Immunoregulatory Drugs: Flashcards
What is the purpose of Immunoregulatory Drugs?
- To suppress the immune systems response in organ transplantation and autoimmune diseases.
- Suppress inflammatories diseases.
What is the purpose of Immunostimulatory Drugs?
-Applicable to treatments of infection, immunodeficiency and cancer.
What is innate immunity?
- Immediate response
- Receptors which recognize common molecules, microbes and viruses.
- -Includes macrophages, neutrophils, mast cells, natural killer cells, complement and interferon.
What is acquired immunity?
- Takes days–> weeks
- Unique antigen specific receptors called B cells and T cells (lymphocytes)
- Includes antigen presenting cells, T- lymphocytes & B-lymphocytes.
–>Cell mediated responses and humeral responses.
What is a cell mediated response in acquired immunity?
-Involves Th1 mediated activation of macrophages and generation of CD8+ cytotoxic T-1 lymphocytes (CTL’s)
What is the humeral response in acquired immunity?
-Involves TH2 cells which secrete cytokines that stimulate proliferation and differentiation of B cells to antibodies- secreting plasma cells.
What is released from cells that plays a role in inflammation of Rheumatoid Arthritis?
Cytokines: TNF-alpha, IL-2, IFNs, TGFs, CSF’s, etc.
Chemokines:
What are Chemokines?
- A family of chemotaxis cytokines that are secreted or membrane bound, and are structurally related proteins of 67- 127 amino acid peptides. There are about 50 Chemokines in humans, which fall in 4 subfamilies:
- ->CXC (alpha), CC (Beta), C (gamma) and CX3C (delta)
- -Chemokines transmit the signals to the cells via binding chemokine receptors, which are 7 transmembrane G protein coupled receptors similar to the cell surface receptors for other chemoattractants.
*Over 40 chemokines within the 4 subclasses.
What is the role of Chemokines in inducing Inflammation?
- -Chemokines are key players in inducing leukocyte- trans epithelial migration.
- Chemokines interact with endothelial cells and activate Integrins on tolling leukocytes to trigger firm adhesion to the endothelium– a prerequisite for leukocyte transmission.
–>Integrins respond to breached sub endothelial structures.
What are the 2 cytokines detected in Rheumatoid Arthritis?
- TNF alpha (from monocytes/ macrophages)
- IL-1B (from monocytes/ macrophages)
*Both increase inflammation & tissue damaged which leads to the pain associated with rheumatoid arthritis.
Overview of the Treatments for Rheumatoid Arthritis:
- Physical Therapy,
- Drugs for the relief of symptoms (NSAIDS, simple analgesia, corticosteroids)
- Surgery
- Disease- Modifying Anti-Rheumatic Drugs (DMARDS)
- Immunosuppressive Drugs
- Complementary medicine (Diet and Food supplements)
Prednisone, Prednisolone, Methylprednisolone
- Glucocorticoid
- Has immunosuppressive effects on tissue
- Leads to regression of lymphoid tissue, enhances destruction of lymphocytes, interferes with the cell cycle of activated lymphoid cells, inhibit leukocyte actions including recruitment, migration, chemotaxis, phagocytosis and activation of CTLs, inhibits antibody formation as inhibit inflammatory mediators.
- ->Prednisone inhibits COX-2 and thus reduces it’s release of inflammatory mediators (PGs and IL’s)
- Blocks PLA2, therefore limiting the availability of AA.
Clinical Uses of Glucocorticoids as well as Adverse Effects:
- Organ and Tissue Transplantation
- Auto immune diseases
- Inflammatory diseases (Allergy and bronchial diseases, RA, IBD, ect.)
Adverse Effects:
- Suppression of the Pituitary- Adrenal Axis
- Increased susceptibility to serious infections.
- Peptic ulcers
- Catabolic Effects (Hyperglycemia, bone catabolic effects, ect.)
What are Cytokines and what are their key Adverse Effects?
- Cytokines are soluble, antigen- non specific signalling proteins that bind to the cell surface receptors on a variety of cells.
- Cytokines include Interleukins, interferons, TNFs, TGFs, CSFs and chemokines.
AEs:
- Nephrotoxicity
- Hepatotoxicity
- Predisposition to infections
- ->Lymphoma (cancer) may occur. Most immmunosuppresive drugs pose a threat to cancer.
Other adverse effects include hypertension, hyperkalemia, tremor, hirsutism, glucose intolerance and gum hyperplasia.
•Cyclosporine (CsA):
- Type of cytokine
- Suppresses cell mediated immune reactions, whereas humoral immunity is affected to a far lesser extent.
- ->CsA binds to cyclophilin and the complex binds and inhibits calcineurin. NFAT remains inactive and can’t enter the nucleus to promote the synthesis of several cytokines, including IL-2.
AE: -Nephrotoxicity (always monitor kidney function)
- Hepatotoxicity
- Predisposition to infections
- Chance of lymphoma
- Other AE’s include hypertension, hyperkalemia, tremor, hirsutism, glucose intolerance and gum hyperplasia.
- ->CsA causes very little bone marrow toxicity.
Tacrolimus (TAC,FK506):
- Is a more potent cytokine compared to Cyclosporine A, and allows for lower doses of glucocorticoid to be used in conjunction.
- Binds to a different immunophilin (FKBP-12)
Sirolimus (Rapamycin):
- Also binds FKBP-12, which forming a complex called mTOR (Mammalian Target of Rapamycin)
- When Sirolimus binds to mTOR after IL-2 has bound it’s receptor, it blocks the progression of activated T cells from the G1 to the S phase of the cell cycle, consequently blocking the proliferation of these cells and reducing the response of IL-2s.
- Sirolimus does not owe it’s effects to lowering IL-2 production, but rather it inhibits the cellular response to IL-2.