Project description:Age as the primary rise factor could be play an important role in incidence and development of osteoarthritis. Several studies have confirmed some tissue specific microRNA were associated with development of osteoarthritis. But if age related microRNA or miRNA cluster would be involved in pivotal post-transcriptional gene regulation in osteoarthritis is unclear. In view of this, we have an idea that several age-related miRNAs would be screened from the rat knee cartilage at different development ages by miRNAs Microarray analysis. We used microarrays to detail the global programme of gene expression underlying the rat knee cartilage and identified distinct classes of age-related miRNAs during this process. The rat knee articular cartilage were selected at successive stages of the rat developmental for RNA extraction and hybridization on Affymetrix microarrays. We sought to obtain homogeneous populations of cartilage at each developmental stage in order to increase the temporal resolution of expression profiles. To that end, we hand-selected cartilage according to the rat developmental stages, i.e. seven time-points: newborn (T0), childhood (T1), youth(T2), adult (T3), middle-aged (T4) early-stage elderly(T5) and latter-stage elderly(T6). The objective of the study is to identify miRNA profile of knee articular cartilage at different developmental ages in rats. Total RNA were extracted from the knee articular cartilage of Sprague-Dawley rats at postnatal day 0(T0), week1(T1), week 4(T2), mon3(T3), mon 6(T4), mon 12(T5), and mon 18(T6). The microRNA profile in the specimens was detected with the Affymetrix GeneChip® miRNA 3.0 Array.
Project description:Cartilage destruction in osteoarthritis (OA) results from disturbed chondrocyte metabolism. Here, we used microarrays to show that TGF alpha and CCL2 are simultaneously upregulated in a rat model of OA and cooperate to drive cartilage degradation. The goals of the experiments included here were to a) characterize gene expression in knee joint articular chondrocytes at various stages of development of OA (2 and 8 weeks after surgical induction of OA), and b) to establish trends in gene expression among groups of genes related to the TGF alpha-EGFR axis, over time, in OA. The model chosen to study these results has been previously validated (Appleton, CT et al, 2007, Arthritis Rheum) and used to describe similar gene expression results at a different time point (4 weeks) after induction of OA. The rat model of OA involves surgical destabilization of the knee joint, followed by forced low-intensity mobilization over several weeks; a sham surgery is used as the control (representing a healthy non-OA knee joint) wherein a surgical incision is made but not structural (i.e. ligamentous) modification is made to the joint. Altogether, our data indicate that TGF and CCL2 cooperate to drive cartilage degradation in osteoarthritis. A total of 12 samples were analyzed. 3 replicates were used per condition: OA surgery at 2 weeks, OA surgery at 8 weeks, Sham (control) surgery at 2 weeks and Sham surgery at 8 weeks. Expression of OA samples was assessed relaitve to Sham (control) expression levels.
Project description:Cartilage destruction in osteoarthritis (OA) results from disturbed chondrocyte metabolism. Here, we used microarrays to show that TGF alpha and CCL2 are simultaneously upregulated in a rat model of OA and cooperate to drive cartilage degradation. The goals of the experiments included here were to a) characterize gene expression in knee joint articular chondrocytes at various stages of development of OA (2 and 8 weeks after surgical induction of OA), and b) to establish trends in gene expression among groups of genes related to the TGF alpha-EGFR axis, over time, in OA. The model chosen to study these results has been previously validated (Appleton, CT et al, 2007, Arthritis Rheum) and used to describe similar gene expression results at a different time point (4 weeks) after induction of OA. The rat model of OA involves surgical destabilization of the knee joint, followed by forced low-intensity mobilization over several weeks; a sham surgery is used as the control (representing a healthy non-OA knee joint) wherein a surgical incision is made but not structural (i.e. ligamentous) modification is made to the joint. Altogether, our data indicate that TGF and CCL2 cooperate to drive cartilage degradation in osteoarthritis.
Project description:We elucidated the molecular cross-talk between knee articular cartilage and paired synovium in n=3 individuals with knee osteoarthritis using the powerful tool of single-cell RNA-sequencing. Multiple cell types were identified based on profiling of 10,640 synoviocytes and 26,192 chondrocytes (11,579 chondrocytes from the diseased medial vs 14,613 chondrocytes from the relatively non-diseased lateral tibial plateau): 12 distinct synovial cell types and 7 distinct articular chondrocyte phenotypes from matched tissues. Intact cartilage was enriched for homeostatic and hypertrophic chondrocytes, while damaged cartilage was enriched for prefibro- and fibro-, regulatory, reparative and prehypertrophic chondrocytes. A total of 61 cytokines and growth factors were predicted to regulate the 7 chondrocyte cell phenotypes. Based on production by >1% of cells, 55% of the cytokines were produced by synovial cells (39% exclusive to synoviocytes and not expressed by chondrocytes) and their presence in osteoarthritic synovial fluid confirmed. The synoviocytes producing IL-1beta (a classic pathogenic cytokine in osteoarthritis), mainly inflammatory macrophages and dendritic cells, were characterized by co-expression of surface proteins corresponding to HLA-DQA1, HLA-DQA2, OLR1 or TLR2. Strategies to deplete these pathogenic intra-articular cell subpopulations could be a therapeutic option for human osteoarthritis.
Project description:Age as the primary rise factor could be play an important role in incidence and development of osteoarthritis. A few studies have confirmed some tissue specific lncRNA were associated with development of osteoarthritis. But if age related lncRNA would be involved in pivotal post-transcriptional gene regulation in osteoarthritis is unclear. In view of this, we have an idea that several age-related lncRNA would be screened from the rat knee cartilage at different development ages by lncRNAs Microarray analysis. We used microarrays to detail the global programme of gene expression underlying the rat knee cartilage and identified distinct classes of age-related lncRNA during this process. The rat knee articular cartilage were selected at successive stages of the rat developmental for RNA extraction and hybridization on Affymetrix lncRNA arrays. We sought to obtain homogeneous populations of cartilage at each developmental stage in order to increase the temporal resolution of expression profiles. To that end, we hand-selected cartilage according to the rat developmental stages, i.e. seven time-points: newborn (T0), youth(T1), adult (T2), early-stage elderly(T3) and latter-stage elderly(T4).
Project description:Cartilage aging is a quintessential feature of knee osteoarthritis, and extracellular matrix (ECM) stiffening is a typical feature of cartilage aging. However, the mechanism of ECM stiffening to influence chondrocytes and downstream molecules is still poorly understood. Here, we mimicked the physiological and pathological stiffness of human cartilage by using polydimethylsiloxane-based substrates. We show that the epigenetic regulation of Parkin by histone deacetylase 3 (HDAC3) represents a new mechanosensitive mechanism by which the stiff matrix affects the physiology of chondrocytes. We found that ECM stiffening could accelerate the senescence of cultured chondrocytes in vitro, and also found that stiff ECM downregulated HDAC3, drove Parkin acetylation to activate excessive mitophagy, and accelerated chondrocyte senescence and osteoarthritis in mice. In contrast, intra-articular injection of adeno-associated virus expressing HDAC3 restored the young phenotype of aged chondrocytes stimulated by ECM stiffening and alleviated osteoarthritis in mice. Our findings indicate that changes in the mechanical properties of ECM initiate pathogenic mechanotransduction signals, promote the acetylation of Parkin and hyperactivate mitophagy, and damage the health of chondrocytes. These findings may provide new insights into how the mechanical properties of ECM regulate chondrocytes.
Project description:Steroid and xenobiotic receptor (SXR) and its murine ortholog pregnane X receptor (PXR) are nuclear receptors that are expressed mainly in the liver and the intestine. They function as xenobiotic sensors by inducing genes involved in detoxification and drug excretion. Recent evidence showed that SXR and PXR are also expressed in bone tissue where they mediate bone metabolism. Here we report that systemic deletion of PXR results in aging-dependent wearing of articular cartilage of knee joints. Histomorphometrical analysis showed remarkable reduction of width and an enlarged gap between femoral and tibial articular cartilage in PXR knockout mice. We hypothesized that genes induced by SXR in chondrocytes have a protective effect on articular cartilage and identified Fam20a (family with sequence similarity 20a) as an SXR-dependent gene induced by the known SXR ligands, rifampicin and vitamin K2. Lastly, we demonstrated the biological significance of Fam20a expression in chondrocytes by evaluating osteoarthritis-related gene expression of primary articular chondrocytes. Consistent with epidemiological findings, our findings indicate that SXR/PXR protects against aging-dependent wearing of articular cartilage and that ligands for SXR/PXR have potential role in preventing osteoarthritis caused by aging.
Project description:Osteoarthritis (OA) is a degenerative joint disease and a leading cause of disability worldwide. Aging is one of the major risk factors for OA, with the disease prevalence dramatically increasing after age 50. While OA is strongly associated with aging, the specific mechanisms underlying this connection remain unclear. In this pilot study, we performed bulk RNA sequencing on human knee articular chondrocytes to identify transcriptomic changes underlying OA development in the context of aging. We compared the gene expression profiles of chondrocytes isolated from osteoarthritic cartilage of older individuals (age 70-80 years) to those of chondrocytes from the healthy cartilage of a young adult (age 26 years). To model aging in vitro, chondrocytes were serially passaged until they reached the replicative senescence.