Inflammatory cytokines induce caveolin-1/β-catenin signalling in rat nucleus pulposus cell apoptosis through the p38 MAPK pathway

POSTN knockdown suppresses IL-1β-induced inflammation and apoptosis of nucleus pulposus cells via inhibiting the NF-κB pathway and alleviates intervertebral disc degeneration

The aim of this study is to investigate the effects of POSTN on IL-1β induced inflammation, apoptosis, NF-κB pathway and intervertebral disc degeneration (IVDD) in Nucleus pulposus (NP) cells (NPCs). NP tissue samples with different Pfirrmann grades were collected from patients with different degrees of IVDD. Western blot and immunohistochemical staining were used to compare the expression of POSTN protein in NP tissues. Using the IL-1β-induced IVDD model, NPCs were transfected with lentivirus-coated si-POSTN to down-regulate the expression of POSTN and treated with CU-T12-9 to evaluate the involvement of NF-κB pathway. Western blot, immunofluorescence, and TUNEL staining were used to detect the expression changes of inflammation, apoptosis and NF-κB pathway-related proteins in NPCs. To investigate the role of POSTN in vivo, a rat IVDD model was established by needle puncture of the intervertebral disc. Rats were injected with lentivirus-coated si-POSTN, and H&E staining and immunohistochemical staining were performed. POSTN expression is positively correlated with the severity of IVDD in human. POSTN expression was significantly increased in the IL-1β-induced NPCs degeneration model. Downregulation of POSTN protects NPCs from IL-1β-induced inflammation and apoptosis. CU-T12-9 treatment reversed the protective effect of si-POSTN on NPCs. Furthermore, lentivirus-coated si-POSTN injection partially reversed NP tissue damage in the IVDD model in vivo. POSTN knockdown reduces inflammation and apoptosis of NPCs by inhibiting NF-κB pathway, and ultimately prevents IVDD. Therefore, POSTN may be an effective target for the treatment of IVDD.

Stress-Activated Protein Kinases in Intervertebral Disc Degeneration: Unraveling the Impact of JNK and p38 MAPK

Intervertebral disc degeneration (IDD) is a major cause of lower back pain. The pathophysiological development of IDD is closely related to the stimulation of various stressors, including proinflammatory cytokines, abnormal mechanical stress, oxidative stress, metabolic abnormalities, and DNA damage, among others. These factors prevent normal intervertebral disc (IVD) development, reduce the number of IVD cells, and induce senescence and apoptosis. Stress-activated protein kinases (SAPKs), particularly, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK), control cell signaling in response to cellular stress. Previous studies have shown that these proteins are highly expressed in degenerated IVD tissues and are involved in complex biological signal-regulated processes. Therefore, we summarize the research reports on IDD related to JNK and p38 MAPK. Their structure, function, and signal regulation mechanisms are comprehensively and systematically described and potential therapeutic targets are proposed. This work could provide a reference for future research and help improve molecular therapeutic strategies for IDD.

Comparative Analysis of Autophagy and Apoptosis in Disc Degeneration: Understanding the Dynamics of Temporary-Compression-Induced Early Autophagy and Sustained-Compression-Triggered Apoptosis

The purpose of this study was to investigate the initiation of autophagy activation and apoptosis in nucleus pulposus cells under temporary compression (TC) and sustained compression (SC) to identify ideal research approaches in intervertebral disc degeneration. Various techniques were used: radiography (X-ray), magnetic resonance imaging (MRI), transmission electron microscope (TEM), H&E staining, Masson's trichrome staining, immunohistochemistry (IHC) (LC3, beclin-1, and cleaved caspase-3), and real-time polymerase chain reaction (RT-qPCR) for autophagy-related (beclin-1, LC3, and P62) and apoptosis-related (caspase-3 and PARP) gene expression analysis. X-ray and MRI revealed varying degrees of disc degeneration, ranging from moderate to severe in both groups. The severity was directly linked to compression duration, with SC resulting in notably severe central NP cell degeneration. Surprisingly, TC also caused similar, though less severe, degeneration. Elevated expression of LC3 and beclin-1 was identified after 6 weeks, but it notably declined after 12 weeks. Central NP cells in both groups exhibited increased expression of cleaved caspase-3 that was positively correlated with the duration of SC. TC showed fewer apoptotic markers compared to SC. LC3, beclin-1, and P62 mRNA expression peaked after 6 weeks and declined after 12 weeks in both groups. Cleaved caspase-3 and PARP expression peaked in SC, positively correlating with longer compression duration, while TC showed lower levels of apoptosis gene expression. Furthermore, TEM results revealed different events of the autophagic degradation process after 2 weeks of compression. TCmay be ideal for studying early triggered autophagy-mediated degeneration, while SC may be ideal for studying late or slower-triggered apoptosis-mediated degeneration.

Unraveling the mechanisms of intervertebral disc degeneration: an exploration of the p38 MAPK signaling pathway

Intervertebral disc (IVD) degeneration (IDD) is a worldwide spinal degenerative disease. Low back pain (LBP) is frequently caused by a variety of conditions brought on by IDD, including IVD herniation and spinal stenosis, etc. These conditions bring substantial physical and psychological pressure and economic burden to patients. IDD is closely tied with the structural or functional changes of the IVD tissue and can be caused by various complex factors like senescence, genetics, and trauma. The IVD dysfunction and structural changes can result from extracellular matrix (ECM) degradation, differentiation, inflammation, oxidative stress, mechanical stress, and senescence of IVD cells. At present, the treatment of IDD is basically to alleviate the symptoms, but not from the pathophysiological changes of IVD. Interestingly, the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway is involved in many processes of IDD, including inflammation, ECM degradation, apoptosis, senescence, proliferation, oxidative stress, and autophagy. These activities in degenerated IVD tissue are closely relevant to the development trend of IDD. Hence, the p38 MAPK signaling pathway may be a fitting curative target for IDD. In order to better understand the pathophysiological alterations of the intervertebral disc tissue during IDD and offer potential paths for targeted treatments for intervertebral disc degeneration, this article reviews the purpose of the p38 MAPK signaling pathway in IDD.

New trends in non-pharmacological approaches for cardiovascular disease: Therapeutic ultrasound

Significant advances in application of therapeutic ultrasound have been reported in the past decades. Therapeutic ultrasound is an emerging non-invasive stimulation technique. This approach has shown high potential for treatment of various disease including cardiovascular disease. In this review, application principle and significance of the basic parameters of therapeutic ultrasound are summarized. The effects of therapeutic ultrasound in myocardial ischemia, heart failure, myocarditis, arrhythmias, and hypertension are explored, with key focus on the underlying mechanism. Further, the limitations and challenges of ultrasound therapy on clinical translation are evaluated to promote application of the novel strategy in cardiovascular diseases.

Pan-cancer analysis of the intervertebral-disc-degeneration-related innate immunity gene NAIP

BACKGROUND

Intervertebral disc degeneration (IDD) is a progressive chronic condition that commonly causes low back pain. Cancer is among the primary reasons for deaths worldwide. Our purpose was to identify the characteristic genes of IDD and explore the potential association between IDD and cancer.

METHODS

Immune cell infiltration and differentially expressed analysis were conducted utilizing data from the GSE124272 database. Enrichment analysis of differentially expressed genes (DEGs) was performed to explore the possible mechanisms underlying IDD development. Moreover, weighted gene correlation network analysis (WGCNA) was applied to select IDD-related hub genes. The immune-related key genes were determined by intersecting DEGs, IDD-related hub genes, and immune genes. Subsequently, machine learning models based on these genes were built to identify and verify the characteristic genes. RNA sequencing and clinical data of 33 carcinoma categories were obtained from the Cancer Genome Atlas (TCGA). The association between NAIP expression and prognosis was calculated using the Kaplan-Meier analysis. To gain a deeper understanding of the impact of NAIP in tumor immunotherapy, the association between NAIP and immune infiltration and two immunotherapeutic biomarkers were explored. Ultimately, the association between NAIP and immunotherapeutic response was investigated utilizing two independent cohorts.

RESULTS

NAIP was identified as an immune-related characteristic gene between IDD and normal intervertebral disc tissue. In certain carcinoma categories, NAIP expression levels were elevated (4/33) and significantly correlated to the respective tumor stage (4/21). Survival analysis revealed that the expression levels of NAIP have prognostic significance in different cancer types. Generally, NAIP presented a strong association with immune cell infiltration and modulators. NAIP may influence immunotherapy effects through tumor mutational burden and microsatellite instability. No remarkable association between NAIP and immunotherapy response was found in either cohort.

CONCLUSION

Our study is the first to identify NAIP as an immune-related characteristic gene. Pan-cancer analysis revealed that NAIP could serve as a novel clinical prognostic marker and therapeutic target for a variety of carcinoma categories, reducing the risk of IDD in tumor patients.

Roles of p38 MAPK signalling in intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is a common degenerative disease mediated by multiple factors. Because of its complex aetiology and pathology, no specific molecular mechanisms have yet been identified and no definitive treatments are currently available for IVDD. p38 mitogen-activated protein kinase (MAPK) signalling, part of the serine and threonine (Ser/Thr) protein kinases family, is associated with the progression of IVDD, by mediating the inflammatory response, increasing extracellular matrix (ECM) degradation, promoting cell apoptosis and senescence and suppressing cell proliferation and autophagy. Meanwhile, the inhibition of p38 MAPK signalling has a significant effect on IVDD treatment. In this review, we first summarize the regulation of p38 MAPK signalling and then highlight the changes in the expression of p38 MAPK signalling and their impact on pathological process of IVDD. Moreover, we discuss the current applications and future prospects of p38 MAPK as a therapeutic target for IVDD treatment.

Exosomes derived from miR-338-3p-modified adipose stem cells inhibited inflammation injury of chondrocytes via targeting RUNX2 in osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a chronic degenerative disease that is one of the main causes of disability in middle-aged and elderly people. Adipose stem cell (ASC)-derived exosomes (ASC-Exo) could repair cartilage damage and treat OA. MiRNA-338-3p expression was confirmed to play a role in inhibiting proinflammatory cytokines. Herein, we aimed to explore the mechanism by which exosomes derived from miR-338-3p overexpressing ASCs protects chondrocytes from interleukin (IL)-1β-induced chondrocyte change.

METHODS

Exosomes were extracted from ASCs transfected with miR-338-3p or its antisense inhibitor. The ASC-Exos (miR-338-3p silencing/overexpression) were incubated with IL-1β-induced ATDC5 cells, followed by evaluation of the chondrocyte proliferation, degradation, and inflammation injury.

RESULTS

In vitro results revealed that ASC-Exos inhibited the expression of prostaglandin E2 (PGE2), IL-6, IL-1β, and TNF-α, as well as promoted the proliferation of ATDC5 cells. Moreover, ASC-Exos inhibited inflammation injury and degradation of ATDC5 cells by transferring miR-338-3p. Luciferase reporter assays showed that RUNX2 was a target gene of miR-338-3p. Additionally, RUNX2 overexpression in ATDC5 cells reversed the protective effect of miR-338-3p on chondrocytes. Taken together, this study demonstrated that exosomes secreted from miR-338-3p-modified ASCs were effective in the repair of IL-1β-induced chondrocyte change by inhibiting RUNX2 expression.

CONCLUSIONS

Our result provided valuable data for understanding the mechanism of ASC-Exos in OA treatment.

Periostin promotes nucleus pulposus cells apoptosis by activating the Wnt/β-catenin signaling pathway

Intervertebral disc (IVD) degeneration (IVDD) is closely linked to degenerative spinal disease, resulting in disability, poor quality of life, and financial burden. Apoptosis of nucleus pulposus (NP) cells (NPCs) is a key pathological basis of IVDD. Periostin (POSTN), an extracellular matrix protein, is expressed in many tissues, whereas its abnormal expression is associated with IVDD. The conventional Wnt/β-catenin pathway is also involved in IVDD and contributes to NPCs apoptosis. However, research on the mechanisms of POSTN in IVDD is lacking. This study investigated the relationship between POSTN and β-catenin expression in degenerated IVDs. We detected the expression of POSTN, β-catenin, and cleaved-caspase-3 (C-caspase3) in degenerated and non-degenerated IVD tissues of different grades (n = 8) using RT-qPCR, immunohistochemical staining, and western blotting analysis. Next, we explored the effects of recombinant periostin (rPOSTN) and isoquercitrin (Iso), an inhibitor of the Wnt/β-catenin pathway, on NPCs apoptosis. Finally, we inhibited the expression of POSTN in degenerated NPCs in vivo and investigated the anti-apoptotic effect. The expression of β-catenin, POSTN, and C-caspase3 in severe degenerative IVDs was significantly higher than that in mild degenerative IVDs. These findings were confirmed in rat and cell-based degenerative models. When treated with rPOSTN, the Wnt/β-catenin pathway activity and cell apoptosis were time- and dose-dependent. However, rPOSTN-induced NPCs apoptosis decreased after iso-induced inhibition of the Wnt/β-catenin pathway. POSTN inhibition reduced apoptosis but was restored by rPOSTN re-addition. Lastly, POSTN inhibition ameliorated puncture-induced IVDD in vivo. Overall, our study demonstrated that POSTN promotes NPCs apoptosis and aggravates degeneration by activating the Wnt/β-catenin pathway.

Cell-penetrating peptide-mediated delivery of therapeutic peptides/proteins to manage the diseases involving oxidative stress, inflammatory response and apoptosis

OBJECTIVES

Peptides and proteins represent great potential for modulating various cellular processes including oxidative stress, inflammatory response, apoptosis and consequently the treatment of related diseases. However, their therapeutic effects are limited by their inability to cross cellular barriers. Cell-penetrating peptides (CPPs), which can transport cargoes into the cell, could resolve this issue, as would be discussed in this review.

KEY FINDINGS

CPPs have been successfully exploited in vitro and in vivo for peptide/protein delivery to treat a wide range of diseases involving oxidative stress, inflammatory processes and apoptosis. Their in vivo applications are still limited due to some fundamental issues of CPPs, including nonspecificity, proteolytic instability, potential toxicity and immunogenicity.

SUMMARY

Totally, CPPs could potentially help to manage the diseases involving oxidative stress, inflammatory response and apoptosis by delivering peptides/proteins that could selectively reach proper intracellular targets. More studies to overcome related CPP limitations and confirm the efficacy and safety of this strategy are needed before their clinical usage.

New Progress in Basic Research of Macrophages in the Pathogenesis and Treatment of Low Back Pain

Low back pain (LBP) is quite common in clinical practice, which can lead to long-term bed rest or even disability. It is a worldwide health problem remains to be solved. LBP can be induced or exacerbated by abnormal structure and function of spinal tissue such as intervertebral disc (IVD), dorsal root ganglion (DRG) and muscle; IVD degeneration (IVDD) is considered as the most important among all the pathogenic factors. Inflammation, immune response, mechanical load, and hypoxia etc., can induce LBP by affecting the spinal tissue, among which inflammation and immune response are the key link. Inflammation and immune response play a double-edged sword role in LBP. As the main phagocytic cells in the body, macrophages are closely related to body homeostasis and various diseases. Recent studies have shown that macrophages are the only inflammatory cells that can penetrate the closed nucleus pulposus, expressed in various structures of the IVD, and the number is positively correlated with the degree of IVDD. Moreover, macrophages play a phagocytosis role or regulate the metabolism of DRG and muscle tissues through neuro-immune mechanism, while the imbalance of macrophages polarization will lead to more inflammatory factors to chemotaxis and aggregation, forming an “inflammatory waterfall” effect similar to “positive feedback,” which greatly aggravates LBP. Regulation of macrophages migration and polarization, inhibition of inflammation and continuous activation of immune response by molecular biological technology can markedly improve the inflammatory microenvironment, and thus effectively prevent and treat LBP. Studies on macrophages and LBP were mainly focused in the last 3–5 years, attracting more and more scholars’ attention. This paper summarizes the new research progress of macrophages in the pathogenesis and treatment of LBP, aiming to provide an important clinical prevention and treatment strategy for LBP.

Caveolin-1 Regulation and Function in Mouse Uterus during Early Pregnancy and under Human In Vitro Decidualization

Decidualization is essential to rodent and primate pregnancy. Senescence is increased during decidualization. Failure of senescence clearance during decidualization will cause pregnancy abnormality. Caveolin-1 is located in plasmalemmal caveolae and involved in senescence. However, whether caveolin-1 is involved in decidualization remains undefined. In this study, we examined the expression, regulation and function of Caveolin-1 during mouse early pregnancy and under mouse and human in vitro decidualization. From days 1 to 8 of pregnancy, Caveolin-1 signals are mainly located in endothelium and myometrium. Estrogen stimulates Caveolin-1 expression in endothelium. Deficiency of estrogen receptor α significantly promotes Caveolin-1 level in uterine stromal cells. Progesterone upregulates Caveolin-1 expression in luminal epithelium. During mouse in vitro decidualization, Caveolin-1 is significantly increased. However, Caveolin-1 is obviously decreased during human in vitro decidualization. Caveolin-1 overexpression and siRNA suppress and upregulate IGFBP1 expression under in vitro decidualization, respectively. Blastocysts-derived tumor necrosis factor α (TNFα) and human Chorionic Gonadotropin (hCG) regulate Caveolin-1 in mouse and human decidual cells, respectively. Caveolin-1 levels are also regulated by high glucose and insulin. In conclusion, a low level of Caveolin-1 should be beneficial for human decidualization.

Identification of IL-6 as a potential mediator of the myocardial fibrosis that occurs in response to surgery with cardiopulmonary bypass in children with Tetralogy of Fallot

BACKGROUND

Tetralogy of Fallot is a common CHD. Studies have shown a close link between heart failure and myocardial fibrosis. Interleukin-6 has been suggested to be a post-independent factor of heart failure. This study aimed to explore the relationship between IL-6 and myocardial fibrosis during cardiopulmonary bypass.

MATERIAL AND METHODS

We downloaded the expression profile dataset GSE132176 from Gene Expression Omnibus. After normalising the raw data, Gene Set Enrichment Analysis and differential gene expression analysis were performed using R. Further, a weighted gene correlation network analysis and a protein-protein interaction network analysis were used to identify HUB genes. Finally, we downloaded single-cell expression data for HUB genes using PanglaoDB.

RESULTS

There were 119 differentially expressed genes in right atrium tissues comparing the post-CPB group with the pre-CPB group. IL-6 was found to be significantly up-regulated in the post-CPB group. Six genes (JUN, FOS, ATF3, EGR1, IL-6, and PTGS2) were identified as HUB genes by a weighted gene correlation network analysis and a protein-protein interaction network analysis. Gene Set Enrichment Analysis showed that IL-6 affects the myocardium during CPB mainly through the JAK/STAT signalling pathway. Finally, we used PanglaoDB data to analyse the single-cell expression of the HUB genes.

CONCLUSION

Our findings suggest that high expression of IL-6 and the activation of the JAK/STAT signalling pathway during CPB maybe the potential mechanism of myocardial fibrosis. We speculate that the high expression of IL-6 might be an important factor leading to heart failure after ToF surgery. We expect that these findings will provide a basis for the development of targeted drugs.

Targeting Cell Death: Pyroptosis, Ferroptosis, Apoptosis and Necroptosis in Osteoarthritis

New research has shown that the development of osteoarthritis (OA) is regulated by different mechanisms of cell death and types of cytokines. Therefore, elucidating the mechanism of action among various cytokines, cell death processes and OA is important towards better understanding the pathogenesis and progression of the disease. This paper reviews the pathogenesis of OA in relation to different types of cytokine-triggered cell death. We describe the cell morphological features and molecular mechanisms of pyroptosis, apoptosis, necroptosis, and ferroptosis, and summarize the current research findings defining the molecular mechanisms of action between different cell death types and OA.

Effect of lentivirus-mediated growth and differentiation factor-5 transfection on differentiation of rabbit nucleus pulposus mesenchymal stem cells

Background

Intervertebral disc degeneration (IDD) is a natural progression of age-related processes. Associated with IDD, degenerative disc disease (DDD) is a pathologic condition implicated as a major cause of chronic lower back pain, which can have a severe impact on the quality of life of patients. As degeneration progression is associated with elevated levels of inflammatory cytokines, enhanced aggrecan and collagen degradation, and changes in the disc cell phenotype. The purpose of this study was to investigate the biological and cytological characteristics of rabbit nucleus pulposus mesenchymal stem cells (NPMSCs)—a key factor in IDD—and to determine the effect of the growth and differentiation factor-5 (GDF5) on the differentiation of rabbit NPMSCs transduced with a lentivirus vector.

Methods

An in vitro culture model of rabbit NPMSCs was established and NPMSCs were identified by flow cytometry (FCM) and quantitative real-time PCR (qRT-PCR). Subsequently, NPMSCs were randomly divided into three groups: a transfection group (the lentiviral vector carrying GDF5 gene used to transfect NPMSCs); a control virus group (the NPMSCs transfected with an ordinary lentiviral vector); and a normal group (the NPMSCs alone). FCM, qRT-PCR, and western blot (WB) were used to detect the changes in NPMSCs.

Results

The GDF5-transfected NPMSCs displayed an elongated shape, with decreased cell density, and significantly increased GDF5 positivity rate in the transfected group compared to the other two groups (P < 0.01). The mRNA levels of Krt8, Krt18, and Krt19 in the transfected group were significantly higher in comparison with the other two groups (P < 0.01), and the WB results were consistent with that of qRT-PCR.

Conclusions

GDF5 could induce the differentiation of NPMSCs. The lentiviral vector carrying the GDF5 gene could be integrated into the chromosome genome of NPMSCs and promoted differentiation of NPMSCs into nucleus pulposus cells. Our findings advance the development of feasible and effective therapies for IDD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-021-00624-5.

Identification of Characteristic Genes in Whole Blood of Intervertebral Disc Degeneration Patients by Weighted Gene Coexpression Network Analysis (WGCNA)

Intervertebral disc degeneration (IDD) is a major cause of lower back pain. However, to date, the molecular mechanism of the IDD remains unclear. Gene expression profiles and clinical traits were downloaded from the Gene Expression Omnibus (GEO) database. Firstly, weighted gene coexpression network analysis (WGCNA) was used to screen IDD-related genes. Moreover, least absolute shrinkage and selection operator (LASSO) logistic regression and support vector machine (SVM) algorithms were used to identify characteristic genes. Furthermore, we further investigated the immune landscape by the Cell-type Identification By Estimating Relative Subsets Of RNA Transcripts (CIBERSORT) algorithm and the correlations between key characteristic genes and infiltrating immune cells. Finally, a competing endogenous RNA (ceRNA) network was established to show the regulatory mechanisms of characteristic genes. A total of 2458 genes were identified by WGCNA, and 48 of them were disordered. After overlapping the genes obtained by LASSO and SVM-RFE algorithms, genes including LINC01347, ASAP1-IT1, lnc-SEPT7L-1, B3GNT8, CHRNB3, CLEC4F, LOC102724000, SERINC2, and LOC102723649 were identified as characteristic genes of IDD. Moreover, differential analysis further identified ASAP1-IT1 and SERINC2 as key characteristic genes. Furthermore, we found that the expression of both ASAP1-IT1 and SERINC2 was related to the proportions of T cells gamma delta and Neutrophils. Finally, a ceRNA network was established to show the regulatory mechanisms of ASAP1-IT1 and SERINC2. In conclusion, the present study identified ASAP1-IT1 and SERINC2 as the key characteristic genes of IDD through integrative bioinformatic analyses, which may contribute to the diagnosis and treatment of IDD.

Low-intensity pulsed ultrasound ameliorates angiotensin II-induced cardiac fibrosis by alleviating inflammation via a caveolin-1-dependent pathway

OBJECTIVES

Cardiac hypertrophy and fibrosis are major pathological manifestations observed in left ventricular remodeling induced by angiotensin II (AngII). Low-intensity pulsed ultrasound (LIPUS) has been reported to ameliorate cardiac dysfunction and myocardial fibrosis in myocardial infarction (MI) through mechano-transduction and its downstream pathways. In this study, we aimed to investigate whether LIPUS could exert a protective effect by ameliorating AngII-induced cardiac hypertrophy and fibrosis and if so, to further elucidate the underlying molecular mechanisms.

METHODS

We used AngII to mimic animal and cell culture models of cardiac hypertrophy and fibrosis. LIPUS irradiation was applied in vivo for 20 min every 2 d from one week before mini-pump implantation to four weeks after mini-pump implantation, and in vitro for 20 min on each of two occasions 6 h apart. Cardiac hypertrophy and fibrosis levels were then evaluated by echocardiographic, histopathological, and molecular biological methods.

RESULTS

Our results showed that LIPUS could ameliorate left ventricular remodeling in vivo and cardiac fibrosis in vitro by reducing AngII-induced release of inflammatory cytokines, but the protective effects on cardiac hypertrophy were limited in vitro. Given that LIPUS increased the expression of caveolin-1 in response to mechanical stimulation, we inhibited caveolin-1 activity with pyrazolopyrimidine 2 (pp2) in vivo and in vitro. LIPUS-induced downregulation of inflammation was reversed and the anti-fibrotic effects of LIPUS were absent.

CONCLUSIONS

These results indicated that LIPUS could ameliorate AngII-induced cardiac fibrosis by alleviating inflammation via a caveolin-1-dependent pathway, providing new insights for the development of novel therapeutic apparatus in clinical practice.

Notoginsenoside R1 suppresses inflammatory response and the pyroptosis of nucleus pulposus cells via inactivating NF-κB/NLRP3 pathways

Intervertebral disc degeneration (IVDD) is the main cause of low back pain. Notoginsenoside R1 (NR1) is widely applied in the treatment of bone disorders, including IVDD. The present study aimed to investigate the effects of NR1 on the development of IVDD and the potential mechanisms. AF puncture was performed to establish IVDD rat model. Histology changes were analyzed by hematoxylin and eosin (H&E) staining. mRNA expressions were determined using qRT-PCR. Protein expressions were detected with western blot. Cellular functions were detected by MTT, EdU, flow cytometry, and TUNEL assays. The results showed that NR1 suppressed AF puncture induced IVDD, restored intervertebral disc (IVD) function, and suppressed mechanical hyperalgesia and thermal hyperalgesia. Moreover, NR1 promoted the release of extracellular matrix (ECM) in vivo and in vitro, and decreased the mRNA expressions of proinflammation cytokines. Additionally, NR1 inactivated NF-κB/NLRP3 pathways, improved cellular functions of nucleus pulposus cells (NPCs), and suppressed cell pyroptosis, which was reversed by NLRP3 activation. Taken together, NR1 may protect against IVDD via suppressing NF-κB/NLRP3 pathways. This may provide a novel therapy for IVDD.

Proper animal experimental designs for preclinical research of biomaterials for intervertebral disc regeneration

Low back pain is a vital musculoskeletal disease that impairs life quality, leads to disability and imposes heavy economic burden on the society, while it is greatly attributed to intervertebral disc degeneration (IDD). However, the existing treatments, such as medicines, chiropractic adjustments and surgery, cannot achieve ideal disc regeneration. Therefore, advanced bioactive therapies are implemented, including stem cells delivery, bioreagents administration, and implantation of biomaterials etc. Among these researches, few reported unsatisfying regenerative outcomes. However, these advanced therapies have barely achieved successful clinical translation. The main reason for the inconsistency between satisfying preclinical results and poor clinical translation may largely rely on the animal models that cannot actually simulate the human disc degeneration. The inappropriate animal model also leads to difficulties in comparing the efficacies among biomaterials in different reaches. Therefore, animal models that better simulate the clinical charateristics of human IDD should be acknowledged. In addition, in vivo regenerative outcomes should be carefully evaluated to obtain robust results. Nevertheless, many researches neglect certain critical characteristics, such as adhesive properties for biomaterials blocking annulus fibrosus defects and hyperalgesia that is closely related to the clinical manifestations, e.g., low back pain. Herein, in this review, we summarized the animal models established for IDD, and highlighted the proper models and parameters that may result in acknowledged IDD models. Then, we discussed the existing biomaterials for disc regeneration and the characteristics that should be considered for regenerating different parts of discs. Finally, well-established assays and parameters for in vivo disc regeneration are explored.

Uric acid can enhance MAPK pathway-mediated proliferation in rat primary vascular smooth muscle cells via controlling of mitochondria and caspase-dependent cell death

Hyperuricemia may be a risk factor for cardiovascular diseases such as hypertension and atherosclerosis, but the mechanisms underlying uric acid-induced pathological conditions remain unknown. In this study, we investigated the effect of short time and long-term administration of increasing uric acid concentrations on cell viability, proliferative and apoptotic pathways in vascular smooth muscle cells (VSMCs). Cell viability/proliferation was determined with WST-1 assay. Expression levels of mitogen-activated protein kinases (MAPKs) (phosphorylated (p)-p38 and p-p44/42 MAPK), extrinsic (caspase 3, caspase 8), and intrinsic (B-cell lymphoma-extra-large (Bcl-xL)) apoptotic pathway proteins were measured by Western blotting. In order to assess the proliferative effects of uric acid incubations on VSMCs, we monitored the proliferative/apoptosis signaling pathways for up to 24 h. Our results indicated that uric acid increases cell viability at time and dose-dependently in VSMCs. Immunoblotting results showed that uric acid treatment elevated the expression level of p-p38 MAPK but did markedly reduce the protein levels of p-p44/42, compared with all the uric acid doses-treated VSMCs, especially at 1 h. Uric acid stimulation increased caspase-3 protein levels and decreased Bcl-xL, but did not alter caspase-8 protein expression at the same dose and time. Furthermore, low uric acid incubations (0-7.5 mg/dL) did not affect any signaling pathways for long time points (6-24 h). In conclusion, our study demonstrates for the first time that VSMCs induced with uric acid can affect cell viability, proliferative, and apoptosis pathways at the widest time and dose range. These findings provide a better understanding of the uric acid effects related to vascular impairments.

Neuropeptide Y prevents nucleus pulposus cells from cell apoptosis and IL‑1β‑induced extracellular matrix degradation

Intervertebral disc degeneration (IDD) is characterized by excessive inflammatory reaction, and neuropeptide Y (NPY) was reported to have anti-inflammatory effect. However, the effect of NPY on NP cells has not been investigated up to date. This study aimed to clarify the role of NPY on the process of IDD. Fourteen fresh human lumbar intervertebral discs were harvested, and degeneration-related proteins were examined. Pfirrmann grading system was used to evaluate IDD. Rat nucleus pulposus (NP) cells were used to investigate the effect of NPY on the proliferation, apoptosis, and extracellular matrix (ECM) in NP cell induced by IL-1βin vitro. The expression levels of NPY and its receptors (type 1 receptor, Y1R, and type 2 receptor, Y2R) were detected via immunohistochemical analysis, western blot, and quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability and proliferation were explored using cell counting kit-8 assay, western blot, and immunofluorescence analysis. Cell apoptosis was investigated by Hoechst staining, JC-1 Staining, annexin V-FITC/PI double staining, and western blot. The secretion of NPY from NP cells was determined via enzyme-linked immunosorbent assay (ELISA). The expression of anabolic and catabolic gene was analyzed by qRT-PCR, western blot, immunofluorescence analysis, and ELISA. The expression of Y2R was significantly increased in both human degenerative intervertebral discs and IL-1β-induced NP cells. Although no positive results for NPY indicated by western blot both in vivo and in vitro, ELISA results demonstrated that the secretion of NPY from NP cells was increased by low-concentration IL-1β, but was decreased when the concentration of IL-1β was 30 ng/ml and above. In addition, NPY could promote NP cells proliferation and protect NP cells against IL‑1β‑induced apoptosis via suppressing mitochondrial-mediated apoptosis pathway. What's more, NPY can suppress the expression of catabolic gene and ameliorate IL-1β- induced matrix degeneration in NP cells. In conclusion, NPY could promote NP cell proliferation and alleviate IL‑1β‑induced cell apoptosis via mitochondrial pathway. In addition, NPY can suppress the expression of ECM‑catabolic proteinases and ameliorate IL-1β- induced ECM degeneration in vitro.

Down-Regulation of microRNA-30d Alleviates Intervertebral Disc Degeneration Through the Promotion of FOXO3 and Suppression of CXCL10

MicroRNAs (miRNAs/miRs) are important biomarkers for the progression of intervertebral disc degeneration (IDD). We investigated the role of miR-30d in IDD progression through its interactions with forkhead box O3 (FOXO3) and C-X-C motif ligand 10 (CXCL10). We first measured the expression of miR-30d, FOXO3, and CXCL10 in NP cells cultured from IDD patients. RNA-immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays were then employed to test the relationship among miR-30d, FOXO3, and CXCL10. Besides, gain- and loss-of function approaches were performed to assess the functional roles of miR-30d and FOXO3 in IDD in vitro and in vivo. We found high expression of miR-30d and CXCL10 and low expression of FOXO3 in IDD. We showed that miR-30d specifically targeted FOXO3, and that down-regulation of miR-30d promoted proliferation and inhibited apoptosis of NP cells in IDD by increasing the expression of FOXO3. Besides, FOXO3 inhibited apoptosis of NP cells by downregulation of CXCL10 expression. Moreover, inhibition of miR-30d promoted proliferation and inhibited apoptosis of NP cells in IDD by decreasing CXCL10. Furthermore, findings in the mouse IDD model confirmed the inhibitory role of decreased miR-30d in IDD progression. Thus, we show that downregulation of miR-30d could promote the proliferation of NP cells by increasing FOXO3 and decreasing CXCL10 expression, which may provide a novel therapeutic target for IDD.

Dual Role of Caveolin-1 in β-Catenin Signaling During Fracture Healing Induced by Low-Intensity Pulsed Ultrasound in Rabbits

We did this research to observe the effect of LIPUS on long bone fracture repair and caveolin-1, β-catenin signaling expression in the radius defects of rabbits, to explore its possible molecular mechanisms. 24 male New Zealand rabbits with bilateral radial bone defects were divided into 4 groups randomly, n = 6. The right side had daily LIPUS exposure for 20 minutes, while the left received sham treatment. After 7, 14, 21, 28 days, respectively, fracture healing was observed by X-ray imaging and Dual Energy X-ray Absorptiometry (DXA) scan, specimens were harvested for histology, immunohistochemistry, and gene expression analysis. We found that LIPUS brought forward endochondral ossification, increased the bone callus size without changes in Bone Mineral Density (BMD). The caveolin-1 expression increased first then decreased, while the β-catenin kept growing during the process. These demonstrated that caveolin-1 participated in fracture healing accelerated by LIPUS, which was speculated to play a dual role in β-catenin signaling expression.

Proinflammatory intervertebral disc cell and organ culture models induced by tumor necrosis factor alpha

Inflammation plays an important role in the pathogenesis of intervertebral disc (IVD) degeneration. The proinflammatory cytokine tumor necrosis factor alpha (TNF-α) has shown markedly higher expression in degenerated human disc tissue compared with healthy controls. Anti-inflammatory treatment targeting TNF-α has shown to alleviate discogenic pain in patients with low back pain. Therefore, in vitro and ex vivo inflammatory models utilizing TNF-α provide relevant experimental conditions for drug development in disc degeneration research. The current method article addressed several specific questions related to the model establishment. (a) The effects of bovine and human recombinant TNF-α on bovine nucleus pulposus (NP) cells were compared. (b) The required dose for an inflammatory IVD organ culture model with intradiscal TNF-α injection was studied. (c) The effect of TNF-α blocking at different stages of inflammation was evaluated. Outcomes revealed that bovine and human recombinant TNF-α induced equivalent inflammatory effects in bovine NP cells. A bovine whole IVD inflammatory model was established by intradiscal injection of 100 ng TNF-α/ cm3 disc volume, as indicated by increased nitric oxide, glycosaminoglycan, interleukin 6 (IL-6), and interleukin 8 (IL-8) release in culture media, and upregulation of MMP3, ADAMTS4, IL-8, IL-6, and cyclooxygenase (COX)-2 expression in NP tissue. However, results in human NP cells showed that the time point of anti-inflammatory treatment was crucial to achieve significant effects. Furthermore, anticatabolic therapy in conjunction with TNF-α inhibition would be required to slow down the pathologic cascade of disc degeneration.

Dioscin Attenuates Interleukin 1β (IL-1β)-Induced Catabolism and Apoptosis via Modulating the Toll-Like Receptor 4 (TLR4)/Nuclear Factor kappa B (NF-κB) Signaling in Human Nucleus Pulposus Cells

Background

Nucleus pulposus (NP) cell dysfunction and apoptosis contribute to disc degeneration. Dioscin, a natural steroid saponin, has been demonstrated to have anti-inflammatory, antiapoptotic, and antioxidative effects in various diseases. However, little is known about the roles of dioscin in intervertebral disc degeneration.

Material/Methods

To evaluate the roles of dioscin in disc degeneration and its specific mechanism, human NP cells were incubated with IL-1β and various concentrations of dioscin. Cell viability, extracellular matrix protein expression, catabolic factors, degree of apoptosis, inflammatory factors, and related signaling pathways were evaluated by western blotting, fluorescence immunostaining, TUNEL staining, and reverse transcription PCR.

Results

Dioscin inhibited IL-1β-activated apoptotic signaling and catabolic activity in NP cells. Dioscin suppressed TLR4/NF-0κB signaling, and attenuated the level of inflammatory mediators (IL-6, TNF-α) in IL-1β-stimulated human NP cells.

Conclusions

Our work provides the first evidence that dioscin attenuates IL-1β-activated inflammation and catabolic activity in human NP cells through inhibiting the TLR4/NF-κB pathway, indicating that dioscin is a new potential candidate for clinical therapy to attenuate disc degeneration.

Idebenone attenuates cerebral inflammatory injury in ischemia and reperfusion via dampening NLRP3 inflammasome activity

BACKGROUND

Idebenone is a well-appreciated mitochondrial protectant while the mechanisms underlying the neuroprotection in cerebral ischemia and reperfusion (I/R) remain elusive. It has been manifested NLRP3 inflammasom activation contributed to I/R induced damage. It raises questions how exactly NLRP3 inflammasom was activated in microglia and neuron and whether idebenone reverses the process in I/R.

METHODS

I/R rat model was utilized and BV2, primary microglia and PC12 cells were subjected to oxygen-glucose deprivation (OGD). Then, western-blotting, q-PCR, immunofluorescence staining, ELISA, flow cytometry and immunoprecipitation analysis were performed.

RESULTS

We found ROS-NLRP3 singaling was activated in BV2 cells at OGD/R 24 h. Importantly, microglial NLRP3 activation was essential for NLRP3 activation in PC12 cells under microglial-neuronal co-culture circumstance, which has been confirmed to induced neuronal apoptosis. Further, we found mitochondrial dysfunction in OGD/R led to mt-DNA translocation as well as generation of mt-ROS, resulting cytosolic accumulation of oxidized mt-DNA. Ultimately, oxidized mt-DNA binding to NLRP3 contributed to further activation of NLRP3 and dramatically augmented inflammation in BV2 and PC12 cells. Furthermore, idebenone treatment inhibited the process, thus suppressing the NLRP3-mediated inflammatory injury after OGD/R. In vivo, NLRP3 was activated in microglia of I/R rats and inhibition of NLRP3 was observed in idebenone treatment group, which had less neurological deficit and less infarct volume.

INTERPRETATION

Our data revealed the anti-inflammatory effects of idebenone via suppressing activation of NLRP3 and ameliorating NLRP3-mediating damage in I/R, which may provide new insight in therapeutic strategy for ischemic stroke.

Substrate Topography Regulates Differentiation of Annulus Fibrosus-Derived Stem Cells via CAV1-YAP-Mediated Mechanotransduction

Regeneration of annulus fibrosus (AF) through tissue engineering techniques shows promise as a treatment for patients with degenerative disc disease (DDD). Yet, it remains challenging because of the intrinsic heterogeneity of AF tissue and shortage of in-depth knowledge of its structure-function correlation. In the current study, we fabricated fibrous poly(ether carbonate urethane)urea (PECUU) scaffolds with various fiber sizes to mimic the microstructural feature of native AF and aimed to regulate the differentiation of AF-derived stem cells (AFSCs) by controlling the topographical cues of the scaffold. We found that the morphology of AFSCs varied significantly on scaffolds with various fiber sizes. Meanwhile, the expression of the phenotypic marker genes of outer AF was up-regulated on scaffolds with large fibers. Meanwhile, enhanced expression of the phenotypic marker genes of inner AF was seen on scaffolds with small fibers. Such topography-dependent gene expression in AFSCs approximated the biochemical profile of AF tissue in various zones. Moreover, cell spreading and nucleus translocation of Yes-associated protein (YAP) were facilitated with increased fiber size. Formation and maturation of focal adhesions of AFSCs were also promoted. We also found that Caveolin-1 (CAV1) positively modulated the mechano-responses of YAP in response to substrate topography. In conclusion, depending on the activation of the CAV1-YAP mechanotransduction axis, tuning the fiber size of scaffolds can effectively induce changes in cell shape, adhesions, and extracellular matrix expression. This work may therefore provide new insights in the design of novel materials toward AF tissue regeneration.

The protein tyrosine kinase inhibitor, Genistein, delays intervertebral disc degeneration in rats by inhibiting the p38 pathway-mediated inflammatory response

The treatment for intervertebral disc degeneration (IDD) has drawn great attention and recent studies have revealed that the p38 MAPK pathway is a potential therapeutic target for delaying the degeneration of intervertebral discs. In this study, we analyzed a nature-derived protein tyrosine kinase inhibitor, Genistein, and its function in delaying IDD in rats both in vitro and in vivo via the p38 MAPK pathway. Nucleus pulposus cells treated with Genistein showed better function compared with untreated cells. Further study revealed that Genistein could play a protective role in IDD by inhibiting phosphorylation of p38, consequently inhibiting the p38 pathway-mediated inflammatory response. The rat IDD model also demonstrated that Genistein could effectively delay the degeneration of intervertebral disc tissue. The current study reveals new biological functions of Genistein, further demonstrates the effects of the p38 MAPK pathway on intervertebral disc degeneration, and deepens our understanding of the treatment and prevention of IDD.

HO-1 induced autophagy protects against IL-1 β-mediated apoptosis in human nucleus pulposus cells by inhibiting NF-κB

In this study, we investigated the role of heme oxygenase-1 (HO-1) in intervertebral disc degeneration (IDD) by assessing the effects of HO-1 overexpression on IL-1β-induced apoptosis in nucleus pulposus cells (NPCs). Immunohistochemical staining showed HO-1 expression to be lower in NPCs from IDD patients than from patients with lumbar vertebral fractures (LVF). Western blot analysis showed HO-1 and LC3-II/I levels to be lower in NP tissues from IDD patients than from LVF patients, suggesting suppression of autophagy in degenerative intervertebral disc. Consistent with that idea, autophagy was increased in HO-1-overexpressing NPCs while IL-1β-induced apoptosis was reduced. These effects were reversed by treatment with the early autophagy inhibitor 3-methyl adenine, which suggests HO-1-induced autophagy suppresses IL-1β-induced apoptosis in NPCs. HO-1 overexpression promoted autophagy by increasing levels of Beclin-1/PI3KC3 complex. Phospho-P65 levels were lower in HO-1-overexpressing NPCs, suggesting inhibition of NF-κB-mediated apoptosis. Our study thus demonstrates that HO-1 promotes autophagy by enhancing formation of Beclin-1/PI3KC3 complex and suppresses IL-1β-induced apoptosis by inhibiting NF-κB. We suggest that HO-1 is a potential therapeutic target to alleviate IDD.

IL-10 delays the degeneration of intervertebral discs by suppressing the p38 MAPK signaling pathway

OBJECTIVES

The degeneration of intervertebral discs (IVD) is a risk factor for chronic low back pain. Anti-inflammation therapy could alleviate IVD degeneration. IL-10 is an important anti-inflammatory cytokine. However, the effect of IL-10 on IVD has not been fully revealed. The current study is to reveal the effect of IL-10 on IVD and its underlying mechanism.

METHODS

IL-1β was used to induce the degeneration of nucleus pulposus cells (NPCs). mRNA expression level was determined by qPCR. Protein expression level was determined by western blotting. Methylene blue was used to determined the expression of aggrecan. Immunocytochemical staining was used to determined the expression of collagen II. A rat caudal IVD degeneration model was established and used to evaluate the effect of IL-10 on IVD in vivo.

RESULTS

IL10 could alleviated NPC degeneration in both morphology and extracellular matrix. IL-10 could increase the mRNA expression of Collagen II, Sox-9, but decrease the mRNA expression of IL-1β, TNFα and Collagen X. IL-10 could also increase the protein level of Collagen II and aggrecan, but decrease that of Collagen X. Western blotting futher revealed the mechanism of the positive effect of IL-10 on IVD. IL-10 reduces phosphorylation level of p38 MAPK effectively. Rat caudal IVD degeneration model futher confirmed the positive effect of IL-10 on IVD degeneration and its mechanism in vivo.

CONCLUSION

The current study demonstrates that exogenous IL-10 treatment can induce an anti-inflammatory response and inhibit p38 MAPK activation to delay IVD degeneration.

Effects of Electrical Stimulation on Stem Cells

Recent interest in developing new regenerative medicine- and tissue engineering-based treatments has motivated researchers to develop strategies for manipulating stem cells to optimize outcomes in these potentially, game-changing treatments. Cells communicate with each other, and with their surrounding tissues and organs via electrochemical signals. These signals originate from ions passing back and forth through cell membranes and play a key role in regulating cell function during embryonic development, healing, and regeneration. To study the effects of electrical signals on cell function, investigators have exposed cells to exogenous electrical stimulation and have been able to increase, decrease and entirely block cell proliferation, differentiation, migration, alignment, and adherence to scaffold materials. In this review, we discuss research focused on the use of electrical stimulation to manipulate stem cell function with a focus on its incorporation in tissue engineering-based treatments.

TRIM32 triggers β-catenin signaling through ubiquitylation of AXIN1 to promote inflammatory factor-induced apoptosis of rat nucleus pulposus cells

The dysregulation of ubiquitin ligase is the cause of many human diseases. Tripartite motif protein 32 (TRIM32) is an E3 ubiquitin ligase whose role in nucleus pulposus (NP) cell apoptosis is unclear. The expression of TRIM family protein and β-catenin in 40 NP tissue samples was detected by RT-PCR. Interleukin (IL)-1β or tumor necrosis factor (TNF)-α was used to treat rat NP cells. Knockdown and overexpression of Trim32 were achieved using specific siRNA and recombinant plasmids. Western blotting, RT-PCR, and flow cytometry were used to assess the expression of TRIM32/β-catenin and the apoptosis rate of NP cells. Coimmunoprecipitation was adopted to analyze the possible interactions between AXIN1 and TRIM32. In clinical samples, TRIM32 expression was of positive relevance with the expression of CTNNB1 (β-catenin). In vitro, apoptosis of IL-1β- or TNF-α-treated rat NP cells was induced through upregulated Trim32 expression and activated β-catenin signaling, whereas Trim32 siRNA and inhibition of β-catenin reversed the induction effect of cytokines. Further studies indicated that TRIM32 activated the β-catenin signaling pathway through ubiquitination of AXIN1, thereby regulating apoptosis. Collectively, this study reveals that TRIM32 promotes inflammatory factor-induced apoptosis of rat NP cells, in part by direct degradation of AXIN1 to trigger β-catenin signaling.

Forkhead box C1 promotes the pathology of osteoarthritis by upregulating β-catenin in synovial fibroblasts

Osteoarthritis (OA) is a joint disease characterized by articular cartilage degeneration, and no effective treatment is available. The OA classification has shifted from a cartilage-only disease to a whole-joint disease, and the synovial membrane plays an important role. Therefore, studies are needed to identify additional genes that regulate the pathological changes in the synovial membrane to develop a promising therapeutic strategy for OA. Here, we validated that the expression of forkhead box protein C1 (FoxC1) and β-catenin was upregulated in OA synovial membranes and synovial fibroblasts (SFs). Gain- and loss-of-function studies revealed that FoxC1 overexpression promoted, whilst silencing inhibited OA synovial fibroblast (OASF) proliferation and pro-inflammatory cytokine [interleukin 6 (IL-6), interleukin 8 (IL-8) and tumour necrosis factor-α (TNF-α)] production. FoxC1 overexpression increased β-catenin mRNA, total and nuclear protein expression in OASFs and upregulated a disintegrin and metalloproteinase with thrombospondin motif 5 (ADAMTS-5), fibronectin, matrix metalloproteinase 3 (MMP3) and matrix metalloproteinase 13 (MMP13) mRNA and total protein expression in OASFs. Conversely, FoxC1 knockdown reduced β-catenin mRNA, total and nuclear protein expression in OASFs and reduced ADAMTS-5, fibronectin, MMP3 and MMP13 mRNA and total protein expression in OASFs. β-catenin mediates FoxC1-induced pathological changes (proliferation, catabolic regulation and inflammation) in OASFs. MicroRNA-200a-3p (miR-200a-3p) binds to the 3'-UTR of FoxC1 and mediates FoxC1 expression. Intra-articular FoxC1-specific siRNA transfection hindered OA development in mice. Therefore, our results demonstrate the key role FoxC1 plays in vivo and in vitro in OA synovial pathology, possibly identifying a potential novel therapeutic target for OA.

Overexpression of miR-150 Inhibits the NF-κB Signal Pathway in Intervertebral Disc Degeneration through Targeting P2X7

Objective: To elaborate the mechanism of miR-150 in the regulation of the NF-κB signal pathway in intervertebral disc degeneration (IDD) by targeting P2X7. Methods: The degenerative and normal intervertebral disc tissues were collected to detect the expressions of miR-150 and P2X7. Nucleus pulposus cells were transfected and divided into different groups. Cell apoptosis was determined by flow cytometry and TUNEL staining. The expressions of IL-6, TNF-α, MMP-3, MMP-13, Cox-2, iNOS, collagen II and aggrecan, as well as NF-κB-associated proteins were measured by qRT-PCR and Western blotting. Furthermore, IDD rat models were established to validate the role of miR-150 in vivo.Results: miR-150 was down-regulated but P2X7 was up-regulated in the degenerative intravertebral disc tissues. The apoptosis of nucleus pulposus cells in the IL-1β-induced group with the transfection of miR-150 mimic and siP2X7 was significantly decreased, with reduced levels of IL-6, TNF-α, MMP-3, MMP-13, Cox-2 and iNOS, increased levels of collagen II and aggrecan, as well as decreased P2X7, p-p65/p65 and cleaved caspase-3. However, the above factors showed an opposite tendency after treatment with miR-150 inhibitor. Furthermore, the P2X7 siRNA transfection could reverse the effects caused by miR-150 inhibitor. Simultaneously, pcDNA P2X7 transfection also inhibited the function of miR-150 mimic in IL-1β-induced nucleus pulposus cells. In vivoexperiments further verified the protective role of miR-150 in IDD rats. Conclusion: miR-150 may alleviate the degeneration of the intervertebral disc partially since it could restrict the NF-κB pathway by targeting P2X7, and thereby inhibiting IL-1β-induced matrix catabolism, inflammatory responses and apoptosis of the nucleus pulposus cells.

JAG2/Notch2 inhibits intervertebral disc degeneration by modulating cell proliferation, apoptosis, and extracellular matrix

Background

Intervertebral disc degeneration (IVDD)-related disorders are the major causes of low back pain. A previous study suggested that Notch activation serves as a protective mechanism and is a part of the compensatory response that maintains the necessary resident nucleus pulposus (NP) cell proliferation to replace lost or non-functional cells. However, the exact mechanism remains to be determined. In this study, we aimed to investigate the role of JAG2/Notch2 in NP cell proliferation and apoptosis.

Methods

Recombinant JAG2 or Notch2, Hes1, and Hey2 siRNAs were used to activate or inhibit Notch signaling. Cell proliferation, apoptosis, cell cycle regulatory factors, and pathways associated with Notch-mediated proliferation were examined. In vivo experiments involving an intradiscal injection of Sprague-Dawley rats were performed.

Results

Recombinant JAG2 induced Notch2 and Hes1/Hey2 expression together with NP cell proliferation. Downregulation of Notch2/Hes1/Hey2 induced G0/G1 phase cell cycle arrest in NP cells. Moreover, Notch2 mediated NP cell proliferation by regulating cyclin D1 and by activating PI3K/Akt and Wnt/β-catenin signaling. Furthermore, Notch signaling inhibited TNF-α-promoted NP cell apoptosis by suppressing the formation of the RIP1-FADD-caspase-8 complex. Finally, we found that intradiscal injection of JAG2 alleviated IVDD and that sh-Notch2 aggravated IVDD in a rat model. These results indicated that JAG2/Notch2 inhibited IVDD by modulating cell proliferation, apoptosis, and extracellular matrix. The JAG2/Notch2 axis regulated NP cell proliferation via PI3K/Akt and Wnt/β-catenin signaling and inhibited TNF-α-induced apoptosis by suppressing the formation of the RIP1-FADD-caspase-8 complex.

Conclusions

The current and previous results shed light on the therapeutic implications of targeting the JAG2/Notch2 axis to inhibit or reverse IVDD.

Exosomes of stem cells from human exfoliated deciduous teeth as an anti-inflammatory agent in temporomandibular joint chondrocytes via miR-100-5p/mTOR

Objectives

Temporomandibular joint osteoarthritis (TMJOA) is an inflammatory joint disease. This study investigated whether exosomes (Exos) of stem cells from human exfoliated deciduous teeth (SHEDs) have a therapeutic effect on TMJ inflammation and elucidated the underlying mechanisms.

Materials and methods

SHEDs were verified by flow cytometry. SHED-Exos were identified by western blotting, nanoparticle tracking analysis, and transmission electron microscopy. Western blot and RT-qPCR were performed to verify the anti-inflammatory effects of SHED-Exos. MicroRNA (miRNA) array analysis was conducted to determine the miRNA expression profiles of SHED-Exos, and the key pathways were analyzed. After chondrocytes were treated with an miR-100-5p mimic or rapamycin, relative expression of genes was measured by RT-qPCR and western blotting. A luciferase reporter assay was performed to reveal the molecular role of the exosomal miR-100 target, mTOR.

Results

MiR-100-5p was enriched in the SHED-Exos. Treatment with SHED-Exos suppressed the expression of interleukin-6 (IL-6), IL-8, matrix metalloproteinase 1 (MMP1), MMP3, MMP9, MMP13, and disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5). Chondrocytes treated with the miR-100 mimic showed lower expression of MMP1, MMP9, MMP13, ADAMTS5, and mTOR. In contrast, miR-100 downregulation upregulated the MMPs and mTOR. Rapamycin treatment upregulated miR-100 and downregulated MMPs and ADAMTS5. Furthermore, the luciferase reporter assay demonstrated that miR-100-5p directly targeted the mTOR 3′ untranslated region and that SHED-Exos miR-100-5p repressed mTOR expression.

Conclusions

This study demonstrated that SHED-Exos suppress inflammation in TMJ chondrocytes and may thus be a novel therapeutic agent for TMJ inflammation.

High glucose promotes annulus fibrosus cell apoptosis through activating the JNK and p38 MAPK pathways

Diabetes mellitus (DM) is an important risk factor of intervertebral disc degeneration. A high glucose niche-mediated disc cell apoptosis is an implicate causative factor for the spine degenerative diseases related with DM. However, the effects of a high glucose niche on disc annulus fibrosus (AF) cell apoptosis and the potential signaling transduction pathway is unclear. The present study is to investigate the effects of high glucose on disc AF cell apoptosis and the role of two potential signaling pathways in this process. Rat AF cells were cultured in baseline medium or medium with different concentrations (0.1 and 0.2 M) of glucose for 3 days. Flow cytometry was used to assess the degree of apoptosis. Activity of caspase 3/9 was evaluated by chemical kit. Expression of pro-apoptotic and anti-apoptotic molecules was analyzed by real-time polymerase chain reaction and Western blot. In addition, activity of the C-Jun NH₂-terminal kinases (JNK) pathway and p38 mitogen-activated protein kinase (MAPK) pathway was evaluated by Western blot. Compared with the control group, high glucose culture increased cell apoptosis ratio and caspase-3/9 activity, up-regulated expression of bax, caspase-3, cleaved caspase-3 and cleaved PARP, and down-regulated expression of bcl-2 in a glucose concentration-dependent manner. Additionally, high glucose culture increased expression of the p-JNK and p-p38 MAPK in a concentration-dependent manner. Further results showed that inhibition of the JNK or p38 MAPK pathway attenuated the effects of high glucose on AF cell apoptosis. Together, high glucose promoted disc AF cell apoptosis through regulating the JNK pathway and p38 MAPK pathway in a glucose concentration-dependent manner.

MALAT1-Driven Inhibition of Wnt Signal Impedes Proliferation and Inflammation in Fibroblast-Like Synoviocytes Through CTNNB1 Promoter Methylation in Rheumatoid Arthritis

Fibroblast-like synoviocytes (FLSs) participate in the pathogenesis of rheumatoid arthritis (RA). Emerging evidence has highlighted the role of long non-coding RNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) and its potential involvement in RA. In this study, we test the hypothesis that the MALAT1 might inhibit proliferation and inflammatory response of FLSs in RA. The expression of MALAT1 was examined in synovial tissues from patients with RA. The effect of MALAT1 on cultured FLSs was analyzed by introducing overexpressed MALAT1 or short hairpin RNA (shRNA) against MALAT1. To validate whether methylation of CTNNB1 promoter was affected by MALAT1 alternation, we assessed the recruitment of DNA methyltransferases to CTNNB1 promoter. In cultured FLSs with shRNA-mediated CTNNB1 knockdown or activated Wnt signaling, we found the interaction between CTNNB1 and Wnt signaling. MALAT1 expression was reduced in synovial tissues of RA. MALAT1 could bind to CTNNB1 promoter region and recruit methyltransferase to promote CTNNB1 promoter methylation, thereby inhibiting CTNNB1. Notably, MALAT1 could suppress the transcription and expression of CTNNB1, thereby modulating the Wnt signaling pathway. Silenced MALAT1 stimulated the nucleation of β-catenin and the secretion of inflammatory cytokines including interleukin-6, interleukin-10, and tumor necrosis factor-α. Additionally, shRNA-mediated MALAT1 silencing elevated proliferation and suppressed apoptosis of FLSs accompanied. These findings provide evidence for the inhibitory effect of MALAT1 on proliferation and inflammation of FLSs by promoting CTNNB1 promoter methylation and inhibiting the Wnt signaling pathway. Therefore, this study provides a candidate therapeutic target for RA.

β‑catenin signalling inhibits cartilage endplate chondrocyte homeostasis in vitro

Cartilaginous endplate degeneration serves a key role in the process of intervertebral disc (IVD) degeneration, however, effective therapies are hindered by an incomplete understanding of the mechanisms that underlie cartilage endplate (CEP) homeostasis and degeneration. Wnt/β-catenin signalling has been reported as a major factor in regulating biological processes. Whether Wnt/β-catenin signalling engages in CEP homeostasis has not yet been investigated. The present study aimed to assess the function of CEP cells via the activation of Wnt/β-catenin signalling to examine and promote the mechanism of degeneration of CEP in vitro. Rat CEP cells were confirmed to exhibit a chondrocytic phenotype by toluidine blue staining. The increased number of senescence-associated β-galactosidase (SA-β-gal)-positive cells and reduced cellular proliferation were investigated in the presence of a β-catenin inhibitor, and the inhibitor improved the trend of senescence. An increased number of apoptotic cells was detected by lithium chloride treatment, and inhibiting Wnt/β-catenin signalling protected the cells from apoptosis. Expression of the catabolic enzymes, metalloproteinase-13 and a disintegrin and metalloproteinase with thrombospondin motifs-5, and the decreased expression of aggrecan were also observed by Wnt/β-catenin signalling activation, and a Wnt/β-catenin signalling inhibitor decreased the expression of catabolic enzymes and increased the expression of aggrecan induced by Wnt/β-catenin signalling activation. Wnt/β-catenin signalling may provide potential strategies for preventing CEP degeneration.

The inflammatory cytokine TNF-α regulates the biological behavior of rat nucleus pulposus mesenchymal stem cells through the NF-κB signaling pathway in vitro

Nucleus pulposus (NP) mesenchymal stem cells (NPMSCs) are a potential cell source for intervertebral disc (IVD) regeneration; however, little is known about their response to tumor necrosis factor-α (TNF-α), a critical inflammation factor contributing to accelerating IVD degeneration. Accordingly, the aim of this study was to investigate the regulatory effects of TNF-α at high and low concentrations on the biological behaviors of healthy rat NPMSCs, including proliferation, migration, and NP differentiation. In this study, NPMSCs were treated with different concentration of TNF-α (0-200 ng/mL). Then we used annexin V/propidium iodide flow cytometry analysis to detect the apoptosis rate of NPMSCs. Cell Counting Kit-8, Edu assay, and cell cycle test were used to examine the proliferation of NPMSCs. Migration ability of NPMSCs was detected by wound healing assay and transwell migration assay. Pellets method was used to induce NP differentiation of NPMSCs, and immunohistochemical staining, real-time polymerase chain reaction, and Western blot analysis were used to examine the NPC phenotypic genes and proteins. The cells were further treated with the nuclear factor-κB (NF-κB) pathway inhibitor Bay 11-7082 to determine the role of the NF-κB pathway in the mechanism underlying the differentiation process. Results showed that treatment with a high concentration of TNF-α (50-200 ng/mL) could induce apoptosis of NPMSCs, whereas a relatively low TNF-α concentration (0.1-10 ng/mL) promoted the proliferation and migration of NPMSCs, but inhibited their differentiation toward NP cells. Moreover, we identified that the NF-κB signaling pathway is activated during the TNF-α-inhibited differentiation of NPMSCs, and the NF-κB signal inhibitor Bay 11-7082 could partially eliminate the adverse effect of TNF-α on the differentiation of NPMSCs. Therefore, our findings provide important insight into the dynamic biological behavior reactivity of NPMSCs to TNF-α during IVD degeneration process, thus may help us understanding the underlying mechanism of IVD degeneration.

In vitro effect of caveolin-1 as a slow-release material on bone-tendon junction healing: A comparative study

Bone tendon junction injury is hard to cure because of its special anatomical structure, and the treatment applied for bone-tendon junction injury cannot result in the perfect vascular regeneration and restoration of the fibrocartilage zone. In this article, we aim to explore the effect of caveolin-1 as a slow-release material on bone-tendon junction healing. Seventy-two New Zealand rabbits were randomly selected and assigned into the experimental, sham-operated and control groups (n = 24). Caveolin-1 microspheres and microcapsule were developed as drug delivery system. At the 4th, 8th, and 12th weeks after surgery, quadriceps muscle patella-patellar tendon (QMPPT) was obtained from each rabbit to observe the tendon-to-bone tunnel healing, and X-ray examination, histological examination and biomechanical testing were applied for evaluating new bone formation. As the X-ray showed, caveolin-1 increased the new bone area at each time point. At the 4th and 8th weeks after surgery, the rabbit treated with caveolin-1 slow release material showed repair of fibrocartilage. According to the biomechanical results, the cross-sectional area, breaking load and ultimate tensile strength were increased along with time. At the same time point, caveolin-1 increased the ultimate tensile strength. Our study demonstrates that caveolin-1 as a slow-release material could accelerate bone-tendon junction healing by promoting the formation of the transition zone.

Low-intensity pulsed ultrasound attenuates cardiac inflammation of CVB3-induced viral myocarditis via regulation of caveolin-1 and MAPK pathways

The aggressive immunological activity elicited by acute viral myocarditis contributes to a large amount of cardiomyocytes loss and poor prognosis of patients in clinic. Low-intensity pulsed ultrasound (LIPUS), which is an effective treatment modality for osteoarthropathy, has been recently illustrated regulating the overactive inflammatory response in various diseases. Here, we aimed to investigate whether LIPUS could attenuate coxsackievirus B3 (CVB3) infection-induced injury by coordinating the inflammatory response. Male BALB/c mice were inoculated intraperitoneally with CVB3 to establish the model of acute viral myocarditis. LIPUS treatment was given on Day 1, Day 1, 3 and Day 1, 3, 5 post-inoculation, respectively. All mice were followed up for 14 days. Day 1, 3, 5 LIPUS treatment significantly improved the survival rate, attenuated the ventricular dysfunction and ameliorated the cardiac histopathological injury of CVB3-infected mice. Western blotting analysis showed Day 1, 3, 5 LIPUS treatment decreased pro-inflammatory cytokines, increased the activation of caveolin-1 and suppressed p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) signallings in heart tissue. RAW264.7 cells were treated with lipopolysaccharides (LPS) to simulate the augmented inflammatory response in vivo. LIPUS treatment on RAW264.7 inhibited the expression of pro-inflammatory cytokines, activated caveolin-1 and suppressed p38 MAPK and ERK signallings. Transfecting RAW264.7 with caveolin-1 siRNA blunted the suppression of pro-inflammatory cytokines and MAPK signallings by LIPUS treatment. Taken together, we demonstrated for the first time that LIPUS treatment attenuated the aggressive inflammatory response during acute viral myocarditis. The underlying mechanism may be activating caveolin-1 and suppressing MAPK signallings.

IL-6/YAP1/β-catenin signaling is involved in intervertebral disc degeneration

Yes‐associated protein 1 (YAP1) is a transcriptional coactivator and negative regulator of the Hippo pathway. It regulates diverse cellular processes, such as cell proliferation, contact inhibition, and tissue size. However, the role of YAP1 in intervertebral disc degeneration (IDD) remains elusive. Here, we demonstrated that YAP1 was activated by Interleukin 6 (IL‐6) through tyrosine phosphorylation in nucleus pulposus cells (NP cells). Overexpression of YAP1 decreased Sox‐9, Col‐II, aggrecan expression, whereas increased matrix metalloproteinases 13 level. In contrast, knockdown of YAP1 by small interfering RNA (siRNA) showed opposite effects and rescued IL‐6 induced NP cells degeneration. In addition, western blot showed that IL‐6 treatment increased YAP1 and β‐catenin protein level; co‐immunoprecipitation (Co‐IP) and immunofluorescence analysis showed that IL‐6 enhanced YAP1 and β‐catenin interaction and nuclear accumulation. Knockdown of β‐catenin by siRNA blocked IL‐6 treatment or YAP1 overexpression induced degeneration. Moreover, we found that verteporfin, a specific inhibitor of YAP1, effectively alleviated IDD development in rat disks. Taken together, our findings indicated that YAP1 plays an important role in IDD, and β‐catenin is essential for IL‐6/YAP1 signaling.

Impact of Wnt signals on human intervertebral disc cell regeneration

Although preconditioning strategies are growing areas of interest for therapies targeting intervertebral discs (IVDs), it is unknown whether the Wnt signals previously implicated in chondrogenesis, Wnt3A, Wnt5A, and Wnt11, play key roles in the promotion of human nucleus pulposus (NP) cell redifferentiation. In this study, NP cells isolated from herniated disc patients were transduced with lentiviral vectors to overexpress the WNT3A, WNT5A, or WNT11 genes, or CRISPR associated protein 9 (Cas9)/single-guide RNA (sgRNA) vectors to knock out these genes. Following expansion, transduced NP cells were induced for redifferentiation toward the NP phenotype. The overexpression of specific WNT factors led to increases in both glycosaminoglycan (GAG) deposition and expression of redifferentiation genes. These effects were attenuated by knockout of the same WNT genes. These results indicate that specific WNT signals can regulate the expression of redifferentiation genes, unequally impact GAG deposition, and contribute to the redifferentiation of human NP cells. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3196-3207, 2018.

Polarity protein Canoe mediates overproliferation via modulation of JNK, Ras-MAPK and Hippo signalling

Objectives

Over the past decade an intriguing connection between cell polarity and tumorigenesis has emerged. Multiple core components of the junction complexes that help to form and maintain cell polarity display both pro‐ and anti‐tumorigenic functions in a context‐dependent manner, with the underlying mechanisms poorly understood.

Materials and Methods

With transgenic fly lines that overexpress or knock down specific signalling components, we perform genetic analysis to investigate the precise role of the polarity protein Canoe (Cno) in tumorigenesis and the downstream pathways.

Results

We show that overexpression of cno simultaneously activates JNK and Ras‐MEK‐ERK signalling, resulting in mixed phenotypes of both overproliferation and cell death in the Drosophila wing disc. Moderate alleviation of JNK activation eliminates the effect of Cno on cell death, leading to organ overgrowth and cell migration that mimic the formation and invasion of tumours. In addition, we find that the Hippo pathway acts downstream of JNK and Ras signalling to mediate the effect of Cno on cell proliferation.

Conclusions

Our work reveals an oncogenic role of Cno and creates a new type of Drosophila tumour model for cancer research.

Targeting tumor necrosis factor receptors in ankylosing spondylitis

Over the past two decades, considerable advances in our understanding of inflammatory and immune pathways have allowed for the growing use of targeted biologic therapy. Most notably, the introduction of tumor necrosis factor (TNF) inhibitors has dramatically changed the management of autoimmune inflammatory disorders, including ankylosing spondylitis (AS). Despite the efficacy of TNF inhibitors documented in multiple clinical trials, anti-TNF therapy in AS is far from foolproof; it is associated with serious adverse effects and limited response to therapy in some patients. Moreover, specific questions regarding the role of TNF as a mediator of AS remain unanswered. Therefore, additional efforts are needed in order to better understand the role of TNF in the pathogenesis of AS and to develop safer and more effective treatment strategies. The purpose of this review is to better the understanding of the physiologic and pathogenic roles of TNF signaling in the course of AS. Relevant TNF biology and novel approaches to TNF blockade in AS are discussed.