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I&I WC1 > Organ-specific immunity: GUT - Disease > Flashcards

Organ-specific immunity: GUT - Disease Flashcards

This deck contains the lectures about IBD and coeliac disease

1
Q

What is dysbiosis?

A

Big shifts in microbiota occurring in individuals

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2
Q

Which factors contribute to dysbiosis? (4)

A
  • Host genetics
  • Lifestyle
  • Early colonization
  • Medical practices
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3
Q

Name examples of host genetics in dysbiosis

A

Mutations in NOD2, IL23R, ATG16 and IGRM

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4
Q

Name examples of lifestyle in dysbiosis (2)

A
  • Diet
  • Stress
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5
Q

Name an example of early colonization in dysbiosis

A

Birth in hospital leading to altered exposure to microbes

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6
Q

Name examples of medical practices in dysbiosis

A
  • Vaccination use
  • Antibiotic
  • Hygiene
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7
Q

How can dysbiosis affect disease? (2)

A
  • Upregulation of pro-inflammatory Th subsets (Th1, Th2, Th17)
  • Reduced regulatory T cells (reduced regulation)
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8
Q

What is the paradigm in IBD?

A

There is dysbiosis leading to severe immune disease

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9
Q

What does inflammatory bowel disease result from?

A

An inappropriate inflammatory response to intestinal microbes in a genetically susceptible host

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10
Q

What does ‘inappropriate’ mean in the definition of IBD?

A

Deregulated immune responses

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11
Q

What does ‘intestinal microbes’ mean in the definition of IBD?

A

Commensals

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12
Q

What does ‘genetically susceptible host’ mean in the definition of IBD?

A

Individual genetic variation. There has to be a specific genetic predisposition that is different in individuals that develop IBD

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13
Q

What are the two major clinical forms of IBD?

A
  • Crohn’s disease
  • Ulcerative colitis
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14
Q

What can be said about the pattern of inflammation in Crohn’s disease?

A
  • Patchy inflammation
  • Can affect every part of the GI-tract
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15
Q

What can be said about the pattern of inflammation in Ulcerative Colitis?

A
  • Inflammation localized only in the colon
  • Always one stretch of tissue
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16
Q

What are the characteristics of Crohn’s disease? (5)

A
  • Patchy
  • Transmural
  • Dense inflammation of lymphocytes
  • Presence of granuloma’s
  • Ulcer formation
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17
Q

What does ‘transmural’ mean?

A

Affecting all layers of the bowel wall

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18
Q

What do granuloma’s in CD tell us?

A

Immune system is not functioning properly

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19
Q

What are the hotspots for CD?

A
  • Terminal ileum
  • Colon
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20
Q

Why are the terminal ileum and colon the hotspots for CD?

A

This is where you have the biggest density and diversity of microbiota

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21
Q

What are cobblestones and how are they formed?

A

Healthy pieces of tissue that are bulging out, because there is strictering tissue (scar tissue) next to it. Because this stretchiness is lost in these pieces of tissue, it pushes the healthy/softer tissue out

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22
Q

What are the characteristics of Ulcerative Colitis? (4)

A
  • Superficial (mucosal) layers (only top layer)
  • Infiltration of lymphocytes, granulocytes
  • Loss of goblet cells (typical for UC → they are empty → mucus out of the cells)
  • Presence of ulcerations and crypt abscesses
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23
Q

True or false: ‘Histologists can not make a distinction between Crohn’s disease and Ulcerative colitis based on granuloma formation.’

A

False. Granuloma formation never occurs in Ulcerative colitis

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24
Q

How do you classify diversity in IBD?

A

Genetics

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25
Q

What is monogenic disease?

A

Disease caused by inheritance of single gene mutations (genes that are completely non-functional)

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26
Q

What is the difference between monogenic disease and SNP-associated dysfunction?

A
  • Monogenic disease: genes are completely non-functional
  • SNP: functional change. Gene is not completely non-functional
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27
Q

Cytokines are predominantly important in CD/UC?

A

CD

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28
Q

Immune-genes are predominantly important in CD/UC?

A

UC

29
Q

Describe the factors involved in an immune regulation pathway in IBD (3)

A
  • IL10RA, IL10RB (two receptors form one chain)
  • IL10 (ligand)
  • STAT3 (phosphorylation)
30
Q

Which factor is involved in neutrophil function and phagocyte/bacterial killing?

A

NFkB

31
Q

Why is NOD2 important?

A

It’s a PRR molecule important for innate immune activation

32
Q

Three questions to consider when studying/adressing the heterogeneity in IBD

A
  • Which pathways are essential to prevent IBD?
  • What type of inflammation emerges from a particular defective pathway?
  • What microbial changes relate to this?
33
Q

Examples of monogenic disease in IBD (3)

A
  • Defective IL10R gene
  • Defective IL10
  • Defective neutrophil function
34
Q

Which risk increases when someone has defective neutrophil function?

A

Risk of infection

35
Q

When do classical people start to suffer from IBD?

A

Peak age 25

36
Q

When do patients with monogenic disease start to suffer from IBD?

A

Super early in age

37
Q

What can cause intestinal inflammation in monogenic immune disorders? (2)

A
  • Defective host defense
  • Hyperactive host defense
38
Q

Example of IBD-like disease due to defective host defense

A

Chronic granulomatous disease due to defective neutrophil function

39
Q

Example of IBD-like disease due to hyperactive host defense

A

Interleukin-10 RA deficiency due to defective regulation via IL-10 signaling

40
Q

Name pathways arising from gene discovery in IBD (5)

A
  • NOD2
  • Autophagy (ATG16L1; IRGM; ATG5)
  • Defective barrier
  • IL-10 signaling
  • Adaptive immunity: IL23, IL23R, Th17, IL17
41
Q

Where are polymorphisms in NOD2 most associated with CD?

A

In CD affecting the ileum

42
Q

What are the two most important normal functions of NOD2 that can be deregulated due to polymorphisms?

A
  • NOD2 promotes the production of AMP by Paneth cells
  • Chronic NOD2 stimulation in APC down regulates pro-inflammatory cytokine production
43
Q

What happens when you delete NEMO in mice?

A

Insufficient NFkB signaling and increased TNF-induced apoptosis

44
Q

Where does the TNF come from during TNF-induced apoptosis in the absence of NFkB?

A

Macrophages that do have intact NFkB signaling, causes spontaneous and severe chronic intestinal inflammation

45
Q

What do mice deficient for IL-10 develop?

A

Enterocolitis to commensal Helicobacter hepaticus

46
Q

What is celiac disease?

A

Loss of tolerance to dietary gluten

47
Q

Which part of the intestine is inflamed in celiac disease? What does this cause?

A

Proximal small intestine is inflamed, nutrient uptake is perturbed

48
Q

What is gluten?

A

Protein component of wheat, barley and rye

49
Q

What is gluten normally used for in plants?

A

Source of protein to nourish embryonic plants during germination

50
Q

What are the characteristics of gluten as a storage protein? (3)

A
  • Insoluble in water
  • Disulfide and hydrogen bonds (aggregates)
  • Proline-rich (resistance to degradation)
51
Q

What are the elastic properties of gluten used for in the food industry?

A
  • The fermentation of bread
  • Texture of pasta
52
Q

Histology: What are the hallmark features of epithelial damage and duodenal inflammation in Celiac disease? (4)

A
  • Duodenal crypt hyperplasia
  • Duodenal villous atrophy
  • Increased numbers of CD8+ MHCI restricted Intraepithelial lymphocytes (IEL)
  • Gliadin-specific IFN-y secreting CD4+T cells in the LP
53
Q

Serum and genetics: What are the hallmark features of epithelial damage and duodenal inflammation in Celiac disease?

A
  • Anti-tissue transglutaminase-2 (TG2) antibodies (binding antibodies - NOT neutralizing)
  • Genetic susceptibility HLA-DQ2/HLA-DQ8
54
Q

What is the normal function of transglutaminase-2?

A

Tissue damage: enzyme becomes activated and repairs

55
Q

Which immune cells drive disease chronicity in Celiac disease?

A

Gluten (in particular gliadin) specific memory CD4+ T cells

56
Q

How do gluten (in particular gliadin) specific memory CD4+ T cells drive disease chronicity in Celiac disease? (4)

A
  • Gluten diffuse across the epithelium
  • TG2 enzyme binds gluten and deamidates/changes conformation of gluten
  • Deaminated gluten peptide can fit in this HLA-DQ2/DQ8 groove
  • Inflammatory T cell differentiation
57
Q

How does this TG2-gliadin complex drive disease in Celiac disease?

A

Due to the conformational change, the complex is suddenly recognized as non-self, because gliadin is attached to it

58
Q

Which cytokine is predominantly produced in Celiac disease?

A

IFN-y, but also IL-21

59
Q

Which antibody is predominantly formed during Celiac disease?

A

IgA

60
Q

Which antibodies are produced by Celiac patients if they are IgA deficient?

A

IgG

61
Q

Which innate cytokines are involved in Celiac disease? (3)

A
  • IL-15
  • IFN-a
  • IL-21
62
Q

Which cytokine would you never find in IBD, but is prominently found in Celiac disease?

A

IL-15

63
Q

Summary: Which innate immune responses are characteristic for Celiac disease?

A
  • Stressed innate epithelial cells secreting IL-15 and expressing NK-receptor ligands
  • Cytotoxic intraepithelial lymphocytes lyse epithelium
64
Q

Summary: Which adaptive immune responses are characteristic for Celiac disease?

A
  • Inflammatory gluten-specific HLA-DQ-restricted CD4 T cells secrete IFN-y
  • Plasma cells secrete anti-TG2 antibodies
65
Q

What causes the villus atrophy in celiac disease?

A

Killing of innate epithelial cells expressing NK-receptor ligands

66
Q

Summarize the celiac disease pathogenesis (3)

A
  • CD4-T cell derived IFN-y causes epithelial stress and activates cytotoxic IEL.
  • IL-15 production by epithelial cells co-stimulates cytotoxic IEL
  • Cytotoxic CD8+ IEL kill epithelial cells.
67
Q

What does the absence of IL-10 signaling in CD11c+ APC cause?

A

Celiac disease-like pathology
- Crypt hyperplasia
- Increased IEL numbers
- Increased numbers of CD4+ and CD8+ T cells in LP

68
Q

Mice model: what is required for tolerance to dietary gluten?

A

Intact IL-10 regulation

69
Q

25% of the dutch population is HLA-DQ2+, however only 1% develops celiac disease. Why?

A

Theory: Tregs maintain balance in healthy individuals

I&I WC1 (25 decks)

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