Chronic inflammation Flashcards
What are the 3 purposes of inflammation?
1) Remove the cause of injury
2) Remove necrosis (dead tissue)
3) Initiate repair
Although inflammation has a purpose, give 2 ways in which it can be damaging?
1) Can damage nearby tissues and be destructive
2) Can be inappropriate - chronic inflammatory disease
What are the 3 kind of cells that predominate in chronic inflammation?
1) Plasma cells
2) Lymphocytes
3) Macrophages
What is the difference between chronic and granulomatous inflammation?
Granulomatous inflammation is a specific type of chronic inflammation
Granulation tissue and scar tissue are formed in chronic inflammation, can they also be formed in acute inflammation?
Yes, but they are more abundant in chronic inflammation
What are the 4 main differences between chronic and acute inflammation?
1) Chronic has a slow onset - days - months
Acute has a quick onset - mins - hours
2) Chronic often has more subtle clinical signs
Acute has very prominent clinical signs
3) In chronic, plasma cells, lymphocytes and macrophages predominate
In acute neutrophils are the main cell involved
4) Chronic is severe and progressive
Acute is often mild and self limiting
What is meant by primary chronic inflammation?
Primary chronic inflammation has all the histological features of acute inflammation but there is no initial of acute inflammation
Does acute inflammation always lead to chronic inflammation?
No in most cases acute inflammation doesnt lead to chronic inflammation as the acute inflammation resolves the problem
In what 2 ways can acute inflammation lead to chronic inflammation?
1) Acute inflammation can progress to chronic inflammation
2) Recurrent episodes of acute inflammation can lead to chronic inflammation
What is the most common type of acute inflammation to lead to chronic inflammation?
Suppurative (pus-forming) type
Give 5 causes of primary chronic inflammation?
1) Some infections
2) Primary granulomatous disease
3) Endogenous material
4) Exogenous material
5) Some autoimmune
Describe how suppurative acute inflammation can progress to chronic inflammation?
1) Pus forms an abscess which is deep-seated
2) Drainage is delayed and the abscess forms thick walls made from granulation and fibrous tissue
3) Rigid walls of the abscess fail to come together after drainage and the stagnating pus becomes organised by the in growth of granulation tissue to be replaced by a fibrous scar
Give an example of a condition in which recurrent episodes of acute inflammation lead to chronic inflammation?
Cholecystitis
Multiple recurrent episodes of acute inflammation lead to replacement of gall bladder wall muscle with fibrous tissues
Predominant cell type becomes lymphocyte rather than neutrophil polymorph
Presence of indigestible material also favours progression to chronic inflammation, what particular kind?
Indigestible material is resistant to the action of lyzosomal enzymes - foreign bodies tend to provoke a specific type of chronic inflammation called granulomatous inflammation - this causes macrophages to from multinucleate giant cells called foreign body giant cells
What are the main types of lymphocytes involved in chronic inflammation?
1) Plasma cells which produce Ab
2) T cells which produce cytokine which have an important role
What is the macroscopic appearance of chronic inflammation?
Depends on the type and the type of tissue
What are the 5 most common macroscopic appearances of chronic inflammation?
1) Chronic ulcer - eg. chronic peptic ulcer, base is lined by granulation tissue and fibrous tissue extends through the muscle layer
2) Chronic abscess cavity
3) Thickening of wall of hollow viscus
4) Granulomatous inflammation presence of granulomas - with or without caseous necrosis
5) Fibrosis - may become most prominent feature when most of the chronic inflammatory cell infiltrate has subsided
What are the predominant features in repair of tissue from chronic inflammation?
Angiogenesis followed by fibroblast proliferation and collagen synthesis resulting in granulation tissue
What are the microscopic features of chronic inflammation? 5
1) Lymphocytes, plasma cells and macrophages
2) Few eiosinophils may be present, very few neutrophils
3) Some macrophages form multinucleate cells
4) Exudation fluid is not prominent
5) May be production of new fibrous tissue from granulation tissue
What is granulation tissue?
Important component of healing, comprises small blood vessels in a connective tissue matrix with myofibroblasts
What is a granuloma?
An aggregate of epithelioid histocytes and other cells - lymphocytes and histiocytic giant cells
Appearance may be augmented by the presence of caseous necrosis
What is a common feature of the many of the stimuli that induce granulomatous inflammation?
Indigestibility of particulate matter by macrophages
What does the association of eiosinophils with granulomas indicate?
Often indicates parasitic infection
What is the role of macrophages in chronic inflammation, what do they respond to and where are they derived from?
1) Respond to chemotactic stimuli
2) Macrophages in inflamed tissue are derived from monocytes that have migrated out of the blood vessels and become macrophages in the tissues
3) They phagocytose material and produce a range of important cytokines
What are the 3 morphological features of chronic inflammation?
1) Infiltration with mononuclear cells (macrophages, plasma cells and lymphocytes)
2) Tissue destruction
3) Healing by fibrosis
What is meant by recruitment, proliferation and immobilisation of macrophages in chronic inflammation?
1) Recruitment - Monocytes enter damaged tissue and from endothelium of blood vessel
2) Proliferation - macrophages proliferate locally in damaged tissue
3) Immobilisation - of macrophages within tissues
What is a fibroma?
Fibrous tissue which arises from 1 cell line
What kind of cell induces the laying down of connective tissue in fibrosis?
Macrophages
What are histiocytic giant cells including function?
Form where material is indigestible to macrophages
Multinucleate giant cells with >100 nuclei
Develop when 2+ macrophages try to engulph the same particle
No known function, not phagocytic
Name 2 bacterial granulomatous diseases?
1) TB
2) Leprosy
Name a parasitic granulomatous disease?
Schistosomiasis
Name a fungal granulomatous disease?
Cryptococcus
Name 1 granulomatous disease caused by synthetic materials?
1) Silicosis
Name 2 granulomatous diseases with unknown causes?
1) Sarcoidosis
2) Crohn’s disease
What are the 2 concentric layers of cells found in an early granuloma?
Middle - macrophages
Edge - lymphocytes
What are the 3 concentric layers of cells found in a noncaseating epitheloid granuloma?
Middle - epithelioid macrophages and langerhan’s type giant cells
2nd layer - Lymphocytes and plasma cells
Outer layer - Fibroblasts producing collagen
What are the 4 concentric layers of cells found in a caseating epitheloid granuloma?
Middle - caseous necrosis
2nd layer - Epitheloid macrophages and langerhan’s type giant cells
3rd layer - lymphocytes, plasma cells
Outer layer - Fibroblasts producing collagen
What is the role of inflammation in MS?
plasma cells and T lymphocytes are seen in white matter where macrophages break down myelin
What is the role of inflammation post MI and in atherosclerosis?
1) Myocardial fibrosis pots MI
2) Inflammation makes an important contribution to development of atheroma
Macrophages adhere to the endothelium, migrate in intima and with T lymphocytes express cell adhesion molecules which recruit other cells, macrophages are also involved in processing the lipids that accumulate in plaques