If you’ve ever twisted your knee, cut your finger, or been stung by an insect, you have firsthand experience with inflammation. The familiar sensations of pain, redness, swelling, and heat that result from an injury or infection are hallmarks of the inflammatory process. Inflammation represents an essential survival mechanism that helps the body fight off hostile microbes and repair damaged tissue. Yet there is another side of inflammation that can be harmful rather than helpful to human health. There’s evidence that inflammation, promoted in part by such factors as obesity, smoking, and a sedentary lifestyle, contributes to a variety of diseases.
There are two forms of inflammation: acute and chronic.
Acute inflammation comes on rapidly, usually within minutes, but is generally short-lived. Many of the mechanisms that spring into action to destroy invading microbes switch gears to cart away dead cells and repair damaged ones. This cycle returns the affected area to a state of balance, and inflammation dissipates within a few hours or days.
Chronic inflammation often begins with the same cellular response, but morphs into a lingering state that persists for months or years when the immune system response fails to eliminate the problem. Alternatively, the inflammation may stay active even after the initial threat has been eliminated. In other cases, low-level inflammation becomes activated even when there is no apparent injury or disease. Unchecked, the immune system prompts white blood cells to attack nearby healthy tissues and organs, setting up a chronic inflammatory process that plays a central role in some of the most challenging diseases of our time, including rheumatoid arthritis, cancer, heart disease, diabetes, asthma, and even Alzheimer’s.
This report will examine the role that chronic inflammation plays in these conditions, and will also provide information on the breadth of drugs currently available to alleviate symptoms. Drug choices range from simple aspirin, a nonsteroidal anti-inflammatory drug that’s been available for more than a century, to disease-modifying drugs and so-called biologics that promise more targeted treatments.
Lifestyle choices, diet, and even family history play a role in the diseases and conditions brought about by chronic inflammation, and each will be discussed in turn. An understanding of how chronic inflammation influences health can lead to a better conversation between you and your doctor, and speed treatment and prevention.
Prepared by the editors of Harvard Health Publishing in consultation Robert H. Shmerling, MD, Corresponding Member of the Faculty of Medicine, Harvard Medical School, Division of Rheumatology, Beth Israel Deaconess Medical Center Senior Editor, Harvard Health Publishing 53 pages (2020)