Transcript vaccine - Altervista

How to make better vaccines in
the future?
Vaccines interfere at more than one point
Vaccine
Adjuvant + Antigen
“Inflammation”
Inflammation:
Cytokines
Cell recruitment
Neutrophils
Monocytes
Macrophages
Granulocytes
APC
T cells
B cells
Antigen
Presenting
Cells:
Monocytes
Macrophages
Dendritic cells
innate
Ab
Protection
adaptive
How to enhance efficiency of vaccines?
Find better antigens
Adjuvants
Delivery systems
Mucosal immunisation
Requirements for a good vaccine
Safety
Protection : most vaccinees against most substrains
Long-lasting
Neutralising Abs: important against bacterial toxins
Mucosal immunity: presence of Abs on mucosae
T cells
Stability, ease of administration etc.
How do you test the quality of your vaccine?
Animal model
Correlate of protection in humans (what aspect of the
immune response is crucial for protection)
Efficacy trials (high numbers)
Adjuvants
Necessary to induce, enhance and direct an Ag
specific immune response
Why and how?
The immune response in one slide
The immune response in one slide
Necessity of adjuvants I
In a real infection, pathogens FIRST activate innate immunity
(macrophages, neutrophils, DCs, NK cells etc.)
The activated innate immune system then TRIGGERS and
STEERS adaptive immunity:
Priming of naive T cells only by activated DCs
Th1 or Th2 type of T cell response depends on cytokines
present during priming
Necessity of adjuvants II
Immunologist’s dirty secret: provide the signals to activate
innate immunity and generate inflammation
Many whole-cell vaccines contain ligands for TLRs
Subunit vaccines made from purified proteins don’t
The only adjuvants allowed for use in humans are alum (1940)
and MF59 (1995)
Both tend to induce Th2 responses
More efficient Th1 inducing adjuvants are needed
The immune response at a glance
Pathogen
“Inflammation”
Inflammation:
Cytokines
Cell recruitment
Neutrophils
Monocytes
Macrophages
Granulocytes
APC
Antigen
Presenting
Cells:
Monocytes
Macrophages
Dendritic cells
T cells
B cells
Ab
Protection
Vaccines interfere at more than one point
Vaccine
Adjuvant + Antigen
“Inflammation”
Inflammation:
Cytokines
Cell recruitment
Neutrophils
Monocytes
Macrophages
Granulocytes
APC
T cells
B cells
Antigen
Presenting
Cells:
Monocytes
Macrophages
Dendritic cells
innate
Ab
Protection
adaptive
Future vaccine challenges
Vaccines not available/ inadequate:
HIV, HCV, tuberculosis, malaria, Group A and
B streptococci, ...
emerging or re-emerging pathogens:
West Nile, SARS, Ebola, Hanta, Dengue,
pandemic influenza
therapeutic vaccines:
against established infections e.g. antibiotic
resistent bacteria, chronic infections
cancer vaccines
Different Vaccines require different Adjuvants
Th2
vs.
Th1
Safety
Gradient
Pediatric
vaccines
Traveler
vaccines
allergy
vaccines
Vaccine
Ab
vs.
CTL
Bioterrorism
military
therapeutic
vaccines
Cancer
vaccines
The Slow Pace of Adjuvant Development
1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s 2000s
Insoluble
Aluminium
Salts
MF59
o/w
Alum
MPL
(TLR4)
•
Thousands of adjuvants have been described in pre clinical studies.
•
Three are included in approved vaccine products.
•
Many have failed, including a licensed product (Merck w/o emulsion for
influenza,1960’s):
•
Many have failed due to safety (Merck emulsion; Chiron with MTP-PE in Phase I)
•
Difficult to manufacture, raw materials unavailable
•
Impossible to scale up
•
Lack of reproducibility
•
Too complex or expensive
•
There will continue to be failures (Adjuvant development not for the easily discouraged)
Adjuvants = Immune potentiators
+ Delivery systems
Delivery systems:
• Ag in particulate form is taken up better
by DCs and Macrophages than Ag in soluble form
• This allows more efficient Ag presentation to T cells
Immune potentiators:
• Substances with direct stimulatory effect on APCs,
often with a specific receptor
Not always clear distinction
Key Components of Effective Vaccines
Delivery
Systems
Immunepotentiators
Antigens
Potent and Durable Immune Responses
Comparison pathogen - vaccine
Bacterium
Protein
antigens
LPS
Flagellae
DNA
Synthetic
Vaccine
Immune
Potentiators
Delivery system
~1m
~1m
A classification system for vaccine adjuvants
Antigen delivery systems
Immunopotentiators
• Alum
• Calcium phosphate
• Tyrosine
• Liposomes
• Virosomes
• Emulsions
• Microparticles
• Iscoms
• Virus-like particles
• MPL and derivatives
• MDP
• CpG oligos
• Alternative PAMPs – flagellin etc.
• Lipopeptides
• Saponins
• dsRNA
• Small molecules e.g. Resiquimod
“the others”
Mechanism
of action???
TLR-agonists
Types of immune potentiators and delivery systems
Adjuvant category
Representative examples
Brief description
Mineral salts
Aluminum and calcium salts
Licensed for human use
Many bacterial and viral antigens
have been adsorbed onto alum
and Ca salts
Emulsions and surfactantbased formulations
MF59, AS02, montanide ISA-51
and ISA-720, QS21
Micro-fluidized detergent-stabilized
emulsions
Surfactants derived from
natural sources
Particulate delivery vehicles
Microparticles, immunostimulatory complexes;
liposomes, virosomes, viruslike particles
Antigens and adjuvants can be
trapped inside or coated onto the
surface of particles
Microbial derivatives
Monophosphoryl lipid A, CpG
oligonucleotides, cholera toxin
and heat labile toxin from
Escherichia coli, lipoproteins
Bacterial products or synthetic mimics
are potent stimulators of the innate
immune system. Most of
these agents signal through TLRs
Cells and cytokines
Dendritic cells; IL-12 and
GM-CSF
Cytokines stimulate cells of the
immune system
Autologous dendritic cells pulsed with
tumor-derived peptides efficiently
present antigenic epitopes
Types of immune potentiators and delivery systems
Adjuvant category
Representative examples
Brief description
Mineral salts
Aluminum and calcium salts
Licensed for human use
Many bacterial and viral antigens
have been adsorbed onto alum
and Ca salts
Emulsions and surfactantbased formulations
MF59, AS02, montanide ISA-51
and ISA-720, QS21
Micro-fluidized detergent-stabilized
emulsions
Surfactants derived from
natural sources
Particulate delivery vehicles
Microparticles, immunostimulatory complexes;
liposomes, virosomes, viruslike particles
Antigens and adjuvants can be
trapped inside or coated onto the
surface of particles
Microbial derivatives
Monophosphoryl lipid A, CpG
oligonucleotides, cholera toxin
and heat labile toxin from
Escherichia coli, lipoproteins
Bacterial products or synthetic mimics
are potent stimulators of the innate
immune system. Most of
these agents signal through TLRs
Cells and cytokines
Dendritic cells; IL-12 and
GM-CSF
Cytokines stimulate cells of the
immune system
Autologous dendritic cells pulsed with
tumor-derived peptides efficiently
present antigenic epitopes
Possible mechanisms of delivery systems
• presentation of Ag in an ideal conformation
• render Ag polymeric
• render Ag particulate [PLG]
• protect Ag from degradation
• retention of Ag at injection site: depot-effect [alum]
• target Ag to antigen presenting cells [mAbs]
• immune cell activation [PAMPS, cytokines, mAbs]
• recruitment of additional immune cells [MF59]
Examples for delivery systems
Cationic PLG/CTAB microparticle for DNA
adsorption
Polylactide-coglycolide
DNA
DNADNA
Delivers DNA to APC
Protects DNA from degradation
Safe, Stable, Scalable
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- -
- +
+
++
+
+
-
DNA
-
+
+
+
1um
+
+
PLG
+
+
Microparticle +
+
+
+
+ + + + +
--
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-
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DNA
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-
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DNA
-DNA
PLG microparticles for vaccine delivery
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1m
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PLG
microparticle
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Ag
Ag
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IP
IP
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IP
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IP
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IP
IP
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–
The antigen is adsorbed after
preparation of the microparticle
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–
PLG/Antigen
–
–
Ag
Ag
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–
–
Ag
–
IP
–
–
Ag
IP
IP
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–
Ag
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–
Ag
–
Ag
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Ag
Ag
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–
Ag
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Ag
Ag
PLG/Immune Potentiator/Antigen
Immune potentiators can be entrapped
in the microparticle during preparation
Adjuvant performance with different Ag
MF59 - o/w emulsion adjuvant
Appearance: milky white oil in water (o/w emulsion)
H2O
H2O H2O
H2O
H2O
H2O
H2O
H2O
OIL
H2O
H2O
H2O
H2O
Composition:
H2O
H2O
H2O H2O
H2O H2O
H2O
H2O
H2O
H2O
OIL
H2O
H2O
H2O
H2O
H2O H2O
0.5% Polysorbate 80 water-soluble surfactant
0.5% Sorbitan Triolate oil-soluble surfactant
4.3% Squalene oil
Water for injection
10 nM Na-citrate buffer
Density: 0.9963 g/ml
Viscosity: close to water, easy to inject.
H2O
H2O
Size: 160nm.
MF59 - Overview
H2O
MF59…
H2O H2O
H2O
H2O
H2O
H2O
OIL
H2O
H2O
H2O
H2O
•
has a good safety profile
•
increases immunogenicity of a wide
range of vaccine Ags tested in
preclinical and clinical trials
•
induces immune responses in
immune compromised individuals
•
induces predominantly Th0/Th2
responses
•
allows reduction of Ag dose
•
increases the breadth of cross
reactivity of Ab responses
H2O
H2O
H2O H2O
Adjuvant performance with different Ag
Addition of MF59 allows to reduce Ag dose
mg/dose
Plain
+ MF59
3.75
7.5
30
Pandemic H9N2
clinical trial:
HAI Geometric
Mean titers
GMT
15
MF59 - Mechanism of Action
MF59 is not only a delivery system, but also an immunopotentiator
MF59 has three human target cell types:
monocytes, macrophages and granulocytes
MF59 induces chemoattractants for cell recruitment
MF59 enhances and accelerates development of dendritic cells
The signature of MF59 (and alum) greatly differs from that of LPS:
“adjuvant” signature vs. “danger” signature?
Consistency with mouse serum cytokine and cell recruitment data
MF59 effects in the context of vaccination
Why is that good?
– increased recruitment of immune cells to the injection
site:
more cells to start the immune response
– increased endocytosis by MC:
Ag is taken up to be presented to the immune system
– differentiation of MC towards immature DCs:
these are the best cells to activate T cells
– up-regulation of chemokine receptor CCR7 on DCs:
helps DCs to migrate to draining lymph nodes where
T cells are
How does MF59 increase the immune response to
vaccine antigens?
Examples for immune potentiators
The immune response in one slide
Naïve T cells are primed by antigen presented
on activated dendritic cells
Naïve T cells are primed by antigen presented
on activated dendritic cells
PRR=
Pattern
Recognition
Receptor
PAMP=
Pathogen
Associated
Molecular
Pattern
Many types of PRR
Structure of bacterial LPS
LPS: Endotoxin from outer membrane of Gram-negative
bacteria stimulates innate immune response via TLR4
E6020 is a completely synthetic TLR4 agonist
Fully synthetic molecules
E. Coli lipid A
(TLR4 Agonist)
Westphal, et al,
Angew. Chem. 1954, 66, 407.
Eritoran
(E5564)
(TLR4 Antagonist)
Rossignol, et al.; In: “Endotoxin in Health and
Disease,” Brade, Opal, Vogel and Morrison, eds.,
Marcel Dekker, Inc., 1999, 699.
E6020
(ER-804057)
(TLR4 Agonist)
(R,R,R,R)
The search for new immune
potentiators
Screens for Immune Potentiators
A. Functional HTS to Identify SMIPs
Small
Molecules
SMIPs
Human PBMCs
Cytokine ELISA
IL-1
TNF
IL-12
IFNs
IL-6
GM-CSF
Screen for immune potentiators
Use small molecule libraries, do high throughput screen for
Th1 related cytokine production of total PBMCs
Modify positive scorers to improve them
Check for cell type specificity on purified populations
Test in vivo in mice in combination with known Ags