RESUMEN
Context: Osteoarthritis (OA) is a chronic joint disease that can eventually lead to degeneration, fibrosis, fractures, and defects of the articular cartilage. Long non-coding RNA (lncRNA) is a key substance in many processes, such as epigenetic regulation and cell-cycle and cell-differentiation modulation, and its relationship with OA has been repeatedly verified. Objective: The study intended to clarify the influence of lncRNA nuclear enriched abundant transcript 1 (NEAT1), lncRNA NEAT1, on lipopolysaccharide (LPS)-induced OA chondrocytes through sponge adsorption of microRNA-378 (miR-378) and to provide novel insights into future diagnosis and treatment of OA. Design: The research team performed an animal study. Setting: The study took place in the Department of Rehabilitation Medicine at Linyi People's Hospital in Linyi, Shangdong, China. Animals: The study's animals were 10 Sprague Dawley (SD) rats, 3-5 days old and 10-15 g in weight, of the specific-pathogen-free (SPF) grade. Intervention: The rat chondrocytes for the positive control group (the model group) were treated with 500 ng/mL of LPS to induce OA. Chondrocytes treated with the same amount of normal saline were used as the negative control group. The chondrocytes of the LPS-induced rats were into six groups: (1) a positive control group transfected with NEAT1-interfering RNA, the sh-NEAT1 group; (2) a negative control group not transfected with NEAT1-interfering RNA, the NEAT1 empty vector (NC-NEAT1) group; (3) an intervention group co-transfected with NEAT1 interfering RNA and the miR-378 inhibitor sequence (Inh-miR-378 the sh-NEAT1+ Inh-miR-378 group; (4) a negative control group transfected with NEAT1 interfering RNA but not transfected with the miR-378 inhibitor sequence, the sh-NEAT1+ miR-378 negative control (NC-miR-378) group; (5) a negative control group transfected with the miR-378 inhibitor sequence but not transfected with NEAT1 interfering RNA, the NEAT1 empty vector (NC-NEAT1) + Inh-miR-378 group; (6) a negative control group not transfected with either NEAT1 interfering RNA or the miR-378 inhibitor sequence, the NC-NEAT1 + NC-miR-378 group. Outcome Measures: An OA-chondrocyte model was induced by LPS and measurements of NEAT1 and miR-378 expression were made by real-time quantitative reverse transcription (qRT)- polymerase chain reaction (PCR). Then, small NEAT1-interfering RNA (sh-NEAT1), empty vector NEAT1 (NC-NEAT1), inhibitor-sequence-miR-378 (Inh-miR-378), and negative-control-miR-378 (NC-miR-378) were transfected into cells, and cell viability and apoptosis rate were measured. Finally, the study verified the relationship between NEAT1 and miR-378. Results: Compared to the control group, NEAT1 was significantly elevated in the model group, and its miR-378 was significantly decreased. Silencing NEAT1 can enhance OA-chondrocyte activity and decrease apoptosis. When NEAT1 and miR-378 were inhibited together, as shown fort the NC-NEAT1 + NC-miR-378 group, NEAT1 expression, as well as the multiplication and apoptosis ability of the OA-model cells, were the same as those of cells transfected with an empty vector, the NC-NEAT1 group. Also, the NEAT1 + NC-miR-378 group's cell activity was lower than that of the sh-NEAT1+NC-miR-378 group but higher than that of the NC-NEAT1 + Inh-miR-378 group. Finally, higher fluorescence activity occurred for NEAT1-mutant type (MUT) transfected with Inh-miR-378. Conclusions: NEAT1, which is highly expressed in OA, mediates LPS-induced OA-chondrocyte activity through sponge adsorption of miR-378.