Benefits & Mischiefs from Normal Microbiota 2 Flashcards
Which PRRs are down regulated after birth?
TLR2 and TLR4 on the apical surface
Which PRRs are expressed in endosomes to target bacteria that end up within the cell?
TLR3, TLR7 and TLR9
Which PRR is expressed on the basolateral surface to target bacteria that cross the cell?
TLR5
What stimulates mucin production?
PAMPs on microbiota and butyrate produced by microbiota
What else does PAMP signalling of microbiota stimulate?
proliferation of crypt enterocytes and Paneth cells, release of antimicrobial peptides, induction of regulatory cytokines
How do short chain fatty acids stop inflammatory responses?
by inhibiting NF-kB and production of inflammatory cytokines
Which lymphoid structure develops postnatally?
isolated lymphoid follicles - due to signalling by microbiota
What is physiological inflammation?
inflammation induced by normal gut microbiota that lead to innate and adaptive defences and dont damage the host
What is pathological inflammation?
Inflammation in response to a pathogen
How do lymphoid tissues discriminate between microbiota and pathogens?
PRRs can detect number and proximity to epithelial surface, PRRs detect whether the bacteria has invaded the cell or not, microbiota only bind weakly to TLRs, only pathogens cause inflammasome signalling
Which antibody is produced by B cells in pathological inflammation?
IgG
What is the relationship between gut microbiota and the malnutrition disease kwashiorkor?
The microbiota in the children that get kwashiorkor is different to that of the healthy children - possibly due to the microbiota leading to inhibition of TCA cycle enzymes
What is the relationship between gut microbiota and obesity?
there is different microbiota in obese and non obese individuals where the obese have decreased diversity of microbiota - the decreased diversity leads to insulin resistance and increased serum triglycerides, cholesterol and insulin - there is also altered fermentation possibly leading to increased energy harvest
What is the relationship between gut microbiota and inflammatory bowel disease?
associated with an elevated immune response against gut microbiota and decreased diversity
What is a possible mechanism for inflammatory bowel disease?
defective signalling through PAMP-PRR with microbiota leading to chronic inflammation
What is the relationship between allergies and gut microbiota?
Early microbial colonisation is critical to protecting against allergies - pre and post natal microbial interactions are critical to develop a regulatory phenotype and antibiotics and cleanliness may interrupt this
Which gut microbiota can lead to urinary tract infections?
E coli
Which gut microbiota can lead to LRTI?
klebsiella
What are gut microbiota sometimes a source of for other bacteria?
DNA for virulence of antibiotic resistance
How can gut microbiota cause GIT disease?
By overgrowth e.g. candida causing diarrhoea or clostridium difficle causing pseudomembranous collitis
What type of bacteria is clostridium difficile?
gram positive, anerobic, spore forming rod
What causes overgrowth of clostridium difficile?
changes to gut microbiota e.g. by antibiotics or cytotoxic drugs
How does clostridium difficile cause pseudomembranous colitis?
It adheres to the mucosal epithelium and produces cytotoxic toxins that cause cell death, inflammation and bowel necrosis
What is the treatment for clostridium difficile?
metronidozole and vancomycin
Which patients have a greater incidence of recurrent clostridium difficile infections?
Patients who have had an appendectomy and who have reduced diversity of microbiota
What unusual treatment is very successful in treating clostridium difficile?
feacal transplants - to re establish normal microbiota
What are prebiotics?
dietary supplements that promote beneficial bacteria
What are probiotics?
a live organism that when ingested in adequate amounts exerts a health benefit on the host
Do prebiotics and probiotics help?
Unclear - difficult to find a high quality RCT on them
