Abstract

Background: Microvascular dysfunction is a hallmark of diabetic retinopathy (DR), which may lead to visual impairment and blindness. Procyanidin B2 (PB2) is a subclass of flavonoids and is widely known due to its anti-oxidant and antiinflammatory effects. However, little is known about the effect of PB2 on hyperglycemia stress-induced retinal microvascular dysfunction.

Objective: The purpose of this study was to investigate the effect of PB2 against hyperglycemia stress in rat retinal capillary endothelial cells (TR-iBRB2) as well as the underpinning mechanism.

Methods: Cell viability was determined using MTT assay. ROS, NOX activity analysis, Western blot analysis, and immunofluorescence analysis were applied in the study.

Results: The results showed that PB2 pre-treatment significantly reduced high glucose- induced cytotoxicity in TR-iBRB2 cells by suppressing oxidative stress and inflammasome activation. Mechanistical study revealed that redoxosomes were formed and activated in TR-iBRB2 cells upon hyperglycemia stress, resulting in activation of NF- κB and thus induction of oxidative stress and inflammasomes activation. However, PB2 pre-treatment dose-dependently attenuated the above events, indicating the protective effect of PB2 against hyperglycemia stress was achieved by regulating redoxosomes/ NF-kB signaling.

Conclusion: Our findings may contribute to the potential clinical use of PB2 in treating DR and suggest redoxosomes/NF-kB signaling may be a potential therapeutic target of this disease.

Keywords: Diabetic retinopathy, microvascular dysfunction, procyanidin B2, redoxosomes/NF-kB signaling, procyanidin B2 (PB2), diabetes mellitus (DM).