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Immunopharmacology 免疫药理学

Immunopharmacology 免疫药理学. 2010.12. Types of Drugs. Immunosuppressants ( important! ) Immunostimulants Immunomodulators Induction of tolerance (tolerogens) Cytokines Hematopoetic growth factors Antibodies targeting key cell receptors/ligands. Simplified schematic of an immune response.

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Immunopharmacology 免疫药理学

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  1. Immunopharmacology免疫药理学 2010.12

  2. Types of Drugs • Immunosuppressants (important!) • Immunostimulants • Immunomodulators • Induction of tolerance (tolerogens) • Cytokines • Hematopoetic growth factors • Antibodies targeting key cell receptors/ligands

  3. Simplified schematic of an immune response proliferation & differentiation CD8+ T cells CD8+ cytolytic T cells Class I IFNg, IL-2 APC proliferation & differentiation CD4+ immune cells (delayed hypersensitivity) Class II CD4+ T cells Cytokines Costim. Mol. IL-4,-5,-6 B cells Protein antigens Plasma cells proliferation & differentiation antibody production MHC class II/peptides APCs

  4. Major steps in immune responses CD8 T cell Antigen IL-2 cytotoxic T cells 1 4 3 2 primed CD4 T helper cell IL-2 IL-1 antigen presenting cell (macrophage, dendritic cell) CD4 T helper cell plasma cells 4 IL-2 B cell

  5. Sites of action of immunosuppressive drugs CD8 T cell 4 Antigen IL-2 X cytotoxic T cells 1 E X C A X 3 2 primed CD4 T helper cell X X D D IL-2 IL-1 B antigen presenting cell CD4 T helper cell 4 plasma cells X cytokines

  6. Immune response The cell-mediated arm of the immune response involves the ingestion and digestion of antigen by antigen-presenting cells such as macrophages. Activated TH cells secrete IL-2, which causes proliferation and activation of cytotoxic T lymphocytes, and TH1 and TH2 cell subsets. TH1 cells also produce IFN-γ and TNF-β, which can directly activate macrophages and NK cells. The humoral response is triggered when B lymphocytes bind antigen via their surface immunoglobulin. They are then induced by TH2-derived IL-4 and IL-5 to proliferate and differentiate into memory cells and antibody-secreting plasma cells. Regulatory cytokines such as IFN- γ and IL-10 down-regulate TH2 and TH1 responses, respectively.

  7. Purpose of immunosuppressive drugs • Prevention of organ transplant rejection • Treatment of autoimmune diseases • Multiple Sclerosis（多发性硬化） • Lupus （红斑狼疮） • Rheumatoid Arthritis （类风湿性关节炎） • Crohn’s Disease（节段性回肠炎） • Type I Diabetes （1型糖尿病） • …

  8. Glucocorticoids • reducing the size and lymphoid content of the lymph nodes and spleen • interfering with the cell cycle of activated lymphoid cells • lowering the effective concentration of specific antibodies

  9. Biology of glucocorticoids Newton, Thorax 2000; 55:603-613

  10. Mechanisms of Glucocorticoid Action • Inhibit the production of • proinflammatory cytokines • Promote the production of inflammatory cytokines • Induce apoptosis in • inflammatory cells • 4. Interfere with cytokine signals Newton, Thorax 2000;55:603-613

  11. Glucocorticoid-sensitive sites of the immune response proliferation & differentiation X MHC Class I/peptides APCs CD8 T-cell CD8 cytolytic T-cells X GC GC IL-2 MHC Class II/peptides APCs proliferation X CD4 immune cell (delayed hypersensitivity) CD4 T-cell (helper T-cells) X IL-1 IL-1, -4,-5,-6 B-cell Protein antigen Plasma cell proliferation & differentiation antibody production

  12. Clinical uses • Autoimmune diseases Idiopathic thrombocytopenic purpura (特发性血小板减少性紫癜) • Autoimmune hemolytic anemia （自主免疫溶血性贫血） • Acute glomerulonephritis（肾小球肾炎） • Acquired factor XIII antibodies and bleeding syndrome • Organ transplantation  • Prevention of cell proliferation induced by coronary stents （支架） • …

  13. Cyclosporin （环孢素） isolated from the fungus Tolypocladium inflatum (多孢木霉菌) isolated from a soil sample obtained by Sandoz scientists at Hardangervidda, Norway in 1969

  14. Immunophilin（免疫亲和素） ligands • Cyclosporine（环孢素）：peptide antibiotic • Cyclosporine ＋ cyclophilin → complex → inhibiting cytoplasmic phosphatase, calcineurin（钙调磷酸酶，necessary for the activation of a T-cell-specific transcription factor）

  15. Targets of Immunosuppressants cyclophilin FK Binding protein sirolimus Cyclosporine tacrolimus mTor Calcineurin NFAT Translocation Cytokine Signaling Genes lead to T cell Activation； IL-2转录↓

  16. Mechanism of Action of Helper T-cell blockers X X From Hardman and Limbird, The Pharmacological Basis of Therapeutics

  17. Clinical uses • organ transplantation: • Body parts: Facial, Limbs, • Organs: Heart, kidney, liver, small intestine, lung, … • Tissues: Islets, hair follicles, bone, bone marrow, cornea, … • Cells: Stem cells, lymphocytes

  18. Immunological Rejection Major Histocompatibility Complex (基因群) MHC编码细胞表面组织相容性抗原，无器官特异性，不同个体间抗原特异性不同，但同卵双生及纯系动物不同个体之间，其抗原特异性完全一致。 Rejections: Antibody mediated T cells mediated Hyperacute rejection e.g., Blood type mismatch Acute Graft Rejection Direct recognition of allogeinic MHC; rejection about 10 days Chronic rejection Take many months to years. Due to failure of immunosuppressants

  19. Clinical uses • graft-versus-host disease（移植物抗宿主疾病） after hematopoietic stem cell transplantation • selected autoimmune disorders

  20. Tacrolimus（他克莫司） • macrolide antibiotic 23-membered macrolide lactone discovered in 1984 from the fermentation broth of a Japanese soil sample that contained the bacteria Streptomyces tsukubaensis.

  21. Tacrolimus • binding to the immunophilin FK-binding protein→inhibiting the cytoplasmic phosphatase, calcineurin • 10-100 times more potent than cyclosporine • used in organ and stem cell transplantation

  22. Sirolimus （西罗莫司） • Structure • macrolide similiar to tacrolimus • Mechanism • binds to immunophilin protein that binds to a key regulatory kinase required for T cell activation • (new unique mechanism to inhibit T lymphocyte activation by IL-2) • different site of action than cyclosporine and tacrolimus

  23. Targets of Immunosuppressants immunophilin FK Binding protein sirolimus Cyclosporine tacrolimus mTOR Calcineurin NFAT Translocation Cytokine Signaling Genes lead to T cell Activation； IL-2转录↓

  24. Consequences of mTOR action • Lymphocyte cell proliferation & differentiation • T cells • B cells • Antibody production • Mesenchymal cell proliferation • Vascular smooth muscle cells • Endothelial cells • Fibroblasts

  25. Sirolimus • Inhibits mammalian target of rapamycin (mTOR) • mTOR is a protein kinase that plays pivotal role in IL-2 receptor responses • IL-2 binds to its receptor on T cells and leads to mTOR activation • mTOR initiates cascade of events (including cyclin dependent kinases) that promote T lymphocyte proliferation and differentiation • Inhibition of mTOR blocks IL-2 dependent cell-cycle progression at G1→S phase transition

  26. Mycophenolate mofetil（霉酚酸酯） • Penicillium glaucum（灰绿青霉菌） • inhibiting T- and B-lymphocyte responses Very often used now • alternative to cyclosporine, solid organ transplant patients • lupus nephritis, rheumatoid arthritis, and some dermatologic disorders

  27. Cytotoxic agents • Azathioprine（硫唑嘌呤） • prodrug of mercaptopurine，functions as an antimetabolite

  28. Cytotoxic agents • Cyclophosphamide（环磷酰胺） • autoimmune disorders (including systemic lupus erythematosus系统性红斑狼疮) • acquired factor XIII antibodies and bleeding syndrome • autoimmune hemolytic anemia • antibody-induced pure red cell aplasia（发育不全） • Wegener‘s granulomatosis（肉芽肿）

  29. Drug Glucortiocoids Cyclosporine and Tacrolimus Sirolimus Mycophenolate Mofetil Target GRE of DNA (regulate gene transcription, inhibit transcription) Calcineurin (inhibit the phosphatase required for IL-2 transcription) Protein kinase involved in cell-cycle progression (inhibits mTOR and inhbits IL-2 signaling) Inosine monophosphate dehydrogenase (inhibits de novo guanine nucleotide synthesis) Immunosuppressants Inhibiting T Cell Activation

  30. Monoclonal antibody • 1975, hybridoma technology by Milstein and Kohler • antibody-forming cells fused to immortal plasmacytoma cells[举例：脾细胞分泌抗体＋骨髓瘤细胞(永生性)] • Pure and mass antibody possible • Antilymphocyte & Antithymocyte Antibodies • Muromonab-CD3 against T-cell surface proteins（莫罗单抗） • …

  31. Inhibitors of immune response A- Immune Globulin(antigen recognition) B- Corticosteroids(IL-1 production, cell proliferation) C- Cyclosporine, Tacrolimus, (1L-2 gene expr.), Sirolimus (IL-2 signal transduction) D- Rapamycin, Mycophenolate(T cell prolif.), Azathioprine, Cyclophosphamide (all cell prolif.) E- OKT3 (Muromonab-CD3) (monoclonal antibody to CD3 on T cell)

  32. Immunostimulants • Thymic Hormones • Improve primary immune deficiency in children • Synthetic Stimulants • Levamisole stimulates phagocytosis and T cell production of cytokines • Adjuvants of bacterial origin • Bacille de Calmette Guerin (BCG, 卡介菌) is viable strain of Mycobacterium bovis that enhances macrophage activity • BCG used for bladder cancer and melanomas

  33. hepatitis B vaccine • a small glycoprotein, hepatitis B surface antigen (HBsAg) • child's immune system recognizes HBsAg as foreign • produces antibodies • when infected with hepatitis B virus • the antibodies recognize the protein and stimulate the immune system to produce large quantities of specific antibodies that attach to and destroy the virus and prevent the disease.

  34. vaccination • a child receives vaccination, most often before leaving the hospital after birth. • the second and third HBV immunizations are administered by the age of 18 months, in conjunction with other routine childhood vaccinations.

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