Gut immunology Flashcards
Why does the gut immologucal system need to have restrained activation?
Surface area is massive-needs a lot of protection. BUT also need to not attack own microbiome, while dealing with TONS of antigen
What is the relation between gut microbiota and immunology?
need a proper gut microbiome to have a proper immunological system
Where is the microbiota most and least abundant?
10^14 (more than cells)-and about 100 times are genomes-provide traits we didn’t evolve
Least in Stomach-with high pH, and highest in colon. Slowly increases from stomach to colon
What is dysbiosis?
Normally, symbionts and commesntals balance with pathogens. Dysbiosis is an imbalance between these-altered microbiota composition
What are the main causes and consequences of dysbiosis?
Abx kill both, and can cause dysbiosis-bacterial metabolites and toxins-causes numerous diseases (like MS, asthma, and tons)
Probably not causes but is related
What are the 1st layers of defence of the gut?
Physical barrier-anatomical and chemical
What makes up the epithelial barrier of the gut?
Mucus layer-goblet cells, Epihtelial monolayers with TJ, Paneth cells (small intestine)
What makes up the immunological defence layers?
MALT and GALT
What is MALT?
Mucosa associated lymphoid tissue. Found in submucosa, as lymphoid mass with follicules
Follicules surrounded by HEV post cappilaty venules for easy entry
What is GALT?
Gut associated lymphoid tissue-responsible for both adaptive and innate immunulty. Still just follcules
has 2 forms-non organised (intra epithelial lymphocytes, lamina propria lymphocytes
Organised-peyers patches (small intestine_, Caecal pathches (large intestine), isolated lymphoid follicules, mesenteric lymph nodes
What are peyers patches
Small intestine-mostly in ileum
Aggregated lympoig follicules covered with follicules associated epothelium (no villi, no mucus, no Iga)
Patch is organised collection of naïve T and B cells. Need microbiota to develop
M cells bring and present AG
Transepithelial dendritic cells also do
What are M cells
In GALT AND MALT-M cell (microfold) in FAE uptake antigen to present to pathc
also produce IgA receptors, facilitating transfer
What are trans-epithelual dendritic cells?
DC that comes and extends an arm through TJ to sample AG and once it finds some, goes to lymph node to present it
What happens when B cells are activated in the gut?
activated (t cell dependen/independent)It migrates to lamina propria where it produes AG. But it can also go to other lymphoid organs. But mostly to lamina propria
If not activated-will leave and free up space
What molecules helps adhesion and entry in the lamina propria?
A4B7 integrins on lymphocytes and MAdCAM-1 on gut epithelium
What is cholera and how does the gut immunology respon to it?
V.Cholerae enters cells and results in exit of ions (water follows)-causes large exit of water
Diarheaeo, dehydration, vomiting
Diagnosis-bacterial culture from stool treatment, dipstick
Treatment-oral rehydration, can have vaccine
What are rotaviruses and their consequences on the gut?
RNA virus that replicated in enterocytes-5types
Most common cause of diarhaeo-oral rehydration is main treatment-transmit oral/touch
Vaccine exits
What is the Norovirus and their consequences on the gut?
called Norwalk virus-RNA virus, incubation 1-2 days
Acute gastroenteritis-transmission faeoco oral
Treatment not necesasary
What is campylobacter?
Cuved bacteria-very common in undercooked meat (poultry)-low effective dose
Treatent not usually required by Abx
What is E.Coli?
6 strains of e.coli are pathogenic- ETEC (2) cause diarheaeo
2 stranfs EHEC (shiga toxin producing)- ureamic syndrome-bad
Enteroinvasive (2)-diarhea
What is clostrum difficile?
Normally present causing no problems. In cases of dysbiosis, then it takes over and survives very long
Treatemnt-isolate patient, stop abx, increasingly difficult to treat
What is Coeliac disease?
AID-glidin (gluten component) is not broken down in stomach, reaches small intestine and IgA (to lamina propria)-activate immune system
Causes abdominal distention, diarrhae
Diagnosis-Ab blood test, biopsy. Treat-diet management (gluten free)
What is irritable bowel syndrome
Mechanism-unusre, but causes hypersensitivy, triggered by diet and stredded
Symptoms-abdo pain, abonram bowel motility, diarrhoea
Treatment-diet modification-avoid the food that causes it. Treat constip-fiber, be less stressed
What is Inflammatory bowel disease
Can be mix of genetics and environemental (dybiosis,, smoking, stress)-destruction of lining and pathogens go to lamina propria, where the regulation of the lymphocytes fails and lead to chronic inflammation-VERY HARMFUL
2 forms-Chrons disease and Ulcerative colitis. 2/3rd of genes are the same
Symptoms-diarrhoae, abdominal cramp, wight loss and fatigue
Only Chrons-happens in ileum and colon, can cause fever, anaemia on top
Ulcerative colitis-only colon, can cause cramping
diagnosis-antibody blood test, etc
Treatment-chrons-immnosupression but surgery isn’t curative. Ulcerative colitis-surgery is curative
