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HSS4102 > Module 4 > Flashcards

Module 4 Flashcards

1
Q

What is the microbiome?

A

-consists of microbes (native bacteria) that are both helpful and harmful
- symbiotic (both human and microbiota benefit)
- can be pathogenic

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2
Q

If a disturbance in the microbiome occurs, what can happen?

A

dysbiosis

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3
Q

What are two dominant divisions of the Gut Microbiota?

A
  1. Firmicutes
  2. Bacteriodetes
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4
Q

How does the gut microbiota vary?

A
  • intestine anatomical regions
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5
Q

How does the gut microbiota vary in each intestinal anatomical region (x5)?

A
  • physiology
  • pH and O2 tension
  • digesta flow rates
  • substrate availability
  • host secretions
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6
Q

Does each person have a unique gut microbiota profile?

A

Yes

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7
Q

When is each human’s gut microbiota developed?

A

In early life!
depends on infant transitions and external factors (ex antibiotic use)

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8
Q

Does healthy core native microbiota remain relatively stable in adulthood?

A

YES

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9
Q

Is there a unique optimal gut microbiota composition?

A

NO! this is because it is different for each individual
- However, a healthy host-microorganism balance must be respected in order to optimally perform metabolic and immune function and prevent disease development!

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10
Q

What are the 7 roles of the gut microbiome?

A
  1. protect against pathogens
  2. synthesis of vitamins
  3. develop the immune system
  4. promote intestinal angiogenesis (formation of new blood vessels)
  5. promote fat storage
  6. produce SCFA by fermentation of dietary fiber
  7. Modulation of the CNS
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11
Q

How does the gut microbiome “protect against pathogens”?

A
  • produces products with antimicrobial effects
  • causes the bacteria to compete for nutrients present in the gut –> important for colonization resistance
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12
Q

What 3 products are produced by the gut microbiome that have antimicrobial effects?

A

a. SCFAS
b. secondary bile acids
c. bacteriocins

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13
Q

What do bile acids do to protect against pathogens in gut microbiome?

A
  • antimicrobial properties
  • produced in liver
  • excreted into intestinal tract to aid in DIGESTION OF DIETARY LIPIDS
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14
Q

What are bacteriocins and what is one mechanism they use?

A
  • short, toxic peptides
  • inhibit the colonization and growth of other species
  • mechanism: can disturb RNA and DNA metabolism and kill cells through pore formation in cell membrane
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15
Q

What composition factor of the gut microbiota acts as a physical barrier function?

A

inner mucus layer!

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16
Q

What does the gut’s inner mucus layer do?

A
  • impenetrable and firmly attached to epithelium
  • stops bacteria from interacting with epithelium to cause an inflammatory response
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17
Q

What are 4 competition processes that can occur in the gut microbiome to prevent pathogenic colonization?

A
  • nutrient metabolism
  • pH modification
  • antimicrobial peptide secretions
  • effects on cell signaling pathways
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18
Q

How does the gut microbiome “synthesize vitamins”?

A
  • cross-feeding between gut microbes allows for essential vitamins growth!
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19
Q

What are the 2 main vitamins synthesized by the gut microbiota?

A
  1. Vitamin K
  2. B group vitamins (ex: folates, biotin, riboflavin, etc..)
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20
Q

How does the gut microbiome “develop the immune system”?

A

trains and develops major components of the host’s innate and adaptive immune system

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21
Q

Does the immune system orchestrate the maintenance of key features of host-microbe symbiosis?

A

YES!

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22
Q

What is one important tissue that the gut microbes important for maturation of?

A

GALT (Gut Associated lympathic tissue)

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23
Q

What does GALT mediate (x2)?

A
  • immunity
  • immune oral tolerance
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24
Q

What 3 gut bacteria induce GALT formation?

A

1, Bacteroids fragilis
2. Bacillus subtilis
3. PSA

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25
Q

What happens if you are exposed to microbes early in life?

A
  • prevents development of T lymphocytes associated with allergies and IBS
  • enhances T - helper cells (GOOD!!!)
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26
Q

Are microbes required for full complement of T cells and development of B cells in mucosa?

A

YES

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27
Q

What gut microbe bacteria and the type of cell “promote intestinal angiogenesis” and capillarization?

A
  • Bacteriaoides thetaiotaomicron
  • paneth cells
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28
Q

What was seen in germ freee mice and mice with a convention microbiota in regards to fat storage?

A

Germ free = leaner and lower body fat

mice with conventional gut microbiota = higher body fat levels, higher levels of leptin, higher levels of fasting glucose and insulin

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29
Q

How are SCFAs produced?

A

by bacteria through fermentation of nondigestable carbs

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30
Q

What are the 3 main SCFAs?

A
  1. acetate
  2. propionate
  3. butyrate
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31
Q

What do the SCFAs do in the intestinal mucosa?

A

All of them…
- exert anti-inflammatory effects by histone deactylases (HDACs)
- role in microbiota-gut-brain cross talk
- beneficial effect for intestinal epithelial cells and immune cells (via intra and extra celllular processes)

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32
Q

What 2 things does the SCFA “butyrate” do?

A
  1. promote the epithelial barrier function
  2. main energy source for colonocytes
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33
Q

How does the gut microbiome modulate the CNS?

A

symbiotic bacteria may stimulate postnatal development of mammalian brain
- regulate anxiety-like behaviours and emotion behaviour via vagus nerve-dependent regulation of GABA receptors
- important for social behaviour (decreases risk of autism)
- gut-brain communication

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34
Q

could the gut microbiota cause some psychological conditions potentially?

A

YES? –> anxiety (bacteria changed metabolites in blood)

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35
Q

Is the intrauterine environment sterile? if not, why?

A

NO!
- there is non-pathogenic bacteria present in amniotic fluid and placenta of healthy infants found
Therefore, showing a maternal-fetal exchange of microbes

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36
Q

What alters the development of the human microbiome?

A

early-life environmental exposures
–> puts immune system into a hypersensitive and hyperinflammatory state

37
Q

Is an early life microbiome a crucial factor for proper immune development and long term health?

A

YES

38
Q

What in pregnancy is considered a “sterile organ” based on the conventional paradigm?

A

placenta

39
Q

How do adverse pregnancy outcomes occur in relation to microbiome?

A

from microbes that originate from the vaginal tract, ascend to the cervix which then colonizes in the placenta

40
Q

What is another route of transmission of microbes in the placenta of pregnant women that has recently showed interest?

A

Oral cavity! –> may be a reason why women with periodontal disease are at risk of pregnancy complications!

41
Q

Do changes in a woman who is pregnant change the microbiota of her gut, oral cavity, and vagina?

A

YES, though data is not consisent

42
Q

The gut microbiota does not shift throughout pregnancy and increased in richness for both alpha diversity and beta diversity. true or false

A

False
- it DOES shift
- decreased richness of alpha
- increased beta diversity

43
Q

What is the difference between alpha and beta diversity?

A

alpha = measure of microbiome diversity in a single sample
beta = measure of similarity or dissimilarity of two communities

44
Q

what are the 4 ways that the gut microbiota contribute the the necessary weight gain of pregnancy?

A
  1. enhanced absorption of glucose and fatty acids
  2. increased fasting-induced adipocyte factor secretion
  3. induction of catabolic pathways
  4. stimulation of the immune system
45
Q

What are 3 roles that the microbiome has during pregnancy?

A
  1. maintenance of a healthy pregnancy
  2. contribution of fetal development
  3. acquisition of necessary bacteria by the neonate for first days outside the womb
46
Q

What are 4 health problems that are associated with gestational dysbiosis?

A
  1. prepregnancy obesity
  2. IBS
  3. gestational diabetes
  4. preeclampsia
47
Q

What are 3 maternal exposures that could alter the maternal gut microbiota composition, function and availability of microbiota-derived metabolites during pregnancy?

A
  1. diet
  2. stress
  3. infection
48
Q

If there are changes in the availability of the microbiota-derived metabolites from mom, what could happen?

A

cause programmatic effects on placenta and fetal compartment

49
Q

What does stress in the first trimester do to the mother and fetus?

A

alters microbes in vagina
- changes are passed to newborns during birth –> cause changes in their gut microbiome and brain development

50
Q

How does maternal diet have an effect on the microbiota?

A

-having a high fat diet can effect the offspring microbiome
- alter the immune response in offspring
- shapes the composition and diversity of breast milk microbiota

51
Q

Does gestational fruit and vegetable consumption have an effect on the infant gut microbiome?

A

YES

52
Q

What are 7 factors affecting the gut microbiome of fetus/neonate?

A
  1. maternal gut microbiome
  2. maternal skin
  3. mode of feeding –> breastfeeding better than bottle
  4. maternal conditions
  5. early environmental exposure
  6. gestational age
  7. mode of birth
  8. maternal vaginal microbiota
53
Q

What is a well-known component of human milk that favours gut infant colonization with beneficial bacteria called?

A

lactoferrin

54
Q

What are 5 bacteria present during pregnancy in the microbiome?

A
  1. fermicutes
  2. proteobacteria
  3. bacteroides
  4. fusobacteria
  5. actinobacteria
55
Q

What is dysbiosis?

A

where the gut bacteria becomes imbalanced

56
Q

What are some factors that can lead to dysbiosis (x6)?

A
  1. excessive or wrong use of antibiotics
  2. excessive alcohol consumption
  3. increased intake of sugar or protein
  4. frequent use of antiacids
  5. exposure to pesticides
  6. chronic stress
57
Q

What is the “Gut-brain axis”?

A
  • bidirectional communication between the CNS and gut microbiota
  • communicate via endocrine, immune, and humoral links
  • hormones, neurotransmitters, and immunological factors are released from gut and send signals to brain directly or via autonomic neurons
58
Q

What does the vagus nerve do?

A

regulates internal organ functions, vasomotor activity and certain reflex actions (coughing, sneezing, swallowing, vomiting)

59
Q

Does the vagus nerve control communication of microbiota with brain?

A

YES

60
Q

What two neurotransmitters connect the gut and the brain?

A
  1. serotonin
  2. GABA
61
Q

What does GABA do?

A

control feelings of fear and anxiety

62
Q

What is another gut microbe produced that affects brain functioning?

A

SCFAs! (by digesting fiber)

63
Q

What is two thing sthat an SCFA does to brain function?

A

reduces appetite
forms blood brain barrier

64
Q

What is another system that the gut-brain axis is connected to?

A

The immune system!

65
Q

What does the gut microbes role with the immune system?

A

control what is passed into the body and what is excreted

66
Q

What is one inflammatory toxin made by bacteria that can cause inflammation if too much is passed from gut into the blood?

A

Lipopolysaccharide (LPS)

67
Q

How could LPS pass into the blood?

A

from a gut barrier becoming “leaky”

68
Q

What has inflammation and high LPS been associated with?

A

Brain disorders (severe depression, dementia, schizophrenia)

69
Q

What was present in obese people in terms of microbiome?

A

lower bacterial diversity
decreased fecal microbial gene richness

70
Q

What type of diety causes changes in gut microbiome?

A

high fat diet

71
Q

What are the 6 mechanisms of gut microbiota dysbiosis promote induced obesity and metabolic complications ?

A
  1. immune dysregulation
  2. altered energy regulation
  3. altered gut hormone regulation
  4. proinflammatory mechanisms (ex:LPS crossing gut barrier and entering blood)
  5. higher production of SCFAs
  6. use of antibiotics during first 6 months
72
Q

There are well-known co-morbidities of COVID-19 associated with dysbiosis. True or false

A

TRUE

73
Q

What can influence the severity of COVID

A
  • variety and volume of bacteria in gut
  • magnitude of immune response
74
Q

can dysbiosis cause long covid? if so why?

A

YES –> cause a persistent inflammatory symptoms

75
Q

When people had covid, what happened to gut microbiome?

A

loss of commensal gut microbes

76
Q

what are commensal gut microbes?

A

benefical
directly act on host immune system to prevent invasion and colonization of pathogenic microbes

77
Q

What are 6 reasons IBS occurs?

A
  1. gut flora changes
  2. prior infection
  3. psychological stress
  4. gut-brain axis
  5. diet/food sensitivity
  6. pre-post natal factors
78
Q

Once the barrier is breached by influx of inflammatory mediators, pathogens or
any agents that provoke intense immune reactions, severe inflammation occurs
and this will affect the intestinal environment, and changes the gut microbiota
composition. True or false

A

TRUE

79
Q

low grade mucosal inflammation + visceral hypersensitivity + impaired bowl motility = what?

A

IBS!!!

80
Q

What reduction of type of food reduces symptoms of IBS?

A

foods high in fermentable carbohydrates (FODMAP) - short chain carbs that are fermented by gut bacteria into methane and hydrogen gasses but DO NOT GET ABSORBED WELL

81
Q

What could be a fix for IBS with Clostridium difficile infection to restore intestinal homeostasis?

A

Fecal microbial transplant (FMT)

82
Q

What is the “hygiene hypothesis” with IBD?

A

lack of early microbial exposure may reduce tolerance of the adaptive immune response
- we live cleaner, more urbanization, more antibiotic use

83
Q

gut microbiota composition is altered in
patients suffering from T2D, but it is not clear whether these changes are a
cause or simply a consequence of the disorder. true or false

A

TRUE

84
Q

What is the difference between probiotics and prebiotics?

A

Probiotics are foods or supplements that contain LIVE bacteria to maintain or improve the “good bacteria”

Prebiotics, are foods typically HIGH IN FIBERS that are fermented by your gut
bacteria, and act as food for your microflora (may also affect brain health –> could also reduce cortisol levels in body)

85
Q

What are 3 other things known to cause dysbiosis in gut microbiome?

A
  1. sucralose, asparatame, and saccharin
  2. food additives (ex; emulsifiers)
  3. certain restrictive diets (vegan, raw food or clean eating, gluten-free, low FODMAP)
86
Q

What is IBS divided into 2 categories?

A
  1. Crohns disease
  2. Ulcerative colitis
87
Q

Is dysbiosis greater in patients with Crohns or Ulcerative colits?

A

Chrons disease!
- more reduced diversity
- a less stable microbial community

88
Q

What is the difference between Chrons and Ulcerative Colitis

A
  • Crohn’s disease can cause inflammation anywhere in the gastrointestinal tract from the mouth to the anus.
  • Ulcerative colitis can cause inflammation and ulceration in the large intestine
89
Q
A

HSS4102 (7 decks)

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