Immuno: Autoinflammatory and Autoimmune diseases 1 Flashcards

1
Q

What is the difference between autoinflammatory and autoimmune disease?

A

Autoinflammatory = driven by components of the innate immune system

Not characterised by autoantibodies and HLA associations are usually less strong

Autoimmune = driven by components of the adaptive immune system

Autoantibodies are found and HLA associations are common

Note: mixed pattern diseases involve mutations affecting the innate and adaptive immune system → HLA associations may be present but autoantibodies are NOT usually a feature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which cells are mainly responsible for:

  1. Autoinflammatory diseases
  2. Autoimmune diseases
A
  1. Autoinflammatory diseases = macrophages and neutrophils (disease is usually localised)
  2. Autoimmune diseases = T and B cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

List examples of monogenic autoinflammatory diseases

A

Familial Mediterranean Fever

TRAPS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

List examples of polygenic autoinflammatory diseases

A

Crohn’s

UC

Osteoarthritis

Giant cell arteritis

Takayasu’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

List examples of monogenic autoimmune diseases

A

APECED

IPEX

ALPS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

List examples of polygenic autoimmune diseases

A

Rheumatoid arthritis

Myasthenia

Pernicious anaemia

Graves disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

List examples of mixed pattern diseases

A

Ankylosing spondylitis

Psoriatic arthritis

Behcet’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Mutations in which pathways are implicated in monogenic autoinflammatory disease?

A

Innate immune cell function - abnormal signalling via key cytokine pathways involving TNF-alpha or IL-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which protein is upregulated in autoinflammatory diseases caused by gain-of-function mutation in NLRP3?

A

Cryopyrin (NALP3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Name 3 diseases that are caused by mutation of NLRP3?

A
  • Muckle Wells syndrome
  • Familial cold autoinflammatory syndrome
  • Chronic infantile neurological cutaneous articular syndrome
  • These are all autosomal dominant

NOTE: other examples of monogenic autoinflammatory conditions: TNF receptor associated periodic syndrome (TNF receptor mutation), Hyper IgD with periodic fever syndrome (mevalonate kinase mutation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which gene mutation causes Familial Mediterranean Fever and which protein does this gene encode?

A

MEFV gene

Encodes pyrin-marenostrin which is ordinarily a negative regulator of the inflammatory pathway → mutation leads to increased inflammation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe how the inflammasome complex functions.

A
  1. The pathway is activated by toxins, pathogens and urate crystals
  2. These act via cyropyrin and ASC (apoptosis-associated speck-like protein) to activate procaspin 1
  3. Activation of procaspin 1 results in the production of NFkB, IL-1 and apoptosis
  4. Pyrin-maronestrin is a negative regulator of this pathway
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which mutations can lead to hyperactivity of the inflammasome complex?

A
  • Loss of function of pryin-marenostrin
  • Gain of functiion of cryopyrin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the inheritance pattern of Familial Mediterranean Fever?

A

Autosomal recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which cells contain pyrin-maronestrin?

A

Neutrophils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Outline the clinical presentation of Familial Mediterranean Fever.

A

Periodic fevers lasting 2-4 days associated with:

  • Abdominal pain (peritonitis)
  • Chest pain (pleurisy, pericarditis)
  • Arthritis
  • Rash
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a complication of Familial Mediterranean Fever?

A

AA amyloidosis (due to chronic elevation of serum amyloid A)

This can deposit in the kidneys causing nephrotic syndome and renal failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Outline the treatment of Familial Mediterranean Fever.

A
  • Colchicine 500µg BD (binds to tubulin and disrupts neutrophil migration and chemokine secretion)
  • 2nd line: blocking cytokines
    • Anakinra - IL-1 receptor blocker
    • Etanercept - TNF-alpha blocker
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are three types of pathogenesis in monogenic autoimmune diseases?

A
  • Abnormality in tolerance
  • Abnormality in regulatory T cells
  • Abnormality of lymphocyte apoptosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does APECED stand for?

A

Autoimmune polyendorcinopathy candidiasis ectodermal dystrophy

NOTE: it is autosomal recessive

21
Q

What mutation causes APECED? What is the role of this gene?

A

AIRE - this is a transcription factor that is responsible for the expression of self-antigens in the thymus and promotes apoptosis of self-reactive T cells. Defects in AIRE leads to a failure of central tolerance and the release of auto-reactive T cells.

22
Q

Which autoimmune conditions tend to occur in APECED?

A
  • Hypoparathyroidism (COMMON)
  • Addison’s disease (COMMON)
  • Hypothyroidism
  • Diabetes mellitus
  • Vitiligo
23
Q

Why are patients with APECED prone to Candida infection?

A

They produce antibodies against IL-17 and IL-22

24
Q

What does IPEX stand for?

A

Immune dysregulation polyendocrinopathy enteropathy X-linked syndrome

25
What mutation causes IPEX? What is the role of this gene?
FoxP3 - required for the development of Treg cells A lack of Tregs leads to autoantibody formation
26
Which autoimmune conditions are often seen in IPEX?
* Enteropathy * Diabetes mellitus * Hypothyroidism * Dermatitis
27
What does ALPS stand for?
Autoimmune lymphoproliferative syndrome
28
Which mutations cause ALPS?
Mutations in the **FAS pathway** leading to **defects in apoptosis** of lymphocytes This leads to a failure of lymphocyte tolerance (as autoreactive lymphocytes don't die by apoptosis) and failure of lymphocyte homeostasis (you keep producing lymphocytes)
29
Describe the clinical phenotype of ALPS.
* High lymphocyte count * Large spleen and lymph nodes * Autoimmune disease (usually cytopaenias) * Lymphoma
30
What is the best known chromosomal region that is implicated in Crohn's disease?
IBD1 on chromosome 16
31
Which gene within the specific chromosome region is associated with Crohn's disease?
NOD2 (aka CARD15) Abnormalities are associated with increased risk of Crohn's, Blau syndrome and some forms of sarcoidosis
32
Where is NOD2 found and what is its role?
Cytoplasm of myeloid cells Acts as a microbial sensor (recognises muramyl dipeptide)
33
Outline the treatment approaches to Crohn's disease
* Corticosteroids * Azathioprine * Anti-TNF-alpha antibodies * Anti-IL 12/23 antibodies
34
What is the strongest genetic association of ankylosing spondylitis?
HLA-B27 NOTE: othes include IL23R, ERAP1, ANTXR2 and ILR2
35
Where does ankylosing spondylitis tend to manifest?
At sites with high shear forces (i.e. entheses- tendons/ligaments insert into bone)
36
What are the treatment options for ankylosing spondylitis?
* NSAIDs * Immunosuppression (anti-TNF-alpha and anti-IL17)
37
List the autoimmune diseases associated with the following HLA polymorphisms: 1. DR3 2. DR3/4 3. DR4 4. DR15
1. DR3 * Graves' disease * SLE 2. DR3/4 * Type 1 diabetes mellitus 3. DR4 * Rheumatoid arthritis 4. DR15 * Goodpasture's syndrome
38
Name and state the function of 2 genes that are involved in T cell activation and are often mutated in polygenic autoimmune disease.
* PTPN22 - suppresses T cell activation * CTLA4 - regulates T cell function (expressed by T cells)
39
What are three forms of peripheral tolerance?
* T cell require costimulation to become activated (costimulatory molecules are upregulated in infection and inflammation) * Regulatory T cells * Immune privileged sites - not affected much by immune response, protects vital organs e.g. eyes, brain
40
Outline the Gel and Coombs effector mechanisms of immunopathology.
Type I: Anaphylactic hypersensitivity - immediate hypersensitivity which is IgE-mediated Type II: antibody mediated cytotoxic hypersensitivity - antibody reacts with cellular antigen Type III: Immune complex hypersensitivity - antibody reacts with soluble antigen to form an immune complex which is then deposited in tissues Type IV: Delayed-type hypersensitivity - T cell mediated response NOTE: autoimmunity is most common with type II hypersensitivity
41
List some inflammatory mediates involved in type I responses that are: 1. Pre-formed 2. Synthesised
1. Pre-formed: Histamine, Serotonin, Proteases (cause immediate symptoms e.g. bronchoconstriction 2. Synthesised: Leukotrienes, prostaglandins, bradykinin, cytokines (slightly later e.g. vasodilation)
42
Outline the pathophysiology of IgE-mediated type I responses.
IgE binds to a foreign antigen (e.g. pollen) The Fc portion binds to mast cells and basophils Exposure to allergen leads to cross-linking and leading to degranulation NOTE: this mechanism is implicated in eczema
43
How does antibodies binding to cellular antigens lead to cell death?
Antibody-dependent cellular cytotoxicity: antibodies can activate complement (by binding to C1) or bind to NK cells and macrophages resulting in phagocytosis
44
What is sometimes considered a type V hypersensitivity reaction?
Antibodies activate or block cellular receptors (e.g. Graves' disease, myasthenia gravis)
45
Name the autoantigen in the following diseases: 1. Goodpasture's disease 2. Pemphigus vulgaris 3. Graves' disease 4. Myasthennia gravis
1. Goodpasture's disease = non-collagenous domain of basement membrane collagen IV 2. Pemphigus vulgaris = Epidermal cadherin 3. Graves' disease = TSH receptor 4. Myasthenia gravis = nicotinic acetylcholine receptor
46
What are the consequences of immune complex formation in type III hypersensitivity reactions?
Immune complexes can deposit in blood vessels (especially in the kidneys, joints and skin) They activate complement and inflammatory cells through their Fc portion
47
What is the autoantigen in: 1. SLE 2. Rheumatoid arthritis
* SLE: DNA, histones, RNP * Rheumatoid arthritis: Fc portion of IgG
48
Give some examples of type IV hypersensitivity mediated diseases and state the autoantigen involved.
* Insulin-dependent diabetes mellitus: pancreatic beta-cell antigen * Multiple sclerosis: myelin basic protein, proteolipid protein, myelin oligodendrocyte glycoprotein