Related Experiment Video
Updated: Apr 29, 2026
Characterization of a Novel Human Organotypic Retinal Culture Technique
Published on: June 9, 2021
Regulation of retinal inflammation by rhythmic expression of MiR-146a in diabetic retina
Qi Wang1, Svetlana N Bozack1, Yuanqing Yan2
1Department of Physiology, Michigan State University, East Lansing, Michigan, United States.
Purpose:
Chronic inflammation and dysregulation of circadian rhythmicity are involved in the pathogenesis of diabetic retinopathy. MicroRNAs (miRNAs) can regulate inflammation and circadian clock machinery. We tested the hypothesis that altered daily rhythm of miR-146a expression in diabetes contributes to retinal inflammation.
Methods:
Nondiabetic and STZ-induced diabetic rats kept in 12/12 light/dark cycle were killed every 2 hours over a 72-hour period. Human retinal endothelial cells (HRECs) were synchronized with dexamethasone. Expression of miR-146a, IL-1 receptor-associated kinase 1 (IRAK1), IL-1β, VEGF and ICAM-1, as well as clock genes was examined by real-time PCR and Western blot. To modulate expression levels of miR-146a, mimics and inhibitors were used.
Results:
Diabetes inhibited amplitude of negative arm (per1) and enhanced amplitude of the positive arm (bmal1) of clock machinery in retina. In addition to clock genes, miR-146a and its target gene IRAK1 also exhibited daily oscillations in antiphase; however, these patterns were lost in diabetic retina. This loss of rhythmic pattern was associated with an increase in ICAM-1, IL-β, and VEGF expression. Human retinal endothelial cells had robust miR-146a expression that followed circadian oscillation pattern; however, HRECs isolated from diabetic donors had reduced miR-146a amplitude but increased amplitude of IRAK1 and ICAM-1. In HRECs, miR-146a mimic or inhibitor caused 1.6- and 1.7-fold decrease or 1.5- and 1.6-fold increase, respectively, in mRNA and protein expression levels of ICAM-1 after 48 hours.
Conclusions:
Diabetes-induced dysregulation of daily rhythms of miR-146a and inflammatory pathways under miR-146a control have potential implications for the development of diabetic retinopathy.
Insights
Altered daily rhythms of microRNA-146a (miR-146a) in diabetes disrupt retinal inflammation control. Restoring miR-146a rhythm may offer new treatments for diabetic retinopathy.
Area of Science:
- Ophthalmology
- Molecular Biology
- Chronobiology
Background:
- Diabetic retinopathy (DR) pathogenesis involves chronic inflammation and disrupted circadian rhythms.
- MicroRNAs (miRNAs) regulate both inflammation and circadian clock genes.
- The role of miR-146a daily expression patterns in DR remains unclear.
Purpose of the Study:
- To investigate the hypothesis that altered daily rhythms of miR-146a expression in diabetes contribute to retinal inflammation.
- To examine the impact of diabetes on the circadian expression of miR-146a and its associated inflammatory pathways in the retina.
Main Methods:
- Studied nondiabetic and diabetic rats over 72 hours under a 12/12 light/dark cycle, collecting samples every 2 hours.
- Analyzed expression of miR-146a, IRAK1, IL-1β, VEGF, ICAM-1, and clock genes using real-time PCR and Western blot.
- Utilized miR-146a mimics and inhibitors in human retinal endothelial cells (HRECs) to modulate expression.
Main Results:
- Diabetes disrupted retinal clock gene rhythms and abolished the antiphase daily oscillations of miR-146a and its target IRAK1.
- Loss of miR-146a rhythmicity correlated with increased retinal ICAM-1, IL-1β, and VEGF.
- In diabetic HRECs, reduced miR-146a amplitude and increased IRAK1/ICAM-1 were observed; miR-146a modulation affected ICAM-1 levels.
Conclusions:
- Diabetes-induced dysregulation of miR-146a daily rhythms contributes to retinal inflammation.
- These findings suggest that targeting miR-146a circadian pathways may offer therapeutic strategies for diabetic retinopathy.
