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Cytokines and their receptors

Explore the role of cytokines in immune responses and disease pathogenesis. Learn about categories, functions, and receptors of cytokines. Discover how various cytokines can be applied in disease treatment.

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Cytokines and their receptors

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  1. Cytokines and their receptors Zhijian Cai (蔡志坚) 浙江省杭州市浙江大学紫金港校区 医学院科研楼B805 医学院免疫学研究所

  2. Introduction to cytokines • Categories of CKs • Biological function of CKs • Cytokine receptor

  3. Introduction to cytokines • Cytokine (CK) Cytokines are small soluble proteins that mediate immune and inflammatory reactions and are responsible for communications between leukocytes and other cells.

  4. The research of CK can help us to clarify the mechanism of immune responses at the molecular level and to understand the pathogenesis of some diseases. • Many CKs and their antagonists can be used in the treatment of many diseases (such as cancer, infection, autoimmune diseases) and to promote hemopoiesis, etc.

  5. According to their source 1) Monokine 2) Lymphokine • According to their function 1) Colony stimulating factor 2) Interleukin 3) Interferon 4) Tumor necrosis factor 5) Growth factor 6) Chemokine

  6. General properties of CKs • Small proteins (MW: approx. 8-30 KD) • Extremely potent, acting at 10-9~10-15M • The production is transient and tightly regulated • Autocrine, paracrine or endocrine • Cytokine actions: Pleiotropy, Redundancy, Synergy and Antagonism

  7. Manner of action 1) Autocrine: IL-2 Th Th 2) Paracrine : IL-12 DC Th 3) Endocrine: IL-1, TNF- Under certain circumstances (e.g. septic shock), large amounts of CKs (such as TNF-) are produced, they may be active distant from their site of secretion.

  8. Cytokine actions 1) Pleiotropy Acts on more than one cell type (IL-4) 2) Redundancy More than one cytokine have the same action (IL-2, IL-7,IL-15) 3) Synergy Two or more cytokines cooperate to produce an effect that is different or greater than the combined effect of the two cytokines when functioning separately (IL-4 and IL-5) 4) Antagonism Two or more cytokines work against each other (IL-4 and IFN-)

  9. Categories of CKs • CKs are classified into 6 functional categories • Interleukin (IL) • Interferon (IFN) • Tumor necrosis factor (TNF) • Colony stimulating factor (CSF) • Chemokine • Growth factor (GF)

  10. Interleukin, IL • Cytokines produced by leukocytes and act on leukocytes • IL-1~35 IL-2, IL-7, IL-9, IL-15 constitute common  chain family IL-4, IL-5, IL-6, IL-13 (Th2 type) IL-8 (belongs to chemokine family) IL-10 (Tr type) IL-11 (stimulator of platelets) IL-12 (DC, macrophages, directs Th1)

  11. Interferon, IFN • IFNs are mediators of the innate immune response and Th1/CTL responses. • Groups Type I IFN: IFN- and IFN- The major source is leukocytes (PDC), fibroblasts Help prevent the spread of virus to uninfected cells. Type II IFN: IFN- IFN- is produced by activated T cells and NK cells. Its main function is immune regulation.

  12. Tumor necrosis factor, TNF • TNF was originally identified (and was so named) as a substance that can cause the necrosis of tumors in vivo. • TNF- and TNF- TNF- is produced by LPS-stimulated mononuclear phagocytes and activated T cells. Involved in inflammation. TNF- is also termed lymphotoxin (LT), and is produced mainly by activated T cells.

  13. Colony-stimulating factors, CSF • Stimulates the differentiation and expansion of bone marrow progenitor cells. • It is assayed by its ability to stimulate the formation of cell colonies in culture. • Includes IL-3, CSF (G-CSF, M-CSF, GM-CSF), SCF, EPO, TPO, etc .

  14. Chemokines (chemotactic cytokines) • Chemokines are a large family of structurally homologous CKs that stimulate movement and regulate the migration of leukocytes from the blood to tissues and within tissues. • About 50 different members. • Subfamilies: CXC, CC , C , CX3C , based on structural characteristics (cysteine residues).

  15. Chemokines Subfamily Target Cells • IL-8 CXC neutrophils • MCP-1 CC monocyte • Lymphotactin C lymphocyte • Fractalkine CX3C lymphocyte

  16. Growth factors, GF • Promote the proliferation and differentiation of cells. • Include TGF-, EGF, VEGF, FGF, NGF, PDGF, etc.

  17. Biologic functions of CKs (1) • Anti-bacteria: IL-1, TNF, IL-6, IL-8 and IL-12 • Anti-virus: type I,II IFN • Mediation and regulation of adaptive immunity: *Stimulating the proliferation of lymphocytes: IL-2, IL-7, IL-15. *Stimulating the development of lymphocytes: IL-12, IFN-, IL-4. *Enhancing the activity of effector cells: IFN-, IL-2,IL-6. *Inhibiting immune response: TGF-, IL-10

  18. Cytokine secretion and biological activities of Th1 and Th2 subsets Type 1 Type 2 Cell-mediated Immune response (intracellular organisms) Humoral response (parasites, extracellularmicrobes) T cell IL-2 IFN-γ TNF IL-4 IL-5 IL-10

  19. The functions of Th1 and Th2 cells.

  20. Functions Of Cytokines

  21. Biologic actions of CKs (2) • Stimulation of hemopoiesis SCF → stem cells CSF → granulocytes and monocytes IL-4 and GM-CSF → dendritic cells EPO → erythrocytes IL-11 and TPO →platelets IL-7, IL-15 → formation of Tm • Apoptosis, killing target cell TNF-α,FasL • Angiogenesis IL-8, VEGF, etc.

  22. Cytokine receptors 1.Five families • Immunoglobulin superfamily • Class I cytokine receptor family • Class II cytokine receptor family • TNF receptor family • Chemokine receptor family

  23. Note: The receptor contains a distinct set of 4 spaced cysteines in their extracellular domains and a conserved sequence motif (WSXWS) located near the external membrane surface.

  24. 2.Multi-subunit receptor and common receptor subunit • Multi-subunit receptor one for cytokine binding another for cytokine signaling • Common receptor subunit There is same receptor subunit for cytokine signaling among the different cytokine receptors. e.g. IL-2R

  25. IL-4, 7,9,15 IL-11, LIF IL-5, GM-CSF

  26. Features of Cytokines Whose Receptors Share γc

  27. In 1993, it was reported that the γ chain was defective in patients with X-linked severe combined immunodeficiency (XSCID; the disease is formally designated as SCIDX1) • Absent or profoundly diminished numbers of T cells and mitogen responses. • 2. Absence of NK cells • 3. Normal numbers of B cells, but defective B-cell responses. • 4. IgM can be normal, but greatly diminished immunoglobulins of other classes. SCID Patient with severe Candida in mouth.

  28. Contains 3-6 cysteine-rich domains. Each domain is made up of approximate 40 amino acid residues.

  29. GTP-binding protein coupled receptor superfamilyor seven predicated transmembrane domain receptor superfamily.

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