PMI03-2013 Chronic Inflammation Flashcards
What is chronic inflammation?
The ongoing inflammatory response from unresolved acute inflammation
It can also arise de novo (by itself) if the causative agent only produces a mild inflammatory response
When does healing and tissue destruction take place in relation to each other in CI?
Tissue destruction takes place alongside healing and repair
What are common features of chronic inflammation?
Tissue destruction and ulceration
Inflammatory infiltrate is a mixture of macrophages, lymphocytes, plasma cells and some polymorphs
Production of new fibrous tissue through granulation tissue formation
What is the mechanism of chronic inflammation?
There is continued recruitment of macrophages and lymphocytes in the infected area
Lymphocytes and macrophages become activated and begin to proliferate at the site of infectio
How does a granuloma form?
In CI, activated macrophages collect to form a granuloma
These granulomas block out an agent that is resistant to destruction
What is a granuloma?
A collection of elongated macrophages (epithelioid cells) which surround a core of lymphocytes
What occurs during TB?
TB is a chronic granulomatous disease caused by Mycobacterium Tuberculosis
Myobacteria are ingested into macrophages
They promote a T cell response
As they are intracellular bacteria, they are protected from immunological attack and persist in tissues
What is the principle feature of TB?
Caseasting granuloma that is a dense mass of epithelioid cells, T lymphocytes, central caseous necrosis and Langerhans giant cells
What is TB hypersensitivity?
Intracellular mycobacteria within macrophages drive ongoing inflammation
This is mediated by a T cell response
Tissue damage is caused by the host cells own response. Bacteria drive the host to form fibrous tissue which causes the damage
What type of hypersensitivity reaction is TB?
Type IV
What is rheumatoid arthritis?
A chronic inflammatory disorder that affects the joints
How does rheumatoid arthritis occur?
An unknown stimulus triggers chronic inflammation of the joints
Fibrous repair occurs in response to tissue damage
Fibrous tissue remodelling and contraction occur
There is ankylosis and deformation of the joints
How does rheumatoid arthritis progress?
Forming granulation tissues at the edge of the synovial lining with extensive angiogenesis and enzymes causing tissue damage
What is the RA hypersensitivity?
If TNF-a release is stimulated by B cell products- it is type III Hypersensitivity
If TNF-a release is stimulated by T cell products such as IL-17- it is type IV hypersensitivity
What is another example of chronic inflammation?
Pulpitis
