The Gut Microbiome in Metabolic Disorders Flashcards Preview

MD1 Metabolism > The Gut Microbiome in Metabolic Disorders > Flashcards

Flashcards in The Gut Microbiome in Metabolic Disorders Deck (36):
1

What is the microbiome?

Collection of microorganisms and their genes and proteins living within our mucosae, skin, and secretions

2

What is the exposome?

Environment

3

What are the two most dominant phyla in the colons of healthy adults?

Firmicutes
Bacteroidetes

4

What are the Firmicutes mainly made of?

Gram positive Clostridia

5

What are the Bacteroidetes mainly made of?

Gram negative Bacteroides

6

Are the less important phyla functionally important?

Yes

7

What are the two approaches to sequencing the microbiome?

16S ribosomal sequencing
Metagenomic shotgun sequencing

8

How does 16S ribosomal sequencing work?

Takes areas common to most bacteria in 16S ribosomal subunit gene and amplifies it
Those areas that are different are also amplified
On this basis, bacteria can be separated

9

What is the speed and ease of 16S ribosomal sequencing?

Simple
Fast
Straightforward to analyse

10

What does 16S ribosomal sequencing report?

Operational taxonomic units, not sequences of species

11

Does 16S ribosomal sequencing resolve well at the species level?

No

12

What are the shortcomings of 16S ribosomal sequencing?

May fail to resolve substantial fraction of diversity
Not ID novel/highly diverged microbes
Can't resolve biological functions associated with taxa

13

How does metagenomic shotgun sequencing work?

Microbial and human DNA separated
Microbial DNA randomly sheared into short segments > sequenced > re-assembled

14

Does metagenomic shotgun sequencing reveal microbial genes that are active?

No, only those that are present

15

What is alpha diversity?

Measure of species diversity within sample

16

What is beta diversity?

Measure of diversity between samples

17

What is dysbiosis?

Disturbance/imbalance in biological system

18

How is a newborn baby seeded with microbiota?

Vagina
Gut
Skin
Breast milk

19

What are the dominant species in the vagina with which the baby is seeded?

Lactobacillus
Prevotella

20

What does a healthy microbiome do in a baby?

Induces maturation and maintains integrity of
- Gut
- Immune system
- Neurological system
- Others
Protects against infection
Produces nutrients and vitamins
Utilises energy > regulates metabolism and weight

21

What happens to the breast milk microbiome after elective C-section?

Altered

22

What childhood diseases is C-section associated with?

Allergic rhinitis
Asthma
Coeliac disease
Type 1 diabetes

23

What evidence is there to show that the microbiome regulates development of type 1 diabetes?

Incidence of T1D in wild mice very low
More than half of mice reared in specific pathogen free environments developed T1D
All mice reared in germ-free environment, and had no microbiome, developed T1D

24

What does diet protection against autoimmune diabetes need?

Microbiome

25

What is the relationship between gut microbial diversity and seroconversion to clinical type 1 diabetes?

Decrease in diversity with seroconversion
Significant decrease in diversity with diagnosis T1D compared to controls

26

How does the gut microbiome change in children with type 1 diabetes?

Diversity decreases
Actinobacteria and Firmicutes decreased
Bacteriodetes increased
Butyrate-producing species within Clostridium decreased

27

How are short-chain fatty acids, such as butyrate, produced?

Bacteria ferment undigested starch

28

What do short-chain fatty acids do?

Maintain epithelial integrity
Absorbed > go to
- Liver
- Muscle
- Brain
- Etc
Anti-inflammatory
- Bind and activate GTRs
- Inhibit histone deacetylases

29

How does a fast food diet change the gut microbiome?

Decreases diversity
Has many additives affecting microbiome

30

What is the gut microbiome like in type 2 diabetes?

Fewer butyrate-producing bacteria
More opportunistic pathogens > can cause infections

31

What is a better predictor of insulin resistance than BMI?

Metagenomic signature

32

Is there evidence that a faecal microbiota transplant cures anything?

No clear evidence that it cures anything except recurrent C difficile infection

33

How did things change in people with metabolic syndrome with the transfer of gut microbiota from lean donors?

Increased insulin sensitivity
Increased diversity in faecal microbiome
Butyrate-producing bacteria increased

34

Is obesity transmissible by gut bacteria?

Yes

35

What are the issues with probiotics?

Contain only few bacteria
Evidence for passage to large bowel
Varying resistance to acid and bile across species and strains
Lack of randomised clinical trials

36

What are prebiotics?

Food parts that promote specific changes in growth/activity of gut bacteria to confer health benefit to host
Examples
- Non-digestible carbohydrates
- Phytochemicals = chemicals in plants