MicroRNA in Osteoarthritis

CircRNA SEC24A promotes osteoarthritis through miR-107-5p/CASP3 axis

Background

Osteoarthritis (OA) is the most frequently diagnosed chronic joint disease. CircSEC24A is significantly elevated in OA chondrocytes upon IL-1β stimulation. However, its biological function in OA is still not fully understood.

Methods

The circRNAs-miRNA-mRNA network was predicted by bioinformatics analysis. An in vitro OA chondrocytes model was established by IL-1β stimulation. The expression of circSEC24A, miR-107-5p, CASP3, apoptosis-related molecules and extracellular matrix (ECM) components were detected by Western blot and qRT-PCR. MTT assay and Annexin V/PI staining were employed to monitor cell viability and apoptosis, respectively. The interaction between circSEC24A and miR-107-5p, as well as the binding between miR-107-5p and CASP3 3' UTR were detected by luciferase reporter and RIP assays. Cytokine secretion was monitored by ELISA assay. The role of circSEC24A was also explored in anterior cruciate ligament transection (ACLT) rat models.

Results

CircSEC24A and CASP3 were increased, but miR-107-5p was decreased in rat OA cartilage tissues and OA chondrocytes. CircSEC24A acted as a sponge of miR-107-5p. Knockdown of circSEC24A promoted chondrocyte proliferation, but suppressed chondrocyte apoptosis, ECM degradation and inflammation via sponging miR-107-5p. CASP3 was identified as a miR-107-5p target gene. MiR-107-5p mimics protected against OA progression via targeting CASP3. Silencing of circSEC24A alleviated OA progression in ACLT model.

Conclusion

CircSEC24A promotes OA progression through miR-107-5p/CASP3 axis.

Role of Serum Micro-RNA-122-5p Expression as a Circulatory Biomarker in People Having Both Knee Osteoarthritis and Osteoporosis: A Case-Control Study

Background Although knee osteoarthritis (KOA) and osteoporosis (OP) manifest distinct pathophysiologies, they share numerous similarities. These health conditions are commonly found in older individuals, particularly among women. The objective of this study is to explore the expression of micro-RNA (miRNA) 122-5p (miR-122-5p) in people affected by both KOA and OP. The main aim is to identify diagnostic biomarkers and potential therapeutic targets, which could help develop personalized treatment approaches. Methods As part of the study, a total of 268 serum samples were collected from the participants, who were divided into four groups: KOA, OP, KOA and OP, and controls, with 67 subjects per group. The miRNA species-containing total RNA was isolated from the serum samples using an miRNeasy serum/plasma kit by QIAGEN (Hilden, Germany). The expression of miR-122-5p was examined in each group using real-time quantitative polymerase chain reaction. Results Expression of miR-122-5p in all three groups (KOA, OP, and common group of KOA and OP) was significantly upregulated, and the fold change value was much higher in the group having both diseases. Conclusions These results might contribute to the identification of cases at risk, early diagnosis, and development, and might also contribute to the development of therapeutic targets in subjects having both KOA and OP.

lncRNA OIP5-AS1 attenuates the osteoarthritis progression in IL-1β-stimulated chondrocytes

In view of the association between long noncoding RNA OIP5-AS1 and osteoarthritis (OA) pathology, the corresponding potential mechanism is worthy of exploration. Primary chondrocytes were identified by morphological observation and immunohistochemical staining of collagen II. The association between OIP5-AS1 and miR-338-3p was analyzed by StarBase and dual-luciferase reporter assay. After the expression of OIP5-AS1 or miR-338-3p in interleukin (IL)-1β-stimulated primary chondrocytes and CHON-001 cells was manipulated, cell viability, proliferation, apoptosis rate, apoptosis-related protein (cleaved caspase-9, Bax) expressions, extracellular matrix (ECM) (matrix metalloproteinase (MMP)-3, MMP-13, aggrecan, and collagen II), PI3K/AKT pathway, and mRNA expressions of inflammatory factors (IL-6 and IL-8), OIP5-AS1, and miR-338-3p were determined by cell counting kit-8, EdU, flow cytometry, Western blot, and quantitative reverse transcription-polymerase chain reaction. As a result, the expression of OIP5-AS1 was downregulated in IL-1β-activated chondrocytes, while miR-338-3p was overexpressed. OIP5-AS1 overexpression reversed the effects of IL-1β on viability, proliferation, apoptosis, ECM degradation, and inflammation in chondrocytes. However, OIP5-AS1 knockdown exhibited opposite effects. Interestingly, the effects of OIP5-AS1 overexpression were partially offset by miR-338-3p overexpression. Furthermore, OIP5-AS1 overexpression blocked the PI3K/AKT pathway by modulating miR-338-3p expression. In sum, OIP5-AS1 promotes viability and proliferation, and inhibits apoptosis and ECM degradation in IL-1β-activated chondrocytes by targeting miR-338-3p through blocking the PI3K/AKT pathway, indicating an attractive strategy for OA treatment.

Exosomal miR-93-5p regulated the progression of osteoarthritis by targeting ADAMTS9

Osteoarthritis (OA) is a type of common degenerative joint disorder, in which adipose mesenchymal stem cells (ADSCs) and the secreted exosomes play an important role. The purpose of this study was to investigate the role and mechanism of exosomes derived from ADSCs (ADSC-exos) in OA. The gradient of IL-1β concentration was designed to construct the articular chondrocyte model of arthritic mice. The expression of miR-93-5p and ADAMTS9 in articular chondrocytes was detected by reverse transcription quantitative polymerase chain reaction. Dual luciferase reporter gene assay was performed to verify the interaction between them. Monodansylcadaverine staining was used to visualize the autophagosome formation and cell apoptosis was analyzed by flow cytometry. ADSC-exos were authenticated by transmission electron microscope and western blot assay. miR-93-5p was found to be downregulated in IL-1β-treated articular chondrocytes compared with OA cartilage while ADAMTS9 was upregulated, which was identified as a direct target gene of miR-93-5p. Silencing of ADAMTS9 attenuated the effects of miR-93-5p. Exosomal miR-93-5p can reduce the release of inflammatory factors in mouse arthritis cell models. This study first described the mechanism under that ADSC-exos inhibited inflammation and alleviated OA through the innovative targets miR-93-5p/ADAMTS9 signal axis. This provided a new method for the treatment of OA.

Circular RNA circ_0008360 Inhibits the Proliferation, Migration, and Inflammation and Promotes Apoptosis of Fibroblast-Like Synoviocytes by Regulating miR-135b-5p/HDAC4 Axis in Rheumatoid Arthritis

Circular RNAs (circRNAs) have been demonstrated to play crucial roles in the development and progression of many diseases, including rheumatoid arthritis (RA). However, the functions and molecular mechanism of circ_0008360 in RA remain unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to determine the expression of circ_0008360, microRNA-135b-5p (miR-135b-5p), and histone deacetylase 4 (HDAC4). Cell Counting Kit-8 (CCK-8) assay, wound healing assay, and flow cytometry analysis were performed to assess cell proliferation, migration, and apoptosis, respectively. Inflammatory response was evaluated by enzyme-linked immunosorbent assay (ELISA). The interaction between miR-135b-5p and circ_0008360 or HDAC4 was predicted by bioinformatics analysis and verified by dual-luciferase reporter and RNA Immunoprecipitation (RIP) and RNA pull-down assays. Western blot assay was used to detect the protein expression of HDAC4 and proliferating cell nuclear antigen (PCNA). The expression of circ_0008360 was downregulated in RA synovial tissues and RA fibroblast-like synoviocytes (RA-FLSs). Circ_0008360 suppressed the proliferation, migration, and inflammation and promoted apoptosis of RA-FLSs, and circ_0008360 knockdown showed opposite effects. Moreover, miR-135b-5p was a direct target of circ_0008360, and miR-135b-5p could reverse the effects of circ_0008360 on proliferation, migration, inflammation, and apoptosis in RA-FLSs. Furthermore, HDAC4 was a downstream target of miR-135b-5p, and miR-135b-5p accelerated the proliferation, migration, and inflammation and suppressed apoptosis of RA-FLSs by targeting HDAC4. In addition, circ_0008360 positively regulated HDAC4 expression by sponging miR-135b-5p. Circ_0008360 inhibited the proliferation, migration, and inflammation and facilitated apoptosis of RA-FLSs by sponging miR-135b-5p and upregulating HDAC4, providing a potential target for prevention and treatment of RA.

miR-18a-3p Encourages Apoptosis of Chondrocyte in Osteoarthritis via HOXA1 Pathway

BACKGROUND

Osteoarthritis is a disorder of joints featuring inflammation and degeneration of articular cartilage. Recently, miRs have been found to be associated in the regulation of chondrocytes and their apoptosis. miR-18a-3p has been found to be associated in the pathogenesis of rheumatoid arthritis, however, its role in articular cartilage tissues remains unclear.

METHODS

C57BL/6 strain of mice and human cartilage tissue were used for the study. Histological analysis was done on isolated cartilage samples followed by TUNEL assay and immunohistochemical analysis. The chondrocytes were isolated from mouse and human cartilage tissues, RNA was isolated and subjected for qRT-PCR analysis. The chondrocytes were transfected with miR-18a-3p agomir, antagomir and siHOXA-1. Luciferase assay was done in 293T cells. Flow cytometry analysis was done and western blot analysis for studying the expression of proteins.

RESULTS

The expression of miR-18a-3p was upregulated in chondrocytes after exposing them to interlukin- 1β (IL-1β) in vitro. The transfection of miR-18a-3p antagomir halted the IL-1β mediated apoptosis. The luciferase assay suggested that miR-18a-3p targets the 3'UTR region of HOXA1 gene thus blocking its expression. The treatment of HOXA1 siRNA demonstrated the rescuing effect of miR- 18a-3p antagomir on the apoptosis of chondrocytes. Treatment of miR-18a-3p antagomir attenuated the surface of cartilage in osteoarthritis mice and the agomir worsened it. TUNEL assay suggested decreased apoptosis and over-expression of HOAX1 in osteoarthritis mice post miR-18a-3p knockdown.

CONCLUSION

The findings confirmed the involvement of miR-18a-3p/HOXA1 pathway as a potential mechanism in the regulation of Osteoarthritis.

Long noncoding RNA ZFAS1 suppresses chondrocytes apoptosis via miR-302d-3p/SMAD2 in osteoarthritis

Osteoarthritis (OA) seriously affects people's quality of life due to joint pain, stiffness, disability, and dyskinesia worldwide. Long noncoding RNA zinc finger antisense 1 (ZFAS1) is downregulated and tightly associated with proliferation, migration, apoptosis, and matrix synthesis of chondrocyte in OA. However, the molecular mechanisms of ZFAS1 in OA remain unknown. The expression correlation between ZFAS1, miR-302d-3p, and SMAD2 in OA tissues was analyzed by Pearson correlation analysis. ZFAS1 was a lower expression, and expedited proliferation and repressed apoptosis of chondrocytes. MiR-302d-3p was a direct target of ZFAS1. MiR-302d-3p hindered proliferation and facilitated apoptosis of chondrocytes. MiR-302d-3p partially reversed the effect of ZFAS1 on proliferation and apoptosis of chondrocytes. SMAD2 was positively regulated by the ZFAS1/miR-302d-3p. MiR-302d-3p-mediated proliferation and apoptosis were partly abrogated by targeting SMAD2. ZFAS1 promoted chondrocytes proliferation and repressed apoptosis possibly by regulating miR-302d-3p/SMAD2 axis, providing a potential target for OA treatment.

Downregulation of MicroRNA-495 Alleviates IL-1β Responses among Chondrocytes by Preventing SOX9 Reduction

PURPOSE

Our previous work demonstrated that miRNA-495 targets SOX9 to inhibit chondrogenesis of mesenchymal stem cells. In this study, we aimed to investigate whether miRNA-495-mediated SOX9 regulation could be a novel therapeutic target for osteoarthritis (OA) using an in vitro cell culture model.

MATERIALS AND METHODS

An in vitro model mimicking the OA environment was established using TC28a2 normal human chondrocyte cells. Interleukin-1β (IL-1β, 10 ng/mL) was utilized to induce inflammation-related changes in TC28a2 cells. Safranin O staining and glycosaminoglycan assay were used to detect changes in proteoglycans among TC28a2 cells. Expression levels of COX-2, ADAMTS5, MMP13, SOX9, CCL4, and COL2A1 were examined by qRT-PCR and/or Western blotting. Immunohistochemistry was performed to detect SOX9 and CCL4 proteins in human cartilage tissues obtained from patients with OA.

RESULTS

miRNA-495 was upregulated in IL-1β-treated TC28a2 cells and chondrocytes from damaged cartilage tissues of patients with OA. Anti-miR-495 abolished the effect of IL-1β in TC28a2 cells and rescued the protein levels of SOX9 and COL2A1, which were reduced by IL-1β. SOX9 was downregulated in the damaged cartilage tissues of patients with OA, and knockdown of SOX9 abolished the effect of anti-miR-495 on IL-1β-treated TC28a2 cells.

CONCLUSION

We demonstrated that inhibition of miRNA-495 alleviates IL-1β-induced inflammatory responses in chondrocytes by rescuing SOX9 expression. Accordingly, miRNA-495 could be a potential novel target for OA therapy, and the application of anti-miR-495 to chondrocytes could be a therapeutic strategy for treating OA.

Human bone mesenchymal stem cells-derived exosomal miRNA-361-5p alleviates osteoarthritis by downregulating DDX20 and inactivating the NF-κB signaling pathway

Osteoarthritis (OA) is a chronic disease featured by joint hyperplasia, deterioration of articular cartilage, and progressive degeneration. Abnormal expression of microRNAs (miRNAs) has been found to be implicated in the pathological process of OA. In this study, the role of miR-361-5p transferred by exosomes derived from human bone mesenchymal stem cells (hBMSCs) in OA was investigated. The expression of Asp-Glu-Ala-Asp-box polypeptide 20 (DDX20) and miR-361-5p in interleukin-1β (IL-1β)-treated chondrocytes was determined by reverse transcription quantitative polymerase chain reaction. DDX20 was knocked down by transfection of short hairpin RNA targeting DDX20, and the effects of DDX20 downregulation on IL-1β-induced damage of chondrocytes were detected. The interaction between DDX20 and miR-361-5p was tested by luciferase report assay. hBMSCs-derived exosomes loaded with miR-361-5p were co-incubated with chondrocytes followed by detection of cell viability, proliferation and inflammatory response. An OA rat model was established to further explore the role of miR-361-5p in vivo. Western blot, luciferase reporter and immunofluorescence staining assays were used to evaluate the activation of the nuclear factor kappa-B (NF-κB) signaling pathway. We found that DDX20 was upregulated, while miR-361-5p was underexpressed in IL-1β-treated chondrocytes. Downregulation of DDX20 inhibits levels of matrix metalloproteinases (MMPs) and suppresses inflammation induced by IL-1β. Mechanistically, miR-361-5p was verified to directly target DDX20. In addition, hBMSC-derived exosomes-transferred miR-361-5p alleviates chondrocyte damage and inhibits the NF-κB signaling pathway via targeting DDX20. Inhibition of NF-κB signaling reverses the effect of overexpressed DDX20 on IL-1β-induced chondrocyte damage. Moreover, exosomal miR-361-5p alleviates OA damage in vivo. Overall, hBMSC-derived exosomal miR-361-5p alleviates OA damage by targeting DDX20 and inactivating the NF-κB signaling pathway.

Circular RNA circ_0128846 promotes the progression of osteoarthritis by regulating miR-127-5p/NAMPT axis

Background

Mounting evidence indicates that circular RNAs (circRNAs) participate in the occurrence and development of various diseases, including osteoarthritis (OA). However, the effects and molecular mechanism of circ_0128846 in OA have not been reported.

Methods

The expression levels of circ_0128846, microRNA-127-5p (miR-127-5p), and nicotinamide phosphoribosyltransferase (NAMPT) were determined by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay. Cell viability was determined by Cell Counting Kit-8 (CCK-8) assay. Cell apoptosis was examined by flow cytometry and western blot assay. Inflammatory response and cartilage extracellular matrix (ECM) degradation were evaluated by western blot assay. The relationship between miR-127-5p and circ_0128846 or NAMPT was predicted by bioinformatics tools and verified by dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays.

Results

Circ_0128846 and NAMPT were upregulated and miR-127-5p was downregulated in OA cartilage tissues. Knockdown of circ_0128846 increased cell viability and inhibited apoptosis, inflammation and ECM degradation in OA chondrocytes, while these effects were reversed by downregulating miR-127-5p. Moreover, circ_0128846 positively regulated NAMPT expression by sponging miR-127-5p. Furthermore, miR-127-5p promoted cell viability and suppressed apoptosis, inflammation, and ECM degradation in OA chondrocytes by directly targeting NAMPT.

Conclusion

Circ_0128846 knockdown might inhibit the progression of OA by upregulating miR-127-5p and downregulating NAMPT, offering a new insight into the potential application of circ_0128846 in OA treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02428-z.

miR-137 targets the inhibition of TCF4 to reverse the progression of osteoarthritis through the AMPK/NF-κB signaling pathway

Purpose: To explore the regulatory mechanism of miR-137 and transcription factor 4 (TCF4) in the progression of osteoarthritis (OA).

Patients and Methods: The expressions of miR-137 and TCF4 were detected in OA cartilage tissue, chondrocytes and OA rat cartilage tissue. miR-137 and TCF4 were up-regulated or down-regulated and transfected into chondrocytes and OA rat cartilage tissue. The gene expression, protein level, cell proliferation, apoptosis and inflammatory factors were detected, respectively. LPS and anterior cruciate ligament transection (ACLT) on the right knee were used to induce chondrocyte inflammation and establish rat OA model, respectively.

Results: miR-137 was low expressed in cartilage tissue of OA group, while TCF4 expression and protein level were significantly higher, showing significant negative correlation. In LPS group, chondrocyte activity was significantly inhibited, cell apoptosis ability was significantly enhanced, and the levels of inflammatory factors TNF-α, IL-1β, IL-6 were significantly increased. However, the above results were significantly improved after the up-regulation of miR-137 or down-regulation of TCF4. Double luciferase report revealed that miR-137 and TCF4 had targeted relationship. LPS induced activation of AMPK/NF-κB pathway and higher level of apoptosis. AMPK/NF-κB pathway inhibitor C could inhibit activation of this pathway, and up-regulation of miR-137 or down-regulation of TCF4 could significantly weaken the regulation of LPS on the pathway and apoptosis. Analysis of OA rat model showed that over-expression of miR-137 could inhibit up-regulation of inflammatory factors and activation of AMPK/NF-κB pathway.

Conclusion: miR-137 targets the inhibition of TCF4 to reverse the progression of OA through the AMPK/NF-κB signaling pathway.

MiRNA-132 regulates the development of osteoarthritis in correlation with the modulation of PTEN/PI3K/AKT signaling

Background

Osteoarthritis (OA) is a commonly known prevalent joint disease, with limited therapeutic methods. This study aimed to investigate the functions of miRNA-132 (miR-132) in the modulation of PTEN/PI3K/AKT signaling pathway in the development and progression of osteoarthritis.

Methods

Eight male osteoarthritic patients and eight healthy males were recruited. Male Sprague Dawley (SD) rats were used for cellular experiments. QRT-PCR was performed to detect the expression levels of miR-132, PTEN, PI3K and AKT. MTT assay and apoptosis assay were carried out to measure the cell proliferation rate and cell apoptosis rate, respectively. Western blotting was employed to detect the protein expression of related RNAs and inflammatory factors.

Results

In osteoarthritic patients, the expression level of miR-132 was decreased, compared with that in the normal group. Over-expression of miR-132 elevated cell proliferation and decreased apoptosis of chondrocytes. Down-regulation of miR-132 decreased cell proliferation and induced apoptosis in chondrocytes. In addition, down-regulation of miR-132 promoted the expression of Bax protein and activated caspase-3/9, increased inflammation divisors. PTEN inhibitor antagonized the destructive effect of the miR-132 inhibitor on cell proliferation of chondrocytes. PI3K inhibitor increased the destructive effect of the miR-132 inhibitor on osteoarthritis.

Conclusion

In conclusion, miR-132 is an important regulator of osteoarthritis in chondrocytes through the PTEN/PI3K/AKT signaling pathway.

CircSEC24A promotes IL-1β-induced apoptosis and inflammation in chondrocytes by regulating miR-142-5p/SOX5 axis

BACKGROUND

Osteoarthritis (OA) is a common joint disease. Currently, many studies have revealed that circular RNAs (circRNAs) are strongly related to the occurrence and development of diseases. Hence, we aimed to further elucidate the role and molecular mechanism of circRNA SEC24 homolog A, COPII coat complex component (circSEC24A) in OA.

METHODS

Chondrocytes were treated with interleukin-1β (IL-1β) to establish OA cell model in vitro. The expression levels of circSEC24A, microRNA-142-5p (miR-142-5p), and sex-determining region Y-box protein 5 (SOX5) were determined by quantitative real-time polymerase chain reaction. MTT and colony formation assays were used to determine cell proliferation. Cell apoptosis was detected by flow cytometry analysis. The protein levels of inflammatory factors and SOX5 were determined by western blot assay. The relationship between miR-142-5p and circSEC24A or SOX5 was confirmed using dual-luciferase reporter assay and RNA immunoprecipitation assay.

RESULTS

CircSEC24A and SOX5 expression were enhanced, while miR-142-5p level was reduced in OA cartilage tissues and chondrocytes. Overexpression of circSEC24A promoted IL-1β-induced injury through decreasing cell proliferation and increasing apoptosis and inflammation in chondrocytes. MiR-142-5p was a direct target of circSEC24A, and its upregulation ameliorated IL-1β-induced injury and abated the effect of oe-circSEC24A in IL-1β-induced chondrocytes. Additionally, SOX5 was a downstream target of miR-142-5p, and its overexpression had a similar role with oe-circSEC24A and reversed the impact of miR-142-5p in IL-1β-induced chondrocytes. CircSEC24A acted as a molecular sponge of miR-142-5p to regulate SOX5 expression in chondrocytes.

CONCLUSION

CircSEC24A aggravated IL-1β-induced injury via modulating miR-142-5p/SOX5 axis, providing possible targets for the clinical diagnosis and treatment of OA.

MiR-467b alleviates lipopolysaccharide-induced inflammation through targeting STAT1 in chondrogenic ATDC5 cells

Osteoarthritis (OA) is one of the most common degenerative joint diseases worldwide. Chondrocytes are activated in OA patients, accompanied by excessive chondrogenic proliferation and production of inflammatory cytokines. MiR-467b is implicated in the regulation of artherosclerosis and pro-inflammatory cytokine secretion. However, the precise role of miR-467b in OA remains unclear. In the present study, we induced inflammation in chondrogenic ATDC5 cells using lipopolysaccharide (LPS). LPS treatment significantly elevated the production of interleukin-6 (IL-6), IL-1β and tumour necrosis factor-α (TNF-α) in ATDC5 cells, accompanied by decreased miR-467 level. Then, we over-expressed miR-467b using its specific mimics in ATDC5 cells, and LPS-induced inflammation was significantly inhibited as evidenced by decreased IL-6, IL-1β and TNF-α levels. MiR-467b agomir also alleviated inflammation in rat knee osteoarthritis (KOA) model. In addition, we validated that signal transducer and activator of transcription 1 (STAT1) was a downstream target of miR-467b. LPS treatment significantly increased the STAT1 expression while miR-467b mimic transfection partially reversed this effect. Moreover, STAT1 knockout reversed the increased contents of IL-6, IL-1β and TNF-α. Furthermore, miR-467b over-expression significantly decreased the production of IL-6, IL-1β and TNF-α induced by LPS treatment, which was partially reversed by further STAT1 over-expression. In summary, our findings demonstrated that miR-467b alleviated LPS-induced inflammation through targeting STAT1, and this miR-467b/STAT1 regulation axis may provide a new therapeutic target for OA clinical management.

MicroRNA‑186‑5p downregulation inhibits osteoarthritis development by targeting MAPK1

As a chronic degenerative joint disease, the characteristics of osteoarthritis (OA) are degeneration of articular cartilage, subchondral bone sclerosis and bone hyperplasia. It has been reported that microRNA (miR)-186-5p serves a key role in the development of various tumors, such as osteosarcoma, non-small-cell lung cancer cells, glioma and colorectal cancer. The present study aimed to investigate the effect of miR-186-5p in OA. Different concentrations of IL-1β were used to treat the human chondrocyte cell line CHON-001 to simulate inflammation, and CHON-001 cell injury was assessed by detecting cell viability, apoptosis, caspase-3 activity and the levels of TNF-α, IL-8 and IL-6. Subsequently, reverse transcription-quantitative PCR was performed to measure miR-186-5p expression. The results demonstrated that following IL-1β treatment, CHON-001 cell viability was suppressed, apoptosis was promoted, the caspase-3 activity was significantly enhanced and the release of TNF-α, IL-8 and IL-6 was increased. In addition, IL-1β treatment significantly upregulated miR-186-5p expression in CHON-001 cells. It was also identified that MAPK1 was a target gene of miR-186-5p, and was negatively regulated by miR-186-5p. miR-186 inhibitor and MAPK1-small interfering RNA (siRNA) were transfected into CHON-001 cells to investigate the effect of miR-186-5p on CHON-001 cell injury induced by IL-1β. The results demonstrated that miR-186 inhibitor suppressed the effects of IL-1β on CHON-001 cells, and these effects were reversed by MAPK1-siRNA. In conclusion, the present results indicated that miR-186-5p could attenuate IL-1β-induced chondrocyte inflammation damage by increasing MAPK1 expression, suggesting that miR-186-5p may be used as a potential therapeutic target for OA.

MicroRNA-320c inhibits articular chondrocytes proliferation and induces apoptosis by targeting mitogen-activated protein kinase 1 (MAPK1)

AIM

To clarify the interaction of microRNA-320c (miR-320c) and mitogen-activated protein kinase 1 (MAPK1), and to investigate the effects of miR-320c on articular chondroctye proliferation and apoptosis.

METHODS

Lentiviral expression vectors were constructed and dual luciferase assays containing MAPK1 3'-untranslated regions (3'-UTRs) were performed. Small hairpin RNA (shRNA) was utilized to modulate MAPK1 expression. The messenger RNA and protein expression levels were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting respectively. Cell Counting Kit-8 and flow cytometry were conducted to detect the proliferation and apoptosis of Human Chondrocyte-articular (HC-a) cells. Besides that, the influences of miR-320c and MAPK1 on MAPK pathway activation were also evaluated.

RESULTS

Our data identified MAPK1 as a direct target gene of miR-320c, and miR-320c can negatively regulate MAPK1 expression by directly binding to MAPK1 3'-UTR in HC-a cells. Further functional study displayed that miR-320c overexpression and MAPK1 shRNA significantly suppressed the proliferation of HC-a cells and promoted cell apoptosis. Meanwhile, MAPK1 shRNA could attenuate miR-320c inhibitor promotive effects on HC-a cell proliferation and reverse its inhibitory effect on cell apoptosis. MAPK1 overexpression could rescue the inhibitory effect of miR-320c on HC-a cell proliferation, and weaken the accelerating effect of miR-320c on cell apoptosis. However, neither miR-320c or MAPK1 shRNA regulate the expression of c-JUN, JNK and c-Fos.

CONCLUSION

miR-320c inhibits articular chondrocyte proliferation and induces apoptosis by targeting MAPK1, suggesting that miR-320c perhaps participates in the pathogenesis of osteoarthritis and acts as a potential target for the therapeutic treatment of osteoarthritis.

MiR-155 promotes interleukin-1β-induced chondrocyte apoptosis and catabolic activity by targeting PIK3R1-mediated PI3K/Akt pathway

Osteoarthritis (OA) is a common joint disease characterized by progressive cartilage degradation, in which elevated chondrocyte apoptosis and catabolic activity play an important role. MicroRNA-155 (miR-155) has recently been shown to regulate apoptosis and catabolic activity in some pathological circumstances, yet, whether and how miR-155 is associated with OA pathology remain unexplored. We report here that miR-155 level is significantly up-regulated in human OA cartilage biopsies and also in primary chondrocytes stimulated by interleukin-1β (IL-1β), a pivotal pro-catabolic factor promoting cartilage degradation. Moreover, miR-155 inhibition attenuates and its overexpression promotes IL-1β-induced apoptosis and catabolic activity in chondrocytes in vitro. We also demonstrate that the PIK3R1 (p85α regulatory subunit of phosphoinositide 3-kinase (PI3K)) is a target of miR-155 in chondrocytes, and more importantly, PIK3R1 restoration abrogates miR-155 effects on chondrocyte apoptosis and catabolic activity. Mechanistically, PIK3R1 positively regulates the transduction of PI3K/Akt pathway, and a specific Akt inhibitor reverses miR-155 effects on promoting chondrocyte apoptosis and catabolic activity, phenocopying the results obtained via PIK3R1 knockdown, hence establishing that miR-155 promotes chondrocyte apoptosis and catabolic activity through targeting PIK3R1-mediated PI3K/Akt pathway activation. Altogether, our study discovers novel roles and mechanisms of miR-155 in regulating chondrocyte apoptosis and catabolic activity, providing an implication for therapeutically intervening cartilage degradation and OA progression.

Circular RNA-9119 protects IL-1β-treated chondrocytes from apoptosis in an osteoarthritis cell model by intercepting the microRNA-26a/PTEN axis

AIMS

Osteoarthritis (OA) is a common degenerative joint disease characterized by cartilage degeneration and joint inflammation. As its pathogenesis remains unclear, there are no effective treatments established. Circular RNA (circRNA), microRNA (miRNA), and other noncoding RNAs participate in OA development; however, the effects and mechanisms of circRNA and miRNA in OA remain unknown.

MAIN METHODS

Cartilage miRNA was examined in patients with and without OA.

KEY FINDINGS

CircRNA-9119 and phosphatase and tensin homolog (PTEN) expression decreased in OA-affected cartilage and interleukin (IL)-1β-induced chondrocytes, and miR-26a expression significantly decreased in normal cells and tissues. CircRNA-9119 overexpression restored chondrocyte growth, whereas IL-1β treatment impaired chondrocyte growth. Annexin V-FITC & PI flow cytometry and Bcl-2/Bax ratio measurement indicated that the apoptosis of IL-1β-treated articular chondrocytes was decreased by circRNA-9119 upregulation. Bioinformatic prediction and the dual-luciferase reporter assay indicated that circRNA-9119 served as a miR-26a sponge and that miR-26a targeted the 3'-UTR of PTEN. Transfection of chondrocytes with a circRNA-9119-overexpressing vector revealed downregulation of miR-26a expression. Furthermore, circRNA-9119 overexpression induced PTEN expression. In addition, a miR-26a mimic induced IL-1β-induced chondrocyte apoptosis, and circRNA-9119 overexpression inhibited IL-1β-induced chondrocyte apoptosis.

SIGNIFICANCE

CircRNA-9119 is an important regulator of IL-1β-treated chondrocytes through the miR-26a/PTEN axis, possibly contributing to OA development.

RETRACTED: Human bone mesenchymal stem cells-derived exosomes overexpressing microRNA-26a-5p alleviate osteoarthritis via down-regulation of PTGS2

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figures 2E, 3D and F, 4B, E+G, 5D+I, and 6D+F, which appear to have a similar phenotype as contained in many other publications, detailed here: https://pubpeer.com/publications/73C0A79F5EDF9ECC9818CE2D9B2A09; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. The provenance of the flow cytometry data in Figure 5A was also questioned, as it appeared to have histograms that were hand drawn. The journal requested the corresponding author comment on these concerns and provide the raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.

Osteoarthritis from evolutionary and mechanistic perspectives

Developmental osteogenesis and the pathologies associated with tissues that normally are mineralized are active areas of research. All of the basic cell types of skeletal tissue evolved in early aquatic vertebrates. Their characteristics, transcription factors, and signaling pathways have been conserved, even as they adapted to the challenge imposed by gravity in the transition to terrestrial existence. The response to excess mechanical stress (among other factors) can be expressed in the pathologic phenotype described as osteoarthritis (OA). OA is mediated by epigenetic modification of the same conserved developmental gene networks, rather than by gene mutations or new chemical signaling pathways. Thus, these responses have their evolutionary roots in morphogenesis. Epigenetic channeling and heterochrony, orchestrated primarily by microRNAs, maintain the sequence of these responses, while allowing variation in their timing that depends at least partly on the life history of the individual.

MiR-27a promotes the autophagy and apoptosis of IL-1β treated-articular chondrocytes in osteoarthritis through PI3K/AKT/mTOR signaling

Osteoarthritis (OA) is a common degenerative joint disorder, which involves articular cartilage degeneration as well as joint inflammatory reactions. The recent studies have identified microRNA (miRNA) as one of the epigenetic mechanisms for the regulation of gene expression. Here we aim to reveal the role of miRNA in the regulation of gene expression in articular chondrocytes and its significance in the OA pathogenesis. In the present study, miRNA profiling was performed using OA cartilage and normal healthy cartilage tissues. As compared to their levels in normal cells and tissues, miR-27a expression was found to be upregulated in OA cartilage and IL-1β-treated articular chondrocytes. TUNEL staining, as well as flow cytometry with Annexin V-FITC/PI double labeling indicated that miR-27a inhibition reduced the apoptosis of IL-1β-treated articular chondrocytes. Bioinformatics prediction and the dual-luciferase reporter assay indicated that miR-27a targeted the 3'-UTR of the PI3K gene to silence it. The PI3K mRNA level in OA cartilage and IL-1β-treated articular chondrocytes was also downregulated, comparing with normal cells and tissues. Transfection of chondrocytes transfected with the miR-27a inhibitor upregulated the PI3K expression. This study demonstrated miR-27a is a regulator of the PI3K-Akt-mTOR axis in human chondrocytes and could participate in OA pathogenesis.

Mechanism of miR-15a regulating the growth and apoptosis of human knee joint chondrocytes by targeting SMAD2

Objective: To investigate the effects of miR-15a on proliferation and apoptosis of human knee articular chondrocytes and explore its underlying mechanism. Methods: qRT-PCR was used to detect the expression of miR-15a in normal chondrocytes and knee arthritic chondrocytes; miR-con (transfected miR-con), miR-15a (transfected miR-15a mimics), anti-miR-con group (transfected anti-miR-con), anti-miR-15a group (transfected anti-miR-15a mimics), pcDNA group (transfected pcDNA), pcDNA-SMAD2 group (transfected pcDNA-SMAD2), the miR-15a + pcDNA group (co-transfected miR-15a and pcDNA), miR-15a + pcDNA-SMAD2 group (co-transfected miR-15a mimics and pcDNA-SMAD2), were transfected into knee articular chondrocytes by liposome method, respectively. The cell proliferation and apoptosis of each group were detected by MTT assay and flow cytometry. The protein expression of SMAD2 was detected by Western blot. The fluorescence activity of each group was detected by dual luciferase reporter gene assay. Results: The expression of miR-15a in knee arthritis chondrocytes was significantly increased (p < .05) compared with that in normal chondrocytes. Moreover, overexpression of miR-15a and silencing of SMAD2 inhibited proliferation and promoted apoptosis in knee arthritis chondrocyte. MiR-15a targeted SMAD2. Overexpression of SMAD2 reversed the inhibitory effects on proliferation and promotion effects on apoptosis induced by miR-15a in knee arthritis chondrocytes. Conclusion: miR-15a can inhibit the proliferation and promote apoptosis of knee arthritis chondrocytes. The mechanism may be related to SMAD2, which will provide a new target for the treatment of knee arthritis.

Synovial Fluid MicroRNA-210 as a Potential Biomarker for Early Prediction of Osteoarthritis

Early detection and treatment are critical in the management of osteoarthritis (OA). OA is closely associated with angiogenesis and the inhibition of angiogenesis presents a novel therapeutic approach to reduce inflammation and pain in OA. Recent reports suggest that circulating microRNAs (miRNAs) have great potential as biomarkers for the diagnosis and prognosis in OA. In this study, we aimed to explore the clinical significance of miR-210 in synovial fluid samples from 10 healthy volunteers and 20 early-stage OA and 20 late-stage OA patients. miR-210 expression was assessed by real-time RT-PCR. VEGF protein levels were examined by ELISA. The results show that miR-210 is significantly upregulated in early-stage OA and late-stage OA patients compared with healthy individuals. Higher levels of VEGF are also found in OA compared with the control. Moreover, miR-210 levels are positively correlated with VEGF levels, suggesting that miR-210 might contribute to OA development through promoting VEGF expression and angiogenesis. In conclusion, upregulation of miR-210 in synovial fluid may occur in the early stage of OA and can be a useful biomarker for early diagnosis of OA.

MicroRNA-15a-5p Regulates the Development of Osteoarthritis by Targeting PTHrP in Chondrocytes

BACKGROUND AND AIMS

A growing body of research has demonstrated that the degeneration of chondrocytes is the primary cause of osteoarthritis (OA). Parathyroid hormone-related protein (PTHrP) can alleviate the degeneration of chondrocytes via promotion of chondrocyte proliferation and inhibition of terminal differentiation, but the underlying mechanism remains unknown. This study aimed to identify the microRNAs (miRNAs) that may target PTHrP and regulate the proliferation and terminal differentiation of chondrocytes.

METHODS

Bioinformatic analysis was used to predict which miRNAs target PTHrP. We collected human knee cartilage specimens to acquire the primary chondrocytes, which we then used to test the expression and function of the targeted miRNAs. To explore the effects of miR-15a-5p on the putative binding sites, specific mimics or inhibitors were transfected into the chondrocytes. Furthermore, a dual-luciferase reporter gene assay and chondrocyte degeneration-related factors were used to verify the possible mechanism.

RESULTS

The expression of PTHrP was upregulated in the OA chondrocytes, whilst miR-15a-5p was downregulated in the OA chondrocytes. A negative correlation was observed between PTHrP and miR-15a-5p. The knockdown of miR-15a-5p promoted the growth of chondrocytes and inhibited calcium deposition, whilst overexpression of miR-15a-5p reversed this trend. The effect of miR-15a-5p overexpression was neutralised by PTHrP. Dual-luciferase reporter assays revealed that PTHrP can be used as a novel targeting molecule for miR-15a-5p.

CONCLUSIONS

miR-15a-5p promotes the degeneration of chondrocytes by targeting PTHrP and, in addition to helping us understand the development of OA, may be a potential biomarker of OA.

miR-10a-5p Promotes Chondrocyte Apoptosis in Osteoarthritis by Targeting HOXA1

Osteoarthritis (OA) is a common joint disease characterized by degradation of the articular cartilage and joint inflammation. Studies have revealed the importance of microRNAs in the regulation of chondrocyte apoptosis. MicroRNA deep sequencing of control and osteoarthritic cartilage has revealed that miR-10a-5p is significantly upregulated in osteoarthritic tissues. However, its role in these tissues remains unknown. The present study was conducted to investigate the effect of miR-10a-5p in promoting OA. miR-10a-5p expression was increased in chondrocytes after interleukin-1β treatment in vitro. Transfection with a miR-10a-5p inhibitor abrogated interleukin-1β-induced apoptosis. A luciferase activity assay showed that miR-10a-5p targeted the 3′ UTR of the homeobox gene HOXA1, inhibiting its expression. Treatment with HOXA1 siRNA reversed the rescuing effect of the miR-10a-5p inhibitor on chondrocyte apoptosis. Additionally, an OA model was established in mice by anterior cruciate ligament transection. AntagomiR-10a-5p improved the cartilage surfaces of osteoarthritic mice, whereas agomiR-10a-5p worsened them. A terminal deoxynucleotidyl transferase dUTP nick-end labeling assay indicated reduced apoptosis and increased HOXA1 expression in osteoarthritic mice after miR-10a-5p knockdown. These findings reveal a novel mechanism regulating OA progression and demonstrate the potential of miR-10a-5p and homeobox protein HOXA1 as therapeutic targets.

Precision Health: Use of Omics to Optimize Self-Management of Chronic Pain in Aging

Chronic pain has become a public health epidemic based on the number of Americans affected and its associated health care costs. Unfortunately, there are few efficacious treatments to manage chronic pain and as the population of older adults and centenarians who are at high risk for chronic pain continues to grow, the chronic pain epidemic will continue to worsen unless new therapeutic strategies are discovered. In the current era of precision medicine, there is a major emphasis being placed on the use of self-management and omics to discover new therapeutic targets and design treatment strategies that are tailored to the individual patient. This commentary discusses the current state of the science related to omics and self-management of chronic pain in older adults, the role of gerontological nurses in this process, and future directions. [Res Gerontol Nurs. 2018; 11(1):7-13.].

microRNA-590-5p targets transforming growth factor β1 to promote chondrocyte apoptosis and autophagy in response to mechanical pressure injury

This study aimed to investigate the role of miR-590-5p in chondrocyte apoptosis and autophagy in response to mechanical pressure injury in vitro, as well as to elucidate its regulatory mechanism in the pathogenesis of osteoarthritis. We applied mechanical pressure of 10 MPa to chondrocytes for 60 minutes to establish the chondrocyte model of experimentally induced mechanical injury. We then investigated the expression of miR-590-5p in the injury model and the effects of miR-590-5p dysregulation on the expression of cell apoptosis-related and autophagy-related proteins. Cell apoptosis was detected by flow cytometry. Moreover, the potential targets of miR-590-5p were investigated. Mechanical pressure injury resulted in a significantly increased expression of miR-590-5p. Suppression of miR-590-5p significantly increased chondrocytes viability, inhibited chondrocytes apoptosis and autophagy in response to mechanical pressure injury. In addition, mechanical pressure injury led to a decreased expression of transforming growth factor β1 (TGFβ1). Moreover, TGFβ1 was confirmed as a direct target of miR-590-5p. Knockdown of TGFβ1 significantly induced chondrocytes apoptosis and autophagy in response to mechanical pressure injury, which was contrary to the effects of miR-590-5p suppression. Furthermore, overexpression of TGFβ1 and miR-590-5p at the same time significantly reversed the effects of overexpression of miR-590-5p alone on chondrocytes apoptosis and autophagy. Our results indicate that upregulation of miR-590-5p may target TGFβ1 to promote chondrocyte apoptosis and autophagy in response to mechanical pressure injury, thus contributing to the pathogenesis of osteoarthritis.

MicroRNAs and Osteoarthritis

An imbalance in gene expressional events skewing chondrocyte anabolic and catabolic pathways toward the latter causes an aberrant turnover and loss of extracellular matrix proteins in osteoarthritic (OA) articular cartilage. Thus, catabolism results in the elevated loss of extracellular matrix proteins. There is also evidence of an increase in the frequency of chondrocyte apoptosis that compromises the capacity of articular cartilage to undergo repair. Although much of the fundamental OA studies over the past 20 years identified and characterized many genes relevant to pro-inflammatory cytokines, apoptosis, and matrix metalloproteinases (MMPs)/a disintegrin and metalloproteinase with thrombospondin motif (ADAMTS), more recent studies focused on epigenetic mechanisms and the associated role of microRNAs (miRs) in regulating gene expression in OA cartilage. Thus, several miRs were identified as regulators of chondrocyte signaling pathways, apoptosis, and proteinase gene expression. For example, the reduced expression of miR-146a was found to be coupled to reduced type II collagen (COL2) in OA cartilage, whereas MMP-13 levels were increased, suggesting an association between MMP-13 gene expression and COL2A1 gene expression. Results of these studies imply that microRNAs could become useful in the search for diagnostic biomarkers, as well as providing novel therapeutic targets for intervention in OA.

Next-generation sequencing identifies articular cartilage and subchondral bone miRNAs after ESWT on early osteoarthritis knee

Extracorporeal shockwave therapy (ESWT) has shown chondroprotective effects on the initiation of the osteoarthritis (OA) changes of the rat knee. This study evaluated 69 significant expressed profiles of microRNA (miRNA) in the articular cartilage and subchondral bone after ESWT. There were 118 target genes identified for miRNAs of interest in articular cartilage and 214 target genes in subchondral bone by next generation sequencing (NGS). In principal component analysis (PCA), the relationships of miRNA expression in bone and cartilage were improved after ESWT. Global functional annotation showed that predicted targets were involved in cartilage development, inflammatory and immune response, ion binding, angiogenesis, cell adhesion, cell cycle, transcription and translation, gene expression, NTP binding, signal transduction, collagen fibril organization, apoptotic process, chondrocyte differentiation, cell differentiation, bone development as well as cell proliferation. The miRNAs profile and the target genes were comprehensively surveyed and compared in articular cartilage and subchondral bone of early OA knee before and after ESWT. Our study represents the direct assessment to date of miRNA expression profiling in early OA articular cartilage and subchondral bone. The results provide insights that could contribute to the development of new biomarkers and therapeutic strategies for OA changes and the treatment with ESWT.

Inhibition of miR-20 promotes proliferation and autophagy in articular chondrocytes by PI3K/AKT/mTOR signaling pathway

Osteoarthritis is a common cause of functional deterioration in older adults and is an immense burden on the aging population. The molecular mechanism underlying the regulation of chondrocyte requires further elucidation, particularly with respect to the role of microRNAs. The aim of this study was to identify and characterize the expression of miR-20 in normal and OA chondrocytes, and to determine its role in OA pathogenesis. MiR-20 expression in cartilage specimens was examined in 30 patients with knee osteoarthritis and 30 traumatic amputees. The effect of miR-20 on chondrocyte was also investigated in chondrocyte cell line. Transfection with miR-20 mimic or inhibitor was employed to investigate the effect of miR-20 on chondrocyte proliferation and autophagy. Cell proliferation activity was detected by MTT assay and clone formation, cell autophagy were evaluated by monodansylcadaverine staining and GFP-LC3 fluorescence microscopy. Western blotting and immunohistochemical were utilized to detect expressions of autophagy markers (LC3, Beclin1 and p62) and of relevant proteins in the PI3K/AKT/mTOR signaling pathway. The results demonstrated that miR-20 inhibit chondrocyte proliferation and autophagy by targeting ATG10 via PI3K/AKT/mTOR signaling pathway. Our data suggest that miR-20 has an important role in the pathogenesis of osteoarthritis and is a potential therapeutic target.

Integrated microRNA-mRNA analyses of distinct expression profiles in follicular thyroid tumors

MicroRNAs (miRNAs/miRs) are small non-coding RNAs identified in plants, animals and certain viruses; they function in RNA silencing and post-transcriptional regulation of gene expression. miRNAs also serve an important role in the pathogenesis, diagnosis and treatment of tumors. However, few studies have investigated the role of miRNAs in thyroid tumors. In the present study, the expression of miRNA and mRNA was compared between follicular thyroid carcinoma (FTC) and follicular thyroid adenoma (FA) samples, and then miRNA-mRNA regulatory network analysis was performed. Microarray datasets (GSE29315 and GSE62054) were downloaded from the Gene Expression Omnibus, and profiling data were processed with R software. Differentially expressed miRNAs (DEMs) and differentially expressed genes (DEGs) were determined, and Gene Ontology enrichment analysis was subsequently performed for DEGs using the Database for Annotation, Visualization and Integrated Discovery. The target genes of the DEMs were identified with miRWalk, miRecords and TarMir databases. Network analysis of the DEMs and DEMs-targeted DEGs was performed using Cytoscape software. In GSE62054, 23 downregulated and 9 upregulated miRNAs were identified. In GSE29315, 42 downregulated and 44 upregulated mRNAs were identified. A total of 36 miRNA-gene pairs were also identified. Network analysis indicated a co-regulatory association between miR-296-5p, miR-10a, miR-139-5p, miR-452, miR-493, miR-7, miR-137, miR-144, miR-145 and corresponding targeted mRNAs, including TNF receptor superfamily member 11b, benzodiazepine receptor (peripheral) -associated protein 1, and transforming growth factor β receptor 2. These results suggest that miRNA-mRNAs networks serve an important role in the pathogenesis, diagnosis and treatment of FTC and FA.

Genome-Wide DNA Methylation Study Identifies Significant Epigenomic Changes in Osteoarthritic Subchondral Bone and Similarity to Overlying Cartilage

OBJECTIVE

To perform a genome-wide DNA methylation study to identify differential DNA methylation patterns in subchondral bone underlying eroded and intact cartilage from patients with hip osteoarthritis (OA) and to compare these with DNA methylation patterns in overlying cartilage.

METHODS

Genome-wide DNA methylation profiling using Illumina HumanMethylation 450 arrays was performed on eroded and intact cartilage and subchondral bone from within the same joint of 12 patients undergoing hip arthroplasty. Genes with differentially methylated CpG sites were analyzed to identify shared pathways, upstream regulators, and overrepresented gene ontologies, and these patterns were compared with those of the overlying cartilage. Histopathology was graded by modified Mankin score and assessed for correlation with DNA methylation.

RESULTS

We identified 7,316 differentially methylated CpG sites in subchondral bone underlying eroded cartilage, most of which (∼75%) were hypomethylated, and 1,397 sites in overlying eroded cartilage, 126 of which were shared. Samples clustered into 3 groups with distinct histopathologic scores. We observed differential DNA methylation of genes including the RNA interference-processing gene AGO2, the growth factor TGFB3, the OA suppressor NFATC1, and the epigenetic effector HDAC4. Among known susceptibility genes in OA, 32 were differentially methylated in subchondral bone, 8 were differentially methylated in cartilage, and 5 were shared. Upstream regulator analysis using differentially methylated genes in OA subchondral bone showed a strong transforming growth factor β1 signature (P = 1 × 10(-40) ) and a tumor necrosis factor family signature (P = 3.2 × 10(-28) ), among others.

CONCLUSION

Our data suggest the presence of an epigenetic phenotype associated with eroded OA subchondral bone that is similar to that of overlying eroded OA cartilage.

MicroRNA-29b Contributes to Collagens Imbalance in Human Osteoarthritic and Dedifferentiated Articular Chondrocytes

Objective

Decreased expression of collagen type II in favour of collagen type I or X is one hallmark of chondrocyte phenotype changes in osteoarthritic (OA) cartilage. MicroRNA- (miR-) 29b was previously shown to target collagens in several tissues. We studied whether it could contribute to collagen imbalance in chondrocytes with an impaired phenotype.

Methods

After preliminary microarrays screening, miR-29b levels were measured by RT- quantitative PCR in in vitro models of chondrocyte phenotype changes (IL-1β challenge or serial subculturing) and in chondrocytes from OA and non-OA patients. Potential miR-29b targets identified in silico in 3′-UTRs of collagens mRNAs were tested with luciferase reporter assays. The impact of premiR-29b overexpression in ATDC5 cells was studied on collagen mRNA levels and synthesis (Sirius red staining) during chondrogenesis.

Results

MiR-29b level increased significantly in IL-1β-stimulated and weakly in subcultured chondrocytes. A 5.8-fold increase was observed in chondrocytes from OA versus non-OA patients. Reporter assays showed that miR-29b targeted COL2A1 and COL1A2 3′-UTRs although with a variable recovery upon mutation. In ATDC5 cells overexpressing premiR-29b, collagen production was reduced while mRNA levels increased.

Conclusions

By acting probably as a posttranscriptional regulator with a different efficacy on COL2A1 and COL1A2 expression, miR-29b can contribute to the collagens imbalance associated with an abnormal chondrocyte phenotype.

MiR-146b is down-regulated during the chondrogenic differentiation of human bone marrow derived skeletal stem cells and up-regulated in osteoarthritis

Articular cartilage injury can result in chondrocyte loss and diminishment of specialised extracellular matrix, which can progress to an osteoarthritic (OA) phenotype. Stem cells have emerged as a favourable approach for articular cartilage regeneration. Identification of miRNAs which influence stem cell fate offers new approaches for application of miRNAs to regenerate articular cartilage. Skeletal stem cells (SSCs) isolated from human bone marrow were cultured as high density micromass' using TGF-β3 to induce chondrogenesis. qPCR and TaqMan qPCR were used to assess chondrogenic gene and miRNA expression. Target prediction algorithms identified potential targets of miR-146b. Transient transfection with miR-146b mimic and western blotting was used to analyse SOX5. Human OA articular chondrocytes were examined for miR-146b expression. Chondrogenic differentiation of human bone marrow derived SSCs resulted in significant down-regulation of miR-146b. Gain of miR-146b function resulted in down-regulation of SOX5. MiR-146b expression was up-regulated in OA chondrocytes. These findings demonstrate the functional role of miR-146b in the chondrogenic differentiation of human bone marrow derived SSCs. MiR-146b may play a role in the pathophysiology of OA. Application of miR-146b combined with stem cell therapy could enhance regeneration of cartilaginous tissue and serve as a potential therapeutic target in the treatment of OA.

Upregulation of microRNA-125b-5p is involved in the pathogenesis of osteoarthritis by downregulating SYVN1

Osteoarthritis (OA) is a degenerative disease characterized by deterioration of articular cartilage. The aim of this study was to identify and characterize the expression of microRNA-125b-5p (miR-125b-5p) in normal and OA synovial cells, and to determine its role in OA pathogenesis. First, the levels of miR-125b-5p and synoviolin 1 (SYVN1) were detected among normal, mild OA and severe OA groups with the use of quantitative PCR. Computational analysis was used to search for the target of the miR-125b-5p, and luciferase reporter assay system was used to validate SYVN1 as the target gene of miR-125b-5p. Then the SYVN1 expression level of cells transfected with miR-125b-5p mimics or inhibitors was estimated using quantitative PCR and western blotting. Finally, MTT assay was employed to estimate the effect of miR-125b-5p on apoptosis. We enrolled 36 participants consisting of 12 normal control, 12 mild OA and 12 severe OA, furthermore, we performed quantitative PCR to detect the levels of miR-125b-5p and SYVN1 among those groups, and found that miR-125b-5p was expressed at highest level in severe OA compared with normal control and mild OA groups, while SYVN1 was expressed at the lowest level in severe OA. Additionally, we identified that SYVN1 is a target of miR-125b-5p by using computational analysis and luciferase assay. Transfection with miR-125b-5p mimic or inhibitor was employed to investigate the effect of miR-125b-5p on expression of SYVN1 in synovial cells, and synovial cell viability and apoptosis, and the results showed that miR-125b-5p mimics significant decreased the expression of SYVN1, a substantially promoted apoptosis of synovial cells, while miR-125b-5p inhibitors remarkably increased the level of SYVN1, and substantially suppressed apoptosis of synovial cells. The data suggested that miR-125b-5p promoted apoptosis of synovial cells through targeting SYVN1 gene, with important implication for validating miR-125b-5p as a potential target for OA therapy.

Hydrostatic Pressure Regulates MicroRNA Expression Levels in Osteoarthritic Chondrocyte Cultures via the Wnt/β-Catenin Pathway

Mechanical loading and hydrostatic pressure (HP) regulate chondrocytes’ metabolism; however, how mechanical stimulation acts remain unclear. MicroRNAs (miRNAs) play an important role in cartilage homeostasis, mechanotransduction, and in the pathogenesis of osteoarthritis (OA). This study investigated the effects of a cyclic HP (1–5 MPa), in both normal and OA human chondrocytes, on the expression of miR-27a/b, miR-140, miR-146a/b, and miR-365, and of their target genes (MMP-13, ADAMTS-5, IGFBP-5, and HDAC-4). Furthermore, we assessed the possible involvement of Wnt/β-catenin pathway in response to HP. Chondrocytes were exposed to HP for 3h and the evaluations were performed immediately after pressurization, and following 12, 24, and 48 h. Total RNA was extracted and used for real-time PCR. β-catenin was detected by Western blotting analysis and immunofluorescence. In OA chondrocytes, HP induced a significant increase (p < 0.01) of the expression levels of miR-27a/b, miR-140, and miR-146a, and a significant reduction (p < 0.01) of miR-365 at all analyzed time points. MMP-13, ADAMTS-5, and HDAC-4 were significantly downregulated following HP, while no significant modification was found for IGFBP-5. β-catenin levels were significantly increased (p < 0.001) in OA chondrocytes at basal conditions and significantly reduced (p < 0.01) by HP. Pressurization did not cause any significant modification in normal cells. In conclusion, in OA chondrocytes, HP restores the expression levels of some miRNAs, downregulates MMP-13, ADAMTS-5, and HDAC-4, and modulates the Wnt/β-catenin pathway activation.

Controlled Release of Interleukin-1 Receptor Antagonist from Hyaluronic Acid-Chitosan Microspheres Attenuates Interleukin-1β-Induced Inflammation and Apoptosis in Chondrocytes

This paper investigates the protective effect of interleukin-1 receptor antagonist (IL-1Ra) released from hyaluronic acid chitosan (HA-CS) microspheres in a controlled manner on IL-1β-induced inflammation and apoptosis in chondrocytes. The IL-1Ra release kinetics was characterized by an initial burst release, which was reduced to a linear release over eight days. Chondrocytes were stimulated with 10 ng/ml IL-1β and subsequently incubated with HA-CS-IL-1Ra microspheres. The cell viability was decreased by IL-1β, which was attenuated by HA-CS-IL-1Ra microspheres as indicated by an MTT assay. ELISA showed that HA-CS-IL-1Ra microspheres inhibited IL-1β-induced inflammation by attenuating increases in NO₂⁻ and prostaglandin E2 levels as well as increase in glycosaminoglycan release. A terminal deoxyribonucleotide transferase deoxyuridine triphosphate nick-end labeling assay revealed that the IL-1β-induced chondrocyte apoptosis was decreased by HA-CS-IL-1Ra microspheres. Moreover, HA-CS-IL-1Ra microspheres blocked IL-1β-induced chondrocyte apoptosis by increasing B-cell lymphoma 2 (Bcl-2) and decreasing Bcl-2-associated X protein and caspase-3 expressions at mRNA and protein levels, as indicated by reverse-transcription quantitative polymerase chain reaction and western blot analysis, respectively. The results of the present study indicated that HA-CS-IL-1Ra microspheres as a controlled release system of IL-1Ra possess potential anti-inflammatory and antiapoptotic properties in rat chondrocytes due to their ability to regulate inflammatory factors and apoptosis associated genes.

Hsa-miR-15a exerts protective effects against osteoarthritis by targeting aggrecanase-2 (ADAMTS5) in human chondrocytes

The aim of the present study was to examine the expression levels and role of hsa-miR-15a in osteoarthritis (OA), as well as the associated mechanisms. The expression levels of hsa-miR-15a and A disintegrin-like and metalloprotease (reprolysin type) with thrombospondin type 1 motif, 5 (ADAMTS5, also known as aggrecanase-2) were measured by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in both OA and normal chondrocytes. hsa-miR‑21 mimics or antisense oligonucleotides (ASO) were co-transfected into the chondrocytes to examine the effects on the putative binding sites compared with the negative control (NC)-mimics or NC-ASO. The relative ADAMTS5 mRNA and protein levels were measured by RT-qPCR and western blot anlaysis, respectively. Moreover, after inhibiting the expression of hsa‑miR‑15a and ADAMTS5 by ASO and small interfering RNA (siRNA), respectively, the amounts of proteoglycan and collagen in the cellular matrix and medium were determined. Additionally, the expression levels of collagen II were measured by western blot analysis. hsa‑miR‑15a expression was downregulated, but ADAMTS5 expression was upregulated in the human OA chondrocytes compared to the normal chondrocytes. Luciferase reporter assay confirmed that the hsa‑miR‑15a binding site was in the ADAMTS5 gene 3'-untranslated region (3'-UTR), and ADAMTS5 was negatively regulated by hsa‑miR‑15a. The downregulation of hsa‑miR‑15a decreased the aggregation of proteoglycan and the collagen content, but increased the release of proteoglycan and collagen; total collagen production was significantly lower, and collagenase activity was markedly higher. The downregulation of ADAMTS5 increased the aggregation of proteoglycan and the collagen content, but decreased the release of proteoglycan and collagen, along with total collagen production. Moreover, collagenase activity was markedly lower. The findings of our study suggest that hsa‑miR‑15a exerts protective effects against OA by targeting ADAMTS5 in human chondrocytes.

Elevated expression of microRNA-30b in osteoarthritis and its role in ERG regulation of chondrocyte

ERG (ETS-related gene) belongs to the ETS family of transcription factors, and has been recently reported to contribute to homeostatic balance in skeleton cell plasticity. MicroRNA-30 (miR-30) family is also demonstrated to play a role in controlling chondrocyte differentiation. The current study investigated the miR-30b and ERG expression in articular cartilage of osteoarthritis (OA) patients. A total of 20 subjects, with 10 OA patients and 10 healthy participants, were included in this study. Human chondrosarcoma cell line SW1353 was used to explore the relationship of miR-30b and ERG in vitro. In OA patients, a significant increase of miR-30b and a decrease of ERG were observed in articular cartilage compared with Normal ones. MiR-30b mimic down-regulated the ERG mRNA and protein expression levels, while miR-30b inhibitor up-regulated ERG expression. In addition, miR-30b mimic also decreased the mRNA expression of COL2a and aggrecan, while miR-30b inhibitor had the opposite effect. Luciferase reporter assay confirmed that miR-30b targeted ERG. In conclusion, miR-30b was involved in the process of OA, and it probably functioned through its target gene ERG.

Therapeutic Effects of Ribunucleinate (Ribonucleotides) in Immuno-Inflammatory and Arthritic Diseases

Ribonucleic acids from different organs and from yeast have been used for the treatment of chronic and degenerative diseases in the context of naturopathic medicine in the last 60 years. This chapter provides general information about ribonucleinates as therapeutic agents. Past and present pharmacological and clinical investigations are discussed in the field of the central nervous system, sensory organs, cancer and degenerative diseases of joints and vertebra.

MicroRNA-33a regulates cholesterol synthesis and cholesterol efflux-related genes in osteoarthritic chondrocytes

Introduction

Several studies have shown that osteoarthritis (OA) is strongly associated with metabolism-related disorders, highlighting OA as the fifth component of the metabolic syndrome (MetS). On the basis of our previous findings on dysregulation of cholesterol homeostasis in OA, we were prompted to investigate whether microRNA-33a (miR-33a), one of the master regulators of cholesterol and fatty acid metabolism, plays a key role in OA pathogenesis.

Methods

Articular cartilage samples were obtained from 14 patients with primary OA undergoing total knee replacement surgery. Normal cartilage was obtained from nine individuals undergoing fracture repair surgery. Bioinformatics analysis was used to identify miR-33a target genes. miR-33a and sterol regulatory element-binding protein 2 (SREBP-2) expression levels were investigated using real-time PCR, and their expression was also assessed after treatment with transforming growth factor-β1 (TGF-β1) in cultured chondrocytes. Akt phosphorylation after treatment with both TGF-β1 and miR-33a inhibitor or TGF-β1 and miR-33a mimic was assessed by Western blot analysis. Furthermore, we evaluated the effect of miR-33a mimic and miR-33a inhibitor on Smad7, a negative regulator of TGF-β signaling, on cholesterol efflux-related genes, ATP-binding cassette transporter A1 (ABCA1), apolipoprotein A1 (ApoA1) and liver X receptors (LXRα and LXRβ), as well as on matrix metalloproteinase-13 (MMP-13), using real-time PCR.

Results

We found that the expression of miR-33a and its host gene SREBP-2 was significantly elevated in OA chondrocytes compared with normal chondrocytes. Treatment of cultured chondrocytes with TGF-β1 resulted in increased expression of both miR-33a and SREBP-2, as well as in rapid induction of Akt phosphorylation, whereas TGF-β-induced Akt phosphorylation was enhanced by miR-33a and suppressed by inhibition of miR-33a, as a possible consequence of Smad7 regulation by miR-33a. Moreover, treatment of normal chondrocytes with miR-33a resulted in significantly reduced ABCA1 and ApoA1 mRNA expression levels and significantly elevated MMP-13 expression levels, promoting the OA phenotype, whereas miR-33a’s suppressive effect was reversed using its inhibitor.

Conclusions

Our findings suggest, for the first time to our knowledge, that miR-33a regulates cholesterol synthesis through the TGF-β1/Akt/SREBP-2 pathway, as well as cholesterol efflux-related genes ABCA1 and ApoA1, in OA chondrocytes, pointing to its identification as a novel target for ameliorating the OA phenotype.

MicroRNAs: Important Epigenetic Regulators in Osteoarthritis

Multiple mechanisms are implicated in the development of primary osteoarthritis (OA), in which genetic and epigenetic factors appear to interact with environmental factors and age to initiate the disease and stimulate its progression. Changes in expression of microRNAs (miRs) contribute to development of osteoarthritis. Numerous miRs are involved in cartilage development, homeostasis and degradation through targeting genes expressed in this tissue. An important regulator of gene expression in human cartilage is miR-140, which directly targets a gene coding aggrecanase ADAMTS-5, that cleaves aggrecan in cartilage. This miR is considered a biological marker for cartilage and its level significantly decreases in OA cartilage. On the other hand, increased expression of miR-146a in early OA inhibits two other cartilage-degrading enzymes: MMP13 and ADAMTS4, and may provide a useful tool in developing treatments for OA. The COL2A1 gene, encoding collagen type II, which is the most abundant structural protein of the cartilage, is silenced by miR-34a and activated by miR-675. Every year, new targets of cartilage miRs are validated experimentally and this opens new possibilities for new therapies that control joint destruction and stimulate cartilage repair. At the same time development of next-generation sequencing technologies allows to identify new miRs involved in cartilage biology.

microRNA and Pain

Pain is an important protective system that alerts organisms to actual or possible tissue damage. However, a variety of pathologies can lead to chronic pain that is no longer beneficial. Lesions or diseases of the somatosensory nervous system cause intractable neuropathic pain that occasionally lasts even after the original pathology subsides. Chronic inflammatory diseases like arthritis are also associated with severe pain. Because conventional analgesics such as non-steroidal anti-inflammatory drugs and opioids have limited efficacy and/or severe adverse events associated with long-term use, chronic pain remains a major problem in clinical practice. Recently, causal roles of microRNAs in chronic pain and their therapeutic potential have been emerging. microRNA expressions are altered not only at the primary origin of pain, but also along the somatosensory pathways. Notably, microRNA expressions are differentially affected depending on the causes of chronic pain. This chapter summarizes current insights into the roles of microRNAs in pain based on the underlying pathologies.

CTGF increases vascular endothelial growth factor-dependent angiogenesis in human synovial fibroblasts by increasing miR-210 expression

Connective tissue growth factor (CTGF, a.k.a. CCN2) is inflammatory mediator and abundantly expressed in osteoarthritis (OA). Angiogenesis is essential for OA progression. Here, we investigated the role of CTGF in vascular endothelial growth factor (VEGF) production and angiogenesis in OA synovial fibroblasts (OASFs). We showed that expression of CTGF and VEGF in synovial fluid were higher in OA patients than in controls. Directly applying CTGF to OASFs increased VEGF production then promoted endothelial progenitor cells tube formation and migration. CTGF induced VEGF by raising miR-210 expression via PI3K, AKT, ERK, and nuclear factor-κB (NF-κB)/ELK1 pathways. CTGF-mediating miR-210 upregulation repressed glycerol-3-phosphate dehydrogenase 1-like (GPD1L) expression and PHD activity and subsequently promoted hypoxia-inducible factor (HIF)-1α-dependent VEGF expression. Knockdown of CTGF decreased VEGF expression and abolished OASF-conditional medium-mediated angiogenesis in vitro as well as angiogenesis in chick chorioallantoic membrane and Matrigel-plug nude mice model in vivo. Taken together, our results suggest CTGF activates PI3K, AKT, ERK, and NF-κB/ELK1 pathway, leading to the upregulation of miR-210, contributing to inhibit GPD1L expression and prolyl hydroxylases 2 activity, promoting HIF-1α-dependent VEGF expression and angiogenesis in human synovial fibroblasts.

MicroRNAs as modulators and biomarkers of inflammatory and neuropathic pain conditions

The post-transcriptional regulator molecules, microRNAs, have emerged as important biomarkers and modulators of numerous pathophysiological processes including oncogenesis and cardiovascular diseases. Recently, a significant number of dysregulations in microRNAs have been reported in patients suffering from painful disorders such as complex regional pain syndrome, cystitis-induced chronic pain and irritable bowel disorder, in both affected tissues and the circulation. Moreover, microRNAs are known to be involved in pain processing based on several recent findings in animal models of inflammatory and neuropathic pain. The basis of this review was to cover and summarize available articles in English encompassing "microRNA and pain". In animal pain models widespread microRNA modulation is present and manifests on multiple levels i.e.: the dorsal root ganglia, the spinal dorsal horn and the brain. Numerous functional in vivo studies have found that dysregulated microRNAs are involved in the post-transcriptional modulation of genes implicated in pain generation and maintenance. Lastly, a few animal studies have delivered promising results as to the possibility of applying microRNAs as therapeutics to alleviate established pain and several clinical studies have highlighted the potential in applying microRNAs as biomarkers in painful conditions such as complex regional pain syndrome and fibromyalgia. This review briefly introduces the basics of microRNAs, their biogenesis and function, and mainly focuses on the recent advances made in understanding the role of microRNAs in relation to pain processing and painful conditions. It also provides an overview of widely diverse methodological approaches and results with a potential for future implications of microRNAs in the diagnosis and treatment of pain.