Disc cell senescence in intervertebral disc degeneration: Causes and molecular pathways

The mechanism of α2-macroglobulin against oxidative stress and promoting cell proliferation in intervertebral disc degeneration

Hui Liang and Yuan Wang. The mechanism of α2-macroglobulin against oxidative stress and promoting cell proliferation in intervertebral disc degeneration. Bioengineered. 2021 Nov. doi: 10.1080/21655979.2021.2011638.Since publication, significant concerns have been raised about the compliance with ethical policies for human research and the integrity of the data reported in the article.When approached for an explanation, the authors provided some original data but were not able to provide all the necessary supporting information. As verifying the validity of published work is core to the scholarly record's integrity, we are retracting the article. All authors listed in this publication have been informed.We have been informed in our decision-making by our editorial policies and the COPE guidelines.The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as 'Retracted.'

Biomolecular therapies for chronic discogenic low back pain: A narrative review

Chronic low back pain caused by intervertebral disc (IVD) degeneration, also termed chronic discogenic low back pain (CD-LBP), is one of the most prevalent musculoskeletal diseases. Degenerative processes in the IVD, such as inflammation and extra-cellular matrix breakdown, result in neurotrophin release. Local elevated neurotrophin levels will stimulate sprouting and innervation of sensory neurons. Furthermore, sprouted sensory nerves that are directly connected to adjacent dorsal root ganglia have shown to increase microglia activation, contributing to the maintenance and chronification of pain. Current pain treatments have shown to be insufficient or inadequate for long-term usage. Furthermore, most therapeutic approaches aimed to target the underlying pathogenesis of disc degeneration focus on repair and regeneration and neglect chronic pain. How biomolecular therapies influence the degenerative IVD environment, pain signaling cascades, and innervation and excitability of the sensory neurons often remains unclear. This review addresses the relatively underexplored area of chronic pain treatment for CD-LBP and summarizes effects of therapies aimed for CD-LBP with special emphasis on chronic pain. Approaches based on blocking pro-inflammatory mediators or neurotrophin activity have been shown to hamper neuronal ingrowth into the disc. Furthermore, the tissue regenerative and neuro inhibitory properties of extracellular matrix components or transplanted mesenchymal stem cells are potentially interesting biomolecular approaches to not only block IVD degeneration but also impede pain sensitization. At present, most biomolecular therapies are based on acute IVD degeneration models and thus do not reflect the real clinical chronic pain situation in CD-LBP patients. Future studies should aim at investigating the effects of therapeutic interventions applied in chronic degenerated discs containing established sensory nerve ingrowth. The in-depth understanding of the ramifications from biomolecular therapies on pain (chronification) pathways and pain relief in CD-LBP could help narrow the gap between the pre-clinical bench and clinical bedside for novel CD-LBP therapeutics and optimize pain treatment.

Discovering Potential Mechanisms of Intervertebral Disc Disease Using Systematic Mendelian Randomization of Human Circulating Immunocytomics

BACKGROUND

Although intervertebral disc degeneration (IVDD) is a critical factor in many spine-related diseases and has an extremely high prevalence in the aging population, the potential pathogenesis remains to be clarified entirely. Immune cells have been found to perform an essential function during the onset and progression of IVDD in recent years. Therefore, we explored the association between immune cell characteristics and IVDD through Mendelian randomization (MR) analysis and further delved into the mediating role of potential metabolites.

METHODS

Based on the MR analysis, the association of 731 immune cell phenotypes and 1400 metabolites on IVDD were assessed. Single nucleotide polymorphisms were closely associated the expression levels of immune cell characteristics and the concentrations of metabolites and have been used as instrumental variables for deducing them as risk factors or protective factors for IVDD. In addition, mediation analyses have been performed to identify potential metabolite mediators between immune cell characteristics and IVDD.

RESULTS

MR analysis identified 27 immune cell phenotypes and 79 metabolites significantly associated with IVDD. In addition, mediation analysis was performed by selecting the immune cell phenotype that most significantly increased the risk of IVDD - CD86 on monocytes. A total of 4 metabolite-mediated mediation relationships were revealed (3 b-hydroxy-5-cholenoic acid, X-22509, N-acetyl-L-glutamine, and N2-acetyl, N6, N6-dimethyllysine).

CONCLUSIONS

The findings of this analysis identified underlying association between immune cell phenotypes, metabolite, and IVDD that may serve as predictive and prognostic clinical biomarkers and benefit IVDD pathogenesis research.

Current Therapeutic Strategies of Intervertebral Disc Regenerative Medicine

Intervertebral disc degeneration (IDD) is one of the most frequent causes of low back pain. No treatment is currently available to delay the progression of IDD. Conservative treatment or surgical interventions is only used to target the symptoms of IDD rather than treat the underlying cause. Currently, numerous potential therapeutic strategies are available, including molecular therapy, gene therapy, and cell therapy. However, the hostile environment of degenerated discs is a major problem that has hindered the clinical applicability of such approaches. In this regard, the design of drugs using alternative delivery systems (macro-, micro-, and nano-sized particles) may resolve this problem. These can protect and deliver biomolecules along with helping to improve the therapeutic effect of drugs via concentrating, protecting, and prolonging their presence in the degenerated disc. This review summarizes the research progress of diagnosis and the current options for treating IDD.

Metformin prevents the onset and progression of intervertebral disc degeneration: New insights and potential mechanisms (Review)

Metformin has been the go‑to medical treatment for addressing type 2 diabetes mellitus (T2DM) as a frontline oral antidiabetic. Obesity, cancer and bone deterioration are linked to T2DM, which is considered a metabolic illness. Numerous diseases associated with T2DM, such as tumours, cardiovascular disease and bone deterioration, may be treated with metformin. Intervertebral disc degeneration (IVDD) is distinguished by degeneration of the spinal disc, accompanied by the gradual depletion of proteoglycans and water in the nucleus pulposus (NP) of the IVD, resulting in lower back pain. The therapeutic effect of metformin on IVDD has also attracted much attention. By stimulating AMP‑activated kinase, metformin could enhance autophagy and suppress cell senescence, apoptosis and inflammation, thus effectively delaying IVDD. The present review aimed to systematically explain the development of IVDD and mechanism of metformin in the treatment and prevention of IVDD to provide a reference for the clinical application of metformin as adjuvant therapy in the treatment of IVDD.

EZH2-H3K27me3-Mediated Epigenetic Silencing of DKK1 Induces Nucleus Pulposus Cell Pyroptosis in Intervertebral Disc Degeneration by Activating NLRP3 and NAIP/NLRC4

Nucleus pulposus (NP) cell pyroptosis is crucial for intervertebral disc degeneration (IDD). However, the precise mechanisms underlying pyroptosis in IDD remain elusive. Therefore, this study aimed to investigate how dickkopf-1 (DKK1) influences NP cell pyroptosis and delineate the regulatory mechanisms of IDD. Behavioral tests and histological examinations were conducted in rat IDD models to assess the effect of DKK1 on the structure and function of intervertebral discs. Detected pyroptosis levels using Hoechst 33,342/propidium iodide (PI) double staining, and determined pyroptosis-related protein expression via western blotting. The cellular mechanisms of DKK1 in pyroptosis were explored in interleukin (IL)-1β-induced NP cells transfected with or without DKK1 overexpression plasmids (oe-DKK1). In addition, IL-1β-treated NP cells transfected with sh-EZH2 and/or sh-DKK1 were utilized to clarify the interplay between the enhancer of zeste homologue 2 (EZH2) and DKK1 in pyroptosis. Additionally, the epigenetic regulation of DKK1 by EZH2 was explored in NP cells treated with the EZH2 inhibitors GSK126/DZNep. DKK1 expression decreased in IDD rats. Transfection with oe-DKK1 reduced pro-inflammatory factors and extracellular matrix markers in IDD rats. In IL-1β-induced NP cells, DKK1 overexpression suppressed pyroptosis and inhibited the NLRP3 and NAIP/NLRC4 inflammasome activation. EZH2 knockdown increased DKK1 expression and reduced pyroptosis-related proteins. Conversely, DKK1 downregulation reversed the inhibitory effects of EZH2 knockdown on pyroptosis. Furthermore, EZH2 suppressed DKK1 expression via H3K27 methylation at the DKK1 promoter. EZH2 negatively regulates DKK1 expression via H3K27me3 methylation, promoting NP cell pyroptosis in IDD patients. This regulatory effect involves the activation of NLRP3 and NAIP/NLRC4 inflammasomes.

TNFR1-mediated senescence and lack of TNFR2-signaling limit human intervertebral disc cell repair in back pain conditions

Poor intervertebral disc (IVD) healing causes IVD degeneration (IVDD) and progression to herniation and back pain. This study identified distinct roles of TNFα-receptors (TNFRs) in contributing to poor healing in painful IVDD. We first isolated IVDD tissue of back pain subjects and determined the complex pro-inflammatory mixture contained many chemokines for recruiting inflammatory cells. Single-cell RNA-sequencing of human IVDD tissues revealed these pro-inflammatory cytokines were dominantly expressed by a small macrophage-population. Human annulus fibrosus (hAF) cells treated with IVDD-conditioned media (CM) underwent senescence with greatly reduced metabolic rates and limited inflammatory responses. TNFR1 inhibition partially restored hAF cell metabolism sufficiently to enable a robust chemokine and cytokine response to CM. We showed that the pro-reparative TNFR2 was very limited on hIVD cell membranes so that TNFR2 inhibition with blocking antibodies or activation using Atsttrin had no effect on hAF cells with CM challenge. However, TNFR2 was expressed in high levels on macrophages identified in scRNA-seq analyses, suggesting their role in repair responses. Results therefore point to therapeutic strategies for painful IVDD involving immunomodulation of TNFR1 signaling in IVD cells to enhance metabolism and enable a more robust inflammatory response including recruitment or delivery of TNFR2 expressing immune cells to enhance IVD repair.

Pip5k1γ promotes anabolism of nucleus pulposus cells and intervertebral disc homeostasis by activating CaMKII-Ampk pathway in aged mice

Degenerative disc disease (DDD) represents a significant global health challenge, yet its underlying molecular mechanisms remain elusive. This study aimed to investigate the role of type 1 phosphatidylinositol 4-phosphate 5-kinase (Pip5k1) in intervertebral disc (IVD) homeostasis and disease. All three Pip5k1 isoforms, namely Pip5k1α, Pip5k1β, and Pip5k1γ, were detectable in mouse and human IVD tissues, with Pip5k1γ displaying a highest expression in nucleus pulposus (NP) cells. The expression of Pip5k1γ was significantly down-regulated in the NP cells of aged mice and patients with severe DDD. To determine whether Pip5k1γ expression is required for disc homeostasis, we generated a Pip5k1γfl/fl; AggrecanCreERT2 mouse model for the conditional knockout of the Pip5k1γ gene in aggrecan-expressing IVD cells. Our findings revealed that the conditional deletion of Pip5k1γ did not affect the disc structure or cellular composition in 5-month-old adult mice. However, in aged (15-month-old) mice, this deletion led to several severe degenerative disc defects, including decreased NP cellularity, spontaneous fibrosis and cleft formation, and a loss of the boundary between NP and annulus fibrosus. At the molecular level, the absence of Pip5k1γ reduced the anabolism of NP cells without markedly affecting their catabolic or anti-catabolic activities. Moreover, the loss of Pip5k1γ significantly dampened the activation of the protective Ampk pathway in NP cells, thereby accelerating NP cell senescence. Notably, Pip5k1γ deficiency blunted the effectiveness of metformin, a potent Ampk activator, in activating the Ampk pathway and mitigating lumbar spine instability (LSI)-induced disc lesions in mice. Overall, our study unveils a novel role for Pip5k1γ in promoting anabolism and maintaining disc homeostasis, suggesting it as a potential therapeutic target for DDD.

Genotoxic parameters of human degenerated intervertebral discs are linked to the pathogenesis of disc degeneration

BACKGROUND

Degenerative disc disease (DDD) is a prevalent disorder that brings great incapacity and morbidity to the world's population. Its pathophysiology is not fully understood. DNA damage can influence this process, but so far, there have been few studies to evaluate this topic and its true importance in DDD, as well as whether there is a relation between degeneration grade and DNA damage. The objective of this study is to evaluate the degree of damage to the DNA and the relation to the severity of DDD and measure its response to this insult compared to live/dead cell parameters and reactive oxygen species activity in human discs.

METHODS

An experimental study was performed with 15 patients with grade IV or V Pfirrmann classification who underwent spinal surgery. Five patients were operated on two levels, resulting in 20 samples that were submitted to the comet assay to measure DNA damage. Of these, six samples were submitted to flow cytometry, and apoptosis, necrosis, cell membrane integrity, intracellular esterase activity, reactive oxygen species (ROS), caspase 3 and mitochondrial membrane potential were evaluated.

RESULTS

All samples had DNA damage, and the average of index damage (ID) was 78.1 (SD±65.11) and frequency damage (FD) was 49.3% (SD±26.05%). There was no statistical difference between the Pfirrmann grades and genotoxic damage. Likewise, all samples that underwent flow cytometry showed apoptosis and ROS to many different degrees.

CONCLUSIONS

DNA damage occurs in high-grade degeneration of human discs and contributes to activation of the apoptosis pathway and ROS production that can accelerate disc degeneration.

Glucose depletion decreases cell viability without triggering degenerative changes in a physiological nucleus pulposus explant model

Although the etiology of intervertebral disc degeneration is still unresolved, the nutrient paucity resulting from its avascular nature is suspected of triggering degenerative processes in its core: the nucleus pulposus (NP). While severe hypoxia has no significant effects on NP cells, the impact of glucose depletion, such as found in degenerated discs (0.2-1 mM), is still uncertain. Using a pertinent ex-vivo model representative of the unique disc microenvironment, the present study aimed, therefore, at determining the effects of "degenerated" (0.3 mM) glucose levels on bovine NP explant homeostasis. The effects of glucose depletion were evaluated on NP cell viability, apoptosis, phenotype, metabolism, senescence, extracellular matrix anabolism and catabolism, and inflammatory mediator production using fluorescent staining, RT-qPCR, (immuno)histology, ELISA, biochemical, and enzymatic assays. Compared to the "healthy" (2 mM) glucose condition, exposure to the degenerated glucose condition led to a rapid and extensive decrease in NP cell viability associated with increased apoptosis. Although the aggrecan and collagen-II gene expression was also downregulated, NP cell phenotype, and senescence, matrix catabolism, and inflammatory mediator production were not, or only slightly, affected by glucose depletion. The present study provided evidence for glucose depletion as an essential player in NP cell viability but also suggested that other microenvironment factor(s) may be involved in triggering the typical shift of NP cell phenotype observed during disc degeneration. The present study contributes new information for better understanding disc degeneration at the cellular-molecular levels and thus helps to develop relevant therapeutical strategies to counteract it.

Progress in the study of molecular mechanisms of intervertebral disc degeneration

Degenerative intervertebral disc disease (IVDD) is one of the main spinal surgery, conditions, which markedly increases the incidence of low back pain and deteriorates the patient's quality of life, and it imposes significant social and economic burdens. The molecular pathology of IVDD is highly complex and multilateral however still not ompletely understood. New findings indicate that IVDD is closely associated with inflammation, oxidative stress, cell injury and extracellular matrix metabolismdysregulation. Symptomatic management is the main therapeutic approach adopted for IVDD, but it fails to address the basic pathological changes and the causes of the disease. However, research is still focusing on molecular aspects in terms of gene expression, growth factors and cell signaling pathways in an attempt to identify specific molecular targets for IVDD treatment. The paper summarizes the most recent achievements in molecularunderstanding of the pathogenesis of IVDD and gives evidence-based recommendations for clinical practice.

Inhibition of MAGL attenuates Intervertebral Disc Degeneration by Delaying nucleus pulposus senescence through STING

Intervertebral disc degeneration (IVDD) stands as the primary cause of low back pain (LBP). A significant contributor to IVDD is nucleus pulposus cell (NPC) senescence. However, the precise mechanisms underlying NPC senescence remain unclear. Monoacylglycerol lipase (MAGL) serves as the primary enzyme responsible for the hydrolysis of 2-arachidonoylglycerol (2-AG), breaking down monoglycerides into glycerol and fatty acids. It plays a crucial role in various pathological processes, including pain, inflammation, and oxidative stress. In this study, we utilized a lipopolysaccharide (LPS)-induced NPC senescence model and a rat acupuncture-induced IVDD model to investigate the role of MAGL in IVDD both in vitro and in vivo. Initially, our results showed that MAGL expression was increased 2.41-fold and 1.52-fold within NP tissues from IVDD patients and rats induced with acupuncture, respectively. This increase in MAGL expression was accompanied by elevated expression of p16INK4α. Following this, it was noted that the suppression of MAGL resulted in a notable decrease in the quantity of SA-β-gal-positive cells and hindered the manifestation of p16INK4α and the inflammatory factor IL-1β in NPCs. MAGL inhibition promotes type II collagen (Col-2) expression and inhibits matrix metalloproteinase 13 (MMP13), thereby restoring the balance of extracellular matrix (ECM) metabolism both in vitro and in vivo. A significant role for STING has also been demonstrated in the regulation of NPC senescence by MAGL. The expression of the STING protein was reduced by 57% upon the inhibition of MAGL. STING activation can replicate the effects of MAGL and substantially increase LPS-induced inflammation while accelerating the senescence of NPCs. These results strongly indicate that the inhibition of MAGL can significantly suppress nucleus pulposus senescence via its interaction with STING, consequently restoring the balance of ECM metabolism. This insight provides new perspectives for potential treatments for IVDD.

M6A methylation-regulated autophagy may be a new therapeutic target for intervertebral disc degeneration

Degeneration of intervertebral discs is considered one of the most important causes of low back pain and disability. The intervertebral disc (IVD) is characterized by its susceptibility to various stressors that accelerate the senescence and apoptosis of nucleus pulposus cells, resulting in the loss of these cells and dysfunction of the intervertebral disc. Therefore, how to reduce the loss of nucleus pulposus cells under stress environment is the main problem in treating intervertebral disc degeneration. Autophagy is a kind of programmed cell death, which can provide energy by recycling substances in cells. It is considered to be an effective method to reduce the senescence and apoptosis of nucleus pulposus cells under stress. However, further research is needed on the mechanisms by which autophagy of nucleus pulposus cells is regulated under stress environments. M6A methylation, as the most extensive RNA modification in eukaryotic cells, participates in various cellular biological functions and is believed to be related to the regulation of autophagy under stress environments, may play a significant role in nucleus pulposus responding to stress. This article first summarizes the effects of various stressors on the death and autophagy of nucleus pulposus cells. Then, it summarizes the regulatory mechanism of m6A methylation on autophagy-related genes under stress and the role of these autophagy genes in nucleus pulposus cells. Finally, it proposes that the methylation modification of autophagy-related genes regulated by m6A may become a new treatment approach for intervertebral disc degeneration, providing new insights and ideas for the clinical treatment of intervertebral disc degeneration.

Role of Galectin-3 in intervertebral disc degeneration: an experimental study

BACKGROUND

This study investigated the role of Galectin-3 in the degeneration of intervertebral disc cartilage.

METHODS

The patients who underwent lumbar spine surgery due to degenerative disc disease were recruited and divided into Modic I, Modic II, and Modic III; groups. HE staining was used to detect the pathological changes in endplates. The changes of Galectin-3, MMP3, Aggrecan, CCL3, and Col II were detected by immunohistochemistry, RT-PCR, and Western blot. MTT and flow cytometry were used to detect cartilage endplate cell proliferation, cell cycle, and apoptosis.

RESULTS

With the progression of degeneration (from Modic I to III), the chondrocytes and density of the cartilage endplate of the intervertebral disc decreased, and the collagen arrangement of the cartilage endplate of the intervertebral disc was broken and calcified. Meanwhile, the expressions of Aggrecan, Col II, Galectin-3, Aggrecan, and CCL3 gradually decreased. After treatment with Galectin-3 inhibitor GB1107, the proliferation of rat cartilage end plate cells was significantly reduced (P < 0.05). GB1107 (25 µmol/L) also significantly promoted the apoptosis of cartilage endplate cells (P < 0.05). Moreover, the percentage of cartilage endplate cells in the G1 phase was significantly higher, while that in the G2 and S phases was significantly lower (P < 0.05). Additionally, the mRNA and protein expression levels of MMP3, CCL3, and Aggrecan in rat cartilage end plate cells were lower than those in the control group.

CONCLUSIONS

Galectin-3 decreases with the progression of the cartilage endplate degeneration of the intervertebral disc. Galectin-3 may affect intervertebral disc degeneration by regulating the degradation of the extracellular matrix.

Construction of a novel mRNA-miRNA-lncRNA/circRNA triple subnetwork associated with immunity and aging in intervertebral disc degeneration

OBJECTIVE

Intervertebral disk degeneration (IVDD) is one of the most common causes of low back pain. However, in the etiology of IVDD, the specific method by which nucleus pulposus (NP) cell senescence and the immune response induce disease is uncertain.

METHODS

Gene Expression Omnibus database was used to find differentially expressed genes (DEGs), differentially expressed miRNAs (DE miRNAs), differentially expressed lncRNAs (DE lncRNAs), and differentially expressed circRNAs (DE circRNAs). Functional enrichment analysis was performed through Enrichr database. Potential regulatory miRNAs, lncRNAs and circRNAs of mRNAs were predicted by ENCORI and circBank, respectively.

RESULTS

We identified 198 upregulated and 131 downregulated genes, 39 upregulated and 22 downregulated miRNAs, 2152 upregulated and 564 downregulated lncRNAs, and 352 upregulated and 279 downregulated circRNAs as DEGs, DE miRNAs, DE lncRNAs, DE circRNAs, respectively. Functional enrichment analysis revealed that they were significantly enriched in Toll-like receptor signaling route and the NF-kappa B signaling pathway. An mRNA-miRNA-lncRNA/circRNA network linked to the pathogenesis of NP cells in IVDD was constructed based on node degree and differential expression level. Eight immune-related DEGs (6 upregulated and 2 downregulated genes) and five aging-related DEGs (3 upregulated and 2 downregulated genes) were identified in the critical network.

CONCLUSION

We established a novel immune-related and aging-related triple regulatory network of mRNA-miRNA-lncRNA/circRNA ceRNA, among which all RNAs may be utilized as the pathogenesis biomarker of NP cells in IVDD.

Sirtuins in intervertebral disc degeneration: current understanding

BACKGROUND

Intervertebral disc degeneration (IVDD) is one of the etiologic factors of degenerative spinal diseases, which can lead to a variety of pathological spinal conditions such as disc herniation, spinal stenosis, and scoliosis. IVDD is a leading cause of lower back pain, the prevalence of which increases with age. Recently, Sirtuins/SIRTs and their related activators have received attention for their activity in the treatment of IVDD. In this paper, a comprehensive systematic review of the literature on the role of SIRTs and their activators on IVDD in recent years is presented. The molecular pathways involved in the regulation of IVDD by SIRTs are summarized, and the effects of SIRTs on senescence, inflammatory responses, oxidative stress, and mitochondrial dysfunction in myeloid cells are discussed with a view to suggesting possible solutions for the current treatment of IVDD.

PURPOSE

This paper focuses on the molecular mechanisms by which SIRTs and their activators act on IVDD.

METHODS

A literature search was conducted in Pubmed and Web of Science databases over a 13-year period from 2011 to 2024 for the terms "SIRT", "Sirtuin", "IVDD", "IDD", "IVD", "NP", "Intervertebral disc degeneration", "Intervertebral disc" and "Nucleus pulposus".

RESULTS

According to the results, SIRTs and a large number of activators showed positive effects against IVDD.SIRTs modulate autophagy, myeloid apoptosis, oxidative stress and extracellular matrix degradation. In addition, they attenuate inflammatory factor-induced disc damage and maintain homeostasis during disc degeneration. Several clinical studies have reported the protective effects of some SIRTs activators (e.g., resveratrol, melatonin, honokiol, and 1,4-dihydropyridine) against IVDD.

CONCLUSION

The fact that SIRTs and their activators play a hundred different roles in IVDD helps to better understand their potential to develop further treatments for IVDD.

NOVELTY

This review summarizes current information on the mechanisms of action of SIRTs in IVDD and the challenges and limitations of translating their basic research into therapy.

Bioinformatics-based discovery of intervertebral disc degeneration biomarkers and immune-inflammatory infiltrates

Background

Intervertebral disc degeneration (IVDD) is a common chronic disease in orthopedics, and its molecular mechanisms are still not well explained.

Aim

This study's objective was to bioinformatics-based discovery of IVDD biomarkers and immune-inflammatory infiltrates.

Materials and Methods

The IVDD illness gene collection was gathered from GeneCards, DisGeNet, and gene expression profiles were chosen from the extensive Gene Expression Omnibus database (GSE124272, GSE150408, and GSE153761). The STRING database was used to create a network of protein-protein interactions, while the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) databases were used for functional enrichment analysis. Using hub genes, the immune cell infiltration between IVDD patient samples and control tissues was examined. Finally, quantitative polymerase chain reaction and Western blot experiments were used to verify the expression of hub genes.

Results

A total of 27 differentially expressed hub genes were identified by bioinformatics. According to GO and KEGG analyses, hub genes were prominent in immunological responses, chemokine-mediated signaling pathways, and inflammatory responses, with the key signaling pathways engaged in cellular senescence, apoptosis, Th1 and Th2 cell differentiation, and Th17 cell differentiation. Immune cell infiltration research revealed that T cells, lymphocytes, B cells, and NK cells were decreased in IVDD patients while monocytes, neutrophils, and CD8 T cells were increased. The expression levels of the senescence hub genes SP1, VEGFA, IL-6, and the apoptosis key gene CASP3 were considerably greater in the IVDD model group than in the control group, according to in vitro validation.

Conclusion

In conclusion, the cellular senescence signaling pathway, the apoptosis signaling pathway, and associated hub genes play significant roles in the development and progression of IVDD, this finding may help direct future research on the senescence signaling route in IVDD.

Dynamics of N6-methyladenosine modification during aging and their potential roles in the degeneration of intervertebral disc

Background

The N6-methyladenosine (m6A) dynamics in the progression of intervertebral disc (IVD) aging remain largely unknown. This study aimed to explore the distribution and pattern of m6A modification in nucleus pulpous (NP) tissues of rats at different ages.

Methods

Histological staining and MRI were performed to evaluate the degeneration of IVD. The expression of m6A modifiers was analyzed using qRT-PCR and western blot. Subsequently, methylated RNA immunoprecipitation next generation sequencing and RNA-seq were conducted to identify differences in m6A methylome and transcriptome of NP tissues.

Results

Compared to 2-month-old rats, we found significant changes in the global m6A level and the expression of Mettl3 and FTO in NP tissues from 20-month-old rats. During the progression of NP aging, there were 1126 persistently differentially m6A peaks within 931 genes, and 51 persistently differentially expressed genes. GO and KEGG analyses showed that these m6A peaks and m6A modified genes were mainly engaged in the biological processes and pathways of intervertebral disc degermation (IDD), such as extracellular matrix metabolism, angiogenesis, inflammatory response, mTOR and AMPK signaling pathways. Meanwhile, conjoint analyses and Venn diagram revealed a total of 405 aging related genes contained significant methylation and expression levels in 20-month-old rats in contrast to 2-month-old and 10-month-old rats. Moreover, it was found that four aging related genes with hypermethylated modification including BUB1, CA12, Adamts1, and Adamts4 depicted differentially expressed at protein level, of which BUB1 and CA12 were decreased, while Adamts1 and Adamts4 were increased during the progression of NP aging.

Conclusion

Collectively, this study elucidated the distribution and pattern of m6A modification during the aging of IVD. Furthermore, the m6A modified genes were involved in the IDD related biological processes and pathways. These findings may provide novel insights into the mechanisms and therapies of IDD from the perspective of aging.

Network Pharmacology with Metabolomics Study to Reveal the Mechanisms of Bushen Huoxue Formula in Intervertebral Disc Degeneration Treatment

Background

Intervertebral disc degeneration (IVDD) is a pathophysiological process that leads to severe back pain or neurological deficits. The Bushen Huoxue Formula (BSHXF) is a traditional herbal remedy widely used to treat diseases related to IVDD. However, its pharmacological mechanism needs further exploration.

Objective

This study aimed to elucidate the mechanisms through which BSHXF treats IVDD-related diseases by integrating metabolomics with network pharmacology.

Methods

Network pharmacology was utilized to identify potential targets of BSHXF against IVDD. Additionally, an animal model of needle puncture-induced disc degeneration was established to assess the effect of BSHXF. Mice were randomly assigned to the sham group, model group, and BSHXF group. Various techniques, including PCR, CCK-8 assay, MRI, histological examinations, and immunohistochemical analyses, were employed to evaluate degenerative and oxidative stress conditions in mouse disc tissue and cultured nucleus pulposus (NP) cells. UHPLC-HRMS/MS was used to differential distinct metabolites in the disc tissue from different groups, and MetaboAnalyst 5.0 was employed to enrich the metabolic pathways.

Results

Through network pharmacology, 15 core proteins were identified through protein-protein interaction (PPI) network construction. Functional enrichment analysis highlighted the critical role of BSHXF in addressing IVDD by influencing the response to oxidative stress. Furthermore, experimental evidence demonstrated that BSHXF significantly improved the pathological progression of IVDD and increased oxidative stress markers SOD-1 and GPX1, both in the disc degeneration model and cultured NP cells. Metabolomics identified differential metabolites among the three groups, revealing 15 metabolic pathways between the sham and model groups, and 13 metabolic pathways enriched between the model and BSHXF groups.

Conclusion

This study, integrating network pharmacology and metabolomics, suggests that BSHXF can alleviate IVDD progression by modulating oxidative stress. Key metabolic pathways associated with BSHXF-mediated reduction of oxidative stress include the citrate cycle, cysteine and methionine metabolism, alanine, aspartate and glutamate metabolism, glycine, serine and threonine metabolism, D-glutamine and D-glutamate metabolism, glutathione metabolism, and tryptophan metabolism. While this research demonstrates the therapeutic potential of BSHXF in reducing oxidative stress levels in IVDD, further research is needed to thoroughly understand its underlying mechanisms.

SEPHS1 attenuates intervertebral disc degeneration by delaying nucleus pulposus cell senescence through the Hippo-Yap/Taz pathway

Nucleus pulposus cell (NPC) senescence is a major cause of intervertebral disc degeneration (IVDD). Oxidative stress and reactive oxygen species (ROS) play critical roles in regulating cell senescence. Selenophosphate synthetase 1 (SEPHS1) was reported to play an important role in mitigating oxidative stress in an osteoarthritis (OA) model by reducing the production of ROS, thereby, delaying the occurrence and development of osteoarthritis. In this study, we explored the, hitherto unknown, role of SEPHS1 in IVDD in vitro and in vivo using an interleukin-1β (IL-1β)-induced NPC senescence model and a rat needle puncture IVDD model, respectively. SEPHS1 delayed NPC senescence in vitro by reducing ROS production. Age-related dysfunction was also ameliorated by the overexpression of SEPHS1 and inhibition of the Hippo-Yap/Taz signaling pathway. In vivo experiments revealed that the overexpression of SEPHS1 and inhibition of Hippo-Yap/Taz alleviated IVDD in rats. Moreover, a selenium (Se)-deficient diet and lack of SEPHS1 synergistically aggravated IVDD progression. Taken together, our results demonstrate that SEPHS1 plays a significant role in NPC senescence. Overexpression of SEPHS1 and inhibition of Hippo-Yap/Taz can delay NPC senescence, restore the balance of extracellular matrix metabolism, and attenuate IVDD. SEPHS1 could be a promising therapeutic target for IVDD.NEW & NOTEWORTHY Selenophosphate synthetase 1 (SEPHS1) deficiency leads to an increase in reactive oxygen species levels and in the subsequent activation of the Hippo-Yap/Taz signaling pathway. In the rat model of intervertebral disc degeneration (IVDD), overexpression of SEPHS1 and inhibition of Hippo-YAP/Taz mitigated the progression of disc degeneration indicating the involvement of SEPHS1 in IVDD. SEPHS1 is a promising therapeutic target for IVDD.

Bardoxolone methyl breaks the vicious cycle between M1 macrophages and senescent nucleus pulposus cells through the Nrf2/STING/NF-κB pathway

Intervertebral disc (IVD) degeneration (IDD), an age-related degenerative disease, is accompanied by the accumulation of senescent nucleus pulposus (NP) cells and extracellular matrix (ECM) degradation. The current study aims to clarify the role of M1 macrophages in the senescence of NP cells, and further explores whether bardoxolone methyl (CDDO-Me) can alleviate the pathological changes induced by M1 macrophages and relieve IDD. On the one hand, conditioned medium (CM) of M1 macrophages (M1CM) triggered senescence of NP cells and ECM degradation in a time-dependent manner. On the other hand, CM of senescent NP cells (S-NPCM) was collected to treat macrophages and we found that S-NPCM promoted the migration and M1-polarization of macrophages. However, both of the above effects can be partially blocked by CDDO-Me. We further explored the mechanism and found that M1CM promoted the expression level of STING and nuclear translocation of P65 in NP cells, while being restrained by CDDO-Me and STING inhibitor H151. In addition, the employment of Nrf2 inhibitor ML385 facilitated the expression level of STING and nuclear translocation of P65, thereby blocking the effects of CDDO-Me on suppressing senescence of NP cells and ECM degradation. In vivo, the injection of CDDO-Me into the disc decreased the infiltration of M1 macrophages and ameliorated degenerative manifestations in the puncture-induced rat IDD model. In conclusion, CDDO-Me was proved to break the vicious cycle between M1 macrophages and senescent NP cells through the Nrf2/STING/NF-κB pathway, thereby attenuating the progression of IDD.

Unraveling the mechanisms of intervertebral disc degeneration: an exploration of the p38 MAPK signaling pathway

Intervertebral disc (IVD) degeneration (IDD) is a worldwide spinal degenerative disease. Low back pain (LBP) is frequently caused by a variety of conditions brought on by IDD, including IVD herniation and spinal stenosis, etc. These conditions bring substantial physical and psychological pressure and economic burden to patients. IDD is closely tied with the structural or functional changes of the IVD tissue and can be caused by various complex factors like senescence, genetics, and trauma. The IVD dysfunction and structural changes can result from extracellular matrix (ECM) degradation, differentiation, inflammation, oxidative stress, mechanical stress, and senescence of IVD cells. At present, the treatment of IDD is basically to alleviate the symptoms, but not from the pathophysiological changes of IVD. Interestingly, the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway is involved in many processes of IDD, including inflammation, ECM degradation, apoptosis, senescence, proliferation, oxidative stress, and autophagy. These activities in degenerated IVD tissue are closely relevant to the development trend of IDD. Hence, the p38 MAPK signaling pathway may be a fitting curative target for IDD. In order to better understand the pathophysiological alterations of the intervertebral disc tissue during IDD and offer potential paths for targeted treatments for intervertebral disc degeneration, this article reviews the purpose of the p38 MAPK signaling pathway in IDD.

DNMT3a-mediated methylation of PPARγ promote intervertebral disc degeneration by regulating the NF-κB pathway

Intervertebral disc degeneration (IVDD) is a common chronic musculoskeletal disease that causes chronic low back pain and imposes an immense financial strain on patients. The pathological mechanisms underlying IVDD have not been fully elucidated. The development of IVDD is closely associated with abnormal epigenetic changes, suggesting that IVDD progression may be controlled by epigenetic mechanisms. Consequently, this study aimed to investigate the role of epigenetic regulation, including DNA methyltransferase 3a (DNMT3a)-mediated methylation and peroxisome proliferator-activated receptor γ (PPARγ) inhibition, in IVDD development. The expression of DNMT3a and PPARγ in early and late IVDD of nucleus pulposus (NP) tissues was detected using immunohistochemistry and western blotting analyses. Cellularly, DNMT3a inhibition significantly inhibited IL-1β-induced apoptosis and extracellular matrix (ECM) degradation in rat NP cells. Pretreatment with T0070907, a specific inhibitor of PPARγ, significantly reversed the anti-apoptotic and ECM degradation effects of DNMT3a inhibition. Mechanistically, DNMT3a modified PPARγ promoter hypermethylation to activate the nuclear factor-κB (NF-κB) pathway. DNMT3a inhibition alleviated IVDD progression. Conclusively, the results of this study show that DNMT3a activates the NF-κB pathway by modifying PPARγ promoter hypermethylation to promote apoptosis and ECM degradation. Therefore, we believe that the ability of DNMT3a to mediate the PPARγ/NF-κB axis may provide new ideas for the potential pathogenesis of IVDD and may become an attractive target for the treatment of IVDD.

Emerging role and therapeutic implications of p53 in intervertebral disc degeneration

Lower back pain (LBP) is a common degenerative musculoskeletal disease that imposes a huge economic burden on both individuals and society. With the aggravation of social aging, the incidence of LBP has increased globally. Intervertebral disc degeneration (IDD) is the primary cause of LBP. Currently, IDD treatment strategies include physiotherapy, medication, and surgery; however, none can address the root cause by ending the degeneration of intervertebral discs (IVDs). However, in recent years, targeted therapy based on specific molecules has brought hope for treating IDD. The tumor suppressor gene p53 produces a transcription factor that regulates cell metabolism and survival. Recently, p53 was shown to play an important role in maintaining IVD microenvironment homeostasis by regulating IVD cell senescence, apoptosis, and metabolism by activating downstream target genes. This study reviews research progress regarding the potential role of p53 in IDD and discusses the challenges of targeting p53 in the treatment of IDD. This review will help to elucidate the pathogenesis of IDD and provide insights for the future development of precision treatments.

Leukoreduced PRP enhanced proliferation and ECM production yet inhibited senescence, inflammation, and multi-differentiation potential of AFSCs by downregulating HMGB1

BACKGROUND

This study assessed the role and potential mechanism of platelet-rich plasma (PRP) in the progression of intervertebral disk degeneration (IVDD).

METHODS

Annulus fibrosus (AF)-derived stem cells (AFSCs) from New Zealand white rabbits received the transfection with high mobility group box 1 (HMGB1) plasmids and the subsequent treatment with bleomycin, 10% leukoreduced PRP or leukoconcentrated PRP. Dying cells were indicated by immunocytochemistry analysis for senescence-associated β-galactosidase (SA-β-gal) staining. The proliferation of these cells was evaluated based on the population doubling time (PDT). The expressions of HMGB1, pro-aging and anti-aging molecules, extracellular matrix (ECM)-related catabolic/anabolic factors, and inflammatory genes at the molecular or transcriptional levels were quantified via Western blot or reverse transcription-quantitative PCR (RT-qPCR). Besides, the adipocytes, osteocytes, and chondrocytes were separately dyed by Oil Red O, Alizarin Red S, and Safranin O staining.

RESULTS

Bleomycin enhanced the senescent morphological changes and increased the PDT and the expressions of SA-β-gal, pro-aging molecules, ECM-related catabolic factors, inflammatory genes, and HMGB1 while suppressing the expressions of anti-aging and anabolic molecules. Leukoreduced PRP reversed the effects of bleomycin and inhibited the differentiation of AFSCs into adipocytes, osteocytes, and chondrocytes. Besides, HMGB1 overexpression offset the roles of leukoreduced PRP in AFSCs.

CONCLUSION

Leukoreduced PRP promotes cell proliferation and ECM production of AFSCs, while inhibiting their senescence, inflammation, and multi-differentiation potentials via downregulating HMGB1 expression.

Traditional Chinese Medicine formula Bu-Shen-Huo-Xue-Fang (BSHXF) protects nucleus pulposus cells against the inflammatory and oxidative stress-induced degenerative changes

Degeneration of the intervertebral disc is primarily caused by the loss of nucleus pulposus cells (NPCs) and extracellular matrix (ECM) (IDD). Bu-Shen-Huo-Xue-Fang (BSHXF), a traditional Chinese medicine decoction, has been used to treat IDD in clinical; nevertheless, the active components and underlying molecular mechanisms remain unknown. BSHXF improved IL-1β and H2O2 stimulation-induced injuries on NPCs by promoting cell viability, increasing ECM deposition, inhibiting cell senescence, and decreasing the levels of inflammatory factors. The active ingredients in BSHXF were identified by LC-MS/MS analysis; three active ingredients from the principal drugs, Aucubin, Tanshinol, and Tanshinone II A promoted NPC viability; and Aucubin and Tanshinol promoted NPC viability more. Aucubin and Tanshinol, respectively, improved H2O2 stimulation-induced injuries on NPCs by promoting cell viability, increasing ECM deposition, inhibiting cell senescence, and decreasing the levels of inflammatory factors. The activator of NF-κB and Wnt signaling pathways attenuated Aucubin and Tanshinol's protective effects by promoting ECM degradation and NPC senescence. Aucubin, Tanshinol, and Tanshinone II A were identified as the most potent compounds in BSHXF protection against degenerative changes in NPCs. The NF-κB and Wnt signaling pathways might be involved in the protective effects of Aucubin and Tanshinol against H2O2-induced degenerative changes.

Genetically predicted triglycerides mediate the relationship between type 2 diabetes Mellitus and intervertebral disc degeneration

BACKGROUND

To validate the causal relationship between type 2 diabetes mellitus (T2DM) and intervertebral disc degeneration (IVDD) and to identify and quantify the role of triglycerides (TGs) as potential mediators.

METHODS

A two-sample Mendelian randomization (MR) analyses of T2DM (61,714 cases and 1178 controls) and IVDD (20,001 cases and 164,682 controls) was performed using genome-wide association studies (GWAS). Moreover, two-step MR was employed to quantify the proportionate impact of TG-mediated T2DM on IVDD.

RESULTS

MR analysis showed that T2DM increased IVDD risk (OR: 1.0466, 95% CI 1.0049-1.0899, P = 0.0278). Reverse MR analyses demonstrated that IVDD does not affect T2DM risk (P = 0.1393). The proportion of T2DM mediated through TG was 11.4% (95% CI 5.5%-17.4%).

CONCLUSION

This work further validates the causality between T2DM and IVDD, with a part of the effect mediated by TG, but the greatest impacts of T2DM on IVDD remain unknown. Further studies are needed to identify other potential mediators.

Machine learning algorithm predicts fibrosis-related blood diagnosis markers of intervertebral disc degeneration

BACKGROUND

Intervertebral disc cell fibrosis has been established as a contributing factor to intervertebral disc degeneration (IDD). This study aimed to identify fibrosis-related diagnostic genes for patients with IDD.

METHODS

RNA-sequencing data was downloaded from Gene Expression Omnibus (GEO) database. The diagnostic genes was identified using Random forest based on the differentially expressed fibrosis-related genes (DE-FIGs) between IDD and control samples. The immune infiltration states in IDD and the regulatory network as well as potential drugs targeted diagnostic genes were investigated. Quantitative Real-Time PCR was conducted for gene expression valifation.

RESULTS

CEP120 and SPDL1 merged as diagnostic genes. Substantial variations were observed in the proportions of natural killer cells, neutrophils, and myeloid-derived suppressor cells between IDD and control samples. Further experiments indicated that AC144548.1 could regulate the expressions of SPDL1 and CEP120 by combininghsa-miR-5195-3p and hsa-miR-455-3p, respectively. Additionally, transcription factors FOXM1, PPARG, and ATF3 were identified as regulators of SPDL1 and CEP120 transcription. Notably, 56 drugs were predicted to target these genes. The down-regulation of SPDL1 and CEP120 was also validated.

CONCLUSION

This study identified two diagnostic genes associated with fibrosis in patients with IDD. Additionally, we elucidated their potential regulatory networks and identified target drugs, which offer a theoretical basis and reference for further study into fibrosis-related genes involved in IDD.

Multifunctional injectable hydrogels with controlled delivery of bioactive factors for efficient repair of intervertebral disc degeneration

Millions of people worldwide suffer from intervertebral disc degeneration (IVDD), which imposes a significant socioeconomic burden on society. There is an urgent clinical demand for more effective treatments for IVDD because conventional treatments can only alleviate the symptoms rather than preventing the progression of IVDD. Hydrogels, a class of elastic biomaterials with good biocompatibility, are promising candidates for intervertebral disc repair and regeneration. In recent years, various hydrogels have been investigated in vitro and in vivo for the repair of intervertebral discs, some of which are ready for clinical testing. This review summarizes the latest findings and developments in using bioactive factors-released bioactive injectable hydrogels for the repair and regeneration of intervertebral discs. It focuses on the analysis and summary of the use of multifunctional injectable hydrogels to delivery bioactive factors (cells, exosomes, growth factors, genes, drugs) for disc regeneration, providing guidance for future study. Finally, we discussed and analyzed the optimal timing for the application of controlled-release hydrogels in the treatment of IVDD to meet the high standards required for intervertebral disc regeneration and precision medicine.

Cellular senescence in skeletal disease: mechanisms and treatment

The musculoskeletal system supports the movement of the entire body and provides blood production while acting as an endocrine organ. With aging, the balance of bone homeostasis is disrupted, leading to bone loss and degenerative diseases, such as osteoporosis, osteoarthritis, and intervertebral disc degeneration. Skeletal diseases have a profound impact on the motor and cognitive abilities of the elderly, thus creating a major challenge for both global health and the economy. Cellular senescence is caused by various genotoxic stressors and results in permanent cell cycle arrest, which is considered to be the underlying mechanism of aging. During aging, senescent cells (SnCs) tend to aggregate in the bone and trigger chronic inflammation by releasing senescence-associated secretory phenotypic factors. Multiple signalling pathways are involved in regulating cellular senescence in bone and bone marrow microenvironments. Targeted SnCs alleviate age-related degenerative diseases. However, the association between senescence and age-related diseases remains unclear. This review summarises the fundamental role of senescence in age-related skeletal diseases, highlights the signalling pathways that mediate senescence, and discusses potential therapeutic strategies for targeting SnCs.

Progress in understanding the role of cGAS-STING pathway associated with programmed cell death in intervertebral disc degeneration

Nucleus pulposus (NP) inflammatory response can induce intervertebral disc degeneration (IVDD) by causing anabolic and catabolic disequilibrium of the extracellular matrix (ECM). This process is accompanied by the production of endogenous DNAs, then detectable by the DNA sensor cyclic GMP-AMP synthase (cGAS). cGAS recognizes these DNAs and activates the downstream adaptor protein, a stimulator of interferon genes (STING), initiating a cascade of inflammation responses through various cytokines. This evidence implies a crucial role of the cGAS-STING signaling pathway in IVDD. Additionally, it is suggested that this pathway could modulate IVDD progression by regulating apoptosis, autophagy, and pyroptosis. However, a detailed understanding of the role of cGAS-STING pathway in IVDD is still lacking. This review provides a comprehensive summary of recent advances in our understanding of the role of the cGAS-STING pathway in modulating inflammatory response in IVDD. We delve into the connection between the cGAS-STING axis and apoptosis, autophagy, and pyroptosis in IVDD. Furthermore, we discuss the therapeutic potential of targeting the cGAS-STING signaling pathway in IVDD treatment. Overall, this review aims to provide a foundation for future directions in IVDD treatment strategies.

Understanding Intervertebral Disc Degeneration: Background Factors and the Role of Initial Injury

The etiology of intervertebral disc degeneration (IVDD) is complex and multifactorial, and it is still not fully understood. A better understanding of the pathogenesis of IVDD will help to improve treatment regimens and avoid unnecessary surgical aggression. In order to summarize recent research data on IVDD pathogenesis, including genetic and immune factors, a literature review was conducted. The pathogenesis of IVDD is a complex multifactorial process without an evident starting point. There are extensive data on the role of the different genetic factors affecting the course of the disease, such as mutations in structural proteins and enzymes involved in the immune response. However, these factors alone are not sufficient for the development of the disease. Nevertheless, like mechanical damage, they can also be considered risk factors for IVDD. In conclusion, currently, there is no consensus on a single concept for the pathogenesis of IVDD. We consider the intervertebral disc autoimmune damage hypothesis to be the most promising hypothesis for clinicians, because it can be extrapolated to all populations and does not counteract other factors. The genetic factors currently known do not allow for building effective predictive models; however, they can be used to stratify the risks of individual populations.

Comparative study of outcomes between allograft intervertebral disc transplantation and anterior cervical discectomy and fusion: a retrospective cohort study at least 5 years of follow-up

PURPOSE

Adjacent segment degeneration (ASDeg) after anterior cervical discectomy and fusion (ACDF) seriously affects the long-term efficacy of the operation. Therefore, our team has done a lot of research on allograft intervertebral disc transplantation (AIDT) to prove its feasibility and safety. This study will compare the efficacy between AIDT and ACDF in the treatment of cervical spondylosis.

METHODS

All patients who received ACDF or AIDT in our hospital from 2000 to 2016 and followed up for at least 5 years were recruited and divided into ACDF and AIDT groups. The clinical outcomes including functional scores and radiological data of both groups were collected and compared preoperatively and postoperatively at 1 week, 3 months, 6 months, 12 months, 24 months, 60 months and last follow-up. Functional scores included Japanese Orthopedic Association score (JOA), Neck Disability Index (NDI), Visual Analog Scale of Neck (N-VAS) and Arms (A-VAS) pain, the Short Form Health Survey-36 (SF-36) and imaging dates including digital radiographs in the lateral, hyperextension and flexion positions to assess the stability, sagittal balance and mobility of the cervical spine and magnetic resonance imaging (MRI) scans to assess the degeneration of adjacent segment.

RESULTS

There were 68 patients with 25 in AIDT group and 43 in ACDF group. Satisfactory clinical results were obtained in both groups, but the long-term NDI score and N-VAS score in the AIDT group were better. The AIDT obtained the same stability and sagittal balance of the cervical spine as fusion surgery. The range of motion of adjacent segments can be restored to the preoperative level after transplantation, but this increases significantly after ACDF. There were significant differences in the superior adjacent segment range of motion (SROM) between two groups at 12 months (P = 0.039), 24 months (P = 0.035), 60 months (P = 0.039) and the last follow-up (P = 0.011). The inferior adjacent segment range of motion (IROM) and SROM had a similar trend in the two groups. The ratio value of the greyscale (RVG) of adjacent segments showed a downward trend. At the last follow-up, the RVG decreased more significantly in the ACDF group. At the last follow-up, there was a significant difference in the incidence of ASDeg between the two groups (P = 0.000). And the incidence of adjacent segment disease (ASDis) is 22.86% in the ACDF group.

CONCLUSION

The allograft intervertebral disc transplantation may be as an alternative technique to traditional anterior cervical discectomy and fusion for the management of cervical degenerative diseases. For the more, the results showed it would improve cervical kinematics and reduce the incidence of adjacent segment degeneration.

Knockdown of microRNA-96-5p resists oxidative stress-induced apoptosis in nucleus pulposus cells

BACKGROUND

Intervertebral disc degeneration (IVDD) often leads to low back pain, which severely affects people's quality of life. Oxidative stress (OS) can accelerate nucleus pulposus cell (NPCs) senescence and apoptosis. Exploring the mechanism underlying OS-induced apoptosis is of utmost importance to aid in the development of IVDD treatment.

METHODS

In the current study, we tested the function of microRNA-96-5p in H2O2-treated NPCs. Apoptosis and mitophagy-related proteins were examined by western blot. Reactive oxygen species (ROS) generation, mitochondrial membrane potential, and apoptosis of NPCs were evaluated by flow cytometry. A luciferase reporter assay was conducted to confirm the interaction between microRNA-96-5p and Forkhead Box Protein O1 (FOXO1).

RESULTS

H2O2 treatment enhanced apoptosis in NPCs and upregulated the microRNA-96-5p expression. It was shown that knockdown of microRNA-96-5p attenuated H2O2-induced OS and apoptosis. FOXO1 is a direct target of microRNA-96-5p, and knockdown of microRNA-96-5p enhanced PINK1/Parkin-mediated mitophagy by up-regulating FOXO1.

CONCLUSIONS

Collectively, knockdown of microRNA-96-5p enhanced PINK1/Parkin-mediated mitophagy by up-regulating FOXO1. Our results facilitate the understanding of the role of microRNA-96-5p in IVDD and the mechanism of H2O2-induced oxidative damage.

STING signaling in inflammaging: a new target against musculoskeletal diseases

Stimulator of Interferon Gene (STING) is a critical signaling linker protein that plays a crucial role in the intrinsic immune response, particularly in the cytoplasmic DNA-mediated immune response in both pathogens and hosts. It is also involved in various signaling processes in vivo. The musculoskeletal system provides humans with morphology, support, stability, and movement. However, its aging can result in various diseases and negatively impact people's lives. While many studies have reported that cellular aging is a leading cause of musculoskeletal disorders, it also offers insight into potential treatments. Under pathological conditions, senescent osteoblasts, chondrocytes, myeloid cells, and muscle fibers exhibit persistent senescence-associated secretory phenotype (SASP), metabolic disturbances, and cell cycle arrest, which are closely linked to abnormal STING activation. The accumulation of cytoplasmic DNA due to chromatin escape from the nucleus following DNA damage or telomere shortening activates the cGAS-STING signaling pathway. Moreover, STING activation is also linked to mitochondrial dysfunction, epigenetic modifications, and impaired cytoplasmic DNA degradation. STING activation upregulates SASP and autophagy directly and indirectly promotes cell cycle arrest. Thus, STING may be involved in the onset and development of various age-related musculoskeletal disorders and represents a potential therapeutic target. In recent years, many STING modulators have been developed and used in the study of musculoskeletal disorders. Therefore, this paper summarizes the effects of STING signaling on the musculoskeletal system at the molecular level and current understanding of the mechanisms of endogenous active ligand production and accumulation. We also discuss the relationship between some age-related musculoskeletal disorders and STING, as well as the current status of STING modulator development.

BSHXF-medicated serum combined with ADSCs regulates the TGF-β1/Smad pathway to repair oxidatively damaged NPCs and its component analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Lower back pain (LBP) is a common and frequent clinical condition, and intervertebral disc degeneration (IDD) is recognized as the leading cause of LBP, typically manifested by increased nucleus pulposus cell (NPC) senescence and death. In recent years, the treatment of IDD with stem cell injections has had great potential compared to surgical treatment. Combining the two may achieve better results, as BuShenHuoXueFang (BSHXF) is an herbal formula that improves the survival rate of transplanted stem cells and enhances their efficacy.

AIM OF THE STUDY

We aimed to qualitatively and quantitatively analyze BSHXF-medicated serum and investigate the molecular mechanism of BSHXF-mediated serum in promoting the differentiation of adipose mesenchymal stem cells (ADSCs) into NPCs and delaying the senescence of NPCs by regulating the TGF-β1/Smad pathway.

MATERIALS AND METHODS

In this study, an ultrahigh-performance liquid chromatography-quadrupole-time-of-flight mass spectrometer (UPLC-Q-TOF-MS) was used to establish a method for the analysis of rat serum samples to track the active components in vivo; the oxidative damage model of NPCs was induced by T-BHP, and a Transwell chamber was used to construct a coculture system of ADSCs and NPCs. Flow cytometry was used to determine the cell cycle; SA-β-Gal staining was used to assess cell senescence; ELISA was used to detect IL-1β, IL-6 inflammatory factors, CXCL-1, CXCL-3, CXCL-10 chemokines, and TGF-β1 in the supernatants of ADSCs and NPCs. WB was used to detect COL2A1, COL1A1, and Aggrecan in ADSCs to assess the manifestation of NP differentiation in ADSCs, and the WB method was used to detect COL2A1, COL1A1, Aggrecan, p16, p21, p53, and p-p53 protein expression in NPCs to reflect the cellular senescence status and to detect TGF-β1, Smad2, Smad3, p- Smad2, and p- Smad3 protein expression in NPCs to reflect the pathway condition.

RESULTS

We finally identified 70 blood components and their metabolites, including 38 prototypes, from the BSHXF-medicated serum. Compared with that in the nonmedicated serum group, the TGF-β1/Smad pathway was activated in the medicated serum group, ADSCs moved toward NPC characteristics, the number of NPCs in the S/G2M phase increased, the number of senescent NPCs decreased, IL-1β and IL-6 inflammatory factors in the Transwell decreased, CXCL-1, CXCL-3, and CXCL-10 chemokines decreased, and the expression of p16, p21, p53 and p-p53 proteins in NPCs was inhibited.

CONCLUSION

By regulating the TGF-β1/Smad pathway, BSHXF-medicated serum promoted ADSCs to NPCs, effectively alleviated the cycle blockage of NPCs after oxidative damage, encouraged the growth and proliferation of NPCs, delayed the aging of NPCs, improved the deteriorating microenvironment around NPCs, and repaired oxidatively damaged NPCs. The combination of BSHXF or its compounds with ADSCs has great potential for the treatment of IDD in the future.

Medical Prospect of Melatonin in the Intervertebral Disc Degeneration through Inhibiting M1-Type Macrophage Polarization via SIRT1/Notch Signaling Pathway

The study aims to explore the medical prospect of melatonin (MLT) and the underlying therapeutic mechanism of MLT-mediated macrophage (Mφ) polarization on the function of nucleus pulposus (NP) in intervertebral disc degeneration (IDD). RAW 264.7 Mφs were induced by lipopolysaccharide (LPS) to simulate Mφ polarization and the inflammatory reaction of Mφs with or without MLT were detected. Conditioned medium (CM) collected from these activated Mφs with or without MLT treatment were further used to incubate NP cells. The oxidative stress, inflammation and extracellular matrix (ECM) metabolism in NP cells were determined. Then, the changes in SIRT1/Notch signaling were detected. The agonist (SRT1720) and inhibitor (EX527) of SIRT1 were used to further explore the association among MLT. The interaction between SIRT1 and NICD was detected by immunoprecipitation (IP). Finally, puncture-induced rat IDD models were established and IDD degrees were clarified by X-ray, MRI, H&E staining and immunofluorescence (IF). The results of flow cytometry and inflammation detection indicated that LPS could induce M1-type Mφ polarization with pro-inflammatory properties. MLT significantly inhibited the aforementioned process and inhibited M1-type Mφ polarization, accompanied by the alleviation of inflammation. Compared with those without MLT, the levels of oxidative stress, pro-inflammatory cytokines and ECM catabolism in NP cells exposed to CM with MLT were markedly downregulated in a dose-dependent manner. The inhibition of SIRT1 and the enhancement of Notch were observed in activated Mφs and they can be reversed after MLT treatment. This prediction was further confirmed by using the SRT1720 and EX527 to activate or inhibit the signaling. The interaction between SIRT1 and NICD was verified by IP. In vivo study, the results of MRI, Pfirrmann grade scores and H&E staining demonstrated the degree of disc degeneration was significantly lower in the MLT-treated groups when compared with the IDD control group. The IF data showed M1-type Mφ polarization decreased after MLT treatment. MLT could inhibit M1-type Mφ polarization and ameliorate the NP cell injury caused by inflammation in vitro and vivo, which is of great significance for the remission of IDD. The SIRT1/Notch signaling pathway is a promising target for MLT to mediate Mφ polarization.

Aging, cell senescence, the pathogenesis and targeted therapies of intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) refers to the aging and degenerative diseases of intervertebral disc components such as nucleus pulposus, annulus fibrosus, and cartilage endplate, and is the main cause of chronic low back pain. Over the past few years, many researchers around the world concerned that the degeneration of nucleus pulposus (NP) cells plays the main role in IVDD. The degeneration of NP cells is caused by a series of pathological processes, including oxidative stress, inflammatory response, apoptosis, abnormal proliferation, and autophagy. Interestingly, many studies have found a close relationship between the senescence of NP cells and the progression of NP degeneration. The classical aging pathways also have been confirmed to be involved in the pathological process of IVDD. Moreover, several anti-aging drugs have been used to treat IVDD by inhibiting NP cells senescence, such as proanthocyanidins, resveratrol and bone morphogenetic protein 2. Therefore, this article will systematically list and discuss aging, cell senescence, the pathogenesis and targeted therapies of IVDD, in order to provide new ideas for the treatment of IVDD in the future.

Embelin protects against apoptosis and inflammation by regulating PI3K/Akt signaling in IL-1β-stimulated human nucleus pulposus cells

Embelin is a natural benzoquinone compound that displays a beneficial effect in various inflammatory-related diseases. However, the effect of embelin on degeneration of intervertebral disc (IDD), a chronic inflammatory disorder, has not been reported. This study was attempted to explore the therapeutic action of embelin on IDD in vitro. Network pharmacology analysis was performed for evaluating the link between embelin and IDD. The human nucleus pulposus cells (NPCs) were stimulated with IL-1β to induce inflammation. Cell viability of NPCs was assessed by CCK-8 assay. Western blotting was conducted to detect the expression levels of PI3K, p-PI3K, Akt, p-Akt, cleaved caspase-3, caspase-3, Bax, Bcl-2, p65 and p-p65. Apoptotic deaths of NPCs were examined by TUNEL assay. The production of COX-2, IL-6, IL-8, and TNF-α was examined by ELISA. It can be seen that 16 overlapping genes were selected from 109 possible targets of embelin and 342 possible targets of IDD. KEGG pathway enrichment analysis showed that the PI3K/Akt signaling pathway was a close link between embelin and IDD. We found that embelin dose-dependently improved the cell viability in IL-1β-stimulated NPCs. Embelin elevated the relative levels of p-PI3K/PI3K and p-Akt/Akt in IL-1β-stimulated NPCs. IL-1β induced a significant increase in apoptotic deaths of NPCs, which was attenuated by embelin treatment. IL-1β-induced alternations in expression levels of apoptotic-related proteins including cleaved caspase-3, Bax and Bcl-2 were prevented by embelin treatment. Pretreatment with LY294002 (an inhibitor of PI3K) reversed the inhibitory effect of embelin on IL-1β-induced apoptosis in NPCs. Embelin treatment caused inhibitory effects on the IL-1β-stimulated production of COX-2, IL-6, IL-8, and TNF-α, which were abolished by LY294002 treatment. Furthermore, embelin treatment prevented IL-1β-induced phosphorylation of p65 in NPCs, while LY294002 elevated the embelin-caused decrease in p-p65/p65 level. Overall, embelin protected human NPCs against IL-1β-stimulated apoptosis and inflammation by regulating the PI3K/Akt signaling pathway. These findings provided new ideas for the clinical usage of embelin in the prevention and treatment of IDD.

The mechanisms and functions of TNF-α in intervertebral disc degeneration

Low back pain (LBP) is one of the most common health problems in people's lives, which brings a massive burden to clinicians, and the leading cause of LBP is intervertebral disc degeneration (IDD). IDD is mainly caused by factors such as aging, mechanical stress, and lack of nutrition. The pathological mechanism of IDD is very complex, involving inflammatory response, cell metabolism disorder, and so on. Unfortunately, in the current treatment of IDD, only relieving symptoms as the primary means of relieving a patient's pain cannot effectively inhibit or reverse the progression of IDD. Tumor necrosis factor-α (TNF-α) is a multifunctional pro-inflammatory factor involved in many diseases' pathological processes. With the in-depth study of the pathological mechanism of IDD, more and more evidence has shown that TNF-α is an essential activator of IDD, which is related to the metabolic disorder, inflammatory responses, apoptosis, and other pathological processes of extracellular dissociation in the intervertebral disc. Therefore, anti-TNF-α therapy is an effective therapeutic target for alleviating IDD, especially in inhibiting extracellular matrix degradation and reducing inflammatory responses. This article reviews the pathological role of TNF-α in IDD and the latest research progress of TNF-α inhibitors in treating IDD.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Mechanism of YAP1 in the senescence and degeneration of endplate chondrocytes induced by intermittent cyclic mechanical tension

BACKGROUND

This study aimed to investigate the potential mechanism of YAP1 in the senescence and degeneration of endplate chondrocytes induced by intermittent cyclic mechanical tension (ICMT).

METHODS

According to the Pfirrmann grade evaluation classification, 30 human endplate cartilage tissues were divided into the lumbar vertebra fracture (LVF) group and lumbar disc herniation (LDH) group. Then, quantitative reverse transcription polymerase chain reaction, western blot, flow cytometry, hematoxylin-eosin staining, and senescence-associated β-galactosidase staining were performed. The difference in extracellular matrix expression between LVF and LDH endplate cartilage was detected. Second, the effect of ICMT on endplate chondrocytes degeneration was observed. Finally, the key regulatory role of YAP1 in ICMT-induced endplate cartilage degeneration was further verified.

RESULTS

In degraded human endplate cartilage and tension-induced degraded endplate chondrocytes, the expression of YAP1, COL-2A, and Sox9 was decreased. Conversely, the expression of p53 and p21 was increased. By regulating YAP1 in vivo and in vitro, we can achieve alleviation of ICMT-induced senescence of endplate chondrocytes and effective treatment of disc degeneration.

CONCLUSIONS

ICMT could induce senescence and degeneration of endplate chondrocytes, and ICMT-induced senescence and degeneration of endplate chondrocytes could be alleviated by regulating YAP1 expression.

Experimental study of miR-503 regulating the activity as well as the function of degenerated human nucleus pulposus cells of the intervertebral disc through inhibiting Wnt pathway

OBJECTIVES

To preliminarily explore miR-503 in human degenerative disc nucleus pulposus cell effects as well as mechanisms.

METHODS

We utilized bioinformatics analysis to determine the miRNA differential expression as well as key signal pathways existing in human nucleus pulposus cells of the degenerative intervertebral discs. Human degenerative disc nucleus pulposus cell model was cultured and established in vitro. miR-503 and TNIK-related genes are knocked down and overexpressed by lentiviral infection, then we added Wnt signaling pathway agonists; CCK-8, ELISA, RT-PCR, Western blot were used to detect proliferation, apoptosis, and activity of cells.

RESULTS

Bioinformatics results demonstrated that miR-503 was significantly down-regulated in human nucleus pulposus cells of the degenerated intervertebral discs. The targeted differentially expressed genes were mainly enriched in Wnt signaling pathway. However, after screening differential genes in the Wnt pathway, it was demonstrated that miR-503 mainly regulates TNIK to achieve Wnt pathway regulation. Cell experiments in vitro showed that cell activity and function were decreased while apoptosis was increased in the degenerative cell model.

CONCLUSIONS

miR-503 can improve the function and activity of human nucleus pulposus cells of degenerated intervertebral disc by inhibiting Wnt expression. miR-503 mainly regulates the Wnt pathway through targeted binding with TNIK.

Myricetin alleviated hydrogen peroxide-induced cellular senescence of nucleus pulposus cell through regulating SERPINE1

BACKGROUND

Myricetin (MYR) is a common plant flavonoid with antioxidant and anticancer properties. However, the anti-aging effect of MYR on nucleus pulposus cells (NPCs) is still unknown. The study aimed to explore the effect of MYR on the senescence of NPCs.

METHODS

Methyl-thiazolyl tetrazolium assay was used to detect NPCs viability. Senescence level was evaluated by senescence-associated β-galactosidase (SA-β-Gal) staining and the expression levels of P21, P16, IL-6 and IL-8. RNA-Sequencing (RNA-seq) technology was used to identify differentially expressed genes (DEGs) between hydrogen peroxide + MYR (HO + MYR) group and HO group, and Gene Ontology (GO) functional was performed to analyze DEGs. A Venn diagram was generated to screen overlapping DEGs related to aging and inflammation, and the role of the promising validated DEG was selected for further investigation by gene functional assays.

RESULTS

HO inhibited NPCs viability and stimulated the senescent phenotype of NPCs, whereas MYR treatment significantly reversed SA-β-gal activity in NPCs. MYR also reduced the expression of p21 and p16 and the secretion of IL-6 and IL-8 induced by HO. RNA-seq screened 421 DEGs. The GO enrichment results showed DEGs were mainly enriched in terms such as "sterol biosynthetic process". We also found SERPINE1 has the highest log2FC abs. Silence of SERPINE1 inhibited HO-induced NPCs senescence, and overexpression of SERPINE1 could limit the anti-aging effect of MYR.

CONCLUSIONS

MYR alleviated HO-induced senescence of NPCs by regulating SERPINE1 in vitro.

Time required for commitment to T cell proliferation depends on TCR affinity and cytokine response

T cell activation and effector functions are determined by the affinity of the interaction between T cell receptor (TCR) and its antigenic peptide MHC (pMHC) ligand. A better understanding of the quantitative aspects of TCR-pMHC affinity-dependent T cell activation is critical for the development of new immunotherapeutic strategies. However, the role of TCR-pMHC affinity in regulating the kinetics of CD8+ T cell commitment to proliferation and differentiation is unknown. Here, we show that the stronger the TCR-pMHC affinity, the shorter the time of T cell-APC co-culture required to commit CD8+ T cells to proliferation. The time threshold for T cell cytokine production is much lower than that for cell proliferation. There is a strong correlation between affinity-dependent differences in AKT phosphorylation and T cell proliferation. The cytokine IL-15 increases the poor proliferation of T cells stimulated with low affinity pMHC, suggesting that pro-inflammatory cytokines can override the affinity-dependent features of T cell proliferation.

A crucial exosome-related gene pair (AAMP and ABAT) is associated with inflammatory cells in intervertebral disc degeneration

Identification of exosome-related genes (ERGs) and competing endogenous RNAs (ceRNAs) associated with intervertebral disc degeneration (IDD) may improve its diagnosis and reveal its underlying mechanisms. We downloaded 49 samples from Gene Expression Omnibus and identified candidate ERGs using differentially expressed ERGs (De-ERGs), exosome-related gene pairs (ERGPs), and machine learning algorithms [least absolute shrinkage and selection operator (LASSO) and support vector machine (SVM)]. Immune cell-related ERGs were selected via immune-infiltration analysis, and clinical values were assessed using receiver operating characteristic curves. Based on the De-ERGs, a ceRNA network comprising 1,512 links and 330 nodes was constructed and primarily related to signal transduction pathways, apoptosis-related biological processes, and multiple kinase-related molecular functions. In total, two crucial De-ERGs [angio-associated migratory cell protein (AAMP) and 4-aminobutyrate aminotransferase (ABAT)] were screened from results in De-ERGs, ERGPs, LASSO, and SVM. Increased AAMP expression and decreased ABAT expression were positively and negatively correlated with CD8⁺ T cell infiltration, respectively. AAMP/ABAT was the only pair differentially expressed in IDD and correlated with CD8⁺ T cell infiltration. Furthermore, AAMP/ABAT displayed higher accuracy in predicting IDD than individual genes. These results demonstrated the ERGP AAMP/ABAT as a robust signature for identifying IDD and associated with increased CD8⁺ T cell infiltration, suggesting it as a promising IDD biomarker.

Identifification and validation of ferroptosis signatures and immune infifiltration characteristics associated with intervertebral disc degeneration

Ferroptosis and immune infiltration play an important role in the pathogenesis of intervertebral disc degeneration (IDD). However, there is still a lack of comprehensive analysis on the interaction between ferroptosis-related genes (FRGs) and immune microenvironment in IDD patients. Therefore, this study aims to explore the correlation between FRGs characteristics and immune infiltration in the progression of IDD. The expression profiles (GSE56081 and GSE70362) and FRGs were downloaded from the comprehensive gene expression omnibus (GEO) and FerrDb database, respectively, and the differences were analyzed using R. The intersection of IDD related differential genes (DEGs) and FRGs was taken as differentially expressed FRGs (DE-FRGs) and GO and KEGG enrichment analysis was conducted. Then, we used least absolute shrinkage and selection operator (LASSO) regression algorithm and support vector machine (SVM) algorithm to screen feature genes and draw ROC curve judge the diagnostic value of key DE-FRGs. Then CIBERSORT algorithm is used to evaluate the infiltration of immune cells and analyze the correlation between key DE-FRGs and immune infiltration. Based on the analysis results, we conducted single gene GSEA analysis on key DE-FRGs. RT-PCR and immunohistochemistry further verified the clinical value of the results of biochemical analysis and screening. Seven key DE-FRGs were screened, including the upregulated genes NOX4 and PIR, and the downregulated genes TIMM9, ATF3, ENPP2, FADS2 and TFAP2A. Single gene GSEA analysis further elucidates the role of DE-FRGs in IDD associated with ferroptosis. Correlation analysis showed that seven key DE-FRGs were closely related to immune infiltration in the development of IDD. Finally, RT-PCR and immunohistochemical staining showed that NOX4, ENPP2, FADS2 and TFAP2A were statistically significant differences. In this study, we explored the connection between ferroptosis related characteristics and immune infiltration in IDD, and confirmed that NOX4, ENPP2, FADS2, and TFAP2A may become biomarkers and potential therapeutic targets for IDD.

Is intervertebral disc degeneration associated with reduction in serum ferritin?

OBJECTIVE

Ferritin autophagy is characterized by intracellular ferroptosis and selective ferritin degradation. However, the role of ferritin in the development of intervertebral disc degeneration (IDD) has not been elucidated. The study aimed to investigate the role of serum iron metabolism markers, especially serum ferritin (SF), in IDD.

METHODS

217 patients who came to the spine surgery department of our hospital for low back pain were recruited, and blood samples were collected for routine examination after admission. The cumulative grade was also calculated by summing up the Pfirrmann grade of all lumbar discs.

RESULTS

Correlation analysis showed that cumulative grade was correlated with SF (r = - 0.185, p = 0.006), not with serum iron (SI), transferrin saturation (TS), unsaturated iron-binding capacity (UIBC) and total iron-binding capacity (TIBC) (all p > 0.05). In addition, SF levels in the low severity IDD were significantly higher than high severity IDD in cumulative grade (p = 0.003) and single disc grade. No statistically significant difference was found in the other four indicators. A statistically significant difference was observed between the high (cumulative grade > 17) and low score (cumulative grade ≤ 17) groups in terms of age. According to the ROC curve, the cut-off value of SF levels was 170.5. Patients with SF < 170.5 ng/mL had severe disc degeneration. The sensitivity and specificity were 0.635 and 0.602, respectively.

CONCLUSION

This study preliminarily showed that SF was negatively correlated with the degree of IDD and can be used to predict IDD severity.