7. Chronic Inflammation Flashcards
What is the purpose of inflammation?
- remove the cause of injury
- remove necrosis that has occurred due to injury
- initiate repair of the tissues
How can inflammation be a bad thing?
- can damage nearby tissues and be destructive
- can be inappropriate (chronic inflammatory diseases and autoimmune diseases)
What are 4 main features of ACUTE inflammation?
- fast onset (mins-hours)
- neutrophil polymorphs
- prominent signs
- mild, self-limiting tissue injury
What are the 4 main features of CHRONIC inflammation?
- slow onset (days)
- macrophages, lymphocytes
- subtle signs
- severe, progressive
Neutrophil polymorph is the main cell in which type of inflammation?
Acute
These neutrophils cause phagocytosis of invading organisms
Which type of inflammation creates prominent signs?
Acute
redness, heat etc
Which type of inflammation has a slow onset?
Chronic
Can take days or even weeks or months in the case of autoimmune diseases
In which type of inflammation are the signs most likely to be missed?
Chronic
Can get progressive and severe disease before the signs are picked up on (the signs are subtle)
Why might autoimmune diseases go unnoticed?
Signs of chronic inflammation are often subtle and progressive and autoimmune diseases often mimic other diseases
Summarise ACUTE inflammation
initial reaction to cell injury
vessels dilates and leak, protein-rich exudate
possible outcomes = resolution, suppuration, organisation into scars, chronic inflammation
What are the dominant cells in CHRONIC inflammation?
lymphocytes, plasma cells, macrophages
What is particularly abundant in chronic inflammation?
Granulation and scar tissue
Is chronic inflammation primary or secondary?
Usually primary but can be sequential from acute
But chronic is not the normal response to acute - normally acute resolves and forms pus etc.
What causes chronic inflammation?
- some infections
- endogenous material
- some autoimmune
- exogenous material
- primary granulomatous disease
Give examples of infections which can cause chronic inflammation?
TB, leprosy, some viruses
Give examples of endogenous material that can cause chronic inflammation
- necrotic adipose tissue
- uric acid crystals
Give examples of exogenous material that can cause chronic inflammation
- asbestos fibres
- sutures
- implanted prostheses
Define exogenous
External origin (outside of the body)
Give examples of autoimmune diseases
rheumatoid arthritis, SLE, pernicious anaemia
What is pernicious anaemia?
An autoimmune disease
Autoantibodies to intrinsic factor and gastric parietal cells lead to no B12 absorption and anaemia results
Give two examples of granulomatous disease
Crohn’s disease
Sarcoidosis
What is a granuloma?
A collection of inflammatory cells
A collection of immune cells called histiocytes
Describe sarcoidosis
granulomas collect in many organs, mainly the lungs and lymph nodes within the chest cavity
Viewed as an immune reaction to usually an infection
In which type of acute inflammation, is progression to chronic most common?
suppurative (pus forming) acute inflammation
Describe the progression from acute to chronic inflammation?
Pus can form an abscess, if the abscess becomes deep enough the walls thicken and become filled with granulation and fibrous tissue - this make a permanent cavity for pus to sit in - this makes it more difficult for the immune system to reach - if this happens recurrently it can lead to chronic inflammation
What is an abscess?
A painful collection of pus
What is granulation tissue?
Repair/healing tissue
New connective tissue and tiny blood vessels that form on the surfaces of a wound during the healing process
What is chronic cholecystitis?
Gall bladder inflammation usually doe to stones
Stones persist - thickened gall bladder wall - fibrous tissue - chronic cholecystitis - chronic pain - may need gall bladder removal
What are the main morphological features of chronic inflammation?
- infiltration with mononuclear cells (macrophages, lymphocytes, plasma cells)
- tissue destruction
- healing by fibrosis
Give examples of mononuclear cells
- macrophages
- lymphocytes
- plasma cells
They are involved in chronic inflammation
What are the macroscopic features of chronic inflammation?
Dependent on the actual disease
Define ‘caseating’
Necrosis with conversion of damaged tissue into a soft substance (cheesy necrosis, soft damaged tissue)
What are the macroscopic features of chronic peptic ulcer? (a type of chronic inflammation)
- mucosal breach
- granulation tissue at the base
- fibrous tissue extends through the wall
What are the macroscopic features of chronic abscess cavity? (a type of chronic inflammation)
Pus becomes encapsulated into fibrous tissue that immune system has difficulty reaching
What is Crohn’s disease?
A chronic inflammatory disease of the intestines, characterise why non-caseating granulomas
Are the granulomas in Crohn’s caseating or non-caseating?
Non-caseating
Are the granulomas in TB caseating or non-caseating?
Caseating
Is fibrosis characteristic of chronic inflammation?
Yes, fibrosis is prominent once the inflammatory infiltrate has stopped
What are the main microscopic features of chronic inflammation?
- cellular infiltrate of lymphocytes, plasma cells and macrophages
- production of new fibrous tissue from granulation tissue
- exudation of fluid is NOT prominent (like it is with ACUTE inflammation)
Is exudate prominent in acute or chronic inflammation?
ACUTE inflammation only
What is characteristic of macrophages microscopically?
Irregular border
What is characteristic of lymphocytes microscopically?
Tiny dark cells
How do plasma cells look different from lymphocytes microscopically?
Plasma cells are bigger than lymphocytes
What are the two types of lymphocytes involved in chronic inflammation?
- B lymphocytes
- T lymphocytes
B cells and T cells are lymphocytes involved in chronic inflammation? What do T cells do?
Produce cytokines
B cells and T cells are lymphocytes involved in chronic inflammation? What do B cells do?
Become plasma cells which produce antibodies