IL-17A enhances ADAMTS-7 expression through regulation of TNF-α in human nucleus pulposus cells

Nucleus pulposus cell network modelling in the intervertebral disc

Intervertebral disc degeneration (IDD) results from an imbalance between anabolic and catabolic processes in the extracellular matrix (ECM). Due to complex biochemical interactions, a comprehensive understanding is needed. This study presents a regulatory network model (RNM) for nucleus pulposus cells (NPC), representing normal intervertebral disc (IVD) conditions. The RNM includes 33 proteins, and 153 interactions based on literature, incorporating key NPC regulatory mechanisms. A semi-quantitative approach calculates the basal steady state, accurately reflecting normal NPC activity. Model validation through published studies replicated pro-catabolic and pro-anabolic shifts, emphasizing the roles of transforming growth factor beta (TGF-β) and interleukin-1 receptor antagonist (IL-1Ra) in ECM regulation. This IVD RNM is a valuable tool for predicting IDD progression, offering insights into ECM degradation mechanisms and guiding experimental research on IVD health and degeneration.

M1 macrophage-derived exosomes promote intervertebral disc degeneration by enhancing nucleus pulposus cell senescence through LCN2/NF-κB signaling axis

Intervertebral disc degeneration (IVDD) is the primary factor contributing to low back pain (LBP). Unlike elderly patients, many young IVDD patients usually have a history of trauma or long-term abnormal stress, which may lead to local inflammatory reaction causing by immune cells, and ultimately accelerates degeneration. Research has shown the significance of M1-type macrophages in IVDD; nevertheless, the precise mechanism and the route by which it influences the function of nucleus pulposus cell (NPC) remain unknown. Utilizing a rat acupuncture IVDD model and an NPC degeneration model induced by lipopolysaccharide (LPS), we investigated the function of M1 macrophage-derived exosomes (M1-Exos) in IVDD both in vivo and in vitro in this study. We found that M1-Exos enhanced LPS-induced NPC senescence, increased the number of SA-β-gal-positive cells, blocked the cell cycle, and promoted the activation of P21 and P53. M1-Exos derived from supernatant pretreated with the exosome inhibitor GW4869 reversed this result in vivo and in vitro. RNA-seq showed that Lipocalin2 (LCN2) was enriched in M1-Exos and targeted the NF-κB pathway. The quantity of SA-β-gal-positive cells was significantly reduced with the inhibition of LCN2, and the expression of P21 and P53 in NPCs was decreased. The same results were obtained in the acupuncture-induced IVDD model. In addition, inhibition of LCN2 promotes the expression of type II collagen (Col-2) and inhibits the expression of matrix metalloproteinase 13 (MMP13), thereby restoring the equilibrium of metabolism inside the extracellular matrix (ECM) in vitro and in vivo. In addition, the NF-κB pathway is crucial for regulating M1-Exo-mediated NPC senescence. After the addition of M1-Exos to LPS-treated NPCs, p-p65 activity was significantly activated, while si-LCN2 treatment significantly inhibited p-p65 activity. Therefore, this paper demonstrates that M1 macrophage-derived exosomes have the ability to deliver LCN2, which activates the NF-κB signaling pathway, and exacerbates IVDD by accelerating NPC senescence. This may shed new light on the mechanism of IVDD and bring a fresh approach to IVDD therapy.

Research on the role and mechanism of IL-17 in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is one of the primary causes of low back pain (LBP), which seriously affects patients' quality of life. In recent years, interleukin (IL)-17 has been shown to be highly expressed in the intervertebral disc (IVD) tissues and serum of patients with IDD, and IL-17A has been shown to promote IDD through multiple pathways. We first searched databases such as PubMed, Cochrane, Embase, and Web of Science using the search terms "IL-17 or interleukin 17″ and "intervertebral discs". The search period ranged from the inception of the databases to December 2023. A total of 24 articles were selected after full-text screening. The main conclusion of the clinical studies was that IL-17A levels are significantly increased in the IVD tissues and serum of IDD patients. The results from the in vitro studies indicated that IL-17A can activate signaling pathways such as the NF-κB and MAPK pathways; promote inflammatory responses, extracellular matrix degradation, and angiogenesis; and inhibit autophagy in nucleus pulposus cells. The main finding of the in vivo experiments was that puncture of animal IVDs resulted in elevated levels of IL-17A within the IVD, thereby inducing IDD. Clinical studies, in vitro experiments, and in vivo experiments confirmed that IL-17A is closely related to IDD. Therefore, drugs that target IL-17A may be novel treatments for IDD, providing a new theoretical basis for IDD therapy.

Intervertebral disc degeneration and inflammatory microenvironment: expression, pathology, and therapeutic strategies

BACKGROUND

Intervertebral disc degeneration (IDD) is a leading cause of low back pain (LBP), posing a significant socioeconomic burden. Recent studies highlight the crucial role of inflammatory microenvironment in IDD progression.

METHOD

A keyword-based search was performed using the PubMed database for published articles.

RESULTS AND CONCLUSIONS

Dysregulated expression of inflammatory cytokines disrupts intervertebral disc (IVD) homeostasis, causing atrophy, fibrosis, and phenotypic changes in nucleus pulposus cells. Modulating the inflammatory microenvironment and restoring cytokine balance hold promise for IVD repair and regeneration. This comprehensive review systematically examines the expression regulation, pathological effects, therapeutic strategies, and future challenges associated with the inflammatory microenvironment and relevant cytokines in IDD. Key inflammatory cytokines, including interleukins (IL), tumor necrosis factor-alpha (TNF-α), and chemokines, exhibit significant pathological effects in IDD. Furthermore, major therapeutic modalities such as chemical antagonists, biologics, plant extracts, and gene transcription therapies are introduced to control and ameliorate the inflammatory microenvironment. These approaches provide valuable insights for identifying potential targets in future anti-inflammatory treatments for IDD.

Cellular senescence - Molecular mechanisms of intervertebral disc degeneration from an immune perspective

Intervertebral disc degeneration (IVDD) is a frequent and intractable chronic condition in orthopedics that causes enormous discomfort in patients' lives and thoughts, as well as a significant economic burden on society and the nation. As a result, understanding the pathophysiology of IVDD is critical. The pathophysiology of IVDD has been linked to numerous variables, including oxidative stress, apoptosis, matrix metalloproteinases, and inflammatory factors. Cellular senescence has recently attracted a lot of attention in the study of age-related diseases. It has been discovered that IVDD is intimately linked to human senescence, in which nucleus pulposus cell senescence may play a significant role. Previously, our group did a comprehensive and systematic clarification of the pathogenesis of IVDD from an immune perspective and discovered that the fundamental pathogenesis of IVDD is inflammatory upregulation and nucleus pulposus cell death caused by an imbalance in the immune microenvironment. In this review, we will treat nucleus pulposus cell senescence as a novelty point to clarify the pathophysiology of IVDD and further explore the probable relationship between senescence and immunity along with the dysregulation of the immunological microenvironment to propose new therapeutic approaches for IVDD.

Regulatory Effect of Inflammatory Mediators in Intervertebral Disc Degeneration

Intervertebral disc degeneration (IDD) is a major contributor to back, neck, and radicular pain. It is related to changes in tissue structure and function, including the breakdown of the extracellular matrix (ECM), aging, apoptosis of the nucleus pulposus, and biomechanical tissue impairment. Recently, an increasing number of studies have demonstrated that inflammatory mediators play a crucial role in IDD, and they are being explored as potential treatment targets for IDD and associated disorders. For example, interleukins (IL), tumour necrosis factor-α (TNF-α), chemokines, and inflammasomes have all been linked to the pathophysiology of IDD. These inflammatory mediators are found in high concentrations in intervertebral disc (IVD) tissues and cells and are associated with the severity of LBP and IDD. It is feasible to reduce the production of these proinflammatory mediators and develop a novel therapy for IDD, which will be a hotspot of future research. In this review, the effects of inflammatory mediators in IDD were described.

The Role of IL-17-Mediated Inflammatory Processes in the Pathogenesis of Intervertebral Disc Degeneration and Herniation: A Comprehensive Review

It has been reported that degenerated and herniated lumbar intervertebral discs show high expression of IL-17, suggesting that local immune reactions occur in patients with low back pain. While clinical sample analyses from different laboratories confirm this, it is not deeply not known on how IL-17 is induced in the pathology and their interactions with other inflammatory responses. This conscience review organizes current laboratory findings on this topic and present trajectory for full understanding on the role of IL-17 in pathology of intervertebral disc disease.

Degenerative disc disease in young adults: cytokine profile and angiogenic factors

Back pain (BP), associated with the degenerative disc disease (DDD), poses a heavy social and economic burden due to early disability and indications to surgery, emerging in young adults. Pathophysiological basis of premature intervertebral disc (IVD) degeneration is being actively studied. The study was aimed to define the profiles of inflammatory cytokines in DDD, as well as their relationship to the structural spine diseases. The molecular genetic analysis of the mRNA gene abundance in patients with BP and herniated IVD after discectomy and healthy individuals was performed by the quantitative polymerase chain reaction method. High expression of TNFα, IL17 was revealed in the IVD tissues of the affected patients (p < 0.01); the levels of TNFα and IL1β correlated with the DDD severity (r = 0.301 and 0.37; p < 0.05). Elevated expression of IL1β, IL6 was found in peripheral white blood cells (p < 0.01); the levels of IL6 negatively correlated with Modic type 1 and 2 changes (r = –0.31; p < 0.05), and the levels of IL17 positively correlated with the IVD herniation in combination with erosions of the adjacent vertebral body endplates and Modic changes (r = 0.401; p < 0.05). The expression of VEGF-А in the IVD tissues and white blood cells negatively correlated with the DDD grades (r = –0.85; p < 0.001), indicating reduced vascularization in the terminal phase of the disease. The findings on DDD demonstrate the contribution of the local low-immune inflammation, coupled with the intense disc vascularization at the earlier stages, and associated with the reactive inflammation in vertebral bodies. The results are prerequisites for developing the anti-inflammatory and reparative therapy based on the DDD grade and the presence of Modic changes in young adults with BP.

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

Objective

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

Methods

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

Results

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

Conclusion

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

Follistatin-Like 1 Attenuation Suppresses Intervertebral Disc Degeneration in Mice through Interacting with TNF-α and Smad Signaling Pathway

Background

Inflammation plays an important role in intervertebral disc degeneration (IDD). The protein follistatin-like 1 (FSTL1) plays a proinflammatory role in a variety of inflammatory diseases.

Objectives

The purpose of this study was to investigate whether IDD could be delayed by inhibiting FSTL-1 expression.

Methods

We established a puncture-induced IDD model in wild-type and FSTL-1+/- mice and collected intervertebral discs (IVDs) from the mice. Safranin O staining was used to detect cartilage loss of IVD tissue, and HE staining was used to detect morphological changes of IVD tissue. We measured the expression of FSTL-1 and related inflammatory indicators in IVD tissues by immunohistochemical staining, real-time PCR, and Western blotting.

Results

In the age-induced model of IDD, the level of FSTL-1 increased with the exacerbation of degeneration. In the puncture-induced IDD model, FSTL-1-knockdown mice showed a reduced degree of degeneration compared with that of wild-type mice. Further experiments showed that FSTL-1 knockdown also significantly reduced the level of related inflammatory factors in IVD. In vitro experiments showed that FSTL-1 knockdown significantly reduced TNF-α-induced inflammation. Specifically, the expression levels of the inflammatory factors COX-2, iNOS, MMP-13, and ADAMTS-5 were reduced. Knockdown of FSTL-1 attenuated inflammation by inhibiting the expression of P-Smad1/5/8, P-Erk1/2, and P-P65.

Conclusion

Knockdown of FSTL-1 attenuated inflammation by inhibiting the TNF-α response and Smad pathway activity and ultimately delayed IDD.

MiR-105 enhances osteogenic differentiation of hADSCs via the targeted regulation of SOX9

OBJECTIVE

To investigate whether miR-105 can regulate the osteogenic differentiation of human adipose-derived mesenchymal stem cells (hADSCs) by targeting SOX9.

METHODS

The hADSCs were grouped for subsequent transfection and induction of osteogenic differentiation as follows: control, miR-NC, miR-105 mimics, miR-105 inhibitors, SOX9, SOX9 siRNA, miR-105 mimics + SOX9 and miR-105 inhibitors + SOX9 siRNA groups. Next, hADSCs were stained for alkaline phosphatase (ALP), and Alizarin Red S staining (ARS) was performed. Osteogenic differentiation-related genes and miR-105 expression were assessed by qRT-PCR, while SOX9 protein expression was determined by Western blotting.

RESULTS

MiR-105 expression was increased and SOX9 protein expression was decreased during the osteogenic differentiation of hADSCs. A dual-luciferase reporter assay confirmed SOX9 to be a target gene of miR-105. Compared with the control group, the miR-105 mimics and SOX9 siRNA groups had elevated BMP2, OPN, OCN, BSP, Osx and Runx2 mRNA expression with reduced SOX9 expression, as well as increased ARS intensity and ALP activity. After transfection of miR-105 inhibitors/SOX9 into hADSCs, the results were the opposite. Overexpressing SOX9 reversed the effect of miR-105 in promoting the osteogenic differentiation of hADSCs.

CONCLUSION

MiR-105 could target SOX9 to improve the expression of osteogenic differentiation genes and thus enhance the osteogenic differentiation of hADSCs.

IL-38 alleviates the inflammatory response and the degeneration of nucleus pulposus cells via inhibition of the NF-κB signaling pathway in vitro

Previous studies have suggested that the inflammatory response contributes to the onset of intervertebral disc degeneration (IVDD). Interleukin (IL)-38, a newly discovered cytokine of the IL-1 family, has been demonstrated to play an anti-inflammatory role in autoimmune diseases, such as Crohn's disease, rheumatoid arthritis and psoriasis. However, whether IL-38 participates in the pathogenesis of IVDD remains unknown. In this study, human disc tissues from IVDD patients and rat disc tissues from an IVDD model were collected to measure the expression of IL-38 in the IVDD groups and the control groups by western blot and immunohistochemical staining. To further determine the role of IL-38 in IVDD, human nucleus pulposus cells (HNPCs) were stimulated with TNF-α to generate an in vitro model of inflammation to mimic the local inflammatory environment of the lumbar disc. The inflammatory response and HNPC degeneration markers were measured after stimulation with TNF-α and IL-38. IL-38 was upregulated in both the human and rat degenerated disc tissues compared with the control tissues. In vitro, IL-38 significantly decreased the TNF-α-induced expression of IL-1β, IL-6, COX-2, MMP-13 and ADAMTS-5 in the HNPCs, and IL-38 also alleviated the TNF-α-induced reductions in type II collagen and aggrecan. Moreover, IL-38 inhibited the activation of the NF-κB signaling pathway in the HNPC-based model of inflammation by reducing the expression level of the NF-κB P-P65 protein. In conclusion, IL-38 could alleviate the inflammatory response and HNPC degeneration in vitro via the inhibition of the NF-κB signaling pathway. These results suggest that IL-38 may be a new strategy for the treatment of IVDD.

Effects of etanercept, a tumor necrosis factor receptor fusion protein, on primary cell cultures prepared from intact human intervertebral disc tissue

The aim of the present study was to investigate the effects of etanercept (ETA), a tumor necrosis factor (TNF) inhibitor, on human cell cultures prepared from intact intervertebral disc tissue. ETA is used as a treatment for cases of rheumatoid arthritis, psoriatic arthritis, axial spondyloarthritis and ankylosing spondylitis accompanied by moderate or severe joint pain. ETA was applied to primary cell cultures [annulus fibrosus and nucleus pulposus (NP) from intact intervertebral disc tissue]. Cell cultures without ETA treatment served as the control group. Morphological and quantitative molecular analyses of the two groups were performed. The number of viable cells and cell proliferation decreased in the ETA-treated cultures as compared with those in the control group. Furthermore, in the treatment group, the chondroadherin gene, an NP-specific marker, was not expressed after 24 h. By contrast, the cartilage oligo matrix protein was expressed 24, 48 and 72 h post-ETA treatment, while its expression was significantly lower than that in the control group. In addition, the expression of interleukin-1β, as well as matrix metallopeptidase-7 and -19, was markedly decreased. Overall, the cell proliferation and gene expression in the ETA-treated cells were significantly different from those in the control group (P<0.05). These results suggest that the treatment duration and dosage of TNF inhibitors, which are used to suppress active inflammation, should be considered in the clinical setting. These biological agents may delay the healing of intervertebral disc tissue damage by slowing cell proliferation and altering gene expression via anabolic and catabolic pathways.

Resveratrol inhibits IL-1β-mediated nucleus pulposus cell apoptosis through regulating the PI3K/Akt pathway

Nucleus pulposus (NP) cell apoptosis is a classical cellular character during intervertebral disc degeneration (IDD). Previous studies have shown that inflammatory cytokine-induced NP cell apoptosis plays an important role in disc degeneration. The present study was aimed to investigate whether resveratrol can suppress IL-1β-mediated NP cell apoptosis and the potential signal transduction pathway. Experimental rat NP cells were treated with culture medium containing IL-1β (20 ng/ml) for 7 days. Control NP cells were cultured in the baseline medium. Resveratrol was added along with culture medium to investigate its effects. The inhibitor LY294002 was used to study the role of the PI3K/Akt pathway. NP cell apoptosis was reflected by the caspase-3 activity, cell apoptosis ratio, and expression of apoptosis-related molecules (Bcl-2, Bax, caspase-3, cleaved caspase-3, and cleaved PARP). Compared with the control NP cells, IL-1β significantly increased caspase-3 activity, NP cell apoptosis ratio and mRNA/protein expression of Bax, caspase-3, cleaved caspase-3 and cleaved PARP, but decreased mRNA expression of Bcl-2. However, resveratrol partly suppressed the effects of IL-1β on those cell apoptosis-related parameters. Further analysis showed that IL-1β significantly decreased activity of the PI3K/Akt pathway whereas resveratrol partly increased activity of the PI3K/Akt pathway in NP cells treated with IL-1β. Additionally, when the inhibitor LY294002 was added along with the resveratrol, its protective effects against IL-1β-induced NP cell apoptosis were attenuated. In conclusion, resveratrol suppresses IL-1β-mediated NP cell apoptosis through activating the PI3K/Akt pathway. Resveratrol may be an effective drug to attenuate inflammatory cytokine-induced disc degenerative changes.

Upregulation of ADAMTS‑7 and downregulation of COMP are associated with spontaneous abortion

A disintegrin and metalloproteinase with thrombospondin motifs 7 (ADAMTS-7) has been revealed to serve an important role in inflammation-associated diseases. However, the role of ADAMTS-7 in spontaneous abortion (SA) remains unclear. In the present study, human and mouse decidual tissues were used to detect the expression of ADAMTS-7 and cartilage oligomeric matrix protein (COMP) in mice with lipopolysaccharide (LPS)-induced abortion (10 mice/group), and in SA humans and the corresponding control group (21 participants in the SA group and 15 participants in the control group). The results revealed that ADAMTS-7 expression was upregulated and that COMP expression was downregulated in the mouse decidual tissue of the LPS-induced abortion group, when compared with that of the normal control group. The results were further confirmed by western blot analysis and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis, which revealed increased ADAMTS-7 and decreased COMP expression at the protein and mRNA levels in mice treated with LPS. Additionally, the expression of ADAMTS-7 was negatively correlated with the expression of COMP in mice, with a correlation coefficient of −0.936 (P<0.001). In addition, the expression of ADAMTS-7 and COMP exhibited was similar in the decidual tissue of SA patients when compared with the levels observed in the tissues of the normal control participants, as demonstrated by increased ADAMTS-7 expression and decreased COMP expression. Western blotting and RT-qPCR analysis revealed that ADAMTS-7 was increased and COMP was decreased in the decidual tissue of SA subjects. The correlation analysis of ADAMTS-7 and COMP in human decidual tissue also revealed a similar result, with a correlation coefficient of −0.836 (P<0.001). The results of the present study demonstrated that ADAMTS-7 was upregulated and COMP was downregulated in the decidual tissues of humans and mice with SA, and a negative correlation was identified between the expression levels of ADAMTS-7 and COMP, thereby providing novel evidence for a better understanding of the pathogenesis of SA, which may lead to improvements in the clinical pregnancy outcomes of these individuals.

Cervical disc degeneration and neck pain

Cervical intervertebral disc has long been considered a common source of neck pain. However, the pain caused by the disc itself has not been clearly defined so far, and its diagnosis and treatment has always been controversial. Degenerative cervical disc has a rich supply of nerve fibers, is prone to inflammatory reactions, and is susceptible to pain that can be provoked by disc stimulation or distention, and can be eliminated by block. Overwhelming clinical evidence demonstrates that neck pain in patients with degenerative cervical radiculopathy or myelopathy can be subsided rapidly by anterior cervical surgery, further indicating that this neck pain stems from the pathology of cervical disc itself. Cervical discography is advocated as the only test that connects disease to symptoms, but the procedure remains controversial. If strict criteria and technique are maintained, discography can discriminate painful, symptomatic discs from nonpainful, asymptomatic discs. Discogenic neck pain alone without cervical disc herniation or cervical spondylosis accounts for a large proportion of chronic neck pain. For these patients who continue to have refractory neck pain and fail to respond to conservative treatment, anterior cervical fusion surgery or artificial cervical disc replacement may be a better choice, and preoperative cervical discography can guarantee the excellent surgical results. Existing basic and clinical studies have scientifically shown that cervical intervertebral disc degeneration can lead to neck pain.

* CRISPR-Based Epigenome Editing of Cytokine Receptors for the Promotion of Cell Survival and Tissue Deposition in Inflammatory Environments

Musculoskeletal diseases have been associated with inflammatory cytokine action, particularly action by TNF-α and IL-1β. These inflammatory cytokines promote apoptosis and senescence of cells in diseased tissue and extracellular matrix breakdown. Stem cell-based therapies are being considered for the treatment of musculoskeletal diseases, but the presence of these inflammatory cytokines will have similar deleterious action on therapeutic cells delivered to these environments. Methods that prevent inflammatory-induced apoptosis and proinflammatory signaling, in cell and pathway-specific manners are needed. In this study we demonstrate the use of clustered regularly interspaced short palindromic repeats (CRISPR)-based epigenome editing to alter cell response to inflammatory environments by repressing inflammatory cytokine cell receptors, specifically TNFR1 and IL1R1. We targeted CRISPR/Cas9-based repressors to TNFR1 and IL1R1 gene regulatory elements in human adipose-derived stem cells (hADSCs) and investigated the functional outcomes of repression of these genes. Efficient signaling regulation was demonstrated in engineered hADSCs, as activity of the downstream transcription factor NF-κB was significantly reduced or maintained at baseline levels in the presence of TNF-α or IL-1β. Pellet culture of undifferentiated hADSCs demonstrated improved survival in engineered hADSCs treated with TNF-α or IL-1β, while having little effect on their immunomodulatory properties. Furthermore, engineered hADSCs demonstrated improved chondrogenic differentiation capacity in the presence of TNF-α or IL-1β, as shown by superior production of glycosaminglycans in this inflammatory environment. Overall this work demonstrates a novel method for modulating cell response to inflammatory signaling that has applications in engineering cells delivered to inflammatory environments, and as a direct gene therapy to protect endogenous cells exposed to chronic inflammation, as observed in a broad spectrum of degenerative musculoskeletal pathology.

Regulation of a disintegrins and metalloproteinase with thrombospondin motifs 7 during inflammation in nucleus pulposus (NP) cells: role of AP-1, Sp1 and NF-κB signaling

AIM

The objective of this study is to explore the effect of inflammatory cytokines on a disintegrins and metalloproteinase with thrombospondin motifs 7 (ADAMTS7) and to demonstrate the role of Sp1, AP-1 and NF-κB signaling on the ADAMTS7 regulation during inflammation in NP cells.

METHODS

Real-time PCR was to detect the effect of ADAMTS7 knockdown on the expression of catabolic enzymes during inflammatory condition in NP cells. Real-time PCR, western blot, immunofluorescence and transfection experiments were used to observe the effect of tumor necrosis factor-α (TNF-α) or interleukin-1β on the expression and the activity of ADAMTS7, and demonstrated the role to Sp1, AP-1 and NF-κB in the regulation of ADAMTS7 during inflammation.

RESULTS

As other cells, ADAMTS7 knockdown suppressed the mRNA expression of catabolic factors during inflammation in human NP cells. However, the expression of ADAMTS7 mRNA and protein and the activity of ADAMTS7 promoter were refractory to inflammatory cytokines. In addition, Sp1, AP-1, not NF-κB signaling sustained the expression of ADAMTS7 mRNA, protein, as well as promoter activity during inflammation in NP cells.

CONCLUSION

ADAMTS7 played a crucial role in the expression of catabolic genes in the presence of TNF-α and AP-1, Sp1, not NF-κB signaling were critical for the maintenance of ADAMTS7 expression during inflammation in NP cells.

Molecular mechanisms of cell death in intervertebral disc degeneration (Review)

Intervertebral discs (IVDs) are complex structures that consist of three parts, namely, nucleus pulposus, annulus fibrosus and cartilage endplates. With aging, IVDs gradually degenerate as a consequence of many factors, such as microenvironment changes and cell death. Human clinical trial and animal model studies have documented that cell death, particularly apoptosis and autophagy, significantly contribute to IVD degeneration. The mechanisms underlying this phenomenon include the activation of apoptotic pathways and the regulation of autophagy in response to nutrient deprivation and multiple stresses. In this review, we briefly summarize recent progress in understanding the function and regulation of apoptosis and autophagy signaling pathways. In particular, we focus on studies that reveal the functional mechanisms of these pathways in IVD degeneration.