Project description:Mechanical Stimuli are arguably the most important aetiolgical factors in osteoarthritis (OA) development. Not only do we see disease arising from joints where the cartilage has sustained direct (e.g. intraarticular fracture) or indirect (e.g. meniscal injury) trauma, but mechanical factors are considered, at least partly, to explain the disease associations with aging and obesity. It is now well established that OA is not simply due to repeated wear and tear, leading to attrition of the articular surfaces, but that it requires activation of a number of inflammatory genes, which drive catabolic protease activity in the joint. These enzymes lead to breakdown of the major extracellular matrix components of cartilage, namely type II collagen, and the proteoglycan, aggrecan. Although it is unclear precisely which enzymes are responsible for matrix breakdown in human OA, Glasson et al showed that deletion of the aggrecan degrading enzyme, ADAMTS5 substantially protected the joint from surgically induced murine OA suggesting that it is a major aggrecanase in the mouse. This study was part of a wider study using the surgical model of murine OA, induced by destabilising the medial meniscus (DMM), to confirm the dependence of joint loading on disease progression and to reveal mechanosensitive genes within the joint which may be involved in the development of OA. Using this model we, and others, have shown that there is a robust degradation of articular cartilage over 4-12wks in male C57B/6 mice. We identified the gene response in joints early following induction of OA, prior to cartilage degradation, by extracting RNA from whole joints (after skin and muscle had been removed) 6hrs, 3 days and 7 days following sham and DMM surgery. An Affymetrix ST1 gene array was performed. Significantly regulated genes (>1.4 fold above naive and sham samples at any timepoint), or those considered to have a putative role in OA pathogenesis were selected for quantitative validation using Taqman low density microfluidic card arrays (TLDA). Gene expression in whole knee joints at 3 early time points post DMM surgery (before cartilage loss), 6hrs, 3days and 7days was examined. Two controls were identified, the first control consisted of age matched naïve mice that had undergone 15 minutes of anaesthesia but were not operated on (0hrs post surgery). The second control included mice which had undergone sham surgery (capsulotomy alone). For this RNA was taken at the same time points post surgery as DMM samples (6hrs, 3days and 7days). There were three biological replicates per condition (total of 21 samples). The right (ipsilateral) knee joint was taken and RNA extracted and processed for microarray analysis using the Affymetrix Mouse Gene 1.0 st v1 platform.

Project description:Mechanical Stimuli are arguably the most important aetiolgical factors in osteoarthritis (OA) development. Not only do we see disease arising from joints where the cartilage has sustained direct (e.g. intraarticular fracture) or indirect (e.g. meniscal injury) trauma, but mechanical factors are considered, at least partly, to explain the disease associations with aging and obesity. It is now well established that OA is not simply due to repeated wear and tear, leading to attrition of the articular surfaces, but that it requires activation of a number of inflammatory genes, which drive catabolic protease activity in the joint. These enzymes lead to breakdown of the major extracellular matrix components of cartilage, namely type II collagen, and the proteoglycan, aggrecan. Although it is unclear precisely which enzymes are responsible for matrix breakdown in human OA, Glasson et al showed that deletion of the aggrecan degrading enzyme, ADAMTS5 substantially protected the joint from surgically induced murine OA suggesting that it is a major aggrecanase in the mouse. This study was part of a wider study using the surgical model of murine OA, induced by destabilising the medial meniscus (DMM), to confirm the dependence of joint loading on disease progression and to reveal mechanosensitive genes within the joint which may be involved in the development of OA. Using this model we, and others, have shown that there is a robust degradation of articular cartilage over 4-12wks in male C57B/6 mice. We identified the gene response in joints early following induction of OA, prior to cartilage degradation, by extracting RNA from whole joints (after skin and muscle had been removed) 6hrs, 3 days and 7 days following sham and DMM surgery. An Affymetrix ST1 gene array was performed. Significantly regulated genes (>1.4 fold above naive and sham samples at any timepoint), or those considered to have a putative role in OA pathogenesis were selected for quantitative validation using Taqman low density microfluidic card arrays (TLDA).

Project description:OBJECTIVE: To analyze genome-wide changes in chondrocyte gene expression in a surgically induced model of early osteoarthritis (OA) in rats, to assess the similarity of this model to human OA, and to identify genes and mechanisms leading to OA pathogenesis. METHODS: OA was surgically induced in 5 rats by anterior cruciate ligament transection and partial medial meniscectomy. Sham surgery was performed in 5 additional animals, which were used as controls. Both groups underwent 4 weeks of forced mobilization, 3 times per week. RNA was extracted directly from articular chondrocytes in the OA (operated), contralateral, and sham-operated knees. Affymetrix GeneChip expression arrays were used to assess genome-wide changes in gene expression. Expression patterns of selected dysregulated genes, including Col2a1, Mmp13, Adamts5, Ctsc, Ptges, and Cxcr4, were validated by real-time polymerase chain reaction, immunofluorescence, or immunohistochemistry 2, 4, and 8 weeks after surgery. RESULTS: After normalization, comparison of OA and sham-operated samples showed 1,619 differentially expressed probe sets with changes in their levels of expression >/=1.5-fold, 722 with changes >/=2-fold, 135 with changes >/=4-fold, and 20 with changes of 8-fold. Dysregulated genes known to be involved in human OA included Mmp13, Adamts5, and Ptgs2, among others. Several dysregulated genes (e.g., Reln, Phex, and Ltbp2) had been identified in our earlier microarray study of hypertrophic chondrocyte differentiation. Other genes involved in cytokine and chemokine signaling, including Cxcr4 and Ccl2, were identified. Changes in gene expression were also observed in the contralateral knee, validating the sham operation as the appropriate control. CONCLUSION: Our results demonstrate that the animal model mimics gene expression changes seen in human OA, supporting the relevance of newly identified genes and pathways to early human OA. We propose new avenues for OA pathogenesis research and potential targets for novel OA treatments, including cathepsins and cytokine, chemokine, and growth factor signaling pathways, in addition to factors controlling the progression of chondrocyte differentiation. Experiment Overall Design: OA was surgically induced in 5 rats by anterior cruciate ligament transection and partial medial meniscectomy. Sham surgery was performed in 5 additional animals, which were used as controls. Both groups underwent 4 weeks of forced mobilization, 3 times per week. RNA was extracted directly from articular chondrocytes in the OA (operated), contralateral, and sham-operated knees, 28 days post-surgery. Affymetrix GeneChip expression arrays were used to assess genome-wide changes in gene expression.

Dataset Information

ScRNA-seq performed in the knee joint of the DMM-induced OA mouse model versus sham-operated mice

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets