NADPH Oxidase versus Mitochondria-Derived ROS in Glucose-Induced Apoptosis of Pericytes in Early Diabetic Retinopathy

Area of Science:

• Biochemistry
• Cell Biology
• Diabetic Complications

Background:

• Diabetic retinopathy involves pericyte apoptosis, a process potentially linked to oxidative stress.
• Reactive oxygen species (ROS) generated by NADPH oxidase and mitochondria are implicated in cellular damage.

Purpose of the Study:

• To investigate whether NADPH oxidase or mitochondria are the primary source of ROS causing high glucose-induced pericyte apoptosis.
• To evaluate the therapeutic potential of targeting NADPH oxidase versus mitochondria in this context.

Main Methods:

• Pericyte apoptosis was induced by high glucose (25 mM) and measured via caspase-3 activity.
• NADPH oxidase localization was confirmed using Western blot and cytochrome C reduction assays.
• ROS production, intracellular glucose, and Nepsilon-(carboxymethyl) lysine (CML) levels were quantified.
• Apocynin (NADPH oxidase inhibitor) and Mitoquinol 10 nitrate (MitoQ; mitochondrial antioxidant) were used to assess ROS source.

Main Results:

• High glucose significantly increased pericyte apoptosis, intracellular glucose, and CML formation.
• Apoptosis correlated with increased gp91phox expression, NADPH oxidase activity, and ROS production.
• Apocynin treatment significantly reduced ROS generation, CML formation, and apoptosis.
• MitoQ did not significantly affect these parameters, indicating mitochondria were not the primary ROS source.

Conclusions:

• NADPH oxidase-derived ROS, not mitochondrial ROS, are the key drivers of high glucose-induced pericyte apoptosis.
• Targeting NADPH oxidase may be a viable therapeutic strategy for diabetic retinopathy.