NATURAL IMMUNITY

1. NATURAL IMMUNITY Dr. habil. Kőhidai László Department of Genetics, Cell- and Immunobiology Semmelweis University ImmunologyEPh 2015.09.14.

2. The immune response Natural (innate) Acquired (adaptive) Provides immediate defense Develops with time

3. Innate immunity • First line defense • Limited specifity • Immediate response (no latency) • Linear amplification • No memory • Cellular and humoral defense

4. Immume homeostasis Adaptive T lymphocyte cytokines B lymphocyte antibodies Innate dendritic cell macrophage gd T cell complement system CD5+ B cell antibacterial peptides NK cell granulocytes cytokines

6. Soluble recognition molecules of innate immune system Defensins bacteria, fungi killing Pentraxines C reactive protein (CRP) ECM protein, complement Serum amyloid protein (SAP) microbial cell wall (polysacch., nucl. acids) Collectines Mannose binding lectins Microbial cell wall complement Ficolin (phosphoryl choline, Surface active proteins saccharides) Lipopolysaccharide binding LPS LPS sens. proteins (LBP)

7. First line defence MPS (mononuclear phagocyte system) Cells:macrophages, neutrophils, NK cells, mast cells, dendritic cells Molecules: complement system Barriers: skin, mucous membranes, secretions

8. First line barriers • Mechanical:skin, mucous membranes, cough, sneeze • Chemical: skin pH: 5,5 stomach pH: 1,2-3 • Biological: in the mouth saliva contains antibacterialagents • lysozyme • lactoperoxidase • lactoferrin • antibody - IgA in toothpaste

9. Limited specificity 3 strategies in recognition Pathogen non-self Altered self Missing self Immunereaction is blocked in case of self markers (missing in microorganisms) Non healthy self markers Characteristic markers of pathogens (missing in the host) Missing MHCI - NK cellsactive Missing C3 convertase – alternative complement activation starts Missing sialic acid – phagocytes, alternative complement activation

10. APOPTOSIS NK CELLS: dual receptor system KIR/KAR Tumor or virus infected cell no MHC www.alergias.med.br/ immunolfig02.html

11. Limited specificity 3 strategies in recognition Pathogen non-self Altered self Missing self Immunreaction is blocked in case of self markers (missing in microorganisms) Non healthy self markers Characteristic markers of pathogens (missing in the host)

12. Phagocytes have two types of receptors on their surfaces Opsonic receptors: Fc and complement receptors Pattern Recognition Receptors (PRRs)

13. Opsonization vs.   Facilitation of phagocytosis

14. Fc receptor complement receptor phagocyte antibody complement protein OPSONIZATION bacterium

15. bindIgG facilitate phagocytosis (regulate B-cell activation) Fcγ receptors bind IgE high affinity receptor is expressed on mast cells and basophils role in allergy (low affinity receptor has regulatory function) Fcε receptors Fc receptors Immunoglobulin = Ig IgG Fc region

16. Fc receptor mediated phagocytosis

17. Limited specificity PRR PAMP Fc receptor Complement receptor phagocyte antibody Complement protein OPSONIZATION bacterium

18. Membrane receptors Secreted receptors Intracellular receptor pattern recognition PAMP PRR pathogen-associated molecular patterns pattern recognition receptors

19. Membrane PRR I. Scavenger receptors - CD14: LPS receptor II. Lectin receptors - macrophage mannose receptor III. Toll like receptors -carbohydrates, lipids, nucleic acids

20. LPS receptor Gay et al.Nature Reviews Immunology, 2006

21. Toll-like receptors(TLR) Nucleic acid and lipid/protein TLR ligands are recognized in different cellular compartments. Lipid or proteinTLR ligands: recognized on the plasma membrane e.g. LPS, flagellin Nucleic acidTLR ligands:recognized by TLRs in theendosome. www.natap.org/2006/AASLD/AASLD_57.htm

22. Intracellular cytoplasmatic PRRs • RIG-I-like helicases (RLHs, RLR) recognizeviral 5’-Triphosphate ssRNA • Nod-like Receptors (NLRs) recognize peptidoglycan constituent of Gram positive and Gram negative bacteria Nature Reviews Microbiology5,491-504

23. 5.Intracellular PRR 4. Multiple recognition Recognition – at multiple levels 1.Secreted PRR 3.Membrane PRR 2.Opsonisation Brown GD. Dectin-1: a signalling non-TLR pattern-recognition receptor. Nat Rev Immunol. 2006 Jan;6(1):33-43.

24. Inflammatory respponses Specificity of TLR

25. Main steps of macrophage activity • expression of receptors • release of mediators • internalization of bacteria • phagolysosome formation

26. Immediate response (no latency)

27. SOD Microbicidal activity of professional phagocytes NADPH-ox = NADPH oxidase SOD = superoxide dismutase MPO = myeloperoxidase www.uni-koeln.de/dictyostelium/07_human.shtml Superoxide:O2 + e-O2- Hydrogen peroxide:O2- + e- + 2H+ H2O2 Hydroxyl groups:H2O2 + e- + 2H+ OH- + H2O

28. Takes place even whithout PHAGOCYTOSIS !

29. FEVER Fever is caused by exogenous (e.g. bacterial subst.) and endogenous pyrogenes (products of macrophages). - Major endogenous pyrogens: IL-1, IL-6, TNF-alpha - Minor endogenous pyrogens: IL-8, MIP-1, MIP-2, interferons Brain: Circumventricularorgans IL-1 TNF-

30. Commensal bacterial flora - all the natural bacteria that live on and in a healthy person (skin, oral cavity, upper respirtory tract, lower GI tract, the urogenital tract) = 1013 cells - about 1012 bacteria living in the human gut - in oral cavity e.g. Streptococcus species Benefit to the host: Compete with pathogens for colonization (by competing for nutrition and attachment sites to the epithelium)

31. Differential expression and compartmentalization of TLRs No TLR: commensal bacteria are tolerated– NO recognition Intracellular bacteria – intracellular TLR TLR: Bacteria passing the epithelia Nature Reviews Immunology 8, 411-420 (June 2008)

32. All bacteria that cross the epithelium are recognized by immune cells

33. DANGER !!!

34. Immature dendritic cell How antigens reach lymph node?

35. Bridge between innate and adaptive immunity

36. Adaptive immunity Innate immunity TLR Dendritic cell COSTIMULATION:required for initial activation of T cells

37. Adaptive immune system NOT ONLY A SIMPLE FIRST LINE defence TLR based CONNECTION between natural and adaptive immunity

38. PAMP: Pathogen associated molecular pattern DAMP: Damage associated molecular pattern Nature Reviews Immunology 8, 279-289 (April 2008)

39. Danger only in case of necrotic cell death ! ! Nature Reviews Immunology 8, 279-289 (April 2008)

40. RAGE: (Receptor for advanced glycation endproducts) TREM: Triggering receptor expressed on myeloid cells 1 synergize with TLR4 http://www.invivogen.com/family.php?ID=242&ID_cat=13&ID_sscat=107

41. Aknowledgements Dr. Holub, M. – for her lecture material „Natural Immunity” used as source