Positive feedback loop of interleukin-1beta upregulating production of inflammatory mediators in human intervertebral disc cells in vitro

Pathophysiology and emerging therapeutic strategies for cervical spondylosis: The role of pro-inflammatory mediators, kinase inhibitors, and Organogel based drug delivery systems

Cervical spondylosis is a prevalent ailment characterized by chronic wear and degenerative changes affecting the cervical spine, leading to various clinical syndromes such as axial neck pain, cervical myelopathy, and cervical radiculopathy. The pathophysiology of the development of cervical alterations is multifaceted, with alterations in the normal physiology and pathogenesis of intervertebral disc degeneration. The involvement of pro-inflammatory mediators, such as interleukin-1, tumor necrosis factor-α, interleukin-4, interleukin-6, and interleukin-10, in the pathological processes associated with intervertebral disc degeneration offers potential therapeutic targets. The review also introduces kinase inhibitors as potential treatments for cervical spondylosis. Protein kinase inhibitors, including mitogen-activated protein kinase (MAPK), Janus kinase (JAK), and spleen tyrosine kinase (SYK), are explored for their anti-inflammatory properties. The article discusses their potential in modulating inflammatory signaling cascades and presents them as attractive candidates for treating immune-mediated disorders. Inhibitors of Nuclear Factor-κB, p38 MAPK, Jun-N terminal kinase (JNK), and Extracellular signal-regulated kinase (ERK) have shown efficacy in suppressing inflammatory responses, offering potential avenues for intervention in this prevalent condition. Organogels are semi-solid materials formed by trapping an organic solvent within a three-dimensional cross-linked network. They hold considerable potential in drug delivery, especially in enhancing drug solubility, facilitating controlled release, and improving skin penetration. These properties of organogels can help treat or alleviate the symptoms of cervical spondylosis.

Explorative Study of Modulatory Effects of Notochordal Cell-Derived Extracellular Vesicles on the IL-1β-Induced Catabolic Cascade in Nucleus Pulposus Cell Pellets and Explants

Background

Cell-free regenerative strategies, such as notochordal cell (NC)-derived extracellular vesicles (EVs), are an attractive alternative in developing new therapies for intervertebral disc (IVD) degeneration. NC-EVs have been reported to elicit matrix anabolic effects on nucleus pulposus cells from degenerated IVDs cultured under basal conditions. However, the degenerative process is exacerbated by pro-inflammatory cytokines contributing to the vicious degenerative cycle. Therefore, this study explores whether NC-EVs modulate interleukin (IL)-1β-mediated pro-inflammatory responses in the degenerating disc.

Methods

This study utilized two IL-1β induced pro-catabolic culture models; a dog 3D nucleus pulposus (NP) cell pellet culture and a human patient-derived, ex vivo NP tissue culture system. Porcine NC-EVs were generated from NC-conditioned medium by differential centrifugation followed by size exclusion chromatography. Donor matched EV-depleted media were generated by overnight ultracentrifugation, whereafter the EV-depleted NCCM supernatant was subjected to size exclusion chromatography. To investigate whether observed effects were EV-associated, NC-EVs conditions were compared to EV-depleted controls in the absence and presence of IL-1β.

Results

The size and concentration of NC-EVs were quantified by nanoparticle tracking analysis, which showed minimal donor variation and confirmed depletion of EVs in the EV-depleted media. In the IL-1β-induced catabolic cascade, the NC-EVs did not elicit anabolic effects at the matrix level nor did they rescue the pro-catabolic phenotype within dog pellets. Modification of the CCL2 secretion seemed to be context dependent in the human explants: where EVs treatment stimulated CCL2 secretion but in the presence of IL-1β this effect was counteracted. Secretion of IL-6 and C-X-C motif chemokine ligand 1 was significantly decreased in NC-EV + IL-1β vs. control+IL-1β but not compared to EV-depleted human explant controls. Altogether, this data provides evidence for a protective modulatory role of NC-EVs. Considering the homeostatic function EVs exert, inherently encompassing subtle biologic modifications, the current study may have lacked sufficient power to demonstrate statistical significance in a sample set with evident donor variation.

Conclusions

NC-EVs may modulate the production of specific cytokines and chemokines in human degenerate explants when the key pro-inflammatory cytokine IL-1β is present. Implementation of the technical EV-depleted controls in further studies is essential to robustly demonstrate that these effects are EV-mediated and not associated with other secreted factors co-isolated during EV-isolation.

Contemporary clinical perspectives on chronic low back pain: The biology, mechanics, etc. underpinning clinical and radiological evaluation

Background

Pain of a chronic nature remains the foremost concern in tertiary spine clinics, yet its elusive nature and quantification challenges persist. Despite extensive research and education on low back pain (LBP), the realm of diagnostic practices lacks a unified approach. Clinically, LBP exhibits a multifaceted character, encompassing conventional assessments of severity and disability, alongside nuanced attributes like pain characterization, duration, and patient expectations. Common instigators of LBP encountered in spine surgical settings comprise degenerated intervertebral discs (IVD), herniated IVD, canal and foraminal stenosis, and spondylolisthesis. However, addressing the root cause necessitates its identification and substantiation through visualization.

Methods

This perspective reviews the diagnostic complexities of LBP. Thorough history-taking and physical examinations offer preliminary insights into the underlying source of pain, whether it arises from discogenic origins, neural compression, or sagittal imbalance. The importance of classifying chronic LBP into the underlying pathophysiology is explored. Emphasis is placed on the necessity of aligning clinical observations with imaging findings to guide personalized treatment strategies.

Results

Currently, there exists a disparity globally between evidence-based recommendations and actual applications. Recent discoveries behind the pathophysiology of pain phenotypes signify the importance of classifying LBP into its neuropathic or nociceptive origins. The pivotal role of radiological investigations in validating clinical findings for an accurate diagnosis cannot be overstated. However, radiology should not operate in isolation; the disconnect between the clinical and radiological realms ultimately benefits neither the patient nor the surgeon. Additionally, more sensitive measures of IVD prolapse and the corresponding inflammatory pathway triggered are required to provide information on the underlying pathophysiological mechanism of pain generation.

Conclusion

This perspective article underscores the imperative fusion of clinical acumen and radiological precision in the intricate landscape of LBP diagnosis. These findings advocate for a paradigm shift towards personalized medicine. By offering a compass for surgeons to navigate this complex terrain and deliver more effective, patient-centered care with targeted interventions this article aims to enhance management outcomes for chronic LBP.

Naringin safeguards vertebral endplate chondrocytes from apoptosis and NLRP3 inflammasome activation through SIRT3-mediated mitophagy

AIM

The degradation of the cartilage endplate (CEP) plays a critical role in the initiation and progression of intervertebral disc degeneration (IVDD), a disease closely associated with inflammation and oxidative stress. Naringin (NGN), a flavonoid compound derived from citrus fruits, has been shown to exhibit significant anti-inflammatory and antioxidant properties. This suggests a promising avenue for NGN's application in IVDD therapy. This study aims to elucidate the therapeutic effects and underlying mechanisms of NGN on CEP degeneration, contributing to the formulation of evidence-based treatment strategies for IVDD.

METHODS

In vivo, we developed an intervertebral disc degeneration (IVDD) model in mice by excising the bilateral facet joints and surrounding ligaments, and evaluated the effects of naringin using HE staining and Micro-CT analysis. In vitro, endplate chondrocytes were isolated and subjected to TBHP to replicate the IVDD pathological condition. The protective effects of NGN on these cells were confirmed through immunofluorescence, Western Blot, and flow cytometry.

RESULTS

In vivo, NGN effectively mitigated IVDD progression and CEP calcification in mice. In vitro, NGN enhanced mitophagy and suppressed NLRP3 inflammasome activation through the SIRT3/FOXO3a/Parkin pathway. Furthermore, NGN safeguarded chondrocytes against apoptosis and calcification triggered by oxidative stress, in addition to mitigating the degradation of the extracellular matrix. However, silencing SIRT3 negated NGN's protective influence on chondrocytes.

CONCLUSION

Our study demonstrated that NGN effectively shields chondrocytes from apoptosis and NLRP3 inflammasome activation by facilitating SIRT3-mediated mitophagy. These insights could pave the way for innovative approaches in the prevention and management of IVDD.

Assessing the causal relationship between CRP, IL-1α, IL-1β, and IL-6 levels and intervertebral disc degeneration: a two-sample Mendelian randomization study

Growing research has suggested an association between chronic inflammation and Intervertebral disc degeneration (IVDD), but whether there is a causal effect remains unknown. This study adopted two-sample Mendelian randomization (MR) approach to explore the etiological role of chronic inflammation in IVDD risk. Here, summary statistics for C-reactive protein (CRP), interleukin (IL)-1 α , IL-1 β , IL-6 expression and IVDD were obtained from genome-wide association studies (GWAS) of European ancestry. MR analyses were conducted by using inverse variance weighted (IVW), Wald Ratio, weighted median, and MR-Egger method. Sensitivity analyses were conducted to assess the robustness of the results. The MR analyses suggested a lack of causal association of CRP, IL-6 , and IL-1 α levels on IVDD (CRP-IVDD: odds ratio [OR] = 0.97, 95% confidence interval [CI] 0.86-1.09, P = 0.583; IL-6-IVDD: OR = 1.04, 95% CI 0.86-1.27, P = 0.679; IL-1 α -IVDD: OR = 1.09, 95%CI 1.00-1.18, P = 0.058). However, there was a sign of a connection between genetically elevated IL-1 β levels and a decreased IVDD incidence (OR = 0.87, 95%CI 0.77-0.99, P = 0.03). Our findings suggest a connection between IL-1 β levels and the risk of IVDD. However, due to the support of only one SNP, heterogeneity and pleiotropy tests cannot be performed, the specific underlying mechanisms warrant further investigation.

Enzymatic TET-1 inhibition highlights different epigenetic behaviours of IL-1β and TNFα in tumour progression of OS cell lines

Osteosarcoma (OS) is the most frequent primary malignant bone tumour, whose heterogeneity represents a major challenge for common antitumour therapies. Inflammatory cytokines are known to be necessary for OS progression. Therefore, to optimise therapy, it is important to discover reliable biomarkers by identifying the mechanism generating OS and investigating the inflammatory pathways that support the undifferentiated state. In this work, we highlight the differences of epigenetic activities of IL-1β and TNFα, and the susceptibility of TET-1 enzymatic inhibition, in tumour progression of three different OS cell lines. Investigating DNA methylation of IL-6 promoter and determining its expression, we found that TET enzymatic inhibition influences proliferation induced by inflammatory cytokines in OS cell lines. Moreover, Bobcat 339 treatment blocks IL-1β epigenetic action on IL-6 promoter, while only partially those of TNFα as well as inhibits IL-1β-dependent epithelial-mesenchymal transition (EMT) process, but only partially those of TNFα. In conclusion, this work highlights that IL-1β and TNFα have different effects on DNA demethylation in OS cell lines, making DNA methylation a potential biomarker of disease. Specifically, in IL-1β treatment, TET-1 inhibition completely blocks tumour progression, while in TNFα actions, it is only partially effective. Given that these two inflammatory pathways can be therapeutic targets for treating these tumours, knowledge of their distinct epigenetic behaviours can be useful for developing precise and specific therapeutic strategies for this disease.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Macrophage migration inhibitory factor (MIF) promotes intervertebral disc degeneration through the NF-κB pathway, and the MIF inhibitor CPSI-1306 alleviates intervertebral disc degeneration in a mouse model

Lumbar intervertebral disc degeneration(IDD) is a prevalent inflammatory disease caused by many proinflammatory factors, such as TNF and IL-1β. Migration inhibitory factor (MIF) is an upstream inflammatory factor widely expressed in vivo that is associated with a variety of inflammatory diseases or malignant tumors and has potential therapeutic value in many diseases. We explored the role of MIF in intervertebral disc degeneration by regulating the content of exogenous MIF or the expression of MIF in cells. Upon inducing degeneration of nucleus pulposus (NP) cells with IL-1β, we found that the increase in intracellular and exogenous MIF promoted the catabolism induced by proinflammatory factors in NP cells, while silencing of the MIF gene alleviated the degeneration to some extent. In a mouse model, the intervertebral disc degeneration of MIF-KO mice was significantly less than that of wild-type mice. To explore the treatment of intervertebral disc degeneration, we selected the small-molecular MIF inhibitor CPSI-1306. CPSI-1306 had a therapeutic effect on intervertebral disc degeneration in the mouse model. In summary, we believe that MIF plays an important role in intervertebral disc degeneration and is a potential therapeutic target for the treatment of intervertebral disc degeneration.

Tension-activated nanofiber patches delivering an anti-inflammatory drug improve repair in a goat intervertebral disc herniation model

Conventional microdiscectomy treatment for intervertebral disc herniation alleviates pain but does not repair the annulus fibrosus, resulting in a high incidence of recurrent herniation and persistent dysfunction. The lack of repair and the acute inflammation that arise after injury can further compromise the disc and result in disc-wide degeneration in the long term. To address this clinical need, we developed tension-activated repair patches (TARPs) for annulus fibrosus repair and local delivery of the anti-inflammatory factor anakinra (a recombinant interleukin-1 receptor antagonist). TARPs transmit physiologic strain to mechanically activated microcapsules embedded within the patch, which release encapsulated bioactive molecules in direct response to spinal loading. Mechanically activated microcapsules carrying anakinra were loaded into TARPs, and the effects of TARP-mediated annular repair and anakinra delivery were evaluated in a goat model of annular injury in the cervical spine. TARPs integrated with native tissue and provided structural reinforcement at the injury site that prevented aberrant disc-wide remodeling resulting from detensioning of the annular fibrosus. The delivery of anakinra by TARP implantation increased matrix deposition and retention at the injury site and improved maintenance of disc extracellular matrix. Anakinra delivery additionally attenuated the inflammatory response associated with TARP implantation, decreasing osteolysis in adjacent vertebrae and preserving disc cellularity and matrix organization throughout the annulus fibrosus. These results demonstrate the therapeutic potential of TARPs for the treatment of intervertebral disc herniation.

IL-1β-mediated inflammatory responses in intervertebral disc degeneration: Mechanisms, signaling pathways, and therapeutic potential

Intervertebral disc degeneration (IDD) has been widely recognized as the primary cause of low back pain and is one of the major chronic diseases imposing a severe socioeconomic burden worldwide. IDD is a degenerative process characterized by inflammatory responses, and its underlying pathological mechanisms remain complex. Genetic, developmental, biochemical, and biomechanical factors contribute to the development of IDD. There is a pressing need for an effective non-surgical treatment, mainly due to the lack of comprehensive understanding of the specific mechanisms involved and the effective therapeutic targets for IDD. Recently, interleukin (IL)-1β has been recognized as an essential inflammatory factor and a key mediator of the inflammatory process in IDD. Current studies have found that IL-1β is mainly involved in IDD by affecting the metabolism of the extracellular matrix and regulating cell death (RCD), such as apoptosis, pyroptosis, and ferroptosis (a new form of RCD). Although analysis of clinical samples from different laboratories confirmed how IL-1β is induced in IDD, its specific signal transduction pathway, and the inflammatory role mediated in IDD remains unclear. This review describes the molecules and mechanisms involved in IL-1β-mediated inflammatory responses, and their roles in resolving the inflammatory process in IDD. Understanding the signaling pathways involved in IL-1β may lead to a new class of targets that promote remission for IDD patients. This review aims to provide a framework for the treatment of IDD by analyzing the signaling mechanism and function related to IL-1β, especially in terms of inflammation, matrix metabolism, and cell death regulation.

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.

Anti-Inflammatory Effects of Adiponectin Receptor Agonist AdipoRon against Intervertebral Disc Degeneration

Adiponectin, a hormone secreted by adipocytes, has anti-inflammatory effects and is involved in various physiological and pathological processes such as obesity, inflammatory diseases, and cartilage diseases. However, the function of adiponectin in intervertebral disc (IVD) degeneration is not well understood. This study aimed to elucidate the effects of AdipoRon, an agonist of adiponectin receptor, on human IVD nucleus pulposus (NP) cells, using a three-dimensional in vitro culturing system. This study also aimed to elucidate the effects of AdipoRon on rat tail IVD tissues using an in vivo puncture-induced IVD degeneration model. Analysis using quantitative polymerase chain reaction demonstrated the downregulation of gene expression of proinflammatory and catabolic factors by interleukin (IL)-1β (10 ng/mL) in human IVD NP cells treated with AdipoRon (2 μM). Furthermore, western blotting showed AdipoRon-induced suppression of p65 phosphorylation (p < 0.01) under IL-1β stimulation in the adenosine monophosphate-activated protein kinase (AMPK) pathway. Intradiscal administration of AdipoRon was effective in alleviating the radiologic height loss induced by annular puncture of rat tail IVD, histomorphological degeneration, production of extracellular matrix catabolic factors, and expression of proinflammatory cytokines. Therefore, AdipoRon could be a new therapeutic candidate for alleviating the early stage of IVD degeneration.

Epigenetic modifications of inflammation in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a common cause of joint-related chronic disability in elderly individuals worldwide. It seriously impacts the quality of life and inflicts a substantial social and economic burden. The pathological mechanisms underlying IDD have not been fully revealed, leading to less satisfactory clinical treatment outcomes. More studies are urgently needed to reveal its precise pathological mechanisms. Numerous studies have revealed that inflammation is closely related to various pathological processes of IDD, including the continuous loss of extracellular matrix, cell apoptosis, and senescence, indicating the important role of inflammation in the pathological mechanism of IDD. Epigenetic modifications affect the functions and characteristics of genes mainly through DNA methylation, histone modification, non-coding RNA regulation, and other mechanisms, thus having a major effect on the survival state of the body. Recently, the role of epigenetic modifications in inflammation during IDD has been attracting research interest. In this review, we summarize the roles of different types of epigenetic modifications in inflammation during IDD in recent years, to improve our understanding of the etiology of IDD and to transform basic research strategy into a clinically effective treatment for joint-related chronic disability in elderly individuals.

The role of mitochondrial fission in intervertebral disc degeneration

Low back pain (LBP) is an extremely common disorder and is a major cause of disability globally. Intervertebral disc degeneration (IVDD) is the main contributor to LBP. Nevertheless, the specific mechanisms underlying the pathogenesis of IVDD remain unclear. Mitochondria are highly dynamic organelles that continuously undergo fusion and fission, known as mitochondrial dynamics. Accumulating evidence has revealed that aberrantly activated mitochondrial fission leads to mitochondrial fragmentation and dysfunction, which are involved in the development and progression of IVDD. To date, research into mitochondrial dynamics in IVDD is at an early stage. The present narrative review aims to summarize the most recent findings about the role of mitochondrial fission in the pathogenesis of IVDD.

Role of Pyroptosis in Intervertebral Disc Degeneration and Its Therapeutic Implications

Intervertebral disc degeneration (IDD), a progressive and multifactorial pathological process, is predominantly associated with low back pain and permanent disability. Pyroptosis is a type of lytic programmed cell death triggered by the activation of inflammasomes and caspases. Unlike apoptosis, pyroptosis is characterized by the rupture of the plasma membrane and the release of inflammatory mediators, accelerating the destruction of the extracellular matrix (ECM). Recent studies have shown that pyrin domain-containing 3 (NLRP3) inflammasome-mediated pyroptosis in nucleus pulposus (NP) cells is activated in the progression of IDD. Furthermore, targeting pyroptosis in IDD demonstrates the excellent capacity of ECM remodeling and its anti-inflammatory properties, suggesting that pyroptosis is involved in the IDD process. In this review, we briefly summarize the molecular mechanism of pyroptosis and the pathogenesis of IDD. We also focus on the role of pyroptosis in the pathological progress of IDD and its targeted therapeutic application.

Innovative immune mechanisms and antioxidative therapies of intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is the basic pathological process of many degenerative diseases of the spine, characterized by series of symptoms, among which low back pain (LBP) is the most common symptom that patients suffer a lot, which not only makes patients and individual families bear a huge pain and psychological burden, but also consumes a lot of medical resources. IDD is usually thought to be relevant with various factors such as genetic predisposition, trauma and aging, and IDD progression is tightly relevant with structural and functional alterations. IDD processes are caused by series of pathological processes, including oxidative stress, matrix decomposition, inflammatory reaction, apoptosis, abnormal proliferation, cell senescence, autophagy as well as sepsis process, among which the oxidative stress and inflammatory response are considered as key link in IDD. The production and clearance of ROS are tightly connected with oxidative stress, which would further simulate various signaling pathways. The phenotype of disc cells could change from matrix anabolism-to matrix catabolism- and proinflammatory-phenotype during IDD. Recent decades, with the relevant reports about oxidative stress and inflammatory response in IDD increasing gradually, the mechanisms researches have attracted much more attention. Consequently, this study focused on the indispensable roles of the oxidative stress and inflammatory response (especially macrophages and cytokines) to illustrate the origin, development, and deterioration of IDD, aiming to provide novel insights in the molecular mechanisms as well as significant clinical values for IDD.

Characteristics and mechanisms of resorption in lumbar disc herniation

Lumbar disc herniation (LDH) can be spontaneously absorbed without surgical treatment. However, the pathogenesis and physiological indications for predicting protrusion reabsorption are still unclear, which prevents clinicians from preferentially choosing conservative treatment options for LDH patients with reabsorption effects. The purpose of this review was to summarize previous reports on LDH reabsorption and to discuss the clinical and imaging features that favor natural absorption. We highlighted the biological mechanisms involved in the phenomenon of LDH reabsorption, including macrophage infiltration, inflammatory responses, matrix remodeling, and neovascularization. In addition, we summarized and discussed potential clinical treatments for promoting reabsorption. Current evidence suggests that macrophage regulation of inflammatory mediators, matrix metalloproteinases, and specific cytokines in intervertebral disc is essential for the spontaneous reabsorption of LDH.

Genetic variants of interleukin 1B and 6 are associated with clinical outcome of surgically treated lumbar degenerative disc disease

BACKGROUND

Successfully surgically treating degenerative disc diseases can be challenging to the spine surgeons, the long-term outcome relies on both the physical and mental status of the patient before and after treatment. Numerous studies underlined the role of inflammatory cytokines - like interleukin 1B and 6 - in the development of chronic diseases such as failed back surgery syndrome (FBSS) and major depressive disorder (MDD) which alter the outcome after spinal surgery. Our aim was to evaluate the associations of IL6 and IL1B gene polymorphisms with the long-term outcome of degenerative lumbar spine surgeries.

METHODS

An international genetical database (GENODISC) was combined with our institute's clinical database to create a large pool with long term follow up data. Altogether 431 patient's data were analysed. Patient reported outcome measures and surgical outcome was investigated in association with IL1B and IL6 SNPs with the help of 'SNPassoc' R genome wide association package.

RESULTS

Interleukin 1B variants analysis confirmed association with improvement of pain after surgery on individual SNP level and on haplotype level, moreover relationship with patient reported outcome and preoperative level of depression was found on individual SNP level. IL6 variants were associated with preoperative depression, somatization and with subsequent surgery.

CONCLUSION

Understanding the complexity of spinal surgery patients' long-term well-being is crucial in effectively treating chronic debilitating somatic diseases and the associated mental illnesses. Further studies should investigate more comprehensively the linkage of chronic physical and mental illnesses focusing on their simultaneous treatment.

Targeting Oxidative Stress and Inflammation in Intervertebral Disc Degeneration: Therapeutic Perspectives of Phytochemicals

Low back pain is a major cause of disability worldwide that declines the quality of life; it poses a substantial economic burden for the patient and society. Intervertebral disc (IVD) degeneration (IDD) is the main cause of low back pain, and it is also the pathological basis of several spinal degenerative diseases, such as intervertebral disc herniation and spinal stenosis. The current clinical drug treatment of IDD focuses on the symptoms and not their pathogenesis, which results in frequent recurrence and gradual aggravation. Moreover, the side effects associated with the long-term use of these drugs further limit their use. The pathological mechanism of IDD is complex, and oxidative stress and inflammation play an important role in promoting IDD. They induce the destruction of the extracellular matrix in IVD and reduce the number of living cells and functional cells, thereby destroying the function of IVD and promoting the occurrence and development of IDD. Phytochemicals from fruits, vegetables, grains, and other herbs play a protective role in the treatment of IDD as they have anti-inflammatory and antioxidant properties. This article reviews the protective effects of phytochemicals on IDD and their regulatory effects on different molecular pathways related to the pathogenesis of IDD. Moreover, the therapeutic limitations and future prospects of IDD treatment have also been reviewed. Phytochemicals are promising candidates for further development and research on IDD treatment.

Smad7 Is Highly Expressed in Human Degenerative Discs and Participates in IL-1β-Induced Apoptosis of Rat AF Cells via the Mitochondria Pathway

Background. Abnormal Smad7 expression can lead to apoptosis in different cell types. Previously, we found high expression of Smad7 in rat degenerative discs. However, the exact role of Smad7 in the apoptosis of disc cells and the possible underlying mechanism remain unclear. Methods. Degenerative and nondegenerative human lumbar intervertebral discs were collected from patients during operation. The expressions of SMAD7 mRNA and protein in the different components of these discs were measured with real-time PCR and Western blotting, respectively. Annulus fibrosus (AF) cells were isolated and cultivated from the discs of young healthy rats. Smad7 in the AF cells was overexpressed with adenovirus and knocked down with siRNA. IL-1β was used to induce apoptosis in the AF cells. Loss-and-gain cell function experiments were performed to show the effect of Smad7 on the apoptosis of AF cells. The function recovery experiments were performed to verify whether Smad7 regulates the apoptosis of AF cells through the mitochondria-mediated pathway. Results. Both the mRNA and protein expressions of Smad7 were significantly higher in the different components of human degenerative discs than in those of the nondegenerative discs. IL-1β stimulated apoptosis while upregulating the Smad7 expression in the AF cells in vitro. Overexpression of Smad7 in AF cells exaggerated the IL-1β-induced apoptosis in the cells while knockdown of Smad7 expression suppressed this apoptosis. With the exaggerated apoptosis in the AF cells with Smad7 overexpression, both active cleaved caspase-3 and cleaved caspase-9, the ratio of Bax/Bcl-2, and Cyt-c increased significantly. However, the inhibitor of caspase-9, Z-LEHD-FMK, significantly diminished the apoptosis in these cells. Conclusion. Smad7 is highly expressed in human degenerative discs and participates in IL-1β-induced apoptosis of rat AF cells via the mitochondria pathway. Smad7 may be a potential target for the prevention and treatment of degenerative disc disease.

Pyroptosis and Sarcopenia: Frontier Perspective of Disease Mechanism

With global ageing, sarcopenia, as an age-related disease, has brought a heavy burden to individuals and society. Increasing attention has been given to further exploring the morbidity mechanism and intervention measures for sarcopenia. Pyroptosis, also known as cellular inflammatory necrosis, is a kind of regulated cell death that plays a role in the ageing progress at the cellular level. It is closely related to age-related diseases such as cardiovascular diseases, Alzheimer’s disease, osteoarthritis, and sarcopenia. In the process of ageing, aggravated oxidative stress and poor skeletal muscle perfusion in ageing muscle tissues can activate the nod-like receptor (NLRP) family to trigger pyroptosis. Chronic inflammation is a representative characteristic of ageing. The levels of inflammatory factors such as TNF-α may activate the signaling pathways of pyroptosis by the NF-κB-GSDMD axis, which remains to be further studied. Autophagy is a protective mechanism in maintaining the integrity of intracellular organelles and the survival of cells in adverse conditions. The autophagy of skeletal muscle cells can inhibit the activation of the pyroptosis pathway to some extent. A profound understanding of the mechanism of pyroptosis in sarcopenia may help to identify new therapeutic targets in the future. This review article focuses on the role of pyroptosis in the development and progression of sarcopenia.

IL-1β Promotes Expansion of IL-33+ Lung Epithelial Stem Cells Following RSV Infection During Infancy

Respiratory syncytial virus (RSV)-induced immunopathogenesis and disease severity in neonatal mice and human infants have been related to elevated pulmonary IL-33. Thus, targeting IL-33 has been suggested as a potential therapy for respiratory viral infections. Yet, the regulatory mechanisms on IL-33 during early life remain unclear. Here, using a neonatal mouse model of RSV, we demonstrate that IL-1β positively regulates but is not required for RSV-induced expression of pulmonary IL-33 in neonatal mice early after the initial infection. Exogenous IL-1β upregulates RSV-induced IL-33 expression by promoting the proliferation of IL-33pos lung epithelial stem/progenitor cells (EpiSPC). These cells are exclusively detected in RSV-infected neonatal rather than adult mice, partially explaining the IL-1β-independent IL-33 expression in RSV-infected adult mice. Furthermore, IL-1β aggravates IL-33 mediated Th2 biased immunopathogenesis upon reinfection. Collectively, our study demonstrates that IL-1β exacerbates IL-33 mediated RSV immunopathogenesis by promoting the proliferation of IL-33pos EpiSPC in early life.

miR-142-3p and HMGB1 Are Negatively Regulated in Proliferation, Apoptosis, Migration, and Autophagy of Cartilage Endplate Cells

BACKGROUND

Cartilage endplate (CEP) degeneration plays a vital role in the pathological process of intervertebral disc degeneration. It has been previously reported that microRNAs may participate in the occurrence and development of intervertebral disc degeneration through regulating its target genes directly. The regulatory roles of miR-142-3p/HMGB1 in some orthopedic diseases have been determined successively, but there was no report about the degeneration of CEP. Therefore, we aimed to determine the regulation of miR-142-3p/HMGB1 or potential molecular mechanisms on proliferation, apoptosis, migration, and autophagy of CEP cells.

METHODS

The target gene of miR-142-3p was determined by double luciferase assay. We selected ATDC5 cell lines. CCK-8 method was used to detect cell proliferation. Real-time fluorescence quantitative polymerase chain reaction was used to determine gene expression levels, and western blot analysis was used to determine protein expression levels. We chose flow cytometry to measure cell apoptosis and cell cycle.

RESULTS

The result of luciferase detection showed that the target gene of miR-142-3p in CEP cells was HMGB1. Knockdown of the miR-142-3p inhibited the expression level of HMGB1, the proliferation and migration of CEP cells, but it promoted apoptosis of CEP cells. In addition, the detection results of the proteins related to apoptosis or autophagy showed that knockdown of miR-142-3p promoted apoptosis and autophagy.

CONCLUSION

The negative regulation of miR-142-3p/HMGB1 can affect the proliferation, apoptosis, migration, and autophagy of CEP cells. Our results provide a new idea for the targeted treatment of CEP degeneration by inhibiting the expression of HMGB1.

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.

IL-1β promotes disc degeneration and inflammation through direct injection of intervertebral disc in a rat lumbar disc herniation model

BACKGROUND CONTEXT

Lumbar intervertebral disc herniation (LDH) is a common disease that causes low back pain, radiating leg pain, and sensory impairment. Preclinical studies rely heavily upon standardized animal models of human diseases to predict clinical treatment efficacy and to identify and investigate potential adverse events in human subjects. The current method for making the LDH model involves harvesting the nucleus pulposus (NP) from autologous coccygeal discs and applying to the lumbar nerve roots just proximal to the corresponding dorsal root ganglion. However, this surgical method generates a model that exhibits very different characteristics of disc herniation than that observed in human.

PURPOSE

To produce a rat LDH model that better resembles disc herniation in humans and a standardized and uniform LDH model using Interleukin-1 beta (IL-1β).

STUDY DESIGN

Experimental rat LDH model.

METHODS

We exposed the L5-6 disc dorsolaterally on the right side through hemi-laminectomy without nerve compression. Herniation was initiated by puncturing the exposed disc with a 30-gauge needle at a depth of 4 mm. Interleukin-1 beta (IL-1β) was injected simultaneously to heighten the pathological processes of disc degeneration, including inflammatory responses, matrix destruction, and herniation of the NP. We performed histological staining to assess morphological changes, immunohistochemistry to analyze inflammation- and pain-related expression within and around the puncture site of the L5-6 disc, and real-time polymerase chain reaction to examine expression of markers for degenerative processes. In addition, we performed locomotor tests on the rats.

RESULTS

We found that the IL-1β groups showed that the border between the annulus fibrosis and nucleus pulposus was severely interrupted compared to that of the control (puncture only) group. And, the injection of IL-1β leads to accelerated disc degeneration and inflammation in a more consistent manner in LDH model. Functional deficit was consistently induced by puncturing and injection of IL-1β in the exposed disc.

CONCLUSIONS

The method proposed here can be used as an index to control the severity of disc degeneration and inflammation through the injected IL-1β concentration concurrent with surgically induced herniation.

CLINICAL SIGNIFICANCE

Our proposed model may facilitate research in drug development to evaluate the efficacy of potential therapeutic agents for disc herniation and neuropathic pain and may also be used for nonclinical studies to more accurately assess the effectiveness of various treatment strategies according to the severity of disc degeneration.

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.

Proinflammatory intervertebral disc cell and organ culture models induced by tumor necrosis factor alpha

Inflammation plays an important role in the pathogenesis of intervertebral disc (IVD) degeneration. The proinflammatory cytokine tumor necrosis factor alpha (TNF-α) has shown markedly higher expression in degenerated human disc tissue compared with healthy controls. Anti-inflammatory treatment targeting TNF-α has shown to alleviate discogenic pain in patients with low back pain. Therefore, in vitro and ex vivo inflammatory models utilizing TNF-α provide relevant experimental conditions for drug development in disc degeneration research. The current method article addressed several specific questions related to the model establishment. (a) The effects of bovine and human recombinant TNF-α on bovine nucleus pulposus (NP) cells were compared. (b) The required dose for an inflammatory IVD organ culture model with intradiscal TNF-α injection was studied. (c) The effect of TNF-α blocking at different stages of inflammation was evaluated. Outcomes revealed that bovine and human recombinant TNF-α induced equivalent inflammatory effects in bovine NP cells. A bovine whole IVD inflammatory model was established by intradiscal injection of 100 ng TNF-α/ cm3 disc volume, as indicated by increased nitric oxide, glycosaminoglycan, interleukin 6 (IL-6), and interleukin 8 (IL-8) release in culture media, and upregulation of MMP3, ADAMTS4, IL-8, IL-6, and cyclooxygenase (COX)-2 expression in NP tissue. However, results in human NP cells showed that the time point of anti-inflammatory treatment was crucial to achieve significant effects. Furthermore, anticatabolic therapy in conjunction with TNF-α inhibition would be required to slow down the pathologic cascade of disc degeneration.

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.

Transcription Analysis of the Chemerin Impact on Gene Expression Profile in the Luteal Cells of Gilts

Chemerin is a recently discovered adipokine that participates in the regulation of many physiological and disorder-related processes in mammals, including metabolism, inflammatory reactions, obesity, and reproduction. We investigated how chemerin affects the transcriptome profile of porcine luteal cells. The luteal cells were acquired from mature gilts. After the in vitro culturing with and without chemerin, the total RNAs were isolated and high-throughput sequencing was performed. Obtained datasets were processed using bioinformatic tools. The study revealed 509 differentially expressed genes under the chemerin influence. Their products take part in many processes, important for the functions of the corpus luteum, such as steroids and prostaglandins synthesis, NF-κB and JAK/STAT signal transducing pathways, and apoptosis. The expression of the CASP3, HSD3B7, IL1B, and PTGS2 genes, due to their important role in the physiology of the corpus luteum, was validated using the quantitative real-time polymerase chain reaction (qPCR) method. The qPCR confirmed the changes of gene expression. Chemerin in physiological concentrations significantly affects the expression of many genes in luteal cells of pigs, which is likely to result in modification of physiological processes related to reproduction.

Sirtuins and intervertebral disc degeneration: Roles in inflammation, oxidative stress, and mitochondrial function

Intervertebral disc degeneration (IDD) is one of the main causes of low back pain, which seriously reduces the quality of life of patients and places a heavy economic burden on their families. Cellular senescence is considered to be an important factor leading to IDD, and inflammatory response, oxidative stress, and mitochondrial dysfunction are closely related to intervertebral disc (IVD) senescence. Therefore, inhibition of the inflammatory response and oxidative stress, along with maintaining mitochondrial function, may be useful in treating IDD. The sirtuins are a family of evolutionarily conserved nicotinamide adenine dinucleotide (NAD⁺)-dependent histone deacetylases, which are the major molecules mediating life extension or delay of aging-related diseases. The sirtuin protein family consist of seven members (SIRT1 - 7), which are mainly involved in various aging-related diseases by regulating inflammation, oxidative stress, and mitochondrial function. Among them, SIRT1, SIRT2, SIRT3, and SIRT6 are closely related to IDD. In addition, some activators of sirtuin proteins, such as resveratrol, melatonin, magnolol, 1,4-dihydropyridine (DHP), SRT1720, and nicotinamide mononucleotide (NMN), have been evaluated in preclinical studies for their effects in preventing IDD. This review described the biological functions of sirtuins and the important roles of SIRT1, SIRT2, SIRT3, and SIRT6 in IDD by regulating oxidative stress, inflammatory response, and mitochondrial function. In addition, we introduce the status of some sirtuin activators in IDD preclinical studies. This review will provide a background for further clarification of the molecular mechanism underlying IDD and the development of potential therapeutic drugs.

Actions of Prostaglandins on Human Nucleus Pulposus Metabolism Inferred by Cyclooxygenase 2 Inhibition of Cytokine Activated Cells

OBJECTIVE

Low back pain is frequently treated with nonsteroidal anti-inflammatory drugs (NSAIDs), but little is known about intervertebral disc metabolism of the prostaglandins that are diminished by these drugs. Hence, this study aimed at delineating prostaglandin actions in cytokine activated disc cells by comparing the response of nucleus pulposus (NP) cells to the pro-inflammatory cytokine interleukin (IL)-1β with and without cyclooxygenase 2 (COX-2) inhibition.

METHODS

NP cells cultured in alginate beads were activated with IL-1β ± the COX-2 inhibitor Sc-58125. Media harvested from cultured cells were analyzed for prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2α), IL-6, and matrix metalloproteinase (MMP)-3 by enzymelinked immunosorbent assay and nitric oxide by Griess Reaction. Gene expression along with proteoglycan, collagen, and total protein synthesis were also measured.

RESULTS

IL-1β increased culture media PGE2 and PGF2α, but decreased proteoglycan and collagen syntheses as well as mRNA expression of the matrix genes aggrecan, versican, collagen I, and collagen II. COX-2 inhibition partially rescued proteoglycan and collagen syntheses and collagen I mRNA, but decreased collagen II mRNA IL-1β activated NP cells. COX-2 inhibition initially enhanced and subsequently reduced IL-1β induced inducible nitric oxide synthase, without altering medium nitrite. IL-1β induction of MMP-3 mRNA was increased by COX-2 inhibition at 24 and 48 hours.

CONCLUSION

COX-2 inhibition alters the response of NP cells to IL-1β, suggesting IL-1β action on disc cells is mediated at least in part through COX-2 and its prostaglandins. COX-2 inhibition produces minimal effects on several key catabolic mediators, with the exception of MMP-3. Blocking COX-2 might be beneficial for maintaining disc matrix since it provides an overall rescue of IL-1 induced loss of matrix protein synthesis.

A single-pulsed electromagnetic field enhances collagen synthesis in tendon cells

Tendinopathy is a progressive pathology of tendon that is characteristic of imbalance between matrix synthesis and degeneration and is often caused by failure to adapt to mechanical loading. Non-steroidal anti-inflammatory medications (NSAIDS) are used as a conventional treatment to alleviate pain and swelling in the short term, but the ideal treatment for tendinopathy remains unclear. Here, we show a single pulsed electromagnetic field (SPEMF, 0.2 Hz) that up-regulated tenogenic gene expression (Col1a1, Col3a1, Scx, Dcn) and down-regulated inflammatory gene expression (Mmp1) in vitro. After five days of SPEMF stimulation (3 min/day), the collagen type I and total collagen synthesis protein levels were significantly increased. Under pro-inflammatory cytokine (IL-1β) irritation, the decreased expression of Col1a1/Col3a1 was up-regulated by SPEMF treatment, and the increased expression of Mmp1 was also reversed. From the above, it can be inferred that SPEMF that enhances matrix synthesis and reduces matrix degeneration may counteract the imbalance in tendinopathy. SPEMF application may be developed as a potential future strategy for therapeutic intervention in tendon disorders.

Alzheimer's Disease and Its Potential Alternative Therapeutics

Alzheimer’s Disease (AD) is a chronic neurodegenerative disease that affects over 5 million individuals in the United States alone. Currently, there are only two kinds of pharmacological interventions available for symptomatic relief of AD; Acetyl Cholinesterase Inhibitors (AChEI) and N-methyl-D-aspartic Acid (NMDA) receptor antagonists and these drugs do not slow down or stop the progression of the disease. Several molecular targets have been implicated in the pathophysiology of AD, such as the tau (τ) protein, Amyloid-beta (Aβ), the Amyloid Precursor Protein (APP) and more and several responses have also been observed in the advancement of the disease, such as reduced neurogenesis, neuroinflammation, oxidative stress and iron overload. In this review, we discuss general features of AD and several small molecules across different experimental AD drug classes that have been studied for their effects in the context of the molecular targets and responses associated with the AD progression. These drugs include: Paroxetine, Desferrioxamine (DFO), N-acetylcysteine (NAC), Posiphen/-(−)Phenserine, JTR-009, Carvedilol, LY450139, Intravenous immunoglobulin G 10%, Indomethacin and Lithium Carbonate (Li₂CO₃).

The Evolving Case Supporting Individualised Physiotherapy for Low Back Pain

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

Berberine prevents human nucleus pulposus cells from IL‑1β‑induced extracellular matrix degradation and apoptosis by inhibiting the NF‑κB pathway

Intervertebral disc degeneration (IDD) is widely considered to be one of the main causes of lower back pain, which is a chronic progressive disease closely related to inflammation, nucleus pulposus (NP) cell apoptosis and extracellular matrix (ECM) degradation. Berberine (BBR) is an alkaloid compound with an anti-inflammatory effect and has been reported to exert therapeutic action in several inflammatory diseases, including osteoarthritis. Therefore, it was hypothesized that BBR may have a therapeutic effect on IDD through inhibition of the inflammatory response. The aim of the present study was to evaluate the influence of BBR on IDD in interleukin (IL)-1β-treated human NP cells in vitro. The results showed that BBR attenuated the upregulation of ECM-catabolic factors [matrix metalloproteinase (MMP)-3, MMP-13, a disintegrin and metalloproteinase with thrombospondin motif (ADAMTS)-4 and ADAMTS-5], and the downregulation of ECM-anabolic factors (type II collagen and aggrecan) following stimulation of the human NP cells with IL-1β. Treatment with BBR also protected human NP cells from IL-1β-induced apoptosis, as determined by western blotting and flow cytometry. Mechanistically, the IL-1β-stimulated degradation of IκBα, and the phosphorylation and translocation of nuclear factor (NF)-κB p65 were found to be attenuated by BBR, indicating that NF-κB pathway activation was suppressed by BBR in the IL-1β-treated human NP cells. The results of the experiments revealed a therapeutic potential of BBR for the prevention or treatment of IDD.

An optimized culture system for notochordal cell expansion with retention of phenotype

BACKGROUND

Notochordal (NC) cells display therapeutic potential in treating degeneration of the intervertebral disc. However, research on their phenotype and function is limited by low-cell yields and a lack of appropriate methodology for cell expansion. Utilizing porcine cells, this study aimed to develop an optimized culture system which allows expansion of NC cell populations with retention of phenotype.

METHODS

Post-natal porcine and foetal human nucleus pulposus tissue was compared histologically and expression of known NC cell marker genes by porcine NC cells was analyzed. Porcine NC cells were isolated from six-week post-natal discs and cultured in vitro under varied conditions: (1) DMEM vs αMEM; (2) laminin-521, fibronectin, gelatin and uncoated tissue culture-treated polystyrene (TCP); (3) 2% O2 vs normoxia; (4) αMEM (300 mOsm/L) vs αMEM (400 mOsm/L); (5) surface stiffness of 0.5 and 4 kPa and standard TCP. Adherence, proliferation, morphology and expression of NC cell markers were assessed over a 14-day culture period.

RESULTS

Native porcine nucleus pulposus tissue demonstrated similar morphology to human foetal tissue and porcine NC cells expressed known notochordal markers (CD24, KRT8, KRT18, KRT19, and T). Use of αMEM media and laminin-521-coated surfaces showed the greatest cell adherence, proliferation and retention of NC cell morphology and phenotype. Proliferation of NC cell populations was further enhanced in hypoxia (2%) and phenotypic retention was improved on 0.5 kPa culture surfaces.

DISCUSSION

Our model has demonstrated an optimized system in which NC cell populations may be expanded while retaining a notochordal phenotype. Application of this optimized culture system will enable NC cell expansion for detailed phenotypic and functional study, a major advantage over current culture methods described in the literature. Furthermore, the similarities identified between porcine and human NC cells suggest this system will be applicable in human NC cell culture for investigation of their therapeutic potential.

Upregulation of glycosaminoglycan synthesis by Neurotropin in nucleus pulposus cells via stimulation of chondroitin sulfate N-acetylgalactosaminyltransferase 1: A new approach to attenuation of intervertebral disc degeneration

It is suggested that most cases of low back pain are related to degeneration of intervertebral discs. Disc degeneration is a chronic and progressive disease and the search for effective medical treatments continues. Neurotropin is widely used in Japan and China to treat low back pain and neck–shoulder–arm syndrome. The present study aimed to investigate the effect of Neurotropin on glycosaminoglycan synthesis in nucleus pulposus cells. Cultured human nucleus pulposus cells were treated with Neurotropin every second day for two weeks. Production of glycosaminoglycan was assessed using a dimethyl-methylene blue assay and PicoGreen was used to measure DNA content. Microarray analysis, real-time PCR, and western blotting were performed to assess the biological processes related to Neurotropin-stimulated glycosaminoglycan synthesis. The results showed that the level of glycosaminoglycan normalized to DNA content was significantly upregulated by the addition of Neurotropin. Gene expression profiling showed over two-fold upregulation of 697 genes in response to Neurotropin treatment. Among these genes, ontological analysis suggested significant implication of phosphatidylinositol 3-kinase signaling, and analysis focused on this pathway demonstrated marked upregulation of angiopoietin 1 and insulin-like growth factor 1. Activation of phosphorylation of the signal transducer protein AKT was detected by western blotting. Of the genes related to sulfated glycosaminoglycan synthesis, the greatest increase in mRNA levels was observed for chondroitin sulfate N-acetylgalactosaminyltransferase 1, an enzyme initiating synthesis of chondroitin sulfate side chains attached to a core protein of aggrecan, which is a predominant disc matrix component. These findings suggest that Neurotropin may activate the phosphatidylinositol 3-kinase–AKT pathway and stimulate glycosaminoglycan synthesis through upregulation of expression of mRNA for chondroitin sulfate N-acetylgalactosaminyltransferase 1. Because there was no cytotoxic cellular growth inhibition, Neurotropin treatment might offer an accessible therapeutic strategy for intervertebral disc degeneration.

A selective inhibition of c-Fos/activator protein-1 as a potential therapeutic target for intervertebral disc degeneration and associated pain

Intervertebral disc (IVD) degeneration is a major cause of low back pain. The transcription factor c-Fos/Activator Protein-1 (AP-1) controls the expression of inflammatory cytokines and matrix metalloproteinases (MMPs) that contribute to the pathogenesis IVD degeneration. We investigated the effects of inhibition of c-Fos/AP-1 on IVD degeneration and associated pain. A selective inhibitor, T-5224, significantly suppressed the interleukin-1β-induced up-regulation of Mmp-3, Mmp-13 and Adamts-5 transcription in human nucleus pulposus cells and in a mouse explant culture model of IVD degeneration. We used a tail disc percutaneous needle puncture method to further assess the effects of oral administration of T-5224 on IVD degeneration. Analysis of disc height, T2-magnetic resonance imaging (MRI) findings, and histology revealed that IVD degeneration was significantly mitigated by T-5224. Further, oral administration of T-5224 ameliorated pain as indicated by the extended tail-flick latency in response to heat stimulation of rats with needle-puncture-induced IVD degeneration. These findings suggest that the inhibition of c-Fos/AP-1 prevents disc degeneration and its associated pain and that T-5224 may serve as a drug for the prevention of IVD degeneration.

Neuroprotective effects of curcumin alleviate lumbar intervertebral disc degeneration through regulating the expression of iNOS, COX‑2, TGF‑β1/2, MMP‑9 and BDNF in a rat model

Curcumin is a natural product with antimutagenic, antitumor, antioxidant and neuroprotective properties. However, to the best of our knowledge, curcumin has yet to be investigated for the treatment of lumbar intervertebral disc degeneration LIDD). The aim of the present study was to investigate whether curcumin can alleviate LIDD through regulating the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)‑2, transforming growth factor (TGF)‑β1/2, matrix metalloproteinase (MMP)‑9 and brain‑derived neurotrophic factor (BDNF) in a rat model of LIDD. The results of the present study suggest that pretreatment with curcumin can prevent the development of LIDD in rats. It was revealed that treatment with curcumin significantly reduced interleukin (IL)‑1β and IL‑6, iNOS, COX‑2 and MMP‑9 levels in rats with LIDD. In addition, treatment with curcumin reduced the mRNA expression levels of TGF‑β1 and TGF‑β2, whereas it increased the mRNA expression levels of BDNF in rats with LIDD. In conclusion, the present findings indicate that curcumin may exert protective effects on LIDD development, exerting its action through the regulation of iNOS, COX‑2, TGF‑β1/2, MMP‑9 and BDNF.

Are Modic changes associated with intervertebral disc cytokine profiles?

BACKGROUND CONTEXT

Degenerative changes including Modic changes (MCs) are commonly observed in patients with chronic low back pain. Although intervertebral disc (IVD) cytokine expression has been shown to be associated with low back pain, the cytokine profile for degenerative IVD with and without MC has not been compared.

PURPOSE

This study aimed to evaluate the potential association between IVD cytokine expression and MCs.

STUDY DESIGN

A laboratory study was carried out.

METHODS

The IVD tissue samples from 10 patients with type II MCs and10 patients without MCs who underwent an anterior lumbar interbody and fusion for significant low back pain were collected. The expression levels of 42 cytokines were determined using a RayBio Human Cytokine Antibody Array 3 (RayBiotech Inc, Norcross, GA, USA) and the results were verified with enzyme-linked immunosorbent assay (ELISA).

RESULTS

The cytokine array demonstrated a statistically significant increase in the expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) (p=.001) and epithelial-derived neutrophil-activating peptide 78 (ENA-78) (p=.04), and a trend toward an increase in interleukin-1β (IL-1β) (p=.12) and tumor necrosis factor-α (TNF-α) (p=.22) in IVDs associated with type II MCs. These results were validated with ELISA which demonstrated a 3.85-fold increase in the GM-CSF level between IVDs with type II MCs compared with those without MCs (p=.03). Similarly there was a significant increase in the level of both ENA-78 (3.68-fold, p=.02) and IL-1β (2.11-fold, p=.01) in IVDs with type II MCs. Lastly, there was a trend (p=.07) toward an increase in TNF-α in IVDs with type II MCs (4.4-fold).

CONCLUSION

Intervertebral discs with type II MCs demonstrate a significant increase in IL-1β, GM-CSF, and ENA-78, and there is a trend toward an increase in TNF-α. These results further strengthen the association between MCs and low back pain.

Sp1 downregulates proinflammatory cytokine‑induced catabolic gene expression in nucleus pulposus cells

During the pathogenesis of intervertebral disc degeneration, pro‑inflammatory cytokines, including tumor necrosis factor‑α (TNF‑α), stimulate the degradation of the extracellular matrix (ECM) of intervertebral discs via the activity of catabolic enzymes including matrix metalloproteinases (MMPs), disintegrins and metalloproteinases with thrombospondin motifs (ADAMTSs), and cyclooxygenase 2 (Cox2). The transcriptional promoters of the human catabolic enzymes MMPs, ADAMTS, Cox2 and Syndecan 4 contain at least one specificity protein‑1 (Sp1) transcription factor‑binding site. The present study investigated the role of Sp1 in the regulation of the mRNA and protein expression of the aforementioned catabolic enzyme genes in nucleus pulposus cells, using reverse transcription‑quantitative polymerase chain reaction, western blot, transfection and RNA interference. The data demonstrated that Sp1 transcription factor protein expression is induced by TNF‑α and interleukin‑1β. Specific inhibitors of Sp1 DNA binding to its GC‑rich consensus site, WP631 and mithramycin A, partially suppressed TNF‑α‑induced catabolic enzyme expression and activity. Genetic inhibition of Sp1 by small interfering RNA‑mediated Sp1 knockdown partially inhibited catabolic enzyme induction by TNF‑α. In addition, Sp1 transcription factor inhibitors decreased the activity of MMP3, ADAMTS4 and ADAMTS5 promoters. Furthermore, chromatin immunoprecipitation revealed functional Sp1 binding sites at ‑577/‑567 bp within the ADAMTS4 promoter and ‑718/‑708 bp within the ADAMTS5 promoter. These results provide pharmacological and genetic evidence of the importance of Sp1 in catabolic enzyme gene regulation during TNF‑α stimulation. Thus, Sp1 may represent an effective target in reducing intervertebral disc‑associated ECM loss.

Association Between Lumbar Disc Degeneration and Propionibacterium acnes Infection: Clinical Research and Preliminary Exploration of Animal Experiment

STUDY DESIGN

Clinical research and animal experiment.

OBJECTIVE

To investigate whether lumbar disc degeneration is associated with Propionibacterium acnes (P acnes) infection.

SUMMARY OF BACKGROUND DATA

The hypothesis that herniated discs may be infected with P acnes by way of bacteremia is remarkable. This may bring a tremendous change in treatment of lumbar disc herniation (LDH). However, this hypothesis is still controversial. Since P acnes isolated may be related to contamination.

METHODS

Nucleus pulposus from 22 patients (30 discs) with lumbar disc herniation was collected during discectomy, following aerobic and anaerobic cultures for 10 days.Twenty-four rabbits were divided into four groups. After L3-L6 being exposed, an incision was made into the three discs in groups A and B. While in groups C and D, two random segments were operated. Six weeks later, 0.05 mL of 5 × 10 CFU/mL P acnes was inoculated into operated discs in group A and sterile physiological saline in group B. In group C, 0.2 mL of 5 × 10 CFU/mL P acnes was injected through ear vein. Sterile saline was used in group D. Six weeks later, MRI was performed. Then, nucleus pulposus and paraspinal muscles were harvested for aerobic and anaerobic cultures.

RESULTS

Clinical research: Anaerobic cultures were positive in three cases: two coagulase-negative staphylococci, one particles chain bacterium. No P acnes was found. Staphylococcus epidermidis was isolated in one aerobic culture.Animal experiment: P acnes was found in 11 out of 18 (61%) discs in group A. There was no P acnes found in the other three groups.

CONCLUSION

Degenerated discs were suitable for P acnes growth. This research did not find the evidence of the symptomatic degenerated lumbar discs infected with P acnes or that P acnes could infect the degenerated lumbar discs by way of bacteremia.

LEVEL OF EVIDENCE

N/A.

Dysregulated miR-98 Contributes to Extracellular Matrix Degradation by Targeting IL-6/STAT3 Signaling Pathway in Human Intervertebral Disc Degeneration

Intervertebral disc degeneration (IDD) is associated with dysregulated expression of microRNAs (miRNAs). However, the precise molecular mechanisms underlying this disorder remain unclear. Therefore, we tested the hypothesis that miRNAs modulate IDD through effects on the IL-6/STAT3 signaling pathway, a potential regulator of IDD. The miRNA expression profile was determined in nucleus pulposus (NP) tissues from patients with IDD and controls, employing miRNA microarray and quantitative real-time PCR (RT-qPCR). Biological functions of differential expression miRNAs were further investigated using immunofluorescent staining. Luciferase reporter assays and Western blotting were performed to determine miRNA targets. We identified 41 miRNAs that were differentially expressed in patients compared with controls. Following RT-qPCR confirmation, miR-98 was significantly downregulated in degenerative NP tissues. Moreover, its level was inversely correlated with grade of disc degeneration. Through gain-of-function and loss-of-function studies, miR-98 was shown to significantly promote type II collagen expression in NP cells. Interleukin-6 (IL-6) was identified as a target of miR-98. Knockdown of IL-6 induced effects on NP cells similar to those induced by miR-98. In contrast, IL-6 treatment abrogated the effects induced by miR-98 upregulation. Moreover, miR-98 dramatically suppressed expression of STAT3 target gene, MMP2. IL-6 treatment antagonized this effect, whereas knockdown of IL-6 by IL-6 short hairpin RNA (shIL-6) induced inhibitory effects on the expression of p-STAT3 and its main target genes, similar to miR-98. The mRNA level of IL-6 was inversely correlated with that of miR-98 in degenerative NP tissues. These results suggest the downregulation of miR-98 could promote IDD through the IL-6/STAT3 signaling pathway. Our findings also highlight miR-98 as a novel hopeful therapeutic target for IDD.

Molecular basis for cytokine biomarkers of complex 3D microtissue physiology in vitro

'Physiologically more-relevant' claims are readily made for cells cultured on any surface or in a scaffold that provides loosely defined 3D geometry. A set of tools to measure culture '3D-ness' more accurately are needed. Such tools should find applications in fields ranging from high-throughput identification of substrates for tissue engineering and regenerative medicine to cell-based screening of drug candidates. Until now, these fields have not provided a consensus for the most promising place to initiate the search. Here, we review recent advances in transcriptomic, proteomic, inflammation and oncology-related pathways, as well as functional studies that strongly point to cytokines as the most likely compounds to form the missing consensus.

Heme oxygenase-1 attenuates IL-1β induced alteration of anabolic and catabolic activities in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is characterized by disordered extracellular matrix (ECM) metabolism, implicating subdued anabolism and enhanced catabolic activities in the nucleus pulposus (NP) of discs. Pro-inflammatory cytokines such as interleukin-1β (IL-1β) are considered to be potent mediators of ECM breakdown. Hemeoxygenase-1 (HO-1) has been reported to participate in cellular anti-inflammatory processes. The purpose of this study was to investigate HO-1 modulation of ECM metabolism in human NP cells under IL-1β stimulation. Our results revealed that expression of HO-1 decreased considerably during IDD progression. Induction of HO-1 by cobalt protoporphyrin IX attenuated the inhibition of sulfate glycosaminoglycan and collagen type II (COL-II) synthesis and ameliorated the reduced expressions of aggrecan, COL-II, SOX-6 and SOX-9 mediated by IL-1β. Induction of HO-1 also reversed the effect of IL-1β on expression of the catabolic markers matrix metalloproteinases-1, 3, 9 and 13. This was combined with inhibition of the activation of mitogen-activated protein kinase signaling. These findings suggest that HO-1 might play a pivotal role in IDD, and that manipulating HO-1 expression might mitigate the impairment of ECM metabolism in NP, thus potentially offering a novel therapeutic approach to the treatment of IDD.

Interleukin-1β in intervertebral disk degeneration

Intervertebral disk degeneration (IDD) is the most common diagnosis in patients with low back pain, a main cause of musculoskeletal disability in the world. Interleukin-1 (IL-1) β is the most important member of the IL-1 family, and has a strong pro-inflammatory activity by stimulating the secretion of multiple pro-inflammatory mediators. IL-1β is highly expressed in degenerative intervertebral disk (IVD) tissues and cells, and it has been shown to be involved in multiple pathological processes during disk degeneration, including inflammatory responses, matrix destruction, angiogenesis and innervation, cellular apoptosis, oxidative stress and cellular senescence. However, inhibition of IL-1β is found to promote extracellular matrix (ECM) repair and protect against disk regeneration. In this review, after a brief description of IL-1β signaling, we mainly focus on the expression profiles, roles and therapeutic potential of IL-1β in IDD. A better understanding will help develop novel IL-1β-based therapeutic interventions for degenerative disk disease.

Effects of Tobacco Smoking on the Degeneration of the Intervertebral Disc: A Finite Element Study

Tobacco smoking is associated with numerous pathological conditions. Compelling experimental evidence associates smoking to the degeneration of the intervertebral disc (IVD). In particular, it has been shown that nicotine down-regulates both the proliferation rate and glycosaminoglycan (GAG) biosynthesis of disc cells. Moreover, tobacco smoking causes the constriction of the vascular network surrounding the IVD, thus reducing the exchange of nutrients and anabolic agents from the blood vessels to the disc. It has been hypothesized that both nicotine presence in the IVD and the reduced solute exchange are responsible for the degeneration of the disc due to tobacco smoking, but their effects on tissue homeostasis have never been quantified. In this study, a previously presented computational model describing the homeostasis of the IVD was deployed to investigate the effects of impaired solute supply and nicotine-mediated down-regulation of cell proliferation and biosynthetic activity on the health of the disc. We found that the nicotine-mediated down-regulation of cell anabolism mostly affected the GAG concentration at the cartilage endplate, reducing it up to 65% of the value attained in normal physiological conditions. In contrast, the reduction of solutes exchange between blood vessels and disc tissue mostly affected the nucleus pulposus, whose cell density and GAG levels were reduced up to 50% of their normal physiological levels. The effectiveness of quitting smoking on the regeneration of a degenerated IVD was also investigated, and showed to have limited benefit on the health of the disc. A cell-based therapy in conjunction with smoke cessation provided significant improvements in disc health, suggesting that, besides quitting smoking, additional treatments should be implemented in the attempt to recover the health of an IVD degenerated by tobacco smoking.

Substance P Receptor Antagonist Suppresses Inflammatory Cytokine Expression in Human Disc Cells

STUDY DESIGN

Laboratory study.

OBJECTIVE

To evaluate whether blockade of the Substance P (SP) NK1R attenuates its proinflammatory effect on human intervertebral disc cells (IVD), and to evaluate the signaling pathways associated with SP.

SUMMARY OF BACKGROUND DATA

SP and its receptors are expressed in human IVD cells, and cause upregulation of inflammatory mediators; however, the effects of blocking these receptors have not been studied in human IVD cells.

METHODS

Human annulus fibrosus (AF) and nucleus pulposus (NP) cells were expanded in monolayer, and then suspended in alginate beads. The alginate beads were treated with culture medium first containing a high affinity NK1R antagonist (L-760735) at different concentrations, and then with medium containing both NK1R antagonist and SP at 2 concentrations. Ribonucleic acid was isolated and transcribed into cDNA. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to evaluate expression of interleukin (IL)-1β, IL-6, and IL-8. Western blot analysis was performed to examine levels of the phosphorylated p38 mitogen-activated protein kinase (MAPK), extracellular signal regulated kinase 1/2 (ERK1/2) and nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB p65). The cells were pretreated with specific inhibitors of p38 (SB203580), ERK1/2 (PD98059), and p65 (SM7368) and then stimulated with SP.

RESULTS

We detected expression of NK1R, neurokinin receptor 2 (NK2R), and neurokinin receptor 3 (NK3R) in AF and NP cells. Treatment of disc cells with the NK1R antagonist was able to suppress expression of IL-1β, IL-6, and IL-8 in a dose-dependent manner. SP stimulation increased phosphorylation of p38-MAPK and ERK1/2, but not of NFκB p65. This indicates that p38-MAPK and ERK1/2 control SP-induced cytokine expression independently from NF-kB p65. Inhibition of p38 and ERK1/2 activation reduced SP-induced IL-6 production in human disc cells.

CONCLUSION

NK1R is responsible for the proinflammatory effect of SP on IVD cells and this effect can be blocked by preventing binding of SP to NK1R. This study shows for the first time that SP mediates signaling in disc cells through NK1R and that SP activates the proinflammatory p38-MAPK and ERK1/2 pathways.

LEVEL OF EVIDENCE

4.

Inflammatory Kinetics and Efficacy of Anti-inflammatory Treatments on Human Nucleus Pulposus Cells

STUDY DESIGN

Human nucleus pulposus (NP) cell culture study investigating response to tumor necrosis factor-α (TNFα), effectiveness of clinically available anti-inflammatory drugs, and interactions between proinflammatory cytokines.

OBJECTIVE

To characterize the kinetic response of proinflammatory cytokines released by human NP cells to TNFα stimulation and the effectiveness of multiple anti-inflammatories with 3 substudies: Timecourse, Same-time blocking, Delayed blocking.

SUMMARY OF BACKGROUND DATA

Chronic inflammation is a key component of painful intervertebral disc degeneration. Improved efficacy of anti-inflammatories requires better understanding of how quickly NP cells produce proinflammatory cytokines and which proinflammatory mediators are most therapeutically advantageous to target.

METHODS

Degenerated human NP cells (n = 10) were cultured in alginate with or without TNFα (10 ng/mL). Cells were incubated with 1 of 4 anti-inflammatories (anti-IL-6 receptor/atlizumab, IL-1 receptor anatagonist, anti-TNFα/infliximab and sodium pentosan polysulfate/PPS) in 2 blocking-studies designed to determine how intervention timing influences drug efficacy. Cell viability, protein, and gene expression for IL-1β, IL-6, and IL-8 were assessed.

RESULTS

Timecourse: TNFα substantially increased the amount of IL-6, IL-8, and IL-1β, with IL-1β and IL-8 reaching equilibrium within ∼72 hours (IL-1β: 111 ± 40 pg/mL, IL-8: 8478 ± 957 pg/mL), and IL-6 not reaching steady state after 144 hours (1570 ± 435 pg/mL). Anti-TNFα treatment was most effective at reducing the expression of all cytokines measured when added at the same time as TNFα stimulation. Similar trends were observed when drugs were added 72 hours after TNFα stimulation, however, no anti-inflammatories significantly reduced cytokine levels compared with TNF control.

CONCLUSION

IL-1β, IL-6, and IL-8 were expressed at different rates and magnitudes suggesting different roles for these cytokines in disease. Autocrine signaling of IL-6 or IL-1β did not contribute to the expression of any proinflammatory cytokines measured in this study. Anti-inflammatory treatments were most effective when applied early in the inflammatory process, when targeting the source of the inflammation.

LEVEL OF EVIDENCE

N/A.

Differential gene expression in anterior and posterior annulus fibrosus

STUDY DESIGN

Laboratory study.

OBJECTIVE

To evaluate the differential gene expression of cytokines and growth factors in anterior versus posterior annulus fibrosus (AF) intervertebral disc (IVD) specimens.

SUMMARY OF BACKGROUND DATA

Histological analysis has demonstrated regional differences in vascular and neural ingrowth in the IVD, and similar differences may exist for cytokine and growth factor expression in patients with degenerative disc disease (DDD). Regional expression of these cytokines may also be related to the pain experienced in DDD.

METHODS

IVD tissue was obtained from patients undergoing anterior lumbar interbody fusion surgery for back pain with radiological evidence of disc degeneration. For a control group, the discs of patients undergoing anterior lumbar discectomy for degenerative scoliosis were obtained as well. The tissue was carefully removed and separated into anterior and posterior AF. After tissue processing, an antibody array was completed to determine expression levels of 42 cytokines and growth factors.

RESULTS

Nine discs from 7 patients with DDD and 5 discs from 2 patients with scoliosis were analyzed. In the DDD group, there were 10 cytokines and growth factors with significantly increased expression in the posterior AF versus the anterior AF ([interleukin] IL-4, IL-5, IL-6, M-CSF, MDC, tumor necrosis factor β, EGF, IGF-1, angiogenin, leptin). In the scoliosis group, only angiogenin and PDGF-BB demonstrated increased expression in the posterior AF. No cytokines or growth factors had increased expression in the anterior AF compared with posterior AF.

CONCLUSION

The posterior AF expresses increased levels of cytokines and growth factors compared with the anterior AF in patients with DDD. This differential expression may be important for targeting treatment of painful IVDs.

LEVEL OF EVIDENCE

N/A.