Chronic inflammation

• What occurs after acute inflammation depends on what?

  1. the amount of tissue damage sustained
  2. whether the causative agent remains
• If the causative agent is destroyed the PMN exudate is replaced with

  a mononuclear exudate
• The mononuclear exudate ?

  • The monocytes are phagocytic ‘macrophages’
  • Monocytes originate in bone marrow where they have a generation life of 24 hours.
  • Monocytes circulate in the blood for 1-3 days 
  • Leave the circulation to become tissue macrophages
  • Accumulate by chemotaxis
  • They begin the demolition phase
• What is the demolition phase?

  macrophages engulf fibrin, red cells, degenerate polymorphs, bacteria and act as scavenger and drain to lymph nodes
• Resolution

  = resolution is the complete return to normal

  Where cellular damage is slight the cellular tissue changes are reversible

  • removal of exudate via lymphatic
  • organ returns to normal
• Is acute inflammatory reaction beneficial 


  usually but inflammatory oedema can endanger life
• Acute inflammation is a vascular phenomenon so can?


  occur in avascular tissue, such as cartilage or cornea
• The tissue response to injury is divided into 3 phases?

  1. initial vascular and exudative phenomena of acute inflammation are followed by
  2. demolition phase
  3. resolution OR if tissue is lost healing by repair and regeration
• When can complete healing ONLY occur?

  • When the acute inflammation and demolition phases are complete
  • the initial cause of inflammation has to be removed
• What is chronic inflammation

  A process in which destruction and inflammation are proceeding at the same time as attempts at healing

  
  

  where tissue damage continues there is a mixture of acute inflammation, demolition, repair and regeneration 
• Denova 


  where the chronic inflammation is primary - there is no preceding acute inflammatory reaction

  this is common
• Granulation tissue 


  New connective tissue that fills the injured area whilst the necrotic debris is being removed.

  It forms where there has been an attempt at healing
• Granulation tissue qualities?

  • a type of fibrovascular tissue
  • reddish
  • soft, moist and bump
  • Painless
  • New small BV, fibroblasts, mononuclear cells in a edematous extracellular matrix
  • Grows at base of wound
• Granulation tissue has?

  • fewer PMNS
  • Lymphocytes and plasma cells
  • Macrophages which remain and sometimes form giant cells
  • proliferation of vascular epithelium via budding forming new capillaries
  • Proliferation of fibroblasts with collagen production
• angiogenesis 


  the formation of new blood vessels
• Granulation tissue is likely to 


  give rise to haemorrhage as it is highly vascular - this is why chronic gingivitis bleeds
• How is granulation tissue formed?

  proliferation and migration of surrounding connective tissue elements. including:

  
  

  • capillary loops
  • fibroblasts
  • inflammatory cells

  
  

  which are initially highly vascular but dev into avascular scar tissue
• Avascular scar tissue formation?

  1. fibroblasts lay down collagen
  2. Scar formation is characteristic of chronic inflam lesions
  3. Lumina of small arteries are obliterated by thickening of tunica intima
  4. = scar tissue
• Lymphocytes 


  form a mobile reserve for other cells eg.plasma cells
• Plasma cells produce

  immunoglobins
• Chronic gingivitis is characterised by?

  • scar tissue
  • massive plasma cell infiltrate
• Regeneration?


  Where tissue is capable of division, regeneration rather than repair takes place
• chronic inflam characteristics?


  • insidious onset
  • long duration
  • pain
  • redness
  • swelling from granulation tissue
  • heat
  • loss of function