Inflammation (Pathology)

Lung Inflammation (Wegener's Granulomatosis):

Basic Facts:

• Inflammation is a physiological response to tissue trauma or infection.
• Leukocytes are effector cells of the inflammatory response.
• Passage of leukocytes into tissues from the blood is heavily regulated.
• Early in inflammation there is recruitment of neutrophils to the involved tissue, with migration across endothelial cells and through the basement membrane.

Factors affecting neutrophil migration:

• Chemokine family peptides are believed to provide the chemotactic stimulus for neutrophils.
• Tumour necrosis factor alpha is essential for recruitment of flowing neutrophils to inflamed tissues.
• Neutrophil transit of the endothelial layer, however, is signalled by metabolism of the omega-6-polyunsaturated fatty acid (n-6-PUFA) arachidonic acid.
• The arachidonic acid is subsequently converted to prostaglandin D2 (PGD2) by cyclooxygenase (COX) enzymes.
• If the dietary n-3-PUFA, eicosapentaneoic acid (EPA) is used instead of n-6-PFA, so producing PGD3, then neutrophil migration across endothelial cells is inhibited.
• The mechanism of PGD3's action appears to be through antagonising binding at the neutrophil PGD2 receptor.

Clinical consequences:

• Inflammation plays a major role in the development of most diseases.
• NF-kB (nuclear transcription factor kappa beta) also has a significant role in diseases and inhibition (blocking) of NF-kB can also suppress inflammation.

Image Credits:
Wegener's granulomatosis - flickr by Pulmonary Pathology (cc)
Neutrophil recruitment by PLoS Biology article here.

Posted by ALCHEssMIST.
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