Inflammation and Immunosuppression Flashcards
(104 cards)
4 Signs of Inflammation?
- Rubor/Redness - increase in local blood flow caused by vasodilator action of inflammatory mediators
- Tumor/ Swelling - increase in vascular permeability, proteins and fluid leak from vasculature
- Calor/ Heat - increased blood flow
- Dolor/ Pain - direct action on nociceptors
Causes of inflammation (3)
- Noxious Stimulation
- Bacterial/Viral/Fungal infection
- Autoimmune reactions (when adaptive immune system attacks the body’s own tissues)
Triple Response of Lewis
- Flush - drawing a pointed instrument forcefully across the skin produces a band of redness that matches the size and shape of the stimulus due to local release of vasodilator substances e.g. histamine
- Neurogenic inflammation - Activation of sensory fibres will send APs to the spinal cord + brain (pain), and to other collateral branches. Branches release CALCITONIN GENE RELATED PEPTIDE and SUBSTANCE P –> results in local production of histamine causing vasodilatation and increased vascular permeability
- Wheal - leakage of plasma from blood to the extracellular space causes swelling due to increased vascular permeability
Dermatographic utcaria
A condition in which the triple response is exaggerated; largely idiopathic and generally treated with H1-receptor antagonists
Omalizumab
- Monoclonal antibody
- Recognises IgE, decreases mast cell activation
- Allergen bound IgE induces mast cell degranulation when bound to its receptor FcERI
Where is histamine made and found?
- Made from histidine by histidine decarboxylase
- Found in 4 cell types: mast cells, basophils, enterochromaffin-like cells (ECL) in the gut, histaminergic neurones in brain
- In mast cells + basophils - histamine is packaged into acidic granules with a high molecular weight MACROHEPARIN
Sodium Cromoglycate
Mast cell stabiliser; inhibits degranulation
Decreased Ca2+ influx upon mast cell stimulation, inhibits inward Cl- conductance required to maintain a negative enough membrane potential to enable sustained influxes of extracellular Ca2+
- Used to treat mastocytosis + used as eye drop for hayfever (opticrom)
Mepyramine
First generation H1 antagonist - classical antihistamine used in treating histamine-mediated inflammatory responses
- Rapidly permeate blood brain barrier + caused drowsiness; not suited for systemic use but used a topical creams for insect bites
Terfenadine
Second generation H1 antagonist
- Cannot cross the blood brain barrier
- Inhibits Kv11.1 or hERG causing Long QT syndrome
Pro-drug that is metabolised by p450 3A4 into fexofenadine.
Diminished p450 3A4 activity enhances risk of death
Bergamottin
A component of grapefruit juice which inhibits p450 3A4, thus increasing the potency of Terfenadine (Long QT syndrome)
Fexofenadine/ Loratadine
Third generation H1 antagonists
- Non-drowsy, lack cardiac side effects
- Mainly used in treating hay fever, allergies and urticaria
Adrenaline
Administered intramuscularly in anaphylaxis to counteract systemic vasodilatation and reduction in tissue perfusion
- Relieves bronchospasm
- Co-administered with hydrocortisone (anti-inflammatory)
Why is noradrenaline not used in anaphylaxis
Highly potent vasoconstrictor, which can cause reflex bradycardia
Imatinib
Receptor tyrosine kinase inhibitors used in the treatment of mastocytosis
- Only efficacious in patients that are NOT presenting with the D816V c-Kit mutation
Oclacitinib
Inhibits Janus Kinases (JAK) - JAKs involved in many cytokine signalling pathways associated with allergic skin diseases
- Lowers pro-inflammatory signalling, can be used as an alternative to corticosteroids/ciclosporin
- Treats Atopic Dermatitis in dogs (10%)
Somatostatin
Negative regulator of H+ release from parietal cells. 2 modes of action…
Direct - Activation of SSRT2 Gi coupled receptors on parietal cells counteracts histamine
Indirect - Activation of SSRT2 on ECL and G cells reduces histamine + gastrin respectively
Proglumide
CCK2 receptor antagonist , reduces histamine secretion from ECL which inhibits gastric acid secretion
- Role in treating peptic ulcers has been surpassed
Cimetidine/ Ranitidine
H2 antagonists used in treating peptic ulcers
Note: Cimetidine inhibits CYP450 and has been displaced by ranitidine
Omeprazole
Proton pump inhibitor (PPI), used preferentially to H2 receptor antagonists
- Authorised for use in treating peptic ulcers In horses
- PPIs are converted to active form in the acidic environment of parietal cells and form disulphide bonds with K+/H+ pump
- PPIs are broken down by H+ and have slow onset to maximal effectiveness
- Predominantly metabolised by CYP2C19 which exhibits genetic polymorphism
Vonoprazan
Potassium competitive acid blocker (P-CAB); competes with K+ binding site, has greater stability than PPIs in H+ and CYP2C19 is less important in its metabolism
Clarithromycin
Eradication of Helicobacter Pylori - causative agent in many cases of human peptic ulcers. Dogs may present with gastric ulcers, which can have a variety of causes, Helicobacter are not generally thought to be the cause
Misoprostal
Synthetic prostaglandin E1 (PGE1) analogue given to patients with gastric complications who have been prescribed NSAIDs
Arthrotec
Combination tablet = NSAID diclofenac + misoprostal
- Used in chronic treatment against rheumatoid arthritis
- Misoprostal acts a prophylactic against NSAID induced ulceration
Activation of bradykinin B1 and B2 receptors in the vascular endothelium causes…
Calcium influx –> Activates cytosolic phospholipase A2 (cPLA2) –> Prostacyclin (PGI2) production + endothelial nitric oxide synthase (eNOS) resulting in NO production –> PGI2 + NO diffuse to vascular smooth muscle –> Increase cAMP and cGMP respectively –> Mediate vasodilatation