innate immunity

Lalita Tearprasert; MD.

Innate Immunity

1

Outline

• Overview of innate immunity • Microbial pattern recognition by innate immunity • Phagocytosis • Inflammatory responses • Antiviral responses • Innate instruction of adaptive immune response

2

3

Overview of Innate Immunity• First line of defense against microbes • Exist before exposure to microbes • Found in Plants, Insects, Vertebrates • 3 Essential function 1.) Initial response to microbes 2.) Eliminate damaged cells and initiate the process of tissue repair 3.) Stimulates adaptive immune response • 2 Major type of responses 1.) Inflammation 2.) Antiviral defense Kuby Immunology 7th edition.

Abbas 8th Edition Innate Immunity, 51-86. Liu A.et al. Middleton's 8th Edition, 1-19.

4 Kuby Immunology 7th edition.

Innate VS Adaptive


1.

2.

Component of innate immunity

1. Anatomical barrier - Physical barriers - Chemical barriers 2. Cell - Phagocytic cells - Dendritic cell - NK cells, ILC 3. Soluble proteins - Complement - Cytokines, Chemokines - Anti-microbial substances

3.

6

1.) Anatomical barriers

• Enzyme • Antimicrobial peptides (AMPs) • pH

• Skin • Mucosal &

Glandular tissues • Mechanical :Cilia

Kuby Immunology 7th edition.

7

2.) Cellular Response (Recognized pathogen by receptors : PRRs) 3.) Soluble proteins

• NK cell - Viral infected cell - Malignancy

• Phagocytic cells -Macrophage, Neutrophil " Phagocytosis " • Dendritic cell >> Activated adaptive immune response

• Cell activation >> Inflammation >> Antiviral defense


8

Microbial pattern recognition by innate immunity

9

Cellular response

• Innate immune system recognizes - PAMPs (Pathogen-associated molecular pattern) : molecular structures of microbial pathogen that required for survival - DAMPs (Damage-associated molecular pattern) : result of cell damage by infections

• Cellular receptors : PRRs (Pattern recognition receptors)

Abbas 8th Edition Innate Immunity, 51-86.

10

PAMPs

1.) Produced only by microbes, not by their hosts 2.) PAMP structures are usually fundamental to the integrity, survival, and pathogenicity of the microorganisms 3.) Shared by entire classes of pathogens

Kuby Immunology 7th edition. Liu A.et al. Middleton's 8th Edition, 1-19.


11

PRRs


12

• Structure: Several families of protein

• Location: Expressed on many effector cells esp. most importantly on the professional APC (Macrophages, Dendritic cells, and B cells) 1.) Transmembrane PRRs 2.) Cytosolic PRRs

• Functions: 3 classes - Secreted PRRs - Endocytic PRRs - Signaling PRRs

Janeway C.et al. NEMJ 2000. 343(5), 338-44. Liu A.et al. Middleton's 8th Edition, 1-19.

Principle functions of PRRs 1.) Opsonization 2.) Activation of complement 3.) Phagocytosis 4.) Activation of proinflammatory signaling pathways 5.) Induction of apoptosis

13

1.) Secreted PRRs

Liu A.et al. Middleton's 8th Edition, 1-19.

14 Liu A.et al. Middleton's 8th Edition, 1-19.

AMPsDefensins & Cathelicidins

15

CollectinsMannose-binding lectin (MBL)

Janeway C.et al. 5th Edition. Abbas 8th Edition Innate Immunity, 51-86.

16

PentraxinsC-reactive protein (CRP)

Fujita Y. et al. Clinical Chemistry 57:10, 1398–1405 (2011).

17

2.) Endocytic PRRs

Mannose receptors (CD206)

• C - Type Lectin Receptors • Recognized carbohydrates (Mannose) - Bacterial, Fungus, Parasite • Expressed on Macrophage • Phagocytosis, NF-kB activation

Kuby Immunology 7th edition. Janeway C.et al. 5th Edition.


18

Scavenger receptors

Kuby Immunology 7th edition. Janeway C.et al. 5th Edition.


• Recognize Lipoproteins on gram + and gram - bacteria • Eliminated old & apoptotic cells • Expressed on Macrophage • Phagocytosis, NF-kB activation

19

4 Major classes of Signaling PRRs 1.) Toll-like receptors (TLRs) : Transmembrane PRRs 2.) C-Type Lectin Receptors (CLRs): Transmembrane PRRs 3.) NOD-like receptors (NLRs) : Cytosolic PRRs 4.) Retinoid acid–inducible gene (RIG)-like receptors (RLRs) : Cytosolic PRRs

Zaru R.Pattern Recognition Receptors (PRRs)

3.) Signaling PRRs

20

Toll-like receptors (TLRs)

21

• Germany, 1980 • Drosophila fruit fly embryos • " Toll " = Weird • Regulation of embryonic development • Cytoplasmic domain of Toll prot. : homologous to IL-1 in vertebrate " Toll-like receptors (TLRs) "


22

Structure of TLRs


• Transmembrane - LLR domain - TIR domain

LxxLxLxxN

23

13 TLRs

D. De Nardo. Cytokine 74 (2015) 181–189.

TLR 1-9 : Human & mouse TLR 10 : Human TLR 11 : Mouse

24

Cellular location of TLRs



Plasma membrane 1/2, 2/6, 4, 5, 11

Endosomes/ Lysosomes membrane

3, 7, 8, 9, 13

26

TLRs signaling pathways

1.) MyD88-dependent pathway - All TLR except TLR3 2.) TRIF-dependent pathway - TLR 3, 4 1.)

2.)

NEMO


TLR4

28

• UNC-93B : multiple-transmembrane-spanning protein in ER - required for endosomal localization & proper function of TLRs 3,7,8,9 - unknown mechanism - genetic def. in UNC-93B >> viral infections esp. Herpes simplex encephalitis


29

Defect affecting TLR signaling

1.) MyD88 defect2.) IRAK4 defect3.) NEMO defect4.) UNC93B defect5.) TLR3 mutation

Esther van de Vosse. et al. Lancet Infect Dis 2009; 9: 688–98. Wong T. et al. Curr Opin Allergy Clin Immunol 2013,13:607–613.

30

NEMO

• Autosomal recessive

• Severe, life-threatening

infections with pyogenic

bacteria

• Invasive bac.

- S. Pneumoniae

- S. Aureus

- P. Aeruginosa

Esther van de Vosse. et al. Lancet Infect Dis 2009; 9: 688–98.

MyD88 Defect& IRAK4 Defect

31

NEMO

• Broad immune dysfunction

• X-linked gene (IKBKG)

1.) Amorphic

2.) Hypomorphic• Gram +, Gram -

esp. S. Pneumoniae


NEMO defect

32

• Amorphic (More common)

Female: Incontinentia pigmenti

Male: Lethal

• Hypomorphic

Female: Carrier

Male: Ectodermal dysplasia

with immunodeficiency


33

TLR3 defect & UNC93B defect

• Childhood Herpes Simplex

Encephalitis

• TLR3 : AD, AR (required to induce

Type 1 IFN to protect

HSV-1 in CNS)

• UNC-93B : AR

Wong T. et al. Curr Opin Allergy Clin Immunol 2013,13:607–613.

34

Nucleotide-binding oligomerization domain-like receptors (NLRs)

35

• Cytosolic PRRs • Recognized - PAMPs & DAMPs - Stress/ Damage signal • Similar to the TLRs : linked to signal transduction • NLR family : 23 Members


Chen et al.Annu. Rev. Pathol. Mech. Dis. 2009.4:365-98.

NOD-Like Receptors (NLRs)

36

Structure of NLRs

• 3 Domains - C-terminal Leucine-rich repeat domain (LRR) - Central nucleotide binding & Oligomerization >> NACHT, NOD, NBD - N-terminal Effector binding domain (EBD) >> CARD, PYD, BIR


Chen et al.Annu. Rev. Pathol. Mech. Dis. 2009.4:365-98.

37 Saxena and Yeretssian. Frontiers in immunology. July 2014.

NLRs subfamily

38

NOD

• Member of CARD domain containing NOD family • NLRC subfamily • Expressed on several cell types : Mucosal epithelial cells, Phagocytes • Response to bacterial cell wall peptidoglycans • 2 Groups - NOD 1 (CARD4) - NOD 2 (CARD15)


Nature Reviews Immunology 14, 9–23 (2014)

39 Chen et al.Annu. Rev. Pathol. Mech. Dis. 2009.4:365-98.

NOD Response to bacterial cell wall peptidoglycans - NOD 1 : iE-DAP - NOD 2 : MDP

40

NOD 1

• Recognizes Diaminopimelic acid (DAP) derived mainly from gram-negative bac. peptidoglycans


NOD 2

• Recognizes Muramyl dipeptide (MDP) derived both gram-negative & gram-positive bac. peptidoglycans • Highly expressed in intestinal Peneth cells • Mutations : Crohn disease (Bac. overgrowth --> chronic inflammation) • Gain-of-function : Blau's syndrome (systemic inflammatory disease)

41 Ramanan D. et al. Immunity 2014, (41), 311-324.

42HS Jin, et al.

Journal of Bacteriology and Virology 2014, 44(3), 215-25.

NLRs signaling pathways

1.

2.

3.CARD9 NEMO

43

Inflammasome

Kuby Immunology 7th edition. H. Kumar et al. International Reviews of Immunology, 30:16–34, 2011.

• Large protein complex that activates caspase-1 to generate IL-1 • Containing

1.) NLR subfamily - NLRP 1 - NLRP 3 - NLRC 4/ IPAF 2.) Non-NLR/ Adaptor protein Ex. ASC, AIM2 3.) Caspase-1 (inactivate)

44

Variety stimuli activated Inflammasome


NLRP3 Inflammasome

- Monocyte - Macrophage - Neutrophils - DC - Lymphocyte

45

Cryopyrin-associated periodic syndrome(CAPS)

NLRP 3 mutation >> Auto-inflammatory disease• Muckle-Wells syndrome

• CINCA

• Familial cold autoinflammatory syndrome


46

C-Type Lectin Receptors (CLRs)

47

• Plasma membrane receptors - monocytes, macrophages, dendritic cells, neutrophils, B cells, and T-cell subsets

• Recognize carbohydrate components of fungi, mycobacteria, viruses, parasites, and some allergens (peanut and dust mite proteins)

• Human : 15 CLRs that function as PRRs • Most recognize sugar moieties

- mannose --> mannose receptor, DC-SIGN - fucose --> Dectin-2, DC-SIGN - glucans --> Dectin-1


48Kuby Immunology 7th edition.

Janeway's Immunobiology. 2012.

• CLRs functions : Variety function - Signaling - Phagocytosis


CLRs signaling pathways

50

Chronic Mucocutaneous Candidiasis (CMCC)

• Dectin-1 defect (recognized B-glycan in cell wall of candida)

51

RIG-Like Receptors (RLRs)

52

• Soluble PRRs • Sensors of viral infection ex. Influenza, Measles • Recognize the RNA viruses in the cytoplasm of infected cells --> induce inflammatory cytokines and type I interferons • 3 Members : CARD-containing RNA helicase 1.) RIG-I 2.) MDA5 3.) LGP2



Signaling of RLRs

54H. Kumar et al.

International Reviews of Immunology, 30:16–34, 2011.

55

Phagocytosis


1.) Direct : PRRs rec.

• Macrophage, Neutrophil, DC : Tissue • Monocyte : Blood

57

Kuby Immunology 7th edition. Janeway's Immunobiology. 2012.


58

" Opsonization " (to make it tasty) - recognition of soluble proteins that have bound to microbial surfaces - Soluble prot. = Opsonin

2.) Indirect : Opsonin rec.

Major opsonin 1.) Lectin 2.) C3b 3.) IgG


60

Inflammatory response


Acute Phase : Local inflammatory response

62

• Phase - Acute : Local inflammation followed by healing - Chronic : Long- term, not resolved • Hallmarks of a localized inflammatory response : Redness, Swelling, Warm, Pain - Vasodilatation >> Warm, Redness - Increased Vascular permeability >> Swelling

Kuby Immunology 7th edition. Abbas 8th Edition Innate Immunity, 51-86.

63

Acute Phase Response proteins (APRs)

• Normally found in blood at low concentrations • Secreted from hepatocyte of liver following stimulation by proinflammatory cytokines (TNF-alpha, IL-1, IL-6) • Function as "opsonin" • Ex. - C-reactive protein (CRP) - Mannose-binding lectin (MBL) - Serum amyloid protein (SAP) - Complement factor - Fibrinogen


64 Abbas 8th Edition Innate Immunity, 51-86.

Local & Systemic actions of cytokines in inflammation

65

Antiviral response

66

• Major way : Induce expression of type 1 interferons >> Inhibit viral replication • Type 1 interferons : IFN-alpha, IFN-beta - Encoded by gene on chromosome 9 - most important in viral defense : IFN-alpha (from Plasmacytoid DC & Mononuclear phagocytes) • Most potent stimuli : Viral nucleic acid (DNA, RNA) • Type 1 interferons receptors : IFNAR1, IFNAR2 (All nucleated cells)


67

Induction of Type 1 Interferons


68

Action of Type 1 interferons

69

Innate Instruction of Adaptive Immune Response

70 Abbas 8th Edition Innate Immunity, 51-86.

Stimulation of adaptive immunity by innate immunity

" Two-Signal hypothesis "

71 Janeway C.et al. NEMJ 2000. 343(5), 338-44.

73

Interleukin-12/interferon-gamma axis

Wong T. et al. Curr Opin Allergy Clin Immunol 2013,13:607–613.

• Mendelian susceptibility to

mycobacterial disease (MSMD)

7 Autosomal

- IRF8

- STAT1

- IL12B, IL12RB1 (40%)

- IFNGR1 (XL) , IFNGR2

- TYK2

Susceptible to - Mycobacterium tuberculosis- Salmonella


1.

2.

3.

4.

5.

75

Thank you

innate immunity

Health & Medicine