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Host Defense Exam 2 > Microbiota and the Immune Response > Flashcards

Microbiota and the Immune Response Flashcards

1
Q

What are some good results of commensal bacteria?

A

we need bacteria do generate secondary lymphoid tissue

mucosal immunity

keep pathogenic agents out

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2
Q

What are some diseases that have been associated with a deficient or improper microbiota?

A

immune encephalitis, IBD, obesity, arthritis,

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3
Q

What is unique about the commensal composition at various mucosal areas?

A

composition of bacteria varies

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4
Q

How does commensal gut bacteria contribute to good health?

A

provide energy by metabolizing dietary polysaccharides

provide vitamins

required for development of the immune system

protect from pathogenic bacteria

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5
Q

How do commensals protect from intestinal inflammation?

A

balance pro and anti inflammatory immune reactions

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6
Q

What is the relationship between Th1, Treg cells, and commensal bacteria?

A

Th17 is needed for protection from pathogenic bacteria, but overproduction of IL17 can lead to intestinal inflammation

Th17 cells are regulated by Tregs - a healthy balance is generated by a healthy intestinal microbiota

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7
Q

What are some examples of organisms inducing specific responses?

A

Segemented filamentous bacteria (SFB) induces Th17

B. fragilis regulates Treg cells

S. typhimunum regulates Th1 cells

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8
Q

What can dysbiosis result in?

A

favoring pro-inflammatory (Th17, Th1) over antiinflammatory (Treg) state

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9
Q

What can cause dysbiosis?

A

antibiotics
diet
toxins
defects in intestinal barrier

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10
Q

What is a precipitating factor of IBD?

A

changes in development or composition of intestinal microbiota results in a T cell mediated inflammatory response

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11
Q

What happens if you take a mouse engineered to develop IBD and do a fecal transplant to a wt mouse?

A

the wt mouse will develop IBD

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12
Q

How can IBD be treated?

A

with Bacteroides fragilis, which induces an anti-inflammatory response

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13
Q

What are some situations in which the incidence of allergy is decreased

A

Children growing up on farms

Children attending day care during first 6 months of life

east german children compared to west german

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14
Q

what is a situation in which the incidence of allergy is increased?

A

Children given antibiotics within the first year of life

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15
Q

What does a rise in immune disorders coincide with?

A

a decline in infectious disease

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16
Q

What is allergy due to?

A

Th2 IgE response

17
Q

What down regulates Th2 responses?

A

Th1 responses

18
Q

What elicits a Th1 response, and what are the factors involved?

A

bacteria and viruses

IL-2, IFN-gamma

19
Q

What would decreased bacterial and viral infections result in?

A

insufficient Th1 response, which would increase Th2 response (IgE)

20
Q

What regulates the Th1 and Th2 responses?

A

Commensals

21
Q

What is EAE, and how are commensals implicated in its management?

A

autoimmune disease where Ab are directed against the myelin sheath - if you give a mouse with EAE intestinal bacteria that induce Tregs, you can prevent EAE

22
Q

What do TLR5 knockout mice develop?

A

increased food intake, insulin resistance, diabetes, obesity

altered gut microbiota

23
Q

What does antibiotic treatment do to the TLR5 knockout mice?

A

reverses obesity

24
Q

What happens if you do a fecal transplant form a TLR5 knockout to a wildtype mouse?

A

the wt will develop obesity, indicating that gut microbiota can cause metabolic syndrome

25
Q

What happens if you transplant the microbiota from a lean and obese twin to two different mice?

A

the obese microbiota will induce the wt mouse to become obese

the lean microbiota will induce the wt mouse to become lean

26
Q

What happens when a lean and obese mouse were cohabitated?

A

obese mouse developed the microbiota of the lean mouse and obesity did not develop

If given low-fat diet, lean-associated microbiota can
prevent obesity in mice with obese-associated microbiota.

With high-fat diet, lean microbiota did not prevent obesity.

27
Q

What does a high fat diet do?

A

induces changes in the microbiota that can promote obesity

affects innate lymphoid cells to secrete IL-22 which induces expression of anti-microbial peptides which will alter the microbiota

28
Q

What disease are gut microbial dysbiosis associated with?

A

IBD, type 2 diabetes, necrotizing enterocolitis

29
Q

What are some causes of microbial dysbiosis?

A

host genetics: mutations in NOD2, IL23R, ATG16L, IGRM

lifestyle: diet and stress

early colonization: birth in hospital, altered exposure to microbes

medical practices: vaccination, antibiotic use, hygiene

disease: increased Th1, Th2, Th17 cells
health: increased Tregs

30
Q

How does the composition of a babies microbial composition differ based on the method of delivery?

A

vaginal: microbiota more resembles vagina of mother
cesarian: microbiota more resembles skin of mother

31
Q

What does an increase in C-sections correlate with?

A

an increase in food allergy

32
Q

What does antibiotic therapy have on the effectiveness of cancer treatment?

A

Antibiotic Treatment Impairs Cancer Therapy

33
Q

What do commensals do?

A

suppress inflammatory responses and protect from disease in the intestines and other organs

34
Q

How do commensals mediate protection?

A

balance Th(Th1 and Th17, pro-inflammatory) and Treg (anti-inflammatory) cells as well as Th1 and Th2 cells

35
Q

What does dysbiosis of gut commensals contribute to?

A

chronic inflammatory diseases (eg IBD)

autoimmunity, allergy, and obesity

36
Q

What can cause dysbiosis?

A

diet, antibiotics, stress, and possibly by early childhood exposure to commensals

37
Q

What can antibiotics that kill commensals result in?

A

alter cancer drug effectiveness

Host Defense Exam 2 (11 decks)

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