innate immunity Flashcards
what are the innate immune mechanisms of the oral cavity?
- barrier functions
- saliva
- initiation of innate immune responses
- recognition of threats
- signalling pathways initiating immune responses
- cytokines and chemokines
what is innate immunity?
first line of nonspecific defence against the oral microbiota
- no lasting memory
what is adaptive immunity?
specific and acquired
what is humeral response mediated by?
mediated by antibody molecules that are secreted by plasma cells
“liquid” “fluid”
blood
yellow bile
black bile
phlegm
how does immune system respond to infection? 3
- tissue homeostasis is essential
- commensals (organisms doesn’t cause disease) elicit low level immune response
- pathogens destroyed in hours and rarely causes disease
when does the innate immune response occur?
first line of defence
1-4 days
why is the innate immune response effective?
regular contact with potential pathogens which are destroyed within minutes or hours only rarely causing disease
is the innate immune response specific or nonspecific?
non specific
does innate immune response allow for protective immunity?
no memory or lasting protective immunity
what does the epithelium (physical barrier) do in innate immunity?
- produce antimicrobial peptides
- produce cytokines and chemokines
what are the innate cell subsets in innate immunity?
- phagocytic cells (macrophages, neutrophils)
- antigen presenting cells (dendritic cells)
what does the chemokine and cytokines do in innate immunity?
- chemokine = cell recruitment
- cytokine = cell activation/ proliferation
what is the rile of the physical barrier (epithelium)?
epithelial barriers produce a number of different compounds
what compounds do epithelial barriers produce in the oral cavity?
- antimicrobial peptides
- immunoglobulins (secretory IgA)
- lactoferrin
- lysozyme
- cystatins
what is the function of antimicrobial peptides?
to kill microbes (binding to cell wall, attaching to surface and disrupt membrane) and modulate immune system.
name 4 major families of antimicrobial peptides?
b - defensins
human neutrophil peptides (HNPs)
cathelicidins
psoriasis proteins
at what concentration are antimicrobial peptides most effective?
effective at low concentrations
how does secretory immunoglobulin S (SlgA) form a protective layer?
absorbing saliva
what does dimeric form of SlgA allow for?
attachment to multiple microbes
what does secretory immunoglobulin A do?
binds and neutralises pathogen and toxins externally and internally.
what is lactoferrin?
glycoprotein that transports iron ions but has antimicrobial activity
- present in saliva
produced by neutrophils
what is lysozyme?
targets cell wall of bacteria
- present in saliva
- produced by macrophages/ neutrophils
what is cystatins?
anti-protease activity
supports remineralisation of teeth
what does the epithelium do in responding to pathogenic threats?
acts as a physical and immunological barrier
what protects the epithelium in immune response?
salivary components and their broad spectrum antimicrobial activity
what receptors do cells involved in immune responses have?
receptors for components of microorganisms
what are microbial agents?
toxins and virulence factors
what actives the immune response in microbial regions?
receptor activation
what are the main receptors?
Toll-like receptors
what are the other type of receptor for fungi?
diction and gluten
what are the other type of receptor for bacteria ?
NOD-like receptors
what are the other type of receptors for microbial and allergen recognition?
protease-activated receptors
what are the main roles for the other receptors?
- promote phagocytosis of microbes
- promote activation of immune cells
what are PRRs ?
Pattern Recognition Receptors
what can PRRs recognise?
Pathogen Associated Molecular Patterns PAMPs
describe the host cell pathogen interaction sequence?
bacteria (lipopolysaccharide/lipoteichoic acid)>
TLR4 or TLR2
then
TLR2>
NF-kB (transcription factor)
cytokine/chemokine transcription - nucleus
cytokine/chemokine translation and processing
cytokine/chemokine secretion
then inflammatory response
what size are cytokines?
small <80kDa
what are cytokines?
signalling molecules to coordinate immune responses
name and describe the 3 functions of cytokines?
AUTOCRINE = alter behaviour of cell from which they were secreted eg. self regulating
PARACRINE = alter behaviour of neighbouring cells
ENDOCRINE = entree circulation and alter behaviour of distant cells
what do cytokine receptors recognise and what happens?
recognise cytokines
induces conformational changes in majority of receptors intracellularly
what is the difference between cytokines and chemokines?
chemokines = tell immune cells where to go (movement)
cytokines = tell immune cells what to do
what are chemokines?
small signalling proteins - chemotactic cytokines
= involved in recruitment(directing)
what is chemotaxis?
movement of a cell in a direction corresponding to a gradient of increasing and decreasing concentration of a particular substance (chemokines)
what are the 4 classes of chemokines?
how many members do they each have?
C chemokines = 2
CC chemokines = 31
CXC chemokines = 18
CX3C chemokines = 1
what produced the chemokines CXCL8?
monocytes
macrophages
fibroblasts
epithelial cells
endothelial cells
what are the receptors for chemokine CXCL8?
CXCR1
CXCR2
what does the oral mucosa produce to prevent infection?
Anti Microbial Peptides (AMPs)
Secretory IgA
Lactoferrin
Lysozyme
Cystatins
how do you initiate inflammatory responses?
activation of intracellular signalling pathways which lead to ‘switching on’ of genes
