MicroRNA-27a protects retinal pigment epithelial cells under high glucose conditions by targeting TLR4.

The present study aimed to investigate whether microRNA-27a (miRNA27a) is associated with the pathogenesis of diabetic retinopathy, and to elucidate the underlying molecular mechanism of any potential association. In retinal pigment epithelial (RPE) cells treated with high glucose, miRNA27a expression, determined by reverse transcription-quantitative polymerase chain reaction analysis, was decreased. Caspase-3/9 activity and B-cell lymphoma 2-associated X (Bax) protein expression was increased in RPE cells subjected to high glucose. Inhibition of miRNA27a suppressed the viability, and increased the caspase-3/9 activity and Bax protein expression of RPE cells treated with high glucose. Inhibition of miRNA27a expression also increased the expression of interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α and Toll-like receptor 4 (TLR4) in RPE cells treated with high glucose. Treatment with immunostimulatory (is)RNA directed against TLR4 was observed to inhibit caspase-3/9 activity, decrease the expression of TLR4, Bax, IL-6, IL-1β and TNF-α, and increase the viability of RPE cells subjected to high glucose following the inhibition miRNA27a. In conclusion, the results of the present study suggest that miRNA27a protects RPE cells subjected to high glucose via inhibiting inflammation and apoptosis through targeting TLR4.