Osteoarthritis-associated fibrosis is related with both elevated pyridinoline cross-link formation and lysyl hydroxylase 2b expression

Abstract

Purpose: Exosomes containing proteins, microRNAs and mRNAs are found in extracellular spaces such as blood and other body fluids and function as messengers in cell-cell communication through transfer of their molecular content. We hypothesize that exosomes containing miRNAs function in a novel communication mechanism among joint cells in osteoarthritis (OA) pathogenesis. We previously observed that the balance of anabolic and catabolic gene expression in chondrocytes was impaired by exosomes derived from OAsynovial fibroblasts (SFB). Angiogenesis in various joint tissues, including synovium, ligaments, menisci and the osteochondral junction, is a recently recognized important factor in OA pathogenesis. The purpose of this study was to investigate potential angiogenic function of exosomes from OA-SFB. Methods: Human SFB were obtained from a normal, OA and rheumatoid arthritis (RA) knee joints, and cultured with or without interleukin-1b (IL-1b). Exosomes were isolated by ExoQuick from IL-1b stimulated medium and control medium. Isolated exosomes fraction was measured for protein content using BCA protein assay kit. To examine the angiogenic functions of exosomes derived from SFB, we examined whether migration and tube formation in human umbilical vein endothelial cells (HUVECs) were affected by normal-, OA-, RA-SFB derived exosomes. Migration assay was evaluated using HUVECs in a modified Boyden chamber. In the tube formation assay, HUVECs were seeded into plates coated with growth-factor-reduced Matrigel and tube length was measured. miRNA profiles in the exosome preparations were established using 3D-Gene miRNA microarray. Results: Migration and tube formation activity were significantly higher in endothelial cells treated with exosomes from OA and RA SFB as compared to exosomes from normal SFB. IL-1b stimulation of SFB enhanced the angiogenic activity in their exosomes. However, migration and tube formation were not induced in endothelial cells by cytokine IL-1b alone. miRNA array data showed that 349 miRNAs were changed in OA SFB exosomes as compared to normal SFB expsomes. OA-and RA-SFB exosomes shared 29 miRNAs that were up-regulated and 35 miRNAs that were down-regulated compared normal SFB exosomes. This includes several differentially expressed angiogenesis-related miRNAs. Conclusions: Exosomes from OA SFB accelerate angiogenic activity in HUVECs, and might be involved in OA development by promoting angiogenesis throughout the joint. miRNA array data suggest an OA-related miRNA profile in exosomes that may serve as a novel biomarker. These results support our hypothesis that exosomes containing miRNAs function in a novel regulatory network that contributes to various aspects of OA pathogenesis.

Stimulation of Fibrotic Processes by the Infrapatellar Fat Pad in Cultured Synoviocytes From Patients With Osteoarthritis: A Possible Role for Prostaglandin F2α

“…OA is a disease of the articular joints in which synovial fibrosis is often seen (). Accumulating data have been presented to suggest that OA is an inflammatory disease in which cytokines and immune cells play a role ().…”

“…These hydroxyallysine collagen crosslinks are found in fibrotic tissues and are associated with irreversible accumulation of collagen (). Recently, it was demonstrated that PLOD2 expression and the presence of LH2b are up‐regulated in the fibrotic synovium of mice with OA ().…”

“…TGFβ is a potent inducer of PLOD2 expression and LH2b activity (), making TGFβ a very potent fibrotic growth factor involved in all of the processes seen in fibrosis. In addition to TGFβ, prostaglandin F 2α (PGF 2α ) was recently discovered as a cytokine that facilitates pulmonary fibrosis independent of TGFβ.…”

The effects of three‐month oral supplementation with a nutraceutical and exercise on the locomotor pattern of aged horses

“…As alluded to earlier, stiffness may also be related, at least partially, to age‐related changes in material properties. It has been shown, both in man and horses, that in articular tissues certain cross‐links that for example are products of the so‐called nonenzymatic glycation process, such as pentosidine, or pyridinoline cross‐links, increase linearly with age once growth has ceased . These cross‐links would increase cartilage and soft tissue stiffness.…”

High-Resolution Dissection of Chemical Reprogramming from Mouse Embryonic Fibroblasts into Fibrocartilaginous Cells

“…We suggest that these results are attributed to the 3D self-organized organoids maintaining a more chondrocyte-like phenotype compared with cells derived from 2D dish cultures ( Figure 2). Formation of fibrous tissue is the principal cause of joint pain and functional loss (Remst et al, 2013).…”