Immunosuppressants Flashcards

1
Q

what is autograft?

A

cells from the same person are put back on them in another location

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2
Q

what is allograft?

A

cells or tissue from a donor and giving them to another person to use

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3
Q

what is xenograft?

A

taking human tumour cells and putting them in mice (or another species)

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4
Q

what are the 3 stages of graft (organ) rejection?

A

hyperacute - in minutes
aute - 7-21 days
chronic - 3 months

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5
Q

what can cause organ rejection?

A

tissue have certain memories, and when they are placed in another individual and the tissues mesh but are not completely compatible, a reaction can occur

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6
Q

what is the major target for anti-rejection drugs?

A

T cell and B cell activation/clonal expansion, cytokine production, antibody action

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7
Q

what is the process that leads to organ rejection?

A

foreign organ proteins bind to antigens on macrophages
stimulate T cell response
T cells help mediate B cell response by releasing cytokines(make antibodies)
antibodies mediate antibody response (neutralization, opsonization, phagocytosis), leading to organ rejection

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8
Q

describe the process of antibody formation

A

1) antigen binds to antigen receptor on activated B cell
2) proliferation occurs
3) further proliferation and differentiation into two types of cells
4) plasma cells mediate antibody response
5) memory cells contain antibody memory aspect and knows if youve been exposed to the allergen before

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9
Q

what are anti-rejection drugs

A

drugs that act on the induction phase (B cell activation via T cells and proliferation) of immune response or that target the effector phase of immune response (differentiation/synthesis of B cells leading to tissue injury)

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10
Q

what are two categories of anti-rejection drugs targeting induction phase? give examples for each

A

inhibitors of interleukin-2 production (cyclosporine, tacrolimus)
inhibitor of cytokine gene expression (glucocorticoids)
both IL and cytokines are major factors that help activate B and T cells

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11
Q

what is cyclosporine?

A

a fat soluble cyclic peptide with 11 amino acids derived from fungus Tolypocladium inflatum and is used in the treatment of organ transplant (kidney, heart, bone marrow)

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12
Q

what is a benefit of cyclosporine?

A

low doses can be used in autoimmune diseases such as RA

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13
Q

What is the moa for cyclosporine?

A

cyclosporine binds to cytosolic protein cyclophilin (immunophilin) and form a complex which inhibits calcineurin/NF-AT activation and blocks IL-2 gene transcription - decr. T cell activation

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14
Q

briefly describe the PK for cyclosporine

A
Oral or IV admin
oral admin has slow and incomplete absorption
metabolism occurs in both GI and liver
t1/2 = 24h
concentrated in peripheral tissue
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15
Q

what are some side effects of cyclosporine?

A
nephrotoxicity**
hypertension
increased risk of infection
liver dysfunction
others: hyperglycemia, anorexia, lethargy, hirsutism, tremor, paraesthesia, gum hypertrophy, GI upset
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16
Q

what are some drug interactions with cyclosporine? which inhibits its metabolism and which induce it?

A
inhibit:
CCBs
antifungals - ketoconazole, fluconazole
antibacterial agents - erythromycin, clarithromycin
grapefruit juice
induce:
anticonvulsants - phenytoin
antituberculosis agents - isoniazid, rifampin
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17
Q

what is tacrolimus?

A

a macrolide antibiotic produced by Streptomyces tsukubaenis with an moa similar to cyclosporine and used to prevent organ transplant rejection

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18
Q

how does the moa of tacrolimus differ from cyclosporine?

A

it binds to immunophilin FK binding protien (FKBP) which inhibits calcineurin phosphatase - leading to decreased activation of transcription factor NF-AT and decreased IL-2 gene transcription

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19
Q

briefly describe the PK for tacrolimus

A

oral or IV admin
t1/2 = 9-12h
metabolized by the liver
toxic effects similar to cyclosporine

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20
Q

what are 5 categories of anti-rejection drugs targeting effector phase? give examples of each

A

1) inhibit action of IL-2 (sirolimus)
2) inhibitors of purine synthesis (myclophenolate mofetil, azathioprine)
3) alkylating cytotoxic agents (cyclophosphamide)
4) suppressor of immune response (glucocorticoids)
5) immunosuppressive antibodies (polyclonal or monoclonal antibodies)

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21
Q

what is sirolimus?

A

a new macrolide antibiotic derived from Streptomyces hygroscopicus

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22
Q

what is the moa for sirolimus?

A

binds to intracellular immunophilins but does NOT block IL-2 gene transcription
interferes with IL-2 signal transduction pathway in activated T cells resulting in deceased clonal proliferation of T cells and B cells

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23
Q

what is mycophenolate mofetil?

A

an agent that is converted to mycophenolic acid

selectively inhibits proliferation of both T and B lymphocytes and cytotoxic T cells

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24
Q

what is the moa for mycophenolate mofetil?

A

potent inhibitor of inosine 5’-monophosphate dehydrogenase, a crucial enzyme in purine synthesis
T cells and B cells are particularly dependent on this pathway for proliferation

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25
Q

briefly describe the PK for mycophenolate mofetil

A

oral admin (well absorbed)
Mg and Al impair absorption
metabolite mycophenolic acid and glucoronide conjugate undergo enterohepatic circulation
eliminated by kidney as inactive glucoronide

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26
Q

what does azathioprine do?

A

it is metabolized to 6-mercaptopurine which is a purine antimetabolite
interferes with purine synthesis (inhibits HGPRT enzyme, which catalyzes conversion of purine base to purine ribosyl monophosphate) and is cytotoxic in dividing cells
results in inhibition of clonal T and B cell proliferation
inhibits both cell mediated and antibody mediated immune reactions

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27
Q

what is a major side effect for azathioprine?

A

bone marrow depression

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28
Q

what is cyclophosphamide? how does it work?

A

a nitrogen mustard (alkylating agent)
inactive until metabolized by liver into active phosphoramide mustard
alkyl groups cross react with two DNA nucleophilic sites (intra/inter guanine) and inhibit DNA replication, leading to cell death

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29
Q

what are some SE’s of cyclophosphamide?

A

bone marrow depression
affects more WBCs than platelets
GI disturbance

30
Q

give some examples of glucocorticoids

A

prednisone
methylprednisolone
dexamethasone

31
Q

how do glucocorticoids work?

A

high doses induce lymphocyte migration to extravascular space - subsequently reduce lymphocyte proliferation
leads to size reduction of lymphoid tissues
affect more T cells than B cells

32
Q

what is the MoA for glucocorticoids?

A

suppression of the induction and effector phases of immune response:
inhibit macrophage activation (antigen presenting cells) and release of IL-1beta
decrease clonal expansion of T and B cells and IL-2 secreting T cells
decrease production and action of cytokines (interleukins, TNFgamma)
decrease generation of IgG

33
Q

what different conditions can glucocorticoids be used for?

A

anti-inflammatory and immunosuppressive therapy (ex: asthma, allergic rhinitis, eczema, RA, organ transplant)
neoplastic diseases
addison’s syndrome

34
Q

what are some SE’s of glucocorticoids?

A

insomnia, mood changes
increased appetite, weight gain
suppress response to injury or infection
metabolic effects (fluid retention, osteoporosis, GI bleeding, hyperglycemia)

35
Q

what is the difference between polyclonal and monoclonal antibodies?

A

poly - anti-lymphocyte immunoglobulin which inhibits T cells, lysis
mono - antibodies against IL-2 receptor which prevents T and B cell activation and proliferation

36
Q

what do polyclonal antibodies do?

A

bind to proteins on the surface of lymphocytes triggering the complement response and cause lysis of lymphocytes

37
Q

what are some adverse effects of polyclonal antibodies?

A

anaphylaxis

38
Q

what do monoclonal antibodies do?

A

directly against a specific surface component of T cells and affects the induction and effector phases of immune response to allograft
targets CD3 proteins with antigen receptors, CD4 co-receptors, IL-2 receptors

39
Q

what types of meds can be used to prevent acute rejection of an organ transplant?

A

high dose glucocorticoids
purine synthesis inhibitors
immunosuppressive antibodies

40
Q

what types of meds can be used to prevent chronic rejection of an organ transplant?

A

1) triple drug therapy (low dose):
calcineurin inhibitor (tacrolimus)
purine synthesis inhibitors (mycophenolate, azathioprine)
glucocorticoid
2) for breakthrough episodes of chronic rejection: alkylating agents (cyclophosphamide) or immunosuppressive antibodies (poly or monoclonal antibodies)

41
Q

what is an autoimmune disease?

A

occurs when the adaptive immune system loses self-tolerance rendering the system unable to distinguish between self and non-self antigens

42
Q

what happens when the two self-tolerance mechanisms fail?

A

adaptive immune system responds as it would to non-self antigens and mounts an immune response. the body’s inability to eliminate the self-antigen results in a sustained response that leads to chronic inflammation

43
Q

what are 3 classes of drugs used to treat rheumatoid arthritis?

A

NSAIDs
glucocorticoids
disease-modifying antirheumatic drugs (DMARDs)

44
Q

name some examples of DMARDs

A
methotrexate
sulfasalazine
leflunomide
anti-TNFalpha therapies
Anti-IL therapies
45
Q

what is RA?

A

it is a chronic autoimmune disorder involving inflammation within the joint

46
Q

what are the 3 phases in RA and what do each of them do?

A

1) intiation phase - inflammation within joint
2) amplification phase - T cell activation
3) chronic inflammatory phase - tissue injury due to destruction of bone and remodelling of joint

47
Q

why are Anti-TNF and Anti-IL effective DMARDs?

A

because they are released within the joint during the chronic inflammatory phase and are early participatns in the inflammatory cascade

48
Q

name 5 anti-TNF based drugs

A
entanercept
infliximab
adalimumab
certolizumab
golimumab
49
Q

what is etanercept?

A

the only soluble receptor TNF antagonist
it is fully human protein that functions like an antibody and binds to TNF (note: does not bind complement or cause cell lysis)

50
Q

name 3 Anti-IL based drugs

A

anakinra
canakinumab
tocilizumab

51
Q

what is ulcerative colitis?

A

inflammation of the submocosa and ulcerations that may cover the entire surface of the colon

52
Q

what are some symptoms of ulcerative colitis?

A
diarrhea
bleeding
severe pain
loss of nutrition
anemia-starvation (risk)
53
Q

what is a complication that could arise from UC?

A

colon can become stiff from scarring and burst, leading to peritonitis

54
Q

what is Crohn’s disease

A

inflammatory disease which may cover the entire digestive system

55
Q

what are some differences between UC and crohn’s?

A

crohns tends to be separate, isolated regions of inflammation
fistulas may form
intestinal wall may be breached
crohn’s may also be associated with severe skin inflammation

56
Q

what is the curative treatment option for UC?

A

surgical removal of colon

57
Q

what are 3 goals of treatment for IBD?

A

treat the acute outbreak
induce and retain remission
treat complications

58
Q

what is first line treatment for mild-mod UC?

A

5-amino salicylic acid

59
Q

what is 5-ASA?

A

works only in the large intestine in sulfasalzine by bacteria
does not work by COX inhibition
unknown MoA

60
Q

what are the 3 responses patients could have to glucocorticoid use? describe each

A

1) steroid responsive (40%) - symptoms improve over 1-2 weeks and the disease remains in remission as the steroids are tapered off
2) steroid dependent (30-40%) patients respond well to steroids, but experience relapse of the disease with tapering off of steroids
3) steroid unresponsive (15-20%) do not respond to steroid treatment

61
Q

when are glucocorticoids used?

A

acute treatment of mod-severe IBD

not useful in maintaining remission

62
Q

what are some side effects to glucocorticoids?

A
weight gain
moon-face
stress
emotional responses
steroid-dependent diabetes
increased risk of infection
63
Q

when would thiopurines be used for IBD patients?

A

when they are steroid-resistant or dependent
useful for remission and reduction of relapse
not useful for acute attacks due to long onset time

64
Q

when would methotrexate be used in IBD treatment?

A

steroid-resistant or dependent patients

65
Q

when is cyclosporine used for IBD patients?

A

for most serious cases of UC and CD

used right before surgery

66
Q

what are TNFalpha inhibitors?

A

TNFalpha is a major pro-inflammatory ligand

inhibition of this is used to treatment conditions such as eczema and RA

67
Q

which TNFalpha inhibitor is not effective in UC treatment?

A

etanercept

68
Q

what are some disadvantages to using TNFalpha inhibitors for IBD treatment?

A

repopulation of submucosa is required if drug kills immune cells
very expensive
increases changes of serious lung infections, esp. tuberculosis

69
Q

what is thalidomide?

A

inhibitor of NF-kB (transcription factor involved in inflammation)
not used do to serious birth defects when used by pregnant mothers

70
Q

why may anti- or pro-biotics be used in UC and CD treatment?

A

these diseases may be due to changes in intestinal flora

anti- or probiotics could change proportions of different bacteria