Blockade of Endothelial-Mesenchymal Transition by a Smad3 Inhibitor Delays the Early Development of Streptozotocin-Induced Diabetic Nephropathy

Abstract

OBJECTIVEA multicenter, controlled trial showed that early blockade of the renin-angiotensin system in patients with type 1 diabetes and normoalbuminuria did not retard the progression of nephropathy, suggesting that other mechanism(s) are involved in the pathogenesis of early diabetic nephropathy (diabetic nephropathy). We have previously demonstrated that endothelial-mesenchymal-transition (EndoMT) contributes to the early development of renal interstitial fibrosis independently of microalbuminuria in mice with streptozotocin (STZ)-induced diabetes. In the present study, we hypothesized that blocking EndoMT reduces the early development of diabetic nephropathy.RESEARCH DESIGN AND METHODSEndoMT was induced in a mouse pancreatic microvascular endothelial cell line (MMEC) in the presence of advanced glycation end products (AGEs) and in the endothelial lineage–traceble mouse line Tie2-Cre;Loxp-EGFP by administration of AGEs, with nonglycated mouse albumin serving as a control. Phosphorylated Smad3 was detected by immunoprecipitation/Western blotting and confocal microscopy. Blocking studies using receptor for AGE siRNA and a specific inhibitor of Smad3 (SIS3) were performed in MMECs and in STZ-induced diabetic nephropathy in Tie2-Cre;Loxp-EGFP mice.RESULTSConfocal microscopy and real-time PCR demonstrated that AGEs induced EndoMT in MMECs and in Tie2-Cre;Loxp-EGFP mice. Immunoprecipitation/Western blotting showed that Smad3 was activated by AGEs but was inhibited by SIS3 in MMECs and in STZ-induced diabetic nephropathy. Confocal microscopy and real-time PCR further demonstrated that SIS3 abrogated EndoMT, reduced renal fibrosis, and retarded progression of nephropathy.CONCLUSIONSEndoMT is a novel pathway leading to early development of diabetic nephropathy. Blockade of EndoMT by SIS3 may provide a new strategy to retard the progression of diabetic nephropathy and other diabetes complications.

Acetyl‐11‐keto‐β‐boswellic acid ameliorates renal interstitial fibrosis via Klotho/TGF‐β/Smad signalling pathway

“…In the context of renal interstitial fibrosis, Smad2/3 was reported to be strongly activated in various CKDs 34. In addition, deletion of Smad3 in mice or use of Smad3 inhibitor suppressed the progress of renal fibrosis 35, 36. As expected, excessive expression of Smad 2/3 was observed both in obstructive kidneys and hypoxia‐insulted HK‐2 cells.…”

Activin Receptor‐Like Kinase 4 Haplodeficiency Mitigates Arrhythmogenic Atrial Remodeling and Vulnerability to Atrial Fibrillation in Cardiac Pathological Hypertrophy

“…After the animal surgery, an Alzet osmotic minipump was implanted for subcutaneous delivery of Smad3 inhibitor SIS3 (2.5 mg/kg per day) for 8 weeks 22. At the end of the experiments, a burst of programmed electrical stimulation was performed to evaluate the inducibility of AF.…”

Controlling the receptor for advanced glycation end‐products to conquer diabetic vascular complications

“…Furthermore, we generated RAGE‐knockout (KO) mice and report the marked improvement in nephromegaly, albuminuria and glomerulosclerosis, as well as increased serum creatinine levels in diabetic RAGE‐KO mice (Figure 3) 31 . The deletion of RAGE also attenuated the endothelial–mesenchymal transition 60 . Streptozotocin (STZ)‐injected RAGE‐KO mice were protected from early kidney injuries as a result of mesangial matrix expansion and thickening of the glomerular basement membrane as seen in wild‐type diabetic mice 61 .…”