Glucagon-like peptide-1 receptor agonists rescued diabetic vascular endothelial damage through suppression of aberrant STING signaling

Glucagon-like peptide-1 receptor agonists(GLP-1 RAs)protect against diabetic cardiovascular diseases and nephropathy.However,their activity in diabetic retinopathy(DR)remains unclear.Our retrospective cohort study involving 1626 T2DM patients revealed superior efficacy of GLP-1 RAs in controlling DR compared to other glucose-lowering medications,suggesting their advantage in DR treatment.By single-cell RNA-sequencing analysis and immunostaining,we observed a high expression of GLP-1R in retinal endothelial cells,which was down-regulated under diabetic conditions.Treatment of GLP-1 RAs significantly restored the receptor expression,resulting in an improvement in retinal degeneration,vascular tortuosity,avascular vessels,and vascular integrity in diabetic mice.GO and GSEA analyses further implicated enhanced mitochondrial gene translation and mitochondrial functions by GLP-1 RAs.Additionally,the treatment attenuated STING signaling activation in retinal endothelial cells,which is typically activated by leaked mitochondrial DNA.Expression of STING mRNA was positively correlated to the levels of angiogenic and inflammatory factors in the endothelial cells of human fibrovascular membranes.Further investigation revealed that the cAMP-responsive element binding protein played a role in the GLP-1R signaling pathway on suppression of STING signaling.This study demonstrates a novel role of GLP-1 RAs in the protection of diabetic retinal vasculature by inhibiting STING-elicited inflammatory signals.

Glucokinase activator improves glucose tolerance and induces hepatic lipid accumulation in mice with diet-induced obesity

Background and aims:Type 2 diabetes mellitus remains a substantial medical problem with increasing global prevalence.Pharmacological research is becoming increasingly focused on personalized treatment strategies.Drug development based on glucokinase(GK)activation is an important strategy for lowering blood glucose.This study aimed to investigate the effect of GK activation on glucose and lipid metabolism in diet-induced obese mice.Materials and methods:Mice were fed with a high-fat diet(HFD)for 16 weeks to induce obesity,followed by a GK activator(GKA,AZD1656)or vehicle treatment by gavage for 4 weeks.The effect of GKA treatment on glucose metabolism was evaluated using glucose and insulin tolerance tests.Hepatic lipid accumulation was assessed by hematoxylin and eosin staining,Oil Red O staining,and transmission electron microscopy.The underlying mechanism of GK activation in glucose and lipid metabolism in the liver was studied using transcriptomic analysis,with a mechanistic study in mouse livers in vivo and AML12 cells in vitro.Results:GK activation by GKA treatment improved glucose tolerance in HFD-fed mice while increasing hepatic lipid accumulation.Transcriptomic analysis of liver tissues indicated the lipogenesis and protein kinase RNA-like endoplasmic reticulum kinase(PERK)-unfolded protein response(UPR)pathway activations in GKA-treated HFD-fed mice.Inhibition of the ACC activity,which is an important protein in lipogenesis,attenuated GKA treatment-induced lipid accumulation and PERK-UPR activation in vitro.Conclusions:GK activation improved glucose tolerance and insulin sensitivity while inducing hepatic lipid accumulation by increasing the lipogenic gene expression,which subsequently activated the hepatic PERK-UPR signaling pathway.