Circ_0022383 alleviates IL-1β-induced apoptosis, inflammation and extracellular matrix degeneration in osteoarthritis cell model by miR-3619-5p/SIRT1 axis.

BACKGROUND

Circular RNAs (circRNAs) have been identified to play roles in cartilage homeostasis and chondrocyte development, and be associated with osteoarthritis (OA) pathophysiology. Here, we aimed to investigate the role and mechanism of circ_0022383 on OA progression.

METHODS

Chondrocytes in functional groups were treated with interleukin (IL)-1β. The levels of genes and proteins were assayed by qRT-PCR and western blotting. Cell proliferation and apoptosis were evaluated by cell counting kit-8 assay, 5-Ethynyl-2'-deoxyuridine (Edu) assay, and flow cytometry, respectively. The inflammation and extracellular matrix (ECM) degeneration were determined by assessing the activity of IL-6, tumor necrosis factor (TNF-α), Aggrecan (ACAN), collagen type II α 1 chain (COL2A1) and ADAMTS5 proteins. The binding between miR-3619-5p and circ_0022383 or silent information regulator 1 (SIRT1) was confirmed by dual-luciferase reporter, RIP and RNA pull-down assays.

RESULTS

Circ_0022383 expression was lower in the cartilages of OA patients and IL-1β-induced primary chondrocytes. Functionally, ectopic overexpression of circ_0022383 alleviated IL-1β-induced proliferation arrest, apoptosis, the release of IL-6 and TNF-α, as well as the decrease of ACAN and COL2A1 and the increase of ADAMTS5 level in chondrocytes. Mechanistically, circ_0022383 acted as a sponge for miR-3619-5p, which was verified to target SIRT1. Rescue experiments showed that miR-3619-5p up-regulation reversed the protective effects of circ_0022383 on IL-1β-stimulated chondrocytes. Additionally, miR-3619-5p inhibition abolished IL-1β-induced apoptosis, inflammation and ECM degeneration in chondrocytes, which were counteracted by SIRT1 silencing.

CONCLUSION

Circ_0022383 protected chondrocytes from IL-1β-induced apoptosis, inflammation and ECM degeneration by miR-3619-5p/SIRT1 axis, inspiring future therapy development for OA prevention.