Innate machanisms Flashcards
Lectures: -Week 1, day 2, lecture 2: Innate immunity - Pattern recognition receptors -Week 1, day 2, lecture 3: Innate immunity - The complement system (52 cards)
What are pattern recognition receptors?
Receptors that recognize patterns that are often found on pathogens
What is a PAMP?
Pathogen-associated molecular pattern, can be recognized by PRR’s
What is a DAMP?
Danger-associated molecular pattern; endogenous molecules that signal danger
What are the three main groups of PRR’s?
- Free receptors in the serum
- Membrane-bound signaling receptors
- Cytoplasmic signaling receptors
Which are the subgroups of the group of free PRR’s in the serum? (4)
- Complement proteins
- Pentraxins
- Collectins
- Ficolins
What are the subgroups of the membrane-bound PRR’s? (3)
- Toll-like receptors (TLR)
- C-lectin receptors (CLR)
- Scavenger receptors
What are the subgroups of the cytoplasmic PRR’s? (3)
- NOD-like receptors (NLR)
- RIG-I-like receptors (RLR)
- Cytosolic DNA sensors
What is the main structural difference between plasma membrane-bound TLR’s and endosomal membrane-bound TLR’s?
Plasma membrane-bound TLR’s are usually dimers, whereas endosomal TLR’s are usually monomers
What do plasma membrane-bound TLR’s recognize?
Patterns on the outside of pathogens
What do endosomal membrane-bound TLR’s recognize?
RNA/DNA in the cytosol
Why is TLR4 an important TLR?
Recognizes LPS -> major component of bacteria
In what way can TLR4 on multiple cells be activated by LPS from a single bacterium?
LPS-binding protein extracts LPS from the bacterium -> bacterium is not bound to one cell
What is an important adaptor molecule for intracellular TLR’s?
TRIF -> leads to the production of type I interferon via IRF3 activation
In what way does the system of TLR’s provide redundancy?
Many TLR’s use the same pathway -> a defect in one of the TLR’s does not prohibit the activation of the immune pathway
What do C- type lectin receptors (CLR’s) recognize? Against which class of pathogens are they especially effective?
Carbohydrate structures; often found on fungi -> important for defence against fungal infections
Where are CLR’s located?
CLR’s are always bound to the plasma membrane
What does the ‘C’ in C-type lectin receptors refer to?
Calcium-dependent
What is the main adaptor molecule for CLR signaling? What kind of response does it induce?
Syk; induces release of IL-23, resulting in a Th17 antimicrobial response that defends epithelial surfaces
What is a symptom of a CLR-mutation?
Frequent candida infections
What are the NOD-like receptors?
A family of receptors with similar NOD-like domains
Where are NLR’s located?
In the cytoplasm
When are NLR’s activated? What does this result in?
NLR’s are activated upon dimerization, resulting in the activation of NF-κB
When are TLR’s activated?
TLR’s are often activated upon dimerization
What is an inflammasome?
The inflammasome is a complex of molecules in the cytoplasm of the cell, activated by NLR’s
The inflammasome cleaves pro-IL-1β into IL-1β through the caspase-pathway
