The Aging Immune System
We’re living longer but our healthy lifespan is lagging. Inflammation is a prime suspect.
We are an aging society with life expectancy increasing at a steady rate – 2 years per decade. Put another way, a child born today has a life expectancy of five hours more than one born yesterday! This is a great testament to the success of public health measures such as vaccination, and modern medicines such as anti-hypertensives which reduce deaths from heart disease. However, even though we are living longer our healthy lifespan is only increasing 1.7 years per decade. In other words the average adult spends the last 15-20 years of their life in poor health. The challenge now for science and society is to reduce age-related diseases so that old age is enjoyed and not endured. We need a long life and a short death!
In recent years our understanding of why and how we age has increased dramatically and it has become clear that one of the factors that underlies many age-related diseases such as heart disease, physical frailty and even cancer and dementia, is inflammation. Inflammation is the body’s way of protecting us against infections and to help us repair tissue when it is damaged. In these situations it is caused by the cells of the immune system which release molecules (cytokines) which cause the inflammation and alert the rest of the immune system to the presence of an infection or of a wound that needs healing. As we get older there is an increase in these cytokines leading to a different kind of inflammation, termed Inflammageing, which is detrimental to health as it lasts for years.
Inflammageing is caused by many factors including:
- Increased fat in the body (fat can produce the inflammation cytokines)
- Old cells, called senescent cells, which also produce inflammation cytokines
- The aged immune system which can no longer dampen down inflammation and actually increases inflammation by releasing cytokines even when there is no infection present
- Reduced physical activity as we age – muscles that don’t move enough produce more inflammation cytokines
The good news is that we can do something about inflammageing. We can use a pharmacological approach, such as taking e statins to lower cholesterol, which also reduces inflammageing. We can also improve our lifestyle. Older adults who stay physically active and have healthy body weights show very low levels of inflammation cytokines. Hippocrates in 400 BC said that “exercise is man’s best medicine.” – Turns out he was right!