Gut Microbacteria and Immunity

Question 1

What are the levels of gut defences?

Answer 1

• Physical
• Innate immunity
• Acquired immunity

Question 2

What are the host defences in the mouth?

Answer 2

• Flow of liquids
• Saliva
• Antimicrobials
• Microbiota

Question 3

What are the host defenses in the oesophagus?

Answer 3

• Flow of liquids

- Peristalsis

Question 4

What is the pH of the stomach?

Answer 4

2

Question 5

What are the host defenses in the stomach?

Answer 5

• Acid pH
• Antimicrobials
• Mucus

Question 6

What is hypochlorhydria?

Answer 6

Production of hydrochloric acid in gastric secretions of the stomach and other digestive organs is absent or low

Question 7

What are the host defenses in the small intestine?

Answer 7

• Flow of gut contents
• Peristalsis
• Mucus
• Bile
• Secretory IgA
• Antimicrobial peptides
• Microbiota

Question 8

What are the host defenses in the large intestine?

Answer 8

• Microbiota
• Peristalsis
• Mucus
• Shedding and replication of epithelium

Question 9

What does it mean if a bacteria is “commensal”?

Answer 9

• Derives food or other benefits from an organism without hurting or benefitting it
• May become pathogenic if circumstances are right

Question 10

What does it mean if a bacteria is “symbiotic”?

Answer 10

It benefits the host and the bacteria

Question 11

What does parasitic mean?

Answer 11

The bacteria benefits from the relationship whereas the host is harmed by the relationship

Question 12

What are probiotics?

Answer 12

• A bacteria which is introduced into the body for its beneficial qualities
• Lactic acid-producing
• Produce bacteriocins

Question 13

Give 3 examples of probiotics?

Answer 13

• Lactobacillus spp.
• Bifidobacterium spp.
• Bacteroides spp.

Question 14

What are prebiotics?

Answer 14

• Non-digestible food ingredients
• Food/nutrients for gut bacteria
• Stimulate growth and activity of gut microbiota

Question 15

As you go down the GI tract what happens to the density of bacteria?

Answer 15

Increases

• Oesophagus 10^3 - 10^5
• Large bowel >10^10

Question 16

How many more bacteria are present in the body than human cells?

Answer 16

There are roughly 10x more bacteria than human cells in the body

Question 17

What is the role of gut microbacteria?

Answer 17

• Prevent colonisation by pathogens
• Excrete useful metabolites
• Ferment unused energy substrates
• Synthesise and excrete vitamins
• Produce hormones

Question 18

What is bacteriotherapy?

Answer 18

• The purposeful use of bacteria or their products in treating an illness

Question 19

What are the factors controlling gut microbiota?

Answer 19

• Physiological status
• Underlying disease
• Intestinal secretions
• Intestinal motility
• Immune mechanisms
• Enviromental factors
• Use of antibiotics

Question 20

What is the primary immune organ in the body?

Answer 20

• GI tract

- Contains 60% of total immunoglobulins and > 10 million lymphocytes per gram tissue

Question 21

What substances recognise pathogen/microbe associated molecular patterns (PAMPs/MAMPs)?

Answer 21

• TLRs: Toll-like receptors
• NODs: Nucleotide-binding oligomerization domain-containing proteins
• NLRs: NOD-like receptors

Question 22

What is NF-kB?

Answer 22

• Transcription factor (nuclear factor kappa-light-chain-enhancer of activated B cells
• Transcribes pro-inflammatory genes
• Secretion of cytokines and chemokines such as TNF and IFNy

Question 23

What can cause intestinal infection?

Answer 23

• Ingestion of infected food and water
• Ingestion of bacterial toxins
• Use of oral antibiotics

Question 24

What is enterocolitis?

Answer 24

Inflammation involving the mucosa of both small and large intestine

Question 25

What is diarrhoea?

Answer 25

• Abnormal faecal discharge characterised by frequent and/or fluid stool
• Result of disease in small intestine
• Involves increased fluid and electrolyte loss