Immunity to infectious diseases

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Immunity to infectious diseases Nov 10, 2008
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Evolutionary pressure on immunity
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Emerging and re-emerging infectious diseases
Morens DM et al., Nature 2004, 430242-9.
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Primary causes of death worldwide
Morens DM et al., Nature 2004, 430242-9.
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Heritability of premature death among 960
adoptees TI Sorenson et al., Genetic and
environmental influences on premature death in
adult adoptees. N Engl J Med 318727-32, 1988
Implies risk of infectious diseases largely
heritable - we need to understand the genes
involved
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Primary Adaptive Immunodeficiencies
Proximal defects multiple lymphocyte lineages
broad spectrum, life-threatening infections bone
marrow reconstitution or gene therapy
required Distal defects narrower spectrum of
infections can be life threatening (XLP, HLH,
IPEX), chronic (Stat3, Tyk2) or unexpectedly mild
(TAP, CD8)
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Primary Innate Immunodeficiencies
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'Immunodeficiencies' can result from immune gene
and non-immune gene defects
Genetic mutation Common Pathogens
DARC Plasmodium vivax
HgbS Plasmodium falciparum
Fut2 Norovirus SAP EBV
EVER1, 2 HPV Terminal complement
components Neisseria IFN?/IL-12 Mycoba
cteria, Salmonella IRAK, MyD88 Encapsulated
gram-positive bacteria Unc93B, TLR3 HSV
encephalitis
Why is the immune deficiency so 'narrow'?
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Infectious diseases definitions
Colonization Persistence on skin or mucosal
sites Infection Invasion and multiplicatio
n at sterile site Disease Pathology
resulting from infection
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Infectious organisms
Commensals Normal flora often
symbiotic Pathogens Virulence genes -
toxins, receptors, etc. Opportunists Immunod
eficient or otherwise compromised host
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Biggest infectious disease risk?
Antibiotics - depletes commensals
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Enrichment of the human intestinal microflora
from the environment
Major
Minor
Absent
Backhed et al., Science 3071915-20, 2005
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How do we do it?
Underwater clues
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Colonization by Vibrio fischeri expressing
luciferase required for development of the light
organs in the Hawaiian bobtail squid, Euprymna
scolopes.
Eye reflectors
Light organ (from ventral side)
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Light organ morphogenesis in response to V.
fischeri
2 hr
Colonization by V. fischeri
Sea water colonization by microbes
100 V. fischeri /ml salt water
106 total bacteria/ml salt water
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Stages of light organ morphogenesis
induced by PG and LPS from symbiont Vibrios
Koropatnick et al., Microbial factor-mediated
development in a host-bacterial mutualism.
Science 2004, 3061186-8.
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Colonization versus invasion - pathogens figure
out how to get in
Fungal symbiosis (arbuscular mycorrhiza) occurred
400-460 million yrs ago at the time of land
colonization by plants Shares transcriptome and
receptors with bacteria and nematodes Comparative
analysis of fungal colonization with fungal
parasitism reveals 40 overlapping genes many
induced by inorganic phosphate
Pathogen
Guimil et al., Comparative transcriptomics of
rice reveals an ancient pattern of response to
microbial colonization. Proc Natl Acad Sci USA
1028066-70, 2005
Symbiont
Pathogen
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Microbial recognition is embedded in innate
immune receptors
Innate immunity Soluble Complement,
collectins Pentraxins, PGRPs Antimicrobial
peptides Cytokines Cellular Toll-like
receptors Cytokine receptors C-type lectin
receptors Cytosolic NOD proteins RNA
helicases DNA recognition Adaptive
immunity Soluble Antibodies Cellular T cell
and B cell receptors
Recognition, self-nonself discrimination,
wounding response Opsonization, phagocytosis,
reactive oxygen/nitrogen Destruction Memory
Invertebrates/Vertebrates Vertebrates
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Innate immunity maintains commensals at
epithelial borders
OLD Paradigm
b-defensins a-defensins
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Susceptible Mouse Knock-outs P x E Selectin
Phox x NOS2 C/EBP? (no specific
granules) Cramp (cathelicidin)
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HUMAN MUTATIONS CONFIRM
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MUCOSA TONICALLY REGULATED
OLD Paradigm
Th17
M
IgA
ENTERIC FLORA
M
M
CD25
IL-10
TGF?
Treg
IBD IL-10, SMAD3, IL-2, IL-2R?,
IL-2R?,TCR? Human IL-23R/NOD2/autophagy
genes
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Commensals maintain immunity at epithelial borders
NEW Paradigm
Commensals sustain epithelial
integrity Commensals sustain mucosal immune
homeostasis Commensals sustain systemic
metabolic homeostasis (insulin sensitivity,
fatty acid metabolism, etc.)
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TLR-mediated signaling from cell surface and
endosomal compartments
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Mice unable to sense intestinal bacteria through
TLRs cannot heal intestinal injury
Rakoff-Nahoum et al., Recognition of commensal
microflora by Toll-like receptors is required for
intestinal homestasis. Cell 118229-41, 2004.
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Intestinal bacteria can be replaced by a defined
TLR ligand to mediate intestinal repair
Rakoff-Nahoum et al., Recognition of commensal
microflora by Toll-like receptors is required for
intestinal homestasis. Cell 118229-41, 2004.
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Commensals regulate numbers of lamina propria
Th17 cells
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Take home messages
Commensalism likely drove innate
microbial receptors Pathogens exploit this
Adaptive immunity evolved to cope
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Acute phase response mediated by IL-6 cytokine
family
Brain - Fever (prostaglandin EP3 receptor)
Liver - Acute Phase Proteins (soluble
recognition factors) Fat - Leptin (energy,
wound repair) Bone Marrow - Leukocyte
precursors
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PMN to monocyte transition during inflammation
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Nonpolymorphic MHC molecules
Molecular chaperones for distinct cellular
compartments Tissue-specific distribution Can be
stress- or cytokine-induced Many interact with
invariant lymphocyte populations Non-peptide-based
recognition
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MIC-A, MIC-B, RAE-1
Stress-induced cytotoxicity
NKG2D
V?1 IEL
Epithelium
MIC-A MIC-B
NKG2D
Stress
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Induction of MIC-A at foci of CMV in infected
lungs
MIC-A CMV
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Nonclassical MHC Molecules
MHC Tissue Lymphocyte Ligand
FcRn gut, endothelium IgG
HFE gut, ubiquitous (Fe,
transferrin) HLA-E (h) ubiquitous
CD94-NKG2C/DAP12 MIC-A,-B (h)
induced NKG2D/DAP10 RAE-1
(m)/UBP (h) induced
NKG2D/DAP10 H2-M3 (m) induced
CD8 CTL CD-1 a,b,c (h) gut, APC
DN, IEL, gd CD-1d (h,m) gut, liver,
thymus, APC NK T cells HPCR
vascular endothelium (activated protein A)
MR1 gut, APC MAIT
cells
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Invariant Lymphocytes
Cells MHC Ligands Receptors NK
T CD1d a-Gal/Cer
Va14(24)/Vb8(11)
Non-a-Gal/Cer Va3.2,Va8/Vb8 Tissue gd
CD1c lipids
Vg2/Vd1 Blood gd ? Prenyl
pyrophosphates, Vg9/Vd2
phosphorylated nucleotides MAIT cells MR1
unknown Va19(7.2)/Ja33 CD8aa IEL
TL CD8aa ? B1 B
cells - TI-antigens (PC)
IgM MZ B cells - TI-antigens (broad)
IgM NK cells class I
Variable KIR, Ly49, CD94-
NKG2C/DAP12
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Activation of immunity
Inflammatory cytokines/chemokines -acute phase
response -phagocyte recruitment/activation Nonpol
ymorphic MHC expression Activation of innate T
and B cells Migration and maturation of dendritic
cells Activation of adaptive T and B cells
All in setting of normal commensal flora
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Sepsis Syndrome - A Systemic Response to Infection
Fever, tachycardia, tachypnea, hypotension, organ
dysfunction due to widespread endothelial
injury 300,000 cases/yr in US with mortality
20-50 Gram negatives Gram positives gt fungi gt
viruses
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LPS is an ancient conserved molecule on GN
bacteria - 75 of cell surface/3x106 molecules
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Septic shock
M?
HPCR
SR
TNF IL-1 IL-6 IL-8
PROCOAGULANT
APC
LPS
CD14
MyD88
NF?B
LPS
Lipoproteins
LPS
TLR4
LBP
LBP
LPS
sCD14
IL-1, IL-6, IL-8 SELECTINS
TLR
NF?B
Mouse KO Phenotype
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Response to LPS in humans
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Admission TNF Levels and Outcome in Sepsis
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Meningococcal sepsis carriage rate of 10,
disease rate 1/100,000/life, incidence 80-fold
higher in family members Susceptibility innate
recognition genes (C components, MBL) What about
LPS recognition?
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Over-representation of rare TLR4 mutations in
patients
Contributes 7.5 of disease susceptibility
Smirnova et al., Proc Natl Acad Sci USA
1006075-80, 2003.
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Mouse Models I. High-dose LPS
25-100 ?g LPS i.v. or i.p. LD50 150 ?g Death in
35 hrs Pathogenesis Proinflammatory cytokines,
PMN activation, widespread endothelial
damage Resistant K.O.'s LBP, CD14, TLR4
(C3H/HeJ), MyD88, P x E Selectin, ASC
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Mouse Models II. Low-dose LPS
Pre-sensitize with D-galactosamine LD50 0.0005
?g Death in 7 hrs Pathogenesis Hepatic
necrosis/apoptosis Resistant K.O.'s FasL,
TNFR1, TNF, IL-18, IFN-?, IFN-?R
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Listeria monocytogenes
Epidemiology Foodborne infection Outbreaks
traced to contaminated vegetables and dairy
products Survival enhanced by cold
enrichment Microbiology Gram-positive,
?-hemolytic, motile Facultative
intracellular organism
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Listeria Infection
Normal Host Fever, Diarrhea (gastroenteritis) In
cubation 20-30 hrs Compromised Host
Meningitis, meningoencephalitis,
bacteremia Incubation 20 days At
Risk Immunosuppressed, pregnancy, infants, HIV
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Listeria Infection
65 of cases have Listeria foods in
refrigerator High-risk Foods soft cheeses,
ready-to-eat deli foods (hot dogs, cold
cuts) Recommendations Thoroughly cook animal
foods wash raw vegetables separate cooked and
uncooked foods avoid unpasteurized foods wash
hands, knives, cutting blocks High-risk
avoid soft cheeses, deli foods
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Listeria Attachment Ligands
Internalin A Binds E-cadherin on intestinal
epithelium Transgenic mice expressing human
E-cad can be infected orally Fetoplacental and
blood brain barriers also express
E-cadherin Internalin B Binds Met receptor
tyrosine kinase on hepatocytes, APC

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Listeria life cycle
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Mouse model of Listeria infection - a broad
interrogation of immunity
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Dendritic cell-mediated clustering of innate
cells leads to activation following Listeria
infection
NK cells
PMNs, Monocytes
NK IFN?
IL-12
Listeria
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M. tuberculosis Acid-fast mycobacteria
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Tuberculosis Global Perspective
2 billion infected (1/3 world population) 8
million active disease 2-3 million deaths (6
world deaths)
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M. tuberculosis Genome - Clonotypic Lineages
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Tuberculosis Pathogenesis
Inhalation of infected droplets (human-to human

transmission) Facultative intracellular pathogen
of macrophages Spread to regional lymph nodes
with bacteremia and diffuse metastatic
foci Control by Th1 cell immunity and macrophage
activation Latent for years in caseating
granulomas in aerobic sites with poor lymphatic
drainage (lung apices, kidneys, vertebral bodies,
meninges)
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Maintenance of TB in humans - sequestration in
granulomas by Th1-mediated immunity
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M. tuberculosis Blocks Phagosome Maturation
Phagosome, pH 7
Early phagosome, pH 6.5
Tuberculosis Phagosome, pH 6.2 - 6.3
Late phagosome, pH 5.8
Early endosome, pH 6.3
Late endosome, pH 5.5
Lysosome, pH 4.5 - 5
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Primary Tuberculosis
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Tuberculin Skin Test (DTH)
LTBI - Latent TB Infection
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Granulomatous Inflammatory Response in TB
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PPD and Risk of Active TB
HIV-neg 0.1 per yr CXR-neg HIV-pos 7
per yr CXR-neg
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Cavitary Latent Tuberculosis
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Reactivation Tuberculosis
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Immunity to Tuberculosis
Latency maintained by Th1 cell immunity CD4gtCD8
IL-12, IFN-?, TNF Genetic risks (environmental
mycobacteria, TB, salmonella) IFN-?R, IL-12 p40,
IL-12R?1, Stat1 mutations Acquired risks HIV,
anti-TNF, immunosuppression
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Leishmania life cycle
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Spectrum of Human Infection with L. donovani
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Th subsets in resistant C57BL/6 and susceptible
BALB/c mice infected with L. major
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Footpad pathology resistant C57BL/6 mice
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Footpad pathology susceptible BALB/c mice
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Th subsets in BALB/c mice infected with L. major
- Cure with anti-IL-4 at time of infection
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BALB/c mice susceptible to Leishmania major clear
infection with anti-IL-4 treatment
L. major
L. major anti-IL-4
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Emergence of IL-4-expressing, LACK-specific T
cells
4get BALB/c mice
time (hrs)
0
24
48
72
96
120
LACK
0
0
0
46
75
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LACK-
0
0
0
1
2
3
eGFP (IL-4)
CD4
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Activation of Tregs enables parasite persistence,
diminishes host pathology, induces concomitant
immunity
IL-27 ?
IL-10
Persistent low-level infection Concomitant
immunity
Treg
IFNg
IL-35 ?
IFNg
Sterile immunity No memory
Belkaid et al., Nature 420502, 2002
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L. major life cycle
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Murine L. major model summary
1. Promastigotes parasitize macrophages and
inhibit IL-12 induction. Convert to
amastigotes. 2. Parasites activate early IL-4
expression independent of genetic background. 3.
Th1-dependent response for cure. 4. Persistence
may relate to activation of IL-10-secreting Th1
cells and Treg in skin.
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Immune effector modules
Extracellular bacteria and fungi
Facultative and obligate intracellular organisms
Helminths and biting insects
Sustain homeostasis in chronic infections
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The End