Immunology of the gut Flashcards
What is dysbiosis?
disequilibrium between symbionts and pathobionts
What epithelial cells protect against infections and how?
Epithelial barrier- goblet and paneth cells
paneth cells secrete antimicrobial peptides
Goblet cells secrete mucous
what is MALT? Where is it most commonly found? How is lymphocyte travel allowed?
mucosal associated lymphoid tissue
Found below epithelium
Oral cavity has loads
Surrounded by HEV (high endothelial) postcapillary venules which lymphocytes can travel through
What is GALT? What non organised and organised cells make it up?
How is GALT cleared?
gut associated lymphoid tissue
Non-organised: intra-epithelial lymphocytes, lamina propria lymphocytes
Organised: peyers patches, lymphocytes, caecal patches and mesenteric lymph nodes
Through mesenteric lymph nodes
What is the role of peyers patches?
What kind of epithelium covers them?
What naive immune cells are found here?
Immune sensors
They get this name because they are covered with follicle associated epithelium which has no goblet cells, secretory IgA or microvilli. In other words they are a collection of naive t and b cells
What cell of the peyers patch detects antigens?
What happens after these antigens are detected?
M cells as they have a lot of IgA receptors
What antigen do b cells originally have and what does it turn to?
What is IgA antibodies’ adaptive response in payers patches to an antigen presentation?
IgM to IgA
Switches to igA
Secretory IgA binds to luminal antigen preventing the adhesion of this antigen and invasion
Why do enterocytes and Goblet cells have a rapid turnover?
theyre the first line of defense against pathogens so mayn be directly affected
therefore lesions will be short lived
Describe pathophysiology of cholera
What is it transmission route?
What is the investigation and treatment?
Bacteria reaches small intestine contacts epihtelium and releases cholera toxin
faecal-oral route
stool culture
oral-rehydration
What does the term dual immunological state of the GI tract refer to?
It’s a balance between tolerance to prevent acting against itself and active immune response to fight off pathogens
Where are bacteria most and leastcommonly found in the GI tract?
Colon
Least in stomach as its most acidic
What are the three types of bacteria found in the GI tract and what are they each?
Symbionts- live in GI tract and get benefit from it
Commensals-dont harm host
Pathobionts- no harm but can be tipped over to be pathological in certain environments
What are some causes of disbiosis?
Infection
Diet
Hygiene
Genetics
What are the symptoms, investigation and treatment of cholera?
Symptoms: faecal-oral route via contaminated water, dehydration and watery diarrhoea, vomiting, abdominal pain
Diagnosis: bacterial culture of stool sample (gold standard)
Treatment: oral rehydration, vaccine
What two main virus’ and bacteria can cause infectious diarrhoea?
Virus: Rotavirus in children and Norovirus
Bacterial: salmonella, campylobacter jejuni
