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Gene Expression Analyses of Subchondral Bone in Early Experimental Osteoarthritis by Microarray

ABSTRACT: 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.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE30322 | GEO | 2012/12/11

SECONDARY ACCESSION(S): PRJNA143609

REPOSITORIES: GEO

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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: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:Background Extracellular matrix (ECM) protein malfunction or defect may lead to temporomandibular joint osteoarthritis (TMJ OA). Dentin sialophophoprotein (DSPP) is a mandibular condylar cartilage ECM protein, and its deletion impacted cell proliferation and other extracellular matrix alterations of postnatal condylar cartilage. However, it remains unclear if long-term loss of function of DSPP leads to TMJ OA. The study aimed to test the hypothesis that long-term haploinsufficiency of DSPP causes TMJ OA. Materials and Methods To determine whether Dspp+/- mice exhibit TMJ OA but no severe tooth defects, mandibles of wild-type (WT), Dspp+/-, and Dspp homozygous (Dspp-/-) mice were analyzed by Micro-computed tomography (micro-CT). To characterize the progression and possible mechanisms of osteoarthritic degeneration over time in Dspp+/- mice over time, condyles of Dspp+/- and WT mice were analyzed radiologically, histologically, and immunohistochemically. Results Micro-CT and histomorphometric analyses revealed that Dspp+/- and Dspp-/- mice had significantly lower subchondral bone mass, bone volume fraction, bone mineral density, and trabecular thickness compared to WT mice at 12 months. Interestingly, in contrast to Dspp-/- mice which exhibited tooth loss, Dspp+/- mice had minor tooth defects. RNA sequencing data showed that haplodeficency of DSPP affects the biological process of ossification and osteoclast differentiation. Additionally, histological analysis showed that Dspp+/- mice had condylar cartilage fissures, reduced cartilage thickness, decreased articular cell numbers and severe subchondral bone cavities, and with signs that were exaggerated with age. Radiographic data showed an increase in subchondral osteoporosis up to 18 months and osteophyte formation at 21 months. Moreover, Dspp+/- mice showed increased distribution of osteoclast in the subchondal bone and increased expression of MMP2, IL-6, FN-1, and TLR4 in the mandibular condylar cartilage. Conclusions Dspp+/- mice exhibit TMJ OA in a time-dependent manner, with lesions in the mandibular condyle attributed to hypomineralization of subchondral bone and breakdown of the mandibular condylar cartilage, accompanied by upregulation of inflammatory markers.

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Gene Expression Analyses of Subchondral Bone in Early Experimental Osteoarthritis by Microarray

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