Project description:Osteoarthritis (OA) is a complex degenerative joint disease, which is not only a cartilage but also a bone disease. A better understanding of the early molecular mechanism changes of subchondral bone in vivo may contribute to elucidating the pathogenesis of OA. We used microarray technology to investigate the time-course molecular changes of subchondral bone just beneath damaged cartilage in early stage of experimental osteoarthritis, and found 2,234 differentially expressed (DE) genes at 1 week, 1,944 at 2 weeks and 1,517 at 4 weeks postsurgery.Further analysis of dysregulated genes indicated that subchondral bone remodeling occurred sequentially and in a time-dependent manner at the gene expression level. Some known dysregulated genes suspected roles in influencing bone development or bone remodeling, such as Alp, Igf1, Tgf β1, Postn, Mmp3, Tnfsf11, Acp5, Bmp5, Aspn and Ihh, were confirmed by real-time PCR, and results indicated that our microarray data could accurately reflect gene expression patterns of early OA. Subsequently, to validate the results of our microarray analysis at protein level, immunohistochemistry staining was introduced to investigate the translational level of genes Mmp3 and Aspn in tissue sections, and results showed that the level of Mmp3 protein expression was totally matched the results of microarray and real-time PCR analysis. Nevertheless, the expression of Aspn protein was not observed differentially expressed at any time point.
Project description:To date, all of the prior osteoarthritic microarray studies in human tissue have focused on the overlying articular cartilage, meniscus, or synovium but not the underlying subchondral bone. In our previous study, our group developed a methodology for high quality RNA isolation from site-matched cartilage and bone from human knee joints, which allowed us to perform candidate gene expression analysis on the subchohndral bone (published on Osteoarthritis and Cartilage on Dec/5/2012 (doi: 10.1016/j.joca.2012.11.016). To the best of our knowledge, the current study is the first to successfully perform whole-genome microarray profiling analyses of human osteoarthritic subchondral bone. We believe our comprehensive microarray results can improve the understanding of the pathogenesis of osteoarthritis and could further contribute to the development of new biomarker and therapeutic strategies in osteoarthritis.
Project description:Osteoarthritis (OA) is a complex degenerative joint disease, which is not only a cartilage but also a bone disease. A better understanding of the early molecular mechanism changes of subchondral bone in vivo may contribute to elucidating the pathogenesis of OA. We used microarray technology to investigate the time-course molecular changes of subchondral bone just beneath damaged cartilage in early stage of experimental osteoarthritis, and found 2,234 differentially expressed (DE) genes at 1 week, 1,944 at 2 weeks and 1,517 at 4 weeks postsurgery.Further analysis of dysregulated genes indicated that subchondral bone remodeling occurred sequentially and in a time-dependent manner at the gene expression level. Some known dysregulated genes suspected roles in influencing bone development or bone remodeling, such as Alp, Igf1, Tgf M-NM-21, Postn, Mmp3, Tnfsf11, Acp5, Bmp5, Aspn and Ihh, were confirmed by real-time PCR, and results indicated that our microarray data could accurately reflect gene expression patterns of early OA. Subsequently, to validate the results of our microarray analysis at protein level, immunohistochemistry staining was introduced to investigate the translational level of genes Mmp3 and Aspn in tissue sections, and results showed that the level of Mmp3 protein expression was totally matched the results of microarray and real-time PCR analysis. Nevertheless, the expression of Aspn protein was not observed differentially expressed at any time point. Ninety 10-week-old male Sprague-Dawley rats, weighing 300-325g, were used in the study. Animals were equally divided into two groups: experimental group (E-Group) and sham-operated group (S-Group). The E-Group rats underwent open surgery, involved in both medial meniscectomy and medial collateral ligament (MCL) transaction with micro-scissors. The S-Group rats were carried out with a sham operation, via a similar incision, without operations of the medial meniscus and the medial collateral ligament.Animals were killed at 1, 2, and 4 weeks postsurgery, and 15 animals were put into use per-timepoint in each treatment group. 5 animals were used for histological analysis and immunohistochemistry, and others were used for microarray study and Real-time polymerase chain reaction (PCR) analysis equally at each timepoint.
Project description:The composition of subchondral bone cell types in patients with osteoarthritis (OA) and the underlying spatiotemporal transformation processes remain unknown. Here, we identified various subchondral bone cell subsets and investigated the mechanism of subchondral bone microstructure alteration using single-cell RNA sequencing (scRNA-seq).
Project description:Osteoarthritis (OA) is the most common joint disease and this is a major cause of joint pain and disability in the aging population. Its etiology is multifactorial (i.e., age, obesity, joint injury, genetic predisposition), and the pathophysiologic process affects the entirety of the joint (Martel-Pelletier J et al. Osteoarthritis. Nature reviews Disease primers. 2016;2:16072). Although it is not yet clear if it precedes or occurs subsequently to cartilage damage, subchondral bone sclerosis is an important feature in OA pathophysiology (Goldring SR et al. Changes in the osteochondral unit during osteoarthritis: structure, function and cartilage-bone crosstalk. Nat Rev Rheumatol. 2016;12:632-44). It is characterized by local bone resorption and the accumulation of weakly mineralized osteoid substance (Bailey AJ et al. Phenotypic expression of osteoblast collagen in osteoarthritic bone: production of type I homotrimer. Int J Biochem Cell Biol. 2002;34:176-82). Subchondral bone sclerosis is suspected to be linked to cartilage degradation, not only by modifying the mechanical stresses transmitted to the cartilage, but also by releasing biochemical factors with an activity on cartilage metabolism (Sanchez C et al. Osteoblasts from the sclerotic subchondral bone downregulate aggrecan but upregulate metalloproteinases expression by chondrocytes. This effect is mimicked by interleukin-6, -1beta and oncostatin M pre-treated non-sclerotic osteoblasts. Osteoarthritis Cartilage. 2005;13:979-87; Sanchez C et al. Subchondral bone osteoblasts induce phenotypic changes in human osteoarthritic chondrocytes. Osteoarthritis Cartilage. 2005;13:988-97; Westacott CI et al J. Alteration of cartilage metabolism by cells from osteoarthritic bone. Arthritis Rheum. 1997;40:1282-91. We have previously demonstrated that osteoblasts isolated from subchondral OA bone exhibited an altered phenotype. More precisely, we showed that osteoblasts coming from the thickening (called sclerotic, SC) of subchondral bone located just below a cartilage lesion produced higher levels of alkaline phosphatase, interleukin (IL)-6, IL-8, prostaglandinE2, vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-9 and transforming growth factor(TGF)-β1 and type I collagen than osteoblasts coming from the non-thickening neighboring area (called non-sclerotic area, NSC) (Sanchez C et al. Phenotypic characterization of osteoblasts from the sclerotic zones of osteoarthritic subchondral bone. Arthritis Rheum. 2008;58:442-55; Sanchez C et al. Regulation of subchondral bone osteoblast metabolism by cyclic compression. Arthritis Rheum. 2012;64:1193-203.) To compare secretome of cells living in different in vivo conditions is useful, not only to better understand the pathological mechanisms underlying changes in OA subchondral bone, but also to identify soluble biomarkers potentially reflecting these changes. Using our well-characterised human subchondral osteoblast culture model, we compared the secretome of osteoblasts coming from sclerotic and non sclerotic OA subchondral bone. This approach allowed to identify changes in secretome that contribute to explain some subchondral bone abnormalities in OA and to propose osteomodulin and fibulin-3 as potential biomarkers of OA subchondral bone remodelling.
Project description:To date, all of the prior osteoarthritic microarray studies in human tissue have focused on the overlying articular cartilage, meniscus, or synovium but not the underlying subchondral bone. In our previous study, our group developed a methodology for high quality RNA isolation from site-matched cartilage and bone from human knee joints, which allowed us to perform candidate gene expression analysis on the subchohndral bone (published on Osteoarthritis and Cartilage on Dec/5/2012 (doi: 10.1016/j.joca.2012.11.016). To the best of our knowledge, the current study is the first to successfully perform whole-genome microarray profiling analyses of human osteoarthritic subchondral bone. We believe our comprehensive microarray results can improve the understanding of the pathogenesis of osteoarthritis and could further contribute to the development of new biomarker and therapeutic strategies in osteoarthritis. Following histological assessment of the integrity of overlying cartilage and the severity of bone abnormality by microcomputed tomography, we isolated total RNA from regions of interest from human OA (n=20) and non-OA (n=5) knee lateral and medial tibial plateaus (LT and MT). A whole-genome profiling study was performed on an Agilent microarray platform and analyzed using Agilent GeneSpring GX11.5. Confirmatory quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis was performed on samples from nine OA individuals to confirm differential expression of 85 genes identified by microarray. Ingenuity Pathway Analysis (IPA) was used to investigate canonical pathways and immunohistochemical staining was performed to validate protein expression levels in samples.
Project description:Osteoarthritis (OA) treatment is limited by the lack of effective non-surgical interventions to slow disease progression. Here, we examined the contributions of the subchondral bone properties to OA development. We used parathyroid hormone (PTH) to modulate bone mass prior to OA initiation and alendronate (ALN) to inhibit bone remodeling during OA progression. We examined the spatiotemporal progression of joint damage by combining histopathological and transcriptomic analyses across joint tissues. The additive effect of PTH pretreatment prior to OA initiation and ALN treatment during OA progression most effectively attenuated load-induced OA pathology. Individually, PTH directly improved cartilage health and slowed the development of cartilage damage, whereas ALN primarily attenuated subchondral bone changes associated with OA progression. Joint damage reflected early transcriptomic changes. With both treatments the structural changes were associated with early modulation of immunoregulation and -response pathways that may contribute to disease mechanisms. Overall, our results demonstrate the potential of subchondral bone-modifying therapies to slow the progression of OA.
Project description:Inflammation is a key component of pathological angiogenesis. Here we induce cornea neovascularisation using sutures placed into the cornea, and sutures are removed to induce a regression phase. We used whole transcriptome microarray to monitor gene expression profies of several genes