Pattern Recognition Receptors Flashcards
What is the role of pathogenic bacteria and fungi
Phagocytosis and killing of cells
Role of viruses
Cellular shut-down, cellular resistance
What are PAMPs
General molecular features common to many types of pathogens
Give an example of a PAMP
Lipopolysaccharides
Viral and bacterial nucleic acids
Protein found in flagellum
What are PRRs
A family of proteins which recognise and bind to a variety of pathogen ligands
What two forms are PRRs found in
- Secreted
2. Cell-associated
How do TLRs and PRRs drive cytokine production
- They activate
2. Antigen-presenting cells can increase the likelihood of a successful T cell activation
Name two PRRs secreted in lining fluids from epithelia and phagocytes
- Defensives
2. Cathelicidin
Role of defensives
Disrupt bacterial membranes as they are POSITIVELY charged
Role of cathelicidin
Disrupts microbial membranes
What is the role of lectin and collections
Bind carbohydrates or lipids in microbe walls
- Activate complement and improve phagocytosis
Role of pentraxins
- Antimicrobial
- Reach with C protein of pneumococci
- Activate complement
- Promote phagocytosis
Example of pentraxins
C-reactive proteins
Where are TLR (Toll-like receptors) found
Macrophages, dendritic cells and neutrophils
Role of TLRs
Recognise and bind to PAMPs
Describe the physiological stages that take place after binding to a TLR
Second messengers are generated within the immune cell which lead to secretion of IL-1, IL12 and TNF-alpha
Stimulate activity of immune cells involved in innate immune response
Role of IL-1, IL-12 and TNF-alpha
Inflammatory mediators
Why are Toll proteins called receptors
They are PLASMA-MEMBRANE bound
induce second-messenger formation
What do TLRs bind to
Extracellular Ligands
How do TLRs recognise endogenous damage molecules
They have characteristics of hydrophobicity + if they appear in unfamiliar contexts
What are the roles of Nod-like receptors
Detect intracellular microbial pathogens
Name two microbial pathogens detected by NLRs
Peptidoglycan
Muramyl Dipeptide
What are the three main NLRs
NOD1
NOD2
NLPR3
Where is NOD2 expressed
Everywhere
Role of NOD2
Recognises MDP
What is MDP a breakdown product of
peptidoglycan
Role of NOD2
Activates inflammatory signalling pathways + anti-viral signalling
What does a non-functioning mutation of NOD2 lead to
Crohn’s disease
Two examples of RLRs
RIG-I
MDA5
Role of RLRs
Detect intracellular doubt stranded viral RNA and DNA
Activates INF production
Why is Toll-like receptor 4 different to the other 3
Very little amounts of lipopolysaccharides are needed to cause a signal
What do mannose receptors respond to
Fungi
Role of Dectin-1 receptors
Recognise beta gluons in fungal wall
Where are scavenger receptors found
Macrophages
Where do viruses multiply
In the cytoplasm of cells
What factor does blood neutrophil numbers depend on
TLR4 (not effected by LPS)
Name three extracellular damage molecules
Fibrinogen
Hyaluronic Acid
Tenascin C
Three examples of intracellular damage molecules
Heat shock proteins
HMGB1
mRNA
stathmin
What TLR is used in vaccinations
TLR4
