Short answers, pulled from the story.
The five cardinal signs of inflammation are heat (calor), pain (dolor), redness (rubor), swelling (tumor), and loss of function (functio laesa). The first four were described by Celsus around 30 BC; the fifth was added later, attributed variously to Galen, Thomas Sydenham, or Rudolf Virchow.
Acute inflammation is a short-term response lasting a few minutes to days, driven primarily by neutrophils and granulocytes, that clears the triggering stimulus and resolves on its own. Chronic inflammation persists for months or years, shifts toward macrophages and lymphocytes, and is associated with diseases including atherosclerosis, diabetes, and osteoarthritis.
Rudolf Virchow proposed in 1863 that cancer originates at sites of chronic inflammation. As of 2012, chronic inflammation was estimated to contribute to approximately 15 to 25 percent of human cancers. Reactive oxygen and nitrogen species produced during prolonged inflammation inflict more than 20 types of DNA damage, leading to mutations and epigenetic changes that can drive cancer development.
Chronic inflammation drives CD4 T-cell depletion and immune dysfunction in HIV infection, even after effective antiretroviral therapy suppresses viral replication. The mechanism involves caspase-1-mediated pyroptosis, a highly inflammatory form of programmed cell death, which creates a feed-forward cycle that sustains inflammation and accelerates disease progression toward AIDS.
A 2019 meta-analysis found that chronic inflammation is associated with a 30 percent increased risk of developing major depressive disorder. Clinical trials have shown that anti-inflammatory medicines taken alongside antidepressants improve symptoms and increase the proportion of patients who respond to treatment.
Resolution begins within hours of an inflammatory response starting, when granulocytes trigger a chemical switch from prostaglandins and leukotrienes to lipoxins, which initiate a shutdown sequence. Omega-3 polyunsaturated fatty acids contribute to the biosynthesis of resolvins and protectins, accelerating neutrophil apoptosis and clearance, after which macrophages exit through the lymphatic system.