Inflammation

Question 1

What is inflammation?

Answer 1

A non-specific response to cellular injury designed to remove the cause and consequence of injury

Question 2

What are the four main signs of acute inflammation?

Answer 2

Swelling/oedema
Redness
Heat
Pain

Question 3

What is the immediate response to damaged tissue?

Answer 3

1. Inflammatory signals:
   - Non-apoptotic cell death
   - Detection of foreign material
2. Vasodilators released:
   - Histamine
   - Nitric Oxide
3. Vascular changes:
   - Increased permeability
   - plasma leakage

Question 4

What is exudate?

Answer 4

A fluid barrier:

Fluid, proteins and cells that have seeped out of a blood vessel

Question 5

How does cell recruitment occur?

Answer 5

1. Chemokines are produced
2. Chemokines diffuse out and form a gradient
3. Leukocytes expressing complementary chemokine receptors migrate to the site

Question 6

What is neutrophil extravasation?

Answer 6

1. Neutrophils detect damage by detecting cytokines which causes the upregulation of adhesion molecules
2. Integrins on the surface of neutrophils become active which causes adhesion to the endothelial surface
3. Diapedesis occurs after where neutrophils squeeze through the gaps produces in the endothelial lining by rearranging the shape of it’s exoskeleton

Question 7

What do neutrophils do at the site of inflammation?

Answer 7

1. They recognise the pathogen using TLR4 AND CD14 receptors to detect lipopolysaccharides present in gram-negative bacteria
2. Pathogens are then cleared by phagocytosis or netosis (engulfing the pathogen in a net of DNA extruded from the neutrophil)
3. Cytokines are then secreted to activate and recruit other immune cells

Question 8

How is an acute inflammation resolved?

Answer 8

1. Pathogens wont be detected by immune cells
2. Nuetrophils and inflammatory mediators (Nitric oxide and histamine) have a short half life so degrade
3. Macrophages come and engulf cellular debris
4. The wound is finally healed/repaired

Question 9

What are the benefits of macrophages?

Answer 9

• Phagocytic
• Cytotoxic (but can damage surrouding tissue)
• Anti-inflammatory
• Wound repair

Question 10

What are the negatives of macrophages?

Answer 10

• Cytotoxicity damages cells surrounding pathogen
• Can be inflammatory
• Pro-fibrotic (causes scarring)

Question 11

What are the positive and negative outcomes of acute and chronic inflammation?

Answer 11

Positives:
- Clear inflammatory agent
- Remove damaged cells
- Restore normal tissue function
Negatives:
- Excess tissue damage can occur -> scarring
- Loss of organ function -> organ failure

Question 12

What are the consequences of inflammation?

Answer 12

• Broncho-pneumonia
• Scarring
• Wound healing in sensitive tissues