The Low-Down on Inflammation From an HIV Doctor
August 25, 2015
When doctors discuss inflammation, we usually end up wildly waving our hands around as we talk. I like to call this the international sign language for inflammation -- it's the same no matter who you talk to and it really captures just how little we really understand about why inflammation happens and what its long-lasting effects can be.
Inflammation is the generic term for the body's response to injury. During injury, the immune system -- our body's defense system -- activates a complicated network of cells and chemical signals. Acute inflammation, immune activation that's rapid and self-limited, is essential for healing. But chronic inflammation, immune activation that continues even after the initial injury is gone, is problematic. Chronic inflammation is like a volume control knob on a stereo being stuck -- with the volume turned all the way up.
Knowing how acute inflammation works helps to understand chronic inflammation.
Here's what happens when you get a paper cut, for instance. Injured skin cells sliced open by the offending paper edge send out chemical SOS signals. These chemical messengers act locally, causing blood vessels near the wound to dilate and more blood to flow to the area. Chemical messengers also circulate in the blood to attract white blood cells -- the warrior cells of the immune system -- to the injured area. When the white blood cells arrive, they send out their own chemical signals, to create a cascading immune response to the injury. The end result of this process is healing. A blood clot is formed, scar tissue is laid down and infection is prevented. At the end of this process, other chemical messengers turn off the immune response leaving the immune system free to respond to the next injury.
Chronic inflammation happens when the immune system doesn't turn off after an injury or triggering event is over. We don't have a cohesive, comprehensive way to measure inflammation as a whole yet, but we can measure separate "inflammatory markers," or chemicals released by cells during the process of inflammation. Some of the main ones being studied right now include C-reactive protein (CRP), D-dimer, fibrinogen, Interleukin-6 (IL-6) and Interleukin-8 (IL-8); but there are many, many more.
Inflammation is linked to just about every bad thing that can happen to our body -- cancer, heart disease, liver and kidney failure, dementia and autoimmune disease (just to name a few). A few years ago, HIV specialists and researchers started talking about inflammation more and more. We noticed that people living with HIV -- even those successfully treated with combination antiretroviral therapy (ART) -- had higher levels of inflammation than HIV-negative people. And, even though our patients weren't getting opportunistic infections anymore, they still had higher rates of heart disease and non-HIV-related cancers higher than the general population.
This excerpt was cross-posted with the permission of BETAblog.org. Read the full article.
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