NTD Vaccine Design Toolkit and Training Workshop Providence, RI January 05, 2011 Cytokines Leslie P. Cousens, PhD EpiVax, Inc.

NTD Vaccine Design Toolkit and Training Workshop Providence, RI January 05, 2011 Cytokines Leslie P. Cousens, PhD EpiVax, Inc.

Cytokines

Properties of Cytokines Cytokines are proteins with specific roles in communication between cells of the immune system. Cytokine: Any low-molecular-weight regulatory protein or glycoprotein (normally less than 30kD) secreted by immune cells or other cells of the body in response to an stimuli. Cytokines through interaction with specific cellsurface receptors, regulate the development or function of another cell.

Properties of Cytokines Many cytokines are referred to as interleukins because they are secreted by some leukocytes and act on other leukocytes. Interleukins 1-35 + have been identified. Chemokines are a subgroup of cytokines that affect chemotaxis and other leukocyte behaviors. Chemokines play an important role in inflammation.

Cytokine Families The hematopoietin family. The interferon family. The interleukin family. The chemokine family. The tumor necrosis factor family.

Properties of Cytokines Cytokines bind to specific receptors on a target cell and trigger a signal transduction pathway that changes gene expression. Inducing Stimulus Cytokine Gene Cytokine Producing Cell Cytokines In general, cytokines have very high affinity for their receptors, so are effective in picomolar concentrations. Gene Activation Cytokine Receptor Target Cell Biological Effects

Properties of Cytokines Autocrine: Cytokine-Producing Cell Cytokines Target Cell Paracrine: Endocrine: Cytokine-Producing Cell Cytokines Target Cell Cytokine-Producing Cell Cytokines Circulation Target Cell

Cytokine Effects Cytokines can be pleiotropic, redundant, synergistic, antagonistic, and/or inducers of cascades. This array of attributes allow them to regulate cellular activity in a coordinated and interactive manner.

Select Innate Cytokines Type I IFN IFN ( ) Virus-infected cells, Any cell pdc, Macrophages, NK cells Fibroblasts T cells Directly antiviral, increases MHC class I, activates NK cells

Select Adaptive Cytokines

IFN-

IL-2

Cytokines can be Pleiotropic Pleiotropic: Having different biological effects on different target cells. Y Activation Proliferation Differentiation B Cell Proliferation Activated Th Cell IL-4 Thymocyte Proliferation Mast Cell

Cytokines can be Redundant Redundant: Two or more cytokine can share a similar effect/function. IL-2 IL-4 Proliferation Activated Th Cell B Cell IL-5

Cytokines can be Synergistic Synergistic: The effect of 2 cytokines together exceeds the additive effect of each individual cytokine. Activated Th Cell IL-4 + IL-5 B Cell Antibody Isotype Class Switch to IgE

Cytokines can be Antagonistic Antagonistic: The effect of a 2 nd cytokine nullifies or reverses the effect of the 1 st. Activated Th Cell IL-4 X B Cell Inhibits Antibody Isotype Class Switch to IgE IFN-

Cytokine Cascade Induction Activated Th Cell Certain cytokines induce a pyramid of effects, including a cascade of cytokine secretion. The action of one cytokine on a target cell induces that cell to produce one or more cytokines. This, in turn, may induce other target cells to produce other cytokines. IFN- IL-12 Macrophage Activated Th Cell IFN-, TNF, IL-2, and other cytokines

Cytokine Functions More than 200 proteins with cytokine activity have been described. Cytokines perform numerous biological functions: o Development of cellular and humoral responses o Induction of the inflammatory responses o Regulation of hematopoiesis o Control of cellular proliferation and differentiation o Healing of wounds

Regulation of Cytokine Function Cytokines act in an antigen-nonspecific manner. Cytokines effect any cells that bear the appropriate receptors and are in a physiological state to respond to cytokines.

Regulation of Cytokine Function Three main factors control cytokine effects: o Receptor expression by target cells only after antigen activation o Direct interaction between the cytokine-producing cell and the target cell ensures that effective concentrations are present only locally. o Short half lives in bodily fluids

Cytokine Receptors Subfamilies of receptors: Specificity conferred by dimeric/trimeric structure Common signaling subunits access intracellular machinery

Cytokine Signal Transduction o Cytokine binds to receptor o Trans-P* of Jaks triggered o STATS are recruited o P*-STATS dimerize in specific combos o Chains of Receptor aggregate o Activated Jaks P* Receptors o STATS are P* o Translocate to the nucleus o Initiate gene transcription

Cytokine Signal Transduction Redundancy: 4 Jaks, 6 STATS Specificity: Receptor availability Jaks Availability of STATS Availability of promoters Variety: Downstream responses

Cytokine Feedback Loop: o Innate immune recognition by APC o The APC makes IL-12 o IL-12 promotes Th1 differentiation o Th1 cells make IFN, IL-2, TNF o Inhibit Th2 development o Promote APC activation; Th1 development

An Inside Look at a Cytokine Feedback Loop: o APC:T Cell Interaction o T Cells receive signals through TCR o T Cells integrate multiple inputs o Signals through TCR o Signal through cytokine Rs o Available transcription factors o Feedback loops at each level help maintain a particular phenotype

Cytokine Networks Cytokine networks are complex. The major cytokine-producing immune cells in the body are Th cells, dendritic cells, and macrophages. Cytokines released by these cells activate an entire network of interacting cells.

Cytokine Networks

Th1 Differentiation

Th2 Differentiation

Immune Response to a Viral Infection

Cytokines Cytokines through interaction with specific cell-surface receptors, regulate the development or function of another cell. Who? What? When? Where? How? Cytokines coordinate immune responses to effectively eliminate pathogens. Understanding coordination of cytokine responses can be applied to vaccine design and development.