MicroRNA in intervertebral disc degeneration

S1PR3 suppresses the inflammatory response and extracellular matrix degradation in human nucleus pulposus cells

Sphingosine 1-phosphate receptor 3 (S1PR3) participates in the inflammatory response in multiple types of diseases. However, the biological role of S1PR3 in intervertebral disc degeneration and the underlying mechanism are unclear. The aim of the present study was to investigate the functional role and the mechanism of S1PR3 in lipopolysaccharide (LPS)-induced human nucleus pulposus cells. The expression of S1PR3 and Toll-like receptor (TLR) 2 in LPS-induced nucleus pulposus (NP) cells was investigated using western blotting. The Cell Counting Kit-8 assay was used to detect cell proliferation, and the levels of inflammatory factors were detected using ELISA. Flow cytometry and western blotting were used for the assessment of apoptosis. The deposition of extracellular matrix (ECM) proteins was investigated using reverse transcription-quantitative PCR and western blotting. In addition, western blotting was used to investigate the protein expression levels of phosphorylated (p)-STAT3, STAT3, p-JNK, JNK, p-ERK, ERK, p-p38 and p38associated with STAT3 and MAPK signaling. S1PR3 expression was reduced, while TLR2 expression was elevated in LPS-induced human nucleus pulposus cells (HNPC). S1PR3 overexpression increased HNPC viability, inhibited the inflammatory response and suppressed apoptosis. Meanwhile, S1PR3 overexpression regulated the expression of ECM-related proteins. Additionally, overexpression of S1PR3 inhibited the expression of the TLR2-regulated STAT3 and MAPK pathways in LPS-induced HNPCs. Furthermore, TLR2 overexpression partially offset the impacts of S1PR3 overexpression on HNPC viability, apoptosis level, inflammation and as ECM degradation. In conclusion, STAT3 overexpression suppressed viability injury, the inflammatory response and the level of apoptosis and alleviated ECM protein deposition in HNPCs through the TLR2/STAT3 and TLR2/MAPK pathways, which may offer a promising candidate for the amelioration of intervertebral disc degeneration.

Single-cell RNA-seq analysis reveals the Wnt/Ca2+ signaling pathway with inflammation, apoptosis in nucleus pulposus degeneration

BACKGROUND

Increasing studies have shown degeneration of nucleus pulposus cells (NPCs) as an critical part of the progression of intervertebral disc degeneration (IVDD). However, there are relatively few studies on single-cell transcriptome contrasts in human degenerated NPCs. Moreover, differences in Wnt/Ca2+ signaling in human degenerated nucleus pulposus cells have not been elucidated. The aim of this study is to investigate the differential expression of Wnt/Ca2+ signaling pathway between normal and degenerated nucleus pulposus cells in humans and try to investigate its mechanism.

METHODS

We performed bioinformatics analysis using our previously published findings to construct single cell expression profiles of normal and degenerated nucleus pulposus. Then, in-depth differential analysis was used to characterize the expression of Wnt/Ca2+ signaling pathway between normal and degenerated nucleus pulposus cells in humans.

RESULTS

The obtained cell data were clustered into five different chondrocytes clusters, which chondrocyte 4 and chondrocyte 5 mainly accounted for a high proportion in degenerated nucleus pulposus tissues, but rarely in normal nucleus pulposus tissues. Genes associated within the Wnt/Ca2+ signaling pathway, such as Wnt5B, FZD1, PLC (PLCB1), CaN (PPP3CA) and NAFATC1 are mainly present in chondrocyte 3, chondrocyte 4 and chondrocyte 5 from degenerated nucleus pulposus tissues. In addition, as a receptor that activates Wnt signaling pathway, LRP5 is mainly highly expressed in chondrocyte 5 of degenerated nucleus pulposus cells. Six genes, ANGPTL4, PTGES, IGFBP3, GDF15, TRIB3 and TNFRSF10B, which are associated with apoptosis and inflammatory responses, and are widespread in chondrocyte 4 and chondrocyte 5, may be closely related to degenerative of nucleus pulposus cells.

CONCLUSIONS

Single-cell RNA sequencing revealed differential expression of Wnt/Ca2+ signaling in human normal and degenerated nucleus pulposus cells, and this differential expression may be closely related to the abundance of chondrocyte 4 and chondrocyte 5 in degenerated nucleus pulposus cells. In degenerated nucleus pulposus cells, LRP5 activate Wnt5B, which promotes nucleus pulposus cell apoptosis and inflammatory response by regulating the Wnt/Ca2+ signaling pathway, thereby promoting disc degeneration. ANGPTL4, IGFBP3, PTGES in chondrocyte 4 and TRIB3, GDF15, TNFRSF10B in chondrocyte 5 may play an important role in this process.

MicroRNA-targeting nanomedicines for the treatment of intervertebral disc degeneration

Low back pain stands as a pervasive global health concern, afflicting almost 80% of adults at some point in their lives with nearly 40% attributable to intervertebral disc degeneration (IVDD). As only symptomatic relief can be offered to patients there is a dire need for innovative treatments.Given the accumulating evidence that multiple microRNAs (miRs) are dysregulated during IVDD, they could have a huge potential against this debilitating condition. The way miRs can profoundly modulate signaling pathways and influence several cellular processes at once is particularly exciting to tackle this multifaceted disorder. However, miR delivery encounters extracellular and intracellular biological barriers. A promising technology to address this challenge is the vectorization of miRs within nanoparticles, providing both protection and enhancing their uptake within the scarce target cells of the degenerated IVD. This comprehensive review presents the diverse spectrum of miRs' connection with IVDD and demonstrates their therapeutic potential when vectorized in nanomedicines.

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

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

Investigating the Differential Circulating microRNA Expression in Adolescent Females with Severe Idiopathic Scoliosis: A Proof-of-Concept Observational Clinical Study

Adolescent Idiopathic Scoliosis (AIS) is the most common form of three-dimensional spinal disorder in adolescents between the ages of 10 and 18 years of age, most commonly diagnosed in young women when severe disease occurs. Patients with AIS are characterized by abnormal skeletal growth and reduced bone mineral density. The etiology of AIS is thought to be multifactorial, involving both environmental and genetic factors, but to date, it is still unknown. Therefore, it is crucial to further investigate the molecular pathogenesis of AIS and to identify biomarkers useful for predicting curve progression. In this perspective, the relative abundance of a panel of microRNAs (miRNAs) was analyzed in the plasma of 20 AIS patients and 10 healthy controls (HC). The data revealed a significant group of circulating miRNAs dysregulated in AIS patients compared to HC. Further bioinformatic analyses evidenced a more restricted expression of some miRNAs exclusively in severe AIS females. These include some members of the miR-30 family, which are considered promising regulators for treating bone diseases. We demonstrated circulating extracellular vesicles (EVs) from severe AIS females contained miR-30 family members and decreased the osteogenic differentiation of mesenchymal stem cells. Proteomic analysis of EVs highlighted the expression of proteins associated with orthopedic disease. This study provides preliminary evidence of a miRNAs signature potentially associated with severe female AIS and suggests the corresponding vesicular component may affect cellular mechanisms crucial in AIS, opening the scenario for in-depth studies on prognostic differences related to gender and grade.

microRNA-365 attenuated intervertebral disc degeneration through modulating nucleus pulposus cell apoptosis and extracellular matrix degradation by targeting EFNA3

This present study is aimed to investigate the role of microRNA-365 (miR-365) in the development of intervertebral disc degeneration (IDD). Nucleus pulposus (NP) cells were transfected by miR-365 mimic and miR-365 inhibitor, respectively. Concomitantly, the transfection efficiency and the expression level of miRNA were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Meanwhile, NP cells apoptosis was measured through propidium iodide (PI)-AnnexinV-fluorescein isothiocyanate (FITC) apoptosis detection kit. Subsequently, immunofluorescence (IF) staining was performed to assess the expression of collagen II, aggrecan and matrix metalloproteinase 13 (MMP-13). In addition, bioinformatic prediction and Luciferase reporter assay were used to reveal the target gene of miR-365. Finally, we isolated the primary NP cells from rats and injected NP-miR-365 in rat IDD models. The results showed that overexpression of miR-365 could effectively inhibit NP cells apoptosis and MMP-13 expression and upregulate the expression of collagen II and aggrecan. Conversely, suppression of miR-365 enhanced NP cell apoptosis and elevated MMP-13 expression, but decreased the expression of collagen II and aggrecan. Moreover, the further data demonstrated that miR-365 mediated NP cell degradation through targeting ephrin-A3 (EFNA3). In addition, the cells apoptosis and catabolic markers were increased in NP cells when EFNA3 upregulated. More importantly, the vivo data supported that miR-365-NP cells injection ameliorated IDD in rats models. miR-365 could alleviate the development of IDD by regulating NP cell apoptosis and ECM degradation, which is likely mediated by targeting EFNA3. Therefore, miR-365 may be a promising therapeutic avenue for treatment IDD through EFNA3.

Updates on Pathophysiology of Discogenic Back Pain

Discogenic back pain, a subset of chronic back pain, is caused by intervertebral disc (IVD) degeneration, and imparts a notable socioeconomic health burden on the population. However, degeneration by itself does not necessarily imply discogenic pain. In this review, we highlight the existing literature on the pathophysiology of discogenic back pain, focusing on the biomechanical and biochemical steps that lead to pain in the setting of IVD degeneration. Though the pathophysiology is incompletely characterized, the current evidence favors a framework where degeneration leads to IVD inflammation, and subsequent immune milieu recruitment. Chronic inflammation serves as a basis of penetrating neovascularization and neoinnervation into the IVD. Hence, nociceptive sensitization emerges, which manifests as discogenic back pain. Recent studies also highlight the complimentary roles of low virulence infections and central nervous system (CNS) metabolic state alteration. Targeted therapies that seek to disrupt inflammation, angiogenesis, and neurogenic pathways are being investigated. Regenerative therapy in the form of gene therapy and cell-based therapy are also being explored.

Quercetin ameliorates oxidative stress-induced senescence in rat nucleus pulposus-derived mesenchymal stem cells via the miR-34a-5p/SIRT1 axis

BACKGROUND

Intervertebral disc degeneration (IDD) is a main contributor to low back pain. Oxidative stress, which is highly associated with the progression of IDD, increases senescence of nucleus pulposus-derived mesenchymal stem cells (NPMSCs) and weakens the differentiation ability of NPMSCs in degenerated intervertebral discs (IVDs). Quercetin (Que) has been demonstrated to reduce oxidative stress in diverse degenerative diseases.

AIM

To investigate the role of Que in oxidative stress-induced NPMSC damage and to elucidate the underlying mechanism.

METHODS

In vitro, NPMSCs were isolated from rat tails. Senescence-associated β-galactosidase (SA-β-Gal) staining, cell cycle, reactive oxygen species (ROS), real-time quantitative polymerase chain reaction (RT-qPCR), immunofluorescence, and western blot analyses were used to evaluated the protective effects of Que. Meanwhile the relationship between miR-34a-5p and Sirtuins 1 (SIRT1) was evaluated by dual-luciferase reporter assay. To explore whether Que modulates tert-butyl hydroperoxide (TBHP)-induced senescence of NPMSCs via the miR-34a-5p/SIRT1 pathway, we used adenovirus vectors to overexpress and downregulate the expression of miR-34a-5p and used SIRT1 siRNA to knockdown SIRT1 expression. In vivo, a puncture-induced rat IDD model was constructed, and X rays and histological analysis were used to assess whether Que could alleviate IDD in vivo.

RESULTS

We found that TBHP can cause NPMSCs senescence changes, such as reduced cell proliferation ability, increased SA-β-Gal activity, cell cycle arrest, the accumulation of ROS, and increased expression of senescence-related proteins. While abovementioned senescence indicators were significantly alleviated by Que treatment. Que decreased the expression levels of senescence-related proteins (p16, p21, and p53) and senescence-associated secreted phenotype (SASP), including IL-1β, IL-6, and MMP-13, and it increased the expression of SIRT1. In addition, the protective effects of Que on cell senescence were partially reversed by miR-34a-5p overexpression and SIRT1 knockdown. In vivo, X-ray, and histological analyses indicated that Que alleviated IDD in a puncture-induced rat model.

CONCLUSION

In summary, the present study provides evidence that Que reduces oxidative stress-induced senescence of NPMSCs via the miR-34a/SIRT1 signaling pathway, suggesting that Que may be a potential agent for the treatment of IDD.

Role of non‑coding RNAs in cartilage endplate (Review)

Cartilage endplate (CEP) degeneration is considered one of the major causes of intervertebral disc degeneration (IDD), which causes non-specific neck and lower back pain. In addition, several non-coding RNAs (ncRNAs), including long ncRNAs, microRNAs and circular RNAs have been shown to be involved in the regulation of various diseases. However, the particular role of ncRNAs in CEP remains unclear. Identifying these ncRNAs and their interactions may prove to be is useful for the understanding of CEP health and disease. These RNA molecules regulate signaling pathways and biological processes that are critical for a healthy CEP. When dysregulated, they can contribute to the development disease. Herein, studies related to ncRNAs interactions and regulatory functions in CEP are reviewed. In addition, a summary of the current knowledge regarding the deregulation of ncRNAs in IDD in relation to their actions on CEP cell functions, including cell proliferation, apoptosis and extracellular matrix synthesis/degradation is presented. The present review provides novel insight into the pathogenesis of IDD and may shed light on future therapeutic approaches.

Repair of degenerative nucleus pulposus by polyphenol nanosphere-encapsulated hydrogel gene delivery system

Intervertebral disc degeneration (IDD) progresses due to local inflammatory response, gradually unbalanced anabolic/catabolic activity, and progressive functional impairment within the nucleus pulposus. Antagomir-21, a cholesterol-modified miRNA-21 inhibitor, has potential extracellular matrix (ECM) regenerative ability, but its application for IDD is limited by inadequate local delivery systems. An injectable hydrogel gene delivery system encapsulating a modified tannic acid nanoparticles (TA NPs) vector was engineered for on-demand and sustained delivery of antagomir-21 into the nucleus pulposus. After nucleus pulposus cell uptake, antagomir-21 was released from TA NPs and regulated the ECM metabolic balance by inhibiting the MAPK/ERK signaling pathway. TA NPs scavenged intracellular ROS and reduced inflammation by downregulating TNF-α expression. In vivo, synergistic anti-inflammatory effects and ECM regeneration effectively promoted therapeutic efficacy against IDD. This hydrogel gene delivery system represents a creative, promising strategy for IDD repair.

Codelivery of TGF-β1 and anti-miR-141 by PLGA microspheres inhibits progression of intervertebral disc degeneration

BACKGROUND

Cervical and lumbar pain is usually caused by degeneration of the nucleus pulposus (NP). As a powerful therapeutic strategy, tissue engineering can effectively restore the normal biological properties of the spinal unit. Previous studies suggested that poly(lactic-co-glycolic acid) (PLGA) microspheres are effective carriers of cells and biomolecules in NP tissue engineering. This study aims to explore the therapeutic effect of PLGA microspheres coloaded with transforming growth factor-β1 (TGF-β1) and anti-miR-141 on intervertebral disc degeneration (IDD).

METHODS

PLGA microspheres were characterized by scanning electron microscopy, a laser particle size analyzer, and laser confocal microscopy. The in vitro release rate of biomolecules from the microspheres was analyzed by reversed-phase high-performance liquid chromatography and agarose gel electrophoresis. The rat NP cells (NPCs) treated with the solutions released from microspheres for different lengths of time were assigned to a control group (Ctrl), an empty PLGA microsphere group (Mock microsphere, MS), a TGF-β1-loaded PLGA microsphere group (TMS), an anti-miR-141-loaded PLGA microsphere group (AMS), and an anti-miR-141 + TGF-β1-loaded PLGA microsphere group (ATMS). The proliferation and apoptosis of NPCs were observed by alamar blue and flow cytometry. The gene and protein expression of cartilage markers COL2A1 and ACAN were observed by RT-qPCR and Western blot. The rat model of IDD was established by tail puncture. Rats were divided into a control group (Ctrl), a mock operation group (Mock), a TGF-β1 microsphere group (TMS), an anti-miR-141 microsphere group (AMS), and an anti-miR-141 + TGF-β1 microsphere group (ATMS). The degree of rat tail IDD was assessed in each group through magnetic resonance imaging (MRI), safranin O-fast green staining, immunohistochemistry, and Western blotting.

RESULTS

PLGA microspheres were stably coloaded and could sustainably release TGF-β1 and anti-miR-141. The results of in vitro cell experiments showed that the release solution of PLGA microspheres significantly enhanced the proliferation of NPCs without inducing their apoptosis and significantly upregulated cartilage markers in NPCs. The effect of microspheres was greater in the ATMS group than that in the TMS group and AMS group. In vivo experiments showed that IDD could be effectively inhibited and reversed by adding microspheres coloaded with TGF-β1 and/or anti-miR-141, and the effect was greatest in the ATMS group.

CONCLUSION

PLGA microspheres coloaded with TGF-β1 and anti-miR-141 can reverse IDD by inhibiting the degeneration of NPCs.

Whole-transcriptome sequencing identifies key differentially expressed circRNAs/lncRNAs/miRNAs/mRNAs and linked ceRNA networks in adult degenerative scoliosis

Background

Adult degenerative scoliosis (ADS) is forecast to be a prevalent disabling condition in an aging society. Universally, its pathogenesis is perceived as intervertebral disc degeneration (IDD), however, a thought-provoking issue is why precisely a subset of patients with disc degeneration develop ADS. Exploring the diversities between common IDD and ADS would contribute to unraveling the etiological mechanisms of ADS. Therefore, we aimed to integrate the circRNA, lncRNA, miRNA, and mRNA expression profiles from normal adults (Normal), patients with lumbar disc herniation (LDH), and ADS by whole transcriptome sequencing, which identifies critical functional ncRNA and ceRNA networks and crosstalk between the various transcripts.

Methods

The fresh whole blood samples (n = 3/group) were collected from ADS patients, LDH patients, and healthy volunteers (Normal group), which were examined for mRNA, miRNA, lncRNA, and circRNA expression and screened for differentially expressed (DE) ncRNAs. Then, Gene Ontology (GO) and KEGG analyses were performed for gene annotation and enrichment pathways on the DE RNAs, which were constructed as a lncRNA-miRNA-mRNA network. Eventually, DE RNAs were validated by qRT-PCR targeting disc nucleus pulposus (NP) tissue in ADS and LDH group (n = 10/group).

Results

Compared to the LDH group, we identified 3322 DE mRNAs, 221 DE lncRNAs, 20 DE miRNAs, and 15 DE circRNAs in the ADS. In contrast to Normal, 21 miRNAs and 19 circRNAs were differentially expressed in the ADS. The expression of multiple differentially expressed ncRNAs was confirmed by qRT-PCR analysis to be consistent with the sequencing results. In addition, GO, and KEGG analysis demonstrated that most DE mRNAs and ncRNAs target genes are involved in various biological processes, including Endocytosis, Apoptosis, Rap1 signaling pathway, Notch signaling pathway, and others. The constructed lncRNA-miRNA-mRNA co-expression network was primarily related to angiogenesis and regulation.

Conclusion

By focusing on comparing asymmetric and symmetric disc degeneration, whole-transcriptome sequencing and bioinformatics analysis systematically screened for key ncRNAs in the development of ADS, which provided an abundance of valuable candidates for the elucidation of regulatory mechanisms. The DE ncRNAs and the lncRNA-miRNA-mRNA network are intrinsically involved in the regulation of mediator and angiogenesis, which may contribute to the insight into the pathogenesis of ADS.

Extracellular vesicles derived from mesenchymal stem cells confer protection against intervertebral disc degeneration through a microRNA-217-dependent mechanism

OBJECTIVE

Extracellular vesicles released by mesenchymal stem cells (MSC-EVs) can be applied to alleviate intervertebral disc degeneration (IVDD) by curbing apoptosis of nucleus pulposus cells (NPCs). The current study aims to evaluate the effect of MSC-EVs on NPC apoptosis and IVDD and the related regulatory mechanisms involving microRNA (miR)-217.

METHOD

Expression of miR-217 was examined in tumor necrosis factor-α (TNF-α)-induced NPCs and MSC-EVs, followed by identification in the relationship between miR-217, enhancer of zeste homolog 2 (EZH2) and forkhead box O-3 (FOXO3). After isolation of EVs from MSCs and subsequent co-culture with NPCs, we assessed effects of miR-217 on NPC viability, autophagy, senescence and apoptosis along with extracellular matrix (ECM) degradation. Further in vivo experiments were conducted in rat models of IVDD to substantiate the effect of miR-217 on IVDD.

RESULTS

Poor miR-217 expression was found in TNF-α-induced NPCs, while high miR-217 expression was identified in MSC-EVs (P < 0.05). MSC-EVs transferred miR-217 to NPCs and increased its expression, thus attenuating NPC apoptosis and ECM degradation (elevated collagen II and aggrecan but reduced MMP13 and ADAMTS5) (P < 0.05). miR-217 targeted EZH2, and EZH2 bound to the FOXO3 promoter and consequently downregulated its expression. FOXO3 restrained NPC apoptosis and ECM degradation by stimulating cell autophagy (P < 0.05). Furthermore, in vivo experimental results confirmed the suppressive role of miR-217 shuttled by MSC-EVs in IVDD.

CONCLUSION

Overall, the delivery of miR-217 may be a novel mechanism underlying the effect of MSC-EVs on NPC apoptosis and ECM degradation following IVDD.

miR-328-5p Induces Human Intervertebral Disc Degeneration by Targeting WWP2

Intervertebral disc degeneration (IDD) development is regulated by miRNA, including inflammatory reactions, cell apoptosis, and degradation of extracellular matrix. Nucleus pulposus cells apoptosis has a absolute influence in the development of IDD. This experiment explores the mechanism of miR-328-5p regulating IDD. Through the analysis of miRNA and mRNA microarray database, we screened the target genes miR-328-5p and WWP2. We verified the expression of miR-328-5p, WWP2, and related apoptotic genes in normal and degenerative nucleus pulposus tissues by qRT-PCR. The expressions of WWP2, Bcl-2, and Bax were detected by qRT-PCR and western blot after transfection to nucleus pulposus cell. The nucleus pulposus cell proliferation and apoptosis after transfection were confirmed by CCK8 and flow cytometry. Luciferase reporter assay and bioinformatics analyzed the targeting relationship between miR-328-5p and WWP2. Firstly, the qRT-PCR experiments confirmed the significant increase of miR-328-5p expression, while significant reduction of WWP2 in a degenerative tissues compared to the normal tissues. Surprisingly, miR-328-5p expression was positively, while that of WWP2 negatively correlated with the degeneration grade of IDD. And we also identified the high expression of Bax and Caspase3, while low expression of Bcl-2 in a degenerative tissues. After miR-328-5p mimic transfected into nucleus pulposus cell, qRT-PCR and western blot confirmed that WWP2 and Bcl-2 expressions were downregulated, while Bax and Caspase3 expressions were upregulated, and the same results were obtained by knocking down WWP2. CCK8 and flow cytometry confirmed that miR-328-5p inhibited the proliferation and induced apoptosis of nucleus pulposus cells. WWP2 is a target gene of miR-328-5p by bioinformatics and luciferase reporter assay. In summary, miR-328-5p targets WWP2 to regulate nucleus pulposus cells apoptosis and then participates in the development of IDD. Furthermore, this study may provide new references and ideas for IDD treatment.

Depleted Long Noncoding RNA GAS5 Relieves Intervertebral Disc Degeneration via microRNA-17-3p/Ang-2

Intervertebral disc degeneration (IVDD) remains a clinical challenge and requires more effective therapeutic targets. Long noncoding RNAs (lncRNAs) have emerged as critical modulators of multiple biological processes, such as cell proliferation and extracellular matrix (ECM) remodeling. Accordingly, the current study sets out to explore the influence of the lncRNA growth arrest-specific 5 (GAS5) on IVDD and investigate the possible involvement of microRNA-17-3p (miR-17-3p)/Angiopoietin-2 (Ang-2) axis. Firstly, the expression patterns of GAS5, miR-17-3p, and Ang-2 were characterized by RNA quantification from the isolated human degenerative nucleus pulposus (NP) tissues. miR-17-3p was found to express at an abnormal low level while GAS5 and Ang-2 expressed at aberrant high level in the human degenerative NP tissues. Utilizing dual-luciferase reporter, RNA immunoprecipitation, and pull-down assays, GAS5 was found to competitively bound to miR-17-3p and further upregulate the expression of Ang-2, a target gene of miR-17-3p. Employing gain- and loss-of-function approaches, their expressions were altered in human degenerative nucleus pulposus cells (NPCs), followed by IL-1β treatment, in order to identify their roles in NP cell proliferation, apoptosis, and ECM metabolism. Silencing of GAS5 expression restrained the levels of cleaved caspase-3, cleaved caspase-7, cleaved caspase-9, MMP3, MMP13, ADAMTS4, and ADAMTS5 and increased collagen II and aggrecan levels. In vitro experiments also revealed that GAS5 depletion inhibited apoptosis and ECM degradation in HDNPCs, while elevating the proliferation through downregulation of Ang-2 by increasing miR-17-3p. Furthermore, in vivo data further validated that either GAS5 silencing or miR-17-3p reexpression alleviated IVDD degree with the help of IVDD mouse models. Altogether, our findings substantiated that downregulation of GAS5 reduced NPC apoptosis and promoted ECM remodeling, ultimately ameliorating the IVDD via miR-17-3p-dependent inhibition of Ang-2. We hope our discoveries offer a fresh molecular insight that can aid the development of novel therapies against IVDD.

MiR-206 improves intervertebral disk degeneration by targeting GJA1

Background

A large amount of evidence suggested that miRNA was involved in the progression of intervertebral disk degeneration (IDD). The purpose of our study was to explore the function and potential mechanism of miR-206/GJA1 axis in IDD.

Methods

IDD nucleus pulposus (NP) cell model was established through treatment of LPS. IDD rat model was established by annulus fibrosus puncture. The expression of miR-206 and GJA1 was detected by RT-PCR, apoptosis was evaluated by flow cytometry or TUNEL, inflammatory factors were tested by ELISA, extracellular matrix related protein expression was detected by western blot, and HE and safranin-O staining were used to assess the pathological changes of IDD.

Results

GJA1 was found to be highly expressed in IDD tissues and LPS-induced NP cells. Down regulation of GJA1 reduced inflammatory factors, inhibited apoptosis and enhanced extracellular matrix in LPS-induced NP cells. MiR-206 was downregulated in IDD tissues and directly targeted GJA1, and the expression of miR-206 was negatively correlated with the expression of GJA1 in IDD tissues. Further, it was demonstrated that overexpression of miR-206 could attenuate LPS-induced NP cell injury by targeting GJA1. In vivo, the upregulation of miR-206 improved IDD and reduced NP cell apoptosis.

Conclusion

Our study showed that miR-206 reduced the level of inflammatory factors, restrained NP cell apoptosis and increases extracellular matrix by targeting GJA1. These data suggested that miR-206/GJA1 might be potential therapeutic targets for IDD.

Differentially Expressed Circular RNAs in Degenerative Diseases Related to Low Back Pain: Potential of Circular RNAs as Biomarkers

Low back pain (LBP) is a main cause of disability around the world. Nevertheless, given the complex pathophysiology of LBP, the etiological diagnosis of LBP is a challenging process. Identifying appropriate biomarkers and/or therapeutic targets is still crucial for LBP research. There has been a growing interest in molecular biomarkers of LBP-related degenerative diseases. Recently, circular RNAs (circRNAs) have received great attention as microRNA (miRNA) sponges that inhibit normal miRNA activity. Due to their abundance and stability, circRNAs are considered as potential diagnostic biomarkers. Indeed, it has been reported that circulating or tissue-specific circRNAs can be used for diagnosing human diseases, including cancers, neurological diseases, and inflammatory diseases. Also of note, from 2015, research on circRNAs involved in LBP-related diseases is very active. Moreover, specific roles of some of the differentially expressed circRNAs have been demonstrated. Thus, the putative involvement of circRNAs in LBP-related diseases may suggest that some of the dysregulated circRNAs may have the potential to serve as therapeutic targets and/or diagnostic biomarkers for LBP. This review summarizes the current progress on differentially expressed circRNAs in diseases related to LBP.

Exosomes Immunity Strategy: A Novel Approach for Ameliorating Intervertebral Disc Degeneration

Low back pain (LBP), which is one of the most severe medical and social problems globally, has affected nearly 80% of the population worldwide, and intervertebral disc degeneration (IDD) is a common musculoskeletal disorder that happens to be the primary trigger of LBP. The pathology of IDD is based on the impaired homeostasis of catabolism and anabolism in the extracellular matrix (ECM), uncontrolled activation of immunologic cascades, dysfunction, and loss of nucleus pulposus (NP) cells in addition to dynamic cellular and biochemical alterations in the microenvironment of intervertebral disc (IVD). Currently, the main therapeutic approach regarding IDD is surgical intervention, but it could not considerably cure IDD. Exosomes, extracellular vesicles with a diameter of 30–150 nm, are secreted by various kinds of cell types like stem cells, tumor cells, immune cells, and endothelial cells; the lipid bilayer of the exosomes protects them from ribonuclease degradation and helps improve their biological efficiency in recipient cells. Increasing lines of evidence have reported the promising applications of exosomes in immunological diseases, and regarded exosomes as a potential therapeutic source for IDD. This review focuses on clarifying novel therapies based on exosomes derived from different cell sources and the essential roles of exosomes in regulating IDD, especially the immunologic strategy.

The Mechanism and Function of miRNA in Intervertebral Disc Degeneration

Intervertebral disc degeneration (IDD) disease has been considered as the main cause of low back pain (LBP), which is a very common symptom and the leading cause of disability worldwide today. The pathological mechanism of IDD remains quite complicated, and genetic, developmental, biochemical, and biomechanical factors all contribute to the development of the disease. There exists no effective, non-surgical treatment for IDD nowadays, which is largely related to the lack of knowledge of the specific mechanisms of IDD, and the lack of effective specific targets. Recently, non-coding RNA, including miRNA, has been recognized as an important regulator of gene expression. Current studies on the effects of miRNA in IDD have confirmed that a variety of miRNAs play a crucial role in the process of IDD via nucleus pulposus cells (NPC) apoptosis, abnormal proliferation, inflammatory factors, the extracellular matrix (ECM) degradation, and annulus fibrosus (AF) degeneration. In the past 10 years, research on miRNA has been quite active in IDD. This review summarizes the current research progression of miRNA in the IDD and puts forward some prospects and challenges on non-surgical treatment for IDD.

LncRNA nuclear receptor subfamily 2 group F member 1 antisense RNA 1 (NR2F1-AS1) aggravates nucleus pulposus cell apoptosis and extracellular matrix degradation

Emerging reports uncover that long noncoding RNAs (lncRNAs) help regulate intervertebral disc degeneration (IVDD). Here, we probe the function of lncRNA nuclear receptor subfamily 2 group F member 1 antisense RNA 1 (NR2F1-AS1) in IVDD. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was applied to verify the expression of NR2F1-AS1 and miR-145-5p in nucleus pulposus (NP) tissues from IVDD patients or NP cells dealt with IL-1β or TNF-α. Flow cytometry or the TdT-mediated dUTP nick end labeling (TUNEL) assay was performed to validate the apoptosis of NP cells with selective regulation of NR2F1-AS1 and miR-145-5p. ECM-related genes, FOXO1, Bax, and Bcl2 were evaluated by qRT-PCR or Western blot (WB). The targeted relationships between NR2F1-AS1 and miR-145-5p, miR-145-5p and FOXO1 were testified by the dual-luciferase reporter assay and the RNA immunoprecipitation (RIP) assay. Our outcomes substantiated that NR2F1-AS1 was up-regulated, while miR-145-5p was down-regulated in intervertebral disc tissues of IVDD patients or NP cells treated with IL-1β or TNF-α. Besides, overexpressing NR2F1-AS1 intensified ECM degradation and NP cell apoptosis induced by IL-1β, while knocking down NR2F1-AS1 or up-regulating miR-145-5p reversed IL-1β-mediated effects in NP cells. Meanwhile, NR2F1-AS1 choked miR-145-5p and abated its effects in NP cells. This study confirms that NR2F1-AS1 modulates IVDD progression by up-regulating the FOXO1 pathway through the sponge of miR-145-5p as a competitive endogenous RNA (ceRNA).

LncRNA OIP5-AS1 accelerates intervertebral disc degeneration by targeting miR-25-3p

It is obvious that epigenetic processes influence the evolution of intervertebral disc degeneration (IDD). However, its molecular mechanisms are poorly understood. Long noncoding RNAs (lncRNAs) have been validated to exert vital roles in IDD. Therefore, we tested the hypothesis that OIP5-AS1, a potential regulator of IDD, modulates IDD progression. RT-PCR was utilized to detect levels of OIP5-AS1, miR-25-3p, Collagen II and Aggrecan in IDD tissues and nucleus pulposus cells (NPCs). Immunofluorescence assay measured Collagen II expression. CCK-8, EdU, and flow cytometry estimated the levels of proliferation and apoptosis. Proteins were assessed via Western blot. The binding affinity of OIP5-AS1 with miR-25-3p was investigated by luciferase reporter assay. Enzyme-linked immunosorbent assay (ELISA) analyzed the levels of inflammatory factors. OIP5-AS1 was high expressed in IDD tissues and its expression gradually promoted with the increasing of Pfirrmann scores. The cell morphology of NPCs changed into spindle-shaped, and Collagen II expression was low. After OIP5-AS1 was silenced, cell proliferation was boosted whereas both apoptosis and extracellular matrix (ECM) degradation were restrained. In LPS-activated NPCs, OIP5-AS1 depletion also suppressed inflammation response. Further, miR-25-3p was a target of OIP5-AS1. The effects of OIP5-AS1 silence on proliferation, apoptosis, and ECM degradation were reversed upon miR-25-3p downregulation. Moreover, the inhibitory impact of OIP5-AS1 knockdown on the inflammation of LPS-treated NPCs was rescued with miR-25-3p inference. In general, lncRNA OIP5-AS1 exerted its effects in IDD by targeting miR-25-3p, implying the usage of OIP5-AS1/miR-25-3p as a novel regulatory axis for the molecular targets of IDD therapy.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The Regulatory Effect of MicroRNA-101-3p on Disc Degeneration by the STC1/VEGF/MAPK Pathway

Aims. Accumulating evidence reported that the microRNA (miRNA) took an important role in intervertebral disc degeneration (IDD). In this study, we revealed a novel miRNA regulatory mechanism in IDD. Main Methods. The miRNA microarray analyses of human degenerated and normal disc samples were employed to screen out the target miRNA. In vitro and in vivo experiments were conducted to verify the regulatory effect of miR-101-3p. Key Findings. The expression level of miR-101-3p was significantly decreased in the degenerated disc samples which were confirmed by qRT-PCR. Moreover, the miR-101-3p expression level was changed dynamically according to the disc degeneration grade. Upregulation of miR-101-3p expression level inhibited cell apoptosis. Furthermore, stanniocalcin-1 (STC1) was selected to be the target gene of miR-101-3p according to the bioinformatic algorithms. Mechanically, upregulation of miR-101-3p significantly decreased the expression of STC1, vascular endothelial growth factor (VEGF), and MAPK pathway expression levels. Therapeutically, in vivo experiment on IDD rat model illustrated that agomir-101-3p could effectively suspend IDD. Significance. Our findings demonstrated that miR-101-3p alleviated IDD process through the STC1/VEGF/MAPK pathway.

Preliminary construction of a regulatory network of miRNAs in the pathogenesis of nucleus pulposus degeneration - a review based on data mining

In this study, we attempted to further collate existing transcriptome sequencing (mRNA-Seq) data by applying data mining and screening intervertebral disc degeneration (IVDD)-related miRNAs. At the same time, combined with published articles, the miRNAs that have been screened out were further excluded, and only the miRNAs confirmed by the reported studies were retained and reviewed. We obtained 12 pro-IVDD miRNAs and ten anti-IVDD miRNAs using the above screening process, involving 33 literature sources. By reviewing and summarizing the above studies, we preliminarily constructed the regulatory network of miRNA in the pathogenesis of IVDD. This regulatory network comprises many gaps and potential miRNA interactions, and these points may be the breakthrough points for further IVDD-related research. This new review approach can also provide a reference for the mechanistic studies of other diseases.

Bone Mesenchymal Stem Cells Promote Extracellular Matrix Remodeling of Degenerated Nucleus Pulposus Cells via the miR-101-3p/EIF4G2 Axis

The etiology of lumbocrural pain is tightly concerned with intervertebral disk degeneration (IDD). Bone mesenchymal stem cell (BMSC)-based therapy bears potentials for IDD treatment. The properties of microRNA (miRNA)-modified BMSCs may be altered. This study investigated the role and mechanism of BMSCs promoting extracellular matrix (ECM) remodeling of degenerated nucleus pulposus cells (NPCs) via the miR-101-3p/EIF4G2 axis. NPCs were collected from patients with IDD and lumbar vertebral fracture (LVF). The expressions of miR-101-3p and ECM-related proteins, Collagen-I (Col-I) and Collagen-II (Col-II), were detected using the reverse transcription-quantitative polymerase chain reaction. The expressions of Col-I and Col-II, major non-collagenous component Aggrecan, and major catabolic factor Matrix metalloproteinase-13 (MMP-13) were detected using Western blotting. BMSCs were cocultured with degenerated NPCs from patients with IDD. Viability and apoptosis of NPCs were measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and flow cytometry. After the degenerated NPCs were transfected with the miR-101-3p inhibitor, the expressions of ECM-related proteins, cell viability, and apoptosis were detected. The targeting relationship between miR-101-3p and EIF4G2 was verified. Functional rescue experiments verified the effects of miR-101-3p and EIF4G2 on ECM remodeling of NPCs. Compared with the NPCs of patients with LVF, the degenerated NPCs of patients with IDD showed downregulated miR-101-3p, Col-II, and Aggrecan expressions and upregulated MMP-13 and Col-I expressions. BMSCs increased the expressions of miR-101-3p, Aggrecan, and Col-II, and decreased the expressions of MMP-13 and Col-I in degenerated NPCs. BMSCs enhanced NPC viability and repressed apoptosis. Downregulation of miR-101-3p suppressed the promoting effect of BMSCs on ECM remodeling. miR-101-3p targeted EIF4G2. Downregulation of EIF4G2 reversed the inhibiting effect of the miR-101-3p inhibitor on ECM remodeling. In conclusion, BMSCs increased the miR-101-3p expression in degenerated NPCs to target EIF4G2, thus promoting the ECM remodeling of NPCs.

DNMT3B decreases extracellular matrix degradation and alleviates intervertebral disc degeneration through TRPA1 methylation to inhibit the COX2/YAP axis

Intervertebral disc degeneration (IVDD) is a main cause of low back pain that is associated with extracellular matrix (ECM) degradation and inflammation. This study aims to investigate the role of DNMT3B and its regulatory mechanisms in IVDD. IVDD rat models were constructed followed by transfections with oe-DNMT3B or oe-YAP in order to explore the role of DNMT3B in the development of IVDD. After that transfection, nucleus pulposus (NP) cells were isolated and transfected with oe-DNMT3B, oe-TRPA1, si-YAP, oe-YAP or oe-COX2 in order to investigate the functions of DNMT3B in NP cells. DNMT3B was poorly expressed in IVDD tissues and NP cells whereas TRPA1, COX2, and YAP were highly expressed. The proliferation or apoptosis of NP cells was detected through CCK-8 assay or flow cytometry, respectively. Overexpression of DNMT3B promoted the proliferation of NP cells, inhibited their apoptosis, as well as increasing the expression of collagen II and aggrecan and decreasing expression of MMP3 and MMP9. Besides, DNMT3B suppressed inflammation and alleviated IVDD. Mechanistically, DNMT3B modified the TRPA1 promoter by methylation to inhibit the expression of COX2. Overexpression of COX2 promoted the apoptosis of NP cells and decreased the expression of YAP, which was reversed by upregulating DNMT3B. DNMT3B may promote the proliferation of NP cells and prevent their ECM degradation through the TRPA1/COX2/YAP axis, thereby alleviating IVDD in rats.

Role of lncRNA XIST/microRNA-19/PTEN network in autophagy of nucleus pulposus cells in intervertebral disc degeneration via the PI3K/Akt signaling pathway

Intervertebral disc degeneration (IVDD) is a complicated pathological condition accompanying with low back pain. This study was designed to figure out the mechanism of lncRNA XIST in IVDD. Abnormally expressed lncRNAs in IVDD patients were measured. The correlations among XIST, miR-19 and PTEN were identified. Overexpression and silencing of XIST, miR-19 and PTEN were introduced and their roles in NPC autophagy in vitro were detected. The potential signaling pathway involved in these events was identified. Consequently, high expression of XIST was found in IVDD patients. It induced NPC autophagy and reduced NPC viability. XIST could serve as a competing endogenous RNA (ceRNA) for miR-19 and upregulate PTEN expression. The overexpression of XIST reduced miR-19 expression, which was followed by enhanced PTEN expression. Upregulation of miR-19 increased NPC viability and proliferation, while decreased NPC autophagy that regulated by XIST, while overexpressed PTEN reversed the above changes. Moreover, overexpression of XIST inactivated the PI3k/Akt signaling pathway.

Construction of a Potentially Functional circRNA-miRNA-mRNA Network in Intervertebral Disc Degeneration by Bioinformatics Analysis

Background

The competing endogenous RNA- (ceRNA-) mediated regulatory mechanisms are known to play a pivotal role in intervertebral disc degeneration (IDD). Our research intended to establish a ceRNA regulatory network related to IDD through bioinformatics analyses.

Methods

The expression profiles of circRNA, miRNA, and mRNA were obtained from the public Gene Expression Omnibus (GEO) datasets. Then, we use sequence-based bioinformatics methods to select differentially expressed mRNAs (DEmRNAs), microRNAs (DEmiRNAs), or circRNAs (DEcircRNAs) related to IDD. We used ChEA3 to verify the targets of transcription factors (TFs). Then, we used DAVID to annotate the DEmRNAs. Finally, we constructed a potentially circRNA-miRNA-mRNA network related to IDD by predicting in the database (ENCORI, TargetScan, miRecords, miRmap, and circBank).

Results

We identified 31 common DEmRNAs by Venn analysis, of which MMP2 was regarded as the key hub genes. Simultaneously, miR-423-5p and miR-185-5p were predicted as the upstream molecules of MMP2. Furthermore, a total of six DEcircRNAs were predicted as the upstream circRNAs of miR-423-5p and miR-185-5p. Then, a potential circRNA-miRNA-mRNA network related to IDD was constructed by bioinformatics analysis.

Conclusion

A comprehensive ceRNA regulatory network was constructed, which was found to be significant in IDD progression.

microRNA-129-5p shuttled by mesenchymal stem cell-derived extracellular vesicles alleviates intervertebral disc degeneration via blockade of LRG1-mediated p38 MAPK activation

Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) have been reported to deliver exogenous microRNAs (miRNAs or miRs) to reduce the progression of intervertebral disc degeneration (IDD). The purpose of the current study was to investigate the therapeutic potential of MSC-derived EVs delivering miR-129-5p in IDD. First, miR-129-5p expression levels were quantified in nucleus pulposus (NP) tissues of IDD patients. An IL-1β-induced NP cell model with IDD was then established, and co-cultured with EVs derived from MSCs that had been transfected with miR-129-5p mimic or inhibitor to elucidate the effects of miR-129-5p on cell viability, apoptosis, and ECM degradation. In addition, RAW264.7 cells were treated with the conditioned medium (CM) of NP cells. Next, the expression patterns of polarization markers and those of inflammatory factors in macrophages were detected using flow cytometry and ELISA, respectively. Lastly, rat models of IDD were established to validate the in vitro findings. It was found that miR-129-5p was poorly-expressed in NP tissues following IDD. Delivery of miR-129-5p to NP cells by MSC-derived EVs brought about a decrease in NP cell apoptosis, ECM degradation and M1 polarization of macrophages. Moreover, miR-129-5p directly-targeted LRG1, which subsequently promoted the activation of p38 MAPK signaling pathway, thus polarizing macrophages toward the M1 phenotype. Furthermore, MSC-derived EVs transferring miR-129-5p relieved IDD via inhibition of the LRG1/p38 MAPK signaling in vivo. Altogether, our findings indicated that MSC-derived EVs carrying miR-129-5p confer protection against IDD by targeting LRG1 and suppressing the p38 MAPK signaling pathway, offering a novel theranostic marker in IDD.

MiRNA-495-3p Attenuates TNF-α Induced Apoptosis and Inflammation in Human Nucleus Pulposus Cells by Targeting IL5RA

Intervertebral disc degeneration (IVDD) is considered to be the fundamental cause of the occurrence and development of lumbar disc herniation (LDH). The degeneration of IVDD is mainly caused by the participation of inflammatory factors. Thus, it is of great significance to analyze the pathogenesis of IVDD, which may guide clinical prevention and treatment of LDH. Our current study aims to identify the role of miR-495-3p in LDH and to further unravel the underlying mechanisms. Results in the current study showed that TNF-α treatment markedly inhibited cell viability of HNPC, increased the IL-1β level, and decreased the mRNA level of miR-495-3p in HNPC in a time-dependent manner. Up-regulation of miR-495-3p promoted cell proliferation and inhibited inflammation and apoptosis in TNF-α-induced HNPCs. To investigate the underlying molecular mechanism through which miR-495-3p regulates TNF-α-induced inflammation and apoptosis in HNPCs, we explored the possible target gene of miR-495-3p. Bioinformatics analysis indicated that IL5RA, which is an important gene for TNF-α-induced HNPC injury, was also a target gene of miR-495-3p. A luciferase reporter assay was applied to test and verify the direct target association between miR-495-3p and IL5RA. The results discovered that down-regulation of miR-495-3p markedly reversed the anti-apoptosis and anti-inflammation of sh-IL5RA. In short, the present study evaluated the roles of miR-495-3p and IL5RA in IVDD development and progression. All the data indicated that miRNA-495-3p may play a protective role via inhibiting inflammation and apoptosis in human nucleus pulposus cells by targeting IL5RA pathway. Therefore, miRNA-495-3p may be a potential agent for LDH, and our study may provide a novel strategy in LDH treatment.

MiR-532-3p Suppresses Nucleus Pulposus Cells Proliferation and Extracellular Matrix Production, Promotes Cell Apoptosis via Targeting High Mobility Group AT-Hook 2

The present study aimed to investigate the function and mechanism of microRNA (miR)-532-3p in intervertebral disc degeneration (IDD). Further, whether miR-532-3p regulates HMGA2 in nucleus pulposus (NP) cells was explored. We collected human nucleus pulposus (NP) tissues from the patients with IDD, and detected miR-532-3p in NP tissues using RT-qPCR. MiR-532-3p mimic and inhibitor were constructed, and they were transfected into the human nucleus pulposus cells (HNPCs) by Lipofectamine 3000. MTT assay was conducted to determine cell proliferation. Cell apoptosis and extracellular matrix remodeling were examined by flow cytometric, Caspase 3/8 Assay Kits and Western blot. A dual-luciferase reporter assay was applied to investigate whether miR-532-3p targets High mobility group AT-hook 2 (HMGA2). We found miR-532-3p expression level was significantly increased in NP tissues of IDD patients, comparing with the controls. MiR-532-3p exerted an inhibitory effect on HNPCs proliferation; however, cell apoptosis and the degradation of extracellular matrix were induced by miR-532-3p. MiR-532-3p directly targets HMGA2, and HMGA2 overexpression reversed the role of miR-532-3p mimic in HNPCs proliferation, apoptosis, and extracellular matrix remodeling. Our study is the first to report that miR-532-3p might suppress NP cell proliferation, promote cell apoptosis and inhibit ECM production of NP cells via targeting HMGA2, thus facilitating the progression of IDD. MiR-532-3p was supposed to be a novel target for the treatment of IDD.

Role of the miR-133a-5p/FBXO6 axis in the regulation of intervertebral disc degeneration

OBJECTIVE

Low back pain is a leading cause of disabilities worldwide, and intervertebral disc degeneration (IVDD)-related disorders have been recognised as one of the main contributors. Nevertheless, the underlying mechanism has not yet been fully understood. The aim of this study was to investigate the role of the miR-133a-5p/FBXO6 axis in the regulation of IVDD.

METHODS

RT-qPCR, WB and IHC were performed to assess the expression of FBXO6 in human IVD tissues. Nucleus pulposus (NP) cells were treated with IL-1β to induce IVDD cellular model. Silence of FBXO6 was achieved using specific siRNAs. CCK-8 assay, flow cytometry, TUNEL assay, RT-qPCR and WB were used to evaluate the role and mechanism of FBXO6 in the process of IVDD. Online tools, GSE datasets and RT-qPCR were used to search the candidate miRNAs targeting FBXO6. The direct binding sites between FBXO6 and miR-133a-5p were further verified by a dual luciferase assay. RT-qPCR, WB and rescue experiments were conducted to identify the regulatory function of miR-133a-5p on the expression of aggrecan, collagen Ⅱ, MMP3, ADAMTS5, IL-6 and COX2. In addition, the role of the NF-κB pathway in regulating miR-133a-5p was studied using lentiviral shRNA, WB and RT-qPCR.

RESULTS

Results showed that FBXO6 mainly expressed in the NP tissue of IVD and the expression of FBXO6 decreased with the process of IVDD as well as under IL-1β stimulation. The silence of FBXO6 led to the decreased expression of aggrecan and collagen Ⅱ and the increased expression of MMP3, ADAMTS5, IL-6 and COX2, which further induced the degeneration of NP cells. The bioinformatic analysis showed that miR-133a-5p was the candidate miRNA targeting FBXO6. miR-133a-5p was upregulated in IVDD tissues and significantly inhibited the expression of FBXO6. The inhibition of miR-133a-5p ameliorated the acceleration of IVDD induced by the silence of FBXO6 in vitro. Moreover, it was demonstrated that IL-1β regulated the expression of the miR-133a-5p/FBXO6 axis via the NF-κB pathway in NP cells.

CONCLUSION

miR-133a-5p was upregulated by IL-1β to aggravate intervertebral disc degeneration via sponging FBXO6. Inhibiting miR-133a-5p expression or rescuing FBXO6 expression may be promising strategies for the treatment of IVDD.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

This study suggests that the miR-133a-5p/FBXO6 axis could regulate NP cells proliferation, apoptosis, synthesis and degradation of extracellular matrix, which provides a promising therapeutic target and strategy for the treatment of IVDD.

CircSNHG5 Sponges Mir-495-3p and Modulates CITED2 to Protect Cartilage Endplate From Degradation

Background

Intervertebral disc degeneration (IDD) is a highly prevalent degenerating disease that produces tremendous amount of low back and neck pain. The cartilage endplate (CEP) is vitally important to intervertebral discs in both physiological and pathological conditions. In addition, circular RNAs (circRNAs) have been shown to be involved in the regulation of various diseases, including IDD. However, the particular role of circRNAs in cervical vertebral CEP degeneration remains unclear. Here, we examined the unique role of circRNAs in CEP of patients with cervical fracture and degenerative cervical myelopathy (DCM).

Methods

Human competitive endogenous RNA (ceRNA) microarray was performed by previous research. Western blot (WB), immunofluorescence (IF), quantitative RT-PCR (qRT-PCR), luciferase assay, and fluorescence in situ hybridization (FISH) were employed to analyze the function of circSNHG5 and its downstream effectors, miR-495-3p, and CITED2.

Results

We demonstrated that circSNHG5 expression was substantially low in degenerative CEP tissues. Knockdown of circSNHG5 in chondrocytes resulted in a loss of cell proliferation and followed by degradation of extracellular matrix (ECM). In addition, circSNHG5 was shown to sponge miR-495-3p and modulate the expression of the downstream gene CITED2. This mechanism of action was further validated via overexpression and knockdown of CITED2.

Conclusion

Our findings identified a novel circSNHG5-miR-495-3p axis responsible for IDD progression. Future investigations into IDD therapy may benefit from targeting this axis.

Expression of miR-195 and its target gene Bcl-2 in human intervertebral disc degeneration and their effects on nucleus pulposus cell apoptosis

Objective

To investigate the expression of miR-195 and its target gene Bcl-2 in intervertebral disc degeneration (IVDD) and its effect on nucleus pulposus (NP) cell apoptosis.

Methods

The expressions of miR-195 and Bcl-2 in NP tissues of IVDD patients were quantified by qRT-PCR and western blotting, respectively. NP cells were divided into blank group, TNF-α group, TNF-α + miR-NC group, TNF-α + siBcl-2 group, and TNF-α + miR-195 inhibitors + siBcl-2 group. Cell proliferation was detected by MTT assay, cell apoptosis evaluated by flow cytometry, and mitochondrial membrane potential (MMP) tested by JC-1 staining. Moreover, the function of miR-195 on IVDD in vivo was investigated using a puncture-induced IVDD rat model.

Results

IVDD patients had significantly increased miR-195 expression and decreased Bcl-2 protein expression in NP tissues. The expression of miR-195 was negatively correlated with the expression of Bcl-2 in IVDD patients. Dual-luciferase reporter gene assay indicated that Bcl-2 was a target gene of miR-195. In comparison with blank group, TNF-α group showed decreased cell proliferation and MMP, increased cell apoptosis, upregulated expression of miR-195, Bax, and cleaved caspase 3, and downregulated Bcl-2 protein, while these changes were attenuated by miR-195 inhibitors. Additionally, siBcl-2 can reverse the protective effect of miR-195 inhibitors on TNF-α-induced NP cells. Besides, inhibition of miR-195 alleviated IVDD degeneration and NP cell apoptosis in the rat model.

Conclusion

MiR-195 was significantly upregulated in NP tissues of IVDD patients, and inhibition of miR-195 could protect human NP cells from TNF-α-induced apoptosis via upregulation of Bcl-2.

Long non-coding RNA RP11-81H3.2 suppresses apoptosis by targeting microRNA-1539/COL2A1 in human nucleus pulposus cells

Intervertebral disk degeneration (IDD) is a severe health problem that results in lower back pain and disability. Previous evidence has indicated that excessive apoptosis of nucleus pulposus (NP) cell is involved in the occurrence and development of IDD. However, the underlying mechanisms regulating NP cell apoptosis are unclear. The present study aimed to investigate the function of a novel long non-coding RNA RP11-81H3.2 in modulating NP cell apoptosis and the potential underlying mechanisms. The results demonstrated that the RP11-81H3.2 expression levels were significantly decreased in NP tissues from patients with IDD compared with those from healthy controls, and that lower expression levels were associated with higher-grade disk degeneration. Functionally, RP11-81H3.2 silencing promoted apoptosis and decreased the viability of NP cells derived from tissue samples of patients with IDD, whereas RP11-81H3.2 overexpression induced opposite effects. Bioinformatics analysis, luciferase assays and reverse transcription-quantitative PCR revealed that microRNA (miR)-1539 was a direct target of RP11-81H3.2. A mechanistic analysis demonstrated that RP11-81H3.2 functioned as an RNA sink to downregulate miR-1539, which led to the upregulation of collagen type 2 α 1 chain (COL2A1), a target of miR-1539. Collectively, the present results suggested that lower RP11-81H3.2 expression levels were associated with higher-grade IDD, and that RP11-81H3.2 inhibited NP cell apoptosis by decreasing the levels of miR-1539 to increase COL2A1 expression levels. The present study identified a beneficial role of RP11-81H3.2 against NP cell apoptosis.

MicroRNA-199a-5p accelerates nucleus pulposus cell apoptosis and IVDD by inhibiting SIRT1-mediated deacetylation of p21

Intervertebral disc degeneration (IVDD) is a multifactorial pathological process associated with low back pain in which nucleus pulposus cell senescence is disrupted. Increasing evidence reveals that IVDD can be modulated by microRNAs (miRNAs or miRs). In the current study, we set out to elucidate the role of miR-199a-5p in nucleus pulposus cell apoptosis and IVDD progression. After sample collection, we found highly expressed miR-199a-5p in nucleus pulposus tissues of both patients diagnosed with IVDD and in IVDD rat models. Next, normal and degenerated nucleus pulposus cells were isolated and transfected with miR-199a-5p mimic, miR-199a-5p inhibitor, overexpressed sirtuin 1 (oe-SIRT1), and oe-p21, followed by detection of nucleus pulposus cell apoptosis and proliferation. In addition, the binding of miR-199a-5p and SIRT1, the interaction between p21 and SIRT1, and the regulation of p21 acetylation by SIRT1 were analyzed. We found that miR-199a-5p overexpression promoted nucleus pulposus cell apoptosis and IVDD. Overexpression of SIRT1 countered the effect of miR-199a-5p overexpression, while overexpression of p21 reversed the effect of miR-199a-5p silencing. Also, miR-199a-5p inhibited SIRT1, promoted p21 acetylation, and upregulated p21 expression, thus accelerating nucleus pulposus cell apoptosis and IVDD. Overall, miR-199a-5p promotes nucleus pulposus cell apoptosis and IVDD by suppressing SIRT1-dependent deacetylation of p21.

Cardamonin protects nucleus pulposus cells against IL-1β-induced inflammation and catabolism via Nrf2/NF-κB axis

Intervertebral disc degeneration (IVDD) is one of the major causes of low back pain, but effective therapies are still lacking because of its complicated pathology. It has been demonstrated that increased levels of interleukin-1β (IL-1β) may promote the development of IVDD. Cardamonin (CAR) is a chalcone extracted from Alpinia katsumadai and other plants. It exhibits an anti-inflammatory effect in multiple diseases. In the present study, we investigated the protective effects of CAR on rat nucleus pulposus (NP) cells under IL-1β stimulation in vitro and in a puncture-induced rat IVDD model in vivo. We explored the CAR treatment's inhibition of the expression of inflammatory factors such as cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), prostaglandin E2 (PGE2), nitric oxide (NO), tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in rat NP cells. Moreover, the up-regulation of matrix metalloproteinase-13 (MMP-13) and thrombospondin motifs 5 (ADAMTS-5) and the degradation of aggrecan and collagen II induced by IL-1β were reversed by CAR. Mechanistically, we demonstrated that CAR inhibited nuclear factor kappa B (NF-κB) signaling by activating the nuclear factor erythroid-derived 2-like 2 (Nrf2) in IL-1β-induced rat NP cells. Furthermore, the protective effect of CAR was shown in the IVDD model through persistent intragastric administration. Taken together, our results revealed that CAR could activate the Nrf2/HO-1 signaling axis and be a novel agent for IVDD therapy.

N6-Methyladenosine Induced miR-34a-5p Promotes TNF-α-Induced Nucleus Pulposus Cell Senescence by Targeting SIRT1

Low back pain is tightly associated with intervertebral disc degeneration (IVDD) and aberrant nucleus pulposus (NP) is a critical cause. miRNAs N6-methyladenosine (m6A) modification accounts for the TNF-α-induced senescence of NP cells. The aim of this study was to investigate whether m6A modification regulates TNF-α-mediated cell viability, cell cycle arrest, and cell senescence and how it works. The results showed that METTL14 expression positively correlated with m6A and TNF-α expression in HNPCs. The knockdown of METTL14 led to the inhibition of the TNF-α-induced cell senescence. METTL14 overexpression promoted cell senescence. METTL14 regulated the m6A modification of miR-34a-5p and interacted with DGCR8 to process miR-34a-5p. The miR-34a-5p inhibitor inhibited the cell cycle senescence of HNPCs. miR-34a-5p was predicted to interact with the SIRT1 mRNA. SIRT1 overexpression counteracted the miR-34a-5p-promoted cell senescence. METTL14 participates in the TNF-α-induced m6A modification of miR-34a-5p to promote cell senescence in HNPCs and NP cells of IVDD patients. Downregulation of either METTL14 expression or miR-34a-5p leads to the inhibition of cell cycle arrest and senescence. SIRT1 mRNA is an effective binding target of miR-34a-5p, and SIRT1 overexpression mitigates the cell cycle arrest and senescence caused by miR-34a-5p.

Role of the Wnt pathway in the formation, development, and degeneration of intervertebral discs

Intervertebral disc degeneration (IVDD) is an age-related degenerative disease that is the main cause of low back pain. It seriously affects the quality of life of patients and places a heavy economic burden on families and society. The Wnt pathway plays an important role in the growth, development, and degeneration of intervertebral discs (IVDs). In the embryonic stage, the Wnt pathway participates in the growth and development of IVD by promoting the transformation of progenitor cells into notochord cells and the extension of the notochord. However, the activation of the Wnt pathway after birth promotes IVD cell senescence, apoptosis, and degradation of the extracellular matrix and induces the production of inflammatory factors, thereby accelerating the IVDD process. This article reviews the relationship between the Wnt pathway and IVD, emphasizing its influence on IVD growth, development, and degeneration. Targeting this pathway may become an effective strategy for the treatment of IVDD.

Down-Regulation of microRNA-30d Alleviates Intervertebral Disc Degeneration Through the Promotion of FOXO3 and Suppression of CXCL10

MicroRNAs (miRNAs/miRs) are important biomarkers for the progression of intervertebral disc degeneration (IDD). We investigated the role of miR-30d in IDD progression through its interactions with forkhead box O3 (FOXO3) and C-X-C motif ligand 10 (CXCL10). We first measured the expression of miR-30d, FOXO3, and CXCL10 in NP cells cultured from IDD patients. RNA-immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays were then employed to test the relationship among miR-30d, FOXO3, and CXCL10. Besides, gain- and loss-of function approaches were performed to assess the functional roles of miR-30d and FOXO3 in IDD in vitro and in vivo. We found high expression of miR-30d and CXCL10 and low expression of FOXO3 in IDD. We showed that miR-30d specifically targeted FOXO3, and that down-regulation of miR-30d promoted proliferation and inhibited apoptosis of NP cells in IDD by increasing the expression of FOXO3. Besides, FOXO3 inhibited apoptosis of NP cells by downregulation of CXCL10 expression. Moreover, inhibition of miR-30d promoted proliferation and inhibited apoptosis of NP cells in IDD by decreasing CXCL10. Furthermore, findings in the mouse IDD model confirmed the inhibitory role of decreased miR-30d in IDD progression. Thus, we show that downregulation of miR-30d could promote the proliferation of NP cells by increasing FOXO3 and decreasing CXCL10 expression, which may provide a novel therapeutic target for IDD.

Characterization and cytocompatibility of 3D porous biomimetic scaffold derived from rabbit nucleus pulposus tissue in vitro

Intervertebral disc (IVD) degeneration is one of the most important causes of lower back pain. Tissue engineering provides a new method for the experimental treatment of degenerative disc diseases. This study aims to develop a natural, acellular, 3D interconnected porous scaffold derived from the extracellular matrix (ECM) of nucleus pulposus. The nucleus pulposus (NP) was decellularized by sequential detergent-nuclease methods, including physical crushing, freeze-drying and cross-linking. These 3D porous scaffolds were fabricated with a high porosity of (81.28 ± 4.10)%, an ideal pore size with appropriate mechanical properties. Rabbit bone marrow mesenchymal stem cells (rBMSCs) were seeded and cultured on the scaffolds. And the mechanical tests showed the compressive elastic modulus of the scaffolds cultured for 4 weeks reached 0.12 MPa, which was better than that of the scaffolds cultured for 2 weeks (0.07 MPa) and that of the control group (0.04 MPa). Scanning electron microscopy (SEM), histological assays, molecular biology assays revealed that the scaffolds could provide an appropriate microstructure and environment for the adhesion, proliferation, migration and secretion of seeded cells in vitro. As assays like histology, immunohistochemistry and the real-time qRT-PCR showed, NP-like tissues were preliminarily formed. In conclusion, the 3D porous scaffold derived from NP ECM is a potential biomaterial for the regeneration of NP tissues. A natural, acellular, 3D interconnected porous scaffold derived from the extracellular matrix (ECM) of nucleus pulposus was developed by sequential detergent-nuclease and freeze-drying method, which can reduce the damage of protein activity to the minimum. It is very similar to the composition and internal environment of the natural nucleus pulposus, because it derived from the natural nucleus pulposus. Scanning electron microscopy (SEM), histological assays, molecular biology assays revealed that the scaffolds could provide an appropriate microstructure and environment for the adhesion, proliferation, migration, and secretion of seeded cells in vitro.

Resveratrol prevents steroid-induced osteonecrosis of the femoral head via miR-146a modulation

The purpose of this study was to investigate the possible use of resveratrol (Res) to reverse abnormal osteogenesis/osteoclastogenesis activity that occurs during femoral head osteonecrosis and to explore the detailed mechanisms. Application of Res to bone marrow-derived mesenchymal stem cells in vitro promoted survival, inhibited apoptosis, and downregulated expression of reactive oxygen species expression. Moreover, Res application was associated with elevated microRNA-146a (miR-146a) expression, osteogenic differentiation, and suppressed osteoclastic differentiation, which were markedly reversed by miR-146a inhibitor. Histopathological observations and micro-computed tomography scanning results indicated that the Res-treated group had lower incidence of osteonecrosis and better bone microstructure than the untreated group. Res inhibited osteoclastogenesis through altering the levels of sirtuin1 (Sirt1), nuclear transcription factor-κB (NF-κB), and receptor activator of NF-κB ligand (RANKL). Simultaneously, Res treatment improved bone formation and increased β-catenin and runt-related transcription factor 2 (Runt2) expression levels, while reducing forkhead box class O (FOXO) family protein levels. The results of our study suggest that Res prevents steroid-induced osteonecrosis by upregulating miR-146a, and thereby stabilizes osteogenesis/osteoclastogenesis homeostasis via Wnt/FOXO and Sirt1/NF-κB pathways.

Low expression of miR-142-3p promotes intervertebral disk degeneration

Background

Intervertebral disk degeneration (IDD) is a degenerative disease characterized by cytoplasm loss and extracellular matrix degradation. Numerous evidence reported that miRNAs participated in IDD development. Nevertheless, the function of miR-142-3p in IDD development remains unknown. This study mainly explored the potential role and function of miR-142-3p in IDD development.

Methods

One percent fetal bovine serum was used to induce the degeneration of ATDC5 cells, and miR-142-3p level was examined by qRT-PCR. Then, miR-142-3p mimic/inhibitor and its corresponding negative control were transfected into ATDC5 normal and degenerative cells. Viability, migration, invasion, apoptosis, cycle, Bax, Bcl-2, P62, and Beclin1 expression levels were assessed using CCK8, wound healing assay, annexin V-FITC/PI staining, western blot, and qRT-PCR, respectively.

Results

The results revealed that the expression levels of MMP13, ADAMTS5, MMP3, and Col-X were increased as well as the expression levels of SOX-9 and Col-II were reduced in ATDC5 degenerative cells, indicating the degeneration model was constructed. We observed that miR-142-3p was decreased in ATDC5 degenerative cells and its suppression could promote ATDC5 cell degeneration. However, miR-142-3p overexpression could reverse the cell viability inhibition, as well as apoptosis and autophagy enhancement in ATDC5 degenerative cells.

Conclusions

Our results proved that miR-142-3p may play an important role in disk degeneration. Further animal study is needed to illustrate the role of the miR-142-3p in IDD development.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-020-02194-4.

Mir-573 regulates cell proliferation and apoptosis by targeting Bax in human degenerative disc cells following hyperbaric oxygen treatment

Background

MicroRNA (miRNA) plays a vital role in the intervertebral disc (IVD) degeneration. The expression level of miR-573 was downregulated whereas Bax was upregulated notably in human degenerative nucleus pulposus cells. In this study, we aimed to investigate the role of miR-573 in human degenerative nucleus pulposus (NP) cells following hyperbaric oxygen (HBO) treatment.

Methods

NP cells were separated from human degenerated IVD tissues. The control cells were maintained in 5% CO₂/95% air and the hyperoxic cells were exposed to 100% O₂ at 2.5 atmospheres absolute. MiRNA expression profiling was performed via microarray and confirmed by real-time PCR, and miRNA target genes were identified using bioinformatics and luciferase reporter assays. The mRNA and protein levels of Bax were measured. The proliferation of NPCs was detected using MTT assay. The protein expression levels of Bax, cleaved caspase 9, cleaved caspase 3, pro-caspase 9, and pro-caspase 3 were examined.

Results

Bioinformatics analysis indicated that the 3′ untranslated region (UTR) of the Bax mRNA contained the “seed-matched-sequence” for hsa-miR-573, which was validated via reporter assays. MiR-573 was induced by HBO and simultaneous suppression of Bax was observed in NP cells. Knockdown of miR-573 resulted in upregulation of Bax expression in HBO-treated cells. In addition, overexpression of miR-573 by HBO increased cell proliferation and coupled with inhibition of cell apoptosis. The cleavage of pro-caspase 9 and pro-caspase 3 was suppressed while the levels of cleaved caspase 9 and caspase 3 were decreased in HBO-treated cells. Transfection with anti-miR-573 partly suppressed the effects of HBO.

Conclusion

Mir-573 regulates cell proliferation and apoptosis by targeting Bax in human degenerative NP cells following HBO treatment.

Comprehensive RNA expression profile of therapeutic adipose‑derived mesenchymal stem cells co‑cultured with degenerative nucleus pulposus cells

Stem cell-based therapy is a promising alternative to conventional approaches to treating intervertebral disc degeneration (IDD). However, comprehensive understanding of stem cell-based therapy at the gene level is still lacking. In the present study, we identified the expression profiles of messenger RNAs (mRNAs) and long non-coding RNAs (lncRNAs) expressed within a co-culture system of adipose-derived mesenchymal stem cells (ASCs) and degenerative nucleus pulposus cells (NPCs) and explored the signaling pathways involved and their regulatory networks. Microarray analysis was used to compare ASCs co-cultured with degenerative NPCs to ASCs cultured alone, and the underlying regulatory pattern, including the signaling pathways and competing endogenous RNA (ceRNA) network, was analyzed with robust bioinformatics methods. The results showed that 360 lncRNAs and 1757 mRNAs were differentially expressed by ASCs, and the microarray results were confirmed by quantitative PCR. Moreover, 589 Gene Ontology terms were upregulated, whereas 661 terms were downregulated. A total of 299 signaling pathways were significantly altered. A Path-net and a Signal-net were built to show interactions among differentially expressed genes. An mRNA-lncRNA co-expression network was constructed to reveal the interplay among differentially expressed mRNAs and lncRNAs, whereas a ceRNA network was built to investigate their connections with microRNAs involved in IDD. To the best of our knowledge, this original and comprehensive exploration reveals differentially expressed lncRNAs and mRNAs of ASCs stimulated by degenerative NPCs, underscoring the regulation pattern within the co-culture system at the gene level. These data may further understanding of NPC-directed differentiation of ASCs and facilitate the application of ASCs in future treatments for IDD.

MicroRNA-16 inhibits the lipopolysaccharide-induced inflammatory response in nucleus pulposus cells of the intervertebral disc by targeting TAB3

INTRODUCTION

A variety of inflammatory mediators are produced by the degenerative human intervertebral disc (IVD) tissues spontaneously, suggesting their role in the development of intervertebral disc degeneration (IDD). Our present study was designed to investigate the regulatory effect of microRNA-16 (miR-16) on the lipopolysaccharide (LPS)-induced inflammatory response in nucleus pulposus (NP) cells of the IVD.

MATERIAL AND METHODS

NP cells were treated with LPS to induce inflammatory responses. The expression of miRNA and genes was determined by qRT-PCR. Western blot and an ELISA kit were used to detect the proteins and protein expression, respectively. A dual luciferase reporter assay was applied to identify the correlation between a miRNA and a gene, and to test nuclear factor-κB (NF-κB) activity.

RESULTS

The results suggested that miR-16 positively regulated the mRNA and protein expression of extracellular matrix (ECM) genes (including aggrecan and collagen II) in NP cells, while it was negatively correlated with ECM degrading enzymes (including MMP3, MMP13, ADAMTS4, ADAMTS5) and related genes of nitric oxide (NO) reaction. Further studies revealed that miR-16 could oppositely regulate NF-κB and MAPK pathways by directly mediating their upstream gene TAB3.

CONCLUSIONS

Our study suggested that, in NP cells of the IVD, miR-16 could exert inhibitory effects on the LPS-induced inflammatory response through NF-κB and MAPK pathways by directly mediating TAB3. In this way, miR-16 would play a protective role against LPS-induced IDD and inflammation. Therefore, miR-16 may be a novel therapeutic target for the inhibit of the ECM in the IVD.