Transcript MACROPHAGE

THE TWO „ARMS” OF THE
IMMUNE SYSTEM
• INNATE/NATURAL IMMUNITY
• ACQUIRED IMMUNITY
WHY IS THE IMMUNE SYSTEM SO IMPORTANT?
Biomass: 90% microbes
Animal mass
PATHOGENS
< 5 – 25x
microbes
Virus
Viruses
Bacteria
Monocellular parazites
3 hours
3 hours
18 - 30 years
Multicellular parazites (helminths)
VARIABILITY
Rapid evolution
Adaptation
Selection
CHARACTERISTICS OF INNATE IMMUNITY
•
•
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•
NATURAL/INNATE
Rapid, prompt
response (hours)
No variable receptors
No improvement
during the response
No memory
Not transferable
Can be exhausted,
saturated
•
•
•
•
•
•
ADAPTIVE/ACQUIRED
Time consuming (several
days)
Variable antigen receptors
Efficacy is improving
during the response
Memory
Can be transferred
Regulated, limited
COMMON EFFECTOR MECHANISMS FOR THE
ELIMINATION OF PATHOGENS
TWO LINES OF IMMUNE DEFENSE
INNATE/NATURAL IMMUNITY
ACQUIRED/ADAPTIVE
IMMUNITY
Phagocytes
(monocyte/macrophage,
neutrophil, dendritic cell)
Killer cells (NK cell, δ T cell)
B lymphocytes (B2)
T lymphocytes
CELLS
helper T cell
cytotoxic T cell
B1 lymphocytes (CD5+)
Enzymes (lysozyme, pepsin,
trypsin)
Antibacterial peptides
HUMORAL
Complement system
FACTORS
Cytokines, chemokines
Antibodies
DEFENSE SYSTEMS
ADAPTIVE IMMUNITY
INNATE IMMUNITY
SENSING
Cells
SENSING
RECOGNITION
Receptors
RECOGNITION
SIGNALING
Signaling
pathways
SIGNALING
Cell-Cell
collaboration
RESPONSE
Effector
functions
RESPONSE
PHYSICAL BARRIERS PROTECTING OUR BODY FROM
THE ENVIRONMENT
BRONCHIAL TRACT
EYES
GASTROINTESTINAL
SYSTEM
Sinuses
Trachea
Lungs
Oral cavity
esophagus
Stomach
Intestines
SKIN
WALDEYER RING
Tonsils, adenoids
Palatinal, pharyngeal
lingual and tubar tonsils
Kidney
Bladder
Vagina
UROGENITAL SYSTEM
Damage
Infection
EPITELIAL SURFACES ARE IMPORTANT
IN THE FIRST LINE OF DEFENSE
α2-macroglobulin inhibits potentially damaging
proteases
About 10% of serum proteins are protease inhibitors.
Human defensins are variable antimicrobial peptides
Peptides of 30-40 amino acids, amphipathic character
They penetrate microbial membranes
Ongoing race between pathogens and the immune system of the host
Normal flora
Cells of human body: 90% microbes, 10% human
Symbiotic, non-pathogenic microbes
– mucosal membrane, skin
Bacteria, Fungi, Protozoa
Gut – colonalization after birth
1012 bakteria/g (1.5 kg) intestinal content
1000 species
100-times more bacterial genes then eukaryotic
„peaceful” commensalisms
vitamins (i.e. K1 vitamin)
real ecosystem, survival of the fittest,
competition with pathogenic organism
the few who brake in through the gut
epithelium induce local immune response
Important role in:
- development of mucosal and systemic immunity
- normal development of peripheral lymphoid organs
- maintenance of basic level of immunity
RECOGNITION
BY THE INNATE IMMUNE SYSTEM
INNATE/NATURAL IMMUNITY
RECOGNITION
Richard Pfeiffer, a student of Robert Koch – ENDOTOXIN
There must be a receptor that recognizes endotoxin
Lipopolysaccharide (LPS) receptor remained elusive
The Dorsoventral Regulatory Gene Cassette Spätzle/Toll/Cactus controls
the potent antifungal response in Drosophila adults
Bruno Lemaitre, A Hoffmann et al, Cell, 1996
Spätzle:
Toll ligand
Toll:
Receptor
Cactus:
I-kB
Dorsal:
NF-kB
Drosomycin
TOLL RECEPTORS ACTIVATE PHYLOGENETICALLY
CONSERVED SIGNAL TRANSDUCTION PATHWAYS
Fungus
Bacterium
Protease
LPB
LPS
Toll
Tube
Spätzel
CD14
Cactus
Relish
Pelle
TLR4
MyD88
NFkB
IRAK
IL-1R associated
Kinase
Peptid
Drosophila
Inflammation
Acute phase response
Danger signal
IL-6
Macrophage
WHAT IS RECOGNIZED BY INNATE AND ACQUIRED
IMMUNITY?
RECEPTORS
Common pattern of groups of pathogens
Pathogen Associated Molecular Pattern
PAMP
Recognition by receptors
Pattern Recognition Receptor
PRR
9-13 various Toll-receptors
TLR family
Innate immunity
Ancient
Unique structural elements
Antigenic determinant
Recognition by highly specific
antigen receptors
B cell receptor BCR (sIg)
T cell receptor TCR
Several millions antigen receptors
Acquired immunity
450 million years
TOLL RECEPTORS RECOGNIZE VARIOUS MICROBIAL
STRUCTURES
Bacteria
Virus
CpG DNA
ssRNS
dsRNA
Peptidoglycane
Gram+
TLR3
IFN
TLR7
TLR8
TLR2
Interferon
producing cell
pDC
Flagellin
LPS
Gram-
TLR4
TLR6
TLR9
TLR5
Macrophage/Dendritic cell
ALL STRUCTURES ARE ESSENTIAL FOR THE SURVIVAL OR REPLICATION OF THE
PATHOGEN
CONSERVED RECEPTORS/SENSORS THAT DETECT DANGER SIGNALS
TLR3
Fibroblast
Epithelial cell
DC
TLR
LRR
MEMBRANE
TIR
domain
CELL MEMBRANE
Bacteria
MEMBRANES OF
INTRACELLULAR VESICLES
virus
TIR: Toll-Interleukin Receptor
signaling domain
PHAGOCYTES ARE ABLE TO RECOGNIZE PATHOGENS
Toll receptormediated signaling
FcR, CR
Toll receptor
PHAGOCYTES (macrophages, dendritic cells, neutrophil granulocytes)
RECOGNIZE PATHOGENS BY PATTERN RECOGNITION RECEPTORS
RECOGNITION IS ESSENTIAL
RECOGNITION
CYTOPLASMIC SENSORS
VESZÉLYT ÉRZÉKELŐ KONZERVÁLT RECEPTOROK
NLR: NOD-like receptor
RLR: RIG-like receptor
CONSERVED RECEPTORS SENSING DANGER SIGNALS
NLR nod-like receptors
Nucleotide binding domain Leucin rich repeats
TLR
N
C
NBD
NLRP1 – ASC
NLRP3 – ASC – CARDINAL
PYR
NBD
NOD1/2, IPAF/NLRC4
CARD
NBD
IPAF
BIR
TLR3
Fibroblast
Epithelial cell
DC
CYTOPLASM
RLH
CARD-CARD-helicase
MEMBRAN
DANGER SIGNALS ARE TRANSLATED TO CYTOKINE SECRETION
THROUGH VARIOUS MOLECULAR SENSORS IN DC SUBTYPES
4
2
1
5
6
6
3
1
7
NLR
7 9 10
8
RLH
RLH
NLR=NOD/NALP (IL-1β)
RLH=RIG-1/MDA5 (IFN)
Conventional DC
TLR1 –
TLR2 –
Plasmacytoid DC
bacterial lipoprotein (together with TLR2)
bacterial lipoprotein, peptidoglycane, lipoteicholic acid
IL-1β
(heteromer with TLR1 and TLR6)
IL-12/23
TLR3 – viral dsRNS, polyI:C
IL-10
TLR4 – bacterial LPS
TLR5 – bacterial flagellin
TLR6 –
bacterial lipoprotein (with TLR2)
TLR7 – viral ssRNA
TLR8 – GU rich viral ssRNS, imidazoquinolin (antiviral drug)
TLR9 – unmethylated CpG DNA
Th1/Th17/Th2 TLR10 – modified viral nucleotides
IFNαβ
NK/DC
SIGNALING
IN INNATE IMMUNITY
TOLL RECEPTORS ACTIVATE PHYLOGENETICALLY
CONSERVED SIGNAL TRANSDUCTION PATHWAYS
Fungus
Bacterium
Protease
LPB
LPS
Toll
Tube
Spätzel
CD14
Cactus
Relish
Pelle
TLR4
MyD88
NFkB
IRAK
IL-1R associated
Kinase
Peptid
Drosophila
Inflammation
Acute phase response
Danger signal
IL-6
Macrophage
TOLL RECEPTOR MEDIATED SIGNALLING
NEW THERAPEUTIC TARGET
Figure 3 The 'hourglass' shape of the innate immune response. Although microbial stimuli are chemically complex
and although the innate immune response ultimately involves the activation of thousands of host genes, innate
immune signals traverse a channel of low complexity. Ten Toll-like receptors (TLRs), four TIR (Toll/interleukin-1
receptor homologous region) adaptors and two protein kinases are required for most microbial perception. This
circumstance lends itself to effective pharmacotherapeutic intervention. NF-B, nuclear factor-B; STAT1, signal
transducer and activator of transcription 1.
EFFECTOR MECHANISMS OF
INNATE IMMUNITY
CELLULAR AND HUMORAL MECHANISMS OF
INNATE IMMUNITY
PHAGOCYTOSIS
Phagocytosis
Intracellular killing
Phagocyte
Bacterium
INFLAMMATION
Cytokines
IL-12
Bacterium
LPS
COMPLEMENT
TNF
IFN
Complement proteins
Neutrophil
NK-cell
Macrophage
Lysis of bacteria
Inflammation
Bacterium
NK-CELLS
Virus-infected
cell
Complement-dependent phagocytosis
NK-cell
Lysis of infected cell
MECHANISMS OF INNATE IMMUNITY
PHAGOCYTOSIS
PRR
Degradation
ACTIVATION
Bacterium
Phagocyte
Uptake
Intracellular killing
0.5 - 1 hours
Antigen + Antibody
The amount of internalized
particles is limited
ACQUIRED IMMUNITY
Antigen presentation
T cell
ACQUIRED IMMUNITY
PHAGOCYTE SYSTEM
NEUTROPHIL GRANULOCYTE
MONOCYTE – MACROPHAGE – DENDRITIC CELL
Gatekeeper function
Sensing commensals and pathogens
Rapid activation of innate immunity
Priming adaptive immune responses
Maintenance of self tolerance
Defence against infectious
diseases
Elimination of tumor cells
PHAGOCYTOSIS
Macrophages ingest and degrade particulate antigens through the use of long
pseudopodia that bind and engulf bacteria. The engulfed bacteria are degraded
when the phagosome fuses with a vesicle containing proteolytic enzymes
(lysosome), forming the phagolysosome. Specialized compartments also exist in
the macrophage to promote antigen processing for presentation to antigenspecific T cells.
Opsonization enhances the efficiency of
phagocytosis of pathogens by phagocytes
Killing of bacteria by neutrophils: azurophilic and specific granules
azurofil ic
Lyzozyme
Defensins
Mieloperoxidase
Cathepsin G
elastase
specific granuls
NADPH oxidase
Lyzozyme
Phagocyte oxidase (Phox) produces reactive oxidative species (ROS) that
help destroy pathogens
Failure of phagocytes to produce reactive oxigen species
in chronic granulomatous didease
PROTECTION
against bacteria and
fungi is down
regulated
MECHANISMS OF INNATE IMMUNITY
INFLAMMATION – ACUTE PHASE RESPONSE
PRR
TNF-
neutrophil
LPS
IL-12
DANGER
SIGNAL
ACTIVATION
IFN
Few hours
LPS (endotoxin) (Gram(-) bacteria)
ACUTE PHASE
RESPONSE
Kinetics of the release of proinflammatory citokines in bacterial
infection
macrophage
cytokines
TNF-
IL-1
Plasma level
Bacterium
NK-cell
TNF-
IL-1
IL-6
IL-6
1
2
3
4
5
hrs
INFLAMMATORY RESPONSE
The classic symptoms of inflammation:
redness (rubor) - vasodilation,
swelling (tumor) - edema,
heat (calor) – increased perfusion,
pain (dolor) – factors stimulating nociceptors,
loss of function (functio laesa)
CONSEQUENCES OF MACROPHAGE ACTIVATION
SYNTHESIS OF CYTOKINES
Systemic effects of pro-inflammatory cytokines
Systemic release of TNFa initiates septic shock
Septic shock
Local production of
TNFα (and IL1) is beneficial, and
protective,
BUT systemic release
may cause death
Drop in blood volume and hence
blood pressure
Disseminated intrvascular
coagulation
Pro-inflammatory cytokines activate endothel which recruits immunocytes
from blood to infected tissues (extravasatio)
THE ACUTE PHASE RESPONSE
IL- 6
C-reactive protein
Phosphocolin
binding (e.g.fungi)
COMPLEMENT
Mannose binding
lectin/protein
MBL/MBP
COMPLEMENT
Liver
Phosphocoline binding
Fungi, bacterial
Cell wall.
Fibrinogen
Serum Amyloid Protein (SAP)
Mannose/galactose binding
IL-6 induces the production of acute phase protiens
MECHANISMS OF INNATE IMMUNITY
COMPLEMENT ACTIVATION
COMPLEMENT
Complement-proteins
Lysis of bacteria
Inflammation
Chemotaxis
Bacterium
Lectin pathway
Alternative
pathway
Complement-dependent
phagocytosis
Antigen + Antibody
Few minutes – 1 hour
ACQUIRED IMMUNITY
Enzymes get fragmented, complement activity
can be exhausted
RECOGNITION BY SOLUBLE
MOLECULES
MANNOSE BINDING LECTIN
GLYCOSYLATION OF PROTEINS IS DIFFERENT IN
VARIOUS SPECIES
Prokariotic cells
Eukariotic cells
Mannose
Glucoseamin
Mannose
Galactose
Neuraminic acid
PATTERN RECOGNITION BY MANNAN BINDING LECTIN
Bacterium
lysis
Complement
activation
LECTIN PATHWAY
CR3
Macrophage
Phagocytosis
Strong binding
No binding
NK cells
- 5-10% of lymphocytes in circulation
- bigger than T or B lymphocytes
- several granules in their cytoplasm
- have no antigen binding receptors („null cells”)
- participants of native immunity
Type I IFNs increase their cytotoxicity (100x)
IL12, and TNFα are also able to activate them
IFNγ production --- MF, DC activation