gkt137831 and Diabetic-Nephropathies

Kidney disease caused by type 1 diabetes can progress to end stage renal disease and can increase mortality risk. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) plays a major role in producing oxidative stress in the kidney in diabetes, and its activity is attenuated by GKT137831, an oral Nox inhibitor with predominant inhibitory action on Nox-1 and Nox - 4. Previous studies have demonstrated renoprotective effects with GKT137831 in various experimental models of type 1 diabetes-related kidney disease. This study will evaluate the effect of GKT137831 in treating clinical diabetic kidney disease.. This is a multi-center, randomized, placebo-controlled trial, parallel arm study evaluating the effect on albuminuria of treatment with GKT137831 400 mg BID for 48 weeks. The study will randomize 142 participants who have persistent albuminuria and estimated glomerular filtration rate (eGFR) at baseline of at least 40 ml/min/1.73m. Difference between arms in urine albumin to creatinine ratio. Secondary outcome measures include eGFR.. This study is important because it may identify a new way of slowing renal disease progression in people with type 1 diabetes and albuminuria already receiving standard of care treatment.

Topics: Albuminuria; Creatinine; Diabetes Mellitus, Type 1; Diabetic Nephropathies; Dose-Response Relationship, Drug; Double-Blind Method; Glomerular Filtration Rate; Humans; NADPH Oxidases; Pyrazolones; Pyridones

Recent studies have suggested that renal Nox is important in the progression of diabetic nephropathy. Therefore, we investigated the effect of a novel pan-NOX-inhibitor, APX-115, on diabetic nephropathy in type 2 diabetic mice. Eight- week-old db/m and db/db mice were treated with APX-115 for 12 weeks. APX-115 was administered by oral gavage at a dose of 60 mg/kg per day. To compare the effects of APX-115 with a dual Nox1/Nox4 inhibitor, db/db mice were treated with GKT137831 according to the same protocol. APX-115 significantly improved insulin resistance in diabetic mice, similar to GKT137831. Oxidative stress as measured by plasma 8-isoprostane level was decreased in the APX-115 group compared with diabetic controls. All lipid profiles, both in plasma and tissues improved with Nox inhibition. APX-115 treatment decreased Nox1, Nox2, and Nox4 protein expression in the kidney. APX-115 decreased urinary albumin excretion and preserved creatinine level. In diabetic kidneys, APX-115 significantly improved mesangial expansion, but GKT137831 did not. In addition, F4/80 infiltration in the adipose tissue and kidney decreased with APX-115 treatment. We also found that TGF-β stimulated ROS generation in primary mouse mesangial cells (pMMCs) from wild-type, Nox1 KO, and Duox1 KO mice, but did not induce Nox activity in pMMCs from Nox2 knockout (KO), Nox4 KO, or Duox2 KO mice. These results indicate that activating Nox2, Nox4, or Duox2 in pMMCs is essential for TGF-β-mediated ROS generation. Our findings suggest that APX-115 may be as effective or may provide better protection than the dual Nox1/Nox4 inhibitor, and pan-Nox inhibition with APX-115 might be a promising therapy for diabetic nephropathy.

Topics: Animals; Blotting, Western; Cells, Cultured; Cytokines; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Enzyme Inhibitors; Female; Gene Expression; Isoenzymes; Kidney; Lipid Peroxidation; Lipids; Male; Mesangial Cells; Mice, Inbred C57BL; Mice, Knockout; NADPH Oxidases; Organ Size; Protective Agents; Pyrazoles; Pyrazolones; Pyridines; Pyridones; Reactive Oxygen Species; Reverse Transcriptase Polymerase Chain Reaction; Time Factors; Transforming Growth Factor beta

Reactive oxygen species (ROS) generated by Nox NADPH oxidases may play a critical role in the pathogenesis of diabetic nephropathy (DN). The efficacy of the Nox1/Nox4 inhibitor GKT137831 on the manifestations of DN was studied in OVE26 mice, a model of type 1 diabetes. Starting at 4-5 mo of age, OVE26 mice were treated with GKT137831 at 10 or 40 mg/kg, once-a-day for 4 wk. At both doses, GKT137831 inhibited NADPH oxidase activity, superoxide generation, and hydrogen peroxide production in the renal cortex from diabetic mice without affecting Nox1 or Nox4 protein expression. The increased expression of fibronectin and type IV collagen was reduced in the renal cortex, including glomeruli, of diabetic mice treated with GKT137831. GKT137831 significantly reduced glomerular hypertrophy, mesangial matrix expansion, urinary albumin excretion, and podocyte loss in OVE26 mice. GKT137831 also attenuated macrophage infiltration in glomeruli and tubulointerstitium. Collectively, our data indicate that pharmacological inhibition of Nox1/4 affords broad renoprotection in mice with preexisting diabetes and established kidney disease. This study validates the relevance of targeting Nox4 and identifies GKT137831 as a promising compound for the treatment of DN in type 1 diabetes.

Topics: Animals; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Nephropathies; Enzyme Inhibitors; Kidney; Mice; NADH, NADPH Oxidoreductases; NADPH Oxidase 1; NADPH Oxidase 4; NADPH Oxidases; Podocytes; Pyrazoles; Pyrazolones; Pyridines; Pyridones; Reactive Oxygen Species

Diabetic nephropathy may occur, in part, as a result of intrarenal oxidative stress. NADPH oxidases comprise the only known dedicated reactive oxygen species (ROS)-forming enzyme family. In the rodent kidney, three isoforms of the catalytic subunit of NADPH oxidase are expressed (Nox1, Nox2, and Nox4). Here we show that Nox4 is the main source of renal ROS in a mouse model of diabetic nephropathy induced by streptozotocin administration in ApoE(-/-) mice. Deletion of Nox4, but not of Nox1, resulted in renal protection from glomerular injury as evidenced by attenuated albuminuria, preserved structure, reduced glomerular accumulation of extracellular matrix proteins, attenuated glomerular macrophage infiltration, and reduced renal expression of monocyte chemoattractant protein-1 and NF-κB in streptozotocin-induced diabetic ApoE(-/-) mice. Importantly, administration of the most specific Nox1/4 inhibitor, GKT137831, replicated these renoprotective effects of Nox4 deletion. In human podocytes, silencing of the Nox4 gene resulted in reduced production of ROS and downregulation of proinflammatory and profibrotic markers that are implicated in diabetic nephropathy. Collectively, these results identify Nox4 as a key source of ROS responsible for kidney injury in diabetes and provide proof of principle for an innovative small molecule approach to treat and/or prevent chronic kidney failure.

Topics: Albuminuria; Animals; Apolipoproteins E; Cell Line, Transformed; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Disease Models, Animal; Enzyme Inhibitors; Extracellular Matrix; Gene Silencing; Glucose; Humans; Macrophages; Male; Mice; Mice, Knockout; NADH, NADPH Oxidoreductases; NADPH Oxidase 1; NADPH Oxidase 4; NADPH Oxidases; Podocytes; Pyrazoles; Pyrazolones; Pyridines; Pyridones; Reactive Oxygen Species