Methylene Blue Attenuates Diabetic Retinopathy by Inhibiting NLRP3 Inflammasome Activation in STZ-Induced Diabetic Rats

ABSTRACT

Purpose: This study aimed to investigate the regulatory effects of methylene blue (MB) on diabetic retinopathy (DR) and explored the molecular mechanisms of MB as a retina protection agent.

Methods: The thicknesses of retinal layers and permeability of the blood–retinal barrier (BRB) were measured by histology analysis, and the expression levels of NLRP3, ASC, procaspase-1, caspase-1, IL-1β, and IL-18 were measured by western blotting. Lentivirus-based knockdown of NLRP3 gene was used to confirm the role of NLRP3 inflammasome.

Results: MB treatment attenuates DR supported by the increase of relative thicknesses of retinal layers and the reduction of BRB permeability when compared with the untreated diabetic group. Further, MB significantly downregulated the levels of all detected inflammation mediators and showed inhibition on NLRP3 inflammasome activation similar to NLRP3 gene silencing.

Conclusions: This study revealed a novel mechanism underlying the protection role of MB in the pathogenesis of DR.

Keywords:

• Diabetes mellitus
• diabetic retinopathy
• methylene blue
• NLRP3 inflammasome
• streptozotocin-induced diabetic model

Declaration of Interest

The authors report no conflicts of interest. The authors alone are responsible for the content and preparation of this manuscript.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.