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Yr 2 - GI & Metabolism > Inflammatory Bowel Disease > Flashcards

Inflammatory Bowel Disease Flashcards

1
Q

What is the innate immune system?

A

First response to infection

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2
Q

What are the 3 main components of the innate immune system?

A
  1. Toxic/inhibitory substances
  2. Complement system
  3. The cells that make up the innate part
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3
Q

What are examples of toxic/inhibitory substances?

A
  • Enzymes e.g. lysozymes in tears

- C-reactive protein (CRP)

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4
Q

What does CRP do?

A

Enhances phagocytosis and complement binding

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5
Q

What is the complement cascade?

A

A series of proteins in blood which, when activated, promote inflammation, opsonisation and lysis of pathogens

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6
Q

What are the cellular components of the innate immune system?

A
  1. Phagocytes (neutrophils, monocytes/macrophages, dendritic cells, eosinophils)
  2. Mast cells & basophils (release mediators (e.g. histamine when activated)
  3. Natural killer cells
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7
Q

Why is the innate immune system insufficient protection?

A

Rapid response
BUT

  • No memory formation
  • Recognises limited numbers of sites on foreign organisms
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8
Q

Where are B cells produced/matured?

A

Produced and matures in bone marrow

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9
Q

What is life cycle of B cells?

A

Produced throughout life, survive only a few days

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10
Q

How do B cells work?

A
  • Have antibodies on their surface which act as antigen receptors
  • When activated proliferate and differentiate into plasma cells producing specific antibody
  • Memory cells formed
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11
Q

Where are T cells produced/matured?

A

Produced in bone marrow and matures in thymus

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12
Q

What is life cycle of T cells?

A

Most produced before puberty, so long-lived

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13
Q

How do T cells work?

A

Have T cell receptors with variable regions which recognise presented antigens

Memory cells are formed

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14
Q

What are the different types of T cells?

A

Distinguished by proteins expressed on surface:

  • CD4+ (Helper T cells)
  • CD8+ (cytotoxic T cells)

Also regulatory T cells (Treg)

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15
Q

How do B and T cells interact?

A
  1. Activated B cell engulfs and digests antigen
  2. B cell displays antigen fragments bound to its unique MHC molecules
  3. Combination of antigen and MHC attracts matching T cell
  4. Cytokines secreted by T cell help B cell to multiply and mature into antibody producing plasma cells
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16
Q

What is MHC?

A

Major Histocompatibility Complex is a region on chromosome 6 coding for proteins involved in immune function

Includes genes for proteins on cell surfaces which have a cleft that holds a small peptide derived from proteins within the cell (HLA)

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17
Q

Where is MHC class I found?

A

On all nucleated cells

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18
Q

What does MHC I display in healthy cells?

A

display fragments of normal intracellular proteins

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19
Q

What does MHC I display in infected cells?

A

display fragments of bacterial or viral protein

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20
Q

Where is MHC class II found?

A

Found on antigen presenting cells (APCs) – macrophages, dendritic cells, B-lymphocytes

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21
Q

What does MHC II display?

A

fragments of internalised antigens

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22
Q

What does CD4 facilitate the binding of?

A

T helper cells to MHC II

23
Q

What does CD8 facilitate the binding of?

A

Cytotoxic T cells to MHC I

24
Q

What are the 3 different types of T helper cells (CD4+ lymphocytes)?

A
  1. Th1
  2. Th2
  3. Th17
25
Q

What is role of Th1?

A

Promote inflammation, stimulate phagocytosis by activating macrophages. Predominantly involved in responses to microbial pathogens

26
Q

What is role of Th2?

A

Promote strong antibody production, particularly IgE. Predominantly involved in responses to parasites, and atopic (allergic) responses

27
Q

What is role of Th17?

A

Not fully understood. Have important roles in intestinal lamina propria, may be implicated in inflammatory bowel disease

28
Q

What are the 3 parts associated with the mucosal immune system?

A
  1. Gut Associated Lymphoid Tissue (GALT)
  2. Intraepithelial lymphocytes
  3. Lamina propria lymphocytes
29
Q

What does GALT include?

A
  • Tonsils
  • Adenoids
  • Peyer’s patches
  • Appendix
30
Q

What does GALT contain?

A

Contain B and T lymphocytes, macrophages and dendritic cells

31
Q

What are intraepithelial lymphocytes?

A

Interspersed amongst epithelial cells – mainly CD8+ T cells

32
Q

What are lamina propria lymphocytes?

A

CD4+ (helper) T cells, B lymphocytes, mast cells

33
Q

What does ulcerative colitis affect?

A

Only affects the mucosa in the colon/rectum (bottom of GI tract) –> inflammation starts at rectum

Continuous areas of inflammation

34
Q

What does Crohn’s disease affect?

A

Anywhere in the GI tract

Inflammation extends through the full thickness of the bowel wall

Patchy “cobblestone” appearance

35
Q

What does ulcerative colitis lead to?

A
  • Mucosal/submucosal inflammation
  • Crypt abscesses, loss of goblet cells
  • Colonic dilatation
36
Q

What does Crohn’s disease lead to?

A
  • Transmural inflammation
  • Granulomas – spherical areas formed during chronic inflammation if non-degradable foreign matter or persistent presence of pathogens
  • Fistulas
37
Q

What are the 2 main types of inflammatory bowel disease?

A
  1. Crohn’s disease

2. Ulcerative colitis

38
Q

What is IBD thought to be triggered by?

A

Inappropriate response to stimuli in genetically susceptible individuals (genes, environment, gut microbiota)

39
Q

How does smoking affect Crohn’s disease/ulcerative colitis?

A

Smoking worsens / smoking may improve condition

40
Q

Is there a surgical cure for Crohn’s disease/ulcerative colitis?

A

No (as affect whole GI tract) / yes

41
Q

Difference between symptoms and signs?

A

Symptoms - volunteered by patients

Signs - observed by doctor

42
Q

Common symptoms of IBD?

A
  • Diarrhoea
  • Rectal bleeding and mucus
  • Faecal urgency/incontinence
  • Abdominal and perianal pain
  • Weight loss
  • Fatigue/lethargy
  • Mouth ulcers
43
Q

Common signs of IBD?

A
  • Abdominal tenderness
  • Mass on palpation
  • Anaemia
  • Fistulae (not in ulcerative colitis)
  • Perianal abscess (not in ulcerative colitis)
44
Q

What is IBD?

A

Chronic relapsing and remitting inflammatory disorders of unknown aetiology

Caused by Failure to maintain oral tolerance (suppression of immune response to antigens consumed orally)

45
Q

Describe intestinal homeostasis dynamic in normal people?

A

Normal interaction between invasive organisms and harmless antigens (e.g. food, proteins and commensal bacteria)

46
Q

Describe intestinal dynamic in IBD?

A
  • Ag activation of innate immune cells
  • Adaptive immune response maintains inflammatory response with abnormally activated CD4+ Th cells releasing pro-inflammatory mediators leading to chronic tissue damage (sensitive to own gut bacterial antigens)
47
Q

What response is CD/UC more associated with?

A

CD - Th1 response

UC - Th2 response

48
Q

Mutations in what genes are associated with increased susceptibility to Crohn’s?

A

Genes NOD2 –> involved in intracellular processing of bacterial antigens

49
Q

What can polymorphisms in IL–23R lead to?

A

Increased susceptibility (CD and UC)

50
Q

What is IL-23R produced by and involved in?

A

IL-23 produced by dendritic cells and involved in regulation of Th-1 and Th-17 cell differentiation and regulation of chronic inflammation

51
Q

What is a panproctocolectomy?

A

The removal of the entire colon, rectum and anal canal.

52
Q

What is transmural?

A

Occurs across entire wall of a vessel/ organ

53
Q

What is ulcerative colitis?

A

UC is a form of colitis (i.e. inflammation of the colon) that includes characteristic ulcers (visible in scans)

54
Q

Why are steroids only used as short term medication for IBD?

A

not long term as cause other complication e.g. hypertension, diabetes

Yr 2 - GI & Metabolism (51 decks)

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