Salubrinal Suppresses IL-17-Induced Upregulation of MMP-13 and Extracellular Matrix Degradation Through the NF-kB Pathway in Human Nucleus Pulposus Cells

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.

Current status and development direction of immunomodulatory therapy for intervertebral disk degeneration

Intervertebral disk (IVD) degeneration (IVDD) is a main factor in lower back pain, and immunomodulation plays a vital role in disease progression. The IVD is an immune privileged organ, and immunosuppressive molecules in tissues reduce immune cell (mainly monocytes/macrophages and mast cells) infiltration, and these cells can release proinflammatory cytokines and chemokines, disrupting the IVD microenvironment and leading to disease progression. Improving the inflammatory microenvironment in the IVD through immunomodulation during IVDD may be a promising therapeutic strategy. This article reviews the normal physiology of the IVD and its degenerative mechanisms, focusing on IVDD-related immunomodulation, including innate immune responses involving Toll-like receptors, NOD-like receptors and the complement system and adaptive immune responses that regulate cellular and humoral immunity, as well as IVDD-associated immunomodulatory therapies, which mainly include mesenchymal stem cell therapies, small molecule therapies, growth factor therapies, scaffolds, and gene therapy, to provide new strategies for the treatment of IVDD.

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.

Oxidative stress in intervertebral disc degeneration: Molecular mechanisms, pathogenesis and treatment

Low back pain (LBP) is a leading cause of labour loss and disability worldwide, and it also imposes a severe economic burden on patients and society. Among symptomatic LBP, approximately 40% is caused by intervertebral disc degeneration (IDD). IDD is the pathological basis of many spinal degenerative diseases such as disc herniation and spinal stenosis. Currently, the therapeutic approaches for IDD mainly include conservative treatment and surgical treatment, neither of which can solve the problem from the root by terminating the degenerative process of the intervertebral disc (IVD). Therefore, further exploring the pathogenic mechanisms of IDD and adopting targeted therapeutic strategies is one of the current research hotspots. Among the complex pathophysiological processes and pathogenic mechanisms of IDD, oxidative stress is considered as the main pathogenic factor. The delicate balance between reactive oxygen species (ROS) and antioxidants is essential for maintaining the normal function and survival of IVD cells. Excessive ROS levels can cause damage to macromolecules such as nucleic acids, lipids, and proteins of cells, affect normal cellular activities and functions, and ultimately lead to cell senescence or death. This review discusses the potential role of oxidative stress in IDD to further understand the pathophysiological processes and pathogenic mechanisms of IDD and provides potential therapeutic strategies for the treatment of IDD.

Low back pain and osteoarthritis pain: a perspective of estrogen

Low back pain (LBP) is the world's leading cause of disability and is increasing in prevalence more rapidly than any other pain condition. Intervertebral disc (IVD) degeneration and facet joint osteoarthritis (FJOA) are two common causes of LBP, and both occur more frequently in elderly women than in other populations. Moreover, osteoarthritis (OA) and OA pain, regardless of the joint, are experienced by up to twice as many women as men, and this difference is amplified during menopause. Changes in estrogen may be an important contributor to these pain states. Receptors for estrogen have been found within IVD tissue and nearby joints, highlighting the potential roles of estrogen within and surrounding the IVDs and joints. In addition, estrogen supplementation has been shown to be effective at ameliorating IVD degeneration and OA progression, indicating its potential use as a therapeutic agent for people with LBP and OA pain. This review comprehensively examines the relationship between estrogen and these pain conditions by summarizing recent preclinical and clinical findings. The potential molecular mechanisms by which estrogen may relieve LBP associated with IVD degeneration and FJOA and OA pain are discussed.

Kartogenin-loaded hydrogel promotes intervertebral disc repair via protecting MSCs against reactive oxygen species microenvironment by Nrf2/TXNIP/NLRP3 axis

Intervertebral disc (IVD) degeneration (IDD) and the consequent low back pain present a major medical challenge. Stem cell-based tissue engineering is promising for the treatment of IDD. However, stem cell-based treatment is severely impaired by the increased generation of reactive oxygen species (ROS) in degenerative disc, which can lead to a high level of cell dysfunction and even death. In this study, a kartogenin (KGN)@PLGA-GelMA/PRP composite hydrogel was designed and used as a carrier of ADSCs-based therapies in disc repair. Injectable composite hydrogel act as a carrier for controlled release of KGN and deliver ADSCs to the degenerative disc. The released KGN can stimulate the differentiation of ADSCs into a nucleus pulposus (NP) -like phenotype and boost antioxidant capacity of ADSCs via activating Nrf2/TXNIP/NLRP3 axis. Furthermore, the composite hydrogel combined with ADSCs attenuated the in vivo degeneration of rat IVDs, maintained IVD tissue integrity and accelerated the synthesis of NP-like extracellular matrix. Therefore, the KGN@PLGA-GelMA/PRP composite hydrogel is a promising strategy for stem cell-based therapies of IDD.

Hesperidin mitigates oxidative stress-induced ferroptosis in nucleus pulposus cells via Nrf2/NF-κB axis to protect intervertebral disc from degeneration

Intervertebral disc degeneration (IVDD), a widely known contributor to low back pain (LBP), has been proved to be a global health challenging conundrum. Hesperidin (hesperetin-7-O-rutinoside, HRD) is a flavanone glycoside that belongs to the subgroup of citrus flavonoids with therapeutic effect on various diseases due to its anti-inflammatory, antioxidant properties. However, the effect of HRD on IVDD remains elusive. The human nucleus pulposus tissues were harvested for isolating human nucleus pulposus (HNP) cells to verify the expression of Nrf2. The biological effect of HRD on HNP cells were assessed in vitro, and the in vivo therapeutic effects of HRD were assessed in mice. Firstly, we found that the expression of Nrf2 was decreased with the progression of degeneration in degenerated human nucleus pulposus tissue. Subsequently, we confirmed that HRD could mitigate oxidative stress-induced ferroptosis in nucleus pulposus cells via enhancing the expression of Nrf2 axis and suppressing the NF-κB pathway to protect intervertebral disc from degeneration in vitro. Finally, the therapeutic effects of HRD were confirmed in vivo. The current study proved for the first time that HRD may protect HNP cells from degeneration by suppressing ferroptosis in an oxidative stress-dependent via enhancing the expression of Nrf2 and suppressing the NF-κB pathway. The evidence will provide a possible basis for future targeted treatment for IVDD.

Oligosaccharides of Polygonatum Cyrtonema Hua ameliorates dextran sulfate sodium-induced colitis and regulates the gut microbiota

Ulcerative colitis (UC) is one common chronic inflammatory bowel disease that causes severe side effects, and expensive treatment limits effective and sustained treatment of UC. Fructooligosaccharide was isolated from Polygonatum Cyrtonema Hua (PFOS) and exhibits anti-inflammatory effects. Therefore, we are curious whether PFOS could be used for the treatment of UC. PFOS was introduced via intragastric gavage to C57BL/6 J mice exposed to acute colitis induced by DSS. The results showed that doses of PFOS at 2 and 5 mg/kg/day alleviated the DSS-induced histopathological damage and improved intestinal barrier function. qPCR analysis revealed that PFOS exerted a significant downregulation of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and upregulation of antioxidant genes, including superoxide dismutase1 (SOD1), glutathion peroxidase2 (GPX2), and nuclear factor erythroid 2 related factor2 (Nrf2). Furthermore, PFOS suppressed the DSS-induced disruption of the mucosal barrier by downregulating MMP13. Moreover, using 16 S rRNA gene-based microbiota analysis, PFOS could selectively enhance the growth of probiotics, including Bifidobacterium, Alloprevofella, and Alistipes. Our findings indicated that PFOS attenuated DSS-induced colitis in mice, suggesting that PFOS might be used as an efficacious supplement for reducing inflammatory bowel disease.

An in-depth analysis of the immunomodulatory mechanisms of intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is the pathological basis of disc herniation, spinal stenosis, and other related diseases, and the lower back pain it produces lays a heavy financial burden on individuals and society. Thus, it is essential to comprehend IVDD's pathophysiology. Numerous factors, such as inflammatory factors, oxidative stress, apoptosis, matrix metalloproteinases, are linked to IVDD pathogenesis. Despite the fact that many researches has provided explanations for the pathophysiology of IVDD, these studies are typically singular, restricted, and isolated, expound only on one or two components, and do not systematically analyze and summarize the numerous influencing elements. In addition, we discovered that the incidence of many chronic diseases in the field of orthopedics may be thoroughly and systematically defined in terms of immunological systems. In order to provide a theoretical foundation for an in-depth understanding of the pathological process of IVDD and the formulation of more effective prevention and treatment measures, this review provides a comprehensive and systematic account of the pathogenesis of IVDD from the physical to the molecular barriers of the intervertebral disc, from the nucleus pulposus tissue to the cellular to the immune-molecular level.

Oxidative Stress and Intervertebral Disc Degeneration: Pathophysiology, Signaling Pathway, and Therapy

Intervertebral disc degeneration (IDD), characterized as decreased proteoglycan content, ossification of endplate, and decreased intervertebral height, is one of the major reasons of low back pain, which seriously affects the quality of life and also brings heavy economic burden. However, the mechanisms leading to IDD and its therapeutic targets have not been fully elucidated. Oxidative stress refers to the imbalance between oxidation and antioxidant systems, between too many products of reactive oxygen species (ROS) and the insufficient scavenging function. Excessive ROS can damage cell lipids, nucleic acids and proteins, which has been proved to be related to the development of a variety of diseases. In recent years, an increasing number of studies have reported that oxidative stress is involved in the pathological process of IDD. Excessive ROS can accelerate the IDD process via inducing the pathological activities, such as inflammation, apoptosis, and senescence. In this review, we focused on pathophysiology and molecular mechanisms of oxidative stress-induced IDD. Moreover, the present review also summarized the possible ideas for the future therapy strategies of oxidative stress-related IDD.

Application of mesenchymal stem cell-derived exosomes from different sources in intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is a main cause of lower back pain, leading to psychological and economic burdens to patients. Physical therapy only delays pain in patients but cannot eliminate the cause of IVDD. Surgery is required when the patient cannot tolerate pain or has severe neurological symptoms. Although surgical resection of IVD or decompression of the laminae eliminates the diseased segment, it damages adjacent normal IVD. There is also a risk of re-protrusion after IVD removal. Cell therapy has played a crucial role in the development of regenerative medicine. Cell transplantation promotes regeneration of degenerative tissue. However, owing to the lack of vascular structure in IVD, sufficient nutrients cannot be provided for transplanted mesenchymal stem cells (MSCs). In addition, dead cells release harmful substances that aggravate IVDD. Extracellular vesicles (EVs) have been extensively studied as an emerging therapeutic approach. EVs generated by paracrine MSCs retain the potential of MSCs and serve as carriers to deliver their contents to target cells to regulate target cell activity. Owing to their double-layered membrane structure, EVs have a low immunogenicity and no immune rejection. Therefore, EVs are considered an emerging therapeutic modality in IVDD. However, they are limited by mass production and low loading rates. In this review, the structure of IVD and advantages of EVs are introduced, and the application of MSC-EVs in IVDD is discussed. The current limitations of EVs and future applications are described.

Targeting Autophagy for Developing New Therapeutic Strategy in Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is a prevalent cause of low back pain. IVDD is characterized by abnormal expression of extracellular matrix components such as collagen and aggrecan. In addition, it results in dysfunctional growth, senescence, and death of intervertebral cells. The biological pathways involved in the development and progression of IVDD are not fully understood. Therefore, a better understanding of the molecular mechanisms underlying IVDD could aid in the development of strategies for prevention and treatment. Autophagy is a cellular process that removes damaged proteins and dysfunctional organelles, and its dysfunction is linked to a variety of diseases, including IVDD and osteoarthritis. In this review, we describe recent research findings on the role of autophagy in IVDD pathogenesis and highlight autophagy-targeting molecules which can be exploited to treat IVDD. Many studies exhibit that autophagy protects against and postpones disc degeneration. Further research is needed to determine whether autophagy is required for cell integrity in intervertebral discs and to establish autophagy as a viable therapeutic target for IVDD.

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.

The Proteolysis of ECM in Intervertebral Disc Degeneration

Intervertebral disc (IVD) degeneration (IDD) is a pathological process that commonly occurs throughout the human life span and is a major cause of lower back pain. Better elucidation of the molecular mechanisms involved in disc degeneration could provide a theoretical basis for the development of lumbar disc intervention strategies. In recent years, extracellular matrix (ECM) homeostasis has received much attention due to its relevance to the mechanical properties of IVDs. ECM proteolysis mediated by a variety of proteases is involved in the pathological process of disc degeneration. Here, we discuss in detail the relationship between the IVD as well as the ECM and the role of ECM proteolysis in the degenerative process of the IVD. Targeting ECM proteolysis-associated proteases may be an effective means of intervention in IDD.

Aloin Regulates Matrix Metabolism and Apoptosis in Human Nucleus Pulposus Cells via the TAK1/NF-κB/NLRP3 Signaling Pathway

Intervertebral disc degeneration (IDD) is a degenerative disease that is characterized by decreased matrix synthesis and extra degradation, nucleus pulposus cells (NPCs) apoptosis, and infiltration of inflammatory factors. Aloin, a colored compound from aloe plants, has been shown to be effective against skeletal degenerative diseases, but it is unclear whether it is protective against IDD. Herein, we investigated the role of aloin in NPCs. In our study, the upregulation of proinflammatory factors, apoptosis, and unbalanced matrix metabolism were observed in degenerative NP tissues. We found that aloin had a curative effect on extracellular matrix metabolism and apoptosis in TNF-alpha- (TNF-α-) treated NPCs by inhibiting oxidative stress and the proinflammatory factor expression. Further investigation revealed that aloin treatment suppressed the TAK1/NF-κB pathway. Moreover, the expression level of the NLPR3 inflammasome was downregulated after aloin treatment in TNF-α-treated NPCs. In summary, our results demonstrated that aloin treatment can reverse TNF-α-induced unbalanced matrix metabolism and apoptosis of NPCs via the TAK1/NF-κB/NLRP3 axis. This study supports that aloin can be a promising therapeutic agent for IDD.

The Role of Oxidative Stress in Intervertebral Disc Degeneration

Intervertebral disc degeneration is a very common type of degenerative disease causing severe socioeconomic impact, as well as a major cause of discogenic low back pain and herniated discs, placing a heavy burden on patients and the clinicians who treat them. IDD is known to be associating with a complex process involving in extracellular matrix and cellular damage, and in recent years, there is increasing evidence that oxidative stress is an important activation mechanism of IDD and that reactive oxygen and reactive nitrogen species regulate matrix metabolism, proinflammatory phenotype, autophagy and senescence in intervertebral disc cells, apoptosis, autophagy, and senescence. Despite the tremendous efforts of researchers within the field of IDD pathogenesis, the proven strategies to prevent and treat this disease are still very limited. Up to now, several antioxidants have been proved to be effective for alleviating IDD. In this article, we discussed that oxidative stress accelerates disc degeneration by influencing aging, inflammation, autophagy, and DNA methylation, and summarize some antioxidant therapeutic measures for IDD, indicating that antioxidant therapy for disc degeneration holds excellent promise.

The role of oxidative stress in intervertebral disc cellular senescence

With the aggravation of social aging and the increase in work intensity, the prevalence of spinal degenerative diseases caused by intervertebral disc degeneration(IDD)has increased yearly, which has driven a heavy economic burden on patients and society. It is well known that IDD is associated with cell damage and degradation of the extracellular matrix. In recent years, it has been found that IDD is induced by various mechanisms (e.g., genetic, mechanical, and exposure). Increasing evidence shows that oxidative stress is a vital activation mechanism of IDD. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) could regulate matrix metabolism, proinflammatory phenotype, apoptosis, autophagy, and aging of intervertebral disc cells. However, up to now, our understanding of a series of pathophysiological mechanisms of oxidative stress involved in the occurrence, development, and treatment of IDD is still limited. In this review, we discussed the oxidative stress through its mechanisms in accelerating IDD and some antioxidant treatment measures for IDD.

Salubrinal protects against inflammatory response in macrophage and attenuates psoriasiform skin inflammation by antagonizing NF-κB signaling pathway

Psoriasiform skin inflammation is the common chronic skin inflammatory disease with no effective clinical therapy. Salubrinal is a multifunctional molecule playing a protective role in several conditions. Recently, studies have reported that Salubrinal is a potential therapeutic agent for inflammatory diseases. However, the protective role of Salubrinal in psoriasis-like skin inflammation remains unknown. In this article, imiquimod (IMQ)-induced psoriasis models were established in wild-type mice to explore the role of Salubrinal in the development of psoriasis. As a result, the IMQ-induced mouse models exhibited typical skin inflammation, which was alleviated by the administration of Salubrinal. Furthermore, RAW264.7 macrophage was stimulated with Lipopolysaccharide(LPS) in the presence or absence of Salubrinal. LPS stimulation elevated the expression of various inflammatory biomarkers, while the administration of Salubrinal abolished the function of LPS in RAW264.7 macrophages. In addition, the activation of the nuclear factor-kappa B (NF-κB) signaling pathway in both the LPS-stimulated RAW264.7 macrophage and psoriasis mouse models was antagonized by the administration of Salubrinal. Collectively, Salubrinal might be considered as a promising therapeutic agent for psoriasis-like skin inflammation.

LIPUS inhibits inflammation and catabolism through the NF-κB pathway in human degenerative nucleus pulposus cells

Background

Low-intensity pulsed ultrasound (LIPUS) is a safe and noninvasive rehabilitative physical therapy with anti-inflammatory effects. The current study investigated the effect of LIPUS on the inflammation of nucleus pulposus (NP) cells and its underlying mechanism.

Methods

Human NP cells were acquired from lumbar disc herniation tissue samples and cultured for experiments. Human NP cells were treated with LPS and then exposed to LIPUS (15 mW/cm², 30 mW/cm² and 60 mW/cm²) for 20 min daily for 3 days to determine the appropriate intensity to inhibit the expression of the inflammatory factors TNF-α and IL-1β. The gene and protein expression of aggrecan, collagen II, MMP-3 and MMP-9 was measured by real‐time PCR and western blotting, respectively. The activity of the nuclear factor‐kappa B (NF‐κB) pathway was examined by western blotting and immunofluorescence. After pretreatment with the NF-κB inhibitor PDTC, the expression of TNF-α, IL-1β, MMP-3 and MMP-9 was measured by real‐time PCR.

Results

LIPUS at intensities of 15 mW/cm², 30 mW/cm² and 60 mW/cm² inhibited LPS-induced NP cell expression of the inflammatory factors TNF-α and IL-1β, especially at 30 mW/cm². LIPUS significantly upregulated the gene and protein expression of aggrecan and collagen II and downregulated the gene and protein expression of MMP-3 and MMP-9 in LPS-induced NP cells. The NF‐κB signaling pathway was inhibited by LIPUS through inhibiting the protein expression of p-P65 and the translocation of P65 into the nucleus in LPS-induced NP cells. In addition, LIPUS had similar effects as the NF-κB inhibitor PDTC by inhibiting the NF-κB signaling pathway, inflammation and catabolism in LPS-induced human degenerative nucleus pulposus cells.

Conclusion

LIPUS inhibited inflammation and catabolism through the NF‐κB pathway in human degenerative nucleus pulposus cells.

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.

Sinapic Acid Inhibits IL-1β-Induced Apoptosis and Catabolism in Nucleus Pulposus Cells and Ameliorates Intervertebral Disk Degeneration

Background

Low back pain (LBP) is a very common condition and leads to serious pain, disability, and price tag all over the world. Intervertebral disk degeneration (IDD) is one of the major reasons that contributed to LBP. The levels of interleukin 1 beta (IL-1β) increase significantly in degenerative disks. IL-1β also accelerates IDD. Sinapic acid (SA) has the effect of anti‐inflammatory, antioxidant and antimicrobial. However, the effect of SA on IDD has never been studied. Therefore, the aim of this study was to figure out whether SA has protective effect on nucleus pulposus (NP) cells and further explore the possible underlying mechanism.

Methods

The nucleus pulposus (NP) tissues of rats were collected and cultured into NP cells. The NP cells were stimulated by IL-1β and treated with SA. In vitro treatment effects were evaluated by ELISA, Western blot assay, immunofluorescence, TUNEL method and real-time PCR. We conducted percutaneous needle puncture in the rat tail to build intervertebral disk degeneration model and treated rats with SA. In vivo treatment effects were evaluated by hematoxylin and eosin (HE) and safranin O (SO) staining and magnetic resonance imaging (MRI) method.

Results

Our results showed that SA not only inhibited apoptosis but also suppressed inflammatory mediators including nitric oxide (NO), prostaglandin E2 (PGE2), cyclooxygenase 2 (COX-2), inducible nitric oxide synthase (iNOS) interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) in IL-1β-stimulated NP cells. As to extracellular matrix (ECM), SA could increase collagen II and aggrecan levels and reduce the expression of MMP13 and ADAMTS5 during the stimulation of IL-1β. Furthermore, SA could activate nuclear factor‐erythroid 2‐related factor‐2 (Nrf2) to inhibit nuclear factor κB (NF‐κB) induced by IL‐1β. Nrf2 knockdown partly reduced the protective effect of SA on NP cells. Correspondingly, SA ameliorated IDD by promoting Nrf2 expression. In vivo results also showed that SA could delay the progression of IDD.

Conclusion

In conclusion, we demonstrated that SA could protect the degeneration of NP cells and revealed the underlying mechanism of SA on Nrf2 activation in NP cells.

MicroRNA-25-3p therapy for intervertebral disc degeneration by targeting the IL-1β/ZIP8/MTF1 signaling pathway with a novel thermo-responsive vector

Background

MicroRNAs play important roles in intervertebral disc degeneration (IDD). The therapeutic effects of miRNA-25-3p on IDD and underlying mechanism are unclear.

Methods

Normal and degenerated nuclear pulposus (NP) tissue were collected. Primary NP cells were isolated and treated with different concentrations of interleukin-1β (IL-1β). IL-1β treated NP cells were interfered with miRNA-25-3p. Associated proteins IL-1β, ZIP8, MTF1, extracellular matrix (ECM) degrading enzymes MMP3, MMP13, ADAMTS5, ECM proteins type II collagen, aggrecan and MiRNA-25-3p were detected by western blotting or qRT-PCR method. Dual luciferase reporter assays were performed to determine potential targets MTF1 of miRNA-25-3p. In vitro miRNA-25-3p transfection efficiency of thermos-responsive vector was observed by fluorescence microscopy. Animal studies were conducted to observe the therapeutic effects of miRNA-25-3p mimic delivered by thermo-responsive vector.

Results

Compared with normal NP tissues, IL-1β, ZIP8 and MTF1 significantly increased and miRNA-25-3p significantly decreased in degenerated tissues. IL-1β promotes the expression of ZIP8 and nuclear translocation of MTF1 in NP cells. Ultimately, it promotes expression of ECM degrading enzymes and inhibits synthesis of ECM protein. MiRNA- 25-3p could inhibit the effects of IL-1β and the expression of ECM degrading enzymes, and recover the expression of ECM protein. Further investigation showed MTF1 was a target protein of miRNA-25-3p. The thermo-responsive vector could effectively deliver miRNA-25-3p into NP cells. Animal studies demonstrated miRNA-25-3p delivered by the thermo-responsive vector can delay progression of IDD

Conclusions

The thermo-responsive vector delivering miRNA-25-3p could delay the progression of IDD by inhibiting IL-1β-induced effects, and may be potential therapy for IDD in future.

17β-Estradiol Prevents Extracellular Matrix Degradation by Downregulating MMP3 Expression via PI3K/Akt/FOXO3 Pathway

STUDY DESIGN

In vitro studies of the role of 17β-estradiol (E2) and its possible targets in intervertebral disc degeneration (IDD).

OBJECTIVE

To define the regulatory role of E2 in IDD and the potential mechanisms.

SUMMARY OF BACKGROUND DATA

IDD has intricate etiology that is influenced by multiple risk factors. However, the underlying molecular mechanisms of occurrence and progression of IDD are not well elucidated. The degradation of extracellular matrix (ECM) has been extensively observed in IDD. E2 was found to inhibit ECM degradation in human nuleus pulposus cells (HNPCs), but the molecular mechanism remained to be determined.

METHODS

Western blot and qPCR was performed to quantify the expression of target proteins in HNPCs. Luciferase reporter gene assay was applied to detect the effects of E2 and forkhead box O-3 (FOXO3) on matrix metalloproteinases (MMP)-3 promoter activity. Chromatin immunoprecipitation assay analyzed the binding of FOXO3 to MMP-3 and the effect of E2 on this process.

RESULTS

We identified the upregulation of collagen II and aggrecan by E2 independent of time and concentration. And E2 downregulated MMP-3 expression in human nucleus pulposus cells. The phosphorylation of FOXO3 led to the reduction of MMP-3 promoter activity. Furthermore, 17β-estradiol-induced the activation of PI3K/Akt pathway is required for FOXO3 phosphorylated.

CONCLUSION

E2 prevents the degradation of ECM by upregulating collagen II and aggrecan expression via reducing MMP-3 expression in HNPCs, and PI3K/Akt/FOXO3 pathway is dispensable for MMP-3 downregulated. Therefore, E2 protects against IDD by preventing ECM degradation.

LEVEL OF EVIDENCE

3.

Procyanidin B3 alleviates intervertebral disc degeneration via interaction with the TLR4/MD-2 complex

As a chronic musculoskeletal degeneration disease, intervertebral disc degeneration (IVDD) has been identified as a crucial cause for low back pain. This condition has a prevalence of 80% among adults without effective preventative therapy. Procyanidin B3 (Pro‐B3) is a procyanidin dimer, which is widely present in the human diet and has multiple functions, such as preventing inflammation. But the inhibiting effect of Pro‐B3 in IVDD development is still no known. Thus, our study aimed to demonstrate the therapeutical effect of Pro‐B3 in IVDD and explain the underlying mechanism. In vitro studies, human nucleus pulposus (NP) cells were isolated and exposed in lipopolysaccharide (LPS) to simulate IVDD development. Pro‐B3 pre‐treatment inhibited LPS‐induced production of inflammation correlated factors such as tumour necrosis factor α (TNF‐α), interleukin‐6 (IL‐6), prostaglandin E2 (PGE2) and Nitric oxide (NO). On the other hand, LPS‐medicated extracellular matrix (ECM) breakdown was blocked in Pro‐B3 treated NP cells. Additionally, Pro‐B3 treatment blocked the activation of NF‐κB/toll‐like receptor 4 pathway in LPS‐exposed NP cells. Mechanistically, Pro‐B3 could occupy MD‐2's hydrophobic pocket exhibiting high affinity for LPS to intervene LPS/TLR4/MD‐2 complex formation. In vivo, Pro‐B3 treatment prevented the loss of gelatin NP cells and structural damage of annulus fibrosus in rat IVDD model. In brief, Pro‐B3 is considered to be a treatment agent for IVDD.

The role of estrogen in intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is a main contributor to low back and radicular pain, which imposes heavy economic burdens on society. However, the etiology and mechanism of IVDD are complex and still not completely clear. In particular, the role of estrogen in IVDD has not received much attention in recent research, although estrogen plays a crucial role in the metabolic dysfunction of others musculoskeletal structures, such as bone, muscle, and tendon. In this review, we attempt to describe the role of estrogen in IVDD and to summarize the proposed mechanisms in vivo and in vitro, as well as, to outline several interesting questions in this field.

Systemic Exposure to Lipopolysaccharide from Porphyromonas gingivalis Induces Bone Loss-Correlated Alzheimer's Disease-Like Pathologies in Middle-Aged Mice

BACKGROUND

Alzheimer's disease (AD) and bone loss are clinically exacerbated. However, the mechanism of exacerbation remains understood.

OBJECTIVE

We tested our hypothesis that periodontitis is involved in the exacerbation, contributing to AD pathologies.

METHODS

The bone, memory, and inflammation in bone and brain were examined in 12-month-old mice after systemic exposure to lipopolysaccharide from Porphyromonas gingivalis (P gLPS) for 3 consecutive weeks.

RESULTS

Compared with control mice, bone loss in tibia (26% decrease) and memory decline (47% decrease) were induced in mice with a positive correlation after exposure to P gLPS (r = 0.7378, p = 0.0011). The IL-6 and IL-17 expression in tibia was negatively correlated with the bone volume/total tissue volume (r = -0.6619, p = 0.0052; r = -0.7129, p = 0.0019), while that in the cortex was negatively correlated with the memory test latency (r = -0.7198, p = 0.0017; p = 0.0351, r = -0.5291). Furthermore, the IL-17 expression in microglia was positively correlated with Aβ42 accumulation in neurons (r = 0.8635, p < 0.0001). In cultured MG6 microglia, the P gLPS-increased IL-6 expression was inhibited by a PI3K-specific inhibitor (68% decrease), and that of IL-17 was inhibited by IL-6 antibody (41% decrease). In cultured N2a neurons, conditioned medium from P gLPS-stimulated microglia (MCM) but not P gLPS increased the productions of AβPP, CatB, and Aβ42, which were significantly inhibited by pre-treatment with IL-17 antibody (67%, 51%, and 41% decrease).

CONCLUSION

These findings demonstrated that chronic systemic exposure to P gLPS simultaneously induces inflammation-dependent bone loss and AD-like pathologies by elevating IL-6 and IL-17 from middle age, suggesting that periodontal bacteria induce exacerbation of bone loss and memory decline, resulting in AD progression.

Interleukin-17: Potential Target for Chronic Wounds

Chronic wounds exhibit persistent inflammation with markedly delayed healing. The significant burden of chronic wounds, which are often resistant to standard therapy, prompts further research on novel therapies. Since the interleukin-17 family has been implicated as a group of proinflammatory cytokines in immune-mediated diseases in the gut and connective tissue, as well as inflammatory skin conditions, we consider here if it may contribute to the pathogenesis of chronic wounds. In this review, we discuss the interleukin-17 family's signaling pathways and role in tissue repair. A PubMed review of the English literature on interleukin-17, wound healing, chronic wounds, and inflammatory skin conditions was conducted. Interleukin-17 family signaling is reviewed in the context of tissue repair, and preclinical and clinical studies examining its role in the skin and other organ systems are critically reviewed. The published work supports a pathologic role for interleukin-17 family members in chronic wounds, though this needs to be more conclusively proven. Clinical studies using monoclonal interleukin-17 antibodies to improve healing of chronic skin wounds have not yet been performed, and only a few studies have examined interleukin-17 family expression in chronic skin wounds. Furthermore, different interleukin-17 family members could be playing selective roles in the repair process. These studies suggest a therapeutic role for targeting interleukin-17A to promote wound healing; therefore, interleukin-17A may be a target worthy of pursuing in the near future.

Luteoloside Inhibits IL-1β-Induced Apoptosis and Catabolism in Nucleus Pulposus Cells and Ameliorates Intervertebral Disk Degeneration

Intervertebral disk degeneration (IDD) is the major cause of low back pain (LBP), which affects 80% of the world’s population. Interleukin 1 beta (IL-1β) is a major inflammatory factor that accelerates disk degeneration, and IL-1β levels increase in degenerative disks. It has recently been reported that luteoloside—a type of flavonoid glycoside—has anti-inflammatory properties. In the present study, we investigated the protective potential of luteoloside in IDD. We found that luteoloside maintains cell morphology and inhibits apoptosis (indicated by the reduced expression of cleaved caspase 3) in IL-1β-treated nucleus pulposus (NP) cells. It also suppresses inflammatory mediators—nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), cyclooxygenase 2 (COX-2), and inducible nitric oxide synthase (iNOS)—in IL-1β-treated NP cells. Furthermore, we found increased collagen II and aggrecan expression and reduced MMP13 and ADAMTS5 expression in luteoloside-treated NP cells in the presence of IL-1β. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is involved in apoptosis, inflammation, and extracellular matrix (ECM) homeostasis. Mechanistic studies revealed that the NF-κB signaling pathway is inhibited by luteoloside, and Nrf2 is involved in the regulation of luteoloside in NF-κB signaling because Nrf2 knockdown reduced the suppressive effect of luteoloside on NF-κB signaling. We also established a puncture-induced rat IDD model and demonstrated that the persistent intraperitoneal injection of luteoloside ameliorates the progression of IDD. In conclusion, we demonstrated that luteoloside activates the Nrf2/HO-1 signaling axis and is a potential therapeutic medicine for IDD.

Angiopoietin-like protein 8 expression and association with extracellular matrix metabolism and inflammation during intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is considered the primary culprit for low back pain. Although the underlying mechanisms remain unknown, hyperactive catabolism of the extracellular matrix (ECM) and inflammation are suggested to play critical roles in IDD progression. This study was designed to elucidate the role of angiopoietin-like protein 8 (ANGPTL8) in the progression of IDD, especially the relationship of ANGPTL8 with ECM metabolism and inflammation. A positive association between ANGPTL8 expression and degenerative grades of IDD was detected in the analysis of human nucleus pulposus tissue samples. Silencing of ANGPTL8 attenuated the degradation of the anabolic protein type collagen II, and reduced the expression of the catabolic proteins MMP3 and MMP9, and the inflammatory cytokine IL-6 through inhibition of NF-κB signalling activation. In addition, the effect of ANGPTL8 was evaluated in a rat model of puncture-induced IDD. Based on the imaging results and histological examination in animal study, knockdown of ANGPTL8 was demonstrated to ameliorate the IDD progression. These results demonstrate the detrimental role of ANGPTL8 expression in the pathogenesis of IDD and may provide a new therapeutic target for IDD treatment.

Activation of Nrf2/HO-1 signal with Myricetin for attenuating ECM degradation in human chondrocytes and ameliorating the murine osteoarthritis

BACKGROUND

Osteoarthritis (OA), one of the prevailing joint degenerative disorders, contributes to the disability around the world. However, no effective therapeutic was introduced currently. Myricetin was reported to possess the function of anti-inflammatory, anti-diabetic and anti-cancer. Thus, we investigate the protection role of myricetin in OA progression and the potential molecular mechanism in present study.

METHODS

Quantitative realtime PCR and western blotting were performed to evaluate the expression of MMP-13, Aggrecan, iNOS, and COX-2 at both gene and protein levels. An enzyme-linked immunosorbent assay was used to evaluate the levels of inflammatory factors (PGE2, TNF-α, and IL-6). The PI3K/AKT, Nrf2/HO-1 and nuclear factor kappa B (NF-κB) signaling pathways were analyzed by western blotting, and immunofluorescence was used to assess the expression of Nrf2, Collagen II and MMP13. The in vitro effect of myricetin was evaluated by intragastric administration into a mouse osteoarthritis model induced by destabilization of the medial meniscus.

RESULTS

Myricetin not only inhibited the generation of inflammatory mediators and cytokines such as nitric oxide (NO), prostaglandin E2 (PGE2), TNF-α and IL-6, but also suppressed the production of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in human chondrocytes under IL-1β stimulation. Moreover, Metalloproteinase 13 (MMP13) and thrombospondin motifs 5 (ADAMTS5), which resulted in the degradation of cartilage, were also suppressed in chondrocytes with the treatment of myricetin. To explore the potential mechanism, we found out that myricetin suppressed NF-κB signaling pathway through Nrf2/HO-1 axis in human chondrocytes. Besides, myricetin regulated the Nrf2 signaling pathway through PI3K/Akt pathway. In addition, in vivo study demonstrated that myricetin could ameliorated the progression of OA in mice DMM model through PI3K/Akt mediated Nrf2 signaling pathway.

CONCLUSION

Taken together, our data first demonstrated that myricetin possesses the therapeutic potential on OA through PI3K/Akt mediated Nrf2/HO-1 signaling pathway.

Neutralization of Interleukin-17A Attenuates Lipopolysaccharide-Induced Mastitis by Inhibiting Neutrophil Infiltration and the Inflammatory Response

Mastitis has been recognized as a common and major disease of cows with a strong impact on dairy farming. Interleukin-17A (IL-17A) has been shown to mediate crucial crosstalk between the immune system and various epithelial tissues, initiating a series of defensive mechanisms against bacterial and fungal infections. This crosstalk is especially involved in neutrophil infiltration. To evaluate the role of IL-17A in immune defense in the mammary gland in mice, we tested the effects of depleting IL-17A on changes in pathology, neutrophil infiltration, and pro-inflammatory cytokine levels in the mammary gland stimulated by lipopolysaccharide (LPS). Further, the effects of IL-17A on the activation of the nuclear factor-κB (NF-κB) signaling pathway during mastitis induced by LPS were also studied. The results showed that the production of IL-17A was significantly elevated during mastitis induced by LPS. IL-17A blockade via an intraperitoneal antibody injection protected against LPS-induced mastitis, as indicated by decreased neutrophil infiltration, myeloperoxidase activity, pro-inflammatory cytokines levels, and NF-κB signaling pathway molecule phosphorylation in response to LPS. In conclusion, an elevated IL-17 level plays a crucial role during mastitis, and anti-IL-17A antibody blockade protects against LPS-induced mammary gland inflammation induced through the NF-κB signaling pathway, which provides a new potential treatment target for mastitis.

Elevated expression of hypoxia-inducible factor-2alpha regulated catabolic factors during intervertebral disc degeneration

HEADINGS AIMS

The present study determined whether nucleus pulposus (NP) cells express hypoxia-inducible factor-2alpha (HIF-2α) and assessed its role in regulating the expression of catabolic factors during intervertebral disc degeneration.

MATERIALS AND METHODS

Human degenerated NP tissues were acquired to examine the HIF-2α expression levels using immunohistochemistry, western blotting, and Real-time PCR. Human NP cells were cultivated under normoxic or hypoxic conditions, and the HIF-2α expression was determined. Then, human NP cells were treated with HIF-2α plasmids, HIF-2α siRNA, and tumor necrosis factor-alpha (TNF-α) to evaluate the role of HIF-2α in regulating matrix metalloproteinase (MMP) and aggrecanase expression. An in vivo rabbit disc degeneration model was established to demonstrate that HIF-2α plays a critical role in disc degeneration.

KEY FINDINGS

We found that HIF-2α had a markedly elevated expression in human degenerated discs in the Grade III stage. HIF-2α protein and gene transcript levels in vitro were relatively higher under hypoxic conditions. The expression of MMP-13, ADAMTS-4 was decreased significantly in HIF-2α silencing condition, while the over-expression resulted in significantly increased levels of MMP-13 and ADAMTS-4. When cytokine TNF-α was added, HIF-2α was induced by nuclear factor-κB (NF-κB). The in vivo experiments showed that the HIF-2α controlled the catabolic factors MMP-13 and ADAMTS-4 that regulated the collagen II and aggrecan metabolism in disc degeneration.

SIGNIFICANCE

HIF-2α is a catabolic regulator in disc degeneration and directly controls the catabolic genes. The suppression of HIF-2α expression leads to decelerates extracellular matrix degradation that might represent a therapeutic target for the degenerative disc.

Alpha 2-Macroglobulin as Dual Regulator for Both Anabolism and Catabolism in the Cartilaginous Endplate of Intervertebral Disc

STUDY DESIGN

Basic science study.

OBJECTIVE

To illustrate supplemental alpha-2 macroglobulin (α2 M) has beneficial effects on cartilaginous endplates (CEPs) that may slow the progression of intervertebral disc (IVD) degeneration.

SUMMARY OF BACKGROUND DATA

CEPs play a vital role in progression of intervertebral disc degenerative diseases. However, the ideal and economic therapies for CEPs degeneration are still urgently required.

METHODS

Firstly, we confirmed degenerative CEP characters by H&E and Safranin O fast green staining and detected increasing level of α2 M and matrix metalloproteinase 13(MMP-13) in degenerative CEP by immunohistochemistry. Then, effects of exogenous α2 M on tumor necrosis factor alpha (TNF-α)-induced CEP catabolic enzyme and anabolic molecules were evaluated by qRT-PCR, Western blotting and ELISA in cultured CEP cells obtained from rats. Furthermore, suppression of α2 M on TNF-α-induced activation of NF-кB signaling pathway was measured by Western blotting and immunofluorescence. In addition, function of α2 M on TNF-α-treated ex vivo IVDs from rats lumbar IVDs was estimated by measuring the expression of MMP-13, Sox9, aggrecan, and type II collagen in CEP area.

RESULTS

Compared with normal CEP, level of α2 M was slightly increased in CEP from degenerative patients, whereas MMP-13 was sharply elevated. In vitro, α2 M inhibited expression and activity of MMP-3 or MMP-13 in a dose-dependent manner in rat CEP cells stimulated by TNF-α. The α2 M refrained phosphorylation of IκBα and inhibited nuclear translocation of p65. Finally, supplemental α2 M reduced expression of MMP-13, and promoted expression of Sox9, aggrecan, and type II collagen in CEP area of ex vivo IVDs cultured with TNF-α.

CONCLUSION

α2 M is not sufficiently produced to inactivate higher concentrations of catabolic factor MMP-13 found in the degenerated CEP. Supplemental α2 M protects against the progression of IVD degeneration by inhibiting effects of proinflammatory cytokines.

LEVEL OF EVIDENCE

N/A.

Potential therapeutic role of Co-Q10 in alleviating intervertebral disc degeneration and suppressing IL-1β-mediated inflammatory reaction in NP cells

Coenzyme Q10 (Co-Q10) is extraordinarily popular and has been used in abundant interventions as an antioxidant reagent that participates in numerous oxidation reactions. According to substantial evidence previously reported, interleukin-1β (IL-1β) is deemed to be one of the chief orchestrator molecules in the degeneration of intervertebral disc (IVD). However, it is unknown whether Co-Q10 is able to protect against IVD degeneration. In the current study, mouse-derived IVDs as well as primary human nucleus pulposus (NP) cells were isolated and cultured. NP cells were stimulated with IL-1β, with or without selective addition of Co-Q10 to investigate the therapeutic effect of Co-Q10 on IVD degeneration. Levels of IL-1β-induced inflammatory biomarkers including TNF-α, COX-2, IL-6 and iNOS were reduced by Co-Q10, which was possibly associated with inhibition of NF-κB signaling activation. Furthermore, Co-Q10 maintained the production of anabolic biomarkers in NP cells such as collagen 2, aggrecan and Sox-9 and altered the enhanced catabolism induced by IL-1β. Moreover, the therapeutic role of Co-Q10 in sustaining IVD tissue-enhanced anabolism is potentially dependent on activation of the Akt signaling pathway. In summary, Co-Q10 may potentially represent an available molecular target that may shed light on approaches to the prevention and treatment of IVD degeneration in the future.

TSG-6 secreted by bone marrow mesenchymal stem cells attenuates intervertebral disc degeneration by inhibiting the TLR2/NF-κB signaling pathway

Inflammation has been correlated with intervertebral disc degeneration (IDD). Recent evidence suggests that TNF-α-stimulated gene 6 protein (TSG-6) secreted by bone marrow mesenchymal stem cells (BMSCs) displays a remarkable ability to inhibit inflammatory processes in a variety of diseases. However, it is unknown whether BMSCs exert their therapeutic effect against IDD by secreting TSG-6. Here we investigated the effects of BMSCs and TSG-6 on IDD and explored the possible underlying mechanisms in vitro and in vivo. We found that BMSCs and TSG-6 reduced the expression of MMP-3 and MMP-13, and increased the expression of collagen II and aggrecan in the IL-1β-treated nucleus pulposus cells (NPCs), but the protective effects of BMSCs and TSG-6 were attenuated when TSG-6 expression was silenced. We also found that the activation of the TLR2/NF-κB pathway was inhibited by BMSCs and TSG-6. The levels of IL-6 and TNF-α in the degenerated NPCs were reduced and the proliferation of IL-1β-treated NPCs was increased in the presence of BMSCs and TSG-6. Furthermore, in vivo experiments showed that BMSCs and TSG-6 restored the MRI T2-weighted signal intensity and increased collagen II and aggrecan expression in the degenerated nucleus pulposus (NP) tissues. Finally, our results showed that BMSCs and TSG-6 downregulated the TLR2/NF-κB signaling and reduced the expression of MMPs and inflammatory cytokines in the degenerated NP tissues. The present study is the first to demonstrate the involvement of TLR2/NF-κB pathway in the potential anti-IDD therapeutic effect of TSG-6, and the results provide new insight into the beneficial effect of BMSCs in the treatment of IDD.

JMJD6 exerts function in neuropathic pain by regulating NF‑κB following peripheral nerve injury in rats

Treatment of neuropathic pain (NPP) continues to be a major challenge, and the underlying mechanisms remain to be elucidated. Previous studies have demonstrated that histone methylation is important in synaptic plasticity of the nervous system and may affect nuclear factor‑κB (NF‑κB) signaling through epigenetic mechanisms. The present study aimed to investigate the role of Jumonji C domain 6 (JMJD6), a histone demethylase, in a chronic constriction injury (CCI) model of NPP. On the third day post‑CCI surgery, a JMJD6 overexpressing lentiviral vector (LV‑JMJD6) was intrathecally injected in the rats. Mechanical withdrawal threshold and thermal withdrawal latency were assessed prior surgery and on days 3, 7, 10 and 14 post‑CCI. The results showed that intrathecal injection with the LV‑JMJD6 attenuated CCI‑induced pain facilitation. The expression of JMJD6 was lower following CCI surgery, and its expression was significantly increased following intrathecal injection with LV‑JMJD6, compared with levels in normal saline (NS)‑ and negative control lentiviral vector (NC)‑treated rats. The expression of spinal NF‑κB phosphorylated (p‑)p65 subunit and its downstream pain‑associated effectors, including interleukin 1β (IL‑1β), tumor necrosis factor‑α (TNF‑α) and vascular endothelial growth factor (VEGF), were increased following CCI surgery. Intrathecal injection with LV‑JMJD6 suppressed activation of the p‑p65 subunit in CCI rats. In addition, expression levels of its downstream effectors IL‑1β, TNF‑α and VEGF were attenuated by intrathecal treatment with LV‑JMJD6, compared with those in the NS‑ and NC‑treated CCI rats. Furthermore, the JMJD6‑ and p65‑immunoreactive cells overlapped in the spinal dorsal horn, however, co‑immunoprecipitation showed that JMJD6 and the NF‑κB p65 subunit did not directly interact, indicating other functional connections may exist between these factors following CCI surgery. Collectively, these findings indicated an important mechanism underlying the pathogenesis of NPP. JMJD6 may exert its therapeutic function in NPP by regulating NF‑κB following CCI.

Simvastatin Inhibits IL-1β-Induced Apoptosis and Extracellular Matrix Degradation by Suppressing the NF-kB and MAPK Pathways in Nucleus Pulposus Cells

Statins are widely used hypocholesterolemic drugs that block the mevalonate pathway. Some studies have shown that statins may have the potential to inhibit intervertebral disk (IVD) degeneration (IDD). Interleukin (IL)-1β, a catabolic cytokine, is a key regulator of IDD. This study aimed to investigate the mechanism underlying the effect of simvastatin on IDD. The viability of nucleus pulposus (NP) cells was determined by the methyl-thiazolyl-tetrazolium (MTT) assay. The apoptosis of NP cells was measured by flow cytometric analysis, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and western blotting of relevant apoptotic proteins. The protein levels of catabolic factors and anabolic factors were determined by western blotting. The cells were stimulated with IL-1β in the absence or presence of simvastatin to investigate the effects on matrix metalloproteinase (MMP)-3, MMP-13, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-4, ADAMTS-5, type II collagen, and aggrecan expression. Our findings indicate that simvastatin considerably inhibited IL-1β-induced apoptosis in NP cells. We also found that simvastatin attenuated IL-1β-induced expression and MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5 activities and also reduced the decrease in type II collagen and aggrecan expression. In addition, simvastatin considerably suppressed the nuclear translocation and activation of nuclear factor-kappa B (NF-KB) by inhibiting p65 phosphorylation and translocation and blocking inhibitor kB-α degradation. It also inhibited MAPK pathway activation by blocking c-Jun N-terminal kinase (JNK), p38, and ERK phosphorylation. The results of our study revealed that simvastatin is a potential agent for IDD prevention and treatment.

Hierarchical, imbalanced pro-inflammatory cytokine networks govern the pathogenesis of chronic arthropathies

BACKGROUND

Chronic inflammatory arthropathies, such as rheumatoid arthritis (RA), spondyloarthritis, including psoriatic arthritis (PsA), ankylosing spondyloarthritis (AS), osteoarthritis (OA), and intervertebral disc degenerative disease (DDD) constitute major public health problems that are anticipated to grow significantly as the human population ages. However, many aspects concerning the molecular mechanisms underlying their onset and progression remain unclear.

DESIGN

This narrative review critically analyzes the molecular mechanisms underlying the inflammation-associated pathogenesis of the aforementioned joint diseases. This includes, in particular, the major role played by several key soluble factors (such as cytokines and the associated signaling pathways, designated as "fragile nodes") produced by local cells and recruited to the joints' immune cells, whose elimination by specific drugs has dramatically improved the diseases' symptomatology and outcome in human clinical trials or in rodent arthritis models.

HYPOTHESIS AND THE AIM OF THIS REVIEW

We hypothesize that the pathogenesis of chronic inflammatory arthropathies is governed by hierarchical, imbalanced pro-inflammatory cytokine networks (HIPICNs) (comprising a combination of fragile nodes) that are created during the development of both autoimmune (RA, PsA, and AS) and non-autoimmune (OA and DDD) disorders. The main aim of this review is to provide evidence that despite substantial pathobiological differences between these arthropathies, the HIPICNs created are quite common, thus justifying the merging of these disorders mechanistically and suggesting that these common mechanisms exist in the onset and progression of different joint diseases.