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Jason's GI Block > Microbiota 1 > Flashcards

Microbiota 1 Flashcards

1
Q

how many commensals in/on us?

A

1-2kg

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2
Q

microbiome provides us with extra source of?

A

genes

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3
Q

humans and microbiota are known as:

A

mutualists

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4
Q

how many bacteria in microbiota?

A

10^14

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5
Q

how many species of bacteria on us?

A

1000

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6
Q

majority of bacteria use oxygen?

A

99.9% are anaerobes

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7
Q

Gram what in
Throat and skin
Gut
Vaginal?

A

Throat/ skin: +ve

gut: -ve
vaginal: +ve

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8
Q

4 main bacteria phyla from most to least

A
  1. bacteroides
  2. firmicutes (clostridia, mollicutes)
  3. actinobacteria
  4. proteobacteria (E.coli)
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9
Q

each body site has low or high diversity of microbiota?

A

high

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10
Q

twins have the same microbiota?

A

share <50% of bacterial species

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11
Q

microbiota unstable in host?

A

stable but influenced by determinants

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12
Q

4 things microbiota contribute to:

A

metabolism (cellulose)
development
immunity
protection

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13
Q

6 factors that influence gut microbiota?

A 
mode of delivery
age (more diversity with age)
diet (breast milk)
antibiotics
genetics/environment (rural vs. city)
chronic inflammation
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14
Q

vaginal birth associated with rapid acquisition of?

A

Firmicutes Bifidobacteria

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15
Q

animal based diets do what to microbiota?

A

decrease plant metabolizing bacteria, more bile-tolerant bacteria

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16
Q

what does iron do to mice microbiota?

A

more bacteroides

less bifidobacteria

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17
Q

does microbiota of mice treated with amoxicillin/metronidazole and bismuth recover?

A

yes

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18
Q

which antibiotic do you not recover your diversity of microbiota?

A

vancomysin

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19
Q

microbiota provides how much calories?

A

10% of calories from plant CHO

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20
Q

microbiota in nutrition does 2 things to help us

A
  1. change our genes for CHO/lipid metabolism

2. maintain enterocyte differentiation/function

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21
Q

microbiota taxa varied by site, what remained stable?

A

metabolic pathways eg. 16S rRNA

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22
Q

what vitamins do microbiota make for us?

A

vitamin B12, K
biotin
folate

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23
Q

what happens to bile acid in the gut?

A

microbiota break it down to desoxycholic acid to reabsorb back into liver

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24
Q

what happens to amino acids in gut?

A

nitrogen recycling from lysine and threonine

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25
Q

what does bacterial degradation of host glycans do?

A

elicits synthesis of new glycans by host

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26
Q

how does microbiota maintain enterocyte differentiation

A

from production of short chain fatty acids from fibre

27
Q

is angiogenesis affected by microbiota?

A

yes

28
Q

describe the metabolism path of dietary fibre:

A

broken into monosaccharides>fermented into SCFAs>absorbed by colon>reaches liver>substrates for gluconeogenesis/lipgenesis

29
Q

how do the colonic epithelial cells get their energy?

A

from fermented and absorbed SCFAs

30
Q

SCFAs do more than just be energy source, explain:

A

control colonic gene expression via HDAC inhibition and GPCR signal regulation

31
Q

mucosal immune systemis closely associated with?

A

intestinal microbiota

32
Q

what is MALT?

A

mucosa-associated lymphoid tissue

33
Q

SI covers how many square metres? so what?

A

400m2, big antigenic challenge, which is why it has the largest collection of lymphoid tissue

34
Q

2 big things the MALT must be able to do

A

protection from pathogens (IgA)

tolerance to normal microbiota/food

35
Q

what is ILFs? where are they found?

A

isolated lymphoid follicles in large/small intestine

36
Q

where are Peyers patches? what happens there?

A

small intestine

induction of T, B Cells

37
Q

enterocytes secrete what cytokines?

A

TGF-B, chemokines, anti-microbial peptides

38
Q

what is lactoferrin? where does it come from on the small intestine?

A

on villus
from Goblet cells
inhibits bacteria growth

39
Q

Paneth cells do what?

A

secrete defensins

40
Q

what immune cells are in the lamina propria of the small intestine?

A

Intraepithelial lymphocytes (IEL)

41
Q

2 kinds of Intraepithelial lymphocytes in the villus?

A

nonconventional lymphocytes

innate lymphocytes

42
Q

what two cells in the small intestine play a role in tolerance?

A 
enterocytes
IEL (intraepithelial lymphocytes)
43
Q

3 innate defences of gut?

A

peristaltic (flushing) action
acid
mucous layer to hold commensals at ‘arms length’

44
Q

Describe the 3 innate defensive roles of enterocytes

A
  1. barrier: integrity is critical tight junctions
  2. antimicrobial factors
  3. cytokines/chemokines
45
Q

What is a mechanism for controlled antigen access?

A

M Cells/ dendritic cells

46
Q

innate leucocytes include:

A

lymphocytes

macrophages

47
Q

What are ILCs? what do they do?

A

innate lymphoid cells

secrete cytokines

48
Q

what does IL-17, IL-22 do?

A

recruits and activates neutrophils

49
Q

What does lymphoid tissue inducer cells do?

A

stim DC, T, B cells, PPs, ILFs

50
Q

what cytokine does IELs secrete?

A

IL-22

51
Q

what does IL-22 do?3 things

A

enhances antimicrobe defence
epithelial repair
barrier integrity

52
Q

What are MAIT cells? what do they do?

A

mucosal associated invariant T cells

rapid response to bacterial antigen

53
Q

what do invariant NKT cells do?

A

secrete pro-inflamm cytokines like IL-22

54
Q

M cell stands for? where is it?

A

microfold cell

directly over the lymphoid aggregates (PPs, ILFs isolated lymphoid follicles)

55
Q

villi on M cells?

A

Nope

folded luminal surface

56
Q

M-cell secrete mucous? why?

A

does not

microbial access easier

57
Q

DCs are located directly below the M-cell, how do they sample? 2 ways:

A

directly (tentacle into lumen)

indirectly (via goblet/M-cells

58
Q

TGF-B stands for?

A

transforming growth factor

59
Q

tell me what DCs do in:

  1. steady state
  2. inflamm state
A
  1. induce Tregs/TGF-B

2. induce Th1/Th17

60
Q

DCs bias what immunoglobulin from B-cells?

A

Isotype switching to IgA

61
Q

inducing mucosal addressin a4B7 on T/B cells does what?

A
  1. allows to bind to MAdCAM1 on mucosal surfaces

2. also gives chemokine receptors specific for lamina propria

62
Q

a4B7 activated T/Bcells are found where?

A

distributed through all mucosal surfaces

63
Q

IELs do what to enterocytes?

A

may eliminate damaged ones

64
Q

what happens in MALT?

A

stimulation
suppression
of immune cells

Jason's GI Block (32 decks)

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