Microbiota Flashcards Preview

Hugh's MD1 Abdominal > Microbiota > Flashcards

Flashcards in Microbiota Deck (91):
1

Which bacteria commonly cause overgrowth in the microbiota?

Candida

Clostridium difficile

2

How many genes are provided to us by our microbiota?

10^6

2

What leads to pseudomembraneous colitis?

Antibiotics use (particularly broad spectrum)

Cytotoxic drugs

3

Which immune cell do lean people have more of?

Tregs

4

What does the appendix do for the microbiota?

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

C. difficile overgrowth in patients with appendectomies

5

How does having a caesarian section effect the microbiota?

It takes longer to develop

5

What is the function of hte mucous layer/ glycocalyx

Holds the bacteria at arms length

6

How similar are the microbiota of identical twinss?

50%

7

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

Multi-subsets, cytokine secreting that resembles a Th subset

7

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

MAdCAM-1

8

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

B12, folate, K, biotin

8

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

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 

9

How much does the microbiota weigh?

1-2kg

9

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

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

9

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

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

Pathogens can be invasive, detected by intracellular and apical PRRs

10

What do lymphoid tissue inducer cells do?

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

11

What is a immunomodulatory molecule secreted by enterocytes?

TGF-beta

12

What is the aetological agent of pseudomembranous colitis?

Clostridium difficile

13

What is TLR 5 for?

Flagellum

14

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

It is altered in a predictable way

14

Overall the microbiota in obese people is...

Differs in composition 

Altered fermentation

Greater energy absorption

14

What is the difference between pre- and probiotics?

Prebiotics are dietary supplements that promote healthy microbiota

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

15

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

Yes

Lysozyme 

Lactoferrin

15

What is Kwashiorkor?

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

16

What is the microbiome?

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

16

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

Throat

17

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

Goblet cells

18

What does ILF stand for?

Isolated lymphoid follicle

18

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

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

19

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

Towards Treg and Th2

20

What is the third signal for IgA isotype switching?

TGF-beta

20

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

Carbohydrate metabolism = greater energy extraction

21

Why is vaginal delivery better?

Allows rapid acquision of Firmicutes and Bifidobacteria

21

What is the function of interepithelial lymphocytes in GIT defence?

Host protection

Epithelial repair

Promoting tolerant DCs

Secrete IL-22

22

What happens to patients intestinal permeability in inflammatory bowel disease?

It increases

22

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

Faecal transplant

24

How does the microbiota effect angiogenesis?

It induce host gene changes

25

What is the meaning of physiological inflammation?

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

27

Which amino acids do the microbiota particularly help provide?

Lycine

Threonine

27

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

Increase defence against pathogens

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

Tone inflammatory response and promote immune regulation

29

How does the microbiota develop with age?

It diversifies

29

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

TCA cycle

31

Are eukaryotes part of the normal microbiota?

Yes

33

What is an alteration in our normal microbiota called?

Dysbiosis

34

How were non-culturable bacteria identified?

Meta-genomics

35

When do isolated lymphoid follicle develop in humans?

Postnatally

37

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

 


 

Bifidobacteria/ Clostridia 

 

 

38

Which cytokine is particularly important for the gut immune defence?

IL-22

38

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

Decreases its diversity

39

How do DCs direct T cells under inflammatory conditions?

Into the develop of Th17 and Th1

40

How much IgA can be produced by B cells?

40mg/kg of IgA/day

41

Sterile mice have smaller what?

Peyer's patches and less lymphoid tissue

42

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

Lactose fermentation

43

What mediates the low grade inflammation seen in obese people?

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

More mast cells, T cells and macrophages

45

What is IL-22 associated with in GIT defence?

Antimicrobial defence

Epithelial repair

Tight junction integrity

46

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

Differentiate pathogens from normal microbiota and food antigen

48

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

Vaginal is better than caesarian 

50

What is a major function of NK in GIT defence?

Secrete IL-22

52

Are they aerobes in the lower GIT??

Yes

53

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

TLR 2 and 4 

To prevent over stimulation but GIT microbiota

54

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

Appendectomy

55

When do mesenteric lymph nodes develop in humans?

Prenatally

57

How are macrophages in the GIT different from elsewhere?

Express less TLRs therefore are hyporesponsive to TLR signalling

58

How many bacteria are in our gut?

10^12

59

What does MALT stand for?

Mucosal-associated lymphoid tissue

60

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

It diversifies

 

61

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

It decrease

63

When do Peyer's patches developed in humans?

Prenatally

64

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

Insulin resistance

Serum triglycerides

Insulin 

Cholesterol

65

Where is TLR5 expressed on enterocytes? Why?

Basolateral surface

So only invasive pathogen activate it

66

What are the four most common phyla found?

Firmicutes

Bacteroidetes

Acinobacteria

Proteobacter

68

What does the microbiome's genes help us with?

Helps with:

Metabolism

Development

Immune system

Protection against pathogens

70

T/F Everyone's microbiota looks the same

False, each of us have a unique "fingerprint"

71

What phyla is most prevalent at a young age?

Firmicutes

73

What carbohydrates does the microbiota help digest?

Lactose

Cellulose

 

75

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

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

76

What type of viruses make up most of our microbiota?

Bacteriophages

77

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

2.5 years

78

What is rePOOPulate?

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

79

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

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

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

alpha4beta7

82

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

The small intestine

83

What antibiotics are used to treat pseudomembraneous colitis?

Metronidazole (+/- vancomycin if required)

84

Is the diversity at each site the same?

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

85

T/F enterocytes secrete cytokines but not chemokines

False, they secrete both

86

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

Lymphoid cells sit there so they can catch Ag immediately

87

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

True

88

What does MAIT stand for?

Mucosal associated invariant T cells

89

Where are our microbiota predominantly gram +ve?

Skin, throat and vagina

90

What cytokines is the third signal from Treg differentiation?

TGF-beta

91

Animal based diet is associated with what type of bacteria?

Increase in bile-tolerant bacteria

Decrease in bacteria that metabolise plant polysaccaride