Mediators of Inflammation Flashcards
How is the action of inflammatory mediators tightly controlled?
They:
- exist as inactive precursors
- they are newly produced when induced
- they are short-lived
What is the function of IL-1β?
- Activates lymphocytes
- Activates the vascular endothelium by enhancing integrin ligand expression
- So increases access of effector cells
What is the primary function of mast cells?
They release histamines
What are the effects of histamine?
Causes arteriolar dilation and increased vascular permeability
Give 2 examples of vasoactive amines
- Histamine
- Serotonin
When is serotonin released?
When platelets have aggregated
What are the effects of serotonin in inflammation?
Causes vasoconstriction during clotting
Which enzyme is responsible for the production of NO?
What is the effect of NO in inflammation?
- Smooth muscle cell relaxation
- Vasodilation
What is the role of NO in macrophages?
Used to breakdown substances
Prostaglandins are metabolic products of what?
Phospholipids
What inhibits the role of dendritic cells?
Prostaglandin 2
Which chemical is used to synthesize prostaglandins?
Arachiodonic acid
What is the role of prostaglandins?
They promote pain and fever
Which enzymes are in involved in the production of prostaglandins?
COX
How do steroids control pain and fever?
They inhibit the action of PLA2 in making arachidonic acid
How do NSAIDs control pain and fever?
They inhibit COX enzymes which prevents the production of prostaglandins
What are the systemic mediators of inflammation?
- Complement system
- Clotting system
- Kinin system
- Fibrinolysis system
What is the function of C3a and C5a?
- Induce mast cells to release histamine
- Act directly on blood vessels to increase vascular permeability
What is the effect of C5a on integrins?
A conformational change
What is the role of bradykinin in inflammation?
It is released in response to tissue damage and so links tissue damage to inflammation
What links the complement to inflammation?
How can tissue injury cause inflammation?
- Release of lysosomal enzymes
- Release of reactive oxygen species
- Release of metabolic products of arachidonic acid
How is IL-1 secretion regulated?
- 2 signals are required for IL-1 to be produced
- The first signal affects gene regulation and produces an inactive precursor protein (pro-IL-1)
- 2nd signal causes activation of NLRP3 to form the inflammasome
What is the inflammasome?
A protein complex which detects pathogens and stress and activates IL-1β and IL-18
Which enzyme is responsible for the proteolytical activation of IL-1β?
Caspase 1
