The Mitochondria in Ischemic Disease - Cardiologia Molinette

©2011 MFMER | slide-1

Advances In Cardiac Arrhythmias and Great Innovations In Cardiology, Turin, Italy, 23-25 October, 2014

The Mitochondria in Ischemic Disease

Lilach O. Lerman, MD, PhD Professor of Medicine and Physiology Division of Nephrology and Hypertension Mayo Clinic, Rochester, MN

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Bio-energetic paradigm for metabolic and degenerative diseases, cancer, and aging

Wallace, JCI 2013

OXPHOS, oxidative Phosphorylation

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Mitochondrial Injury in Ischemia

http://www.frontiersin.org/aging_neuroscience/10.3389/fnagi.2010.00138/full

The opening of the mPTP ultimately results in mitochondrial swelling, mitochondrial Ca2+ efflux and the release of apoptogenic proteins, such as cytochrome c and pro-caspases, from the inter-membrane space

Mitochondrial permeability transition pore (mPTP): A conductance pore that spans the inner and outer mitochondrial membranes

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Mitochondria as a Therapeutic Target

Bayeva M, Gheorghiade M, Ardehali H. J Am Coll Cardiol 61: 599-610, 2013.

Mitochondrial Biogenesis Adenosine monophosphate kinase (AMPK) agonists, stimulants of NO/cGMP pathway, or resveratrol can stimulate nuclear-encoded proteins peroxisome proliferator–activated receptor gamma coactivator 1 (PGC1), nuclear respiratory factor (NRF)1/2, and transcription factor A (Tfam), which, in turn, facilitate production of new mitochondria in the heart.

Mitochondrial Iron Mitochondria regulate cellular iron balance. However, accumulation of iron can catalyze generation of ROS. Reducing mitochondrial iron through mitochondria-permeable iron chelators can potentially protect failing hearts.

Mitochondrial production of reactive oxygen species Mitochondrial electron transport chain (ETC) complexes and NAD(P)H oxidase 4 (Nox4) might generate excessive ROS, and mitochondria are sensitive to oxidative stress. Various approaches have been applied for targeting antioxidants to mitochondria, including MitoQ, MnSOD/catalase mimetics, and Szeto-Schiller peptides (Bendavia).

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• Small synthetic peptides (<10 amino acids)

• Stable in aqueous solution, resist peptidase degradation

• Passive diffusion into

a variety of cell types

• Mitochondrial uptake

~x1,000-5,000

Mitochondrial Targeted Peptides

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Bendavia (SS-31) stabilizes cardiolipin

Cardiolipin

Courtesy of Stealth Biopharmaceuticals, Inc.

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Kloner et al: J Am Heart Assoc 1, 2012

Reduction of Ischemia/Reperfusion Injury with Bendavia, a Mitochondria-Targeting Cytoprotective Peptide

Postischemic administration of Bendavia protected against reperfusion injury in several distinct models of injury

Infarct Size in Isolated Guinea Pig Hearts Exposed to Ischemia/Reperfusion (20 min/2h)

0

10

20

30

40

50

60

70

Infa

rct s

ize

(% a

rea

at ri

sk)

Treatment

Control 1 nM Bendavia whole time 1 nM Bendavia @ reperfusion 0.2 uM cyclosporine-A @ reperfusion

n=14 n=9 n=9 n=8 Mitochondria-produced reactive oxygen species may be centrally involved in each aspect of reperfusion injury

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Bendavia reduces atherosclerotic plaques in ApoE K/O Mice

Rader et al 2012

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Mitochondrial injury in Experimental Ischemic Renal

Disease in Pigs

1. Revascularization (acute reversal of ischemia and hypertension)

2. Chronic atherosclerotic renal artery stenosis (chronic ischemia & renovascular hypertension)

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Bendavia 0.05 mg/kg/hr or vehicle infusion (IV)

• Bendavia given after established Atherosclerotic Renal Artery Stenosis (ARAS)

• One IV dose during Percutaneous Transluminal Renal Angioplasty (PTRA) & Stenting with assessments 4 weeks later

(Atherogenic)

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Renal outcomes 4 weeks after PTRA

* p<0.05 vs. Normal, ‡p<0.05 vs. ARAS+PTRA+Bendavia

0

200

400

600

800

0

20

40

60

80

100RBF (ml/min) GFR (ml/min)

* * * * ‡ ‡ ‡ ‡

ARAS+PTRA +Bendavia

ARAS+PTRA +Vehicle

ARAS NORMAL

0

50

100

150

200

250

1 11 21 31 41 51 61 71

PTRA or Sham

Days

Mea

n ar

teria

l pre

ssur

e (m

mH

g)

ARAS+PTRA +Bendavia

ARAS+PTRA +Vehicle

ARAS NORMAL

6 weeks of stenosis 4 weeks after PTRA

NORMAL ARAS ARAS+PTRA+Vehicle ARAS+PTRA+Bendavia

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Bendavia Improves Renal Mitochondrial Biogenesis, and Decreases Apoptosis & Oxidative Stress

* p<0.05 vs. Normal, ‡p<0.05 vs. ARAS+PTRA+Bendavia

TUN

EL NORMAL ARAS ARAS+PTRA

+Vehicle ARAS+PTRA +Bendavia

DH

E

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

PGC-1α NRF-1 GABP

* * ‡ ‡

*

* * ‡ ‡

Pro

tein

exp

ress

ion

(R

elat

ive

to G

AP

DH

)

NORMAL ARAS ARAS+PTRA+Vehicle ARAS+PTRA+Bendavia

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Bendavia Increases Microvascular Density and Decreases Fibrosis in the Post-Stenotic Kidney

Tubulointerstitial fibrosis

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Normal RVHT Low

High

Oxygenation

Eirin A et al, J Hypertens 32: 154-65, 2014

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Eirin A, et al. Cardiovasc Res 103: 461-72, 2014.

Bendavia (0.1 mg/kg) or Vehicle (SC)

Start diet RAS in vivo studies

Euthanasia + in vitro studies

6 weeks 6 weeks 4 weeks 1 week

Sham

ARAS+Vehicle ARAS+Bendavia Normal+Bendavia Normal+Vehicle

Cardiolipin

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Renal Function After 4 Weeks of SC Bendavia

0

200

400

600

800

1000

RB

F (m

l/min

)

0

20

40

60

80

100

GFR

(ml/m

in)

Normal+ Vehicle

Normal+ Bendavia

ARAS+ Bendavia

ARAS+ Vehicle

* ‡ *

‡

* ‡

* p<0.05 vs. Normal+Vehicle, ‡ p<0.05 vs. ARAS+Bendavia, # p<0.05 vs. Baseline

# # #

NORMAL+Vehicle ARAS+Vehicle ARAS+Bendavia NORMAL+Bendavia

BOLD-MRI

Baseline Response to Ach

50

60

70

80

90

100

110

Rel

axat

ion

effe

ct (%

)

Ach

NORMAL+VEHICLE NORMAL+Bendavia ARAS+VEHICLE ARAS+Bendavia

* †

* †

* † *

† * †

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Bendavia Decreases Stenotic Kidney Injury M

edul

la

Cor

tex

DHE

ARAS+Vehicle ARAS+Bendavia Normal+Bendavia Normal+Vehicle

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Attenuated myocardial remodeling in renovascular hypertension (RVHT)

50μm

αSM

A

Normal+Vehicle Normal+Bendavia RVHT+Vehicle RVHT+Bendavia

50μm

50μm Siriu

s R

ed

H&

E

0,3

0,4

0,5

0,6

0,7

* †

* Media-lumen ratio

Normal+Vehicle Normal+Bendavia RVH+Vehicle RVH+Bendavia

400

600

800

1000 * †

*

Myocyte cross sectional area (μm²)

0

1

2

3

4

* †

* † Area (%)

Sirius Red Trichrome

0,0

0,5

1,0

1,5

2,0

E/A

ratio

Diastolic Function

†*

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A Phase 2a, Randomized, Placebo-controlled, Single Center Trial to Evaluate the Impact of Intravenous Bendavia-131 on Ischemia Reperfusion Injury in Atherosclerotic Renal Artery Stenosis in Patients Undergoing Percutaneous Transluminal Angioplasty of the Renal Artery (PTRA)

ClinicalTrials.gov Identifier: NCT01755858, IRB: 12-002947

A phase 2a, randomized, double-blind, placebo-controlled trial to evaluate the safety, tolerability and efficacy of intravenous Bendavia on reperfusion injury in patients treated with standard therapy including primary percutaneous coronary intervention and stenting for ST-segment elevation myocardial infarction

Clinical Trials

EMBRACE-STEMI Study: Evaluation of the Myocardial effects of Bendavia for reducing Reperfusion injury in patients with Acute Coronary Events — ST-wave Elevation Myocardial Infarction.

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Conclusions • The mitochondria are fundamental therapeutic targets in ischemia

• Mitochondrial-targeted peptides possess a unique potential to decrease ischemic damage in the kidney and heart • Acute • Chronic

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Questions?