Immune response and inflammation

Handono Kalim

Department of Internal MedicineFaculty of Medicine, University of Brawijaya, Malang

“Silent killer”; TIME March,1,2004

The immune system

Infectious or inflammatory trigger

Innate or natural response Acquired or adaptive response

Same extent each time

Uses phagocytic cells

• PMNs• Monocytes• Macrophages

Cells release mediators

Complement, APR,cytokines

Involves proliferation ofantigen specific T and B cells

Antigen presenting cells display antigen

T cells help B cells, assist macrophages , and kill cells

Complement, APR, cytokines

Innate immune response

Mast cell Fibroblast Macrophage

VESSELS

CONNECTIVETISSUECELLS

CONNECTIVETISSUEMATRIX

Endothelium Basement membrane:Collagen type IVLamininFibronectinProteoglycansOthers Elastic fibers Collagen fibers Proteoglycans

Basophil

EosinphilMonocyte

Platelets

LymphocytePolymorphonuclear

leukocyte

Intra vascular cells and connective tissue matrix and cells involved in the inflammatory response

B lipoproteinsB lipoarabinomannansLPS (Lestospira, P. gingivalis)Peptidoglycan (Gram-positive)Zymosan (yeast)GPI anchor (T. Cruzi)

LPS (Gram-negative)Taxol (plant)Viral proteinsHsp60 (host)Fibronectin (host)

ViraldsRNA

IgG1,IgG3 (host)

MICA (host)

HLA-E (host)

MHC class I (host)Viral

hemagglutinin

BacterialCpG DNABacterial

flagelline

TLR2/TLR1 or 6

TLR3

TLR5TLR9

TLR4/MD2

DC/MCD16 NK

cellNKp46

KIR/DAP12

CD94NKG2A or C

NKG2D/DAP10

Recognition of danger by the innate immune system

Components of innate immunity

Humoral or cellular immune response

Antigens

Foreigh proteins Viruses

BacteriaParasites

Fungi

Vertebrate body

CELL MEDIATED RESPONHUMORAL RESPONSE

+

B cellT cell

TH cell

ActivatedTH cell

+Ag-class IIMHC molecule

+Ag-classIMHC molecule

CTL

Altered self cell

Cytokinesecretion

Killing ofAltered self-cell

Antigen

Ab-secretingPlasma cells

Antigen elimination

Antibody

Molecular interaction that mediate naïve T lymphocyte activation by APC

IL-4IL-5IL-10IL-13

Th2cell

IL-4

Tr1cell

IL-10TGF-

Th1cell

IFN-TNF-

IL-10

IL-12, IL-18

NaïveT cell

Antigenpresentation

Co stimulation

Internalization

TLR

Pathogen

APC

Recognition

Effector Mechanisms of Humoral Immunity

Mechanisms in Rheumatology ©2001

Th2 effector functions

Effector function of antibodies

B cell

Microbe

Antibodies

Fc receptor

Cb3 receptor

Complement activation

Lysis of microbe

InflammationComplement activation

Phagocytosis of microbes opsonized with complement fragments ( e.g.,C3b)

Opsonization and phagocytosis of microbe

Neutralization of microbe and toxins

Effector Mechanisms of Cellular Immunity

Mechanisms in Rheumatology ©2001

Click here to run the animation

Th1 effector functions

Types of cell-mediated immune responses

IFN- /

IFN- / receptor

Protein kinasePKR (inactive)

PKR (activated)

+ ATP and dsRNA

2-5(A) synthase

ATP 2-5 (A)

Phosphorylationof elF-2

InactiveRNAse L

ActiveRNAse L

Degradation ofpoly (A)mRNA

elF2-GDP(nonfunctional)

INHIBITION OF PROTEIN SYNTHESIS

Induction of antiviral activity by IFN- and -

Immune Protection VS Immunopathology

Immune pathologic : abnormalities in physiology of adaptive immune responses

• Specificity

• Diversity

• Memory

• Specialization

• Self limitation

• Non reactivity to self

Mechanisms of the decline of normal immune responses (homeostasis)

Tissue destruction by mediators

derived from neutrophil activation

Bacterial products, immune complexes, toxins,

physical injury, other cytokines

MACROPHAGES (AND OTHER CELL) ACTIVATION

IL-1/TNF

ACUTE-PHASE REACTIONS Fever Sleep Appetite Acute phase proteins Hemodynamic effects (shock), neutrophilia

ENDOTHELIAL EFFECTS Leukocyte adherence PGI synthesis Procoagulant activity Anticoagulant IL-1, IL-8, IL-6,

FIBROBLAST EFFECTS Proliferation Collagen synthesis Collagenase Protease PGE synthesis

LEUKOCYTES EFFECTS Cytokine secretion , priming

Major effect of IL-1 and TNF in inflammation: physiologic or pathologic ?

Biologic effects of mediators in inflammation

VasodilationProstaglandins, nitric oxide

Increased vascular permeabilityVasoactive amines, C3a and C5a (through liberating amines), bradykinin, leukotrienes C4, D4, E4, PAF, substance P

Chemotaxis, leukocyte activationC5a, leukotriene B4, chemokines, bacterial products

FeverIL-1, IL-6, TNF, prostaglandin

PainProstaglandin, bradykinin

Tissue damageNeutrophil and macrophage lysozomal enzymes, oxygen metabolites, nitric oxide

Mechanisms in Rheumatology ©2001

Balance between pro-inflammatory and anti-inflammatory cytokines

Oxygen – Derived Free radicals

• Oxygen-derived free radicals may be released extracellularly from leukocytes after exposure to chemotactic factors, immune complexes or phagocytic challenge

• Low levels of these potent mediators can increase the expression of chemokines ( e.g IL8 ), cytokines, and endothelial leukocyte adhesion molecules

• At higher levels can be damaging to the host : Endothelial cell damage, with resultant increased vascular permeability. Inactivation of antiproteases , such as a1-antitrypsin. Injury to other cell types ( tumor cells, red cells, parenchymal cells )

Mechanisms in Rheumatology ©2001

Lipid-derived inflammatory mediators

• Comprises a cascade of systemic responses upon tissue injury or infection

• Characterized by a variety of changes in organ function such as fever, leucocytosis, major laboratory changes

• In response to mayor cytokines : IL-1,IL-6 and TNF-

Changes of acute phase proteins production by hepatocyte

Protein whose plasma concentrations increase

• Complement system

• Coagulation and fibrinolytic systems

• Antiproteases

• Transport protein

• Participants in inflammatory responses

• Others

Protein whose plasma concentrations decrease

• Albumin

• Transferrin

• Insulin like growth factor

• Etc

Other acute phase phenomena

• Neuroendocrine changes• Hematopoietic changes• Metabolic changes• Hepatic changes• Changes in non protein plasma concentration

• Stimulates amino acid uptake : IL-1, IL-6, TNF , EGF

• Inhibit liver amino acid up take : TGF and IGF-I

• Enhance glucose up take : IL-6, IGF-I

• Reduced gluconeogenesis : IL-1

• Enhance glicolysis: EGF

• Inhibit fatty acids synthesis : IL-4

• Modulation of hepatic cholesterol synthesis : IL-1, TNF, IFN, EGF, PDGF

• Increased fatty acids synthesis : IFN, IL-1, IL-6

Influence of cytokines in hepatic protein , carbohydrate and lipid metabolism

Neuro – endocrine- immune interaction

Hormonal signaling of the brain by immune signals: routes of communication

•Actively carried from the blood to the brain across the blood-brain barrier

•Cross passively at certain anatomically leaky points in the blood-brain barrier

•Some cytokine effects are indirectly mediated through second messengers

•Peripheral cytokines can signal the brain via direct neuronal routes

Communication between the immune system and the CNS (humoral and neuronal)

C2A2

C1A1

LC

ImmuneSystem

Sympathetic

ACTH AVP Cyto

kines

PVN

AVPCRH

Behavior

IL-1 Neuronal Pathways

Nucleus tr solitarius

Sensory afferents

Extra cellularinsult

Proinflammatorycytokines

Adhesionmolecules

Chemokines

GlucocorticoidsAnti-inflammatorycytokines

Proinflammatorycytokines

Adhesionmolecules

Chemokines

Neuro endocrine immune interaction represent an important physiologic mechanism for modulation of the intensity of immune response, control of

susceptibility, and resistance to inflammatory disease

Physiologic role of neuro-endocrine-immune communication

Behavioral effects cytokines on the CNS

• Increased somnolence

• Loss of appetite

• Decreased mobility

• Fever, pain

• Depression, anxiety

Sickness behavior

Immune reactions, Inflammation

Pyrogenic cytokines: Il- 1,IL- 6,TNF,IFN

Hypothalamic endothelium PGE2

Glial cells : cAMP

↑Thermoregulatory set point

Heat conservation

Heat production

Fever

Chronology of events required for the induction of fever

Microbial toxins

Circulation

Inflammation ?

Chronic irritation and inflammation which may lead to neoplastic transformation

Oesophageal adeno carcinoma

Barret’s dysplasia

Intestinal metaplasia

Gastric dysplasia

Gastric adeno-carcinoma

Reflux disease

Barret’s metaplasia

H. Pylori infection

Oesophageal adeno-

carcinoma

Gastric adeno carcinoma

Inflammatory markers and clinical progression of Alzheimer’s disease dementia

IL-6, C1q mRNA

HLA-DR microglia

COX-2 protein

No dementia Questionable Mild Moderate Severe– very severe

Amyloid plaque density

Atherosclerosis : an inflammatory disease

Evidence Supporting Involvement of Infectious Agents in Atherosclerosis

Presence or absence of evidence for an infectious agents

EvidenceCytomegalo

virusHerpes virus

hominisClamidia

pneumoniae

Seroepidemiology

Atherosclerosis + - +

Transplantation

arteriosclerosis+ - -

Pathogen present in atheroma

+ +

Can produce atheroma in animals

+ +

Proof of casuality - - -

Novel Risk Factors for Cardiovascular Events in Apparently Healthy Woman

Atherosclerosis RA

B cell activation

Autoantibodies (oxLDL,

HSP)0 or 0 or

Rheumatoid factor 0 C- reactive protein (UA) Adhesion molecules (VCAM-1, ICAM-1, E-selectin,P-selectin)

Endothelin Neoangiogenesis

Possible antigensHSP, OxLDL,

Infectious agents

Collagen II, cartilage antigens ,

HSP, infectious agents

Similarities between Atherosclerosis and Rheumatoid Arthritis

Chronic inflammation

Chronic Inflammation

Chronic inflammation is an inflammation of prolonged duration in which active inflammation, tissue destruction, and attempts at repair are proceeding simultaneously

1. Persistent infections by certain microorganisms of low toxicity and evoke DTH

2. Prolonged exposure to potentially toxic agents, either exogenous or endogenous (e.g. silicosis, atherosclerosis, Alzheimer’ dementia and cancer)

3. Autoimmunity and allergy

4. Idiopathic diseases : e.g. autism, idiopathic pulmonary hypertension and myocardiopathy

INJURYAcute

inflammation

Chronic inflammation

RESOLUTION

ABSCESS FORMATION

HEALING Regeneration, scarring

Mediators

Mediators

Persistent infection, persistent toxin, autoimmune disease

Outcome of acute inflammation

Two stimuli for macrophage activation

Auto immunity

Mechanisms in Rheumatology ©2001

Anti-inflammatory cytokines: mechanisms of action

LIVER(major source)

PLASMA

Complementactivation

Factor XII (Hagemanfactor) activation

C3aC5aC3bC5b-9

anaphylaxotins

(membrane attack complex)

Kinin system (bradykin)Coagulation/ fibrinolysis system

Newly synthesized

ProstaglandinLeukotrienesPlatelet-activating factorsActivated oxygen speciesNitric oxideCytokines

CELLULAR

Preformed mediatorsin secretary granules

MEDIATORS SOURCE

HistamineSerotinLysosomal enzymes

Mast cell, basophil, plateletsPlateletsNeutrphils, macrophage

All leukocytes, platelets, ECAll leukocytesAll leukocytes, ECAll leukocytesMacrophagesLymphocytes, macrophage, EC

Chemical mediators of inflammation

Inhibition of antigen presentation by viruses

Mechanisms of how viruses may escape immune surveillance

• Negative selection of T cells if viral antigens in thymus

• Exhaustive induction and deletion of all peripheral T cells

• Viral effects on lymphocytes ( limphotoxicity, effects on function ) or interleukin production

• Down modulation of class I or II MHC or viral antigens

• Residence in privileged site ( e.g epithelial cells )

• T or B epitope escape mutant

Effector functions of antibodies

Samad TA et al. Nature. 2001;410:471-5. Woolf CJ et al. Science. 2000;288:1765-8.

Byers MR et al. In: Bonica’s Management of Pain. 2001:26-72.

EP Receptor

PKAPKC

Resting MembranePotential Increases

SNS/PN3

TTX-ResistantSodium Channel

Inflammation

P

COX-2

PGE2

Neuron Firing Threshold

Decreases

Inflammation and peripheral nerve sensitization

Dorsal horn neuron (Lamina V)

PG

COX-1

COX-2PLA2

Ca2+

PG

C-fibre terminal

Cytokines

Microglia

NMDA

Receptors

Non-NMDANK-1EP

COX-1/2?

COX-2

SP

Glutamate

GlutamateCOX-1/2?

Inflammation and central sensitization

Sensory nerve fibers

Sympathetic nerve fibers

For exampleSubstance P

For exampleNorepinephrine

Adenosine

At low neurotransmitter concentrations

(2 A1)

At high neurotransmitter

concentrations (, A2)

Proinflammatory

Antiinflammatory

Proinflammatory

Synovial tissue

Modulation of inflammatory response by neuro transmitter peripheral and sympathetic nervous system

Humoral Immunity

Pathogenic mechanism of autoimmunity

Pathogenesis of Autoimmune Disease

Susceptibility genes (usually multiple)

Triggering factors (probably environmental)

Abnormal Immune Response

Hyperactive T cells Hyperactive B cells Inadequate regulatory mechanism

Persistent pathogenic auto antibodies

Persistent pathogenic immune complexes

(Persistent damaging auto reactive T cell)

Sick syndrome

Innate and adaptive immunity to intracellular bacteria

Phagocytosis

Killing of infected cells by NK cells

Antigens

Foreign proteins Viruses

BacteriaParasites

Fungi

Vertebrate body CELL MEDIATED RESPONHUMORAL RESPONSE

+

B cellT cell

TH cell

ActivatedTH cell

+Ag-class IIMHC molecule

+Ag-classIMHC molecule

CTL

AlteredSel-cell

Cytokinesecretion

Killing ofalteredself-cell

Antigen

Ab-secretingPlasma cells

Antigen elimination

Macrophages - lymphocytes interactions in chronic inflammation

Biologic functions of the complement system

• Increased of vascular permeability and dilation , mainly by releasing histamin from mast cells ( C3a, C5a and C4a )

• C5a activates the lipooxygenase pathway of AA in neutrophil and monocytes

• Leukocyte adhesion, chemotaxis and activation (C5a) for neutrophils, monocytes, eosinophils, and basophils

• Phagocytosis : C3b and C3b1 act as opsonins and favor phagocytosis by neutrophil and macrophages which bear cell surface receptors for C3b

• C3 and C5 can be activated by several proteolytic enzymes present within the inflammatory exudate ( plasmin, lyzosomal enzymes )

Two stimuli for macrophage activation

Interactions of macrophages with lymphocytes in chronic inflammation

IL-1,TNFα

Present ag.to lymphocyte

Induction of Th1 and Th2 immune responses

Hours Days

Time after infection

Complement

6 12 1 3 5

NK cells

Phagocytes

Epithelialbarriers

Microbe

T lymphocytes

B lymphocytes Antibodies

Effector T cells

Adaptive immunityInnate immunity

0

Innate and adaptive immunity

Interaction of plasma protease in inflammation

Innate and adaptive immune responses to viruses

Protection against infection

Eradication of established infection

Mechanisms of how viruses may escape immune surveillance

• Negative selection of T cells if viral antigens in thymus

• Exhaustive induction and deletion of all peripheral T cells

• Viral effects on lymphocytes ( limphotoxicity, effects on function ) or interleukin production

• Down modulation of class I or II MHC or viral antigens

• Residence in privileged site ( e.g epithelial cells )

• T or B epitope escape mutant

IFN- /

IFN- / receptor

Protein kinasePKR (inactive)

PKR (activated)+ ATP and dsRNA

2-5(A) synthase

ATP 2-5 (A)

Phosphorylation of elF-2Inactive RNAse L Active RNAse L

Degradation of poly (A)mRNA elF2-GDP (nonfunctional)

INHIBITION OF PROTEIN SYNTHESIS

Induction of antiviral activity by IFN- and -

Inflammatory reaction

Stimulation of adaptive immunity by innate immune responses

Innate immunity

Adaptive immunity

INFECTIONS, TOXINS, IMMUNE COMPLEXES, NEOPLASIA

IL-1/TNF IL-6

Hypothalamus

Prostaglandins (E)

Vasomotor center

Sympathetic nerves

Skin vasocontriction

Heart dissipation

Fever

Mechanism of fever

Vaso active amines

HISTAMIN. Causes dilation and increased vascular permeability via H1 receptors . Mostly come from mast cell , but also found in basophil and platelets, in response to:• Physical injury ( trauma, cold,or heat). • Immune reactions involving binding of Ab to mast cells.• Fragments of complement called anaphylatoxins ( C3a, C5a)• Histamin-releasing proteins derived from leucocytes.• Neuropeptides ( eg substance P).• Cytokines (IL-1,IL-8)

SEROTONIN. Present only in platelets and enterochromaffin cells.

The major local manifestations of acute inflammation

Margination of leukocytes

Chemotaxis

Chemotaxis : locomotion oriented along a chemical gradient

Chemoattractans: bacterial products and endogenous chemical mediators• Components of the complement system, particularly C5a • Products of the lipoxygenase pathway mainly leukotriene B4 (LTB4)• Cytokines, particularly those of the chemokine family (eg, IL-8 )

Inhibitors ( regulators ) of Complement Activation

• Regulation of C3 and C5 convertases by enhancing the dissociation ( decay acceleration ) of convertase complex ( e.g. decay accelerating factor _ DAF,and Factor I )

• Binding of active complement components : C1 inhibitor ( C1 INH )

• Proteins that act at the level of MAC formation ( eg CD59 : membrane inhibitor of reactive lysis )

Ultrastructure of neutrophil granules stained for peroxidase activity and their constituents

Generation of lipoxin

General properties of cytokines and chemokines

• Secretion of cytokines during immune and inflammatory response is transient and closely regulated

• Many cell types produce multiple cytokines

• The proteins are pleotrophic in that they can act on different cell types

• Cytokine effects are often redundant, can influence the synthesis or action of other cytokines

• They are multifunction, an individual cytokine may have both positive and negative regulatory actions

• Cytokines mediate their effects by binding to specific receptors on target cells

General pattern of intracellular signaling

Platelet activating factor

Antigen presentation

B cell TH cell

Cellular interactions involved in induction of immune responses

APC(dendritic cell)

Antigen Co-stimulatorysignal

TH cellT cell

receptor

Class IIMHC

TH activation

Cytokine receptorCD4

IL-2

Effector+

MemoryTH cells

IL-2IL-2IL-2

IL-2Class I MHC

CD8 Altered self cellTc cell

(a)

(b)

Antigen

Memory cell Plasma cell Memory Tc cell CTLKilling

Lysis

Granule

Nukleus

Completed pore Polymerized perforin

Perforin monomers

Schematic representation of apoptosis

Effector functions of Th1 cells

Molecular interaction that mediate naïve T lymphocyte activation by antigen

presenting cells (APC)

ANTIGEN-PRESENTINGCELL

T LYMPHOCYTE

CD54

peptide/MHC

CD80/CD86

CD40CD58

CD11a/CD18 CD4/

CD8

CD3/TCR CTLA-4

CD 28

CD154

CD 2

Two types oxide (NO) in endothelium (left) and macrophages (right)

Histologic pattern of acute inflammation

Pathways of reparative responses

after acute

inflammatory injury

Events in the resolution

of inflammation

Generation of diversity in T cell and B cell antigen receptors

L V D J C

Germ line DNA

Rearranged DNA

Rearranged DNA

Primary RNA transcript

mRNA

Aktivasi komplemen

Mikroba

C3b

Acute inflammation induced by complement activation

C5a, C4a, C3a

CR2

Sel B

Inflamasi

Lisis mikroba Opsonisasi dan fagositosis mikroba Imunitas adaptif

(imunitas humoral)

Bacteria

Toxin

C3b

C3b

C3b

Complementactivation

C3a , C4a , C5a

C3b

C3b

C3b

MacrophageLymphocyteNeutrophil

Extravasation

Mediator

Mast cell

Macrophage

!!11

C3b

22

33

44

55 Chemotaxis

Toxin neutralization

Complement-mediated lysis

Opsonization andphagocytosis

Anaphylatoxin mediatemast cell degranulation.

Mechanisms in Rheumatology ©2001

General functions of cytokines

Microbial surfacesPolysaccharides

C3 C3b

FactorB

FactorD

C3bBb C3bBb3b

Alternative pathwayC3 convertaseStabilized by

properdin

Alternative pathwayC5 convertase

ALTERNATIVE PATHWAY

C3b

C5C3

C3a C5a

C3b2a C4b2a3b

C5b

C6 C7 C8 C9

Membraneattack complex

C5-9

Also generated via plasminor lysosomal proteases

CLASSIC PATHWAY

Classic pathwayC5 convertase

Classic pathwayC3 convertase

Antigen-antibody (IgG or IgM)complex

C1 Activated C1

C4 + C2

Overview of complement activation pathways

Inhibition of antigen presentation by viruses

TERIMA KASIH