Interleukin-1β in intervertebral disk degeneration

Causal relationship of interferon-γ and interleukin-18 upstream of intervertebral disc degeneration pathogenesis: a two-sample Mendelian randomization study

Introduction

Intervertebral disc degeneration (IVDD) is a complex disease caused by genetic and environmental factors, but its pathogenesis is still unclear. Although studies of inflammatory cytokines have been used in recent years to unravel the biological mechanisms of a variety of diseases, such analyses have not yet been applied to IVDD. Therefore, we used a Mendelian Randomization approach to explore the potential mechanisms underlying the pathogenesis of IVDD.

Methods

We obtained GWAS data from publicly available databases for inflammatory cytokines and IVDD, respectively, and explored the causal relationship between individual inflammatory cytokines and IVDD using instrumental variable (IV) analysis. We primarily used IVW methods to assess causality, while sensitivity, heterogeneity and multidirectionality analyses were performed for positive results (p < 0.05). All analyses were performed using R software.

Results

In our study, we performed a two-sample MR analysis of 41 inflammatory cytokines to identify metabolites causally associated with IVDD. Ultimately, 2 serum metabolites associated with IVDD were identified (pval<0.05), IFN-γ and IL-18. sensitivity, heterogeneity, and Pleiotropy test analyses were performed for all results.

Conclusion

Our study identified a causal relationship between IFN-γ and IL-18 and IVDD. It is valuable for the monitoring and prevention of IVDD and the exploration of targeted drugs. However, more evidence is needed to validate our study.

Ephrin B2 (EFNB2) potentially protects against intervertebral disc degeneration through inhibiting nucleus pulposus cell apoptosis

Nucleus pulposus (NP) cell apoptosis is a significant indication of accelerated intervertebral disc degeneration; however, the precise mechanism is unelucidated as of yet. Ephrin B2 (EFNB2), the only gene down-regulated in the three degraded intervertebral disc tissue microarray groups (GSE70362, GSE147383 and GSE56081), was screened for examination in this study. Subsequently, EFNB2 was verified to be down-regulated in degraded NP tissue samples. Interleukin-1 (IL-1β) treatment of NP cells to simulate the IDD environment indicated that IL-1β treatment decreased EFNB2 expression. In degenerative NP cells stimulated by IL-1β, EFNB2 knockdown significantly increased the rate of apoptosis as well as the apoptosis-related molecules cleaved-caspase-3 and the Bax to Bcl-2 ratio. EFNB2 was found to promote AKT, PI3K, and mTOR phosphorylation; the PI3K/AKT signaling role was investigated using the PI3K inhibitor LY294002. EFNB2 overexpression significantly increased PI3K/AKT pathway activity in IL-1β-stimulated NP cells than the normal control. Moreover, EFNB2 partially alleviated NP cell apoptosis induced by IL-1β, reduced the cleaved-cas3 level, and decreased the Bax/Bcl-2 ratio after the addition of the inhibitor LY294002. Additionally, EFNB2 overexpression inhibited the ERK1/2 phosphorylation; the effects of EFNB2 overexpression on ERK1/2 phosphorylation, degenerative NP cell viability, and cell apoptosis were partially reversed by ERK signaling activator Ceramide C6. EFNB2 comprehensively inhibited the apoptosis of NP cells by activating the PI3K/AKT signaling and inhibiting the ERK signaling, obviating the exacerbation of IDD. EFNB2 could be a potential target to protect against degenerative disc changes.

Genkwanin alleviates intervertebral disc degeneration via regulating ITGA2/PI3K/AKT pathway and inhibiting apoptosis and senescence

Intervertebral disc degeneration (IVDD) is a progressive degenerative disease influenced by various factors. Genkwanin, a known anti-inflammatory flavonoid, has not been explored for its potential in IVDD management. This study aims to investigate the effects and mechanisms of genkwanin on IVDD. In vitro, cell experiments revealed that genkwanin dose-dependently inhibited Interleukin-1β-induced expression levels of inflammatory factors (Interleukin-6, inducible nitric oxide synthase, cyclooxygenase-2) and degradation metabolic protein (matrix metalloproteinase-13). Concurrently, genkwanin upregulated the expression of synthetic metabolism genes (type II collagen, aggrecan). Moreover, genkwanin effectively reduced the phosphorylation of phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin, mitogen-activated protein kinase (MAPK), and nuclear factor-κB (NF-κB) pathways. Transcriptome sequencing analysis identified integrin α2 (ITGA2) as a potential target of genkwanin, and silencing ITGA2 reversed the activation of PI3K/AKT pathway induced by Interleukin-1β. Furthermore, genkwanin alleviated Interleukin-1β-induced senescence and apoptosis in nucleus pulposus cells. In vivo animal experiments demonstrated that genkwanin mitigated the progression of IVDD in the rat model through imaging and histological examinations. In conclusion, This study suggest that genkwanin inhibits inflammation in nucleus pulposus cells, promotes extracellular matrix remodeling, suppresses cellular senescence and apoptosis, through the ITGA2/PI3K/AKT, NF-κB and MAPK signaling pathways. These findings indicate that genkwanin may be a promising therapeutic candidate for IVDD.

Myricetin Protects Against Rat Intervertebral Disc Degeneration Partly Through the Nrf2/HO-1/NF-κB Signaling Pathway

Intervertebral disc (IVD) degeneration (IDD) is a prevalent musculoskeletal disorder. Nucleus pulposus cells (NPCs) play a significant role in the normal functioning of the IVD. Myricetin is an agent that exerts anti-inflammatory and antioxidant effects in various pathological conditions. Here, we investigated the ameliorative effects of myricetin on the IVD degeneration. NPCs were obtained from the IVD of rats, and were treated with myricetin (0, 5, 10, 15, 20 μM) for 24 h before 20 ng/mL IL-1β stimulation. RT-qPCR, western blotting, and ELISA were applied to evaluate the levels of inflammatory factors (iNOS, COX-2, TNF-α, IL-6, PGE2, and Nitrite) and extracellular matrix (ECM)-associated components (MMP13, ADAMTS-5, aggrecan, and collagen II) in NPCs. Activation status of related signaling pathways (NF-κB and Nrf2) was determined using western blotting and immunofluorescence staining. Experimental rat models of IDD were established using a needle puncture method. Myricetin (20 mg/kg) was administrated intraperitoneally, and the degeneration was evaluated using histopathological analysis. Myricetin treatment attenuated the IL-1β-induced production of inflammatory factors in NPCs. Downregulation of aggrecan and collagen II as well as upregulation of MMP-13 and ADAMTS-5 in NPCs caused by IL-1β was reversed by myricetin treatment. Mechanistically, myricetin blocked NF-κB signaling by activation of Nrf2 in IL-1β-stimulated NPCs. Moreover, inhibition of Nrf2 reversed the protective effects of myricetin in NPCs. The in vivo experiments showed that myricetin ameliorated the IDD progression in rats. The present work suggests that Nrf2 is involved in the pathogenesis of IDD and shows the protective effects as well as the underlying mechanism of myricetin on Nrf2 activation in NPCs.

Mitochondrial dysfunction: a new molecular mechanism of intervertebral disc degeneration

OBJECTIVE

Intervertebral disc degeneration (IVDD) is a chronic degenerative orthopedic illness that causes lower back pain as a typical clinical symptom, severely reducing patients' quality of life and work efficiency, and imposing a significant economic burden on society. IVDD is defined by rapid extracellular matrix breakdown, nucleus pulposus cell loss, and an inflammatory response. It is intimately related to the malfunction or loss of myeloid cells among them. Many mechanisms have been implicated in the development of IVDD, including inflammatory factors, oxidative stress, apoptosis, cellular autophagy, and mitochondrial dysfunction. In recent years, mitochondrial dysfunction has become a hot research topic in age-related diseases. As the main source of adenosine triphosphate (ATP) in myeloid cells, mitochondria are essential for maintaining myeloid cell survival and physiological functions.

METHODS

We searched the PUBMED database with the search term "intervertebral disc degeneration and mitochondrial dysfunction" and obtained 82 articles, and after reading the abstracts and eliminating 30 irrelevant articles, we finally obtained 52 usable articles.

RESULTS

Through a review of the literature, it was discovered that IVDD and cellular mitochondrial dysfunction are also linked. Mitochondrial dysfunction contributes to the advancement of IVDD by influencing a number of pathophysiologic processes such as mitochondrial fission/fusion, mitochondrial autophagy, cellular senescence, and cell death.

CONCLUSION

We examine the molecular mechanisms of IVDD-associated mitochondrial dysfunction and present novel directions for quality management of mitochondrial dysfunction as a treatment approach to IVDD.

Pure platelet-rich plasma promotes semaphorin-3A expression: a novel insight to ameliorate intervertebral disk degeneration in vitro

INTRODUCTION

Intervertebral disk degeneration (IVDD) can be effectively treated using platelet-rich plasma (PRP). While the exact process is fully understood, it is believed that using pure PRP (P-PRP) without leukocytes is a better option for preventing IVDD. Semaphorin-3A (Sema3A), an inhibitor of angiogenesis and innervation, is essential for preserving IVDD's homeostasis. Whether PRP prevents IVDD by modifying Sema3A has yet to receive much research. This work aims to clarify how P-PRP affects Sema3A when IVDD develops in vitro.

METHODS

Nucleus pulposus cells (NPCs) isolated from 8-week-old male Sprague-Dawley rats were exposed to 10 ng/ml IL-1β and then treated with P-PRP or leukocyte platelet-rich plasma (L-PRP) in vitro, followed by measuring cell proliferation, apoptosis and microstructures, inflammatory gene and Sema3A expression, as well as anabolic and catabolic protein expression by immunostaining, quantitative real-time polymerase chain reaction (qPCR), western blot, and enzyme-linked immunosorbent assay (ELISA).

RESULTS

In comparison with L-PRP, P-PRP had a higher concentration of growth factors but a lower concentration of inflammatory substances. P-PRP increased the proliferation of NPCs, while IL-1 relieved the amount of apoptosis due to its intervention. Anabolic genes, aggrecan, and collagen II had higher expression levels. MMP-3 and ADAMTS-4, two catabolic or inflammatory genes, showed lower expression levels. Sema3A activity was enhanced after P-PRP injection, whereas CD31 and NF200 expression levels were suppressed.

CONCLUSIONS

P-PRP enhanced the performance of NPCs in IVDD by modifying the NF-κB signaling pathway and encouraging Sema3A expression, which may offer new therapy options for IVDD.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

The findings provide a new therapeutic target for the treatment of IVDD and show a novel light on the probable mechanism of PRP and the function of Sema3A in the progression of IVDD.

Effect of Moxibustion on Inflammatory Cytokines for Low Back Pain: A Systematic Review, Meta-Analysis and Meta-Regression

Background and Objective

Moxibustion is effective for low back pain (LBP), and inflammatory cytokines may play an important role in the mechanism of moxibustion treatment. The purpose of this meta-analysis was to explore the mechanism of moxibustion in LBP in terms of inflammatory cytokines.

Methods

We searched China National Knowledge Infrastructure, Wanfang database, Cochrane Central Register of Controlled Trials, Ovid MEDLINE, Embase, PubMed, and Web of Science to identify eligible randomized controlled trials (RCTs). There was no restriction on the publication date.

Results

Thirty RCTs measuring interleukin (IL-) 1, IL-1β, IL-6, IL-12, IL-17, IL-23, and tumor necrosis factor (TNF-) α were included in this meta-analysis. Compared to controls: single moxibustion could effectively decrease levels IL-6 and IL-23 (SMD, -0.71, 95% CI: -1.25 to -0.17, p = 0.01; SMD, -1.61, 95% CI: -2.20 to -1.03, p < 0.01, respectively); combined moxibustion had significant effects on IL-1, IL-1β, IL-6, IL-12, IL-17, and TNF-α (p < 0.05). Overall, for LBP, single or combined moxibustion could effectively down-regulate levels of pro-inflammatory cytokines (p = 0.007 and p < 0.00001, respectively). For safety of moxibustion, the incidence rate of side effects was similar to that of controls (RD, -0.01, 95% CI: -0.02 to 0.01, p = 0.59). Sensitivity analysis showed that the pooled estimates were robust, and publication bias analysis showed there was a significant small study effect (Egger's test p = 0.0000). High statistical heterogeneity existed between included RCTs, meta-regression showed there was no potential factor explaining the source of heterogeneity.

Conclusion

For LBP, moxibustion can effectively decrease levels of IL-1, IL-1β, IL-6, IL-12, IL-17, IL-23, and TNF-α to achieve analgesia. Because the side effects of moxibustion are transient, it is relatively safe for clinical use. However, based on high heterogeneity in this meta-analysis, rigorously designed RCTs are required to further confirm the results in this review.

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.

A Review: Methodologies to Promote the Differentiation of Mesenchymal Stem Cells for the Regeneration of Intervertebral Disc Cells Following Intervertebral Disc Degeneration

Intervertebral disc (IVD) degeneration (IDD), a highly prevalent pathological condition worldwide, is widely associated with back pain. Treatments available compensate for the impaired function of the degenerated IVD but typically have incomplete resolutions because of their adverse complications. Therefore, fundamental regenerative treatments need exploration. Mesenchymal stem cell (MSC) therapy has been recognized as a mainstream research objective by the World Health Organization and was consequently studied by various research groups. Implanted MSCs exert anti-inflammatory, anti-apoptotic, and anti-pyroptotic effects and promote extracellular component production, as well as differentiation into IVD cells themselves. Hence, the ultimate goal of MSC therapy is to recover IVD cells and consequently regenerate the extracellular matrix of degenerated IVDs. Notably, in addition to MSC implantation, healthy nucleus pulposus (NP) cells (NPCs) have been implanted to regenerate NP, which is currently undergoing clinical trials. NPC-derived exosomes have been investigated for their ability to differentiate MSCs from NPC-like phenotypes. A stable and economical source of IVD cells may include allogeneic MSCs from the cell bank for differentiation into IVD cells. Therefore, multiple alternative therapeutic options should be considered if a refined protocol for the differentiation of MSCs into IVD cells is established. In this study, we comprehensively reviewed the molecules, scaffolds, and environmental factors that facilitate the differentiation of MSCs into IVD cells for regenerative therapies for IDD.

Current and Novel Therapeutics for Articular Cartilage Repair and Regeneration

Articular cartilage repair is a sophisticated process that has is being recently investigated. There are several different approaches that are currently reported to promote cartilage repair, like cell-based therapies, biologics, and physical therapy. Cell-based therapies involve the using stem cells or chondrocytes, which make up cartilage, to promote the growth of new cartilage. Biologics, like growth factors, are also being applied to enhance cartilage repair. Physical therapy, like exercise and weight-bearing activities, can also be used to promote cartilage repair by inducing new cartilage growth and improving joint function. Additionally, surgical options like osteochondral autograft, autologous chondrocyte implantation, microfracture, and others are also reported for cartilage regeneration. In the current literature review, we aim to provide an up-to-date discussion about these approaches and discuss the current research status.

TAK-715 alleviated IL-1β-induced apoptosis and ECM degradation in nucleus pulposus cells and attenuated intervertebral disc degeneration ex vivo and in vivo

BACKGROUND

Intervertebral disc degeneration (IDD) is one of the most common disorders related to the spine. Inflammation, apoptosis and extracellular matrix (ECM) degradation contribute to disc degeneration in nucleus pulposus cells (NPCs). This study focused on the role and mechanism of the p38 inhibitor TAK-715 in intervertebral disc degeneration.

METHODS

NPCs were treated with IL-1β to mimic apoptosis, followed by the addition of TAK-715. It was determined that apoptosis, inflammatory mediators (COX-2), inflammatory cytokines (HMGB1), and ECM components (collagen II, MMP9, ADAMTS5, and MMP3) existed in NPCs. In addition, the p38MAPK signaling pathways were examined. The role of TAK-715 in vivo was determined by acupuncture-induced intervertebral disc degeneration. Following an intradiscal injection of TAK-715, MRI and a histopathological analysis were conducted to assess the degree of degeneration.

RESULTS

IL-1β-induced apoptosis was alleviated by TAK-715 in vitro, and antiapoptotic proteins were upregulated. Furthermore, TAK-715 blocked IL-1β-induced inflammatory mediator production (COX-2) and inflammatory cytokine production (HMGB1) and degraded the ECM (collagen II, MMP9, ADAMTS5, and MMP3). By inhibiting the phosphorylation of p38, TAK-715 exerted its effects. In a rat tail model, TAK-715 ameliorates puncture-induced disc degeneration based on MRI and histopathology evaluations.

CONCLUSION

TAK-715 attenuated intervertebral disc degeneration in vitro and in vivo, suggesting that it might be an effective treatment for IDD.

Pharmacological network analysis of the functions and mechanism of kaempferol from Du Zhong in intervertebral disc degeneration (IDD)

Background

Senescence and apoptosis of the nucleus pulposus cells (NPCs) are essential components of the intervertebral disc degeneration (IDD) process. Senescence and anti-apoptosis treatments could be effective ways to delay or even stop disc degeneration. IDD has been treated with Eucommia ulmoides Oliver (Du Zhong, DZ) and its active ingredients. However, the roles and mechanisms of DZ in NPC apoptosis and senescence remain unclear.

Methods

Traditional Chinese Medicine Systems Pharmacology (TCMSP) database was used to select the main active ingredients of DZ with the threshold of oral bioavailability (OB) ​≥ ​30% and drug-likeness (DL) ​≥ ​0.2. GSE34095 contained expression profile of degenerative intervertebral disc tissues and non-degenerative intervertebral disc tissues were downloaded for different expression genes analysis. The disease targets genes of IDD were retrieved from GeneCards. The online tool Metascape was used for functional enrichment annotation analysis. The specific effects of the ingredient on IL-1β treated NPC cell proliferation, cell senescence, reactive oxygen species (ROS) accumulation and cell apoptosis were determined by CCK-8, SA-β-gal staining, flowcytometry and western blot assays.

Results

A total of 8 active compounds of DZ were found to meet the threshold of OB ​≥ ​30% and DL ​≥ ​0.2 with 4151 drug targets. After the intersection of 879 IDD disease targets obtained from GeneCards and 230 DEGs obtained from the IDD-related GSE dataset, a total of 13 hub genes overlapped. According to functional enrichment annotation analysis by Metascape, these genes showed to be dramatically enriched in AGE-RAGE signaling, proteoglycans in cancer, wound healing, transmembrane receptor protein tyrosine kinase signaling, MAPK cascades, ERK1/2 cascades, PI3K/Akt signaling pathway, skeletal system, etc. Disease association analysis by DisGeNET indicated that these genes were significantly associated with IDD, intervertebral disc disease, skeletal dysplasia, and other diseases. Active ingredients-targets-signaling pathway networks were constructed by Cytoscape, and kaempferol was identified as the hub active compound of DZ. In the IL-1β-induced IDD in vitro model, kaempferol treatment significantly improved IL-1β-induced NPC cell viability suppression and senescence. In addition, kaempferol treatment significantly attenuated IL-1β-induced ROS accumulation and apoptosis. Furthermore, kaempferol treatment partially eliminated IL-1β-induced decreases in aggrecan, collagen II, SOX9, and FN1 levels and increases in MMP3, MMP13, ADAMTS-4, and ADAMTS-5. Moreover, kaempferol treatment significantly relieved the promotive effects of IL-1β stimulation upon p38, JNK, and ERK1/2 phosphorylation. ERK1/2 inhibitor PD0325901 further enhanced the effect of kaempferol on the inhibition of ERK1/2 phosphorylation, downregulation of MMP3 and ADAMTS-4 expression, and upregulation of aggrecan and collagen II expressions.

Conclusion

Kaempferol has been regarded as the major active compound of DZ, protecting NPCs from IL-1β-induced damages through promoting cell viability, inhibiting cell senescence and apoptosis, increasing ECM production, and decreasing ECM degradation. MAPK signaling pathway may be involved.

The translational poteintial of this article

This study provides in vitro experimental data support for the pharmacological effects of kaempferol in treating IDD, and lays a solid experimental foundation for its future clinical application in IDD treatment.

Physalin A alleviates intervertebral disc degeneration via anti-inflammatory and anti-fibrotic effects

Background

The incidence of intervertebral disc degeneration (IVDD) is a common degenerative disease with inflammation, decreased autophagy, and progression of fibrosis as its possible pathogenesis. Physalin A (PA) is a widely studied anti-inflammatory drug. However, its therapeutic effects on IVDD remain unexplored. Therefore, we aimed to explore the therapeutic potential of PA in IVDD progression.

Materials and methods

In vivo, we investigated PA bioactivity using a puncture-induced IVDD rat model. IVDD signals and height changes were detected using X-ray, micro-CT, and MRI, and structural and molecular lesions using histological staining and immunohistochemistry of intervertebral disc sections. In vivo, interleukin-1 beta (IL-1β) and TGF-β1 were employed to establish inflammation fibrotic nucleus pulposus (NP) cells. The PA effect duration, concentration, influence pathways, and pathological changes in IVDD treatment were elucidated using western blotting, real-time PCR, and immunofluorescence.

Results

PA exerted significant effects on IVDD remission due to anti-inflammation, fibrosis reduction, and autophagy enhancement. In vitro, PA improved inflammation by blocking the NF-κB and MAPK pathways, whereas it promoted autophagy via the PI3K/AKT/mTOR pathway and affected fibrotic progression by regulating the SMAD2/3 pathway. Moreover, PA improved the disc degeneration process in IVDD model.

Conclusions

PA exhibited significant anti-inflammatory and anti-fibrotic effects and improved autophagy in vivo and in vitro IVDD models, thus effectively relieving IVDD progression, indicating it is a promising agent for IVDD treatment.

The translational potential of this article

This study successfully reveals that PA, a natural bioactive withanolide, effectively relieved IVDD progression via inflammation inhibition, fibrosis reduction, and autophagy enhancement, indicating it is a promising agent for IVDD treatment.

Maltol ameliorates intervertebral disc degeneration through inhibiting PI3K/AKT/NF-κB pathway and regulating NLRP3 inflammasome-mediated pyroptosis

OBJECTIVES

As one of the major causes of low back pain, intervertebral disc degeneration (IDD) has caused a huge problem for humans. Increasing evidence indicates that NLRP3 inflammasome-mediated pyroptosis of NP cells displays an important role in the progression of IDD. Maltol (MA) is a flavoring agent extracted from red ginseng. Due to its anti-inflammatory and antioxidant effects, MA has been widely considered by researchers. Therefore, we hypothesized that MA may be a potential IVD protective agent by regulating NP cells and their surrounding microenvironment.

METHODS

In vitro, qRT-PCR, and Western blot were used to explore the effect of MA on the transcription and protein expression of the anabolic protein (ADAMTS5, MMP3, MMP9) catabolic protein (Aggrecan), and pro-inflammatory factor (iNOS COX-2). Next, the effects of MA on PI3K/AKT/NF-κB pathway and pyroptosis pathway were analyzed by Western blot and immunofluorescence. Molecular docking was used to investigate the relationship between PI3K and MA. Moreover, ELISA was also used to detect the effects of MA on inflammatory factors (TNF-α, PGE2, IL-1β, and IL-18). In vivo, the effects of MA on the vertebral structure of IDD mice were studied by HE and SO staining and the effects of MA on ECM and PI3K/AKT/NF-κB and pyroptosis pathway of IDD mice were studied by immunohistochemical staining.

RESULTS

MA can ameliorate intervertebral disc degeneration in vivo and in vitro. Specifically, the molecular docking results showed that the binding degree of MA and PI3K was significant. Second, in vitro studies showed that MA inhibited the degradation of ECM and inflammatory response by inhibiting the PI3K/AKT/NF-κB pathway and the pyroptosis mediated by NLRP3 inflammasome, which increased the expression of anabolic proteins, decreased the expression of catabolic proteins, and decreased the secretion of inflammatory mediators such as IL-18 and IL-1β. In addition, according to the study results of the mouse lumbar instability model, MA also improved the tissue disorder and degradation of the intervertebral disc, reduced the loss of proteoglycan and glycosaminoglycan, and inhibited intervertebral disc inflammation, indicating that MA has a protective effect on the intervertebral disc to intervertebral disc in mice.

CONCLUSIONS

Our results suggest that MA slowed IDD development through the PI3K/AKT/NF-κB signaling pathway and NLRP3 inflammasome-mediated pyroptosis, indicating that MA appeared to be a viable medication for IDD treatment.

Ginsenoside Rg1 inhibits nucleus pulposus cell apoptosis, inflammation and extracellular matrix degradation via the YAP1/TAZ pathway in rats with intervertebral disc degeneration

PURPOSE

Intervertebral disc degeneration (IDD) is one of the main causes of low back pain, which not only affects patients' life quality, but also places a great burden on the public health system. Recently, ginsenoside Rg1 has been found to act in IDD; however, the mechanism is still unclear. The purpose of this study is to explore the function of ginsenoside Rg1 and its molecular mechanism in IDD.

METHODS

The rat model of IDD and nucleus pulposus (NP) experimental groups treated with ginsenoside Rg1 was constructed for investing the role of ginsenoside Rg1 in IDD rats. In the in vitro and in vivo study, the histological morphological changes, motor threshold (MT), inflammatory factors, oxidative stress, apoptosis and expression of the YAP1/TAZ signaling pathway-related proteins of the intervertebral discs (IVD) were measured by histological staining, mechanical and thermal stimulation, ELISA, qRT-PCR, flow cytometry, and western blot, respectively.

RESULTS

Ginsenoside Rg1 significantly increased the threshold for mechanical and thermal stimulation and alleviated histological changes in IDD rats. Ginsenoside Rg1 had a significant inhibitory effect on the secretion level of inflammatory factors, redox activity, extracellular matrix (ECM) degradation in IVD tissue and NP cells, and apoptosis in NP cells. Further investigation revealed that ginsenoside Rg1 significantly inhibited the expression of YAP1/TAZ signaling pathway-related proteins. Additionally, the above inhibitory effect of ginsenoside Rg1 on IDD progression was concentration-dependent, that is, the highest concentration of ginsenoside Rg1 was most effective.

CONCLUSION

Ginsenoside Rg1 inhibits IDD progression by suppressing the activation of YAP1/TAZ signaling pathway. This means that ginsenoside Rg1 has the potential to treat IDD.

Astragaloside IV attenuates IL-1β-induced intervertebral disc degeneration through inhibition of the NF-κB pathway

BACKGROUND

Intervertebral disc degeneration (IDD) is the main cause of low back pain. Patients with low back pain may experience significant socio-economic burdens and decreased productivity. Previous studies have shown that inflammation is one of the main causes of IDD. Astragaloside IV (AS IV), a traditional Chinese medicine, has been reported to have therapeutic effects on many inflammation-related diseases; however, the effectiveness of AS IV as the treatment for IDD has not been studied.

METHODS

Nucleus pulposus (NP) cells from patients with IDD were used for the experiments. Cell counting kit 8 (CCK8) was used to evaluate the effect of AS IV on the viability of NP cells (NPCs). To mimic IDD in vitro, NPCs were divided into the following groups: control group, interleukin 1β (IL-1β) group, and AS IV + IL-1β group. To analyse the effect of AS IV on IL-1β-induced IDD, Western blotting, RT-qPCR, flow cytometry, and immunofluorescence assays were performed. To evaluate the effect of AS IV in vivo, a rat model of puncture-induced IDD was established.

RESULTS

AS IV effectively alleviated IL-1β-induced inflammation, apoptosis, and extracellular matrix degeneration in NPCs. We also observed that AS IV decreased the IL-1β-induced phosphorylation of inhibitor of kappa B-alpha (p-IκBα) in the cytosol, and reduced nuclear translocation of NF-κB p65, indicating that AS IV inhibited the NF-κB pathway. Using the puncture-induced rat IDD model, our results showed that AS IV had a protective effect against the progression of IDD, suggesting that AS IV could alleviate IDD in vivo.

CONCLUSIONS

Our results demonstrated that AS IV effectively alleviated IDD in vivo and in vitro, indicating that it could be used as a therapeutic to treat IDD.

The role of nerve fibers and their neurotransmitters in regulating intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) has been the major contributor to chronic lower back pain (LBP). Abnormal apoptosis, senescence, and pyroptosis of IVD cells, extracellular matrix (ECM) degradation, and infiltration of immune cells are the major molecular alternations during IVDD. Changes at tissue level frequently occur at advanced IVD tissue. Ectopic ingrowth of nerves within inner annulus fibrosus (AF) and nucleus pulposus (NP) tissue has been considered as the primary cause for LBP. Innervation at IVD tissue mainly included sensory and sympathetic nerves, and many markers for these two types of nerves have been detected since 1940. In fact, in osteoarthritis (OA), beyond pain transmission, the direct regulation of neuropeptides on functions of chondrocytes have attracted researchers' great attention recently. Many physical and pathological similarities between joint and IVD have shed us the light on the neurogenic mechanism involved in IVDD. Here, an overview of the advances in the nervous system within IVD tissue will be performed, with a discussion on in the role of nerve fibers and their neurotransmitters in regulating IVDD. We hope this review can attract more research interest to address neuromodulation and IVDD itself, which will enhance our understanding of the contribution of neuromodulation to the structural changes within IVD tissue and inflammatory responses and will help identify novel therapeutic targets and enable the effective treatment of IVDD disease.

Pharmacological Effects of Resveratrol in Intervertebral Disc Degeneration: A Literature Review

Intervertebral disc degeneration (IDD) is a high incidence disease of musculoskeletal system that often leads to stenosis, instability, pain and even deformity of the spinal segments. IDD is an important cause of discogenic lower back pain and often leads to large economic burden to families and society. Currently, the treatment of IDD is aimed at alleviating symptoms rather than blocking or reversing pathological progression of the damaged intervertebral disc. Resveratrol (RSV) is a polyphenol phytoalexin first extracted from the Veratrum grandiflflorum O. Loes and can be found in various plants and red wine. Owing to the in-depth study of pharmacological mechanisms, the therapeutic potential of RSV in various diseases such as osteoarthritis, neurodegenerative diseases, cardiovascular diseases and diabetes have attracted the attention of many researchers. RSV has anti-apoptotic, anti-senescent, anti-inflammatory, anti-oxidative, and anabolic activities, which can prevent further degeneration of intervertebral disc cells and enhance their regeneration. With high safety and various biological functions, RSV might be a promising candidate for the treatment of IDD. This review summarizes the biological functions of RSV in the treatment of IDD and to facilitate further research.

Berberine Attenuates IL-1β-Induced Damage of Nucleus Pulposus Cells via Activating the AMPK/mTOR/Ulk1 Pathway

Intervertebral disc degeneration (IDD) is a chronic progressive condition mainly caused by excessive inflammatory cytokines. Berberine (BBR) exerts anti-inflammatory effect on diseases and protective effect against IDD. However, the mechanism is not uncertain. This study is aimed at investigating the molecular mechanism of BBR on IDD. Nucleus pulposus (NP) cells were treated with BBR at different concentrations. The IDD rat model was established by acupuncture. The effect of BBR on interleukin- (IL-) 1β-induced cell proliferation was measured by CCK-8 assay and BrdU staining. The role of BBR in IL-1β-induced apoptosis, autophagy repression, and extracellular matrix (ECM) degradation was measured by Annexin/PI staining, immunofluorescence, and immunoblot. The effect of BBR on IDD was investigated in rat. Our findings showed that BBR restored cell growth and attenuated apoptosis in IL-1β-induced NP cells. BBR also prevented the IL-1β-induced ECM degradation through regulating ECM-related enzymes and factors. Additionally, BBR significantly activated autophagy repressed by IL-1β. Autophagy stimulated by BBR was diminished by the inhibition of the AMPK/mTOR/Ulk1 signaling pathway. In vivo study also showed BBR attenuated intervertebral disc degeneration. BBR could attenuate NP cells apoptosis and ECM degradation induced by IL-1β through autophagy by the AMPK/mTOR/Ulk1 pathway. This study suggests BBR might function as an AMPK activator to alleviate IDD progression.

Arctigenin inhibits apoptosis, extracellular matrix degradation, and inflammation in human nucleus pulposus cells by up-regulating miR-483-3p

BACKGROUND

Arctigenin (ATG) is the active ingredient of the Chinese herbal medicine Arctium lappa, with anti-inflammatory and antioxidant effects. Excessive inflammation and cell apoptosis are important causes of intervertebral disc degeneration (IDD). Hence, this study probed into the possible role of ATG in IDD.

METHODS

Interleukin (IL)-1β (10 ng/ml) was adopted to induce human nucleus pulposus cells (HNPCs) as a cell model for IDD. The effects of different concentrations of ATG (0, 2, 5, 10, 20, 50 μmol/L) on the viability of HNPCs and effects of ATG (10, 50 μmol/L) on the viability of IL-1β-induced HNPCs were detected by cell counting kit-8 (CCK-8). After IL-1β-induced HNPCs were transfected with miR-483-3p inhibitor and/or treated with ATG, cell viability and apoptosis were determined by CCK-8 and flow cytometry; the expressions of miR-483-3p, extracellular matrix (ECM)-related genes, and inflammation-related genes were measured by quantitative real time polymerase chain reaction (qRT-PCR), and expressions of ECM/apoptosis/NF-κB pathway-related proteins were quantified by Western blot.

RESULTS

ATG had no significant effect on the viability of HNPCs but could promote the viability of IL-1β-induced HNPCs. ATG inhibited apoptosis, ECM degradation, inflammation, and activation of NF-κB pathway in HNPCs induced by IL-1β, but promoted the expression of miR-483-3p. MiR-483-3p inhibitor reversed the above-mentioned regulatory effects of ATG.

CONCLUSION

Arctigenin suppresses apoptosis, ECM degradation, inflammation, and NF-κB pathway activation in HNPCs by up-regulating miR-483-3p.

Alarmins S100A8/A9 promote intervertebral disc degeneration and inflammation-related pain in a rat model through toll-like receptor-4 and activation of the NF-κB signaling pathway

OBJECTIVE

The molecules released from cells undergoing necrosis are recognized as alarmins, and S100A8/9, a typical alarmin, is associated with several inflammation-related diseases. This study was to investigate the molecular role of S100A8/A9 on the process of intervertebral disc degeneration (IVDD) and inflammation-related pain.

METHODS

The expression pattern of S100A8/A9 in different degenerated human nucleus pulposus (NP) tissues were measured by Real-time quantitative reverse transcription PCR (RT-qPCR) and immunohistochemical (IHC). The effects of S100A8/A9 on matrix production were assessed by RT-qPCR, western blotting, and cell immunofluorescence. Involvement of TLR4 and NF-κB signaling pathways were studied by pharmachemical inhibitors and small interfering RNAs (siRNAs). The development of degenerative and pain features in the IVDD model were examed by IHC and pain-behavior testing.

RESULTS

The expression of S100A8/A9 was significantly elevated in severely degenerated human NP tissue with similar expression pattern of TNF-α. In NP cells, S100A8/A9 increased MMP-3/13, TNF-α, IL-6 expression and inhibited aggrecan and collagen II expression. RT-qPCR and western blotting showed that the regulatory effects of S100A8/A9 on IVD were TLR4 dependent. Pharmacological inhibition or siRNA knockdown of the NF-κB signaling attenuated S100A8/A9-induced upregulation of MMP-3/13, TNF-α and IL-6. In vivo, S100A9 inhibitor treatment inhibited disc-puncture induced IVDD and inflammation-related pain.

CONCLUSIONS

This study showed that S100A8/A9 bound to TLR4 and increased the expression of MMPs, TNF-α, and IL-6 through NF-κB signaling pathways in NP cells. Furthermore, S100A8/A9 inhibitor could prevent development of IVDD and inflammation-related pain in the rat model.

BRD4 Inhibition Suppresses Senescence and Apoptosis of Nucleus Pulposus Cells by Inducing Autophagy during Intervertebral Disc Degeneration: An In Vitro and In Vivo Study

Intervertebral disc degeneration (IDD) is the most common chronic skeletal muscle degeneration disease. Although the underlying mechanisms remain unclear, nucleus pulposus (NP) autophagy, senescence, and apoptosis are known to play a critical role in this process. Previous studies suggest that bromodomain-containing protein 4 (BRD4) promotes senescent and apoptotic effects in several age-related degenerative diseases. It is not known, however, if BRD4 inhibition is protective in IDD. In this study, we explored whether BRD4 influenced IDD. In human clinical specimens, the BRD4 level was markedly increased with the increasing Pfirrmann grade. At the cellular level, BRD4 inhibition prevented IL-1β-induced senescence and apoptosis of NP cells and activated autophagy via the AMPK/mTOR/ULK1 signaling pathway. Inhibition of autophagy by 3-methyladenine (3-MA) partially reversed the antisenescence and antiapoptotic effects of BRD4. In vivo, BRD4 inhibition attenuated IDD. Taken together, the results of this study showed that BRD4 inhibition reduced NP cell senescence and apoptosis by induced autophagy, which ultimately alleviated IDD. Therefore, BRD4 may serve as a novel potential therapeutic target for the treatment of IDD.

Oxidative Stress Aggravates Apoptosis of Nucleus Pulposus Cells through m6A Modification of MAT2A Pre-mRNA by METTL16

The process of intervertebral disc degeneration (IVDD) is complex, and its mechanism is considered multifactorial. Apoptosis of oxidative stressed nucleus pulposus cells (NPCs) should be a fundamental element in the pathogenesis of IVDD. In our pilot study, we found that the expression of MAT2A decreased, and METTL16 increased in the degenerative nucleus pulposus tissues. Previous studies have shown that the balance of splicing, maturation, and degradation of MAT2A pre-mRNA is regulated by METTL16 m⁶A modification. In the current study, we aimed to figure out whether this mechanism was involved in the aberrant apoptosis of NPCs and IVDD. Human NPCs were isolated and cultured under oxidative stress. An IVDD animal model was established. It showed that significantly higher METTL16 expression and lower MAT2A expression were seen in either the NPCs under oxidative stress or the degenerative discs of the animal model. MAT2A was inhibited with siRNA in vitro or cycloleucine in vivo. METTL16 was overexpressed with lentivirus in vitro or in vivo. Downregulation of MAT2A or upregulation of METTL16 aggravated nucleus pulposus cell apoptosis and disc disorganization. The balance of splicing, maturation, and degradation of MAT2A pre-mRNA was significantly inclined to degradation in the NPCs with the overexpression of METTL16. Increased apoptosis of NPCs under oxidative stress could be rescued by reducing the expression of METTL16 using siRNA with more maturation of MAT2A pre-mRNA. Collectively, oxidative stress aggravates apoptosis of NPCs through disrupting the balance of splicing, maturation, and degradation of MAT2A pre-mRNA, which is m⁶A modified by METTL16.

The Role of IL-17-Mediated Inflammatory Processes in the Pathogenesis of Intervertebral Disc Degeneration and Herniation: A Comprehensive Review

It has been reported that degenerated and herniated lumbar intervertebral discs show high expression of IL-17, suggesting that local immune reactions occur in patients with low back pain. While clinical sample analyses from different laboratories confirm this, it is not deeply not known on how IL-17 is induced in the pathology and their interactions with other inflammatory responses. This conscience review organizes current laboratory findings on this topic and present trajectory for full understanding on the role of IL-17 in pathology of intervertebral disc disease.

Cationic Polymer Brush-Modified Carbon Nanotube-Meditated eRNA LINC02569 Silencing Attenuates Nucleus Pulposus Degeneration by Blocking NF-κB Signaling Pathway and Alleviate Cell Senescence

Enhancer RNAs (eRNAs) are noncoding RNAs that synthesized at active enhancers. eRNAs have important regulatory characteristics and appear to be significant for maintenance of cell identity and information processing. Series of functional eRNAs have been identified as potential therapeutic targets for multiple diseases. Nevertheless, the role of eRNAs on intervertebral disc degeneration (IDD) is still unknown yet. Herein, we utilized the nucleus pulposus samples of patients and identified a key eRNA (LINC02569) with the Arraystar eRNA Microarray. LINC02569 mostly locates in nucleus and plays an important role in the progress of IDD by activating nuclear factor kappa-B (NF-κB) signaling pathway. We used a cationic polymer brush coated carbon nanotube (oCNT-pb)-based siRNA delivery platform that we previously designed, to transport LINC02569 siRNA (si-02569) to nucleus pulposus cells. The siRNA loaded oCNT-pb accumulated in nucleus pulposus cells with lower toxicity and higher transfection efficiency, compared with the traditional siRNA delivery system. Moreover, the results showed that the delivery of si-02569 significantly alleviated the inflammatory response in the nucleus pulposus cells via inhibiting P65 phosphorylation and preventing its transfer into the nucleus, and meanwhile alleviated cell senescence by decreasing the expression of P21. Altogether, our results highlight that eRNA (LINC02569) plays important role in the progression of IDD and could be a potential therapeutic target for alleviation of IDD.

Extracellular vesicles: a promising cell-free therapy for cartilage repair

Few effective therapies for cartilage repair have been found as cartilage has a low regenerative capacity. Extracellular vesicles (EVs), including exosomes, are produced by cells and contain bioactive components such as nucleic acids, proteins, lipids and other metabolites that have potential for treating cartilage injuries. Challenges like the difficulty in standardizing targeted therapy have prevented EVs from being used frequently as a treatment option. In this review we present current studies, mechanisms and delivery strategies of EVs. Additionally, we describe the challenges and future directions of EVs as therapeutic agents for cartilage repair.

Repairing cartilage damage is challenging due to the tissue’s low regenerative capacity. Extracellular vesicles (EVs) contain bioactive components that may be able to treat cartilage injuries. However, EV-based therapy is not widely used. This review summarizes the current state of knowledge regarding the use of EVs for cartilage repair, including the mechanisms, delivery strategies, challenges and future directions.

Causes of and Molecular Targets for the Treatment of Intervertebral Disc Degeneration: A Review

Intervertebral disc degeneration (IVDD) is a pathological condition that can lead to intractable back pain or secondary neurological deficits. There is no fundamental cure for this condition, and current treatments focus on alleviating symptoms indirectly. Numerous studies have been performed to date, and the major strategy for all treatments of IVDD is to prevent cell loss due to programmed or regulated cell death. Accumulating evidence suggests that several types of cell death other than apoptosis, including necroptosis, pyroptosis, and ferroptosis, are also involved in IVDD. In this study, we discuss the molecular pathway of each type of cell death and review the literature that has identified their role in IVDD. We also summarize the recent advances in targeted therapy at the RNA level, including RNA modulations through RNA interference and regulation of non-coding RNAs, for preventing cell death and subsequent IVDD. Therefore, we review the causes and possible therapeutic targets for RNA intervention and discuss the future direction of this research field.

Anti-degenerative effect of melatonin on intervertebral disc: protective contribution against inflammation, oxidative stress, apoptosis, and autophagy

Intervertebral disc (IVD) degeneration is a leading cause of lower back pain. Although the etiology of IVD degeneration (IVDD) is unclear, excessive oxidative stress, inflammation and apoptosis and disruption of autophagy play important role in the pathogenesis of IVDD. Therefore, finding a solution to mitigate these processes could stop or reduce the development of IVDD. Melatonin, a powerful antioxidant, plays an important role in regulating cartilage tissue hemostasis. Melatonin inhibits destruction of extracellular matrix (ECM) of disc. Melatonin preserves ECM contents including sox-9, aggrecan, and collagen II through inhibiting matrix degeneration enzymes such as MMP-13. These protective effects may be mediated by the inhibition of oxidative stress, inflammation and apoptosis, and regulation of autophagy in IVD cells.

The protective effects of dezocine on interleukin-1β-induced inflammation, oxidative stress and apoptosis of human nucleus pulposus cells and the possible mechanisms

Intervertebral disc degeneration (IDD) is a natural problem linked to the inflammation. We aimed to investigate the role of dezocine (DEZ) in the development of IDD. Human nucleus pulposus cells (HNPCs) induced by interleukin (IL)-1β was used as a cellular model of IDD. After treatment with DEZ, HNPCs viability was evaluated with a CCK-8 assay. Then, the levels of inflammatory factors, including IL-6 and tumor necrosis factor-α (TNF-α), and oxidative stress-related markers, including reactive oxygen species (ROS), malondialdehyde (MDA) and reduced glutathione (GSH), were tested by RT-qPCR or kits. TUNEL staining was employed to detect cell apoptosis and Western blot was used to determine the expression of proteins related to inflammation, oxidative stress, apoptosis, endoplasmic reticulum stress (ERS) and MAPK signaling. Afterward, PMA, a MAPK signaling pathway agonist, was adopted for exploring the regulatory effects of DEZ on MAPK pathway. Results indicated that DEZ enhanced cell viability of HNPCs after IL-1β exposure. DEZ alleviated the inflammation and oxidative stress, evidenced by decreased levels of IL-6, TNF-α, ROS, MDA, p-NF-κB p65, NF-κB p65 in nucleus, cox-2 and increased levels of NF-κB p65 in cytoplasm, GSH, SOD1 and SOD2. Moreover, DEZ notably inhibited IL-1β-induced apoptosis of HNPCs. Furthermore, DEZ suppressed the levels of ERS-related proteins. The levels of related proteins in MAPK signaling including p-P38 and p-ERK1/2 were remarkably reduced after DEZ administration. By contrast, PMA crippled the impacts of DEZ on inflammation, oxidative stress and apoptosis of HNPCs induced by IL-1β. Collectively, DEZ ameliorates IL-1β-induced HNPCs injury via inhibiting MAPK signaling.

LncRNA MIR155HG functions as a ceRNA of miR-223-3p to promote cell pyroptosis in human degenerative NP cells

Nucleus pulposus (NP) cell pyroptosis plays a critical role in the pathogenesis of intervertebral disk degeneration (IDD). MIR155 host gene (MIR155HG) is a long non-coding RNA with pro-inflammatory activity. However, very little is known about its role in NP cell pyroptosis. This study aimed to observe the impact of MIR155HG on cell pyroptosis and to explore the underlying mechanism in human degenerative NP cells. Our results demonstrated that MIR155HG expression was significantly increased in human degenerative NP tissue samples and showed a positive correlation with Pfirrmann score. Overexpression of MIR155HG through a lentiviral vector decreased miR-223-3p levels, up-regulated NLRP3 expression and induced cell pyroptosis in human degenerative NP cells. A ceRNA action mode was identified among MIR155HG, miR-223-3p, and NLRP3. The stimulatory effect of MIR155HG on human degenerative NP cell pyroptosis was significantly reversed by pretreatment with miR-223-3p mimic or NLRP3 siRNA. In summary, these data suggest that MIR155HG sponges miR-223-3p to promote NLRP3 expression, leading to induction of cell pyroptosis in human degenerative NP cells. Targeting MIR155HG could be a novel and promising strategy to slow down the progression of IDD.

The P2X7 purinergic receptor in intervertebral disc degeneration

Mechanisms involved in the development of intervertebral disc (IVD) degeneration are only partially known, thus making the implementation of effective therapies very difficult. In this study, we investigated P2X7 purinergic receptor (P2X7R), NLRP3 inflammasome, and interleukin (IL)-1β expression in IVD specimens at different stages of disease progression, and during the in vitro dedifferentiation process of the primary cells derived thereof. We found that P2X7R, NLRP3, and IL-1β expression was higher in the IVD samples at a more advanced stage of degeneration and in the expanded IVD cells in culture which partially recapitulated the in vivo degeneration process. In IVD cells, the P2X7R showed a striking nuclear localization, while NLRP3 was mainly cytoplasmic. Stimulation with the semiselective P2X7R agonist benzoyl ATP together with lipopolysaccharide treatment triggered P2X7R transfer to the cytoplasm and P2X7R/NLRP3 colocalization. Taken together, these findings support pathophysiological evidence that the degenerated disc is a highly inflamed microenvironment and highlight the P2X7R/NLRP3 axis as a suitable therapeutic target. The immunohistochemical analysis and the assessment of subcellular localization revealed a substantial expression of P2X7R also in normal disc tissue. This gives us the opportunity to contribute to the few studies performed in natively expressed human P2X7R so far, and to understand the possible physiological ATP-mediated P2X7R homeostasis signaling. Therefore, collectively, our findings may offer a new perspective and pave the way for the exploration of a role of P2X7R-mediated purinergic signaling in IVD metabolism that goes beyond its involvement in inflammation.

MAPK /ERK signaling pathway: A potential target for the treatment of intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a chronic skeletal muscle degenerative disease, which is considered the main cause of low back pain. It seriously affects the quality of life of patients and consequently brings a heavy economic burden to their families and the society. Although IDD is considered a natural process in degenerative lesions, it is mainly caused by aging, trauma, genetic susceptibility and other factors. It is closely related to changes in the tissue structure and function, including the progressive destruction of extracellular matrix, cell aging, cell death of the intervertebral disc (IVD), inflammation, and impairment of tissue biomechanical function. Currently, the treatment of IDD is aimed at alleviating symptoms rather than at targeting pathological changes in the IVD. Furthermore, the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathway is closely related to various pathological processes in IDD, and the activation of the MAPK/ERK pathway promotes the degradation of the IVD extracellular matrix, cell aging, apoptosis, and inflammatory responses. It also induces autophagy and oxidative stress that accelerate the IVD process. In our current review, we summarize the latest developments in the negative regulation of IDD after activation of the MAPK/ERK signaling pathway and emphasize on its influence on IDD. Targeting this pathway may become an attractive treatment strategy for IDD in the near future.

The potential role of melatonin in retarding intervertebral disc ageing and degeneration: A systematic review

Intervertebral disc degeneration (IDD) is a common degenerative disease of the musculoskeletal system that develops with age. It is regarded as the main cause of chronic low back pain in the elderly. IDD has various causes, including ageing, mechanical overloading, and nutritional deficiency. Melatonin is a pleiotropic indole hormone secreted by the pineal gland and plays an important role in resisting various degenerative diseases. The serum levels of melatonin decline with age and are reported to be negatively correlated with the symptomatic and histopathological scores of IDD. In vivo studies have shown that exogenous administration of melatonin could maintain the structural integrity of the intervertebral disc and inhibit the development of IDD. Mechanistically, by interacting with its membrane or intracellular receptors, melatonin can promote autophagic flux, scavenge free radicals, inhibit the release of pro-inflammatory factors, and block apoptotic pathways, thereby enhancing anti-stress abilities and matrix anabolism in different types of disc cells. Therefore, melatonin supplementation may be a promising therapeutic strategy for IDD. This review aimed to summarize the latest findings regarding the therapeutic potential of melatonin in IDD.

Natural Products of Pharmacology and Mechanisms in Nucleus Pulposus Cells and Intervertebral Disc Degeneration

Intervertebral disc degeneration (IDD) is one of the main causes of low back pain (LBP), which severely reduces the quality of life and imposes a heavy financial burden on the families of affected individuals. Current research suggests that IDD is a complex cell-mediated process. Inflammation, oxidative stress, mitochondrial dysfunction, abnormal mechanical load, telomere shortening, DNA damage, and nutrient deprivation contribute to intervertebral disc cell senescence and changes in matrix metabolism, ultimately causing IDD. Natural products are widespread, structurally diverse, afford unique advantages, and exhibit great potential in terms of IDD treatment. In recent years, increasing numbers of natural ingredients have been shown to inhibit the degeneration of nucleus pulposus cells through various modes of action. Here, we review the pharmacological effects of natural products on nucleus pulposus cells and the mechanisms involved. An improved understanding of how natural products target signalling pathways will aid the development of anti-IDD drugs. This review focuses on potential IDD drugs.

A comparative study of mesenchymal stem cell transplantation and NTG-101 molecular therapy to treat degenerative disc disease

Cellular replacement therapy using mesenchymal stem cells (MSCs) and/or the delivery of growth factors are at the forefront of minimally invasive biological treatment options for Degenerative Disc Disease (DDD). In this study, we compared the therapeutic potential of a novel drug candidate, NTG-101 to MSCs, including rat cartilage derived stem cells (rCDSCs), bone marrow stem cells (rBMSCs) and human Umbilical Cord Derived Mesenchymal Stem Cells (hUCMSCs) for the treatment of DDD. We induced DDD using a validated image-guided needle puncture injury in rat-tail IVDs. Ten weeks post-injury, animals were randomized and injected with MSCs, NTG-101 or vehicle. At the end of the study, histological analysis of the IVD-Nucleus Pulposus (NPs) injected with NTG-101 or rCDSCs showed a healthy or mild degenerative phenotype in comparison to vehicle controls. Immunohistochemical analysis revealed strong expression of aggrecan, collagen 2, brachyury and Oct4 in IVD-NPs injected with NTG-101. Our results also demonstrated suppression of inflammation induced p38 and NFκB resulting in inhibition of catabolic genes, but activation of Smad-2/3, Erk-1/2 and Akt-dependent signaling inducing anabolic genes in IVD-NP on treatment with NTG-101. In conclusion, a single injection of NTG-101 into the degenerative disc demonstrated superior benefits compared to stem cell transplantation.

The Role of Melatonin on NLRP3 Inflammasome Activation in Diseases

NLRP3 inflammasome is a part of the innate immune system and responsible for the rapid identification and eradication of pathogenic microbes, metabolic stress products, reactive oxygen species, and other exogenous agents. NLRP3 inflammasome is overactivated in several neurodegenerative, cardiac, pulmonary, and metabolic diseases. Therefore, suppression of inflammasome activation is of utmost clinical importance. Melatonin is a ubiquitous hormone mainly produced in the pineal gland with circadian rhythm regulatory, antioxidant, and immunomodulatory functions. Melatonin is a natural product and safer than most chemicals to use for medicinal purposes. Many in vitro and in vivo studies have proved that melatonin alleviates NLRP3 inflammasome activity via various intracellular signaling pathways. In this review, the effect of melatonin on the NLRP3 inflammasome in the context of diseases will be discussed.

Polymorphism of IL-1β rs16944(T/C) Associated with Serum Levels of IL-1β and Subsequent Stimulation of Extracellular Matrix Degradation Affects Intervertebral Disk Degeneration Susceptibility

Purpose

To investigate the association of polymorphism of IL-1β rs16944(T/C) with intervertebral disk degeneration (IDD), explore the possible mechanism and evaluate the predictive value of IL-1β for IDD.

Patients and Methods

A total of 196 consecutive patients with IDD were recruited, and 196 healthy controls were matched to these patients based on sex and age (±3 years). The polymorphisms of IL-1β rs16944(T/C), rs1143623(G/C), rs10490571(T/C) and rs2853550(A/G) were determined, and serum IL-1β, MMP-1, MMP-3, MMP-9 and a disintegrin-like and metalloproteinase with thrombospondin motif-4 (ADAMTS-4) levels were measured. Univariate analysis was performed with Student t-test or one-way ANOVA followed by post hoc and Chi-square test. Variables with two-sided P<0.10 were included in multivariate analysis, which employed a backward stepwise logistic regression model. Receiver operating characteristic (ROC) curve was used to evaluate the predictive value.

Results

Multivariate analysis showed that the polymorphism of IL-1β rs16944(T/C) was independently associated with IDD. The risk for IDD was significantly increased in TT and TC genotype compared with CC genotype, and the OR of TT genotype was higher than that of TC genotype. ANOVA analysis showed that serum concentration of IL-1β was highest in IL-1β rs16944 TT genotype, intermediate in TC genotype, and lowest in CC genotype. Similarly, serum concentrations of MMP-3 and ADAMTS-4 demonstrated the same tendency of TT > TC > CC genotype. Serum concentrations of MMP-1 and MMP-9 were higher in TT genotype than in TC and CC genotype. The area under curve (AUC) of IL-1β levels in predicting IDD was 0.788 (SE: 0.023, P=0.001, 95% CI: 0.742–0.834), and the predictive value was modest with a sensitivity of 77.0% and a specificity of 75%.

Conclusion

Polymorphism of IL-1β rs16944(T/C) affected IDD susceptibility through upregulation of serum levels of IL-1β and subsequent stimulation of ECM degradation. IL-1β levels could be applied in predicting IDD.

NFKB2 inhibits NRG1 transcription to affect nucleus pulposus cell degeneration and inflammation in intervertebral disc degeneration

Extracellular matrix degradation, reactive oxygen species (ROS) generation, and inflammation in nucleus pulposus (NP) cells contribute to the progression of intervertebral disc degeneration (IDD). NRGs (Neuregulins) play a vital role in the development of the nervous system. In the present study, we found that NRG1 was downregulated within degenerative intervertebral disc and NP tissues, according to both bioinformatics and experimental analyses. Within IL-1β-stimulated NP cells, we observed degenerative and inflammatory changes, including inhibited cell viability, promoted cell apoptosis and ROS accumulation, reduced collagen II and aggrecan proteins, elevated MMP-3/13 and ADAMTS-4/5 proteins, and upregulated IL-6 and TNF-α mRNA levels. Within IL-1β-stimulated NP cells, NRG1 expression was also downregulated. NRG1 overexpression attenuated, whereas NRG1 silencing aggravated IL-1β-induced degenerative and inflammatory changes. Moreover, NRG1 regulated ErbB2/3 activation, contributing to the NRG1 protective function in NP cells. NFKB2 directly targeted the promoter region of NRG1 and inhibited NRG1 expression. In IL-1β-stimulated NP cells, silencing NFKB2 attenuated, whereas silencing NRG1 aggravated the degenerative changes and inflammation; the effects of NFKB2 silencing were significantly reversed by NRG1 silencing. In conclusion, NRG1 expression is downregulated within degenerative NP tissue samples and IL-1β-stimulated NP cells. NRG1 might protect against IL-1β-induced degenerative changes and inflammation. The upregulated NFKB2 might be the reason of NRG1 downregulation in degenerative NP tissues.

Pathomechanism and Biomechanics of Degenerative Disc Disease: Features of Healthy and Degenerated Discs

The human intervertebral disc (IVD) is a complex organ composed of fibrous and cartilaginous connective tissues, and it serves as a boundary between 2 adjacent vertebrae. It provides a limited range of motion in the torso as well as stability during axial compression, rotation, and bending. Adult IVDs have poor innate healing potential due to low vascularity and cellularity. Degenerative disc disease (DDD) generally arises from the disruption of the homeostasis maintained by the structures of the IVD, and genetic and environmental factors can accelerate the progression of the disease. Impaired cell metabolism due to pH alteration and poor nutrition may lead to autophagy and disruption of the homeostasis within the IVD and thus plays a key role in DDD etiology. To develop regenerative therapies for degenerated discs, future studies must aim to restore both anatomical and biomechanical properties of the IVDs. The objective of this review is to give a detailed overview about anatomical, radiological, and biomechanical features of the IVDs as well as discuss the structural and functional changes that occur during the degeneration process.

Rhizoma drynariae total flavonoids inhibit the inflammatory response and matrix degeneration via MAPK pathway in a rat degenerative cervical intervertebral disc model

Rhizoma drynariae total flavonoids (RDTF) are extracted from Drynaria fortunei J. Sm (D. fortunei), which was a Chinese herb commonly used to treat fractures and bruises. Modern pharmacological studies indicate flavonoids have anti-inflammatory effect in clinical practice. However, its active ingredients and the mechanisms of action are far from clear. The present study aims to determine whether RDTF can protect against intervertebral disc degeneration in a rat cervical intervertebral disc model and investigate the associated molecular mechanisms. Sprague Dawley (SD) rats were randomized into five groups: control group (CG, n = 8), intervertebral disc degeneration group (NG, n = 8), low-dose RDTF-treated group (LG, n = 8), medium-dose RDTF-treated group (MG, n = 8), and high-dose RDTF-treated group (HG, n = 8). Hematoxylin and eosin (HE) staining, immunohistochemistry (IHC), immunofluorescence, ELISA, Western blot and quantitative real time PCR (qRT-PCR) assays were used to investigate inflammatory, catabolic factors and the latent regulatory mechanism of the effects of RDTF on intervertebral disc cells. HE staining showed disc degeneration in all groups except CG, and the function was restored after RDTF treatment. IHC, Western blot, qRT-PCR, immunofluorescence and ELISA results showed that RDTF prevented intervertebral disc degeneration by suppressing mitogen-activated protein kinase (MAPK) pathway, which reduced expression of intracellular matrix metalloproteinases (MMPs), such MMP3, MMP13, and inflammatory factors including interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α). Notably RDTF inhibited extracellular matrix (ECM) degeneration by increasing expression of aggrecan and collagen type II and preventing the upregulation of collagen type I and III. It suggests that RDTF has a potential therapeutic effect on cervical spondylosis.

Pro-Inflammatory and Neurotrophic Factor Responses of Cells Derived from Degenerative Human Intervertebral Discs to the Opportunistic Pathogen Cutibacterium acnes

Previously, we proposed the hypothesis that similarities in the inflammatory response observed in acne vulgaris and degenerative disc disease (DDD), especially the central role of interleukin (IL)-1β, may be further evidence of the role of the anaerobic bacterium Cutibacterium (previously Propionibacterium) acnes in the underlying aetiology of disc degeneration. To investigate this, we examined the upregulation of IL-1β, and other known IL-1β-induced inflammatory markers and neurotrophic factors, from nucleus-pulposus-derived disc cells infected in vitro with C. acnes for up to 48 h. Upon infection, significant upregulation of IL-1β, alongside IL-6, IL-8, chemokine (C-C motif) ligand 3 (CCL3), chemokine (C-C motif) ligand 4 (CCL4), nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), was observed with cells isolated from the degenerative discs of eight patients versus non-infected controls. Expression levels did, however, depend on gene target, multiplicity and period of infection and, notably, donor response. Pre-treatment of cells with clindamycin prior to infection significantly reduced the production of pro-inflammatory mediators. This study confirms that C. acnes can stimulate the expression of IL-1β and other host molecules previously associated with pathological changes in disc tissue, including neo-innervation. While still controversial, the role of C. acnes in DDD remains biologically credible, and its ability to cause disease likely reflects a combination of factors, particularly individualised response to infection.

Multiscale Regulation of the Intervertebral Disc: Achievements in Experimental, In Silico, and Regenerative Research

Intervertebral disc (IVD) degeneration is a major risk factor of low back pain. It is defined by a progressive loss of the IVD structure and functionality, leading to severe impairments with restricted treatment options due to the highly demanding mechanical exposure of the IVD. Degenerative changes in the IVD usually increase with age but at an accelerated rate in some individuals. To understand the initiation and progression of this disease, it is crucial to identify key top-down and bottom-up regulations' processes, across the cell, tissue, and organ levels, in health and disease. Owing to unremitting investigation of experimental research, the comprehension of detailed cell signaling pathways and their effect on matrix turnover significantly rose. Likewise, in silico research substantially contributed to a holistic understanding of spatiotemporal effects and complex, multifactorial interactions within the IVD. Together with important achievements in the research of biomaterials, manifold promising approaches for regenerative treatment options were presented over the last years. This review provides an integrative analysis of the current knowledge about (1) the multiscale function and regulation of the IVD in health and disease, (2) the possible regenerative strategies, and (3) the in silico models that shall eventually support the development of advanced therapies.

Overexpression of LMP-1 Decreases Apoptosis in Human Nucleus Pulposus Cells via Suppressing the NF-κB Signaling Pathway

Intervertebral disc degeneration (IDD) is a prevalent disease characterized by low back pain. Increasing extracellular matrix (ECM) synthesis and decreasing nucleus pulposus cell (NPC) apoptosis are promising strategies to recover degenerated NP. LIM mineralization protein- (LMP-) 1 has anti-inflammatory potential and is a promising gene target for the treatment of NP degeneration. In this study, we measured the expression of LMP-1 in the NP of patients. Then, we constructed LMP-1-overexpressing NPCs using lentiviral vectors and investigated the effects of LMP-1 on cell proliferation, apoptosis, and ECM synthesis in NPCs. The results showed that LMP-1 was highly expressed in the NP of patients. LMP-1 overexpression significantly increased proliferation and decreased apoptosis in NPCs. The expression of collagen II and sulfated glycosaminoglycan (sGAG) in NPCs was also upregulated after LMP-1 was overexpressed. Moreover, we demonstrated that LMP-1 decreased apoptosis of NPCs by inhibiting NF-κB signaling activation. These findings suggest that LMP-1 plays an essential role in mediating apoptosis in NPCs by regulating NF-κB signaling and can be used as a gene target for the treatment of IDD.

Cartilage intermediate layer protein affects the progression of intervertebral disc degeneration by regulating the extracellular microenvironment (Review)

Intervertebral disc degeneration (IDD), which is caused by multiple factors, affects the health of individuals and contributes to low back pain. The pathology of IDD is complicated, and changes in the extracellular microenvironment play an important role in promoting the process of degeneration. Cartilage intermediate layer protein (CILP) is a matrix protein that resides in the middle of human articular cartilage and is involved in numerous diseases that affect cartilage. However, there is no detailed review of the relationship between CILP and degenerative disc disease. Growing evidence has revealed the presence of CILP in the extracellular microenvironment of intervertebral discs (IVDs) and has suggested that there is a gradual increase in CILP in degenerative discs. Specifically, CILP plays an important role in regulating the metabolism of the extracellular matrix (ECM), an important component of the extracellular microenvironment. CILP can combine with transforming growth factor-β or insulin-like growth factor-1 to regulate the ECM synthesis of IVDs and influence the balance of ECM metabolism, which leads to changes in the extracellular microenvironment to promote the process of IDD. It may be possible to show the correlation of CILP with IDD and to target CILP to interfere with IDD. For this purpose, in the present study, the current knowledge on CILP was summarized and a detailed description of CILP in discs was provided.

Danshen Attenuates Intervertebral Disc Degeneration via Antioxidation in SD Rats

Objective

To investigate the effects of Danshen on the imaging and histological parameters, expression levels of ECM-associated proteins and inflammatory factors, and antioxidative activity in the degenerated intervertebral disc (IVD) of SD rats.

Methods

Sixty male rats were randomly divided into three groups (control, IDD, and Danshen IDD). Percutaneous needle puncture in Co8-9 intervertebral disc was conducted in all rats of the IDD and Danshen IDD groups to induce intervertebral disc degeneration (IDD). After operation, animals of the Danshen IDD group were administrated with Danshen granules (3 g/kg body weight ) by gavage once a day. Four weeks later, the coccygeal vertebrae were harvested and used for imaging (disc height and MR signal), histological, immunohistochemical, and biochemical [water content, glycosaminoglycans (GAG), superoxide dismutase (SOD2), glutathione (GSH), and malondialdehyde (MDA)] analyses.

Results

The puncture induced significant decreased IVD space and MR T2 signal at both 2 and 4 weeks, which were attenuated by Danshen treatment. The disc degeneration in the IDD group (HE and Safranin O-Fast Green histological staining was markedly more serious compared with that in the control group. Four weeks of Danshen treatment significantly alleviated this degeneration compared with the IDD group. Needle puncture resulted in the upregulation of IL-1β and TNF-α, MMP-3, and downregulation of COL2 and aggrecan in the IDD group. However, this change was significantly weakened by Danshen treatment. Significantly lower water and GAG content, as well as the SOD2 and GSH levels, in the IDD group were found compared with those in the control group. However, the above parameters of the Danshen IDD group were significantly higher than those of the IDD group. Danshen treatment significantly decreased the content of MDA which was increased by needle puncture in the IDD group.

Conclusion

Danshen can attenuate intervertebral disc degeneration in SD rats by suppressing the oxidation reaction.

The treatment of intervertebral disc degeneration using Traditional Chinese Medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Intervertebral disc degeneration (IDD) is one of the most common causes of chronic low back pain that spending a lot of workforces and financial resources, seriously affecting human physical and mental health. Clinically used drug treatments and surgical treatments cannot fundamentally relieve the disease and have a risk of recurrence. Traditional Chinese Medicine (TCM) has a history of more than a thousand years in the prevention and treatment of IDD. However, so far, there are few reviews on the treatment of IDD by TCM. Therefore, it is crucial and necessary to systematically mine the existing literature on the treatment of IDD with TCM. This paper strives to systematically describe the modern medicine and TCM theoretical research on IDD, progress in the treatment of IDD and focuses on the treatment of IDD by TCM, which would lay some theoretical foundation and provide new directions for future research.

MATERIALS AND METHODS

Information on clinical observations, animal experiments and relevant pharmacology data about the treatment of IDD were gathered from various sources including traditional Chinese books and Chinese Pharmacopoeia, scientific databases (Elsevier, PubMed, Science Direct, Baidu Scholar, CNKI, Spring Link, Web of Science) and from different professional websites.

RESULTS

This review mainly introduces the current research on the theoretical research on IDD, the combination principle of the TCM formula, and the underlying mechanism of the formula and active ingredients.

CONCLUSIONS

At present, domestic and foreign scholars have carried out a lot of research in different ways, such as the molecular mechanism and predisposing factors of IDD, which provides theoretical development and clinical practice significance for future research. TCM, as a multi-component and multi-targeted drug, can produce synergistic effects to exert its efficacy. Therefore, the development of TCM with more specific functions and practical data will not only become a significant trend in the world market but also has an irreplaceable role in the future treatment of IDD.

MicroRNA-25-3p therapy for intervertebral disc degeneration by targeting the IL-1β/ZIP8/MTF1 signaling pathway with a novel thermo-responsive vector

Background

MicroRNAs play important roles in intervertebral disc degeneration (IDD). The therapeutic effects of miRNA-25-3p on IDD and underlying mechanism are unclear.

Methods

Normal and degenerated nuclear pulposus (NP) tissue were collected. Primary NP cells were isolated and treated with different concentrations of interleukin-1β (IL-1β). IL-1β treated NP cells were interfered with miRNA-25-3p. Associated proteins IL-1β, ZIP8, MTF1, extracellular matrix (ECM) degrading enzymes MMP3, MMP13, ADAMTS5, ECM proteins type II collagen, aggrecan and MiRNA-25-3p were detected by western blotting or qRT-PCR method. Dual luciferase reporter assays were performed to determine potential targets MTF1 of miRNA-25-3p. In vitro miRNA-25-3p transfection efficiency of thermos-responsive vector was observed by fluorescence microscopy. Animal studies were conducted to observe the therapeutic effects of miRNA-25-3p mimic delivered by thermo-responsive vector.

Results

Compared with normal NP tissues, IL-1β, ZIP8 and MTF1 significantly increased and miRNA-25-3p significantly decreased in degenerated tissues. IL-1β promotes the expression of ZIP8 and nuclear translocation of MTF1 in NP cells. Ultimately, it promotes expression of ECM degrading enzymes and inhibits synthesis of ECM protein. MiRNA- 25-3p could inhibit the effects of IL-1β and the expression of ECM degrading enzymes, and recover the expression of ECM protein. Further investigation showed MTF1 was a target protein of miRNA-25-3p. The thermo-responsive vector could effectively deliver miRNA-25-3p into NP cells. Animal studies demonstrated miRNA-25-3p delivered by the thermo-responsive vector can delay progression of IDD

Conclusions

The thermo-responsive vector delivering miRNA-25-3p could delay the progression of IDD by inhibiting IL-1β-induced effects, and may be potential therapy for IDD in future.

Upregulation of Sirt1 by tyrosol suppresses apoptosis and inflammation and modulates extracellular matrix remodeling in interleukin-1β-stimulated human nucleus pulposus cells through activation of PI3K/Akt pathway

Intervertebral disc degeneration (IDD) is the major pathogenesis of lower back pain. Tyrosol is a polyphenolic compound that exhibits anti-oxidant, anti-apoptotic, and anti-inflammatory effects. Herein, we explored the effects and mechanisms of tyrosol on IDD progression in interleukin (IL)-1β-stimulated human nucleus pulposus cells (HNPCs). Cell viability and apoptosis were detected by CCK-8 and flow cytometry analysis, respectively. The production of tumor necrosis factor-α (TNF-α), IL-6, nitric oxide (NO), and prostaglandin E2 (PGE2) was examined to evaluate inflammation. The mRNA expression of matrix metalloproteinases (MMPs) (MMP-3/9/13), collagen type II, SRY-related high mobility group box 9 (SOX-9), and aggrecan was measured by qRT-PCR. Protein levels of silent information regulator 2 homolog 1 (Sirt1), phosphorylated protein kinase B (p-Akt), Akt, collagen type II, SOX-9, and aggrecan were determined by western blot. Results showed that tyrosol attenuated IL-1β-induced viability reduction, apoptosis, and caspase-3/7 activity in HNPCs. The increase in the production of TNF-α, IL-6, NO, and PGE2 in IL-1β-treated HNPCs was abolished by tyrosol treatment. Tyrosol treatment reversed IL-1β-induced upregulation of MMP-3, MMP-9, and MMP-13, and downregulation of collagen II, SOX-9, and aggrecan in HNPCs. Additionally, tyrosol treatment activated the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in IL-1β-stimulated HNPCs. Sirt1 was upregulated by tyrosol, and Sirt1 silencing inhibited Akt phosphorylation in HNPCs. Sirt1 knockdown attenuated the effects of tyrosol on IL-1β-induced apoptosis, inflammation, and ECM remodeling in HNPCs. In summary, upregulation of Sirt1 by tyrosol suppressed apoptosis and inflammation and regulated ECM remodeling in IL-1β-stimulated HNPCs through activation of PI3K/Akt pathway.