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Application of Systems Pharmacology to
Analyze Risk of Thrombosis Resulted from
Administration of Anti-Inflammatory Drugs
Yuri Kosinsky, Sergey Smirnov and Oleg Demin
Institute for Systems Biology SPb, Moscow, Russia
Shanghai, IDDST2009
Outline
• Biomarkers vs disease progression vs drug
efficacy and safety
• Systems Pharmacology Modeling Strategy
• Application of the Strategy to the problem
of adverse effects of Non Steroidal Anti
Inflammatory Drugs
Biomarkers vs disease progression vs drug efficacy and safety
A biomarker, or biological marker, is in general a substance used as an
indicator of a biological state. It is a characteristic that is objectively
measured and evaluated as an indicator of normal biological processes,
pathogenic processes, or pharmacologic responses to a therapeutic
intervention
Two challenges interconnecting disease progression, drug efficacy
and biomarker issues:
• HOW to identify an optimal set of biomarkers which is reliably
describe drug efficacy and safety at any state of disease
• HOW to understand what knowledge about drug and disease can
be extracted from measurements of a given set of biomarkers
Our solution: Systems Pharmacology Modeling Approach
Systems Pharmacology Modeling (SPM) Strategy
1. Identification of biological system of interest. Mining all possible information about the system
(organs, tissues and types of cells involved, intercellular and extracellular interactions, structural and kinetic properties of
proteins/enzymes involved)
2. Identification of the main players (proteins, enzymes low molecular weight molecules) and reconstruction
of events (signaling, metabolic and genetic networks…) and regulations at different levels (inhibitions,
activations, induction, repression …)
3. Development of appropriate mathematical model of the biological system and its verification
against experimentally established facts and reliable data
4. Development of mathematical model describing PK of the drug, its influence on intracellular
pathways and possible PD endpoints
5. Application of the model (i) to understand functioning and regulation of the system at normal
and pathological states, (ii) to distinguish between drug and system determinants of a
pharmacological response, (iii) to understand mechanisms underlying adverse effects and (iv)
to address the “biomarker” challenges
Modeling techniques combined in SPM:
• pathways modeling
• mechanism based PK/PD modeling
• PBPK modeling
• cell dynamics modeling
• physiological modeling
Final Model
represents system of Algebraic and
Ordinary Differential Equations
Demin O., Goryanin I. Kinetic Modelling in Systems Biology.
Taylor & Francis (United States), (2008), pp.360
Example:
•NSAIDs side effects
NSAIDs safety problem • NSAIDs – popular drugs for pain relief and antipyretic, more
recently started to be used in cancer and even depression.
• Main targets – COX1,2
• Wide range of adverse effects
• Aspirin – risk of gastro-intestinal bleeding
• Selective COX-2 inhibitors (Coxibs) - efficient in pain relief but with unfavourable side effects (heart attacks)
• The exact mechanism of NSAID action, and the origin of many undesirable adverse effects still remain poorly understood.
• Biomarkers to characterize Coxibs adverse effects: prostacyclin (PGI2) and thromboxane A2 (TXA2)
AIM OF THE MODELING EXERCISE: Applying our strategy (1)
to understand mechanism of Coxibs mediated increase in
probability of clot formation and (2) to demonstrate that PGI2 and
TXA2 are reliable biomarkers able to follow this adverse effect in
vivo
What we know about biological system of interest
• What cells contribute mainly to prostanoid (PGI2 and TXA2) concentrations
in blood?
- Endothelium cells produce PGI2
- Platelets produce TXA2
• Concentrations of PGI2 and TXA2 in plasma can modulate the intracellular
Ca2+ concentration in both endothelium cells and platelets via signaling
pathways.
• The production rate of PGI2 and TXA2 is governed by intracellular Ca2+
concentration.
• Risk of clot formation is proportional to concentration of Ca2+ in platelets
• All these cells belong to blood circulation system
• Model of Prostaglandin H synthase taking into account its inhibition with
various NSAIDs has been developed and verified against in vitro
experimental data.
• Models of all individual enzyme catalyzed and degradation processes
involved in biosynthesis and signaling pathways initiated by PGI2 and
TXA2 in platelets and endothelium cells have been developed and verified
against in vitro experimental data
• Models of biosynthesis of prostanoids and signaling pathways initiated by
them in platelets and endothelium cells (EC) have been developed on the
basis of the models of individual processes and verified against
experimental data measured in cell culture.
• Model of human blood circulation system has been developed. Models of
endothelium cells and platelets developed at “cellular level” have been
integrated into model of blood circulation
Reaction level
Cellular level
Organ level
What modeling efforts have been done
Mogilevskaya E., Bagrova N., Plyusnina T., Gizzatkulov N., Metelkin E., Goryacheva E., Smirnov S., Kosinsky Y.,
Dorodnov A., Peskov K., Karelina T., Lebedeva G., Goryanin I. and Demin O. Kinetic modeling as a tool to integrate
multilevel dynamic experimental data. Methods Mol Biol. (2009), 563, 197-218
Explanation of Coxibs mediated increase in probability of clot formation
PGI2 and TXA2 are reliable biomarkers able to follow this adverse effect in vivo
The Cyclooxygenase Reaction
Arachidonic acid + 2O2 PGG2 + H2O PGG2 PGH2
The enzyme has two activities: Cyclooxygenase and peroxidase
Cyclooxygenase (COX) is a membrane bound enzyme responsible for the
oxidation of arachidonic acid to Prostaglandin G2 (PGG2) and the subsequent
reduction of PGG2 to prostaglandin H2 (PGH2).
reaction level cellular level organ/organism level
Main assumptions in our model:
• COX is a bifunctional enzyme with two distinct activities: cyclooxygenase (COX) and peroxidase (POX)
• Radical mechanism of COX functioning
• Self-inactivation of COX and POX activity
• Two isoforms COX-1 and COX-2
23 enzyme states and 55 reactions considered in the model
reaction level cellular level organ/organism level
Goltsov A., Maryashkin A., Swat M., Kosinsky Y., Humphery-Smith I., DeminO., Goryanin I., Lebedeva G. Kinetic
modelling of NSAID action on COX-1: focus on in vitro/in vivo aspects and drug combinations (2009) Europ J
Pharmac Sciences. 36(1), 122–136.
The model of Prostaglandin H synthase has already been presented at IDDST-2009 by
Dr. Alexey Goltsov (section 3-13 “Current Strategies of Bioequivalence…”)
Kinetic model of Cox-1/2 catalytic cycle
reaction level cellular level organ/organism level
ODE system corresponding to the catalytic cycle: 23 equations, 22 parameters
120 110 100 90 80 70 60 50 40 30 20 10 0
AA
co
nsu
mption
., m
kM
2,2
2
1,8
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
Time, s
[AA]=20 mkM
2 mkM
1 mkM
0.5 mkM
Time, s
300 250 200 150 100 50 0
[Adre
nochro
me], m
kM
160
140
120
100
80
60
40
20
0
1.08 mkM
0.81 mkM
0.54 mkM
0.27 mkM
0.16 mkM
[COX-1]=1.61 mkM
Validation of the COX model
The COX model was developed and successfully validated on more than 150
independent studies globally
Rate constant Identified value Literature value
k1 40 M-1 s-1 k_1/k1= 1-3 M
k5 1.1 M-1 s-1 -
k6 0.7 M-1 s-1 -
k7 18 M-1 s-1 14 M-1 s-1
k9 332 s-1 350 s-1
k_in1 0.011 s-1 0.013 s-1
All kinetic parameters (22 in total) of COX catalytic cycle were identified:
•Validated kinetic model can be used for analysis / prediction of the enzyme interaction with the inhibitors
reaction level cellular level organ/organism level
Effects of inhibitors (NSAIDs)
introduced to the COX model:
•Aspirin + - 1,2
•Indomethacin + + 1,2
•Naproxen 1-,2+ + 1,2
•Diclofenac + + 1
•Ibuprofen - + 1,2
•Celecoxib 1-,2+ + 2
•Rofecoxib 1-,2+ + 2
Time
dependence Reversibility
of binding
Selectivity to
COX1,2
1- COX1; 2 - COX2
reaction level cellular level organ/organism level
The model allows for consistent description of experimental data on
inhibitory effects of different types of NSAIDs in vitro
1,2 Preincubation time, sec
Aspirin
0.8 mM
2.35 mM
4.36 mM
0
0,2
0,4
0,6
0,8
1
1,2
0 1000 2000 3000 4000 5000
Rela
tive
CO
X a
cti
vit
y
Preincubation time, sec
Indomethacin
2.2 M
3.8 M
5.4 M
0
0,2
0,4
0,6
0,8
1
0 500 1000 1500
1.4 M
Rela
tive
CO
X a
cti
vit
y
0
20
40
60
80
100
0 200 400 600 800 1000 1200
Ibuprofen concentration, M
Ibuprofen
Rela
tive
CO
X a
cti
vit
y
Experimental data from:
Varfolomeev S.B.
Prostaglandins - molecular
biological regulators. 1985.
Publishing Moscow State
University. in Russian
Points – experimental data; Curves – model predictions
1
Re
l C
OX
-2 a
cti
vit
y
Celecoxib
0.5 M
1 M
2 M
0
0,2
0,4
0,6
0,8
0 10 20 30 40 50 60 70
Experimental data
from: Gierse J. K. et
al Kinetic basis for
selective inhibition of
cyclo-oxygenases.
Biochem. J. (1999)
339, 607-614
Preincubation time, sec
reaction level cellular level organ/organism level
Conclusions derived from COX modeling (presented at
IDDST talk of Dr. Alexey Goltsov; section 3-13 “Current
Strategies of Bioequivalence…”):
• Model explains the discrepancy between in vitro/in vivo estimates of IC50 for Aspirin
• Model predicts that selectivity for Celecoxib in vivo depends on substrate concentration
reaction level cellular level organ/organism level
AA
PLA2
COX-1,-2
PGH2
TXAS
HHT TXA2
TXB2
inactivation…
Ph.Lip.-AA
PGH2 (ext)
TXB2 (ext)
AA (ext)
cAMP
ATP
PKA
IP3R
Ca2+
AC
Ca2+ ER
PLC
IP3
PIP2
AMP
Ca-
ATPase
degradation
PGE2 (ext)
R1
Gq
R2
Gs
thrombin,
TXA2 (ext)
TXA2 (ext)
PKC
degradation
DAG
PGE2
PGES
PGI2 PGI2 (ext)
PGIM (ext)
PGIS
PGI2 (ext) ,
iloprost (IP);
PGD2(ext) (DP)
Endothelium cell model • prostanoid biosynthesis (PGI2, PGE2, TxA2)
• transmembrane transport
• signalling pathways activated by prostanoids
• Ca2+ fluxes involved in EC activation
• NSAIDs action on cyclooxygenase
reaction level cellular level organ/organism level
ODE system:
47 equations,
69 rate laws,
184 parameters
Model validation: I. Endothelium cells response to thrombin stimulation Data from Journal of Cellular Physiology
(1988), 136: 54-62 Ca Time-dependence, model description
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0 0,5 1 1,5 2 2,5 3
Time, min
Ca
, u
M
0,01 uM, TXA2
0,1
1
10
0,05
0,5
II. Prostaglandin biosynthesis by HUVEC cell culture as a response to addition of 25 M AA
Data from Circ. Res. 1998;83;353-365
Синтез PGH2 в HUVEC
0
200
400
600
800
1000
1200
0 20 40 60 80 100AAext, uM
PG
H2e
xt, p
mol
/10^
6 ce
lls
exp
model
Thrombosis Research 99 (2000) 155–164
PGD2 (ext)
TXA2 (ext)
AA
PLA2
COX-1
PGH2
TBXAS
HHT TXA2
TXB2
inactivation
Ph.Lip.-AA
PGH2 (ext)
TXB2 (ext)
AA (ext)
cAMP
ATP
PKA
IP3R
Ca2+
AC
Ca2+ ER
PLC
IP3
PIP2
AMP
Ca-
ATPase
degradation
PGE2 (ext)
R1
Gq
R2
Gs
thrombin,
ADP,
TXA2 (ext)
PGI2 (ext) ,
iloprost (IP);
PGD2(ext) (DP)
PKC
degradation
DAG
Platelet model • TXA2 biosynthesis
• transmembrane transport
• signalling pathways activated by prostanoids
• Ca2+ fluxes involved in platelet activation
• NSAIDs action on cyclooxygenase
reaction level cellular level organ/organism level
ODE system:
42 equations,
62 rate laws,
152 parameters
Model validation: Platelet response to thrombin stimulation is
inhibited by iloprost (prostacyclin stable analog)
Model demonstrates that high dose of iloprost
effectively inhibits platelet activation by thrombin.
Stimulation of platelet IP receptors by iloprost leads to cAMP-dependent
PKA activation that phosphorilates IP3-dependent calcium channels (IP3R)
on endoplasmic reticulum (ER). This results in decrease of IP3R sensitivity
to IP3 and inhibition of Ca2+ flux from ER to cytoplasm
Model demonstrate that preincubation of
platelets with iloprost completely inhibits their
sensitivity to thrombin…
So, platelets model demonstrate at least qualitively
agreement with in vitro experimental data…
Time
10 9 8 7 6 5 4 3 2 1 0
Co
nc
en
tra
tio
n,
M
4
3.8 3.6
3.4
3.2 3
2.8 2.6
2.4 2.2
2 1.8
1.6 1.4 1.2 1
0.8
0.6 0.4
0.2
0
Time 10 9 8 7 6 5 4 3 2 1 0
Co
nc
en
tra
iotn
,
M
4 3.8
3.6
3.4 3.2
3 2.8
2.6
2.4 2.2
2 1.8
1.6 1.4
1.2
1 0.8
0.6 0.4
0.2
0
Data from JBC(2002)277:29321
Ca2+
iloprost
thrombin
COX-1
IP3 cAMP
thrombin
iloprost
Ca2+
cAMP
IP3
COX-1
“Two cell model” takes into account:
1) Three compartments: endothelium cell, platelet and blood
2) Platelets express COX-1 only
3) Endothelium cells express COX-1 at normal conditions and both COX-1
and COX-2 at inflammation
4) Endothelium cells produce prostacyclin but platelets produce TXA2
5) Both endothelium cells and platelets produce PGD2, PGE2 and PGF2a
6) Both endothelium cells and platelets can export/import PGH2
Models of endothelium cell and platelet
have been combined
The aim of development of the model is to understand
how clot formation depends on COX-1 and COX-2 inhibition
reaction level cellular level organ/organism level
ODE system: 95 equations, 137 rate laws, 325 parameters
reaction level cellular level organ/organism level
System:
platelets (COX1) +
inflammatory EC
(COX1,2)
Inhibitors:
COX2 selective
(selectivity =
Kd_Cox1/Kd_Cox2);
selectivity of celecoxib
and rofecoxib is equal to
10 and 100,
correspondently.
Risk of clot formation is
proportional to
concentration of Ca2+
in platelets
Rofecoxib
Celecoxib
Model predicts
(1) Ca2+ concentration in platelets is able to increases with increase in
COX2 selective inhibitor concentration
(2) More selective inhibitor results in more significant increase in platelet
Ca2+ concentration
Calculated dose dependence of intracellular platelet Ca2+ concentration
reaction level cellular level organ/organism level
Model explains that
(1) Administration of COX2 selective inhibitor results in decrease in PGI2 synthesis and, consequently,
PGI2 extracellular concentration
(2) Decrease in PGI2 concentration results in decrease in inhibition of Ca2+ release from ER
(3) Decrease in inhibition of Ca2+ release results in increase in Ca2+ concentration in platelets
(4) increase in platelet Ca2+ concentration results in increase in risk of clot formation
How “two cell” model explains this phenomena
Ca2+ Ca2+
COX-1
COX-2 COX-1
PGI2
TXA2
Ca2+ Ca2+
COX-1
COX-2 COX-1
PGI2
TXA2
COX-2 selective
inhibitor
no inhibitor
platelet endothelium cell
On the basis of the MODEL we can predict response of the platelets
and endothelium cells to inflammation and different NSAIDs
BUT
we cannot calculate concentrations of biomarkers (PGI2 and
TXA2) and compare their profiles with risk of clot formation (Ca2+
concentration in platelets) at different parts of blood circulation
system in vivo.
“Classical” PBPK and PK/PD models do not allow us to solve the
problem, i.e. predict probability of clot formation and biomarker
concentrations on the basis of knowledge about intracellular
processes.
reaction level cellular level organ/organism level
We developed mathematical model of blood circulation and
integrated into it kinetic models of platalets and endothelium cells
reaction level cellular level organ/organism level
Heart
muscle
Head
(Brain)
AORTA
LUNG Upper
body
(arms)
Kidneys
GIT
Live
r VENA CAVA
Lower body
(Legs)
reaction level cellular level organ/organism level
Kinetic model of
endothelium cell
Endothelium
cells
Platelets Kinetic model
of platelet
Model of blood circulation takes into
account 1) Several phases (immobile, mobile,…)
2) Several cell types
3) Interaction between different cells via secreted
metabolites
4) Kinetic description of intracellular processes of
each cell type
5) Anatomical/geometrical features of the system
6) Changes in properties of the cells located at
different parts of the system
8 organs have been taken into
account in our models
The model of blood circulation system has been applied
1) To monitor ability of plateles to form a clot (risk of clot formation) in
different parts of blood circulation system
2) To monitor TXA2/PGI2 ratio in different parts of blood circulation
system
3) To compare the profile of biomarker concentration ratio
(TXA2/PGI2) with risk of clot formation at different part of
circulation system and to demonstrate that TXA2/PGI2 is reliable
biomarker able to follow this Coxibs adverse effect in vivo
reaction level cellular level organ/organism level
reaction level cellular level organ/organism level
Scheme of virtual experiment 1) Wound in leg capillaries
2) Release of soluble PAFs –
platelet activation factors
(TXA2,…)
3) Distribution of the PAFs
resulted from blood stream
4) Monitoring state of platelets
moving along with PAFs
Heart
muscle
Head
(Brain)
AORTA
LUNG Upper
body
(arms)
Kidneys
GIT
Liver
VENA CAVA Lower body
(Legs)
Thrombus
Platelets
Soluble platelet activating
factors (TXA2)
WOUND
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
iTX
A2
co
nce
ntr
ati
on
(n
M) T = 0.75 min
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
iTX
A2
co
nce
ntr
ati
on
(n
M) T = 1.5 min
PAFs introducing
(activation zone) Spatial distribution of PAFs (TXA2,…) in leg compartments at
different time after initial point
flow direction A
ort
a
Ve
na c
ava
arteries
capillaries venules veins
1) PAFs wave is damped due to PAFs degradation and dilution
2) It takes about 1.5 - 2 minutes that PAFs wave arrives at place of its initiation (capillaries of legs)
reaction level cellular level organ/organism level
Heart
muscle
Head
(Brain)
AORTA
LUNG Upper
body
(arms)
Kidneys
GIT
Liver
VENA CAVA Lower body
(Legs)
Thrombus
Platelets
Soluble platelet activating
factors (TXA2)
WOUND
Monitoring state of platelets moving along with PAFs
Way passed by Platelets:
Legs – Vena Cava – Lung –
Heart muscle/Arms
Dynamic of platelet intracellular Ca2+ concentration after local activation
0
0.05
0.1
0.15
0.2
0.25
0.3
0 0.5 1 1.5 2 2.5 3
Time after activation (min)
Intr
acellu
lar
Ca2+ c
on
cen
trati
on
(µM
)
ca
pil
lari
es
& v
en
ule
s
veins
lung
ve
na
ca
va
ao
rta
ve
na
ca
va
lower body (legs) c
ap
illa
rie
s
art
eri
es
&
art
eri
ole
s
Activation
(TXA2)
veins
ca
pil
lari
es
& v
en
ule
s
upper body (arms)
reaction level cellular level organ/organism level
Monitoring state of platelets moving along with PAFs
1) Maximal risk of clot formation (Ca2+ concentration in platelets) is observed in leg veins
2) Capillaries of lungs and arms decrease risk of clot formation substantially
Spatial distribution of TXA2/PGI2 ratio (at 1.65 min)
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
TX
A2
/PG
I2 r
ati
o
upper body (arms)
ve
na c
ava
lung
heart
ve
na c
ava
ao
rta
ao
rta
Art
eri
es
Art
eri
ole
s
Cap
illa
rie
s
Cap
illa
rie
s
Cap
illa
rie
s
Venules Veins
reaction level cellular level organ/organism level
1) TXA2/PGI2 ratio increases substantially in veins of arms
2) Capillaries of lungs, heart and arms decrease substantially TXA2/PGI2 ratio
CONCLUSIONS
• Systems Pharmacology Modeling allows us to understand
regulatory mechanisms underlying adverse effects of anti-
inflammatory drugs at the reaction, cellular and organ levels
• We have demonstrated that ratio of TXA2/PGI2 is reliable
biomarker able to follow Coxibs adverse effect in vivo at any part of
blood circulation system. In particular, capillaries of lungs, heart
and arms decrease substantially both TXA2/PGI2 ratio and Ca2+
platelet concentration, i.e. risk of clot formation.
http://www.insysbio.ru
Thank you for attention!
Our team:
Modelers Yuriy Kosinskiy
Galina Lebedeva
Alexey Goltsov
Tatiana Plyusnina
Ekaterina Mogilevskaya
Evgeniy Metyolkin,
Aleksandr Dorodnov
Kirill Peskov
Tatiana Karelina
Ekaterina Goryacheva
Sergey Smirnov
Nataliya Bagrova
Anton Maryashkin
Acknowledgements: Edinburgh University, Biosystems
Informatics Institute
http://www.insysbio.ru
Scientific programming
Nail Gizzatkulov
Aleksandr Galchenko