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.