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PathologyInflammation and Repair

Cardinal signs, stages, and harmful consequences of inflammation

THE CONTEXT
Inflammation produces recognizable external signs and proceeds through a sequence of defensive and reparative steps. Under some circumstances, the reaction itself causes disease.

Cardinal signs

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The five cardinal signs are heat (calor), redness (rubor), swelling (tumor), pain (dolor), and loss of function.
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These manifestations result from vascular changes and leukocyte recruitment and activation.

The five R’s

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The sequence begins with recognition of the offending agent, followed by recruitment of blood cells and proteins to the tissue site.
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Subsequent steps are removal of the offending agent, regulation of the reaction, and repair of injured tissue.

When inflammation causes disease

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Inflammatory responses to infection often cause local tissue damage and pain, but these consequences usually resolve as inflammation subsides, leaving little or no permanent damage.
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Disease can result when inflammation is directed against self tissues in autoimmune disease, occurs against usually harmless environmental substances in allergies, or persists excessively because microbes resist eradication, as with Mycobacterium tuberculosis.
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Abnormal inflammatory reactions underlie chronic diseases such as rheumatoid arthritis, asthma, and lung fibrosis.
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Inflammation may also contribute to atherosclerosis, type 2 diabetes, and Alzheimer disease.
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