Immunosuppresive agents Flashcards
Calcineurin inhibitors (2)
Cyclosporin
Tacrolimus
Nuclear transcription inhibitors (1)
prednisone
mTOR inhibitors (1)
sirolimus (Rapamune)
Cell Cycle disruptors (4)
mycophenolate mofetil (CellCept)
azathioprine (imuran)
Methotrexate (trexall)
Cyclophosphamide (cytoxan)
Overall goal of immunosuppresive therapy
reduce T cell population
Critical cytokine released by an activated T cell, for proliferation/clonal expansion
IL-2
CD28 on T cell binds to?
B7 on APC
3 types of immunosuppressive therapies
- induction
- maintenance
- Rescue
Hallmarks of induction therapy
- at the time of the transplant
- relatively intense
- prolonged use prihibitively toxic
- may include donor specific transfusion or irradiation as drug alternatives
hallmarks of maintenance therapy
tolerable in chronic use, but not without side effects
*tends to employ drugs of milder potency that are more tolerable throughout the course of treatment
hallmarks of rescue therapy
intense and effective
chronically intolerable
*applied in response to rejection episode
classic maintenance therapy 3-drug combo
- calcineurin inhibitor (cylosporin)
- anti-proliferative (mycophenolate mofetil)
- steroids (prednisone)
list the order of graft immunogenicity
lungs > heart > kidney > liver > dick
Bind FKB12 protein
Tacrolimus
Polyclonal IgG drugs against human T-Lymphocytes
Thymoglobulin
Nuclear Transcription inhibitors
Prednisone
Binds to FKBP12 (2)
Tacrolimus
Sirolimus
Where do most of these immunosuppressive drugs work?
T cells: Targets include:
- cell surface inhibitors
- calcineurin inhibitors
- transcription inhibitors
- mTOR inhibitors
- cell-cycle inhibitors
Most common drug used in renal transplantation currently
thymoglobulin (poly clonal IgG against T cells)
transplantation between two non-identical organisms
allograft
second signal required for activation of T cell
CD28 must bind to B7 of APC to release autocrine growth factor IL2
IL-2 activated adjacent t cells to udndergo proliferation and differentiation
drugs that target T cell surface would be attempting to inhibit what
- proliferation of T cells in response to IL2
2. targeting the t cell for death by other immuno components
normal treatment path for induction therapy
there is none–> tx is different in each specific case
more similarites between donor/recipient will probably require less potent drugs
more dissimilar–>more potent drugs at higher concentrations
Calcineurin inhibitors MOA
a phosphatase that controls NFAT–>This prevents T cell from upregulate IL-2–>inhibits t cell proliferation and differentiation signal
Monoclonal Ab’s MOA
block secreted IL from an activated T cell from binding to the CD25 receptor on adjacent T cells
*diminishes t cell proliferation
glucocorticoids MOA
act in the cell nucleus to INHIBIT REGULATION of transcription of many proinflammatory cytokines…one of which is IL-2 this downregulate t cell proliferation
Normally, activation by IL-2 leads to what
activation of mTOR and initiation of cell-cycling
*inhibition of mTOR causes the IL-signal to be irrelevant
Where is CD52 expressed
surface of mature lymphocytes
Binding of CD52 by mAb’s leads to what processes
- ADCC (NK cell and is FC dependent) FCgammaR3
2. compliment mediated cytotoxicity
Thymoglobulin MOA
polyclonal IgG against human T lymphocytes–> leads to t lymphocyte depletion via Compliemnt dependent opsonization and lysis
mAb’s that bind to a ligand (2)
infliximab
omalizumab
mAb’s that bind to a receptor (2)
natalizumab
daclizumab
TGN1412 is what
mAb that is a CD28 superagonist
*binding to CD28 receptor can activate the Tcell without TCR ligation to antigen
What does FcRn do
controls transpot or IgG across cell barriers
*fucking Miller keeps calling this the FcRb receptor
Does drugs acting on IL-2 receptor or release lead to cell depletion
NO
target of muromonab
CD3 (transduction unit for a t cell)
target of basiliximab
Cd-25 the IL2 receptor
target of daclizumab
IL 2 receptor (cd25)
drugs that target B7
belacept
drug that targets CD52
alemtuzumab (leads to ADCC and CDC)
problems associated with imunosuppressive
I. increased risk for opportunistc infections
2. secondary malignancies
toxicity associated with CNI’s
- renal toxicity (calcification, vasoconstricton etc)
- mild-moderate HTN from renal vasoconstrcition and increased sympathetic tone
- secondary malignancies
does CNI’s affect T cell, Bcells or both
Both
INHIBITS IFg and IL-2 production in t cells
Il-4 production in B cells
Hirsutism or hypertrichosis is associated with
cyclosporine
CNI with neurotoxicity
Tac (headache, insomnia, parasthesias and dizziness)
Gingival hyperplasia is associated with
cyclosporine
two ways in which corticosteroids+GR inhibit gene transcription of inflammatory proteins
- directly
2. indirectly by recruitment of HDAC–> leads to diminished transcription bc the DNA is too tightly wound up
Blood content reactions (other than inhibition of T cell activity) due to prolonged corticosteroid therapy
- neutrophilia: increased production and decreased apoptosis
- eosinopenia: increased apoptosis
- monocytopenia: decreased production and differentiation
Sirolimus MOA
binds to FKB12–>inhibits mTOR–>leading to cell-cycle arrest
“first phase of T cell activation”
production of autocrine growth factors like IL-2 that lead to proliferation and differentiation
“second phase of T cell activation”
signal transduction and clonal proliferation of T cells (G1 arrest)
synergistic drug that you can give with cyclosporin
sirolimus (does not affect CN activity)
Sirolimus affect on B cells
prevents differntition into antibody producing cells –>decreased host levels of IgM, IgG and IGa
Pt’s taking sirolimus must be monitored for
hyperlipidemia. HTN, fever, diarrhea,
Blood content reaction to sirolimus
anemia, leukopenia, thrompocytopenia, hypokalemia, azotemia (high nitrogen),increased serum creatinine, defreased GFR
pt.s taking sirolimus are at increased risk for?
thromboembolism and DVT’s, secondary malignancies, infections
organ affected by sirolimus
liver–>hepatotoxicity including fatal necrosis of the liver
kidney as well
risk of secondary malignancies is associated with which drug classes
Sirolimus (mTOR inhibitor)
CNI’s (cyclosporin)
mAb’s
MMF
azothiprine (skin cancer with increased UV)
*all due to weakend self-monitoring respnses by immunosuppression
MMF MOA
inhibits inosine monophosphate dehydrogenase–>interrupts DNA synthesis
Cell cycle disruptors affect which cell lines the most?
B and T cells
*cannot synthesize GTP sufficiently through the salvage pathway–>therby if DNA becomes a rate limiting reagent T cell proliferation is inhibited
drug wtih selective effect on lymphocyte proliferation
MMF
drugs without selctive effect on lymphocyte proliferation
methotrexate
asathioprine
Adverse effects of MMF
secondary malignancies
Gi upset
neutropenia (myelosuppression)
Azathioprine is converted to
6 mercaptopurine (an anticancer drug in its own right)
Metabolism for azothiprine
azo->6mc–> 6 thioguanine triphosphate–>
6 thioguanine triphosphate does what
1.Inhibits RAC1
blocks CD28 co stimulation
promotes apoptosis
especially CD45RO (IL2 stimulated)memory T cells
2. leads to cell cycle arrest by incorporating a decoy DNA precursor (6 thio GTP) in to chain
cannot give azothioprine in concert with which drugs
- allopurinol (increases azothioprine toxicity)
2. warfarin (decreased INR)
cyclophosphamide
requires activation of its pro-drug form
greatest effect of cyclophosphamide
suppression of humoral immunity
ADE’s of cyclophosphamide
cardiovascular risks: CHF, toxicity, PE skin cancer azoospermia fibrosis of bladder fibrosis of lungs
uptake of MTX follows
folate pathway
efflux of MTX is via
ABC transporter
MTXPG leads to accumulation of
AICAR
AICAR inhibits ADA and AMp deaminase and leads to
build up of adenosine (which is anti-inflammatory)
where would you find adenosine receptors
APC’s
Adenosine-AR binding does what in APC’s
via cAMP and increased cytosolic calcium
- ->dimnished production of ILa anf TNF-a, MIP1a, and NO
- ->increase production of IL10 and VEGF
S phase specific cell-cycle disruptor
methotrexate
dirreah, NV
pulmonary fibrosis
blood reactions cause by MTX
anemia
leuko, thrompo, neutro, pancytopenias
MTX is a teratogen
yes
drug with no pGp or cyp34 involvment
MMF
substrate + inhibitor for pGp and CYP3a4
cyclosporine
substrate for cyp3a4/ no involvement with pGp
tacrolimus
substrate for CYP3a4 and substrate + inhibitor for PGP
sirolimus
drug used for established rejection pulsed high dosage
muromonab CD3
and
Thymoglobulin
(anti-t lumphocyte ab’s)
used for cardiac transplant via impregnanted stents
sirolimus