ELABELA/APJ Axis Prevents Diabetic Glomerular Endothelial Injury by Regulating AMPK/NLRP3 Pathway.

ELABELA (ELA), a recently discovered peptide, is highly expressed in adult kidneys and the endothelium system. It has been identified as a novel endogenous ligand for the apelin receptor (APJ). This study aims to investigate the role of ELA in diabetic glomerular endothelial pyroptosis and its underlying mechanism. Initially, a significant decrease in ELA mRNA levels was observed in the renal cortex of db/db mice and high glucose-treated glomerular endothelial cells (GECs). It was also found that ELA deficiency in ELA+/- mice significantly accelerated diabetic glomerular injury, as shown by exacerbated glomerular morphological damage, increased serum creatine and blood urea nitrogen, and elevated 24-h urinary albumin excretion. In addition, in vivo overexpression of ELA prevented diabetic glomerular injury, reduced von Willebrand factor expression, restored endothelial marker CD31 expression, and attenuated the production of adhesive molecules such as intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. Furthermore, in vitro studies confirmed that treatment with ELA inhibited GEC injury by regulating the NOD-like receptor protein 3 (NLRP3) inflammasome, as indicated by blocking NLRP3 inflammasome formation, decreasing cleaved Caspase-1 production, and inhibiting interleukin-1ß and interleukin-18 production. Moreover, in vitro experiments demonstrated that the protective effects of ELA in GECs during hyperglycemia were diminished by inhibiting adenosine monophosphate-activated protein kinase (AMPK) using Compound C or by APJ deficiency. Taken together, this study provides the first evidence that ELA treatment could prevent diabetic glomerular endothelial injury, which is partly mediated by the regulation of the AMPK/NLRP3 signaling pathway. Therefore, pharmacologically targeting ELA may serve as a novel therapeutic strategy for diabetic kidney disease.

Sappanone a prevents diabetic kidney disease by inhibiting kidney inflammation and fibrosis via the NF-κB signaling pathway.

Background: Low grade of sterile inflammation plays detrimental roles in the progression of diabetic kidney disease (DKD). Sappanone A (SA), a kind of homoisoflavanone isolated from the heartwood of Caesalpinia sappan, exerts anti-inflammatory effects in acute kidney injury. However, whether SA has beneficial effects on diabetic kidney disease remains further exploration. Methods and Results: In the present study, uninephrectomized male mice were treated with Streptozotocin (STZ, 50 mg/kg) for five consecutive days to induce diabetes. Next, the diabetic mice were administered orally with SA (10, 20, or 30 mg/kg) or vehicle once per day. Our results showed that STZ treatment significantly enhanced damage in the kidney, as indicated by an increased ratio of kidney weight/body weight, elevated serum creatinine and blood urea nitrogen (BUN), as well as increased 24-h urinary protein excretion, whereas SA-treated mice exhibited a markedly amelioration in these kidney damages. Furthermore, SA attenuated the pathological changes, alleviated fibrotic molecules transforming growth factor-ß1 (TGF-ß1) and Collagen-IV (Col-IV) production, decreased inflammatory cytokines interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) expression in STZ-treated mice. Similarly, in glomerular mesangial cells, SA pretreatment decreased high glucose (HG)-induced proliferation, inflammatory cytokines excretion, and fibrotic molecules expression. Mechanistically, SA decreased the expression of nuclear factor kappa B (NF-κB) and restored the expression of total NF-κB inhibitor alpha (IκBα) both in vivo and in vitro. Conclusion: Our data suggest that SA may prevent diabetes-induced kidney inflammation and fibrosis by inhibiting the NF-κB pathway. Hence, SA can be potential and specific therapeutic value in DKD.