Deregulated miR-155 promotes Fas-mediated apoptosis in human intervertebral disc degeneration by targeting FADD and caspase-3

Omeprazole exacerbates intervertebral disc degeneration through Caspase-3 mediated apoptosis of nucleus pulposus cells: a Mendelian randomization, network toxicology, and in vitro experimental study

OBJECTIVE

To investigate the causal correlation and toxicological mechanisms of omeprazole in intervertebral disc degeneration (IVDD), alongside a particular emphasis on Caspase-3 (CASP3) mediated apoptosis of nucleus pulposus cells (NPCs).

METHODS

Mendelian randomization (MR): GWAS data was employed to assess causal associations between proton pump inhibitors (PPIs) and IVDD. Network toxicology: Shared omeprazole-IVDD targets were identified using STRING, SwissTargetPrediction, and GeneCards databases. Functional enrichment analysis: Biological pathways were explored by employing Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Molecular docking: Omeprazole-CASP3 binding affinity was assessed by employing AutoDock Vina. Experimental validation: Rat NPCs were subjected to CCK-8 assay viability, flow cytometry apoptosis, Western blot, and immunofluorescence.

RESULTS

MR analysis suggested omeprazole substantially augmented IVDD risk (OR = 1.058, 95% CI = 1.004-1.115, P = 0.034), with no association observed for esomeprazole or lansoprazole. Network toxicology identified 11 overlapping targets, with CASP3 as the hub gene. Molecular docking revealed strong omeprazole-CASP3 binding (free energy: - 6.725 kcal/mol) via hydrogen bonds, π-π stacking, and π-S interactions. Enrichment analysis highlighted the response to reactive oxygen species, caveolae, endopeptidase activity, and IL-17 signaling pathway as key pathways. As revealed by in vitro experiments, omeprazole dose-dependently lessened NPCs viability (300 µM) and heightened apoptosis (28.99% apoptosis rate). Western blot showed significant upregulation of Cleaved-CASP3/pro-CASP3 ratios (P < 0.001), and immunofluorescence demonstrated CASP3 nuclear translocation in omeprazole-treated NPCs.

CONCLUSIONS

This study found that taking omeprazole may exacerbate IVDD, and its potential mechanism is through CASP3 leading to apoptosis of NPCs. These findings advocate cautious long-term omeprazole use in clinical practice and suggest alternative PPIs.

Mechanism of microRNA-124-3p targeting calpain-1 to affect the function of intervertebral disc nucleus pulposus cells

Intervertebral disc degeneration (IVDD) represents a major cause of lower back pain, whose prevalence rises with age. This study probed into the mechanism of microRNA (miR)-124-3p regulating function of nucleus pulposus cells (NPCs) by targeting calpain-1 (CAPN1). Rat IVD NPCs were cultured in vitro and transfected with miR-124-3p mimics, miR-124-3p inhibitor, oe-CAPN1 and their negative controls. The mRNA levels of miR-124-3p and CAPN1 were assessed by RT-qPCR. Cell proliferation, apoptosis and migration were evaluated by CCK-8, flow cytometry and Transwell assays. Levels of CAPN1 protein, apoptosis-related proteins (BAX, Cleaved-Caspase3, BCL-2) and extracellular matrix (ECM) proteins (Collagen II, Aggrecan, Fibronectin, Collagen I, matrix metalloproteinase [MMP]-13) were determined by Western blot. The target binding relationship between miR-124-3p and CAPN1 was verified by dual-luciferase assay. miR-124-3p overexpression facilitated NPC function and the maintenance of ECM homeostasis, as evidenced by increased NPC proliferation and migration, decreased apoptosis, elevated apoptosis-related protein BCL-2 level, diminished BAX and Cleaved-Caspase3 levels, reduced levels of ECM homeostasis-associated factors Collagen I and MMP-13 proteins, as well as raised levels of Collagen II, Aggrecan and Fibronectin proteins. Conversely, miR-124-3p knockdown brought about the opposite results. miR-124-3p targeted CAPN1. Furthermore, overexpression of CAPN1 partially reversed the regulatory effects of miR-124-3p on the ECM homeostasis, proliferation and migration in NPCs, and promoted apoptosis. miR-124-3p contributed to proliferation and migration of IVD NPCs, and reduced their apoptosis by inhibiting CAPN1 expression, thereby modulating ECM homeostasis and maintaining the function of IVD NPCs.

Machine learning analysis of gene expression profiles of pyroptosis-related differentially expressed genes in ischemic stroke revealed potential targets for drug repurposing

The relationship between ischemic stroke (IS) and pyroptosis centers on the inflammatory response elicited by cerebral tissue damage during an ischemic stroke event. However, an in-depth mechanistic understanding of their connection remains limited. This study aims to comprehensively analyze the gene expression patterns of pyroptosis-related differentially expressed genes (PRDEGs) by employing integrated IS datasets and machine learning techniques. The primary objective was to develop classification models to identify crucial PRDEGs integral to the ischemic stroke process. Leveraging three distinct machine learning algorithms (LASSO, Random Forest, and Support Vector Machine), models were developed to differentiate between the Control and the IS patient samples. Through this approach, a core set of 10 PRDEGs consistently emerged as significant across all three machine learning models. Subsequent analysis of these genes yielded significant insights into their functional relevance and potential therapeutic approaches. In conclusion, this investigation underscores the pivotal role of pyroptosis pathways in ischemic stroke and identifies pertinent targets for therapeutic development and drug repurposing.

Mechanism of lncRNA ZFAS1 mediating nucleus pulposus cell pyroptosis in intervertebral disc degeneration

BACKGROUND

This study investigates the mechanism of lncRNA ZFAS1 in pyroptosis of TNF-α-induced nucleus pulposus cells (NPCs) in intervertebral disc degeneration (IDD).

METHODS

Mouse NPCs were isolated and induced by TNF-α to establish a cell model of IDD. The cell viability was evaluated by MTT assay. NLRP3, GSDMD-N, and cleaved-Caspase1 expressions were detected by Western blot. IL-1β and IL-18 contents were detected by ELISA. RT-qPCR was performed to determine ZFAS1, miR-155-3p, and METTL14 expressions. After intervening in ZFAS1 expression, the effect of ZFAS1 on pyroptosis was verified by Western blot and ELISA assays. RNA pull down or dual luciferase assay verified the binding between ZFAS1, miR-155-3p, and METTL14.

RESULTS

TNF-α induced pyroptosis of NPCs and promoted ZFAS1 expression. Silence of ZFAS1 repressed pyroptosis of TNF-α-induced NPCs. Mechanistically, ZFAS1 upregulated the transcription of METTL14 by competitively binding to miR-155-3p, thus enhancing NLRP3/Caspase-1-mediated NPC pyroptosis. Inhibition of miR-155-3p or overexpression of METTL14 alleviated the inhibitory effect of ZFAS1 silencing on TNF-α-treated NPC pyroptosis.

CONCLUSION

ZFAS1 facilitates NLRP3/Caspase-1-mediated pyroptosis of NPCs in IDD via miR-155-3p/METTL14 axis.

Microenvironment Remodeling Microgel Repairs Degenerated Intervertebral Disc via Programmed Delivery of MicroRNA-155

The progression of intervertebral disc degeneration (IVDD) is associated with increased cell apoptosis and reduced extracellular matrix (ECM) production, both of which are driven by ongoing inflammation. Thus, alleviating the acidic inflammatory microenvironment and mitigating the apoptosis of nucleus pulposus cells (NPCs) are essential for intervertebral disc (IVD) regeneration. Regulating pH levels in the local environment can reduce inflammation and promote tissue recovery. In this study, a lactic acid-capturing microgel carrying a functionalized miRNA-155 nanocarrier was designed for IVD regeneration. microRNA-155 was loaded into the NPC-targeted nanogel via host-guest binding. The miR-155 nanocarrier (NGM) achieved lactic acid-sensitive release of miRNA-155, resulting in rapid regulation of apoptosis. Moreover, SS31, which dissociated from the nanogel network, had the ability to regulate mitochondrial metabolism. Moreover, the microgel was constructed using a matrix metalloproteinase-responsive peptide. The chitosan coating on the microgel system was ingeniously employed to capture lactic acid and enable pH-responsive dissociation, thereby alleviating the acidic microenvironment to protect cell viability and facilitate the delivery of the NGM. The microgel system effectively promoted IVD regeneration by alleviating the acidic microenvironment and preventing NPC apoptosis.

Tetrahedral framework nucleic acids-based delivery of microRNA-155 alleviates intervertebral disc degeneration through targeting Bcl-2/Bax apoptosis pathway

Intervertebral disc degeneration (IDD) is one of the most common causes of chronic low back pain, which does great harm to patients' life quality. At present, the existing treatment options are mostly aimed at relieving symptoms, but the long-term efficacy is not ideal. Tetrahedral framework nucleic acids (tFNAs) are regarded as a type of nanomaterial with excellent biosafety and prominent performance in anti-apoptosis and anti-inflammation. MicroRNA155 is a non-coding RNA involved in various biological processes such as cell proliferation and apoptosis. In this study, a complex named TR155 was designed and synthesised with microRNA155 attached to the vertex of tFNAs, and its effects on the nucleus pulposus cells of intervertebral discs were evaluated both in vitro and in vivo. The experimental results showed that TR155 was able to alleviate the degeneration of intervertebral disc tissue and inhibit nucleus pulposus cell apoptosis via Bcl-2/Bax pathway, indicating its potential to be a promising option for the treatment of IDD.

MicroRNA-targeting nanomedicines for the treatment of intervertebral disc degeneration

Low back pain stands as a pervasive global health concern, afflicting almost 80% of adults at some point in their lives with nearly 40% attributable to intervertebral disc degeneration (IVDD). As only symptomatic relief can be offered to patients there is a dire need for innovative treatments.Given the accumulating evidence that multiple microRNAs (miRs) are dysregulated during IVDD, they could have a huge potential against this debilitating condition. The way miRs can profoundly modulate signaling pathways and influence several cellular processes at once is particularly exciting to tackle this multifaceted disorder. However, miR delivery encounters extracellular and intracellular biological barriers. A promising technology to address this challenge is the vectorization of miRs within nanoparticles, providing both protection and enhancing their uptake within the scarce target cells of the degenerated IVD. This comprehensive review presents the diverse spectrum of miRs' connection with IVDD and demonstrates their therapeutic potential when vectorized in nanomedicines.

Exosomes derived from Mouse Bone Marrow Mesenchymal Stem Cells Attenuate Nucleus Pulposus Cell Apoptosis via the miR-155- 5p/Trim32 Axis

BACKGROUND

Lower back pain, shown to be strongly associated with IVDD, affects approximately 60%-80% of adults and has a considerable societal and economic impact. Evidence suggests that IVDD, caused by abnormal apoptosis of nucleus pulposus cells (NPCs), can be treated using MSC-derived exosomes.

OBJECTIVE

This study aimed to evaluate the role of miR155-5p/Trim32 in intervertebral disc disease (IVDD) and elucidate the underlying molecular mechanisms. Deregulating miR-155 has been shown to promote Fas-mediated apoptosis in human IVDD. Evidence also suggests that tripartite motif (TRIM)-containing protein 32 (Trim32) is regulated by miR-155. However, the role of miR155-5p/Trim32 in IVDD remains unclear.

METHODS

Cell viability was checked using CCK-8 kits, and flow cytometry was used to analyze cell cycle and apoptosis. Cell migration was measured with a Transwell assay, while a luciferase assay was adopted to study how miR-155-5p interacts with Trim32. The roles of Trim32 and miR-155-5p were studied by silencing or up-regulating them in NPCs, while qPCR and immunoblots were used to evaluate mRNA and protein changes, respectively.

RESULTS

TNF-α treatment significantly inhibited cell viability but promoted Trim32 expression in primary mouse NPCs. Administration of bone marrow mesenchymal stem cells (BMSCs) attenuated primary NPC cell cycle arrest and apoptosis induced by TNF- α. BMSCs-derived exosomes could be taken up by NPCs to inhibit TNF-α-induced cell cycle arrest and apoptosis through miR-155-5p. Examination of the underlying mechanism showed that miR-155-5p targeted Trim32. Moreover, Trim32 overexpression inhibited the effect of BMSCs-derived exosomes on primary mouse NPC cell apoptosis induced by TNF-α.

CONCLUSION

Overall, these findings suggest that exosomes from BMSCs can suppress TNF-α-induced cell cycle arrest and apoptosis in primary mouse NPCs through the delivery of miR-155-5p by targeting Trim32. This study provides a promising therapeutic strategy for IVDD.

Study of molecular patterns associated with ferroptosis in Parkinson's disease and its immune signature

Parkinson's disease is the second most common neurodegenerative disease in the world. We downloaded data on Parkinson's disease and Ferroptosis-related genes from the GEO and FerrDb databases. We used WCGAN and Random Forest algorithm to screen out five Parkinson's disease ferroptosis-related hub genes. Two genes were identified for the first time as possibly playing a role in Braak staging progression. Unsupervised clustering analysis based on hub genes yielded ferroptosis isoforms, and immune infiltration analysis indicated that these isoforms are associated with immune cells and may represent different immune patterns. FRHGs scores were obtained to quantify the level of ferroptosis modifications in each individual. In addition, differences in interleukin expression were found between the two ferroptosis subtypes. The biological functions involved in the hub gene are analyzed. The ceRNA regulatory network of hub genes was mapped. The disease classification diagnosis model and risk prediction model were also constructed by applying hub genes based on logistic regression. Multiple external datasets validated the hub gene and classification diagnostic model with some accuracy. This study explored hub genes associated with ferroptosis in Parkinson's disease and their molecular patterns and immune signatures to provide new ideas for finding new targets for intervention and predictive biomarkers.

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.

Identification of potential immune-related hub genes in Parkinson's disease based on machine learning and development and validation of a diagnostic classification model

BACKGROUND

Parkinson's disease is the second most common neurodegenerative disease in the world. However, current diagnostic methods are still limited, and available treatments can only mitigate the symptoms of the disease, not reverse it at the root. The immune function has been identified as playing a role in PD, but the exact mechanism is unknown. This study aimed to search for potential immune-related hub genes in Parkinson's disease, find relevant immune infiltration patterns, and develop a categorical diagnostic model.

METHODS

We downloaded the GSE8397 dataset from the GEO database, which contains gene expression microarray data for 15 healthy human SN samples and 24 PD patient SN samples. Screening for PD-related DEGs using WGCNA and differential expression analysis. These PD-related DEGs were analyzed for GO and KEGG enrichment. Subsequently, hub genes (dld, dlk1, iars and ttd19) were screened by LASSO and mSVM-RFE machine learning algorithms. We used the ssGSEA algorithm to calculate and evaluate the differences in nigrostriatal immune cell types in the GSE8397 dataset. The association between dld, dlk1, iars and ttc19 and 28 immune cells was investigated. Using the GSEA and GSVA algorithms, we analyzed the biological functions associated with immune-related hub genes. Establishment of a ceRNA regulatory network for immune-related hub genes. Finally, a logistic regression model was used to develop a PD classification diagnostic model, and the accuracy of the model was verified in three independent data sets. The three independent datasets are GES49036 (containing 8 healthy human nigrostriatal tissue samples and 15 PD patient nigrostriatal tissue samples), GSE20292 (containing 18 healthy human nigrostriatal tissue samples and 11 PD patient nigrostriatal tissue samples) and GSE7621 (containing 9 healthy human nigrostriatal tissue samples and 16 PD patient nigrostriatal tissue samples).

RESULTS

Ultimately, we screened for four immune-related Parkinson's disease hub genes. Among them, the AUC values of dlk1, dld and ttc19 in GSE8397 and three other independent external datasets were all greater than 0.7, indicating that these three genes have a certain level of accuracy. The iars gene had an AUC value greater than 0.7 in GES8397 and one independent external data while the AUC values in the other two independent external data sets ranged between 0.5 and 0.7. These results suggest that iars also has some research value. We successfully constructed a categorical diagnostic model based on these four immune-related Parkinson's disease hub genes, and the AUC values of the joint diagnostic model were greater than 0.9 in both GSE8397 and three independent external datasets. These results indicate that the categorical diagnostic model has a good ability to distinguish between healthy individuals and Parkinson's disease patients. In addition, ceRNA networks reveal complex regulatory relationships based on immune-related hub genes.

CONCLUSION

In this study, four immune-related PD hub genes (dld, dlk1, iars and ttd19) were obtained. A reliable diagnostic model for PD classification was developed. This study provides algorithmic-level support to explore the immune-related mechanisms of PD and the prediction of immune-related drug targets.

Prognostic and immune correlation analysis of mitochondrial autophagy and aging-related genes in lung adenocarcinoma

PURPOSE

Mitophagy and aging (MiAg) are very important pathophysiological mechanisms contributing to tumorigenesis. MiAg-related genes have prognostic value in lung adenocarcinoma (LUAD). However, prognostic, and immune correlation studies of MiAg-related genes in LUAD are lacking.

METHODS

MiAg differentially expressed genes (DEGs) in LUAD were obtained from public sequencing datasets. A prognostic model including MiAg DEGs was constructed according to patients divided into low- and high-risk groups. Gene Ontology, gene set enrichment analysis, gene set variation analysis, CIBERSORT immune infiltration analysis, and clinical characteristic correlation analyses were performed for functional annotation and correlation of MiAgs with prognosis in patients with LUAD.

RESULTS

Seven MiAg DEGs of LUAD were identified: CAV1, DSG2, DSP, MYH11, NME1, PAICS, PLOD2, and the expression levels of these genes were significantly correlated (P < 0.05). The RiskScore of the MiAg DEG prognostic model demonstrated high predictive ability of overall survival of patients diagnosed with LUAD. Patients with high and low MiAg phenotypic scores exhibited significant differences in the infiltration levels of eight types of immune cells (P < 0.05). The multi-factor DEG regression model showed higher efficacy in predicting 5-year survival than 3- and 1-year survival of patients with LUAD.

CONCLUSIONS

Seven MiAg-related genes were identified to be significantly associated with the prognosis of patients diagnosed with LUAD. Moreover, the identified MiAg DEGs might affect the immunotherapy strategy of patients with LUAD.

Biomarkers for intervertebral disc and associated back pain: From diagnosis to disease prognosis and personalized treatment

Biomarkers are commonly recognized as objective indicators of a medical state or clinical outcome and have been widely used as clinical and diagnostic tools and surrogate endpoints in many pathological conditions. In the context of intervertebral disc (IVD) and associated back pain, also known as degenerative disc disease (DDD), the use of biomarkers has been poorly explored. DDD is currently diagnosed using imaging techniques and subjective pain scales, limiting an objective association between DDD and pain levels, as well as an evaluation of disease progression. There is a need for objective and reliable measurements for DDD, pain and pathology progression. DDD predictors could also help clinicians in deciding on the optimal treatment for distinct patient groups. This review addresses the current candidate biomarkers in DDD, including imaging, genetic, metabolite and protein-based parameters, both at the tissue and systemic levels, that may become a major advance in the diagnosis and prognosis of the disease, as well as in the management of therapeutic approaches to DDD.

Identification and validation of a prognostic signature of cuproptosis-related genes for esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a highly lethal form of cancer. Cuproptosis is a recently discovered form of regulated cell death. However, its significance in ESCC remains largely unknown. In this study, we observed significant expression differences in most of the 12 cuproptosis-related genes (CRGs) in the TCGA-ESCC dataset, which was validated using GSE20347, GSE38129, and individual ESCC datasets. We were able to divide patients in the TCGA-ESCC cohort into two subgroups based on disease, and found significant differences in survivor outcomes and biological functions between these subgroups. Additionally, we identified 11 prognosis-related genes from the 12 CRGs using LASSO COX regression analysis and constructed a CRGs signature for ESCC. Patients were categorized into high- and low-risk subgroups based on their median risk score, with those in the high-risk subgroup having significantly worse overall survival than those in the low-risk subgroup. The CRGs signature was also highly accurate in predicting prognosis and survival outcomes. Univariate and multivariate Cox regression analyses revealed that 8 of the 11 CRGs were independent prognostic factors for predicting survival in ESCC patients. Furthermore, our nomogram performed well and could serve as a useful tool for predicting prognosis. Finally, our risk model was found to be relevant to the sensitivity of targeted agents and immune infiltration. Functional enrichment analysis demonstrated that the risk model was associated with biological pathways of tumor migration and invasion. In summary, our study may provide a promising prognostic signature based on CRGs and offers potential targets for personalized therapy.

Research hotspots and trends of microRNAs in intervertebral disc degeneration: a comprehensive bibliometric analysis

BACKGROUND

MicroRNAs (miRNAs) are involved in various pathological processes, such as proliferation, growth, and apoptosis, of intervertebral disc (IVD) cells and play an important role in the development of intervertebral disc degeneration (IDD). Although some studies have reported the role of miRNAs in IDD, scientific econometric analysis in this field is not available.

OBJECTIVES

We designed this study to describe the current research trends and potential mechanisms associated with the role of miRNAs in IDD and to provide new ideas for future research in this field.

METHODS

We conducted a bibliometric analysis of the publications on the role of miRNAs in IDD included in the Web of Science core collection database to elucidate the current research trends in this field. The potential mechanisms were constructed using the Arrowsmith project.

RESULTS

We found that the number of miRNAs and IDD-related publications increased over the years. China was the most important contributor to research in this field. The top three institutions in terms of number of articles published were Huazhong University of Science and Technology, Shanghai Jiao Tong University, and Xi'an Jiao Tong University. Shanghai Jiao Tong University had the highest number of citations. Experimental and thermal medicine had the maximum number of documents, and Cell promotion had the most citations. The journal with the most mean times cited per study was Annals of the Rheumatic Diseases. The author Wang K had the highest number of publications, and Wang HQ had the highest number of citations. These two authors made important contributions to the research in this field. The keyword analysis showed that recent studies have focused on miRNAs regulating nucleus pulposus cell apoptosis and proliferation. Moreover, we revealed the potential mechanisms of miRNAs associated with IDD, including miRNAs regulating the extracellular matrix (ECM) degradation, mediating cartilage endplate (CEP) degeneration, and participating in inflammatory responses.

CONCLUSION

We demonstrated the knowledge map of miRNAs and IDD-related research through bibliometric analysis and elucidated the current research status and hotspots in this field. The mechanisms by which miRNAs regulate the apoptosis and proliferation of degenerated IVDs, promote ECM degradation, mediate CEP degeneration, and participate in inflammatory responses should be explored in further studies.

MicroRNA-155 suppressed cholesterol-induced matrix degradation, pyroptosis and apoptosis by targeting RORα in nucleus pulposus cells

Intervertebral disc degeneration (IDD) is associated with low back pain, yet its inherent mechanism remains obscure. Hypercholesteremia was regarded as a risk factor for IDD, and our previous study showed that cholesterol accumulation could elicit matrix degradation in the nucleus pulposus (NP). MicroRNA-155 (miR-155) was substantiated as protective in IDD, but its role in cholesterol-induced IDD was unclear. The present study investigated whether miR-155 could mediate cholesterol-related IDD and its internal mechanisms. In vivo experiments revealed high-fat diet-induced hypercholesteremia in wild-type (WT) mice along with the occurrence of IDD, whereas Rm155LG transgenic mice showed milder NP degeneration, as evidenced by Safranin O-fast green (SF) staining and immunohistochemistry (IHC). Meanwhile, IHC showed that NLRP3 and Bax expression was also suppressed in Rm155LG mice. In vitro studies using Western blotting (WB) and immunofluorescence (IF) confirmed that the miR-155 mimic could alleviate cholesterol-induced matrix degradation, apoptosis and pyroptosis in NP. Moreover, RORα was upregulated in severely degenerated NP compared to mild IDD. It was also noted that RORα was suppressed in Rm155LG mice. In this study, we demonstrated that miR-155 could target RORα and that inhibition of RORα could prevent cholesterol-induced matrix degradation, apoptosis, and pyroptosis in NP, indicating the protective effect of miR-155 in cholesterol-induced IDD by targeting RORα.

The long non-coding RNA KLF3-AS1/miR-10a-3p/ZBTB20 axis improves the degenerative changes in human nucleus pulposus cells

Excessive apoptosis of intervertebral disc cells, namely nucleus pulposus (NP) cells, results in decreased cell density and extracellular matrix (ECM) catabolism, hence leading to intervertebral disc degeneration (IVDD). As a cell model in the present study, a commercially available human NP cell line was utilized. Long noncoding RNAs and microRNAs may regulate the proliferation or apoptosis of human NP cells, hence exerting a significant influence on the occurrence of IVDD. KLF3-AS1 was discovered to be abnormally downregulated in IVDD tissues. Overexpression of KLF3-AS1 enhanced NP cell viability, prevented cell apoptosis, boosted ECM synthesis, and lowered MMP-13 and ADAMTS4 levels. ZBTB20 and KLF3-AS1 were co-expressed in IVDD; ZBTB20 overexpression had similar effects on NP cells, ECM production, and MMP-13 and ADAMTS4 levels as KLF3-AS1 overexpression. miR-10a-3p may target KLF3-AS1 and ZBTB20 and inhibit the expression of ZBTB20. Inhibition of miR-10a-3p enhanced NP cell viability, reduced apoptosis, and enhanced ECM synthesis. KLF3-AS1 overexpression increased ZBTB20 expression, whereas miR-10a-3p overexpression decreased ZBTB20 expression; miR-10a-3p overexpression reduced the effects of KLF3-AS1 on ZBTB20. Overexpression of miR-10a-3p consistently decreased the effects of KLF3-AS1 overexpression on NP cell survival, apoptosis, and ECM synthesis. In conclusion, KLF3-AS1 overexpression may ameliorate degenerative NP cell alterations through the miR-10a-3p/ZBTB20 axis.

Exploration of microRNA-106b-5p as a therapeutic target in intervertebral disc degeneration: a preclinical study

MicroRNA (miRNA) has emerge as a vital regulator in the pathogenesis of intervertebral disc degeneration (IDD). However, miR-106b-5p expression in the human nucleus pulposus (NP) and potential mechanisms remain to be elucidated. In this study, the aim was to verify the potential therapeutic mechanisms of miR-106b-5p for IDD. Key miRNAs were screened for in degenerative and normal human intervertebral disc samples. qRT-PCR and fluorescence in situ hybridization (FISH) were used to verify the miR-106b-5p differential expression. The targeting link between miR-106b-5p and Sirtuin 2 (SIRT2) was identified using the luciferase reporter assay and bioinformatics. Flow cytometry, EdU method, and cell scratching were all performed to determine the NP cell function and IDD models were constructed for in vivo experiments. SIRT2, MMP13, ADAMTS5, Col II, Aggrecan, Ras, ERK1/2, and p-ERK1/2 protein levels were assayed by western blotting. Overexpression of miR-106b-5p in NP cells decreased cell growth, induced apoptosis, hindered extracellular matrix formation, and increased the expression of matrix-degrading enzymes through the SIRT2/MAPK/ERK signaling pathway. Importantly, intradiscal delivery of antagomiR-106b-5p significantly attenuated IDD development. Our findings demonstrate that targeting miR-106b-5p in intervertebral disc has therapeutic effects on IDD.

Biomaterials delivery strategies to repair degenerated intervertebral discs by regulating the inflammatory microenvironment

Intervertebral disc degeneration (IVDD) is one of the leading causes of lower back pain. Although IVDD cannot directly cause death, it can cause pain, psychological burdens, and economic burdens to patients. Current conservative treatments for IVDD can relieve pain but cannot reverse the disease. Patients who cannot tolerate pain usually resort to a strategy of surgical resection of the degenerated disc. However, the surgical removal of IVDD can affect the stability of adjacent discs. Furthermore, the probability of the reherniation of the intervertebral disc (IVD) after surgery is as high as 21.2%. Strategies based on tissue engineering to deliver stem cells for the regeneration of nucleus purposes (NP) and annulus fibrosus (AF) have been extensively studied. The developed biomaterials not only locally withstand the pressure of the IVD but also lay the foundation for the survival of stem cells. However, the structure of IVDs does not provide sufficient nutrients for delivered stem cells. The role of immune mechanisms in IVDD has recently become clear. In IVDD, the IVD that was originally in immune privilege prevents the attack of immune cells (mainly effector T cells and macrophages) and aggravates the disease. Immune regulatory and inflammatory factors released by effector T cells, macrophages, and the IVD further aggravate IVDD. Reversing IVDD by regulating the inflammatory microenvironment is a potential approach for the treatment of the disease. However, the biological factors modulating the inflammatory microenvironment easily degrade in vivo. It makes it possible for different biomaterials to modulate the inflammatory microenvironment to repair IVDD. In this review, we have discussed the structures of IVDs and the immune mechanisms underlying IVDD. We have described the immune mechanisms elicited by different biological factors, including tumor necrosis factors, interleukins, transforming growth factors, hypoxia-inducible factors, and reactive oxygen species in IVDs. Finally, we have discussed the biomaterials used to modulate the inflammatory microenvironment to repair IVDD and their development.

FADD as a key molecular player in cancer progression

Cancer is a leading disease-related cause of death worldwide. Despite advances in therapeutic interventions, cancer remains a major global public health problem. Cancer pathogenesis is extremely intricate and largely unknown. Fas-associated protein with death domain (FADD) was initially identified as an adaptor protein for death receptor-mediated extrinsic apoptosis. Recent evidence suggests that FADD plays a vital role in non-apoptotic cellular processes, such as proliferation, autophagy, and necroptosis. FADD expression and activity of are modulated by a complicated network of processes, such as DNA methylation, non-coding RNA, and post-translational modification. FADD dysregulation has been shown to be closely associated with the pathogenesis of numerous types of cancer. However, the detailed mechanisms of FADD dysregulation involved in cancer progression are still not fully understood. This review mainly summarizes recent findings on the structure, functions, and regulatory mechanisms of FADD and focuses on its role in cancer progression. The clinical implications of FADD as a biomarker and therapeutic target for cancer patients are also discussed. The information reviewed herein may expand researchers’ understanding of FADD and contribute to the development of FADD-based therapeutic strategies for cancer patients.

Regulatory roles of noncoding RNAs in intervertebral disc degeneration as potential therapeutic targets (Review)

Intervertebral disc degeneration (IDD) is the leading cause of lower back pain, which is one of the primary factors that lead to disability and pose a serious economic burden. The key pathological processes involved are extracellular matrix degradation, autophagy, apoptosis, and inflammation of nucleus pulposus cells. Non-coding RNAs (ncRNAs), including microRNAs, long ncRNAs and circular RNAs, are key regulators of the aforementioned processes. ncRNAs are differentially expressed in tissues of the intervertebral disc between healthy individuals and patients and participate in the pathological progression of IDD via a complex pattern of gene regulation. However, the regulatory mechanisms of ncRNAs in IDD remain unclear. The present review summarizes the latest insights into the regulatory role of ncRNAs in IDD and sheds light on potentially novel therapeutic strategies for IDD that may be implemented in the future.

microRNAs associated with the pathogenesis and their role in regulating various signaling pathways during Mycobacterium tuberculosis infection

Despite more than a decade of active study, tuberculosis (TB) remains a serious health concern across the world, and it is still the biggest cause of mortality in the human population. Pathogenic bacteria recognize host-induced responses and adapt to those hostile circumstances. This high level of adaptability necessitates a strong regulation of bacterial metabolic characteristics. Furthermore, the immune reponse of the host virulence factors such as host invasion, colonization, and survival must be properly coordinated by the pathogen. This can only be accomplished by close synchronization of gene expression. Understanding the molecular characteristics of mycobacterial pathogenesis in order to discover therapies that prevent or resolve illness relies on the bacterial capacity to adjust its metabolism and replication in response to various environmental cues as necessary. An extensive literature details the transcriptional alterations of host in response to in vitro environmental stressors, macrophage infection, and human illness. Various studies have recently revealed the finding of several microRNAs (miRNAs) that are believed to play an important role in the regulatory networks responsible for adaptability and virulence in Mycobacterium tuberculosis. We highlighted the growing data on the existence and quantity of several forms of miRNAs in the pathogenesis of M. tuberculosis, considered their possible relevance to disease etiology, and discussed how the miRNA-based signaling pathways regulate bacterial virulence factors.

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.

A new biomarker to enhance the radiosensitivity of hepatocellular cancer: miRNAs

Aims: This review summarizes findings regarding miRNAs that modulate radiation in hepatocellular carcinoma (HCC) and evaluates their potential clinical therapeutic uses. Materials & methods: We searched the relevant English-language medical databases for papers on miRNAs and radiation therapy for tumors to identify miRNAs that are linked with radiosensitivity and radioresistance, focusing on those associated with HCC radiation. Results: There were 88 papers assessed for miRNAs associated with tumor radiation, 56 of which dealt with radiosensitization, 21 with radioresistance and 11 with radiosensitization for HCC. Conclusion: Further work in this area would enable future evaluation of radiation responses and the potential use of miRNAs as therapeutic agents in HCC patients.

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.

Role of Caspase Family in Intervertebral Disc Degeneration and Its Therapeutic Prospects

Intervertebral disc degeneration (IVDD) is a common musculoskeletal degenerative disease worldwide, of which the main clinical manifestation is low back pain (LBP); approximately, 80% of people suffer from it in their lifetime. Currently, the pathogenesis of IVDD is unclear, and modern treatments can only alleviate its symptoms but cannot inhibit or reverse its progression. However, in recent years, targeted therapy has led to new therapeutic strategies. Cysteine-containing aspartate proteolytic enzymes (caspases) are a family of proteases present in the cytoplasm. They are evolutionarily conserved and are involved in cell growth, differentiation, and apoptotic death of eukaryotic cells. In recent years, it has been confirmed to be involved in the pathogenesis of various diseases, mainly by regulating cell apoptosis and inflammatory response. With continuous research on the pathogenesis and pathological process of IVDD, an increasing number of studies have shown that caspases are closely related to the IVDD process, especially in the intervertebral disc (IVD) cell apoptosis and inflammatory response. Therefore, herein we study the role of caspases in IVDD with respect to the structure of caspases and the related signaling pathways involved. This would help explore the strategy of regulating the activity of the caspases involved and develop caspase inhibitors to prevent and treat IVDD. The aim of this review was to identify the caspases involved in IVDD which could be potential targets for the treatment of IVDD.

Construction of a circular RNA-based competing endogenous RNA network to screen biomarkers related to intervertebral disc degeneration

Background

Intervertebral disc degeneration (IDD) is a leading cause of disability with limited treatment strategies. A better understanding of the mechanism of IDD might enable less invasive and more targeted treatments. This study aimed to identify the circular RNA (circRNA)–microRNA (miRNA)–messenger RNA (mRNA) competing endogenous RNA (ceRNA) regulatory mechanisms in IDD.

Methods 

The GSE67567 microarray dataset was downloaded from the Gene Expression Omnibus database. After data preprocessing, differentially expressed circRNAs, miRNAs and mRNAs between IDD and controls were identified. A ceRNA network was constructed on the basis of the interaction between circRNAs and miRNAs, and miRNAs and mRNAs. Pathway enrichment analysis was performed on the mRNAs in the ceRNA network. Then, with ‘intervertebral disc degeneration’ as keywords, IDD-related Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were searched for in the Comparative Toxicogenomics Database.

Results

A total of 105 differentially expressed circRNAs, 84 miRNAs and 967 mRNAs were identified. After analysis, 86 circRNA–miRNA, and 126 miRNA–mRNA regulatory relationship pairs were obtained to construct a ceRNA network. The mRNAs were enriched in six KEGG signalling pathways, and four were associated with IDD: the hsa04350: TGF-beta signalling pathway, hsa04068: FoxO signalling pathway, hsa05142: Chagas disease (American trypanosomiasis) and hsa04380: Osteoclast differentiation. An IDD-related ceRNA network was constructed involving four circRNAs, three miRNAs and 11 mRNAs. Auxiliary validation showed that the expression levels of miR-185-5p, miR-486-5p, ACVR1B, FOXO1, SMAD2 and TGFB1 were consistent in different databases.

Conclusions

Our study identified some circRNA–miRNA–mRNA interaction axes potentially associated with the progression of IDD, viz.: circRNA_100086–miR-509-3p–MAPK1, circRNA_000200–miR-185-5p–TGFB1, circRNA_104308–miR-185-5p–TGFB1, circRNA_400090–miR-486-5p–FOXO1 and circRNA_400090–miR-486-5p–SMAD2.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05579-0.

1. An IDD-related ceRNA network involving four circRNAs, three miRNAs and 11 mRNAs was constructed.

2. The expression levels of miR-185-5p, miR-486-5p, FOXO1, SMAD2 and TGFB1 were consistent in different databases.

3. Our study identified IDD-related circRNA–miRNA–mRNA interaction axes, including circRNA_100086–miR-509-3p–MAPK1.

Lipid nanocapsules for intracellular delivery of microRNA: a first step towards intervertebral disc degeneration therapy

Approximately 40% of cases of lower back pain are caused by disc degeneration disease (DDD). It is well established that microRNA (miR) dysregulation is a key player in various diseases, and its impact on DDD has recently been highlighted. RNAi (miR in particular) is increasingly being considered as a novel therapeutic tool. However, free miR is degraded rapidly in vivo, and its protection is thus a prerequisite. Nanoparticular platforms, such as lipid nanocapsules (LNC), could be specifically adapted for miR delivery, allowing the transfer and release of miR in the cell cytoplasm. The objective of the current study was to formulate and characterize miR-loaded LNC to establish their in vitro potential (cell internalization, bioactivity) as well as to determine the safety and feasibility of in situ intervertebral disc (IVD) injection of miR LNC in a healthy sheep model. Using a miR library, miR-155 was clearly identified as being involved in the DDD process and was selected for further assessment. miR-155-loaded LNC (miR-155 LNC) were successfully formulated using a phase inversion process, with the addition of lipoplexes in the cooling step. Following purification, miR-155 LNC were fully characterized, and the optimized formulation had an average diameter of 75 nm, a polydispersity index below 0.1, and a positive zeta potential. By fluorescence spectroscopy, an encapsulation efficiency (EE) of 75.6% and a drug loading (DL) of 0.6% were obtained, corresponding to a sufficient amount of miR per mL of LNC to potentially have a biological effect. The sustained release of miR-155 from LNC was demonstrated compared with free miR-155: only 22% was released after 2 h and 58% after 24 h. miR-155 protection against endonuclease degradation by LNC was confirmed by gel electrophoresis, a sine qua non condition for it to be administered in vivo. Cell viability assays were performed on human adipose stromal cells (hASCs) and ovine Nucleus pulposus cells (oNP), and a cytotoxicity of less than 30% was obtained at the considered concentrations. Additionally, miR-155 LNC cell internalization was demonstrated by flow cytometry and confocal imaging. Moreover, downregulation of total ERK1/2 in hASCs and oNP cells, after miR-155 LNC treatment, was demonstrated by Western blot and quantitative reverse-transcription PCR (qRT-PCR), thus confirming maintenance of its bioactivity after formulation and internalization. Finally, the feasibility and safety of miR-155 LNC in situ injection (compared to control groups: blank LNC and sham condition) was demonstrated in healthy sheep by imaging (MRI and T2wsi measurement) and histology (Boos' scoring) analysis. T2wsi was measured, and no significant difference was observed three months after the injection between the different conditions. No histological impact was observed, with no significant difference in Boos' scoring between the different conditions. All these results suggest LNC may be a potent strategy for the encapsulation and delivery of miR (particularly miR-155) and can be considered as a first step towards IVD regenerative medicine.

SNHG5/miR-299-5p/ATF2 Axis as a Biomarker in Immune Microenvironment of Intervertebral Disc Degeneration

Methods

The data sets of GSE56081 and GSE63492 in the Gene Expression Omnibus (GEO) database were used for screening and analysis, and the key gene markers were verified by GSE34095 and GSE126883. Finally, the infiltration of immune cells in the data were analyzed by MCPcounter analysis package.

Results

In this study, a ceRNA containing 15 lncRNAs, 9 miRNAs, and 103 mRNAs was constructed. After multimodel screening and verification, key gene marker was found, namely, ATF2. The lncRNA/miRNA/mRNA axis closely related to ATF2 have also been found, namely, SNHG5/miR-299-5p/ATF2. In the analysis of immune infiltration, ATF2 was negatively correlated with T cells but positively correlated with neutrophils and endothelial cells.

Conclusion

The SNHG5/miR-299-5p/ATF2 can be used as biomarker of IDD, and infiltration of immune cells plays an important role in the pathological development of IDD. In addition, as a marker of IDD, the involvement of the above-mentioned axis in the pathological development of IDD remains to be further explored.

Identification of Core Genes and Screening of Potential Targets in Intervertebral Disc Degeneration Using Integrated Bioinformatics Analysis

Background: Intervertebral disc degeneration (IDD), characterized by diverse pathological changes, causes low back pain (LBP). However, prophylactic and delaying treatments for IDD are limited. The aim of our study was to investigate the gene network and biomarkers of IDD and suggest potential therapeutic targets.

Methods: Differentially expressed genes (DEGs) associated with IDD were identified by analyzing the mRNA, miRNA, and lncRNA expression profiles of IDD cases from the Gene Expression Omnibus (GEO). The protein–protein interaction (PPI) network, Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis as well as miRNA–lncRNA–mRNA networks were conducted. Moreover, we obtained 71 hub genes and performed a comprehensive analysis including GO, KEGG, gene set enrichment analysis (GSEA), gene set variation analysis (GSVA), Disease Ontology (DO), methylation analysis, receiver operating characteristic (ROC) curve analysis, immune infiltration analysis, and potential drug identification. We finally used qRT-PCR to verify 13 significant DEGs in normal and degenerative nucleus pulposus cells (NPCs).

Results: We identified 305 DEGs closely related to IDD. The GO and KEGG analyses indicated that changes in IDD are significantly associated with enrichment of the inflammatory and immune response. GSEA analysis suggested that cell activation involved in the inflammatory immune response amide biosynthetic process was the key for the development of IDD. The GSVA suggested that DNA repair, oxidative phosphorylation, peroxisome, IL-6-JAK-STAT3 signaling, and apoptosis were crucial in the development of IDD. Among the 71 hub genes, the methylation levels of 11 genes were increased in IDD. A total of twenty genes showed a high functional similarity and diagnostic value in IDD. The result of the immune cell infiltration analysis indicated that seven genes were closely related to active natural killer cells. The most relevant targeted hub genes for potential drug or molecular compounds were MET and PIK3CD. Also, qRT-PCR results showed that ARHGAP27, C15orf39, DEPDC1, DHRSX, MGAM, SLC11A1, SMC4, and LINC00887 were significantly downregulated in degenerative NPCs; H19, LINC00685, mir-185-5p, and mir-4306 were upregulated in degenerative NPCs; and the expression level of mir-663a did not change significantly in normal and degenerative NPCs.

Conclusion: Our findings may provide new insights into the functional characteristics and mechanism of IDD and aid the development of IDD therapeutics.

Downregulation of miR-760 Causes Human Intervertebral Disc Degeneration by Targeting the MyD88/Nuclear Factor-Kappa B Signaling Pathway

Dysregulation of microRNAs (miRNAs) plays a critical role in the development of intervertebral disc degeneration (IDD). In this study, we present evidence from in vitro and in vivo research to elucidate the mechanism underlying the role of miR-760 in IDD. miRNA microarray and quantitative reverse transcription-polymerase chain reaction were used to determine the miRNA profiles in patients with IDD. Functional analysis was performed to evaluate the role of miR-760 in the pathogenesis of IDD. Luciferase reporter and western blotting assays were used to confirm the miRNA targets. The expression of miR-760 was significantly decreased in degenerative nucleus pulposus (NP) cells and negatively correlated with disc degeneration grade. Functional assays demonstrated that miR-760 delivery significantly increased NP cell proliferation and promoted the expression of collagen II and aggrecan. Moreover, MyD88 was identified as a target gene of miR-760. miR-760 effectively suppressed MyD88 expression by interacting with the 3'-untranslated region, which was abolished by miR-760 binding site mutations. An in vivo experiment using an IDD mouse model showed that the upregulation of miR-760 could effectively suspend IDD. Therefore, miR-760 was found to play an important role in IDD and can be used as a promising therapeutic target for the treatment of patients with IDD.

Emerging Issues Questioning the Current Treatment Strategies for Lumbar Disc Herniation

Lumbar disc herniation is among the common phenotypes of degenerative lumbar spine diseases, significantly affecting patients' quality of life. The practice pattern is diverse. Choosing conservative measures or surgical treatments is still controversial in some areas. For those who have failed conservative treatment, surgery with or without instrumentation is recommended, causing significant expenditures and frustrating complications, that should not be ignored. In the article, we performed a literature review and summarized the evidence by subheadings to unravel the cons of surgical intervention for lumbar disc herniation. There are tetrad critical issues about surgical treatment of lumbar disc herniation, i.e., favorable natural history, insufficient evidence in a recommendation of fusion surgery for patients, metallosis, and implant removal. Firstly, accumulating evidence reveals immune privilege and auto-immunity hallmarks of human lumbar discs within the closed niche. Progenitor cells within human discs further expand the capacity with the endogenous repair. Clinical watchful follow-up studies with repeated diagnostic imaging reveal spontaneous resolution for lumbar disc herniation, even calcified tissues. Secondly, emerging evidence indicates long-term complications of lumbar fusion, such as adjacent segment disease, pseudarthrosis, implant failure, and sagittal spinal imbalance, which get increasing attention. Thirdly, systemic and local reactions (metallosis) for metal instrumentation have been noted with long-term health concerns and toxicity. Fourthly, the indications and timing for spinal implant removal have not reached a consensus. Other challenging issues include postoperative lumbar stiffness. The review provided evidence from a negative perspective for surgeons and patients who attempt to choose surgical treatment. Collectively, the emerging underlying evidence questions the benefits of traditional surgery for patients with lumbar disc herniation. Therefore, the long-term effects of surgery should be closely observed. Surgical decisions should be made prudently for each patient.

Long Non-Coding RNAs H19 and HOTAIR Implicated in Intervertebral Disc Degeneration

Objective: Intervertebral disc degeneration (IDD) is the major cause of low back pain. We aimed to identify the key genes for IDD pathogenesis.

Methods: An integrated analysis of microarray datasets of IDD archived in public Gene Expression Omnibus was performed. Bioinformatics analyses including identification of differentially expressed mRNAs/microRNAs/long non-coding RNAs (DEMs/DEMis/DELs), pathway enrichment, and competitive endogenous RNA (ceRNA) network construction were performed to give insights into the potential functions of differentially expressed genes (DEGs, including DEMs, DEMis, and DELs). The diagnostic value of DEMis in distinguishing IDD from normal controls was evaluated through receiver operating characteristic (ROC) analysis.

Results: DEGs were identified in IDD, including H19 and HOTAIR. In the DEMis–DEMs network of IDD, miR-1291, miR-4270, and miR-320b had high connectivity with targeted DEMs. Cell death biological processes and the JAK–STAT pathway were significantly enriched from targeted DEMs. The area under the curve (AUC) of 10 DEMs including miR-1273e, miR-623, miR-518b, and miR-1291 in ROC analysis was more than 0.8, which indicated that those 10 DEMs had diagnostic value in distinguishing IDD from normal individuals.

Conclusions: DELs H19 and HOTAIR were related to IDD pathogenesis. Cell death biological processes and the JAK–STAT pathway might play key roles in IDD development.

The involvement of immune system in intervertebral disc herniation and degeneration

Intervertebral disc (IVD) herniation and degeneration contributes significantly to low back pain (LBP), of which the molecular pathogenesis is not fully understood. Disc herniation may cause LBP and radicular pain, but not all LBP patients have disc herniation. Degenerated discs could be the source of pain, but not all degenerated discs are symptomatic. We previously found that disc degeneration and herniation accompanied by inflammation. We further found that anti-inflammatory molecules blocked immune responses, alleviated IVD degeneration and pain. Based on our recent findings and the work of others, we hypothesize that immune system may play a prominent role in the production of disc herniation or disc degeneration associated pain. While the nucleus pulposus (NP) is an immune-privileged organ, the damage of the physical barrier between NP and systemic circulation, or the innervation and vascularization of the degenerated NP, on one hand exposes NP as a foreign antigen to immune system, and on the other hand presents compression on the nerve root or dorsal root ganglion (DRG), which both elicit immune responses induced by immune cells and their mediators. The inflammation can remain for a long time at remote distance, with various types of cytokines and immune cells involved in this pain-inducing process. In this review, we aim to revisit the autoimmunity of the NP, immune cell infiltration after break of physical barrier, the inflammatory activities in the DRG and the generation of pain. We also summarize the involvement of immune system, including immune cells and cytokines, in degenerated or herniated IVDs and affected DRG.

The Mechanism and Function of miRNA in Intervertebral Disc Degeneration

Intervertebral disc degeneration (IDD) disease has been considered as the main cause of low back pain (LBP), which is a very common symptom and the leading cause of disability worldwide today. The pathological mechanism of IDD remains quite complicated, and genetic, developmental, biochemical, and biomechanical factors all contribute to the development of the disease. There exists no effective, non-surgical treatment for IDD nowadays, which is largely related to the lack of knowledge of the specific mechanisms of IDD, and the lack of effective specific targets. Recently, non-coding RNA, including miRNA, has been recognized as an important regulator of gene expression. Current studies on the effects of miRNA in IDD have confirmed that a variety of miRNAs play a crucial role in the process of IDD via nucleus pulposus cells (NPC) apoptosis, abnormal proliferation, inflammatory factors, the extracellular matrix (ECM) degradation, and annulus fibrosus (AF) degeneration. In the past 10 years, research on miRNA has been quite active in IDD. This review summarizes the current research progression of miRNA in the IDD and puts forward some prospects and challenges on non-surgical treatment for IDD.

Causes of and Molecular Targets for the Treatment of Intervertebral Disc Degeneration: A Review

Intervertebral disc degeneration (IVDD) is a pathological condition that can lead to intractable back pain or secondary neurological deficits. There is no fundamental cure for this condition, and current treatments focus on alleviating symptoms indirectly. Numerous studies have been performed to date, and the major strategy for all treatments of IVDD is to prevent cell loss due to programmed or regulated cell death. Accumulating evidence suggests that several types of cell death other than apoptosis, including necroptosis, pyroptosis, and ferroptosis, are also involved in IVDD. In this study, we discuss the molecular pathway of each type of cell death and review the literature that has identified their role in IVDD. We also summarize the recent advances in targeted therapy at the RNA level, including RNA modulations through RNA interference and regulation of non-coding RNAs, for preventing cell death and subsequent IVDD. Therefore, we review the causes and possible therapeutic targets for RNA intervention and discuss the future direction of this research field.

Autophagy and apoptosis cascade: which is more prominent in neuronal death?

Autophagy and apoptosis are two crucial self-destructive processes that maintain cellular homeostasis, which are characterized by their morphology and regulated through signal transduction mechanisms. These pathways determine the fate of cellular organelle and protein involved in human health and disease such as neurodegeneration, cancer, and cardiovascular disease. Cell death pathways share common molecular mechanisms, such as mitochondrial dysfunction, oxidative stress, calcium ion concentration, reactive oxygen species, and endoplasmic reticulum stress. Some key signaling molecules such as p53 and VEGF mediated angiogenic pathway exhibit cellular and molecular responses resulting in the triggering of apoptotic and autophagic pathways. Herein, based on previous studies, we describe the intricate relation between cell death pathways through their common genes and the role of various stress-causing agents. Further, extensive research on autophagy and apoptotic machinery excavates the implementation of selective biomarkers, for instance, mTOR, Bcl-2, BH3 family members, caspases, AMPK, PI3K/Akt/GSK3β, and p38/JNK/MAPK, in the pathogenesis and progression of neurodegenerative diseases. This molecular phenomenon will lead to the discovery of possible therapeutic biomolecules as a pharmacological intervention that are involved in the modulation of apoptosis and autophagy pathways. Moreover, we describe the potential role of micro-RNAs, long non-coding RNAs, and biomolecules as therapeutic agents that regulate cell death machinery to treat neurodegenerative diseases. Mounting evidence demonstrated that under stress conditions, such as calcium efflux, endoplasmic reticulum stress, the ubiquitin-proteasome system, and oxidative stress intermediate molecules, namely p53 and VEGF, activate and cause cell death. Further, activation of p53 and VEGF cause alteration in gene expression and dysregulated signaling pathways through the involvement of signaling molecules, namely mTOR, Bcl-2, BH3, AMPK, MAPK, JNK, and PI3K/Akt, and caspases. Alteration in gene expression and signaling cascades cause neurotoxicity and misfolded protein aggregates, which are characteristics features of neurodegenerative diseases. Excessive neurotoxicity and misfolded protein aggregates lead to neuronal cell death by activating death pathways like autophagy and apoptosis. However, autophagy has a dual role in the apoptosis pathways, i.e., activation and inhibition of the apoptosis signaling. Further, micro-RNAs and LncRNAs act as pharmacological regulators of autophagy and apoptosis cascade, whereas, natural compounds and chemical compounds act as pharmacological inhibitors that rescue neuronal cell death through inhibition of apoptosis and autophagic cell death.

MicroRNAs and the DNA damage response: How is cell fate determined?

It is becoming clear that the DNA damage response orchestrates an appropriate response to a given level of DNA damage, whether that is cell cycle arrest and repair, senescence or apoptosis. It is plausible that the alternative regulation of the DNA damage response (DDR) plays a role in deciding cell fate following damage. MicroRNAs (miRNAs) are associated with the transcriptional regulation of many cellular processes. They have diverse functions, affecting, presumably, all aspects of cell biology. Many have been shown to be DNA damage inducible and it is conceivable that miRNA species play a role in deciding cell fate following DNA damage by regulating the expression and activation of key DDR proteins. From a clinical perspective, miRNAs are attractive targets to improve cancer patient outcomes to DNA-damaging chemotherapy. However, cancer tissue is known to be, or to become, well adapted to DNA damage as a means of inducing chemoresistance. This frequently results from an altered DDR, possibly owing to miRNA dysregulation. Though many studies provide an overview of miRNAs that are dysregulated within cancerous tissues, a tangible, functional association is often lacking. While miRNAs are well-documented in 'ectopic biology', the physiological significance of endogenous miRNAs in the context of the DDR requires clarification. This review discusses miRNAs of biological relevance and their role in DNA damage response by potentially 'fine-tuning' the DDR towards a particular cell fate in response to DNA damage. MiRNAs are thus potential therapeutic targets/strategies to limit chemoresistance, or improve chemotherapeutic efficacy.

miR-489-3p overexpression inhibits lipopolysaccharide-induced nucleus pulposus cell apoptosis, inflammation and extracellular matrix degradation via targeting Toll-like receptor 4

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

MicroRNA-338-3p as a novel therapeutic target for intervertebral disc degeneration

Recent studies have demonstrated the pivotal role played by microRNAs (miRNAs) in the etiopathogenesis of intervertebral disc degeneration (IDD). The study of miRNA intervention in IDD models may promote the advancement of miRNA-based therapeutic strategies. The aim of the current study was to investigate whether intradiscal delivery of miRNA can attenuate IDD development. Our results showed that miR-338-3p expression was significantly increased in the nucleus pulposus (NP) of patients with IDD. Moreover, there was a statistically significant positive correlation between the expression level of miR-338-3p and the severity of IDD. Our functional studies showed that miR-338-3p significantly influenced the expression of extracellular matrix synthesis genes, as well as the proliferation and apoptosis of NP cells. Mechanistically, miR-338-3p aggravated IDD progression by directly targeting SIRT6, a negative regulator of the MAPK/ERK pathway. Intradiscal injection of antagomir-338-3p significantly decelerated IDD development in mouse models. Our study is the first to identify miR-338-3p as a mediator of IDD and thus may be a promising target for rescuing IDD.

Therapeutic effect of co-culture of rat bone marrow mesenchymal stem cells and degenerated nucleus pulposus cells on intervertebral disc degeneration

BACKGROUND

After non-contact co-culture of bone marrow mesenchymal stem cells (BMSCs) with nucleus pulposus cells (NPCs), exosomes secreted by BMSCs were able to ameliorate the degree of disc degeneration. The reason for this is, at least in part, that exosomes from BMSCs achieve by affecting the level of autophagy in NPCs, while the components in exosomes are diverse and their specific mechanism of action is still unclear.

PURPOSE

Here, we aimed to explore the therapeutic effect of co-culture of BMSCs and NPCs on NPCs and explore its specific mechanism of action.

STUDY DESIGN/SETTING

In vitro study.

METHODS

Rat NPCs and BMSCs were isolated and cultured in vitro. The serum deprivation experiment (using oxygen, glucose, and serum deprivation [OGD]) simulates the pathological state of low blood supply of the intervertebral disc in vivo. We used apoptotic cell staining and flow cytometry to study the effect of BMSCs on the apoptosis rate of rat NPCs, and the apoptotic proteins active-caspase-3, active-caspase-9, autophagy marker proteins LC3 and Beclin 1 were further detected using Western blot analysis. The expression levels of the pro-apoptotic protein Bax and the apoptosis-inhibiting protein Bcl2 were measured. The differentially expressed miRNAs were screened in a gene expression profiling chip. Then qRT-PCR was used to detect the effect of different treatment methods on miR-155 expression. The effect of anti-miR-155 antibodies on autophagy was studied by flow cytometry and transmission electron microscopy. A luciferase reporter assay was used to study the direct interaction between miR-155 and BACH1 mRNA, which was analyzed by TargetScan software, and the results were verified by Western blotting.

RESULTS

Compared with the OGD group, the expression level of miR-155 and the NPC autophagy level significantly increased; the HO-1 protein expression increased; and the Bach1 protein expression, degeneration index, and apoptosis index all significantly decreased in the co-culture group. After BMSCs transfected with anti-miR-155 were co-cultured with NPCs, the miR-155 expression in the cells was significantly reduced, the HO-1 protein expression and the level of cell autophagy was reduced. However, Bach1 protein expression, NPC degeneration index, and apoptosis index increased. After being inhibited by the autophagy inhibitor wortmannin, the cell degeneration index and apoptosis rate significantly improved.

CONCLUSION

In the OGD model, BMSCs can significantly increase the viability, the level of autophagy, and reduce the level of apoptosis in rat NPCs. BMSC exosomes increase miR-155 expression in NPCs, which targets Bach1 and in turn upregulates HO-1 expression, activates autophagy in NPCs, inhibits the apoptosis level, and improves intervertebral disc degeneration.

CLINICAL SIGNIFICANCE

Our experiment shows that it is maybe feasible to treat disc degeneration with drugs. At the same time, compared with BMSC injection method of treatment, side effects of drug therapy are smaller, and can be controlled, it also provides a new way for intervertebral disc degeneration drug treatment.

HIF-1α-Mediated miR-623 Regulates Apoptosis and Inflammatory Responses of Nucleus Pulposus Induced by Oxidative Stress via Targeting TXNIP

Excessive apoptosis and inflammatory responses of nucleus pulposus (NP) cells induced by oxidative stress contribute to intervertebral disc degeneration (IVDD). Though some microRNAs are associated with IVDD, the specific microRNA that can mediate apoptotic and inflammatory responses of NP cells induced by oxidative stress synchronously still needs further identification. Here, we find that microRNA-623 (miR-623) is downregulated in IVDD and its expression is regulated by hypoxia-inducible factor-1α (HIF-1α) under oxidative stress conditions. Mechanistically, HIF-1α is observed to promote miR-623 expression by directly binding to its promoter region (-1,994/-1,987 bp). Functionally, miR-623 is found to work as an intermediator in alleviating apoptosis and inflammatory responses of NP cells induced by oxidative stress via regulating thioredoxin-interacting protein (TXNIP) expression by directly targeting its 3'-untranslated region (3'-UTR). Thus, on elucidating the expression and functional mechanisms of miR-623, our study suggests that miR-623 can be a valuable therapeutic target for treating oxidative stress-induced IVDD.

Multiple interactions between melatonin and non-coding RNAs in cancer biology

The melatonin hormone secreted by the pineal gland is involved in physiological functions such as growth and maturation, circadian cycles, and biological activities including antioxidants, anti-tumor, and anti-ischemia. Melatonin not only interacts with proteins but also has functional effects on regulatory RNAs such as long non-coding RNAs (lncRNAs) and microRNAs (miRNAs). In this study, we overview various physiological and pathological conditions affecting melatonin through lncRNA and miRNA. The information compiled herein will serve as a solid foundation to formulate ideas for future mechanistic studies on melatonin. It will also provide a chance to more clarify the emerging functions of the non-coding transcriptome.

Role of microRNA-129 in cancer and non-cancerous diseases (Review)

An increasing number of studies indicate that microRNAs (miRNAs/miRs) are involved in diverse biological signaling pathways and play important roles in the progression of various diseases, including both oncological and non-oncological diseases. These small non-coding RNAs can block translation, resulting in a low expression level of target genes. miR-129 is an miRNA that has been the focus of considerable research in recent years. A growing body of evidence shows that the miR-129 family not only functions in cancer, including osteosarcoma, nasopharyngeal carcinoma, and ovarian, prostate, lung, breast and colon cancer, but also in non-cancerous diseases, including heart failure (HF), epilepsy, Alzheimer's disease (AD), obesity, diabetes and intervertebral disc degeneration (IVDD). It is therefore necessary to summarize current research progress on the role of miR-129 in different diseases. The present review includes an updated summary of the mechanisms of the miR-129 family in oncological and non-oncological diseases. To the best of our knowledge, this is the first review focusing on the role of miR-129 in non-cancerous diseases such as obesity, HF, epilepsy, diabetes, IVDD and AD.

circARL15 Plays a Critical Role in Intervertebral Disc Degeneration by Modulating miR-431-5p/DISC1

Background

Intervertebral disk degeneration (IDD) is a serious public health problem associated with genetic and environmental factors. However, the pathogenic factors involved and the pathological mechanism of this disease still remain enigmatic.

Methods

The associated microarray was downloaded and further analyzed using statistical software R. The competing endogenous RNA (ceRNA) co-expression network was constructed to measure the meaningful correlated expression of differentially expressed genes. We further measured the expression of circARL15/miR-431-5p/DISC1 in IDD tissues. Cell proliferation and apoptosis were detected in NP cells transfected with a circARL15 overexpression plasmid and miR-431-5p mimics. The expression of DISC1 was detected by immunohistochemistry and Western blot analysis.

Results

Within the ceRNA network, circARL15 is the most differentially expressed circular RNA. circARL15 was down-regulated in IDD and was negatively correlated with miR-431-5p and positively associated with DISC1. miR-431-5p was found to bind directly to circARL15 and DISC1. circARL15 inhibited nucleus pulposus cell apoptosis but promoted nucleus pulposus cell proliferation by targeting the miR-431-5p/DISC1 signaling pathway.

Conclusion

circARL15/miR-431-5p/DISC1 is involved in the pathogenesis of IDD, which might be helpful in determining the diagnostic biomarkers and providing potential therapeutic targets for patients with IDD.

Matrix Metalloproteinase Inspired Therapeutic Strategies for Bone Diseases

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

Role of microRNAs in intervertebral disc degeneration (Review)

The incidence of lower back pain caused by intervertebral disc degeneration (IDD) is gradually increasing. IDD not only affects the quality of life of the patients, but also poses a major socioeconomic burden. There is currently no optimal method for delaying or reversing IDD, mainly due to its unknown pathogenesis. MicroRNAs (miRNAs/miRs) participate in the development of a number of diseases, including IDD. Abnormal expression of miRNAs in the intervertebral disc is implicated in various pathological processes underlying the development of IDD, including nucleus pulposus (NP) cell (NPC) proliferation, NPC apoptosis, extracellular matrix remodeling, inflammation and cartilaginous endplate changes, among others. The focus of the present review was the advances in research on the involvement of miRNAs in the mechanism underlying IDD. Further research is expected to identify markers for early diagnosis of IDD and new targets for delaying or reversing IDD.

The Role of miR-31-5p in the Development of Intervertebral Disc Degeneration and Its Therapeutic Potential

Intervertebral disc degeneration (IDD) refers to the abnormal response of cell-mediated progressive structural failure. In order to understand the molecular mechanism of the maintenance and destruction of the intervertebral disc, new IDD treatment methods are developed. Here, we first analyzed the key regulators of IDD through microRNAs microarrays. Then, the level of miR-31-5p was evaluated by qRT-PCR. The association between miR-31-5p and Stromal cell-derived factor 1 (SDF-1)/CXCR7 axis was assessed by 3′-untranslated region (UTR) cloning and luciferase assay. The apoptosis of cells under different treatments was evaluated by flow cytometer. The cell proliferation was assessed by EdU assay. After IDD model establishment, the discs of mice tail were harvested for histological and radiographic evaluation in each group. Finally, the protein levels of SDF-1, CXCR7, ADAMTS-5, Col II, Aggrecan, and MMP13 were assessed by western blot. The results show that miR-31-5p is a key regulator of IDD and its level is down-regulated in IDD. Overexpression of miR-31-5p facilitates nucleus pulposus cell proliferation, inhibits apoptosis, facilitates ECM formation, and inhibits the level of matrix degrading enzymes in NP cells. The SDF-1/CXCR7 axis is the direct target of miR-31-5p. miR-31-5p acts on IDD by regulating SDF-1/CXCR7. In vitro experiments further verified that the up-regulation of miR-31-5p prevented the development of IDD. In conclusion, overexpression of miR-31-5p can inhibit IDD by regulating SDF-1/CXCR7.

LncRNA LINC00324 is upregulated in intervertebral disk degeneration and upregulates FasL in nucleus pulposus cells

BACKGROUND

It has been reported that long intergenic non-protein-coding RNA 324 (LINC00324) promotes liver cancer by upregulating Fas ligand (FasL), which is a major player in intervertebral disk degeneration (IDD), indicating the involvement of LINC00324 in IDD. This study was carried out to investigate the interaction between LINC00324 and FasL in IDD.

METHODS

Plasma samples were collected from both IDD (n = 60) and healthy controls (n = 60). The expression of LINC00324 and FasL in plasma was determined by RT-qPCR. The interactions between LINC00324 and FasL in nucleus pulposus (NP) cells were analyzed by overexpression experiments.

RESULTS

LINC00324 and FasL were upregulated in IDD patients, and they were positively correlated. After treatment, the expression levels of FasL and LINC00324 were significantly decreased. In NP cells, overexpression of LINC00324 increased the expression of FasL at both mRNA and protein levels, while overexpression of FasL did not affect the expression of LINC00324.

CONCLUSION

LINC00324 may upregulate FasL in IDD to promote disease progression.