Abstract:AIM: To investigate the effect and potential mechanism of liraglutide(LIR)combined with neural stem cells(NSCs)in alleviating diabetic retinopathy(DR)in rats.
METHODS:A DR rat model was established using a high-fat diet combined with a single intraperitoneal injection of streptozotocin(STZ). Rats in the control group were fed a normal diet and received an intraperitoneal injection of citric acid-sodium citrate buffer. After modeling, the rats were divided into the control group, DR group, DR+LIR group, DR+BMSCs group, DR+NSCs group, DR+BMSCs+LIR group, and DR+NSCs+LIR group. According to the grouping instructions, rats were given intraperitoneal injection of LIR at 200 μg/(kg·d)and intravitreal injection of bone marrow mesenchymal stem cells(BMSCs), or NSCs, or the combined therapy accordingly for 8 wk. Fasting blood glucose(FBG)and serum insulin levels, as well as retinal oxidative stress indexes and serum inflammatory indexes, were detected in each group. Retinopathy was evaluated by hematoxylin-eosin(HE)staining, retinal cell apoptosis was detected by TUNEL staining, SIRT1 expression in retinal tissues was detected by immunohistochemistry, and BDNF expression in retinal tissues was detected by immunofluorescence. The transcriptional levels of cZNF532, miR-29a-3p, SIRT1, TGF-β1, NRF2, Keap1, and BDNF in retinal tissues were detected by qRT-PCR, and the protein expression levels of SIRT1, TGF-β1, SMAD2/3, p-SMAD2/3, NRF2, Keap1, p65, and p-p65 in retinal tissues were detected by Western blot.
RESULTS:Compared with the other groups of rats, the retinal morphology of rats in the DR+NSCs+LIR group was significantly improved, the levels of FBG, TNF-α, IL-1β, IL-6 and MDA were decreased(all P<0.05), the serum insulin level and the levels of SOD, CAT, and GSH-Px were increased(all P<0.05), the TUNEL-positive rate of retinal cells was reduced(all P<0.05). The expression levels of cZNF532, SIRT1, NRF2, and BDNF in retinal tissue were up-regulated(all P<0.05), whereas the expression levels of miR-29a-3p, TGF-β1, p-SMAD2/3, Keap1, and p-p65 were down-regulated(all P<0.05).
CONCLUSION:LIR combined with NSCs alleviates DR by regulating the cZNF532-miR-29a-3p-SIRT1 network and its downstream TGF-β/SMAD, NF-κB, and Keap1/NRF2 signaling pathways.
