Inflammation Flashcards
What are the clinical signs of inflammation?
erythema
oedema
heat
pain
What is inflammation?
The body’s response to tissue injury
What causes inflammation?
chemical agents
cold, heat
trauma
invasion of microbes
Why have inflammation?
serves to destroy, dilute or wall off the injurious agent and induce repair
BUT can be potentially harmful in uncontrolled
What is barrier immunity?
What are active barrier defences?
physical barrier of protection e.g. skin, lungs, gut
active barrier defence e.g. cilia, secretions, anti-bacterial peptides
Describe the innate immune defence
Provides a rapid local response to pathogens
Ready to activate at any time
No memory
No specificity
Preprogrammed, generic response
Recognition by pattern recognition receptors
Which cells of the immune system recognise the threat?
Professional Antigen Presenting Cells (APC’s)
- mast cells
- dendritic cells
- macrophages / monocytes
Which cells of the immune system contain and destroy a threat?
Phagocytes - neutrophils - macrophages Granulocytes - neutrophils - eosinophils - mast cells / basophils
What are the main three proteins of the innate immune system? Give the function of each
Acute phase proteins - e.g CRP - opsonise or present pathogens Cytokines - chemical signals which modulate cell activity or attract cells (chemokines) Complement - multiple funcitons - opsonisation, killing, activation chemo-attraction
Give an overview of the three stages of the acute phase response
Recognise problem - danger signal - recognised by innate immune cells Response - cellular activation/recruitment - cytokine/complement activation Deal with problem - phagocytosis/destruction of pathogen - resolution of inflammation or recruitment of adaptive immune response
Describe the proteins involved in recognising a threat
Pathogens are recognised by Pattern Recognition Receptors (PRR’s)
These are on every innate immune cell
PRR’s recognise pattern-associated molecular patterns (PAMPs) that occur on microbes
- but not in humans so distinguish self from non-self
Which cells are responsible to initiating the acute phase?
mast cells
- detect injury
- release histamine and other mediators
- initiating inflammatory response
What are the effects of histamine?
vasodilation
endothelial junction widening (increased permeability)
irruption of nerve endings (itch)
What are the other important mediators of inflammation?
Arachidonic acid metabolites (eicosanoids)
- prostaglandins and thromboxanes
- COX pathway
- cause vasodilation and probing oedema
- but also protective (gastric mucosa)
- COX blocked by aspirin and NSAIDs
Leukotrienes
- lipoxygenase pathway
- are chemotaxis and vasoconstrictors
- cause increased vascular permeability and bronchospasm
- leukotriene receptor antagonists (e.g. monteleukast) used in asthma
In what situations/conditions can it be useful to block inflammatory mediators? x3
Histamine
- useful in allergy to block histamine induced vasodilation
Arachidonic acid metabolites
- block progtaglandins and COX pathway with NSAIDs and aspirin to reduce pain and fever
- prostaglandins - used in pulmonary hypertension
Leukotrienes
- used in asthma to reverse leukotriene induced bronchospasm