Metabolic syndrome increases osteoarthritis risk: findings from the UK Biobank prospective cohort study.

OBJECTIVE: The association between Metabolic Syndrome (MetS), its components, and the risk of osteoarthritis (OA) has been a topic of conflicting evidence in different studies. The aim of this present study is to investigate the association between MetS, its components, and the risk of OA using data from the UK Biobank. METHODS: A prospective cohort study was conducted in the UK Biobank to assess the risk of osteoarthritis (OA) related to MetS. MetS was defined according to the criteria set by the International Diabetes Federation (IDF). Additionally, lifestyle factors, medications, and the inflammatory marker C-reactive protein (CRP) were included in the model. Cox proportional hazards regression was used to calculate hazard ratios (HR) and 95% confidence intervals (CI). The cumulative risk of OA was analyzed using Kaplan-Meier curves and log-rank tests. To explore potential nonlinear associations between MetS components and OA risk, a restricted cubic splines (RCS) model was employed. In addition, the polygenic risk score (PRS) of OA was calculated to characterize individual genetic risk. RESULTS: A total of 45,581 cases of OA were identified among 370,311 participants, with a median follow-up time of 12.48 years. The study found that individuals with MetS had a 15% higher risk of developing OA (HR = 1.15, 95%CI:1.12-1.19). Additionally, central obesity was associated with a 58% increased risk of OA (HR = 1.58, 95%CI:1.5-1.66), while hyperglycemia was linked to a 13% higher risk (HR = 1.13, 95%CI:1.1-1.15). Dyslipidemia, specifically in triglycerides (HR = 1.07, 95%CI:1.05-1.09) and high-density lipoprotein (HR = 1.05, 95%CI:1.02-1.07), was also found to be slightly associated with OA risk. When stratified by PRS, those in the high PRS group had a significantly higher risk of OA compared to those with a low PRS, whereas no interaction was found between MetS and PRS on OA risks. Furthermore, the presence of MetS significantly increased the risk of OA by up to 35% in individuals with elevated CRP levels (HR = 1.35, 95% CI:1.3-1.4). CONCLUSION: MetS and its components have been found to be associated with an increased risk of OA, particularly in individuals with elevated levels of CRP. These findings highlight the significance of managing MetS as a preventive and intervention measure for OA.

Triamcinolone acetonide-loaded nanoparticles encapsulated by CD90+ MCSs-derived microvesicles drive anti-inflammatory properties and promote cartilage regeneration after osteoarthritis.

BACKGROUND: Osteoarthritis (OA) is a highly prevalent human degenerative joint disorder that has long plagued patients. Glucocorticoid injection into the intra-articular (IA) cavity provides potential short-term analgesia and anti-inflammatory effects, but long-term IA injections cause loss of cartilage. Synovial mesenchymal stem cells (MSCs) reportedly promote cartilage proliferation and increase cartilage content. METHODS: CD90+ MCS-derived micro-vesicle (CD90@MV)-coated nanoparticle (CD90@NP) was developed. CD90+ MCSs were extracted from human synovial tissue. Cytochalasin B (CB) relaxed the interaction between the cytoskeleton and the cell membranes of the CD90+ MCSs, stimulating CD90@MV secretion. Poly (lactic-co-glycolic acid) (PLGA) nanoparticle was coated with CD90@MV, and a model glucocorticoid, triamcinolone acetonide (TA), was encapsulated in the CD90@NP (T-CD90@NP). The chondroprotective effect of T-CD90@NP was validated in rabbit and rat OA models. RESULTS: The CD90@MV membrane proteins were similar to that of CD90+ MCSs, indicating that CD90@MV bio-activity was similar to the cartilage proliferation-inducing CD90+ MCSs. CD90@NP binding to injured primary cartilage cells was significantly stronger than to erythrocyte membrane-coated nanoparticles (RNP). In the rabbit OA model, the long-term IA treatment with T-CD90@NP showed significantly enhanced repair of damaged cartilage compared to TA and CD90+ MCS treatments. In the rat OA model, the short-term IA treatment with T-CD90@NP showed effective anti-inflammatory ability similar to that of TA treatment. Moreover, the long-term IA treatment with T-CD90@NP induced cartilage to restart the cell cycle and reduced cartilage apoptosis. T-CD90@NP promoted the regeneration of chondrocytes, reduced apoptosis via the FOXO pathway, and influenced type 2 macrophage polarization to regulate inflammation through IL-10. CONCLUSION: This study confirmed that T-CD90@NP promoted chondrocyte proliferation and anti-inflammation, improving the effects of a clinical glucocorticoid treatment plan.

Characterization of exosomal long non-coding RNAs in chondrogenic differentiation of human adipose-derived stem cells.

The exosomes derived from chondrogenic stem cells and long non-coding RNAs (lncRNAs) play a key role in cartilage regeneration. Here, we investigated the expression profile of exosomal lncRNAs in chondrogenesis of human adipose derived stem cells (hADSCs). hADSCs were induced to differentiate into chondrocytes in vitro. Exosomes from undifferentiated hADSCs and chondrogenic hADSCs were isolated. LncRNA and mRNA expression profiles in the isolated exosomes were analyzed by RNA sequencing. The resultant data were subjected to gene ontology (GO) terms and KEGG pathway analysis to identify differentially expressed lncRNAs. We identified 23 upregulated and 163 downregulated lncRNAs in exosomes derived from chondrogenic hADSCs compared to that in exosomes from undifferentiated hADSCs. In addition, analysis of mRNA expression data revealed 968 upregulated genes and 572 downregulated genes in exosomes of chondrogenic hADSCs. Lncrna and mRNA expression levels were further validated by qRT-PCR. Differentially expressed lncRNAs and mRNAs were utilized to construct a coding-non-coding gene co-expression network (CNC network). GO terms and KEGG pathway enrichment analysis revealed several significant processes differentially regulated between undifferentiated hADSCs and chondrogenic hADSCs. Taken together, this study revealed the differential expression of exosomal lncRNAs of chondrogenic hADSCs and provided a foundation for future study on the cartilage recovery mechanism of exosomes derived from chondrogenic stem cells.

Limited value of serum neutrophil-to-lymphocyte ratio in the diagnosis of chronic periprosthetic joint infection.

BACKGROUND: Diagnosing chronic periprosthetic joint infection (PJI) is challenging. No single biomarker can accurately recognize PJI preoperatively in a timely manner. Therefore, the aim of the present study was to investigate the usefulness of the serum neutrophil-to-lymphocyte ratio (NLR) in aiding the diagnosis of chronic PJI. MATERIALS AND METHODS: We retrospectively evaluated the medical records of 158 patients who had undergone revision arthroplasty (104 with aseptic mechanic failure and 54 with chronic PJI) from July 2011 to July 2020. Univariate analysis followed by multivariate logistic regression was applied to compare NLR, C-reactive protein (CRP), and erythrocyte sedimentation ratio (ESR) between the two groups. The receiver operating characteristic (ROC) curve was used to assess the diagnostic performance of NLR alone and in combination with CRP and ESR. RESULTS: NLR, CRP, and ESR were significantly higher in patients with chronic PJI than in the aseptic revision group (p < 0.05). ROC curve analysis revealed that NLR had a sensitivity of 57.41% and a specificity of 77.88% with an optimal threshold of 2.56. The optimal threshold for CRP and ESR was 7.00 mg/L (sensitivity 62.50% and specificity 83.12%) and 43 mm/h (sensitivity 59.38% and specificity 80.52%), respectively. The combined diagnostic value of NLR with CRP and ESR was shown to have no additional diagnostic value in predicting chronic PJI. CONCLUSION: Compared with traditional inflammatory biomarkers (ESR and CRP), the value of serum NLR alone or combined with CRP and ESR for diagnosing chronic PJI is limited. LEVEL OF EVIDENCE: Level 3.

Novel mitochondrion-targeting copper(II) complex induces HK2 malfunction and inhibits glycolysis via Drp1-mediating mitophagy in HCC.

[Cu(ttpy-tpp)Br2 ]Br (abbreviated as CTB) is a novel mitochondrion-targeting copper(II) complex synthesized by our research group, which contains tri-phenyl-phosphonium (TPP) groups as its lipophilic property. In this study, we explored how CTB affects mitochondrial functions and exerts its anti-tumour activity. Multiple functional and molecular analyses including Seahorse XF Bioanalyzer Platform, Western blot, immunofluorescence analysis, co-immunoprecipitation and transmission electron microscopy were used to elucidate the underlying mechanisms. Human hepatoma cells were subcutaneously injected into right armpit of male nude mice for evaluating the effects of CTB in vivo. We discovered that CTB inhibited aerobic glycolysis and cell acidification by impairing the activity of HK2 in hepatoma cells, accompanied by dissociation of HK2 from mitochondria. The modification of HK2 not only led to the complete dissipation of mitochondrial membrane potential (MMP) but also promoted the opening of mitochondrial permeability transition pore (mPTP), contributing to the activation of mitophagy. In addition, CTB co-ordinately promoted dynamin-related protein 1 (Drp1) recruitment in mitochondria to induce mitochondrial fission. Our findings established a previously unrecognized role for copper complex in aerobic glycolysis of tumour cells, revealing the interaction between mitochondrial HK2-mediated mitophagy and Drp1-regulated mitochondrial fission.

Single-cell RNA-seq analysis identifies meniscus progenitors and reveals the progression of meniscus degeneration.

OBJECTIVES: The heterogeneity of meniscus cells and the mechanism of meniscus degeneration is not well understood. Here, single-cell RNA sequencing (scRNA-seq) was used to identify various meniscus cell subsets and investigate the mechanism of meniscus degeneration. METHODS: scRNA-seq was used to identify cell subsets and their gene signatures in healthy human and degenerated meniscus cells to determine their differentiation relationships and characterise the diversity within specific cell types. Colony-forming, multi-differentiation assays and a mice meniscus injury model were used to identify meniscus progenitor cells. We investigated the role of degenerated meniscus progenitor (DegP) cell clusters during meniscus degeneration using computational analysis and experimental verification. RESULTS: We identified seven clusters in healthy human meniscus, including five empirically defined populations and two novel populations. Pseudotime analysis showed endothelial cells and fibrochondrocyte progenitors (FCP) existed at the pseudospace trajectory start. Melanoma cell adhesion molecule ((MCAM)/CD146) was highly expressed in two clusters. CD146+ meniscus cells differentiated into osteoblasts and adipocytes and formed colonies. We identified changes in the proportions of degenerated meniscus cell clusters and found a cluster specific to degenerative meniscus with progenitor cell characteristics. The reconstruction of four progenitor cell clusters indicated that FCP differentiation into DegP was an aberrant process. Interleukin 1ß stimulation in healthy human meniscus cells increased CD318+ cells, while TGFß1 attenuated the increase in CD318+ cells in degenerated meniscus cells. CONCLUSIONS: The identification of meniscus progenitor cells provided new insights into cell-based meniscus tissue engineering, demonstrating a novel mechanism of meniscus degeneration, which contributes to the development of a novel therapeutic strategy.

Expression of exosomal microRNAs during chondrogenic differentiation of human bone mesenchymal stem cells.

The aim of the current study was to compare the expression of microRNAs (miRNAs) in exosomes derived from human bone mesenchymal stem cells (hBMSCs) with and without chondrogenic induction. Exosomes derived from hBMSCs were isolated and identified. Microarray analysis was performed to compare miRNA expression between exosomes derived from hBMSCs with and without chondrogenic induction, and quantitative real-time polymerase chain reaction (qRT-PCR) was used to verify the differentially expressed miRNAs. hBMSCs were transfected with miRNA mimic to extract miRNA-overexpressed exosomes. The results showed that most exosomes exhibited a cup-shaped or round-shaped morphology with a diameter of approximately 50-200 nm and expressed CD9 and CD63. We detected 141 miRNAs that were differentially expressed with and without chondrogenic induction by over a twofold change, including 35 upregulated miRNAs, such as miR-1246, miR-1290, miR-193a-5p, miR-320c, and miR-92a, and 106 downregulated miRNAs, such as miR-377-3p and miR-6891-5p. qRT-PCR analysis validated these results. Exosomes derived from hBMSCs overexpressing miR-320c were more efficient than normal exosomes derived from control hBMSCs at promoting osteoarthritis chondrocyte proliferation, down-regulated matrix metallopeptidase 13 and up-regulated (sex determining region Y)-box 9 expression during hBMSC chondrogenic differentiation. In conclusion, we identified a group of upregulated miRNAs in exosomes derived from hBMSCs with chondrogenic induction that may play an important role in mesenchymal stem cell-derived exosomes in cartilage regeneration and, ultimately, the treatment of arthritis. We demonstrated the potential of these modified exosomes in the development of novel therapeutic strategies.

Substantive molecular and histological changes within the meniscus with tears.

BACKGROUND: The meniscus plays a vital role in the normal biomechanics of the knee. However, it is not well studied at the molecular level. The purpose of this study was to determine whether molecular and pathological changes in the meniscal tissue vary depending on the presence or absence of meniscal and/or anterior cruciate ligament tear (ACL). METHODS: Six normal menisci (group A), seven simple torn menisci (group B) and seven torn menisci with concomitant anterior cruciate ligament tears (group C) were collected. We observed the pathological changes in the menisci and used real-time polymerase chain reaction along with immunohistochemistry and in situ hybridisation to examine the levels of ACAN, ADAMTS5, COL10A1, CEBPß, MMP13 and miR-381-3p, miR-455-3p, miR-193b-3p, miR-92a-3p, respectively. Patients were scored preoperatively and postoperatively using the Lysholm Knee Scoring Scale and International Knee Documentation Committee Subjective Knee Evaluation Form. RESULTS: Compared with group A, the expression levels of ADAMTS5, COL10A1, CEBPß, and MMP13 and all the miRNAs were increased while ACAN was down-regulated in groups B and C. Additionally, the gene expression and miRNA levels were higher in group C than that in group B, except for ACAN, which was lower. Several fibrochondrocytes strongly expressed ADAMTS5, CEBPß, and MMP13 in groups B and C and had high levels of miR-381-3p and miR-455-3p than that in group A. Postoperative Lysholm and IKDC scores were higher in group B than in group C. CONCLUSIONS: Our findings suggest that the meniscus tended to degenerate after it was injured, especially when combined with a torn ACL. The miRNAs investigated in this study might also contribute to meniscus degeneration. Patients with a combined injury patterns might have relatively worse joint function.

Exosomal miR-95-5p regulates chondrogenesis and cartilage degradation via histone deacetylase 2/8.

MicroRNAs play critical roles in the pathogenesis of osteoarthritis, the most common chronic degenerative joint disease. Exosomes derived from miR-95-5p-overexpressing primary chondrocytes (AC-miR-95-5p) may be effective in treating osteoarthritis. Increased expression of HDAC2/8 occurs in the tissues and chondrocyte-secreted exosomes of patients with osteoarthritis and mediates cartilage-specific gene expression in chondrocytes. We have been suggested that exosomes derived from AC-miR-95-5p (AC-miR-95-5p-Exos) would enhance chondrogenesis and prevent the development of osteoarthritis by directly targeting HDAC2/8. Our in vitro experiments showed that miR-95-5p expression was significantly lower in osteoarthritic chondrocyte-secreted exosomes than in normal cartilage. Treatment with AC-miR-95-5p-Exos promoted cartilage development and cartilage matrix expression in mesenchymal stem cells induced to undergo chondrogenesis and chondrocytes, respectively. In contrast, co-culture with exosomes derived from chondrocytes transfected with an antisense inhibitor of miR-95-5p (AC-anti-miR-95-5p-Exos) prevented chondrogenic differentiation and reduced cartilage matrix synthesis by enhancing the expression of HDAC2/8. MiR-95-5p suppressed the activity of reporter constructs containing the 3'-untranslated region of HDAC2/8, inhibited HDAC2/8 expression and promoted cartilage matrix expression. Our results suggest that AC-miR-95-5p-Exos regulate cartilage development and homoeostasis by directly targeting HDAC2/8. Thus, AC-miR-95-5p-Exos may act as an HDAC2/8 inhibitor and exhibit potential as a disease-modifying osteoarthritis drug.

An injectable, biodegradable calcium phosphate cement containing poly lactic-co-glycolic acid as a bone substitute in ex vivo human vertebral compression fracture and rabbit bone defect models.

Purpose/Aim of the study: To evaluate the biomechanical characteristics and biocompatibility of an injectable, biodegradable calcium phosphate cement (CPC) containing poly lactic-co-glycolic acid (PLGA). MATERIALS AND METHODS: A vertebral compression fracture model was established using 20 human cadaveric vertebrae (T11-L3) divided into CPC/PLGA composite versus PMMA groups for biomechanical testing. In addition, 35 New Zealand rabbits were used to evaluate biodegradability and osteoconductive properties of CPC/PLGA using a bone defect model. In vitro cytotoxicity was evaluated by culturing with L929 cells. RESULTS: The CPC/PLGA composite effectively restored vertebral biomechanical properties. Compared with controls, the maximum load and compression strength of the CPC/PLGA group were lower, and stiffness was lower after kyphoplasty (all p <.05). Degradation was much slower in the control CPC compared with CPC/PLGA group. The bone tissue percentage in the CPC/PLGA group (44.9 ± 23.7%) was significantly higher compared with control CPC group (25.7 ± 10.9%) (p <.05). The viability of cells cultured on CPC/PLGA was greater than 70% compared with the blanks. CONCLUSIONS: Our biodegradable CPC/PLGA composite showed good biomechanical properties, cytocompatibility, and osteoconductivity and may represent an ideal bone substitute for future applications.

MicroRNA-455-3p modulates cartilage development and degeneration through modification of histone H3 acetylation.

Histone acetylation regulated by class I histone deacetylases (HDACs) plays a pivotal role in matrix-specific gene transcription and cartilage development. While we previously demonstrated that microRNA (miR)-455-3p is upregulated during chondrogenesis and can enhance early chondrogenesis, the mechanism underlying this process remains largely unclear. In this study, we characterized the effect of miR-455-3p on histone H3 acetylation and its role during cartilage development and degeneration. We observed that miR-455-3p was highly expressed in proliferating and pre-hypertrophic chondrocytes, while HDAC2 and HDAC8 were primarily expressed in hypertrophic chondrocytes. Meanwhile, miR-455-3p suppressed the activity of reporter constructs containing the 3'-untranslated regions of HDAC2/8, inhibited HDAC2/8 expression and promoted histone H3 acetylation at the collagen 2 (COL2A1) promoter in human SW1353 chondrocyte-like cells. Treatment with the HDAC inhibitor trichostatin A (TSA) resulted in increased expression of cartilage-specific genes and promoted glycosaminoglycan deposition. Moreover, TSA inhibited matrix metalloproteinase 13 (Mmp13) expression and promoted nuclear translocation of SOX9 in interleukin-1-treated primary mouse chondrocytes. Lastly, knockdown of HDAC2/3/8 increased SRY (sex-determining region Y)-box 9 (SOX9) and decreased Runt-related transcription factor 2 (RUNX2) expression. Taken together, these findings suggest that miR-455-3p plays a critical role during chondrogenesis by directly targeting HDAC2/8 and promoting histone H3 acetylation, which raises possibilities of using miR-455-3p to influence chondrogenesis and cartilage degeneration.

MicroRNA-92a-3p Regulates Aggrecanase-1 and Aggrecanase-2 Expression in Chondrogenesis and IL-1ß-Induced Catabolism in Human Articular Chondrocytes.

BACKGROUND/AIMS: Aggrecanase-1 (ADAMTS-4) and aggrecanase-2 (ADAMTS-5) are secreted enzymes belonging to the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family that play significant roles in the progression of osteoarthritis (OA). Here, we aimed to determine whether the expression of ADAMTS-4/5 in chondrogenesis and inflammation is regulated by microRNA-92a-3p (miR-92a-3p). METHODS: MiR-92a-3p and ADAMTS-4/5 expressions were determined by quantitative polymerase chain reaction (qPCR). To investigate the repressive effect of miR-92a-3p on ADAMTS-4/5 expression, chondrogenic human mesenchymal stem cells (hMSCs) and human chondrocytes were transfected with mature miR-92a-3p or an antisense inhibitor (anti-miR-92a-3p), respectively. ADAMTS-4/5 protein production was quantified by enzyme-linked immunosorbent assay (ELISA), and miR-92a-3p involvement in IL-1ß-mediated catabolic effects was examined by immunoblotting. The roles of activated MAP kinases (MAPK) and nuclear factor (NF)-κB were evaluated by using specific inhibitors. Interaction between miR-92a-3p and its putative binding site in the 3'-untranslated region (3'-UTR) of ADAMTS-4/5 mRNA was confirmed by luciferase reporter assay. RESULTS: miR-92a-3p expression was elevated in chondrogenic hMSCs, with significantly lower expression in OA cartilage than in normal cartilage. Stimulation with IL-1ß significantly reduced miR-92a-3p expression in primary human chondrocytes (PHCs). Transfection of chondrocytes with miR-92a-3p downregulated IL-1ß-induced ADAMTS-4/5 expression, and the activity of a reporter construct containing the 3'-UTR of human ADAMTS-4/5 mRNA. MiR-92a-3p expression was suppressed upon IL-1ß-induced activation of MAPK and NF-κB in chondrocytes. CONCLUSION: MiR-92a-3p is an important regulator of ADAMTS-4/5 in human chondrocytes and may contribute to the development of OA.

Identification and Characterization of Long Non-Coding RNAs in Osteogenic Differentiation of Human Adipose-Derived Stem Cells.

BACKGROUND/AIMS: Long noncoding RNAs (lncRNAs) play important roles in stem cell differentiation. However, their role in osteogenesis of human adipose-derived stem cells (ASCs), a promising cell source for bone regeneration, remains unknown. Here, we investigated the expression profile and potential roles of lncRNAs in osteogenic differentiation of human ASCs. METHODS: Human ASCs were induced to differentiate into osteoblasts in vitro, and the expression profiles of lncRNAs and mRNAs in undifferentiated and osteogenic differentiated ASCs were obtained by microarray. Bioinformatics analyses including subgroup analysis, gene ontology analysis, pathway analysis and co-expression network analysis were performed. The function of lncRNA H19 was determined by in vitro knockdown and overexpression. Quantitative reverse transcription polymerase chain reaction was utilized to examine the expression of selected genes. RESULTS: We identified 1,460 upregulated and 1,112 downregulated lncRNAs in osteogenic differentiated human ASCs as compared with those of undifferentiated cells (Fold change ≥ 2.0, P < 0.05). Among these, 94 antisense lncRNAs, 85 enhancer-like lncRNAs and 160 lincRNAs were further recognized. We used 12 lncRNAs and 157 mRNAs to comprise a coding-non-coding gene expression network. Additionally, silencing of H19 caused a significantly increase in expression of osteogenesis-related genes, including ALPL and RUNX2, while a decrease was observed after H19 overexpression. CONCLUSION: This study revealed for the first time the global expression profile of lncRNAs involved in osteogenic differentiation of human ASCs and provided a foundation for future investigations of lncRNA regulation of human ASC osteogenesis.

Advanced glycation end products biphasically modulate bone resorption in osteoclast-like cells.

Advanced glycation end products (AGEs) disturb bone remodeling during aging, and this process is accelerated in diabetes. However, their role in modulation of osteoclast-induced bone resorption is controversial, with some studies indicating that AGEs enhance bone resorption and others showing the opposite effect. We determined whether AGEs present at different stages of osteoclast differentiation affect bone resorption differently. Based on increased levels of tartrate-resistant acid phosphatase (TRAP) and cathepsin K (CTSK), we identified day 4 of induction as the dividing time of cell fusion stage and mature stage in RAW264.7 cell-derived osteoclast-like cells (OCLs). AGE-modified BSA (50-400 µg/ml) or control BSA (100 µg/ml) was then added at the beginning of each stage. Results showed that the presence of AGEs at the cell fusion stage reduced pit numbers, resorption area, and CTSK expression. Moreover, expression of receptor activator of nuclear factor-κB (RANK) as well as the number of TRAP-positive cells, nuclei per OCL, actin rings, and podosomes also decreased. However, the presence of AGEs at the mature stage enlarged the resorption area markedly and increased pit numbers slightly. Intriguingly, only the number of nuclei per OCL and podosomes increased. These data indicate that AGEs biphasically modulate bone resorption activity of OCLs in a differentiation stage-dependent manner. AGEs at the cell fusion stage reduce bone resorption dramatically, mainly via suppression of RANK expression in osteoclast precursors, whereas AGEs at the mature stage enhance bone resorption slightly, most likely by increasing the number of podosomes in mature OCLs.

MicroRNA-381 Regulates Chondrocyte Hypertrophy by Inhibiting Histone Deacetylase 4 Expression.

Chondrocyte hypertrophy, regulated by Runt-related transcription factor 2 (RUNX2) and matrix metalloproteinase 13 (MMP13), is a crucial step in cartilage degeneration and osteoarthritis (OA) pathogenesis. We previously demonstrated that microRNA-381 (miR-381) promotes MMP13 expression during chondrogenesis and contributes to cartilage degeneration; however, the mechanism underlying this process remained unclear. In this study, we observed divergent expression of miR-381 and histone deacetylase 4 (HDAC4), an enzyme that directly inhibits RUNX2 and MMP13 expression, during late-stage chondrogenesis of ATDC5 cells, as well as in prehypertrophic and hypertrophic chondrocytes during long bone development in E16.5 mouse embryos. We therefore investigated whether this miRNA regulates HDAC4 expression during chondrogenesis. Notably, overexpression of miR-381 inhibited HDAC4 expression but promoted RUNX2 expression. Moreover, transfection of SW1353 cells with an miR-381 mimic suppressed the activity of a reporter construct containing the 3'-untranslated region (3'-UTR) of HDAC4. Conversely, treatment with a miR-381 inhibitor yielded increased HDAC4 expression and decreased RUNX2 expression. Lastly, knockdown of HDAC4 expression resulted in increased RUNX2 and MMP13 expression in SW1353 cells. Collectively, our results indicate that miR-381 epigenetically regulates MMP13 and RUNX2 expression via targeting of HDAC4, thereby suggesting the possibilities of inhibiting miR-381 to control chondrocyte hypertrophy and cartilage degeneration.

The Role of MicroRNA-381 in Chondrogenesis and Interleukin-1-ß Induced Chondrocyte Responses.

AIM: The molecular pathways regulating cartilage degradation are unclear. miR-381 was identified as a putative regulator of chondrogenesis related genes. Here, we examined its role in chondrogenesis and osteoarthritic cartilage degeneration. METHODS: miR-381 expression was assessed in vitro in response to IL-1ß stimulation in primary human (PHC) and mouse (PMC) chondrocytes, and ATDC5 derived chondrocytes; and in vivo in mouse embryos and human osteoarthritic cartilage. The effects of miR-381 on chondrogenesis and NF-kB signaling were assessed using a synthetic RNA mimic or inhibitor and luciferase assay, respectively. Upstream regulators of miR381 were probed using siRNA or overexpression plasmids for Sox9 and Runx2. RESULTS: miR-381 expression was elevated in chondrogenic and hypertrophic ATDC5 cells. miR-381 was induced in vitro by IL-1ß in ATDC5 cells, PMCs, and PHCs, and was expressed in areas of cartilage degradation or absorption in vivo. Overexpression of Runx2 or Sox9 increased miR-381 expression in ATDC5 cells. miR-381 suppressed expression of collagen, type II, alpha 1, and enhanced expression of metalloproteinase-13 (MMP-13), but did not regulate NFKBIA and NKRF activity. CONCLUSION: miR-381 was highly expressed during chondrogenesis and in arthritic cartilage. It may contribute to absorption of the cartilage matrix by repressing type II collagen and inducing MMP-13.

Wear particles promote reactive oxygen species-mediated inflammation via the nicotinamide adenine dinucleotide phosphate oxidase pathway in macrophages surrounding loosened implants.

BACKGROUND/AIMS: Prosthesis loosening is closely associated with chronic inflammatory cytokine secretion by macrophages, which are activated by wear particles or inflammatory stimulants such as lipopolysaccharide (LPS). Reactive oxygen species (ROS) are critical regulators of inflammation, but their enzymatic sources in response to wear particles and their effects on peri-implant LPS-tolerance remain unclear. METHODS: Three ROS-related enzymes-nicotinamide adenine dinucleotide phosphate oxidase (NOX)-1 and -2 and catalase-were investigated in interface membrane tissues and in titanium (Ti) particle-stimulated macrophages in vitro. The generation of ROS and downstream inflammatory effects were measured with or without pre-incubation with apocynin, an NOX inhibitor. RESULTS: Pre-exposure to Ti particles attenuated NF-κB activation in LPS-stimulated macrophages, indicating that wear particles suppress immune response, which may lead to chronic inflammation. NOX-1 and -2 were highly expressed in aseptically loosened interface membranes and in macrophages stimulated with Ti particles; the particles induced a moderate amount of ROS generation, NF-κB activation, and TNF-α secretion in macrophages, and these effects were suppressed by apocynin. CONCLUSION: Wear particles induce ROS generation through the NOX signaling pathway, resulting in persistent inflammation and delayed loosening. Thus, the suppression of NOX activity may be a useful strategy for preventing prosthesis loosening.

Expression patterns of transcription factor PPARγ and C/EBP family members during in vitro adipogenesis of human bone marrow mesenchymal stem cells.

In the past decades increasing lines of evidence have demonstrated that adipose tissue, as an endocrine organ plays a central role in metabolic homeostasis and its related maladies. CCAAT/enhancer-binding protein (C/EBP) family members and the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) were known to be the vital transcription factors in the regulation of adipogenesis. However, the exact mechanism for increased marrow fat in patients with bone metabolic diseases, such as osteoporosis, is still poorly understood. Herein, we studied the expression pattern of PPARγ and C/EBPs in human bone marrow mesenchymal stem cell (hBMSC) adipogenesis and evaluated the effects of individual components of an adipogenic cocktail on the differentiation and transcription factor expression. We furthermore examined whether the ERK signaling pathway was involved in mediating these effects. These findings showed that C/EBPß and C/EBPδ were detected in undifferentiated hBMSC and maintained during the whole process of adipogenesis, and could initiate the expression of PPARγ1 under the treatment of dexamethasone and IBMX. Subsequently, the activation of PPARγ1 by indomethacin, its exogenous ligand, activated C/EBPα, which, together with IBMX, up-regulated PPARγ2 expression and therefore the fullest adipogenesis. Insulin and its downstream signal pathway extracellular signal-regulated kinases (ERK), however, were found not necessary for hBMSC adipogenesis. Our results revealed some unique characteristics of human adipocyte formation, which may help to understand the molecular mechanisms of bone marrow adipogenesis and give insights into the treatment of osteoporosis.

Efficacy and Safety of Tranexamic Acid in Bilateral Total Knee Replacement: A Meta-Analysis and Systematic Review.

BACKGROUND Tranexamic acid (TXA) has been well documented to reduce blood loss and transfusion requirements in patients undergoing unilateral total knee arthroplasty (TKA). However, the efficacy and safety of TXA in simultaneous bilateral TKA have not been clearly defined. The aim of our study was to systematically review the existing evidence regarding the role of TXA in patients undergoing simultaneous bilateral TKA. MATERIAL AND METHODS A systematic search of all studies published through June 2014 was performed using Medline, EMBASE, OVID, and other databases. All studies that compared the efficacy and safety of TXA administration in simultaneous bilateral TKA patients were identified. The data from the included trials were extracted and analyzed regarding blood loss and transfusion rates. The evidence quality levels of the selected articles were evaluated using a grading system. RESULTS Six studies were included, in which a total of 245 patients received TXA and 271 patients were controls. Overall, the results demonstrated that the use of TXA significantly reduced total blood loss by a mean of 371.1 ml (95% confidence interval (CI)=-412.12 to -330.09; p<0.001) and reduced the number of patients requiring blood transfusion (risk ratio (RR)=0.16; 95% CI=0.10 to 0.28; p<0.001). No significant differences in adverse effects such as deep vein thrombosis (DVT) or pulmonary embolism (PE) were noted in any group. CONCLUSIONS The intravenous use of TXA in patients undergoing simultaneous bilateral TKA is effective and safe and results in significantly reduced estimated blood loss and transfusion rates. No significant difference was observed in the incidence of side effects. Due to the limitations in the evidence quality of current meta-analyses, well-conducted, larger, high-quality randomized controlled trials (RCTs) are required.

Roles of Sagittal Anatomical Parameters of the Pelvis in Primary Total Hip Replacement for Patients with Ankylosing Spondylitis.

We examined the correlation between acetabular prostheses and sagittal anatomical parameters of the pelvis for the preoperative evaluation of total hip arthroplasty in 29 patients with ankylosing spondylitis between April 2004 and November 2011. No implant dislocation or subsidence was observed at 4.18 years. The relationship between sagittal parameters conformed to the equation Pelvic incidence (PI)=Pelvic tilt (PT)+Sacral slope (SS). Better outcomes were achieved in the SS>PT group, postoperative function was positively correlated with SS/PI. Functional abduction and anteversion were positively correlated with PT but negatively correlated with SS. Due to the compensatory changes in the pelvis and spine of patients with AS, the preoperative assessment of sagittal parameters plays pivotal roles in placing acetabular prostheses in optimal positions and preventing postoperative impingement and dislocation.