As Daniel Patrick Moynihan, an American sociologist, politician, and diplomat once said: “Everyone is entitled to his own opinion, but not his own facts”. And we wholeheartedly agree. A shared set of facts is the first step to building a better world with longevity for all. In that spirit, we are creating a series that covers 101 indisputable facts about ageing, health and longevity.
Inflammation is a defence mechanism that works in tandem with the rest of the immune system to protect the body against pathogens. Inflammation helps rouse the immune system to action, makes it easier for white blood cells to access the site of the infection, and also initiates the healing process once the infection is resolved. However, the signals that activate inflammation are never completely absent: low levels of inflammatory signals can still be detected in the blood and in tissues, even when no pathogens are present. This is often referred to as ‘background inflammation’.
During ageing, levels of background inflammation increase – this is sometimes called infalmmageing. Though inflammation is vital for protection against pathogens, a continuously elevated level of inflammation is problematic because inflammation damages the body’s own tissues and contributes to most age-related diseases. Three of the world’s most deadly chronic age-associated diseases – cardiovascular disease, cancer, and dementia – are driven or at least strongly associated with inflammation. Levels of some inflammatory molecules are predictive of all-cause mortality. For example among 80 year-olds, an increase in circulating IL-6 (interleukin-6) of 1 pg/ml was associated with a 13% increase in mortality within 6 years.
These increasing levels of inflammatory molecules originate from a variety of sources. Senescent cells (touched upon in fact #23) produce inflammatory signals, as does adipose tissue, which tends to increase with age. Inflammation occurs not just in response to the presence of pathogens, but also in response to cellular damage, which increases during ageing for many reasons that will be covered in future “facts”. The way in which the genetic code is packaged and read changes during ageing, which may alter the expression of inflammatory molecules. The ageing of the bone marrow, in which new blood cells are produced, leads to an increased production of inflammatory white cells at the expense of other types of immune cell. These are just some of the reasons for which chronic inflammation may increase with age.
Predicting death from tumour necrosis factor-alpha and interleukin-6 in 80-year-old people: https://dx.doi.org/10.1046%2Fj.1365-2249.2003.02137.x
Advancing age and insulin resistance: role of plasma tumor necrosis factor-α: https://doi.org/10.1152/ajpendo.1998.275.2.E294
Inflammageing: chronic inflammation in ageing, cardiovascular disease, and frailty: https://doi.org/10.1038/s41569-018-0064-2