Cell Apoptosis Of Chondrocytes Research Articles

LncRNA CALML3-AS1 regulates chondrocyte apoptosis by acting as a sponge for miR-146a

Chondrocyte apoptosis contributes to osteoarthritis, while miR-146a is a critical player in chondrocyte apoptosis. Our bioinformatics analysis showed that miR-146a may bind with long non-coding RNA (lncRNA) CALML3 antisense RNA 1 (CALML3-AS1). Our study was therefore carried out to investigate the interactions between lncRNA CALML3-AS1 and miR-146a in osteoarthritis. This study included 66 osteoarthritis patients who were admitted at Shanxi People’s Hospital from July 2016 to June 2019. Transfections were performed to analyse gene interactions. RT-qPCR and Western blot were performed to determine the expression levels of gene and protein, respectively. Cell apoptosis of chondrocytes induced by lipopolysaccharide (LPS) was analysed by cell apoptosis assay. We found that CALML3-AS1 was downregulated, while miR-146a was upregulated in osteoarthritis. However, no significant correlation was found between them. In addition, overexpression of CALML3-AS1 or miR-146a did not affect the expression of each other. However, overexpression of CALML3-AS1 resulted in the upregulation of Smad family member 4 (Smad4), a downstream target of miR-146a. We also found that the expression of miR-146a and Smad4 were negatively correlated, while the correlation between CALML3-AS1 and smad4 was not significant. In cell apoptosis assay, overexpression of CALML3-AS1 and Smad4 resulted in decreased proliferation of chondrocytes. MiR-146a played an opposite role and reduced the effects of overexpression of CALML3-AS1 and Smad4. Therefore, CALML3-AS1 may regulate chondrocyte apoptosis by acting as a sponge for miR-146a to upregulate Smad4.

Tanshinone IIA Ameliorates Inflammation Response in Osteoarthritis via Inhibition of miR-155/FOXO3 Axis

Background: Osteoarthritis (OA) is the most common joint disorder characterized by degeneration of the articular cartilage and joint destruction with an associated risk of mobility disability in elderly people. Although a lot of achievements have been made, OA is still regarded as an incurable disease. Therefore, the pathological mechanisms and novel therapeutic strategies of OA need more investigation. Methods: MTT assay was conducted to measure the viability of chondrocytes after LPS treatment. Cell apoptosis was analyzed by annexin V/propidium iodide labeling. ELISA was used to determine the concentrations of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in the culture supernatant of chondrocytes. The expression level of miR-155, IL-1β, FOXO3, TNF-α, IL-6, caspase-3, and caspase-9 in chondrocytes was analyzed by RT-qPCR or Western blot. Results: We found that LPS led to inflammatory responses, cell apoptosis, and increased miR-155 expression in human articular chondrocytes. Tanshinone IIA could inhibit LPS-induced inflammation and cell apoptosis of chondrocytes via regulating the expression of miR-155 and FOXO3. miR-155 directly targeted the 3′-UTR of FOXO3 to regulate its expression. Conclusions: Taken together, our data suggest tanshinone IIA ameliorates inflammation response in OA via inhibition of the miR-155/FOXO3 axis, and provide some evidences that tanshinone IIA could be designed and developed as a new promising clinical therapeutic drug for OA patients.

Notch1-ADAM8 positive feed-back loop regulates the degradation of chondrogenic extracellular matrix and osteoarthritis progression

BackgroundOsteoarthritis (OA) is one of the most prevalent joint disease, and there are still no effective therapeutic agents or clinical methods for the cure of this disease to date. The degradation of cartilage extracellular matrix (ECM) is a major cause of OA.MethodIL-1β was used to induce chondrogenic degradation. Q-PCR and Western blotting were used to detect mRNA and protein level, respectively. ELISA was used to detect the secreted TNF-α and IL-6 level. Immunofluorescence was used to detect the protein level of Aggrecan, Collagen II and ki67. TUNEL and flow cytometry were used to examine cell apoptosis of chondrocytes. ChIP and luciferase assay were used to study molecular gene regulation. Osteoarthritic animal model and Safranin-O staining were used to determine the in vivo OA phenotype.ResultsThe expression of ADAM8 was up-regulated in osteoarthritic chondrocytes. Knockdown of ADAM8 suppressed the OA phenotype in the in vitro OA cell model. ADAM8 regulated OA progression through the activation of EGFR/ERK/NF-κB signaling pathway. Inhibition of Notch signaling suppressed OA phenotype in the in vitro OA cell model. Notch signaling regulated the gene expression of ADAM8 directly via Hes1. Notch1-ADAM8 positive feedback loop promoted the progression of OA in vivo.ConclusionNotch1-ADAM8 feed-back loop regulates the degradation of chondrogenic extracellular matrix and osteoarthritis progression.

Astragaloside IV protects against apoptosis in human degenerative chondrocytes through autophagy activation.

Increased cell apoptosis in chondrocytes is a feature of degenerative cartilage. Astragaloside IV (AST) has been proven to possess an antiarthritic effect by preventing interleukin (IL)-1β-induced cartilage damage. However, the role of AST on chondrocyte apoptosis and its underlying mechanism remains unknown. In the present study, degenerative chondrocytes isolated from patients with osteoarthritis (OA) were subjected to AST and IL-1β treatment. Results indicated that AST protected against chondrocyte apoptosis induced by IL-1β. Western blotting indicated that AST increased the protein expression of LC3-II/I and decreased P62/SQSTM1 expression, which suggested that AST upregulated autophagy activity in chondrocytes. Fluorescent protein GFP-LC3 analysis and transmission electron microscopy observation confirmed that autophagy was promoted by AST. In contrast, after autophagy inhibited by 3-methyladenine, chondrocyte apoptosis was further increased under IL-1β treatment. Ultimately, rapamycin was used as a positive control, whose results confirmed that rapamycin-mediated autophagy also decreased chondrocyte apoptosis induced by IL-1β. In conclusion, these results suggested that AST-mediated autophagy serves an anti-apoptotic role in chondrocytes, which may aid the development of novel therapeutic approaches for OA treatment.

MiR-210 inhibits NF-κB signaling pathway by targeting DR6 in osteoarthritis.

Osteoarthritis (OA) is characterized by degradation of articular cartilage and joint inflammation. MicroRNAs have been proved to play an important role in the regulation of chondrogenesis. Previous study showed that microRNA-210 (miR-210) was probably associated with osteoarthritis, while the function of miR-210 in osteoarthritis still remains unknown. The aim of the present study was to investigate the protective effect of miR-210 on osteoarthritis. In the in vitro study, miR-210 level in chondrocytes was decreased after treatment with lipopolysaccharide (LPS). Transfection with miR-210 mimic inhibited LPS-induced pro-inflammatory cytokines production, cell viability reduction and cell apoptosis. Results of luciferase activity assay showed that miR-210 targeted 3′-UTR of death receptor 6 (DR6) to inhibit its expression. MiR-210 mimic and DR6 siRNA transfection inhibited the activation of NF-κB pathway and cell apoptosis of chondrocytes. For the in vivo study, OA model was established on rats by anterior cruciate ligament transection (ACLT). MiR-210 expression is reduced in OA rats. MiR-210 over-expressing lentivirus was injected into the OA rats. Cytokines production, and NF-κB and DR6 expression in OA rats was inhibited by miR-210 overexpression. The results demonstrated that miR-210 decreased inflammation in articular cavity in OA rats by targeting DR6 and inhibiting NF-κB signaling pathway.