PMI03-2014 Flashcards
Describe an acute inflammatory response.
Microvascular effects triggered by a variety of cell and plasma in and around these vessels, including local hormones and inflammatory mediators
Give examples of some inflammatory mediators.
Histamine
Bradykinin
Nitric oxide
Eicosanoids (prostaglandins, leukotrienes, thromboxanes)
Neuropeptides (substance P, CGRP)
Cytokines
Complement
VEGF
What type of molecule is histamine and what is it derived from?
Amine
From histidine
What type of molecule is bradykinin?
Peptide
What type of molecule are eicosanoids and what are they derived from?
Lipids
From arachidonic acid
What are the major sources of histamine in the body?
Mast cells and basophils
When is histamine typically released?
Allergic/type I hypersensitivity reactions
What do histamine/H1 receptors mediate?
Increased blood flow
Increased microvascular permeability
Itch
Give an example of a sedating H1 antagonist.
Chlorpheniramine
Diphenhydramine
Promethazine
Give an example of a non-sedating H1 antagonist.
Loratadine
Cetirizine
Terfenadine
Astemizole
Are H1 antagonists preferred to be sedating or non-sedating nowadays?
Non-sedating
What are the main pain neurons?
C and Aδ fibres
What do the pain neurons do?
Transmit sensory info to CNS/initiate reflexes = pain/itch
Release neuropeptides, including substance P and CGRP
What percentage of afferent C fibres in skin mediate itch?
5%
Describe the C fibres that mediate itch.
Respond to histamine and are unresponsive to mechanical stimuli
Slow conducting velocities of 0.5m/s (half that of normal C fibres)
What type of medication is an effective anti-itch agent?
Anti-histamine
What enzyme catalyses the formation of prostaglandins?
COX (cyclooxygenase)
What are the two types of COX and when are they present?
COX-1 = prevalent all the time
COX-2 = inducible and found at inflammatory sites
What is the chemical name of arachidonic acid?
5, 8, 11, 14-eicosatetraenoic acid
Which enzyme catalyses the formation of leukotrienes?
5-lipoxygenase
What does COX do?
Converts arachidonic acid to prostaglandins
What does 5-lipoxygenase do?
Converts arachidonic acid to leukotrienes
What cells release PGE2 and PGI2 and what do these molecules do?
Released by endothelial cells and white blood cells
Mediate increased blood flow and hyperalgesia (increased sensitivity to pain)
What cells release PGD2?
Mast cells
What common condition are leukotriene (LT) antagonists used for?
Asthma
What do LTC4 and LTD4 do?
Increase microvascular permeability
Bronchoconstriction
What does LTB4 do?
Chemotaxin = recruits neutrophils to inflammatory sites
What is the pathway of prostaglandin formation?
Arachidonic acid | PGG2 | PGH2 | PGI2 or PGE2 or PGD2 or PGF2α (or TXA2)
Mediated by COX (mainly)
Give an example of a cyclic endoperoxide.
PGG2
PGH2
What is an alternative name for COX?
Prostaglandin-endoperoxide synthase
What is another name for PGI2?
Prostacyclin
Where is PGF2α found?
Lungs and reproductive tissues
What enzyme do NSAIDs inhibit?
Cyclooxygenase
What are the effects of NSAIDs?
Analgesic (pain-relieving)
Anti-inflammatory
Fever-reducing
May enhance bleeding and stop normal vasodilatation and mucus secretion
Why may NSAIDs enhance bleeding?
Inhibit COX
No TXA2 formed by activated platelets which is essential in haemostasis
Give some of the types of NSAIDs.
Salicylates (aspirin)
Acetic acids (indomethacin, diclofenac)
Propionic acids (ibuprofen, naproxen)
Oxicoms (piroxicam, phenylbutazone)
Fenamates (meclofenamate)
What type of NSAID is aspirin?
Salicylate
What type of NSAID is ibuprofen?
Propionic acid
What is the difference with paracetamol and typical NSAIDs effect-wise?
Paracetamol is not anti-inflammatory
What is another name for paracetamol?
Acetaminophen
Why do we use ice to treat some injuries?
Suppresses vasoactive components to reduce swelling
Why do we use noradrenaline to treat some injuries?
Reduces blood flow (=> inflammation)
What is the approximate ratio of men to women suffering from rheumatoid arthritis?
1:3
Give some of the inflammatory mediators and their functions in joints in arthritis.
TNF-α (primary mediator)
IL-1 = TNF-α and IL-1 upregulate each other’s activity
IL-6, IL-8, IL-17 = pro-inflammatory
IL-10 = anti-inflammatory
PGE2 = hyperalgesic
Where do most of the inflammatory mediators in the joints in arthritis come from?
Synovial membrane
What does DMARD stand for?
Disease-modifying anti-inflammatory/rheumatic drug
Describe the function of COX-1.
Found in most cells
Involved in normal physiology:
- GI tract = PGs important in maintaining good blood flow and enabling mucus production
- vasculature = TXA2 stimulates thrombus formation, PGI2 inhibits this
Describe the function of COX-2.
Induced in inflammatory cells by inflammatory stimuli
Allows release of high levels of PGs at inflammatory sites
Which form of COX do we want to inhibit clinically?
COX-2
What does celecoxib do?
Inhibits COX-2
What is the use of oral NSAIDs often associated with?
Proton pump inhibitors to inhibit GI reflux due to excess acid - NSAIDs inhibit PG formation so inhibit formation of mucus and substances that neutralise stomach acid
(may choose to use PG analogues, like misoprostol, alongside to protect stomach and maintain bloodflow in CV risk patients)
When are DMARDs and biologics prescribed?
When there is definite disease, and NSAIDs and painkillers are insufficient
What is the usual first choice DMARD?
Methotrexate
Which DMARD is used for SLE and rare diseases?
Azathioprine
Which DMARD has cardiac side effects?
Anti-malarials (chloroquine)
Give examples/types of DMARDs.
Methotrexate
Azathioprine
Anti-malarials (chloroquine)
Sulphasalasine
Penicillamine
Anti-inflammatory steroids
Immunosuppressives
What are biologics?
Larger MW DMARDs (antibody therapy)
Injected
What are “targeted” DMARDs?
Oral
Target specific molecules (eg JAK inhibitor)
Give an example of an anti-inflammatory steroid.
Hydrocortisone
Dexamethasone
Prednisolone
What are the pros of using anti-inflammatory steroids?
Anti-inflammatory:
- inhibit arachidonic acid release
- inhibit cytokines
- downregulation of adhesion molecules
- inhibition of enzyme (COX, NOS) induction
Inhibition of T cell proliferation
(Induces apoptosis)
What are the possible cons of using anti-inflammatory steroids?
Osteoporosis
Increased risk of infection
Adrenal atrophy
Diabetes
How can you decrease the possible cons of anti-inflammatory steroids?
Give anti-inflammatory steroid locally:
- intra-articular
- aerosol
- topically
What does “steroid sparing” mean?
Can take less steroid to give the same effect which reduces side effects
Describe the use of methotrexate.
Folate antagonist
Most widely used anti-metabolite in cancer chemotherapy but may act via other mechanisms for anti-inflammatory effects which may allow lower doses
Better if used early, used in the young and elderly
Can be toxic so monitored with blood tests
May be best when used with an NSAID (co-therapy)
What happens when TNF-α binds its receptor?
Inflammation and tissue damage
How may biologics be used to target TNF-α activity?
Anti-TNF antibodies (monoclonal, synthesised) or soluble TNF receptor constructs can be used if DMARDs fail
Can be given as co-treatments, well-tolerated (compared to other anti-inflammatory drugs
What are the cons with using biologics to target TNF-α?
Effective for only 30% of cases and can be less successful in follow-up treatments
Expensive
Patient may suffer from opportunistic infection (eg TB)
Give an example of anti-TNF biologic treatment.
Anti-TNF antibodies = infliximab (remicade), adalimumab (humira)
TNF receptor constructs = etanercept (enbrel)
What may IL-17 receptor antagonists be used for in the future?
Psoriatic arthritis
What may IL-6 blockers be used for in the future?
Non-responders to anti-TNF or biologics
Effective in treating cytokine storms
What is Tocilizuma/RoActemra examples of?
IL-6 blockers (biologic)
What is canakinumab?
Anti-IL-1 antibody
Treatment for juvenile arthritis and atherosclerosis
What is rituximab/MabThera?
New drug that removes antibody-producing white blood cells
What does abatacept/Orencia do?
Inhibits action of T cells
What are biosimilars?
Biologic medical product that is almost an identical copy of another original product that may be manufactured by a different company
Cheaper as patent runs out
Describe what the traditional methods of treating rheumatoid arthritis are like.
Treating symptoms of pain and swelling
Less aggressive and less toxin (usually NSAIDs)
Describe the modern methods of treating rheumatoid arthritis.
Limiting join destruction with early aggressive treatment (eg methotrexate)
Combination therapy
Use of biologics