2024 IBD Diseases Lecture Notes (IB)

Crohn’s Disease and Inflammatory Bowel Disease Jean Latimer, Ph.D. College of Pharmacy Dept. of Pharmaceutical Sciences [email protected] Inflammatory Bowel Disease (IBD) IBD 2 distinct disorders: Ulcerative Colitis Crohn’s disease – Treatment: non specific mechanisms of anti-inflammatory actio...

Crohn’s Disease and Inflammatory Bowel Disease Jean Latimer, Ph.D. College of Pharmacy Dept. of Pharmaceutical Sciences [email protected] Inflammatory Bowel Disease (IBD) IBD 2 distinct disorders: Ulcerative Colitis Crohn’s disease – Treatment: non specific mechanisms of anti-inflammatory action – Monoclonal antibodies – Drugs chosen on the basis of severity of disease, responsiveness and drug toxicity IBD Symptoms Inflammation of all or part of the digestive tract Weight loss Belly pain Bloody diarrhea Anemia Diagnosed most frequently by colonoscopy If uncontrolled ulcers can form, increased risk of colon cancer Ulcerative colitis The first choice is usually a drug that contains aminosalicylates (not talking about these today) If that doesn't help, your doctor may prescribe a steroid such as prednisone A third option is an immune modifier, which lowers inflammation by changing the activity of your immune system. up to 3 months before you feel the benefits Common Crohn’s disease symptoms Frequent, recurring diarrhea Rectal (Lowest portion of the large intestine that connects to the anus) bleeding Unexplained weight loss Fever Abdominal pain and cramping Fatigue and a feeling of low energy Reduced appetite Outline – Immunosuppressive Drugs (antibodies and others) – Hybridoma Technology – Humanized vs. Chimeric Monoclonal ABs – Anti-TNF antibodies (antagonists) Other drugs (Cyclosporine, Azathioprine, Mercaptopurine, Glucocorticoids, Methotrexate) Inflammatory Bowel Disease Biologic Therapies Most biologic treatments for these diseases are directed against Tumor Necrosis Factor (TNF) Administered by IV The Immune System Innate Immune System: –1st line of defense against pathogens (bacteria, viruses, fungi, parasites), is complement system, cellular aspects Adaptive Immune System: –Requires previous exposure to antigen Cell Types in both types of Immune System Macrophages, Dendritic Cells, Neutrophils, Monocytes T Cells – Natural killer (NK) – Natural Killer T cells (NKT) – gamma delta T (fc T) cells – T Helper Cells TH1 and TH2 cells B Cells (antibody producing cells) BIOLOGIC DRUGS Immunosuppressive Antibodies Mass Production of Immunosuppressive Antibodies Hybridoma Techology – Milstein and Kohler 1975 revolutionized Antibody (AB) field Hybridomas: antibody forming cells fused to immortal plasmacytoma cells Hybridomas Hybrid cells that are stable and produce a specific AB – can be subcloned for mass culture for Antibody production Large scale fermentation facilities used for this purpose Movies https://app.jove.com/science-education/13374/hybridoma-technology Immunosuppressive Abs Background (2) Molecular biology has been used more recently to develop monoclonal antibodies – directed against one epitope of an antigen with another methodology Libraries of cDNAs encoding heavy and light genes, expressed on bacteriophage surfaces are screened against purified antigens Purified antigens can be from: – from disease pathogens of interest – bacterial proteins – cancer cells – viruses – cytokines – To produce high affinity and high specificity antibodies Other Genetic Engineering Techniques lead to Humanized ABs Chimeric Monoclonal Antibodies of murine (mouse) antibodies Humanized Antibodies from murine antibodies – to reduce their antigenicity – & increase the half life in human patients AB Figure Mouse antibodies given to human patients elicit production of: –Human Anti-Mouse Antibodies that are cleared quickly (HAMAs) Naming of Antibodies H anized Antibodies: ◊ umab ◊ zumab Ch eric Antibodies: ◊ imab ◊ ximab these procedures prevent HAMA production for the following ABs Humanization: (humanized) ►Replacing most of the murine antibody with equivalent human regions keeping only the variable antigen specific regions intact Chimeric: ►Mouse human antibodies are similar but with less complete replacement of the murine parts All of the following interact with TNFa Adalimumab (Humira) Certolizumab pegol (Cimzia) Golimumab (Simponi) Infliximab (Remicade) Etanerept RA drug Page 1000 in Lange 14th edition has the trade names Previous Slide Anti-TNFa ABs TNFa: Pro-inflammatory cytokine important in autoimmune diseases (RA) and Crohn’s disease Anti TNFa: Increased risk of lymphoma Inhibitors of tumor necrosis factor (TNF)-alpha represent important treatment advances in a number of inflammatory conditions, – including rheumatoid arthritis (RA) – seronegative spondyloarthropathies – inflammatory bowel disease TNF-alpha inhibitors offer a targeted strategy that contrasts with the nonspecific immunosuppressive agents traditionally used to treat most inflammatory diseases Adverse effects of TNF-alpha inhibition (2) – Malignancy – Induction of autoimmunity – Reactivation of : M. tuberculosis, Hepatitis B & systemic fungi Adalimumab In vivo reduces levels of – C Reactive protein – Erythrocyte sedimentation rate – Serum IL-6 – Matrix metalloproteinases: MMP1 and MMP3 – Serum half life 2 weeks and increased by methotrexate Inhibitors of tumor necrosis factor (TNF) Golimumab – human IgG monoclonal AB – binds soluble and membrane associated TNFa – does not lyse cells Approved for RA, psoriatic arthritis, ankylosing spondylitis Certolizumab pegol – Recombinant humanized Fab fragment that neutralizes TNFa without lysing cells – Coupled to polyethylene glycol – Crohn’s – RA Inhibitors of tumor necrosis factor (TNF) Infliximab – human mouse chimeric IgG monoclonal – human constant regions, mouse variable regions – same activity as adalimumab and etanercept approved for Crohn’s, ulcerative colitis, RA, psoriatic arthritis, plaque psoriasis, ankylosing spondylitis Adalimumab https://www.youtube.com/watch?v=rBfjfwQ45ZU 2:30-3:20 - Completely human IgG - Blocks TNFa binding with its receptor - lyses cells with TNFa receptors on surface in presence of complement - RA, psoriatic arthritis, ankylosing spondylitis, Crohn’s and plaque psoriasis Adalimumab Movie Anti TNF Antibodies Katzung and Lange 14th Edition Natalizumab (not TNF alpha related) Humanized IgG, binds alpha4 subunit of integrins expressed on leukocyte surfaces - Inhibits a 4 adhesion of leukocytes to their cognate receptor - Used for Multiple Sclerosis and Crohn’s disease Glucocorticoids Glucocorticoids aka corticosteroids 1st hormonal agents recognized as having lympholytic properties Reduce the size and lymphoid content of the lymph nodes and spleen Glucocorticoids Mechanism of action: (chapter 39 Lange) – cytotoxic (cell killing) to certain subsets T cells – but effects due to ability to modify cellular functions, rather than to direct cytotoxicity Glucocorticoids Cellular immunity more affected than humoral (within adaptive immunity: Humoral immunity: deals with antigens freely circulating, Cellular immunity: occurs inside infected cells and is mediated by T lymphocytes and Antigen presenting cells) Although with continued use, primary AB response can be diminished Continued use increases the catabolic (break down) rate of IgG, major class of AB immunoglobulins, lowering the effective concentration of specific ABs Glucocorticoid Toxicity adrenal suppression growth inhibition muscle wasting osteoporosis salt retention glucose intolerance (diabetes risk) behavioral changes Dosages are tapered up and down at the beginning and ending of treatment Cyclosporine Positive and negative effects of Cyclosporine –Cyclosporine may cause tumors because it induces TGF beta which promotes tumor invasion and metastasis –Also it depresses the immune system (what we want) TGF B MOVIE please watch on your own https://www.youtube.com/watch?v=Z1gSsKxBN8U&t=37s Cyclosporine in combination and alone May be given in combination with glucocorticoids (and other immunosuppressants) Sole immuno-suppressant for cadaveric transplantation of solid tissue Cyclophilin A Main target of the immunosuppressive drug Cyclosporine A Immunosuppressive activity of cyclosporines correlate with their ability to form complexes with cyclophilins Cyclophilins inhibit Calcineurin Phosphatase activity Autoimmune disease use of Cyclosporine Rheumatoid arthritis Uveitis Psoriasis Asthma Ulcerative colitis Newer formulations (smaller, better tasting pills) Combined with newer agents Cyclosporine + methotrexate are given together –for prophylactic regimen to prevent graft vs. host allogeneic stem cell transplantation CYTOTOXIC AGENTS Cytotoxic Agents Azathioprine Methotrexate These are not used for IBD (below): Cyclophosphamide Leflunomide Hydroxychloroquine Cytarabine – Vinblastine – Vincristine Azathioprine Prodrug of mercaptopurine – (forms mercaptopurine) Functions as Anti-metabolite – kills proliferative cells small amounts of unchanged drug and the metabolite are excreted from the urine inactivation of the drug depends on xanthine oxidase so patients on allopurinol for hyperuricemia should receive a reduced dose of azathioprine Azathioprine Interferes with purine biosynthesis at steps required for the wave of lymphoid cell proliferation after antigen stimulation Destroys lymphoid cells Cellular immunity – primary and secondary serum antibody responses knocked out So why should purine or pyrimidine synthesis blocking matter? You need a LOT of purines and pyrimidines to replicate DNA and for 46 chromosomes you need them quickly, because replication proceeds quickly Cancer cells divide much faster than normal cells Replication Movie https://www.youtube.com/watch?v=bee6PWUg Po8 Speed of DNA replication Azathioprine Usage In Lupus management of glomerulonephritis Rheumatoid Arthritis Crohn’s Disease Multiple Sclerosis (MS) Prednisone-resistant antibody-mediated idiopathic thrombocytopenia purpura Autoimmune hemolytic anemias Toxicity: Azathioprine & Mercaptopurine bone marrow suppression – leukopenia, but also anemia, thrombocytopenia fever gastrointestinal symptoms liver dysfunction (alkaline phosphatase levels) jaundice (with pre-existing liver disfunction) Methotrexate (antimetabolite) Folic acid analog that binds with high affinity to active catalytic site of dihydrofolate reductase (DHFR) Results in inhibition of synthesis of tetrahydrofolate (THF), the key one carbon carrier for enzymatic processes involved in de novo (new) synthesis of thymidylate, purine nucleotides and amino acids: serine and methionine Affects DNA, RNA synthesis and some protein synthesis in the cell Use in RA, Crohn’s, other autoimmunity diseases Fin