Benefits & Mischiefs from Normal Microbiota 2

Question 1

Which PRRs are down regulated after birth?

Answer 1

TLR2 and TLR4 on the apical surface

Question 2

Which PRRs are expressed in endosomes to target bacteria that end up within the cell?

Answer 2

TLR3, TLR7 and TLR9

Question 3

Which PRR is expressed on the basolateral surface to target bacteria that cross the cell?

Answer 3

TLR5

Question 4

What stimulates mucin production?

Answer 4

PAMPs on microbiota and butyrate produced by microbiota

Question 5

What else does PAMP signalling of microbiota stimulate?

Answer 5

proliferation of crypt enterocytes and Paneth cells, release of antimicrobial peptides, induction of regulatory cytokines

Question 6

How do short chain fatty acids stop inflammatory responses?

Answer 6

by inhibiting NF-kB and production of inflammatory cytokines

Question 7

Which lymphoid structure develops postnatally?

Answer 7

isolated lymphoid follicles - due to signalling by microbiota

Question 8

What is physiological inflammation?

Answer 8

inflammation induced by normal gut microbiota that lead to innate and adaptive defences and dont damage the host

Question 9

What is pathological inflammation?

Answer 9

Inflammation in response to a pathogen

Question 10

How do lymphoid tissues discriminate between microbiota and pathogens?

Answer 10

PRRs can detect number and proximity to epithelial surface, PRRs detect whether the bacteria has invaded the cell or not, microbiota only bind weakly to TLRs, only pathogens cause inflammasome signalling

Question 11

Which antibody is produced by B cells in pathological inflammation?

Answer 11

IgG

Question 12

What is the relationship between gut microbiota and the malnutrition disease kwashiorkor?

Answer 12

The microbiota in the children that get kwashiorkor is different to that of the healthy children - possibly due to the microbiota leading to inhibition of TCA cycle enzymes

Question 13

What is the relationship between gut microbiota and obesity?

Answer 13

there is different microbiota in obese and non obese individuals where the obese have decreased diversity of microbiota - the decreased diversity leads to insulin resistance and increased serum triglycerides, cholesterol and insulin - there is also altered fermentation possibly leading to increased energy harvest

Question 14

What is the relationship between gut microbiota and inflammatory bowel disease?

Answer 14

associated with an elevated immune response against gut microbiota and decreased diversity

Question 15

What is a possible mechanism for inflammatory bowel disease?

Answer 15

defective signalling through PAMP-PRR with microbiota leading to chronic inflammation

Question 16

What is the relationship between allergies and gut microbiota?

Answer 16

Early microbial colonisation is critical to protecting against allergies - pre and post natal microbial interactions are critical to develop a regulatory phenotype and antibiotics and cleanliness may interrupt this

Question 17

Which gut microbiota can lead to urinary tract infections?

Answer 17

E coli

Question 18

Which gut microbiota can lead to LRTI?

Answer 18

klebsiella

Question 19

What are gut microbiota sometimes a source of for other bacteria?

Answer 19

DNA for virulence of antibiotic resistance

Question 20

How can gut microbiota cause GIT disease?

Answer 20

By overgrowth e.g. candida causing diarrhoea or clostridium difficle causing pseudomembranous collitis

Question 21

What type of bacteria is clostridium difficile?

Answer 21

gram positive, anerobic, spore forming rod

Question 22

What causes overgrowth of clostridium difficile?

Answer 22

changes to gut microbiota e.g. by antibiotics or cytotoxic drugs

Question 23

How does clostridium difficile cause pseudomembranous colitis?

Answer 23

It adheres to the mucosal epithelium and produces cytotoxic toxins that cause cell death, inflammation and bowel necrosis

Question 24

What is the treatment for clostridium difficile?

Answer 24

metronidozole and vancomycin

Question 25

Which patients have a greater incidence of recurrent clostridium difficile infections?

Answer 25

Patients who have had an appendectomy and who have reduced diversity of microbiota

Question 26

What unusual treatment is very successful in treating clostridium difficile?

Answer 26

feacal transplants - to re establish normal microbiota

Question 27

What are prebiotics?

Answer 27

dietary supplements that promote beneficial bacteria

Question 28

What are probiotics?

Answer 28

a live organism that when ingested in adequate amounts exerts a health benefit on the host

Question 29

Do prebiotics and probiotics help?

Answer 29

Unclear - difficult to find a high quality RCT on them