Molecular and cellular changes in acute kidney injury

Acute Kidney Injury in Aging
The Role of Baseline ROS and
Inflammation in AKI
AGER1 is a determinant of Baseline
ROS/Inflammation in Aging
AGER1 Controls ROS and Inflammation,
thus it may control AKI in Toxic Injury, DM
Gary E. Striker, MD
Helen Vlassara, MD
Mount Sinai School of Medicine, NY
1

Determinants of ROS and
Inflammation and AKI in Aging
• The Development of AKI in Aging Patients
with Drug Toxicity or Diabetes Depends on
Pre-Existing ROS/Inflammation.
• What Determines Pre-Existing ROS?
Is it Genes or Environmental Oxidants
• AGER1 Controls the Levels of ROS/Infl
(normally) by controlling oxidants (AGEs).
2

AGEs are one Major Source of Oxidants:
the Level of Oxidants Determines ROS
HbA1c
Proteins
Lipids
Protein
RNA/DNA
+
Glucose
HO
·
-A
RO
·
B
O·
ROS
-C
AGEs
RNS
ROS/Infl
H.Vlassara: Annals of Medicine, 2008
3

Summary (AGEs - ROS)
• AGEs-ROS increase with chronological age, and
they derive mostly from food.
• Excess AGE-ROS are bound and detoxified by
AGER1, and are excreted by the kidneys.
• AGER1 controls systemic AGE-ROS, and may
control the response to AKI in aging after toxin
exposure and in diabetes.
4

AGER1 at the Cell Surface Controls
Exposure of Cells to Oxidant AGEs
Extrinsic Oxidants (MG, CML)
AGEs
AGE-Restriction
AGER1
EGFR
AGER1
RAGE
p66Shc
p-PKC δ
p-p47 phox
ROS
NAPDH
Cytoplasm
NF-kB p65
p-AKT
p-FOXO
Nucleus
TNFα
Vlassara, PNAS 2006, AmJPhys 2009
5

AGER1 is Present in Many Cell Membranes;
In the E.R. it is part of the OST Complex
The OST Complex Plays a Role in Protein
Secretion, Synthesis, RNA Synthesis and the
Unfolded Protein Response (UPR).
6

AGER1 and the OST Complex
• Misfolded proteins increase OS and turn off
protein and RNA synthesis (unfolded protein
response, UPR).
• AGER1 may Protect Against ROS and the UPR.
• AGER1 Deficiency may Promote and/or Aggravate
the UPR.
7

AGER1 Levels, Normal Subjects, CKD Patients
800
AGE-R1 mRNA (AU)
700
600
500
400
300
200
100
Normal
CKD, T2D
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
sMG (nmol/ml)
AGER1 levels Normally Respond to AGEs
However, AGER1 is Decreased in Chronic OS
Vlassara, Uribarri, Striker et al, JCEM, 2009
8

Serum AGEs and Renal Function are Linked
eGFR vs. Aging
Serum CML vs. eGFR
250
200
r = - 0.447
p = 0.0001
60
50
r = - 0.647
p = 0.0001
150
100
40
30
20
50
10
0
20 40 60 80 100
age (years)
0
0 50 100 150 200 250
eGFRCr
Thus, AGE-ROS and Renal Function are Linked.
Vlassara, Uribarri, Striker et al, JAGS 2008; ibid JCEM, 2009
9

AGER1 Levels can be Restored in T2D Patients
(4wk) by Reducing the Intake of AGEs
8-iso
TNFα
AGER1
RAGE
VCAM-1
sCML
sMG
-100 -50 0 50 100
% Change
Thus, Reduced AGER1 levels are not due to
an epigenetic change and can be normalized
quickly and simply.
10
Vlassara, Uribarri, Striker et al, JCEM, 2009

Restoration of AGER1 by Reduced AGE
Intake Restores AGE Excretion (4 mo)
Urine MG (nmoles/24 hr)
400.00
* p

Effect of Decreased AGER1 After a AGE over-load
A Low AGE Diet Prevents Kidney Disease of Aging
and a Single Oral AGE (MG-H1) Promotes CKD of
Aging in (24 mo C57BL6 mice)
A. Low AGE Diet B. AGE (MG)-Supplemented Diet
Thus, AGEs cause ROS/Inflammation, Kidney
Disease, and Also Lead to CVD, etc.!
12
Zheng, Vlassara, Striker, AmJPath 2009

AKI and Baseline ROS
• Baseline Levels of ROS and Inflammation
Determine The Amount and Type of Responses
to an Oxidative Stress or Inflammatory Insult
(toxins, metabolic).
• Since toxins and DM Increase the Levels of
ROS/Inflammation, the Subsequent Response
Depends on Baseline Levels.
• Tested using Tunicamycin to induce ER stress
and by Inducing T1D in Young (Low ROS) and
Old (High ROS) Mice.
13

A
Urinary Albumin
(g/mg.cr)
Diabetic Nephropathy (Y/O)
##
900
700
Old/DN
500
300
100
*
80
60
Y/DN
Old
40
Y
20
0
Before 2 3 4
months after diabetes
B
Urinary Albumin
(g/mg.cr)
1000
800
600
400
200
0
##
Y/DN Old/DN
Proteinuria Increased in the High, But NOT in
those with Low Pre-existing OS/Inflammation
Renal Lesions in DM with Pre-Existing OS/Infl
14

Nephropathy Only with High OS/Infl
Young
Old
No Diabetic
Kidney
Lesions
Young
Old
Typical
Diabetic
Kidney
Lesions
Severe
Diabetic Micro
Vascular
Lesions
Old
Tubulointerstitial
lesion score
9m 9m/DN 22m 22m/DN
ER stress and High OS/Infl
4
3
2
1
0
TID
B
Apoptotic cell/Field
15
10
5
0
Apop
**
9m 9m/DN 22m 22m/DN
15

A
2.0
High Baseline ROS/Inflammation Was
Associated with Endoplasmic Stress (UPR)
**
B
12
##
G
H
GRP78 (xfold)
1.5
1.0
0.5
CHOP (xfold)
8
4
**
C
0
9m 9m/DN 22m 22m/DN
D
0
9m 9m/DN 22m 22m/DN
I
J
L
E
F
0
9 m 9m/DN 22m 22m/DN
ER Stress Data Were Confirmed in KO Mice
K
p-PERK staining
in cortex (%)
100
80
60
40
20
**
##
p-eIF2 staining
( Relative unit)
50
40
30
20
10
0
**
9 m 9m/DN 22m 22m/DN
#
16

Blocking ER Stress Pathways Blocks Apoptosis
and Proteinuria in Old Diabetic Mice
Cell death (%)
100
80
60
**
40
20
0
**
Tuni (g) 0.6 0.8 1.0 1.2
**
**
Wild type
**
Con DN Con DN
Wild type CHOP-/-
CHOP-/-
Urinary Albumin
(g/mg.creatinine)
120
100
80
60
40
20
0
High Pre-Existing OS/Inflammation and ER
Stress (in Aging Mice) is Aggravated by a
Superimposed Oxidative Injury (Tuni, Diabetes).
High Pre-existing OS/Inflammation Increases
Cytokines and Vascular Injury in Old DM Mice.
17

Summary
• Pre-Existing Levels of OS and Inflammation Determine
the Amount and Type of Response to AKI (due to
Toxins, DN).
• Since control of OS/Inflammation is critical in AKI,
Pre-Existing OS should be recognized and treated
first.
• OS/Inflammation can be Reduced (with drugs and/or
Low-AGE Diet).
• Best Option? A Combination of Drugs and Control of
AGE Intake.
18

So, What Constitutes High AGE Intake?
Heat-Processed Foods .
The Good News: A 50% decrease may be Sufficient!
No Changes in Calorie or Nutrient Consumption 19

Future Directions
• Relationship between AGER1 and markers of
AKI; first in models and then in aging patients
exposed to renal toxins and/or with diabetes.
• Determine if reduction of AGER1 after AKI
prevents/ameliorates the development of CKD.
• Determine if return of AGER1 levels to normal
in aging patients protects reduces OS/Infl and
and AKI in aging patients scheduled for
elective procedures.
• Focus, focus, focus.
20

Mt. Sinai School of Medicine Team
Dr HELEN VLASSARA, Director Division of Experimental
Diabetes and Aging Division, Dept. of Geriatrics
Weijing Cai
Cijiang He
Jaime Uribarri
Susan Goodman
Elliot Rayfield
Juan Badimon
Feng Zheng
Sylvan Wallenstein
Collaborators
Luigi Ferrucci Nat. Inst. Aging Baltimore, MD
Edward Fisher New York Univ NY,NY
Carl Schulman M.S.SM, U. Miami, Miami, FL
Maria Alevizaki
Athens Med School Greece
Melpomeni Peppa Athens Med School Greece
Theodore Koschinsky Diabetes Research Institute Dusseldorf, GE
Arlin Stirban Tubingen U Tubingen, GE
21