Agents Which Affect the Immune Response Dan Fernandez

Overview I. Immune System Overview II. History of Immunology III. Current Treatment Techniques Immunosuppressants Tolerogens Immunostimulants Immunization IV. What the future holds V. Conclusion

History of Immunology 430 BC: Earliest known mention of immunity during the plague of Athens Thucydides noted that recovered individuals could help nurse the sick without getting the illness a second time University of Maryland conference concluded that typhus was the causative disease, though its still up for debate 18th Century: Scientist de Maupertuis experimented with scorpion venom and found some mice and dogs were immune to effects. Louis Pasteur later exploited these observations in developing vaccination and germ theory of diseases. 1891: Robert Koch published proof that microorganisms caused infectious diseases GO QUICKLY

History of Immunology Paul Erlich Noted for curing syphilis and research into autoimmunity Side-Chain Theory: explained effects of serum and enabled measurement of antigen Coined term “chemotherapy” Work showed the existence of a blood brain barrier Popularized concept of “magic bullet” Target specifically a bacterium without affecting other organisms Salvarsan GO QUICKLY

History of Immunology Ilya Ilyich Mechnikov Received nobel prize in 1908 for his work on phagocytosis Realized digestion was basically same mechanism done by white blood cells to engulf and destroy harmful bacteria Current popular thought was that white blood cells actually helped spread the ingested pathogens around the body Also believed that aging is caused by toxic bacteria in gut and that lactic acid could help prolong life Drank sour milk everyday Thought inspired Minoru Shirota to investigate relationship between bacteria and good intestinal health This led to marketing of fermented milk drinks, a.k.a. Probiotics Neutrophils hunt and kill white blood cells. Staph a have been added. Bacteria release chemoattractant sensed by the neutrophil, which becomes polarized and starts chasing the bacteria. Thermal energy moves the bacteria in a random path. When the neutrophil catches the bacteria, it engulfs the bacteria by phagocytosis Neutrophil Chase

Immune System Overview Two types of Immune Response Non-specific (Basically just recognizes foreign vs native) Barriers Inflammation Phagocytes All types of White Blood Cells (Leukocytes) Dendritic Cells Macrophages Neutrophils

Immune System Overview Specific (Adaptive) Response Lymphocytes (also types of white blood cells) B Lymphocytes (B Cells) Produced in bone marrow Humoral Response Before Infection/Infiltration T Lymphocytes (T Cells) Start in bone marrow, but mature in Thymus Cell Mediated Response Helper T Cells Cytotoxic T Cells Once activated, T Cells and B Cells differentiate and divide Causes cytokine and lymphokine release

B-Cells Have membrane-bound antibodies on cell surface Make antibodies Variable and specific for each B-Cell Make antibodies Activation: Antigen must bind to sites Stimulation by Helper T-Cells

T-Cells Helper T Cells Cytolytic T Cells T-Regulatory Cells (Tregs) Respond to nearly all antigens, Produce CD4, which helps bind to class II MHC complexes on antigen presenting cells Cytolytic T Cells Main response towards infected and cancerous cells Produce CD8 protein, binds transplanted tissue, infected cells, cancer cells Secrets proteins that cause cell death T-Regulatory Cells (Tregs) Suppress the activation of the immune system to help maintain homeostasis

Rheumatoid Arthritis Disease that leads to inflammation of the joints and surrounding tissues Can affect organs The immune system confuses healthy tissue with foreign and begins to attack itself Occurs at any age, usually affects women more than men Affects joints on both sides equally Wrists, fingers, knees, feet, ankles http://www.scienceclarified.com/images/uesc_01_img0050.jpg

Systemic Lupus Erythematosus Autoimmune disease Symptoms: Chest pain, fatigue, fever, general discomfort, hair loss, mouth sores, sensitivity to sunlight, skin rash, swollen lymph nodes, arrhythmias, blood in urine, abdominal pain, coughing up blood, patchy skin colors Other form: lupus nephrititis Can cause kidney failure and lead to dialysis http://www.taconichills.k12.ny.us/webquests/noncomdisease/lupuspic.jpg

Other Immunological Diseases Type I diabetes mellitus Multiple sclerosis Asthma Allergies SCID

Treatment Strategies Immunosuppression – involves downregulating immune system activity Tolerance – the idea that a body can be taught not to reject somthing Immunostimulation – involves upregulating immune system activity Immunization – active or passive It depends on the disease which one you will use to treat. As such, it’s easy to sort of classify the drugs under a wide umbrella: -suppressants will be used when the immune system is overactive, like in auto-immune disorders, and used to help prevent transplant rejection -tolerance involves inducing and maintaining tolerance -stimulation will be used in diseases where there’s an immune deficiency, in order to stimulate the body to do what it was built to do

Immunosuppression – Glucocorticoids Usually co-administered with other suppressive agents to treat auto-immune disorders or treatment of transplant rejection Exact mechanism not elucidated Very broad anti-inflammatory effects Downregulate IL-1 and IL-6 Cause apoptosis in activated cells IL-1 and IL-6 are pro-inflammatory agents

Immunosuppression – Glucocorticoids Side Effects Toxic Causes increased infection risk Poor wound healing Hyperglycemia Hypertension Increased infection risk occurs with all immunosuppressants, as they decrease your body’s natural defenses. Must be careful!

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Immunosuppression – Glucocorticoids Prednisone Dexamethasone Dexamethasone is a potent synthetic member of the glucocorticoid class of steroid drugs. It acts as an anti-inflammatory and immunosuppressant. It is 20 to 30 times more potent than the naturally occurring hormone cortisol and 4 to 5 times more potent than prednisone. Cortisol

Immunosuppression – Calcineurin Inhibitors Calcineurin – protein phosphatase that activates T Cells by dephosphorylating transcription factors, including NFAT (nuclear factor of activated T cells). Blocks T Cell proliferation Decreased immune response When an antigen-presenting cell interacts with a T cell receptor on T cells, there is an increase in the cytoplasmic level of calcium, which[2] activates calcineurin, by binding a regulatory subunit and activating calmodulin binding. Calcineurin induces different transcription factors (NFATs) that are important in the transcription of IL-2 genes. IL-2 activates T-helper lymphocytes and induces the production of other cytokines. In this way, it governs the action of cytotoxic lymphocytes and NK cells. The amount of IL-2 being produced by the T-helper cells is believed to influence the extent of the immune response significantly.

Immunosuppression – Calcineurin Inhibitors Tacrolimus a.k.a. FK-506 Tacrolimus – Prograf®; macrolide antibiotic with greater efficacy than most Calcineurin inhibitors b/c it’s easy to monitor blood levels. It forms a complex with tacrolimus-FKBP-12, Ca+2, calmodulin, and calcineurin, which inhibits the phosphatase activity of calcineurin. Cyclosporine A has similar mechanism to Tacrolimus Cyclosporin A

http://drtedwilliams.net/cop/753/753CalcineurinInhibitors.GIF

Immunosuppression – Anti-proliferative and Anti-Metabolic Drugs Inhibit immune cell proliferation, reducing the immune response mTOR inhibitors Enzyme in lymphocyte cell that is key to transition from G1 to S phase

Immunosuppression – Anti-proliferative and Anti-Metabolic Drugs Sirolimus administered with glucocorticoids, have a synergistic effect Everolimus Sirolimus

Immunosuppression – Anti-proliferative and Anti-Metabolic Drugs Azathioprine Purine anti-metabolite Tioguanine Mercaptopurine Azathioprine Guanine

Immunosuppression – Anti-proliferative and Anti-Metabolic Drugs Mycophenolate Mofentil (CellCept®) Hydrolyzed to mycophenolic acid IMPDH inhibitor (inosine monophosphate dehydrogenase enzyme Important in biosynthesis of guanine Good alternative to azathioprine when toxicity is an issue Mycophenolic acid

Immunosuppression – Monoclonal Antibodies Anti-CD3 Antibodies Binds to chain of CD3, which is involved in T-cell antigen recognition, signaling, and proliferation Administration of mAb followed by depletion of T cells from bloodstream and lymphoid organs Lack of IL-2 production Reduction of multiple cytokines Not IL-4 and IL-10 Used to treat organ transplant rejection Muromonab-CD3 (Orthoclone OKT3®)

Immunosuppression – Monoclonal Antibodies Anti-IL-2 Receptor [Anti-CD25] Antibodies Exact mechanism not understood Binds to IL-2 receptor on surface of activated T cells No effect on resting T cells Stops current response Daclizumab and Basiliximab

Immunosuppression – Monoclonal Antibodies http://www.facetbiotech.com/images/moa_illustrations/FACET_MoA_ELOTUZUMAB.jpg

Immunosuppression – Other Agents Others include Alemtuzumab (mAb) – targets CD52, causes lympholysis by inducing apoptosis of targeted cells IL-1 Inhibition Alefacept – protein, interferes with T-cell activation

Tolerance Strategy is to induce and maintain tolerance Useful strategy for organ transplantation Very much the target of research today Would represent a true cure for autoimmune conditions without side effects of immunosuppressive agents “Holy Grail” of immunomodulation

Tolerance Co-Stimulation Donor Cell Chimerism Requires two signals to activate Donor Cell Chimerism Co-existence of two genetic lineages in a single individual First dampen or eliminate immune function with ionizing radiation, drugs, or antibodies The provide new source of immune function by transfusion Shows promise in development of long-term unresponsiveness

Immunostimulants Immunostimulants are applicable during infections, immunodeficiency, and cancer Levamisole Restores depressed immune function of B and T Cells, monocytes, and macrophages Causes agranulocytosis Removed from market in 2005 Agranulocytosis – severe and dangerous lowered white blood cell count Levamisole

Immunostimulants Thalidomide Teratogenetic BUT is useful to treat erythema nodosum leprosum and multiple myeloma Multiple Myeloma – cancer of plasma cells (B cells that make antibodies) Erythema nodosum leprosum – inflammation of fat cells under the skin characterized by red nodules or lumps Thalidomide

Immunostimulants Interferons Bind to spefici cell-surface receptors that initiate series of intracellular events Induction of enzymes Inhibition of cell proliferation Enhancement of immune activity Intron A ® - peptide used for tumor treatment and infectious diseases; Actimmune ® - peptide that activates phagocytes and induces generation of oxygen metabolites that are toxic to a number of microorganisms

Immunization Active or passive Active – stimulation with antigen to develop antigens for future prevention Passive – administration of antibodies to individual already exposed or about to be exposed to antigens Vaccines – active; administration whole, killed organism, live organism, or specific peptide from organism Immune Globulin – used in passive immunization; used in individuals deficient in antibodies

Future More research into Tolerance may yield less immunological diseases Always looking for more specific targets Less toxic compounds needed with less side effects

Conclusion Most immunomodulatory drugs are suppressants Cause problems as it makes patients more susceptible to infection Most are somewhat toxic Tolerance is a great concept but not yet fully realized Stimulants are helpful to boost the immune system Immunization has been a proven tool against fighting infectious diseases

References Besedovsky, Hugo O., and Adriana Del Rey. "Regulating Inflammation by Glucocorticoids." Nature Immunology 7.6 (2006): 537. Print. Campbell, Neil A., and Jane B. Reece. "43. The Immune System." Biology. 7th ed. San Francisco: Pearson, Benjamin Cummings, 2005. 898-921. Print. Goodman, Louis Sanford, Laurence L. Brunton, Bruce Chabner, and Björn C. Knollmann. "35. Immunosuppressants, Tolerogens, and Immunostimulants." Goodman & Gilman's The Pharmacological Basis of Therapeutics. 12th ed. New York: McGraw-Hill Medical, 2011. 1005- 030. Print. Hamawy, MM. "Molecular Actions of Calcineurin Inhibitors." Drug News & Perspectives 16.5 (2003): 277-82. Print. Marder, Wendy, and W. McCune. "Advances in Immunosuppressive Therapy." Seminars in Respiratory and Critical Care Medicine 28.4 (2007): 398-417. Print.  

Reading Assignment Hamawy, MM. "Molecular Actions of Calcineurin Inhibitors." Drug News & Perspectives 16.5 (2003): 277-82. Print. Marder, Wendy, and W. McCune. "Advances in Immunosuppressive Therapy." Seminars in Respiratory and Critical Care Medicine 28.4 (2007): 398- 417. Print.  

Homework Questions Who were the two main fathers of modern immunology and what were their major contributions? What is the mechanism of action of Azathioprine? What is the mechanism of action of Leflunomide? Explain the Calcium-calcineurin cascade.