Core Immunology - Immunomodulation and Immunosuppression (13) Flashcards
Immunomodulation
Manipulating the immune system using immunomodulatory drugs
What is the therapeutic effect of immunomodulation?
- Immunopotentiation
- Immunosuppression
- Immunological tolerance
Immunopotentiation
Enhancing immune response by adding another substance, increasing it’s rate/prolonging duration
Mechanisms of immunomodulation
Immunisation, replacement therapy, immune stimulants, immune suppressants, anti-inflammatory agents, allergen immunotherapy/desentisation, adoptive immunotherapy
Biologics - immunomodulators
Medicine products produced using molecular biology techniques - recombinant DNA
Classes of biologics immunomodulators
- Substances nearly identical to body’s own key signalling proteins
- Monoclonal antibodies
- Fusion proteins
Anti-TNF
- Adalimumab (human IgG)
- Infliximab (chimeric mouse-human IgG)
- Etanercept (fusion protein)
- Cetrolizumab (humanised)
Immunopotentiation
Increase immune response by administration of another substance (increasing rate/prolonging duration)
Examples of immunopotentiation
Immunisation, replacement therapies, immune stimulants
Passive immunisation
Transfer of specific, high-titre antibody from donor to recipient, provides immediate but transient protection
Problems with passive immunisation
Risk of transmission of viruses, serum sickness
Types of passive immunisation
Pooled specific human Ig, animal sera (antitoxins and antivenins)
Uses of passive immunisation
Hep B (prophylaxis and treatment), Botulism, VZV (pregnancy), Diphtheria, Snake bites
Active immunisation
To stimulate the development of protective immune response from immunological memory
Active immunisation immunogenic material
Weakened forms of pathogens, killed inactivated pathogens, purified materials (proteins, DNA), adjuvants
Active immunisation problems
Allergy to any vaccine component, limited usefulness in immunocompromised, delay in achieving protection
Replacement therapies - Pooled human Ig
Used in treatment of antibody deficiencies (IV/SC)
Immune stimulation - G-CSF/GM-CSF
Act on bone marrow, to increase production of mature neutrophils
Immune stimulation - IL-2
Stimulates T cell activation (rarely used)
Immune stimulation a-INF
Hep C
Immune stimulation B-INF
MS
Immune stimulation y-INF
Intracellular infections (atypical mycobacteria), chronic granulomatous disease, IL-12 deficiency
Interferon
Increases anti-viral response, occurs naturally, increase protein synthesis > increased resistance (makes you feel flu-like)
Immunosuppression
- Cortiocosteroids
- Cytotoxic agents
- Anti-proliferative/activation agents
- DMARD’s
- Biologic DMARD’s
Corticosteroids action
Decrease neutrophil margination, reduce cytokine production, inhibit phospholipase A2 (reduced arachidonic acid metabolites production), lymphopenia, decreases T cell proliferation and Ig production
Corticosteroid side-effects
- Carb and lipid metabolism (diabetes and hyperlipidaemia)
- Reduced protein synthesis (poor wound healing)
- Osteoporosis
- Glaucoma and cataracts
- Psychiatric complications
Uses of corticosteroids
- AI (connective tissue disorder, vasculitis, RA)
- Inflammatory (Crohn’s, sarcoid, GCA/polymyalgia rheumatica)
- Lymphoma
- Allograft rejection
Antimetabolites
Stop proliferation of T-cells - Azathioprine (AZA), Mycophenolate mofetil (MMF)
Calcineurin inhibitors
Ciclosporin A (CyA), Tacrolimus (FK506)
CyA
Binds to intracellular protein cyclophilin
Tacrolimus
Binds to intracellular protein FKBP-12
Calcineurin mode of actions
Prevent activation of NFAT, factors which stimulate cytokines (IL-2 and INFy) gene transcription
M-TOR inhibitors
Sirolimus/rapamycin (structurally related to tacromilus)
M-TOR mode of action
Inhibits target of rapamycin (Macrolide antibiotic), inhibits response to IL-2
M-TOR effects on T cels
Can’t proliferate, cell cycle arrests at GI-S phase
Calcineurin/M-TOR side effects
Increased bp, nephrotoxicity, lymphomas, neurotoxicity, hirsutism (hair growth), hepatotoxicity, opportunistic infections, multiple drug interactions
Antimetabolites
Inhibit nucleotide/purine synthesis
AZA mechanism
Guanine anti-metabolite, rapidly converts > 6-mercaptopurine
MMF mechanism
Non-competitive inhibitor of IMPDH, prevents production of guanosine triphosphate
Antimetabolites effects on B and T cells
Impaired DNA production, prevents early stages of activated cell proliferation
Antimetabolite uses
Allograft rejetion, SLE, vasculitis, IBD
Cytotoxic antimetabolites
MTX and cyclophospamide
Methotrexate mechanism
Folate antagonist
Uses of methotrexate
RA, PsA, GvHD in BMT, RA, Polymyositis, Vasculitis
Cyclophospamide mechanism
Cross-link DNA
Cyclophospamide uses
SLE, vasculitis, Wagner’s, CSS
Side effects of MTX and Cyclophospamide
Bone marrow suppression, gastric upset, hepatitis, susceptibility to infections (MTX - pneumonitis, C-cystitis)
Biological DMARD’s
Biological Disease-Modifying Anti Rheumatic Drugs
Types of biological DMARD’s
Anti-cytokines (TNF, IL-6, IL-1), anti B-cell, anti- T cell activation, anti-adhesion molecules, complement inhibitors
Anti-cytokines
- Anti-TNF (activate macrophages)
- Anti IL-6
- Anti IL-1
Anti-TNF
Used: RA, Crohn’s, Psoriasis, Ankylosing Spondylitis
Anti IL-6
Tocilizumab, RA and adult onset still’s disease
Anti-TNF problems
Increased risk of TB
Anti IL-6 problems
Control of serum lipids
Anti IL-1 examples
Anakinra, Rilonacept, Canakinumab
Anti IL-1 uses
AOSD and auto inflammatory syndromes
Rituximab
Part mouse and part human chimeric mAB against CD20-B cell
Rituximab uses
Lymphoma (B-cell origin), leukaemia, transplant rejection, autoimmune disorder (chemotherapy resistant diffuse large B-cell lymphoma)
Adoptive immunotherapy
Bone marrow transplant or stem cell transplant
Adoptive immunotherapy uses
SCID, lymphomas, leukaemias, inherited metabolic disorders (osteoporosis), AI
Immunomodulators - allergy
Immune suppressants, allergen specific immunotherapy, anti-IgE monoclonal therapy, anti IL-5 monoclonal treatment
Indications of allergy immunomodulators
- Allergic rhinoconjuctivitis not controlled
- Anaphylaxis to insect venom
- Steroids low response
Mechanisms of allergy immunomodulators
Switching of immune response Th2 (allergic) > Th1 (non-allergic), development of T reg cells and tolerance
Routes of allergy immunomodulators
SC/sublingual
Side effects of allergy immunomodulators
Localised/systemic allergic reactions
Monoclonal antibodies against allergies
Omalizumab and Mepolizumab
Omalizumab
Against IgE
Omalizumab uses
Asthma, chronic urticaria and angio-oedema
Side effects of omalizumab
Severe systemic anaphylaxis
Mepolizumab
Against IL-5, prevents eosinophil recruitment and activation