Tilianin Protects Diabetic Retina through the Modulation of Nrf2/TXNIP/NLRP3 Inflammasome Pathways

Oxidative stress and inflammation are regarded as prime reasons for the progression and development of diabetic retinopathy. Currently, nuclear factor erythroid-2-related factor 2 (Nrf2), thioredoxin interacting protein (TXNIP) and NLRP3 inflammasome pathways are under increasing focus in research on oxidative stress and inflammation-related diseases. On the other hand, tilianin (TN) has received much attention because of its various pharmacological properties. Based on results of these studies, this investigation was performed to inspect the therapeutic efficiency of TN on the retina in diabetic rats. Rats were arbitrarily assigned to three groups: control group, diabetic group, and diabetic plus TN (20 mg/ kg body weight for 42 days, orally) group. TN supplementation in diabetic rats, their food intake, fasting blood glucose status, glycosylated hemoglobin (HbA1c) levels were drastically reduced, and there was a marked augmentation in serum insulin status. TN treatment of diabetic rats increased mRNA expression of Nrf2 and its target gene, HO-1, and noticeably decreased the malondialdehyde status. Activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidases (GPX) were increased relative to diabetic rats. Furthermore, administering TN to the diabetic rats resulted in decreased expression of TXNIP, NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, and IL-1β proteins and decreased distribution of TXNIP, NLRP3, ASC, and caspase-1 proteins in retinas. In addition, TN treatment ameliorated morphological and morphometric changes in the retinas of diabetic rats. Together, all of these findings provide clear evidence that TN treatment of diabetic rats attenuated diabetic retinal changes through its hypoglycemic, antioxidant, and anti-inflammatory properties. The antioxidant and anti-inflammatory effects in diabetic retinas occur at least in part through the modulation of Nrf2/TXNIP/NLRP3 inflammasome pathways, which may have remedial benefits in the healing of diabetic retinopathy.