collectins and defensins Flashcards
(13 cards)
what are collectins
collectins are part of the innate immune system
the are soluble pttern recognition receptors
aid the idetnficiation of antigens to prevent infection
recognise oligosaccharide regions of microorganism to initate phagocytosis and aggregation
vital for cell immunity
work with denfensins
high abundance in areas of high exposure such as GI ttract, resp and skin
first identified in avelolar space and secreted by clara cells
structure
chromosome 10
8 members- collectin placenta, liver,43,46, surfactant a and d and mannose binding lectin
have a calcium depending carbohydrate binding head
alpha coiled coil
and triple collagen helix
structure differs between the membrs of the family
role in general
aggregation and and phagocytsosis
mediates clearance - trapping pathogen in mucus layer
involvs antigen presenting cells such as dendritic cells
t cell proliferation
chemotaxis - increase colonisation diversity of hpylori when deficient of surfactant d
the
mackay 2016
treatment resistant asthmatic patients mild asthma and non control cohorts found that decrease in bronchoaveloar lavarage and increase in serum surfactant d leakage potentially a biomarker in serum may play role in persistence
low study body and funded by astrozenca
evidence for roles
surfactant binds to the surface of bacteria virus or fungi and to the lps of the gram neg bacteria
causes aggregation and increases phagocytosis by macrophages and neutrophils
found in gastric mucosa and is upregulated by h.pylori
murray 2002 binding to hplyori inhbiitrs its motility
however khamri 2005 - variants in hpylori lps means thatit can escape surfactant d binding
needed for dendritic cells to take up h.pylori and if not present, dendritic cells do not do this
study with mouse dieficent and non deficient - spleen taken to assess t cells and then stomach isolated for urease, pcr and neutrophils
khamri 2007
found that decrease in t cell proliferation, increase in sucetibility to infection and decrease in neutrophil infilteration
what are defensins
small catonic antimicrobial peptides
isolated from neutrophils macrographs and also in panel cells
function
act a chemokine towards these immune cells through CCR6 receptor
in stomach function to encotuner foreign antigens due to their location in mucosal surface
secrete HD into crytps in response to bacteria
cryptdin alpha defensin type- antibacterial defense
protective role where HD5 mice show improvement in ressitance to infection with salmonia - role to prevent bacterial multiplication and entry into intestine wall
structure
chr 8, cysteine rich with disulphide bonds
consists of alpha and beta defensin
alpha more abundant
alpha in paneth cells with HD5 and 6
beta in epithelial cells in different organs HB1 and HB2
what are cryptdins
alpha denfsins
synthesis a biological inactive precursor which requires processing to make peptides which express antimicrobial acitivity
this is conducted by mmp7 ezyme to active it
mmp7 deficiency found to lack crypdin and have accumulation of precpusor with decrease antimicrobial atiivty
supports role of densfin and mmp7 in antbacterial denfense
recombinant hd5
activeagainst ecoli listeria candida albican swhich can act in presence of trypsin and hostile environmentsl
its action is to aid pore formation and membrane permilibisisation
disutption to bacteria energy metabolism and interfere with biosynthetic pathay
dendritic cell role
denfence alpha chemochine for dentrticicells at low conc for their activity increase cytokine in activated monocytes
beta also chemotactive for immature dc and t cells
hamanaka
beta defensins increased in gastric mucosa with h.yplor
in epithelium
incuation of hpylori with HD decrease growh grade and inhibited proliferation t high conc
disease
graddock 2008
increase alpha in cancer and inflammation
decrease HD56 and crohns and necrotising enteroclitis in newborns
imbalance in acne
increase in schizophrenia potential biomarker
