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Hugh's MD1 Abdominal > Microbiota > Flashcards

Microbiota Flashcards

1
Q

Which bacteria commonly cause overgrowth in the microbiota?

A

Candida

Clostridium difficile

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2
Q

How many genes are provided to us by our microbiota?

A

10^6

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2
Q

What leads to pseudomembraneous colitis?

A

Antibiotics use (particularly broad spectrum)

Cytotoxic drugs

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3
Q

Which immune cell do lean people have more of?

A

Tregs

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4
Q

What does the appendix do for the microbiota?

A

It is a reservoir for bacteria - as reflected by higer incidence of

C. difficile overgrowth in patients with appendectomies

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5
Q

How does having a caesarian section effect the microbiota?

A

It takes longer to develop

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5
Q

What is the function of hte mucous layer/ glycocalyx

A

Holds the bacteria at arms length

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6
Q

How similar are the microbiota of identical twinss?

A

50%

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7
Q

Innate lymphoid cells of the GIT resemble which other class of immune cell most?

A

Multi-subsets, cytokine secreting that resembles a Th subset

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7
Q

What does alpha4beta7 bind to on vascular enthelium of all mucosal surface?

A

MAdCAM-1

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8
Q

Which vitamins are made entirely by the microbiota (from dietary sources)?

A

B12, folate, K, biotin

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8
Q

How is the micrbiome’s response to a nutritious diet different in children with Kwashiorkor cf those without?

A

The diversity of the microbiome in children with Kwashiorkor doesn’t increase in response to a change from Malawian diet to nutritious diet cf to health children

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9
Q

How much does the microbiota weigh?

A

1-2kg

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9
Q

What is one important implication of alpha4beta7 homing activated T and B cells to all mucosal surfaces (more than just the GIT’s)?

A

B cells will go to the breast tissue > IgA is secreted in milk for the infant’s protection

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9
Q

How does the GIT epithelium and lymphoid tissue differentiate the microbiota from pathogens?

A

Pathogens are close to the epithelium, the microbiota are held at arms lengths

Pathogens can be invasive, detected by intracellular and apical PRRs

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10
Q

What do lymphoid tissue inducer cells do?

A

Stimulate recruitment of DCs, T cells and B cells to Peyer’s patches and isolated lymphoid follicles

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11
Q

What is a immunomodulatory molecule secreted by enterocytes?

A

TGF-beta

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12
Q

What is the aetological agent of pseudomembranous colitis?

A

Clostridium difficile

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13
Q

What is TLR 5 for?

A

Flagellum

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14
Q

How can you characterise the microbiota of people with type 2 diabetes?

A

It is altered in a predictable way

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14
Q

Overall the microbiota in obese people is…

A

Differs in composition

Altered fermentation

Greater energy absorption

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14
Q

What is the difference between pre- and probiotics?

A

Prebiotics are dietary supplements that promote healthy microbiota

Probiotics are live organisms ingested to improve the health of the microbiota

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15
Q

Do goblet cells secrete more than just mucous? So if, what?

A

Yes

Lysozyme

Lactoferrin

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15
Q

What is Kwashiorkor?

A

A wasting disease associated with malnutrition that is predmoninantly found in Africa

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16
Q

What is the microbiome?

A

The total of all the genes provided to us by the microbiota

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16
Q

Which site has more micro-organisms, the throat or skin?

A

Throat

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17
Q

Apart from M cells, what other cells delivery Ag across the gut epithelium?

A

Goblet cells

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18
Q

What does ILF stand for?

A

Isolated lymphoid follicle

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18
Q

T/F DCs can only get their Ag from M cells or goblet cells

A

False, they can also project their process through tight junctions directly into the lumen of the gut

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19
Q

In the steady state how do DCs direct T cell maturation?

A

Towards Treg and Th2

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20
Q

What is the third signal for IgA isotype switching?

A

TGF-beta

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20
Q

What genes does the microbiota of obese mice have more off?

A

Carbohydrate metabolism = greater energy extraction

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21
Q

Why is vaginal delivery better?

A

Allows rapid acquision of Firmicutes and Bifidobacteria

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21
Q

What is the function of interepithelial lymphocytes in GIT defence?

A

Host protection

Epithelial repair

Promoting tolerant DCs

Secrete IL-22

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22
Q

What happens to patients intestinal permeability in inflammatory bowel disease?

A

It increases

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22
Q

What is an alternative treatment for recurrent pseudomembraneous colitis recently introduced?

A

Faecal transplant

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24
Q

How does the microbiota effect angiogenesis?

A

It induce host gene changes

25
Q

What is the meaning of physiological inflammation?

A

The microbiota induced changes to the mucosal immune response that promotes the development of a protective innate and adaptive immune system

27
Q

Which amino acids do the microbiota particularly help provide?

A

Lycine

Threonine

27
Q

What effect do PAMPs from microbiota have? How do they do that?

A

Increase defence against pathogens

Stimulate more mucous production, Paneth cell replication, anti-microbial peptide secretion

Tone inflammatory response and promote immune regulation

29
Q

How does the microbiota develop with age?

A

It diversifies

29
Q

Which metabolic process was the Kwashiorkor microbiome found to adversely affect?

A

TCA cycle

31
Q

Are eukaryotes part of the normal microbiota?

A

Yes

33
Q

What is an alteration in our normal microbiota called?

A

Dysbiosis

34
Q

How were non-culturable bacteria identified?

A

Meta-genomics

35
Q

When do isolated lymphoid follicle develop in humans?

A

Postnatally

37
Q

In mice, the numbers of which bacteria increases in response to a iron free diet?

A

Bifidobacteria/ Clostridia

38
Q

Which cytokine is particularly important for the gut immune defence?

A

IL-22

38
Q

How does a High fat / low fibre diet affect the microbiota?

A

Decreases its diversity

39
Q

How do DCs direct T cells under inflammatory conditions?

A

Into the develop of Th17 and Th1

40
Q

How much IgA can be produced by B cells?

A

40mg/kg of IgA/day

41
Q

Sterile mice have smaller what?

A

Peyer’s patches and less lymphoid tissue

42
Q

The microbes present in the first few months of life must do what?

A

Lactose fermentation

43
Q

What mediates the low grade inflammation seen in obese people?

A

More inflammatory cytokines - TNF-alpha, IL-1, IL-6, IL-17

More mast cells, T cells and macrophages

45
Q

What is IL-22 associated with in GIT defence?

A

Antimicrobial defence

Epithelial repair

Tight junction integrity

46
Q

What must the gut’s immune system be able do?

A

Differentiate pathogens from normal microbiota and food antigen

48
Q

How does the mode of a babies delivery effect the microbiota?

A

Vaginal is better than caesarian

50
Q

What is a major function of NK in GIT defence?

A

Secrete IL-22

52
Q

Are they aerobes in the lower GIT??

A

Yes

53
Q

Some TLRs on enterocytes are downregulated after birth, which ones? Why?

A

TLR 2 and 4

To prevent over stimulation but GIT microbiota

54
Q

What surgical precedure is associated with a greater risk of recurrent pseudomembraneous colitis?

A

Appendectomy

55
Q

When do mesenteric lymph nodes develop in humans?

A

Prenatally

57
Q

How are macrophages in the GIT different from elsewhere?

A

Express less TLRs therefore are hyporesponsive to TLR signalling

58
Q

How many bacteria are in our gut?

A

10^12

59
Q

What does MALT stand for?

A

Mucosal-associated lymphoid tissue

60
Q

How does the microbiota of children change in response to exposure to different food?

A

It diversifies

61
Q

What happens the bacterial diversity to patients with inflammation bowel disease?

A

It decrease

63
Q

When do Peyer’s patches developed in humans?

A

Prenatally

64
Q

What do individuals with low microbiota diversity have higher levels of?

A

Insulin resistance

Serum triglycerides

Insulin

Cholesterol

65
Q

Where is TLR5 expressed on enterocytes? Why?

A

Basolateral surface

So only invasive pathogen activate it

66
Q

What are the four most common phyla found?

A

Firmicutes

Bacteroidetes

Acinobacteria

Proteobacter

68
Q

What does the microbiome’s genes help us with?

A

Helps with:

Metabolism

Development

Immune system

Protection against pathogens

70
Q

T/F Everyone’s microbiota looks the same

A

False, each of us have a unique “fingerprint”

71
Q

What phyla is most prevalent at a young age?

A

Firmicutes

73
Q

What carbohydrates does the microbiota help digest?

A

Lactose

Cellulose

75
Q

T/F Antibiotics only causes short term changes to the microbiota?

A

False, some can have long term affects (eg Vancomycin)

76
Q

What type of viruses make up most of our microbiota?

A

Bacteriophages

77
Q

How long does it take for one’s microbiota to be established?

A

2.5 years

78
Q

What is rePOOPulate?

A

A mixture of 33 microbes to restoration of a healthy gut microbiota

79
Q

What are the 2 postulated mechanisms to explain how the microbiota provides extra energy to the host?

A
  1. They directly provide nutrients from dietary substances eg vitamin B12
  2. They alter the host’s metabolism to help it metabolise carbohydrates and fats
81
Q

What is the name of the homing molecule that direct activated B and T cells to the GIT epithelium?

A

alpha4beta7

82
Q

Peyer’s patches are primarily located in which part of the GIT?

A

The small intestine

83
Q

What antibiotics are used to treat pseudomembraneous colitis?

A

Metronidazole (+/- vancomycin if required)

84
Q

Is the diversity at each site the same?

A

No, while the main 4 phyla are generally there, they’re in different proportions

85
Q

T/F enterocytes secrete cytokines but not chemokines

A

False, they secrete both

86
Q

What is the function of the pocket on the apical side of M cells?

A

Lymphoid cells sit there so they can catch Ag immediately

87
Q

T/F the metabolic effect of the microbiota is the same across different sites despite the variation in phyla at those sites

A

True

88
Q

What does MAIT stand for?

A

Mucosal associated invariant T cells

89
Q

Where are our microbiota predominantly gram +ve?

A

Skin, throat and vagina

90
Q

What cytokines is the third signal from Treg differentiation?

A

TGF-beta

91
Q

Animal based diet is associated with what type of bacteria?

A

Increase in bile-tolerant bacteria

Decrease in bacteria that metabolise plant polysaccaride

Hugh's MD1 Abdominal (21 decks)

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