Cytokines

1. Lu Qing, PhD，MDDepartment of ImmunologySchool of Medicin, Fudan UniversityTel：5423-7093E-mail: fluqing@fudan.edu.cn Cytokines

2. What are cytokines? • “Cytokines” are soluble protein secreted by the cells of innate and adaptive immunity and therefore mediate many of the functions of these cells • Based on their cellular sourcesmonokines (mononuclear phagocyte)lymphokines (lymphocytes)interlukins (leukocytes) (IL-1, IL-2, etc.) • A subfamily of cytokines primarily functions in directing migration of cells, these are called “chemotactic cytokines” or “chemokines”

3. Cytokines • General Properties • Functional Categories of Cytokines • Cytokine Receptors • Biologic Actions

4. Cytokines • General Properties • Functional Categories of Cytokines • Cytokine Receptors • Biologic Actions

5. Innate and adaptive Immunity

6. Phagocytes-identify, ingest, and destroy microbes • Mononuclear phagocytes • Neutrophils (polymorphonuclear leukocytes) Short-lived (6h); the most abundant population of circulating WBCs;mediate the earliest phase of inflammatory response

7. (b) Bacterium becomes attached to membrane evaginations called pseudopodia Bacterium is ingested, forming phagosome Phagosome fuses with lysosome Lysosomal enzymes digest captured material (a) Digestion products are released from cell

8. NK cells-kill infected cells and tumor cells • perforin/granzyme (cytolysis) • Fas/FasL • TNF-/TNFR-I Cell apoptosis

9. As a result of cellular activation: NK cells secret cytokine, mainly IFN-g—to activate macrophage to destroy phagocytosed microbes. Mononuclear phagocytes are the principal source of cytokines of innate immunity • Tumor necrosis factor (TNF) • IL-1 • IL-12 • Type I IFNs • IL-15 • IL-18

10. Innate and adaptive Immunity

11. Three elemental R‘s of T-cell biology: repertoire, recognition, response Repertoire of clones Recognition phase Recognition of processed antigens: peptide-MHC Cytokine production is one of the principal response of T cells to antigen recognition Activation phase Effector phase ResponseClonal expansionFunctional differentiationMemoryTolerance to self TH1（IFN-）TH2（IL-4,5, 13）TH17（IL-17）TR1（IL-10）Foxp3+TregCTL

12. T lymphocytes in response to Ags are the principal sources of cytokine in adaptive immunity . • The function of T helper cells is mediated by cytokines

13. What are cytokines? • Cytokines are polypeptides produced by the cells of innate and adaptive immunity in response to microbes and other antigens as a result of cellular activation. • Cytokines initiate their actions by binding to specific membrane receptors on target cells. • The cellular responses to most cytokines consist of gene activation, resulting in the expression of new functions and sometimes the proliferation of the target cells

14. Autocrineaction act on cytokine-producing cell itself Paracrine action act on a nearby cell circulation Endocrine action act at a distance from the site of infection Cytokine actions may be local and systemic

15. T lymphocytes often secret cytokines at the site of contact with antigen-presenting cells . Most cytokines act close to where they are produced

16. pleiotropism • redundancy • synergy • antagonism

17. Cytokines • General Properties • Functional Categories of Cytokines • Cytokine Receptors • Biologic Actions

18. Functional Categories of Cytokines • Mediators and regulators of innate immunityTumor necrosis factor (TNF), IL-1, IL-6, IL-12, Type I IFNs, IL-15, IL-18,chemokines • Mediators and regulators of adptive immunityIL-2, IL-4, IL-5, IFN-g, TGF-, LT(TNF- ), IL-13,etc • Stimulators of hematopoiesisgranulocyte-CSF, G-CSF macrophage-CSF，M－CSF granulocyte-macrophage-CSF, GM-CSF) erythropoietin, EPO TPO stem cell factor, SCF

19. Cytokines • General Properties • Functional Categories of Cytokines • Cytokine Receptors • Biologic Actions

20. Cytokine Receptors • Type I cytokine receptors • Type II cytokine receptors • Ig superfamily • TNF receptors • Seven-transmembrane -helical receptors *Classification of cytokine receptors based on structural homologies among the extracellular cytokine-binding domain.

21. -S-S- -S-S- -S-S- Cytokine receptor families and ligands Ig superfamily Type I cytokine-R Type II cytokine-R TNF-R Chemokine-R C1C3C2 C1C3C2 C1C3C2 Conserved cycteins CC C C C1C3C2 WSXWS G protein IL-2 IL-3 IL-4 IL-5 IL-6 IL-7 IL-9 IL-11 IL-12 IL-13 IL-15 OSM GM-CSF G-CSF EPO TNF-a TNF-b CD40L NGF FASL IFN-a IFN-b IFN-g IL-10 IL-1 M-CSF C-kit IL-8 RANTES MIP-1 PF4

22. IL-2R IL-4R IL-7R IL-9R IL-15R common g chain g–chain shared by IL-2 receptor family a b g a g a b g Cytokine receptors consist of unique ligand-binding chains and one or more signal-transducing chains,which are often shared by receptors for different cytokines

23. Cytokine receptors and signaling Different cytokines binding to cytokine receptors activated distinct signal transduction pathways resulting in gene activation.

24. Cytokines • General Properties • Functional Categories of Cytokines • Cytokine Receptors • Biologic Actions

25. Biologic Actions • Cytokines That Mediate and Regulate Innate Immunity • Cytokines That Mediate and Regulate Adaptive Immunity • Cytokines That Stimulate Hematopoiesis *Cytokines have many functions, we’ll focus on a few central functions of a few key cytokines

26. *Mononuclear phagocytes are the principal source of cytokines of innate immunity Cytokines That Mediate and Regulate Innate Immunity • Tumor necrosis factor (TNF) • IL-1 • IL-6 • chemokines • Type I IFNs • IL-12 • IL-15 • IL-18 Proinflammatory cytokines

27. Active recruitment of the cells to the sites of infectionrecognition of microbes phagocytosis destruction

28. TNF Low quantities (plasma conc.<10-9M) Moderate quantities High quantities (plasma conc.10-7M) Systemic effects Septic shock Local inflammation Leukocyte Fever Low output Activation Thrombus Adhesion molecule IL-1,chemokines Endothelial cell Hypoglycemia

29. *Mononuclear phagocytes are the principal source of cytokines of innate immunity Cytokines That Mediate and Regulate Innate Immunity • Tumor necrosis factor (TNF) • IL-1 • IL-6 • chemokines • IL-12 • Type I IFNs • IL-15 • IL-18

30. directing migration of leukocytes Chemokines Tissue Primary lymphoid organs Secondary lymphoid organs Blood inflammation Cellular sources to inflammatory sites • inflammatory stimuli • Constitutively produced in lymphoid organs Physiologic traffic of lymphocytes through the organs

31. X: any amino acid C: cyctein Chemokine family and structure Family Structure The chemokines are classified into families based on the number and location of N-terminal of cyctein residues CXC、CC、C、CX3C

32. CXCL8/IL-8 CXCL1/GROα CXCL4/PF4 CXCL10/IP-10 Microbesinflammatory cytokines CXC chemokines CC chemokines CCL2/MCP-1 leukocytesendothelial cells epithelial cells fibroblasts CCL3/MIP-1 CCL5/RANTES CCL11/Eotaxin lymphocytes neutrophils basophils lymphocytes eosinophils Endothelial cells Mononuclear phagocytes

33. The chemokine/chemokine-receptor family

34. Chemokines recruit the cells to sites of infection

35. Cytokines and Inflammation • Macrophages or DCs stimulated via microbes make pro-inflammatory cytokines, especially TNF (Tumor necrosis factor), IL-1, and IL-6 • TNF and IL-1 signal to endothelial cells to make them: • Leaky to fluid (influx of plasma; containing antibodies, complement components, etc.) • Sticky for leukocytes, leading to influx of neutrophils first, then monocytes, lymphocytes • Chemokines induce movement of leukocytes and their migration toward chemical gradient of the cytokine

36. directing migration of leukocytes Chemokines Tissue Primary lymphoid organs Secondary lymphoid organs Blood inflammation to inflammatory sites • inflammatory stimuli • Constitutively produced in lymphoid organs Physiologic traffic of lymphocytes through the organs

37. Chemokines regulate the traffic of lymphocytes and other cells through peripheral lymphoid tissues Segregation of B cells and T cells in distinct areas of the lymph node is dependent on cytokines. CXCR5/CCR7

38. *Mononuclear phagocytes are the principal source of cytokines of innate immunity Cytokines That Mediate and Regulate Innate Immunity • Tumor necrosis factor (TNF) • IL-1 • IL-6 • chemokines • Type I IFNs • IL-12 • IL-15 • IL-18

39. Type I IFNs • Major cellular sourcesIFN-: mononuclear phagocytes IFN-: fibroblasts • Potent stimulusviral infection • Functionmediate the early innate immune response to viral infections Inhibits viral replication Increase expression of class I MHC molecules Stimulates the development of Th1 cells in human

40. type I IFN inhibits viral replication Induction of “antiviral state” virus Viral replication Induction of enzymes that block viral replication Potent stimulus nucleus nucleus Virus infected cells IFN-a Nearby uninfected cell

41. *Mononuclear phagocytes are the principal source of cytokines of innate immunity Cytokines That Mediate and Regulate Innate Immunity • Tumor necrosis factor (TNF) • IL-1 • IL-6 • chemokines • Type I IFNs • IL-12 • IL-15 • IL-18

42. Microbes Antigen presentation Activation Macrophage Dendriticcell Naïve CD4+T cell CD40 CD40L IL-12 CD8+ T cell NK cell NK cell TH1 cell IFN- Increased cytolytic activity Macrophage activation;killing of phagocytosed microbes Killing of infected cell

43. 0 1 3 6 Hours after LPS injection Roles of cytokines in innate immunity and inflammation

44. Biologic Actions • Cytokines That Mediate and Regulate Innate Immunity • Cytokines That Mediate and Regulate Adaptive Immunity • Cytokines That Stimulate Hematopoiesis

45. Three elemental R‘s of T-cell biology: repertoire, recognition, response Repertoire of clones Recognition phase Recognition of processed antigens: peptide-MHC Cytokine production is one of the principal response of T cells to antigen recognition Activation phase Effector phase ResponseClonal expansionFunctional differentiationMemoryTolerance to self TH1（IFN-）TH2（IL-4,5, 13）TH17（IL-17）TR1（IL-10）Foxp3+TregCTL

46. Function of T cell derived Cytokines • In the activation phase of T cell-dependant immune response:Regulate the growth and differentiation of various lymphocyte population • In the effector phase of adaptive immune response:Recruit, activate, and regulate specialized effector cells, such as mononuclear phagocytes, neutrophils, and eosinophils, to eliminate antigens

47. Cytokine of adaptive immunity are produced mainly by T lymphocytes in response to specific recognition of protein Ags. • The function of T helper cells is mediated by cytokines

48. Figure 8-20

49. IL-2 • a growth factor for antigen-stimulated T lymphocytes • responsible for T cell clonal expansion after antigen recognition

50. Function of T cell derived Cytokines • In the activation phase of T cell-dependant immune response:Regulate the growth and differentiation of various lymphocyte population • In the effector phase of adaptive immune response:Recruit, activate, and regulate specialized effector cells, such as mononuclear phagocytes, neutrophils, and eosinophils, to eliminate antigens