The superoxide dismutase mimetic tempol blunts diabetes-induced upregulation of NADPH oxidase and endoplasmic reticulum stress in a rat model of diabetic nephropathy

Miles J. De Blasio, Anand Ramalingam, Anh H Cao, Darnel Prakoso, Ji-Ming Ye, Raelene Pickering, Anna M.D. Watson, Judy B. de Haan, David M. Kaye, Rebecca H. Ritchie

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Abstract

Endoplasmic reticulum (ER) stress contributes to progression of diabetic nephropathy, which promotes end-stage renal failure in diabetic patients. This study was undertaken to investigate the actions of tempol and ramipril, pharmacological agents that target the consequences of NADPH oxidase, on diabetic nephropathy in a rat model of type 1 diabetes, with an emphasis on markers of ER stress. Male Sprague-Dawley rats were injected intravenously with a single bolus of streptozotocin (55 mg/kg) to induce type 1 diabetes. An additional age-matched group of rats was administered with citrate vehicle as controls. After 4 weeks of untreated diabetes, rats received tempol (1.5 mM/kg/day subcutaneously, n=8), ramipril (1 mg/kg/day in drinking water, n=8) or remained untreated for an additional 4 weeks (n=7). After 8 weeks of diabetes in total, kidneys were collected for histological analysis, gene expression and protein abundance. Tempol and ramipril blunted diabetes-induced upregulation of NADPH oxidase isoforms (Nox4, Nox2, p47phox), accompanied by an amelioration of diabetes-induced glomerular injury (podocin, nephrin, Kim-1), tubulo-interstitial fibrosis (TGFβ1, TGFβ-R2, pSMAD3, α-SMA) and pro-inflammatory cytokines (TNFα, MCP-1, ANX-A1, FPR2) expression. In addition, the diabetes-induced renal ER stress, evidenced by increased expression of GRP-78 chaperone and stress-associated markers ATF4, TRB3, as well as XBP1s, phospho-p38 mitogen-activated protein kinase (MAPK) and 3-nitrotyrosination, were all attenuated by tempol and ramipril. These observations suggest that antioxidant approaches that blunt NADPH upregulation may attenuate diabetic nephropathy, at least in part by negatively regulating ER stress and inflammation, and hence ameliorating kidney damage.

Original languageEnglish
Pages (from-to)12-20
Number of pages9
JournalEuropean Journal of Pharmacology
Volume807
DOIs
Publication statusPublished - 2017

Keywords

  • ACE inhibitor
  • Antioxidant
  • Inflammation
  • Kidney
  • NADPH oxidase
  • Renal remodeling

Cite this

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title = "The superoxide dismutase mimetic tempol blunts diabetes-induced upregulation of NADPH oxidase and endoplasmic reticulum stress in a rat model of diabetic nephropathy",
abstract = "Endoplasmic reticulum (ER) stress contributes to progression of diabetic nephropathy, which promotes end-stage renal failure in diabetic patients. This study was undertaken to investigate the actions of tempol and ramipril, pharmacological agents that target the consequences of NADPH oxidase, on diabetic nephropathy in a rat model of type 1 diabetes, with an emphasis on markers of ER stress. Male Sprague-Dawley rats were injected intravenously with a single bolus of streptozotocin (55 mg/kg) to induce type 1 diabetes. An additional age-matched group of rats was administered with citrate vehicle as controls. After 4 weeks of untreated diabetes, rats received tempol (1.5 mM/kg/day subcutaneously, n=8), ramipril (1 mg/kg/day in drinking water, n=8) or remained untreated for an additional 4 weeks (n=7). After 8 weeks of diabetes in total, kidneys were collected for histological analysis, gene expression and protein abundance. Tempol and ramipril blunted diabetes-induced upregulation of NADPH oxidase isoforms (Nox4, Nox2, p47phox), accompanied by an amelioration of diabetes-induced glomerular injury (podocin, nephrin, Kim-1), tubulo-interstitial fibrosis (TGFβ1, TGFβ-R2, pSMAD3, α-SMA) and pro-inflammatory cytokines (TNFα, MCP-1, ANX-A1, FPR2) expression. In addition, the diabetes-induced renal ER stress, evidenced by increased expression of GRP-78 chaperone and stress-associated markers ATF4, TRB3, as well as XBP1s, phospho-p38 mitogen-activated protein kinase (MAPK) and 3-nitrotyrosination, were all attenuated by tempol and ramipril. These observations suggest that antioxidant approaches that blunt NADPH upregulation may attenuate diabetic nephropathy, at least in part by negatively regulating ER stress and inflammation, and hence ameliorating kidney damage.",
keywords = "ACE inhibitor, Antioxidant, Inflammation, Kidney, NADPH oxidase, Renal remodeling",
author = "{De Blasio}, {Miles J.} and Anand Ramalingam and Cao, {Anh H} and Darnel Prakoso and Ji-Ming Ye and Raelene Pickering and Watson, {Anna M.D.} and {de Haan}, {Judy B.} and Kaye, {David M.} and Ritchie, {Rebecca H.}",
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T1 - The superoxide dismutase mimetic tempol blunts diabetes-induced upregulation of NADPH oxidase and endoplasmic reticulum stress in a rat model of diabetic nephropathy

AU - De Blasio, Miles J.

AU - Ramalingam, Anand

AU - Cao, Anh H

AU - Prakoso, Darnel

AU - Ye, Ji-Ming

AU - Pickering, Raelene

AU - Watson, Anna M.D.

AU - de Haan, Judy B.

AU - Kaye, David M.

AU - Ritchie, Rebecca H.

PY - 2017

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AB - Endoplasmic reticulum (ER) stress contributes to progression of diabetic nephropathy, which promotes end-stage renal failure in diabetic patients. This study was undertaken to investigate the actions of tempol and ramipril, pharmacological agents that target the consequences of NADPH oxidase, on diabetic nephropathy in a rat model of type 1 diabetes, with an emphasis on markers of ER stress. Male Sprague-Dawley rats were injected intravenously with a single bolus of streptozotocin (55 mg/kg) to induce type 1 diabetes. An additional age-matched group of rats was administered with citrate vehicle as controls. After 4 weeks of untreated diabetes, rats received tempol (1.5 mM/kg/day subcutaneously, n=8), ramipril (1 mg/kg/day in drinking water, n=8) or remained untreated for an additional 4 weeks (n=7). After 8 weeks of diabetes in total, kidneys were collected for histological analysis, gene expression and protein abundance. Tempol and ramipril blunted diabetes-induced upregulation of NADPH oxidase isoforms (Nox4, Nox2, p47phox), accompanied by an amelioration of diabetes-induced glomerular injury (podocin, nephrin, Kim-1), tubulo-interstitial fibrosis (TGFβ1, TGFβ-R2, pSMAD3, α-SMA) and pro-inflammatory cytokines (TNFα, MCP-1, ANX-A1, FPR2) expression. In addition, the diabetes-induced renal ER stress, evidenced by increased expression of GRP-78 chaperone and stress-associated markers ATF4, TRB3, as well as XBP1s, phospho-p38 mitogen-activated protein kinase (MAPK) and 3-nitrotyrosination, were all attenuated by tempol and ramipril. These observations suggest that antioxidant approaches that blunt NADPH upregulation may attenuate diabetic nephropathy, at least in part by negatively regulating ER stress and inflammation, and hence ameliorating kidney damage.

KW - ACE inhibitor

KW - Antioxidant

KW - Inflammation

KW - Kidney

KW - NADPH oxidase

KW - Renal remodeling

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