The good news, and bad news, of inflammation
Is the body's response to injury good for you, or is it bad? It depends. Following short-term injury, infection and exercise, inflammation is your friend. In chronic, low-dose form, it may be to blame for nearly all that ails us.
ROCHESTER, Minn. — Though the hospital treats them on separate floors, some of the most pressing health conditions of our time — whether that be diabetes, cardiovascular disease, cancer and Alzheimer's — share one thing in common.
The body's blood marker signaling the presence of inflammation happening somewhere — a compound known as C-Reactive Protein — is elevated in all of them.
Inflammation is all the rage these days. Interventions claiming to be "anti-inflammatory" can be found in cookbooks, magazines, sport drinks, as well as in mental health and exercise plans.
But our rising interest in the body's inflammatory machine suggests more than just marketing. The public is catching up with the science of inflammation.
Two forms of inflammation
A system designed to fight pathogens and repair tissues, inflammation operates in a window of function.
Like stress, when inflammation comes and goes, it keeps the body healthy, say experts in heart disease, sports medicine and rheumatic illness.
When it is stuck in the "on" position, inflammation can set the stage for all kinds of disease, however. As these conditions worsen, the body produces more inflammation.
"Simply put, inflammation is ... anything that irritates the tissues," said Dr. Stephen Kopecky, a preventive cardiologist at Mayo Clinic. He calls chronic inflammation "a malfunctioning system."
"When you're in the sun all day you're going to come away with sunburn, which is inflammation of your skin tissues. That happens in the body too, from anything that irritates our tissues."
Chemicals from chronic inflammation in one part of the body can travel elsewhere, he says, "irritating ... our arteries, our brain, our lungs and leading to problems."
"In the arteries, it's a heart attack. In the brain, it's Alzheimer's. In the colon or gut, it can be cancer."
Because it is chronic, inflammation in rheumatic disease "can be damaging to tissue and organs," said Dr. John Davis, rheumatologist and professor of medicine at Mayo Clinic.
Research suggests, in fact, that chronic inflammation is a factor in almost all that ails us. The list includes aging, insulin resistance, obesity, cardiovascular disease, cancer and even COVID-19.
And yet there remain times when inflammation helps.
"I think inflammation has gotten a bad reputation," said Dr. Edward Laskowski, professor of sports medicine at Mayo. "It really is a part of the body's natural response to healing."
"When a tissue gets injured — say you sprain an ankle — there is a rush of helpful substances that go into the area to help healing," Laskowski said.
Laskowski cites research showing that overuse injuries, for example, could be the result of interrupting the healing process of everyday inflammation following exercise.
This beneficial side of inflammation that follows injury became apparent last May, when an international team of researchers reported in the journal Science Translational Medicine that the use of common anti-inflammatory drugs "was associated with increased risk of persistent pain" in the low back.
Something about taking a pill to get rid of inflammation following an injury, the researchers learned, made low back pain stick around — which is the opposite of why you take a pill such as ibuprofen.
"It showed if we take them early, maybe we promote prolongation of that pain later," Laskowski said. "So maybe they are blocking some of those early healing pathways that are beneficial in the body."
Nor will ibuprofen-type drugs known as NSAIDs help systemic inflammation, Davis said.
"We don't think of NSAIDs as having disease-modifying properties," he said. "They are not generally considered to suppress chronic inflammation well enough to prevent damage."
Overall dietary quality likely contributes to the inflammatory state we're in. A diet that consistently causes blood glucose to spike, for example, can lead to insulin resistance.
Insulin resistance is believed to increase a protein known as FOXO1, which is followed by a spike in inflammatory cytokines, according to research from the University of Pittsburgh published in the journal Diabetes.
Because insulin resistance can lead to increased hunger and obesity, and because body fat releases chemicals that promote inflammation as well, the dietary pathway of inflammation can become bidirectional.
Inflammation even connects far-flung regions of the body. It's been known for years, for example, that periodontal disease releases infectious agents that trigger the release of inflammatory cytokines in the bloodstream.
Over time, these cytokines can irritate the endothelial cells lining the arteries. Once that happens, these arteries begin trapping proteins, forming plaque.
"People with gum disease (also known as periodontal disease) have two to three times the risk of having a heart attack, stroke, or other serious cardiovascular event," according to the publication Harvard Health .
And that's just one pathway to irritating the lining of the arteries.
Kopecky said that arteries have lining a single cell layer thick, and that "it is usually impermeable."
"Once something irritates the lining of the artery, it could be stress, it could be genes, it could be smoking, could be blood pressure, that lining is no longer impermeable," he said.
When it gets lodged in these irritations, cholesterol also creates inflammation in the arteries, which is the reasoning for lowering cholesterol through diet and medications.
According to a 2017 drug trial known as CANTOS , a study conducted by Brigham and Women’s Hospital cardiologist Dr. Paul Ridker, lowering inflammation may be at the center of why such medications offer benefit.
In any case, the story of disease in our time is clearly changing, moving toward one in which inflammation sits at the center of our health problems, with some beneficial processes feeding it, but also some bad ones as well.
NewsMD correspondent Viv Williams contributed to this report. Paul John Scott can be reached at email@example.com.