Inflammation

Draw and label a bronchiole before and during an asthma attack

https://ibb.co/xStNNXx1

Describe how anti-allergen IgE are generated in the thymus in allergic asthma

• DCs from bronchiole submucosa endocytose

• Present on MHC II

• Bind to naieve T cell with MHC II and B7

• Polarised Th2 response

• Releases IL-4/5/13

• Stimulates isotope swithcing IgG —> IgE

• Increased IgE upregualted FcepsilonRI expression on mast cells

Describe how mast cells are activated in allergic asthma

• Once IgE generated, binds to FcepsilonRI (now upregulated) on mast cells

• Allergen binds

• Cross-links bound IgE

• Brings receptors closer together, tyr autophosphorylation

• Activation of PLCgamma

• Increased IP3

• Increased int Ca2+

• Degranulation

What inflammatory mediators do mast cells release when they degranulate and what do they do?

• Histamine, H1R agonism, bronchoconstriction

• ACh, M3 agonism, brochoconstriction

• TNF-alpha, IL-4/5/13, eosinophil recruitment, Th2 polarisation

What are key pathological features of an asthmatic airway?

• Thickened smooth muscle

• Dilated vessels

• Broken lumen epithelium

• Constricted, uneven lumen

• Thick mucus plug

• Eosinophil infiltrate

What beta2-adrenorecepttor agonists are used for asthma vs COPD?

• Asthma: salbutamol (Short acting, inhaled)

• Asthma and COPD: formoterol (long acting, inhaled, in LABA-LAMA)

How do beta2-adrenoreceptor agonist drugs help alleviate breathlessness in asthma and COPD on a receptor level?

• BGalphaS coupled

• GDP-GTP exchange

• Adneylyl cylase activation

• Increase cAMP

• Increase PKA activity

• Bronchodilation

Why is formoterol long acting but salbutamol short?

• Formoterol has a lipophilic tail

• Embeds in membrane, makes a drug reservoir

Discuss use of short term M3 antagonists in the use of asthma vs COPD (and name one)

• Ipratropium

• Can be used for asthma attacks when bursts of ACh from mast cell degranulation

• COPD irreversible chronic damage, not bursts of ACh during flare ups, short term use would just be risking side effects with no benefit

Discuss the use of long term M3 antagonists in the use of asthma vs COPD (and name one)

• Tiotropium

• Used in LABA-LAMA inhalers for both

• First line COPD, only in progressive asthmatics where damage is becoming permanent

• Want to minimize medication dependence

• Long-term instead of flare up use increases chances of seeing side effects

• Synergistic effect with LABA, minimal effect alone

How do M3 antagonist drugs help alleviate breathlessness in asthma and COPD on a receptor level?

• Compete with ACh for GPCR binding site

• When ACh is used:

• GalphaQ coupled

• PLC activation

• Increase IP3

• Increase int Ca2+

• Callmodulin activation

• Smooth muscle contraction

• Bronchoconstriction

• Antagonizing this prevents ACh-mediated constriction

What are side effects of beta2-adrenoreceptor agonist use?

• Agonises b2adr in skeletal muscle: tremor, and cardiac muscle: tachycardia

Mechanism of action and metabolism of theophylline

• Inhibits PDE

• Increase cAMP, bronchodilation

• Increase cAMP in immune cells makes them require greater stimulus for activation

• CYP450

• Caution with polypharmacy (harder in COPD due to co-morbidity)

Discuss the use of theophylline in asthma vs COPD

• A: targets eosinophil infiltrate

• C: targets neutrophil / macrophage damage

• Same MOA, all immune cells effected in both conditions

• Clinical benefit seen from differential contribution of these cells between conditions

• Effective in both due to PD

Explain how exposure to pollutants causes the irreversible damage of COPD

• NO and superoxide inhaled

• Combine into ONOO-

• Nitrates histone deacetylase 2 at active site

• Inactivated

• Cannot deacetylate glucocorticoid receptor-alpha

• GRalpha cannot compete with NFkB for promoter region

• Greater transcription of inflammatory cytokines, especially IL-2/4/13, TNF-alpha

• Polarises Th1 response (different FC)

Describe how different aspects of the Th1 response cause the irreversible damage of COPD

• Fibroblast proliferation intercalates and replaces elastic and smooth muscle with collagen

• Thickened, fibrotic connective tissue

• Thinner smooth muscle and elastic layers

• Macrophages release TGF-beta, more fibroblast proliferation, Treg activation suppresses repair mechanisms

• Neutrophils activated, release proteases and ROS, degrades tissues

How are corticosteroids immunosuppressive, name two

• Hydrocortisone, beclomethasone

• Bind to GRalpha, releasing Hsp90

• GRalpha can homodimerize and activate/repress transcription of 1% genome

• Competes with NFkB

• Represses synthesis of pro-inflammatory cytokines involved in both Th1 and Th2

Discuss how corticosteroids can be used for asthma

• Represses synthesis of IL-4/5/13 released from Th2

• Decreases isotope switching

• Decreases anti-allergen IgE, stops increased expression of FcepsilonRI

• Beclomethasone inhaled prophylactically

• Has to be co-perscribed with b2-adr ag as not good at reversing during an attack, just preventing

What are the main problems of prescribing corticosteroids and what is done about it?

• Reduces both innate and adaptive response

• Delays wound healing

• Increased susceptibility to opportunistic infection

• Peptic ulcer risk (PG inhibition weakens stomach lining)

• Co-prescribe w/ PPIs

• Short-term only or in bridging therapy

Discuss why corticosteroids can’t be used for COPD treatment

• Resistance is “built in” to the disease

• Main target of csds is GRalpha, which is mostly in the inactive state in COPD as HDAC2 can’t deacetylate and activate it, that’s the problem

• PD problem as cannot bind effectively to the inactive GRalpha

What targetted therapy is being explored for COPD (only need one to compare with asthma)

• Increase de-acetylated HDAC2 expression

• Could prevent progression of damage

• Reverses corticosteroid resistance

What targetted therapy is available for asthma (only need one to compare to COPD)

• Omalizumab

• Humanised mAb

• Only in severe, treatment-resistant cases

• Binds IgE Fc so it cannot bidn to FcepsilonRI on mast cells

• Injection every 2-4 weeks

Where are the therapeutic benefits of theophylline seen in asthmatics?

• Mast cell stabilization

• Greater stimulus required to degranulate

Where are the therapeutic benefits of theophylline seen in COPD?

• Neutrophil stabilization

• Greater stimulus required to release proteases and ROS

Draw a labelled diagram of a COPD airway

https://ibb.co/SwftVBSb

Simply, describe how a diagram of pain transmission would be best drawn (how it was drawn in the big overview thing)

• Stimulus

• Myelinated dendritic cell labelled nociceptor

• Exocytosis of neurotransmitter

• Myelinated dendritic cell labelled spinal chord neurone

• Pain signal transmitted to and through CNS

• To brain

• Blockage by mu, kappa, delta, ORL1 receptors

Draw a diagram showing how nociceptor sensitization can increase the sensation of pain

https://ibb.co/HJkm44w

What are the four main stimuli that a nociceptor is receptive to and where do they arise from? (no explanation)

• Prostaglandins - inflammation

• H+ - acid damage / anaerobic metabolism during hypoxia

• Bradykinin - inflammation

• ATP - released from lysed cells

Besides normal neurotransmitters, what else can be exocytosed by a nociceptor during pain transmission and what are the consequences of this?

• Substance P, CGRP

• Redness and swelling

What is the synthesis pathway of prostalgandins?

• Arachidonic acid derived from membrane phospholipids

• Cyclysed, oxygenated by COX to PGG2

• Reduced by COX to PGH2

• PGE synthase to PGE2

What main PG sensitizes nociceptors?

• PGE2

Why is COX inhibition anti-inflammatory and pain relief?

• Less PGH2 to be turned to PGE2

• PGE2 potent sensitser of nociceptors

• Other PGs also involved in inflammation and swelling

How do NSAIDs block COX activity and how can this be made selective between COX-1 and COX-2?

• Block entry of arachidonic acid into catalytic site

• COX-1 channel is much narrower, so can select for 2 using bulkier/S-containing R groups that are too big to block 1

Draw a rough diagram of NSAID action on COX enzymes

https://ibb.co/HDMtC328

Name a COX-1 selective NSAID and its brief mechanism of action

• Aspirin

• Irreversible acetylation of channel into catalytic site

• Also inhibits thromboxane production for platelet lifetime (10 days) so also used fo rmigranes

Name a COX-2 selective NSAID

• Etoricoxib

What’s the main risk when using non-selective / COX-1 specific NSAIDs and what is done about it?

• Decreased PG production weakens stomach lining protection against acid and irritant foods

• Increased peptic ulcer risk

• Co-prescribe PPI

What’s the main risk when using no-selective / COX-2 selective NSAIDs and what’s done about it?

• Decreased PGI2 causes vasoconstriction

• Decreases platelet aggregation

• Increased myocardial infarction risk

• Antagonistic effect of some BP meds

Why is COX-2 selectivity desirable?

• Less inhibition of production of PGs used for gastrointestinal lining protection

• COX-1 PGs are heavily involved in this

What are the three main routes of medicating CNS transmission of pain?

• Opioids - agonise mu/delta/kappa/ORL1 receptors that block onwards pain signaling in CNS

• Gabapentin - block onward transmission of pain signal especially in pre-frontal cortex

• SNRIs / Tricyclic antidepressants - interact with sera and noradr signaling, more effective for migraine

Describe how opioid drugs are structured relative to morphine

• Analogues

• Substitution of functional groups on morphine’s three joined benzene rings

How is naloxone structured to be an antagonist of opioid recepeptors?

• Bulky substitution of the CH3 of morphine’s -N-CH3

Why is heroin so effective at causing analgesia and dependnece?

• Prodrug of morphine

• Prodrug crosses BBB more rapidly

• Deacetylated in brain

• Directs analgesia to receptors in brain, very addictive

Describe codeine as an analgesic

• More reliable oral PK than morphine

• Less analgesia

• Used in later stages of post-op care when pt is at home

• Minimum effective dose alone still has excessive side effects and risk of addiction

• Co-codamol combines with paracetemol, decreasing dose of codeine required (synergism) to decrease symptoms

Describe how opiod-agonism of mu-kappa/delta/ORL1 receptors has an analgesic effect

• Galpha-i coupled

• Dissociation

• Galpha-i subunit inhibits adenyly cyclase

• Decrease cAMP

• Counteract sensitization by nociceptors

• Betagamma subunit opens inward rectifying K+v, hyperpolarizing CNS neurones

• Increased stimulation required to transmit pain signals

How can opioids reduce the effective component of pain? What is the problem with this?

• Mu-mediated euphoria

• Can occur all over the body

• Physical dependence and tolerance

What are the risks of opioid use?

• Mu-mediated respiratory depression (and death)

• Tolerance

• Physical dependence

Give an example of an SNRI used in pain management

• Duloxetine

Give an example of a tricyclic antidepressant used in pain management?

• Amitriptyline

Describe gabapentin’s action on the brain that makes it useful as a pain medication

• Inhibition and long-term decrease in expression of L-type alpha2delta1 Ca2+v particularly at pre-frontal cortex excitatory neurones

• These Ca2+ upregulated in some neuropathic pain pts

• Less stimulation in response to incoming action potenital

• Decreased onward transmission of pain signal

What are the four main categories of drugs that target pain signalling

• NSAIDs (Block PG production, less nociceptor sensitization)

• Opioids (block pain signaling using mu/delta/kappa/ ORL1 receptors )

• Gabapentin (block pain signaling in pre-frontal cortex)

• SNRIs/tricyclics

Draw a complete diagram showing the pathogenesis of rheumatoid arthritis

https://ibb.co/jk8bP1Qc

Describe how endocytosis of joint cartilage antigens by B cells causes RA pathogenesis

• Present on MHC II to TFH cells in germinal centre

• TFH secretes IL-21, pro-proliferative for B cell

• Somatic hypermutation in germinal centre

• Clonal expansion into plasma cells

• Release Ab that bind and are cross linked by joints

• C3 and C5 bind Fc, opsonization and inflammation

• Destruction, secondary complement deficiency

Describe how endocytosis of joint cartilage antigens by DCs causes RA pathogenesis

• Present on MHC II to naieve T cell TCR

• CD80 on DC co-stimulates CD28

• Activation, polarisation to Th1 in any secondary lymphoid organ

• Th1 TCR bind cartilage antigens at joint

• Secrete IL-12, neutrophil activation, protease and ROS damage

• Secrete TNFalpha, neutrophil and macrophage activation

• Macrophages secrete IL-8, neutrophil activation and TNalpha, autocrine

Why is neutrophil activation highly inflammatory?

• Upregulation of COX-1 and 2 in surrounding synovial fluid

• Increased PGE synth, esp. PGE2

• Nociceptor sensitization

• Allodynia

What are the three main targets in RA and give two drugs for each

• COX1/2 - aspirin, etoricoxib

• GRalpha and inflammatory cytokines - hydrocortisone, becalomethasone

• DMARD - etanercept, hydroxychloroquine

What are the main ways of treating RA in terms of the disease

• Treat symptoms - NSAIDs

• Minimize damage, slight regression - Corticosteroidds

• Prevention and regression - DMARDs

Describe the action of NSAIDs for RA treatment, give examples

• Inhibit COX enzymes by binding channel entry, prevents arachidonic acid entry into AS

• Prevent cox-mediated PGH2 synthesis, which is altered further into potent sensitizer PGE2

• Less nociceptor sensitization, return to resting state, normal pain response to stimuli

• Piroxicam, aspirin, etoricoxib

Describe how COX selectivity is achieved, and give examples of drugs for each of the selectivities

• COX1 channel is much narrower

• COX2 selectivity in drugs with bulky, sulfer-containing R groups

• Non: piroxicam, COX1: aspirin (weakly) COX2: etoricoxib

What are the problems and pros with COX2 selective drugs? Give an example

• Decreased PGI2 can cause vasoconstriction and decrease platelet aggregation, increase myocardial infarction risk

• COX-1 PG’s more involved in protecting stomach lining, decrease peptic ulcer risk

• Etoricoxib

Describe the action of corticosteroids in RA treatment, give an example

• Bind GRalpha

• Release hsp90

• GRalpha homodimerizes, competes with TF NFkB

• Represses transcription of many pro-inflammatory cytokines, including IL-2 and TNF-alpha

• Less neutrophil activation, less protease ROS damage

• Hydrocortisone - also inhibits PG synth by limiting arachidonic acid release from membrane lipids

What should be considered when treating RA with corticosteroids?

• Suppression of both innate and adaptive immunity

• Increases wound healing time (careful when also on anti-thrombotic e.g. aspirin)

• Increase risk of opportunistic infection

• PG inhibition increases peptic ulcer risk (Co persc. w/ PPIs)

Describe Etanercept as an RA treatment

• Anti-TNFalpha

• Biologic: fusion protein of TNFalphaR and IgGFc

• Binds endogenous TNFalpha before it can bind and activate macrophages (and therefore neutrophils)

• Reserved for severe, treatment resistant as very expensive and needs IV/SC admin

Describe the consequences of Etanercept treatment for RA

• Both admin and macrophage suppression increase chance of infection

• Can cause bone marrow suppression

• Multiple cases of MS

Describe Hydroxychloroquine as a treatment for RA

• Lipophillic, accumulates in macrophage vesicles

• Increases pH

• Decreases lysozyme / enzymatic activity

• Peptides cannot be processed in macrophages for MHC presentation

• SOSA (from anti-malarial chloroquine)