Abstract
Purpose :
A growing body of evidence shows that microRNA (miRNA) play important roles in pathological mechanisms involved in diabetic retinopathy, as well as possessing great potential as novel therapeutic targets. Pathological mechanisms underlying diabetic retinopathy are not fully understood. The purpose of our study was to test the hypothesis that miR-146a plays a key role in attenuating hyperglycemia-induced inflammatory pathways through a reduction in TLR4/NF-κB and TNF alpha signaling in primary human retinal microvascular endothelial cells (REC).
Methods :
Human REC were maintained in normal (5mM) glucose or transferred to high glucose medium (25 mM) for 3 days. REC were transfected with miRNA mimics (hsa-miR-146a-5p) 48 hours before cell harvest. A final concentration of 50 nM was used. A negative control group was treated with an equal concentration of a Mimic Negative Control and cultured in high glucose. miRNA overexpression was verified using quantitative reverse transcription–polymerase chain reaction and real-time PCR. Western blot analyses were performed to measure the levels of TLR4, MyD88, TRAF6, IRAK1, TRIF, IRF3, and NF-κB. In addition, ELISA was used to examine TNF alpha levels. Analyses were done using unpaired Student t test. Data are presented as mean±SEM.
Results :
We demonstrated that miR-146a expression was decreased in human REC cultured in hyperglycemia. Overexpression of miR-146a using mimics significantly reduced the levels of TLR4/NF-κB and TNF alpha signaling in hyperglycemia. Both MyD88-dependent and –independent pathways were inhibited by miR-146a overexpression in hyperglycemia.
Conclusions :
Hyperglycemia induced the decrease of miR-146a expression in REC. Elevation of miR-146a levels inhibited TLR4/NF-κB and TNF alpha signaling in hyperglycemia. The results suggest that miR-146a is a potential therapeutic target for reducing inflammation in the diabetic retina through inhibition of TLR4/NF-κB and TNF alpha signaling. Our study will contribute to understanding on diabetic retinal pathology, as well as providing important clues to develop therapeutics for clinical applications.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.