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اعداد الصيدالني علي محسن هاشم IMMUNOPHARMACOLOGY Major Steps in Immune Responses _ _ _ _ 1- Antigen recognition 2- IL-1 production 3- IL-2 and other cytokine expression 4- lymphocyte proliferation & differentiation MAJOR STEPS IN IMMUNE RESPONSES Antigen IL-2 CD8 T cell 1 cytotoxic T cells 4 2 3 IL-1 IL-2 antigen presenting cell (macrophage, dendritic cell) CD4 T helper cell primed CD4 T helper cell 4 IL-2 B cell plasma cells SITES OF ACTION OF IMMUNOSUPPRESSIVE DRUGS Antigen 1 X A IL-2 CD8 T cell4 X E C X 2 B IL-1 antigen presenting cell X D X 3 IL-2 CD4 T helper cell D primed CD4 T helper cell 4 X cytokines cytotoxic T cells plasma cells Inhibitors of Immune Response (site of action) _ _ _ _ _ A- Immune Globulin (antigen recognition) B- Corticosteroids (IL-1 production, cell proliferation) C- OKT3 ,ATG (T cell receptors/surface prot.) D- Cyclosporine, Tacrolimus, (1L-2 gene expr.), Sirolimus (IL-2 signal transduction) E- Rapamycin, Mycophenolate (T cell prolif.), Azathioprine,Cyclophosphamide (all cell prolif.) Major Classes of Immunosuppressant Drugs _ _ _ Glucocorticoids Calcineurin inhibitors Cytotoxic agents: include azathioprine , cyclophosphamide ,leflunomide ,hydroxychloroquine, other cytotoxic agents vincristine, MTX,cytarabine _ Biologics (Antibodies) Clinical uses of immunosuppressive agents -Autoimmune disease: Idiopathic thrombocytopenic purpura (ITP):Prednisone, vincristine, occasionally cyclophosphamide, mercaptopurine, or azathioprine; commonly high-dose gamma globulin Autoimmune hemolytic anemia : Prednisone, cyclophosphamide, chlorambucil, mercaptopurine, azathioprine, high-dose gamma globulin . Acute glomerulonephritis: Prednisone,mercaptopurine , cyclophosphamide . Acquired factor XIII antibodies :Cyclophosphamide plus factor XIII Autoreactive tissue disorders (autoimmune diseases including systemic lupus erythematosus, rheumatoid arthritis, scleroderma, dermatomyositis, mixed tissue disorder, multiple sclerosis, Wegener's granulomatosis, chronic active hepatitis, lipoid nephrosis, inflammatory bowel disease.): Prednisone, cyclophosphamide, methotrexate, interferon-α and -β, azathioprine, cyclosporine, infliximab, etanercept, adalimumab . -Isoimmune disease(Hemolytic disease of the newborn):Rho(D) immune globulin . -Organ transplantation Renal & heart : Cyclosporine, azathioprine, prednisone, ALG, OKT3, tacrolimus, basiliximab, daclizumab, sirolimus . Liver :Cyclosporine, prednisone, azathioprine, tacrolimus, sirolimus bone marrow:Cyclosporine, cyclophosphamide, prednisone, methotrexate, ALG . -Prevention of cell proliferation (Coronary stents) : sirolimus . Cyclosporine (Neoral, Gengraf) _ Structure _ _ lipophilic cyclic peptide Mechanism _ _ inhibits transcription of IL-2 gene plus other lymphokine genes (IL-3, gamma interferon) site of action is a binding protein that inhibits calcineurin (a phosphatase) which is necessary for the activation of a T-cell-specific transcription factor Cyclosporine (Neoral) _ Pharmacokinetics _ _ _ _ variable, incomplete oral absorption extensive hepatic metabolism, excreted in bile used alone or in combination with prednisone and azathioprine (or other antineoplastic drugs) Adverse Effects _ _ nephrotoxicity, hepatotoxicity, hirsutism,HTN , hyperglycemia, hyperK,convulsion,gum hypertrophy. Drug interactions due to induction and inhibition of hepatic cytochrome P450 _ Cyclosporine may be used alone or in combination with other immunosuppressants, particularly glucocorticoids. _ Used successfully as the sole immunosuppressant for cadaveric transplants of the kidney, pancreas, and liver, and cardiac transplants as well. _ In combination with methotrexate, cyclosporine is a standard prophylactic regimen to prevent graft– versus-host disease . _ Cyclosporine has also proved useful in a variety of autoimmune disorders, including uveitis, rheumatoid arthritis, psoriasis, and asthma. Tacrolimus (FK506) _ Structure _ _ macrolide (structure like erythromycin) Mechanism _ similiar to cyclosporine except binds to different protein that inhibits calcineurin (a phosphatase enzyme involved in gene transcription of IL-2, gamma interferon and other cytokines) Tacrolimus(FK506) _ Bioavailability _ _ _ given by IV infusion or orally used concomitantly with corticosteroids Adverse Effects _ nephrotoxicity, increased risk of lymphomas, hypersensitivity, hyperglycemia, GI complaints, hypertension, neurotoxicity (tremor, headache, motor disturbances, seizures) Sirolimus (Rapamune) _ 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 Sirolimus (Rapamune) _ 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 Consequences of TOR Action _ Lymphocyte cell proliferation & differentiation _ _ _ _ T cells B cells Antibody production Mesenchymal cell proliferation _ _ _ Vascular smooth muscle cells Endothelial cells Fibroblasts Properties of TOR Inhibitors such as Sirolimus (Rapamune) _ _ _ _ Selective blockade of cytokine signal transduction Inhibition of T cell division and proliferation Potent and effective immunosuppression Potential for synergy with other immunosuppressants Sirolimus (Rapamune) _ other theoretical actions include _ _ _ _ _ blockade of B cell Ig synthesis inhibition of antibody-dependent cellular toxicity inhibition of lymphocyte activated killer cells inhibition of natural killer cells inhibition of immune and nonimmune cell proliferation (via inhibition of growth factor signaling) (may explain antitumor actions) Sirolimus (Rapamune) _ Bioavailability _ _ _ _ low oral absorption hepatic metabolism by CYP4503A4 (drug interactions may occur) long half-life (60 hours) Adverse Effects _ _ thrombocytopenia, hyperlipidemia, rash lacks direct end organ toxicity but increased incidence impaired renal function when combined with cyclosporine Mycophenolate Mofetil (CellCept) _ Structure _ _ derivative of mycophenolic acid Mechanism _ _ _ inhibits inosine monophosphate dehydrogenase involved in de novo synthesis of purines selectively suppressess T- and B-cell proliferation Also suppresses some macrophage functions (may explain anti-inflammatory actions) Mycophenolate Mofetil _ Pharmacokinetics _ _ oral absorption and hepatic metabolism Adverse Effects _ _ diarrhea, leukopenia and CMV infections increased incidence of lymphomas and other malignancies _ _ _ _ Thalidomide inhibits TNFα,reduces phagocytosis by neutrophils,↑production of IL10,alters adhesion mol. expression &enhances cell mediated immunity via interaction with T cell Indications for leprosy and multiple myeloma Side effects: teratogenicity, neuropathy, fatigue, constipation, deep vein thrombosis Thalidomide analogs have been obtained based on its antiangiogenic and immunomodulatory properties.(Immunomodulatory derivatives of thalidomide are termed IMiDs.) _ Lenalidomide (Revlimid) - as the first commercially derivative.It is only available in a restricted distribution to avoid its use during preg. _ CC-4047 (Actimid) is another IMiD that is being investigated for the treatment of myelodysplastic syndrome, myeloma, and prostate cancer. _ Another group of thalidomide analogs, selective cytokine inhibitory drugs (SelCIDs), are phosphodiesterase type 4 inhibitors with potent anti-TNF- activity but no T-cell co-stimulatory activity. Several SelCIDs are currently under investigation for clinical use. Corticosteroid _ _ _ _ _ _ _ _ _ Prednisone used most often orally Methylprednisolone used parenterally Numerous available preparations Corticosteroid action Inhibition of IL-1 and TNF gene expression and synthesis Decreased activation of T lymphocytes by decreasing IL-1 release Decreased neutrophil functions esp chemotaxis Decreased antibody production (high doses) Decreased release of kinins and proinflammatory eicosanoids (prostaglandins and leukotrienes) Corticosteroid Immunosuppression _ Decreased cell-mediated immune reactions that mediate rejection of organ transplants _ Mechanisms: _ decreased activation of T lymphocytes by inhibition of IL-1 synthesis by macrophages _ decreased lymphocyte mobilization out of lymphoid organs (lymphopenia) New Immunosuppressants _ Mizoribine (investigational) _ _ Brequinar (investigational) _ _ Inhibitor of de novo pyrimidine synthesis 15-Deoxyspergualin (investigational) _ _ Inhibitor of purine nucleotide synthesis Antimonocytic that decreases MHC antigen expression Pimecrolimus (Elidel) _ _ Calcineurin inhibitor like cyclosporine Approved for topical treatment of eczema New Class of Immunosuppressant _ _ _ _ _ _ FTY720 (prodrug: requires phosphorylation) Sphingosine 1-phosphate receptor (S1P-R) agonist Reduces recirculation of lymphocytes from lymphatic system to the blood Lymphocyte homing action which reversibly sequesters host lymphocytes into lymph nodes Useful in combination therapy but not alone Toxicity: lymphopenia, decreased heart rate _ Biologics(antibodies):- _ Antilymphocyte & Antithymocyte Antibodies _ Immune Globulin Intravenous (IGIV) _ RhO(D) Immune Globulin Micro-Dose _ Hyperimmune Immunoglobulins _ Monoclonal Antibodies (MABS) Antibodies Used for Acute Rejection of Organ Transplants -Antilymphocyte & Antithymocyte Antibodies _ Antisera directed against lymphocytes. ALG and antithymocyte globulin (ATG) are now in clinical use in many medical centers, especially in transplantation programs. The antiserum is usually obtained by immunization of large animals such as horses or sheep with human lymphoid cells. ALG and ATG are useful for suppressing certain major compartments (ie, T cells) of the immune system and play a definite role in the management of solid organ and bone marrow transplantation -OKT3 (Muromonab-CD3) _ _ _ _ Murine monoclonal antibody to CD3 on T cell & thymocytes inhibits cytotoxic T killer cell function opsonizes circulating T lymphocytes and enhances their removal used to prevent or reverse acute graft rejection Antithymocyte Globulin-Rabbit (Thymoglobulin) _ _ _ Rabbit gamma immune globulin preparation Composed of antibodies to variety of T cell markers Mechanisms _ _ _ removal of T cells from circulation modulation of T cell activation, homing and cytotoxicity decreases cytokine induced reactions Adverse Effects of Antibody Preps _ Hypersensitivity reactions may occur with nonhuman antibodies resulting in chills, fever, thrombocytopenia, erythema, pruritis _ Problem with murine MAB OKT3 is formation of anti-OKT3 antibodies limit its action so only given by IV infusion for 7-14 days . Immune Globulin Intravenous (IGIV) This immunoglobulin preparation (usually IgG) is prepared from pools of thousands of healthy donors, and no specific antigen is the target of the "therapeutic antibody“& have a normalizing effect upon the patient's immune networks IGIV in high doses (2 g/kg) has proved effective in a variety of different conditions ranging from immunoglobulin deficiencies to autoimmune disorders to HIV disease to bone marrow transplants It is used in Kawasaki's disease, reducing systemic inflammation and preventing coronary artery aneurysms. it also used in SLE & refractory ITP Possible mechanisms of action of IGIV include a reduction of T helper cells, increase of suppressor T cells, decreased spontaneous immunoglobulin production, Fc receptor blockade, increased antibody catabolism, and idiotypic-anti-idiotypic interactions with "pathologic antibodies." Rho(D) Immune Globulin _ used to suppress immune response of Rh(neg.) mother after delivery of Rh (pos.) baby _ Given within 24-72 hours after birth of Rh(pos.) baby,the mother's own antibody response to the foreign Rho(D)positive cells is suppressed because the infant's red cells are cleared from circulation before the mother can generate a B-cell response against Rho(D),to prevent hemolytic anemia of the newborn that may occur in subsequent preg. The usual dose of Rho(D) immune globulin is 2 mL intramuscularly, containing approximately 300 mcg anti-Rho(D) IgG. Adverse reactions are infrequent,local discomfort at the injection site or, rarely, a slight temperature elevation. _ _ _ Rho(D) immune globulin is a concentrated (15%) solution of human IgG containing a higher titer of antibodies against the Rho(D) antigen of the red cell. Hyperimmune Immunoglobulins _ _ _ Hyperimmune immunoglobulin preparations are IGIV preparations made from pools of selected human or animal donors with high titers of antibodies against particular agents of interest such as viruses or toxins. Various hyperimmune IGIVs are available for treatment of respiratory syncytial virus, cytomegalovirus, varicella zoster, human herpesvirus 3, hepatitis B virus, rabies, tetanus, and digoxin overdose. Intravenous administration of the hyperimmune globulins is a passive transfer of high titer antibodies that either reduces risk or reduces the severity of infection MONOCLONAL ANTIBODYS NOMENCLATURE Murine Chimeric Rituximab Muromonab Daclizumab Humanized Monoclonal Antibody MONOCLONAL ANTIBODY STRUTURE Mouse Chimeric Human Humanized Advantages of Chimeric and Humanized Antibodies _ _ Reduce immunogenicity without sacrificing affinity Allow complement fixation to occur by using the human Fc region instead of murine Fc _ _ _ Resulting in ADCC and activation of phagocytic cells Humanization of Fab fragment may decrease binding affinity compared to initial murine antibody Baciliximab has higher affinity for IL-2 receptor than Daclizumab Antitumor MABs 1.Alemtuzumab humanized MAB binds to CD52 found on normal and malignant B and T lymphocytes, NK cells, monocytes, macrophages, and granuloctes Alemtuzumab is approved for the treatment of B-cell chronic lymphocytic leukemia in patients who have been treated with alkylating agents and have failed fludarabine therapy,it deplete leukemic and normal cells by direct antibody-dependent lysis S.E:lymphopenia and neutropenia, anemia, and thrombocytopenia 2. Bevacizumab binds to vascular endothelial growth factor (VEGF) and inhibits VEGF from binding to its receptor, especially on endothelial cells. It is an antiangiogenic drug inhibit growth of blood vessels (angiogenesis) in tumors. It is approved for first-line treatment of patients with metastatic colorectal cancer alone or in combination with 5-FU-based chemotherapy. S.E: hemorrhage, GI perforations, and wound healing problems 3.Cetuximab chimeric MAB binds to epidermal growth factor receptor (EGFR) & inhibits tumor cell growth by a variety of mechanisms, including decreases in kinase activity, matrix metalloproteinase activity, and growth factor production, and increased apoptosis. It is indicated for use in patients with metastatic colorectal cancer whose tumors overexpress EGFR. 4. Gemtuzumab is a humanized MAB specific for CD33 found on leukemic blast cells in 80–90% of patients with acute myelogenous leukemia (AML).In the clinical formulation, gemtuzumab is coupled to the cytotoxic agent, ozogamicin, which is an antibiotic with antitumor activity.Gemtuzumab is approved for the treatment of patients 60 years and older in first relapse with CD33 acute myelogenous leukemia who are not considered candidates for other types of cytotoxic chemotherapy S.E: severe myelosuppression,especially neutropenia,others hepatotoxicity and various hypersensitivity reactions. 5.Rituximab binds to CD20 molecule on normal and malignant B lymphocytes and is approved for the therapy of patients with relapsed or refractory low-grade or follicular, B-cell nonHodgkin's lymphoma. The mechanism of action includes complement-mediated lysis, antibody-dependent cellular cytotoxicity, and induction of apoptosis in the malignant lymphoma cells. _ _ _ _ _ Adverse reactions: Serious adverse events include cardiac arrest, tumor lysis syndrome Infections:Hepatitis B reactivation,Other viral infections Progressive multifocal leukoencephalopathy (PML) Other anti CD20 monoclonal antibodies being developed: Ocrelizumab, humanized B-cell depleting agent. Ofatuzumab a fully-human B-cell depleting agent. 6.Trastuzumab humanized MAB binds to the extracellular domain of the human epidermal growth factor receptor HER-2/neu. This antibody blocks the natural ligand from binding and down-regulates the receptor. Trastuzumab is approved for the treatment of metastatic breast cancer in patients whose tumors overexpress HER-2/neu. As a single agent it induces remission in about 15–20% of patients; in combination with chemotherapy, it increases response rate and duration as well as 1-year survival. MABs Used to Deliver Isotopes to Tumors 1.Arcitumomab is a murine F(ab')2 fragment from an anti-carcinoembryonic antigen (CEA) antibody labeled with technetium 99m (99mTc) that is used for imaging patients with metastatic colorectal carcinoma (immunoscintigraphy) to determine extent of disease. CEA is often upregulated on tumor in patients with gastrointestinal carcinomas. 2. Capromab pendetide is a murine monoclonal antibody specific for prostate specific membrane antigen. It is coupled to isotopic indium (111In) and is used in immunoscintigraphy for patients with biopsyconfirmed prostate cancer and post-prostatectomy in patients with rising prostate specific antibody level to determine extent of disease. . 3.Ibritumomab tiuxetan is an anti-CD20 murine MAB labeled with isotopic yttrium (90Y) or 111In. The radiation of the isotope provides the major antitumor activity. Ibritumomab is approved for use in patients with relapsed or refractory low-grade, follicular, or Bcell non-Hodgkin's lymphoma, including patients with rituximab-refractory follicular disease. 4.Nofetumomab is a mouse MAB coupled to 99mTc that is used for diagnostic purposes to determine extent of disease and to stage patients with small cell lung cancer. It binds a 40 kD antigen found on many tumor cell types, but also on some normal cells. 5. Tositumomab is another anti-CD20 MAB and is complexed with iodine 131 (131I).It is used in two-step therapy in patients with CD20-positive, follicular nonHodgkin's lymphoma whose disease is refractory to rituximab and standard chemotherapy. Toxicities are severe thrombocytopenia and neutropenia. MABs Used as Immunosuppressants and AntiInflammatory Agents #ANTI-TNF- α MABS block TNF-α(a proinflammatory cytokine) from binding to TNF receptors on inflammatory cell surfaces results in suppression of downstream inflammatory cytokines such as IL-1 and IL-6 and adhesion molecules involved in leukocyte activation and migration.They are includes _ Adalimumab is a completely human MAB approved for use in RA ,administered as single doses subcutaneously, every other week. _ Etanercept is a dimeric fusion protein,it is approved for adult RA, polyarticular-course juvenile RA, and psoriatic arthritis. It may be used in combination with methotrexate.Administered subcutaneously, twice weekly _ Infliximab is a chimeric MAB ,it is approved for use in Crohn's disease, ulcerative colitis,RA, ankylosing spondylitis, and psoriatic arthritis.It is given by i.v infusion every 8 weeks. #Abatacept is a fusion protein composed of the extracellular domain of CTLA-4 fused to human IgG Fc. CTLA-4 is a costimulatory molecule found on T cells that binds to CD80 and CD86 on APC.It blocks activation of T cells by binding to CD80 or 86 so that CD28 on T cells cannot bind and stimulate the T cell and lead to cytokine release. Abatacept is approved for patients with severe RA who have failed other DMARDS #Alefacept is an engineered protein consisting of the CD2-binding portion of LFA-3 fused to a human IgG1 Fc approved for the treatment of plaque psoriasis. It inhibits activation of T cells by binding to cell surface CD2, inhibiting the normal CD2/LFA-3 interaction. Treatment of patients with alefacept also results in a dosedependent reduction of the total number of circulating T cells and the drug discontinued if CD4 lymphocyte levels fall below 250 cells/μ L. #Anakinra is a recombinant IL-1 receptor antagonist it is approved for use in adult rheumatoid arthritis patients who have failed treatment with one or more DMARDS. #Basiliximab is a chimeric MAB that binds to CD25, the IL-2 receptor alpha chain on activated lymphocytes. It functions as an IL-2 antagonist,and is therefore immunosuppressive. It is indicated for prophylaxis of acute organ rejection in renal transplant patients #Daclizumab is a humanized MAB similar basiliximab, but the mode of administration differs. #Efalizumab is humanized anti-CD11a MAB approved for the treatment of adult patients with severe psoriasis. Binding of efalizumab to CD11a (the alpha subunit of LFA-1) inhibits the interaction of LFA-1 on all lymphocytes with ICAM-1, thereby inhibiting the adhesion, activation, and migration of lymphocytes into skin.It is administered by S.C. injection. #Omalizumab is an anti-IgE humanized MAB that is approved for the treatment of allergic asthma in adult and adolescent patients refractory to inhaled steroids.It blocks the binding of IgE to the high-affinity Fcέ receptor on basophils and mast cells, which suppresses IgE-mediated release of type I allergy mediators such as histamine and leukotrienes. Other MABs Abciximab is a Fab fragment of MAB that binds to the GPIIb/IIIa receptor on activated platelets and inhibits fibrinogen, von Willebrand factor, and other adhesion molecules from binding to activated platelets, thus preventing their aggregation. Palivizumabis a MAB that binds to the fusion protein of respiratory syncytial virus, preventing infection in susceptible cells in the airways. It is used in neonates at risk for this viral infection. Immunostimulatory Cytokines _ Interleukins IL-2 (enhance antitumor actions of cytotoxic T cells and NK cells) _ _ Colony Stimulating Factors G-CSF (Filgrastim)(Neupogen®) treat neutropenia _ GM-CSF (Sargramostim)(Leukine®) myeloid recovery after bone marrow transplant _ Interferon Alpha (Roferon®, Intron®) (prod. by leukocytes) (antiviral, antiproliferative) malignant melanoma, renal cell carcinoma, hairy cell leukemia, Kaposi’s sarcoma _ Interferon Beta (Avonex®, Rebif®) (prod. by fibroblasts) (antiviral, antiproliferative) relapsing type MS _ Interferon Gamma (Actimmunex®)(prod. by lymphocytes) (stimulates NK cells and macrophages) chronic granulomatous disease Other Hematopoetic Growth Factors _ Erythropoietin alpha (Epoetin alpha) (Procrit®) _ _ _ _ _ Produced by recombinant DNA technology Stimulates division and differention of erythroid progenitor cells Used for anemia due to renal failure or cancer chemotherapy Adverse effects include hypertension, headache, hypersensitivity reactions are rare Darbopoetin alpha (Aranesp®) _ Recombinant long-acting erythropoetin (3X epoetin) Other Immunostimulants _ Thymic Hormones _ _ Synthetic Stimulants _ _ Improve primary immune deficiency in children Levamisole stimulates phagocytosis and T cell production of cytokines Adjuvants of bacterial origin _ _ BCG is viable strain of Mycobacterium bovis that enhances macrophage activity BCG used for bladder cancer and melanomas References - Basic and Clinical Pharmacology. Bertram Katzung. 10th ed. -Clinical Immunology: Principles and Practice. Robert Rich et al. Second Edition. -Rheumatology Secrets. Sterling West. Second Edition. -Immunobiology. Charles Janeway. 5th edition -Review of Immunology. Andrew Lichtman. 2005 -Genomic and non genomic effects of glucocorticoids. Stah and Buttgereit. Nature Clinical Practice. 2008 Vol4 no10; 525-533 -Therapeutic vaccination for chronic diseases: a new class of drugs in sight. Bachman and Dyer. Nature reviews. 2004 vol3 -Inflammatory resolution: new opportunities for drug discovery. Derek Gilroy et al. Nature reviews. 2004 vol3. -Recognition of microorganisms and activation of the immune response. Ruslan Medzhitov. Nature 2007 vol449/18. -Basic Immunology: Function and Disorders of the Immune System. Abul Abbas. 2nd edition.