EPITHELIAL CELLS Pattern recognition receptors (PRR) Cytokine, chemokine secretion

1. CELLS & MECHANISMS OF INNATE IMMUNITY • EPITHELIAL CELLS • Pattern recognition receptors (PRR) • Cytokine, chemokine secretion • NEUTROPHIL GRANULOCYTES • Phagocytósis • Intracellular cytotoxicity • MONOCITE – MACROPHAGE – DENDRITIC CELL NETWORK • Pattern recognition receptors (PRR) • Internalizing receptors • Phagocytosis • NATURAL KILLER CELLS • Cytotoxicity • Cytokine production

2. FIRST LINE OF DEFENSE BY INNATE IMMUNITY Soluble proteins – Defensins Enzymes - Complement system - Chemotaxis Recognition by Pattern Recognition Receptors Macrophage & dendritic cell subsets Neutrophils Pro-inflammatory cytokine secretion Local effects Systemic effects Chemokine receptors & ligands – cell recruitment, other functions Cytotoxicity – NK cells

3. CONTACT SURFACES Physical, chemical, biological borders GASTROINTESTINAL SYSTEM AIRWAY SYSTEM Sinuses Trachea Lungs EYE Stomach Alimentary tract Oral cavity Esophagus UROGENITAL SYSTEM Kidney BladderVagina SKIN WALDEYER RING Tonsils, adenoids Palatinal, pharyngeal lingual and tubar tonsils Demage Infection Mucus glycoproteins, proteoglycanes, enzymes

4. THE EPITHELIUM AS AN IMPORTANT FIRST LINE OF DEFENSE EPITHELIAL MONOLAYER

5. DEFENSE LINES OF NATURAL IMMUNITY ANATOMICAL BORDERS Skin Inhibits entry of pathogens, pH3 – 5 inhibits growth Mucosa Normal bacterial flora competes for binding sites and nutrients Mucus keeps away pathogens from the surface Cilia remove pathogens PHYSIOLOGICAL BORDERS Temperature Physiological body temperature and fever inhibits growth of certain pathogens Low pH Most pathogens are destroyed in the stomach Chemical Lysosyme degrades bacterial cell wall Type I interferons induce anti-viral resistance The complement system is able to lyse bacteria and promotes phagocytosis PHAGOCYTOSIS/ENDOCYTOSIS Many cells can take up microorganisms by receptor-mediated internalization Special professional phagocytes (monocyte, neutrophil, macrophage) are able to internalize, kill and degrade microorganisms INFLAMMATION Tissue demage and infection results in the leakage of anti-bacterial proteins and peptides to the affected tissue Phagocytic cells leave the blood stream and enter inflammed tissues

6. ORGANIZATION OF IMMUNE CELLS UNDER EPITHELIAL SURFACES NK cell NKT cell Granulocyte Macrophage Dendritic cell Epithelial cells Stroma cells DC PERIFÉRIÁS SZÖVETEK PERIFÉRIÁS LIMFOID SZERVEK TISSUE – SPECIFIC CELLULAR COMMUNICATION NETWORKS

7. PHAGOCYTOSIS, RECOGNITION RECEPTROS, SIGNAL TRANSDUCTION, EFFECTOR MECHANISM Pattern recognition Receptors (PRR) Engagement of PRR triggers phagocytosis and cytokine production

8. Chemoattractant cytokines called chemokines direct migration of leukocytes to the appropriate anatomical sites

9. FAGOCYTE SYSTEM GRANULOCYTES MONOCYTE – MACROPHAGE – DENDRITIC CELL Defence against infectious diseases Elimination of tumor cells Transplantation Gatekeeper function Sensing commensals and pathogens Rapid activation of innate immunity Priming adaptive immune responses Maintenance of self tolerance

10. RECOGNITION BY THE INNATE IMMUNE SYSTEM

11. PHAGOCYTES ARE ABLE TO RECOGNIZE PATHOGENS Toll receptor-mediated signaling Toll receptor PHAGOCYTES (macrophages, dendritic cells, neutrophil granulocytes) RECOGNIZE PATHOGENS BY PATTERN RECOGNITION RECEPTORS RECOGNITION IS ESSENTIAL Macrophage, dendritic cell – ACT AS TISSUE SENSORS (GATE KEEPERS) Neutrophil granulocytes – MIGRATE FROM THE BLOOD TO THE SITE OF INFLAMMATION

12. INNATE/NATURAL IMMUNITY RECOGNITION Richard Pfeiffer, a student of Robert Koch – ENDOTOXIN There must be a receptor that recognizes endotoxin Lipopolysaccharide (LPS) receptor remained elusive The Dorsoventral Regulatory Gene Cassette Spätzle/Toll/Cactus controls the potent antifungal response in Drosophila adults Bruno Lemaitre, A Hoffmann et al, Cell, 1996 Spätzle: Toll ligand Toll: Receptor Cactus: I-kB Dorsal: NF-kB Drosomycin is not synthesized

13. INNATE (NATURAL) IMMUNITY RECOGNIZING RECEPTORS PROTECTIVE MECHANISMS Enzyme systems Multicellular (Metazoa) Sea urchin 600 million years Toll-receptors C. elegans Drosophila 700 million years complement IN PLANTS

14. TOLL RECEPTORS RECOGNIZE VARIOUS MICROBIAL STRUCTURES Virus Bacteria ssRNS dsRNA CpG DNA Gram- Flagellin Peptidoglycane LPS Gram+ TLR9 TLR7 TLR8 TLR3 TLR2 TLR6 TLR5 TLR4 Interferon producing cell PC/DC IFN Macrophage/Dendritic cell ALL STRUCTURES ARE ESSENTIAL FOR THE SURVIVAL OR REPLICATION OF THE PATHOGEN

15. DANGER SIGNALS ARE TRANSLATED TO CYTOKINE SECRETION THROUGH VARIOUS MOLECULAR SENSORS IN DC SUBTYPES 4 6 6 2 1 1 NLR RLH RLH IL-1β IL-12/23 IL-10 IFNαβ NK/DC Th1/Th17/Th2 5 10 7 3 9 7 8 NLR=NOD/NALP (IL-1β) RLH=RIG-1/MDA5 (IFN) Plasmacytoid DC Conventional DC TLR1 – bacterial lipoprotein (together with TLR2) TLR2 – bacterial lipoprotein, peptidoglycane, lipoteicholic acid (heteromer with TLR1 and TLR6) TLR3 – viral dsRNS, polyI:C TLR4 – bacterial LPS TLR5 – bacterial flagellin TLR6 – bacterial lipoprotein (with TLR2) TLR7 – viral ssRNA TLR8 – GU rich viral ssRNS, imidazoquinolin (antiviral drug) TLR9 – unmethylated CpG DNA TLR10 – mdified viral nucleotides

16. CONSERVED RECEPTORS/SENSORS THAT DETECT DANGER SIGNALS TLR TLR3 MEMBRANE Fibroblast Epithelial cell DC LRR CELL MEMBRANE Bacteria MEMBRANES OF INTRACELLULAR VESICLES vírus TIR domain TIR: Toll-Interleukin Receptor signaling domain

17. SIGNALING IN INNATE IMMUNITY

18. TOLL RECEPTORS ACTIVATE PHYLOGENETICALLY CONSERVED SIGNAL TRANSDUCTION PATHWAYS TLR3 TLR4 Fungus CD14 Protease Spätzel Toll TRIF Tube IRF3 STAT1 Relish Pelle Cactus NFkB IFN Peptid Bacterium LPB LPS TLR4 CD14 MyD88 IRAK IL-1R associated Kinase Inflammation Acute phase response Danger signal IL-6 Drosophila Macrophage

19. Sensing of LPS by TLR4 leads to activation of the Transcription factor NFkB and the synthesis of inflammatory cytokines.

20. TLR4 activation can lead to the production of either inflammatory cytokines or antiviral type I interferons.

21. TOLL RECEPTOR MEDIATED SIGNALLING NEW THERAPEUTIC TARGET Figure 3 The 'hourglass' shape of the innate immune response. Although microbial stimuli are chemically complex and although the innate immune response ultimately involves the activation of thousands of host genes, innate immune signals traverse a channel of low complexity. Ten Toll-like receptors (TLRs), four TIR (Toll/interleukin-1 receptor homologous region) adaptors and two protein kinases are required for most microbial perception. This circumstance lends itself to effective pharmacotherapeutic intervention. NF-B, nuclear factor-B; STAT1, signal transducer and activator of transcription 1.

22. THE ACUTE PHASE RESPONSE IL- 6 Mannose binding lectin/protein MBL/MBP COMPLEMENT C-reactive protein COMPLEMENT Fibrinogen Serum Amyloid Protein (SAP) Mannose/galactose binding Chromatin, DNA, Influenza Liver IL-6 induces the production of acute phase protiens

23. RECOGNITION BY SOLUBLE MOLECULES MANNOSE BINDING LECTIN

24. PHAGOCYTES ARE ABLE TO RECOGNIZE PATHOGENS MANNOSE RECEPTOR MANNOSE BINDING LECTIN Toll receptor CR3 Toll receptor OTHER PATTERN RECOGNITION MOLECULES

25. Eukariotic cells Mannose GLYCOSYLATION OF PROTEINS IS DIFFERENT IN VARIOUS SPECIES Prokariotic cells Galactose Glucoseamin Sialicacid Mannose

26. Mannose Bacterium Mannose Receptor MANNOSE RECEPTORS ON PHAGOCYTES Macrophage/dendritic cells

27. PATTERN RECOGNITION BY MANNAN BINDING LECTIN Bacterium lysis Complement activation LECTIN PATHWAY CR3 Macrophage Phagocytosis Strong binding No binding