Acute inflammation

Question 1

Define acute inflammation and what are some common causes?

Answer 1

immediate / early response to injury (mins-days)
Causes:
- infection (bacterial, viral etc)
- physical inflammation e.g. burns 
- chemical agent 
- immune response 
- tissue death 
Any form of tissue injury will induce acute inflammation

Question 2

What are the consequences of acute inflammation?

Answer 2

can be beneficial e.g. bacterial killing, removal of dead tissue
can also be harmful - lung damage in pneumonia, kidney damage in acute pylonephritis
May precede chronic inflammation, healing and repair

Question 3

What are the 2 main components of acute inflammation?

Answer 3

1) vascular response
- vasodilation (erytherma)
- odema - increased permeability
- leukocyte margination

2) inflammatory cell infiltration
- mainly neutrophils (1st line defence)
- macrophages (later stages)
- lymphocytes may also be involved

Question 4

What happens during increased permeability?

Answer 4

protein-rich fluid escapes into extravascular space
increased concentration of RBCs = congestion
increased blood viscosity
reduced blood flow = stasis

Question 5

What happens during leukocyte margination?

Answer 5

loss of axial streaming
first stage in process of leukocyte emigration - allows them to come into contact with endothelial lining
- the initial increase in blood flow leads to leukocyte margination

Question 6

What are the phases of leukocyte margination?

Answer 6

1) margination = movement to periphery of blood vessels (mainly related to stasis)
2) rolling = transient weak binding to endothelium by selectins
3) adhesion = firm adhesion to endothelium by integrins
4) transmigration = movement into extravascular space by platelet endothelial cell adhesion molecule-1

Question 7

What is involved in the control of leukocyte migration ?

Answer 7

interaction between leukocyte receptors and ligands on endothelial cells
- regulated by cytokines and chemokines

Question 8

Define chemotaxis:

Answer 8

migration along chemical gradients

Question 9

What are some examples of chemotactic substances?

Answer 9

bacterial products, complement components (C5a), leukotrienes, chemotactic cytokines (attract leukocytes and activate receptors)

Question 10

What is the process of phagocytosis?

Answer 10

1) recognition and attachment of particle to leukocyte - opsonins
2) engulfment - pseudopods surround particle, form phagocytic vacuole
3) killing and degradation - production of ROS, release of lysosomal enzymes

Question 11

What are the general aspects about the chemical mediators involved in acute inflammation?

Answer 11

may be locally produced or systemic
most act on specific receptors expressed on target cells 0 mediator function tightly regulated
others act in a non-specific manner

Question 12

What are some different examples of suppurative (purulent) inflammation?

Answer 12

Pus

• mainly neutrophils, necrotic cells and bacteria
• complication of infection with pus forming bacteria - pyogenic (specific type of pus forming bacteria)

Abscess
- localised collection of pus

Question 13

What are diseases with lymphocytes rather than neutrophils?

Answer 13

acute viral hepatitis - A, B, C
viral meningitis e.g. coxsackievirus, mumps
viral myocarditis e.g. coxsackievirus, echovirus

immune mediated diseases
- autoimmune hepatitis

Question 14

What are the main inflammatory cells in viral myocarditis?

Answer 14

lymphocytes

Question 15

What is the sequel of acute inflammation?

Answer 15

resolution - limited injury, return tissue to normal state
scarring/fibrosis - more extensive damage, tissues with limited capacity to regenerate, abscess formation
progression to chronic

Question 16

What are the classic clinical features of acute inflammation?

Answer 16

1) heat (calor)
2) redness (rubor)
3) swelling (tumor)
4) pain (dolor)
HALLMARKS

Question 17

What is also apparent in acute inflammation?

Answer 17

raised WBC count - mainly neutrophils

• particularly high pyogenic bacteria
• also present in non-infective causes (myocardial infarction)
• neutrophil rich leukocytosis in other body fluids

if rich in lymphocytes instead it is more likely to be a viral infection

Question 18

What are examples of hereditary defects in leukocyte function?

Answer 18

chronic granulomatous disease

Question 19

What are examples of acquired defects in leukocyte function?

Answer 19

leukaemia

Question 20

What is a broad spectrum anti-inflammatory treatment?

Answer 20

NSAIDs- inhibits cyclooxygenase enzymes involved in arachidonic acid production which produces prostaglandins

Question 21

What is a targeted anti-inflammatory treatment?

Answer 21

therapies blocking specific chemical mediators or receptor ligand interactions e.g. anti-TNF ab, anti-ICAM-1