Long non-coding RNA MCM3AP-AS1 protects chondrocytes ATDC5 and CHON-001 from IL-1β-induced inflammation via regulating miR-138-5p/SIRT1

Bergamottin (Ber) ameliorates the progression of osteoarthritis via the Sirt1/NF-κB pathway

Osteoarthritis (OA) is a common chronic disease characterized by progressive cartilage degeneration and secondary synovial inflammation. Bergamottin (Ber) is an important natural derivative of the furanocoumarin compound, extracted from natural foods, such as the pulp of grapefruits and pomelos. Ber exhibits several characteristicsthat are beneficial to human health, such as anti-inflammation, antioxidant, and anti-cancer effects. However, the role of Ber in the treatment of OA has not been elucidated to date. Therefore, in the present study, in vitro experiments were conducted, which demonstrated that Ber reduces the secretion of inducible nitric oxide synthase (iNOS), nitric oxide (NO), cyclooxygenase-2 (COX2), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and prostaglandin E2 (PGE2) under the stimulation of interleukin-1β (IL-1β). Ber also reversed the IL-1 β-mediated aggrecan and type II collagen degradation within the extracellular matrix (ECM). In addition, in vivo experiments were conducted, in which Ber ameliorated the progression of OA in mice. It was revealed that Ber exerted its cellular effect by activating the Sirt1/NF-kB pathways. In conclusion, the present study demonstrated the therapeutic potential of Ber in the context of OA.

MicroRNA-138: an emerging regulator of skeletal development, homeostasis, and disease

Noncoding microRNAs are powerful epigenetic regulators of cellular processes by their ability to target and suppress expression of numerous protein-coding mRNAs. This multitargeting function is a unique and complex feature of microRNAs. It is now well-described that microRNAs play important roles in regulating the development and homeostasis of many cell/tissue types, including those that make up the skeletal system. In this review, we focus on microRNA-138 (miR-138) and its effects on regulating bone and cartilage cell differentiation and function. In addition to its reported role as a tumor suppressor, miR-138 appears to function as an inhibitor of osteoblast differentiation. This review provides additional information on studies that have attempted to alter miR-138 expression in vivo as a means to dampen ectopic calcification or alter bone mass. However, a review of the published literature on miR-138 in cartilage reveals a number of contradictory and inconclusive findings with respect to regulating chondrogenesis and chondrocyte catabolism. This highlights the need for more research in understanding the role of miR-138 in cartilage biology and disease. Interestingly, a number of studies in other systems have reported miR-138-mediated effects in dampening inflammation and pain responses. Future studies will reveal if a multifunctional role of miR-138 involving suppression of ectopic bone, inflammation, and pain will be beneficial in skeletal conditions such as osteoarthritis and heterotopic ossification.

Potential Joint Protective and Anti-Inflammatory Effects of Integrin αvβ3 in IL-1β-Treated Chondrocytes Cells

In osteoarthritis (OA), the articular cartilage covering the articular surface of the bone wears out, exposing the subchondral bone, and the synovial membrane surrounding the joint becomes inflamed, causing pain and deformity. OA causes pain, stiffness, and swelling, and discomfort in the knee when climbing stairs is a typical symptom. Although drug development studies are conducted to treat these inflammatory joint diseases, it is difficult to find conclusive research results which could reduce inflammation and slow cartilage tear. The development of drugs to relieve inflammatory pain often utilizes inflammatory triggers. Interleukins, one of the proteins in the limelight as pro-inflammatory factors, are immune-system-stimulating factors that promote the body's fight against harmful factors such as bacteria. In this study, inflammation was induced in Chondrocytes cells (Chon-001 cells) with IL-1β and then treated with integrin αvβ3 to show anti-inflammatory and chondrogenesis effects. Integrin αvβ3 was not toxic to Chon-001 cells in any concentration groups treated with or without IL-1β. COX-2 and iNOS, which are major markers of inflammation, were significantly reduced by integrin αvβ3 treatment. Expressions of p-ERK, p-JNK, and p-p38 corresponding to the MAPKs signaling pathway and p-IκBα and p-p65 corresponding to the NF-κB signaling pathway were also decreased in a dose-dependent manner upon integrin αvβ3 treatment, indicating that inflammation was inhibited, whereas treatment with integrin αvβ3 significantly increased the expression of ALP, RUNX2, BMP2, BMP4, Aggrecan, SOX9, and COL2A1, suggesting that osteogenesis and chondrogenesis were induced. These results suggest that integrin αvβ3 in-duces an anti-inflammatory effect, osteogenesis, and chondrogenesis on IL-1β-induced Chon-001 cells.

Interaction between SIRT1 and non-coding RNAs in different disorders

SIRT1 is a member of the sirtuin family functioning in the process of removal of acetyl groups from different proteins. This protein has several biological functions and is involved in the pathogenesis of metabolic diseases, malignancy, aging, neurodegenerative disorders and inflammation. Several long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs) have been found to interact with SIRT1. These interactions have been assessed in the contexts of sepsis, cardiomyopathy, heart failure, non-alcoholic fatty liver disease, chronic hepatitis, cardiac fibrosis, myocardial ischemia/reperfusion injury, diabetes, ischemic stroke, immune-related disorders and cancers. Notably, SIRT1-interacting non-coding RNAs have been found to interact with each other. Several circRNA/miRNA and lncRNA/miRNA pairs that interact with SIRT1 have been identified. These axes are potential targets for design of novel therapies for different disorders. In the current review, we summarize the interactions between three classes of non-coding RNAs and SIRT1.

Extracellular vesicles derived from cervical cancer cells carrying MCM3AP-AS1 promote angiogenesis and tumor growth in cervical cancer via the miR-93/p21 axis

Tumor cells can promote angiogenesis by secreting extracellular vesicles (EVs). Meanwhile, tumor-derived EVs can carry long non-coding RNAs to activate pro-angiogenic signaling in endothelial cells. Here, we investigated the role of long non-coding RNA MCM3AP-AS1 carried by cervical cancer (CC) cell-derived EVs in the angiogenesis and the resultant tumor growth in CC, as well as the potential molecular mechanisms. LncRNAs significantly expressed in CC cell-derived EVs and CC were screened, followed by prediction of downstream target genes. EVs were isolated from HcerEpic and CaSki cell supernatants, followed by identification. The expression of MCM3AP-AS1 in CC was analyzed and its interaction with miR-93-p21 was confirmed. Following co-culture system, the role of MCM3AP-AS1 carried by EVs in HUVEC angiogenic ability, CC cell invasion and migration in vitro along with angiogenesis and tumorigenicity in vivo was assayed. MCM3AP-AS1 was overexpressed in CC cell-derived EVs as well as in CC tissues and cell lines. Cervical cancer cell-derived EVs could transfer MCM3AP-AS1 into HUVECs where MCM3AP-AS1 competitively bound to miR-93 and upregulate the expression of the miR-93 target p21 gene. Thus, MCM3AP-AS1 promoted angiogenesis of HUVECs. In the similar manner, MCM3AP-AS1 enhanced CC cell malignant properties. In nude mice, EVs-MCM3AP-AS1 induced angiogenesis and tumor growth. Overall, this study reveals that CC cell-derived EVs may transport MCM3AP-AS1 to promote angiogenesis and tumor growth in CC.

Advances in Research on the Regulatory Roles of lncRNAs in Osteoarthritic Cartilage

Osteoarthritis (OA) is the most common degenerative bone and joint disease that can lead to disability and severely affect the quality of life of patients. However, its etiology and pathogenesis remain unclear. It is currently believed that articular cartilage lesions are an important marker of the onset and development of osteoarthritis. Long noncoding RNAs (lncRNAs) are a class of multifunctional regulatory RNAs that are involved in various physiological functions. There are many differentially expressed lncRNAs between osteoarthritic and normal cartilage tissues that play multiple roles in the pathogenesis of OA. Here, we reviewed lncRNAs that have been reported to play regulatory roles in the pathological changes associated with osteoarthritic cartilage and their potential as biomarkers and a therapeutic target in OA to further elucidate the pathogenesis of OA and provide insights for the diagnosis and treatment of OA.

Emerging role of lncRNAs in osteoarthritis: An updated review

Osteoarthritis (OA) is a prevalent joint disease, which is associated with progressive articular cartilage loss, synovial inflammation, subchondral sclerosis and meniscus injury. The molecular mechanism underlying OA pathogenesis is multifactorial. Long non-coding RNAs (lncRNAs) are non-protein coding RNAs with length more than 200 nucleotides. They have various functions such as modulating transcription and protein activity, as well as forming endogenous small interfering RNAs (siRNAs) and microRNA (miRNA) sponges. Emerging evidence suggests that lncRNAs might be involved in the pathogenesis of OA which opens up a new avenue for the development of new biomarkers and therapeutic strategies. The purpose of this review is to summarize the current clinical and basic experiments related to lncRNAs and OA with a focus on the extensively studied H19, GAS5, MALAT1, XIST and HOTAIR. The potential translational value of these lncRNAs as therapeutic targets for OA is also discussed.

Engineering of MSC-Derived Exosomes: A Promising Cell-Free Therapy for Osteoarthritis

Osteoarthritis (OA) is characterized by progressive cartilage degeneration with increasing prevalence and unsatisfactory treatment efficacy. Exosomes derived from mesenchymal stem cells play an important role in alleviating OA by promoting cartilage regeneration, inhibiting synovial inflammation and mediating subchondral bone remodeling without the risk of immune rejection and tumorigenesis. However, low yield, weak activity, inefficient targeting ability and unpredictable side effects of natural exosomes have limited their clinical application. At present, various approaches have been applied in exosome engineering to regulate their production and function, such as pretreatment of parental cells, drug loading, genetic engineering and surface modification. Biomaterials have also been proved to facilitate efficient delivery of exosomes and enhance treatment effectiveness. Here, we summarize the current understanding of the biogenesis, isolation and characterization of natural exosomes, and focus on the large-scale production and preparation of engineered exosomes, as well as their therapeutic potential in OA, thus providing novel insights into exploring advanced MSC-derived exosome-based cell-free therapy for the treatment of OA.

Long non-coding RNA plasmacytoma variant translocation 1 and growth arrest specific 5 regulate each other in osteoarthritis to regulate the apoptosis of chondrocytes

Long non-coding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) and growth arrest specific 5 (GAS5) have opposite functions in the apoptosis of chondrocytes, which are involved in the pathogenesis of osteoarthritis (OA). The opposite roles of PVT1 and GAS5 in OA may indicate the existence of crosstalk between them in OA. This study aimed to explore the possible interaction between PVT1 and GAS5 in OA. Accumulation of PVT1 and GAS5 in OA and control synovial fluid samples was measured by RT-qPCR. The interaction between PVT1 and GAS5 in chondrocytes was explored by overexpression experiments. Dual-luciferase reporter assay was performed to analyze the binding of PVT1 and GAS5 to each other’s promoter regions. Regulatory roles of PVT1 and GAS5 in the apoptosis of chondrocytes were studied with cell apoptosis assay. PVT1 was upregulated in OA, and GAS5 was downregulated in OA. An inverse correlation between PVT1 and GAS5 was observed across OA samples. Under lipopolysaccharides (LPS) treatment, PVT1 was upregulated and GAS5 was downregulated. Interestingly, PVT1 and GAS5 overexpression downregulated each other in chondrocytes. Cell apoptosis analysis showed that PVT1 overexpression promoted cell apoptosis, while GAS5 overexpression suppressed cell apoptosis induced by LPS. Co-transfection of PVT1 and GAS5 failed to significantly affect cell apoptosis. PVT1 and GAS5 directly bound to each other’s promoter regions. Our study characterized the interaction between PVT1 and GAS5 in OA. Their interaction regulated the apoptosis of chondrocytes, which play a critical role in OA. PVT1 and GAS5 may form a negative feedback loop in OA.

Long intergenic non-protein coding RNA 00707 regulates chondrocyte apoptosis and proliferation in osteoarthritis by serving as a sponge for microRNA-199-3p

It is known that long intergenic non-protein coding RNA 00707 (LINC00707) promotes lipopolysaccharide (LPS)-injury and microRNA-199-3p (miR-199-3p) regulates chondrocyte proliferation and apoptosis. Both processes participate in osteoarthritis (OA). We predicted that LINC00707 and miR-199-3p may interact with each other. Therefore, LINC00707 and miR-199-3p may interact with each other to participate in OA. In this study, the expression of LINC00707 and miR-199-3p in both OA and normal articular cartilage tissues was analyzed using RT-qPCR. The subcellular location of LINC00707 and its direct interaction with miR-199-3p were explored by nuclear fractionation assay, RNA pull-down assay and Luciferase reporter assay, respectively. The role of LINC00707 and miR-199-3p in regulating the expression of each other was analyzed using an overexpression assay, followed by RT-qPCR. The role of LINC00707 and miR-199-3p in regulating OA chondrocyte proliferation and apoptosis was analyzed by BrdU assay and cell apoptosis assay, respectively. OA tissues exhibited increased expression of LINC00707 and decreased expression of miR-199-3p. LINC00707 directly interacted with miR-199-3p in cytoplasm. However, LINC00707 and miR-199-3p overexpression failed to affect each other’s expression. LPS treatment increased LINC00707 expression and decreased miR-199-3p expression in OA chondrocyte. LINC00707 overexpression increased the apoptosis of OA chondrocytes induced by LPS and suppressed the proliferation of OA chondrocytes. Moreover, LINC00707 suppressed the role of miR-199-3p in enhancing cell proliferation and suppressing cell apoptosis. In conclusion, LINC00707 can be detected in cytoplasm and it may sponge miR-199-3p to regulate chondrocyte proliferation and apoptosis in OA.

Calcium-binding protein 39 overexpression promotes macrophages from 'M1' into 'M2' phenotype and improves chondrocyte damage in osteoarthritis by activating the AMP-activated protein kinase/sirtuin 1 axis

Osteoarthritis (OA) is a degenerative joint disease that affects cartilage and its peripheral tissues. Up-regulation of Calcium-binding protein 39 (CAB39) has a significant protective effect on osteoblasts, but the role and related molecular mechanisms of CAB39 in OA have not yet been reported. CAB39 overexpression and knockdown models were set up in chondrocytes (ATDC5) and macrophages (RAW264.7). The OA cell model was induced in ATDC5 cells with IL-1β (10 ng/mL). Cell viability was tested by the cell counting kit-8 assay, apoptosis was checked by flow cytometry. Western blot was applied for checking the expression of MMP3, MMP13, Aggrecan, the AMPK/Sirt-1 pathway, apoptosis-related proteins (Bax, Bcl-2, and Caspase-3), and macrophage phenotypic markers (CD86, iNOS, CD206, and Arg1). An OA model was constructed in mice, and CAB39 overexpression plasmids were administered to the knee cavity of the OA model mice. As a result, CAB39 was down-regulated in IL-1β-treated chondrocytes and OA mice. Overexpressing CAB39 enhanced ATDC5 cell viability and choked IL-1β-mediated apoptosis. Overexpression of CAB39 boosted the polarization of macrophages from M1-phenotype into M2 phenotype. In addition, overexpressing CAB39 facilitated the AMPK/Sirt-1 pathway activation, and AMPK inhibitors reversed the protective effect of CAB39 overexpression on chondrocytes. Moreover, CAB39 exhibited anti-inflammatory effects in OA mice by activating the AMPK/Sirt-1 pathway. Collectively, overexpressing CAB39 heightened macrophages’ M2 polarization and declined chondrocyte injury in OA by activating the AMPK/Sirt-1 pathway.Abbreviations AMPK: AMP-activated protein kinaseArg1: arginase 1Bax: Bcl-2-associated X proteinBcl-2: B-cell lymphoma-2CAB39: Calcium-binding protein 39CM: Conditioned mediumDMM: destabilization of the medial meniscusECM: extracellular matrixELISA: enzyme-linked immunosorbent assayFCM: Flow cytometryIL-1β: interleukin-1βIL-4: interleukin-4IL-6: interleukin-6IL-10: interleukin-10IFN – γ: Interferon-gammaIHC: ImmunohistochemistryiNOS: Inducible nitric oxide synthaseLKB1: liver kinase B1MMP3: Matrix metalloproteinase3MMP13:Matrix metalloproteinase13NF-κB: NF-kappaBOA: OsteoarthritisqRT-PCR: Quantitative reverse transcription-polymerase chain reactionRT: room temperatureSirt-1: sirtuin 1STRAD: STE20-related adaptor alphaWB: Western blot

The anti-fibrotic agent nintedanib protects chondrocytes against tumor necrosis factor-ɑ (TNF-ɑ)-induced extracellular matrix degradation

Osteoarthritis is an inflammatory disease of the musculoskeletal system characterized by damaged articular cartilage. Nintedanib is an oral triple kinase inhibitor with anti-fibrotic and anti-inflammatory properties. Thus, we hypothesized that nintedanib might exert a protective effect in chondrocytes and it could be meaningful to repurpose the drug for osteoarthritis. In this study, we aimed to investigate the potential effects of nintedanib on TNF-α-induced cellular injury in CHON-001 chondrocytes. The results show that nintedanib ameliorated TNF-α-induced reactive oxygen species (ROS) production and reduced glutathione (GSH) decrease. Nintedanib reduced the production of pro-inflammatory cytokines interleukin-6 (IL-6) and interleukin-1β (IL-1β) in TNF-α-induced CHON-001 chondrocytes. Nintedanib restored TNF-α caused decreased expression levels of Col II and sry-type high-mobility-group box-9 (SOX-9) in CHON-001 chondrocytes. Moreover, nintedanib ameliorated the TNF-α-caused impairment of protein kinase A/cAMP-response element-binding protein (PKA/CREB) signaling pathway as revealed by the decreased PKA RI expression and increased p-CREB in CHON-001 cells. Inhibition of PKA by H89 abolished the effects of nintedanib on SOX-9 and Col II expression. Taken together, nintedanib presented protective effects on TNF-α-induced oxidative stress, inflammation, and ECM damage in CHON-001 chondrocytes. Mechanically, the effect of nintedanib is associated with the PKA/CREB pathway. These data imply that the anti-fibrotic agent nintedanib may have a potential therapeutic application for osteoarthritis.

MiR-18a-3p improves cartilage matrix remodeling and inhibits inflammation in osteoarthritis by suppressing PDP1

Osteoarthritis (OA) is a degenerative disease characterized by synovial inflammation. MiR-18a-3p was reported to be downregulated in knee anterior cruciate ligament of OA patients. In the present study, the specific functions and mechanism of miR-18a-3p in OA were explored. An in vitro model of OA was established using 10 ng/ml IL-1β to treat ATDC5 cells, and medial meniscus instability surgery was performed on Wistar rats to establish in vivo rat model of OA. RT-qPCR revealed that miR-18a-3p was downregulated in IL-1β-stimulated ATDC5 cells. MiR-18a-3p overexpression inhibited secretion of inflammatory cytokines and concentration of matrix metalloproteinases, as shown by ELISA and western blotting. The binding relation between miR-18a-3p and pyruvate dehydrogenase phosphatase catalytic subunit 1 (PDP1) was detected by luciferase reporter assays. MiR-18a-3p targeted PDP1 and negatively regulated PDP1 expression. Results of rescue assays revealed that PDP1 upregulation reserved the suppressive effect of miR-18a-3p overexpression on levels of inflammatory cytokines and matrix metalloproteinases in IL-1β-stimulated ATDC5 cells. H&E staining was used to observe pathological changes of synovial tissues in the knee joint of Wistar rats. Safranin O-fast green/hematoxylin was used to stain cartilage samples of knee joints. MiR-18a-3p overexpression suppressed OA progression in vivo. Overall, miR-18a-3p improves cartilage matrix remodeling and suppresses inflammation in OA by targeting PDP1.

Depletion of mmu_circ_0001751 (circular RNA Carm1) protects against acute cerebral infarction injuries by binding with microRNA-3098-3p to regulate acyl-CoA synthetase long-chain family member 4

Circular RNAs (circRNAs) play a critical role in acute cerebral infarction (ACI). Our research discussed the effect of circ-Carm1 in ACI and its potential molecular mechanisms. Healthy controls and patients with ACI were included in this study. The establishment of an oxygen and glucose deprivation/reoxygenation (OGD/R) model of HT22 cells was conducted to mimic ACI in vitro. Quantitative reverse transcription polymerase chain reaction was conducted to determine mRNA levels extracted from serum and HT22 cell samples, and Western blotting was performed to determine protein levels. Terminal deoxynucleotidyl transferase dUTP nick end labeling and cell counting kit 8 assays were conducted to evaluate cellular functions. Concentrations of Fe²⁺ and malondialdehyde, and levels of transferrin receptor 1, glutathione peroxidase 4, and glutathione were evaluated to determine ferroptosis in OGD/R-induced HT22 cells. The binding relationships between mRNAs and miRNAs were verified. circ-Carm1 was highly expressed in OGD/R-treated HT22 cells. Deficiency of circ-Carm1 restored cell viability and suppressed ferroptosis in OGD/R-induced HT22 cells. miR-3098-3p was predicted to be a target of circ-Carm1. The miR-3098-3p inhibitor partly neutralized the functions of circ-Carm1 in OGD/R-induced HT22 cells. Furthermore, acyl-CoA synthetase long-chain family member 4 (ACSL4) was confirmed to be a downstream target of miR-3098-3p and was elevated in OGD/R-induced HT22 cells. Overexpression of ACSL4 mitigated the functions of miR-3098-3p and accelerated HT22 cell dysfunction. Hence, circ-Carm1 is upregulated in ACI. circ-Carm1 suppression protects HT22 cells from dysfunction by inhibiting ferroptosis. Therefore, inducing circ-Carm1 deficiency may be a promising therapeutic method for ACI.

Fumitremorgin C alleviates advanced glycation end products (AGE)-induced chondrocyte inflammation and collagen II and aggrecan degradation through sirtuin-1 (SIRT1)/nuclear factor (NF)-κB/ mitogen-activated protein kinase (MAPK)

Fumitremorgin C is a potent and selective inhibitor of the breast cancer resistance protein. This study aimed to explore the role of fumitremorgin C in osteoarthritis (OA) and disclose the underlying mechanism. The cell viability of AGE-treated SW1353 cells in the presence of fumitremorgin C was detected by Cell Counting Kit-8 (CCK-8) assay. The inflammation and extracellular matrix (ECM) deposition of AGE-induced SW1353 cells was respectively measured by enzyme linked immunosorbent assay (ELISA), immunofluorescence, and Western blot. The expression of SIRT1 and NF-KB/MAPK signal was examined by Western blot. After that, SIRT1 inhibitor EX527 was added to observe the mechanism of action of fumitremorgin C. Fumitremorgin C restored the cell viability of SW1353 cells injured by AGE. Furthermore, it alleviated inflammation and ECM degradation in AGE-induced SW1353 cell. The SIRT1 expression decreased by AGE was recovered upon fumitremorgin C to SW1353 cells. The ratio of phosphorylated p65 (p-p65) and p65, phosphorylated JNK (p-JNK) and JNK, and phosphorylated 38 (p-38) and 38 were increased by AGE treatment, which was recovered by fumitremorgin C addition. SIRT1 inhibitor EX527 reverts the repressive effects of fumitremorgin C on inflammation and ECM degradation in AGE-induced SW1353 cell. In conclusion, fumitremorgin C alleviates AGE-induced inflammation and the degradation of collagen II and aggrecan through SIRT1/NF-κB/MAPK, which reveals the underlying mechanism by which fumitremorgin C alleviates OA.

LncRNA nuclear receptor subfamily 2 group F member 1 antisense RNA 1 (NR2F1-AS1) aggravates nucleus pulposus cell apoptosis and extracellular matrix degradation

Emerging reports uncover that long noncoding RNAs (lncRNAs) help regulate intervertebral disc degeneration (IVDD). Here, we probe the function of lncRNA nuclear receptor subfamily 2 group F member 1 antisense RNA 1 (NR2F1-AS1) in IVDD. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was applied to verify the expression of NR2F1-AS1 and miR-145-5p in nucleus pulposus (NP) tissues from IVDD patients or NP cells dealt with IL-1β or TNF-α. Flow cytometry or the TdT-mediated dUTP nick end labeling (TUNEL) assay was performed to validate the apoptosis of NP cells with selective regulation of NR2F1-AS1 and miR-145-5p. ECM-related genes, FOXO1, Bax, and Bcl2 were evaluated by qRT-PCR or Western blot (WB). The targeted relationships between NR2F1-AS1 and miR-145-5p, miR-145-5p and FOXO1 were testified by the dual-luciferase reporter assay and the RNA immunoprecipitation (RIP) assay. Our outcomes substantiated that NR2F1-AS1 was up-regulated, while miR-145-5p was down-regulated in intervertebral disc tissues of IVDD patients or NP cells treated with IL-1β or TNF-α. Besides, overexpressing NR2F1-AS1 intensified ECM degradation and NP cell apoptosis induced by IL-1β, while knocking down NR2F1-AS1 or up-regulating miR-145-5p reversed IL-1β-mediated effects in NP cells. Meanwhile, NR2F1-AS1 choked miR-145-5p and abated its effects in NP cells. This study confirms that NR2F1-AS1 modulates IVDD progression by up-regulating the FOXO1 pathway through the sponge of miR-145-5p as a competitive endogenous RNA (ceRNA).

Crosstalk Among circRNA/lncRNA, miRNA, and mRNA in Osteoarthritis

Osteoarthritis (OA) is a joint disease that is pervasive in life, and the incidence and mortality of OA are increasing, causing many adverse effects on people's life. Therefore, it is very vital to identify new biomarkers and therapeutic targets in the clinical diagnosis and treatment of OA. ncRNA is a nonprotein-coding RNA that does not translate into proteins but participates in protein translation. At the RNA level, it can perform biological functions. Many studies have found that miRNA, lncRNA, and circRNA are closely related to the course of OA and play important regulatory roles in transcription, post-transcription, and post-translation, which can be used as biological targets for the prevention, diagnosis, and treatment of OA. In this review, we summarized and described the various roles of different types of miRNA, lncRNA, and circRNA in OA, the roles of different lncRNA/circRNA-miRNA-mRNA axis in OA, and the possible prospects of these ncRNAs in clinical application.

Celecoxib prevents tumor necrosis factor-α (TNF-α)-induced cellular senescence in human chondrocytes

Osteoarthritis (OA) is a cartilage degenerative disease commonly observed in the elderly population and significantly impacts the normal life of OA patients. It has been reported that the development of pathological cell senescence in chondrocytes is involved in the pathogenesis of OA. Celecoxib is a common non-steroidal anti-inflammatory drug, and it has been recently reported to exert therapeutic effects on OA. However, its underlying mechanism is still unclear. The present study intends to explore its mechanism and provide fundamental evidence for the application of Celecoxib in the treatment of clinical OA. Tumor necrosis factor-α (TNF-α) was utilized to establish an in vitro model of chondrocytes senescence. The elevated reactive oxygen species (ROS) generation, increased cell cycle arrest in G0/G1 phase, reduced telomerase activity, and upregulated senescence-associatedβ-galactosidase (SA-β-Gal) staining were all observed in TNF-α-treated chondrocytes, which were then dramatically reversed by 10 and 20 μM Celecoxib. In addition, the upregulated DNA damage biomarkers, p-ATM, and p-CHK2, observed in TNF-α-treated chondrocytes were significantly downregulated by 10 and 20 μM Celecoxib. Lastly, the expression level of p21 and p53 was greatly elevated in chondrocytes by stimulation with TNF-α which was then pronouncedly repressed by treatment with Celecoxib. Taken together, our data reveal that Celecoxib ameliorated TNF-α-induced cellular senescence in human chondrocytes.

Long noncoding RNA SNHG8 accelerates acute gouty arthritis development by upregulating AP3D1 in mice

Gout can affect the quality of life of patients due to monosodium urate monohydrate (MSU) crystals. Numerous studies have proposed that long noncoding RNAs (lncRNAs) regulate gout. We aimed to reveal the function of lncRNA small nucleolar RNA host gene 8 (SNHG8) in acute gouty arthritis (GA). A GA mouse model was established by injection of MSU into footpads. The levels of SNHG8, miR-542-3p and adaptor-related protein complex 3 subunit delta 1 (AP3D1) in footpads were detected via polymerase chain reaction analysis. Hematoxylin–eosin staining revealed the paw swelling in mice. Enzyme-linked immunosorbent assay and western blot analysis were applied to determine the concentrations of proinflammatory cytokines. SNHG8 expression was identified to be upregulated after MSU treatment. Ablation of SNHG8 decreased the MSU-induced enhancement of paw swelling and foot thickness. In addition, SNHG8 depletion decreased the protein levels of proinflammatory factors in GA mice. Mechanically, SNHG8 was verified to be a sponge of miR-542-3p, and miR-542-3p targeted AP3D1 3ʹ untranslated region. SNHG8 competitively bound with miR-542-3p to upregulate AP3D1 expression. Finally, results of rescue assays illustrated that AP3D1 upregulation offset the SNHG8-mediated inhibition on paw swelling and protein levels of proinflammatory factors in GA mice. In conclusion, SNHG8 accelerates acute GA development by upregulating AP3D1 in an miR-542-3p-dependent way in mice, providing an effective therapeutic approach to treat acute GA.

Identification of transcription factors and construction of a novel miRNA regulatory network in primary osteoarthritis by integrated analysis

Backgrounds

As osteoarthritis (OA) disease-modifying therapies are not available, novel therapeutic targets need to be discovered and prioritized. Here, we aim to identify miRNA signatures in patients to fully elucidate regulatory mechanism of OA pathogenesis and advance in basic understanding of the genetic etiology of OA.

Methods

Six participants (3 OA and 3 controls) were recruited and serum samples were assayed through RNA sequencing (RNA-seq). And, RNA-seq dataset was analysed to identify genes, pathways and regulatory networks dysregulated in OA. The overlapped differentially expressed microRNAs (DEMs) were further screened in combination with the microarray dataset GSE143514. The expression levels of candidate miRNAs were further validated by quantitative real-time PCR (qRT-PCR) based on the GEO dataset (GSE114007).

Results

Serum samples were sequenced interrogating 382 miRNAs. After screening of independent samples and GEO database, the two comparison datasets shared 19 overlapped candidate micRNAs. Of these, 9 up-regulated DEMs and 10 down-regulated DEMs were detected, respectively. There were 236 target genes for up-regulated DEMs and 400 target genes for those down-regulated DEMs. For up-regulated DEMs, the top 10 hub genes were KRAS, NRAS, CDC42, GDNF, SOS1, PIK3R3, GSK3B, IRS2, GNG12, and PRKCA; for down-regulated DEMs, the top 10 hub genes were NR3C1, PPARGC1A, SUMO1, MEF2C, FOXO3, PPP1CB, MAP2K1, RARA, RHOC, CDC23, and CREB3L2. Mir-584-5p-KRAS, mir-183-5p-NRAS, mir-4435-PIK3R3, and mir-4435-SOS1 were identified as four potential regulatory pathways by integrated analysis.

Conclusions

We have integrated differential expression data to reveal putative genes and detected four potential miRNA-target gene pathways through bioinformatics analysis that represent new mediators of abnormal gene expression and promising therapeutic targets in OA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04894-2.

miR-125a-5p-abundant exosomes derived from mesenchymal stem cells suppress chondrocyte degeneration via targeting E2F2 in traumatic osteoarthritis

miRNAs are broad participants in vertebrate biological processes, and they are also the major players in pathological processes. miR-125a-5p was recently found a modulator in the progression of osteoarthritis (OA). Our study was aimed to explore the role and underlying mechanisms of miR-125a-5p-abundant exosomes derived from mesenchymal stem cells (MSC) on OA progression. We separated bone marrow mesenchymal stem cells (BMSCs) as well as the exosomes from traumatic OA patients. The immunofluorescence and cartilage staining were implemented for the observation and the assessment on endocytosis of chondrocytes and exosomal miR-125a-5p efficacy to cartilage degradation. Dual luciferase reporter assay was performed to verified the relationship between miR-125a-5p and E2F2. Then, the function of exosomal miR-125a-5p were examined on chondrocyte degeneration in vitro and in vivo. Our findings indicated that E2F2 expression was elevated while the miR-125a-5p was down in traumatic OA cartilage tissue, showing a negative correlation of the former and the latter. miR-125a-5p targets E2F2 in traumatic OA cartilage tissue and leads to the down-expression of E2F2. The E2F2 expression in chondrocytes was decreased after internalization of exosomes. We additionally found that BMSCs-derived exosomes were rich in miR-125a-5p content and chondrocytes can have it internalized. miR-125a-5p is endowed with a trait of accelerating chondrocytes migration, which is going along with the up-expressions of Collagen II, aggrecan and SOX9 and the down-expression of MMP-13 in vitro. Besides that, the mice model with post-traumatic OA turned out that exosomal miR-125a-5p might beget an alleviation in chondrocyte extracellular matrix degradation. All these outcomes revealed that BMSCs-derived exosomal miR-125a-5p is a positive regulator for chondrocyte migration and inhibit cartilage degeneration We thus were reasonable to believe that transferring of exosomal miR-125a-5p is a prospective strategy for OA treatment.

Overexpression of long noncoding RNA MCM3AP-AS1 promotes osteogenic differentiation of dental pulp stem cells via miR-143-3p/IGFBP5 axis

MCM3AP-AS1 regulates the cartilage repair in osteoarthritis, but how it regulates osteogenic differentiation of dental pulp stem cells (DPSCs) remains to be determined. DPSCs were isolated and induced for osteogenic differentiation. MCM3AP-AS1 expression was increased along with the osteogenic differentiation of DPSCs, whose expression was positive correlated with those of OCN, alkaline phosphatase (ALP) and RUNX2. On contrary, miR-143-3p expression was decreased along with the osteogenic differentiation and was negatively correlated with those of OCN, ALP and RUNX2. Dual-luciferase reporter gene assay showed that miR-143-3p can be negatively regulated by MCM3AP-AS1 and can regulate IGFBP5. MCM3AP-AS1 overexpression increased the expression levels of osteogenesis-specific genes, ALP activity and mineralized nodules during DPSC osteogenic differentiation, while IGFBP5 knockdown or miR-143-3p overexpression counteracted the effect of MCM3AP-AS1 overexpression in DPSCs. Therefore, this study demonstrated the role of MCM3AP-AS1/miR-143-3p/IGFBP5 axis in regulating DPSC osteogenic differentiation.

Long non-coding RNA (lncRNA) nuclear enriched abundant transcript 1 (NEAT1) promotes the inflammation and apoptosis of otitis media with effusion through targeting microRNA (miR)-495 and activation of p38 MAPK signaling pathway

Long non-coding RNA (lncRNA) plays a vital role in human inflammatory diseases. Our study aimed to investigate the function of lncRNA nuclear-enriched abundant transcript 1 (NEAT1) in otitis media with effusion (OME). The mRNA levels of NEAT1 and miR-495 were measured by RT-qPCR. The protein levels of p38 MAPK were detected by western blot. The levels of inflammatory cytokines were examined by ELISA. CCK-8 and flow cytometry assays were used to evaluate the cell viability and apoptosis, respectively. The interaction between NEAT1 and miR-495 was determined by luciferase reporter and RIP assays. NEAT1 was highly expressed in OME, and silencing of NEAT1 facilitated the cell proliferation and suppressed levels of inflammatory cytokines and cell apoptosis in LPS-induced HMEECs. Moreover, miR-495 was confirmed as a downstream target of NEAT1. Functional assays revealed that NEAT1 promoted the OME by targeting miR-495. It was further demonstrated that NEAT1 could activate the p38 MAPK signaling pathway by regulating miR-495, and the p38 MAPK inhibitor restored the effects of NEAT1 overexpression on the inflammation levels, cell proliferation, and apoptosis. Our study revealed that lncRNA NEAT1 served as a ceRNA to activate p38 MAPK signaling by targeting miR-495 in OME, which may offer a new target for OME treatment.

miR-7/EGFR/MEGF9 axis regulates cartilage degradation in osteoarthritis via PI3K/AKT/mTOR signaling pathway

Osteoarthritis (OA) is a common degenerative disease in middle-aged and elderly people. Our previous study has proved that microRNA-7 (miR-7) exacerbated the OA process. This study was aimed to explore the downstream genes and mechanism regulated by miR-7 to affect OA. Multiple EGF-like-domains 9 (MEGF9) was the predicted target of miR-7 by databases. Luciferase report experiment results confirmed that MEGF9 could bind to miR-7. Among the 10 collected pairs of OA and healthy samples, the expression levels of miR-7 and MEGF9 were both up-regulated when compared with healthy subjects by qRT-PCR and immunohistochemistry (IHC). The increased MEGF9 levels were due to the interaction with epidermal growth factor receptor (EGFR) by co-immunoprecipitation. Evaluations found that upregulation of miR-7 or MEGF9 can increase the expression of EGFR, matrix metalloproteinase-13 (MMP-13) and a disintegrin like and metallopeptidase with thrombospondin type 1 motif 5 (ADAMTS-5), so as to aggravate cartilage degradation. In addition, this effect induced by miR-7/EGFR/MEGF9 axis was by activation of PI3K/AKT signaling. The IHC and western blot assay results on OA model mice also demonstrated that miR-7/EGFR/MEGF9 axis regulated cartilage degradation in vivo. In summary, miR-7/EGFR/MEGF9 axis may perform a crucial function in the regulation of OA, providing potential for OA treatment.

Montelukast attenuates interleukin IL-1β-induced oxidative stress and apoptosis in chondrocytes by inhibiting CYSLTR1 (Cysteinyl Leukotriene Receptor 1) and activating KLF2 (Kruppel Like Factor 2)

Montelukast is a cysteinyl leukotriene receptor 1 (CysLTR1) antagonist widely used to suppress the inflammatory response in asthma and allergic rhinitis. This study aimed to investigate the potential impacts of montelukast on osteoarthritis (OA) progression. To determine the role of montelukast in OA, the expression of CysLTR1 was first examined by quantitative reverse transcription PCR (RT-qPCR) and western blot in IL-1β-induced ATDC5 cells treated with or without montelukast. Subsequently, the impacts of montelukast on cell viability and oxidative stress were measured by Cell-Counting-Kit-8 (CCK-8), commercial kits and western blot. Oxidative stress-related protein expressions were determined by western blot analysis in Il-1β-induced ATDC5 cells. Cell apoptosis and cartilage degradation were examined by TdT-mediated dUTP Nick-End Labeling (TUNEL) assay, western blot and RT-qPCR. KLF2 expression was measured in IL-1β-induced ATDC5 cells treated with montelukast. After interference with small interfering RNA (siRNA)-KLF2 in ATDC5 cells, the loss-of-function assays were also performed in same ways. CysLTR1 expression was elevated in IL-1β-induced ATDC5 cells but inhibited significantly by montelukast. Montelukast attenuated the oxidative stress and apoptosis, improved cell viability. Moreover, montelukast enhanced KLF2 expression. After transfected with siRNA-KLF2, montelukast attenuated cell injury, oxidative stress, apoptosis and cartilage degradation in IL-1β-induced ATDC5 cells by activating KLF2.In summary, this work elaborates the evidence that montelukast could attenuate oxidative stress and apoptosis in IL-1β-induced chondrocytes by inhibiting CysLTR1 and activating KLF2, which can guide the therapeutic strategies of montelukast for OA development in the future.

Long non-coding RNA (lncRNA) nuclear enriched abundant transcript 1 (NEAT1) regulates fibroblast growth factor receptor substrate 2 (FRS2) by targeting microRNA (miR)-29-3p in hypertrophic scar fibroblasts

Long non-coding RNAs (lncRNAs) play crucial roles in human diseases. However, the detailed role of lncRNAs in hypertrophic scar fibroblasts (HSFs) is inadequately understood. This study aimed to investigate the potential role of lncRNA nuclear enriched abundant transcript 1 (NEAT1) in hypertrophic scarring. Expression of lncRNAs, miRNAs, and genes were detected by polymerase chain reaction; protein expression was evaluated using western blotting. Cellular function was determined using the CCK-8 assay. The interaction between microRNA (miR)-29-3p and NEAT1 or fibroblast growth factor receptor substrate 2 (FRS2) was verified by luciferase and RNA pull-down assays. The results showed that NEAT1 was overexpressed in the hypertrophic dermis and in HSFs. However, knockdown of NEAT1 suppressed the proliferation and extracellular matrix (ECM) production of HSFs. Moreover, NEAT1 functioned as a competing endogenous RNA to upregulate FRS2 by sponging miR-29-3p. Downregulation of miR-29-3p or overexpression of FRS2 antagonized the effects of NEAT1 knockdown and promoted HSF proliferation and ECM release. In conclusion, NEAT1 knockdown protected against hypertrophic scarring by modulating the miR-29-3p/FRS2 axis, which is a viable target in scar treatment.

Etomidate ameliorated advanced glycation end-products (AGEs)-induced reduction of extracellular matrix genes expression in chondrocytes

Osteoarthritis (OA) is a rheumatic disease common in the elderly. AGEs are the end products of glycation reactions and play an important role in the development of OA. Etomidate is a general anesthesia-inducing agent recently reported to exert significant anti-inflammatory effects. The present study aims to explore the protective effect of Etomidate against advanced glycation end-products (AGEs)-induced reduction of extracellular matrix gene expression in chondrocytes. In the present study, we found that AGEs significantly reduced the expression of Collagen II (COL2A1) and Aggrecan (ACAN) at the gene level. Furthermore, AGEs inhibited the expression of SRY-related high mobility group-box gene 9 (SOX-9), promoting the expression of COL2A1 and ACAN. COL2A1, ACAN, and SOX-9 in chondrocytes were significantly elevated by treatment with Etomidate alone. Consistently, Etomidate ameliorated AGEs-induced downregulation of COL2A1, ACAN, and SOX-9 in a dose-dependent manner. Importantly, we found that knockdown of SOX-9 eliminated the beneficial effects of Etomidate against AGEs-induced decrease in COL2A1 and ACAN genes. Based on these findings, we demonstrated that Etomidate could ameliorate AGEs-induced reduction of extracellular matrix gene expression in chondrocytes by upregulating SOX-9.

Long non-coding RNA H19 protects against intracerebral hemorrhage injuries via regulating microRNA-106b-5p/acyl-CoA synthetase long chain family member 4 axis

Intracerebral hemorrhage (ICH) is one of the most common refractory diseases. Long non-coding RNAs (lncRNAs) play crucial roles in ICH. This study was designed to investigate the role of lncRNA H19 in ICH and the underlying molecular mechanisms involved. Real-time quantitative polymerase chain reaction (RT-qPCR) was performed to determine mRNA expression. Cell viability was analyzed using Cell Counting Kit 8 (CCK8). PI staining Flow cytometry and TdT-mediated biotinylated nick end-labeling (TUNEL) assays were performed to determine ferroptosis in brain microvascular endothelial cells (BMVECs). Targeting relationships were predicted using Starbase and TargetScan and verified by RNA pull-down and luciferase reporter gene assays. Western blotting was performed to assess protein expression. LncRNA H19 is highly expressed in ICH model cells. Over-expression of H19 suppressed cell viability and promoted ferroptosis of BMVECs. miR-106b-5p is predicted to be a target of H19. The expression of miR-106b-5p was lower in oxygen and glucose deprivation hemin-treated (OGD/H-treated) cells. Over-expression of miR-106b-5p reversed the effects of H19 on cell viability and ferroptosis in BMVECs. Furthermore, acyl-CoA synthetase long-chain family member 4 (ACSL4) was verified to be a target gene of miR-106b-5p and was highly expressed in OGD/H-treated cells. Upregulation of ACSL4 inhibited the effects of miR-106b-5p and induced BMVEC dysfunction. In conclusion, lncRNA H19 was overexpressed in ICH. Knockdown of H19 promoted cell proliferation and suppressed BMVECs ferroptosis by regulating the miR-106b-5p/ACSL4 axis. Therefore, H19 knockdown may be a promising therapeutic strategy for ICH.