Extracellular vesicles enriched in connexin 43 promote a senescent phenotype in bone and synovial cells contributing to osteoarthritis progression

Abstract

The accumulation of senescent cells is a key characteristic of aging, leading to the progression of age-related diseases such as osteoarthritis (OA). Previous data from our laboratory has demonstrated that high levels of the transmembrane protein connexin 43 (Cx43) are associated with a senescent phenotype in chondrocytes from osteoarthritic cartilage. OA has been reclassified as a musculoskeletal disease characterized by the breakdown of the articular cartilage affecting the whole joint, subchondral bone, synovium, ligaments, tendons and muscles. However, the mechanisms that contribute to the spread of pathogenic factors throughout the joint tissues are still unknown. Here, we show for the first time that small extracellular vesicles (sEVs) released by human OA-derived chondrocytes contain high levels of Cx43 and induce a senescent phenotype in targeted chondrocytes, synovial and bone cells contributing to the formation of an inflammatory and degenerative joint environment by the secretion of senescence-associated secretory associated phenotype (SASP) molecules, including IL-1ß and IL-6 and MMPs. The enrichment of Cx43 changes the protein profile and activity of the secreted sEVs. Our results indicate a dual role for sEVs containing Cx43 inducing senescence and activating cellular plasticity in target cells mediated by NF-kß and the extracellular signal-regulated kinase 1/2 (ERK1/2), inducing epithelial-to-mesenchymal transition (EMT) signalling programme and contributing to the loss of the fully differentiated phenotype. Our results demonstrated that Cx43-sEVs released by OA-derived chondrocytes spread senescence, inflammation and reprogramming factors involved in wound healing failure to neighbouring tissues, contributing to the progression of the disease among cartilage, synovium, and bone and probably from one joint to another. These results highlight the importance for future studies to consider sEVs positive for Cx43 as a new biomarker of disease progression and new target to treat OA.

Excessive sulfur oxidation in endoplasmic reticulum drives an inflammatory reaction of chondrocytes in aging mice

“…At present, there are many studies on aging and osteoarthritis, ranging from the RNA level to the protein level. Based on existing studies (Liu et al, 2021), (Miura et al, 2022) , (Varela-Eirín et al, 2022), this study found that with the increase of age, the number of aging cells in articular cartilage increased, which promoted the occurrence of inflammatory aging-related secretory phenotype (SASP), and then led to an increase in the expression of inflammatory response-related genes and proteins. At the same time, it has been reported that osteoarthritis is related to bone metabolism.…”

Implication of Cellular Senescence in Osteoarthritis: A Study on Equine Synovial Fluid Mesenchymal Stromal Cells

“…Cellular senescence is characterized by a stable exit of the cell cycle and loss of replicative capacity, even in the presence of mitogenic stimuli [ 7 , 37 ]. Furthermore, the ability of these cells to secrete SASP components [ 9 ], which enhance the surrounding inflammatory microenvironment helpful for the OA progression [ 38 ], indicates that sf-MSCs are not quiescent cells but metabolically active [ 19 ]. Our findings regarding the proliferation activity of OA sf-MSCs and ROS production, agree with a state of cellular senescence.…”

Breakthrough of extracellular vesicles in pathogenesis, diagnosis and treatment of osteoarthritis

“…The researchers also found that sEVs secreted by OA-derived chondrocytes were enriched in transmembrane connexin 43 (Cx43). These sEVs can secrete SASP to promote inflammatory progression and can regulate cell senescence through NF-κB and ERK1/2 [ 49 ]. This series of studies shows that EVs from SnCs have a direct negative regulatory effect on inflammation, and the main mechanism might be through inflammation-related miRNAs.…”