The immune system and ageing (in mice)
Reading a news feature from Nature, 7 May 2024: “Hacking the immune system could slow ageing — here’s how”.
With so many strands of research coming together, scientists are cautiously hopeful that the immune system will indeed prove to be a key lever in healthy ageing.
The immune system doesn’t work as well as you age. There are less immune cells circulating (and in different proportion) compared to youngsters. That’s bad for fighting infections, and also non-infectious illnesses including cancer.
Moreover, increasing numbers of immune cells become senescent, meaning that they stop replicating but don’t die.
Any cell in the body can become senescent, typically when damaged by a mutation. Once in this state, cells start to secrete inflammatory signals, flagging themselves for destruction. This is an important anticancer and wound-healing mechanism that works well in youth. But when too much damage accumulates with ageing — and immune cells themselves also become senescent — the mechanism breaks down. Senescent immune cells, attracted by the inflammatory signals from senescent tissue, secrete their own inflammatory molecules. So not only do they fail to clean up properly, but they also add to the inflammation that damages surrounding healthy tissue. The phenomenon is known as ‘inflammaging’.
Approaches to tackling this, in increasing order of difficulty (maybe):
- Remove of block senescent immune cells, via drugs.
- Boost the ability of the immune system, via drugs.
- Generate new immune cells via stem cells for transplants!
- Reprogram cells to un-do senescence, via epigenetic reprogramming.