Allergy, atopy and asthma
Rich Locksley
Micro 204
December 2014
Allergy and asthma: cells and cytokines timeline
Th2 cytokines in
asthma lung biopsies
IgE
Ishizaka/Be
nnich/Johan
sson
Anaphylaxis
Charles Richet
1879
Eos, basos,
mast cells
Paul Ehrlich
1913
1921
Prausnitz-Kustner
1967
Th2 cells
Mosmann, Coffman
IL-5 ko mice
IL-13 ko mice
1983
1986
1991 1992
IL-4, IL-5, IL-13
1998
2002
2009-
IL-4/5/13 ko mice
IL-4 ko mice
aIL-5, aIL-13
Global burden of allergic pathology
Developed Countries
Asthma and Allergy
Developing Countries
Parasitic helminth infections
>300 million worldwide
Intestinal nematodes (>2 billion)
Asthma prevalence increased 75%
from 1980-1994
Tissue filaria (>120 million)
Tapeworms (>2 million)
>70% asthma patients have allergy
Schistosomes (>200 million)
1:8-12 US children
>$20 billion/yr health care costs US
Major causes of liver failure,
bladder cancer, elephantiasis,
blindness, epilepsy
(post-reproductive morbidity)
A word about helminths
Account for ~80% of all individual animals on earth
Estimates up to 106 species
Three major, two minor clades - all includes parasitic species
2.9 billion humans estimated infected
Universal in rural subtropical environments typical of human evolution
Essentially universal in feral vertebrates (mammals, birds, fish, reptiles, amphibians)
Genome size ~ 20,000
If type 2 immunity protects us from
helminths, it doesn’t do a very good
job…
Maybe helminths exploit the pathway for
other things…
Parkinson J, et al. 2004. A transcriptome analysis
of the phylum Nematoda. Nature Genet 36:125967.
Ana - phylaxis: “Backwards Protection”
X
X
Richet: 1913 Nobel Prize
Allergy
An adverse immune response to environmental antigens
(allergens).
Operational definition:
IgE
Manifestations: Anaphylaxis, Eczema, Hayfever, Asthma
Insect venoms
Many Allergens Acquired
Via the Mucosa
Pollens
Mite feces
Animal danders
Food
Haptenylated drugs (penicillin)
IgE = “Reagin” or “Reaginic Antibodies”
PCA: Passive Cutaneous Anaphylaxis
Serum (IgE) (Ishizaka, 1966)
Atopic to
Antigen X
aIgE
Non-Atopic
Antigen X
Immediate Hypersensitivity
Stages of Allergy - I.
Early Phase Reaction - minutes
IgE
Allergen
FceRI
PGD2
LTC4
“Wheal &
Flare”
Edema
LTD4
LTE4
Histamine
Post-capillary Venule
Stages of Allergy - II.
Late Phase Reaction - hours
CCR8
a4
TNF
Th2
PGD2
CCR3
Eotaxins 1, 2, 3
IL-4
IL-13
MCP 2, 3, 4
RANTES
IL-5
a4
IL-3
IL-9
CCR3
a4
Basophils
Eosinophils
Stages of Allergy - II.
Late Phase Reaction - hours
CCR8
a4
TNF
Mast
cell
Th2
PGD2
CCR3
Eotaxins 1, 2, 3
IL-13
ILC2
cell
IL-5
MCP 2, 3, 4
RANTES
GM-CSF
a4
IL-9
CCR3
a4
Basophils
Eosinophils
Stages of Allergy - III.
Chronic Phase Reaction - wks - yrs
1. Subepithelial Fibrosis
TGF-b;
Toxic
Granules
3. Mucosal and Mast Cell
Hyperplasia
2. Smooth
Muscle
Hypertrophy
FceRI: Key Player
IgE
+++
Kd = 10-10 M
a
gg
b
P
Lyn
AA
P
P
Syk
LAT
PLA-2
GADS/SLP-76
VAV
LTC4
IL-4
PIP3
PLCg1
Rab
MAPK
TNF
Btk/Itk
Ca++
Ras
PGD2
PI(3)K
Cytoskeleton
Granule
Exocytosis
Mouse = Human
Mouse IgG1/FcgRIII on mast cells can trigger pathway (not
present on human mast cells)
Human APC, Eosinophils:
ag2 FceRI
a
gg
IgE-linked antigen
presentation in human
How do perivascular mast cells acquire serum IgE?
…..they reach in and take it
Mast cell (green) around a
blood vessel (white outline)
extending a process into the
lumen to bind an IgE-coated
bead.
Cheng et al, Immunity 38:166-75, 2013
Mast Cell Granules
Histamine: Vasodilator
Edema*
Heparin: Bonds constituents (negative charge)
Neutral Serine Proteases:
Tryptase
All
Chymase
Carboxypeptidase
Cathepsin G
Knock-out: no mast cell granules
C.T. >
mucosal
*Dudeck A et al, Immunity 34:973-84, 2011
Myeloid Cell Eicosanoids
Ca++
FLAP
AA
IgE
LTA4
5-LO*
PLA2
LTA4 Hydrolase
PMN
M
Transpeptidase
LTB4
chemoattractant
BLT1
BLT2
Cell
Recruitment
LTC4
synthase; in
asthma
LTC4
Mast Cells
Eosinophils
Basophils
AAM
LTD4
Dipeptidase
LTE4
(SRS-A)
CysLT1,CysLT2
Smooth Muscle
Contraction
Endothelial NO
* Mouse ko:
anaphylaxis
Mucus Secretion
Leukotriene Receptors
BLT1
LTB4 (Kd~0.5
nM)
BLT2
LTB4 (Kd~23
nM),
Gene duplication
14q (h)
Myeloid, lymphoid cells
Tissue
recruitment
More widely
other eicosanoids
CysLT1 LTD4>C4=E4
CysLT2 LTC4=LTD4>E4
X (h)
13q14 (h)
PBL, lung smooth muscle,
Vascular
lung macrophages,
relaxation; smooth
small intestine
muscle contraction;
cell activation
PBL, lung, heart, brain
Cell activation
Mast Cell PGD2
Ca++
IgE
AA
PLA-2
in asthma
COX
PGD2
DP1**
Kd ~ 1.5 nM
(airway epi,
basophils,smooth
muscle lung, GI)
**Mouse ko = lung
inflammation, bronchial
hyperreactivity
*Mouse ko = skin allergic
hypersensitivity
CRTh2 (DP2)*
Kd ~ 2.5 nM
(Th2, eo, baso,ILC2,
lung smooth muscle,
GI)
Bronchoconstriction
Chemokines (Eotaxins, MCPs, MDC)
Eosinophil Granules
Specific
Major Basic Protein
Eosinophil Cationic Protein (RNase3)
Eosinophil Peroxidase
Eosinophil-derived Neurotoxin
(Rnase 2)
Primary
Lysophospholipase
(Charcot-Leyden crystals)
CYTOTOXICITY
(multi-system toxicity in patients with idiopathic HES)
Eosinophils and airway remodeling
Less subepithelial and interstitial collagen deposition in sensitized mice lacking
eosinophils (Humbles et al., Science 305:1776, 2004)
Asthma
Prevalence:
>300 million worldwide
1/6 U.S. children
Cost in U.S. > $6 billion/yr
ing
Developed > Nondeveloped Countries
Hygiene Hypothesis
Reflects developmental evolution of mucosal/regulatory immune system, possibly
through effects on establishing the commensal flora
?Worms, ectoparasites, childhood infections
Asthma: an epidemic in the absence of infection…
Inverse relationship between infections and immune disorders
Bach JF. 2002. N Engl J Med. 347:911.
Asthma Triad
1. Reversible episodes airway obstruction
( mucus, eosinophils, T cells with IL-4, IL-5,
IL-13, GM-CSF, etc.)
2. Chronic airway inflammation
( T cells, eosinophils with
type 2 cytokines;
chronic subepithelial, epithelial changes with
mucus cell hyperplasia)
3. Bronchial hyperreactivity with provocative agents
The global epidemic of asthma
Masoli et al., The global burden of asthma: executive summary of the GINA dissemination
committee report. Allergy 59:469-78, 2004
A disease of persistent Th2-associated airway inflammation
Innate cytokines in Type 2 immunity
21 Kb
N. brasiliensis
S. mansoni
Sullivan et al, Nature Immunology 2011:
Type 2 immunity as a
confluence of innate and
adaptive responses to
epithelial insults…
…and why no Tregs?
(prominent in helminth
infection)
Locksley, Cell 140:777-783, 2010:
ILC2
cells
Innate lymphoid cells, 2014…
ILC1
ILC2
ILC3
Group 1: T-bet+
Group 2: GATA3hi
Group 3: RORγt+
IEL ILC1
Natural helper cells
Nuocytes
Ih2
NK-22
ILC1
cNK
IFNγ
Th1
Ex-RORγt
LTi
IL-5
IL-13
Th2
IL-17A IL-22
Th17
Th22
IFNγ
ExTh17
Unexpected roles for ILC2s (and probably Th2s)…
Group 2: GATA3hi, RORa+
Type 2 immune responses
Anti-helminth immunity
Allergic pathology
?Treg homeostasis
ILC2
Tissue homeostasis
IL-9
IL-5
Basal eosinophilopoiesis
Mucosal integrity
?Organ repair
IL-13
AAM
Metabolic homeostasis
White adipose tissue
?Beige adipose
?Adaptive thermogenesis
ILC2s sustain resident eosinophils and AAMs needed for
metabolic homeostasis
Wu et al, Science 2011; Molofsky et al, J Exp Med 2013
Role for eosinophils and AAMs in brown fat (adaptive
thermogenesis) and ‘beige’ fat consistent with role for
ILC2s
Nguyen et al, Nature 2011; Qui et al, Cell 2014;
Rao et al, Cell 2014; Lee et al, Cell (in press)
ILC2s integrate diverse signals to dynamically
regulate tissue microenvironments
Lipid mediators
IFN-g
Neuropeptide
transmitters
VIP
Circulating
eosinophils
IL-9, GM-CSF
Amphiregulin
AAMs
Local eosinophils
AAM
Treg homeostasis
Cytokines
Birds of a feather…
ILC2
Th2
IL-9
IL-5
IL-9
IL-13
AAM
IL-5
IL-13
AAM
Do worms exploit type 2 immunity for their own metabolic and
tissues needs?
Eggs
Pharynyx
Chitin in egg shells and
pharyngeal feeding tube
Asthma GWAS
Part of ILC2 / Th2 signature
Asthma GWAS
Moffat MM et al, NEJM 363:1211-21, 2012
Mouse 'Asthma'
OVA
OVA
X 3-5
BAL:
Eos, Th2
Histology:
Mucus Cell Hyperplasia,
Inflammation (BALT’s)
Physiology:
Airway Hyperreactivity
Therapy of human asthma
Approved in clinic
Steroids and beta-agonists (long- and short-acting) - mainstay
5-LO inhibitors (LTA4 synthesis blockers)
CysLTI antagonists (LTD4 blockers)
Monoclonal humanized anti-IgE mAb (E25)
Anti-IL-5 (decrease disease in high-eo subsets, usually steroidresistant)
Anti-IL-13 (in Th2-high signature asthmatics)
In development/testing:
anti-TSLP (clinical trial promising)
Suplatast tosilate (suppresses IL-4, IL-5 from Th2 cells)
CDP840, phosphodiesterase type 4 inhibitor
IL-4 receptor, IL-4/13 inhibitors, anti-IL-5R
OX40L blockade
anti-TNF (steroid resistant asthma), IL-17 inhibitors
anti-IL-33
Topics for discussion
Asthma reaches prevalence levels of 8%-12% in some urban Westernized
populations. Allergic asthma is predominantly a disease of childhood. Consider the
impact of genetics, environment and development in constructing a model to explain
the immunologic underpinnings explaining the increasing prevalence of asthma.
How would you proceed to validate and/or intervene therapeutically based on your
conclusions?
Asthma is an integrated tissue response involving innate and adaptive cell crosstalk. Delineate the relevant cell types, the pathways believed to drive the tissue
pathology, and identify shared ‘nodes’ of intervention designed to disrupt the
cytokine/cellular network in order to restore homeostasis. Consider possible ‘offtarget’ side-effects, even in other tissues.