Comparison of secretome from osteoblasts derived from sclerotic versus non-sclerotic subchondral bone in OA: A pilot study

Abstract

ObjectiveOsteoarthritis (OA) is characterized by cartilage degradation but also by other joint tissues modifications like subchondral bone sclerosis. In this study, we used a proteomic approach to compare secretome of osteoblast isolated from sclerotic (SC) or non sclerotic (NSC) area of OA subchondral bone.DesignSecretome was analyzed using differential quantitative and relative label free analysis on nanoUPLC G2 HDMS system. mRNA of the more differentially secreted proteins were quantified by RT-PCR in cell culture from 5 other patients. Finally, osteomodulin and fibulin-3 sequences were quantified by western blot and immunoassays in serum and culture supernatants.Results175 proteins were identified in NSC osteoblast secretome. Data are available via ProteomeXchange with identifier PXD008494. Compared to NSC osteoblast secretome, 12 proteins were significantly less secreted (Osteomodulin, IGFBP5, VCAM-1, IGF2, 78 kDa glucose-regulated protein, versican, calumenin, IGFBP2, thrombospondin-4, periostin, reticulocalbin 1 and osteonectin), and 13 proteins were significantly more secreted by SC osteoblasts (CHI3L1, fibulin-3, SERPINE2, IGFBP6, SH3BGRL3, SERPINE1, reticulocalbin3, alpha-2-HS-glycoprotein, TIMP-2, IGFBP3, TIMP-1, SERPINF1, CSF-1). Similar changes in osteomodulin, IGF2, SERPINE1, fibulin-3 and CHI3L1 mRNA levels were observed. ELISAs assays confirm the decrease by half of osteomodulin protein in SC osteoblasts supernatant compared to NSC and in OA patients serum compared to healthy subjects. Fibulin-3 epitopes Fib3-1, Fib3-2 and Fib3-3 were also increased in SC osteoblasts supernatant compared to NSC.ConclusionsWe highlighted some proteins differentially secreted by the osteoblasts coming from OA subchondral bone sclerosis. These changes contribute to explain some features observed in OA subchondral bone, like the increase of bone remodeling or abnormalities in bone matrix mineralization. Among identified proteins, osteomodulin was found decreased and fibulin-3 increased in serum of OA patients. These findings suggest that osteomodulin and fibulin-3 fragments could be biomarkers to monitor early changes in subchondral bone metabolism in OA.

Gene expression and functional comparison between multipotential stromal cells from lateral and medial condyles of knee osteoarthritis patients

“…Whereas a little overlap between differentially regulated genes in both MSCs and chondrocytes was found, SERPINE1 was one molecule showing parallel up-regulation in medial condyle MSCs and chondrocytes. Consistent with our findings SERPINE1 protein was found to be more abundant in the supernatants of cultured osteoblasts derived from sclerotic areas of OA subchondral bone 54 , however in contrast to our study, its mRNA expression was found to be lower in medial condyle chondrocytes, compared to healthy or lateral condyle chondrocytes in another study 55 . These differences can be partially explained by the fact, that SERPINE1 expression is downregulated in chondrocyte culture 56 .…”

Microenvironment in subchondral bone: predominant regulator for the treatment of osteoarthritis

“…56 In addition, slit guidance ligand (SLIT3) and TGF-β1 derived from osteoblasts acts as pro-angiogenic factors to increase the number of type H ECs. [57][58][59] Notably, TGF-β1 derived from osteoclastic resorption is primarily responsible for subchondral angiogenesis in earlystage OA, 60 while the increase in preosteoclast-derived PDGF-BB plays a relatively predominant role in angiogenic and osteogenic differentiation in late-stage OA (figure 2). 61…”

Cancer Metastases to Bone: Concepts, Mechanisms, and Interactions with Bone Osteoblasts

“…In addition to osteomyelitis, osteoarthritis is a common joint disease typically characterized by chronic inflammation and altered osteoblast function. It has been demonstrated that osteoblasts produce increased amounts of the inflammatory cytokines IL-6, IL-8, prostaglandin E2 (PGE2), and vascular endothelial growth factor (VEGF); extracellular matrix markers matrix metalloproteinase-9 (MMP-9) and type I collagen; as well as tumor-growth factor beta-1 (TGF-beta 1) in regions of sclerotic bone as compared to normal bone [ 30 , 31 , 57 ]. And, similar to osteomyelitis, regions of osteoarthritis are marked by an imbalance in alkaline phosphatase expression, and a reduction in osteoblast mineralization and bone sialoprotein expression [ 58 , 59 ].…”

“…Under conditions of normal bone homeostasis, there is a tightly regulated balance between bone deposition and resorption, where there is no net bone gain or loss. However, this balance is upset in several pathological conditions, including osteomyelitis, osteoarthritis, and bone metastatic cancers [ 28 , 29 , 30 , 31 ]. In each of these conditions, and especially in osteolytic disease, osteoclasts are overstimulated to degrade bone.…”