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

Human molecular mechanisms of discogenic low back pain: A scoping review

The limited understanding of the mechanisms underlying human discogenic low back pain (DLBP) has hampered the development of effective treatments. While there is much research on disc degeneration, the association between degeneration and pain is weak. Therefore, there is an urgent need to identify pain-inducing molecular mechanism to facilitate the development of mechanism-specific therapeutics. This scoping review aims to determine the current knowledge of molecular mechanisms associated with human DLBP. A systematic search on CENTRAL, CINAHL, Citation searching, ClinicalTrials.gov, Embase, Google Scholar, MEDLINE, PsycINFO, PubMed, Scopus, Web of Science, and World Health Organization was performed. Studies with human DLBP as diagnosed by discography or imaging that analyzed human disc tissues and reported pain-related outcomes were included, and those on predominant radicular pain were excluded. The search returned 6012 studies. Most studies did not collect pain-related outcomes. Those that included pain assessment relied on self-report of pain intensity and disability. Six studies qualified for data extraction and synthesis. The main molecular mechanisms associated with DLBP were the expressions of nociceptive neuropeptides and cytokines, particularly TNF-αdue to its strong association with pain outcomes. Activation of NF-κB signaling pathway, alterations in adrenoceptor expressions, and increase in reactive oxygen species (ROS) were also associated with DLBP through regulation of pro-inflammatory factors and pain-related neuropeptides. Current evidence converges to TNF-α, NF-κB signaling, and ROS-induced pro-inflammation. Major weaknesses in the current literature are the focus on degeneration without pain phenotyping, and lack of association of molecular findings with pain outcomes. PERSPECTIVE: This scoping review identified TNF-α, NF-κB signaling, and ROS-induced pro-inflammation as relevant mechanisms of human discogenic low back pain. Major weaknesses in the current literature are the focus on degeneration without pain phenotyping, and lack of association of molecular findings with pain outcomes.

Sequential Targeted Enzyme-Instructed Self-Assembly Supramolecular Nanofibers to Attenuate Intervertebral Disc Degeneration

As an age-related disease, intervertebral disc degeneration is closely related to inflammation and aging. Inflammatory cytokines and cellular senescence collectively contribute to the degradation of intervertebral disc. Blocking this synergy reduces disc extracellular matrix damage caused by inflammation and aging. In this study, drug-loaded nanofibers with sequential targeting functions are constructed through intelligent response, hydrophilicity, and in situ self-assembly empowerment of flurbiprofen. The peptide precursor responds to the cleavage of overexpressed MMP-2 in the degenerative intervertebral disc microenvironment (intracellular and extracellular), resulting in the formation of self-assembled nanofibers that enable the on-demand release of flurbiprofen and COX-2 response. In vitro, Comp. 1 (Flurbiprofen-GFFYPLGLAGEEEERGD) reduces the expression of inflammation-related genes and proteins and the polarization of M1 macrophages by competitively inhibiting COX-2 and increases the expression of extracellular matrix proteins COL-2 and aggrecan. Additionally, it can reduce the expression of Senescence-Associated Secretory Phenotype and DNA damage in aged nucleus pulposus cells and promote the recovery of proliferation and cell cycle. In vivo, drug-loaded nanofibers delay intervertebral disc degeneration by inhibiting inflammation and preventing the accumulation of senescent cells. Therefore, the sequentially targeted self-assembled drug-loaded nanofibers can delay intervertebral disc degeneration by blocking the synergistic effect of inflammatory cytokines and cellular senescence.

Repair of annulus fibrosus defects using decellularized annulus fibrosus matrix/chitosan hybrid hydrogels

Degenerative disc disease is the leading cause of lower back and leg pain, considerably impacting daily life and incurring substantial medical expenses for those affected. The development of annulus fibrosus tissue engineering offers hope for treating this condition. However, the current annulus fibrosus tissue engineering scaffolds fail to accurately mimic the natural biological environment of the annulus fibrosus, resulting in limited secretion of extracellular matrix produced by the seeded cells and poor biomechanical properties of the constructed biomimetic annulus fibrosus tissue. This inability to match the biomechanical performance of the natural annulus fibrosus hinders the successful treatment of annulus fibrosus defects. In this study, we fabricated decellularized annulus fibrosus matrix (DAFM)/chitosan hydrogel-1 (DAFM: Chitosan 6:2) and DAFM/chitosan hydrogel-2 (DAFM: Chitosan 4:4) by varying the ratio of DAFM to chitosan. Rat annulus fibrosus (AF)-derived stem cells were cultured on these hydrogel scaffolds, and the cell morphology, AF-related gene expression, and Interleukin-6 (IL-6) levels were investigated. Additionally, magnetic resonance imaging, Hematoxylin and eosin staining, and Safranine and Fast Green staining were performed to evaluate the repair effect of the DAFM/chitosan hydrogels in vivo. The gene expression results showed that the expression of Collagen type I (Col-I), Collagen type I (Col-II), and aggrecan by annulus fibrosus stem cells (AFSCs) cultured on the DAFM/chitosan-1 hydrogel was higher compared with the DAFM/chitosan-2 hydrogel. Conversely, the expression of metalloproteinase-9 (MMP-9) and IL-6 was lower on the DAFM/chitosan-1 hydrogel compared with the DAFM/chitosan-2 hydrogel. In vivo, both the DAFM/chitosan-1 and DAFM/chitosan-2 hydrogels could partially repair large defects of the annulus fibrosus in rat tail vertebrae. In conclusion, the DAFM/chitosan-1 hydrogel could be regarded as a candidate scaffold material for the repair of annulus fibrosus defects, offering the potential for improved treatment outcomes.

Pathogenesis and therapeutic implications of matrix metalloproteinases in intervertebral disc degeneration: A comprehensive review

Intervertebral disc (IVD) degeneration (IDD) is a common disorder that affects the spine and is a major cause of lower back pain (LBP). The extracellular matrix (ECM) is the structural foundation of the biomechanical properties of IVD, and its degradation is the main pathological characteristic of IDD. Matrix metalloproteinases (MMPs) are a group of endopeptidases that play an important role in the degradation and remodeling of the ECM. Several recent studies have shown that the expression and activity of many MMP subgroups are significantly upregulated in degenerated IVD tissue. This upregulation of MMPs results in an imbalance of ECM anabolism and catabolism, leading to the degradation of the ECM and the development of IDD. Therefore, the regulation of MMP expression is a potential therapeutic target for the treatment of IDD. Recent research has focused on identifying the mechanisms by which MMPs cause ECM degradation and promote IDD, as well as on developing therapies that target MMPs. In summary, MMP dysregulation is a crucial factor in the development of IDD, and a deeper understanding of the mechanisms involved is needed to develop effective biological therapies that target MMPs to treat IDD.

Intervertebral disc degeneration-Current therapeutic options and challenges

Degeneration of the intervertebral disc (IVD) is a normal part of aging. Due to the spine's declining function and the development of pain, it may affect one's physical health, mental health, and socioeconomic status. Most of the intervertebral disc degeneration (IVDD) therapies today focus on the symptoms of low back pain rather than the underlying etiology or mechanical function of the disc. The deteriorated disc is typically not restored by conservative or surgical therapies that largely focus on correcting symptoms and structural abnormalities. To enhance the clinical outcome and the quality of life of a patient, several therapeutic modalities have been created. In this review, we discuss genetic and environmental causes of IVDD and describe promising modern endogenous and exogenous therapeutic approaches including their applicability and relevance to the degeneration process.

The role of ADAMTS6 and ADAMTS17 polymorphisms in susceptibility to lumbar disc herniation in Chinese Han population

PURPOSE

LDH caused by lumbar disc degeneration is associated with genetic factors. However, the role of ADAMTS6 and ADAMTS17 genes in LDH risk is still unknown.

METHODS

To investigate the interaction between ADAMTS6 and ADAMTS17 variants in the susceptibility of LDH, five SNPs were genotyped in 509 patients and 510 healthy individuals. The experiment used logistic regression to calculate odds ratio (OR) and 95% confidence interval (CI). Multi-factor dimensionality reduction (MDR) was chosen to evaluate impact of interaction of SNP-SNP on susceptibility to LDH.

RESULTS

ADAMTS17-rs4533267 is significantly associated with reducing risk of LDH (OR = 0.72, 95% CI = 0.57-0.90, p = 0.005). Stratified analysis indicates that ADAMTS17-rs4533267 is significantly associated with the reducing risk of LDH among participants aged ≤ 48 years old. In addition, we observed that ADAMTS6-rs2307121 was associated with increasing risk of LDH in females. MDR analysis shows that single-locus model composed by ADAMTS17-rs4533267 can be chosen as the best model for predicting susceptibility to LDH (CVC = 10/10, test accuracy = 0.543).

CONCLUSION

ADAMTS6-rs2307121 and ADAMTS17-rs4533267 are potentially associated with LDH susceptibility. In particular, ADAMTS17-rs4533267 has a strong association with reducing risk of LDH.

A novel rat model of vertebral inflammation-induced intervertebral disc degeneration mediated by activating cGAS/STING molecular pathway

In this study, we describe a new rat model of vertebral inflammation-induced caudal intervertebral disc degeneration (VI-IVDD), in which IVD structure was not damaged and controllable segment and speed degeneration was achieved. VI-IVDD model was obtained by placing lipopolysaccharide (LPS) in the caudal vertebral bodies of rats. Rat experimental groups were set as follows: normal control group, group with a hole drilled in the middle of vertebral body and not filled with LPS (Blank group), group with a hole drilled in the middle of vertebral body and filled with LPS (Mid group), and group with hole drilled in the vertebral body in proximity of IVD and filled with LPS (NIVD group). Radiological results of VI-IVDD rats showed a significant reduction in the intervertebral space height and decrease in MRI T2 signal intensity. Histological stainings also revealed that the more the nucleus pulposus and endplate degenerated, the more the annulus fibrosus structure appeared disorganized. Immunohistochemistry analysis demonstrated that the expression of Aggrecan and collagen-II decreased, whereas that of MMP-3 increased in Mid and NIVD groups. Abundant local production of pro-inflammatory cytokines was detected together with increased infiltration of M1 macrophages in Mid and NIVD groups. Apoptosis ratio remarkably enhanced in Mid and NIVD groups. Interestingly, we found a strong activation of the cyclic GMP-AMP synthase /stimulator of interferon gene signalling pathway, which is strictly related to inflammatory and degenerative diseases. In this study, we generated a new, reliable and reproducible IVDD rat model, in which controllable segment and speed degeneration was achieved.

Platelet-Derived Biomaterials Inhibit Nicotine-Induced Intervertebral Disc Degeneration Through Regulating IGF-1/AKT/IRS-1 Signaling Axis

Apart from aging process, adult intervertebral disc (IVD) undergoes various degenerative processes. However, the nicotine has not been well identified as a contributing etiology. According to a few studies, nicotine ingestion through smoking, air or clothing may significantly accumulate in active as well as passive smokers. Since nicotine has been demonstrated to adversely impact various physiological processes, such as sympathetic nervous system, leading to impaired vasculature and cellular apoptosis, we aimed to investigate whether nicotine could induce IVD degeneration. In particular, we evaluated dose-dependent impact of nicotine in vitro to simulate its chronic accumulation, which was later treated by platelet-derived biomaterials (PDB). Further, during in vivo studies, mice were subcutaneously administered with nicotine to examine IVD-associated pathologic changes. The results revealed that nicotine could significantly reduce chondrocytes and chondrogenic indicators (Sox, Col II and aggrecan). Mice with nicotine treatment also exhibited malformed IVD structure with decreased Col II as well as proteoglycans, which was significantly increased after PDB administration for 4 weeks. Mechanistically, PDB significantly restored the levels of IGF-1 signaling proteins, particularly pIGF-1 R, pAKT, and IRS-1, modulating ECM synthesis by chondrocytes. Conclusively, the PDB impart reparative and tissue regenerative processes by inhibiting nicotine-initiated IVD degeneration, through regulating IGF-1/AKT/IRS-1 signaling axis.

Matrix Metalloproteinase Inspired Therapeutic Strategies for Bone Diseases

Matrix Metalloproteinases (MMPs), as a family of zinc-containing enzymes, show the function of decomposing Extracellular Matrix (ECM) and participate in the physiological processes of cell migration, growth, inflammation, and metabolism. Clinical and experimental studies have indicated that MMPs play an essential role in tissue injury and repair as well as tumor diagnosis, metastasis, and prognosis. An increasing number of researchers have paid attention to their functions and mechanisms in bone health and diseases. The present review focuses on MMPs-inspired therapeutic strategies for the treatment of bone-related diseases. We introduce the role of MMPs in bone diseases, highlight the MMPs-inspired therapeutic options, and posit MMPs as a trigger for smart cell/drug delivery.

Integrated traditional Chinese medicine alleviates sciatica while regulating gene expression in peripheral blood

Background

Although integrated traditional Chinese medicine (TCM) has long been indicated to be effective in the treatment of sciatica and is widely used in the management of this condition, the mechanism by which integrated TCM alleviates sciatica has not yet been fully defined, and the effect of integrated TCM on gene expression in the peripheral blood of patients with sciatica is still unknown. We performed this study to investigate the effect of integrated TCM on peripheral blood gene expression in patients with sciatica and to explore new clues for studying the mechanism of integrated TCM in alleviating sciatica.

Methods

We used a microarray to identify differentially expressed genes (DEGs) in the peripheral blood of patients with sciatica and healthy controls (DEGs-baseline), bioinformatic analysis to reveal the characteristics of DEGs-baseline, and the key genes that contribute to the gene dysregulation. A microarray was also used to identify DEGs in the peripheral blood of patients with sciatica after integrated TCM treatment compared with those at baseline, and the expression levels of DEGs were validated by qRT-PCR.

Results

We identified 153 DEGs-baseline, which included 131 upregulated genes and 22 downregulated genes. Bioinformatic analysis revealed that most of the DEGs-baseline were related to immunity and the inflammatory response and that TLR4, MMP9, MPO, CAMP, RETN, TLR5, and IL1RN were key genes involved in the dysregulation of genes in the peripheral blood of patients with sciatica. The expression levels of TLR5, IL1RN, SLC8A1, RBM20, GPER1, IL27, SOCS1, and GRTP1-AS1 were decreased in the peripheral blood of patients after integrated TCM treatment compared with that at baseline, which was accompanied by relief of pain.

Conclusion

Integrated TCM treatment relieved pain while regulating the gene expression of TLR5, IL1RN, SLC8A1, RBM20, GPER1, IL27, SOCS1, and GRTP1-AS1 in the peripheral blood of patients with sciatica. Our study provides new clues for studying the mechanism of TCM in treating sciatica.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02280-1.

Microarray analysis reveals an inflammatory transcriptomic signature in peripheral blood for sciatica

BACKGROUND

Although the pathology of sciatica has been studied extensively, the transcriptional changes in the peripheral blood caused by sciatica have not been characterized. This study aimed to characterize the peripheral blood transcriptomic signature for sciatica.

METHODS

We used a microarray to identify differentially expressed genes in the peripheral blood of patients with sciatica compared with that of healthy controls, performed a functional analysis to reveal the peripheral blood transcriptomic signature for sciatica, and conducted a network analysis to identify key genes that contribute to the observed transcriptional changes. The expression levels of these key genes were assessed by qRT-PCR.

RESULTS

We found that 153 genes were differentially expressed in the peripheral blood of patients with sciatica compared with that of healthy controls, and 131 and 22 of these were upregulated and downregulated, respectively. A functional analysis revealed that these differentially expressed genes (DEGs) were strongly enriched for the inflammatory response or immunity. The network analysis revealed that a group of genes, most of which are related to the inflammatory response, played a key role in the dysregulation of these DEGs. These key genes are Toll-like receptor 4, matrix metallopeptidase 9, myeloperoxidase, cathelicidin antimicrobial peptide, resistin and Toll-like receptor 5, and a qRT-PCR analysis validated the higher transcript levels of these key genes in the peripheral blood of patients with sciatica than in that of healthy controls.

CONCLUSION

We revealed inflammatory characteristics that serve as a peripheral blood transcriptomic signature for sciatica and identified genes that are essential for mRNA dysregulation in the peripheral blood of patients with sciatica.

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.

RAB40C gene polymorphisms rs62030917 and rs2269556 are associated with an increased risk of lumbar disc herniation development in the Chinese Han population

BACKGROUND

Lumbar disc herniation (LDH) places a serious burden on the daily lives and socioeconomics of people. Although the pathogenesis of LDH is complex, genetic factors such as single nucleotide polymorphisms (SNPs) may affect the risk of developing LDH. In the present study, we aimed to elucidate the effect of RAB40C SNPs on the risk of LDH in the Chinese Han population.

METHODS

We investigated 508 LDH cases and 508 healthy controls for this case-control study. Three tag SNPs in RAB40C were selected and genotyped using the Agena MassARRAY platform (Agena Bioscience, San Diego, CA, USA). After adjusting for age and gender, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using unconditional logistic regression.

RESULTS

In the allele model, we found rs62030917 and rs2269556 in RAB40C with a minor G allele significantly increased the risk of LDH (rs62030917: OR = 1.23, 95% CI = 1.00-1.50, p = 0.046; rs2269556: OR = 1.21, 95% CI = 1.02-1.45, p = 0.033). In genetic model analysis, rs2269556 was associated with an increased risk of LDH under both codominant (OR = 1.49, 95% CI = 1.03-2.15, p = 0.035) and log-additive models (OR = 1.21, 95% CI = 1.01-1.45, p = 0.035). rs62030917 of RAB40C was associated with an increased risk of LDH under codominant, recessive and log-additive models (p < 0.05) only among individuals younger than 49 years after stratification by age.

CONCLUSIONS

For the first time, our results suggest that rs62030917 and rs2269556 in the RAB40C gene influence genetic susceptibility to LDH.

Lycopene alleviates disc degeneration under oxidative stress through the Nrf2 signaling pathway

Intervertebral disc degeneration (IDD) is a main cause of diseases such as discogenic low back pain, cervical and lumbar disc herniation, degenerative spinal stenosis, and lumbar spondylolisthesis. Nuclear factor erythroid 2-related factor 2 (Nrf2), an important transcription factor, regulates antioxidant genes and induces cellular defense mechanisms against oxidative stress. In this study, the protective effect of plant antioxidant lycopene on nucleus pulposus cells (NPCs) under oxidative stress was investigated. The results indicated that Nrf2 expression decreased in degenerated NPCs. We further found that lycopene was protective in NP tissue under oxidative stress and alleviated oxidative stress-induced apoptosis of degenerative human NPCs via Nrf2. The results also showed that lycopene reduced H₂O₂-induced decomposition of cartilage extracellular matrix in NPCs. In conclusion, our findings suggested that lycopene may alleviate disc degeneration under oxidative stress through the Nrf2 signaling pathway.

Gene polymorphisms and expression levels of interleukin-6 and interleukin-10 in lumbar disc disease: a meta-analysis and immunohistochemical study

Background

To investigate the association between interleukin-6 (IL-6) (rs1800795, rs1800796, rs1800797, rs13306435, rs2069849) and interleukin-10 (IL-10) (rs1800871, rs1800896) gene polymorphisms, expression levels, and lumbar disc disease (LDD).

Methods

We conducted a literature research on PubMed, Embase, Web of Science, Cochrane Library, and China National Knowledge Infrastructure (CNKI) until February 28, 2019. We included all case-control studies about the association between IL-6 and IL-10 gene polymorphisms and LDD. The odds ratio (OR) and 95% confidence interval (CI) were calculated to estimate the strength of association. Statistical analysis was conducted by Review Manager (RevMan) 5.3 software. Furthermore, immunohistochemistry (IHC) and RT-PCR were performed to evaluate IL-6 and IL-10 expressions in the normal and degenerated disc.

Results

A total of 6 studies, involving 1456 cases and 1611 controls, were included in this meta-analysis. G alleles of rs1800795 and rs1800797 in the IL-6 gene were significantly associated with LDD (rs1800795: G vs. C, OR = 1.38, 95% CI = 1.16–1.64, P = 0.0002; rs1800797: G vs. A, OR = 1.35, 95% CI = 1.14–1.61, P = 0.0006). Begg’s funnel plot and Egger’s tests did not show any evidence of publication bias. IL-6 expression and IL-6 mRNA levels were significantly increased in the degenerated disc compared with those in the normal disc (IL-6 immunopositive cells, 73.68 ± 10.99% vs. 37.23 ± 6.42%, P < 0.001).

Conclusions

IL-6 gene polymorphisms (rs1800795 and rs1800797) were significantly associated with susceptibility to LDD. A high expression level of IL-6 may be an important risk factor for LDD.

Oxymatrine suppresses IL-1β-induced degradation of the nucleus pulposus cell and extracellular matrix through the TLR4/NF-κB signaling pathway

Intervertebral disc degeneration is the main cause of low back pain. However, its pathomechanism has not been fully clarified yet. Previous studies have indicated that inflammation may lead to apoptosis of nucleus pulposus cells and break the balance between anabolism and catabolism of the nucleus pulposus extracellular matrix. The purpose of this study is to explore the mitigative effect of oxymatrine on extracellular matrix degradation and apoptosis of nucleus pulposus cells after interleukin-1 beta-induced inflammation, and its possible signaling pathway. We examined the gene and protein levels of collagen II, aggrecan, and MMPs (MMP2/3/9/13) and interleukin 6 in nucleus pulposus cells. The results demonstrated that oxymatrine could reduce extracellular matrix degradation and apoptosis of nucleus pulposus cells; interleukin-1 beta prompted the expression of MMPs and interleukin 6 through TLR4/NF-κB axis, while oxymatrine reduced the expression of MMPs and TNF-α induced by interleukin-1 beta. Moreover, TAK 242, as a small molecule inhibitor of TLR4 signaling, was used to detect the effect of oxymatrine on the TLR4/NF-κB signaling. The final experimental results show that oxymatrine could reduce the inflammatory response of nucleus pulposus cells and degradation of nucleus pulposus tissue. Oxymatrine may be a potential medicine to reduce disc inflammation and relieve intervertebral disc degeneration by inhibiting the TLR4/NF-κB signal pathway.

Impact statement

Currently, drug therapy is a potential treatment for patients with intervertebral disc degeneration. In the present research, oxymatrine intervenes in intervertebral disc degeneration effectively via regulating inflammation in intervertebral disc degeneration rats. Our research highlights the therapeutic potential of oxymatrine in the treatment of intervertebral disc degeneration.

Long non-coding RNA HOTAIR modulates intervertebral disc degenerative changes via Wnt/β-catenin pathway

BACKGROUND

Intervertebral disc degeneration (IDD) has a complicated and enigmatic pathogenic process. Accumulating evidence shows that long non-coding RNAs (LncRNAs) play a role in the pathogenesis of IDD. This study aimed to investigate the expression and role of the LncRNA HOTAIR in IDD pathogenesis.

METHODS

Nucleus pulposus (NP) tissue samples from 10 patients with idiopathic scoliosis and 10 patients with lumbar disc herniation were collected. qRT-PCR was used to assess the expression of HOTAIR and ECM-related genes; western blotting was used to detect the expression of senescence biomarkers, apoptosis-related proteins, and Wnt/β-catenin pathway; flow cytometry was used to detect apoptosis; and the MTT assay was used to determine cell proliferation. Moreover, a classic needle-punctured rat tail model was used to investigate the role of HOTAIR in IDD in vivo.

RESULTS

The results showed that the expression of HOTAIR significantly increased during IDD progression. The overexpression of HOTAIR was found to induce nucleus pulposus (NP) cell senescence, apoptosis, and extracellular matrix (ECM) degradation. HOTAIR silencing by RNA interference in NP cells prevented interleukin-1β-induced NP cell senescence, apoptosis, and ECM degradation. Furthermore, we found that the Wnt/β-catenin pathway played a role in regulating HOTAIR to induce these changes in NP cells. Moreover, HOTAIR inhibition in a rat model effectively attenuated IDD symptoms in vivo.

CONCLUSIONS

Our findings confirmed that HOTAIR promoted NP cell senescence, apoptosis, and ECM degradation via the activation of the Wnt/β-catenin pathway, while silencing HOTAIR attenuated this degeneration process, indicating a potential therapeutic target against IDD.

MiR-202-3p regulates interleukin-1β-induced expression of matrix metalloproteinase 1 in human nucleus pulposus

MicroRNAs (miRNAs), small noncoding RNA molecules, have emerged as important factors during intervertebral disc degeneration. This study was to determine whether miR-202-3p regulates interleukin-1β (IL-1β)-induced expression of matrix metalloproteinase 1 (MMP-1) in human nucleus pulposus (NP) cells. Human NP cells were stimulated with IL-1β in vitro. MicroRNA arrays were used to determine the expression profile of 1971 human miRNAs and the miRNAs targets were identified using bioinformatics. In IL-1β-stimulated NP cells, 10 microRNAs were down-regulated, 2 microRNAs were up-regulated. There was a significant reduction in hsa-miR-202-3p (miR-202-3p) expression in the severe degenerative disc compared with mild degenerative disc. Down-regulation of miR-202-3p expression by IL-1β was correlated with up-regulation of MMP-1 expression in human NP cells. IL-1β-induced activation of MAP kinase (MAPK) and nuclear factor-κB (NF-κB) decreased miR-202-3p expression and induced MMP-1 expression. MiR-202-3p suppressed IL-1β-induced MMP-1 production. Conversely, treatment with anti-miR-202-3p remarkably increased MMP-1 production. In addition, mutation of the miR-202-3p binding site in the 3'-UTR of MMP-1 mRNA abolished miR-202-3p-mediated repression of reporter activity. Functional analysis showed that miR-202-3p could decrease type II collagen degradation, whereas overexpression of MMP-1 by Lentiviral-shMMP-1 abolished the effect of miR-202-3p on type II collagen degradation. These results suggest that miR-202-3p is an important regulator of MMP-1 in human nucleus pulposus and may contribute to the development of intervertebral disc degeneration.

Upregulation of miR-107 expression following hyperbaric oxygen treatment suppresses HMGB1/RAGE signaling in degenerated human nucleus pulposus cells

Background

The expression of both high-mobility group box 1 (HMGB1) and receptor for advanced glycation end-products (RAGE) is upregulated in degenerated discs. HMGB1 is known to function as a coupling factor between hypoxia and inflammation in arthritis, and this inflammatory response is modulated by microRNAs (miRNAs), with miR-107 expression downregulated during hypoxia. In this study, we investigated the regulation of the miR-107/HMGB1/RAGE pathway in degenerated nucleus pulposus cells (NPCs) after hyperbaric oxygen (HBO) treatment.

Methods

NPCs were separated from human degenerated intervertebral disc 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 cellular protein and mRNA levels of HMGB1, RAGE, and inducible nitric oxide synthase (iNOS) were assessed, and the phosphorylation of MAPK (p38MAPK, ERK, and JNK) was evaluated. Additionally, cytosolic and nuclear fractions of the IκBα and NF-κB p65 proteins were analyzed, and secreted HMGB1 and metalloprotease (MMP) levels in the conditioned media were quantified.

Results

Using microarray analyses, 96 miRNAs were identified as upregulated and 66 downregulated following HBO treatment. Based on these results, miR-107 was selected for further investigation. Bioinformatics analyses indicated that the 3′ untranslated region of the HMGB1 mRNA contained the “seed-matched-sequence” for hsa-miR-107, which was validated via dual-luciferase reporter assays. MiR-107 was markedly induced by HBO, and simultaneous suppression of HMGB1 was observed in NPCs. Knockdown of miR-107 resulted in upregulation of HMGB1 expression in HBO-treated cells, and HBO treatment downregulated the mRNA and protein levels of HMGB1, RAGE, and iNOS and the secretion of HMGB1. In addition, HBO treatment upregulated the protein levels of cytosolic IκBα and decreased the nuclear translocation of NF-κB in NPCs. Moreover, HBO treatment downregulated the phosphorylation of p38MAPK, ERK, and JNK and significantly decreased the secretion of MMP-3, MMP-9, and MMP-13.

Conclusions

HBO inhibits pathways related to HMGB1/RAGE signaling via upregulation of miR-107 expression in degenerated human NPCs.

Moderate Fluid Shear Stress Could Regulate the Cytoskeleton of Nucleus Pulposus and Surrounding Inflammatory Mediators by Activating the FAK-MEK5-ERK5-cFos-AP1 Signaling Pathway

We first applied moderate fluid shear stress to nucleus pulposus cells. The correlation of AP-1 with type II collagen, proteoglycan, Cytokeratin 8 protein, MAP-1, MAP-2, and MAP-4 and the correlation of AP-1 with IL-1β, TNF-α, IL-6, IL-8, MIP-1, MCP-1, and NO were detected. Our results document that moderate fluid shear stress could activate the FAK-MEK5-ERK5-cFos-AP1 signaling pathway. AP1 could downregulate the construct factors of cytoskeleton such as type II collagen, proteoglycan, Cytokeratin 8 protein, MAP-1, MAP-2, and MAP-4 in nucleus pulposus cell after the fluid shear stress was loaded. AP1 could upregulate the inflammatory factors such as IL-1β, TNF-α, IL-6, IL-8, MIP-1, MCP-1, and NO in nucleus pulposus cell after the fluid shear stress was loaded. Taken together, our data suggested that moderate fluid shear stress may play an important role in the cytoskeleton of nucleus pulposus and surrounding inflammatory mediators by activating the FAK-MEK5-ERK5-cFos-AP1 signaling pathway, thereby affecting cell degeneration.

Association between IL4, IL6 gene polymorphism and lumbar disc degeneration in Chinese population

Lumbar disc disease (LDD) is a common musculoskeletal disorder, caused by degeneration of intervertebral discs of the lumbar spine and is one of the most common musculoskeletal disorders affliction in adult. There is growing evidence that LDD has strong genetic determinants. We analyze whether the IL4 and IL6 gene polymorphism is related to LDD in Chinese Han population. The participants were 498 with LDD and 463 without LDD. IL4 and IL6 gene polymorphism were determined by Sequenom MassARRAY. We found that SNPs rs1800796(OR = 1.29, 95% CI, 1.07 – 1.57, p = 0.009), rs1524107(OR = 1.28, 95% CI, 1.05 – 1.55, p = 0.013), rs2069840 (OR = 1.39, 95% CI, 1.03 – 1.89, p = 0.033) in IL6 gene were significantly associated with LDD risk at a 5% level. In addition, genetic models found IL4 gene (rs2243250) were associated with LDD. In this study, we analyzed and associated SNPs of IL4 and IL6 with LDD risk. In summary, four variations (rs1800796, rs1524107, rs2069840, rs2243250) of the selected candidate SNPs were associated with susceptibility to LDD in our study. The results of this study have the guiding significance in clinical work in the future in the treatment of lumbar disc herniation patients, not one-sided that the symptoms of low back pain only from mechanical oppression.