Gut Microbiota and Immunity Flashcards
Human Microbiome
the combined genetic matter of the micro-organisms residing on the human body.
Microbiota
the micro-organisms which reside in a particular community e.g. gut microbiota, skin microbiota
How do the mouth and oesophagus defend against disease?
Mouth - flow of liquid, saliva, antimicrobials (IgA), and microbiota.
Oesophagus - flow of liquids, peristalsis and reverse (vomit)
Why are asthmatics more likely to get an infection?
Steroid inhalers could kill the mouth microbiota
How does the stomach defend against disease?
- Acidity - pH 2-3. Parietal cells secrete the gastric acid.
- Mucous - secreted by Goblet cells.
- Antimicrobials - Beta Defensins
Which bacteria can survive in the Stomach?
Helicobacter Pylori
How does the Small Intestine defend against disease?
- Flow of hut contents
- Peristalsis
- Mucous
- Secretory IgA - can pass through membranes
- Antimicrobial peptides - A Defensins
- Microbiota
Small Intestine Bacterial Overgrowth
Overgrowth of bacteria in the intestine. Can lead to various symptoms e.g. diarrhoea, malabsorption. Associated with IBS. Certain drugs have been implicated; proton pump inhibitors and opioids.
How does the Large Intestine defend against disease?
- Peristalsis
- Mucous
- Shedding and replication of epithelium
- Microbiota
What is E. Hystolytica?
Bacteria which adheres to epithelial layer of gut wall. Causes disease in 10% of cases. Secretes an enzyme which cleaves mucin and disrupts the mucous layer.
What is the difference between Commensal, Symbiotic and Parasitic Bacteria?
Commensal - human gets no benefits, bacteria gets benefits.
Symbiotic - both human and bacteria get benefits
Parasitic - human gets disease, bacteria gets benefits
Name 3 common and ‘friendly’ bacteria.
Lactobacillus, Bifidobacterium, and Bacteroides.
They are acid producing, which promotes an acidic environment which is less favourable to harmful bugs. And they also produce Bacteriocins, antimicrobial peptides which harm other types of bacteria.
Why is the gut microbiome important for human health at the micro level?
- Prevents colonisation of pathogens.
- Ferment unused energy substrates (e.g. fibre) and mucous to produce useful metabolites (short chain fatty acids) beneficial for health (e.g. butyrate).
- Synthesise and excrete vitamins.
- Influence release of gut hormones influencing digestion/metabolism of food and appetite.
- Interacts with immune system.
What is the link between the GIT and the immune system?
The GIT is part of the primary immune system. It contains 60% of the body’s total immunoglobulins and over 10mil lymphocytes per gram tissue. GI microbiota have a strong influence on the development of local and systematic immunity and regulation of immune functions including regulating the balance between responding to pathogens and “immune tolerance” so that the immune response doesn’t harm the host.
Why is the gut microbiome important for human health at the macro level?
Lower bacterial diversity has been associated with loads of diseases e.g. inflammatory bowel disease, psoriatic arthritis, coeliac disease, type 1 diabetes mellitus, atopic eczema and obesity.
It is all thought to be due to the interaction between microbes, food and our immune system.
