Roles of Cell Cyle Regulators Cyclin D1, CDK4, and p53 in Knee Osteoarthritis

Paeoniflorin, the Main Monomer Component of Paeonia lactiflora, Exhibits Anti-inflammatory Properties in Osteoarthritis Synovial Inflammation

OBJECTIVE

To explore the mechanism of paeoniflorin (PF) on osteoarthritis (OA) synovial inflammation from network pharmacology to experimental pharmacology.

METHODS

Targets of OA were constructed by detecting the database of network database platforms (Therapeutic Target database, DrugBank and GeneCards), and the targets of PF were constructed by PubChem and Herbal Ingredients' Targets database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of these co-targeted genes were conducted via Database for Annotation, Visualization, and Integrated Discovery (DAVID) database, and protein-protein interaction (PPI) networks were conducted via the search tool for the retrieval of interacting genes (STRING) database. Cell counting kit-8 (CCK-8) assay was performed to assess the potential toxicity of PF on human OA fibroblast-like synoviocytes (FLS), quantitative real-time polymerase chain reaction (qPCR), enzyme-linked immunosorbent assay (ELISA) and Western blot were used to verify the potential mechanism of PF in synovial inflammation.

RESULTS

Twenty-six co-targeted genes were identified. GO enrichment results showed that these co-targeted genes were most likely localized in the cytoplasm, and the biological processes mainly involved 'cellular response to hypoxia' 'lipopolysaccharide (LPS)-mediated signaling pathway' and 'positive regulation of gene expression'. KEGG pathway analysis indicated that these co-targeted genes may function through pathways associated with 'hypoxia-inducible factor-1 (HIF-1) signaling pathway' and 'tumor-necrosis factor (TNF) signaling pathway'. The PPI network showed that the top 3 hub genes were TP53, TNF, and CASP3. Molecular docking results showed that PF was well docking with TNF. CCK-8 showed no potential toxicity of 10, 20 and 50 µmol/L PF on human OA FLS. And PF significantly decreased the expression levels of interleukin-1 β, interleukin-6, TNF-α matrix metalloproteinase 13 (MMP13), and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) and TNF-α in LPS-induced OA FLS.

CONCLUSION

PF exhibited potent anti-inflammatory effect in OA synovial inflammation.

Mechanical gated ion channel Piezo1: Function, and role in macrophage inflammatory response

Macrophages are present in many mechanically active tissues and are often subjected to varying degrees of mechanical stimulation. Macrophages play a crucial role in resisting pathogen invasion and maintaining tissue homeostasis. Piezo-type mechanosensitive channel component 1 (Piezo1) is the main cation channel involved in the rapid response to mechanical stimuli in mammals. This channel plays a crucial role in controlling blood pressure and motor performance and regulates urinary osmotic pressure and epithelial cell proliferation and division. In recent years, numerous studies have shown that in macrophages, Piezo1 not only plays a role in regulating the aforementioned physiological processes but also participates in multiple pathological processes such as inflammation and cancer. In this review, we summarize the research progress on Piezo1-mediated regulation of macrophage-mediated inflammatory responses through downstream signalling pathways and the aerobic glycolysis pathway.

Promoting the proliferation of osteoarthritis chondrocytes by resolvin D1 regulating the NLRP3/caspase-1 signaling pathway

Osteoarthritis (OA) is a degenerative joint disease commonly found in middle-aged and older people. Chondrocytes are the only cells in joint cartilage that are difficult to heal after pyroptosis, and they will aggravate the wear and tear of joint cartilage and affect the progression of OA. Pyroptosis is a novel form of programmed cell death, and the classical pyroptosis pathway is a programmed cell death pattern mediated by inflammatory cysteine protease-1. Activation of NLRP3 leads to activation and cleavage of caspase-1 precursors, which in turn leads to activation and cleavage of GSDMD proteins and the release of proinflammatory factors. Resolvin D1 (RvD1) is a specialized pro-resolving mediator (SPM) derived from omega-3 unsaturated fatty acids that reduces inflammation and catabolic responses in OA chondrocytes. However, it is unclear whether RvD1 promotes OA chondrocyte proliferation and thus joint cartilage repair. Our results show that RvD1 regulates the NLRP3/caspase-1 signaling pathway by inhibiting the expression of caspase-1, promoting the proliferation of OA chondrocytes, promoting the repair of articular cartilage in rats and delaying the progression of osteoarthritis.

Osteoarthritis related epigenetic variations in miRNA expression and DNA methylation

Osteoarthritis (OA) is chronic arthritis characterized by articular cartilage degradation. However, a comprehensive regulatory network for OA-related microRNAs and DNA methylation modifications has yet to be established. Thus, we aimed to identify epigenetic changes in microRNAs and DNA methylation and establish the regulatory network between miRNAs and DNA methylation. The mRNA, miRNA, and DNA methylation expression profiles of healthy or osteoarthritis articular cartilage samples were downloaded from Gene Expression Omnibus (GEO) database, including GSE169077, GSE175961, and GSE162484. The differentially expressed genes (DEGs), differentially expressed miRNAs (DEMs), and differentially methylated genes (DMGs) were analyzed by the online tool GEO2R. DAVID and STRING databases were applied for functional enrichment analysis and protein-protein interaction (PPI) network. Potential therapeutic compounds for the treatment of OA were identified by Connectivity map (CMap) analysis. A total of 1424 up-regulated DEGs, 1558 down-regulated DEGs, 5 DEMs with high expression, 6 DEMs with low expression, 1436 hypermethylated genes, and 455 hypomethylated genes were selected. A total of 136 up-regulated and 65 downregulated genes were identified by overlapping DEGs and DEMs predicted target genes which were enriched in apoptosis and circadian rhythm. A total of 39 hypomethylated and 117 hypermethylated genes were obtained by overlapping DEGs and DMGs, which were associated with ECM receptor interactions and cellular metabolic processes, cell connectivity, and transcription. Moreover, The PPI network showed COL5A1, COL6A1, LAMA4, T3GAL6A, and TP53 were the most connective proteins. After overlapping of DEGs, DMGs and DEMs predicted targeted genes, 4 up-regulated genes and 11 down-regulated genes were enriched in the Axon guidance pathway. The top ten genes ranked by PPI network connectivity degree in the up-regulated and downregulated overlapping genes of DEGs and DMGs were further analyzed by the CMap database, and nine chemicals were predicted as potential drugs for the treatment of OA. In conclusion, TP53, COL5A1, COL6A1, LAMA4, and ST3GAL6 may play important roles in OA genesis and development.

Role of Wnt signaling pathway in joint development and cartilage degeneration

Osteoarthritis (OA) is a prevalent musculoskeletal disease that affects approximately 500 million people worldwide. Unfortunately, there is currently no effective treatment available to stop or delay the degenerative progression of joint disease. Wnt signaling pathways play fundamental roles in the regulation of growth, development, and homeostasis of articular cartilage. This review aims to summarize the role of Wnt pathways in joint development during embryonic stages and in cartilage maintenance throughout adult life. Specifically, we focus on aberrant mechanical loading and inflammation as major players in OA progression. Excessive mechanical load activates Wnt pathway in chondrocytes, resulting in chondrocyte apoptosis, matrix destruction and other osteoarthritis-related changes. Additionally, we discuss emerging Wnt-related modulators and present an overview of emerging treatments of OA targeting Wnt signaling. Ultimately, this review provides valuable insights towards discovering new drugs or gene therapies targeting Wnt signaling pathway for diagnosing and treating osteoarthritis and other degenerative joint diseases.

Intergenic Interactions of SBNO1, NFAT5 and GLT8D1 Determine the Susceptibility to Knee Osteoarthritis among Europeans of Russia

This study was conducted to examine the associations between genome-wide association studies (GWAS)-important single nucleotide polymorphisms (SNPs) and knee osteoarthritis (KOA) among Europeans of Russia. The present replicative study ("patient-control" design has been used) was carried out on 1000 DNA samples from KOA (n = 500) and KOA-free (n = 500) participants. Ten GWAS-important for KOA SNPs of eight candidate genes (LYPLAL1, GNL3, GLT8D1, SBNO1, WWP2, NFAT5, TGFA, GDF5) were studied. To assess the link between SNPs and KOA susceptibility, logistic regression (to establish independent SNP effects) and MB-MDR (to identify SNP-SNP interactions) were used. As a result of this genetic analysis, the associations of individual SNPs with KOA have not been proven. Eight loci out of ten tested SNPs interacted with each other (within twelve genetic models) and determined susceptibility to KOA. The greatest contribution to the disease development were made by three polymorphisms/genes such as rs6976 (C>T) GLT8D1, rs56116847 (G>A) SBNO1, rs6499244 (T>A) NFAT5 (each was included in 2/3 [8 out 12] KOA-responsible genetic interaction models). A two-locus epistatic interaction of rs56116847 (G >A) SBNO1 × rs6499244 (T>A) NFAT5 determined the maximum percentage (0.86%) of KOA entropy. KOA-associated SNPs are regulatory polymorphisms that affect the expression/splicing level, epigenetic modification of 72 genes in KOA-pathogenetically significant organs such as skeletal muscles, tibial arteries/nerves, thyroid, adipose tissue, etc. These putative KOA-effector genes are mainly involved in the organization/activity of the exoribonuclease complex and antigen processing/presentation pathways. In conclusion, KOA susceptibility among Europeans of Russia is mediated by intergenic interactions (but not the main effects) of GWAS-important SNPs.

A Study on the Potential Mechanism of Shujin Dingtong Recipe against Osteoarthritis Based on Network Pharmacology and Molecular Docking

Background. With the aging of the social population, Osteoarthritis (OA) has already become a vital health and economic problem globally. Shujin Dingtong recipe (SJDTR) is an effective formula to treat OA in China. Although studies have shown that SJDTR can significantly alleviate OA symptoms, its mechanism still remains unclear. Purpose. This study is aimed at investigating the potential mechanism of SJDTR for the treatment of OA based on network pharmacology and molecular docking. Methods. Main ingredients of SJDTR were retrieved from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database. OA disease targets were obtained from the Gene Expression Omnibus (GEO) database. The overlapped targets and signaling pathways were explored using Protein-Protein Interaction (PPI) network, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG). Following this, the core targets were employed to dock with corresponding components via molecular docking in order to further explore the mechanism of SJDTR in the treatment of OA. Results. From network pharmacology, we found 100 active components of SJDTR, 31 drug and OA-related targets, 1161 GO items, and 91 signaling pathways. Based on the analysis with PPI network and molecular docking, TP53, CCNB1, and MMP-2 were selected for the core targets of SJDTR against OA. Molecular docking demonstrated that Quercetin, Baicalein, and Luteolin, had good binding with the TP53, CCNB1, and MMP-2 protein, respectively. Conclusion. To conclude, our study suggested the main ingredients of SJDTR might alleviate the progression of OA through multiple targets and pathways. Additionally, network pharmacology and molecular docking, as new approaches, were adopted for systematically exploring the potential mechanism of SJDTR for the treatment of OA.

Mechanical force modulates macrophage proliferation via Piezo1-AKT-Cyclin D1 axis

Orthodontic tooth movement (OTM) is induced by biomechanical stimuli and facilitated by periodontal tissue remodeling, where multiple immune cells participate in this progression. It has been demonstrated that macrophage is essential for mechanical force-induced tissue remodeling. In this study, we first found that mechanical force significantly induced macrophage proliferation in human periodontal samples and murine OTM models. Yet, how macrophages perceive mechanical stimuli and thereby modulate their biological behaviors remain elusive. To illustrate the mechanisms of mechanical force-induced macrophage proliferation, we subsequently identified Piezo1, a novel mechanosensory ion channel, to modulate macrophage response subjected to mechanical stimuli. Mechanical force upregulates Piezo1 expression in periodontal tissues and cultured bone-marrow-derived macrophages (BMDMs). Remarkably, suppressing Piezo1 with GsMTx4 retarded OTM through reduced macrophage proliferation. Moreover, knockdown of Piezo1 effectively inhibited mechanical force-induced BMDMs proliferation. RNA sequencing was further performed to dissect the underlying mechanisms of Piezo1-mediated mechanotransduction utilizing mechanical stretch system. We revealed that Piezo1-activated AKT/GSK3β signaling was closely associated with macrophage proliferation upon mechanical stimuli. Importantly, Cyclin D1 (Ccnd1) was authenticated as a critical downstream factor of Piezo1 that facilitated proliferation by enhancing Rb phosphorylation. We generated genetically modified mice in which Ccnd1 could be deleted in macrophages in an inducible manner. Conditional ablation of Ccnd1 inhibited periodontal macrophage proliferation and therefore delayed OTM. Overall, our findings highlight that proliferation driven by mechanical force is a key process by which macrophages infiltrate in periodontal tissue during OTM, where Piezo1-AKT-Ccnd1 axis plays a pivotal role.

Long noncoding RNA H19 alleviates inflammation in osteoarthritis through interactions between TP53, IL-38, and IL-36 receptor

Aims

Osteoarthritis (OA) is a common degenerative joint disease characterized by chronic inflammatory articular cartilage degradation. Long noncoding RNAs (lncRNAs) have been previously indicated to play an important role in inflammation-related diseases. Herein, the current study set out to explore the involvement of lncRNA H19 in OA.

Methods

Firstly, OA mouse models and interleukin (IL)-1β-induced mouse chondrocytes were established. Expression patterns of IL-38 were determined in the synovial fluid and cartilage tissues from OA patients. Furthermore, the targeting relationship between lncRNA H19, tumour protein p53 (TP53), and IL-38 was determined by means of dual-luciferase reporter gene, chromatin immunoprecipitation, and RNA immunoprecipitation assays. Subsequent to gain- and loss-of-function assays, the levels of cartilage damage and proinflammatory factors were further detected using safranin O-fast green staining and enzyme-linked immunosorbent assay (ELISA) in vivo, respectively, while chondrocyte apoptosis was measured using Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL) in vitro.

Results

IL-38 was highly expressed in lentivirus vector-mediated OA mice. Meanwhile, injection of exogenous IL-38 to OA mice alleviated the cartilage damage, and reduced the levels of proinflammatory factors and chondrocyte apoptosis. TP53 was responsible for lncRNA H19-mediated upregulation of IL-38. Furthermore, it was found that the anti-inflammatory effects of IL-38 were achieved by its binding with the IL-36 receptor (IL-36R). Overexpression of H19 reduced the expression of inflammatory factors and chondrocyte apoptosis, which was abrogated by knockdown of IL-38 or TP53.

Conclusion

Collectively, our findings evidenced that upregulation of lncRNA H19 attenuates inflammation and ameliorates cartilage damage and chondrocyte apoptosis in OA by upregulating TP53, IL-38, and by activating IL-36R.

Cite this article: Bone Joint Res 2022;11(8):594–607.

Adipokine Signaling Pathways in Osteoarthritis

Osteoarthritis (OA) is a debilitating joint disease that affects millions of individuals. The pathogenesis of OA has not been fully elucidated. Obesity is a well-recognized risk factor for OA. Multiple studies have demonstrated adipokines play a key role in obesity-induced OA. Increasing evidence show that various adipokines may significantly affect the development or clinical course of OA by regulating the pro/anti-inflammatory and anabolic/catabolic balance, matrix remodeling, chondrocyte apoptosis and autophagy, and subchondral bone sclerosis. Several signaling pathways are involved but still have not been systematically investigated. In this article, we review the cellular and molecular mechanisms of adipokines in OA, and highlight the possible signaling pathways. The review suggested adipokines play important roles in obesity-induced OA, and exert downstream function via the activation of various signaling pathways. In addition, some pharmaceuticals targeting these pathways have been applied into ongoing clinical trials and showed encouraging results. However, these signaling pathways are complex and converge into a common network with each other. In the future work, more research is warranted to further investigate how this network works. Moreover, more high quality randomised controlled trials are needed in order to investigate the therapeutic effects of pharmaceuticals against these pathways for the treatment of OA. This review may help researchers to better understand the pathogenesis of OA, so as to provide new insight for future clinical practices and translational research.

Identifying the shared genes and KEGG pathways of Resolvin D1-targeted network and osteoarthritis using bioinformatics

Osteoarthritis (OA) is a common chronic degenerative disease characterized by the loss of articular cartilage, which causes loss of joint function and reduce quality of life. Resolvin D1 (RvD1) has shown interesting anti-inflammatory effects; however, the mechanism of action of RvD1 in OA remains unclear. The aim of this study was to investigate the potential mechanism of RvD1 in OA by bioinformatics and partial in vitro mechanisms. Here, 106 shared differentially expressed genes (DEGs) were identified based on the GSE82107, GSE55235, GSE55457 dataset; 700 DEGs were identified based on GSE169077. Enrichment analyses of these genes were then successively conducted. RvD1-targeted genes and KEGG pathways are identified by STITCH. 27 shared KEGG pathways were identified among RvD1-targeted pathways and OA. Furthermore, cell apoptosis assay, western blotting, real-time fluorescent quantitative PCR (qRT-PCR), enzyme linked immunosorbent assay (ELISA) were used to confirm the expression levels of the key genes of shared Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways between RvD1-targeted and OA in IL-1β treated rat knee chondrocytes. The results showed that RvD1-targeted pathways and the expression of nuclear p65, p53, and p-JNK were inhibited in the RvD1 group compared with the IL-1β group. Thus, the findings indicate that RvD1 may inhibit the development of OA through NF/kB, p53, MAPK/JNK, PI3K-AKT signaling pathways, and act as a treatment for OA.

Epigallocatechin Gallate Enhances Inhibition Effect of DDP on the Proliferation of Gastric Cancer BGC-823 Cells by Regulating p19Arf-p53-p21Cip1 Signaling Pathway

OBJECTIVE

To indicate the effect of Epigallocatechin gallate (EGCG) and Cisplatin (DDP) on proliferation of gastric cancer BGC-823 cells and the relative underlying mechanism.

METHODS

Cultured BGC-823 cells were treated by 5 μg/mL DDP, 25 μg/mL EGCG and combined 5 μg/mL DDP with 25 μg/mL EGCG, a blank group was used as control. Cell morphology was observed by 4',6-diamidino-2-phenylindole (DAPI) staining. The ability of cell proliferation was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)assay. The cell cloning rate was determined by colony formation assay. The ability of cell migration was detected by cell scratch test. The cell cycle distributions and apoptosis were analyzed by flow cytometry, The expression of p19Arf, p53, p21Cip1 mRNA was determined by RT-qPCR. The protein levels of p19Arf, p53, p21Cip1 were measured by Western blot.

RESULTS

Compared with DDP or EGCG treatment alone, EGCG combined with DDP treatment significantly caused nuclear shrinkage, reduced the proliferation rate, the ability of cell clone and migration. EGCG combined with DDP treatment caused cell cycle arrest in G1 phase in BGC-823 cells, increase of apoptosis (21.3%) vs EGCG (7.25%) and DDP (3.86%) single-use group (p <0.01), up-regulated gene and protein expressions of p19Arf, p53, p21Cip1 (p <0.01).

CONCLUSION

EGCG can enhance the effect of DDP on inhibiting BGC-823 cell proliferation and inducing apoptosis via activating the p19Arf-p53-p21Cip1 signaling pathway.

Downregulation of microRNA-29b by DNMT3B decelerates chondrocyte apoptosis and the progression of osteoarthritis via PTHLH/CDK4/RUNX2 axis

The correlation between DNA methyltransferases (DNMTs) and microRNAs (miRNAs) has been well-established, but its interaction in osteoarthritis (OA) has been barely clarified. This study aimed to analyze the relationship between DNMT3B and miR-29b as well as their implications in OA. Our results revealed that DNMT3B was downregulated while miR-29b was upregulated in OA cartilage tissues relative to normal cartilage tissues. Hypermethylation of specific CpG sites in the miR-29b promoter region induced by DNMT3B contributed to downregulation of miR-29b in OA chondrocytes. Furthermore, luciferase activity determination demonstrated that miR-29b targeted and negatively regulated the parathyroid hormone-like hormone (PTHLH). Moreover, the PTHLH upregulation induced by miR-29b methylation led to the enhancement of chondrocyte growth and suppression of their apoptosis and extracellular matrix degradation, which was achieved by the upregulation cyclin-dependent kinase 4 (CDK4) expression. Co-IP suggested that CDK4 induced ubiquitination of RUNX2, which could be enhanced by DNMT3B. In the OA mouse model induced by destabilization of the medial meniscus, overexpression of DNMT3B was observed to downregulate the expression of RUNX2 whereby preventing OA-induced loss of chondrocytes. Hence, the DNMT3B/miR-29b/PTHLH/CDK4/RUNX2 axis was found to be involved in the apoptosis of chondrocytes induced by OA, highlighting a novel mechanism responsible for OA progression.

Chondroprotective Effects of Combination Therapy of Acupotomy and Human Adipose Mesenchymal Stem Cells in Knee Osteoarthritis Rabbits via the GSK3β-Cyclin D1-CDK4/CDK6 Signaling Pathway

Adipose-derived stem cells (ASCs) are highly chondrogenic and can be used to treat knee osteoarthritis (KOA) by alleviating cartilage defects. Acupotomy, a biomechanical therapy guided by traditional Chinese medicine theory, alleviates cartilage degradation and is widely used in the clinic to treat KOA by correcting abnormal mechanics. However, whether combining acupotomy with ASCs will reverse cartilage degeneration by promoting chondrocyte proliferation in KOA rabbits is unknown. The present study aimed to investigate the effects of combination therapy of acupotomy and ASCs on chondrocyte proliferation and to determine the underlying mechanism in rabbits with KOA induced by knee joint immobilization for 6 weeks. After KOA modeling, five groups of rabbits (acupotomy, ASCs, acupotomy + ASCs, model and control groups) received the indicated intervention for 4 weeks. The combination therapy significantly restored the KOA-induced decrease in passive range of motion (PROM) in the knee joint and reduced the elevated serum level of cartilage oligomeric matrix protein (COMP), a marker for cartilage degeneration. Furthermore, magnetic resonance imaging (MRI) and scanning electron microscopy (SEM) images showed that the combination therapy inhibited cartilage injury. The combination therapy also significantly blocked increases in the mRNA and protein expression of glycogen synthase kinase-3β (GSK3β) and decreases in the mRNA and protein expression of cyclin D1/CDK4 and cyclin D1/CDK6 in cartilage. These findings indicated that the combination therapy mitigated knee joint immobility, promoted chondrocyte proliferation and alleviated cartilage degeneration in KOA rabbits, and these effects may be mediated by specifically regulating the GSK3β-cyclin D1-CDK4/CDK6 pathway.

Epigenetic regulation of chondrocyte hypertrophy and apoptosis through Sirt1/P53/P21 pathway in surgery-induced osteoarthritis

Sirt1 involved in cellular aging and aging-related diseases, including osteoarthritis (OA). Our previous study showed Sirt1 played a role in the pathogenesis of OA, however, the underlying mechanisms are still poorly elicited. In this study, we investigated the role of Sirt1 in epigenetically regulating P53/P21 pathway in a Sirt1 loss model. Sirt1 deletion male mice (n = 10) with destabilization of the medial meniscus (DMM) were used to observe its role on OA development. Then, the relationships between SIRT1 and P53 were detected by Coimmunoprecipitation (CoIP), and the gain-off function of P53 gene was indicated by P53 activators and inhibitors in vitro. Finally, human cartilage samples from patients with OA were collected. Sirt1 deletion mice displayed a spontaneous OA development, manifesting severe chondrocytes hypertrophy markers MMP13 and ADAMTS5, highly expressed P53 and P21. Strikingly, surgery-induced meniscus injury promoted the OA pathogenesis and apoptosis in Sirt1 deficient mice. Ultimately, our CoIP data demonstrated that Sirt1 directly interacted with P53 in vitro. However inhibition of P53 alleviated OA progression. We also observed that chondrocyte apoptosis and P53 increased in osteoarthritis (OA) progression with a declining expression of Sirt1 in human cartilage. Loss of Sirt1 in cartilage led to accelerated OA pathogenesis via aberrant activation of p53/p21 mediated senescence associated secretory phenotype, hypertrophy and apoptosis.

Searching for valuable differentially expressed miRNAs in postmenopausal osteoporosis by RNA sequencing

AIM

Postmenopausal osteoporosis is a systemic and chronic bone disease in women. In order to understand the pathological mechanism of postmenopausal osteoporosis, we aimed to find the potential differentially expressed miRNAs in the disease.

METHODS

Firstly, RNA sequencing was used to identify differentially expressed miRNAs, followed by the construction of the miRNA-target mRNA regulatory network. Then, Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes were used to analyze the biological function of target mRNAs. Finally, electronic validation of identified differentially expressed miRNAs and target mRNAs was performed.

RESULTS

A total of 33 differentially expressed miRNAs (18 upregulated and 15 downregulated miRNAs) and 6820 miRNA-mRNA pairs were identified. Among which, seven miRNAs with high degree including hsa-miR-17-5p, hsa-miR-1-3p, hsa-miR-193b-3p, hsa-miR-125b-5p, hsa-miR-10b-5p, hsa-miR-100-5p and hsa-miR-30a-3p were obtained in the miRNA-mRNA regulatory network. TGF-beta was the most significantly enriched signaling pathway of target mRNAs. The electronic validation result of hsa-miR-1-3p, hsa-miR-193b-3p, hsa-miR-10b-5p, hsa-miR-100-5p, hsa-miR-133b, hsa-miR-708-5p, CRK, RAB5C, CCND1 and PCYOX1 was consisted with the RNA sequencing analysis.

CONCLUSION

Dysfunctional miRNAs may play significant roles in postmenopausal osteoporosis.

Cyclin D1 regulates osteoarthritis chondrocyte apoptosis via WNT3/β-catenin signalling

Objective: Cyclin D1 was an important molecular involved in the pathological process of osteoarthritis (OA). The purpose of this study was to identify the effect and potential mechanism of Cyclin D1 for the proliferation and apoptosis of OA chondrocytes. Methods: We used polymerase chain reaction (PCR) method to identify the expression levels of Cyclin D1 and down-stream Wnt/β-catenin pathway-related genes in OA chondrocytes according to the grade of OA. Small interfering RNA (siRNA) or overexpression of Cyclin D1 were used to identify the role of Cyclin D1 in cell proliferation and apoptosis. Next, we used XAV-939 to inhibit the Wnt/β-catenin pathway and explore the relevant mechanism. Results: Cyclin D1 was significantly decreased with OA grade (p < .05). After siCyclin D1 transfection, the expression level of WNT3 and nuclear β-catenin were significantly increased, while Wnt10a and total β-catenin were not obviously changed. Co-cultured with XAV-939 and siCyclin D1 abolished the effects of siCyclin D1 on proliferation and apoptosis of OA chondrocytes (p < .05). Conclusions: Cyclin D1 regulated chondrocyte proliferation and apoptosis through Wnt3/β-catenin instead of Wnt10a/β-catenin signalling pathway.

Long Non-Coding RNA (LncRNA) CAIF is Downregulated in Osteoarthritis and Inhibits LPS-Induced Interleukin 6 (IL-6) Upregulation by Downregulation of MiR-1246

Background

Osteoarthritis (OA) affects about 40% of people older than 40 years of age, and the mechanism is not well understood. Long non-coding RNA (lncRNA) CAIF is a recently identified critical player in myocardial infarction, while its role in other human diseases is unclear. The present study aimed to investigate the role of CAIF in OA.

Material/Methods

Levels of CAIF in synovial fluid of OA patients (n=60) and healthy controls (n=60) were measuring by performing quantitative real-time polymerase chain reaction (qRT-PCR). MiR-1246 and interleukin (IL)-6 levels in synovial fluid were measured by performing qRT-PCR and enzyme-linked immunosorbent assay (ELISA), respectively. Cell apoptosis analysis was performed after CHON-001 cells were treated with 500 mg/mL lipopolysaccharide (LPS) for 24 hours.

Results

We found that CAIF in synovial fluid was downregulated in OA patients and inversely correlated with miR-1246 and IL-6. Downregulated CAIF distinguished OA patients from healthy controls. In cells of chondrogenic cell line CHON-001, CAIF overexpression mediated the inhibited expression of miR-1246 and secretion of IL-6, while miR-1246 overexpression reduced the effects of CAIF overexpression on IL-6 secretion. In addition, CAIF overexpression inhibited the apoptosis of CHON-001 cells under LPS treatment, while miR-1246 overexpression attenuated the effects of CAIF overexpression.

Conclusions

Therefore, CAIF may downregulate miR-1246 to improve OA.

Identification of key gene modules and transcription factors for human osteoarthritis by weighted gene co-expression network analysis

Osteoarthritis (OA) is one of the most prevalent causes of joint disease. However, the pathological mechanisms of OA have remained to be completely elucidated, and further investigation into the underlying mechanisms of OA development and the identification of novel therapeutic targets are urgently required. In the present study, the dataset GSE114007 was downloaded from the Gene Expression Omnibus database. Based on weighted gene co-expression network analysis (WGCNA) and the identification of differentially expressed genes (DEGs), the microarray data were further analyzed to identify hub genes, key transcription factors (TFs) and pivotal signaling pathways involved in the pathogenesis of OA. A total of 1,898 genes were identified to be differentially expressed between OA samples and normal samples. Based on WGCNA, the present study identified 5 hub modules closely associated with OA, and the potential key TFs for hub modules were further explored based on CisTargetX. The results demonstrated that B-Cell Lymphoma 6, Myelin Gene Expression Factor 2, Activating Transcription Factor 3, CCAAT Enhancer Binding Protein γ, Nuclear Factor Interleukin-3-Regulated, FOS Like Antigen-2, FOS-Like Antigen-1, Fos Proto-Oncogene, JunD Proto-Oncogene, Transcription Factor CP2 Like 1, RELA proto-oncogene NF-kB subunit, SRY-box transcription factor 3, V-Ets Avian Erythroblastosis Virus E26 Oncogene Homolog 2, Interferon Regulatory Factor 4 and REL proto-oncogene, NF-kB subunit were the potential key TFs. In addition, osteoclast differentiation, FoxO, MAPK and PI3K/Akt signaling pathways were revealed to be imperative for the pathogenesis of OA, as these 4 pivotal signaling pathways were observed to be tightly linked through 4 key TFs Fos Proto-Oncogene, JUN, JunD Proto-Oncogene and MYC, and 4 DEGs Vascular Endothelial Growth Factor A, Growth Arrest and DNA Damage Inducible α, Growth Arrest and DNA Damage Inducible β and Cyclin D1. The present study identified a set of potential key genes and signaling pathways, and provided an important opportunity to advance the current understanding of OA.

Exploring the Key Genes and Pathways of Osteoarthritis in Knee Cartilage in a Rat Model Using Gene Expression Profiling

PURPOSE

To compare differentially expressed genes (DEGs) mediating osteoarthritis (OA) in knee cartilage and in normal knee cartilage in a rat model of OA and to identify their impact on molecular pathways associated with OA.

MATERIALS AND METHODS

A gene expression profile was downloaded from the Gene Expression Omnibus database. Analysis of DEGs was carried out using GEO2R. Enrichment analyses were performed on the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway using the Search Tool for the Retrieval of Interacting Genes database (http://www.string-db.org/). Subsequently, the regulatory interaction network of OA-associated genes was visualized using Cytoscape software (version 3.4.0; www.cytoscape.org).

RESULTS

In the gene expression profile GSE103416, a total of 99 DEGs were identified. Among them, 76 DEGs (76.77%) were overexpressed, and the remaining 23 DEGs (23.23%) were underexpressed. GO and pathway enrichment analyses of target genes were performed. Using gene-gene interaction network analysis, relevant core genes, including MET, UBB, GNAI3, and GNA13, were shown to hold a potential relationship with the development of OA in cartilage. Using quantitative real-time PCR, the Gna13/cGMP-PKG signaling pathway was identified as a potential research target for therapy and for further understanding the development of OA.

CONCLUSION

The results of the present study provide a comprehensive understanding of the roles of DEGs in knee cartilage in relation to the development of OA.

Identification of key genes in rheumatoid arthritis and osteoarthritis based on bioinformatics analysis

Rheumatoid arthritis (RA) and osteoarthritis (OA) comprise the most common forms of arthritis. The aim of this study was to identify differentially expressed genes (DEGs) and associated biological processes between RA and OA using a bioinformatics approach to elucidate their potential pathogenesis.The gene expression profiles of the GSE55457 datasets, originally produced through use of the high-throughput Affymetrix Human Genome U133A Array, were downloaded from the Gene Expression Omnibus (GEO) database. The GSE55457 dataset contains information from 33 samples, including 10 normal control (NC) samples, 13 RA samples, and 10 OA samples. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analyses were performed to identify functional categories and associated molecular and biochemical pathways, respectively, for the identified DEGs, and a protein-protein interaction (PPI) network of the DEGs was constructed using Cytoscape software.GO and KEGG results suggested that several biological pathways (ie, "immune response," "inflammation," and "osteoclast differentiation") are commonly involved in the development of both RA and OA, whereas several other pathways (eg, "MAPK signaling pathway," and "ECM-receptor interaction") presented significant differences between these disorders.This study provides further insights into the underlying pathogenesis of RA and OA, which may facilitate the diagnosis and treatment of these diseases.

[Shaoyangzhugu Formula regulates p19Arf-p53-p21Cip1 signaling pathway to ameliorate cartilage degeneration in aged cynomolgus monkeys with knee osteoarthritis]

OBJECTIVE

To study the effect of Shaoyangzhugu (SYZG) Formula (a formula consisting of 9 traditional Chinese drugs) in delaying the degeneration of articular cartilage and the role p19^Arf-p53-p21^Cip1 signaling pathway in mediating this effect.

METHOD

Thirteen aged cynomolgus monkeys with degenerative knee joints were selected based on X-ray findings, and one of them was randomly selected for pathological observation. The other monkeys were randomized equally into SYZG Formula group (treated with SYZG decoction), ammonia moxime group and saline group. All the monkeys were sacrificed after 8 weeks of treatment with intragastric administration of the drugs or saline. The pathology in the knee joint articular cartilage was observed and the mRNA and protein expressions of p19^Arf, p53, and p21^Cip1 in the articular cartilage were detected using RT-qPCR and Western blotting.

RESULTS

The pathological findings of the articular cartilage in old cynomolgus monkeys were consistent with the characteristics of knee osteoarthritis (KOA). Mankin scores of the cynomolgus monkeys were 7.38∓0.52 in SYZG Formula group, 7.88∓0.83 in ammonia moxime group, and 8.38∓0.74 in saline group, showing a significant difference between SYZG Formula group and saline group (P<0.05). The expressions of p19^Arf, p53, and p21^Cip1 were the lowest in SYZG Formula group and the highest in saline group with significant differences among the 3 groups (P<0.05).

CONCLUSION

SYZG Formula can delay chondrocyte senescence by regulating p19^Arf-p53-p21^Cip1 signaling pathway to delay articular cartilage degeneration in aged cynomolgus monkeys.

Emerging Players at the Intersection of Chondrocyte Loss of Maturational Arrest, Oxidative Stress, Senescence and Low-Grade Inflammation in Osteoarthritis

The prevalence of Osteoarthritis (OA) is increasing because of the progressive aging and unhealthy lifestyle. These risk factors trigger OA by removing constraints that keep the tightly regulated low turnover of the extracellular matrix (ECM) of articular cartilage, the correct chondrocyte phenotype, and the functionality of major homeostatic mechanisms, such as mitophagy, that allows for the clearance of dysfunctional mitochondria, preventing increased production of reactive oxygen species, oxidative stress, and senescence. After OA onset, the presence of ECM degradation products is perceived as a “danger” signal by the chondrocytes and the synovial macrophages that release alarmins with autocrine/paracrine effects on the same cells. Alarmins trigger innate immunity in the joint, with important systemic crosstalks that explain the beneficial effects of dietary interventions and improved lifestyle. Alarmins also boost low-grade inflammation: the release of inflammatory molecules and chemokines sustained by continuous triggering of NF-κB within an altered cellular setting that allows its higher transcriptional activity. Chemokines exert pleiotropic functions in OA, including the recruitment of inflammatory cells and the induction of ECM remodeling. Some chemokines have been successfully targeted to attenuate structural damage or pain in OA animal models. This represents a promising strategy for the future management of human OA.

Identification of novel genes in aging osteoblasts using next-generation sequencing and bioinformatics

During the aging process, impaired osteoblastic function is one key factor of imbalanced bone formation and age-related bone loss. The aim of this study is to explore the differentially expressed genes in normal and aged osteoblasts and to identify genes potentially involved in age-related alteration in bone physiology. Based on next generation sequencing and bioinformatics analysis, 12 differentially expressed microRNAs and 22 differentially expressed genes were identified. Up-regulation of miR-204-5p was validated in an array of osteoporotic hip fracture in the Gene Expression Omnibus database (GSE74209). The putative targets for miR-204-5p were Kruppel-like factor 7 (KLF7) and SRY-box 11 (SOX11). Ingenuity Pathway Analysis identified SOX11, involved in osteoarthritis pathway and differentiation of osteoblasts, together with miR-204-5p, a potential upstream regulator, suggesting the critical role of miR-204-5p-SOX11 regulation in the aging process of human bones. In addition, as semaphorin 3A (SEMA3A) and ephrin type-A receptor 5 (EPHA5) were involved in nervous system related biological functions, we postulated a potential linkage between SEMA3A, EPHA5 and development of neurogenic heterotopic ossification. Our findings implicate new candidate genes in the diagnosis of geriatric musculoskeletal disorders, and provide novel insights that may contribute to the elaboration of new biomarkers for neurogenic heterotopic ossification.

Cyclin D1 Gene Silencing Promotes IL-1β-Induced Apoptosis in Rat Chondrocytes

This study investigated the effects of cyclin D1 gene silencing on cell proliferation and apoptosis of interleukin-1β (IL-1β)-induced osteoarthritis (OA) chondrocytes. Chondrocytes from healthy sprague-dawley rats were divided into blank, OA model (chondrocytes underwent IL-1β inducement), OA trial (chondrocytes underwent IL-1β inducement with cyclin D1-shRNA treatment), and negative control (NC; chondrocytes underwent IL-1β inducement and control-shRNA treatment) groups. Cell proliferation was assessed by CCK-8 assay, and cell cycle and apoptosis by flow cytometry. qRT-PCR and Western blotting were performed to detect cyclin D1 and apoptosis-related factors expression levels. Chondrocyte proliferation increased after 72-96 h after incubation. The OA trial group exhibited reduced cell proliferation at 48, 72, and 96 h after treatment. The OA model, OA trial, and NC groups all contained more cells arrested in G1 phase and had higher apoptosis rates than the blank group. Additionally, the OA trial group contained more cells arrested in G1 phase, with increased apoptosis rates compared to the OA model and NC groups. The OA model group had lowest expression of cyclin D1 whereas the blank group contained the highest among the four groups. qRT-PCR also showed that the OA model, OA trial, and NC groups all had increased expression levels of Bax and reduced expression levels of Bcl-2 and P53 compared to the blank group, whereby by the OA group had the most significant change. The combined evidence in our study shows that cyclin D1 gene silencing suppresses proliferation and induces apoptosis of rat chondrocytes in IL-1β-induced OA. J. Cell. Biochem. 119: 290-299, 2018. © 2017 Wiley Periodicals, Inc.