Is the 21st century turning against us?
Genetic, environmental and lifestyle factors all play a role in inflammatory diseases
Why do we hear of more and more diseases that are “inflammatory” by nature? There are two reasons, says Professor Jennifer Stow from IMB.
“One is that we have an ageing population, and ageing is associated with more chronic disease,” she says.
The second reason is our environment. “We live in an inflammatory world that we’ve created for ourselves,” she says.
Inflammation is a very ancient response designed to be triggered by things such as pathogens or injury.
But now we assault our bodies with all sorts of things – air pollution, cigarette smoke, food additives, stress, alcohol and many more.
All of these can act as environmental danger signals that trigger inflammation, often subtly in the background.
Environmental factors, including dietary choices, can lead to so-called “lifestyle diseases”, such as type 2 diabetes, where chronic inflammation is a major factor.
And as IMB’s Dr Larisa Labzin explains, the problem is made worse when the immune system doesn’t receive the signal that the threat has been neutralised, and the immune system can turn off. Then you get more and more inflammation.
“In the case of an infection, the inflammatory and immune responses to pathogens such as bacteria or viruses enable them to be killed and degraded,” she says.
“But if it’s against something inert that’s made its way into the body – silica particles or asbestos fibres, for example – you’re mounting an immune response against something that can’t really be destroyed by our immune system. So, our usual weapons are useless against them."
“That’s when you get chronic inflammation that’s not being turned off.”
As a result, the body itself becomes subject to collateral damage.
There is a similar outcome with autoimmune diseases, although for different reasons.
The root causes of many of these diseases, which include rheumatoid arthritis, Addison’s disease, lupus and type 1 diabetes, are not yet completely understood, but the mechanics are well established.
Instead of attacking bacteria, viruses or other sources of infection, the immune system attacks healthy organs and tissues. For example, in rheumatoid arthritis, our immune cells destroy the insulin-producing cells in the pancreas.
“This abnormal response also drives constant inflammation, further contributing to disease processes,” says Professor Matt Sweet, an immune system specialist at IMB.
Chronic inflammation is rapidly becoming synonymous with disease in the 21st century.
We assault our bodies with all sorts of things that it interprets as dangerous – air pollution, cigarette smoke, food additives, stress.
Autoimmune or inflammatory?
- Inflammatory diseases are not the same as autoimmune diseases, although the dividing line is often blurred.
- The difference lies in the immune system. Inflammatory diseases are those in which your innate immune system – the first line of defence against infection – launches an inflammatory response that does not stop.
- In autoimmune diseases, your adaptive immune system attacks your body as if it were an invader. That can lead to inflammation and inflammation-related conditions.
It’s a dangerous world
Some of the environmental inflammatory factors we face:
Studies have found that increased exposure to fine particulate matter in air pollution is associated with elevated inflammation markers in the blood. This inflammation can contribute to the incidence of heart attack and stroke.
Smoking is a major factor in a range of inflammatory diseases. Not only is it linked to cardiovascular and respiratory diseases, but also to increased levels of inflammatory markers and accelerated atherosclerosis. It is a major risk factor for rheumatoid arthritis. It increases the risk of developing Crohn’s disease and may aggravate its course.
Asbestos exposure is the cause of a range of lung diseases. While the biology of this is complex, exposure to asbestos leads to chronic inflammation and scarring of the connective tissue in the lungs.
Stress triggers the production of cortisol, the flight-or-flight stress hormone that plays a role in inflammation, and can interfere with the body’s ability to control it. Physical stress, such as a sporting injury, can also trigger excessive inflammation, sometimes years later.
Your body can determine that certain chemicals are harmful and launch an immune and inflammatory response to them, whether you are exposed through the air, by touching them or through a wound.