The role of matrix metalloproteinase 9 in intervertebral disc degeneration

Identification of key eRNAs for intervertebral disc degeneration by integrated multinomial bioinformatics analysis

BACKGROUND

Intervertebral disc degeneration (IVDD) is a common degenerative condition leading to abnormal stress distribution under load, causing intervertebral stenosis, facet joint degeneration, and foraminal stenosis. Very little is known about the molecular mechanism of eRNAs in IVDD.

METHODS

Gene expression profiles of 38 annulus disc samples composed of 27 less degenerated discs (LDs) and 11 more degenerated discs (MDs) were retrieved from the GEO database. Then, differentially expressed enhancer RNAs (DEeRNAs), differentially expressed target genes (DETGs), and differentially expressed transcription factors (DETFs), hallmark of cancer signalling pathways according to GSVA; the types and quantity of immune cells according to CIBERSORT; and immune gene sets according to ssGSEA were analysed to construct an IVDD-related eRNA network. Then, multidimensional validation was performed to explore the interactions among DEeRNAs, DETFs and DEGs in space.

RESULTS

A total of 53 components, 14 DETGs, 15 DEeRNAs, 3 DETFs, 5 immune cells, 9 hallmarks, and 7 immune gene sets, were selected to construct the regulatory network. After validation by online multidimensional databases, 21 interactive DEeRNA-DEG-DETF axes related to IVDD exacerbation were identified, among which the C1S-CTNNB1-CHD4 axis was the most significant.

CONCLUSION

Based upon the results of our study, we theorize that the C1S-CTNNB1-CHD4 axis plays a vital role in IVDD exacerbation. Specifically, C1S recruits CTNNB1 and upregulates the expression of CHD4 in IVDD, and subsequently, CHD4 suppresses glycolysis and activates oxidative phosphorylation, thus generating insoluble collagen fibre deposits and leading to the progression of IVDD. Overall, these DEeRNAs could comprise promising therapeutic targets for IVDD due to their high tissue specificity.

Adipokine human Resistin promotes obesity-associated inflammatory intervertebral disc degeneration via pro-inflammatory cytokine cascade activation

Adipokine human Resistin (hResistin), is known to be associated with insulin resistance and secrete low-grade pro-inflammatory cytokines in obesity. Although studies on low-grade inflammation of adipokine hResistin are known, studies on the effects and mechanisms of intervertebral disc degeneration (IVDD) are still lacking. Thus, we investigated the adipokine hResistin with or without pro-inflammatory cytokine IL-1β in intervertebral disc (IVD) cells such as human annulus fibrosus (hAF) and nucleus pulposus (hNP). The protein expression changes in IL-1β, IL-6, IL-8, MMP-1, MMP-3, and MMP-13, induced by the combined-hResistin and IL-1β stimulation on hAF cells, was significantly greater than that of the same induced by mono-IL-1β stimulation. Similarly, in the case of the protein expression change of inflammatory mediators induced by the combined-hResistin and IL-1β stimulation on hNP cells was also significantly greater than that of the same induced by mono-IL-1β stimulation. These results improve understanding of hResistin on inflammatory IVDD but also with other obesity-related inflammatory diseases.

Network Pharmacological Dissection of the Mechanisms of Eucommiae Cortex-Achyranthis Radix Combination for Intervertebral Disc Herniation Treatment

Eucommiae cortex (EC) and Achyranthis radix (AR) are herbal medicines widely used in combination for the treatment of intervertebral disc herniation (IDH). The mechanisms of action of the herbal combination have not been understood from integrative and comprehensive points of view. By adopting network pharmacological methodology, we aimed to investigate the pharmacological properties of the EC-AR combination as a therapeutic agent for IDH at a systematic molecular level. Using the pharmacokinetic information for the chemical ingredients of the EC-AR combination obtained from the comprehensive herbal drug-associated databases, we determined its 31 bioactive ingredients and 68 IDH-related therapeutic targets. By analyzing their enrichment for biological functions, we observed that the targets of the EC-AR combination were associated with the regulation of angiogenesis; cytokine and chemokine activity; oxidative and inflammatory stress responses; extracellular matrix organization; immune response; and cellular processes such as proliferation, apoptosis, autophagy, differentiation, migration, and activation. Pathway enrichment investigation revealed that the EC-AR combination may target IDH-pathology-associated signaling pathways, such as those of cellular senescence and chemokine, neurotrophin, TNF, MAPK, toll-like receptor, and VEGF signaling, to exhibit its therapeutic effects. Collectively, these data provide mechanistic insights into the pharmacological activity of herbal medicines for the treatment of musculoskeletal diseases such as IDH.

Effect of voluntary running activity on mRNA expression of extracellular matrix genes in a mouse model of intervertebral disc degeneration

INTRODUCTION

Low back pain (LBP), a leading cause of global disability, is often associated with intervertebral disc degeneration (IDD). Exercise therapy is recommended for chronic LBP management and affects many tissues and organ systems. However, the ability of exercise to repair the extracellular matrix (ECM) in degenerating discs is unclear. The aims of the study were to examine mRNA expression of ECM structural components (collagen I, II, X, aggrecan) and regulators of matrix turnover (matrix metalloproteinases (MMP)-3, - 9, - 13, ADAMTS-4, - 5, TIMP1-4, CCN2) between age-matched (a) wild-type and secreted protein acidic and rich in cysteine (SPARC)-null, (b) sedentary and active, and (c) male and female mice.

METHODS

At 8 months of age, male and female SPARC-null and wild-type control mice received a home cage running wheel or a control, fixed wheel for 6 months. Deletion of the SPARC gene results in progressive IDD beginning at 2 to 4 months of age. Increased activity was confirmed, and qPCR was performed on excised lumbar discs.

RESULTS

Male SPARC-null mice expressed less aggrecan mRNA than wild-type controls. After 6 months of running, collagen, MMP3, and MMP13 expression was increased in male and MMP3 was increased in female SPARC-null mice. Sex differences were observed in wild-type mice and in response to IDD and long-term running.

CONCLUSIONS

Voluntary running results in changes in mRNA consistent with increased ECM turnover and disc regeneration. Improved disc ECM might contribute to the beneficial effects of exercise on LBP and may create an intradiscal environment hospitable to regenerative therapies. Sex-specific differences should be considered in the development of disc-targeting therapies.

Uncovering the secretome of mesenchymal stromal cells exposed to healthy, traumatic, and degenerative intervertebral discs: a proteomic analysis

BACKGROUND

Mesenchymal stromal cells (MSCs) have been introduced as promising cell source for regenerative medicine. Besides their multilineage differentiation capacity, MSCs release a wide spectrum of bioactive factors. This secretome holds immunomodulatory and regenerative capacities. In intervertebral disc (IVD) cells, application of MSC secretome has been shown to decrease the apoptosis rate, induce proliferation, and promote production of extracellular matrix (ECM). For clinical translation of secretome-based treatment, characterization of the secretome composition is needed to better understand the induced biological processes and identify potentially effective secretomes.

METHODS

This study aimed to investigate the proteome released by bone marrow-derived MSCs following exposure to a healthy, traumatic, or degenerative human IVD environment by mass spectroscopy and quantitative immunoassay analyses. Exposure of MSCs to the proinflammatory stimulus interleukin 1β (IL-1β) was used as control.

RESULTS

Compared to MSC baseline secretome, there were 224 significantly up- or downregulated proteins following healthy, 179 following traumatic, 223 following degenerative IVD, and 160 proteins following IL-1β stimulus. Stimulation of MSCs with IVD conditioned media induced a more complex MSC secretome, involving more biological processes, compared to stimulation with IL-1β. The MSC response to stimulation with IVD conditioned medium was dependent on their pathological status.

CONCLUSIONS

The MSC secretome seemed to match the primary need of the IVD: homeostasis maintenance in the case of healthy IVDs, versus immunomodulation, adjustment of ECM synthesis and degradation disbalance, and ECM (re) organization in the case of traumatic and degenerative IVDs. These findings highlight the importance of cell preconditioning in the development of tailored secretome therapies. The secretome of human bone marrow-derived mesenchymal stromal cells (MSCs) stimulated with intervertebral disc (IVD) conditioned medium was analyzed by proteomic profiling. Depending on the pathological state of the IVD, the MSC secretome protein composition indicated immunomodulatory or anabolic activity of the secretome. These findings may have implications for tailored secretome therapy for the IVD and other tissues.

Human mesenchymal stem cells respond differentially to platelet preparations and synthesize hyaluronic acid in nucleus pulposus extracellular matrix

BACKGROUND CONTEXT

In recent years, autologous platelet-rich plasma (PRP) and bone marrow aspirate concentrate (BMAC) have been used as treatments for disc-related pain. A better understanding of the effects of leukocyte-rich (LR) versus leukocyte poor (LP-) PRP on bone marrow derived human mesenchymal stem/progenitor cells (hMSCs) is likely to improve future research studies, clinical practice and care for patients with chronic discogenic back pain.

PURPOSE

The primary aim of this study is to determine the effects of LR-PRP and LP-PRP on the proliferation and migration of hMSCs in pig nucleus pulposus (NP) extracellular matrix (ECM). The secondary aim is to characterize hMSC-dependent expression of the matrix remodeling enzymes metalloproteinases MMP-2, MMP-3, MMP-9 and tissue inhibitor of metalloproteinases TIMP-2, and to determine whether transplanted hMSCs can synthesize hyaluronic acid (HA).

STUDY DESIGN

Controlled laboratory study.

METHODS

Bone marrow-derived culture expanded hMSCs were seeded onto pig NP and cultured with LR-PRP, LP-PRP or serum/platelet releasate (PR). The same conditions without hMSCs were used as controls. hMSC proliferation, migration and dispersion was assessed via fluorescent microscopy, while HA synthesis, MMP-2, MMP-3, MMP-9, and TIMP-2 protein levels were assessed via enzyme linked immunosorbent assay. All funding was provided by a 501c(3) research foundation and does not have any commercial or sponsorship interests.

RESULTS

LP-PRP and PR cultures resulted in higher hMSC proliferation, migration, dispersion, and MMP-2 expression. LP-PRP cultures resulted in the highest HA production. LR-PRP cultures resulted in lower hMSC proliferation, negligible migration and dispersion, increased MMP-9 expression and lower HA production.

CONCLUSIONS

Human bone marrow-derived hMSCs seeded onto pig NP ECM are capable of synthesizing HA, indicating a transition towards a NP cell phenotype. This process was most enhanced by LP-PRP and marked by increased hMSC proliferation, MMP-2 production, HA synthesis and reduced MMP-9 levels.

CLINICAL SIGNIFICANCE

LP-PRP and PR, with or without hMSCs, may provide better outcomes than LR-PRP in lab investigations and clinical trials for discogenic pain. Bone marrow-derived hMSCs may hold promise as a treatment for disc degeneration.

Therapeutic evaluation of acupoint stimulation with needle-scapelon on rat model of degenerative cervical intervertebral discs

Cervical spondylosis (CS), which is resulted from degeneration of cervical intervertebral disc, is a common disease seriously threatening human health and quality of life. However, there is still no effective clinic strategies for the treatment of this disease. The acupoint stimulation with needle-scalpel is a widely used approach to treat orthopedic diseases. In the present study, we evaluated the therapeutic effects of acupoint stimulation around neck with needle-scalpel on delaying the degeneration of cervical intervertebral discs and hopefully provided an approach for the precaution and early intervention of CS. We firstly established a rat model of CS by cervical static-dynamic imbalance to mimics disc degeneration and then stimulated the acupoints around neck with needle-scalpel. The cervical intervertebral disc samples were collected to measure type I and II collagen by quantitative PCR (qPCR), immunohistochemistry, and western blot. The changes in micro-structure and ultra-structure of nucleus pulposus were analyzed under the optical microscope and electron microscope respectively. Acupoint stimulation with needle-scapelon increased type I collagen production and decreased type II collagen production, and improved the micro-structure and ultra-structure of nucleus pulposus. Our results suggest that acupoint stimulation around neck with needle-scapelon could inhibit intervertebral disc degeneration through modulating the extracellular matrix collagen system and improving the changed structure of nucleus pulposus.

Evaluation of Common Variants in Matrix Metalloproteinase-9 Gene with Lumbar Disc Herniation in Han Chinese Population

OBJECTIVE

Lumbar disc herniation (LDH) is a common and frequent orthopedic disease with strong genetic determinants. The disruption of the intervertebral disc extracellular matrix has been found to play a key role in the development of LDH, suggesting that abnormal matrix metalloproteinases (MMPs) may promote the degradation of the disc matrix. MMP-9, an important member of the MMP family, is a good candidate for the LDH susceptibility gene. The present study aimed to investigate the association of common variants in the MMP-9 gene with the risk, severity, and clinical characteristic variables of LDH.

MATERIALS AND METHODS

Fourteen tag single nucleotide polymorphisms (SNPs) entirely covering the region of the MMP-9 gene were analyzed in a sample of 845 patients and 1751 healthy controls.

RESULTS

The SNP rs17576 was found to be significantly associated with susceptibility to LDH (OR = 0.77, p = 0.0002), which was also confirmed by haplotype-based analyses (rs79845319-rs17576-rs45437897, global p < 0.001). Our results indicated that the A allele of rs17576 reduced the risk of LDH by ∼23% on average. Furthermore, the G allele of rs17576 was found to correlate with more severe grades of disc degeneration.

CONCLUSION

Our results provide additional evidence supporting an important role of the MMP-9 gene in the pathogenesis of LDH.

Neuroprotective effects of curcumin alleviate lumbar intervertebral disc degeneration through regulating the expression of iNOS, COX‑2, TGF‑β1/2, MMP‑9 and BDNF in a rat model

Curcumin is a natural product with antimutagenic, antitumor, antioxidant and neuroprotective properties. However, to the best of our knowledge, curcumin has yet to be investigated for the treatment of lumbar intervertebral disc degeneration LIDD). The aim of the present study was to investigate whether curcumin can alleviate LIDD through regulating the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)‑2, transforming growth factor (TGF)‑β1/2, matrix metalloproteinase (MMP)‑9 and brain‑derived neurotrophic factor (BDNF) in a rat model of LIDD. The results of the present study suggest that pretreatment with curcumin can prevent the development of LIDD in rats. It was revealed that treatment with curcumin significantly reduced interleukin (IL)‑1β and IL‑6, iNOS, COX‑2 and MMP‑9 levels in rats with LIDD. In addition, treatment with curcumin reduced the mRNA expression levels of TGF‑β1 and TGF‑β2, whereas it increased the mRNA expression levels of BDNF in rats with LIDD. In conclusion, the present findings indicate that curcumin may exert protective effects on LIDD development, exerting its action through the regulation of iNOS, COX‑2, TGF‑β1/2, MMP‑9 and BDNF.

Correlation of matrix metalloproteinase (MMP)-1, -2, -3, and -9 expressions with demographic and radiological features in primary lumbar intervertebral disc disease

Degeneration of IVD is a progressive and irreversible process and can be evaluated with immunohistochemical examination or radiological grading. MMPs are a family of proteolytic enzymes and involved in the degradation of the matrix components of the IVD. We aimed to compare MMP-1, -2, -3, and -9 expressions with demographic features, visual analogue scale (VAS), Oswestry Disability Index (ODI) and radiological (MRI) grades. The study involved 60 participants. We recorded data about age, complaint, radiological imaging, expression levels of MMP-1, -2, -3, and -9, ODI and VAS for back pain retrospectively. Intervertebral disc degeneration was graded on a 0-5 scale according to the Pfirrmann classification. As a result of the study, the median age was 52.09±12.74years. There were statistical significances between age and MMP-1, and MMP-2. There was a close correlation between grade and MMP-9. We found correlation between the VAS and the MMP-9 expression. In addition, there was relationship between expression of MMP-2 and MMP-1, MMP-3, MMP-9. In conclusion, the expressions of MMP-1 and -2 are increased with aging. There was no relationship between radiological evaluation of IVDD and aging. Increased expression of MMPs affected IVDD positively. The relationship with MMPs is not explained. This study adds to our understanding of the interaction between MMPs and IVDD.

Mesenchymal Stem/Stromal Cells seeded on cartilaginous endplates promote Intervertebral Disc Regeneration through Extracellular Matrix Remodeling

Intervertebral disc (IVD) degeneration is characterized by significant biochemical and histomorphological alterations, such as loss of extracellular matrix (ECM) integrity, by abnormal synthesis of ECM main components, resultant from altered anabolic/catabolic cell activities and cell death. Mesenchymal Stem/Stromal Cell (MSC) migration towards degenerated IVD may represent a viable strategy to promote tissue repair/regeneration. Here, human MSCs (hMSCs) were seeded on top of cartilaginous endplates (CEP) of nucleotomized IVDs of bovine origin and cultured ex vivo up to 3 weeks. hMSCs migrated from CEP towards the lesion area and significantly increased expression of collagen type II and aggrecan in IVD, namely in the nucleus pulposus. Concomitantly, hMSCs stimulated the production of growth factors, promoters of ECM synthesis, such as fibroblast growth factor 6 (FGF-6) and 7 (FGF-7), platelet-derived growth factor receptor (PDGF-R), granulocyte-macrophage colony-stimulating factor (GM-CSF) and insulin-like growth factor 1 receptor (IGF-1sR). Overall, our results demonstrate that CEP can be an alternative route to MSC-based therapies for IVD regeneration through ECM remodeling, thus opening new perspectives on endogenous repair capacity through MSC recruitment.

The role of matrix metalloproteinase 14 polymorphisms in susceptibility to intervertebral disc degeneration in the Chinese Han population

INTRODUCTION

Matrix metalloproteinase 14 (MMP14) plays an important role in the pathophysiology of intervertebral disc degeneration (IVDD). The present study aimed to determine whether two single nucleotide polymorphisms (-378 T/C and -364 G/T) of MMP14 were associated with the risk and severity of IVDD in the Chinese Han population.

MATERIAL AND METHODS

A total of 908 patients with IVDD and 906 healthy controls were enrolled in this study. The grade of disc degeneration was determined according to Schneiderman's classification for magnetic resonance imaging. The polymorphisms of MMP14 were genotyped using polymerase chain reaction and direct sequencing.

RESULTS

The genotype distribution of -364G/T did not show a significant difference between IVDD patients and healthy controls. The frequencies of the -378T/C and CC genotypes were significantly lower among IVDD patients compared with healthy controls (p < 0.001); unconditional logistic regression analysis revealed that the CT and CC genotypes were significantly associated with a decreased risk of IVDD compared with the TT genotype (p < 0.001). Patients with IVDD showed significantly higher frequencies of the T allele at -378T/C than healthy controls (p < 0.001). In addition, the -375 CC genotype, as well as the C allele, was associated with lower degenerative grades of IVDD compared with the TT genotype and the T allele, respectively (both p < 0.001).

CONCLUSIONS

The -378T/C polymorphism of MMP14 may be associated with the risk and severity of IVDD in the Chinese Han population. It shows potential to become a biomarker to predict risk and severity of IVDD.