Mucosal immunity Flashcards
what are the features of comensals?
no histone damage
- designed to live with you
what are the common features of mucosal barriers?
Outer mucus layer- traps commensals and potential pathogens
Inner mucus layer- contains anitgen and antimicrobial peptides
Epithelial cells- kept as far from the lumen, and so potential pathogens as possible
why do we need immunity in the respiratory tract?
- Exposure to inhaled antigens and allergens
- Common site of infection
- Needs to be able to respond to “bad” bacterial but not respond to “good” bacteria
- Needs to avoid damage
what does tolerogenic mean?
wont respond to minor stimuli
what are the common features of mucosal barriers?
Outer mucus layer- traps commensals and potential pathogens
Inner mucus layer- contains antigen and antimicrobial peptides
Epithelial cells- kept as far from the lumen, and so potential pathogens as possible
what are the precursor cells to macrophages?
Monocytes
what is the result of oxidized alveolar lung fluid?
It is less of a barrier to infection
- caused with ageing
what are ILCs?
Innate Lymphoid cells
what are innate lymphoid cells?
they have no antigen receptors
- Respond to cytokines and signals from epithelial cells
what cytokines to cytotoxin ILCs release?
perforin/granzyme
IFN-g
TNF
what do ILCs help fight in an immune response?
Viruses
Cancer
Chronic inflammation
why do we need immunity in the GI tract?
- the gut has 10^14 ‘foreign’ bacterial cells
- exposure to food antigens
- common site of infection
- needs to be able to respond to “bad” bacterial but not to “good” bacteria
how does the gut enact its immune function?
The gut has a specialised structure to allow antogen sampling and local immune responses
what is the Peyer’s patch in the GI tract?
Secondary lymphoid tissue
- contaisn T, B and plasma cells
what is the roll of Tregs in the gut?
Maintain a non-inflammed state
what is the role of M cells in the GI tract?
Allow some translocation of bacteria across the cell membrane
where are M cells found in the GI tract?
In the Follicule Associated epithelium
- a region ontop of the peyers patch
what is the roll of paneth cells in the GI tract?
Make antimicrobial peptides
- important for maintaining sterile environment
what are DAMPs?
dammage associated molecular patterns
how does the gut keep homeostasis?
commensal bacteria do not lead to DAMP presentation
pathogenic bacteria lead to DAMP presentation
what are pro-inflammatory cytokines?
IL-6
IL-12
IL-23
what leads to tolerance in the GI tract?
Treg activation- no inflammatory response
what leads to an inflammatory response in the gut?
T cell activation
what happens during TLR-dependent expression of DAMPs?
upregulated production of antimicrobial peptides
what is the role of migrating dendritic cells in the immune response in the gut?
can induce T and B cell activation in the mesenteric lymph nodes
what is the role of the mesenteric lymph node?
has the ability to make gut associated lymphoid tissue
- holds lots of immune cells
what is the role of M cells?
Activated peyers patch is situ
what cells are found in the outer layer of the gut mucosal surface?
CD8+ T (resident memory) cells
what is the stream of cell maturation in the gut?
Central memory cell
to
Presursor memory cell
to
Effector cell (recruited into the tissue by cytokines)
how does age affect gut immunity?
Age-related changes in gut-microbial communities and associated declines in intestinal tissue function may fuel inflammaging, creating a vicious cycle further impacting host-microbiome interactions
