Chronic Inflammation and Healing

Question 1

Chronic Inflamm: Causes

Answer 1

• Unresolved acute inflammation
• Prolonged exposure to agent eg. silica wear particles from prosthetic implants
• Autoimmune disease states eg. Crohn’s

Question 2

Chronic Inflammation

Answer 2

• Will persist until the damaging stimulus is eradicated

- If damaging stimulus is eradicated -> organisation and repair (always going to get some form of scar tissue)

Question 3

Chronic Inflammation: Main cell types

Answer 3

• Lymphocytes
• Macrophages
• Plasma cells
• Mast cells
• Fibroblasts
• Eosinophils
• • no neutrophils

Question 4

Chronic Inflammation: Macrophages

Answer 4

• Produce chemokines, cytokines and growth factors (TNF, TGF-beta, IL-1)
• > cell influx
• > fibroblast proliferation
• > stimulate angiogenesis
• > activation and recruitment of lymphocytes
• Participate in bacterial and cell killing
• Clear extracellular debris, fibrin and other foreign material

Question 5

Chronic Inflammation: Lymphocytes

Answer 5

• T cells: in cell mediated immunity

- B cells: in humoral mediated immunity, differentiate into plasma cells which produce antibodies

Question 6

Chronic Inflammation: Plasma cells

Answer 6

• Terminally differentiate in to B cells

- Produce antibodies

Question 7

Types of Healing

Answer 7

• Regenerative: tissue replaced with parenchymal tissue eg. fracture healing
• Non-regenerative healing: healing occurs by replacement with CT scar, not functioning parenchymal cells eg. MI

Question 8

Organisation and Repair

Answer 8

Occurs when:

• Tissue that are incapable of division eg. heart and muscle OR
• Extensive tissue and framework destruction
• Healing process is repair by deposition of collagen and other ECM components resulting in a scar
• Scar is formed by an intermediary tissue: granulation tissue

Question 9

Granulation Tissue: Components

Answer 9

• Macrophages and other mononuclear cells clear away the debris
• Angiogensis
• Fibroblasts -> collagen -> scar

Question 10

Stages of Granulation Tissue

Answer 10

1. Vascular granulation tissue: network of newly formed capillaries, macrophages and support cells which replace the are of tissue damage (mainly angiogenesis)
2. Fibrovascular granulation tissue: proliferating fibroblasts, capillaries and macrophages (activating fibroblasts)
3. Fibrous granulation tissue:
   - Fibroblasts synthesise collagen and align themselves so collagen is deposited in a uniform pattern
   - Contraction frequently occurs, size of damaged area is reduced

Question 11

Local Factors Influencing Wound Healing

Answer 11

• Infection
• Mechanical factors eg. wound on knee
• Foreign bodies
• Size, location, type
• Vascular supply

Question 12

Systemic Factors Influencing Wound Healing

Answer 12

• Metabolic status eg. diabetes
• Hormones
• Immunosuppression
• Age
• Nutrition