Roderick TanLab of Youhua Liu

Departments of Medicine and PathologyOctober 24, 2013

EXTRACELLULAR SUPEROXIDE DISMUTASE IN KIDNEY DISEASE

OUTLINE• Oxidative Stress in Renal Fibrosis

• Introduction to EC-SOD

• Role of EC-SOD in Adriamycin Injury

• Association with Wnt/beta-catenin signaling

DEVELOPMENT OF RENAL FIBROSIS

Liu, Nat Rev Neph 2011

OXIDATIVE STRESS (OS)

ROS Antioxidants

OXIDATIVE STRESS (OS)

ROS

AntioxidantsInflammationAngiotensin IINADPH oxidases

SOD, Catalase,Glutathione peroxidase

EXTRACELLULAR SUPEROXIDE DISMUTASE (EC-SOD)

• 1 of 3 isoforms of SOD

• Antioxidant enzyme

• High expression in normal kidney

Folz et al., AJRCMB 1997

O2- + O2

- O2 + H2O2

2H+

EC-SOD

K ~ 1 x 109

Molecular Oxygen (O2)Superoxide (O2-)

O O׃ ׃ ׃׃ ׃

● ● ●

O = O׃׃׃׃

-

Inflammatory CellsActivated Fibroblasts, Epithelium, Endothelium

O2●-

EC-SOD prevents superoxide from forming potent reactive oxygen species

+ NO●ONOO- HO●

NO2

Fe3+Fe2+

H202

HO●

EC-SODCell and tissue damage, signaling cascades, aging,etc.

Distribution of EC-SOD in kidney

Zelko and Folz, Endocrinology 2005

ADRIAMYCIN NEPHROPATHY• Murine model for FSGS• Single IV (tail vein) injection• Glomerular injury proteinuria• Tubular damage / fibrosis• Superoxide-mediated

ADR INJURY IN WILD TYPE MICE

CTL ADR0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

CTL ADR0

25

50

75

100

125

seru

m c

reat

inin

e (m

g/d

L)

mg

Ual

b /

mg

UC

r* *

ADR DEPLETES RENAL EC-SOD

CTL 1 WK 5 WK0.0

1.0

2.0

3.0

EC

-SO

D

**

EC-SOD KNOCKOUT MICE

• Global knockouts (KO)

• No overt phenotype under basal conditions

EC-SOD KO MICE ARE SENSTIVIE TO ADR INJURY

WT ADR KO ADRD

HE

WT KO0

5000

10000

15000

20000

25000

Th

resh

old

ed

are

a

*

NADPH OXIDASE

WT KO0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

NO

X2

WT KO0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

NO

X4

*

EC-SOD KO MICE ARE SENSTIVIE TO ADR INJURY

TIME 0

4 WK 5 WK 6 WK 7 WK 8 WK0

50

100

150

200

250

300

350

400

450

WILD TYPE ECSOD KO

mg

Ua

lb /

mg

UC

r

**

*

*

*

*

EC-SOD KO MICE ARE SENSITIVE TO ADR INJURY

EC-SOD KO MICE ARE SENSITIVE TO ADR INJURY

WT KO0.0

0.5

1.0

1.5

2.0

2.5

fib

ron

ec

tin

mR

NA

WT KO0.0

0.2

0.4

0.6

0.8

de

sm

in

WT KO0.0

1.0

2.0

3.0

4.0

fib

ron

ecti

n **

*

WNT/BETA-CATENIN SIGNALING

• Developmental pathway

• Quiescent in normal adult kidney tissue

• Upregulated in glomerular and interstitial injuries

• Blockade ameliorates of renal injury

He, JASN (2009, 2011); Hao, JASN (2011); Dai, JASN (2009)

EC-SOD KO MICE ARE SENSTIVIE TO ADR INJURY

WT KO

β-c

aten

in

WT ADR KO ADR0.00

1.00

2.00

3.00

4.00

MM

P-7

mR

NA *

SUMMARY

• EC-SOD is depleted from kidneys after ADR

• EC-SOD KO mice are sensitized to oxidative stress, proteinuria and fibrosis after ADR

• EC-SOD KO have increased b-catenin activation after ADR

MODEL OF INJURYADRIAMYCIN

PODOCYTE / GLOMERULAR INJURY

PROTEINURIA

FIBROSISDECREASED RENAL FUNCTION

EC-SOD

ACKNOWLEDGMENTS• Liu Lab

• Youhua Liu

• Dong Zhou

• Liangxiang Xiao

• Lin Lin

• Tom Kleyman

• Tim Oury

• Donna Beer-Stolz

• Bruce Freeman

• Ken Hallows

• Pittsburgh Center for Kidney Research

• Center for Biologic Imaging

• NIDDK R01 DK091239

• NIDDK T32 DK061296

• AHA FTF 16990086

Tokarska-Schlattner, J of Mol and Cell Card (2006)

MECHANISM OF ACTION