Inflammation Flashcards
What are the four cardinal features of inflammation?
Rubor - redness
Calor - heat
Tumor - swelling
Dolor - pain
What causes rubor?
Vascular leakage leads to an accumulation of blood contents, including red blood cells which causes the redness
What causes calor at a site of inflammation?
High metabolism of infiltrating immune cells all generate heat. Also the increased presence of fluid at core body temperature at a site that usually has limited exposure
What is inflammation?
A non specific immune response to cellular injury which is designed to remove damaged cells and clear threats such as infections and pathogens
What are the causes of inflammation?
Pathogens, allergens, physical damage, extreme temperatures, autoantigens
Where can inflammation occur?
Any vascularised tissue
When is inflammation initiated?
When cellular damage leads to the release of Damage Associated Molecular Pathogens (DAMPs) or Pathogen Associated Molecular Pathogens (PAMPs)
What causes swelling at a site of inflammation?
Vascular leakage increases blood flow into the inflamed tissue, leading to tissue buildup
What causes pain in an inflamed area?
Many of the mediators that signal to endothelial and immune cells during inflammation also signal on local nerve cells
What is meant by acute inflammation?
A short term process occuring in response to tissue injury, normally associated with rapid onset and resolution
What is acute inflammation characterised by?
Neutrophil recruitment
What triggers the release of DAMPs and PAMPs?
Non-apoptotic cell death eg due to a wound for example
What vasodilators do mast cells release?
Nitric oxide and histamine
What are the vascular changes associated with the release of histamine and nitric oxide?
- Increase permeability of blood vessel wall
- Dilation
- Plasma leakage
What 4 benefits does increased vascular permeability and leakage into an inflamed site bring? BALP
forms a BARRIER
more ANTIBODIES
more LEUKOCYTE migration
more PROTEINS to the site
Why do we experience pain during inflammation?
Due to the release of prostaglandins
How do neutrophils move to areas of damage?
Via chemotaxis, following a concentration gradient of chemotoxins including C5a, LTB4 and bacterial peptides
What is exudate?
Fluid, protein and cells that have seeped out a blood vessel
What does the exudate form?
A separation between healthy tissue and the inflamed tissue - acts as a physical barrier
How are neutrophils able to migrate towards the chemokine source?
They express complementary chemokine receptors which allow them to migrate towards the course
What is meant by neutrophil extravasation?
The movement of neutrophils from the vasculature into the surrounding tissue to reach the site of inflammation
What are the four steps of neutrophil extravasation?
- Chemo-attraction
- Rolling adhesion
- Tight Adhesion
- Transmigration
What are the two adhesion molecules which are upregulated by cytokines?
P-selectin and E-selectin
How do neutrophils recognise selectin molecules on the endothelium?
They have complementary carbohydrate ligands which bind to the selectin molecules
What is rolling adhesion?
When there is gentle interaction between the selectin molecules and the surface ligands which bind, causing the neutrophils to roll along the endothelium
What is the name of the P selectin ligand?
PSGL1
What promotes the low to high affinity switch in integrins?
Chemokines
What is meant by transmigration?
The movement of the neutrophil through the endothelial wall which involves the cytoskeleton of the neutrophil to be rearranged
What molecule mediates the transmigration of the neutrophil molecule?
PECAM
What are the three functions of neutrophils at the site of inflamation?
- Pathogen recognition
- Pathogen clearance
- Cytokine secretion
How do neutrophils recognise pathogens?
They use the TLR4 receptor to identify lipopolysaccharides that are present in gram negative bacteria for example
How do neutrophils clear pathogens?
By phagocytosis