Flashcards in Microbiota 1 Deck (64):
how many commensals in/on us?
microbiome provides us with extra source of?
humans and microbiota are known as:
how many bacteria in microbiota?
how many species of bacteria on us?
majority of bacteria use oxygen?
99.9% are anaerobes
Gram what in
Throat and skin
Throat/ skin: +ve
4 main bacteria phyla from most to least
2. firmicutes (clostridia, mollicutes)
4. proteobacteria (E.coli)
each body site has low or high diversity of microbiota?
twins have the same microbiota?
share <50% of bacterial species
microbiota unstable in host?
stable but influenced by determinants
4 things microbiota contribute to:
6 factors that influence gut microbiota?
mode of delivery
age (more diversity with age)
diet (breast milk)
genetics/environment (rural vs. city)
vaginal birth associated with rapid acquisition of?
animal based diets do what to microbiota?
decrease plant metabolizing bacteria, more bile-tolerant bacteria
what does iron do to mice microbiota?
does microbiota of mice treated with amoxicillin/metronidazole and bismuth recover?
which antibiotic do you not recover your diversity of microbiota?
microbiota provides how much calories?
10% of calories from plant CHO
microbiota in nutrition does 2 things to help us
1. change our genes for CHO/lipid metabolism
2. maintain enterocyte differentiation/function
microbiota taxa varied by site, what remained stable?
metabolic pathways eg. 16S rRNA
what vitamins do microbiota make for us?
vitamin B12, K
what happens to bile acid in the gut?
microbiota break it down to desoxycholic acid to reabsorb back into liver
what happens to amino acids in gut?
nitrogen recycling from lysine and threonine
what does bacterial degradation of host glycans do?
elicits synthesis of new glycans by host
how does microbiota maintain enterocyte differentiation
from production of short chain fatty acids from fibre
is angiogenesis affected by microbiota?
describe the metabolism path of dietary fibre:
broken into monosaccharides>fermented into SCFAs>absorbed by colon>reaches liver>substrates for gluconeogenesis/lipgenesis
how do the colonic epithelial cells get their energy?
from fermented and absorbed SCFAs
SCFAs do more than just be energy source, explain:
control colonic gene expression via HDAC inhibition and GPCR signal regulation
mucosal immune systemis closely associated with?
what is MALT?
mucosa-associated lymphoid tissue
SI covers how many square metres? so what?
400m2, big antigenic challenge, which is why it has the largest collection of lymphoid tissue
2 big things the MALT must be able to do
protection from pathogens (IgA)
tolerance to normal microbiota/food
what is ILFs? where are they found?
isolated lymphoid follicles in large/small intestine
where are Peyers patches? what happens there?
induction of T, B Cells
enterocytes secrete what cytokines?
TGF-B, chemokines, anti-microbial peptides
what is lactoferrin? where does it come from on the small intestine?
from Goblet cells
inhibits bacteria growth
Paneth cells do what?
what immune cells are in the lamina propria of the small intestine?
Intraepithelial lymphocytes (IEL)
2 kinds of Intraepithelial lymphocytes in the villus?
what two cells in the small intestine play a role in tolerance?
IEL (intraepithelial lymphocytes)
3 innate defences of gut?
peristaltic (flushing) action
mucous layer to hold commensals at 'arms length'
Describe the 3 innate defensive roles of enterocytes
1. barrier: integrity is critical tight junctions
2. antimicrobial factors
What is a mechanism for controlled antigen access?
M Cells/ dendritic cells
innate leucocytes include:
What are ILCs? what do they do?
innate lymphoid cells
what does IL-17, IL-22 do?
recruits and activates neutrophils
What does lymphoid tissue inducer cells do?
stim DC, T, B cells, PPs, ILFs
what cytokine does IELs secrete?
what does IL-22 do?3 things
enhances antimicrobe defence
What are MAIT cells? what do they do?
mucosal associated invariant T cells
rapid response to bacterial antigen
what do invariant NKT cells do?
secrete pro-inflamm cytokines like IL-22
M cell stands for? where is it?
directly over the lymphoid aggregates (PPs, ILFs isolated lymphoid follicles)
villi on M cells?
folded luminal surface
M-cell secrete mucous? why?
microbial access easier
DCs are located directly below the M-cell, how do they sample? 2 ways:
directly (tentacle into lumen)
indirectly (via goblet/M-cells
TGF-B stands for?
transforming growth factor
tell me what DCs do in:
1. steady state
2. inflamm state
1. induce Tregs/TGF-B
2. induce Th1/Th17
DCs bias what immunoglobulin from B-cells?
Isotype switching to IgA
inducing mucosal addressin a4B7 on T/B cells does what?
1. allows to bind to MAdCAM1 on mucosal surfaces
2. also gives chemokine receptors specific for lamina propria
a4B7 activated T/Bcells are found where?
distributed through all mucosal surfaces
IELs do what to enterocytes?
may eliminate damaged ones