Interleukin‑1β‑mediated suppression of microRNA‑27a‑3p activity in human cartilage via MAPK and NF‑κB pathways: A potential mechanism of osteoarthritis pathogenesis.

The aim of the present study was to investigate the role of microRNA (miR)‑27a‑3p in osteoarthritis (OA). Reverse transcription‑quantitative polymerase chain reaction and western blotting were performed to determine the expression of miR‑27a‑3p and aggrecanase‑2 (ADAMTS5) in cartilage tissues from patients with OA and healthy controls, and also in interleukin (IL)‑1β‑treated primary human chondrocytes. Primary human chondrocytes were transfected with miR‑27a‑3p. A luciferase reporter assay was used to validate the direct contact between miR‑27a‑3p and its putative binding site in the 3'‑untranslated region ADAMTS5 mRNA. Furthermore, the effects of IL‑1β‑induced activation of mitogen‑activated protein kinase (MAPK) and nuclear factor (NF)‑κB on miR‑27a‑3p were evaluated using specific inhibitors. The results revealed that the level of miR‑27a‑3p was reduced in OA cartilage tissues compared with those of normal controls. In addition, decreased miR‑27a‑3p and increased ADAMTS5 expression was observed in a time‑ and dose‑dependent manner in chondrocytes treated with IL‑1β. Furthermore, overexpression of miR‑27a‑3p suppressed the expression of ADAMTS5 in human chondrocytes induced by IL‑1β. miR‑27a‑3p overexpression also decreased the luciferase activity of the wild‑type ADAMTS5 reporter plasmid. Mutation of the miR‑27a‑3p binding site in the 3'‑untranslated region of ADAMTS5 mRNA abolished the miR‑27a‑3p‑mediated repression of reporter activity. Furthermore, the use of specific inhibitors demonstrated that IL‑1β may regulate miR‑27a‑3p expression via NF‑κB and MAPK signaling pathways in chondrocytes. The present study concluded that miR‑27a‑3p was downregulated in human OA and was suppressed by IL‑1β, and functions as a crucial regulator of ADAMTS5 in OA chondrocytes. In addition, IL‑1β‑mediated suppression of miR‑27a‑3p activity may occur via the MAPK and NF‑κB pathways. The present study may provide a novel strategy for clinical treatment of OA caused by upregulation of miR‑27a‑3p.