title: Plumbagin ameliorates diabetic nephropathy via interruption of pathways that include NOX4 signalling.
abstract: NADPH oxidase 4 (Nox4) is reported to be the major source of reactive oxygen species (ROS) in the kidneys during the early stages of diabetic nephropathy. It has been shown to mediate TGFβ1-induced differentiation of cardiac fibroblasts into myofibroblasts. Despite TGFβ1 being recognised as a mediator of renal fibrosis and functional decline role in diabetic nephropathy, the renal interaction between Nox 4 and TGFβ1 is not well characterised. The aim of this study was to investigate the role of Nox4 inhibition on TGFβ1-induced fibrotic responses in proximal tubular cells and in a mouse model of diabetic nephropathy. Immortalised human proximal tubular cells (HK2) were incubated with TGFβ1 ± plumbagin (an inhibitor of Nox4) or specific Nox4 siRNA. Collagen IV and fibronectin mRNA and protein expression were measured. Streptozotocin (STZ) induced diabetic C57BL/6J mice were administered plumbagin (2 mg/kg/day) or vehicle (DMSO; 50 µl/mouse) for 24 weeks. Metabolic, physiological and histological markers of nephropathy were determined. TGFβ1 increased Nox4 mRNA expression and plumbagin and Nox4 siRNA significantly inhibited TGF-β1 induced fibronectin and collagen IV expression in human HK2 cells. STZ-induced diabetic C57BL/6J mice developed physiological features of diabetic nephropathy at 24 weeks, which were reversed with concomitant plumbagin treatment. Histologically, plumbagin ameliorated diabetes induced upregulation of extracellular matrix protein expression compared to control. This study demonstrates that plumbagin ameliorates the development of diabetic nephropathy through pathways that include Nox4 signalling.
authors.affiliation: Department of Medicine, Kolling Institute of Medical Research, Northern Clinical School, University of Sydney, Sydney, Australia.
authors.forename: Rachel
authors.initials: R
authors.lastname: Yong
authors.forename: Xin-Ming
authors.initials: XM
authors.lastname: Chen
authors.forename: Sylvie
authors.initials: S
authors.lastname: Shen
authors.forename: Swarna
authors.initials: S
authors.lastname: Vijayaraj
authors.forename: Qing
authors.initials: Q
authors.lastname: Ma
authors.forename: Carol A
authors.initials: CA
authors.lastname: Pollock
authors.forename: Sonia
authors.initials: S
authors.lastname: Saad
mesh_terms: D000818:Animals; D001483:Base Sequence; D002461:Cell Line, Transformed; D024141:Collagen Type IV / Q000235:genetics; D017931:DNA Primers; D003928:Diabetic Nephropathies / Q000188:drug therapy* / Q000201:enzymology; D005353:Fibronectins / Q000235:genetics; D005947:Glucose / Q000008:administration & dosage; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D009285:Naphthoquinones / Q000627:therapeutic use*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D013311:Streptozocin; D013482:Superoxide Dismutase / Q000235:genetics; D053773:Transforming Growth Factor beta1 / Q000378:metabolism
chemical_list: D024141:Collagen Type IV; D017931:DNA Primers; D005353:Fibronectins; D009285:Naphthoquinones; D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1; D013311:Streptozocin; D013482:Superoxide Dismutase; D019255:NADPH Oxidases; D005947:Glucose; C014758:plumbagin