The Thromboxane Receptor Antagonist S18886 Attenuates Renal Oxidant Stress and Proteinuria in Diabetic Apolipoprotein E-Deficient Mice

The Thromboxane Receptor Antagonist S18886 Attenuates Renal Oxidant Stress and Proteinuria in Diabetic Apolipoprotein E-Deficient Mice Shanqin Xu 1 , Bingbing Jiang 1 , Karlene A. Maitland 1 , Hossein Bayat 1 , Jiali Gu 2 , Jerry L. Nadler 2 , Stefano Corda 3 , Gilbert Lavielle 4 , Tony J. Verbeuren 5 , Adriana Zuccollo 1 and Richard A. Cohen 1 1 Vascular Biology Unit, Department of Medicine, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts 2 Department of Diabetes and Endocrinology, University of Virginia, Charlottesville, Virginia 3 Institut de Recherches Internationales Servier, Courbevoie, France 4 Division of Chemistry, Institut de Recherches Servier, Croissy, France 5 Division of Angiology, Institut de Recherches Servier, Suresnes, France Address correspondence and reprint requests to Dr. Richard A. Cohen, Director, Vascular Biology Unit, Boston University Medical Center, 650 Albany St., X704, Boston, MA 02118. E-mail: racohen{at}bu.edu Abstract Arachidonic acid metabolites, some of which may activate thromboxane A 2 receptors (TPr) and contribute to the development of diabetes complications, including nephropathy, are elevated in diabetes. This study determined the effect of blocking TPr with S18886 or inhibiting cyclooxygenase with aspirin on oxidative stress and the early stages of nephropathy in streptozotocin-induced diabetic apolipoprotein E −/− mice. Diabetic mice were treated with S18886 (5 mg · kg −1 · day −1 ) or aspirin (30 mg · kg −1 · day −1 ) for 6 weeks. Neither S18886 nor aspirin affected hyperglycemia or hypercholesterolemia. There was intense immunohistochemical staining for nitrotyrosine in diabetic mouse kidney. In addition, a decrease in manganese superoxide dismutase (MnSOD) activity was associated with an increase in MnSOD tyrosine-34 nitration. Tyrosine nitration was significantly reduced by S18886 but not by aspirin. Staining for the NADPH oxidase subunit p47 phox , inducible nitric oxide synthase, and 12-lipoxygenase was increased in diabetic mouse kidney, as were urine levels of 12-hydroxyeicosatetraenoic acid and 8-iso-prostaglandin F 2α . S18886 attenuated all of these markers of oxidant stress and inflammation. Furthermore, S18886 significantly attenuated microalbuminuria in diabetic mice and ameliorated histological evidence of diabetic nephropathy, including transforming growth factor-β and extracellular matrix expression. Thus, in contrast to inhibiting cyclooxygenase, blo