Assuntos
Bacteriemia , Neoplasias Colorretais , Infecções Estreptocócicas , Bacteriemia/complicações , Bacteriemia/diagnóstico , Neoplasias Colorretais/complicações , Neoplasias Colorretais/diagnóstico , Humanos , Infecções Estreptocócicas/complicações , Infecções Estreptocócicas/diagnóstico , Streptococcus gallolyticusRESUMO
NADPH oxidase-derived excessive production of reactive oxygen species (ROS) in the kidney plays a key role in mediating renal injury in diabetes. Pathological changes in diabetes include mesangial expansion and accumulation of extracellular matrix (ECM) leading to glomerulosclerosis. There is a paucity of data about the role of the Nox5 isoform of NADPH oxidase in animal models of diabetic nephropathy since Nox5 is absent in the mouse genome. Thus, we examined the role of Nox5 in human diabetic nephropathy in human mesangial cells and in an inducible human Nox5 transgenic mouse exposed to streptozotocin-induced diabetes. In human kidney biopsies, Nox5 was identified to be expressed in glomeruli, which appeared to be increased in diabetes. Colocalization demonstrated Nox5 expression in mesangial cells. In vitro, silencing of Nox5 in human mesangial cells was associated with attenuation of the hyperglycemia and TGF-ß1-induced enhanced ROS production, increased expression of profibrotic and proinflammatory mediators, and increased TRPC6, PKC-α, and PKC-ß expression. In vivo, vascular smooth muscle cell/mesangial cell-specific overexpression of Nox5 in a mouse model of diabetic nephropathy showed enhanced glomerular ROS production, accelerated glomerulosclerosis, mesangial expansion, and ECM protein (collagen IV and fibronectin) accumulation as well as increased macrophage infiltration and expression of the proinflammatory chemokine MCP-1. Collectively, this study provides evidence of a role for Nox5 and its derived ROS in promoting progression of diabetic nephropathy.
Assuntos
Nefropatias Diabéticas/metabolismo , NADPH Oxidases/metabolismo , Animais , Western Blotting , Linhagem Celular , Nefropatias Diabéticas/genética , Ensaio de Imunoadsorção Enzimática , Humanos , Inflamação/metabolismo , Rim/metabolismo , Glomérulos Renais/metabolismo , Células Mesangiais/metabolismo , Camundongos , Camundongos Transgênicos , NADPH Oxidases/genética , Proteína Quinase C beta/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
SIGNIFICANCE: Intrarenal oxidative stress plays a critical role in the initiation and progression of diabetic kidney disease (DKD). Enhanced oxidative stress results from overproduction of reactive oxygen species (ROS) in the context of concomitant, insufficient antioxidant pathways. Renal ROS production in diabetes is predominantly mediated by various NADPH oxidases (NOXs), but a defective antioxidant system as well as mitochondrial dysfunction may also contribute. Recent Advances: Effective agents targeting the source of ROS generation hold the promise to rescue the kidney from oxidative damage and prevent subsequent progression of DKD. Critical Issues and Future Directions: In the present review, we summarize and critically analyze molecular and cellular mechanisms that have been demonstrated to be involved in NOX-induced renal injury in diabetes, with particular focus on the role of increased glomerular injury, the development of albuminuria, and tubulointerstitial fibrosis, as well as mitochondrial dysfunction. Furthermore, novel agents targeting NOX isoforms are discussed. Antioxid. Redox Signal. 25, 657-684.
Assuntos
Injúria Renal Aguda/genética , Nefropatias Diabéticas/genética , Estresse Oxidativo/genética , Injúria Renal Aguda/patologia , Antioxidantes/metabolismo , Nefropatias Diabéticas/patologia , Humanos , Rim/metabolismo , Rim/patologia , NADPH Oxidases/genética , Espécies Reativas de Oxigênio/metabolismoRESUMO
AIMS/HYPOTHESIS: Changes in podocyte morphology and function are associated with albuminuria and progression of diabetic nephropathy. NADPH oxidase 4 (NOX4) is the main source of reactive oxygen species (ROS) in the kidney and Nox4 is upregulated in podocytes in response to high glucose. We assessed the role of NOX4-derived ROS in podocytes in vivo in a model of diabetic nephropathy using a podocyte-specific NOX4-deficient mouse, with a major focus on the development of albuminuria and ultra-glomerular structural damage. METHODS: Streptozotocin-induced diabetes-associated changes in renal structure and function were studied in male floxedNox4 and podocyte-specific, NOX4 knockout (podNox4KO) mice. We assessed albuminuria, glomerular extracellular matrix accumulation and glomerulosclerosis, and markers of ROS and inflammation, as well as glomerular basement membrane thickness, effacement of podocytes and expression of the podocyte-specific protein nephrin. RESULTS: Podocyte-specific Nox4 deletion in streptozotocin-induced diabetic mice attenuated albuminuria in association with reduced vascular endothelial growth factor (VEGF) expression and prevention of the diabetes-induced reduction in nephrin expression. In addition, podocyte-specific Nox4 deletion reduced glomerular accumulation of collagen IV and fibronectin, glomerulosclerosis and mesangial expansion, as well as glomerular basement membrane thickness. Furthermore, diabetes-induced increases in renal ROS, glomerular monocyte chemoattractant protein-1 (MCP-1) and protein kinase C alpha (PKC-α) were attenuated in podocyte-specific NOX4-deficient mice. CONCLUSIONS/INTERPRETATION: Collectively, this study shows the deleterious effect of Nox4 expression in podocytes by promoting podocytopathy in association with albuminuria and extracellular matrix accumulation in experimental diabetes, emphasising the role of NOX4 as a target for new renoprotective agents.