the gut microbiome Flashcards
the gut is
the most heavily colonised organ in the body
surface area of GI tract
surface area of a tennis court- 200m^2
where more than…. of all microbes in the body are found
70%
are there more strict anaerobes or facultative aerobes and aerobes
more strict anaerobes
which two phyla dominate the gut
- bacteroidetes
- firmicutes
how many bacterial species
500-1000
where the most bacterial species
the colon
colonisation begins
at brith during passage through the birth canal
–>Intestinal microbiota of infants shows similarities with the vaginal microbiota of their mothers. Infants delivered through caesarean have diff gut microbiota composition compared to vaginal delivered babies.
what effects gut microbiome
genetics and diet
what collectively make up inflammatory bowel disease
crowns disease (CD) and ulcerative colitis (UC)
HMP and IBD
investigating links between microbipme, host and IBD
nod2 and CD
3 polymorphisms in nod2 associated with CD- each polymorphism results in reduced activation of NF-kB in response to bacterial peptidoglycan
Nod2
intracellular sensor for bacterial peptidoglycan
Nod2 function is required
for optimal defence in expression very important antimicrobial peptide- critics component of the innate immune system
obesity and gut microbial ecology
associated with a large shift in the relative abundance of the taxa present- 50% reduction in bacterodeites and a significant increase in firmicutes
–> in mice and human
an ‘obese microbiome’
promotes weight gain when transplanted to a germ-free mouse, compared to a comparable transplantation of a lean micro biome
nod2 is required for
optimal defensin expression
defensins
are very important antimicrobial peptides- critical components of the innate immune systems
IBD5
helps maintain the integrity of the epithelial barrier- association between IBD5 polymorphisms and both UC and CD
IL-23R
susceptible gene for both UC and C. receptor for IL-23R, plays a role in activation and perpetuation of inflammatory response
ATG16L1
polymorphisms restricted to CD and not UC
-gene is part of the autophagosome pathway which has been implicated in handling intracellular bacteria
high levels of adhesive and invasive …. have been reported in CD patients
E.coli
intracellular invasion by AIEC is associated with
active CD and intestinal pathology
many studies have reported an abundance of…. in IBD patients
Enterobacteriacaea
a decrease in Faecalibacterium prausnitzii
has been associated with a UC and highly indicative CD
faecalibacterium prausnitzii
s an anti-inflammatory commensal bacterium identified by gut microbiota analysis of Crohn disease patients–> secreted metabolites from the bacterium promoted production of anti-inflammatory cytokines, whilst inhabiting production of pro-inflammatory cytokines.
anti-inflammatory gut organisms such as faecalibacterium
might be an effective probiotic for treatmentment of CD
when thinking about eradicating certain microbiota like H.pylori (which may cause gastric carcinomas)..
must weigh up potential for unintended implications- microbes have co-evolved with humans and eradication of one or more species may upset the delicate balance that has evolved over the millennia
rDNA from faecal samples of healthy and CD individuals was applied to a microarray
revealing many shifts in microbiota
microarray tools for investigating dysbiosis
study used intro from gut micro biome to design custom phylogenetic microarray- composed of rRNA probes representing around 500 bacterial species from the human and animal gut
NOD 2
NOD2 plays an important role in the immune system. It recognizes bacterial molecules (peptidoglycans) and stimulates an immune reaction.
NOD2 is an intracellular pattern recognition receptor, which is similar in structure to resistant proteins of plants and recognizes molecules containing the specific structure called muramyl dipeptide (MDP) that is found in certain bacteria.
