Chronic Inflammation

Question 1

What is chronic inflammation?

Answer 1

Chronic inflammation is a response of prolonged duration (weeks or months) in which inflammation, tissue injury, and attempts at repair co-exist, in varying combinations.
- Some forms of chronic inflammation may be important in the pathogenesis of diseases that are not conventionally thought of as inflammatory disorders, such as Alzheimer’s, Metabolic Syndrome, and Type 2 Diabetes.

Question 2

There are three major causes of chronic inflammation, describe them shortly.

Answer 2

• Persistent Infections by microorganisms that are difficult to eradicate, such as mycobacteria and other microbes. associated with granulomatous reaction.
• Hypersensitivity Diseases - chronic inflammation plays an important role in such disorders for example autoimmune disorders (rheumatoid arthritis, multiple sclerosis, etc.) or allergies.
• often associated with fibrosis.
• Prolonged exposure to toxic agents, either endogenous or exogenous.
• For example, Silicosis is a chronic inflammatory lung disease caused by prolonged exposure to inhaled silica particles.
• Atherosclerosis is thought to be a chronic inflammatory process also due to the participation of overproduced endogenous substances such as cholesterol and lipids.

Question 3

What are the morphologic features of chronic inflammation?

Answer 3

• Infiltration WITH mononuclear cells.
• Tissue Destruction
• Attempts at healing by connective tissue replacement of damaged tissue: Angiogenesis & Fibrosis.

Question 4

Which cytokine is particularly involved in activating macrophages to the M1 mode (Classical activation)?

Answer 4

IFN-gamma (PAMPS/DAMPS also)

Question 5

Which cytokines are particularly involved in activating macrophages to the M2 mode (Alternative activation)?

Answer 5

IL-4, IL-13

Question 6

Which cytokines secreted by M2 activated macrophage?

Answer 6

• IL-10, TGF-beta for anti-inflammation.

- Growth factors (and TGF-beta) for repair and fibrosis.

Question 7

Which cytokines secreted by M1 activated macrophage?

Answer 7

• IL-1, TNF, IL-12, IL-23, and chemokines for INFLAMMATION.

- ROS, NO, and lysosomal enzymes for killing microbes.

Question 8

There are two types of granulomas, what are they?

Answer 8

• Foreign Body Granulomas.

- Immune Granulomas.

Question 9

What are epithelioid cells?

Answer 9

Activated macrophages that have been developed abundant of cytoplasm and begin to resemble epithelial cells. associated with granulomas.

Question 10

What are giant cells?

Answer 10

Literally - Giant cells formed by the fusion of few macrophages.

Question 11

What is the most obvious difference between foreign body granuloma and immune granuloma?

Answer 11

• The participation of T-lymphocytes. (which is seen in immune granulomas - “crosstalk” between T cells and macrophages, IL-2 present)