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Abstract Background Limited supply of certain nutrients and deregulation of nucleus pulposus (NP) plays a key role in the pathogenesis of intervertebral disc degeneration (IVDD). However, whether nutrient deprivation-induced cell death, particularly disulfidptosis, contributes to the depletion of NP cells and the development of IVDD, is unknown. Methods RNA-seq, single-cell RNA-seq, and Genome-wide DNA methylation datasets of nucleus pulposus tissue were collected for bioinformatic analysis. Predictive models of disulfidptosis related genes in IVDD were constructed by machine learning and their differential expression was analyzed. In addition, we performed cell subsets identification analysis, cell-cell communications analysis, and functional enrichment analysis of key genes in the core subset based on single-cell RNA-seq data of NP tissues isolated from one normal sample and one IVDD sample. Finally, glucose deprivation-induced disulfidptosis in human NP cells (HNPCs) was verified by various cell death inhibitors and disulfidptosis-related molecular markers. Results We found the disulfidptosis signal was significantly activated in the IVDD group. Using single-cell RNA-seq analysis, we focused on the chondrocytes and found that disulfidptosis-related genes significantly highly expressed in the IVDD C4 chondrocyte subset, which was identified as a new disulfidptosis-associated cell subset. Correlation analysis revealed the negative correlation between SLC7A11 (driving gene of disulfidptosis) and the glucose transporter GLUTs (SLC2A1-4) family genes (suppressing genes of disulfidptosis) in the IVDD group. We also found obvious cell death in HNPC upon glucose starvation, while employment of various cell death inhibitors could not inhibit glucose starvation-induced death in HNPCs. Moreover, the accumulation of disulfide bonds in cytoskeletal proteins was indicated by slowed migration in non-reducible protein blotting experiments. 2-DG, a key disulfidptosis inhibitor, significantly rescued cell death caused by glucose starvation through lowering the NADP+/NADPH ratio. Conclusions We validated the occurrence of disulfidptosis in HPNCs and identified a novel disulfidptosis-associated cell subset, followed by experimental verification of disulfidptosis in a glucose-limited context to mimic a fall in nutrient supply during the development disc degeneration. These findings provided new insights into the pathological mechanisms of IVDD and encourage us to explore potential therapeutic targets involved in the regulation of disulfidptosis for the prevention of intervertebral disc degeneration. Graphical Abstract

Background: Limited supply of certain nutrients and deregulation of nucleus pulposus (NP) plays a key role in the pathogenesis of intervertebral disc degeneration (IVDD). However, whether nutrient deprivation-induced cell death, particularly disulfidptosis, contributes to the depletion of NP cells and the development of IVDD, is unknown. Methods: RNA-seq, single-cell RNA-seq, and Genome-wide DNA methylation datasets of nucleus pulposus tissue were collected for bioinformatic analysis. Predictive models of disulfidptosis related genes in IVDD were constructed by machine learning and their differential expression was analyzed. In addition, we performed cell subsets identification analysis, cell-cell communications analysis, and functional enrichment analysis of key genes in the core subset based on single-cell RNA-seq data of NP tissues isolated from one normal sample and one IVDD sample. Finally, glucose deprivation-induced disulfidptosis in human NP cells (HNPCs) was verified by various cell death inhibitors and disulfidptosis-related molecular markers. Results: We found the disulfidptosis signal was significantly activated in the IVDD group. Using single-cell RNA-seq analysis, we focused on the chondrocytes and found that disulfidptosis-related genes significantly highly expressed in the IVDD C4 chondrocyte subset, which was identified as a new disulfidptosis-associated cell subset. Correlation analysis revealed the negative correlation between SLC7A11 (driving gene of disulfidptosis) and the glucose transporter GLUTs (SLC2A1-4) family genes (suppressing genes of disulfidptosis) in the IVDD group. We also found obvious cell death in HNPC upon glucose starvation, while employment of various cell death inhibitors could not inhibit glucose starvation-induced death in HNPCs. Moreover, the accumulation of disulfide bonds in cytoskeletal proteins was indicated by slowed migration in non-reducible protein blotting experiments. 2-DG, a key disulfidptosis inhibitor, significantly rescued cell death caused by glucose starvation through lowering the NADP+/NADPH ratio. Conclusions: We validated the occurrence of disulfidptosis in HPNCs and identified a novel disulfidptosis-associated cell subset, followed by experimental verification of disulfidptosis in a glucose-limited context to mimic a fall in nutrient supply during the development disc degeneration. These findings provided new insights into the pathological mechanisms of IVDD and encourage us to explore potential therapeutic targets involved in the regulation of disulfidptosis for the prevention of intervertebral disc degeneration. [ABSTRACT FROM AUTHOR]

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To explore the effect of baicalin on human nucleus pulposus cells (NPCs) in response to interleukin (IL)-1β stimulation. Viability of NPCs was measured by cell counting kit-8 (CCK-8) assay. TUNEL staining assay and flow cytometry were performed to detect apoptotic cell death of NPCs. Western blot analysis was conducted to detect the expression levels of proteins. Enzyme-linked immunosorbent assay (ELISA) was applied for the determination of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor alpha (TNF-α), and IL-6. Oxidative stress indicators including reactive oxygen species (ROS) production, malondialdehyde (MDA) level, and superoxide dismutase (SOD) activity were measured. Baicalin attenuated IL-1β-caused cell viability reduction and apoptosis in NPCs. IL-1β-induced increase in Bax expression and decrease in Bcl-2 expression were attenuated by baicalin treatment. IL-1β-induced production of iNOS, COX-2, IL-6, and TNF-α in NPCs was inhibited by baicalin treatment. Baicalin treatment reversed IL-1β-induced increase in ROS production and MDA level, as well as decrease in SOD activity. Furthermore, baicalin treatment elevated the expression levels of Col II and Aggrecan and downregulated the expression levels of MMP3, MMP13, and ADAMTS5 in IL-1β-induced NPCs. A total of 402 related targets of baicalin and 134 related targets of intervertebral disk degeneration were found, and nine intersection targets were screened out. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that mitogen-activated protein kinase (MAPK) pathway was found to be involved in the effects of baicalin. Baicalin exhibited protective effects on IL-1β-caused cell viability reduction, apoptosis, oxidative stress, inflammation, and extracellular matrix degradation in NPCs. In addition, we found c-Jun N-terminal kinase (JNK) and p38 MAPK pathways as targets of baicalin through bioinformatic analysis. [ABSTRACT FROM AUTHOR]

Intervertebral disc degeneration (IDD) is a complex degradative disorder associated with inflammation. Emodin, an anthraquinone derivative, possesses strong anti-inflammatory activity. This study focused on the in vitro therapeutic action of emodin in a cellular model of IDD. Human nucleus pulposus cells (NPCs) were stimulated with interleukin‐1 β (IL-1 β) to induce inflammation. Cell Counting Kit-8 and terminal deoxynucleotidyl transferase dUTP nick end labeling staining assays were performed to evaluate the viability and apoptosis of NPCs, respectively. Caspase-3 activity was measured to indirectly assess cell apoptosis. Western blot analysis was performed to detect protein expression levels. Reverse transcription‐polymerase chain reaction was performed for the detection of relative mRNA levels of tumor necrosis factor- α (TNF- α) and IL-6. Enzyme-linked immunosorbent assay was performed to analyze TNF- α and IL-6 secretion. Our results showed that emodin treatment mitigated IL-1β-induced reduction of cell viability in NPCs. Moreover, the increase in reactive oxygen species (ROS) production, apoptotic rate, and caspase-3 activity in IL-1 β -stimulated NPCs was reduced by emodin treatment. Treatment with emodin also abolished IL-1 β -induced inflammation in NPCs, as indicated by reduced secretion of IL-6 and TNF- α. Besides, the increase in expression levels of phosphorylated p65 and nuclear p65 in IL-1 β -stimulated NPCs was suppressed by emodin treatment. Furthermore, inhibition of nuclear factor kappa B (NF- κ B) activation with pyrrolidine dithiocarbamate aggravated the protective effects of emodin. These results suggested that emodin protected NPCs against IL-1 β -induced apoptosis and inflammation via inhibiting ROS-mediated activation of NF- κ B. [ABSTRACT FROM AUTHOR]

According to the linear model of microarray data analysis, triggering receptor expressed on myeloid cells 1 (TREM1) has been shown to have a significantly different expression profile between intervertebral disc degeneration (IDD) samples and associated control samples. The purpose of the present study was to explore the probable role and underlying mechanism of TREM1 in IDD. To accomplish this, an in vitro model of IDD was established by using IL-1ß to stimulate human nucleus pulposus cells (NPCs). After the level of TREM1 had been determined, its functions in terms of the viability of the NPCs, extracellular matrix (ECM) degradation, inflammation, apoptosis and endoplasmic reticulum stress (ERS) were assessed. The downstream target of TREM1 was predicted to be Toll-like receptor-4 (TLR-4) and its roles were then studied, incorporating experiments featuring an ERS agonist. IL-1ß was found to elevate the level of TREM1 in NPCs. TREM1 knockdown reversed the observed effects of IL-1ß on cell viability, ECM degradation, inflammation, apoptosis of NPCs, ERS and TLR4/NF-B signaling. Subsequently, the TLR4 and ERS agonists were found to reverse the effect of TREM1 knockdown on NPCs, indicating that the TLR4/NF-B signaling pathway and ERS were responsible for mediating the regulation of TREM1. In conclusion, the present study showed that TREM1 knockdown blocked the TLR4/NF-B signaling pathway, inhibited ERS and reduced the levels of ECM degradation and apoptosis of NPCs induced by IL-1ß. [ABSTRACT FROM AUTHOR]

Cervical spondylosis is a degenerative disease commonly found in older adults and characterized by progressive osteophyte formation and disc collapse. Apoptosis in nucleus pulposus (NP) cells which induced by TNF-α has been widely known to associate with the disc degeneration. However, the exactly underlying molecular mechanism was still unclear. The aim of our study was to investigate whether TRIM14/NF-κB signalling pathway is associated with the apoptosis of human NP cells (HNPC) induced by TNF-α. Our data demonstrated that TNF-α treatment obviously decreased the cell viability, induced apoptosis and increased TRIM14 expression and NF-κBp65 activity in HNPC in a dose-dependent manner. Down-regulation of TRIM14 or NF-κB inhibitor PDTC treatment significantly inhibited cell apoptosis, Bax/Bcl-2 ratio and NF-κBp65 activation induced by TNF-α in HNPC. Meanwhile, up-regulation of TRIM14 obviously increased cell apoptosis, Bax/Bcl-2 ratio and NF-κBp65 activation in HNPC. Then, we found that the protein PPM1A was identified as a binding partner of TRIM14 and ubiquitinated by TRIM14. These findings provide insights into the function of TRIM14 and NF-κB signalling and might, therefore, represent a novel therapeutic target for treatment of cervical spondylosis.

Background/Aims: Nucleus pulposus cell (NPC) apoptosis is the main factor in intervertebral disc degeneration (IDD); thus, inhibiting the excessive apoptosis of nucleus pulposus cells may be a potential way to alleviate IDD. The effect of Hemeoxygenase-1 (HO-1) on human NPC apoptosis has never been reported. Our study aimed to investigate the effect and mechanism of HO-1 on apoptosis in human degenerative NPCs. Methods: Nucleus pulposus tissues were collected from patients with lumbar vertebral fracture (LVF) and IDD. The expression of HO-1 and P65 in intervertebral discs was determined using immunohistochemistry and western blot analysis. Apoptosis of human nucleus pulposus cells was quantified by flow cytometric analysis. A recombinant lentiviral vector overexpressing HO-1 and HO-1-siRNA was used to promote or silence the expression of HO-1 in nucleus pulposus cells. The NF-κB inhibitor PDTC was used to inhibit the NF-κB pathway. Results: Our study demonstrated that compared with normal samples, IDD samples showed down-regulation of HO-1 expression and up-regulation of P65 expression. Overexpression of HO-1 inhibited the increase in nucleus pulposus cell apoptosis after IL-1β treatment and simultaneously inhibited the expression of p-P65. Furthermore, after treatment with PDTC, the number of apoptotic cells was significantly decreased with or without overexpression of HO-1. Conclusion: HO-1 might play a significant role in IDD, and HO-1 protected degenerative human NPCs against apoptosis induced by IL-1β through the NF-κB pathway. These findings would aid in the development of novel therapeutic approaches for IDD treatment.

Background/Aims: Nucleus pulposus cell (NPC) apoptosis is the main factor in intervertebral disc degeneration (IDD); thus, inhibiting the excessive apoptosis of nucleus pulposus cells may be a potential way to alleviate IDD. The effect of Hemeoxygenase-1 (HO-1) on human NPC apoptosis has never been reported. Our study aimed to investigate the effect and mechanism of HO-1 on apoptosis in human degenerative NPCs. Methods: Nucleus pulposus tissues were collected from patients with lumbar vertebral fracture (LVF) and IDD. The expression of HO-1 and P65 in intervertebral discs was determined using immunohistochemistry and western blot analysis. Apoptosis of human nucleus pulposus cells was quantified by flow cytometric analysis. A recombinant lentiviral vector overexpressing HO-1 and HO-1-siRNA was used to promote or silence the expression of HO-1 in nucleus pulposus cells. The NF-κB inhibitor PDTC was used to inhibit the NF-κB pathway. Results: Our study demonstrated that compared with normal samples, IDD samples showed down-regulation of HO-1 expression and up-regulation of P65 expression. Overexpression of HO-1 inhibited the increase in nucleus pulposus cell apoptosis after IL-1β treatment and simultaneously inhibited the expression of p-P65. Furthermore, after treatment with PDTC, the number of apoptotic cells was significantly decreased with or without overexpression of HO-1. Conclusion: HO-1 might play a significant role in IDD, and HO-1 protected degenerative human NPCs against apoptosis induced by IL-1β through the NF-κB pathway. These findings would aid in the development of novel therapeutic approaches for IDD treatment. [ABSTRACT FROM AUTHOR]

Intervertebral disc degeneration is widely recognized as a cause of lower back pain, neurological dysfunction and other musculoskeletal disorders. The major inflammatory cytokine IL-1β is associated with intervertebral disc degeneration; however, the molecular mechanisms that drive IL-1β production in the intervertebral disc, especially in nucleus pulposus (NP) cells, are unknown. In some tissues, advanced glycation end products (AGEs), which accumulate in NP tissues and promote its degeneration, increase oxidative stress and IL-1β secretion, resulting in disorders, such as obesity, diabetes mellitus and ageing. It remains unclear whether AGEs exhibit similar effects in NP cells. In this study, we observed significant activation of the NLRP3 inflammasome in NP tissues obtained from patients with degenerative disc disease compared to that with idiopathic scoliosis according to results detected by Western blot and immunofluorescence. Using NP cells established from healthy tissues, our in vitro study revealed that AGEs induced an inflammatory response in NP cells and a degenerative phenotype in a NLRP3-inflammasome-dependent manner related to the receptor for AGEs (RAGE)/NF-κB pathway and mitochondrial damage induced by mitochondrial reactive oxygen species (mtROS) generation, mitochondrial permeability transition pore (mPTP) activation and calcium mobilization. Among these signals, both RAGE and mitochondrial damage primed NLRP3 and pro-IL-1β activation as upstream signals of NF-κB activity, whereas mitochondrial damage was critical for the assembly of inflammasome components. These results revealed that accumulation of AGEs in NP tissue may initiate inflammation-related degeneration of the intervertebral disc via activation of the NLRP3 inflammasome. [ABSTRACT FROM AUTHOR]

Background: Intervertebral disc degeneration (IVD) is a pain-inflicting disorder, posing a serious threat to the elderly, and new therapies are urgently needed. In this study, we examined the potential therapeutic effect of mesenchymal stem cells (MSCs) transplantation on IVD., Methods: Both human adipose-derived stem cells (hADSCs) and human bone marrow mesenchymal stem cells (hBMSCs) provided by a volunteer were non-contact co-cultured with the human nucleus pulposus cells (hNPCs) to determine the efficacy of hNPCs-oriented differentiation. Flow cytometry was used to characterize the purity of hADSCs/hBMSCs. We determined the expression of surface antigen molecules, such as CD73, CD105, CD90, CD31, HLA-DR, CD34 and CD45, using flow cytometry. Osteogenic and lipogenic differentiations demonstrated by the cells were identified with Alizarin red and Oil red O staining, respectively, and changes in type II collagen and proteoglycan levels were detected by immunofluorescence. Myeloid cell-related mRNA and protein expression levels were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot, respectively. The therapeutic effect of hADSCs and hBMSCs on IVD was evaluated in experimental rats, in which degeneration was induced by needling the annulus fibrosus of the caudal intervertebral disc., Results: As evidenced by the presence of hNPCs-like morphology, both hBMSCs and hADSC could effectively differentiate into hNPCs. Using flow cytometry assays, we found high expression of type II collagen (COL2) and aggrecan (ACAN) protein in the hNPCs-like tissue. Treatment with hADSCs and hBMSCs attenuated IVD progression in the rats, and most importantly, there was no significant difference between the therapeutic effects of both types of cells on IVD, on the basis of the COL2 and SRY-Box Transcription Factor 9 (SOX9) protein expression and the histological results. Findings from the animal studies also suggested that both hADSCs and hBMSCs transplantation could be applied in IVD treatment., Conclusions: In summary, both hADSCs and hBMSCs can attenuate the progression of IVD by delaying, rather than completely reversing the deterioration of disc degeneration, and there is no significant difference between hADSCs and hBMSCs on the therapeutic effects.

This study aims to explore the effect of microRNA-21 (miR-21) on the proliferation of human degenerated nucleus pulposus (NP) by targeting programmed cell death 4 (PDCD4) tumor suppressor. NP tissues were collected from 20 intervertebral disc degeneration (IDD) patients, and from 5 patients with traumatic spine fracture. MiR-21 expressions were tested. NP cells from IDD patients were collected and divided into blank control group, negative control group (transfected with miR-21 negative sequences), miR-21 inhibitor group (transfected with miR-21 inhibitors), miR-21 mimics group (transfected with miR-21 mimics) and PDCD4 siRNA group (transfected with PDCD4 siRNAs). Cell growth was estimated by Cell Counting Kit-8; PDCD4, MMP-2,MMP-9 mRNA expressions were evaluated by qRT-PCR; PDCD4, c-Jun and p-c-Jun expressions were tested using western blot. In IDD patients, the expressions of miR-21 and PDCD4 mRNA were respectively elevated and decreased (both P

The present study aimed to investigate the role of microRNA (miR)-210 in the development of intervertebral disc degeneration (IDD). Human nucleus pulposus (NP) samples were collected from patients with scoliosis and IDD (n=12 each) as the scoliosis control and IDD groups, respectively. The expression levels of miR-210 were detected using reverse-transcription quantitative polymerase chain reaction. In vitro overexpression and knockdown of miR-210 in human NP cells were achieved by transfection of NP cells with lentiviral pre-miR-210 and antagomiR-210, respectively. The protein expression levels of homeobox A9 (HOXA9) were then detected in NP cells with modulated miR-210 using western blot analysis. Flow cytometry with allophycocyanin-Annexin V/7 and 7-aminoactinomycin D staining was also used to detect the proportion of NP cells with modulated miR-210 undergoing apoptosis. The current study revealed that the miR-210 expression was decreased in patients with IDD compared with that of the scoliosis control group (P<0.05). Furthermore, the upregulation of miR-210 with pre-miR-210 led to the repression of HOXA9. The HOXA9 level was significantly lower in these cells compared with that of NP cells treated with a corresponding negative sequence (P<0.05). Knockdown of miR-210 with antagomiR-210 resulted in upregulation of HOXA9 in NP cells, determined as the level of HOXA9 was significantly higher than that of NP cells treated with a negative sequence (P<0.05). The proportion of apoptotic NP cells also significantly decreased following treatment with pre-miR-210 compared with the scoliosis control group (12.1±1.43 vs. 23.8±1.22%, respectively; P<0.05). In conclusion, downregulation of miR-210 may promote Fas-mediated apoptosis in human IDD by regulating the expression of HOXA9. This indicates that miR-210 may be closely associated with the development of IDD and may act as a novel target in IDD treatment. [ABSTRACT FROM AUTHOR]

Objectives: To preliminarily explore miR-503 in human degenerative disc nucleus pulposus cell effects as well as mechanisms., Methods: We utilized bioinformatics analysis to determine the miRNA differential expression as well as key signal pathways existing in human nucleus pulposus cells of the degenerative intervertebral discs. Human degenerative disc nucleus pulposus cell model was cultured and established in vitro . miR-503 and TNIK-related genes are knocked down and overexpressed by lentiviral infection, then we added Wnt signaling pathway agonists; CCK-8, ELISA, RT-PCR, Western blot were used to detect proliferation, apoptosis, and activity of cells., Results: Bioinformatics results demonstrated that miR-503 was significantly down-regulated in human nucleus pulposus cells of the degenerated intervertebral discs. The targeted differentially expressed genes were mainly enriched in Wnt signaling pathway. However, after screening differential genes in the Wnt pathway, it was demonstrated that miR-503 mainly regulates TNIK to achieve Wnt pathway regulation. Cell experiments in vitro showed that cell activity and function were decreased while apoptosis was increased in the degenerative cell model., Conclusions: miR-503 can improve the function and activity of human nucleus pulposus cells of degenerated intervertebral disc by inhibiting Wnt expression. miR-503 mainly regulates the Wnt pathway through targeted binding with TNIK., Competing Interests: The authors have no conflict of interest.

• Omentin-1 is downregulated by interleukin-1 in human nucleus pulposus cells. • Omentin-1 exerts a proliferative effect on nucleus pulposus cells. • Omentin-1 lessens nucleus pulposus cell degeneration via PI3K/Akt signaling pathway. • Omentin-1 reveals potential in treating intervertebral disc degeneration. Intervertebral disc degeneration is an abnormal, cell-mediated process of tissue remodeling, recognized as the principal cause of low back pain affecting 80% of the population worldwide. Inflammatory cytokine, Interleukin-1beta (IL-1β) is involved in the intervertebral disc degeneration (IDD) process, and it is upregulated in degenerated discs. Omentin-1, also known as intelectin-1, is an adipokine with anti-inflammatory, anti-apoptosis, pro-proliferation, and proangiogenic properties in various types of cells. However, little is known about the effects of omentin-1 on human nucleus pulposus cells (HNPCs). This study aims to investigate the effects of omentin-1 on healthy HNPCs regarding proliferation and further investigate the effects of omentin-1 on IL-1β-induced inflammation, apoptosis, and degeneration in HNPCs. Genes and proteins of interest were measured by qRT-PCR, immunoblotting, and immunofluorescence to conduct related experiments. Cell viability (CCK-8), EdU, and mitochondrial membrane potential (JC-1), flow cytometry assays were used to assess proliferation and apoptosis, respectively. Our study showed that omentin-1 promoted proliferation in normal HNPCs. Furthermore, omentin-1 expression was decreased in IL-1β-treated HNPCs. Omentin-1 protected against IL-1β-induced inflammation, apoptosis, and degeneration in HNPCs in vitro via the activation of the PI3K/Akt signaling pathway. These findings may contribute to understanding the role of omentin-1 in HNPCs and may be a potential therapeutic candidate for intervertebral disc degeneration. [ABSTRACT FROM AUTHOR]

Cellular niches play fundamental roles in regulating cellular behaviors. However, the effect of niches on direct converted cells remains unexplored. In the present study, the specific combination of transcription factors is first identified to directly acquire induced nucleus pulposus-like cells (iNPLCs). Next, tunable physical properties of collagen niches are fabricated based on various crosslinking degrees. Collagen niches significantly affect actomyosin cytoskeleton and then influence the maturation of iNPLCs. Using gain- and loss of function approaches, the appropriate physical states of collagen niches are found to significantly enhance the maturation of iNPLCs through actomyosin contractility. Moreover, in a rat model of degenerative disc diseases, iNPLCs with collagen niches are transplanted into the lesion to achieve significant improvements. As a result, overexpression of transcription factors in human dermal fibroblasts are efficiently converted into iNPLCs and the optimal collagen niches affect cellular cytoskeleton and then facilitate iNPLCs maturation toward human nucleus pulposus cells. These findings encourage more in-depth studies toward the interactions of niches and direct conversion, which would contribute to the development of direct conversion., (© 2022 Wiley-VCH GmbH.)

ABSTRACT Human degenerative disc disease (DDD) is characterized by progressive loss of human nucleus pulposus (HNP) cells and extracellular matrix, in which the massive deposition are secreted by HNP cells. Cell therapy to supplement HNP cells to degenerated discs has been thought to be a promising strategy to treat DDD. However, obtaining a large quality of fully functional HNP cells has been severely hampered by limited proliferation capacity of HNP cells in vitro. Previous studies have used lipofectamine or recombinant adeno-associated viral (rAAV) vectors to deliver human telomerase reverse transcriptase (hTERT) into ovine or HNP cells to prolong the activity of nucleus pulposus cells with limited success. Here we developed a lentiviral vector bearing both hTERT and a gene encoding green fluorescence protein (L-hTERT/EGFP). This vector efficiently mediated both hTERT and EGFP into freshly isolated HNP cells. The expressions of both transgenes in L-hTERT/EGFP transduced HNP cells were detected up to day 210 post viral infection, which was twice as long as rAAV vector did. Furthermore, we observed restored telomerase activity, maintained telomere length, delayed cell senescence, and increased cell proliferation rate in those L-hTERT/EGFP transduced HNP cells. Our study suggests that lentiviral vector might be a useful gene delivery vehicle for HNP cell therapy to treat DDD. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:159-166, 2014. [ABSTRACT FROM AUTHOR]

Background: Arctigenin (ATG) is the active ingredient of the Chinese herbal medicine Arctium lappa, with anti-inflammatory and antioxidant effects. Excessive inflammation and cell apoptosis are important causes of intervertebral disc degeneration (IDD). Hence, this study probed into the possible role of ATG in IDD., Methods: Interleukin (IL)-1β (10 ng/ml) was adopted to induce human nucleus pulposus cells (HNPCs) as a cell model for IDD. The effects of different concentrations of ATG (0, 2, 5, 10, 20, 50 μmol/L) on the viability of HNPCs and effects of ATG (10, 50 μmol/L) on the viability of IL-1β-induced HNPCs were detected by cell counting kit-8 (CCK-8). After IL-1β-induced HNPCs were transfected with miR-483-3p inhibitor and/or treated with ATG, cell viability and apoptosis were determined by CCK-8 and flow cytometry; the expressions of miR-483-3p, extracellular matrix (ECM)-related genes, and inflammation-related genes were measured by quantitative real time polymerase chain reaction (qRT-PCR), and expressions of ECM/apoptosis/NF-κB pathway-related proteins were quantified by Western blot., Results: ATG had no significant effect on the viability of HNPCs but could promote the viability of IL-1β-induced HNPCs. ATG inhibited apoptosis, ECM degradation, inflammation, and activation of NF-κB pathway in HNPCs induced by IL-1β, but promoted the expression of miR-483-3p. MiR-483-3p inhibitor reversed the above-mentioned regulatory effects of ATG., Conclusion: Arctigenin suppresses apoptosis, ECM degradation, inflammation, and NF-κB pathway activation in HNPCs by up-regulating miR-483-3p., (© 2022 The Authors. Journal of Clinical Laboratory Analysis published by Wiley Periodicals LLC.)

Intervertebral disc degeneration (IDD) is a common disease with a high morbidity rate, which results in a significant deterioration in the quality of life of patients. MicroRNAs (miRNAs/miRs) are a class of endogenous small non-coding RNAs that influence target genes and serve critical roles in numerous biological processes. However, the role of miR-489-3p in lumbar disc degeneration is yet to be elucidated. In the present study, human NP cells were treated with 10 ng/ml lipopolysaccharide (LPS) for 24 h to investigate the role of miR-489-3p in IDD in an in vitro model. Reverse transcription-quantitative (RT-q)PCR was performed to determine the expression levels of miR-489-3p. Then, the TargetScan database was used to predict the potential binding sites between miR-489-3p and Toll-like receptor (TLR)4, and a dual-luciferase reporter assay was performed to verify the findings. Subsequently, RT-qPCR and western blotting were used to analyze the expression levels of TLR4. In addition, human nucleus pulposus (NP) cells were transfected with a miR-489-3p mimic and TLR4 overexpression plasmid to study the effects of miR-489-3p on LPS-induced human NP cells. Cell apoptosis and cell viability were also determined using flow cytometry and MTT assays, respectively. Finally, ELISAs were performed to analyze the levels of inflammatory factors. The expression levels of miR-489-3p were discovered to be downregulated in LPS-treated human NP cells. In addition, TLR4 was revealed to be a direct target gene of miR-489-3p, and its expression levels were upregulated in LPS-treated human NP cells. miR-489-3p was found to inhibit the LPS-induced decreases in cell viability and increases in apoptosis, and the concentration of inflammatory cytokines. Furthermore, miR-489-3p suppressed the LPS-induced decreases in extracellular matrix deposition via decreasing the expression levels of aggrecan and collagen type II in human NP cells. Finally, the results revealed that miR-489-3p inhibited the LPS-induced activation of the NF-κB signaling pathway in human NP cells. Conversely, all of the effects of miR-489-3p on LPS-induced human NP cells were reversed by the TLR4 overexpression plasmid. These findings suggested that miR-489-3p may represent a novel therapeutic target for the treatment of IDD. [ABSTRACT FROM AUTHOR]

• Sodium butyrate alleviates oxidative stress in human nucleus pulposus cells. • Sodium butyrate restores Klotho suppression under oxidative stress. • HDAC3 inhibition promotes acetylation and transactivation of PPARγ. We investigated the involvement of klotho in the inhibition of oxidative stress by sodium butyrate (NaB) in human nucleus pulposus cells (NPCs). NPCs were pretreated with different concentrations of NaB for 2 h before stimulation with tert -butyl hydroperoxide (TBHP). NaB alleviated TBHP-induced oxidative injury in the NPCs, as evident by the reduced accumulation of mitochondrial superoxide, intracellular reactive oxygen species, and malondialdehyde, and increased activities of superoxide dismutase and glutathione peroxidase. Flow cytometry and western blotting showed that TBHP-induced apoptosis of NPCs was inhibited by NaB. NaB also reduced the TBHP-induced release of proteases that degrade the extracellular matrix, including matrix metalloproteinases 3 and 13, and ADAMTS-4 (a disintegrin and metalloproteinase with thrombospondin motifs 4). Intriguingly, NaB significantly reversed TBHP-induced klotho suppression. However, the protective effects of NaB on NPCs were abolished by klotho-specific small interfering RNA (siRNA). TBHP stimulation had no obvious effects on total or nuclear expression of peroxisome proliferator-activated receptor γ (PPARγ), but significantly reduced PPARγ acetylation and transcriptional activity, which were restored by NaB. TBHP stimulation also promoted the nuclear translocation of histone deacetylase 3 (HDAC3) and enhanced the association between HDAC3 and PPARγ in the nucleus, but this interaction was substantially disrupted by NaB. siRNA-induced HDAC3 knockdown significantly increased PPARγ acetylation and transactivation, reversing the TBHP-induced suppression of klotho. Therefore, NaB alleviates TBHP-induced oxidative stress in human NPCs by elevating PPARγ-regulated klotho expression. HDAC3 may be a critical HDAC subtype that mediates the regulation of PPARγ activity by NaB under oxidative stress. [ABSTRACT FROM AUTHOR]

Autophagy is involved in degenerative diseases such as osteoarthritis and disc degeneration. Although, tumor necrosis factor α-induced protein 3 (TNFAIP3) is well-known as a key regulator of inflammation and autophagy, it is still not clear whether TNFAIP3 regulates autophagy to protect from human disc cells degeneration. We hypothesize that TNFAIP3 may also regulate autophagy to inhibit pro-inflammatory cytokines expression in human nucleus pulposus cells (NPCs). In this study, TNFAIP3 expression was increased in degenerative disc tissue as well as LPS-stimulated human NPCs, and the effect of TNFAIP3 in LPS-induced NPCs was further explored. The results demonstrated that pro-inflammatory cytokines expression in TNFAIP3-His cells was decreased, while it was increased in TNFAIP3-siRNA cells. Further molecular mechanism research showed that TNFAIP3-siRNA cells enhanced the phosphorylation of mammalian target of rapamycin (mTOR) and inhibited autophagy. Meanwhile, after treatment of TNFAIP3-siRNA cells with the mTOR inhibitor Torin1, the level of autophagy increased and the decrease of extracellular matrix was reversed. In summary, overexpressed TNFAIP3 can promote autophagy and reduce inflammation in LPS-induced human NPCs. Moreover, autophagy triggered by TNFAIP3 can ameliorate the degeneration of inflammatory human NPCs, providing a potential and an attractive therapeutic strategy for degenerative disease.

Intervertebral disc degeneration (IDD) is a form of chronic inflammation and is one of the most common disorders reported to be involved in low back pain (LBP). The pathophysiology of degeneration is not completely understood, but the consensus is that the degradation of extracellular matrix (ECM) proteins in the disc is the leading factor contributing to IDD. High temperature requirement A1 (HtrA1) is serine protease that has been shown to be increased in degenerated intervertebral discs as a result of an increase in the expression of matrix metalloproteinases (MMPs), but no study has focused on the effect of HtrA1 on a disintegrin-like and metalloproteinase with thrombospondin motifs (ADAMTSs). In the present study, we successfully isolated human nucleus pulposus cells (HNPCs) from IDD patients who were our research subjects to elaborate on the potential role of HtrA1 in the pathogenesis of IDD. We confirmed that HtrA1 has the potential to induce the expression of ADAMTS-5 in a dose-dependent manner. Consistently, this was mediated by the ERK, NF-κB and JNK pathways. By using inhibitors of these pathways, the increase in ADAMTS-5 could be reduced. Our findings indicated that HtrA1 can induce the expression of ADAMTS-5 in HNPCs via the ERK/NF-κB/JNK signaling pathway, and our study also elucidated the involved induction mechanisms in HNPCs, which may provide new insights for the treatment of IDD., Competing Interests: None.