Regulation of MMP3 by laminin alpha 4 in human osteoarthritic cartilage

Osteoarthritis related epigenetic variations in miRNA expression and DNA methylation

Osteoarthritis (OA) is chronic arthritis characterized by articular cartilage degradation. However, a comprehensive regulatory network for OA-related microRNAs and DNA methylation modifications has yet to be established. Thus, we aimed to identify epigenetic changes in microRNAs and DNA methylation and establish the regulatory network between miRNAs and DNA methylation. The mRNA, miRNA, and DNA methylation expression profiles of healthy or osteoarthritis articular cartilage samples were downloaded from Gene Expression Omnibus (GEO) database, including GSE169077, GSE175961, and GSE162484. The differentially expressed genes (DEGs), differentially expressed miRNAs (DEMs), and differentially methylated genes (DMGs) were analyzed by the online tool GEO2R. DAVID and STRING databases were applied for functional enrichment analysis and protein-protein interaction (PPI) network. Potential therapeutic compounds for the treatment of OA were identified by Connectivity map (CMap) analysis. A total of 1424 up-regulated DEGs, 1558 down-regulated DEGs, 5 DEMs with high expression, 6 DEMs with low expression, 1436 hypermethylated genes, and 455 hypomethylated genes were selected. A total of 136 up-regulated and 65 downregulated genes were identified by overlapping DEGs and DEMs predicted target genes which were enriched in apoptosis and circadian rhythm. A total of 39 hypomethylated and 117 hypermethylated genes were obtained by overlapping DEGs and DMGs, which were associated with ECM receptor interactions and cellular metabolic processes, cell connectivity, and transcription. Moreover, The PPI network showed COL5A1, COL6A1, LAMA4, T3GAL6A, and TP53 were the most connective proteins. After overlapping of DEGs, DMGs and DEMs predicted targeted genes, 4 up-regulated genes and 11 down-regulated genes were enriched in the Axon guidance pathway. The top ten genes ranked by PPI network connectivity degree in the up-regulated and downregulated overlapping genes of DEGs and DMGs were further analyzed by the CMap database, and nine chemicals were predicted as potential drugs for the treatment of OA. In conclusion, TP53, COL5A1, COL6A1, LAMA4, and ST3GAL6 may play important roles in OA genesis and development.

The tendon interfascicular basement membrane provides a vascular niche for CD146+ cell subpopulations

Introduction: The interfascicular matrix (IFM; also known as the endotenon) is critical to the mechanical adaptations and response to load in energy-storing tendons, such as the human Achilles and equine superficial digital flexor tendon (SDFT). We hypothesized that the IFM is a tendon progenitor cell niche housing an exclusive cell subpopulation. Methods: Immunolabelling of equine superficial digital flexor tendon was used to identify the interfascicular matrix niche, localising expression patterns of CD31 (endothelial cells), Desmin (smooth muscle cells and pericytes), CD146 (interfascicular matrix cells) and LAMA4 (interfascicular matrix basement membrane marker). Magnetic-activated cell sorting was employed to isolate and compare in vitro properties of CD146+ and CD146- subpopulations. Results: Labelling for CD146 using standard histological and 3D imaging of large intact 3D segments revealed an exclusive interfascicular cell subpopulation that resides in proximity to a basal lamina which forms extensive, interconnected vascular networks. Isolated CD146+ cells exhibited limited mineralisation (osteogenesis) and lipid production (adipogenesis). Discussion: This study demonstrates that the interfascicular matrix is a unique tendon cell niche, containing a vascular-rich network of basement membrane, CD31+ endothelial cells, Desmin+ mural cells, and CD146+ cell populations that are likely essential to tendon structure and/or function. Contrary to our hypothesis, interfascicular CD146+ subpopulations did not exhibit stem cell-like phenotypes. Instead, our results indicate CD146 as a pan-vascular marker within the tendon interfascicular matrix. Together with previous work demonstrating that endogenous tendon CD146+ cells migrate to sites of injury, our data suggest that their mobilisation to promote intrinsic repair involves changes in their relationships with local interfascicular matrix vascular and basement membrane constituents.

Comparative proteomics analysis reveals the difference during antler regeneration stage between red deer and sika deer

Deer antler, as the only mammalian regenerative appendage, provides an optimal model to study regenerative medicine. Antler harvested from red deer or sika deer were mainly study objects used to disclose the mechanism underlying antler regeneration over past decades. A previous study used proteomic technology to reveal the signaling pathways of antler stem cell derived from red deer. Moreover, transcriptome of antler tip from sika deer provide us with the essential genes, which regulated antler development and regeneration. However, antler comparison between red deer and sika deer has not been well studied. In our current study, proteomics were employed to analyze the biological difference of antler regeneration between sika deer and red deer. The proteomics profile was completed by searching the UniProt database, and differentially expressed proteins were identified by bioinformatic software. Thirty-six proteins were highly expressed in red deer antler, while 144 proteins were abundant in sika deer. GO and KEGG analysis revealed that differentially expressed proteins participated in the regulation of several pathways including oxidative phosphorylation, ribosome, extracellular matrix interaction, and PI3K-Akt pathway.

A Meta-Analysis of Non-Osteoarthritis and Osteoarthritis Chondrocyte Gene Expression to Determine the Efficacy of Autologous Chondrocyte Transplantation as a Viable Treatment Option

BACKGROUND

Osteoarthritis (OA) is a clinical syndrome characterized by joint failure that is accompanied by pain and functional limitations. OA is the leading cause of chronic disability in elderly and it is estimated that the United States spends $185 billion in management of OA annually. Although OA patients receive both pharmacologic and non-pharmacologic treatments, none of them provide long-lasting treatments. Since 1980s, autologous chondrocyte transplantation (ACT) has been used to regenerate cartilage within focal cartilage defects of young patients without pre-existing OA with increased functionality by 74% to 90%. In this technique, chondrocytes are removed from patients, multiplied in vitro, then implanted into the focal cartilage defect. Our review aimed to compare chondrocyte gene expression profiles of non-OA patients with OA patients to determine if OA-derived chondrocytes could be used for the ACT.

METHODS

An extensive literature search was conducted with following criteria:(1) comparing chondrocyte gene expression profiles of OA joint and non-OA joint, or (2)relating to ACT. Ingenuity Pathway Analysis (IPA) was then utilized to analyze the differential chondrocyte gene expression profiles of OA to non-OA patients to identify key associated biological pathways.

RESULTS

Differential gene expression profiles were similar between non-OA and OA chondrocytes: including ACAN, COL2A1, COL1A1, SOX 6 (p<0.001-0.05); FN1, COL11A1, MMP7, DLX5, SOX9, MMP2, TGFB1, THBS3, COMP, CILP2, ASPN, IGF2, DPT (p<0.001-0.05), and ADAMTS5, LAMA4 (p<0.01-0.05).

CONCLUSION

These genes are important to cartilage function. Therefore, our results suggest that OA-derived chondrocytes may be useful to heal focal cartilage defects using ACT.

The role of laminins in cartilaginous tissues: from development to regeneration

As a key molecule of the extracellular matrix, laminin provides a delicate microenvironment for cell functions. Recent findings suggest that laminins expressed by cartilage-forming cells (chondrocytes, progenitor cells and stem cells) could promote chondrogenesis. However, few papers outline the effect of laminins on providing a favorable matrix microenvironment for cartilage regeneration. In this review, we delineated the expression of laminins in hyaline cartilage, fibrocartilage and cartilage-like tissue (nucleus pulposus) throughout several developmental stages. We also examined the effect of laminins on the biological activities of chondrocytes, including adhesion, migration and survival. Furthermore, we scrutinized the potential influence of various laminin isoforms on cartilage-forming cells' proliferation and chondrogenic differentiation. With this information, we hope to facilitate the understanding of the spatial and temporal interactions between cartilage-forming cells and laminin microenvironment to eventually advance cell-based cartilage engineering and regeneration.

Effect of Laminin-A4 inhibition on cluster formation of human osteoarthritic chondrocytes

Formation of chondrocyte clusters is not only a morphological sign of osteoarthritis but it is also observed in cell culture. Active locomotion of chondrocytes is controlled by integrins in vitro. Integrins bind to Laminin-A4 (LAMA4), a protein that is highly expressed in vivo in clusters of hypertrophic chondrocytes. We tested if LAMA4 is relevant for cluster formation. Human chondrocytes were cultured in a 2D matrigel model and treated with different concentrations of a monoclonal inhibitory anti-LAMA4-antibody. Migration and cluster formation was analysed using live cell imaging technique. Full genome gene expression analysis was performed to assess the effect of LAMA4 inhibition. The data set were screened for genes relevant to cell motility. F-actin staining was performed to document cytoskeletal changes. Anti-LAMA4 treatment significantly reduced the rate of cluster formation in human chondrocytes. Cells changed their surface morphology and exhibited fewer protrusions. Expression of genes associated with cellular motility and migration was affected by anti-LAMA4 treatment. LAMA4-integrin signalling affects chondrocyte morphology and gene expression in vitro, thereby contributing to cluster formation in human osteoarthritic chondrocytes.

Laminins and Nidogens in the Pericellular Matrix of Chondrocytes: Their Role in Osteoarthritis and Chondrogenic Differentiation

The aim of this study was to investigate the role of laminins and nidogen-2 in osteoarthritis (OA) and their potential to support chondrogenic differentiation. We applied immunohistochemistry, electron microscopy, siRNA, quantitative RT-PCR, Western blot, and proteome analysis for the investigation of cartilage tissue and isolated chondrocytes in three-dimensional culture obtained from patients with late-stage knee OA and nidogen-2 knockout mice. We demonstrate that subunits of laminins appear in OA cartilage and that nidogen-2-null mice exhibit typical osteoarthritic features. Chondrogenic progenitor cells (CPCs) produced high levels of laminin-α1, laminin-α5, and nidogen-2 in their pericellular matrix, and laminin-α1 enhanced collagen type II and reduced collagen type I expression by cultured CPCs. Nidogen-2 increased SOX9 gene expression. Knockdown of nidogen-2 reduced SOX9 expression, whereas it up-regulated RUNX2 expression. This study reveals that the influence of the pericellular matrix on CPCs is important for the expression of the major regulator transcription factors, SOX9 and RUNX2. Our novel findings that laminins and nidogen-2 drive CPCs toward chondrogenesis may help in the elucidation of new treatment strategies for cartilage tissue regeneration.

Sphingosine 1-phosphate counteracts the effects of interleukin-1β in human chondrocytes

Objective

The lipid mediator sphingosine 1-phosphate (S1P) is found in the synovial fluid of osteoarthritis (OA) patients. S1P protects bovine cartilage by counteracting the effects of interleukin-1β (IL-1β). This study was undertaken to examine the interaction of S1P and IL-1β in human OA chondrocytes.

Methods

Human cartilage was obtained from patients undergoing total knee joint replacement. Chondrocytes were cultured in monolayer and treated with IL-1β and S1P. Expression of S1P receptor subtypes and genes involved in cartilage degradation was evaluated using real-time polymerase chain reaction, immunohistochemistry, and Western blotting. S1P signaling was evaluated using inhibitors of S1P receptors and small interfering RNA (siRNA) knockdown of the S1P₂ receptor. Phosphorylation of MAP kinases and NF-κB in response to IL-1β and S1P was detected by Western blotting.

Results

S1P₂ was identified as the most prevalent S1P receptor subtype in human OA cartilage and chondrocytes in vitro. S1P reduced expression of inducible nitric oxide synthase (iNOS) in IL-1β–treated chondrocytes. Reduction of ADAMTS-4 and matrix metalloproteinase 13 expression by S1P correlated with S1P₂ expression. Pharmacologic inhibition of the S1P₂ receptor, but not the S1P₁ and S1P₃ receptors, abrogated the inhibition of iNOS expression. Similar results were observed using siRNA knockdown. S1P signaling inhibited IL-1β–induced phosphorylation of p38 MAPK.

Conclusion

In human chondrocytes, S1P reduces the induction of catabolic genes in the presence of IL-1β. Activation of the S1P₂ receptor counteracts the detrimental phosphorylation of p38 MAPK by IL-1β.