Inflammatory microRNA-194 and -515 attenuate the biosynthesis of chondroitin sulfate during human intervertebral disc degeneration

Mechanism exploration of Osteoking in the treatment of lumbar disc herniation based on network pharmacology and molecular docking

OBJECTIVE

Lumbar disc herniation (LDH) is a common spinal surgical disease. Low back and leg pain caused by LDH is the main factor leading to functional disability, which has caused a serious burden to patients and society. Osteoking can delay the progression of osteoporosis and osteoarthritis, and even has a significant effect on the prevention of deep vein thrombosis after fracture surgery. In recent years, it has been gradually used in the treatment of LDH and has received significant results. However, the underlying mechanism remains unclear. The aim of this study was to predict the mechanism of Osteoking in the treatment of LDH through network pharmacology and verify it by molecular docking method.

METHODS

The TCMSP database was used to collect the relevant active components and targets of Osteoking, while the GeneCards, OMIM and DisGeNET databases were utilized to collect the relevant disease targets of LDH. The Venny 2.1.0 software was employed to obtain the intersecting gene targets of Osteoking and LDH. PPI network construction and core target selection were performed using Cytoscape 3.9.0 software. The Metascape database was used for GO and KEGG enrichment analysis of the relevant targets. Finally, molecular docking was conducted using AutoDock software.

RESULTS

The study identified 116 potential targets and 26 core targets for the treatment of LDH with Osteoking. Pathways in cancer, Alzheimer's disease, microRNAs in cancer and the IL-17 signalling pathway were among the main involved signalling pathways. Molecular docking results demonstrated that the key targets AKT1, IL-6, ALB, TNF and IL-1β exhibited relatively stable binding activities with the main active components of Osteoking.

CONCLUSIONS

Osteoking can alleviate the symptoms of lumbar disc herniation through the modulation of multiple targets and signalling pathways.

Low-dose celecoxib-loaded PCL fibers reverse intervertebral disc degeneration by up-regulating CHSY3 expression

Intervertebral disc degeneration (IDD) has been identified as one of the predominant factors leading to persistent low back pain and disability in middle-aged and elderly people. Dysregulation of Prostaglandin E2 (PGE2) can cause IDD, while low-dose celecoxib can maintain PGE2 at the physiological level and activate the skeletal interoception. Here, as nano fibers have been extensively used in the treatment of IDD, novel polycaprolactone (PCL) nano fibers loaded with low-dose celecoxib were fabricated for IDD treatment. In vitro studies demonstrated that the nano fibers had the ability of releasing low-dose celecoxib slowly and sustainably and maintain PGE2. Meanwhile, in a puncture-induced rabbit IDD model, the nano fibers reversed IDD. Furthermore, low-dose celecoxib released from the nano fibers was firstly proved to promote CHSY3 expression. In a lumbar spine instability-induced mouse IDD model, low-dose celecoxib inhibited IDD in CHSY3^wt mice rather than CHSY3^-/- mice. This model indicated that CHSY3 was indispensable for low-dose celecoxib to alleviate IDD. In conclusion, this study developed a novel low-dose celecoxib-loaded PCL nano fibers to reverse IDD by maintaining PGE2 at the physiological level and promoting CHSY3 expression.

Sensory Nerve Maintains Intervertebral Disc Extracellular Matrix Homeostasis Via CGRP/CHSY1 Axis

Sensory nerves are long being recognized as collecting units of various outer stimuli; recent advances indicate that the sensory nerve also plays pivotal roles in maintaining organ homeostasis. Here, this study shows that sensory nerve orchestrates intervertebral disc (IVD) homeostasis by regulating its extracellular matrix (ECM) metabolism. Specifically, genetical sensory denervation of IVD results in loss of IVD water preserve molecule chondroitin sulfate (CS), the reduction of CS bio-synthesis gene chondroitin sulfate synthase 1 (CHSY1) expression, and dysregulated ECM homeostasis of IVD. Particularly, knockdown of sensory neuros calcitonin gene-related peptide (CGRP) expression induces similar ECM metabolic disorder compared to sensory nerve denervation model, and this effect is abolished in CHSY1 knockout mice. Furthermore, in vitro evidence shows that CGRP regulates nucleus pulposus cell CHSY1 expression and CS synthesis via CGRP receptor component receptor activity-modifying protein 1 (RAMP1) and cyclic AMP response element-binding protein (CREB) signaling. Therapeutically, local injection of forskolin significantly attenuates IVD degeneration progression in mouse annulus fibrosus puncture model. Overall, these results indicate that sensory nerve maintains IVD ECM homeostasis via CGRP/CHSY1 axis and promotes IVD repair, and this expands the understanding concerning how IVD links to sensory nerve system, thus shedding light on future development of novel therapeutical strategy to IVD degeneration.

Whole-genome resequencing to investigate the determinants of the multi-lumbar vertebrae trait in sheep

Multi-lumbar vertebrae trait is a beneficial mutation that can significantly improve livestock meat production. However, the genetic basis of the multi-lumbar vertebrae in sheep is still unclear. Here, we analysed the number of lumbar vertebrae of Duolang sheep and found three different traits of lumbar vertebrae number. Compared with the normal sheep, the length and weight of animal carcass from the multi-lumbar vertebrae sheep increased by 2.21 cm and 0.78 kg, respectively. We performed high-throughput genome resequencing on multi-lumbar vertebrae (n = 18) and normal (n = 11) Duolang sheep and obtained a total of more than 528.87 GB data. We found that the most significantly selective region were located in the 49.68-49.74 MB of chromosome 4 by selective-sweep analysis. We annotated this region and found that it contains SFRP4 which is known to regulate bone development. We further used the PCR-SSCP technology to detect the single nucleotide polymorphism (SNP) of the putative candidate SFRP4 and found that the two SNPs (rs600370085:C > T and rs415133338: A > G) of this gene were significantly associated with the multi-lumbar vertebrae of Duolang sheep. Our study indicates that the SFRP4 may be a potential major gene that affects the number of lumbar vertebrae in Duolang sheep, and has the potential to be utilized for sheep breeding in the future.

Age-dependent microstructural changes of the intervertebral disc: a validation of proteoglycan-sensitive spectral CT

Objective

To analyze the two major components of the intervertebral disc (IVD) in an ex vivo phantom, as well as age-related changes in patients.

Methods

Collagen and chondroitin sulfate were imaged at different concentrations in agar solution. Age-related changes in disc density were retrospectively analyzed in normal-appearing discs in dual-energy computed tomography (DECT) images from a patient cohort with various spinal pathologies (n = 136). All computed tomography (CT) scans were acquired using single-source DECT at 80 and 135 kVp with automatic exposure calculation. In 136 patients, the attenuation of normal-appearing discs on collagen/chondroitin maps (cMaps) correlated with the patients’ age with Pearson’s r using standardized regions of interest in the anterior anulus fibrosus (AAF) and nucleus pulposus (NP).

Results

DECT collagen mapping revealed concentration-dependent Hounsfield units (HU) of IVD components. For collagen, we found Pearson’s r = 0.9610 (95% CI 0.6789–0.9959), p = 0.0023 at 120 kVe, and r = 0.8824 (95% CI 0.2495–0.9871), p = 0.0199 in cMap. For chondroitin sulfate, Pearson’s r was 0.9583 (95% CI 0.6603–0.9956), p = 0.0026 at 120 kVp, and r = 0.9646 (95% CI 0.7044–0.9963), p = 0.0019 in cMap. Analysis of normal-appearing IVDs revealed an inverse correlation of density with age in the AAF: Pearson’s r = − 0.2294 at 135 kVp (95% CI − 0.4012 to − 0.04203; p=0.0141) and r = − 0.09341 in cMap (95% CI − 0.2777 to 0.09754; p = 0.0003). In the NP, age and density did not correlate significantly at 135 kVp (p = 0.9228) and in cMap (p = 0.3229).

Conclusions

DECT-based collagen mapping allows microstructural analysis of the two main intervertebral disc components—collagen and chondroitin sulfate. IVD density declines with age, presumably due to a reduction in collagen and chondroitin sulfate content. Age-related alterations of disc microstructure appear most pronounced in the AAF.

Key Points

• DECT-based collagen mapping allows precise analysis of the two main intervertebral disc components—collagen and chondroitin sulfate.

• Intervertebral disc (IVD) density declines with age, presumably due to a reduction in collagen and chondroitin sulfate content.

• Age-related alterations of disc microstructure are most pronounced in the anterior anulus fibrosus (AAF).

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08028-z.

The potential role and trend of HIF‑1α in intervertebral disc degeneration: Friend or foe? (Review)

Lower back pain (LBP) is one of the most common reasons for seeking medical advice in orthopedic clinics. Increasingly, research has shown that symptomatic intervertebral disc degeneration (IDD) is mostly related to LBP. This review first outlines the research and findings of studies into IDD, from the physiological structure of the intervertebral disc (IVD) to various pathological cascades. The vicious cycles of IDD are re-described in relation to the analysis of the relationship among the pathological mechanisms involved in IDD. Interestingly, a ‘chief molecule’ was found, hypoxia-inducible factor-1α (HIF-1α), that may regulate all other mechanisms involved in IDD. When the vicious cycle is established, the low oxygen tension activates the expression of HIF-1α, which subsequently enters into the hypoxia-induced HIF pathways. The HIF pathways are dichotomized as friend and foe pathways according to the oxygen tension of the IVD microenvironment. Combined with clinical outcomes and previous research, the trend of IDD development has been predicted in this paper. Lastly, an early precautionary diagnosis and treatment method is proposed whereby nucleus pulposus tissue for biopsy can be obtained through IVD puncture guided by B-ultrasound when the patient is showing symptoms but MRI imaging shows negative results. The assessment criteria for biopsy and the feasibility, superiority and challenges of this approach have been discussed. Overall, it is clear that HIF-1α is an indispensable reference indicator for the accurate diagnosis and treatment of IDD.

Integrated transcriptome and proteome analyses identify novel regulatory network of nucleus pulposus cells in intervertebral disc degeneration

BACKGROUND

Degeneration of intervertebral disc is a major cause of lower back pain and neck pain. Studies have tried to unveil the regulatory network using either transcriptomic or proteomic analysis. However, neither have fully elucidated the exact mechanism of degeneration process. Since post-transcriptional regulation may affect gene expression by modulating the translational process of mRNA to protein product, a combined transcriptomic and proteomic study may provide more insight into the key regulatory network of Intervertebral disc degeneration.

METHODS

In order to obtain the proteomic and transcriptomic data, we performed label-free proteome analysis on freshly isolated nucleus pulposus cells and obtained transcriptome profiling data from the Gene Expression Omnibus repository. To identify the key regulatory network of intervertebral disc degeneration in nucleus pulposus cells, we performed bioinformatic analyses and established a protein-RNA interacting network. To validate the candidate genes, we performed in vitro experimentation and immunochemistry labeling to identify their potential function during nucleus pulposus degeneration.

RESULTS

The label-free proteome analysis identified altogether 656 proteins, and 503 of which were differentially expressed between nucleus pulposus cells from degenerated or normal disc cells. Using the existing nucleus pulposus transcriptomic profiling data, we integrated the proteomic and transcriptomic data of nucleus pulposus cells, and established a protein-RNA interacting network to show the combined regulatory network of intervertebral disc degeneration. In the network, we found 9 genes showed significant changes, and 6 of which (CHI3L1, KRT19, COL6A2, DPT, TNFAIP6 and COL11A2) showed concordant changes in both protein and mRNA level. Further functional analysis showed these candidates can significantly affect the degeneration of the nucleus pulposus cell when altering their expression.

CONCLUSIONS

This study is the first to use combined analysis of proteomic and transcriptomic profiling data to identify novel regulatory network of nucleus pulposus cells in intervertebral disc degeneration. Our established protein-RNA interacting network demonstrated novel regulatory mechanisms and key genes that may play vital roles in the pathogenesis of intervertebral disc degeneration.

Emerging evidence on noncoding-RNA regulatory machinery in intervertebral disc degeneration: a narrative review

Intervertebral disc degeneration (IDD) is the most common cause of low-back pain. Accumulating evidence indicates that the expression profiling of noncoding RNAs (ncRNAs), including microRNAs (miRNAs), circular RNAs (circRNAs), and long noncoding RNAs (lncRNAs), are different between intervertebral disc tissues obtained from healthy individuals and patients with IDD. However, the roles of ncRNAs in IDD are still unclear until now. In this review, we summarize the studies concerning ncRNA interactions and regulatory functions in IDD. Apoptosis, aberrant proliferation, extracellular matrix degradation, and inflammatory abnormality are tetrad fundamental pathologic phenotypes in IDD. We demonstrated that ncRNAs are playing vital roles in apoptosis, proliferation, ECM degeneration, and inflammation process of IDD. The ncRNAs participate in underlying mechanisms of IDD in different ways. MiRNAs downregulate target genes’ expression by directly binding to the 3′-untranslated region of mRNAs. CircRNAs and lncRNAs act as sponges or competing endogenous RNAs by competitively binding to miRNAs and regulating the expression of mRNAs. The lncRNAs, circRNAs, miRNAs, and mRNAs widely crosstalk and form complex regulatory networks in the degenerative processes. The current review presents novel insights into the pathogenesis of IDD and potentially sheds light on the therapeutics in the future.

Regulation of Apoptosis and Inflammatory Response in Interleukin-1β-Induced Nucleus Pulposus Cells by miR-125b-5p Via Targeting TRIAP1

The aim of the present study was to determine the function of microRNA (miR)-125b-5p in lumbar disc degeneration (LDD). Nucleus pulposus (NP) cells were stimulated with 10 ng/ml IL-1β for 24 h to establish an LDD model. Reverse transcription-quantitative PCR was used to assess miR-125b-5p levels in human lumbar degenerative NP samples and IL-1β-treated NP cells. An interaction between miR-125b-5p and TP53-regulated inhibitor of apoptosis 1 (TRIAP1) was revealed by TargetScan 7.1 and dual-luciferase reporter assay. Protein levels of pro-inflammatory factors were determined using ELISA. Cell viability and apoptosis were evaluated by MTT and flow cytometry analysis, respectively. miR-125b-5p was markedly upregulated in both human lumbar degenerative NP specimens and IL-1β-treated NP cells. TRIAP1, which directly targets miR-125b-5p, was markedly downregulated in human lumbar degenerative NP specimens and IL-1β-treated NP cells. The levels of TNF-α and IL-6 were inhibited in IL-1β-treated NP cells transfected with miR-125b-5p inhibitor. Moreover, miR-125b-5p inhibitor increased NP cell viability, prevented apoptosis and repressed the apoptotic peptidase activating factor 1/caspase 9 pathway in IL-1β-treated NP cells. Thus, the present findings suggested that miR-125b-5p could regulate LDD by adjusting NP cell apoptosis and inflammatory responses via TRIAP1.

A Bioinformatic Analysis of MicroRNAs' Role in Human Intervertebral Disc Degeneration

Objectives The aim of our study was to ascertain the underlying role of microRNAs (miRNAs) in human intervertebral disc degeneration (IDD). Design Bioinformatic analysis from multiple databases. Methods Studies of the association of miRNAs and IDD were identified in multiple electronic databases. All potential studies were assessed by the same inclusion and exclusion criteria. We recorded whether miRNA expression was commonly increased or suppressed in the intervertebral disc tissues and cells of IDD subjects. We used String to identify biological process and cellular component pathways of differentially expressed genes. Results We included fifty-seven articles from 1,277 records in this study. This report identified 40 different dysregulated miRNAs in 53 studies, including studies examining cell apoptosis (26 studies, 49.06%), cell proliferation (15 studies, 28.3%), extracellular matrix (ECM) degradation (10 studies, 18.86%), and inflammation (five studies, 9.43%) in IDD patients. Three upregulated miRNAs (miR-19b, miR-32, miR-130b) and three downregulated miRNAs (miR-31, miR-124a, miR-127-5p) were considered common miRNAs in IDD tissues. The top three biological process pathways for upregulated miRNAs were positive regulation of biological process, nervous system development, and negative regulation of biological process, and the top three biological process pathways for downregulated miRNAs were negative regulation of gene expression, intracellular signal transduction, and negative regulation of biological process. Conclusions This study revealed that miRNAs could be novel targets for preventing IDD and treating patients with IDD by regulating their target genes. These results provide valuable information for medical professionals, IDD patients, and health care policy makers.

Sweet Control: MicroRNA Regulation of the Glycome

Glycosylation is a sophisticated informational system that controls specific biological functions at the cellular and organismal level. Dysregulation of glycosylation may underlie some of the most complex and common diseases of the modern era. In the past 5 years, microRNAs have come to the forefront as a critical regulator of the glycome. Herein, we review the current literature on miRNA regulation of glycosylation and how this work may point to a new way to identify the biological importance of glycosylation enzymes.

Bone metabolism regulation: Implications for the treatment of bone diseases

Bone cells in the human body are continuously engaged in cellular metabolism, including the interaction between bone cells, the interaction between the erythropoietic cells of the bone marrow and stromal cells, for the remodeling and reconstruction of bone. Osteoclasts and osteoblasts play an important role in bone metabolism. Diseases occur when bone metabolism is abnormal, but little is known about the signaling pathways that affect bone metabolism. The study of these signaling pathways will help us to use the relevant techniques to intervene, so as to improve the condition. The study of these signaling pathways will help us to use the relevant techniques to intervene, so as to improve the condition. I believe they will shine in the diagnosis and treatment of future clinical bone diseases.

MicroRNAs in Intervertebral Disc Degeneration, Apoptosis, Inflammation, and Mechanobiology

Intervertebral disc (IVD) degeneration is a multifactorial pathological process associated with low back pain, the leading cause of years lived in disability worldwide. Key characteristics of the pathological changes connected with degenerative disc disease (DDD) are the degradation of the extracellular matrix (ECM), apoptosis and senescence, as well as inflammation. The impact of nonphysiological mechanical stresses on IVD degeneration and inflammation, the mechanisms of mechanotransduction, and the role of mechanosensitive miRNAs are of increasing interest. As post-transcriptional regulators, miRNAs are known to affect the expression of 30% of proteincoding genes and numerous intracellular processes. The dysregulation of miRNAs is therefore associated with various pathologies, including degenerative diseases such as DDD. This review aims to give an overview of the current status of miRNA research in degenerative disc pathology, with a special focus on the involvement of miRNAs in ECM degradation, apoptosis, and inflammation, as well as mechanobiology.

Circulating miR-155-5p as a Novel Biomarker of Lumbar Degenerative Disc Disease

MINI: Circulating microRNAs provide an insight into current disease states. Comparing patients with degenerative disc disease to healthy controls, patients with disc disease were found to have significantly downregulated levels of miR-155-5p. This marker was found to be an accurate diagnostic predictor for the presence of degeneration (P = 0.006).

STUDY DESIGN

Case-control study measuring differential gene expression of circulating microRNA (miRNA) in patients with degenerative disc disease (DDD).

OBJECTIVE

To identify miRNA dysregulation in serum samples of patients with DDD compared to healthy controls (HC).

SUMMARY OF BACKGROUND DATA

Early DDD can be a difficult diagnosis to make clinically, with lack of positive and specific findings on physical exam or advanced imaging. miRNAs are a class of molecules that act as gene regulators and have been shown to be dysregulated in local degenerative disc tissue. However, to date no studies have identified dysregulation of serum miRNA in patients with DDD.

METHODS

Whole blood samples were obtained from 69 patients with DDD and 16 HC. Patient-reported outcomes were collected preoperatively and degree of DDD was classified using Pfirrmann grade on preoperative imaging. Differential gene expression analysis using a screening assay for several hundred miRNAs and further characterization for five specific miRNAs (miR-16-5p, miR-21-5p, miR-142-3p, miR-146a-5p, and miR-155-5p) was performed. In addition, a pro-inflammatory cytokine multiplex assay and bioinformatics analysis were done.

RESULTS

The initial screening assay showed 13 miRNA molecules that were significantly dysregulated in DDD patients, with miR-155-5p showing significant downregulation (p = 0.027) and direct interactions with the pro-inflammatory cytokine IL-1β, and the tumor suppressor genes p53 and BRAF. Analyzing the whole cohort, miR-155 showed an almost four-fold downregulation in DDD patients (-3.94-fold, P < 0.001) and was the sole miRNA that accurately predicted the presence of disc degeneration (P = 0.006). Downregulation of miR-155 also correlated with increased leg pain (P = 0.018), DDD (P = 0.006), and higher Pfirrmann grade (P = 0.039). On cytokine analysis, TNF-α (0.025) and IL-6 (P < 0.001) were significantly higher in DDD patients.

CONCLUSION

Serum miR-155-5p is significantly downregulated in patients with DDD and may be a diagnostic marker for degenerative spinal disease.

LEVEL OF EVIDENCE

N/A.

miR-194 suppresses epithelial-mesenchymal transition of retinal pigment epithelial cells by directly targeting ZEB1

Background

Epithelial-mesenchymal transition (EMT) of the retinal pigment epithelial (RPE) cells is a critical step in the pathogenesis of proliferative vitreoretinopathy (PVR). Some microRNAs (miRNAs) participate in regulating RPE cell EMT as post-transcriptional regulators. However, the function of miR-194 in RPE cell EMT remains elusive. Here, the role of miR-194 in PVR was investigated.

Methods

Retinal layers were obtained using laser capture microdissection (LCM). Gene expression at the mRNA and protein level in the tissues and cells was examined using quantitative reverse transcription (RT)-polymerase chain reaction and Western blotting, respectively. The related protein expression was observed by immunostaining. The effect of miR-194 on RPE cell EMT was examined by gel contraction, wound healing, and cell migration assays. RNAseq was performed in ARPE-19 with transfection of pSuper-scramble and pSuper-miR-194. The target gene of miR-194 was identified and confirmed via bioinformatics analysis and dual-luciferase reporter assay. ARPE-19 (adult retinal pigment epithelium-19) cells were treated with transforming growth factor (TGF)-β1 in the same fashion as the in vitro RPE cell EMT model. A PVR rat model was prepared by intravitreous injection of ARPE-19 cells with plasma-rich platelets.

Results

miR-194 was preferentially expressed in the RPE cell layer compared with the outer nuclear layer (ONL), inner nuclear layer (INL), and ganglion cell layer in rat retina. RNAseq analysis indicated that miR-194 overexpression was involved in RPE cell processes, including phagocytosis, ECM-receptor interaction, cell adhesion molecules, and focal adhesion. miR-194 overexpression significantly inhibited the TGF-β1-induced EMT phenotype of RPE cells in vitro. Zinc finger E-box binding homeobox 1 (ZEB1), a key transcription factor in EMT, was confirmed as the direct functional target of miR-194. Knockdown of ZEB1 attenuated TGF-β1-induced α-smooth muscle actin expression in ARPE-19 cells, and overexpression of miR-194 could significantly reduce the expression of some genes which were up-regulated by ZEB1. Exogenous miR-194 administration in vivo effectively suppressed PVR in the rat model, both functionally and structurally.

Conclusions

Our findings demonstrate for the first time that miR-194 suppresses RPE cell EMT by functionally targeting ZEB1. The clinical application of miR-194 in patients with PVR merits further investigation.

Investigation of the effect of dipyrone on cells isolated from intervertebral disc tissue

The present study aimed to evaluate the effects of dipyrone, an indispensable analgesic, anti-pyretic and anti-spasmodic used in emergency departments, on nucleus pulposus and annulus fibrosus cells in vitro. After surgical biopsy, primary cell cultures were prepared from intact intervertebral disc tissues. Dipyrone was administered to the cultures in the experimental groups except for the control group. The data obtained were statistically evaluated. The proliferation was identified to be suppressed via MTT analysis. The gene expression profile of the intervertebral disc cells in the dipyrone-treated groups was significantly changed. The expression of chondroadherin, cartilage oligo matrix protein, interleukin-1β and metalloproteinase (MMP)-19 genes were decreased, but MMP-13 and MMP-7 genes expressions were increased, as determined via reverse transcription-quantitative PCR. AO/PI staining revealed that no apoptotic or other type of cell death was detectable after administration of dipyrone does not mean that the drug is innocuous. The occurrence of cellular senescence and/or the halt of cell proliferation may also be important mechanisms underlying the adverse inhibitory effects of dipyrone. Therefore, prior to administering dipyrone in clinical practice, all possible adverse effects of this drug should be considered.

miR-573 regulates cell proliferation and apoptosis by targeting Bax in nucleus pulposus cells

Background

MicroRNA (miRNA) plays a vital role in the pathogenesis of intervertebral disc degeneration (IDD). The expression and potential mechanism of miR-573 in human nucleus pulposus (NP) remains to be elucidated. In this study, we aimed to investigate the role of miR-573 in IDD.

Methods

Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis was applied to examine the expression of miR-573 and Bax in idiopathic scoliosis tissues and IDD tissues. Human NP cells were employed for analysis. Moreover, the proliferation and apoptosis of NP cells were detected using MTT and flow cytometry assay respectively. The expression levels of Bcl-2, cleaved caspase-3, cleaved caspase-9, caspase-3 and caspase-9 in degenerative NP cells were measured by Western blotting assay. Furthermore, a luciferase reporter assay was used to verify the relationship between miR-573 and Bax.

Results

The results revealed that the mRNA expression level of miR-573 was down-regulated whereas Bax was up-regulated notably in degenerative NP cells. In addition, overexpression of miR-573 increased cell viability remarkably, coupled with inhibition of cell apoptosis. The expression level of Bcl-2 was increased while cleaved caspase-3 and cleaved caspase-9 expression levels were decreased in miR-573 overexpression NP cells. Additionally, the bioinformatics analysis underscored that Bax was a direct target gene of miR-573.

Conclusion

These results suggest that overexpression of miR-573 inhibited NP cell apoptosis by down-regulating Bax, which proved to be a novel effective strategy for IDD therapies.

MicroRNA-155 suppresses the catabolic effect induced by TNF-α and IL-1β by targeting C/EBPβ in rat nucleus pulposus cells

AIM

miR-155 is a pro-inflammatory or anti-inflammatory factor depending on the cell type in which it is expressed. miR-155 controls apoptosis and matrix degradation in nucleus pulposus (NP) cells in vitro. The aim of this study is to explore the effect of miR-155 in vivo and further investigate the mechanism of miR-155 in vitro.

METHODS

MRI, hematoxylin-eosin staining, or Collagen-II immunochemistry were performed to observe intervertebral disk degeneration in conditional miR-155 overexpression mice and miR-155 knockout mice. In vitro, a dual luciferase reporter assay, real-time PCR and western blot experiments were performed to demonstrate the effect of miR-155 on the expression of catabolic genes induced by inflammatory cytokines and determine the role of β-catenin and C/EBPβ in the miR-155-mediated modulation of the expression of catabolic genes.

RESULTS

Degeneration was observed in the lumbar disks of 1-year-old miR-155 knockout mice but not in the conditional miR-155 overexpression mice. miR-155 overexpression repressed the catabolic effect induced by TNF-α or IL-1β in vitro. Furthermore, specifically in NP cells, miR-155 overexpression suppressed the expression of C/EBPβ but not of β-catenin. Additionally, in the loss-of-function experiments using C/EBPβ siRNA, C/EBPβ knockdown repressed the expression of catabolic genes induced by TNF-α and IL-1β, which is consistent with the miR-155 results.

CONCLUSION

miR-155 is a sustainable factor for intervertebral disk and suppresses the expression of catabolic genes induced by TNF-α and IL-1β by targeting C/EBPβ in rat NP cells.

Glycosaminoglycan synthesis in the nucleus pulposus: Dysregulation and the pathogenesis of disc degeneration

Few human tissues have functions as closely linked to the composition of their extracellular matrices as the intervertebral disc. In fact, the hallmark of intervertebral disc degeneration, commonly accompanying low back and neck pain, is the progressive loss of extracellular matrix molecules - specifically the GAG-substituted proteoglycans. While this loss is often associated with increased extracellular catabolism via metalloproteinases and pro-inflammatory cytokines, there is strong evidence that disc degeneration is related to dysregulation of the enzymes involved in GAG biosynthesis. In this review, we discuss those environmental factors, unique to the disc, that control expression and function of XT-1, GlcAT-I, and ChSy/ChPF in the healthy and degenerative state. Additionally, we address the pathophysiology of aberrant GAG biosynthesis and highlight therapeutic strategies designed to augment the loss of extracellular matrix molecules that afflict the degenerative state.

Detection of miR‑29a in plasma of patients with lumbar spinal stenosis and the clinical significance

The present study aimed to detect miR-29a expression in the plasma of patients with lumbar spinal stenosis (LSS) and to investigate the clinical significance. A total of 30 patients with LSS, 27 patients with lumbar intervertebral disc herniation (LDH), 27 healthy people and 7 patients that had succumbed to mortality were involved in the present study for specimen collection. Expression levels of miR-29a in plasma and intervertebral disc tissue were detected by reverse transcription-quantitative polymerase chain reaction analysis. Plasma expression levels of matrix metalloproteinase 9 (MMP9) and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) were detected ELISA. The expression levels of MMP9 and ADAMTS5 protein were detected by western blotting. Pearson correlation analysis was used to analyze the correlations between the expression levels of microRNA (miR)-29a, MMP9 and ADAMTS5. Receiver operating characteristic curve analysis was used to analyze the possibility of the use of miR-29a as a biomarker of LSS. The expression levels of miR-29a in plasma and intervertebral disc tissue of patients with LSS were significantly lower in patients with LSS compared with in patients with LDH, as well as healthy controls. Conversely, the protein expression levels of MMP9 and ADAMTS5 were significantly higher in patients with LSS compared with patients with LDH, as well as healthy controls. The expression levels of miR-29a was negatively correlated with the expression levels of MMP9 and ADAMTS5. In addition, miR-29a demonstrated low temperature sensitivity and high freeze-thaw stability, and may be used to accurately diagnose LSS. Therefore, miR-29a may be considered to be a potential biomarker of LSS.

Role of miR-589-3p in human lumbar disc degeneration and its potential mechanism

The present study aimed to investigate the role of miR-589-3p in lumbar disc degeneration (LDD) and to explore the underlying mechanisms. Nucleus pulposus (NP) cells were stimulated with lipopolysaccharide (LPS) to simulate an in vitro model of intervertebral disc degeneration. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression level of microRNA (miR)-589-3p in the NP cells, and the results demonstrated that the increased expression of miR-589-3p in LPS stimulated NP cells compared with the control. To further investigate the role of miR-589-3p in LDD, a human NP cell line with high/low miR-589-3p expression was generated using miR-589-3p mimics/inhibitors. In addition, a human NP cell inflammation model was conducted by LPS (10 µM) treatment. Western blot analysis and RT-qPCR were performed for detection of associated genes and proteins. Protein levels of pro-inflammatory factors, including tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 were evaluated by ELISA. Flow cytometry was used for cell apoptosis determination. Furthermore, Targetscan was used to predict potential targets of miR-589-3p, and a dual luciferase reporter assay was used to verify the prediction. The findings verified that miR-589-3p was significantly upregulated in LDD. In vitro, miR-589-3p mimics/inhibitors significantly increased/reduced the production of TNF-α, IL-1β and IL-6 in LPS stimulated NP cells. Furthermore, miR-589-3p mimics/inhibitors significantly promoted/inhibited LPS stimulated NP cell apoptosis. MiR-589-3p mimics/inhibitors significantly repressed/enhanced type II collagen and aggrecan expression in LPS stimulated NP cells. In addition, it was demonstrated that mothers against decapentaplegic homolog (Smad) 4 was a direct target gene of miR-589-3p, and was negatively regulated by miR-589-3p in NP cells. In conclusion, miR-589-3p may function as a promoter in LDD development via the regulation of Smad4.