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Sunrise Free Radical School Inflammation and Immunity: From Innate Oysters to Adaptive Humans J. John Cohen Department of Immunology University of Colorado Medical School john. cohen@uchsc. edu Inflammation and Immunity SFRBM Education Program Cohen 1

Metchnikoff 1883 Metchnikoff watched the reaction to a thorn inserted into a mollusk. Hemocytes (amoebocytes) arrived and tried to ingest the foreign body; if they could not, they walled it off, gradually converting into, or recruiting, fibroblasts. We do exactly the same thing to foreign bodies. Source: Wikipedia Inflammation and Immunity SFRBM Education Program Cohen 2

Mouse macrophage Oyster hemocyte The similarity between an invertebrate phagocyte and our own is striking; they also use many of the same mechanisms, including the production of reactive oxygen species. http: //www. mdsg. umd. edu/oysters/oysblood. htm Inflammation and Immunity http: //itgmv 1. fzk. de/www/itg/diabate/images. html#fig 5 SFRBM Education Program Cohen 3

silicone droplets chromic catgut Foreign body reactions in the human. The suture material is not digestible by macrophages, so it has been walled off by fibroblasts. Atlas of Granulomatous Diseases Yale Rosen, M. D. Inflammation and Immunity The clear (unstained) globules of silicone have been released from a ruptured breast implant. They also cannot be ingested, and this early stage shows the accumulation of macrophages, including one that has become a multinucleated giant cell showing the “asteroid bodies” characteristic of the foreign body reaction. SFRBM Education Program Cohen 4

Toll Like Receptors • The next slide shows a schematic that gives a feel for the multiple Toll-like receptor (TLR) pathways. • These receptors respond to foreign molecular patterns (PAMPs), so they are referred to as PRRs. • Recognized motifs include: lipopolysaccharide (LPS) from Gram-negative cell walls, peptidoglycans from the cell walls of both Gram-negative and – positive bacteria, viral double-stranded RNA, and Cp. G-rich bacterial DNA. • The result of the signals in all cases is a pro-inflammatory response and the release of chemokines and cytokines. Review: Beutler B. Inferences, questions and possibilities in Toll-like receptor signaling. Nature. 2004 Jul 8; 430(6996): 257 -63. Inflammation and Immunity SFRBM Education Program Cohen 5

Ligands are PAMPs (pathogenassociated molecular patterns); Receptors are PRRs (patternrecognition receptors) Inflammation and Immunity SFRBM Education Program Cohen 6

The structure of two chemokines, HCC 2 and, in the inset, eotaxin, shows their overall similarity. Their receptors are 7 -span transmembrane structures which are, in general, ion channels that result in cell activation. Chemokines are low molecular weight peptides whose major role is in inflammation. HCC 2, a chemokine CCR 5, a chemokine receptor Source: Aegis (CDC) Source: Protein data base (PDB) Inflammation and Immunity SFRBM Education Program Cohen 7

Oyster family Human family http: //faculty. haas. berkeley. edu/arose/Asher 1 st 2. htm In ecology, there are r-strategists and K-strategists. Oysters are r-strategists: they have huge numbers of progeny but invest relatively little in the survival of any individual; their survival is statistical. So they have the simple innate immune response, but cannot amplify it, nor do they adapt to specific challenges. The human is a K-strategist; small litters, but a heavy investment in individual survival. So we (jawed vertebrates) have added the adaptive immune response which vastly increases our chances (remember the Bubble Boy, born without an adaptive immune response and. Immunity unable to live in the SFRBM real world). Inflammation Education Program Cohen 8

Dendritic cell iccosomes Dendritic cells are the link between innate and adaptive immunity. They are superb phagocytes. Inflammation and Immunity David Hunt. Cell Systems Initiative, U. of Washington. SFRBM Education Program Cohen 9

Dendritic Cells • When dendritic cells are bathed in the cytokine and chemokine products of the innate response, they change, and move from the local area through the lymphatics to the draining lymph node (next slide) as they mature into the best antigen-presenting cells. • Iccosomes are clumps of stored antigen-antibody immune complexes, which allow the dendritic cell to stimulate immunity for a long time. • Dendritic cells enter the lymph node via the afferent lymphatics and percolate through the substance of the node, positioning themselves at the interface between T and B cell areas. There they display their processed antigenic peptides on both MHC Class I and Class II, so that it can be recognized by the best-fitting receptors of both CD 4 (helper) T cells (which see antigen on Class II) and CD 8 (killer) T cells (which see antigen on Class I). Inflammation and Immunity SFRBM Education Program Cohen 10

chemokines cytokines PAMP PRR T Immature dendritic cell Mature dendritic cell Inflammation and Immunity SFRBM Education Program Cohen 11

Antigen is picked up by a dendritic cell and taken to the draining lymph node, where it is presented to T cells. Artist: Helen Macfarlane Inflammation and Immunity SFRBM Education Program Cohen 12

The peptides are now on the cell surface, presented on MHC Class II molecules and cross-presented on MHC Class I Inflammation and Immunity SFRBM Education Program Cohen 13

LYMPH NODE A: Germinal centres (B cells) B: Zone of T, B, and DC contact C: Paracortex (T cells) D: Afferent lymphatics E: Subcapsular sinus F: Efferent lymphatic F Inflammation and Immunity SFRBM Education Program Cohen 14

A helper T cell with the correct receptor recognizes peptide + MHC and becomes activated Inflammation and Immunity SFRBM Education Program Cohen 15

T Cell Receptor MHC foreign peptide T Cell Inflammation and Immunity Dendritic Cell SFRBM Education Program Pique, Garcia, Wilson: Scripps Cohen 16

Members of the helper cell family • There are 3 cells in the helper family. • Th 1 cells are the activators of delayed hypersensitivity and are sometimes thought of as “pro-inflammatory”. Their characteristic cytokine, interferon-gamma, is strongly chemotactic for macrophages. • Th 2 cells help B cells make antibody. Their cytokines oppose Th 1 development (Th 1 cytokines oppose Th 2 development, so there is “sibling rivalry”). Thus Th 2 are sometimes thought of as anti-inflammatory. • Newly recognized are the Tregs, whose cytokines shut down both Th 1 and Th 2 responses. This is one of the hot areas in immunology. Inflammation and Immunity SFRBM Education Program Cohen 17

APC Th 1 IL-2, IFN-γ APC IL-10, Treg TGFβ APC IL-4, IL-5, Th 2 IL-10 Inflammation and Immunity SFRBM Education Program Inflammation, delayed hypersensitivity Downregulation of immunity B cell help; sometimes suppression of inflammation Cohen 18

Activated T cells divide T Inflammation and Immunity SFRBM Education Program Cohen 19

T Activated Th 1 cells release lymphokines Many macrophages are attracted Inflammation and Immunity SFRBM Education Program Cohen 20

All cells show peptides from the proteins they make, including virus and tumor proteins, on MHC Class I molecules V Inflammation and Immunity V V SFRBM Education Program Cohen 21

Foreign or abnormal peptides + MHC are recognized by a cytotoxic (killer) T cell V V V CTL Killer T cells (cytotoxic T lymphocytes, CTL) actually don’t kill; they induce their targets to kill themselves by apoptosis. There are two pathways, one dependent on the exocytosis of granules, the other on transmembrane signaling via the Fas- Fas ligand Inflammation and Immunity SFRBMinteraction. Education Program Cohen 22

The CTL transmits a death signal Granule exocytosis V V V CTL Fas: Fas ligand Inflammation and Immunity SFRBM Education Program Cohen 23

The abnormal cell dies by the process of apoptosis At the meeting a video of a CTL inducing apoptosis in a virus-infected cell was shown. It was obtained from Cells Alive! http: //www. cellsalive. com/ctl. htm Inflammation and Immunity SFRBM Education Program Cohen 24

Why adaptive? Amplification of inflammation T cell clones expand 64, 000 x in 4 days Each activated Th 1 cell attracts 1, 000 macrophages Cytokine-stimulated macrophages are “angry” Repertoire Almost unlimited number of epitopes recognized Memory Secondary responses: sooner, steeper, faster, higher lower threshold Inflammation and Immunity SFRBM Education Program Cohen 25