CircSCAPER knockdown attenuates IL-1β-induced chondrocyte injury by miR-127-5p/TLR4 axis in osteoarthritis

Abstract

Purpose

Osteoarthritis (OA) is a chronic inflammatory degenerative disease characterized by articular cartilage degradation. Circular RNAs have been shown to play significant roles in OA process. Herein, this work aimed to investigate the potential role and mechanism of circSCAPER in OA progression.

Methods

Levels of circSCAPER, miR-127-5p and toll-like receptor 4 (TLR4) were detected by qRT-PCR or western blotting. Cell apoptosis was determined by flow cytometry. The expression of Aggrecan and Matrix metallopeptidase was examined using western blot to assess extracellular matrix (ECM) degradation. Inflammatory response and oxidative stress were determined by measuring the release of inflammatory factors, along with the generation of intracellular reactive oxygen species and malondialdehyde. The interaction between miR-127-5p and circSCAPER or TLR4 was determined by dual-luciferase reporter, RNA immunoprecipitation and pull-down assays.

Results

Chondrocytes were treated with interleukin-1β (IL-1β) to mimic OA condition in vitro. CircSCAPER was increased in OA cartilages and IL-1β-induced chondrocytes. Functionally, knockdown of circSCAPER attenuated IL-1β-evoked apoptosis, ECM degradation, inflammation and oxidative stress in vitro. CircSCAPER up-regulation in OA cartilages was discovered to be accompanied by decreased miR-127-5p and increased TLR4. Mechanistically, circSCAPER acted as a sponge for miR-127-5p to positively regulate TLR4 expression in chondrocytes. IL-1β treatment reduced miR-127-5p expression but up-regulated TLR4 expression, re-expression of miR-127-5p suppressed IL-1β-caused chondrocyte injury, which was abolished by TLR4 overexpression. Moreover, miR-127-5p inhibition reversed the protective action of circSCAPER knockdown on chondrocytes under IL-1β treatment.

Conclusion

CircSCAPER silencing protected against IL-1β-induced apoptosis, ECM degradation, inflammation and oxidative stress in chondrocytes via miR-127-5p/TLR4 axis.

Keywords:

• circSCAPER
• miR-127-5p
• TLR4
• chondrocyte
• osteoarthritis
• extracellular matrix

Authors’ contribution

Conceptualization and Methodology: Ping Zhao and Sen Li; Formal analysis and Data curation: Xiangqian Mu and Huaqi Wang; Validation and Investigation: Yuchang Zhang and Sen Li; Writing – original draft preparation and Writing – review and editing: Yuchang Zhang, Ping Zhao and Xiangqian Mu.

Ethics approval and consent to participate

This study was approved by the Ethics Committee of Gansu Provincial Hospital of Traditional Chinese Medicine (Gansu China.).

Availability of data and materials

The datasets used and analysed during this study are available from the corresponding author on reasonable request.

Disclosure statement

The authors have no conflict of interest to declare.

Funding

The author(s) reported there is no funding associated with the work featured in this article.