key genes. We also analyzed a single-cell sequencing dataset, GSE199866, which showed that both CKAP4 and SSR1 were highly expressed in fibrocartilage chondrocytes. Finally, we validated our findings in vitro by performing real time polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC) on 30 human disc samples. Our results showed that CKAP4 and SSR1 were upregulated in degenerated disc samples. Taken together, our findings suggest that CKAP4 and SSR1 have the potential to serve as disease biomarkers for IDD.

Application and development of hydrogel biomaterials for the treatment of intervertebral disc degeneration: a literature review

Low back pain caused by disc herniation and spinal stenosis imposes an enormous medical burden on society due to its high prevalence and refractory nature. This is mainly due to the long-term inflammation and degradation of the extracellular matrix in the process of intervertebral disc degeneration (IVDD), which manifests as loss of water in the nucleus pulposus (NP) and the formation of fibrous disc fissures. Biomaterial repair strategies involving hydrogels play an important role in the treatment of intervertebral disc degeneration. Excellent biocompatibility, tunable mechanical properties, easy modification, injectability, and the ability to encapsulate drugs, cells, genes, etc. make hydrogels good candidates as scaffolds and cell/drug carriers for treating NP degeneration and other aspects of IVDD. This review first briefly describes the anatomy, pathology, and current treatments of IVDD, and then introduces different types of hydrogels and addresses "smart hydrogels". Finally, we discuss the feasibility and prospects of using hydrogels to treat IVDD.

A novel biomarker of MMP-cleaved cartilage intermediate layer protein-1 is elevated in patients with rheumatoid arthritis, ankylosing spondylitis and osteoarthritis

Rheumatic joints have an altered cartilage turnover. Cartilage intermediate layer protein 1 (CILP-1) is secreted from articular chondrocytes and deposited into the cartilage extracellular matrix. We developed an immunoassay targeting a Matrix Metalloproteinase (MMP)-generated neo-epitope of CILP-1, named CILP-M. Human articular cartilage was cleaved with proteolytic enzymes and CILP-M levels were measured. We also quantified CILP-M in two studies from patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS) and osteoarthritis (OA) and explored the monitoring and prognostic potential of CILP-M in TNF-α inhibitory treatment and modified Stoke AS Spine Score (mSASSS) progression. CILP-M was generated by MMP-1, -8 and -12. In the discovery study, CILP-M was significantly higher in patients with RA, AS and OA than healthy donors (p < 0.01, p < 0.001, p < 0.05) with an area under the curve (AUC) between the diseased groups and healthy donors > 0.95 (p < 0.001). In the validation study, patients with RA and AS had significantly higher CILP-M levels than healthy controls (p < 0.001) and AUC > 0.90 (p < 0.001). Patients with AS treated with TNF- α inhibitory treatment in the validation study had significantly lower CILP-M levels after treatment (p = 0.004). CILP-M may provide useful insights into cartilage degradation processes in rheumatic diseases.

Cartilaginous endplates: A comprehensive review on a neglected structure in intervertebral disc research

The cartilaginous endplates (CEP) are key components of the intervertebral disc (IVD) necessary for sustaining the nutrition of the disc while distributing mechanical loads and preventing the disc from bulging into the adjacent vertebral body. The size, shape, and composition of the CEP are essential in maintaining its function, and degeneration of the CEP is considered a contributor to early IVD degeneration. In addition, the CEP is implicated in Modic changes, which are often associated with low back pain. This review aims to tackle the current knowledge of the CEP regarding its structure, composition, permeability, and mechanical role in a healthy disc, how they change with degeneration, and how they connect to IVD degeneration and low back pain. Additionally, the authors suggest a standardized naming convention regarding the CEP and bony endplate and suggest avoiding the term vertebral endplate. Currently, there is limited data on the CEP itself as reported data is often a combination of CEP and bony endplate, or the CEP is considered as articular cartilage. However, it is clear the CEP is a unique tissue type that differs from articular cartilage, bony endplate, and other IVD tissues. Thus, future research should investigate the CEP separately to fully understand its role in healthy and degenerated IVDs. Further, most IVD regeneration therapies in development failed to address, or even considered the CEP, despite its key role in nutrition and mechanical stability within the IVD. Thus, the CEP should be considered and potentially targeted for future sustainable treatments.

Injectable kaempferol-loaded fibrin glue regulates the metabolic balance and inhibits inflammation in intervertebral disc degeneration

To construct an injectable fibrin glue system loaded with kaempferol (FG@F) to improve the bioavailability of kaempferol and observe its efficacy in the treatment of intervertebral disc degeneration (IVDD). Kaempferol-loaded fibrin glue was first synthesized in advance. Subsequently, the materials were characterized by various experimental methods. Then, nucleus pulposus cells (NPCs) were stimulated with lipopolysaccharide (LPS) to establish a degenerative cell model, and the corresponding intervention treatment was conducted to observe the effect in vitro. Finally, the tail disc of rats was punctured to establish a model of IVDD, and the therapeutic effect of the material in vivo was observed after intervertebral disc injection. The FG@F system has good injectability, sustained release and biocompatibility. This treatment reduced the inflammatory response associated with IVDD and regulated matrix synthesis and degradation. Animal experimental results showed that the FG@F system can effectively improve needle puncture-induced IVDD in rats. The FG@F system has better efficacy than kaempferol or FG alone due to its slow release and mechanical properties. The drug delivery and biotherapy platform based on this functional system might also serve as an alternative therapy for IVDD.

Modic change is associated with increased BMI but not autoimmune diseases in TwinsUK

PURPOSE

Low back pain (LBP) is one of the largest causes of morbidity worldwide. The aetiology of LBP is complex, and many factors contribute to the onset. Bone marrow lesions within the vertebra adjacent to an intervertebral degenerate disc named Modic change (MC) have been suggested as a diagnostic subgroup of LBP. Autoimmune response has been proposed to be one of the causes that promote the development of MC. The aim of the current investigation is to assess prevalence and severity of MC and LBP in participants with an autoimmune disease diagnosis in a well-documented cohort of adult twin volunteers.

METHODS

Multivariate generalized mixed linear models (GLMM) were implemented in order to calculate the association between having an autoimmune disorder and MC prevalence, width and severe and disabling LBP. The model was corrected for family structure as well as for covariates such as age, BMI and smoking.

RESULTS

No association was found between diagnosis of autoimmune disorder and MC. Interestingly, BMI was independently associated with MC width but not to MC prevalence. These results help to shed light on the relationship between MC and autoimmunity as well as the role of BMI in the development of the lesions.

CONCLUSION

This study is the first to examine autoimmune disorders and MC prevalence in a large, population-based female cohort. The study was well powered to detect a small effect. No association was found between having a diagnosis of one or more autoimmune conditions and MC prevalence, width or LBP.

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.

Intervertebral disc degeneration and inflammatory microenvironment: expression, pathology, and therapeutic strategies

BACKGROUND

Intervertebral disc degeneration (IDD) is a leading cause of low back pain (LBP), posing a significant socioeconomic burden. Recent studies highlight the crucial role of inflammatory microenvironment in IDD progression.

METHOD

A keyword-based search was performed using the PubMed database for published articles.

RESULTS AND CONCLUSIONS

Dysregulated expression of inflammatory cytokines disrupts intervertebral disc (IVD) homeostasis, causing atrophy, fibrosis, and phenotypic changes in nucleus pulposus cells. Modulating the inflammatory microenvironment and restoring cytokine balance hold promise for IVD repair and regeneration. This comprehensive review systematically examines the expression regulation, pathological effects, therapeutic strategies, and future challenges associated with the inflammatory microenvironment and relevant cytokines in IDD. Key inflammatory cytokines, including interleukins (IL), tumor necrosis factor-alpha (TNF-α), and chemokines, exhibit significant pathological effects in IDD. Furthermore, major therapeutic modalities such as chemical antagonists, biologics, plant extracts, and gene transcription therapies are introduced to control and ameliorate the inflammatory microenvironment. These approaches provide valuable insights for identifying potential targets in future anti-inflammatory treatments for IDD.

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.