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Hugh's MD1 Abdominal > Microbiota > Flashcards

Microbiota Flashcards

(91 cards)

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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
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?
## Footnote 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

Hugh's MD1 Abdominal (21 decks)

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