Reduced miR-519d-3p levels in the synovium and synovial fluid facilitate the progression of post-traumatic osteoarthritis by targeting VEGF

Senescence-regulatory factors as novel circulating biomarkers and therapeutic targets in regenerative medicine for osteoarthritis

Recent discoveries reveal that the chronic presence of senescent cells in osteoarticular tissues provides a focal point of disease development for osteoarthritis (OA). Nevertheless, senescence-regulatory factors associated with OA still need to be identified. Furthermore, few diagnostic- and prognostic-validated biochemical markers (biomarkers) are currently used in clinics to evaluate OA patients. In the future, alongside imaging and clinical examination, detecting senescence-regulatory biomarkers in patient fluids could become a prospective method for disease: diagnosis, monitoring, progression and prognosis following treatment. This review summarizes a group of circulating OA biomarkers recently linked to senescence onset. Remarkably, these factors identified in proteomics, metabolomic and microRNA studies could also have deleterious or protective roles in osteoarticular tissue homeostasis. In addition, we discuss their potentially innovative modulation in combination with senotherapeutic approaches, for long-lasting OA treatment.

TGF-β1 regulates chondrocyte proliferation and extracellular matrix synthesis via circPhf21a-Vegfa axis in osteoarthritis

Background

The transforming growth factor-beta (TGF-β) signaling pathway is an important pathway associated with the pathogenesis of osteoarthritis (OA). This study was to investigate the involvement of circRNAs in the TGF-β signaling pathway.

Methods

Cell Counting Kit-8 (CCK-8) assay and 5-ethynyl-2′-deoxyuridine (EdU) assay were used to detect the proliferation of primary mouse chondrocytes (PMCs). RNA-sequencing together with bioinformatics analysis were used to systematically clarify TGF-β1 induced alternations of circRNAs in PMCs. The regulatory and functional role of circPhf21a was examined in PMCs. Downstream targets of circPhf21a were explored by RNA-sequencing after overexpression of circPhf21a and verified by RT-qPCR in PMCs. Finally, the role and mechanism of circPhf21a in OA were explored in mouse models.

Results

We found that TGF-β1 promoted the proliferation of PMCs. Meanwhile, RT-qPCR and western blotting indicated that TGF-β1 promoted extracellular matrix (ECM) anabolism. RNA-sequencing revealed that a total of 36 circRNAs were differentially expressed between PMCs treated with and without TGF-β1. Of these, circPhf21a was significantly decreased by TGF-β1. Furthermore, circPhf21a knockdown promoted the proliferation and ECM synthesis of PMCs, whereas overexpression of circPhf21a showed the opposite effects. Mechanically, the expression profiles of the mRNAs revealed that Vegfa may be the target of circPhf21a. Additionally, we found that circPhf21a was significantly upregulated in the mouse OA model, and inhibition of circPhf21a significantly relieved the progression of OA.

Conclusions

Our results found that TGF-β1 promoted the proliferation and ECM synthesis of PMCs via the circPhf21a-Vegfa axis, which may provide novel therapeutic targets for OA treatment.