Lung

ILC2 plasticity

Intestine

Adipose tissue

Spleen and thymus

Skin

EILPNKP CHILP

? ILCP LTiP

ILC2P

EOMES,IL-15,T-bet

Bone marrow or fetal liver

Periphery

Activatingfactors

Effectormolecules

EOMES,ID2,NFIL3

TCF1,NFIL3,TOX

GATA3,ID2,IL-7

PLZFRORγt,RUNX3

AHR,RORγt,RUNX3

TOX

EOMES,T-bet

RUNX3,T-bet BCL-11B,

GFI1, TCF1

BCL-11B,GATA3, IL-2,Notch, RORα

NKcell iILC1 ILC1 exILC3 NCR+

ILC3NCR–

ILC3LTicell

IL-12,IL-15,IL-18

IL-12,IL-15

IL-12,IL-18

IFNγ, granzymes, perforin

IFNγ IFNγ

ILC2

IL-2, IL-25, IL-33, PGD

2,

TL1, TSLP

AREG, GM-CSF, IL-4, IL-5, IL-9, IL-13

IL-2,IL-12,IL-18

IL-1β,IL-2, IL-6,IL-23

GM-CSF,IL-22, LT,TNF

GM-CSF,IL-17, LT

IL-17, IL-22,LT, TNF

IL-1β,IL-2,IL-6,IL-23

IL-1β,IL-2,IL-23

CLP

Gobletcell

Macrophage

Mucusproduction

Goblet cellhyperplasia

B cell

Eosinophilia

ILC2

ILC2

ILC2

Homeostasis andtissue repair

Airway hyperresponsivenessand asthma

OVA, papain,HDM or LPS

High-fat diet

Obesity-induced airway hyperresponsiveness

IL-33 AREG

ILC3

IL-1β

IL-17

IL-25, IL-33,TL1, TSLP

ICOSL

Mast cell

Fibrosis

Repair

Virus

IL-4

LXA4

IL-13

LTD4

ICOS

PGD2

IL-5IL-9 IL-4,IL-13

GM-CSF

IgE isotypeswitch

Basophil

M2

TH2

cell

IL-2

M1

DC

Airway remodelling and neutrophil influx

DC

ILC3

CD4+

T cell

CD4+

T cellMZ B cell

MSC

NeutrophilOX40OX40LCD30

CD30L

IL-23CD40L

CD40

Tissue restorationafter injury

↑ ICAM1↑ VCAM1

IL-22,LTβ MADCAM1 LTα,

TNF

APRIL

GM-CSF

BAFF

DLL1

T cell memorymaintenance

α4β7integrin

Stromalcell

• Survival • Proliferation• IgM, IgA and

IgG production• Plasmablast

differentiation

DC

InflammatoryILC2

Natural ILC2-like

ILC3-like

IL-17

IL-13

ST2

KLRG1low

KLRG1hi

IL-25

IL-33

Candida albicans

IL-17RB

Nippostrongylusbrasiliensis

IL-2, IL-7,IL-33 IL-5,

IL-13

ILC1

Acuteinfection

IBD Homeostasis andtissue repair

Intracellularpathogen

Tumour

Intestinalepithelialcell

Helminth infection orallergen exposure

Gobletcell

Mucus layer

IL-12,IL-18

IL-12,IL-18

IL-6,IL-23

Repair

iILC1

ILC1

ILC2ILC2

ILC3ILC3

Bacterialkilling

Neutrophilrecruitment

IFNγ

IFNγ

IFNγ

IL-17

Phagocytosisandcytotoxicity

NeutrophilAREG

LT, IL-22

IL-33Mucins,AMPs,proliferation

IL-25

IL-22BP

IL-1β,IL-23,retinoic acid

Tolerogenic DC

exILC3

TH17

cell

TCR

MHCAntigen

IgEisotypeswitch

Eosinophil

IL-13

IL-25,IL-33,TSLP

Fibrosis

Mucus production

B cell

IL-2

IL-9

Proliferation and type 2 cytokineproduction

Eosinophilia

IL-5

• Stem cell regeneration

• Epithelial fucosylation

Inhibition of commensal-specific T

H17 cells through

IL-2 consumption

TH2

cell

DC

M1

M1

B cell

Eosinophilia

TH2

cellILC2

ILC2

NCR–

ILC3

Allergy

NCR+

ILC3

Neutrophil

DC

IL-25,IL-33, TSLP

Mast cell

Fibrosis

IgE isotypeswitch

Homeostaticsuppression ofILC2 function

Psoriasis

Keratinocyteproliferation

Basophil

Keratinocyte

E-cadherin

KLRG1

IL-4IL-9

IL-5IL-4,IL-13

IL-2

IL-13

PGD2 GM-CSF

IL-6, IL-8,CCL20

IL-17

IL-22

IL-1β,IL-23

Homeostasis andtissue repair

OVA, papain, HDM, calcipotriol or LPSBacteria Damage

M2

M1

DC

IL-25,IL-33,VIP

Beige adipocyte Metabolic

homeostasis

Beiging

Whiteadipocyte

ILC2

IL-13,MetEnk

Source?

Innate lymphoid cellsJenny Mjösberg

Innate lymphoid cells (ILCs) are recently described populations of lymphocytes that lack rearranged antigen-specific receptors. The ILC family has been divided into three main subsets — ILC1, ILC2 and ILC3 — and also includes natural killer (NK) cells and lymphoid tissue-inducer (LTi) cells. ILCs are increasingly appreciated to have important immune functions at mucosal surfaces, where they respond to signals they receive from other cells in the tissue

microenvironment. However, they can regulate tissue homeostasis, inflammation and repair at both mucosal and non-mucosal sites, including the intestine, lungs and skin, as well as in adipose and lymphoid tissues1. ILC effector functions are mainly mediated through cytokine secretion and through direct cell–cell interactions with stromal cells and other immune cells. This Poster summarizes some of the key features of ILCs in homeostasis and disease.

STEMCELL Technologies STEMCELL Technologies offers a complete portfolio of fast and easy cell isolation products, including solutions for the isolation of ILCs. Our wide range of positive and negative cell isolation kits are proven to rapidly give you high recovery and purity of functional cells from virtually any sample source including fresh and previously frozen peripheral blood mononuclear cells (PBMCs), Leuko Paks, whole blood, bone marrow, lymph nodes, and spleen.• EasySep™ (www.EasySep.com) is a fast, easy and

column-free immunomagnetic cell separation system for isolating highly purified immune cells in as little as 8 minutes. Cells are immediately ready for downstream functional assays.

AbbreviationsAHR, aryl hydrocarbon receptor; AMPs, antimicrobial peptides; APRIL, a proliferation-inducing ligand; AREG, amphiregulin; BAFF, B cell activating factor; BCL-11B, B cell lymphoma 11B; CCL20, CC-chemokine ligand 20; CD30L, CD30 ligand; CD40L, CD40 ligand; DC, dendritic cell; DLL1, delta-like protein 1; EILP, early ILC progenitor; EOMES, eomesodermin; GFI1, growth factor independent protein 1; GM-CSF, granulocyte–macrophage colony-stimulating factor; HDM, house dust mite; ICAM1, intercellular adhesion molecule 1; ICOS, inducible T cell costimulator; ICOSL, ICOS ligand; ID2, inhibitor of DNA binding 2; IFNγ , interferon-γ ; IL, interleukin; IL-17RB, IL-17 receptor B; IL-22BP, IL-22 binding protein; KLRG1, killer-cell lectin like receptor G1; LTD

4, leukotriene D

4; LPS, lipopolysaccharide; LT, lymphotoxin; LTβR, lymphotoxin-β

receptor; LXA4, lipoxin A

4; M1, type 1 macrophage; M2, type 2 macrophage; MADCAM1, mucosal

addressin cell adhesion molecule 1; NCR, natural cytotoxicity receptor; NFIL3, nuclear factor IL-3 induced; OVA, ovalbumin; OX40L, OX40 ligand; PGD

2, prostaglandin D

2; PLZF, promyelocytic

leukaemia zinc finger protein; ROR, retinoic acid receptor-related orphan receptor; RUNX3, runt-related transcription factor 3; ST2, IL-33 receptor; TCF1, T cell factor 1; TCR, T cell receptor; T

H, T helper; TL1, TNF-like ligand 1; TNF, tumor necrosis factor; TSLP, thymic stromal lymphopoietin;

VCAM1, vascular cell adhesion molecule 1; VIP, vasoactive intestinal peptide.

ILC development Much work has been done to define the ontogeny of mouse ILCs; however, human ILC development remains largely uncharacterized. ILCs originate from a common lymphoid progenitor (CLP), which develops into either a common helper innate lymphoid progenitor (CHILP)2 under the influence of transcription factors such as TCF13 and ID2, or into an NK cell progenitor (NKP)4 under the additional influence of EOMES and NFIL3. The subsequent expression of RORγt by the CHILP leads to LTi cell differentiation via the LTi cell precursor (LTiP), whereas PLZF expression marks the development of the ILC progenitor (ILCP) which, under the influence of T-bet, GATA3 or RORγt, gives rise to the ILC1, ILC2 or ILC3 subsets, respectively5. NCR+ ILC3s are characterized by IL-22 production, whereas NCR– ILC3 produce IL-17. Both subsets can differentiate into IFNγ-producing exILC3s. The development of intraepithelial ILC1s (iILC1s) remains to be elucidated.

ILCs contribute to intestinal inflammation and are functionally plasticHuman inflammatory bowel disease (IBD) is associated with an increased frequency of IL-17-producing ILC3s20, which parallels findings in mice, in which Helicobacter hepaticus-induced colitis increases the number of IL-17- and IFNγ-producing ILC3s21. Noteworthy, neutralization of IL-17 in this model, or in clinical trials, does not ameliorate disease, pointing towards a crucial role for ILC3-derived IFNγ in IBD. In mice, intestinal environmental cues induce T-bet expression in RORγt+NCR+ ILC3s, which is crucial for defence against Salmonella infection22. However, this causes collateral damage that presents as enterocolitis. Paralleling these observations, human Crohn's disease is associated with an accumulation of IFNγ-producing ILC1s23. ILC1s can be derived from ILC3s under the influence of IL-12, whereas IL-23 and retinoic acid exposure lead to ILC3 re-differentiation24. Hence, a finely tuned balance of ILC1s and ILC3s ensures tissue integrity while maintaining immune defence in the intestine.

The yin and yang of ILC3s IL-22 produced by NCR+ ILC3s binds to the IL-22 receptor, which is exclusively expressed by non-haematopoietic cells. The tissue protective role of IL-22 in the intestine during intestinal infection has been well documented10 and includes promotion of epithelial cell fucosylation, which supports host–microbiota symbiosis. However, the potent capacity of IL-22 to induce proliferation of stromal cells also implies that excessive IL-22 production may lead to pathology. Indeed, in a mouse model of colorectal cancer, tumour growth was enhanced by ILC3-derived IL-2211. Intriguingly, whereas IL-22 seems mainly protective in the intestine, IL-22-producing ILC3s accumulate in the skin of patients with psoriasis12 and, supported by observations in a mouse model of psoriasis13, this suggests a disease-promoting role for these cells in this tissue. Furthermore, in the lungs, ILC3s may promote obesity-induced airway hyperresponsiveness through the production of IL-17.

• RoboSep™ (www.RoboSep.com), the fully automated cell isolation platform, performs all cell labeling and magnetic isolation steps using EasySep™ reagents to reduce hands-on time and increase laboratory throughput.

• RosetteSepTM (www.RosetteSep.com) is a unique immunodensity cell isolation system for the isolation of untouched cells directly from whole blood during the standard density centrifugation step.

For more information on the complete range of cell separation products available, or to learn more about primary cells, cell culture media, antibodies or other products for your immune cell workflow, please visit our website: www.stemcell.comDocument # 27005 Version 1.0.0

AffiliationsJenny Mjösberg is at the Center for Infectious Medicine, Department of Medicine Huddinge, Karolinska University Hospital Huddinge, Karolinska Institutet, S-14186 Stockholm, Sweden. (jenny.mjosberg@ki.se)

The author apologizes to colleagues whose work has not been cited owing to space limitations.

References and a table of the surface markers expressed by human and mouse ILCs are available online.

Edited by Olive Leavy and Jamie D. K. Wilson; copy-edited by Gemma Ryan; designed by Kirsten Lee and Simon Bradbrook.

© 2015 Nature Publishing Group. All rights reserved.www.nature.com/posters/ilcs/index.html

ILC2s are involved in type 2 inflammationSeveral mouse models and clinical observations support a role for ILC2s in type 2 inflammation in the skin, lungs and intestine6,7,8. ILC2 activation is triggered by IL-25, IL-33, TSLP and PGD2 produced by activated epithelial cells or immune cells in response to helminth infections or allergen exposure. The effector functions of ILC2s are largely mediated by IL-4, IL-5, IL-9 and IL-13 and promote goblet cell hyperplasia, mucus production, eosinophilia, IgE isotype switching and fibrosis1. Importantly, these mechanisms are mainly protective in the setting of helminth infection, in which ILC2 responses are driven predominantly by IL-33 but can become exaggerated and cause pathology in allergy and asthma. Interestingly, ILC2s display functional plasticity, and inflammatory ILC2s may also differentiate into IL-17-producing ILC3-like cells and participate in antifungal immunity9.

The role for ILCs in homeostasis and tissue repair Important tissue protective effects of ILC2s and ILC3s have been described. ILC3s produce IL-22, which is crucial for the repair of thymic tissue following viral infection14 and for intestinal mucosal barrier protection10. In addition, ILC3s can suppress commensal-specific TH17 cells through IL-2 consumption, preventing intestinal inflammation15. In the spleen, ILC3s interact with adaptive immune cells to maintain memory CD4+ T cells16 and marginal zone (MZ) B cells17. Furthermore, ILC2s in adipose tissue produce met-enkephalin (MetEnk), which promotes beiging of adipose tissue18. Lung ILC2s contribute to tissue restoration upon viral insult through the production of AREG19.