Chronic inflammation Flashcards
What is Chronic Inflammation?
Inflammation of a prolonged duration
When does chronic inflammation occur?
- When the acute inflammatory response fails to remove the stimulus
- When there are repeated episodes of acute inflammation
- The stimulus or microbe has unique biochemical characteristics or virulence factors which incite chronic inflammation
What are some mechanisms of chronic inflammation?
Persistent or resistant infections
unresponsiveness to phagocytosis or enzymatic breakdown
autoimmunity
What maintains the chronic inflammatory response?
infiltration and activation of lymphocytes, macrophages, plasma cells and multinucleated giant cells
Tissue destruction
proliferation of fibroblasts and deposition of collagen
Initiation of wound healing
What are the benefits of chronic inflammation?
walling off/ getting rid of the inciting substance
What are the harmful aspects of chronic inflammation?
The space occupying lesions can be formed resulting in
* displacement of the original tissue
* Loss of function
* Clinical sigficance that is determined by the size, tissue and the position
What is granulomatous inflammation?
a distinct type of chronic inflammation dominated by cells of the monocyte-macrophage system and multinucleated giant cells
Why do birds and reptiles struggle to convert neutrophils into pus?
Because they lack myeloperoxidase in their neutrophils
How are the macrophages of granulomatous inflammation dispersed?
either dispersed as sheets at random within the tissue
or arranged in discrete masses/nodules
How do nodular/tuberculoid granulomas develop?
they develop with a T helper lymphocyte type 1 response
What is the difference between caseating and non-caseating granulomas?
Caseating means they have a central core of necrotic debris
What is the general appearance of tuberculoid granulomas?
Round/Oval
May form a fibrous capsule
What are some of the causes of tuberculoid granulomas?
Myobacterium bovis/ Myobacterium tuberculosis
Deep fungal infections
How do lepromatous granulomas develop?
they develop with a T helper lymphocyte type 2 response
What do lepromatous granulomas look like?
they are poorly delineated, forming sheets within the tissue
composed of numerous macrophages and few lymphocytes/plasma cells
What are some of the causes of lepromatous granulomas?
Mycobacterium avium
Mycobacterium lapraemurium
What are eosinophillic granulomas characterised by?
dense infiltration of eosinophils, macrophages and varying numbers of lymphocytes/palsma
When does pyogranulomatous inflammation occur?
When the inciting stimulus continues to elicit an acute inflammatory response
What are the cellular constituents of a pyogranulomatous inflammation?
same as teh granulomatous inflammation but with neutrophils, plasma proteins and fibrin
What is a pyogranuloma?
a ndoular granuloma with a central area of neutrophils
What is a Lymphoplasmacytic inflammation?
Common type of inflammation often seen at the early stages of chronic inflammation
also seen in response to specific microbes or in response to antigenic inflammation
What occurs to the macrophages once they enter the tissues?
They become activated by cytokines (e.g IL-4 or IFN-7 from T lymphocytes)
What two roles do activated macrophages have?
- Inflammation/ tissue injury (e.g removing NO, ROS, Proteases, Cytokines…)
- Repair (Growth factors, Remodelling)
What are the two different classes of activated macrophage?
- Classically activated macrophage
- Alternatively activated macrophage
What are the 4 types of granulomatous inflammtion?
- Diffuse or lepromatous (dispersed as sheets at random within the tissue)
- Tuberculoid or nodular (discrete masses)
What is the difference between lymphoplasmacytic and lymphohistiocytic inflammation
lymphoplasmacytic- composed of lymphocytes and plasma cells
lymphohistiocytic- when the lymphocytes and macrophages predominate over plasma cells
When is lymphoplasmacytic inflammation most commonly seen?
In the early stages of chronic inflammation
What are the functions of classically activated macrophages?
- Microbicidial actions
- phagocytosis
- pathological inflammation
What activates classically-activated macrophages?
pro-inflammatory signals
microbial products
What is the function of alternatively activated macrophages?
- Anti-inflammatory effects
- Wound repair
What stimulates alternatively activated macrophages?
Induced by anti-inflammatory signals
What are eosinophillic granulomas secondary to?
They are secondary to parasitic infections
