Biophysical Immunology Laboratory Thomas Vorup-Jensen Institute for Medical Microbiology and Immunology University of Aarhus Denmark

Innate Immunity Janeway’s Immunobiology Chapter 2&3 Lecture II:(mainly) Soluble (humoral) factors Important messages: Important soluble molecules supporting innate immunity effector functions Connection between molecular structure and function in the immune System Connection between cellular and humoral innate immunity 2

The (very) basic order of events in complement activation: three steps to inflammation Complement factors in solution ( plasma ) Surface bound complement factors Pathogen Cascade deposition: positive amplification loop Conformational change? Recruitment of inflammatory cells Enhanced Phagocytosis (faster clearing!) Direct killing by lysis 3

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”Target-binding” complement proteins are larger than the rest…. Vorup-Jensen & Boesen (2011) Adv. Drug Discov. Rev. 63: nm …but why? Tanaka et al. (2010) J Infect Chemother 16:383–387

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Innate Immunity Janeway’s Immunobiology Chapter 2&3 Lecture II:(mainly) Soluble (humoral) factors Important messages: The classical pathway is activated through antibodies: Major molecular species involved are C1, C2 and C4 supporting to C3 activation 13

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Innate Immunity Janeway’s Immunobiology Chapter 2&3 Lecture II:(mainly) Soluble (humoral) factors Important messages: The alternative pathway is activated spontaneous depostion of C3 on cell surface. Failure to down-regulate C3 activation leads to opsonization of microbes. 19

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Dong et al. J. Immunol. (2007) 178: SAXS solution structure of MBL Trimer of carbohydrate- recognitiondomains 23

Atomic Force Microscopy Mingdong Dong, Sailong Xu & Flemming Besenbacher iNANO, University of Aarhus 24

Constructing a MBL ligand-coated surface suitable for AFM Mannose-amine immobilized on mica through coordination bonds NH 3 O O O SiO 3 - Mineral (mica) structure 25

AFM imaging of rhMBL(I) on a mannosamine-coated surface in liquid Dong et al. J. Immunol. (2007) 178:

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BSA S I = 600 RU S I = 1600 RU S I = 4000 RU 1,000 RU  1 ng protein/mm mcBSA molecules/mm mcBSA molecules/mm mcBSA molecules/mm 2 28

Surface density of ligands change MBL binding kinetics 60 nm K D  M and k d  s -1 d ~ 14 nm d ~ 9 nm d ~ 6 nm 29

Organization of the cell wall of S. aureus: a nm-scaled pattern? Touhami A et al. (2004) J. Bacteriol. 186: 3286– nm 30

Primary immunodeficiency in the innate immune system Induced deficiency in neutrophils 31

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Innate Immunity Janeway’s Immunobiology Chapter 2&3 Lecture II:(mainly) Soluble (humoral) factors Important messages: The lytic pathway may serve to from pores in target membranes. The pore formation will eventually leads to cellular lysis. 35

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Time (adaptive immunity) 39

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Innate Immunity Janeway’s Immunobiology Chapter 2&3 Lecture II:(mainly) Soluble (humoral) factors Important messages: The complement system is an important mediator of cross-talk between innate and adaptive immunity by mediating antigen uptake. 41

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iC3b is ”inactive” with regard to C3 conversion but may bind Complement receptors 3 & 4 45

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Hereditary angioedema: lack of C1INH Treatment: blood transfusion or C1INH protein 47

48 Systemic Lupus Erythematosus (SLE) trialx.com

Innate Immunity Janeway’s Immunobiology Chapter 2&3 Lecture II:(mainly) Soluble (humoral) factors Important messages: Failure to control complement activation leads to significant health problems 49

Innate Immunity Janeway’s Immunobiology Chapter 2&3 Lectures I & II Important messages: Important soluble molecules supporting innate immunity effector Functions Cytokines & complement Connection between molecular structure and function in the immune system Pattern recognition, conformational changes in MBL Connection between cellular and humoral innate immunity Opsonization facilitates antigen presentation to lymphocytes 50