Gut Immunology Flashcards
What does microbiota mean?
A mixture of microorganisms that makes up a community within an anatomical niche
What does microbiome mean?
Collective genomes of all microbiota in all the different anatomical niches
What host factors stimulate bacterial growth?
- Ingested nutrients
- Secreted nutrients
What host factors inhibit bacterial growth?
- Chemical digestive factors → bacterial lysis
- Peristalsis, contractions, defecation → bacterial elimination
Define dysbiosis
Altered microbiota composition.
What are symbionts in regards to immunology?
Microbiota and humans live with each other but not with benefit or harm to either, they just live
What are commensals in regards to immunology?
microorganisms that benefits from associating with host but has no effect on the host
What are pathobionts in regards to immunology?
Symbionts that doesn’t normally elicit inflammatory response, but under specific conditions can cause dysregulated inflammatory disease.
What causes either equilibrium or dysbiosis (depending on how it is)?
- Infection or inflammation
- Diet
- Xenobiotics
- Hygiene
- Genetics
How can dysbiosis negatively affect the rest of the body?
Through producing bacterial metabolites and toxins
Give 4 examples of bacterial metabolites and toxins
- TMAO: increases cholesterol deposition in artery walls to cause atherosclerosis
-4-EPS: associated with autism
- SCFA’s: short chain fatty acids, decreased numbers are associated with IBD and increased numbers are associated with neuropsychiatric disorders e.g. stress
- AHR ligands, associated with:
- MS
- rheumatoid arthritis
- asthma
What is the first line of defence the body has against pathogens?
Mucosal defence
What are the 3 layers of mucosal defence?
1st- Physical barriers
2nd-Commensal bacteria
3rd- Immunological
What 2 components make up the physical barriers of mucosal defence.
-Anatomical barriers
-Chemical barriers
What is the epithelial barrier of the mucosal defence made up of?
-Mucous layer, made by goblet cells
-Epithelial monolayer with tight junctions
-Paneth cells found in bases of crypts of Lieberkuhn
- Secrete antimicrobial
peptides (defensins) and
lysozyme
What are the two types of lymphoid tissue in mucosal defence?
-MALT (Mucosa Associated Lymphoid Tissue)
-GALT (Gut Associated Lymphoid Tissue)
Where are Mucosa Associated Lymphoid tissues found and where in the body are they particularly concentrated?
-In submucosa below epithelium, concentrated in the oral cavity-pharyngeal palatine…
How big is the GALT?
Largest mass of lymphoid tissue in the body.
What types of immune response is the GALT responsible for?
Both adaptive and innate immune response
What two types of GALT are there?
-Non organized
-Organized
What are peyers patches also known as?
Immune sensors
What are peyer’s patches associated with?
Follicle associated epithelium. (FAE)
What is special about the structure of FAE (follicle associated epithelium).
No goblet cells, no secretory IgA, no microvilli.
What kind cells do peyers patches contain?
Organised collection of Naive T & B cells.
