To Ενδοθήλιο στη Σήψη

To Ενδοθήλιο στη Σήψη

Σ. Ορφανός

Β’ Κλινική Εντατικής Θεραπείας Π.Γ.Ν. ΑΤΤΙΚΟΝ

Sepsis: An Urgent Healthcare Challenge More than 1400 people lose their lives to severe sepsis every day.

Definitions (ACCP/SCCM, 1991)

• Systemic Inflamatory Response Syndrome (SIRS): The systemic inflammatory response to a variety of severe clinical insults (For example, infection).

• Sepsis: The systemic inflammatory response to infection.

Relationship Between Sepsis and SIRS

TRAUMA

BURNS

PANCREATITIS

SEPSIS SIRS INFECTION SEPSIS

BACTEREMIA

Severe Sepsis

• Major cause of morbidity and mortality worldwide. • Leading cause of death in noncoronary ICU. • 11th leading cause of death overall.

• More than 750,000 cases of severe sepsis

in US annually.

Definitions (ACCP/SCCM):

• Multiple Organ Dysfunction Syndrome (MODS): The presence of altered organ function in an acutely ill patient such that homeostasis cannot be maintained without intervention.

Stages In the Development of SIRS (Bone, 1996)

• Stage 1. In response to injury / infection, the local environment produces cytokines.

• Stage 2. Small amounts of cytokines are released into the circulation: • Recruitment of inflammatory cells. • Acute Phase Response. • Normally kept in check by endogenous anti-inflammatory

mediators (IL-10, PGE2, Antibodies, Cytokine receptor antagonists).

Stages In the Development of SIRS

• Stage 3. Failure to control inflammatory cascade: • Loss of capillary integrity. • Stimulation of Nitric Oxide Production. • Maldistribution of microvascular blood flow.

• Organ injury and dysfunction.

Challenge of SIRS/MOF

• Gap between Pathophysiology and Diagnosis

• Gap between Mechanisms and Treatment

• Gap between Basic Science and Clinical Implementation

• Nonlinear Behavior => Complexity

High-risk vs

Low-risk

Sepsis is like pornography. It’s hard to define but you know it when you see it.

Clear vs

Unclear

Courtesy of Pr. J.D. Catravas

Courtesy of Pr. J.D. Catravas

Copyright ©2007 American Heart Association

Aird, W. C. Circ Res 2007;100:174-190


Aird, W. C. Circ Res 2007;100:174-190

ECs in the heart


ECs in the lung


ECs in the lung


Aird, W. C. Circ Res 2007;100:174-190

ECs in the lung

Intensive Care Med 2004; 30:1702

Anti-adhesive, anti-coagulant, fibrinolytic NO, PGI2, AT II,

TxA2, ET-1

O2, CO2

Alveolus

RBC PMN

Plt

Lymphatic drainage

caveolae Aquaporins

Vascular tone

Permeability

Gas exchange VSMC

Vessel

EC

Maniatis et al. Vascul Pharmacol 2008

NF-κB

TNF-α IL-1

LPS

Vascular

Endothelium

Neutrophil

Monocyte

TLR chemokines

eNOS ECE COX-1

NO PGI2

ET-1

smooth muscle

relaxation

constriction

Vasodilation Vasoconstriction

LPS LPS

TxA2

adhesion molecules ACE

ANG II BK

B2

ROS

LBP

iNOS

PGI2

ONOO-

COX-2 ECE

ET-1 NO

ROS

TxA2

hypoxia

LPS


Mediators of Septic Response

Pro-inflammatory Mediators

• Bacterial Endotoxin • TNF-α • Interleukin-1 • Interleukin-6 • Interleukin-8 • Platelet Activating Factor (PAF) • Interferon-Gamma • Prostaglandins • Leukotrienes • Nitric Oxide

Anti-inflammatory Mediators

• Interleukin-10 • PGE2 • Protein C • Interleukin-6 • Interleukin-4 • Interleukin-12 • Lipoxins • GM-CSF • TGF • IL-1RA

Pathophysiology of Sepsis-Induced Organ Injury

• Multiple Organ Dysfunction (MODS) and Multiple Organ Failure (MOF) result from diffuse cell injury / death resulting in compromised organ function.

• Mechanisms of cell injury / death: • Cellular Necrosis (ischemic injury). • Apoptosis. • Leukocyte-mediated tissue injury. • Cytopathic Hypoxia

Pathophysiology of Sepsis-Induced Ischemic Organ Injury

• Cytokine production leads to massive production of endogenous vasodilators.

• Structural changes in the endothelium result in extravasation of intravascular fluid into interstitium and subsequent tissue edema.

• Plugging of select microvascular beds with neutrophils, fibrin aggregates, and microthrombi impair microvascular perfusion.

• Organ-specific vasoconstriction.

Infection

Microbial Products (endotoxin)

Cellular Responses

Oxidases Platelet

Activation Kinins

Complement

Coagulopathy/DIC Vascular/Organ System Injury

Multi-Organ Failure

Death

Coagulation Activation

Cytokines TNF, IL-1, IL-6

Pathogenesis of Severe Sepsis:

Pathogenesis of Vasodilation in Sepsis

• Loss of Sympathetic Responsiveness: • Down-regulation of adrenergic receptor number and

sensitivity, possible altered signal transduction.

• Vasodilatory

• Endotoxin has direct vasodilatory effects.

• Increased Nitric Oxide Production. • Inflammatory Mediators.

NF-κB

TNF-α IL-1

LPS

Vascular

Endothelium

Neutrophil

Monocyte

TLR chemokines

eNOS ECE COX-1

NO PGI2

ET-1

smooth muscle

relaxation

constriction


LPS LPS

TxA2


ANG II BK

B2

ROS

LBP

iNOS

PGI2

ONOO-

COX-2 ECE

ET-1 NO

ROS

TxA2

hypoxia

LPS


Endothelial Leukocyte Interactions in Sepsis • Endothelial cell expression of Selectins and CAMs is

upregulated in Sepsis due to inflammatory activation. • Selectins bind carbohydrate ligands on the surfaces

of PMN’s.

• ICAM bind Integrins on the surfaces of PMN’s.

• The Selectins initiate a weak bond between the PMN and the endothelial cell causing PMN’s to tumble along the vessel wall.

Pathogenesis of Endothelial Cell Dysfunction in Sepsis

• Binding of leukocytes to ICAM leads to transmigration of PMN’s into interstitium.

• Transmigration disrupts normal cell-cell adhesions resulting in increased vascular permeability and tissue edema.

• Vascular permeability is also increased by several types of inflammatory cytokines.

Pulmonary Endothelium

Macrophage

Neutrophil Lumen

IL-1 TNF-α

LPS

LPS

rolling

transmigration

IL-1

IL-1

TNF-α

prothrombotic

TNF-α

infection

PAF cytokines TxA2

NO, PGI2 t-PA

growth factors

L-selectin

E & P-selectins ET-1 L-selectin CD11/CD18

ICAM-1

adhesion β2-integrins

antithrombotic

ROS Proteases

ET-1

chemokines

IL-1

PSGL-1 capture

PECAM-1


Leukocyte-Mediated Tissue Injury

• Transmigration and release of elastase and other degradative enzymes can disrupt normal cell-cell connections and normal tissue architecture required for organ function.

• Reactive oxygen species cause direct cellular DNA and membrane damage and induce apoptosis.

NF-κΒ

PMN-PLT complex

ROS

Mediators

Myosin

Actin cytoskeletal contraction

Adhesion molecules

iNOS

RhoA

MLCK

Ca2+ AT I AT II

Ο2-

ΝΟ

-ΟΝΟΟ

Gap junction

P-selectin ACE

HSP-90

Ca2+

TNF-α

AJ disassembly

Fyn

Fluid, PMN

Maniatis & Orfanos Curr Opin Crit Care 2008

Apoptosis in Sepsis

• A physiologic process of homeostatically-regulated programmed cell death to eliminate dysfunctional or excessive cells.

• A number of inflammatory cytokines, NO, low tissue perfusion, oxidative injury, LPS, and glucocorticoids all are known to increase apoptosis in endothelial and parenchymal cells.

• Levels of circulating sfas (circulating apoptotic receptor) and nuclear matrix protein (general cell death marker) are both elevated in MODS.

Microvascular Plugging in Sepsis • Decreased red cell deformability in inflammatory states.

• Microvascular sequestration of activated leukocytes and platelets.

• Sepsis is a Procoagulant State.

• The extrinsic pathway may be activated in sepsis by

upregulation of Tissue Factor on monocytes or endothelial cells.

• Fibrinolysis appears to be inhibited in sepsis by upregulation of

Plasminogen Activator Inhibitor. • A variety of pathways result in reduced Protein C activity in

sepsis.

PMN adhesion , AT II, TxA2, ET-1

O2, CO2

Alveolar edema

RBC

PMN

Plt-PMN complex

Lymphatic drainage

caveolae Aquaporins

vasoconstriction

Clotting

Hyaline membrane

Cytokines Proteolytic

enzymes Thromboxane A2

Increased permeability

Hypoxemia EC

VSMC

Maniatis et al. Vascul Pharmacol 2008

Therapy For Sepsis

Experimental Therapies in Sepsis • Modulation of Host Response

• Targeting Endotoxin

• Anti-endotoxin monoclonal antibody failed to reduce mortality in gram negative sepsis.

• Neutralizing TNF • Excellent animal data. • Large clinical trials of anti-TNF monoclonal

antibodies showed a very small reduction in mortality (3.5%).


• IL-1 Antagonism

• Three randomized trials: Only 5% mortality improvement.

• PAF-degrading enzyme • Great phase II trial. • Phase III trial stopped due to no demonstrable efficacy.

• NO Antagonist (LNMA)

• Increased mortality (? Pulmonary Hypertension).


• Antithrombin III

• No therapeutic effect. • Subset of patients with effect when concomitant heparin

not given.

• Activated Protein C (Drotrecogin alpha / Xigris) • Statistically significant 6% reduction in mortality. • Well-conducted multicenter trial (PROWESS). • FDA-approved for use in reduction of mortality in severe

sepsis (sepsis with organ failure).

NF-κΒ

APC

Adhesion molecules

iNOS

Apoptosis

Barrier protection

PC PAR-1

TM

Thrombin Neutrophil

Endothelial Cell

EPCR

Actin cytoskeleton

Orfanos et al. 2008 Yearbook Intensive Care & Emergency Med

PULMONARY METABOLISM STUDIES in

Humans

NF-κB

TNF-α IL-1

LPS

Vascular

Endothelium

Neutrophil

Monocyte

TLR chemokines

eNOS ECE COX-1

NO PGI2

ET-1

smooth muscle

relaxation

constriction


LPS LPS

TxA2


ANG II BK

B2

ROS

LBP

iNOS

PGI2

ONOO-

COX-2 ECE

ET-1 NO

ROS

TxA2

hypoxia

LPS


Assessing Pulmonary Endothelial Angiotensin Converting Enzyme Activity

In Vivo • Pulmonary Capillary Endothelium Bound Angiotensin Converting Enzyme

(PCEB-ACE) is homogeneously expressed on the luminal endothelial surface area (ectoenzyme)

• Due to its location, PCEB-ACE is directly accessible to blood-borne substrates and inhibitors; its activity may be assessed by means of indicator-dilution techniques

• PCEB-ACE activity has been shown to be a sensitive and quantifiable index of pulmonary endothelial function in both animals and humans, in health and disease

THE BASIC PRINCIPLE 3H-Benzoyl-Phe-Ala-Pro

ACE 3H-Benzoyl-Phe

LIS = 2.7

LIS = 1.7

Circulation 2000; 102:2011




SUBJECTS & METHODS

Applying indicator-dilution type techniques, we estimated PCEB-ACE activity in nineteen (19) suffering from septic ALI/ARDS.

All patients were on severe sepsis-septic shock Patients were subsequently divided in survivors (N=9;

28-day survival) and non-survivors (N=10). Both groups were balanced for sex and age

survivors non-survivors0.00

0.40

0.80

1.20

subs

trat

e hy

drol

ysis

(v)

0

10

20

30

40

50

subs

trat

e %

met

abol

ism

v % M

*

*

survivors non-survivors0

60

120

180

240

300

PaO

2/FiO

2 (m

mH

g)

0

1

2

3

4

Lung

Inju

ry S

core

PaO2/FiO2 LIS

survivors non-survivors0

10

20

30

40

50

APA

CH

E II

scor

e

0

6

12

18

24

SOFA

sco

re

APACHE II SOFA

*

Acknowledgements

• E. Psevdi A. Kotanidou • I. Mavrommati N. Maniatis • C. Glynos • P. Kaltsas • I. Korovesi • Ch. Athanasiou • K. Kaziani • O. Livaditi

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