Chronic inflammation

Question 1

Overview

Answer 1

Inflammation, repair and continued tissue destruction occur simultaneously
Lasts weeks, months or years

Question 2

Causes of chronic inflammation

Answer 2

Result of previous acute inflammation which failed to
resolve:
• foreign body, grit, retained sutures
• Non-vital tooth causing continued chronic inflammation
at the root apex
• Poor healing due to inadequate blood supply

Question 3

Chronic and low grade from outset

Answer 3

Usually in response to chronic low grade stimuli
• Certain micro-organisms such as mycobacteria
responsible for tuberculosis
• Prolonged exposure to toxins e.g. silica responsible for
silicosis; atherosclerosis- response to lipids in plasma
• Autoimmune disease- body mounts an inflammatory
reaction against a component of ‘self. e.g. rheumatoid
arthritis

Question 4

Features of chronic inflammation

Answer 4

Minimal vascular changes
Infiltration by chronic inflammatory cells-macrophages,
lymphocytes and plasma cells
Repair- vascular granulation tissue (fibroblasts +
endothelial cells)- may mature to give scarring
Continued tissue destruction- inflammatory agent or
inflammatory cells

Question 5

Macrophages

Answer 5

Derived from blood monocyte –> IFN-γ T cells –> activated macrophage
Phagocytosis
Antigen presentation - stimulate immune response
Growth factors
-stimulation of fibroblasts & endothelial cells to promote healing
Cytokines and chemokines attract inflammatory cells and regulate inflammatory response

Question 6

Lymphocytes

Answer 6

T cells (cell mediated immunity) move from blood to tissues in response to cytokines (produced by macrophages)
Macrophages and T cells activate each other
T cell immune regulation –> cytotoxic T cell killing // activate humoral immunity (B cells) –> plasma cells and antibodies

Question 7

Eosinophils

Answer 7

Resemble neutrophils but
have eosinophilic
cytoplasm.
Important in parasitic
infections
Asthma, type I sensitivity reactions

Question 8

Tissue destruction

Answer 8

Products of activated macrophages suchs as free oxygen, proteases
Necrotic tissue promotes further inflammation
Release of enzymes by neutrophils
Cytotoxic T cells
Products of micro-organisms

Question 9

Repair: two mechanisms

Answer 9

1. Regeneration
   - complete resolution to normal tissue
2. CT deposition and scar formation
   - occurs in tissues not capable of complete regeneration or where there has been prolonged, severe damage

Question 10

Granulation tissue

Answer 10

Fibroblasts
Endothelial cells
Stimulated by growth factors from macrophages

Question 11

Granulomatous inflammation e.g. in TB

Answer 11

Distinct pattern of chronic inflammation - formation of ‘granulomas’ (giant cells)
-epitheliod macrophages
-multinucleate giant cells
-lymphocytes
Certain micro-orgainsms e.g. mycobacterium which causes TB, syphilis, leprosy
Certain immune reactions e.g. Crohn’s disease; sarcoid
Response to foreign material e.g. sutures

Question 12

Multinucleate giant cells

Answer 12

Form by fusion of macrophages

• foreign body type (non-caseating?)
• Langhans type (nuclei form neatly round edge) - caseating?

Question 13

TB

Answer 13

Cell mediated immune response Th1 and mycobacterium–> activates macrophages –> Continued Th1 response (hyersensitivity) to organisms –> granuloma