Barrier Immunology in the Gut Flashcards

1
Q

TH1 cells secrete IFN-y which stimulates class switching to ?

A

IgG subtypes

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2
Q

TGF-beta and retinoic acid seem to stimulate class switching to

A

IgA

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3
Q

TH2 cells secrete IL4 and IL5 which stimulates class switching to

A

IgE

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4
Q

what is the function of IgE

A

binds to cells with an Fc receptor for IgE triggering degranulation of granulocytes (eosinophils, basophils, mast cells)

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5
Q

IgE is secreted as a ?

A

monomer

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6
Q

IgA is predominantly found as a ? secreted into the ?

A

dimer
GI and respiratory tract mucous

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7
Q

what is important function in developing tolerance within the mucosal immune system

A

IgA

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8
Q

what are major types of innate lymphoid cells (ILCs)

A
  • NK cells
  • “resident” ILCs
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9
Q

Type 1 ILCs secretes ?

A

secrete cytokines such as IFN-y and TNF-a -> “pushes” the barrier into a “Type 1” response and favours the development of Th1 cells

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10
Q

Type 2 ILCs secretes?

A

secrete cytokines such as IL-4, IL-5, IL-9, IL-13  “pushes” the barrier into a “Type 2” response and favours the development of Th2 cells

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11
Q

Type 3 ILCs secretes?

A

secrete IL-17, IFN-y -> effective against extracellular bacteria

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12
Q

what are claudins in tight junctions?

A

trans-membrane proteins that can act as channels for small molecules (paracellular)

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13
Q

what are occludin in tight junctions?

A

trans-membrane protein, function not clear

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14
Q

what are Junctional adhesion molecules (JAM)?

A

Trans-membrane protein that may mediate permeability to larger molecules

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15
Q

what are ZO-proteins in tight junctions?

A

Important in tight junction formation, interact with the cytoskeleton

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16
Q

what are Peyer’s patches?

A

large collections of lymphoid nodules in the ileum

17
Q

what are Isolated lymphoid follicles (ILFs)?

A

MALT nodules without capsules, much smaller than peyer’s patches

18
Q

what does goblet cells do?

A

Secrete mucous, which presents a barrier to bacterial invasion

19
Q

what secretes anti-microbial peptides (AMPs) that prevent bacteria from getting “too close” to the epithelial lining

A

goblet cells

20
Q

what else secrete large quantities of AMPs?

A

paneth cells

21
Q

what are Very specialized cells present over the surface of Peyer patches and isolated lymphoid follicles (ILFs)

A

microfold cells

22
Q

what impairs bacterial mobility and makes it difficult for bacteria to penetrate the epithelial barrier

A

mucous in the lumen

23
Q

what is secreted mostly by Paneth cells, mainly toxic against gram (+)-ve bacteria but also seems to have some activity against gram (-)-ves

A

REG3

24
Q

what does “unshuffled” IgA mean

A

the antibody sequence has not undergone affinity maturation – is often broadly specific for a wide range of microbes

25
Q

what does “shuffled” IgA mean

A

the antibody sequence has undergone affinity maturation due to Th-B cell interactions

26
Q

IgA is secreted from plasma cells from 3 major sources:

A
  • ILFS
  • Peyer’s patches
  • Plasma cells in the mesenteric lymph nodes located around the abdominal aorta
27
Q

what induces IgA class switching in B-cells via TGF-beta, and CD40L/iCOS interactions – RA plays a role but is not secreted by follicular T cells

A

T-dependent – follicular T cells (Tfh)

28
Q

when activated, ILC3 cells secrete?

A

○ Secrete IL-22 & IL-17, which leads to increased production of AMPs by enterocytes and Paneth cells
○ Secrete factors that induce the full development of Peyer’s patches and ILFs and IgA production
○ Amplify the Th17 response in the gut

29
Q

Th17 cells can be induced to become either:

A
  • Tfh cells
  • Treg cells
30
Q

what “messes with” our intestinal immune in a complex and multi-step way

A

Gluten

31
Q

what is a degradation product of gluten and is resistant to proteolytic degradation by pancreatic enzymes

A

alpha-gliadin

32
Q

what does gliadin bind to?

A

chemokine receptor CXCR3

32
Q

what does CXCR3 produce and release

A

zonulin

33
Q

What happens when zonulin bind to its receptor

A

disassembly of ZO proteins -> disassembly of tight junctions

34
Q

what is the adult presentation of celiac disease

A
  • anemia, chronic diarrhea
  • bloating, fatigue
  • deficiencies in B12 and iron
35
Q

what is the pediatric presentation of celiac disease

A

○ Irritability, anorexia, chronic diarrhea, weight loss muscle wasting (malabsorption)
○ Some present with abdominal pain, nausea, vomiting, bloating, or constipation