Infection and immunology Flashcards
What is restrained activation of the gut? WHy must this occur?
Where the gut is primed to react to pathogens
- Due to massive antigen load because of high surface area and high microbiota
- It is both tolerance and immunoreactivity
What is the role of the microbiota?
Development of the immune system components
Provide traits that we have not needed to evolve ourself
- function as virtual organ
- provide ability to digest and metabolise
Why might bacterial populations vary in the GI?
DIfferent conditions
- some too hostile - stomach’s low pH
What are the types of microbiota?
Symbionts
- help us and provide nutrients
Commensal
- prevent adherence of pathogens to eptihelial wall
Pathogens
- cause inflammation
What is dysbiosis? What might cause this?
Imbalance of microbiota
Diet Antibiotics Infection Hygiene Genetics
What are the effects of dysbiosis?
Systemic diseases
Brain, lung and liver disorders
Outline the types of mucosal defence
Physical
- anatomical and chemical
Commensal bacteria
- prevent joining
Immunological - post-invasion
- MALT and GALT
Epithelial
- Paneth cells for lysozyme production
- Tight junctions
- mucous layer
What is MALT?
Mucosa associated lymphoid tissue
- lymphoid mass containing lymphoid follicles
Follicles are surrounded by HEV venules
What is GALT? HOw does it provide production? What are the two forms?
Innate immunity and adaptive response
Non-organised
- intra-epthelial, has T cells, NK cells
Organised
- Peyer’s patch -small intestine
- Caecal patch -large intestine
- Isolated lymphoid follicle
- Mesenteric lymph nodes
What are Peyer’s patches? Describe the organisation and brief composition
Immune sensors
Aggregated with lymphoid follicles
- follicle associated epithelium
- cant make IgA
- no goblet cells and little microvilli
Organised collection of naive T cells and B cells
Decelopment requires exposure to bacteria
Antigen uptake by M cells M cells express IgA receptors - facilitates transfer of IgA complex Also by dendritic cells - sample - doesnt compromise the tight junction
Is IgA dimeric of monomeric in the gut?
Dimeric as it is a SECRETORY form of IgA
how many mucosal layers does the large intestine have?
2 - Outer and inner
Outer is thicker - rich in lymphocytes
Outline lymphocyte honing and circulation from secondary lymphoid tissue, such as GALT and Peyer’s patches
Release to meet AG to activate
If no meeting, it returns
It will roam until it meets
What is MAdCAM-1?
An integrin, responsible for activation and honing of lymphocytes, back to the gut
What is the mechanism for choelra infection?
VIbrio cholerae reach small intestine
Close contact with epithelia leads to cholera toxin release
Cholera toxin enters cell, starting cascade that leads to ion exit
How is cholera diagnsoed and treated?
Bacterial culture from stool sample
Oral-rehydration
Vaccination
How is cholera transmitted and what occurs?
Faecal oral root
Dehydration
What are rotaviruses? Give treatment
RNA virus, replicate in enterocytes
Most common cause of diarrhoes
Live attenuated vaccine
What are noroviruses?
RNA virus
Closed communities
Acute gastroenteritis
What is campylobacter?
C. jejuni
Undercooked meat
Low dosage
antibiotic treatment
How many enterotoxigenic E cloi are there?
6 types
bloody diarrhoea
What is c difficile?
Antibiotics stimulates dysbiosis
Bloody diarrhoea
Isolate patient, v v contagious
Stop antibiotics, use specific ones
Treat also by faecal microbiota transplantation
What is coeliac disease? Symptoms? Diagnosis? Treatment?
GLIADIN not broken down, reaches small intestine and bings to sIgA, leads to production of inflammatory cytokines
- leads to inflammation
Distension, diarrhoea
Ab blood test, biopsy
GLuten free diet
What is Irritable BS? Symptoms? Diagnosis? Treatment?
Stress, visceral hypersensitivity
Abdominal pain, abnormal bowel movement
Diet modification, treatment of pains, stress management, fibre for constipation
What is Inflamm BS? Symptoms? Diagnosis? Treatment? Two types?
Merchansim
Genetic and env factors lead to impaired barrier function
- Microbial product enters, causing immune cell activation
- chronic inflammation occurs - failure of stoppage
- fibrosis and stenosis hence occurs
Crohn’s and Colitis
Crohn’s and Colitis differences?
Crohns
- distal ileum and colon
- patchy inflammation
- diarrhoea
Colitis
- colon onlky
- chronic continuous inflamm
- diarrhoes
- Anti-inflammatory drugs, i
Diagnose by Ab blood test, endoscopy
