2.07 - Rheumatoid Arthritis [Still Need Learning Topics]

Front 1

Contrast central and peripheral tolerance.

Back 1

CENTRAL
deletion of auto-reactive lymphocutes in primary lymphoid organs

PERIPHERAL
control of T/B cell activation in secondary lymphoid organs
[T cells need co-stimulation, B cells need T cell help]

Front 2

How would a T cell see non-thymic antigens whilst still in the thymus?

Back 2

AIRE

Front 3

What is involved in peripheral activation of T cells?

Back 3

1. Ag recognition
2. Co-stimulation (CD80, CD86 on DC binds CD28 on T cell)

Front 4

How do T cells develop in the thymus?

Back 4

IN THE CORTEX:
1. Lymphocyte pre-cursor undergoes TcR-rearrangement
2. Double positive T cell exposed to APC (i.e. MHC)
3. Positive selection if recognise MHC to become single positive T cell (i.e. CD4+ or CD8+)

MEDULLA
4. Negative selection of single-positive T cells (those that recognise self-peptide are killed)

Front 5

If a CD8+ T cell solely recognises MHC class I, what will happen to it?

Back 5

No co-stimulation means that the cell will undergo ANERGY.
[this needs to happen because MHC-I is expressed on all cells, constantly displaying self-peptide]

This is an example of peripheral tolerance

Front 6

What is the role of a regulatory T cell?

Back 6

T regs inhibit auto-reactive T cells.
CD25+ CD4+
Recognise self-peptide and inhibit proliferation of disease-causing activated T cells

Develop in thymus or during induction of immune responses in peripheral lymphoid organs

Front 7

What do T regs express?

Back 7

Foxp3 = Transcription factor

Front 8

What inhibitory cytokines do T regs produce?

Back 8

IL-10
TGF-beta

Front 9

T/F: Everyone acquires autoimmune antibodies as they age

Back 9

TRUE!
But they don't always cause disease (low affinity, not pathogenic, IgM, etc)

Front 10

What "T cell help" does a B cell require to be activated?

Back 10

IL-4
CD40L from T cell (binds CD40 on B cell)

Front 11

How do B cells present to T cells for help? Then what happens?

Back 11

B cell = APC.

1. B cell takes up antigen (binds BCR)
2. Antigen processed (phagolysosomal pathway) and loaded onto MHC Class II
3. B cell presents to T cell
4. T cell provides help (cytokines, CD40L)
5. B cells class switch (higher affinity now)
6. Plasma cells become long lived

Front 12

What controls T cell expansion?

Back 12

Fas-FasL

Front 13

What are the features of autoimmunity?

Back 13

Precipitated by interaction of environmental factors (eg infections) with genetically susceptible host
Occurs mainly in secondary lymphoid tissue
Female predominance
Chronic fluttering course (relapse/remission)
Occurance with other autoimmune diseases
Lymphoid cell infiltration of tissues
Presence of autoantibodies
Response to anti-inflam/immunosuppressive drugs

Front 14

What genes are associated with rheumatoid arthritis?

Back 14

HLA-DRB1 locus
PTPN22 (normally turns off signalling in T cell and macrophages)

Other possible genes = CTLA4, IL-2ReceptorA, genes in the TNF signalling pathway

Front 15

What is the incidence in autoimmune diseases in identical twins?

Back 15

Less than 50%
-->ENVIRONMENTAL FACTORS!!!

Front 16

What is associated with developing anti-cyclic citrullineated peptide (CCP) in RA?

Back 16

Smoking

Front 17

Organ specific autoimmune diseases are in which "cluster"?

Back 17

Thryo-gastric cluster

Front 18

Non-organ specific autoimmune diseases are in which "cluster"?

Back 18

Systemic or Lupus cluster

Front 19

What autoantibodies are found in connective tissue disease?

Back 19

1. Anti-CCP [anti-cyclic citrullinated peptide]

2. ANA [anti-nuclear antibody]
-->to various components of the nucleus e.g. anti dsDNA antibody

3. ACA [anti-cardiolipin antibody, or anti-phospholipid antibody]

4. Rheumatoid factor [IgM anti-IgG antibody]

Front 20

What is SLE?

Back 20

Lupus
Ag = dsDNA
Immune complex driven process
[Immune complexes precipitate in various sites in body - complement activated - C3a inflammation]

Front 21

Outline stages of pathogenesis of autoimmune disease (using RA as example)

Back 21

1. INDUCTION
-->DCs in synovium undergo maturation, migrate to lymph nodes and pick up self-peptide
-->Activate CD4+ T cells and then migrate back to tissues

2. PERPETUATION
-->Activated CD4+ T cells release cytokines causing inflammation
-->Activated CD4+ T cells help B cells to produce Abs e.g. RF, ANA

3. CHRONIC FLUCTUATING PHASE
-->Tissue damaged by inflammation
-->Dysregulation involving multiple cells, local upregulation of MHC-II causing more damage
-->Spreading of autoimmune response, self-reactivity spreads to more antigens

Front 22

What do synovial inflammatory cells release in rheumatoid arthritis ?
Which plays a central role in the inflammatory response

Back 22

TNF, IL-1, IL-6, IL-12, + others

[TNF plays central role]

Front 23

What are the principles of diagnosis of an autoimmune disease?

Back 23

1. Confirm presence of disease
2. Categorise disease
3. Determine extent
4. Determine severity

Front 24

What are the principles of therapy for autoimmune disease

Back 24

1. Determine extent
2. Anti-inflammatory drugs for mild/moderate disease
3. Immunosuppressants for severe disease
4. Replacement when target tissue destroyed
5. Removal of unwanted autoantibodies/immune compexes (plasmapheresis)
6. Selective inhibition

Front 25

What percentage of NSAIDs are albumin bound?
What does this mean?

Back 25

95%
-->small vol distribution

Front 26

What are some side effects of NSAIDs?

Back 26

Front 27

What is the MOA of NSAIDs?

Back 27

Inhibit COX (cyclooxygenase), thus inhibiting the production of pro-inflammatory prostaglandins

Front 28

What are the pharmacological properties of NSAIDs

Back 28

Anti-inflammatory
Analgesic
Anti-pyretic
Anti-platelet

Front 29

What are some normal physiological roles of prostaglandins?

Back 29

COX-1 --> PGE2 and PGI2 are present in the gastric mucosa (give protection)

PGH2 used to produce Thromboxane A2 (aggregates platelets)

Prostaglandins maintain normal renal perfusion

Front 30

What is the role of COX-1?

Back 30

Produces prostanoids that mediate physiological role in:

Gastric mucosa
Small/large bowel
Kidney
Platelets
Endothelial cells

Front 31

Where is COX-2 expressed?

Back 31

Constitutively expressed in brain and kidney, but induced at sites of inflammation [produces prostanoids that mediate inflammation, pain and fever]

Front 32

T/F: Cox-2 inhibitors and traditional NSAIDs have similar effects in the kidney

Back 32

TRUE

Front 33

Which inhibitor would spare platelet aggregation?
COX-2
COX-1

Back 33

COX-2 inhibitor (because platelets contain COX-1)

Front 34

T/F: COX-2 inhibitors have reduced efficacy

Back 34

FALSE.
The efficacy of COX-2 inhibitors is essentially the same as that of regular NSAIDs

Front 35

Why is there an increased cardiovascular risk with COX-2 inhibitors in patients with atherosclerosis?

Back 35

Platelets produce pro-aggregatory TxA2 (because they contain COX-1)

In atherosclerosis, the plaque induces COX-2 (recall induced during inflammation) which synthesises PGI2 (anti-aggregatory).

If give selective COX-2 inhibitor, going to inhibit PGI2 production, but not the TxA2 production --> PRO-AGGREGATION (i.e. clotting)

[Typical NSAIDs inhibit both PGI2 and TxA2 synthesis]

Front 36

When are corticosteroids clinically indicated

Back 36

Inflammatory disorders (SLE, RA, sarcoidosis etc)
Skin conditions (mainly topical application)
Asthma - underlying inflammation
Immunosuppression (s.a. for organ transplantation)

Front 37

What are the two major groups of corticosteroids and what are their roles?

Back 37

1. MINERALOCORTICOIDS
(aldosterone)
--> maintain electrolyte and water balance (conserve Na, waste K)

2. GLUCOCORTICOIDS
(cortisol)
-->anti-inflammatory
-->glucose, protein, fat metabolism (incr. free glucose, break down protein)

Front 38

Dexamethasone has __ times more glucocorticoid activity than cortisol

Back 38

30

Front 39

what are the 4 processes identified as the basis for anti-inflammatory activity of glucocorticoids?

Back 39

1. TRANSACTIVATION
synthesis of anti-inflammatory proteins

2. TRANSREPRESSION
Switch off inflammatory genes

3. POST-GENOMIC EFFECTS
destabilise pro-inflammatory mRNA

4. ACTIVATION OF HDACs
[histone de-acetylases]
wind up DNA so can't read it

Front 40

How do glucocorticoids mediate transactivation?

Back 40

1. GC travels in plasma bound to cortisol binding protein
2. GC crosses membrane and knocks off heat shock proteins keeping its receptor inactive
3. Active GC-GCR complex goes into nucleus and binds glucocorticoid response element (GRE) on DNA
4. Transcription of mRNA
5. Translation of mRNA into anti-inflammatory proteins (such as annexin-1 which inhibits phospholipase A2)

Front 41

Why may giving corticosteroids cause a better response to beta-agonists in asthma?

Back 41

Glucocorticoids cause translation of proteins that are very similar to beta-receptors in airway smooth muscle. Give asthma a beta-agonist -> will bind to these proteins -> better response because more beta-receptors in ASM

Front 42

Histone acetylation allows what?

Back 42

Unwinding and thus reading of DNA

Front 43

How do glucocorticoids mediate transrepression?

Back 43

Aim of transrepression = to switch OFF inflammatory genes.

NF-KB is a pro-inflammatory TF that has intrinsic histone acetylation property (to unwind and read DNA).
Corticosteroid-R complex can bind NF-KB, inhibiting its histone acetylation activity

End result = repress the reading of genes that would have led to production of pro-inflammatory proteins

Front 44

How do glucocorticoids mediate post-genomic effects?

Back 44

Corticosteroids inhibit stabilising proteins that would otherwise protect pro-inflammatory mRNA

Front 45

How do glucocorticoids mediate histone de-acetylation?

Back 45

Acetylation of histones causes unwinding of DNA allowing gene transcription and synthesis (of pro-inflammatory proteins)

Histone deacetylases (HDACs) deacetylate acetylated histones -> the DNA remains wound -> GENE SILENCING

The GR complex (active receptor + steroid) facilitates the activity of HDACs

Front 46

What is the preferred agent for long term corticosteroid therapy?

Back 46

Prednisone - once/day

Front 47

How does changing the dose of prednisone change its activity?

Back 47

Low dose = physiological
Medium dose = anti-inflammatory
High dose = immunosuppressive

Front 48

T/F: Side effects are reversible on cessation of corticosteroid treatment

Back 48

TRUE

Front 49

What are some SHORT TERM side effects of taking high dose prednisone?

Back 49

Weight gain
Mood changes
Incr. blood glucose
Hypokalemia
Transitory HPA axis suppression

Front 50

what are some LONG TERM effects of taking corticosteroids?

Back 50

Oedema/weight gain
Infection (immunosuppressed)
Osteoporosis
Incr. blood glucose
Muscle wasting
Thin skin

Front 51

How can corticosteroids cause osteoporosis??

Back 51

Cause protein breakdown
Incr. urinary calcium losses
Inhibit gut Ca absorption
HPA axis suppression -> decr. sex steroids

Front 52

Why is there HPA axis suppression with use of corticosteroids ?

Back 52

High dose of corticosteroid - feedback inhibition - reduce production of cortisol.

Long term use can completely shut down endogenous cortisol production

Front 53

Excess corticosteroid can lead to what?

Back 53

Cushing's syndrome.

Front 54

What characterises Cushing's syndrome?

Back 54

Moonface – redistribution of fat
Easy bruising – protein disappears from skin, blood vessels aren’t very well supported [trivial trauma → vessels rupture]
Trunk obesity – redistribution of fat
Striae/stretch marks – abdominal wall expands, skin is thin, blood vessels rupture
Thin limbs – muscle wasting
Poor healing – immunosuppression
Buffalo hump – redistribution of fat above cervical spine
Osteoporosis
↑ BP due to Na retention
Thin skin – loss of skin protein

Front 55

Give two examples of using recombinant proteins as drugs.

Back 55

Can use recombinant DNA technology to make proteins directed against other proteins (i.e. antibodies or receptors).

1. Anti-TNF-alpha antibodies can be made and used in RA. These antibodies bind TNF-alpha before it reaches the cell membrane

2. Soluble receptors can be synthesised (e.g. TNF-alpha binds to the receptor thinking it's found the cell, but ends up floating around in the ECF)

Front 56

What is TNF-alpha's role in the inflammatory response?

Back 56

Induces pro-inflammatory cytokines (such as IL-1)

Increases adhesion molecules on epithelial cells

Activates neutophils and eosinophils

Front 57

What are the criteria for diagnosing RA?

Back 57

AT LEAST FOUR OF THE FOLLOWING:

1.Morning stiffness > 1hr [6+ wks}
2.Arthritis of ≥ 3 joints [6+ wks}
3.Arthritis of hand joints [6+ wks}
4.Symmetrical arthritis [6+ wks}
5.Rheumatoid nodules
6.Serum rheumatoid factor
7.Typical radiographic changes

Front 58

What is the epidemiology of RA?

Back 58

1% of world’s population

3-5x more common in women

50% slow onset, 25% acute onset

Both local and systemic disease

MTDx (mean time to diagnosis) = 9 months

Front 59

What are some proposed causes of RA?

Back 59

Triggered by exposure of a genetically suscepible host to an antigen which causes a breakdown in self-tolerance.

Infectious agent in synovium? Continued presence of super antigen? Altered T cell repertoire? Decr. T regs?

Front 60

What ultimately destroys the joint in RA?

Back 60

The CD4+ T cell activation, and local release of inflammatory mediators/cytokines

Front 61

What cells are in the synovial membrane?

Back 61

Type A synoviocytes (equivalent to macrophages)

Type B synoviocytes (equivalent to fibroblasts - produce synovial fluid)

Front 62

How thick is the synovial lining?

Back 62

One cell

Front 63

What are the characteristic histological features of ACUTE RA?

Back 63

1. Increased vascular flow
2. Aggregation of organising fibrin (can float in joint space = rice body)
3. Endothelial activation so cells can migrate into tissue
4. vascular proliferation (HEV, angiogenesis)
5. Replication Type B synoviocytes
6. Recruit type A synoviocytes (recall like macrophages)
7. Type A and Type B FUSE --> GIANT CELL
8. Pannus formation (cells are proliferating with nowhere to go so they protrude into the synovial space)

Front 64

Which immune response elements are present in the acute response to RA?

Back 64

Innate = synovial fluid neutrophils, NK cells, macrophages

Adaptive = B1 cells, CD4+ T cells,

Soluble recruitment factors

Front 65

What CHRONIC changes are seen in RA?

Back 65

1. Recruitment (macrophages, neutrophils, T/B cells)

2. Remodelling (inflammatory process has done a lot of damage via MMPs, macrophages, ROS, NO .. have TIMPs.

3. Decr. apoptosis of synoviocytes (anti-apoptotic factors s.a. bcl-2)

4. Hypoxia induced proliferation

5. Synoviocyte fusion

6. Pannus formation

7. Cartilage/bone erosion (juxta-articular erosion, subchondral cysts, osteoporosis)

Front 66

What radiological features would you see in RA?

Back 66

Joint narrowing
Erosions adjacent to cartilage
Osteopaenia

Front 67

What is the 'pannus' ?

Back 67

Pannus = mass of synovium stroma consisting of inflammatory cells, granulation tissue and synovial fibroblasts which grows over the articular cartilage and causes its erosion.

Front 68

What is within the 'pannus' ?

Back 68

Hypoxia in Type B synoviocytes --> Incr. HIF-alpha --> makes VEGF --> poorly ordered angiogenesis

Have HEV instead of normal BVs

Type A synoviocytes producing IL-1, IL-6, TNF-a, IL-17, IL-23

Type B synoviocytes producing M-CSF, TNF, IL-17, TGF-b

MMPs

DCs (Continuous antigen)

B cells -> Abs -> immune complexes (i.e. RF)

Front 69

What are some genetic polymoprhisms associated with RA?

Back 69

- Genetic susceptibility clearly major contributor to pathogenesis of RA
- Class II MHC – Specific HLA-DRB1 alleles have been shown to be associated with RA
- Class II MHC-linked – TNF-α, heat shock protein-70
- Hormone-related genes – prolactin, oestrogen, …
- Lymphocyte-associated genes
- Cytokines and cytokine receptors

Front 70

What is the function of synovial fluid?

Back 70

Efficient lubricant
Vehicle for nutrients and oxygen to articular cartilage

Front 71

What is the function of articular cartilage?

Back 71

Shock absorber
Smooth, friction-free surface

Front 72

Why is there an irregular junction between cartilage and subchondral bone?

Back 72

To resist shearing forces

Front 73

What do the ligaments and joint capsule consist of?

Back 73

Dense, collagenous connective tissue.
--> strong and stable junction between bones

Front 74

What is in the matrix of articular cartilage?

Back 74

Hydrophilic glucosaminoglycans trapped in inextensible collagen fibril framework

Front 75

T/F: articular cartilage lacks a periosteum

Back 75

FALSE. lacks a perichondrium.
o Develops within a continuous tube of developing collagenous connective tissue that becomes periosteum over the surfaces of the adjacent bones

Front 76

Define the immune response in RA in a sentence.

Back 76

T cell driven initiation followed by macrophage dominated perpetuation and joint destruction