Chronic Inflammation

Question 1

Causes of Chronic Inflammation

Answer 1

1. Persistent/recurrent injury or infection
2. Immune mediated diseases
3. Prolonged exposure to potentially toxic agents

Question 2

How long of an inflammation makes it chronic?

Answer 2

Weeks to months

Question 3

What causes persistent/recurrent injury or infection

Answer 3

1. Micro-organisms that are difficult to eradicate

2. Patient factor (immunosuppression, poor vascular supply)

Question 4

What causes immune mediated diseases

Answer 4

1. Autoimmune diseases (eg. Rheumatoid Arthritis, Systemic Lupus Erythematosus(SLE))
2. Micro-organisms (eg. inflammatory bowel disease)
3. Common environmental substances (eg. Bronchial Asthma)

Question 5

What toxic agents can cause chronic inflammation?

Answer 5

Exogenous Agents:
Nondegradable inanimate material inhaled for prelonged periods (eg. Silica, Asbestos)

Endogenous Agents:
Lipid components (Artherosclerosis)

Question 6

What colour is asbestos fibre microscopically?

Answer 6

Black :(

Question 7

What are the features of chronic inflammation?

Answer 7

1. Inflammatory cells (Lymphocytes, Macrophages, Plasma cells, Eosinophils, Mast Cells, Granulomas)
2. Tissue Destruction
3. Attempts at regeneration and repair (Angiogenesis, Granulation tissue)
4. Fibrosis (Scar formation)

Question 8

What are Granulomas?

Answer 8

Aggregate of specialised macrophages and Langhans multinucleated giant cells

Question 9

What is a feature of plasma cells?

Answer 9

They have more cytoplasm than lymphocytes

Question 10

What is granulation tissue?

Answer 10

It is highly vascularised connective tissue

Question 11

How is granulation tissue formed?

Answer 11

Capillaries are derived from vascular proliferation of adjacent healthy tissue at the periphery. Fibroblasts migrate with the capillaries to the injured area and there is accumulation of collagen (fibrosis). It is stimulated by growth factors (eg. VEGF) produced by macrophages and endothelial cells.

Question 12

How does scar tissue look like microscopically?

Answer 12

Long elongated fibroblast cells (Spindle cells) with pink collagen lines.

Question 13

Why is scar tissue found in damaged heart muscles?

Answer 13

This is because heart muscles cannot be regenerated.

Question 14

What is granulomatous inflammation?

Answer 14

It is a distinct pattern of chronic inflammation which is a cellular attempt to contain offending agent that is difficult to eradicate. It is made of granulomas which is specialised epithelioid macrophages occuring in aggregate with multinucleated (~30 nuclei) Langhans giant cells. These granulomas are surrounded by lymphocytes, plasma cells and fibrosis.

Question 15

What are some possible causes of granulomatous inflammation

Answer 15

• Infections (eg. Tuberculosis, syphilis, fungal infections)
• Foreign body reactions
• Autoimmune conditions (eg. Sarcoidosis)

Question 16

What are some systemic effects of inflammation?

Answer 16

• fever
• loss of appetite
• sleepiness/tiredness
• headache
• raised acute phase protein (C-reactive protein)
• Leukocytosis (increased WBC count)

Question 17

How is inflammation biologically tracked?

Answer 17

By checking levels of acute phase protein (C-reactive protein)

Question 18

What are some consequences of defective inflammation

Answer 18

• increased susceptibility to infection

- delayed wound healing