Grem1 accelerates nucleus pulposus cell apoptosis and intervertebral disc degeneration by inhibiting TGF-β-mediated Smad2/3 phosphorylation

Identification and Validation of Circadian Rhythm-Related Genes Involved in Intervertebral Disc Degeneration and Analysis of Immune Cell Infiltration via Machine Learning

Background

Low back pain is a significant burden worldwide, and intervertebral disc degeneration (IVDD) is identified as the primary cause. Recent research has emphasized the significant role of circadian rhythms (CRs) and immunity in affecting intervertebral discs (IVD). However, the influence of circadian rhythms and immunity on the mechanism of IVDD remains unclear. This study aimed to identify and validate key rhythm-related genes in IVDD and analyze their correlation with immune cell infiltration.

Methods

Two gene expression profiles related to IVDD and rhythm-related genes were obtained from the Gene Expression Omnibus and GeneCards databases to identify differentially expressed rhythm-related genes (DERGs). Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene set enrichment analysis (GSEA) were conducted to explore the biological functions of these genes. LASSO regression and SVM algorithms were employed to identify hub genes. We subsequently investigated the correlation between hub rhythm-related genes and immune cell infiltration. Finally, nucleus pulposus-derived mesenchymal stem cells (NPMSCs) were isolated from normal and degenerative human IVD tissues. Hub rhythm-related genes expression in NPMSCs was confirmed by real-time quantitative PCR (RT-qPCR).

Results

Six hub genes related to CRs (CCND1, FOXO1, FRMD8, NTRK2, PRRT1, and TFPI) were screened out. Immune infiltration analysis revealed that the IVDD group had significantly more M0 macrophages and significantly fewer follicular helper T cells than those of the control group. Specifically, M0 macrophages were significantly associated with FRMD8, PRRT1, and TFPI. T follicular helper cells were significantly associated with FRDM8, FOXO1, and CCND1. We further confirmed that CCND1, FRMD8, NTRK2, and TFPI were dysrhythmic within NPMSCs from degenerated IVD in vitro.

Conclusion

Six genes (CCND1, FOXO1, FRMD8, NTRK2, PRRT1 and TFPI) linked to circadian rhythms associated with IVDD progression, together with immunity. The identification of these DEGs may provide new insights for the diagnosis and treatment of IVDD.

Baicalin alleviates intervertebral disc degeneration by inhibiting the p38 MAPK signaling pathway

BACKGROUND

Intervertebral disc degeneration (IVDD) represents a prevalent degenerative pathology of the spinal, primarily precipitated by inflammatory processes and the deterioration of extracellular matrix (ECM). Baicalin has an effective anti-inflammatory effect on degenerative diseases. In addition, the P38 mitogen-activated protein kinase (MAPK) signaling pathway plays a crucial role in the pathogenesis of IVDD.

OBJECTIVE

To investigate the therapeutic potential of baicalin in modulating pathological changes in IVDD.

METHODS

To design an in vitro model of degeneration of nucleus pulposus cells (NPCs) stimulated by IL-1β and an in vivo mouse model of needling to assess the protective effect of baicalin against IVDD and its underlying mechanism.

RESULTS

Baicalin down-regulated inflammatory factors (INOS, COX-2, IL-6) and catabolic factors (MMP-3, MMP-13, ADAMTS-5) while up-regulating anabolic factors (collagen II, SOX-9) by inhibiting the activation of the p38 MAPK signaling pathway, in addition to slowing down the progression of IVDD in the mouse acupuncture model.

CONCLUSION

Our study demonstrated in vitro experiments that baicalin attenuates IL-1β-stimulated IVDD by inhibiting activation of the P38 MAPK signaling pathway. Meanwhile, the effects of baicalin were also confirmed in vivo experiments, Consequently, we propose that baicalin is a promising therapeutic agent for the treatment of disc degeneration.

ACVR1 drives neuropathic pain by regulating NLRP3-Induced neuronal pyroptosis through the p38 and Smad1/5/8 pathways

BACKGROUND

Neuropathic pain is characterized by sustained pain hypersensitivity caused by nerve injury. The molecular mechanisms underlying this condition remain poorly understood. This study aims to elucidate the role of ACVR1 and its downstream pathways in mediating neuropathic pain through neuronal pyroptosis and neuroinflammation.

METHODS

A spared nerve injury (SNI) model was established both in male and female mouse to induce neuropathic pain. Behavioral tests, Western blot, PCR, and immunofluorescence were used to assess the expression of ACVR1, p-Smad1/5/8, p-p38, and pyroptosis-related proteins (NLRP3, Caspase-1, and GSDMD-N). ACVR1, p38, and Smad1/5/8 were pharmacologically inhibited to evaluate their roles in neuropathic pain and pyroptosis.

RESULTS

Behavioral analysis confirmed successful SNI model establishment, marked by reduced paw withdrawal thresholds (PWT). Protein and mRNA expression analysis revealed significant upregulation of ACVR1, p-Smad1/5/8, and p-p38 in the spinal cord, particularly in neurons. Furthermore, SNI enhanced pyroptosis-related protein expression, including NLRP3, Caspase-1, GSDMD-N, IL-1β and IL-18. Inhibition of ACVR1 alleviated mechanical allodynia, reduced neuronal pyroptosis, and decreased serum IL-1β and IL-18 levels. Similarly, p38 inhibition mitigated NLRP3-induced pyroptosis without altering ACVR1 expression. In contrast, Smad1/5/8 inhibition by DMH-1 effectively reduced pyroptosis and inflammation via NLRP3 but had no effect on p38 phosphorylation. Combined p38 and Smad1/5/8 pathway inhibition synergistically decreased pyroptosis-related protein expression, highlighting their interactive roles in ACVR1-mediated neuropathic pain.

CONCLUSION

These findings suggest that ACVR1 exacerbates neuropathic pain by activating neuronal pyroptosis and neuroinflammation via the p38 and Smad1/5/8 pathways. Targeting ACVR1 and its downstream signaling pathways may offer novel therapeutic strategies for neuropathic pain.

Microneedle delivery of CAR-M-like engineered macrophages alleviates intervertebral disc degeneration through enhanced efferocytosis capacity

Macrophages eliminate apoptotic cells produced daily in the body through efferocytosis. Restricted clearance can cause inflammation-related diseases. In intervertebral discs (IVDs), apoptotic nucleus pulposus cells (NPCs) are difficult to effectively remove, and their accumulation can cause changes in the inflammatory microenvironment, disrupt IVD homeostasis, and lead to IVD degeneration (IDD). Here, we present chimeric antigen receptor-M-like engineered macrophages (CAR-eMs) with enhanced efferocytosis capacity for IDD treatment. Macrophages undergo phenotypic transformation and a reduction in phagocytic ability after phagocyting apoptotic NPCs, but their efferocytosis capacity recovers with upregulated brain-specific angiogenesis inhibitor 1 (BAI1) expression. We develop a CAR-eM system with enhanced BAI1 expression and an IVD circular microneedle (MN) delivery system that utilizes arrays of MNs to deliver CAR-eMs into the deep IVD layers, thereby clearing apoptotic NPCs, ameliorating the inflammatory microenvironment, and repairing damaged IVDs. Our study explores the therapeutic potential of CAR-eM efferocytosis for IDD treatment.

Curculigoside upregulates BMAL1 to decrease nucleus pulposus cell apoptosis by inhibiting the JAK/STAT3 pathway

BACKGROUND

Intervertebral disc degeneration (IVDD) is a natural process that occurs with aging and is the main cause of low back pain. Basic helix-loop-helix ARNT-like 1 (BMAL1) plays key roles in the pathogenesis of many diseases. The present study investigates the role of curculigoside (CUR), which has been reported to be a potential anti-apoptotic compound in other diseases.

METHODS

Dysregulated genes were identified by RNA sequencing (RNA-seq). Western blotting (WB), immunohistochemistry, immunofluorescence (IF) staining, and real-time fluorescent quantitative polymerase chain reaction were used to detect BMAL1 expression in 25 human intervertebral disc specimens (male: female =13:12), tissues from BMAL1-knockout mice and from an IVDD mouse model. The regulatory effects of CUR and BMAL1 in nucleus pulposus (NP) cells after Small Interfering RNA (siRNA) transfection were examined by flow cytometry, IF staining and WB. The therapeutic effect of intraperitoneal CUR injection was also evaluated in mice.

RESULTS

BMAL1 expression was negatively correlated with IVDD severity and was significantly lower in degenerative NP cells. After BMAL1 knockdown using siRNA, the apoptosis rate of degenerative NP cells was significantly higher, while transfection with a lentivirus overexpressing BMAL1 exerted the opposite effect. Bioinformatics analysis revealed that BMAL1 is regulated by the JAK-STAT3 pathway, and CUR upregulated BMAL1 expression by inhibiting STAT3 phosphorylation, subsequently alleviating NP cell apoptosis and increasing extracellular matrix (ECM) components., thus alleviating IVDD.

CONCLUSIONS

CUR can inhibit apoptosis and improve the ECM by upregulating BMAL1 expression, which is reduced in IVDD. This study provides a therapeutic strategy to alleviate apoptosis associated with inflammation-induced IVDD.

M2 macrophages regulate nucleus pulposus cell extracellular matrix synthesis through the OPN-CD44 axis in intervertebral disc degeneration

OBJECTIVE

Macrophages play a crucial role in various physiological processes. In intervertebral disc degeneration (IDD), macrophage infiltration has been observed in human intervertebral disc (IVD) specimens, but how macrophages influence IDD remains unclear.

METHODS

According to the single-cell transcriptome expression profiles from GSE165722, we verified the infiltration of macrophages in IDD and the possible interaction between infiltrated macrophages and nucleus pulposus cells (NPCs). The expression of macrophage-associated markers was verified in specimens of human nucleus pulposus, lumbar spinal instability mice and annulus fibrosus puncture mice. By treating NPCs cocultured with M2 macrophages with osteopontin (OPN) neutralization antibody and siCD44, we demonstrated that both in vitro and in vivo macrophages regulated IDD through the OPN-CD44 axis. Using transforming growth factor beta 1 and siCD44 treatment, we verified that CD44 regulated the pSMAD2/3 pathway.

RESULTS

IDD engaged macrophage infiltration, mainly gathered in the endplate, and induced macrophage M2 polarization. Infiltrated macrophages showed high-level expression of OPN, and NPCs showed upregulated CD44. Depletion of macrophages significantly decreased the expression of OPN and CD44 in degenerative IVD, concurrently exacerbating IDD. The co-culture of macrophages and NPCs in vitro demonstrated that the conditioned media from NPCs induced macrophage M2 polarization. Further, M2 macrophages rescued NPCs extracellular matrix (ECM) phenotype through the OPN-CD44 axis, by regulating pSMAD2/3 nuclear translocation.

CONCLUSIONS

Our findings suggest that macrophages regulate NPC ECM expression in IDD through the OPN-CD44 axis, emphasizing the therapeutic potential of targeting macrophages and the OPN-CD44 axis for IDD prevention and treatment.

LT-α Facilitates the Aerobic Glycolysis and M1 Polarization of Macrophages by Activating the NF-κB Signaling Pathway in Intervertebral Disc Degeneration

Purpose

Injury and inflammatory activate and polarize macrophages in intervertebral disc degeneration (IVDD). Further research needs to be carried to explore the mechanisms that regulate macrophage polarization, providing new insights and targets for IVDD treatment. The aim of our study was to evaluate the influence of LT-α on aerobic glycolysis (AG) and polarization in macrophages.

Methods

M0 macrophages were achieved by stimulating THP-1 cells with PMA. M1 macrophages were obtained by IFN-γ and LPS stimulation in M0 macrophages. Energy metabolomics, AG and apoptosis related protein expression, migration and invasion measurement, proliferation was analyzed. Polarization of macrophages, AG associated genes expression, macrophage recruitment was evaluated. NF-κB signaling was ascertained by laser confocal and Western blotting.

Results

The propanoate metabolism pathway was enriched in LT-α overexpressing M0 macrophages, and various energy metabolites were detected. Glucose absorption, lactic acid production, and levels of AG proteins were strikingly increased in LT-α overexpression macrophages and remarkably repressed in LT-α knockdown macrophages, accompanied by activated and inactivated NF-κB signaling, respectively. Suppressed migration and invasion ability, restrained proliferation, activated AG, and enhanced apoptosis were observed in nucleus pulposus (NP) cells treated by LT-α overexpressed macrophages, accompanied by reduced macrophage recruitment, with opposite results when treated by LT-α knockdown macrophages. The enhanced M1 polarization and activated AG in LT-α overexpression macrophages were abolished by co-culturing with NF-κB inhibitor.

Conclusion

LT-α facilitates the AG and M1 polarization of macrophages via activating the NF-κB signaling pathway.

Reprogramming to restore youthful epigenetics of senescent nucleus pulposus cells for mitigating intervertebral disc degeneration and alleviating low back pain

Aging is a pivotal risk factor for intervertebral disc degeneration (IVDD) and chronic low back pain (LBP). The restoration of aging nucleus pulposus cells (NPCs) to a youthful epigenetic state is crucial for IVDD treatment, but remains a formidable challenge. Here, we proposed a strategy to partially reprogram and reinstate youthful epigenetics of senescent NPCs by delivering a plasmid carrier that expressed pluripotency-associated genes (Oct4, Klf4 and Sox2) in Cavin2-modified exosomes (OKS@M-Exo) for treatment of IVDD and alleviating LBP. The functional OKS@M-Exo efficaciously alleviated senescence markers (p16INK4a, p21CIP1 and p53), reduced DNA damage and H4K20me3 expression, as well as restored proliferation ability and metabolic balance in senescent NPCs, as validated through in vitro experiments. In a rat model of IVDD, OKS@M-Exo maintained intervertebral disc height, nucleus pulposus hydration and tissue structure, effectively ameliorated IVDD via decreasing the senescence markers. Additionally, OKS@M-Exo reduced nociceptive behavior and downregulated nociception markers, indicating its efficiency in alleviating LBP. The transcriptome sequencing analysis also demonstrated that OKS@M-Exo could decrease the expression of age-related pathways and restore cell proliferation. Collectively, reprogramming by the OKS@M-Exo to restore youthful epigenetics of senescent NPCs may hold promise as a therapeutic platform to treat IVDD.

FSTL1 accelerates nucleus pulposus-derived mesenchymal stem cell apoptosis in intervertebral disc degeneration by activating TGF-β-mediated Smad2/3 phosphorylation

BACKGROUND

Intervertebral disc degeneration (IVDD) is the leading cause of low back pain, and repair using nucleus pulposus-derived mesenchymal stem cells (NP-MSCs) represents a promising therapeutic approach. However, both endogenous and transplanted NP-MSCs demonstrate limited proliferative capacity, increased apoptosis, and reduced resilience to the harsh microenvironment within the degenerative intervertebral disc (IVD).

METHODS

RNA sequencing (RNA-seq) was utilized to identify genes and associated mechanisms that mediate the responses of NP-MSCs to acidic conditions. Western blotting, qPCR, and immunofluorescence were used to evaluate follistatin-like 1 (FSTL1) expression in NP-MSCs. Apoptosis and extracellular matrix (ECM) anabolism were assessed via flow cytometry, TUNEL staining and Western blotting, while the TGF-β/Smad2/3 pathway was analyzed using Western blotting and immunofluorescence. FSTL1 knockdown with small interfering RNA (siRNA) was performed to determine its role in apoptosis and ECM regulation. The FSTL1 siRNA pretreatment was assessed in a puncture-induced rat IVDD model using MRI and histological staining.

RESULTS

Using RNA-seq, we identified FSTL1 as the primary acid-responsive gene in NP-MSCs. We further observed elevated FSTL1 expression in NP-MSCs isolated from degenerative IVDs in both humans and rats compared to normal IVDs. Acidic conditions upregulated FSTL1 expression in NP-MSCs in a pH-dependent manner. Notably, recombinant FSTL1 was shown to enhance cellular apoptosis and disrupt ECM metabolism. Conversely, silencing FSTL1 with siRNA reduced NP-MSC apoptosis and improved ECM anabolism. Importantly, TGF-β pathway inhibition partially reversed the pro-apoptotic and ECM catabolism effects of FSTL1. In the rat model of IVDD, pretreatment of NP-MSCs with FSTL1 siRNA significantly suppressed IVDD progression.

CONCLUSIONS

This study provides novel insights into the mechanistic role of FSTL1 in acid-induced apoptosis of NP-MSCs and its contribution to the progression of IVDD. These findings offer valuable perspectives for developing targeted therapeutic strategies to mitigate IVDD progression.

CRLF1/CLCF1 heterodimer involvement in intervertebral disc degeneration via exacerbation of extracellular matrix degradation and nucleus pulposus cell senescence

OBJECTIVE

Low back pain (LBP) is one of the most prevalent musculoskeletal disorders and has a significant global impact. Intervertebral disc degeneration (IVDD) is an important cause of LBP. The aim of this study was to test a hypothesis that elucidates the potential role and molecular mechanisms of cytokine receptor-like factor 1 (CRLF1) in IVDD and LBP.

METHODS

We identified dysregulated genes in normal and degenerative discs via microarray profiles. We verified the correlation between CRLF1 and the progression of IVDD in animal models and cellular models and further explored the effect of increased CRLF1 on nucleus pulposus cells (NPCs) and its mechanism by RNA-seq. Finally, the ameliorative effect of CRLF1 knockdown on degenerated NPCs was elucidated by in vivo and in vitro experiments.

RESULTS

We verified the close relationship between senescent NPCs and disc degeneration. We determined that elevated CRLF1 is associated with the progression of NPC senescence and disc degeneration in animal and cellular models. In addition, fluorescence colocalization and coimmunoprecipitation analysis revealed that CRLF1 forms a heterodimer with CLCF1, which together activate JAK/STAT3 signaling. This activation enhances the production of SASPs and accelerates NPC senescence. In vitro studies have shown that targeting CRLF1 reduces ECM degradation and alleviates NPC senescence. Correspondingly, in vivo and pain-behavior tests showed that CRLF1 knockdown reduces IVDD and LBP.

CONCLUSION

The CRLF1/CLCF1 heterodimer is involved in IVDD, and CRLF1 may be an effective therapeutic target for treating IVDD progression and associated LBP.

Integrated bulk and single-cell RNA sequencing to identify potential biomarkers in intervertebral disc degeneration

BACKGROUND

Nucleus pulposus (NP) deterioration plays a significant role in the development of intervertebral disc degeneration (IVDD) and low back pain (LBP). This paper aims to identify potential genes within degenerated NP tissue and elucidate the pathogenesis of IVDD through bioinformatics analysis.

METHODS

We conducted a transcriptomic analysis of patient's degenerative NP tissue employing advanced bioinformatics techniques and machine learning algorithms. Utilizing hdWGCNA, we successfully acquired WGCNA single-cell sequencing data and pinpointed crucial genes implicated in IVDD. Subsequently, we employed the Monocle3 package to perform pseudotime sequence analysis, enabling the identification of genes associated with the differentiation and developmental processes of NP tissue. Following this, normalized and logarithmically transformed the bulk sequencing data. Subsequently, we conducted preliminary screening using single-factor logistic regression on the genes derived from single-cell sequencing. Next, we applied two machine learning techniques, namely, SVM-RFE and random forest, to discern pivotal pathogenic genes. Finally, we used validation sets to verify trends and qualitativeness and performed in vitro and in vivo validation analyses of normal and degenerative NP tissues.

RESULTS

909 genes associated with IVDD were identified through hdWGCNA, while pseudotime sequence analysis uncovered 1964 genes related to differentiation and developmental processes. The two had 208 genes in common. Subsequently, we conducted an initial screening of single-cell genes by integrating the bulk database with single logistic regression. Next, we utilized machine learning techniques to identify the IVDD genes CDH, DPH5, and SELENOF. PCR analysis confirmed that the expression of CDH and DPH5 in degraded nucleus pulposus cells (NPCs) was decreased by 31% and 28% in vivo, and 36% and 29% in vitro, respectively, while SELENOF showed the opposite trend. Furthermore, IVDD was validated through imaging and histological staining.

CONCLUSION

As pathogenic genes in IVDD, our findings indicate that CTH, DPH5, and SELENOF are important players and might be promising therapeutic targets for IVDD treatment.

Microenvironment Remodeling Microgel Repairs Degenerated Intervertebral Disc via Programmed Delivery of MicroRNA-155

The progression of intervertebral disc degeneration (IVDD) is associated with increased cell apoptosis and reduced extracellular matrix (ECM) production, both of which are driven by ongoing inflammation. Thus, alleviating the acidic inflammatory microenvironment and mitigating the apoptosis of nucleus pulposus cells (NPCs) are essential for intervertebral disc (IVD) regeneration. Regulating pH levels in the local environment can reduce inflammation and promote tissue recovery. In this study, a lactic acid-capturing microgel carrying a functionalized miRNA-155 nanocarrier was designed for IVD regeneration. microRNA-155 was loaded into the NPC-targeted nanogel via host-guest binding. The miR-155 nanocarrier (NGM) achieved lactic acid-sensitive release of miRNA-155, resulting in rapid regulation of apoptosis. Moreover, SS31, which dissociated from the nanogel network, had the ability to regulate mitochondrial metabolism. Moreover, the microgel was constructed using a matrix metalloproteinase-responsive peptide. The chitosan coating on the microgel system was ingeniously employed to capture lactic acid and enable pH-responsive dissociation, thereby alleviating the acidic microenvironment to protect cell viability and facilitate the delivery of the NGM. The microgel system effectively promoted IVD regeneration by alleviating the acidic microenvironment and preventing NPC apoptosis.

Role of macrophage in intervertebral disc degeneration

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

ROS-responsive Hydrogel Loaded with Allicin Suppresses Cell Apoptosis for the Treatment of Intervertebral Disc Degeneration in a Rat Model

BACKGROUND

Intervertebral disc degeneration (IVDD) is a common cause of lower back pain, and cell apoptosis plays a key role in its progression. This study explores the therapeutic potential of a reactive oxygen species (ROS)-responsive hydrogel loaded with allicin for treating IVDD.

METHODS

Allicin was encapsulated in an ROS-responsive hydrogel, and its controlled release was studied in vitro. Nucleus pulposus cells were treated with hydrogen peroxide to induce apoptosis, and the effects of the hydrogel were examined using quantitative polymerase chain reaction and Western blotting. An in vivo rat model of IVDD was also established to assess the efficacy of the treatment.

RESULTS

The ROS-responsive hydrogel effectively inhibited apoptosis in nucleus pulposus cells by reducing ROS levels and modulating the expression of apoptotic and antiapoptotic genes. In the rat model, the hydrogel loaded with allicin significantly reduced IVDD, preserving disc morphology and matrix integrity.

CONCLUSIONS

ROS-responsive hydrogel loaded with allicin shows potential as a therapeutic approach for IVDD by inhibiting cell apoptosis and reducing disc degeneration in vivo.

LRP1 mitigates intervertebral disc degeneration by inhibiting endoplasmic reticulum stress through stabilizing the PPARγ

Background

Intervertebral disc degeneration (IDD) is a significant cause of lower back pain, characterized by inflammation-mediated extracellular matrix (ECM) degradation, apoptosis, and aging of nucleus pulposus (NP) cells. Identifying key regulatory targets for these processes is crucial for IDD treatment. Previous research has highlighted the role of low-density lipoprotein receptor-related protein 1 (LRP1) in regulating ECM levels and cell fate, but its role in IDD remains under-explored. This study aims to elucidate the function and mechanism of LRP1 in the progression of IDD.

Methods

LRP1 expression was assessed in clinical tissue samples from patients diagnosed with IDD and in a rat IDD model established using needle puncture injuries. The effects of LRP1 knockdown and treatment with the LRP1 activator SP16 on apoptosis and ECM metabolism in NP cells were analyzed, with a focus on their relationship with endoplasmic reticulum (ER) stress. The interaction and regulatory mechanism between LRP1 and peroxisome proliferator-activated receptor gamma (PPARγ) were further explored to clarify how LRP1 regulates ER stress. Finally, the in vivo therapeutic effect of SP16 was investigated using a rat tail IDD model.

Results

We found that LRP1 expression was significantly downregulated in IDD. In NP cells with LRP1 knockdown, there was a marked increase in apoptosis and detrimental ECM remodeling, which were associated with the activation of ER stress. Our research further revealed that LRP1 interacts with PPARγ, stabilizing the PPARγ protein and preventing its lysosomal degradation, thereby mitigating ER stress. Activation of LRP1 in our models significantly reduced ER stress, matrix degradation, and apoptosis, thereby attenuating IDD both in vitro and in vivo.

Conclusion

This study systematically investigated the role and mechanisms of the LRP1/PPARγ/ER stress signaling axis in IDD. Our findings suggest that targeting LRP1 to modulate this signaling pathway could provide a promising therapeutic approach for the treatment of IDD.

The Translational potential of this Article

Our study demonstrated that LRP1 can reduce apoptosis and ECM degradation by inhibiting ER stress through stabilizing PPARγ, indicating that targeting LRP1 may be a novel therapeutic strategy for IDD.

Animal Models of Intervertebral Disc Diseases: Advantages, Limitations, and Future Directions

Animal models are valuable tools for studying the underlying mechanisms of and potential treatments for intervertebral disc diseases. In this review, we discuss the advantages and limitations of animal models of disc diseases, focusing on lumbar spinal stenosis, disc herniation, and degeneration, as well as future research directions. The advantages of animal models are that they enable controlled experiments, long-term monitoring to study the natural history of the disease, and the testing of potential treatments. However, they also have limitations, including species differences, ethical concerns, a lack of standardized protocols, and short lifespans. Therefore, ongoing research focuses on improving animal model standardization and incorporating advanced imaging and noninvasive techniques, genetic models, and biomechanical analyses to overcome these limitations. These future directions hold potential for improving our understanding of the underlying mechanisms of disc diseases and for developing new treatments. Overall, although animal models can provide valuable insights into pathophysiology and potential treatments for disc diseases, their limitations should be carefully considered when interpreting findings from animal studies.

A novel multi-omics approach for identifying key genes in intervertebral disc degeneration

Many different cell types and complex molecular pathways are involved in intervertebral disc degeneration (IDD). We used a multi-omics approach combining single-cell RNA sequencing (scRNA-seq), differential gene expression analysis, and Mendelian randomization (MR) to clarify the underlying genetic architecture of IDD. We identified 1,164 differentially expressed genes (DEGs) across four important cell types associated with IDD using publicly available single-cell datasets. A thorough gene network analysis identified 122 genes that may be connected to programmed cell death (PCD), a crucial route in the etiology of IDD. SLC40A1, PTGS2, and GABARAPL1 have been identified as noteworthy regulatory genes that may impede the advancement of IDD. Furthermore, distinct cellular subpopulations and dynamic gene expression patterns were revealed by functional enrichment analysis and pseudo-temporal ordering of chondrocytes. Our results highlight the therapeutic potential of GABARAPL1, PTGS2, and SLC40A1 targeting in the treatment of IDD.

An exploratory study of cervical disc degeneration model and mechanism of acupuncture therapy in rabbits

Acupuncture is an important therapy method in traditional Chinese medicine for treating intervertebral disc degeneration (IVDD), offering a wide range of applications. It is based on the theory of Chinese veterinary medicine and combines the stage of the disease course and individual differences for syndrome differentiation and treatment. However, there are few studies on the acupuncture treatment of cervical disc degeneration (CDD) in rabbits. Treatment based on syndrome differentiation is the basic principle of Chinese veterinary treatment. The selection of acupoints for external treatment should be based on individual etiology and pathogenesis. Nevertheless, most current studies do not follow this guideline. In this study, we established the CDD model and explored the mechanism of acupuncture treatment in alleviating CDD in rabbits by selecting a group of main acupoints including cervical Jiaji, Fengchi, Tianzhu, Naohu, Dazhui, and Houxi acupoints, combined with Western medicine's understanding of the pathogenesis of cervical spondylosis, from the anti-inflammatory, analgesic, and tissue-repairing perspectives. Magnetic resonance imaging (MRI) confirmed the successful establishment of the rabbit CDD model. Acupuncture stimulation reduced the increase of average and maximum neck temperature due to CDD in rabbits. The acupuncture treatment relieved the spinal disc damage in the neck of the rabbit, which also decreased the expression level of pro-apoptotic factor Bax and increased the expression level of anti-apoptotic factor Bcl-2. In addition, it can alleviate the abnormal apoptosis of rabbit intervertebral disc, decrease the expression level of inflammatory factors such as TNF-α, IL-1β, IL-2, and PGE2α, and alleviate the intense inflammation and pain response caused by CDD in rabbits. In conclusion, Acupuncture treatment can slow down the CDD of rabbits by regulating the inflammatory response and abnormal apoptosis of intervertebral disc tissue.

Melatonin attenuates degenerative disc degression by downregulating DLX5 via the TGF/Smad2/3 pathway in nucleus pulposus cells

Background

Intervertebral disc degeneration (IVDD) is the leading cause of low back pain, and apoptosis plays a key role in its pathogenesis. Distal-less homeobox 5 (Dlx5) has been reported to induce cell apoptosis. Melatonin, as a powerful antiapoptotic agent, has been widely reported.

Aim

This study aimed to investigate the role of DLX5 in the pathogenesis of IVDD and the potential therapeutic role of melatonin in targeting DLX5 in IVDD.

Materials & Methods

Western blotting, RT-qPCR, immunohistochemistry, si-DLX5, Ex-DLX5, flow cytometry, and immunofluorescence were used to examine the regulatory effect of DLX5 on apoptosis. Therapeutic efficacy was assessed by the intraperitoneal injection of melatonin into IVDD mice.

Results

The expression level of DLX5 is significantly increased in IVDD, and the expression levels were positively correlated with the grade of IVDD. DLX5 was significantly upregulated in TNF-α-induced degenerative NP cells. Degenerative NP cells transfected with si-DLX5 exhibited significantly less apoptosis than control cells. Melatonin significantly alleviated IVDD in surgically induced IVDD model mice.

Discussion

The results revealed that the expression of DLX5 was positively correlated with the severity of IVDD and that melatonin ameliorated DLX5-induced apoptosis and extracellular matrix imbalance by inhibiting the TGF-β/Smad signaling pathway. This study may provide therapeutic strategies to alleviate inflammation-induced apoptosis IVDD-associated inflammation-induced apoptosis.

Conclusion

DLX5 plays an important role in IVDD progression by promoting apoptosis, and melatonin represents a promising therapeutic strategy for alleviating IVDD-associated inflammation and apoptosis.

CARMA3 Drives NF-κB Activation and Promotes Intervertebral Disc Degeneration: Involvement of CARMA3-BCL10-MALT1 Signalosome

Intervertebral disc degeneration (IDD) diseases are common and frequent diseases in orthopedics. The caspase recruitment domain (CARD) and membrane-associated guanylate kinase-like protein 3 (CARMA3) is crucial in the activation of the NF-κB pathway. However, the biological function of CARMA3 in IDD remains unknown. Here, CARMA3 expression was elevated in nucleus pulposus (NP) tissues of IDD rats and nutrient deprivation (ND)-induced NP cells. The main pathological manifestations observed in IDD rats were shrinkage of the NP, reduction of NP cells, fibrosis of NP tissues, and massive reduction of proteoglycans. These changes were accompanied by a decrease in the expression of collagen II and aggrecan, an increase in the expression of the extracellular matrix (ECM) catabolic proteases MMP-3, MMP-13, and metalloprotease with ADAMTS-5, and an increase in the activity of the pro-apoptotic protease caspase-3. The expression of p-IκBαSer32/36 and p-p65Ser536 was also upregulated. However, these effects were reversed with the knockdown of CARMA3. Mechanistically, CARMA3 bound to BCL10 and MALT1 to form a signalosome. Knockdown of CARMA3 reduced the CARMA3-BCL10-MALT1 signalosome-mediated NF-κB activation. CARMA3 activated the NF-κB signaling pathway in a manner that bound to BCL10 and MALT1 to form a signalosome, which affects NP cell damage and is involved in the development of IDD. This supports CARMA3-BCL10-MALT1-NF-κB as a promising targeting axis for the treatment of IDD.

The impact of site-specific DNA methylation in KCNJ11 promoter on type 2 diabetes

Aims

This study explores the correlation between site-specific methylation levels of the KCNJ11 promoter and type 2 diabetes mellitus (T2DM), analyzing potential molecular mechanisms.

Methods

Thirty patients newly diagnosed with T2DM and 30 healthy controls were selected to determine the CpG methylation levels in the promoter region of the KCNJ11 gene using the bisulfite assay. The online software JASPAR was used to predict transcription factors binding to differentially methylated sites. Key transcription factors were further validated through quantitative PCR (q-PCR) and chromatin immunoprecipitation followed by PCR (ChIP-PCR).

Results

Methylation at multiple CpG sites within the KCNJ11 gene promoter was generally reduced in newly diagnosed T2DM patients compared with healthy individuals. The methylation status of CpG-471, a site crucial for the binding of the transcription factor TCF12, emerged as potentially influential in T2DM pathogenesis. This reduction in methylation at CpG-471 may enhance TCF12 binding, thereby altering KCNJ11 expression.

Conclusion

Hypomethylation of specific CpG sites in the promoter region of the KCNJ11 gene in patients with incipient T2DM potentially contributes to the disease's pathogenesis. This hypomethylation may influence TCF12 binding, with potential regulatory effects on KCNJ11 expression and pancreatic beta-cell function, though further studies are needed to confirm the exact mechanisms involved.

Evidence from Mendelian randomization analysis combined with meta-analysis for the causal validation of the relationship between 91 inflammatory factors and lumbar disc herniation

Lumbar disc herniation (LDH) is a common spinal disease. In recent years, an increasing number of observational studies have reported the impact of inflammatory factors on LDH. By conducting Mendelian randomization (MR) analysis on 91 inflammatory factors, it is possible to reveal their causal relationship with LDH, providing new insights for prevention and treatment strategies. In this study, a two-sample MR analysis was performed, using 91 inflammatory factors as exposure data, and LDH data from 2 different sources as outcome data. Subsequently, the most significant results from the inverse-variance weighted analysis were subjected to meta-analysis, with multiple corrections applied to the thresholds to ensure result accuracy. Finally, reverse causality MR analysis was conducted to validate the causal relationship between the identified positive inflammatory factors and LDH. Ninety-one cytokines were analyzed in relation to LDH using MR with data from the Finngen and UK Biobank databases. The inverse-variance weighted results from both analyses were then meta-analyzed, and multiple corrections were applied to the significance threshold of the meta-analysis results. Ultimately, only 1 cytokine, tumor necrosis factor-beta levels (genome-wide association study ID: GCST90274840), showed a significant association after the combined MR analysis and multiple corrections, with an odds ratio of 1.073 (95% confidence interval: 1.034-1.113, P = .0154). Furthermore, this positive cytokine did not display any reverse causality with LDH from either data source. Tumor necrosis factor-beta levels are a risk factor for LDH, potentially increasing the risk of developing the condition and exacerbating its symptoms.

pH-Responsive Modified HAMA Microspheres Regulate the Inflammatory Microenvironment of Intervertebral Discs

Currently, intervertebral disc (IVD) degeneration is believed to lead to local accumulation of lactic acid in the IVD, a decrease in pH, activation of the inflammatory pathway, and continued destruction of homeostasis of the IVD. To address these issues, the intelligent and accurate release of drugs is particularly important. In this study, acid-sensitive release methacrylated hyaluronic acid (HAMA) microspheres were constructed by using microfluidic technology, which can be used as a targeted drug delivery system for intervertebral disc degeneration (IVDD) through Schiff base chemical bonding on the surface of the microspheres to achieve intelligent drug release. Interleukin-1 receptor antagonist (IL-1 Ra) is a naturally occurring anti-inflammatory antagonist of the interleukin-1 family of pro-inflammatory cytokines. Despite its outstanding broad-spectrum anti-inflammatory effects, IL-1 Ra has a short biological half-life (4-6 h). The slow-release performance of IL-1 Ra can be greatly improved using bovine serum albumin nanoparticles (BNP). In addition, the modified HAMA microspheres exhibited good injectability and porosity, and efficient and uniform loading of nanoparticles was achieved via the Schiff base bond. The inflammatory microenvironment can be significantly reversed by transporting the modified HAMA microspheres-BNPs (Modified MS) to the degenerative nucleus pulposus.

MUC1 and CREB3 are Hub Ferroptosis Suppressors for Nucleus Pulposus and Annulus Fibrosus Degeneration by Integrated Bioinformatics and Experimental Verification

Purpose

Ferroptosis is an underlying mechanism for various degenerative diseases, but its role in intervertebral disc degeneration remains elusive. This study aims to explore the key ferroptosis-related genes and its role in nucleus pulposus (NP) and annulus fibrosus (AF) degeneration.

Methods

We analyzed the gene expression profiles of NP and AF from the Gene Expression Omnibus database. The ferroptosis-related differentially expressed genes (FRDEGs) in degenerated NP and AF were filtered, followed by GO and KEGG analysis. Feature FRDEGs were identified by the LASSO and SVM-RFE algorithms, and then Gene Set Enrichment Analysis (GSEA) and Gene Set Variation Analysis (GSVA) were conducted. Immune infiltration analysis was conducted by CIBERSORT algorithm. We established drug networks via the Drug-Gene Interaction Database and competitive endogenous RNA (ceRNA) networks via miRanda, miRDB, and TargetScan database. The expression levels of the feature FRDEGs were assessed by the validation sets, single-cell RNA-seq, and experimental verification.

Results

A total of 15 and 18 FRDEGs were obtained for NP and AF, respectively. GO and KEGG analysis revealed their implication in oxidative stress. Four (AKR1C1, AKR1C3, MUC1, ENPP2) and five (SCP2, ABCC1, KLF2, IDO1, CREB3) feature genes were identified for NP and AF, respectively. The GSEA and GSVA analysis showed that these feature genes were enriched in lots of biological functions, including immune response. CREB3 in degenerated AF was negatively correlated with Eosinophils via CIBERSORT algorithm. The drugs and ceRNAs targeting CREB3 and MUC1 were identified. Experimental verification and single-cell RNA-seq analysis revealed that MUC1 and CREB3 were downregulated in degenerated NP and AF, respectively.

Conclusion

MUC1 and CREB3 were considered novel biomarkers for NP and AF ferroptosis, respectively. Drug and ceRNA networks were constructed for future drug development and investigation of new mechanisms of ferroptosis.

IL-32 aggravates metabolic disturbance in human nucleus pulposus cells by activating FAT4-mediated Hippo/YAP signaling

Extracellular matrix (ECM) metabolism disorders in the inflammatory microenvironment play a key role in the pathogenesis of intervertebral disc degeneration (IDD). Interleukin-32 (IL-32) has been reported to be involved in the progression of various inflammatory diseases; however, it remains unclear whether it participates in the matrix metabolism of nucleus pulposus (NP) cells. Therefore, this study aimed to investigate the mechanism of IL-32 on regulating the ECM metabolism in the inflammatory microenvironment. RNA-seq was used to identify aberrantly expressed genes in NP cells in the inflammatory microenvironment. Western blotting, real-time quantitative PCR, immunohistochemistry and immunofluorescence analysis were performed to measure the expression of IL-32 and metabolic markers in human NP tissues or NP cells treated with or without tumor necrosis factor-α (TNF-α). In vivo, an adeno-associated virus overexpressing IL-32 was injected into the caudal intervertebral discs of rats to assess its effect on IDD. Proteins interacting with IL-32 were identified via immunoprecipitation and mass spectrometry. Lentivirus overexpressing IL-32 or knocking down Fat atypical cadherin 4 (FAT4), yes-associated protein (YAP) inhibitor-Verteporfin (VP) were used to treat human NP cells, to explore the pathogenesis of IL-32. Hippo/YAP signaling activity was verified in human NP tissues. IL-32 expression was significantly upregulated in degenerative NP tissues, as indicated in the clinical samples. Furthermore, IL-32 was remarkably overexpressed in TNF-α-induced degenerative NP cells. IL-32 overexpression induced IDD progression in the rat model. Mechanistically, the elevation of IL-32 in the inflammatory microenvironment enhanced its interactions with FAT4 and mammalian sterile 20-like kinase1/2 (MST1/2) proteins, prompting MST1/2 phosphorylation, and activating the Hippo/YAP signaling pathway, causing matrix metabolism disorder in NP cells. Our results suggest that IL-32 mediates matrix metabolism disorders in NP cells in the inflammatory micro-environment via the FAT4/MST/YAP axis, providing a theoretical basis for the precise treatment of IDD.

Whole transcriptome sequencing of testis and epididymis reveals genes associated with sperm development in roosters

BACKGROUND

Chickens play a crucial role as the primary global source of eggs and poultry, and the quality of rooster semen significantly impacts poultry reproductive efficiency. Therefore, it is imperative to comprehend the regulatory mechanisms underlying sperm development.

RESULTS

In this study, we established transcriptome profiles of lncRNAs, miRNAs, and mRNAs in 3 testis tissues and 3 epididymis tissues from "Jing Hong No.1" roosters at 24, 35, and 64 weeks of age. Using the data, we conducted whole transcriptome analysis and constructed a ceRNA network. We detected 10 differentially expressed mRNAs (DEmRNAs), 33 differentially expressed lncRNAs (DElncRNAs), and 10 differentially expressed miRNAs (DEmiRNAs) in the testis, as well as 149 DEmRNAs, 12 DElncRNAs, and 10 DEmiRNAs in the epididymis. These genes were found to be involved in cell differentiation and development, as well as various signaling pathways such as GnRH, MAPK, TGF-β, mTOR, VEGF, and calcium ion pathways. Subsequently, we constructed two competing endogenous RNA (ceRNA) networks comprising DEmRNAs, DElncRNAs, and DEmiRNAs. Furthermore, we identified four crucial lncRNA-mRNA-miRNA interactions that govern specific biological processes in the chicken reproductive system: MSTRG.2423.1-gga-miR-1563-PPP3CA and MSTRG.10064.2-gga-miR-32-5p-GPR12 regulating sperm motility in the testis; MSTRG.152556.1-gga-miR-9-3p-GREM1/THYN1 governing immunomodulation in the epididymis; and MSTRG.124708.1-gga-miR-375-NDUFB9/YBX1 controlling epididymal sperm maturation and motility.

CONCLUSIONS

Whole transcriptome sequencing of chicken testis and epididymis screened several key genes and ceRNA regulatory networks, which may be involved in the regulation of epididymal immunity, spermatogenesis and sperm viability through the pathways of MAPK, TGF-β, mTOR, and calcium ion. These findings contribute to our comprehensive understanding of the intricate molecular processes underlying rooster spermatogenesis, maturation and motility.

The Role of the Bone Morphogenetic Protein Antagonist Noggin in Nucleus Pulposus Intervertebral Disc Cells

Low back pain (LBP) is a significant global health issue, contributing to disability and socioeconomic burdens worldwide. The degeneration of the human intervertebral disc (IVD) is a critical factor in the pathogenesis of LBP. Recent studies have emphasized the significance of a specific set of genes and extracellular matrix (ECM) in IVD health. In particular, Noggin has emerged as a critical gene due to its high expression levels in healthy nucleus pulposus cells (NPCs) observed in our previous research. In this study, it was hypothesized that decreased Noggin expression in NPCs is associated with IVD degeneration and contributes to LBP development. A lentivirus-mediated RNAi was applied to knock down Noggin expression in primary NPCs from six human donors. The NPCs after transduction were evaluated through cell viability analysis, XTT assay, and cell apoptosis analyses. After two weeks, a colony formation assay was used to examine the anchor-independent growth ability of transduced cells. At the transcript level, anabolic and catabolic markers were quantified using RT-qPCR. The results demonstrated that lentivirus-mediated downregulation of Noggin significantly inhibited cell proliferation, reduced cell viability, and suppressed colony formation, while inducing apoptosis in human NPCs in vitro. Notably, it disrupted cellular anabolic processes and promoted catabolic activity in human NPCs post-transduction. Our findings indicated that the degeneration of human IVD is possibly related to decreased Noggin expression in NPCs. This research provides valuable insights into the role of Noggin in IVD homeostasis and its implications in LBP treatment.

The muscle-intervertebral disc interaction mediated by L-BAIBA modulates extracellular matrix homeostasis and PANoptosis in nucleus pulposus cells

Upon engaging in physical activity, skeletal muscle synthesizes myokines, which not only facilitate crosstalk with various organs, including the brain, adipose tissue, bone, liver, gut, pancreas, and skin but also promote intramuscular signaling. Crosstalk is vital for maintaining various physiological processes. However, the specific interactions between skeletal muscle and intervertebral discs remain largely unexplored. β-Aminoisobutyric acid (BAIBA), an exercise-induced myokine and a metabolite of branched-chain amino acids in skeletal muscle, has emerged as a key player in this context. Our study demonstrated that exercise significantly elevates BAIBA levels in skeletal muscle, plasma, and nucleus pulposus (NP) tissues. Moreover, exercise enhances extracellular matrix (ECM) synthesis in NP tissues and upregulates L-BAIBA synthase in skeletal muscle. Both in vivo and in vitro evidence revealed that L-BAIBA impedes PANoptosis and ECM degradation in NP cells by activating the AMPK/NF-κB signaling pathway. These findings suggest that exercise, coupled with the resulting increase in L-BAIBA, may serve as an effective intervention to decelerate the progression of intervertebral disc degeneration (IDD). Consequently, L-BAIBA, which originates from skeletal muscle, is a promising new therapeutic approach for IDD.

Evaluation of Gremlin-1 as a therapeutic target in metabolic dysfunction-associated steatohepatitis

Gremlin-1 has been implicated in liver fibrosis in metabolic dysfunction-associated steatohepatitis (MASH) via inhibition of bone morphogenetic protein (BMP) signalling and has thereby been identified as a potential therapeutic target. Using rat in vivo and human in vitro and ex vivo model systems of MASH fibrosis, we show that neutralisation of Gremlin-1 activity with monoclonal therapeutic antibodies does not reduce liver inflammation or liver fibrosis. Still, Gremlin-1 was upregulated in human and rat MASH fibrosis, but expression was restricted to a small subpopulation of COL3A1/THY1+ myofibroblasts. Lentiviral overexpression of Gremlin-1 in LX-2 cells and primary hepatic stellate cells led to changes in BMP-related gene expression, which did not translate to increased fibrogenesis. Furthermore, we show that Gremlin-1 binds to heparin with high affinity, which prevents Gremlin-1 from entering systemic circulation, prohibiting Gremlin-1-mediated organ crosstalk. Overall, our findings suggest a redundant role for Gremlin-1 in the pathogenesis of liver fibrosis, which is unamenable to therapeutic targeting.

Single-cell RNA sequencing reveals the differentiation and regulation of endplate cells in human intervertebral disc degeneration

Low back pain (LBP) is largely attributed to intervertebral disc degeneration (IVDD), of which the endplate changes are an important component. However, the alterations in cell fate and properties within the endplates during degeneration remain unknown. Here, we firstly performed the single-cell RNA-sequencing analysis (scRNA-seq) of the cells focusing on degenerative human endplates. By unsupervised clustering of the 8,534 single-cell based on the gene expression, we identified nine distinct cell types. We employed Gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis, and the single-cell regulatory network inference and clustering (SCENIC) to determine the enriched pathways and transcriptional activities across seven chondrocyte subpopulations. Furthermore, two cell fates of chondrocyte differentiation were found by trajectory analysis, one was enriched in inflammation-related genes, and the other was related to extracellular matrix (ECM). Additionally, the intercellular interactions of macrophages (MA) and chondrocytes, T cells/natural killer cells (T/NK) and chondrocytes were examined by ligand-receptor pairs analysis, showing the important regulative function of FN1 from MA and CD74 from T/NK during endplate degeneration. Overall, our findings provide novel perspectives on the endplate degeneration at the single-cell level and a whole-transcriptome size.

A novel spherical GelMA-HAMA hydrogel encapsulating APET×2 polypeptide and CFIm25-targeting sgRNA for immune microenvironment modulation and nucleus pulposus regeneration in intervertebral discs

METHODS

Single-cell transcriptomics and high-throughput transcriptomics were used to screen factors significantly correlated with intervertebral disc degeneration (IDD). Expression changes of CFIm25 were determined via RT-qPCR and Western blot. NP cells were isolated from mouse intervertebral discs and induced to degrade with TNF-α and IL-1β. CFIm25 was knocked out using CRISPR-Cas9, and CFIm25 knockout and overexpressing nucleus pulposus (NP) cell lines were generated through lentiviral transfection. Proteoglycan expression, protein expression, inflammatory factor expression, cell viability, proliferation, migration, gene expression, and protein expression were analyzed using various assays (alcian blue staining, immunofluorescence, ELISA, CCK-8, EDU labeling, transwell migration, scratch assay, RT-qPCR, Western blot). The GelMA-HAMA hydrogel loaded with APET×2 polypeptide and sgRNA was designed, and its effects on NP regeneration were assessed through in vitro and mouse model experiments. The progression of IDD in mice was evaluated using X-ray, H&E staining, and Safranin O-Fast Green staining. Immunohistochemistry was performed to determine protein expression in NP tissue. Proteomic analysis combined with in vitro and in vivo experiments was conducted to elucidate the mechanisms of hydrogel action.

RESULTS

CFIm25 was upregulated in IDD NP tissue and significantly correlated with disease progression. Inhibition of CFIm25 improved NP cell degeneration, enhanced cell proliferation, and migration. The hydrogel effectively knocked down CFIm25 expression, improved NP cell degeneration, promoted cell proliferation and migration, and mitigated IDD progression in a mouse model. The hydrogel inhibited inflammatory factor expression (IL-6, iNOS, IL-1β, TNF-α) by targeting the p38/NF-κB signaling pathway, increased collagen COLII and proteoglycan Aggrecan expression, and suppressed NP degeneration-related factors (COX-2, MMP-3).

CONCLUSION

The study highlighted the crucial role of CFIm25 in IDD and introduced a promising therapeutic strategy using a porous spherical GelMA-HAMA hydrogel loaded with APET×2 polypeptide and sgRNA. This innovative approach offers new possibilities for treating degenerated intervertebral discs.

Exploration of the mode of death and potential death mechanisms of nucleus pulposus cells

Intervertebral disc degeneration (IVDD) is a common chronic orthopaedic disease in orthopaedics that imposes a heavy economic burden on people and society. Although it is well established that IVDD is associated with genetic susceptibility, ageing and obesity, its pathogenesis remains incompletely understood. Previously, IVDD was thought to occur because of excessive mechanical loading leading to destruction of nucleus pulposus cells (NPCs), but studies have shown that IVDD is a much more complex process associated with inflammation, metabolic factors and NPCs death and can involve all parts of the disc, characterized by causing NPCs death and extracellular matrix (ECM) degradation. The damage pattern of NPCs in IVDD is like that of some programmed cell death, suggesting that IVDD is associated with programmed cell death. Although apoptosis and pyroptosis of NPCs have been studied in IVDD, the pathogenesis of intervertebral disc degeneration can still not be fully elucidated by using only traditional cell death modalities. With increasing research, some new modes of cell death, PANoptosis, ferroptosis and senescence have been found to be closely related to intervertebral disc degeneration. Among these, PANoptosis combines essential elements of pyroptosis, apoptosis and necroptosis to form a highly coordinated and dynamically balanced programmed inflammatory cell death process. Furthermore, we believe that PANoptosis may also crosstalk with pyroptosis and senescence. Therefore, we review the progress of research on multiple deaths of NPCs in IVDD to provide guidance for clinical treatment.

Homoplantaginin alleviates intervertebral disc degeneration by blocking the NF-κB/MAPK pathways via binding to TAK1

Intervertebral disc degeneration (IVDD) is a common degenerative disease which is closely related to low back pain (LBP) and brings huge economic and social burdens. In this study, we explored the therapeutic effects of Homoplantaginin (Hom) for IVDD due to its convincing anti-inflammatory and antioxidant functions. TNF-α was used to simulate the inflammatory environment for nucleus pulposus (NP) cells in vitro. We verified that Hom could alleviate the TNF-α-induced inflammation and disturbance of ECM homeostasis through blocking the NF-κB/MAPK signaling pathways. Subsequently, we screened the binding targets of Hom and confirmed that Hom could directly bind to TAK1 and inhibit its phosphorylation to down-regulate the inflammation-related pathways. The therapeutic effects of Hom on IVDD were further validated through a needle puncture rat model in vivo. Overall, Hom was a promising small molecule for IVDD early intervention, possessing huge clinical translational value.

Identification and validation of ferroptosis-related lncRNA signature in intervertebral disc degeneration

Low back pain influences people of every age and is one of the major contributors to the global cost of illness. Intervertebral disc degeneration (IVDD) is a major contributor to low back pain, but its pathogenesis is unknown. Recently, ferroptosis has been shown to have a substantial role in modulating IVDD progression. However, the function of ferroptosis-related long non-coding RNAs (lncRNAs) has rarely been reported in IVDD. Consequently, the research was conducted to explore the ferroptosis-related lncRNA signature in the IVDD occurrence and development. We analyzed two datasets (GSE167199 and GSE167931) archived in the NCBI Gene Expression Omnibus (GEO) public database. We screened differentially expressed genes (DEGs) and differentially expressed lncRNAs (DELncs) in these datasets using the limma package. Ferroptosis-related genes (FRGs) were derived from the FerrDb V2 website and the intersection of DEGs and FRGs was considered as differentially expressed ferroptosis-related genes (DFGs). These genes were then subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis. Correlations between DFGs and DELncs were shown by Pearson test to determine differential expression of ferroptosis-related lncRNAs. The Pearson test showed that CPEB1-HTR2A-AS1 and ACSL3-DNAJC27-AS1 pairs had correlation coefficients over 0.9. Twenty ferroptosis-related lncRNAs were identified and validated in IVDD. Eight of these lncRNAs were upregulated in IVDD nucleus pulposus cells, including HTR2A-AS1, MIF-AS1, SLC8A1-AS1, LINC00942, DUXAP8, LINC00161, LUCAT1 and LINC01615. Twelve were downregulated in IVDD nucleus pulposus cells, including DNAJC27-AS1, H19, LINC01588, LINC02015, FLNC1, CARMN, PRKG1-AS1, APCDD1L-DT, LINC00839, LINC00536, LINC00710 and LINC01535. Eighteen of the 20 lncRNAs (excluding H19 and LUCAT1) were identified as ferroptosis-related lncRNAs for the first time and verified in IVDD. We have identified a ferroptosis-related lncRNA signature involved in IVDD and revealed a close relationship between CPEB1 and HTR2A-AS1, and between ACSL3 and DNAJC27-AS1. Our findings indicate that ferroptosis-related lncRNAs are a new target set for the early detection and therapy of IVDD.

MIF inhibition attenuates intervertebral disc degeneration by reducing nucleus pulposus cell apoptosis and inflammation

Nucleus pulposus cells (NPCs) apoptosis and inflammation are the extremely critical factors of intervertebral disc degeneration (IVDD). Nevertheless, the underlying procedure remains mysterious. Macrophage migration inhibitory factor (MIF) is a cytokine that promotes inflammation and has been demonstrated to have a significant impact on apoptosis and inflammation. For this research, we employed a model of NPCs degeneration stimulated by lipopolysaccharides (LPS) and a rat acupuncture IVDD model to examine the role of MIF in vitro and in vivo, respectively. Initially, we verified that there was a significant rise of MIF expression in the NP tissues of individuals with IVDD, as well as in rat models of IVDD. Furthermore, this augmented expression of MIF was similarly evident in degenerated NPCs. Afterwards, it was discovered that ISO-1, a MIF inhibitor, effectively decreased the quantity of cells undergoing apoptosis and inhibited the release of inflammatory molecules (TNF-α, IL-1β, IL-6). Furthermore, it has been shown that the PI3K/Akt pathway plays a vital part in the regulation of NPCs degeneration by MIF. Ultimately, we showcased that the IVDD process was impacted by the MIF inhibitor in the rat model. In summary, our experimental results substantiate the significant involvement of MIF in the degeneration of NPCs, and inhibiting MIF activity can effectively mitigate IVDD.

siRNA incorporated in slow-release injectable hydrogel continuously silences DDIT4 and regulates nucleus pulposus cell pyroptosis through the ROS/TXNIP/NLRP3 axis to alleviate intervertebral disc degeneration

Aims

In this investigation, we administered oxidative stress to nucleus pulposus cells (NPCs), recognized DNA-damage-inducible transcript 4 (DDIT4) as a component in intervertebral disc degeneration (IVDD), and devised a hydrogel capable of conveying small interfering RNA (siRNA) to IVDD.

Methods

An in vitro model for oxidative stress-induced injury in NPCs was developed to elucidate the mechanisms underlying the upregulation of DDIT4 expression, activation of the reactive oxygen species (ROS)-thioredoxin-interacting protein (TXNIP)-NLRP3 signalling pathway, and nucleus pulposus pyroptosis. Furthermore, the mechanism of action of small interfering DDIT4 (siDDIT4) on NPCs in vitro was validated. A triplex hydrogel named siDDIT4@G5-P-HA was created by adsorbing siDDIT4 onto fifth-generation polyamidoamine (PAMAM) dendrimer using van der Waals interactions, and then coating it with hyaluronic acid (HA). In addition, we established a rat puncture IVDD model to decipher the hydrogel's mechanism in IVDD.

Results

A correlation between DDIT4 expression levels and disc degeneration was shown with human nucleus pulposus and needle-punctured rat disc specimens. We confirmed that DDIT4 was responsible for activating the ROS-TXNIP-NLRP3 axis during oxidative stress-induced pyroptosis in rat nucleus pulposus in vitro. Mitochondria were damaged during oxidative stress, and DDIT4 contributed to mitochondrial damage and ROS production. In addition, siDDIT4@G5-P-HA hydrogels showed good delivery activity of siDDIT4 to NPCs. In vitro studies illustrated the potential of the siDDIT4@G5-P-HA hydrogel for alleviating IVDD in rats.

Conclusion

DDIT4 is a key player in mediating pyroptosis and IVDD in NPCs through the ROS-TXNIP-NLRP3 axis. Additionally, siDDIT4@G5-P-HA hydrogel has been found to relieve IVDD in rats. Our research offers an innovative treatment option for IVDD.

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.

Regulation of endoplasmic reticulum stress on autophagy and apoptosis of nucleus pulposus cells in intervertebral disc degeneration and its related mechanisms

Intervertebral disc degeneration (IVDD) is a common and frequent disease in orthopedics, which seriously affects the quality of life of patients. Endoplasmic reticulum stress (ERS)-regulated autophagy and apoptosis play an important role in nucleus pulposus (NP) cells in IVDD. Hypoxia and serum deprivation were used to induce NP cells. Cell counting kit-8 (CCK-8) assay was used to detect cell activity and immunofluorescence (IF) was applied for the appraisement of glucose regulated protein 78 (GRP78) and green fluorescent protein (GFP)-light chain 3 (LC3). Cell apoptosis was detected by flow cytometry and the expression of LC3II/I was detected by western blot. NP cells under hypoxia and serum deprivation were induced by lipopolysaccharide (LPS), and intervened by ERS inhibitor (4-phenylbutyric acid, 4-PBA) and activator (Thapsigargin, TP). Then, above functional experiments were conducted again and western blot was employed for the evaluation of autophagy-, apoptosis and ERS-related proteins. Finally, NP cells under hypoxia and serum deprivation were stimulated by LPS and intervened using apoptosis inhibitor z-Val-Ala-DL-Asp-fluoromethyl ketone (Z-VAD-FMK) and autophagy inhibitor 3-methyladenine (3-MA). CCK-8 assay, IF, flow cytometry and western blot were performed again. Besides, the levels of inflammatory cytokines were measured with enzyme-linked immunosorbent assay (ELISA) and the protein expressions of programmed death markers were estimated with western blot. It showed that serum deprivation induces autophagy and apoptosis. ERS was significantly activated by LPS in hypoxic and serum deprivation environment, and autophagy and apoptosis were significantly promoted. Overall, ERS affects the occurrence and development of IVDD by regulating autophagy, apoptosis and other programmed death.

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.

Sympathetic Neurotransmitter, VIP, Delays Intervertebral Disc Degeneration via FGF18/FGFR2-Mediated Activation of Akt Signaling Pathway

Neuromodulation-related intervertebral disc degeneration (IVDD) is a novel IVDD pattern and are proposed recently. However, the mechanistic basis of neuromodulation and intervertebral disc (IVD) homeostasis remains unclear. Here, this study aimed to investigate the expression of postganglionic sympathetic nerve fiber-derived vasoactive intestinal peptide (VIP) system in human IVD tissue, and to assess the role of VIP-related neuromodulation in IVDD. Patient samples and in vitro cell experiments showed that the expression of receptors for VIP is negatively correlated with the severity of IVDD, and the administration of exogenous VIP can ameliorate interleukin 1β-induced nucleus pulposus (NP) cell apoptosis and inflammation. Further mRNA-seq analysis revealed that fibroblast growth factor 18- (FGF18)-mediated activation of V-akt murine thymoma viral oncogene homolog signaling pathway is involved in the protective effects of VIP on inflammation-induced NP cell degeneration. Further analysis identified VIP via its receptor vasoactive intestinal peptide receptor 2 can directly result in decreased expression of miR-15a-5p, which targeted FGF18. Finally, in vivo mice lumbar IVDD model confirmed that focally exogenous administration of VIP can effectively ameliorated the progression of IVDD, as shown by the radiological and histological analysis. In conclusion, these results indicated that sympathetic neurotransmitter, VIP, delayed IVDD via FGF18/FGFR2-mediated activation of V-akt murine thymoma viral oncogene homolog signaling pathway, which will broaden the horizon concerning how the neuromodulation correlates with IVDD and shed new light on novel therapeutical alternatives to IVDD.

Interleukin-17 alleviates erastin-induced alveolar bone loss by suppressing ferroptosis via interaction between NRF2 and p-STAT3

AIM

To investigate the relationship between interleukin-17 (IL-17), ferroptosis and osteogenic differentiation.

MATERIALS AND METHODS

We first analysed the changes in ferroptosis-related molecules in experimental periodontitis models. The effects of erastin, a small-molecule ferroptosis inducer, and IL-17 on alveolar bone loss and repair in animal models were then investigated. Primary mouse mandibular osteoblasts were exposed to erastin and IL-17 in vitro. Ferroptosis- and osteogenesis-related genes and proteins were detected. Further, siRNA, immunofluorescence co-localization and immunoprecipitation were used to confirm the roles of the nuclear factor erythroid-2-related factor 2 (NRF2) and phosphorylated signal transducer and activator of transcription 3 (p-STAT3), as well as their interaction.

RESULTS

The levels of NRF2, glutathione peroxidase 4 and solute carrier family 7 member 11 were lower in the ligated tissues than in normal periodontal tissues. Alveolar bone loss in an in vivo experimental periodontitis model was aggravated by erastin and alleviated by IL-17. In vitro, IL-17 ameliorated erastin-inhibited osteogenic differentiation by reversing ferroptosis. Altered NRF2 expression correlated with changes in ferroptosis-related molecules and osteogenesis. Furthermore, the physical interaction between NRF2 and p-STAT3 was confirmed in the nucleus. In IL-17 + erastin-stimulated osteoblasts, the p-STAT3-NRF2 complex might actively participate in the downstream transcription of ferroptosis- and osteogenesis-related genes.

CONCLUSIONS

IL-17 administration conferred resistance to erastin-induced osteoblast ferroptosis and osteogenesis. The possible mechanism may involve p-STAT3 directly interacting with NRF2.

From drugs to biomaterials: a review of emerging therapeutic strategies for intervertebral disc inflammation

Chronic low back pain (LBP) is an increasingly prevalent issue, especially among aging populations. A major underlying cause of LBP is intervertebral disc degeneration (IDD), often triggered by intervertebral disc (IVD) inflammation. Inflammation of the IVD is divided into Septic and Aseptic inflammation. Conservative therapy and surgical treatment often fail to address the root cause of IDD. Recent advances in the treatment of IVD infection and inflammation range from antibiotics and small-molecule drugs to cellular therapies, biological agents, and innovative biomaterials. This review sheds light on the complex mechanisms of IVD inflammation and physiological and biochemical processes of IDD. Furthermore, it provides an overview of recent research developments in this area, intending to identify novel therapeutic targets and guide future clinical strategies for effectively treating IVD-related conditions.

Regulating inflammation and apoptosis: A smart microgel gene delivery system for repairing degenerative nucleus pulposus

The progression of intervertebral disc degeneration (IDD) is attributed to the gradual exacerbation of cellular apoptosis and impaired extracellular matrix (ECM) synthesis, both of which are induced by progressive inflammation. Therefore, it is crucial to address the inflammatory microenvironment and rectify the excessive apoptosis of nucleus pulposus cells (NPCs) to achieve intervertebral disc (IVD) regeneration. In this study, we devised a smart microgel gene delivery system that incorporates functionalized gene nanoparticles (NPs) for the purpose of IVD regeneration. siGrem1 was loaded into the NPs to enhance their antiapoptotic ability and protective effects. Furthermore, the encapsulation of HADA further endows the NPs (referred to as HSGN) with targeted delivery and anti-inflammatory effects, as well as reactive oxygen species (ROS) scavenging capacities. To create an microenvironment-responsive microgel system, phenylboronic acid-functionalized microspheres (referred to as M.S.) were fabricated and dynamically loaded with the HSGN. This microgel system (MHSGN), which is highly biocompatible, enables the sustained release of siGrem1, effectively modulating inflammation, scavenging ROS, and alleviating apoptosis in NPCs. These multifunctional capabilities promote the restoration of metabolic homeostasis within the nucleus pulposus ECM, ultimately leading to delayed IDD.

Mesenchymal stem cell exosomes inhibit nucleus pulposus cell apoptosis via the miR-125b-5p/TRAF6/NF-κB pathway axis

Intervertebral disc degeneration (IVDD) is the pathological basis of a range of degenerative spinal diseases and is the primary cause of lower back pain. Mesenchymal stem cell (MSC) transplantation inhibits IVDD progression. However, the specific mechanisms that underlie these effects remain unclear. In this study, candidate microRNAs (miRNAs) are screened using bioinformatics and high-throughput sequencing. TNF-α is used to induce nucleus pulposus cell (NPC) degeneration. MSC-derived exosomes (MSC-exosomes) are obtained using high-speed centrifugation and identified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blot analysis. Cell viability is determined by CCK-8 assay. Flow cytometry and TUNEL assays are used to detect cell apoptosis. The expression levels of miR-125b-5p are detected by RT-qPCR, and a dual-luciferase gene reporter assay confirms the downstream target genes of miR-125b-5p. Protein expression is determined by western blot analysis. Rat models are used to validate the function of miR-125b-5p in MSC-exosomes. The results show that miR-125b-5p is expressed at low levels in degenerated disc tissues compared with that in normal disc tissues; however, it is highly expressed in MSC-exosomes. Furthermore, MSC-exosomes are efficiently taken up by NPCs while miR-125b-5p is delivered into NPCs; thus, MSC-exosomes act as inhibitors of apoptosis in NPCs. Overexpression of miR-125b-5p downregulates TRAF6 expression and inhibits NF-κB activation. However, TRAF6 overexpression reverses these effects of miR-125b-5p. We demonstrate that MSC-exosomes attenuate IVDD in vivo by delivering miR-125b-5p. MSC-exosomes can deliver miR-125b-5p to target TRAF6, inhibit NF-κB activation, and attenuate the progression of IVDD.

Identification and analysis of key genes in adipose tissue for human obesity based on bioinformatics

BACKGROUND

Obesity is a complex condition that is affected by a variety of factors, including the environment, behavior, and genetics. However, the genetic mechanisms underlying obesity remains poorly elucidated. Therefore, our study aimed at identifying key genes for human obesity using bioinformatics analysis.

METHODS

The microarray datasets of adipose tissue in humans were downloaded from the Gene Expression Omnibus (GEO) database. After the selection of differentially expressed genes (DEGs), we used Lasso regression and Support Vector Machine (SVM) algorithm to further identify the feature genes. Moreover, immune cell infiltration analysis, gene set variation analysis (GSVA), GeneCards database and transcriptional regulation analysis were conducted to study the potential mechanisms by which the feature genes may impact obesity. We utilized receiver operating characteristic (ROC) curve to analysis the diagnostic efficacy of feature genes. Finally, we verified the feature genes in cell experiments and animal experiments. The statistical analyses in validation experiments were conducted using SPSS version 28.0, and the graph were generated using GraphPad Prism 9.0 software. The bioinformatics analyses were conducted using R language (version 4.2.2), with a significance threshold of p < 0.05 used.

RESULTS

199 DEGs were selected using Limma package, and subsequently, 5 feature genes (EGR2, NPY1R, GREM1, BMP3 and COL8A1) were selected through Lasso regression and SVM algorithm. Through various bioinformatics analyses, we found some signaling pathways by which feature genes influence obesity and also revealed the crucial role of these genes in the immune microenvironment, as well as their strong correlations with obesity-related genes. Additionally, ROC curve showed that all the feature genes had good predictive and diagnostic efficiency in obesity. Finally, after validation through in vitro experiments, EGR2, NPY1R and GREM1 were identified as the key genes.

CONCLUSIONS

This study identified EGR2, GREM1 and NPY1R as the potential key genes and potential diagnostic biomarkers for obesity in humans. Moreover, EGR2 was discovered as a key gene for obesity in human adipose tissue for the first time, which may provide novel targets for diagnosing and treating obesity.

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.

Diagnostic model based on key autophagy-related genes in intervertebral disc degeneration

BACKGROUND

Current research on autophagy is mainly focused on intervertebral disc tissues and cells, while there is few on human peripheral blood sample. therefore, this study constructed a diagnostic model to identify autophagy-related markers of intervertebral disc degeneration (IVDD).

METHODS

GSE150408 and GSE124272 datasets were acquired from the Gene Expression Omnibus database, and differential expression analysis was performed. The IVDD-autophagy genes were obtained using Weighted Gene Coexpression Network Analysis, and a diagnostic model was constructed and validated, followed by Gene Set Variation Analysis (GSVA) and Gene Set Enrichment Analysis (GSEA). Meanwhile, miRNA-gene and transcription factor-gene interaction networks were constructed. In addition, drug-gene interactions and target genes of methylprednisolone and glucosamine were analyzed.

RESULTS

A total of 1,776 differentially expressed genes were identified between IVDD and control samples, and the composition of the four immune cell types was significantly different between the IVDD and control samples. The Meturquoise and Mebrown modules were significantly related to immune cells, with significant differences between the control and IVDD samples. A diagnostic model was constructed using five key IVDD-autophagy genes. The area under the curve values of the model in the training and validation datasets were 0.907 and 0.984, respectively. The enrichment scores of the two pathways were significantly different between the IVDD and healthy groups. Eight pathways in the IVDD and healthy groups had significant differences. A total of 16 miRNAs and 3 transcription factors were predicted to be of great value. In total, 84 significantly related drugs were screened for five key IVDD-autophagy genes in the diagnostic model, and three common autophagy-related target genes of methylprednisolone and glucosamine were predicted.

CONCLUSION

This study constructs a reliable autophagy-related diagnostic model that is strongly related to the immune microenvironment of IVD. Autophagy-related genes, including PHF23, RAB24, STAT3, TOMM5, and DNAJB9, may participate in IVDD pathogenesis. In addition, methylprednisolone and glucosamine may exert therapeutic effects on IVDD by targeting CTSD, VEGFA, and BAX genes through apoptosis, as well as the sphingolipid and AGE-RAGE signaling pathways in diabetic complications.

The antioxidant Glycitin protects against intervertebral disc degeneration through antagonizing inflammation and oxidative stress in nucleus pulposus cells

Intervertebral disc degeneration (IVDD) is a kind of typical degenerative disorder of the skeletal muscle system caused by many factors including aging, abnormal mechanical stress and inflammatory responses. Glycitin is a natural isoflavone extracted from legumes. Previous studies have found that it is anti-inflammatory and promotes wound repair. However, the role of Glycitin in IVDD has not been elucidated. In the present research, we were surprised that Glycitin antagonized the NF-κB pathway activity. In addition, we also found that Glycitin alleviated TNF-α-induced metabolic disorders, extracellular matrix degradation, oxidative stress, inflammation responses, and mitochondrial damage. Furthermore, in in vivo experimental study, we discovered Glycitin attenuated IVDD. The results revealed that Glycitin alleviated the degenerative phenotype of IVDD. According to this research, Glycitin has anti-inflammatory properties that might exert a protective function in IVDD, suggesting a prospective therapeutic approach for IVDD.

Verapamil attenuates intervertebral disc degeneration by suppressing ROS overproduction and pyroptosis via targeting the Nrf2/TXNIP/NLRP3 axis in four-week puncture-induced rat models both in vivo and in vitro

Low back pain is usually caused by intervertebral disc degeneration (IVDD), during which the involvement of oxidation system imbalance and inflammasome activation cannot be neglected. In this study, we aimed to validate the expression level of TXNIP in IVDD and investigate the function and potential mechanism of action of verapamil. TXNIP is upregulated in the degenerate nucleus pulposus in both humans and rats, as well as in tert-butyl hydroperoxide (TBHP)-stimulated nucleus pulposus cells. Administration of verapamil, a classic clinical drug, mitigated the TBHP-induced overproduction of reactive oxygen species and activation of the NLRP3 inflammasome, thus protecting cells from pyroptosis, apoptosis, and extracellular matrix degradation. The Nrf2/TXNIP/NLRP3 axis plays a major role in verapamail-mediated protection. In vivo, a puncture-induced IVDD rat model was constructed, and we found that verapamil delayed the development of IVDD at both the imaging and histological levels. In summary, our results indicate the potential therapeutic effects and mechanisms of action of verapamil in the treatment of IVDD.